1. El Nino – Southern Oscillation - Southern Oscillation (atmosphere) - El Nino (ocean) - change in equatorial Pacific circulation - produces global climate changes - can significantly alter weather in California Geography 104 - “Physical Geography of the World’s Oceans”

2. Pacific Decadal Oscillation (PDO) variations in Pacific ocean climate on decadal scales

3. El Nino – Southern Oscillation (ENSO) variations in Pacific ocean climate on few-year scales

4. The Southern Oscillation Discovered in 1928 by Sir Gilbert Walker Proposes a zonal circulation cell over the equatorial Pacific Links changes to global climate

5. Walker Circulation East-to-west pressure gradients drive trades

6. Walker Circulation Vertical cell driven by warmest waters

7. Southern Oscillation correlation coefficients are equal in magnitude, opposite in sign

8. atmospheric pressure: Darwin vs. Tahiti

9. Southern Oscillation Index SOI = Tahiti - Darwin air pressure  ’s Low SOI = El Niño conditions

10. Southern Oscillation & warm water off S. America

12. Multivariate ENSO Index Combines observations of air pressure, zonal & meridional components of wind, sea surface temperature, air temperature and total cloudiness. Positive MEI = ENSO conditions

13. Pacific Ocean sea surface temperature

14. Western Pacific Warm Pool

15. normal equatorial conditions

17. El Nino conditions

19. El Niño Relaxation of trade winds causes warm pool to slosh esatward across Pacific

20. Fig. 8.32.b La Nina conditions

21. normal El Nino La Nina

22. normal El Nino

23. An El Niño History late 1800s Fishermen name El Niño to the periodic warm waters that appear off the coasts of Peru and Ecuador around Christmas. 1928 Gilbert Walker describes the Southern Oscillation. 1957 A large El Niño is observed which affects not just the coasts of Peru and Ecuador but the entire Pacific Ocean. 1969 Jacob Bjerknes links the Southern Oscillation with El Niño events.

24. An El Niño History 1975 Wyrtki uses island sea level to show how eastward flow causes SST’s to rise in east Pacific. 1976 An idealized computer model demonstrates that winds over the far western Pacific can change SST off Peru. 1982 A severe El Niño develops unexpectedly, but is recorded in detail with newly developed ocean buoys. 1985 Several nations launch the Tropical Ocean- Global Atmosphere (TOGA) program.

25. An El Niño History 1986 First coupled model of ocean & atmosphere predicts El Niño event. 1988 Researchers explain how the "memory" of the ocean--the lag between a change in the winds and the response of the ocean--influences terminations of El Niño and the onset of La Niña. 1996-1997 The array of instruments monitoring the Pacific, plus coupled ocean-atmosphere models, enable scientists to warn the public of an impending El Niño event.

27. La Niña El Niño Sea surface temperature: el Niño vs normal conditions el Niño Dec 1996 Dec 1997 la Niña SOI

28. Sea surface temperature: el Niño vs normal conditions normal el Niño anomaly

29. El Niño in Australia

30. http://www.charterboats-uk.co.uk/Photographs/Fish/Anchovy.gif Anchovy (Anchoa lucida - family: Engraulidae)

31. el Niño effects on Peruvian fishery

32. El Niño Temperature and Precipitation Patterns

33. La Niña Temperature and Precipitation Patterns

34. El Niño Hadley cells intensify as source of heat is now in central equatorial Pacific Jet stream intensifies & takes south path

35. El Niño in the United States

36. La Nina in the United States

37. El Niño in the United States

38. La Niña in the United States

39. El Niño effects on Southern California Bight

40. TAO-Triton mooring array http://www.pmel.noaa.gov/tao/

41. TAO-Triton mooring

42. EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION issued by CLIMATE PREDICTION CENTER/NCEP/NWS 9 October 2008 Synopsis: ENSO-neutral conditions are expected to continue into early 2009. ENSO-neutral conditions continued during September 2008, as sea surface temperatures (SSTs) remained near-average in the east-central equatorial Pacific Ocean. SSTs remained slightly below-average in the central Pacific, and slightly above-average in the eastern Pacific. From west to east, the latest weekly SST index values range from −0.2°C in the Niño- 4 region to +0.3°C in the Niño 1+2 region. The subsurface oceanic heat content (average temperatures in the upper 300m of the ocean, continued to decrease in response to the strengthening of negative temperature anomalies at thermocline depth in the east-central Pacific.

45. ENSO Summary Slide

46. Readings (Ocean and Atmosphere): Text Chapter 8 (pgs 138 – 163) Reader pgs. 51 - 61 Reader Maps pgs 200 - 204 Midterm on Wednesday 5 Nov 2008