Research On Evaluation Of The Artificial Precipitation Enhancement Effect Based On Modern Statistical Methods

At present,cloud seeding technology has been widely applied to solve the problem of water shortage.However,there is still no convincing scientific evidence to prove the effect of artificial precipitation enhancement.As a result,how to evaluate the catalytic effect of artificial precipitation enhancement scientifically and reasonably has become an urgent problem to be solved.Taking the effect of precipitation enhancement in Jilin Province from April to July,the main research contents based on modern statistical methods,cloud seeding operations data and large-scale meteorological data are as follows:The first chapter introduced the research background and research status of artificial precipitation enhancement evaluation.It mainly described the statistical test plan design,regionalization of precipitation and estimation of natural precipitation.Then the research content and innovation of this paper were illustrated.In the second chapter,the spatial and temporal characteristics of precipitation in Jilin Province from April to July and its relationship with atmospheric circulation were analyzed.The large-scale meteorological variables affecting precipitation and their influencing mechanisms were also studied using downscaling methods.The results shown that the precipitation in Jilin Province from April to July is extremely uneven,with more precipitation in summer and drought in spring.The spatial distribution is seriously affected by the terrain.The precipitation in spring and summer in Jilin Province depends on the water vapor content in the middle and low altitudes and weakly affected by teleconnection.In addition,the influence of meridional and vertical water vapor transport on summer precipitation is greater than that in spring.In the third chapter,the large-scale meteorological variables were introduced based on the precipitation influence mechanism analysis in the second chapter,and the precipitation characteristics of Jilin were regionalized using the self-organizing mapping method(SOM).Then,the homogeneity of the partitioned regions was tested by the heterogeneity measurements based on L-moment ratios and some adjustments were implemented.According to the results of the regionalization,cloud seeding operations data and analysis of prevailing wind,the main target area of artificial precipitation enhancement and the corresponding comparison area in Jilin Province were determined.In the fourth chapter,using the large-scale meteorological variables and telecorrelation influencing factors which affecting precipitation significantly,precipitation in the contrast area and the surface precipitation attributes,the precipitation occurrence model and precipitation intensity model were constructed respectively based on the generalized linear model framework to simulate the natural precipitation in the main target areas of cloud seeding operations in Jilin Province.Considering the drought situation in Jilin and the dependence among the sites in the whole region,the two models better captures the actual precipitation of each site under the form of weak precipitation,which is of great significance to improve the accuracy of the evaluation of artificial precipitation enhancement effect.The statistical evaluation and analysis of the artificial precipitation enhancement effect shown that the effect of artificial precipitation enhancement depends on the natural precipitation situation in target areas.To improve the artificial precipitation enhancement effect,a deep study for cloud water conditions,precipitation potential and cloud seeding feasibility must be carried out.Finally,the main conclusions of this paper were summarized and the future prospects for this research were discussed in the fifth chapter.