Analysis Of Climate Modeling In Yunnan Region By Using RegCM3Model And Research Of Its Preliminary Application

Detailed information of climate modeling and climate change can be provided by the RegionalClimate Models(RCM), compared to global models,which leads to the fact that RCMs are usedwidely all over the world.YunNan province,situated in the southeastern of Tibetan, islow-latitude plateau, the weather and climate of YunNan is extremly hard to be forecasteddue to the special geography location and the fairly complex character of terrain.Actually,quite a lot of work has been done about the weather and climate in YunNan,however, RCMs arestill not utilized to conduct long-time modeling and applied to this region.In this thesis,the popularly used Regional Climate Model version3(RegCM3) is introduced toaccomplish a21-year long regional climate modeling in YunNan as well as the application ofRegCM3in YunNan,including the soil moisture sensitive experiments and the tropical IndianOcean sensitive experiments with positive SSTA prescribed,the main conclusions as followsare derived:(1) Both the potential predictability of the summer rainfall and temperature is the smallestamong the four seasons while the largest is spring，additionally,the distributions of thepotential predictabilities are also considered to be quite complex.These results is beneficialto our understanding the potential difficulties when conducting climate modeling in YunNan.(2) The annual variance of annual precipitation can be reproduced quite well as well as annualvariance of the four seasonal precipitations by the RegCM3.While,the reproduced rainfall inspring is fairly overestimated and the summer rainfall is underestimated verymuch.Overall,capturing the distribution of rainfall is still a challenge to the RegCM3.Thedistributions of temperatures of the four seasons and the annual are precisely reproduced butthe variances are not well reproduced.All these difficulties may be caused by the the special geography location and the fairly complex character of terrain in YunNan region.(3)The results in model and analysis of potential predictability are quite consistent bothin spring and in summer in terms of seasonal rainfall,which suggests the results derived fromthe RegCM3shall be treated correctly and carefully.Any excessive expect is not necessary.(4) In the soil moisture experiments,both the external water vapour and local potential heatflux can be impacted to change the rainfall in mid and late spring,what is more,this can sustaintill late summer, especially,the circulation systems in summer could be changed by theperturbation of dry soil in early spring which lead to the much more decrease of rainfall insummer compared to spring.This soil moisture-precipitation feedback could be weakened much bythe serious Atmosphere-Ocean interaction in ENSO phase.When the SSTA in tropical Indian Oceanis highly positive,the water vapour can be reduced from the peninsula to the southeastern Chinaso that the rainfall in spring of YunNan is reduced,alternatively,in summer,the water vapourfrom Bay of Bengal and south China sea are enhanced quite a lot to increase therainfall.However,in comparing the changing amplitude of rainfall,it is much bigger in the soilmoisture experiments.(5)From the above discussion,the perturbation of soil moisture and positive SSTA in tropicalIndian Ocean can be considered as the previous signals when climate modeling and forcastingare conducted in YunNan,much more work,however,is still need to be done to confirm thisconclusion.