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         Climatic data decoding




               Hussain Majid




                   -i-
                                  ABSTRACT
        Climatic parameters strongly influence plume behavior in the atmosphere
and hence are important while studying its behavior in the atmosphere. Real time
Meteorological data for the whole world is available on the internet and it can be
used in radionuclide dispersion calculations. The data available on the internet is
in coded form and has to be decoded before use. This report includes
explanations of different weather parameters used in the dispersion calculation
and the method of data decoding with examples. Introduction of some of the
important meteorological organizations of various countries and that of Pakistan
Meteorological Department have also been included at the end of this report.




                                     - ii -
                                            Table of Contents

    ABSTRACT ........................................................................................................ i
    Table of Contents.............................................................................................. iii
    List of Tables.....................................................................................................vi
    List of Figures .................................................................................................. vii
1      INTRODUCTION ........................................................................................... 1
2      THE ATMOSPHERE ..................................................................................... 2
    2.1 Atmospheric Layers .................................................................................... 2
3      WEATHER AND CLIMATE ........................................................................... 4
    3.1 The Elements of Weather and Climate ....................................................... 4
       3.1.1        Rainfall ............................................................................................ 4
       3.1.2        Pressure .......................................................................................... 6
       3.1.3        Temperature ................................................................................... 7
       3.1.4        Humidity .......................................................................................... 8
       3.1.5        Winds .............................................................................................. 9
       3.1.6        Clouds ............................................................................................. 9
          3.1.6.1 Classification of clouds .............................................................. 10
       3.1.7        Visibility ......................................................................................... 15
4      ATMOSPHERIC DISPERSION ................................................................... 16
5      TURBULENCE OF THE ATMOSPHERE .................................................... 16
6      INDICATOR OF TURBULENCE ................................................................. 17
    6.1 Temperature Lapse Rate .......................................................................... 17
       6.1.1        Adiabatic Condition ....................................................................... 18
       6.1.2        Super Adiabatic Condition ............................................................. 19
       6.1.3        Stable Condition ............................................................................ 19
       6.1.4        Inversions ...................................................................................... 20
       6.1.5        Isothermal Condition ..................................................................... 20
    6.2 Wind Direction Fluctuation ........................................................................ 21
    6.3 Insolation, Cloudiness and Wind Speed.................................................... 21
7      WEATHER OBSERVATIONS ..................................................................... 21
8      SURFACE OBSERVATIONS ...................................................................... 22


                                                       - iii -
    8.1 Equipment Used ....................................................................................... 22
    8.2 Code Classification ................................................................................... 25
       8.2.1        Section-0 ....................................................................................... 25
       8.2.2        Section-1 ....................................................................................... 25
       8.2.3        Section-2 ....................................................................................... 25
       8.2.4        Section-3 ....................................................................................... 25
       8.2.5        Section-4 ....................................................................................... 25
       8.2.6        Section-5 ....................................................................................... 25
9      UPPER WIND (PILOT) OBSERVATIONS................................................... 26
    9.1 Instruments Used ...................................................................................... 27
    9.2 Code Classification ................................................................................... 27
       9.2.1        Part-A ............................................................................................ 27
       9.2.2        Part-B ............................................................................................ 28
       9.2.3        Part-C............................................................................................ 28
       9.2.4        Part-D............................................................................................ 28
10        ‘TEMPS’ OBSERVATIONS...................................................................... 29
    10.1 Equipment Used ..................................................................................... 29
    10.2 Code Classification ................................................................................. 29
       10.2.1       Part-A ............................................................................................ 29
       10.2.2       Part-B ............................................................................................ 30
       10.2.3       Part-C............................................................................................ 31
       10.2.4       Part-D............................................................................................ 31
11        WEATHER CHARTS ............................................................................... 31
    11.1 Surface Chart .......................................................................................... 31
    11.2 Upper Air Chart ....................................................................................... 31
    11.3 “TEMPS” Chart ....................................................................................... 33
12        METEOROLOGICAL ORGANIZATIONS................................................. 33
    12.1 National Oceanic & Atmospheric Administration ..................................... 34
    12.2 Met Office................................................................................................ 34
    12.3 Islamic Republic of Iran Meteorological Organization ............................. 35
    12.4 Turkish State Meteorological Service ...................................................... 35



                                                      - iv -
   12.5 China Meteorological Administration ....................................................... 35
   12.6 India Meteorological Department ............................................................ 36
   12.7 World Meteorological Organization ......................................................... 36
      12.7.1       World Weather Watch ................................................................... 37
13       PAKISTAN METEOROLOGICAL DEPARTMENT (PMD)........................ 39
   13.1 Services .................................................................................................. 40
14       CONCLUSIONS ...................................................................................... 43
References ......................................................................................................... 44




                                                      -v-
                                               List of Tables

Table 1: Gaseous Contents of Air......................................................................... 2
Table 2: Atmospheric Layers. ............................................................................... 2
Table 3: Extreme Rain Falls Recorded In Major Cities of Pakistan During ........... 5
Table 4: Extreme Pressures Recorded In Major Cities of Pakistan ...................... 6
Table 5: Extreme Temperatures Recorded in Major Cities of Pakistan During Last
      50 Years. ....................................................................................................... 8
Table 6: Extreme Relative Humidity (RH) Recorded In Major Cities..................... 8
Table 7: The Beaufort Wind Scale. ....................................................................... 9
Table 8: Example of Synoptic Data Decoding. ................................................... 26
Table 9: Code Classification of PILOT Code. ..................................................... 27
Table 10: Example of PILOT Data Decoding. ..................................................... 28
Table 11: Code Classification of ‘TEMPS’ Code................................................. 29
Table 12: Example of ‘TEMPS’ Data Decoding. ................................................. 30
Table 13: World Weather Observation System................................................... 38




                                                      - vi -
                                            List of Figures
Figure 1: Atmospheric layers starting from the earth’s surface. ............................ 3
Figure 2: Atmospheric layers vs. altitude. ............................................................. 3
Figure 3: Schematic of the global climate system................................................. 4
Figure 4: Isohyets showing annual normal rainfall in Pakistan. ............................ 5
Figure 5: Isotherm plot showing annual normal temperature in Pakistan. ............ 7
Figure 6: Cirrus clouds. ...................................................................................... 11
Figure 7: Cirrocumulus clouds. ........................................................................... 11
Figure 8: Cirrostratus clouds............................................................................... 11
Figure 9: Altocumulus clouds.............................................................................. 12
Figure 10: Altostratus clouds. ............................................................................. 12
Figure 11: Stratocumulus clouds. ....................................................................... 13
Figure 12: Stratus clouds. ................................................................................... 13
Figure 13: Nimbostratus clouds. ......................................................................... 13
Figure 14: Cumulus clouds. ................................................................................ 14
Figure 15: Cumulonimbus clouds. ...................................................................... 14
Figure 16: Low-level temperature distribution in the atmosphere. ...................... 17
Figure 17: Movement of a parcel of air in superadiabatic profile. ....................... 18
Figure 18: Movement of parcel of air in inversion profile. ................................... 20
Figure 19: The world time zones. ....................................................................... 22
Figure 20: Wind vanes. ....................................................................................... 22
Figure 21: Stevenson screens. ........................................................................... 23
Figure 22: Wind anemometers. .......................................................................... 23
Figure 23: Mercury barometers. ......................................................................... 24
Figure 24: Self recording rain gauges................................................................. 24
Figure 25: Pilot balloon being sent for collection of upper air data. .................... 27
Figure 26: Surface chart showing isobars, low/high pressure and trough. ......... 32
Figure 27: Upper Air (PILOT) charts showing wind direction and speed. ........... 32
Figure 28: TEMPS chart showing wind direction and speed. ............................. 33
Figure 29: World weather watch meteorological satellite network. ..................... 39
Figure 30: Meteorological observatory station network in Pakistan....................... 42


                                                   - vii -
1 INTRODUCTION

           Mankind has always been affected by weather and has been curiously
involved in collecting and analyzing various weather parameters for its interest.
All of the parameters such as temperature, pressure, wind direction/speed and
humidity affect the release of radioactivity from nuclear facilities to the
atmosphere. It is necessary to be able to calculate doses to the public and the
impact to the environment from such releases. Such computations also play an
important role in determining the acceptability of a proposed nuclear facility
location and safe operation [1].

       To do such type of calculations it is necessary to have real time weather
data for the study of plume behavior. For this purpose the Directorate of Safety
has gathered some information about meteorological observations from Pakistan
Meteorological Department.

   Meteorological observations are of three different types:
           Surface observations
           Pilot observations
           Temperature and Pressure (TEMPS) observation

           The Meteorological data is presently manually plotted on different
weather charts and analyzed by forecasters. The plotted charts and other related
information help the forecasters to make weather forecast.

           Real time meteorological data can be downloaded from the website. The
data is coded in World Meteorological Organization (WMO) format and the
Directorate of Safety has developed the capability to decode the data.




                                      -1-
2 THE ATMOSPHERE
       The atmosphere is made up of gases and vapours, and receives incoming
solar energy from the sun giving rise to what is called climate. We actually live at
the bottom of this layer of atmosphere where the air is densest. Higher up, the air
thins out and about 966 Km above sea level it is estimated as the limit of the
atmosphere. From analysis taken in different parts of the earth, it is found that
the lower part of the atmosphere contains the following (table1) consistent
proportion of gases.
                        Table 1: Gaseous Contents of Air.

                        Gaseous Contents of Air          Percentage

                       Nitrogen                               78
                       Oxygen                                 21
                       Carbon dioxide                        0.03

                       Argon, Helium etc                     0.07

2.1 Atmospheric Layers
       The gaseous layers into which the earth’s atmosphere can be divided
according to the change in physical properties and spatially temperature are
called Atmospheric Layers. The altitude figures are given in table 2 and shown in
figure 1.
                          Table 2: Atmospheric Layers.

                                        Distance from          Temperature
       Sr. No.         Layers
                                           Surface              Variation

            1.   Troposphere            Up to 10 Km          25o to -50oC

            2.   Stratosphere           10 to 40 Km          -50o to 0o

            3.   Ozone Layer            40 to 45 km          Constant at 0oC

            4.   Mesosphere             45 to 85 Km          0o to -100oC

            5.   Thermosphere           85 to 400 Km         -100oC to infinity

            6.   Exosphere              Above 400 Km         Up to Infinity



                                      -2-
                                                                           Exposphere
                                                                         (Above 400 Km)
                                                                           Thermosphere
                                                                           (85 to 400 Km)
                                                                           Mesosphere
                                                                           (45 to 85 Km)
                                                                           Ozone Layer
                                                                           (40 to 45 Km)
                                                                           Stratosphere
                                                #
                                                                           (10 to 40 Km)
                                                                               Troposphere
                                                                               (Up to 10 Km)

                                                                                   Earth




      Figure 1: Atmospheric Layers starting From the Earth’s Surface.

                                                    Exposphere

                160


                140


                120
                                                    Thermosphere
Altitude (Km)




                100


                80
                                                    Mesosphere
                60

                                                    Ozone Layer
                40
                                                    Stratosphere
                20

                                                    Troposphere
                 0
                      -100      -50         0            50        100   150
                                                     o
                                      Temperature( C)

                        Figure 2: Atmospheric Layers vs. Altitude.


                                          -3-
3    WEATHER AND CLIMATE
        Normally people don’t differentiate between weather and climate; however
the two words actually have different meanings. Climate means an average
atmospheric condition of an area over a considerable time. For climatic averages, a
minimum period of 35 years is desirable. The degree of variability in the climate or
weather of a country also differs. The climate of temperate latitude is far more
variable then that of the tropics. Weather describes the prevailing atmospheric
conditions of a certain place at a certain time. It is never static, and can not be
generalized. In a certain country weather can change tremendously. It may be
sunny in one part of the district but raining heavily in another part. So, weather can
change haphazardly at any time. Global climatic system is shown in figure 3.




        Figure 3: Schematic of the Global Climate System.

3.1 The Elements of Weather and Climate

        To collect various climatic data to prepare maps and charts of them, the
following elements of climate are normally observed and measured by weather
instruments.

3.1.1    Rainfall

         Rainfall including other forms of precipitation (snow, sleet and hail) is
always measured by a metal instrument called a rain gauge. The rain fall is


                                       -4-
measured in units of millimeters. Twenty five mm (an inch) of rainfall means the
amount of water that would cover the ground to a depth of 25 mm, (1 inch)
provided none is evaporated, drained off or percolates away [2].

       Table 3: Extreme Rain Falls Recorded in Major Cities of Pakistan During
                     Last 50 Years (1953-2002).

                City                    Minimum Rainfall                                    Maximum Rainfall
                                              (mm)                                               (mm)
        Islamabad                       91.2 (November)                                       743.3 (July)
        Lahore                          77.9 (November)                                         825.5 (August)
        Karachi                               33.3 (May)                                             429.3 (July)
        Peshawar                              55.4 (June)                                       280.2 9 (August)
        Quetta                                19.2 (June)                                       189.2 (February)
       Data from PMD Website.10

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Figure 4: Isohyets Showing Annual Normal Rainfall in Pakistan. (Data from PMD
Website.10)


                                                        -5-
        For meteorological recordings, a rainy day is reckoned as a period of 24
hours with at least 0.25 mm (0.01 inch) or more rain being recorded. If the mount
exceeds 1 mm (0.04 inch) it is considered a wet day. Extreme rain falls recorded
in Pakistan during 50 years (1952-2002) is shown in table 3. The mean annual
rainfall is obtained from the averages of annual rainfall taken over a long period
of say 35 years. For plotting in rainfall maps, places having the same mean
annual rainfall are joined by a line called isohyets [2] as shown in figure 4.
3.1.2    Pressure
         Air is made up of a number of mixed gases and has weight; it therefore
exerts a pressure on the earth’s surface which varies from place to place and
from time to time. This force that presses on the surface of any object can be
fairly accurately measured. The instrument for measuring pressure is a
barometer. A new unit known as the millibar (mb) was adopted by meteorological
stations in 1914. A normal atmospheric pressure equivalent is 1.03 kg per cm2
(14.7lb per square inch) in weight or a reading of 760 mm (29.9 inches) of
mercury in the column is 1013 mb. One tenth of a millibar is hectopascal (hPa) or
geopotential meter (gpm). In temperate latitudes, pressure changes are very
rapid in the formation of cyclones and anticyclones. In normal circumstances,
they vary from 960 mb to 1040 mb [2]. On maps places of equal pressure are
joined by lines called isobars as shown later in figure 26. Extreme pressures
recorded in Pakistan during 10 years (1993-2002) are shown in table 4.

          Table 4: Extreme Pressures Recorded in Major Cities of Pakistan
                   During Last 10 (1993-2002) Years.
           City              Minimum Pressure         Maximum Pressure
                                 (hPa/gpm)                (hPa/gpm)
           Islamabad            997.53 (July)         1016.21 (December)

           Lahore               996.51 (July)           1016.41(January)

           Karachi              998.09 (July)          1015.78 (January)

           Mianwali             995.88 (July)            1016 (January)

           Data from PMD.8



                                       -6-
3.1.3    Temperature
         Temperature is a very important element of climate and weather. The
instrument for measuring temperature is the thermometer. As the degree of
‘hotness’ varies tremendously from one place to another, the siting of the
instrument is very important. A temperature taken in open daylight is very high,
because it measures the direct insolation of the sun. But the temperatures that
we are so accustomed to in climatic graphs are shade temperatures that are the
temperatures of the air.

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Figure 5: Isotherm Plot Showing Annual Normal Temperature in Pakistan. (Data
from PMD Website 10)

The mean daily temperature is the average of maximum and minimum
temperature and the mean monthly temperature is the average of the daily mean



                                                  -7-
temperature. Temperatures are shown on maps known as isotherms as shown in
figure 5. Extreme temperatures recorded in major cities of Pakistan are given in
table 5.
            Table 5: Extreme Temperatures Recorded in Major Cities of Pakistan
                    During Last 50 (1953-2002) Years.

                 City             Minimum                   Maximum
                               Temperature (oC)          Temperature (oC)
             Islamabad           -3.9 (January)              46.1 (June)
             Lahore              -2.2 (January)              48.3 (May)
             Karachi             0.0 (January)               47.8 (May)
             Peshawar            -3.9 (January)              50.0 (June)
             Quetta             -18.3(January)               42.0 (July)
            Data from PMD Website.10
3.1.4      Humidity
           Humidity is a measure of the dampness of the atmosphere which varies
greatly from place to place at different times of day. The actual amount of water
vapour present in the air, which is expressed in gram per cubic meter, is called
the absolute humidity. Relative humidity (RH) is the ratio between the actual
amount of water vapour and the total amount the air can hold at a given
temperature, expressed as a percentage. The instrument for measuring relative
humidity is the hygrometer, which comprises wet and dry bulb thermometers
placed side by side in the Stevenson Screen shown later in figure 21.
        Relative humidity can be obtained with reference to prepared tables under
the difference column of dry and wet bulb reading. Normally a large difference
indicates a low R.H. Warm air can hold more water vapour than cold air, so if it
contains only half the amount it could carry, the RH is 50 %. When the RH
reaches 100 per cent, the air is completely saturated and the air temperature is
said to be at dew point. Further cooling will condense the water vapour into
clouds or rain. It is thus clear that when relative humidity is high the air is moist;
when it is low, the air is dry. Extreme RH recorded in major cities of Pakistan is
given in table 6.



                                       -8-
          Table 6: Extreme Relative Humidity (RH) Recorded In Major Cities
                   of Pakistan during Last 10 Years(1993-2002).
           City        Minimum RH (%age) Maximum RH (%age)
           Islamabad 25.8 (May)               87.2(December)
           Lahore      24.2 (July)            86.1(January)
           Karachi     32.2 (August)          81.3(February)
           Mianwali    24 (May)               90.4 (December)
                                   8
          Data from PMD Website.
3.1.5    Winds
         Wind is air in motion and has both direction and speed. Unlike other
elements in climate such as rain, snow or sleet, winds are made up of a series of
gusts and eddies that can only be felt but not seen. The instrument widely used
for measuring wind direction is wind wane and for measuring wind speed is
anemometer. By seeing the way some objects move, a great deal can be said
about the strength of wind. The best guide is obtainable from the Beaufort Wind
Scale which was devised by Admiral Beaufort in 1805 for estimating wind speed
is given in table 7.
3.1.5.1 Clouds
        When air rises, it is cooled by expansion. After dew point has been
reached, cooling leads to condensation of water vapour in the atmosphere. Tiny
droplets of water vapour which are too small to fall as rain or snow (less than
0.01 mm, approximately 0.0005 inches in radius) will be suspended in the air and
float as clouds. Their form, shape, height and movements tell us a great deal
about the sky conditions and the weather we are likely to experience. It is
fascinating and very rewarding to know something about the clouds which we
see every day [2]. For meteorological purposes, the amount of cloud cover in the
sky is expressed in eight or oktas. Details of cloud type are indicated in code
figures which have been internationally accepted. On maps places with an equal
degree of cloudiness are joined by lines known as isonephs. As clouds vary so
quickly from time to time at any particular place, isoneph maps have little
significance. The classification of clouds is based on a combination of form,



                                       -9-
height and appearance. Four major cloud types and their variations can be
recognized and described below.

                          Table 7: The Beaufort Wind Scale.
 Beaufort     Wind          Speed        Effects (a guide to observation)
 Scale No. Description   Km/h (mph)
    0      Calm        Less than 1.6(1) Smoke rises vertically
     1        Light air                            Wind direction shown by smoke-drift
                             1.6-5(1-3)
                                                   but not by wind vanes
     2                                             Wind felt on face; leaves rustle;
              Slight Breeze 7-11(4-7)
                                                   vanes moved by wind
     3        Gentle                               Leaves and twigs in constant
                             13-19(8-12)
              Breeze                               motion; winds extend light flags
     4        Moderate                             Raises dust and loose paper; small
                             21-29(13-18)
              Breeze                               branches moved
                                                   Small trees in leaf begin to sway;
     5        Fresh
                             31-39(19-24)          crested wavelets form on inland
              Breeze
                                                   water
     6        Strong                               Large branches in motion; whistling
                             41-50(25-31)
              Breeze                               heard in telegraph wires
     7        Moderate                             Whole tree in motion; walking
                             51-61(32-38)
              Gale                                 inconvenienced
     8                                             Twigs broken off trees; progress
              Fresh Gale     63-74(39-46)
                                                   generally impeded
     9                                             Slight structural damage occurs,
              Strong Gale    75-86(47-54)
                                                   chimney pots removed
    10                                             Considerable structural damage,
              Whole Gale     88-101(55-63)
                                                   trees uprooted
    11                                             Widespread damage, very rarely
              Storm          103-120(64-75)
                                                   experienced
    12                       More than             Widespread devastation,
              Hurricane
                             120(75)               experienced only in tropical areas.
From Strahler. 2

3.1.5.2 Classification of clouds
    a) High Clouds: High Clouds at 6000 meters above ground and are of
         following three types.
         i) Cirrus. This look thin, delicate, crystals clouds as shown in figure 6.
            Sometime these appear as booked filament called mares’ tails.




                                          - 10 -
                     Figure 6: Cirrus Clouds.11

ii) Cirrocumulus. This appears thin white ice crystals cloud in the form of
   ripples, waves or globular masses all in a row a shown in figure 7.




                 Figure 7: Cirrocumulus Clouds.11

iii) Cirrostratus. These appear like thin sheet of white ice crystals cloud
   that gives the sky a milky look as shown in figure 8.




                  Figure 8: Cirrostratus Clouds. 12


                              - 11 -
    b) Medium Clouds: Medium clouds are at heights 2000-6000 meters above
           ground and are of following two types.
           i) Altocumulus. White to grey cloud often cloud composed of separate
              globules; black clouds. The sky looks milky and the sun or moon
              shines through it as shown in figure 9.




                              Figure 9: Altocumulus Clouds.12

       ii)    Altostratus. Stratified veil of clouds that are generally thin, grayish and
              may produce light precipitation as shown in figure 10.




                              Figure 10: Altostratus Clouds.11

They have a fibrous or striated structure through which the sun’s rays shine
faintly.
    c) Low Clouds: Low clouds are below 2100 meters. These clouds have
           following types.
           i) Stratocumulus. Soft grey cloud in globular patches or rolls. There is
              great contrast between the bright and shaded parts as shown in fig.11.




                                         - 12 -
                Figure 11: Stratocumulus Clouds.12

ii) Stratus. Low uniform layer resembling fog but not resting on the
   ground. It brings dull weather with light drizzle. It reduces visibility for
   aircrafts. The types of clouds are shown in figure 12 below.




                    Figure 12: Stratus Clouds.12

iii) Nimbostratus. These are amorphous layer of dark grey clouds. It may
   bring continuous rain, snow or sleet. These clouds are shown in figure
   13 below.




                 Figure 13: Nimbostratus Clouds.11




                               - 13 -
d) Clouds of vertical developments: These are the clouds with no definite
   height (6000-9000 meters). These clouds have following types.
   i) Cumulus. This cloud is with a rounded top and flat base. Its great white
      globular masses may look grey against sun. These are known as fair
      weather clouds as shown in figure 14.




                      Figure 14: Cumulus Clouds.12

   ii) Cumulonimbus. These are towering clouds sometime spreading out on
      top to form an anvil head. It is black and white globular masses tale a
      fantastic range of shapes. It is also referred as a thunder cloud
      accompanied by lightning and rain and shown in figure 15.




                   Figure 15: Cumulonimbus Clouds.12


                                - 14 -
3.1.6 Visibility
           The distance up to which it is possible to see an object under the
prevailing atmospheric or weather conditions is called visibility. Horizontal
visibility is not same in different directions. The Shortest distance is quoted for
reporting visibility conditions. Elements affecting visibility include haze; mist and
fog are described below.
Haze. This is caused by smoke and dust particles in industrial areas or may be
due to unequal refraction of light in air of different densities in the low atmosphere.
The term is usually used in connection with the reduction of visibility in regions of
lower humidity, less than 75 percent. When visibility is less than 2 km (1.25 miles)
haze is present.
Mist. The condensation of water vapour in the air causes small droplets of water
to float about forming clouds at ground level called mist. It reduces visibility to
about 1000 meters or 1,100 yards. Unlike haze, mist occurs in wet air, when the
relative humidity is over 75 per cent.
Fog. Ordinary fog is due to water condensing on dust and other particles like
smoke from houses and factories. It only occurs in the lower strata of the
atmosphere as a sort of dense ground cloud. The visibility in fog is even less than
1000 meters. In industrial area, very thick smoky fog, called smog is formed. The
visibility may be reduced to 200 meters (220 yards) or even less. Fogs that occur
on hills are called hill fogs. They are most common in the morning, even in the
tropics, and disperse when the sun rises. In temperate lands, when days are hot
and nights are clear and still, fogs may also result from cooling of the land surface
by radiation. Fogs are more common over seas than lands, and are most
prevalent over coastal areas. The dry interiors experience haze or mist. Dense
fogs are more likely to occur in the high and middle latitudes rather than in the
tropics.




                                         - 15 -
4 ATMOSPHERIC DISPERSION

       A radioactive gas once become airborne travels and disperses in a
manner that is influenced by its own physical properties and those of ambient
atmosphere into which it is released. The effluent once released into the
atmosphere with certain velocity and temperature are generally different that of
the ambient atmosphere. The effluent motion has vertical component due to the
effects of vertical velocity and difference of temperature until they are dissipated.
The vertical rise of the effluent is called the plume rise and it changes the
effective height of the release point. The effluent movement is also affected by
wind during and after rise which is called Guide transport. The turbulent motion of
the atmosphere causes random movement of the effluent resulting in a
progressive lateral and vertical spreading by mixing with air called Guide
atmospheric dispersion. The combination of transport and diffusion is called
atmospheric dispersion [3].

       Atmospheric    dispersion    calculation   is   based    on      the   following
meteorological parameters which effect the concentration of radioactive effluent
variation from point to point after its emission into the atmosphere.

          Air temperature
          Air flow ( with directions, associated speed and their directions)
          Thickness of mixing layers
          Precipitation ( for estimation of deposition and depletion)
          Humidity

5 TURBULENCE OF THE ATMOSPHERE

       Fluctuation of wind direction and temperature laps rate are direct indicator
of turbulence. The diffusion characteristics of an atmospheric layer may be
partially determined by temperature difference between at least two levels. The
fluctuation in wind speed should also be measured at the same level and in the
same duration at which the temperature difference is measured [1].




                                      - 16 -
  6 INDICATOR OF TURBULENCE

             In various models used to find atmospheric dispersion, it is necessary to
  specify atmospheric stability in terms of or as a function of meteorological
  parameters. The atmospheric stability may consist of the following parameters
  depending upon the model chosen for dispersion calculation [1].
  6.1 Temperature Lapse Rate

             Meteorology of dispersion is mainly dependent on the low level
  atmospheric temperature and temperature of plume itself.            The variation in
  atmospheric temperature is driven by the relation:
                                    dT
                                        To  Cz                                    (1)
                                    dz
Where To is the temperature at z =0, ground level. The constant C is equal to the

rate of change in temperature per unit altitude and is called the adiabatic lapse rate.
  Altitude




                          Isothermal


                                                                       Superadiabatic

             Adiabatic




               Earth Surface
                                         Temperature


  Figure 16: Low-Level Temperature Distribution in the Atmosphere. (From
  Lamarsh.1)




                                          - 17 -
         When there is no heat transfer, an atmosphere that is as discussed earlier
is a mixture of different gases exhibit an adiabatic lapse rate. However,
atmospheric conditions are continually changing and as a result the temperature
distribution in the atmosphere frequently differs substantially from adiabatic
condition. Some of these behaviors and their effects on dispersion of pollutants
(assumed to be released at the same temperature as that of air) are described
below.
6.1.1     Adiabatic Condition

         If the rate of change in temperature is per unit altitude then it is called the
adiabatic lapse rate. This lapse rate is about 5.4 oF/1,000 ft or 1 oC/100 m as
shown in fig.17.

         If a parcel is released in an adiabatic profile, its movements are not
accompanied by changes in its relative buoyancy. The parcel simply moves a
short distance up or down the adiabatic profile, subject to whatever local
fluctuations occur in the atmosphere. That is why an adiabatic profile is referred
as neutral profile.


                         Z




                                                           Super-
                         h                                 Adiabatic




                                                 Ta                T

Figure 17: Movement of a Parcel of Air in Super adiabatic Profile. (From
Lamarsh1)




                                        - 18 -
6.1.2    Super Adiabatic Condition

        Over certain ranges in altitude the rate of temperature decrease may be
more rapid than the adiabatic rate, and in this case, the stratum of air is said to
exhibit super adiabatic behavior. The earth is heated during the daytime by the
sun, but at night it cools down as it radiates energy. Super adiabatic conditions
may occur in the first few hundreds meters of the atmosphere on clear days and
with light winds. This condition occurs due to the heat transferred to the air from
the hot surface of the earth.

        If volume of pollutant air or parcel of air whose volume generally changes
after release at some altitude h and at the same temperature Ta as the
atmosphere as shown in fig.17 , then according to the equation 1, the parcel will
remain in static equilibrium at that point. Suppose there is fluctuation in the
atmosphere then the parcel will move upward. The parcel will cool adiabatically
as it rises and the temperature of the parcel will follow the adiabatic curve as
shown by dashed lines in the fig. 17.

        It is clear from the figure that although the temperature of the parcel
decreases in absolute terms but as the parcel moves up its temperature rises
than the surrounding super adiabatic atmosphere. In turn, the parcel becomes
increasingly buoyant, causing it to move upward more rapidly far from its point of
release. On the other hand, if the parcel is initially pushed downward its
temperature will fall more rapidly than that of the ambient atmosphere and the air
will become increasingly dense. This situation will accelerate the parcel
downward. It is clear that super adiabatic temperature conditions are inherently
unstable and are highly favorable for the dispersion of pollutants [1].

6.1.3    Stable Condition

        In stable condition at the altitude the rate of temperature decrease is less
rapid as compared to adiabatic rate and the stratum.
        If a fluctuation in the parcel moves the parcel downward, its temperature
increases above that of the atmosphere, the parcel becomes more buoyant, and




                                        - 19 -
it again returns to the release point. The atmosphere in this case is said to be
stable, obviously not a desirable state of affairs for pollutant dispersion.

6.1.4     Inversions

        When the temperature increases over some range in altitude and some
where not then the condition exist called an inversion. This condition evolves on
cloudy night when the earth radiates energy most easily. The earth’s surface may
cool down faster than the air immediately above it and the result is a radiation
inversion.
        If the parcel is released into an inversion profile as shown in Fig.18, a
fluctuation in the parcel moves the parcel upward and its temperature falls more
rapidly than that of the atmosphere. In this situation the parcel becomes denser,
its upward motion stops and it returns to its release point.


                        Z                        Adiabatic




                                                             Inversions
                        h




                                            Ta                       T

Figure 18: Movement of Parcel of Air in Inversion Profile. (From Lamarsh.1)

6.1.5     Isothermal Condition
        When the temperature remains constant across a stratum, it is then known
as isothermal. Examples of these temperature distributions are illustrated in
Fig.16.
        If the parcel is hotter than its surroundings, the parcel will immediately
rise, due to its greater buoyancy. With unstable or neutral conditions, the parcel



                                       - 20 -
rise a distance Δh until it has mixed with and achieved temperature equilibrium
with the atmosphere. From other hand, when a hot parcel is released in stable
air, it rises until it reaches the inversion and then fans out.

6.2 Wind Direction Fluctuation
       The Change in magnitude of wind and its direction fluctuation are function
of the intensity of fluctuation. The wind direction fluctuation is therefore also used
to characterize the atmospheric stability. The standard deviation of the wind
direction is obtained by electronic devices or by wind direction records. The wind
direction record shows different width of trace for different stability conditions [3].
6.3 Insolation, Cloudiness and Wind Speed
       Insolation, cloudiness and wind speed are also used to determine the
stability classes. Thermal turbulence is related to heat flux. The cloud cover
reduces the heat losses or heat gain tending to make the stability neutral. Strong
winds increase mixing and lead to neutral stability. Clear skies at night with low
winds make for stable atmosphere. Whereas, the similar conditions in day time
make for an unstable atmosphere. During the day solar radiation measurement
or estimates are useful in determining the stability classes [3].

7 WEATHER OBSERVATIONS
       Various types of observations are made the world over at Universal Time
Coordinated (UTC) times prescribed by World Meteorological Organization
(WMO). The world time zones are shown in figure 19. The types of observation
are given as under.
           Hourly/ half hourly observations, for aviation.
           Three hourly observations at 0000, 0300, and 0600 UTC etc. called
            synoptic observation or SYNOP.
           Six hourly observations regarding upper air (Wind Direction/Speed)
            called PILOT observations.
           Twelve hourly observations regarding temperature, humidity, pressure
            etc called “TEMPS” observations at various levels.



                                       - 21 -
            g
     150o 1 3 o 1 2 o 1 0 5 9 o 7 o 6 4 o 3 0 1 5 o 1 o 3 o 4 5 6 o 7 o o 105 120 0 1 3 o 1 5 0 165 180
 165o5 1 5 013551200 105o 900 755 60o0 455 30o 15o 00 155 300 45o 600 755 909 0 1 0o5 1 2o1355 150o1 6 5 o1 8 0 o
  16



                                                                                                                                                                                                                                 N




                                                                  7 a.m.




                                                                                                                                                                                120
                                                          75




                                                                                                                                   45




                                                                                                                                                                                                                      Mdinight
                                                                                                                                                                                                            11 p.m.
                                                         7 a.m.
            2 a.m.




                                                                                                                                                                                                  10 p.m.
                     3 a.m.

                              4 a.m.




                                                                   8 a.m.
                                       5 a.m.

                                                6 a.m.




                                                                                                                                                                       7 p.m.


                                                                                                                                                                                         9 p.m.
                                                                            9 a.m.




                                                                                                                                                                                8 p.m.
                                                                                     10 a.m.




                                                                                                                                                              6 p.m.
                                                                                                11 p.m.
   1 a.m.




                                                                                                          Noon
                                                                                                                 1 p.m.
                                                                                                                          2 p.m.


                                                                                                                                            4 p.m.

                                                                                                                                                     5 p.m.
                                                                                                                                    3 p.m
                                                         Figure 19: The World Time Zones.

8 SURFACE OBSERVATIONS
            Surface observations give information about temperature, pressure, wind
direction/speed, dew point temperature and relative humidity etc. This
information is gathered at the station level and interval of 3 hrs starting from 0000
UTC [3].
8.1 Equipment Used
              Following equipments are used for gathering surface observations.
I. WIND VANE-The instrument widely used for measuring wind direction is wind
vane. It is erected in an exposed position, to get a true direction. It consists of
two parts, one is an arrow on the top which is free to move and the other part
consists of four compass points which show the direction of wind as shown in
figure 20 below.




                                                                    Figure 20: Wind Vanes.11



                                                                                               - 22 -
II. STEVENSON SCREEN - To find temperatures Stevenson screen is used. It
consists of white wooden box raised 1.2 meters above the ground on stilts. The
roof is double-layered with an intervening air space to exclude much of the direct
rays of sun. The sides of the box are lowered like ’Venetian blinds’ to allow free
circulation of air as shown in figure 21. The Stevenson screen normally carries
following thermometers:
        a) Maximum temperature (mercury thermometer)
        b) Minimum temperature (alcoholic thermometer)
        c) Dry bulb temperature (mercury thermometer)
        d) Wet bulb temperature (mercury thermometer)




                          Figure 21: Stevenson Screens.11

III. ANEMOMETER-This is used to find wind speed in units of Knots. It consists
of four semi circular cups attached to the ends of horizontal spokes mounted on
a high vertical spindle as shown in figure 22. The horizontal spoke rotates due to
a wind that transmits the velocity of the wind in Kilometers per hour. The speed
recorded is not absolutely accurate because after wind has abated, the rotation
continues due to its own momentum.




                          Figure 22: Wind Anemometers.11


                                     - 23 -
IV. MERCURY BAROMETER- This is used to find atmospheric pressure in units
of mbar (1bar=105 N/m2). Pressure readings vary with a number of factors like
temperature, altitude and gravitational forces at different latitude. Therefore
meteorologist made correction in respect of the above described factors. Mercury
barometers are shown in figure 23.




                        Figure 23: Mercury Barometers.11

V. SELF RECORDING RAIN GAUGE-This is used in recording rain in units of
millimeters. It consists of indicator coupled with jar storing water and a chart with
graduation marks as shown in figure 24. The level of water rising in the jar is
automatically transferred to the chart and recorded.




                    Figure 24: Self Recording Rain Gauges.11



                                      - 24 -
8.2 Code Classification
        For reporting surface observations, five sections of codes are used. The
letters AAXX identifies the surface observations. The whole code is made up of
figure group arranged by sections in ascending order of their numerical indicator
[5]. The sections are as following

8.2.1     Section-0

        This section is used to report the Station type (SYNOP or SHIP), day and
time of report, local and international station No. and units of wind speed used.

8.2.2     Section-1

        This section of report is used to report visibility condition, cloud coverage
on sky, wind direction/speed, temperature, due point temperature, sea/ station
level pressure and Past / present weather conditions.

8.2.3    Section-2

        This section is for Maritime data pertaining to coastal station.
        (Not in use.)

8.2.4    Section-3

        This section is used for reporting, minimum and maximum temperature in
°Celsius, Amount of pressure variation during the last 24 hrs and amount of
precipitation with duration.

8.2.5     Section-4

        This section is used for the stations whose base is often below the station
level. This section is only used for clouds data reporting.

8.2.6     Section-5

        This section is for national exchange of data. (Not in use)
Example
        Following is the example for decoding synoptic data
AAXX 41577 31996 01802 10125 20108 39932 40074 70400 333 20197 59034
(data form)


                                       - 25 -
                      Table 8: Example of Synoptic Data Decoding.

Code        Code form        Section   Description

 41577     IIiii                0      II=41(Country Code), iii=577(Station No. i.e.
                                       Islamabad)
                                       IR=3 (Inclusion or omission of precipitation
 31996     IRix*hvv             1
                                       data 3 means omitted), Ix=1 (Past and
                                       present weather included or omitted, 1
                                       means included). h=9 (Height above ground
                                       of base of cloud, 9 means above 8000 feet),
                                       vv =96(Horizontal visibility at surface 96
                                       means objects visible at 4000 meters.)
 01802     Nddff                1      N=0 (Gives cloud coverage 0 mean no
                                       clouds) , dd=18 (wind direction i.e. 165o),
                                       ff=02 (wind speed in knots)
 10225     1SnTTT               1      Sn=0 (Sign of Temp. i.e. +ve)
                                       TTT=225 (means 22.5oC temperature)
 20108     2SnTdTdTd*           1      Sn=0 (Sign of Temperature. i.e. +ve),
                                       TdTdTd=108 i.e 10.8 is dew pt. Temperature)

 39932     3P0P0P0P0            1      P0P0P0P0=993.2mb Pressure
 40074     4PPPP                1      PPPP=1 (0074 or 107.4mb pressure)
 70400     7wwW1W1              1      ww=04 (Present weather 04 means reduced
                                       visibility), W1W1=00 (Gives cloud coverage
                                       00 means clear sky)

                                       Sn=0 (Sign of temp. 0 means +v.
 20197     2SnTnTnTn            3
                                       TnTnTn=197 Minimum Temperature. i.e.
                                       19.7oC.)
59034      59P24P24P24*         3      59 are for negative surface pressure over
                                       the last 24 hrs i.e. P24P24P24=034
                                       (Decreased P)
Subscripts: x* means indicator for type of station, d* means Dew point, 24* means 24
hours

9 UPPER WIND (PILOT) OBSERVATIONS

        From PILOT observations we get information about upper wind speed and
direction. The letters PP identifies a PILOT code. These observations are
recorded at standard heights starting from 850 mbar to 100 mbar. Upper wind
observations are reported at an interval of 6 hrs starting from 0000 UTC [6].


                                        - 26 -
9.1 Instruments Used

        Pilot balloons filled with hydrogen gas as shown in figure 25 are used for
obtaining upper wind drift. Theodolite is used to measure azimuth and altitude
angles. These angles are helpful in finding wind direction and wind speed.




Figure 25: Pilot Balloon Being Sent For Collection of Upper Air Data. (From
WMO Website 9)

9.2 Code Classification

        Pilot data consist of four parts i.e. A, B, C and D as described below. Each
of the four parts of PILOT data is coded as separate report in specified form.
Each of the four parts may consist of any of the section given in table 9 [6].

                        Table 9: Code Classification of PILOT Code.

           Section     Indicator Fig. Contents

             1.           None          Identification & position of data
             2.           55            Standard isobaric surface data
             3.           6,7           Data for maximum wind
             4.           9,1           Data for fixed region

9.2.1     Part-a

        Part A section-2 (table 9) contains data for the standard isobaric surfaces
850,700,500,400,300,250, 200,150 and 100mb above ground. Section 3 contains
data for level of maximum wind but often not reported.


                                      - 27 -
9.2.2        Part-B

     This part contains data only for fixed regional level up to 100mb level in units
of 300 meters. These regional levels are 300, 600, 900, 2100, 3600,
4500,6000,13500 & 15000 meters.

9.2.3        Part-C

     Part-C section-2 (table 9) contains data for standard isobaric surfaces of
70,50,30,20 and 10 mb. (Not in use)

9.2.4        Part-D

            Part-D section-4 contains data only for regional levels above the 100mb in
units of 300 meters. These regional levels are 19500, 22500, 25000, 28500,
31500 & 33000 meters. (Not in use)
Example
PPAA 53121 41780 55385 32505 30517 29528 30517 29528 55340 29041
29543 30048 55120 31052 7999 (Code Form)
                           Table 10: Example of PILOT Data Decoding.

  Code          Code form        Section          Description

                                           YY=53 (Date of the month 53-50=3)
  53121        YYGGa4               1      GG=12 (Time of observation)
                                           a4=1 ( Type of equipment used 1 means
                                           optical thedolite)
  41780        IIiii                1      II=41(Country Code), iii=780 (Station No.
                                           i.e. Karachi)
                                           n=3 (No. of consecutive isobaric surfaces
  55385        55nP1P1*             2      maximum is No. 3)
                                               P1P1=85 (850mb lowest isobaric surface )
                                               dd=325o (Wind direction rounded off)
  32505        Dddfff               2
                                               fff=05 (Wind sped in knots)
        :              :            :      :
  7999         7HmHmHm*             3      HmHmHm=999 (Indication figure of the end
                                           the part)
Subscripts: 0, 1, 2…n* means standard isobaric surfaces, m* means maximum level



                                               - 28 -
10 ‘TEMPS’ OBSERVATIONS
       These    observations       are     reported     to     give     information   regarding
temperature, pressure and humidity etc. at various levels above surface. The
observations are recorded at standard heights i.e. 850mb, 400mb, 300mb,
200mb 50mb and 100mb etc. The observations are reported with a difference of
12 hrs i.e. at 0000 UTC and 1200 UTC [7].

10.1 Equipment Used

       Hydrogen gas filled balloons along with radiosonde transmitter is used for
obtaining upper level information about temperature pressure and humidity level.
Theodolite is used to measure azimuth and altitude angles. These angles are
helpful in finding wind direction and speed.

10.2 Code Classification

       TEMPS data consist of four parts i.e. A, B, C and D as described below.
Each of the four parts is coded as a separate report in specified form. Each of the
four parts may consist of the following seven sections given in table 11 [7].

                  Table 11: Code Classification of ‘TEMPS’ Code.

  Section Indicator fig.                 Contents
      1.         None                    Identification of position
      2.         None                    Data for standard isobaric surfaces

      3.         88                      Data for tropopause level

      4.         77 or 66                Data for maximum wind level

      5.         None                    Data for temperature and relative humidity
      6.         21212                   Data for significant levels for winds.
      7.         41414                   Cloud data

10.2.1 Part-A
       Part-A of TEMPS report consists of section 1, 2, 3 and 4 (table 11).
Section    2   contains     data    for      standard        isobaric    surfaces     of   1000,


                                           - 29 -
850,700,500,400,300,250,200, 150 and 150mb above ground. This part also
gives information about air temperature, dew point temperature, pressure and
wind direction/ speed etc.

10.2.2 Part-B

       Part-B consists of sections 1, 5 and 6. This section contains data for fixed
regional levels starting from 1000mb.It gives information of the intermediate
surfaces of part A. It also gives information about air temperature, dew point
temperature, pressure, wind direction and wind speed etc.
Example
TTAA 57002 43041 99951 22235 85536 23875 06510 (data form)

                  Table 12: Example of ‘TEMPS’ Data Decoding.

 Code     Code form          Section Description

 57003    YYGGId               1      YY=57 (Date of month i.e. 57-50=7), GG=00
                                      (Time of observation. here 00 GMT)
                                      Id=3 (Indicator for the last isobaric surface 2
                                      means 200mb)
 43041    IIiii                1      II=43 (Country code for India),
                                      iii=041(Station No.)

 99951    99PoPoPo*            2      99=Indicator figure for surface data.
                                      PoPoPo= 951(Pressure at station level in mb)

 22235    ToToToDoDo           2      ToToTo=222 (Air temp. at surface i.e. 2.2oC),
                                      DoDo= 35 (Dew pt. depression temp 3.5 oC)
 85536    PnPnhnhnhn           2      PnPn=85 (pressure in tens of mb means 850
                                      mb), hnhnhn=536 (Geopotential height in
                                      meters)
 23875    TnTnTan* DnDn        2      TnTnTan= 238 (Air temp. i.e. 23.8 oC)
                                      DnDn=75 (Due point depression temp. i.e.
                                      25 oC)
 06510    dndn fnfnfn          2      dndn = 065 (wind direction i.e. 65o),
                                      fnfnfn =10 ( Wind speed in Knots)
Subscripts: 0, 1, 2…n* means standard isobaric surfaces, an* means approximate value




                                      - 30 -
10.2.3 Part-C
      Part-C consists of section 1, 2, 3 and 4 (table 12). It contains data for
standard isobaric surfaces of 70,50,30,20 and 10mb. This section contains data
that is hemi- spherically exchanged. (Not in use)
10.2.4 Part-D
      Part-D consists of section 1, 5 and 6 (table 12). It contains data above
100mb level. It contains information about, temperature, pressure, wind direction
and speed. (Not in use)

11 WEATHER CHARTS

      Different weather charts are prepared by forecasters at different intervals
of time weather to show barometric pressure, wind, and rainfall. These charts
help them to understand the local as well as regional prevailing weather
condition. These charts help forecaster in determining the future fast breaking
weather events like tornadoes, severe thunderstorms, and flash floods. Some of
the important weather charts are described as under.

11.1 Surface Chart

     These charts are prepared at an interval of 3 hrs. In this chart same
atmospheric pressure places are connected called isobars as shown in figure 26.
These types of surface analysis give information about position of high, low,
trough & ridges. Occurrence of type of weather type i.e. rain, fog, mist or haze. It
also gives idea about min/max temperature and determining future shape of
weather.

11.2 Upper Air Chart

      This chart is prepared at an interval of 6 hrs. Prevailing wind speed and
direction at specified heights are drawn on this chart as shown in figure 27.
Analysis of this chart gives information like prevailing wind speed direction, the
moisture incursion at various level, the level up to which active weather system
extends and future pattern of upper wind and active surface weather system.




                                     - 31 -
Figure 26: Surface Chart Showing Isobars, Low/High Pressure and Trough.
(From PMD Website10)




Figure 27: Upper Air (PILOT) Charts Showing Wind Direction and Speed. (From
PMD Website10)


                                 - 32 -
11.3 “TEMPS” Chart
       This chart is prepared at an interval of 12 hrs. Temperature, dew point and
prevailing win direction/speed are plotted on this chart as shown in figure 28. Low
and high pressure are identified on these charts, which are helpful in determining
prevailing   temperature   at   various   levels   and   active   weather   system
determination.




Figure 28: TEMPS Chart Showing Wind Direction and Speed. (From PMD
Website10)

12 METEOROLOGICAL ORGANIZATIONS

       For weather prediction, climate change related activities and tropical storm
forecasting, most of the countries have meteorological organizations to allow
increasingly prompt and accurate weather information and other services for
public, private and commercial use, including international airline and shipping
industries. Meteorological activities contribute to the safety of life and property,
the socio-economic development of the country and the protection of the
environment. Introduction of some of the important meteorological organizations
is given below.


                                     - 33 -
12.1 National Oceanic & Atmospheric Administration

       National Oceanic & Atmospheric Administration (NOAA) is an intrinsic part
of the history of the United States and the development of its science and
commercial infrastructure. The ancestor agencies of the National Oceanic and
Atmospheric Administration include the United States Coast Survey established
in 1807, the United States Weather Bureau established in 1870. NOAA was to
lead the development of a consolidated national oceanic and atmospheric
research and development program and provide a variety of scientific and
technical services to other Federal agencies, private sector interests and the
general public. Following are the six major programmatic components of NOAA.
          The National Marine Fisheries Service
          The Environmental Research Laboratories
          The National Weather Service
          The Environmental Data Center
          The National Ocean Survey
          The National Environmental Satellite Service
       The National Weather Service program provides tomorrow's forecasters
with advanced tools for observing and forecasting small-scale, fast breaking
weather events like tornadoes, severe thunderstorms, and flash floods weather
events. The collected data is exchanged with most of the other countries in the
world that collect similar observations [13].

12.2 Met Office

       The Met Office (MO) of UK was formed in 1854 as a small department
within the Board of Trade to provide meteorological and sea current information
to mariners. After the war in 1952 a Directorate of Research was formed to
control and direct the practical and theoretical investigations that were being
carried out. The Met Office becomes an Executive Agency in April 1990. A month
later, the Hadley Centre for Climate Prediction and Research opened.
       Met Office is one of the world's leading providers of environmental and
weather-related services. Its solutions and services meet the needs of many


                                      - 34 -
communities of interest from the general public, government and schools,
through broadcasters and online media, to civil aviation and almost every other
industry sector in the UK and around the world. Met office looks at the impacts of
the weather on the environment and will expand into environmental sciences,
such as hydrology and oceanography [14].

12.3 Islamic Republic of Iran Meteorological Organization

        Islamic Republic of Iran Meteorological Organization (IRIMO) originally
started work in 1919 in the fields of meteorology, agro meteorology and aviation
meteorology. However general office for meteorology was established in 1958
and began its operation under authority of the ministry of roads and
transportation. The main objectives of the IRIMO is to provide air force and civil
aviation with meteorological information, to provide meteorological data and
forecast to private and government enterprises and to study atmospheric
condition and physical status of the sea for oil exploration and fishing etc [15].

12.4 Turkish State Meteorological Service

        Turkish State Meteorological Service (TSMS) was founded in 1937. It is
the only legal organization which provides all meteorological information in
Turkey. The main objectives of the TSMS are to make observations, to provide
forecasts, to provide climate data, archive data, and other information, to
communicate these to the public and to provide meteorological needs of army
and civil aviation [16].

12.5 China Meteorological Administration

       The China Meteorological Administration (CMA), a state government
institution directly subordinate to the State Council of the People's Republic of
China, is to administer and oversee the weather-related affairs nationwide. Its
terms of reference are as follows [17]:
       Formulate policies, legal and regulatory frameworks.
       Participate in the central government decision-making process in case of
        meteorological disasters.


                                      - 35 -
       Oversee meteorological setups located in other sectors from trade
        perspective.
       Administer the national weather forecast and warning.
       Administer meteorological foreign affairs etc.

12.6 India Meteorological Department

       The India Meteorological Department (IMD) was established in 1875. It is
the National Meteorological Service of the country and the principal government
agency in all matters relating to meteorology, seismology and allied subjects.
Following are the main objectives of IMD [18].
       To take meteorological observations and to provide current and forecast
        meteorological information for optimum operation of weather-sensitive
        activities like agriculture, irrigation, shipping, aviation, offshore oil
        explorations, etc.
       To warn against severe weather phenomena like tropical cyclones, dust
        storms, heavy rains and snow, cold and heat waves, etc.
       To provide meteorological statistics required for agriculture, water
        resource management, industries, oil exploration and other nation-building
        activities.
       To conduct and promote research in meteorology and allied disciplines.
       To detect and locate earthquakes and to evaluate seismicity in different
        parts of the country for development projects.

12.7 World Meteorological Organization

        World Meteorological Organization (WMO) was created under World
Meteorological Convention in the Twelfth Conference of Directors of the
International Meteorological Organization (IMO), which met in Washington in
1947. Although the Convention itself came into force in 1950, WMO commenced
operations as the successor to IMO in 1951 and, later that year, was established
as a specialized agency of the United Nations by agreement between the UN
and WMO [10].



                                      - 36 -
      The purposes of WMO are to facilitate international cooperation in the
establishment of networks of stations for making meteorological, hydrological and
other observations; and to promote the rapid exchange of meteorological
information, the standardization of meteorological observations and the uniform
publication of observations and statistics. It also furthers the application of
meteorology to aviation, shipping, water problems, agriculture and other human
activities, promotes operational hydrology and encourages research and training
in meteorology.

      As of June 1996, there were 185 Members, comprising 179 Member
States and 6 Member Territories, all of which maintain their own Meteorological
and Hydrological Services.

      The World Meteorological Congress, which is the supreme body of WMO,
meets every four years. It determines policies, approves the programme and
budget and adopts regulations.

      Members are grouped in six regional associations (Africa, Asia, South
America, North and Central America, South-West Pacific and Europe). Each of
them meets every four years to coordinate meteorological and operational
hydrological activities within their region and to examine questions referred to
them by the Council. WMO has eight technical commissions responsible for:
aeronautical meteorology; agricultural meteorology; atmospheric sciences; basic
systems; climatology; hydrology; instruments and methods of observation; and
marine meteorology. Each of them meets every four years.

12.7.1 World Weather Watch

      WMO's major scientific and technical programmes include the World
Weather Watch (WWW), which is the backbone of WMO's activities. WWW offers
up-to-the-minute world-wide weather information through Member-operated
observation systems and telecommunication links with weather stations given in
table 13. World weather watch meteorological satellite network is shown in figure
29.



                                    - 37 -
      Each day, high-speed links transmit over 15 million data characters and
2000 weather charts through the World, 35 Regional and 183 National
Meteorological Centers cooperating with each other in preparing weather
analyses and forecasts in an elaborately engineered fashion. Thus transoceanic
ships and aeroplanes, research scientists on air pollution or global climate
change, the media and the general public are given a constant supply of timely
data. It is through WMO that the complex agreements on standards, codes,
measurements and communications are established internationally.

                      Table 13: World Weather Observation System.

              Weather Observation System               Number of Stations

              Polar-Orbiting Satellite                          4
              Geostationary Satellite                           5
              Land Stations                                   10,000
              Ship Stations                                   7,000
              Moored and drifting automatic Station            300
             Data from WMO website 10.
      Data from all over the world are needed to provide weather forecasts. If
there were no WMO, the nations of the world would have to conclude individual
agreements with one another to ensure the exchange and availability of data to
meet their national requirements, such as provision of forecasts for the public
and special services for various economic sectors like agriculture, utilities (gas,
electric power production) and so on. An aircraft does not take off, nor does a
ship leave port, without a weather forecast. The provision of such services is part
of the international responsibilities of individual countries which would be hard
pressed to provide accurate and timely information if the global infrastructure
established under the auspices of WMO did not exist.

      Also grouped under the WWW "umbrella" are WMO's satellite and
emergency response activities, the latter relating to the coordination and
implementation of procedures and response mechanisms for the provision and



                                     - 38 -
exchange of observational data and specialized products in case of nuclear
accidents, as well as the Instruments and Methods of Observation Programme
and the Tropical Cyclone Programme (TCP). The TCP, which is contributing
substantially to the UN International Decade for Natural Disaster Reduction, is
designed to assist more than 50 countries in areas vulnerable to tropical
cyclones to minimize destruction and loss of life by improving forecasting and
warning systems, and disaster preparedness measures. Meteor




Figure 29: World Weather Watch Meteorological Satellite Network. (From WMO
Website 9)

13 PAKISTAN METEOROLOGICAL DEPARTMENT (PMD)
    The Pakistan Meteorological Department is both a scientific and a service
department, and functions under the Ministry of Defense. It is responsible for
providing meteorological service throughout Pakistan to wide variety of interest and
for numerous public activities and projects which require weather information. In its
services to aviation the department's responsibility goes to some extent beyond
national boundaries in fulfillment of accepted international agreements and



                                      - 39 -
obligations which include, among other things, the collection and rebroadcast of
meteorological data.

    Apart      from    meteorology,    the   department     is   also     concerned   with
Agrometeorology, Hydrology, Astronomy and Astrophysics (including solar
physics), Seismology, Geomagnetism, Atmospheric Electricity and studies of the
Ionosphere and Cosmic Rays. Pakistan Meteorological Department shoulders the
responsibility to investigate the factors responsible for global warming, climate
change its impact assessment and adaptation strategies in various sectors of
human activities [9].

    The Pakistan Meteorological Department is headed by Director General.
Functionally, the Department is divided into three Directorates located in the Office
at Karachi, each headed by a Director, as follows:

       i)        Directorate of Maintenance
       ii)       Directorate of Forecasting and Climatology
       iii)      Chief Administration Officer
            The field set up of the department is constituted as below:
       i)        Regional Meteorological Centre, Karachi.
       ii)       Regional Meteorological Centre, Lahore.
       iii)      Director National Flood Forecasting Bureau, Lahore.
       iv)       Director Geophysical Centre, Quetta.
       v)        Director Computerized Data Processing Centre, Karachi.

    Major functions entrusted to the Pakistan Meteorological Department are to
provide information on meteorological and geophysical matters with the objective of
traffic safety in air, on land and sea, mitigation of disasters due to weather and
geophysical phenomena, agriculture development based on climatic potential of the
country, prediction and modification of weather forecast.

13.1 Services
       i)        Observatories, data generation and dissemination services in the
                 following areas
              a. Surface Weather Data             b. Upper Air Data


                                         - 40 -
        b. Earthquake Data                   d. Astronomical Data
        e. Solar Radiation Data              f. Atmosphere Ozone Data
        g. Earth's Magnetic field Data       h. Background Air Pollution Data
ii)        Aeronautical forecasts and warning services for Civil Aviation, PAF,
           Army, Navy and other users.
iii)       Flood forecast and warning services.
iv)        Earthquake data and seismic information services to Civil Engineers
           and other users for dams, bridges, townships etc.
v)         Farmer's Weather Bulletin and Warning Services.
vi)        Public utility and advisory services in various fields of:
        a. Planning and Development
        b. Town Planning
        c. Construction of Roads, Bridges, Aerodromes, Power Plants, Air
           conditioning etc.
        d. Provision of Meteorological/Geophysical data for court cases,
           insurance claim, inquiry reports, district gazetteers etc.
vii)       Military operation services in the following way:
        a. Weather Monitoring Air Bases.
        b. Forecasts and Warning for Air Bases.
        c. Weather forecasts and Monitoring in assigned areas.
        d. Meteor Reports
viii)      Marine Meteorological Forecasting and Warning Services.
ix)        Air Pollution Monitoring Services.
x)         Research activities in the following fields:

        a. Meteorology                   b. Climatology
        c. Hydrology                     d. Oceanography
        e. Atmospheric Physics           f. Environmental Pollution
        g. Geophysics                    h. Agricultural Meteorology




                                    - 41 -
                                                                        $                       Gupis
                                                                                   A
                                                                                            $     $
                                                                                                     Chillas
                                                                                                    Gilgit
                                                                          FAN Sakardu
                                                                 Chitral                                $
                                                                $
                                                                  Drosh
                                                                       P         Astore                         $   $

                                                              DirWF
                                                                        $


                                                              NRisalpur Muzz.abad
                                                                   Saidu Sharif
                                                                                $
                                                                                           D
                                                                                        UTE
                                                                                                $
                                                                            %

                                                               PeshawarMurre
                                                                                  SP EA
                                                                    %



                                                              Kohat AJKDI
                                                      $                                     $
                                                      ParachinarChirat
                                                                $
                                                                        $
                                                                                        %           $

                                                          A Islanabad      Kotli        R
                                                     FAT Mianwali Jehlum A
                                                                                                %

                                                                    %
                                                                              Sialkot                       %


                                                                        Sargodha    %
                                                           %
                                                               D.I Khan %         Lahore
                                                                   B
                                                                                 %




                                                            NJA
                                                 $
                                                                    Jhang Faisalabad

                                                          PU Multan
                                                Zhob                 %


                                                                %
                               $
                                 Quetta                             %
                                                                      Bahawalnagar
                                                 $
                                                   Barkhan
                          AN           Sibbi                   Bahawalpur
                                     %                       %



                       IST
                   Dalbadin $ Kalat
                      H
                                                                                                                        Legend
                   LOC
                 $
        $
          Nokkundi
                                                       %
                                                         Khanpur
                                                                                                                        $
                 BA
                              $
                                Khuzdar %
                                          %
                                            Jacobabad                                                                     Hill
                                              Rohri                                                                     % Plain
                                       %
                                         Mohenjodoro
               $
                 Panjgur               %
                                         Padidan
                                           D
                                        SIN
                           %
                             Lasbela
                                         %
                                           Nawabshah
            Pasni Gawadar
    Jewani %       %
                                              %
                                                Chhor
    %
                                         %
                                           Hyderabad
                                   %
                                       Karachi % Badin



Figure 30: Meteorological Observatory Station Network in Pakistan. (Data from
PMD Website 10)

      xi)       Astronomical services in the following fields:
             a. Sun rise/set timings
             b. Names timings and Quibble Direction calculations
             c. Morning/evening twilight timings
             d. Sun/Moon Eclipse                      e. Sighting of new moon
      xii)      Training in Meteorology and Geophysics for:
             a. Departmental Trainees                b. Trainees from other organizations
             c. Foreign Training                      d. PAF (Met. branch) trainees.




                                               - 42 -
14 CONCLUSIONS
       Weather      parameters   are      important   in   atmospheric   dispersion
calculations. Real time weather data is therefore necessarily required in case of
these types of calculations. Weather data is mainly of three type namely surface
data, PILOT data and TEMPS data. The surface data is gathered at the station
level with an interval of 3 hrs starting from 0000 UTC. The other two types of data
are gathered at various altitudes and times. The weather data includes
information about temperature, pressure, wind direction/speed and relative
humidity. The real time data is also helpful in determining future weather
conditions.

       There are 72 meteorological observatories of Pakistan Meteorological
Department (PMD) in Pakistan to collect and analyze the weather data for issuing
forecasts and warnings. The information gathered from these observatories is
available on the web page www.pakmet.com in coded form. The world
meteorological web site also includes Pakistan territory data on the web page
www.atmos.albany.edu/weather/data1/surfac/syn/. The data available can be
decoded as described in the sections 5-7 of this report and can be used for
various purposes.




                                       - 43 -
References
[1]    John R. Lamarsh “Introduction to Nuclear Engineering” 3rd Edition, 1998,
       Addison-Wesley Publishing Company, United States.
[2]    Alan H. Strahler “Modern Physical Geography” 4rh edition, October 1991,
       John Wiley and sons publishing company.
[3]    Pasquill, F.” Atmospheric Diffusion”, 2nd edition, 1973, Halstead Press, New
       York.
[4]    International Atomic Energy Commission” Atmospheric Dispersion in
       Nuclear Power Plant Siting” A Safety Guide, 1980, Vienna.
[5]    Pakistan Meteorological Department “Surface Weather Observations” 1982,
       Karachi.
[6]    Pakistan Meteorological Department “Reporting Upper Wind Observations”
       1980, Karachi.
[7]    Pakistan Meteorological Department “Reporting Radiosonde and
       Rawinsonde Observations”, 1972, Karachi.
[8]    Computer Data Processing Center,” Ten Years (1993-2002) Averaged
       Data”, Pakistan Meteorological Department, University Road Karachi.
[9]    The web site address of World Meteorological Organization is
       http://www.wmo.com
[10]   The web site address of Pakistan Meteorological Department is
       http://www.pakmet.com
[11]   The web site address Dept. of atmospheric science at university of Illinois
       Urbana Campaign http://www.atmos.uiuc.edu/guides/mtr/cld/cldtyp/
[12]   The web site address for cloud classification observation is
       http://www.australiasevereweather.com/techniques/moreadv/class.htm
[13]   The web site address of United States for meteorological observation is
       http://www.lib.noaa.gov
[14]   The web site address of UK for meteorological observation is
       http://www.metoffice.com
[15]   The web site address of Iran for meteorological observation is
       http://www.irimo.gov.irn
[16]   The web site address of Turkey for meteorological observation is
       http://www.meteor.gov.tr
[17]   The web site address of China for meteorological observation is
       http://www.cma.gov.cn
[18]   The web site address of India for meteorological observation is
       http://www.imd.ernet.in




                                      - 44 -

				
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Description: Climatic parameters strongly influence plume behavior in the atmosphere and hence are important while studying its behavior in the atmosphere. Real time Meteorological data for the whole world is available on the internet and it can be used in radionuclide dispersion calculations. The data available on the internet is in coded form and has to be decoded before use. This report includes explanations of different weather parameters used in the dispersion calculation and the method of data decoding with examples. Introduction of some of the important meteorological organizations of various countries and that of Pakistan Meteorological Department have also been included at the end of this report.