A Preliminary Study of the Possible Statistical Relationship between the Tropical Pacific Sea Surface Temperature and the Atmospheric Circulation

Wan-Cheng Chiu Department of meteorology, University of Hawaii, Honolulu 96822

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Andrew Lo Department of meteorology, University of Hawaii, Honolulu 96822

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Abstract

The National Meteorological Center's tropical grid data together with sea surface temperature (SST) data at several Pacific stations wore used to test Bjerknes’ hypothesis that, through the mechanism of momentum transport, fluctuations of mean temperature in the tropical cast Pacific influence the sub-tropical and middle-latitude atmospheric circulations. Computed correlation coefficients indicate that the subtropical and equatorial upper tropospheric zonal wind anomalies in the eastern Pacific have a concurrent and tag (with ocean leading) relationship with SST anomalies at Puerto Chicama (in the El Niño area), but not with SST anomalies outside the El Niño area. There is also an indication of a relationship between fluctuations of the 250 mb zonal wind over the Indian monsoon area and fluctuations of SST in the El Niño area, with the former loading the latter, and a relationship between the 700 mb zonal winds in the western equatorial Pacific and SST in the El Niño area for both positive and negative lass. However, the lag-correlation coefficients between SST anomalies at Puerto Chicama and momentum transport in eastern Pacific are very small. The results of this study so far fail to confirm Bjerknes' hypothesis.

Abstract

The National Meteorological Center's tropical grid data together with sea surface temperature (SST) data at several Pacific stations wore used to test Bjerknes’ hypothesis that, through the mechanism of momentum transport, fluctuations of mean temperature in the tropical cast Pacific influence the sub-tropical and middle-latitude atmospheric circulations. Computed correlation coefficients indicate that the subtropical and equatorial upper tropospheric zonal wind anomalies in the eastern Pacific have a concurrent and tag (with ocean leading) relationship with SST anomalies at Puerto Chicama (in the El Niño area), but not with SST anomalies outside the El Niño area. There is also an indication of a relationship between fluctuations of the 250 mb zonal wind over the Indian monsoon area and fluctuations of SST in the El Niño area, with the former loading the latter, and a relationship between the 700 mb zonal winds in the western equatorial Pacific and SST in the El Niño area for both positive and negative lass. However, the lag-correlation coefficients between SST anomalies at Puerto Chicama and momentum transport in eastern Pacific are very small. The results of this study so far fail to confirm Bjerknes' hypothesis.

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