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Oceans & El Nino

Oceans & El Nino. Ocean-atmosphere coupling matters. Key Points. Climate & ocean-atmosphere coupling Seasonal heating stored in upper layers of ocean Evaporation of water to atmosphere increases with temperature The Ocean Circulation El Niño, La Niña Other Fluctuations. Evaporation.

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Oceans & El Nino

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  1. Oceans & El Nino Ocean-atmosphere coupling matters

  2. Key Points • Climate & ocean-atmosphere coupling • Seasonal heating stored in upper layers of ocean • Evaporation of water to atmosphere increases with temperature • The Ocean Circulation • El Niño, La Niña • Other Fluctuations

  3. Evaporation • Increases with temperature

  4. 0 m Mixed layer 100 m Deep ocean 3700 m Temperature Schematic Layers in the Ocean • Deep water is cold and dense • Surface warmed by sunlight and mixed by wind Horel and Geisler: Figure 4.5

  5. Sea Surface Temperature 9/24/98 Winds Courtesy WGBH The Principal Links for Climate

  6. Sea Surface Temperature • From Geostationary Satellite January, 1999

  7. Key Points • Climate & ocean-atmosphere coupling • The Ocean Circulation • Ocean basins 4 - 5 km deep • Filled with cold dense water from polar regions • Warmed from above in tropics and mid latitudes • Surface layers mixed by wind and seasonal cooling • Deep ocean overturns slowly ( ~ 2000 yr) • El Niño, La Niña • Other Fluctuations

  8. Schematic Ocean Circulation Ocean surface • residence time 2000 years Mixed layer Upwelling Downwelling Ocean bottom Low latitudes High latitudes Horel and Geisler: Figure 4.6

  9. Conveyor Belt • A schematic view of the global ocean circulation Horel & Geissler after Broecker

  10. Key Points • Climate & ocean-atmosphere coupling • The Ocean Circulation • El Niño, La Niña • Fluctuations every few years in equatorial Pacific • Feedback: ocean surface temperature ->atmospheric convection -> winds ->ocean currents -> temperature • Causes droughts and floods world wide • Other Fluctuations

  11. El Nino Normal La Nina NOAA/PMEL Equatorial Pacific Sea SurfaceTemperature Dec 97 Dec 90 Dec 88

  12. El Nino Years

  13. El Nino or La Nina? • El Nino: • Eastern and Central Pacific WARM • Indonesian rain area moves EAST • Coastal Andes: • Ocean: NO UPWELLING • Land: F LOODS • La Nina: • Eastern and Central Pacific COLD • Indonesian rain area NORMAL • Coastal Andes: • Ocean: UPWELLING • Land: VERY DRY

  14. The El Nino Feedback • Ocean-atmosphere coupling • Slackening trade winds cause surge in upper ocean water along equator • Ocean temperature anomalies persist for many months • SST anomalies change atmospheric circulation and trade winds

  15. Ocean Atmosphere - Normal • Courtesy NOOAA/PMEL

  16. Ocean Atmosphere - El Nino • Courtesy NOOAA/PMEL

  17. Associations of El Nino - 1

  18. Associations of El Nino - 2

  19. Consequences • Warm/cold winters • Floods • Droughts

  20. Vegetation Stress • El Nino (top) • La Nina (bottom)

  21. A TAO Buoy • Pacific Marine Environmental Laboratory

  22. In between. Neither El Niño nor La Niña TAO Array Current Status 10/11/00

  23. Current Status 2/13/00 • La Nina persists National Oceanic and Atmospheric Administration

  24. Sea SurfaceTemp-erature Strength of trade winds A historical perspective PMEL

  25. Key Points • Climate & ocean-atmosphere coupling • The Ocean Circulation • El Niño, La Niña • Other Fluctuations • Pacific Decadal Oscillation • Salmon catches, Alaska - California • North Atlantic Oscillation • Rainfall in Sahel • Drought in N.E. Brazil

  26. Warm Pacific Decadal Oscillation • Cool Mantua et al

  27. Mantua et al Black Warm PDO Grey Cool PDO SelectedPacific Salmon Catches

  28. Key Points • Climate & ocean-atmosphere coupling • The Ocean Circulation • El Niño, La Niña • Other Fluctuations

  29. Sources of Information • Horel & Geisler Chapter 3, 4 • http://www.pmel.noaa.gov/toga-tao/el-nino • http://www.sacbee.com/news/projects/gathering_storm/day1.html • http://www.check6.com • http://www.iphc.washington.edu:80/PAGES/IPHC/Staff/hare/html/papers/pdo/PDO.html

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