云滴谱的不确定性对中尺度降水的影响  

IMPACT OF CLOUD DROPLETS SPECTRAL UNCERTAINTY ON THE MESOSCALE PRECIPITATION

作　　者：周广强[1] 赵春生[1] 秦瑜[1] 

机构地区：[1]北京大学物理学院大气科学系

出　　处：《热带气象学报》2005年第6期605-614,共10页Journal of Tropical Meteorology

基　　金：国家自然科学基金项目(40475003);国家重大基础研究发展规划"我国重大气候和天气灾害形成机理与预测理论研究"子课题(G1998040911)资助

摘　　要：云滴的谱分布通过改变云滴的有效半径影响辐射传输过程,改变大气的热力、动力状况,进而影响云的发展,因此云滴谱将影响云和辐射的相互作用,从而改变地面降水。利用包含详细云微物理方案的MM5V3中尺度模式对1998年6月8日华南暴雨和2002年7月22日长江暴雨进行了数值模拟,研究了中尺度模式中云滴谱的不确定性对地面降水的影响。模拟结果表明,云滴谱在中尺度地面降水中起着重要的作用,其不确定性对地面降水的范围影响很小,却能明显地改变降水强度,能显著地改变地面降水中心的降水量和中心位置,还可能改变降水的起止时间;云滴谱的不确定性能够引起最大超过10%的平均降水强度的改变,而且其差异在白天比夜间更明显。The effective radius of cloud droplets, changing due to the cloud droplets spectral uncertainty （CDSU）, can affect the radiation transfer processes. This effect may modify the atmospheric thermal and dynamical structure, cloud development, and surface precipitation. The impact of CDSU in the cloud-radiation processes on mesoscale precipitation was studied in this paper using two storm cases, a South China storm on June 8th, 1998 and a Yangtze River storm on July 22nd, 2002, and employing the MM5V3 with which a newly developed, dual-parameterized explicit moisture scheme is coupled. The results show that CDS plays a very important role in the mesoscale precipitation. Its uncertainty has a slight effect on the overall rainfall pattern, but a significant effect on rainfall intensity. The position and intensity, even the beginning and ending time of the precipitation centers, can also be modified significantly. The maximum change of mean rainfall intensity is over 10% due to CDSU and difference among experiments is more obvious in the daytime than at night.

关 键 词：云辐射 中尺度降水 有效半径 数值模拟 

分 类 号：P426.62[天文地球—大气科学及气象学]