Cyclones have increased in the Pacific whereas the last Atlantic hurricane season showed a decrease in events. El Niño, this ocean/climate phenomenon, is back -- wreaking havoc on climate worldwide.
For centuries, Peruvian fishermen have feared the sea warming called El Niño which, every few years, around Christmas, drastically reduces their fishing catches. These El Niño events are part of a broader disruption to normal weather patterns which causes drought, flooding and hurricanes around the world. In the tropical Pacific, ocean and atmosphere circulations are closely linked, each reacting quickly to changes in the other.
Particularly strong El Niño events were observed in 1982-1983 and 1987-1988, leading to the realisation that it was absolutely essential to monitor the Equatorial Pacific and forecast this phenomenon. A smaller episode was observed in 1993-1994, before the El Niño of the (twentieth) century was observed in 1997-98. From then on (2002, 2004 and 2009), the observed El Niño were mostly of a moderate strength, positioned around the Central Pacific rather than along the American coasts as is typical of El Niño events. This is why these episodes are known as El Niño "Modoki" (meaning "similar but different" in Japanese).
Since the 1990s, an in-situ observation system has been implemented in the Pacific and new altimetry satellites have continuously scanned the global ocean (at the moment, Jason-2, Jason-1 and Envisat). These observation systems contribute to test and refine our knowledge of ocean-climate interactions and numerical models of the climate. The 1997-98 El Niño was the first closely monitored event, especially by Topex/Poseidon; for the first time, global-scale seasonal forecasts were produced.
Though we cannot avoid El Niño's whims, we can predict and mitigate its impacts. Setting up an early warning/alert system is important for all phases of natural hazard management, from outreach and education to danger prepartions. MyOcean is an important initiative in this respect, since it organises the global ocean monitoring and forecasting system at the European level.
MyOcean is a European project dedicated to operational oceanography. MyOcean Service provides the best information available on the ocean, on both large and regional scales (European seas), based on the combination of satellite and in-situ observations and their use in models: temperature, salinity, currents, ice extent, sea level, primary ecosystems, ...
In early summer 2009, forecast models predicted a moderate El Niño event for the autumn. Sea surface height positive anomalies are measured by altimetry satellites from August 2009 with a maximum during December 2009. These conditions are weakening to normal conditions during the first half of 2010.
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