How does ENSO affect the distribution of rainfall?

Question

Olivia Akins · Accepted Answer

See below.

ENSO has two forms: La Niña and El Niño. Both La Niña and El Niño refer to changes in temperature between the sea surface and the atmosphere in the east-central Pacific.

El Niño is the warming phase where sea surface temperatures are warmer in the central-eastern Pacific. In South America, warmer and wetter months occur during an El Niño. California also experiences increased rainfall during El Niño. Australia and Southeast Asia are drier than normal.

La Niña is the cold phase where cooler ocean temperatures are found in the central-eastern Pacific. In Southeastern Asia, La Niña causes heavy rains. Ecuador and Peru, which were wet during El Niño, are dry. The midwestern US experiences drier summers and wetter winters during La Niña.

You can read more about ENSO and precipitation here.

Nathan Abbe · Answer

undefined The El Niño-Southern Oscillation (ENSO) affects the distribution of rainfall by altering atmospheric circulation patterns and sea surface temperatures in the tropical Pacific Ocean. During El Niño events, warmer-than-average sea surface temperatures in the central and eastern Pacific Ocean lead to changes in atmospheric circulation, resulting in a weakening of the Walker Circulation and a shift in the location of convection and precipitation patterns. This often leads to decreased rainfall in the western Pacific, including parts of Australia and Indonesia, and increased rainfall in the central and eastern Pacific, along the west coast of South America. Conversely, during La Niña events, cooler-than-average sea surface temperatures in the central and eastern Pacific Ocean strengthen the Walker Circulation, leading to increased rainfall in the western Pacific and decreased rainfall in the central and eastern Pacific.