SEASONAL HEAT-STORAGE IN THE NORTH PACIFIC - 1976-1989

Volunteer observing ship expendable bathythermograph data obtained dur ing the period 1976-1989, from 30 degrees N to 40 degrees N in the Nor th Pacific, were used to compute the rate of change of heat storage to a fixed upper ocean temperature surface. The variability of the stora ge rate in the seasonal timescale, computed on a 5 degrees latitude by 5 degrees longitude spatial scale, is compared to the net surface hea t flux computed from available surface marine weather data to the same spatial and temporal resolution. Averaged across the entire basin, th e difference between the average monthly heat storage rate and the ave rage monthly heat flux is 3.76 Wm(-1). The average basin-wide absolute heat storage rate agrees to within 7.5% of the average absolute heat flux for the whole basin. An empirical orthogonal decomposition of the spatial patterns of the difference between the heat storage rate and the net heat flux reveals no obvious trends in the heat flux computati on or possible physical processes responsible for the difference. Inst ead, the eddies shed by the warm boundary current, the Kuroshio, is pr obably responsible for the major part of the difference patterns in lo cations where the difference values are maximum. The most important re sults of this study are that the heat storage rate computed to a fixed isotherm matches the net heat flux extremely well at the chosen locat ions and across the whole basin; and the heat storage rate computation is sensitive to the isotherm choice and to the space scale involved.