地形及下垫面对渤海大风影响的数值研究

Numerical Study of Terrain and Underlying Surface Effect on Bohai Gale

为研究渤海周围下垫面对大风的影响,利用WRF(Weather Research and Forecasting)模式,对2009年4月13和15日两次渤海东北大风过程进行了地形和海洋下垫面敏感性试验。结果表明:渤海北部地形对渤海海面大风有增强作用。地形的存在会使大风区更偏东,冷空气速度略偏慢,而辽宁东部地形的阻挡作用会使黄海北部海面风速减小。辽河平原喇叭口地形的存在使喇叭口东北部风速增大,而喇叭口西南侧及渤海海面风速减小。由于海洋下垫面较光滑,会对海上大风起到增强作用,引起"向岸风"效应。海洋下垫面对大风的增强作用与大风强度有关,风速越大,海面对大风的增强作用越明显,向岸风作用也就越明显。两次东北大风的试验结果表明,海面对大风的增强作用在渤海北部约2~3 m·s^(-1),渤海南部约3~5m·s^(-1)。渤海海洋下垫面对大风的增强作用大于渤海北部地形动力作用。

In order to study the effect of underlying surface near Bohai Sea on gale,sensitivity experiments of terrain and sea surface with two northeasterly gale cases on 13 and 15 April 2009 were conducted using the WRF (Weather Research and Forecasting)model.The results show that the terrain to the north of Bo-hai Sea may enhance the wind force over the sea,and gale occurs more easterly and cold air moves more slowly.The dynamic block of the northeastern terrain of Bohai Sea may weaken the wind force over the north Yellow Sea.The bell-mouthed terrain to the north of Bohai Sea may enhance the wind force to the northeastern part and weaken the wind force to southwestern part.The sea surface may enhance the wind over the sea to 3-5 m·s-1 in the southern part and 2-3 m·s-1 in the northern part,which causes the“shoreward gale”effect.The stronger the wind,the more obvious the ocean effect.In all,the effect of sea surface is stronger than the effect of terrain.