Meredith Taghon Physical Oceanography Fall 2015 Bigger Stronger Faster: Current El Niño

“Christ child” Coupled ocean-atmospheric phenomenon Characterized by warm southward flowing currents in the Equatorial Pacific ocean and weakening of the trade winds Irregular intervals of 2-7 years, but occurs on average every 3-4 years Last around months In occurrence for thousands of years according to tree rings and other geological evidence (AOML) El Niño is associated with changes in the Southern Oscillation, but they are NOT the same! High atmospheric sea level pressures in western tropical Pacific + Indian Ocean; low sea level pressures in southeastern tropical Pacific Definition and Detection

Atmospheric Process Weakening of trade winds in central and west Pacific regions El Niño Cause and Effect Oceanic Process Thermocline: depression in east, elevation in west Reduced upwelling efficiency Higher sea surface temperature (S) /data-access/EQSST_xt.gif

Cause and Effect Cont’d Atmospheric Process Weak easterly trade winds Oceanic Process Warm water moves eastward Easterly-displaced atmospheric heat source Huge changes in global weather patterns

Current El Niño vs. Prior El Niños

6 MEI multivariates: Northwest of Australia: very high P Northeast of Australia: very strong V s Along Equator: U w Central + eastern equatorial Pacific: S and A Dateline region of southern tropical Pacific: C Precipitation: Lower rainfall in large areas of Central America (including Amazon region), Caribbean, and India (monsoon rainfall has been 86% of expected values [WMO]); dryness has contributed to increased wildfires in Indonesia Argentina and Peru: increased rain and flooding Current Global Impact percent-more-precipitation-to-california/

“Definitions of El Nino, La Nina, and ENSO.” Tropical Atmospheric Ocean Project. National Oceanic and Atmospheric Administration, November Web. 27 November “El Niño/ENSO.” Atlantic Oceanographic and Meteorological Laboratory: Physical Oceanography Division. National Oceanic and Atmospheric Administration, 2 October Web. 28 November “Multivariate ENSO Index (MEI).” Earth System Research Laboratory. National Oceanic and Atmospheric Administration, November Web. 27 November Sutherlan, Scott. “As 2015 tops 5-yr record, El Niño may push 2016 even hotter.” The Weather Network. 28 November Web. 29 November may-push-2016-even-hotter-wmo/60387/ “WMO: 2015 likely to be Warmest on Record, Warmest Five Year Period.” World Meteorological Organization. 25 November Web. 27 November warmest-five-year-period References True/False: Days are longer as a result of El Niño events.