Variation in thermal structure and geostrophic current between Alaska and Hawaii determined from synoptic space sections

Abstract

Five synoptic space sections along 158°W longitude between Hawaii and the Aleutian Is lands were developed from data collected by air­ borne expendable bathythermographs during experiment PARKA, a research project sponsored by the U. S. Navy in 1968. The sections are examined for spacial and temporal variation in thermal structure and geostrophic surface velocity. Two recently developed analysis techniques are employed. Denner's T-S gradient method, wherein thermal and haline contributions to total geostrophic velocity are distinguishable, expedites calculations and results in velocity fields comparable to those developed by the dynamic method. Thermocline parameters are developed using Boston's objective definition of the thermocline , a statistical curve-fitting technique which develops the notion of a Gaussian thermocline. Gross features of thermal structure remain fairly consistent during the heating season; however, thermal fronts are observed to vary in time and space. The distribution of isothermal lines with latitude suggests the possibility of a Taylor-column effect slightly north of Hawaii.