Bigger Stronger Faster:
Current El Niño
Meredith Taghon
Physical Oceanography Fall 2015
http://www.theweathernetwork.com/us/news/articles/winter-preview-el-nino-contributes-to-a-tale-of-two-seasons/56531/
Definition and Detection
• “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
El Niño Cause and Effect
• Atmospheric Process
• Weakening of trade
winds in central and
west Pacific regions
• 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
Current Global Impact
• 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
http://www.mapsofworld.com/projection-maps/
• 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
http://losangeles.cbslocal.com/2015/10/15/el-nino-forecast-to-bring50-percent-more-precipitation-to-california/
References
• “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-ninomay-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-2011-2015warmest-five-year-period
True/False: Days are longer as a result of El Niño events.