简介：

简介：利用常规地面高空观测资料、山东省123个自动站1h降雨量资料和25个地基GPS反演的大气可降水量资料,对比分析不同天气系统影响下典型强降雨过程中的大气可降水量变化特征。结果表明：（1）降雨开始前水汽累积时间与天气系统尺度有密切关系,一般尺度越大,水汽积累时间越长,低槽冷锋强降雨前大气可降水量的积累时长可达约26h,副高边缘强降雨发生前水汽积累时间仅5~6h;（2）水汽增速与天气系统尺度密切相关。天气系统尺度越小增速越快,低槽冷锋强降雨发生前水汽增速小于2.0mm·h~（-1）,副高边缘强降雨发生前水汽增速可达3.1mm·h~（-1）;（3）短时强降雨发生前,水汽累积时间与积累速度呈反相关,即水汽增速越快,强降雨发生越快,当水汽增速大于2.0mm·h~（-1）,可降水量经历5~6h积累即可产生短时强降雨;（4）一般强降雨时段多数在可降水量峰区时段,而副高边缘型短时强降雨和冷式切变线第1阶段强降雨均发生在可降水量增长时段。降雨过程结束后,一般情况下可降水量锐减,而副高边缘型和冷式切变线第1阶段强降雨结束后可降水量继续增长。冷式切变线第2阶段降雨结束后可降水量出现持续小幅减小,数小时后,可降水量再次增长。

简介：DataobtainedbyGRACE(GravityRecoveryandClimateExperiment)havebeenusedtoinvertfortheseismicsourceparametersofmegathrustearthquakesundertheassumptionofeitheruniformslipoveranentirefaultorapoint-likeseismicsource.Herein,wefurtherextendtheinversionofGRACElong-wavelengthgravitychangestoheterogeneousslipdistributionsduringthe2011Tohokuearthquakeusingthreefaultmodels:(I)aconstant-strikeandconstant-dipfault,(II)avariabledipfault,and(III)arealisticallyvaryingstrikefault.Byremovingthepost-seismicsignalfromthetimeseries,andtakingtheeffectofoceanwaterredistributionintoaccount,weinvertforslipmodelsI,II,andIIIusingco-seismicgravitychangesmeasuredbyGRACE,de-stripedbyDDK3decorrelationfilter.Thetotalseismicmomentsofourslipmodels,withrespectivevaluesof4.9×1022Nm,5.1×1022Nm,and5.0×1022Nm,aresmallerthanthoseobtainedbyotherstudiesrelyingonGRACEdata.Theresultingcentroidsarealsolocatedatgreaterdepths(20km,19.8km,and17.4km,respectively).BycombiningonshoreGPS,GPS-Acoustic,andGRACEdata,weobtainajointlyinvertedslipmodelwithaseismicmomentof4.8×1022Nm,whichislargerthantheseismicmomentobtainedusingonlytheGPSdisplacements.Weshowthattheslipinvertedfromlowdegreespace-bornegravimetricdata,whichcontainsinformationattheoceanregion,isaffectedbythestrikeofthearcuatetrench.Thespace-bornegravimetricdatahelpusconstrainthesourceparametersofamegathrustearthquakewithintheframeofheterogeneousslipmodels.