HR: 08:40h
AN: PP51A-03 INVITED     [Abstracts]
TI: El Nino Studies In Mexico
AU: * Magaña, V
EM: victormr@servidor.unam.mx
AF: Universidad Nacional Autonoma de México, Centro de Ciencias de la Atmósfera, UNAM, Mexico CIty, DF 04510, Mexico
AB: Since El Niño was found to be an important modulator of interannual climate variability in the tropics and subtropics, numerous studies have documented its signal in various meteorological parameters and various regions of the world. Mexico has also been part of this effort to determine to what extent El Niño may be responsible for some of the climatic disasters in recent years. The analysis of El Niño signal in Mexico has been divided in two seasons: winter and summer. During winter, El Niño triggers the Pacific North American (PNA) pattern that modifies the mean atmospheric circulation. This anomalous mean flow leads to more frequent midlatitude systems reaching low latitudes. During El Niño, some of these extratropical cyclones result in an enhanced number of the so-called Nortes and consequently in more extreme events. During summer, El Niño affects the seas surface temperatures of the warm pools surrounding Mexico and Central America. The result of warmers than normal SSTs in the north eastern Pacific is a weaker temperature gradient between the cold tongue off Peru and the warm pool of the Pacific coast of Mexico. This causes the ITCZ to remain closer to the equator and enhanced subsidence over most of the country. Such combination of circulation anomalies translates in drought over most of Mexico during summer. However, El Niño may have effects on the Caribbean Sea climatic conditions and consequently in Mexico´s climate, since easterly waves and tropical cyclone activity may be modified. The potential mechanisms of the El Niño related processes that may lead to climate anomalies over Mexico are discussed, including the roles of quasi-stationary circulations, subsidence and transient activity in observations and models.
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 4522 ENSO (4922)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly