四維變分和集合卡爾曼濾波同化多普勒雷達(dá)資料的方法及其反演暴雨中尺度結(jié)構(gòu)的研究.pdf

1、南京信息工程大學(xué)博士學(xué)位論文四維變分和集合卡爾曼濾波同化多普勒雷達(dá)資料的方法及其反演暴雨中尺度結(jié)構(gòu)的研究姓名：許小永申請學(xué)位級別：博士專業(yè)：大氣物理學(xué)與大氣環(huán)境指導(dǎo)教師：鄭國光劉黎平20050401ABSTRACTTwomethods:thefourdimensionalvariational(4DVAR)andtheensembleKalmanfilter(EnKF)areappliedtoassimilateDopplerradar

2、datainacloudmodel.Thequalityofretrievalandperformancesofthetwotechniquesinobtainingquantitativelymesoscaleinformationofhazardousweathersystemshavebeentestedusingsimulateddataandrealobservations.Themajorcontentsandconclus

3、ionsarepresentedasfollows:Firstlythe4DVARtechniqueandthecloudmodeldevelopedbySunandCrook(1997)，areusedtoassimilatedatafromasimulatedconvectivestorm.Experimentsdemonstratethatthe4DVARassimilationapproachisabletoretrieveth

4、edetailedstructureofwindthermodynamicsandmicrophysicsusingeitherdualDopplerorsingleDopplerradardata.Thequalityofretrievaldependsstronglyonthemagnitudeofconstraintwithrespecttothevariable.Secondlythe4DVARmethodisappliedto

5、aMeiyuheavyprecipitationinthemiddleYangtzeRiverreachobservedbytheYICHANGJINGZHOUdualDopplerradarsThestudyhasclearlydemonstratedtheabilityofthe4DVARassimilationapproachtodrivethequantitativeinformationofrainstormmesoscale

6、structurefromrealradarobservationsIthasbeenrevealedintheassimilationresultsthatthetorrentialrainfalliscausedbythewindshearlineandatlowlevel.Theconvectiverainfallisoftenrelatedtolowerlevelconve心encepressureatlowerupperlev

7、eldivergencecoupledwithanupdraftcharacterizedbyhighlevelandlowpressureatupperlevel.Thetemperaturestructureofconvectivesystemshowswarmeratmiddlelevelandcolderatlowerandupperlevelthantheenvironment.Thewatervaporcouldwatera

8、ndrainwaterareassociatedwiththeconvectivecloudtheupdraftandthereflectivityrespectively.ThirdlythemesoscalefeatureofaMeiyufrontrainstormoverthelowerYangtzeRiverbasinisinvestigatedbythe4DVARassimilationofdatafromtheHEFEIWU

9、WEIMAANSHANdualthreeDopplerradars.Theassimilationsofdatafromthreegroupsofdualradarsorsingleradarproducegenerallysimilarmesoscalestructures.TheconvergencelineisprimarydynamicalcharacteristicoftheMeiyuheavyprecipitation.Th