History---Cause---Effects on Different Parts of the World---Case Studies of South East Asia Countries

Cause of El Nino

The Southern Oscillation

This natural marvel, El Nino, could be related to a shift in the air movement over the tropical Pacific Ocean. Changes in wind direction cause the alteration in circulation and temperature of the ocean, which, in turn further disrupt air movement and ocean currents. This natural episode is the largest irregularity in the year to year fluctuation of the oceanic and atmospheric systems. It is probably caused by the interaction of the two systems. It is most likely related to the Southern Oscillation, which is an irregular oscillation of the atmospheric mass between the Indonesian low pressure system and the Easter Island high pressure system. The oscillation' period is several years.

Figure (a) shows the normal conditions, and figure (b) shows the abnormal conditions during El Nino

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