Word description Wind speed Wind impact on ship and rigging Sea state M

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Word description Wind speed Wind impact on ship and rigging Sea state M Powered By Docstoc
					Steve,


Sea surface state (MS) is determined visually and depends upon wind force. Wind force is
visually described both in words and in Beaufort wind scale numbers (Forces).


We have made an attempt to review manuals and guides on ship wind observations and so
far managed to find the only one, namely, “Instructions to hydrometeorological stations
and posts”(Issue 9, Part 2, 1948), which gives the joint table of wind force and sea surface
state described by the so-called Beaufort-Simpson scale (Table 1). This table was used in
Russian observations to estimate both wind force and the MS parameter.


In the period of 1962-1992 the same Beaufort scale was used and word description of
indicators required to define the surface state of an ocean, sea, lake or large water body
(MS) corresponds to that given in Table 3, which we included into the format.


Since 1992 the Beaufort scale has been modified. Wind speed increased and the
corresponding wind force given in numbers remained unchanged (Table2).
In original historical tables the MS parameter has already been encoded and given in
numbers.


Russian national manuals on ship observations do not mention that Beaufort scale should
be used to estimate MS. They give only Table 3, which we include into the format.
In my opinion, when MS is converted to wind force Beaufort scale used at the time, when
observations were made, should be applied.


The digitization work is go on OK. At present time we prepare 100 cruises-files with
meteorological and actinometric observations and forwarding to NCAR in a week.
Regards,
Svetlana


Table 1
Wind force, wind speed and sea surface state




                                                                                               1
      Wind force                                                              Sea surface state with wind waving




                                              indicators observed
                                               Visual wind force
                          Wind speed m/s
                                                                              Word description                    Indicators for




                                              on board a ship




                                                                                                                     in numbers
                                                                                                    Sea surface
                                                                                                                  determining actual
           Word
Beaufort
numbers
           description                                                                                            wind force and




                                                                                                   state
                                                                                                                  wind waving

0          Calm           0,0-0,5          Flags are still                    Calm glassy          0              Like a mirror
1          Light airs     0,6-1,7                                             Calm rippled         1
                                                                                                                  Ripples
2                         1,8-3,3                                             Smooth wavelets      1-2             Small wavelets,
           Light breeze                    Flags slightly                                                         no breaking, no
                                           waver in the wind                                                      foam
3          Gentle         3,4-5,2          Flags flap in the                  Slight               2               Large well-
           breeze                          wind                                                                   defined wavelets,
                                                                                                                  some breaking,
                                                                                                                  glassy foam,
                                                                                                                  flocks of sheep
                                                                                                                  here and there
4          Moderate       5,3-7,4          Small flags and a                  Slight to Moderate   3              Small waves,
           breeze                          pendant in streaks                                                     breaking, flocks of
                                           (stretch)                                                              sheep everywhere
5          Fresh breeze   7,5-9,8          Big flags in                       Moderate             4               Moderate waves,
                                           streaks                                                                blocks of sheep
                                                                                                                  everywhere
6          Strong         9,9-             Wind begins to                     Rough                5              Large waves,
           breeze         12,4             sing in the wires                                                      foam and spray
                                           and rigging
7          Near gale      12,5-                                               Very rough           6              Sea heads up,
                          15,2                                                                                    foam in streaks
8          ветер Gale     15,3-                                               Very rough           7
                          18,2             It is difficult to                                                     High waves, dense
9                         18,3-            walk a deck                                             7              foam, spray
           Strong gale    21,5             against the wind                   High                                impairs visibility
10                        21,6-                                                                    8              Very high
           Storm          25,1                                                Very high                           tumbling waves,
                                                                                                                  surface white with
                                                                                                                  foam, visibility
                                                                                                                  affected
11         Violent        25,2-                                                                    9
           storm          29,0                                                Phenomenal                          Exceptionally high
12                        Более                                                                    9              waves, sea
                          29,0                                                                                    covered in foam,
           Harricane                                                                                              air filled with
                                                                                                                  spray and foam,
                                                                                                                  visibility severely
                                                                                                                  impaired



                                                                    Table 2

                                                                                                                                   2
                           Beaufort scale to estimate wind force
                        Wind speed                      Wind impact on      Sea state
Wind    Word            M/s        Km/h      knots      ship and rigging
force   description
0                       0-0,2       0-1      0-1        Air is              Calm glassy
        Calm            (0)         (0)      (0)        absolutely calm.
                                                        Smoke is
                                                        vertical.
                                                        Pendant is still
1       Light airs      0,3-1,5     1-5      1-3        Light air is felt
                        (1)         (3)      (2)        from time to        Calm rippled
                                                        time. Smoke
                                                        inclines
                                                        showing wind
                                                        direction
2                       1,6-3,3     6-11     4-6        Continuous
        Light breeze    (3)         (8)      (5)        breeze. Flags       Small wavelets
                                                        and pendants
                                                        slightly waver
                                                        in the wind
3       Gentle          3,4-5,4     12-19    7-10       Flags and           Large wavelets, some
        breeze          (5)         (15)     (8)        pendants flap in    breaking, glassy foam
                                                        the wind.
                                                        Smoke is
                                                        almost
                                                        horizontal
4                       5,5-7,9     20-28    11-16                          Small waves, breaking,
        Moderate        (7)         (24)     (13)       Pendant is in a     flocks of sheep here
        breeze                                          streak              and there
5                       8,0-10,7    29-38    17-21      Big flags flap in
        Fresh breeze    (9)         (33)     (19)       the wind and        Moderate well-defined
                                                        are instreaks.      waves, flocks of sheep
                                                        Wind moves          everywhere
                                                        small objects.
6                       10,8-13,8   39-49    22-27
        Strong breeze   (12)        (44)     (25)       Wind begins to      Large waves, foam and
                                                        sing in the wires   spray.
                                                        and rigging
7                       13,9-17,1   50-61    28-33      Wind sings in       Sea heads up, foam in
        Near gale       (15)        (55)     (31)       the wires and       streaks
                                                        rigging. Some
                                                        difficulties in
                                                        walking a deck
                                                        against the wind
8                       17,2-207    62-64    34-40      Very difficult to   Higher long waves,
        Gale            (19)        (68)     (37)       walk a deck         foam in streaks
                                                        against the wind
9                       20,8-24,4   75-88    41-47      Small damage
        Strong gale     (23)        (81)     (44)       to rigging is       High waves, dense
                                                        possible.           foam, spray impairs
                                                        Unfixed objects     visibility.
                                                        move.

                                                                                             3
10                        24,5-28,4     89-102      48-55   Considerable    Very high tumbling
         Storm            (27)          (95)        (51)    damage to       waves, surface white
                                                            rigging is      with foam, visibility
                                                            possible        affected
11                        28,5-32,6     103-        56-63                   Exceptionally high
         Violent storm    (31)          117         (59)    Same            waves, sea covered in
                                        (110)                               foam, visibility
                                                                            severely impaired
12                        Свыше         Свыше Свыше                         Air filled with spray
         Harricane        >33           >117  >63           Severe damage   and foam, visibility
                                                                            severely impaired


Code. Table 3. Sea Surface State (MS).

Number     Indicators to define sea surface state
           (number of wave degree).

0          Sea surface is calm glassy

1          Ripple; small wave crests appear.

2          Small wave crests begin to break,
           however foam, which is generated, is not
           white but glassy.
3          Small waves are clearly visible, crests of
           some of them break forming here and
           there white froth – flocks of sheep.
4          Waves take a well-defined form, flocks of
           sheep are formed everywhere.
5          Crests of considerable height appear wind
           begins to tear foam away from wave
           crests.
6          Crests outline long streaks of wind
           waves.
7          Long streaks of foam torn off by wind
           cover wave slopes and in places reach
           wave hollows.
8          Wide streaks of foam cover wave slopes
           making sea surface white. Only here and
           there in wave troughs there are areas free
           of foam.
9          Sea surface is covered with a thick layer
           of foam, air is full of water spray, and
           visibility is affected considerably.




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