Deriving corrections to FNOC surface heat flux estimates for use in North Pacific ocean predictions

Abstract

The specification of the surface heat flux is essential for synoptic and seasonal prediction of the upper ccsan thermal structure. Estimates of tlia surface heat flux have been prepared for the central North Pacific during January 1976 through April 1979 using archived fields from the Fiast Numerical Oceanography Center (FNOC) hemispheric atmospheric prediction model. Monthly accumulations of the surface heat flux are compared with the change in heat content above 2D0 m derived from temperature analyses of the North Pacific Experiment TRANSPAC ship-of-cpportunit y program. Systematic differences are found between the accumulated heat flux fields and the oceanic heat content change. Some of the differences are due to excessively large changes in ocean heat contents above a fixed level. However, our earlier studies have suggested a bias of excessive upward surface heat flux, especially along the southern boundary of the domain. Assuming local heat balance o/er a 36-month period, a correction field to the FNOC surface heat flux estimates is derived. Separate correction fields for the heating and cooling seasons demonstrate a seasonal variation in the accumulated heat flux versus heat content change values. Thus, six bi-monthly correction fields to be added to the FNOC heat fluxes are prepared to enable these heat fluxes to be used for ocean prediction.