Two Types of Mid-Latitudes Responses during La Niña

[摘要] La Niña cases that occurred after 1948 are classified into cold and non-cold winters in the Far East to investigate the formation of disparate teleconnection patterns corresponding to the two types and to compare with those during El Niño. According to composite analyses using reanalysis datasets, the North Pacific Oscillation (NPO)/western Pacific (WP) pattern (NPO/WP pattern) and the Pacific-North American (PNA) pattern dominate in the cold and non-cold winters, respectively. As during El Niño, modulations of the local Hadley circulation associated with La Niña play an important role in the formation of the teleconnection patterns. These results indicate that the formation mechanisms of teleconnection patterns during La Niña are the same as those during El Niño but are not simple reverse signals.