A statistical study of synoptic storm activity over the north Pacific in 1975

Abstract

A statistical analysis was made of the 00 and 12 GMT surface wind analysis prepared by Fleet Numerical Weather Central (FNWC) during 1975 to describe the synoptic storm activity over the North Pacific Ocean. Temporal variance of the surface wind components at each individual grid point was "band passed " (approximately 2.5-6 days) using the filtering procedure of Blackmon (1976). Both the original winds and the time-filtered wind components were used to calculate the cube of the friction velocity and the wind stress curl. Monthly mean maps of uo3 from the filtered wind components show clearly the location and intensity of the monthly mean synoptic storm activity during this period. Also, this measure of the synoptic storm activity was qualitatively related to the monthly mean sea surface temperature (SST) anomalies as analyzed by Namias. A somewhat surprising result was that the monthly mean wind stress curl from the filtered wind components did not appear to have a well organized spatial pattern and did not appear to play a significant part in the generation of SST anomalies. Prior to the study, some type of relationship was thought to be probable in view of the known proportionality of wind stress curl to the Ekman pumping mechanism .