Earth 2

Thursday, February 18th, 1999
Announcements: Test has been postponed until next Tuesday.

Lecture notes:

NATURAL VARIABILITY

Forced Climate Variations --> Volcanoes

Unforced Changes

• Odd behavior depends on how changes in the ocean and the atmosphere interact

• Easterlies and Westerlies create upwelling-->very high productivity

EAST PACIFIC

• Hi Pressure
• Low Rainfall (13mm)
• Strong Trade Winds
• Promoting Upwelling
• Nutrients-->Fish, Seals

• Low Pressure
• High Rainfall
• Weak Winds
• No Upwelled Nutrients
• No Fish
• This is what occurs during EL NINO!!!

Southern Oscillation

• Defined by Sir Gilbert Walker
• Occurs when there is high pressure in one spot and low pressure in another--looks somewhat like a wave structure
• This "wave" structure sometimes reverses--it's time scale is effected by warm pool, which occurs when the atmosphere and ocean react causing El Nino

This is known as El Nino Southern Oscillation

Teleconnection

Teleconnection--when something happening in one part of the system is transferred to another part of the system

NAO

North Atlantic Oscillation

Every once in a while...

Lessons

1) Climate System--extremely variable. Can be attributed to some change. Systems operate on different time scales.

2) Coupling Idea Produces Change

• El Nino (occurs every 5 years)
• NAO (occurs every 20, 30, and 50 years)
• Ice Cores (unsure of how often they occur)