Different types of La Niña events and different responses of the tropical atmosphere
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Historical La Niña events since 1950 are divided into Eastern Pacific (EP) type and Central Pacific (CP) type, and the SSTA developing features as well as the different responses of the tropical atmosphere are further analyzed by using multiple datasets. Classification of different types La Niña is based on the normalized Niño3 and Niño4 indices and the SSTA distribution pattern during the mature phase. The minimum negative SSTA for CP La Niña is located over the equatorial central Pacific near the dateline, more westward than that of EP La Niña. It has stronger intensity and larger east-west zonal difference of SSTA over the equatorial Pacific than EP La Niña. Influenced by the different SSTA distribution pattern, CP La Niña induces more westward location of the anomalous sinking motion and the anomalous low-level divergent and high-level convergent winds over the equatorial eastern Pacific. The different response of the tropical atmospheric circulation between EP and CP La Niña is more significant in the upper troposphere than in the lower troposphere. However, the tropical precipitation patterns during the mature phase of EP and CP La Niña are much similar, except the less (more) precipitation over the equatorial central Pacific (eastern Indian Ocean-western Pacific) during CP La Niña than during EP La Niña.
KeywordsLa Niña Eastern Pacific (EP) type Central Pacific (CP) type tropical atmosphere Walker circulation precipitation
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