THE SEASONAL HEAT-BUDGET OF THE NORTH PACIFIC - NET HEAT-FLUX AND HEAT-STORAGE RATES (1950-1990)

A new estimate of the heat budget for the North Pacific Ocean is prese nted in this paper. The seasonal net heat flux and heat storage rates were calculated for the North Pacific Ocean from 1950 to 1990 on a spa tial resolution of 5 degrees x 5 degrees. Temperature profiles from th e National Ocean Data Center were used to calculate the heat storage r ates. Satellite remotely sensed solar irradiance and ship marine weath er reports from the Comprehensive Ocean-Atmosphere Data Set were used to calculate the net surface heat flux. Heat storage rates were calcul ated as the time rate of change of the heat content integrated from th e surface down to the isotherm that was 1 degrees C less than the cold est locally observed wintertime sea surface temperature, which was def ined as the locally observed wintertime ventilation isotherm. The mont hly climatology of the 5 degrees x 5 degrees resolution net heat flux was balanced by the heal storage rate for most regions of the North Pa cific. To achieve this balance the net heat flux was calculated using the Liu et al. formulations for latent and sensible heat exchange and a modified version of the Reed cloud correction for solar insolation. The root-mean-square error in the difference between the net heat flux and heat storage rate climatologies was calculated at 40 W m(-2). Whe n the individual temperature profiles from the northeastern portion of the basin were normalized to the local 300-m mean temperature, thereb y removing some of the potential local changes caused by barotropic va riability of water motion, the root-mean-square error in this region w as further reduced to 20 W m(-2) and the large-scale semiannual period icity in the difference observed in the subtropics was removed. This n ormalization process may have removed some of the basin-scale variabil ity in the horizontal heat advection. An estimate of the northward hea t transport was calculated by integrating the annual mean net heat flu x over the North Pacific. The resulting heat transport values were clo ser to actual northward heat transport estimates made at 10 degrees, 2 4 degrees, 35 degrees, and 47 degrees N, than previous ocean heat flux estimates. The bias in the data was estimated to be less than 7% by c omparing the demeaned seasonal cycle of the net heat flux with that of the heat storage rates. The annual mean net heat flux was then used w ith the 7% bias and the 20 W m(-2) uncertainty to calculate a more con strained error envelope for the annual mean northward heat transport i n the North Pacific.