1960年以来东亚季风区云-降水微物理的直接观测研究

In-situ measurements of cloud-percipitation microphysics in East Asian monsoon region since 1960

  • 摘要: 云-降水的直接观测结果是云微物理参数化的重要依据。自1960年以来,处于东亚季风影响下的中国实施了大量对云-降水微物理参数的观测和研究,旨在加深对云-降水微物理过程的认识,从而改进数值模式中云微物理参数化方案和指导人工影响天气作业。云-降水微物理参数包括气溶胶、冰核、云滴、雨滴、冰晶、雪晶、冰雹等粒子浓度和谱分布,以及云滴、雨滴含水量等。中国已有云-降水微物理参数的成果可归纳为:(1)通常云-降水微物理粒子浓度变化较大,但总体变化有一定的范围;(2)采用Γ函数拟合云滴谱更接近实际谱,但不同拟合谱参数差异较大;(3)可用指数函数和Γ函数来拟合层状云降水雨滴谱,Γ函数拟合积云和层积混合云降水雨滴谱精度更高;(4)中国冰核浓度较高,冰核浓度随温度的降低近似成指数变化;(5)冰晶谱、雪晶谱、冰雹谱通常采用指数函数来描述;(6)通常使用荣格(Junge)和Γ函数来分段描述气溶胶粒子谱拟合误差更小。由于云-降水过程及其反馈作用描述不准确是数值模式预报结果不确定性的最大因素,中国正在不断地推进云-降水的微物理观测研究,以期进一步加深对东亚季风区云-降水微物理特征的认识,从而为模式中微物理参数化方案的改进提供观测依据和科学指导。基于数值预报模式中云微物理过程参数化发展的需要,总结了中国1960年以来云-降水微物理直接观测的研究成果,可为东亚地区云-降水微物理研究及其模式参数化方案的改进提供观测依据。此外,针对云微物理参化发展的需求,结合过去已有的大量观测提出了几点建议,为今后云-降水物理综合性观测方案的设计提供参考。

     

    Abstract: It is well realized that the in-situ measurement results provide significant information for the microphysical parameterization in weather and climate models. Since 1960, there have been made a large number of in-situ measurements for cloud-precipitation microphysical properties with the aim at understanding the cloud-precipitation microphysical processes, and thus improving the cloud microphysical parameterizations in numerical models. The cloud-precipitation microphysical properties include particle size distribution and concentration, as well as liquid water content of a cloud and rain. Those measurements have yielded some useful information about cloud-precipitation microphysics over China. The main results are as follows: (1) various particles' total number concentrations vary greatly, which occurs however in certain scale distances only; (2) the gamma-function distribution has been widely used to describe the size distributions of cloud droplets in stratiform clouds, but fitted parameters have a wide range of variations; (3) both the exponential-and the gamma-function distributions are suitable for representing the raindrops size distributions (RSDs) of the rains originated from stratiform clouds, and the gamma-function distribution has been applied widely to describe RSDs of the rains originated from both convective and mixed (stratiform and cumuliform) clouds; (4) there is a higher ice nuclei concentration over China than that in other regions over the world, and the dependence of ice nuclei concentration on temperature is consistent, with approximately a expoentially increasing with decreasing temperature; (5) the exponential-function distribution is well adopted to represent the size distributions of ice crystals, snow crystals, and hailstones sampled at several locations; and (6) the sum of a modified gamma distribution and a Junge power-law distribution are used for describing aerosol particle size distributions. All these may be helpful for verifying the physical processes and hydrometeor fields simulated by a microphysical parameterization and improving the parameterization schemes in numerical models in the future. In addition, such comprehensive summary and analysis of the previous works as done in this work might also benefit designing new observation programs.

     

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