Reading: Chapter 8, 212-228
Chapter 9, 246-250
This is a text version of the notes presented in class.
Feel free to email the instructor (alisonjs@kent.edu) with any
comments about the format and ease of use of these online notes.
1. Sea, Sky and Land - The Climate Connection
- Oceans and Heat
- Oceans and Ice
- Air-Sea Interaction – Looking at ENSO (El Niño-Southern Oscillation)
2. . A Brief Refresher on Climate Basics: What Influences
Global Atmospheric Circulation?
- Uneven solar heating
- Rotation of the Earth (the "Coriolis effect")
- Land/sea temperature contrasts
Graphic: Earth, as viewed from Apollo 17. Image courtesy of NASA.
3. Uneven Solar Heating
Tilt of Earth's axis affects the solar energy received in the northern
and southern hemispheres and produces the seasons
Over a full year more solar energy is received in the tropics than
at the poles
Graphic: Garrison Fig. 8.6, pg. 207.
4. Solar Radiation and Heat Transport
Tropics:
- gain more heat from the sun than they lose to space
- heat surplus
Poles:
- lose more heat to space than they gain from the sun
- heat deficit
Heat is transported from the tropics to the poles to even out the surplus
and deficits
Graphic: Garrison, Fig. 8.5a and b, pg 206.
5. How is Heat Transported by the Atmosphere?
Convection currents transport heat in the atmosphere
Warm air rises, Cold air sinks
Convection currents result from this vertical motion and the horizontal
motion that closes the loop
Graphic: Garrison, Fig. 8.7, pg 208.
6. What Causes Climate?
Climate is driven by energy from the sun
Climate depends on:
- the amount of energy received
- what happens to this energy once it reaches Earth's atmosphere
7. Heat Exchange and Climate
Heat transfer between ocean and atmosphere is a primary driving force
for climate
Different climates can be produced with the same amount of incoming
solar energy
Graphics: Garrison, Fig. 8.5b, pg 206.
8. Heat Capacity
Heat needed to raise the temperature of 1 gram of a substance by 1
degree C
Substance Heat capacity (cal/g/C)
granite 0.20
dry air
0.24
pure water 1.00
Water absorbs (or releases) lots of heat with little change in temperature
Oceans store large volumes of heat and moderate climate
9. Land, Sea and Seasonal Temperature
Summer to winter temperature change:
- Smaller where the ocean influences climate
Peak summer temps:
- Occur several months after summer solstice where the ocean influences
climate
Graphic: Garrison, Fig. 6.10, pg 164.
10. Impact of Wind-Driven Ocean Circulation on Climate
Wind-driven currents move heat and influence climate
During summer:
Warm western boundary currents produce warmer air temperatures along
the east coast
Cool eastern boundary currents produce colder air temperatures along
the west coast
Graphic: Garrison, Fig. 9.14, pg 244.
11. Ice and Climate
Ice insulates the ocean from the atmosphere
Large amounts of heat moves from the ocean to the atmosphere as polar
ice forms in the winter
Ice decreases absorption of solar energy in polar areas by reflecting
energy back to space
12. The "Ice-Albedo" Feedback
- As ice melts, patches of open water develop
- These patches absorb energy and heat
- This heats the ocean, further melting the ice
13. Climate and Ice - North and South
Arctic Ocean (north) Antarctic
Continent (south)
About 2 meters of sea 1000's
of meters of ice
ice floats on the ocean rests
on the land
A small amount of heating in the Arctic can have a larger impact on
climate than a small amount of heating
in the Antarctic
14. Climate Change and the Arctic
Most climate models predict Arctic warming due to increasing atmospheric
CO2
Measurements of sea ice draft (amount of ice below the water line)
indicate less ice in the Arctic recently compared with
the 1950's through 1970's
15. Impacts of Arctic Climate Change on Global Climate
Warming or freshening the Arctic can change thermohaline circulation
This circulation moves heat from the Indian and North Pacific into
the North Atlantic
Graphic: see Garrison, Fig. 9.27, pg 256.
16. Solar Heating of Land and Sea
During the day...
- Air above land warms and rises
- Air above ocean cools and descends
- This sets up atmospheric convection and an onshore "sea breeze"
At night...
- Land cools more rapidly than ocean, sets up an offshore "land breeze"
Graphic: Garrison, Fig. 8.17 pg 216
17. Monsoons: Air-Sea Interaction on a Continental Scale
N. hemisphere summer...
- Air above land warms and rises, drawing cool, moist air onto the
continent from the ocean
N. hemisphere winter...
- Air above land cools and sinks. Dry terrestrial air is driven
offshore to replace rising air over the ocean
Graphic: Monsoon winds, also see Garrison, Fig. 8.16, pg 215.
18. Air-Sea Interaction with Global Reach - El Niño and
La Niña
- El Niño and La Niña are reorganizations of atmospheric
and oceanic circulation due to natural interactions between
the atmosphere and ocean
El Niño = warm sea surface temperatures in tropical Pacific
La Niña = cold sea surface temperatures in tropical Pacific
El Niño and La Niña impact climate globally
19. What are extreme weather events linked to El Nino?
Increased Tropical Storms in the Equatorial Pacific
Heavy rainfall along California coast-the famous California mudslides
Drought in the Sahel
Failure of the Monsoon in India
Drought in Australia and Indonesia
20. El Niño, La Niña and Society
Climate impacts last 9 months to 2 years, and affects
- Water use
- Agriculture and fisheries
- Energy use
and many other segments of society
21. Working with El Nino and La Nina
Example: Peruvian Economy
Rotation of Crops to coincide with the ENSO cycle
22. Hunting El Niño from Space
A developing El Niño or La Niña can be detected from
changes in tropical Pacific:
- sea level
- sea surface temperature
- surface winds
All of these are now measured by satellites that orbit the Earth
Next Lecture: Ocean and Climate, Part 2
ch. 18, pgs 523-529
-Climate Change and Life in the Greenhouse
Focus Question: What are natural controls of climate change?