中国东部城市土地利用变化对江南春雨影响的模拟研究

Numerical simulations of the influence of land-use change over East China on spring persistent rains

利用美国国家大气研究中心发布的较高分辨率大气环流模式CAM 5.1,进行了中国东部（20～50°N,100～125°E）城市土地利用变化对江南春雨影响的数值试验。结果显示：较中国东部无城市土地利用的试验相比,城市用地增加后,江南春雨推迟约3候建立而提前1候结束,持续时间缩短,同时降水强度减弱。进一步分析表明：东部城市土地利用增加可改变地表能量收支,使得东部大部分地区的地表增暖,导致地表感热增强,对大气的异常加热使得该区域上空等压面抬升,缩小了低层青藏高原东南侧至西太平洋间的位势梯度,使得形成江南春雨的直接原因——西南风减小,从而减少春季江南地区的降水。中国东部城市土地利用改变可能是影响近几十年江南春雨年代际变化的原因之一。

Based on the higher resolution atmospheric circulation model. Community Atmosphere Mod- el Version 5. 1 （ CAMS. 1 ）, the effect of the land use variation over East China on the spring persistent rain is numerically simulated. Results show that the spring persistent rain onset starts 3 pentads later than nor- mal but ends 1 pentad earlier than normal, thus both persistent time and intensity of precipitation decrase due to the land -use change. The urbanization can increase the surface absorption of the solar radiation, and the strong sensible heat can warm the air over the region. The physical processes leading to the changes of the atmospheric circulation are analyzed in detail in the article. The land-use change may be responsible for the decadal variation of the spring rainfall.