PRINCIPAL MODES OF THE SOUTH PACIFIC SSTA IN JUNE, JULY AND AUGUST AND THEIR RELATIONS TO ENSO AND SAM

• Published in: Journal of Tropical Meteorology Vol. 19; no. 2; pp. 154 - 161
• Main Author: 孙密娜 管兆勇 张蓬勃 曹舒娅
• Format: Journal Article
• Language: English
• Published: Guangzhou Guangzhou Institute of Tropical & Marine Meteorology 01.06.2013
• Subjects: Annular; austral; ENSO; Hemisphere; Mode; Pacific; South; Southern; SSTA; winter
• ISSN: 1006-8775

The relationships of variations of sea surface temperature anomalies (SSTA) in the South Pacificwith ENSO and Southern Hemisphere Annular Mode (SAM) are examined in the present article byemploying the NCEP-NCAR reanalysis from 1951 to 2006. Two principal modes of South Pacific SSTA areobtained using the EOF (Empirical Orthogonal Function) analysis for austral winter (June, July and August).Our results suggest that EOF1 is closely related with ENSO and EOF2 links to SAM. The EOF1 varieslargely on an interannual and EOF2 on a decadal scale. The time series of coefficients of EOF1 is highlycorrelated simultaneously with Nino3 index. However, the time series of coefficients of EOF2 issignificantly correlated with the March-April-May mean SAM index. Both the EOF1 and EOF2 are found insignificant correlation to summer precipitation over China. With higher-than-normal SSTs in the easternSouth Pacific and simultaneously lower SSTs in the western South Pacific in June-July-August, thesummertime rainfall is found to be less than normal in northern China. As displayed in EOF2 of SSTA, inyears with lower-than-normal SSTs in mid-latitude southern and equatorial eastern Pacific andhigher-than-normal SSTs in the equatorial middle Pacific in March-April-May, the summer precipitation inAugust tends to be more than normal in regions south of Yangtze River.