Statistic Analysis Of The Efficacy Of Arificial Precipitation In Liaocheng And Simulation Of Catalyst Diffusion

How to evaluate the efficacy of artificial precipitation is a very important part of the study of weather modification. The calculation and analysis of the catalytic efficacy under different conditions are bases for choosing the optimum time and weather conditions for artificial precipitation in Liaocheng.A review of the previous evaluation methods is made first in this thesis. The improvement for the unsupported assumption of certain methods is proposed. Then the efficacy of artificial precipitation from 2004 to 2007 in Liaocheng is analyzed by historical regional regression test and the statistical method of layered weather systems using precipitation data and synoptic charts from 1963 to 2007.The main results include: 1) The statistical method of layered weather systems can be effective in improving the relevance of regional rainfall. Thereby this method enhances the efficiency of assessment. 2) June is a favorable month for the artificial precipitation in Liaocheng. South cyclone is the ideal weather system for the best efficacy of artificial precipitation. 3)There is a certain relationship between the efficacy of artificial precipitation and rainfall intensity. The most effective optimum conditions correspond with different rainfall intensity levels under different weather system conditions.Artificial precipitation is to artificially impose impacts to clouds to increase the amount of precipitation. Under appropriate weather conditions, the suitable parts of cloud, efficient catalyzing techniques and optimum way should be chosen seriously in order to make a effective operation of artificial precipitaion. Based on the widely used Gauss model, this thesis simulates the catalyst diffusion in stratiform clouds. From the simulation results, a way of how to shoot the catalyst into the clouds to achieve maximum precipitation increment is proposed. For stratiform clouds, bullets containing catalyst should be shoot into the wind with a ' lag of angel' one by one in a rotary hemicycle way. This thesis also computes the number of bullets and 'lag angel' under different working parameter conditions, which provides a scientific guidance for artificial precipitation.