1. CHAPTER 6 Air-Sea Interaction by Dr. Charles Dong at ECC

2. Overview Atmosphere and ocean one interdependent system
Solar energy creates winds
Winds drive surface ocean currents and waves
Examples of interactions:
El Niño-Southern Oscillation
Greenhouse effect

3. Seasons
Fig. 6-1

4. Seasons Earth’s axis of rotation tilted with respect to ecliptic
Tilt responsible for seasons
Vernal (spring) equinox
Summer solstice
Autumnal equinox
Winter solstice
Seasonal changes and day/night cause unequal solar heating of Earth’s surface

5. Uneven solar heating Angle of incidence of solar rays per area
Equatorial regions more heat
Polar regions less heat
Thickness of atmosphere
Albedo
Day/night
Seasons

6. Insert Fig. 6-3

7. Oceanic heat flow High latitudes more heat lost than gained
Due to albedo of ice and high incidence of solar rays
Low latitudes more heat gained than lost

8. Composition (dry air) Gas Percent Nitrogen (N2) 78.1% Oxygen (O2)
20.9%
Argon (Ar)
0.9%
Carbon dioxide (CO2)
0.036%
All others
Trace

9. Water vapor Cool air cannot hold much water vapor, typically dry
Warm air can hold more water vapor, typically moist
Water vapor decreases the density of air

10. Physical properties of atmosphere
Atmosphere mostly nitrogen (N2) and oxygen (O2)
Temperature profile of lower atmosphere
Troposphere – temperature cools with increasing altitude
Fig. 6.4

11. Exe 07-01
Sketch a diagram to explain the cause of seasons on the Earth.
Name two major gases in the atmosphere.
Which can hold more water vapor, cool air or warm air?
List layers generally in the atmosphere

12. Physical properties of atmosphere
Warm air, less dense (rises)
Cool air, more dense (sinks)
Moist air, less dense (rises)
Dry air, more dense (sinks)
Fig. 6.5

13. Movements in atmosphere
Fig. 6.6
Air (wind) always moves from regions of high pressure to low
Cool dense air, higher surface pressure
Warm less dense air, lower surface pressure

14. Movements in air Non-rotating Earth
Air (wind) always moves from regions of high pressure to low
Convection or circulation cell
Fig. 6.7

15. The Coriolis effect r1 r2 Which spot on earth moves the fastest?
Different latitude bands r1 r2
Which spot on earth moves the fastest?

16. The Coriolis effect on Earth
As Earth rotates, different latitudes travel at different speeds
The change in speed with latitude causes the Coriolis effect

17. Air Movement
Two air parcels are moving toward New Orleans in the Northern Hemisphere
Both air parcels curve to the right
If this were in the Southern Hemisphere they would turn left

18. The Coriolis effect The Coriolis effect
Is a result of Earth’s rotation
Causes moving objects to follow curved paths:
In Northern Hemisphere, curvature is to right
In Southern Hemisphere, curvature is to left
Changes with latitude:
No Coriolis effect at Equator
Maximum Coriolis effect at poles

19. Circulation Cells Rises at equator Descends at 30°N/S
Hadley Cell
Rises at equator
Descends at 30°N/S
Ferrel Cell
Rises at Arctic / Antarctic circle
With Hadley Cell
Polar Cell
With Ferrel Cell
Descends at pole

20. Wind Belts
Surface portion of circulation cells are effected by Coriolis
Hadley Cell
Surface wind, north to south
Bent right in NH, left in SH
NE Trade winds, SE Trade winds
Ferrel Cell
Surface wind, south to north
Prevailing westerlies
Polar Cell
Polar easterlies

21. Wind belts and boundaries
Region/Latitude
Wind belt or boundary name
Characteristic
Equatorial (0-5º)
Doldrums
Low pres. boundary
5-30º
Trade winds
Persistent easterlies
30º
Horse latitudes
High pres. boundary
30-60º
Prevailing westerlies
Mid-latitude winds
60º
Polar front
60-90º
Polar easterlies
Cool easterly winds
Polar (90º)
Polar high pressure

22. Real World

23. Exe. 07-02 What is the effect of the earth rotation called?
When an objective is thrown from the north to the south in the Northern Hemisphere, to which direction do you expect it will be deflected due to the earth rotation? How about in the Southern Hemisphere?
Sketch three atmospheric circulation cells
At places with the latitude 30 degree, what kind of weather you expect mostly?

24. Ocean weather and climate patterns
Weather – conditions of atmosphere at particular time and place
Climate – long-term average of weather
Northern hemisphere winds move counterclockwise (cyclonic) around a low pressure region
Southern hemisphere winds move clockwise (anticyclonic) around a low pressure region

25. Coastal winds Solar heating
Different heat capacities of land and water
Sea breeze
From ocean to land
Land breeze
From land to ocean
Fig. 6.13

26. Hurricane morphology and movement
Fig. 6.17

27. Hurricane destruction
Fast winds
Heavy rain
Storm surge most damaging
Historical examples:Hurricane Katrina, 2005

28. Fig. 6.18

29. Tropical cyclones (hurricanes)
Large rotating masses of low pressure
Strong winds, torrential rain
Classified by maximum sustained wind speed
Fig. 6.16

30. Ocean’s climate patterns
Open ocean’s climate regions parallel to latitude
May be modified by surface ocean currents
Equatorial regions – warm, lots of rain
Tropical regions – warm, less rain, trade winds
Subtropical regions – rather warm, high rate of evaporation, weak windsTemperate regions – strong westerlies
Subpolar regions – cool, winter sea ice, lots of snow
Polar regions – cold, sea ice, polar high pressure

31. Ocean’s climate patterns
Fig. 6.20

32. Exe 07-03 Describe how sea breeze and land breeze form.
Describe how a hurricane forms
List oceanic climate regions

33. Trace atmosphere gases absorb heat reradiated from surface of Earth
Greenhouse effect
Trace atmosphere gases absorb heat reradiated from surface of Earth
Infrared radiation released by Earth
Solar radiation mostly ultraviolet and visible region of electromagnetic spectrum
Fig. 6.24

34. Earth’s heat budget
Earth maintained a nearly constant average temperature because of equal rates of heat gain and heat loss
Fig. 6.25

35. Greenhouse gases Absorb longer wave radiation from Earth Water vapor
Carbon dioxide (CO2)
Other trace gases: methane, nitrous oxide, ozone, and chlorofluorocarbons
Fig. 6.26

36. Fig. 6.28
Fig. 6.29

37. Global warming over last 100 years
Average global temperature increased
Part of warming due to anthropogenic greenhouse (heat-trapping) gases such as CO2

38. Possible consequences of global warming
Melting glaciers
Shift in species distribution
Warmer oceans
More frequent and more intense storms
Changes in deep ocean circulation
Shifts in areas of rain/drought
Rising sea level

39. Reducing greenhouse gases
Greater fuel efficiency
Alternative fuels
Re-forestation
Eliminate chlorofluorocarbons
Reduce CO2 emissions
Intergovernmental Panel on Climate Change 1988
Kyoto Protocol 1997

40. Ocean’s role in reducing CO2
Oceans absorbs CO2 from atmosphere
CO2 incorporated in organisms and carbonate shells (tests)
Stored as biogenous calcareous sediments and fossil fuels
Ocean is repository or sink for CO2
Add iron to tropical oceans to “fertilize” oceans (increase biologic productivity)

41. Exe 07-04 What is greenhouse effect?
What is global warming? What are its consequences?
What is the role of ocean in global warming?