THERMODYNAMIC MECHANISM CAUSING HEAVY RAINFALL OVER THE CENTRAL HIGHLAND AND THE SOUTH IN THE CASE OF A FAR TYPHOON OBSERVED OVER NORTHERN VIETNAM EAST SEA COMBINATED WITH SOUTHWEST MONSOON AND TERRAIN

Abstract

In this article, the simulated products from WRF high-resolution model were used to research the thermodynamic mechanism causing the typical heavy rain from 9-13/8/2013 in the Central Highlands and the South in the case of typhoon Utor observed over Northern East Sea. The model runs with three nested domains with resolutions of 54 km, 18 km and 6 km, respectively. Third domain covers the whole of the South and south of the Central Highlands. Data has been used in this study including observation data and re-forecast data of CFS model. The results show that interaction between circulation of typhoon Utor, southwest monsoon in forming this heavy rainfall event has been determined through Southwest moisture transport band which originate from Bengal gulf to the research region and connected typhoon circulation Utor. This interaction help to enhance a part of Southwest monsoon to the region which bring humid air and large kinetic energy combining with orographic blocking and lifting effects at high terrain leading to enhance moisture convergence and form the forced updraft in west windward side causing heavy rainfall.