简介：Aheavyrainfallassociatedwiththedeepeningofamonsoondepressionhappenedinthesummerof2005.Thisprocesswasfirstdiagnosticallyanalyzedandthe3Dstructureofthemonsoondepressionwasdiscussed,thenthisstructurewascomparedwiththoseofthemonsoondepressioninSouthAsiaandthelowvortexintheMeiyufront.TheresultsshowedthattheheavyrainfalldirectlyresultedfromamonsoondepressioninSouthChina,andthelarge-scaleenvironmentprovidedafavorablebackgroundforthedeepeningofthemonsoondepression.The3Dstructureofthemonsoondepressionwasasfollows.Inthehorizontaldirection,thereexistedaconvectivecloudbandtothesouthofthemonsoondepression,whichlayinaconvectivelyinstablearea,witharelativelystrongascendingmotioninthemidandlowlevelsofthetroposphere,andtheascendingmotionmatchedwellwithamoisttongue,aconvergencearea,andabandofpositivevorticityinthemidandlowlevelsofthetroposphere.Intheverticaldirection,thedepressionhadanobviouslycycloniccirculationinthemidandlowlevelsofthetroposphere,butnocirculationfromabove300hPa.Themonsoondepressioncorrespondedtoconvergenceandpositivevorticityinthelowlevels,buttodivergenceandnegativevorticityintheupperlevels.Theupwarddraftofthedepressioncouldreachtheupperlevelsofthetroposphereinthewestofthedepression,whilethedescendingmotionlayintheeast.Therewasalow-leveljettothesouthofthedepression,whiletheupper-leveljetwasnotobvious.Thedepressionwasverticallywarmintheupperlevelsandcoldinthelowlevels,andtheaxisofthedepressiontiltedsoutheastwardwithheight,whosecharacteristicsweredifferentnotonlyfromthemonsoondepressioninSouthAsiabutalsofromthelowvortexintheMeiyufront.