OCEAN LAB 03 ATMOCNcirculation by tyC9OW

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Oceanography Lab 5—Atmospheric and Oceanic Circulation




We will be referring to web activities at www.wcc.hawaii.edu/facstaff/miliefsky-m/ ocean
lab 5 folder to view color images for the following assignment.

Background:

Plotting ocean buoy data to show surface currents

Data in Table 1 below are from drifter buoys in the North Pacific Ocean. Released into
the ocean, the buoys float with the currents and take measurements of the water with
built-in instruments. They are tracked by satellites in orbits far above Earth and transmit
data several times a day. Ships and airplanes can drop these low cost (~$4500) and
durable buoys into the sea. When released by ships, they have a 98% survival rate;
from the air, survival drops to 78%. About half of the drifters lose their ability to
communicate with the satellite, for one reason or another, after 440 days. Other buoys
last longer and transmit their information for several years.

The floater at the top of the buoy sits at the surface of the water and holds an antenna
for sending data to a satellite above. Drogues well below the surface cause the ocean
currents to take the buoy along instead of the surface wind (Figure 1 below). The buoy
also holds electronic instruments for measuring sea surface temperatures (SST),
submergence, irradiance (for sunlight) and barometric pressure. At the top is another
device for measuring temperature and conductivity (used to calculate salinity).
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1. (a.) Plot the 1995 data from 3 buoys in the North Pacific (Table 1) on the Pacific
Ocean Map (Fig. 2). Use longitude and latitude data to plot the position of each buoy
location during the year; then connect the locations with lines and draw an arrow to
show the direction of motion.

NOTE: Longitudes with a negative number are on the west side of the prime meridian
and those with a positive number are on the east side of the prime meridian. Latitudes
are in the northern hemisphere.




TABLE 1. NORTH PACIFIC BUOY DATA

Buoy no                   Position day       Latitude         Longitude

12410                     27 Feb 95          30.1             -123.7

12410                     28 Mar 95          27.5             -121.8

12410                     22 Apr 95          25               -124.6

12410                     22 May 95          23.6             -128

12410                     24 June 95         22.5             -133.9

12410                     24 July 95         23.1             -138.4

12410                     26 Aug 95          20.5             -145.4

12410                     25 Sept 95         20               -147.6

12410                     20 Nov 95          17.9             -155.3

12410                     18 Dec 95          21.4             -159.5

15022                     25 Feb 95          10.7             162

15022                     27 Mar 95          10.5             152.1

15022                     23 Apr 95          11.6             145.5

15022                     20 May 95          12.4             137.6

15022                     25 June 95         17               131.1

15022                     22 July 95         21.7             127.8

15022                     27 Aug 95          33               141.6
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Buoy no                    Position day       Latitude          Longitude

15022                      23 Sept 95         37                147.8

15022                      23 Oct 95          39.3              152

15022                      25 Nov 95          40.1              154.5

15022                      31 Dec 95          37.6              160.4

22217                      27 Feb 95          51.2              -162.7

22217                      27 Mar 95          50.4              -165.3

22217                      24 Apr 95          48.7              -159.5

22217                      29 May 95          50.7              -155.1

22217                      26 June 95         50.4              -151.7

22217                      24 July 95         51.5              -149.3

22217                      28 Aug 95          51                -145

22217                      25 Sept 95         53.1              -143.8

22217                      23 Oct 95          55.2              -139.1

22217                      27 Nov 95          57.1              -141.4

22217                      18 Dec 95          56.9              -141.7



(b.) Refer to the Fig. 1. Map of Surface Currents

What are the names of the surface currents that moved the buoys whose courses
you plotted?

Buoy 12410:

Buoy 15022:

Buoy 22217:

 (c.) The currents plotted in a.) are all part of the North Pacific gyre, a clockwise-moving
current that redistributes heat in the North Pacific.

1. Name the four surface currents that make up the N. Pacific Gyre.

2. What is the name of the current that moves cold water?
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PART 2A :

Investigating atmospheric circulation and surface currents---the Topex/Poseidon
mission

A joint effort between NASA and the French space agency to study Earth's oceans, the
TOPEX/POSEIDON mission will observe the global ocean circulation for 3-5 years. The
oceans play a fundamental role in maintaining the habitable climate we experience on
Earth by transporting an enormous amount of heat through large-scale circulation
systems. Understanding the dynamics of ocean circulation and the role this circulation
plays in climate change is the main goal of the TOPEX/POSEIDON mission. The
satellite travels in an orbit that allows coverage of 95% of the ice-free oceans every 10
days. The satellite measures sea levels, current variations, effects of currents on global
climate change, and provides information about tides, waves, and wind. The images are
"false color" images. That is, different measured values have been assigned different
colors to make them easier to see. Note that when images are labeled winter or
summer, this refers to the Northern Hemisphere perspective.



2. The satellite images below show the amount of water vapor in the atmosphere, which
is heated indirectly. First, the sun heats ocean water, some of which evaporates and
rises. As the air rises, it cools and condenses, thus releasing heat into the atmosphere.
This process is called latent heat. The TOPEX/POSEIDON satellite is able to measure
the amount of water vapor in the air, an indication of where and how much air is rising.
Understanding the transfer of heat by this process is important to understanding the
overall heat balance of Earth.

The Atmospheric Circulation diagram (Fig. 5) shows generalized wind patterns on
Earth's surface. It does not account for the influence of continents. A persistent low
pressure zone is created over the equator (ITCZ), where massive amounts of
evaporation cause air to rise. The solid lines and arrows show generalized wind
patterns on Earth's surface. The dotted lines and arrows show how the lower
atmosphere circulates (above Earth's surface). For example, air is shown rising over the
ITCZ (low pressure zone) and falling over the subtropical high pressure zone (around
30 degree N and S latitude).
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Fig. 6 water vapor content Jan 2003
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(a.) Where are the areas of highest water vapor content in the atmosphere (Fig. 6)
and how do these areas correlate to the climate belts shown in the Atmospheric
Circulation Diagram (Fig. 5)?

(b.) Where are the areas of lowest water vapor content and how do these areas
correlate to the climate belts shown in the Atmospheric Circulation Diagram (Fig. 5)?

(c.) Compare the winter and summer images. How do the locations of high and low
atmospheric water vapor change from summer to winter (Northern Hemisphere
perspective) Fig. 7 & 8?




Fig. 7 Atmospheric water vapor data from Aug. 5, 2005 Northern Hemisphere Summer
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Fig. 8 Atmospheric water vapor data from Dec. 22, 2005 Northern Hemisphere Winter

3. The two satellite images show world-wide wind speeds during the Northern
Hemisphere summer (Fig. 9) and winter (Fig.10). The winds drive surface currents and
also create waves that move energy across the ocean's surface. See wave height
variations in the world ocean during the Northern Hemisphere summer (Fig. 11) and
winter (Fig.12) .




Fig 9. Wind speed data (in m/sec) on Aug. 5, 1995 (N. hemisphere summer)
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Fig. 10. Wind speed data (in m/sec) on Dec. 22, 1995 (N. hemisphere winter)




Fig. 11 Wave height data Aug. 5, 1995 (N. hemisphere summer)
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Fig. 12. Wave height data Dec. 22, 1995 (N. hemisphere winter)




(a.) Where are the areas of high speed and low speed surface winds (Fig. 9 &10) and
how do these areas correlate to the wind belts shown on the Atmospheric Circulation
Diagram (Fig. 5)?



summer high-speed winds:



summer low-speed winds:



winter high-speed winds:



winter low-speed winds:

(b.) Where are the areas of large waves and how do these areas correlate to wind
speeds?

summer:

winter:
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PART 2B:

Investigating atmospheric circulation and surface currents---other satellite imagery

Sea-surface temperatures (SSTs) are easily measured by satellites and can show the
locations of currents that move across the ocean's surface. The following images show
examples of Earth's major currents, delineated by measured differences in sea-surface
temperatures.



4. Figure 13 below shows sea-surface temperatures (SSTs) for the entire world ocean
in July 2008. Temperatures are in degrees Celsius.




Fig. 13. Sea surface temperature (SST) for July 2008

(a.) Describe the general pattern of sea surface temperatures in the ocean.

(b.) Examine the zone of warm water along the equator.

Why does this zone widen to the west in each ocean; for example, in the Pacific
Ocean? (Hint: look at the Atmospheric Circulation Diagram and the Surface Current
Map.) Perturbations to this pattern are involved with the El Niño climatic condition.
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5. Fig. 14 below uses sea-surface temperature measurements to illustrate the location
of the Kurishio current. The Kurishio current is called a western boundary current (it
moves along the west side of an ocean). Sea-surface temperatures are in degrees
Celsius.




Fig. 14. SST Kurishio Current

(a.) What is the geographical location of the Kurishio Current?



(b.) Is the Kurishio Current a warm-water or a cold-water current? [Provide a
temperature range.]
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(c.) Do you see any evidence for the influence of another current? If so, what is
its name and its temperature? Refer to the Surface Currents Map.

6. The figures below use sea-surface temperature measurements to show another
western boundary current, the Gulf Stream. The two images show data collected 6 days
apart, on 19 February (Fig. 15) and 25 February (Fig. 16) in 1996. Major currents such
as the Gulf Stream can be compared to rivers in the ocean, although they can transport
incredibly huge amounts of water from place to place. For example, the Gulf Stream
transports more than 150 million cubic meters of water per second, compared to a flow
of 0.6 meters per second for all of the rivers that flow into the Atlantic Ocean. On these
images the Labrador Current, as well as the Gulf Stream Current, is visible.




Fig. 15. SST from 19 February 1996. Degrees in Celsius.
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Fig. 16. SST from 25 February 1996. Degrees in Celsius.

(a.) What is the temperature range of the Gulf Stream current?

(b.) What is the temperature range of the Labrador current?

(c.) Describe what changes occur in the currents during the 6-day period between the
two images. For example, notice what happens with the ring of Gulf Stream water
enclosed in the colder water.
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(d.) Describe the boundaries of the Gulf Stream. For example, are they sharp or
diffuse; straight or meandering?



7. Figure 17 shows sea-surface temperatures of the Agulhas Current at the tip of Africa.
Measurements were collected by satellite in 21 February 1996.




Fig. 17. SST of Agulhas Current from Feb. 21, 1996.

Explain the distribution of water temperatures visible on this image in the context
of the currents that affect this part of the world. Refer to the Surface Currents
Map. Because the east side and west coasts of South Africa are effected by
currents of different temperatures, they have quite different climates.
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PART 3:

Vertical structure of the ocean

We have looked at evidence for horizontal currents that move along the surface of the
ocean to redistribute heat. Vertical currents also move water from place to place.
Upwelling currents driven by the wind are one mechanism for bringing deeper water to
the ocean surface. Vertical motions can also be induced by density instabilities in the
water column. An unstable water column occurs where denser water overlies less
dense water. Throughout much of the ocean, vertical motions are inhibited by a stable
density structure.

In the open ocean, temperature has the largest effect on water density. Based on
temperature variations, the ocean can be divided into three depth zones:

(A) Mixed or surface zone of uniformly warm water.

(B) Thermocline where temperature decreases rapidly.

(C) Deep zone of uniformly cold water.

The three zones produce a stable water column where less dense (warm) water
overlies more dense (cold) water. It is primarily at high (polar) latitudes, where the three
zones are poorly developed, that the density instabilities that stimulate vertical motions
occur.



8. The graphs below show water-temperature measurements sampled in a vertical
column along the equatorial Pacific Ocean, at 110 W longitude, 140 W longitude, and
180 W longitude. See a world map for sampling locations. The data were collected on
22 and 23 February 1996. Four to six sampling sites are included on each diagram. The
sites range from 9 degrees North to 8 degrees South Latitude.
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Graph 1. Pacific Ocean water temperature measurements for 110 W longitude
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Graph 2. Pacific Ocean water temperature measurements for 140 W longitude
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Graph 3. Pacific Ocean water temperature measurements for 180 W longitude

(a.) On a paper copy of the graphs, mark the depths of the boundaries between
the surface zone, thermocline, and deep zone. Label the 3 zones.

(b.) What changes do you observe from east to west along the equator in the
Pacific Ocean? Why do you think these changes occur? (Hint: this reason is similar
to the reason for your observations in question 5.)
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Part 4. Explore the world of ocean topography from space
with this 3D interactive viewer from the Jet Propulsion Laboratory.

4A.http://climate.jpl.nasa.gov/

       4A-1. What is Jason I?

       4A-2. What does TOPEX Poseidon measure?

       4A-3. How often does El Nino occur?

       4A-4. What impact does El Nino have on our climate?

       4A-5. What level on the Richter scale was the Sumatran earthquake?



4B. Sea level viewer:
http://climatechange.jpl.nasa.gov/SeaLevelViewer/seaLevelViewer.cfm

       4B-1. What percentage of ice was lost in the Arctic from 1979 to 2007?

       4B-2. Which countries ice sheet, if melted, would cause a 5-7 meter rise in sea
       level?

       4B-3. How much has sea level risen since 1992? over this century?

       4B-4. What is our current CO2 level?

       4B-5. When in our past were levels this high?

       4B-6. What has been our average temperature change since 1895?

       4B-7. Is the ozone hole growing or shrinking?

       4B-8. What is ozone and how does it help our planet?

       4B-9. What destroys ozone?



4C. Climate Time machine:
http://climate.jpl.nasa.gov/ClimateTimeMachine/climateTimeMachine.cfm



4D. Global Change Theater: http://climate.jpl.nasa.gov/videos/index.cfm
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Part 5. Sea Level rise in Hawaii SOEST’s Chip Fletcher

http://www.soest.hawaii.edu/coasts/sealevel/index.html

Watch the movie:

      The 1 m contour at high tide - the "Blue Line Project"

      Salt water flooding through storm drains in Mapunapuna

      Model of Sea-level rise, coastal erosion, and wave overtopping in
       Waimanalo

      Waikiki flooding under 1m of sea level rise



Part 6. Earth Science Highlights:

http://svs.gsfc.nasa.gov/stories/earth_sci_20040422/index.html

Watch the movie:

      SEASONS OF CHANGE: EVIDENCE OF ARCTIC WARMING GROWS

      THE CASE OF SOOT AND RECEDING ICE
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Fig. 18. SST for July 19, 2008.

Web site for current SST: www.skypoint.com/members/benhuset/wx.htm




Reference:

(http://funnel.sfsu.edu/courses/geol103/labs/currents/currents.home.html)
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Fig. 1. Surface Ocean Currents
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180 165 150   135 120   105   90   75   60   45   30   15   0   15   30   45   60   75   90   105   120 135   150 165 180
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                                                                                                                                 Fig. 2
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Fig. 3 Status of Global Drifter Array Feb. 12, 2007
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Fig. 4 Status of Global Drifter Array May 9, 2011
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Fig. 5 Atmospheric Circulation Diagram

								
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