Preliminary Study On Change Of Humidity Field For Typhoons During Landfalling

Few papers are focus on analyzing the humidity field of typhoon, though thereare many works to studying the typhoon's structure with the relative vorticity. Thechanges of humidity fields for 33 typhoon cases landfalled in China are analyzedbefore and after its landfalling, based on the NCEP/NCAR 1°×1°grid analyzed datacover global troposphere. The main results show that the changes of the humidity oftyphoon's moist core can be divided three categories: (1) The humidity becomessmaller in magnitude and area during after landfalling than before; (2) The highhumidity content in typhoon's moist core before landfalling can be maintained afterlandfalling; (3) It appear sophisticated states for the moist content of typhoon's moistcore, that is, the humidity becomes larger from before to after landfalling and viceversa.Analyzing has been made for the vertical changes of humidity content oftyphoon's moist core. The diagnostic results suggest that the humidity of typhoon'smoist core on 500hPa is most sensitive to before and after landfalling of typhoon.That is to say, the humidity content of typhoon's changes sharply from beforelandfalling to after that, and the moist core of typhoon occurs firstly on 500hPa.Besides, the changes of humidity content of typhoon's moist core appear above500hPa.It is a quite important subject of the maintaining time on land for typhoon.Because the more long of the typhoon maintaining on land, the more the disaster is.Chen Lianshou has shown 6 kinds of circulation forms when the typhoon maintainon land and often stop at some place, in addition, his studying indicates that thehumidity is the basic condition for the typhoon's maintaining on land. In recent years, Li Ying and Chen Lianshou analyzed the relation between landfalling typhoon and itshumidity with some typhoon cases. There are no many typhoon cases studying on therelation between the maintaining time on land and humidity of typhoon. The changeof humidity field in typhoon's moist core is closely related to the maintenance oftyphoon after landfalling. The humidity content and area is more high, themaintenance time is long for the landfalling typhoons.