Heat and Water Budget over the Japan Sea and the Japan Islands in Winter Season

With special emphasis on the relation among the supply from sea surface, the convective transfer and the heavy snowfall

Abstract

The heat and water budgets over the Japan Sea and the Japan Islands are analysed with special emphasis on the physical links among the energy supply from the sea surface to the atmosphere, the convective transfer of heat and moisture and the heavy snowfall for various synoptic situations in the winters of 1963, 1964 and 1965 by using aerological data with the aid of the marine, radar, dropsonde and aerophotographic cloud observations.
When a cold vortex aloft passes over, the increase of evaporation from the Japan Sea and the convergence of water vapor over the Japan Islands are not so remarkable as the increase of snowfall and the sensible heat supply from the sea. The large amount of snowfall is explained by the high
efficiency in condensation process and the convergence of the condensed water substance over the coastal area.
The terms concerning the convective transfer of heat and moisture are introduced in the large scale budget equation and the magnitudes of the transfer across various levels are estimated. The amount of transfer as well as that of the supplied energy are found to increase when the stratification becomes unstable under the influence of the cold air aloft.
The magnitude of the convective transfer obtained in large scale analysis coincides almost with the estimation based on the observation data about cumulus convection such as the convective upward speed or excess temperature in clouds.