一次海风锋天气过程分析与数值模拟

利用NCEP再分析资料、自动气象站观测数据、多普勒天气雷达反射率因子和WRF模式,对2015年5月24日午后,海南岛东北部出现的一次较强的海风锋降水天气进行过程分析和数值模拟。结果表明:强降水发生期间,海南岛处于副热带高压边缘,中低层水汽来源充沛,降水前后K指数变化明显;两支分别来自海口海岸线向东南移动与来自文昌海岸线向西北移动的海风锋的发展、增强与移动,是导致本次降水的主要原因。另外,中部山区小尺度的地形辐合有利于过程期间海风锋的加强与发展;WRF模式的模拟结果说明,海风锋发展最旺盛的时候,锋面高度达约1000 m,宽度约0.15个经度;海风锋垂直环流圈的建立伴随着地面降水的加强;地面降水减弱时,海风锋环流圈逐渐消失。

Process Analysis and Numerical Simulation of a Sea Breeze Front Weather

Using NCEP reanalysis data, automatic weather stations data, weather radar reflectivity factor and WRF model, an afternoon heavy rainstorm induced by sea breeze front at northeastern Hainan on 24th May 2015 is examined. The results show that the heavy rainstorm case occurred when Hainan was on the north edge of subtropical high and with abundant middle and low level water vapor transport. The K index changed significantly before and after the rainstorm. The development, enhancement and movement of two sea breeze front, which started from the coastline of Haikou with southeastern propagation and the coastline of Wenchang with northwestern movement respectively, contribute most to the heavy rainstorm. Moreover, the small scale convergence by topography over the central mountainous area was helpful to strengthen and develop the sea breeze front. The simulation results of WRF model indicate that the strongest sea breeze front can reach a height of nearly 1000 meters, and its width is about 0.15 longitude. The establishment of sea breeze front circulation is accompanied by the enhancement of surface precipitation. When surface rainfall decreases, the sea breeze front circle gradually disappears.