IMPACT OF REGIONAL CIRCULATION AND HEAT BUDGET TO TROPICAL NIGHT

Abstract

C called tropical night inthe mountainous coastal region was investigated by a three-dimensional non-hydrostatic model from 09:00LST, August 13 to 09:00LST, August 15, 1995.As synoptic westerly blowing over the mountain in the west is interrupted byupslope wind combined with valley wind and easterly sea breeze from the east-ern sea, two different wind regimes go up to the 1700m height, becoming awesterly return flow over the sea. Convective boundary layer (CBL) of about1km and thermal internal boundary layer less than 150m are developed overthe mountain basin and along the mountain slope from the coast. As sensibleheat flux convergences between the ground surface of the mountain or inlandcoast and upper level atmosphere over the surface are much greater than theflux on the coastal sea, the flux should be accumulated inside thermal inter-nal boundary layer along the mountain slope and the CBL over the mountain.Then, accumulated sensible heat flux under the influence of sea-valley windfrom the sea to the top of mountain and from the mountain top toward thecoastal surface should be transported into the coast, resulting in high air tem-peratures in the coastal inland and sea. After sunset, synoptic westerly windwas associated with mountain wind and land breeze and was further stronger.Very small flux divergence occurs in the coast, while flux divergences are muchgreater at both the mountain top and along its eastern slope than over thecoastal inland and sea surfaces. By more cooling down of the mountain surfacethan the coastal surface and heat transfer from warm pool over the coast intothe coastal surface, nocturnal air temperatures on the sea and coastal inlandsurfaces are not much changed from daytime ones, resulting in the formationof nocturnal high temperature.