El Nino Defined: a global coupled ocean-atmosphere phenomenon In the Pacific ocean, El Nino (“the little boy”) and La Nina (“the little girl”) – noticed off the west coast of South America around Christmas time first in 1923. El Nino – warming of the equatorial Pacific waters; seems to occur once every 3 to 7 years La Nina – cooling of the equatorial Pacific waters
What and how do we know? El Niño as a physical occurrence is a proven fact. The way it works is a theory. Difficult to predict start of cycle but fairly good skill in forecasting next 6 to 9 months ahead -Monitoring with satellites -Buoys measure sea surface temps, waves, winds, and ocean currents -Reports from ships at sea El Niño as a physical occurrence is a proven fact. The way it works is a theory. Difficult to predict start of cycle but fairly good skill in forecasting next 6 to 9 months ahead -Monitoring with satellites -Buoys measure sea surface temps, waves, winds, and ocean currents -Reports from ships at sea
Global SST Departures ( o C) Equatorial SSTs remained below-average in the central and east-central Pacific Ocean, and above-average in the western Pacific, Atlantic and central Indian Ocean. Positive anomalies covered much of the North Atlantic and western North Pacific Oceans.
Central & Eastern Pacific Upper-Ocean (0-300 m) Weekly Heat Content Anomalies January 2007 to April 2008: below average May 2008 to mid-August 2008: above average Mid-August 2008 to Current: below-average
El Nino Oscillation since 1950 The most recent ONI value (July– September 2008) is 0.0 o C. El Niño La Niña neutral
1997-1998 El Nino Strongest on record, developing more rapidly than any other El Nino in past 40 years. July 1997: record high sea-surface temps in the Pacific Ocean. Fall 1997: record flooding in Chile, Marlin caught off coast of Washington, extensive smog cloud over Indonesia, quiet Atlantic hurricane season. Winter 1997-98: heavy rains southern US, unusually mild Midwest winter, record rains in California and Florida.
Forecasts indicate NEUTRAL conditions will continue through Northern Hemisphere Summer 2009. Several dynamical models suggest weak La Niña conditions during the Winter of 2008-09 El Niño Outlook Figure provided by the International Research Institute (IRI) for Climate and Society (updated 24 October 2008).
SST Outlook: NCEP CFS Forecast Issued 26 October 2008 The CFS ensemble mean (heavy blue line) indicates La Niña conditions through mid- 2009.
U. S. Seasonal Outlooks November 2008 – January 2009 TemperaturePrecipitation These seasonal outlooks combine long-term trends and soil moisture effects.
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