Meredith TaghonPhysical Oceanography Fall 2015

Bigger Stronger Faster: Current El Niño

http://www.theweathernetwork.com/us/news/articles/winter-preview-el-nino-contributes-to-a-tale-of-two-seasons/56531/

• “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 12-18 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)

http://www.pmel.noaa.gov/tao/jsdisplay/plots/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

http://www.pmel.noaa.gov/tao/elnino/report/figure17b.html

Current El Niño vs. Prior El Niños

http://www.esrl.noaa.gov/psd/enso/mei/index.html#data

• 6 MEI multivariates: • Northwest of Australia: very high P• Northeast of Australia: very strong Vs

• Along Equator: Uw • 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

http://www.mapsofworld.com/projection-maps/

http://losangeles.cbslocal.com/2015/10/15/el-nino-forecast-to-bring-50-percent-more-precipitation-to-california/

• “Definitions of El Nino, La Nina, and ENSO.” Tropical Atmospheric Ocean Project. National Oceanic and Atmospheric Administration, November 2015. Web. 27 November 2015. http://www.pmel.noaa.gov/tao/elnino/el-nino-story.html

• “El Niño/ENSO.” Atlantic Oceanographic and Meteorological Laboratory: Physical Oceanography Division. National Oceanic and Atmospheric Administration, 2 October 2007. Web. 28 November 2015. http://www.aoml.noaa.gov/phod/faq/enso_faq.php

• “Multivariate ENSO Index (MEI).” Earth System Research Laboratory. National Oceanic and Atmospheric Administration, November 2015. Web. 27 November 2015. http://www.esrl.noaa.gov/psd/enso/mei/index.html#discussion

• Sutherlan, Scott. “As 2015 tops 5-yr record, El Niño may push 2016 even hotter.” The Weather Network. 28 November 2015. Web. 29 November 2015. http://www.theweathernetwork.com/us/news/articles/2015-tops-5-yr-heat-record-el-nino- may-push-2016-even-hotter-wmo/60387/

• “WMO: 2015 likely to be Warmest on Record, 2011-2015 Warmest Five Year Period.” World Meteorological Organization. 25 November 2015. Web. 27 November 2015. https://www.wmo.int/media/content/wmo-2015-likely-be-warmest-record-2011-2015-warmest-five-year-period

References

True/False: Days are longer as a result of El Niño events.