Henan Province, The Spring-scale Structure In The Layered Cloud System And Precipitation Simulation Comparison Study

This paper simulated two cases of spring stratus precipitation processes occurring during April 4 to 5,2002, and April 11,1999 in Henan province and contrast the simulated results with the observation. The cases were simulated by the Nonhydrostatic mesoscale numerical model MM5(v3.5),the shortest net distance was 3km, and the simulated results were compared with observation data including NCEP reanalysis data ,GMS-5 satellite cloud pictures, TRMM satellite data .radar echo pictures, synoptic charts, precipitation station data, etc. We studied the characteristics of the dynamical structure, the vapor distribution, the thermal distribution, and macrostructure and microstructure of the cloud system during precipitation. We also made discussion about the microphysics mechanism of the precipitation and the distribution of cloud potential to rain enhancement.In the process during 2002, the simulated results is similar to the observation, especially the rain core's appearing, growing, and disappearing is similar to the observation of the rainfall in Henan Province, and the results shows the relationship between the vortex in 850 hpa with the vapor in lower layer and the precipitation. In the process during 1999, analyses on both the simulated results and the observation shows that, the north Henna province was affected by the low trough-cold front system, while in south Henan, cyclone system grew. The simulated cloud system structure of the two process are similar to both rader echo and TRMM satellite's pictures. The simulated results show that the nohydrostatic mesoscale numerical model with explicit microphysical schemes simulated spring stratus precipitation processes in Henan province successfully.The analyses of contrast show some common character: the vapor transfers in low layer has evidence impact on precipitation, rain fall heavily where vapor transfers are abundant; In steady low trough -cold front cloud system, the top of the ice is above 10km. The broad cloud consists of ice mainly in high levels, though rainfall happens only some parts of the cloud where snow, graupel, cloud water, rain can be found here. The snow and graupel are distributed between ice and 0°C layer, the cloud water and rain are distributed between 0° C layer and the ground; There are updraft, and consistent water matter where rainfall exceed 5mm/h. The strong updraft correspond with cloud water and snow well. From proper cross section, we can see column clouds whose horizontal scale are ten to several hundred Km and heavy surface rainfall center under the clouds. The cloud system takes unequally distribution where no rainfall or rain gently, the cloud takes layered structure; The potential instability also has evidence impact on precipitation; The simulated results show there is abundant super-cooling water in clouds, updraft air corresponding well to cloud water, The results show that some places have abundant super-cooled water and little ice .these places could be taken into account for catalyzing. Terrain also takes effect on precipitation.The simulated results show that the nohydrostatic mesoscale numerical model with explicit microphysical schemes could simulate spring stratus precipitation processes in Henan province successfully.