小型水体对气温观测环境影响的初步模拟分析

为研究水体对气温观测环境的影响,应用WRF中尺度模式,通过对四季晴天小风、阴天大风背景天气下有无水体算例模拟结果的比较,分析了浙江青山湖水体(6.5 km2)对周边2 m高度处气温的影响。模拟结果表明:(1)冬季天气条件通常较稳定,水体对下风方的影响最为明显;春、秋季节水体对下风方的影响次之,夏季局地热力环流复杂,水体对下风方气温影响不若其他季节明显。(2)青山湖水体对下风方约5 km内的气温可能产生明显影响,非下风方缩短为0.4 km。(3)水体面积越大,对周边气温影响距离越大。(4)当风速大于6.2 m·s-1时,水陆热力性质差异迅速被平流项输送携带走,水体对下风方气温影响不明显。而湍流扩散项则将水体与陆面热力性质的差异向上传递,湍流强度大于0.5 m2·s-2时,水体对下风方气温的影响不明显。

A preliminary simulation analysis on effects of water body on air temperature observation environment

In order to research the effects of water body on temperature observation environment at meteorological stations, through comparing the case simulation results with or without water bodies, the impacts of Qingshan Lake(6.5 km²)in Zhejiang province on the surrounding air temperature at 2 m by using WRF model were analyzed under the weather background of clear sky with light wind and cloudy sky with gale in four seasons, respectively. Results show that (1) water body would increase leeward air temperature greater in winter than in spring and autumn due to the stable weather condition, while in summer, the influence of water body was not so obvious because of the complex local thermodynamic circulation. (2) The Qingshan Lake has obvious effects on the air temperature at a distance of 5 km from the lake leeward and 0.4 km in other directions. (3) The larger the water body area is, the longer the affecting distance of surrounding air temperature is. (4)When the wind speed is higher than 6.2 m·s^-1, the thermodynamic property divergence between water and land would be quickly carried away by advection, so the effect was not obvious. And then the turbulent diffusion would transmit the thermodynamic property divergence upward, so the effects became not so obvious when the turbulence intensity was larger than 0.5 m²·s^-2.