抄録
Surface layer(0-17 °C isotherm depth) heat balance of a closed rectangular system (the Kuroshio
system) in the North-West Pacifichas been examined for a period of 10 days (from 16th to 25th
October, 1991), by considering the residual of net surface heat flux and heat divergence of the
systemdue to horizontaladvection. The Kuroshio system has been formulated by taking hydrographic
sections (CTD) across the lateral boundaries. Net surface heat flux for the system has
been obtained exclusively from satellite observations of surface meteorological parameters using
bulk method. Heat divergence in the systemis deducedby consideringthe residual heat advection
into/out of the system due to geostrophic currents across the lateral boundaries, derived using
method of Wunsch (1978).
Synoptic flux estimates using satellite observations are compared with earlier estimates for
this region (in the same season) from in situ data and are found to be reasonable. While the
Kuroshio regime shows large net heat loss, towards the south it decreases and have heat surplus.
An evaluation of the satellite derived heat fluxes by comparing with flux estimates from in situ
observations at ocean weather station-Tango are also found to be comparable. For net satellite
derived heat flux varying from 0 to 300w/m^2 the uncertainties are found to be of the order of 50-
80w/m^2. For the same range of flux values the possible uncertainties in ground based climatological
estimates are from 40 to 60w/m^-2. This increase in uncertainties for satellite derived fluxes
are found to be due to remote sensing error. For the Kuroshio system, the net heat flux varies from
0-300w/m2 with uncertainties varying from 50 to 80w/m^2.
Regarding the heat balance of the Kuroshio box model, the net surface heat flux for the box is
-1.4x10^14watt. Though there is a general view that Kuroshio act as an effective feeder for the
surface heat loss for this region in the present case it is found that for 10-days mean period this is
not hapening. Instead of that the system is also losing heat in terms of advection. The horizontal
heat divergence due to advection is -0.6x10^14watt. During the observation period it is seen that the
surface layer (nearly 100m) temperature falls down considerably (of the order of 1°C). It is found
that the observed surface heat loss alone is not sufficient to cause the fall in the surface layer
temperature of such a large system. The observed horizontal heat divergence is largely caused by
the mass imbalance rather than the flow temperature difference at the boundaries.
