目前制约数值预报的SPIN-UP现象不容忽视。尽管现代高分辨数值模式大多已采用显式云方案，但SPIN-UP现象仍存在，其原因在于受观测限制，大气云水、云冰、雨水、雪等凝结水物质含量大都采用零初值法（即冷启动），冷启动产生出符合实际的云需要一定的时间，使得模式积分初期云和降水误差很大。本项目根据中国特定地理区域和天气气候背景，利用卫星、雷达、GPS、微波辐射计、地面、探空等多源探测资料检验云的宏、微观特征，开展云分析方案在我国南方暴雨过程中的适用性分析和参数优化，弄清不同探测资料在云分析中的贡献和作用，以便更加科学合理地获得云分析产品；同时开展暴雨数值模式热启动方法研究，采用四维变分同化方法调整模式动力、热力和云初值场使其相互协调，尝试解决由于模式动力、热力和云初值场不协调带来的热启动影响很快被抹掉的问题，以减轻SPIN-UP现象，提高云和降水短时临近数值预报准确率。

Now not neglected is the model SPIN-UP in numerical forecast, which still exist even with explicit cloud microphysics schemes used in high-resolution numerical models. Due to observational limitations, initial cloud hydrometeors, like cloud water, cloud ice, rain water, snow, and among others, are set to be zero at the beginning of model integration, which is called model cold start. Numerical errors are usually very large in the first several hours of model integration because cloud hydrometeors need several hours to be generated in the model integration. According to the particular geography and weather background in China, this program is planned to carry out studies on the cloud-analysis theory and method, with heavy rainfall processes of special cloud features in South China. Multiple data, like satellite remote sensing, radar detections, GPS water vapor, micrometers, surface and sounding observations and among others, will be used to test the macro- and micro- features of clouds. Besides, the contributions and roles of different observational data will be evaluated in the cloud analysis, so as to obtain cloud analyzed products more reasonably and scientifically. Furthermore, research on the hot start methodology of heavy-rain numerical model will be conducted. Four-dimensional variational method will be adopted to adjust model initial filed, including dynamic, thermodynamic and cloud fields, and to make them in concert with each other during the model integration. Lastly, efforts will be tried to eliminate the quick attenuation of hot start impacts in model integration due to the inharmonious among model dynamic, thermodynamic and cloud fields, to diminish the model SPIN-UP, and to improve short-time numerical forecast of clouds and precipitation.