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El Nino Teleconnections

El Nino Teleconnections. Philip Kreycik EPS 131 4/30/04. El Niño - What it is. Periodic anomaly in climate conditions Irregular period Centered in Tropical Pacific Local SST changes, surface pressure change Local and Global consequences South American floods African droughts

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El Nino Teleconnections

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  1. El Nino Teleconnections Philip Kreycik EPS 131 4/30/04

  2. El Niño - What it is • Periodic anomaly in climate conditions • Irregular period • Centered in Tropical Pacific • Local SST changes, surface pressure change • Local and Global consequences • South American floods • African droughts • North American rains

  3. ’97-’98 El Niño Beginning to Peak Fig. From JPL

  4. Walker Circulation Fig. From the Australian Bureau of Meteorology

  5. El Niño- what causes it • We’re still uncertain • Atmosphere is a chaotic system • Difficult to sort out causes and effects • Pressure seems to be the driving force • Slackening of trade winds impacts temp. profile in ocean • But what causes changes in the trans-Pacific pressure gradient?

  6. Attempts to Predict and Prepare Fig. From Natl. Geographic online

  7. Southern Oscillation Index (SOI) • Oscillation in pressure difference across tropical Pacific • Normalized to the average difference • + means La Nina • - means El Niño

  8. Recent SOI Values

  9. Teleconnections- Floods • Deep Convection- the mechanism • NW Peruvian Coast • Sechura Desert • Southern Brazil • Europe • Implications for human health • Food resources • Disease

  10. Teleconnections- Drought • Shifting Walker Circulation shifting wet and dry areas • Africa, India, Polynesia, Australia, New Zealand Photo from the Royal Society of New Zealand

  11. North American Teleconnections “Hurricane Linda, spawned during an El Niño, churns northeastward in September 1997. Linda’s 185-mile-an-hour [298-kilometer-an-hour] winds made it one of the strongest eastern Pacific storms ever recorded” Photo and caption from Natl. Geographic

  12. Teleconnections- N. American Storms and Rain Fig. from the NOAA

  13. North American Monsoon • Christopher Castro et al. “The Relationship of the N. Am. Monsoon to Tropical and N. Pacific SST as Revealed by Observational Analyses” • Highly variable period of wet weather • Short bursts of intense precipitation

  14. Western US Sensitivity to ENSO • Not as simple as the NOAA diagram makes it seem! • Dependence on several oscillating systems • ENSO • NPO • Others • Relative phases

  15. ENSO and the N. Pacific Oscillation • NPO high, El Nino phaseconstructive interference • cold central Pacific, warm East Pacific • Strong effect on N. Am. monsoon • NPO low, El Nino phasedestructive interference

  16. Some Results

  17. Final conclusion of the study • Moisture drawn in from Gulf of Mexico • Low pressure displaced to lower lat. in El Nino • Circulation around pressure system • Predictive power still leaves something to be desired

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