Effects of the Vertical Resolution and the Treatment of Surface Winds on Atmospheric Heat and Moisture Budget Computations During a Period of Cold Air Outbreak Over the Warm Sea Surface

[摘要] The heating and moistening rates in the atmosphere over the Kuroshio region in winter are compared to each other for cases with different vertical resolutions of upper-air obser-vation data. The total sensible and latent heat flux at the sea surface calculated with a poor vertical resolution is overestimated by about 60W m-2 (-15% of the total flux)(-15% of the total flux) compared to that with a fine resolution due to the overestimation of the heating rate in the upper part of the convective mixed layer. Such discrepancies are remarkable when the wind in the mixed layer is strong (in an intense cold air outbreak situation). These errors are partly due to errors of the horizontal advection of heat in the use of a poor vertical resolution, but mainly due to the underestimation of the vertical p-velocity which is caused by the underestimation of horizontal divergence in the lowest layer. It is suggested that errors in budget computations in the mixed layer can be reduced if we properly treat wind speeds near the surface at land stations even in cases of poor vertical resolutions.

[学科分类] 大气科学