Variations of zonal mean sea surface temperature and large‐scale air‐sea interaction

Abstract

AbstractTwenty‐four years data of zonal mean sea surface temperature (SST) were assembled to examine the seasonal and nonseasonal variations of SST. Outside the tropics, annual and semi‐annual variations of SST dominate, accounting for over 90% of the variance. In the tropics, the nonseasonal variation of SST is dominated by low‐frequency variations with periods longer than 3 years in the Pacific. Variations with periods of 24–32 months account for more than 10% of the variance in the tropical Atlantic from 25 £N to 10 £S and in the equatorial Pacific from 0–10 £S. An empirical orthogonal function (EOF) analysis showed that the major global pattern of zonal mean SST variations is dominated by variations in the equatorial eastern Pacific which precede zonal mean SST variations elsewhere. The time series of this EOF is found to be correlated with an index of the Southern Oscillation. The maximum correlation coefficient is −0£61, with the index leading by 2 months. Finally, the relation between SST and tropical tropospheric temperature (TTT) is examined. SST variations in the Atlantic and in the Indian Ocean are almost contemporary with variations in TTT. Possible explanations for the 1–2 seasons lead time between SST and TTT as found in earlier studies are suggested.