一次局地辐射雾过程及其水汽来源的数值模拟

Numerical simulation of a local radiation fog process and its water vapor source

基于WRF中尺度数值预报模式和HYSPLIT后向轨迹模式对2017年11月10~11日发生在广东省佛山市的一次局地雾天气过程及其水汽来源进行高分辨率的数值模拟研究。WRF模拟结果表明:本次雾是一次典型的辐射雾过程;晴朗夜晚地面长波辐射冷却降温使得区域范围内水汽聚集并凝结产生相变,同时夜间存在逆温层以及局地低于1 m/s的静小风促进了此次雾过程的发展;垂直方向上温度和水汽含量的变化较为一致,揭示了近地面雾层的垂直发展情况。进一步利用WRF高分辨率模拟结果驱动HYSPLIT后向轨迹模式对此次雾天气过程的水汽来源进行分析发现:除本地水汽凝结相变外,佛山市辖区内珠江流域水汽的输送对本次雾天气有促进作用。

The WRF mesoscale meteorological model and the HYSPLIT model were used to investigate a local radiation fog that occurred in Foshan from Nov 10th to Nov 11th,2017,and its sources of water vapor.The results show this is a typical radiation fog process.During the clear night,surface long-wave radiation cooling resulted in water vapor gathering and condensing,meanwhile,temperature inversion and wind speed that lower than 1 m/s in the area promoted the development of the fog.Vertical temperature variations were highly related to water vapor concentrations,which could represent the features of vertical development during the fogging process.To analyze the sources of water vapor in this fog,high-resolution simulation results from the WRF model were utilized to drive the HYSPLIT model.It is found that in addition to the local water vapor condensation,the transport of water vapor from the Pearl River in Foshan city also promoted fogging.