On Haney-Type Surface Thermal Boundary Conditions for Ocean Circulation Models

Haney-type surface thermal boundary conditions linearly connect net downward surface heat flux Q to air– sea temperature difference (gradient-type condition) DT1 or to climate/synoptic sea temperature difference (restoring-type condition) DT2 by a coupling coefficient k. In this study, the authors used the global reanalyzed data (6-h resolution) of Q, surface air temperature TA, and sea surface temperature TO from the National Centers for Environmental Prediction during 1 October 1994–31 December 1995 to verify the validity of Haney-type surface thermal boundary conditions. First, daily means of these variables were computed to get rid of diurnal variation. Second, the cross-correlation coefficients (CCC) between Q and (DT1, DT2) were calculated. The ensemble mean CCC fields show (i) no correlation between Q and DT2 anywhere in the world oceans, (ii) no correlation between Q and DT1 in the equatorial regions, and (c) evident correlation (CCC $ 0.7) between Q and DT1 in the middle and high latitudes. Third, the variance analysis was conducted and a value of 70 W m22 K21 (65 W m22 K21) was suggested for the coupling coefficient k in the northern (southern) middle and high latitude zone. Thus, the authors find that the restoring-type surface thermal conditions by no means represent the net air– ocean heat flux anywhere in the world oceans. However, the gradient-type surface thermal condition represents the net heat flux quite well for the middle and high latitudes. In addition, it is also found that, if the solar shortwave component is treated separately, the gradient-type condition will have more fidelity for the middle and high latitudes.