IMPACT OF TC INTENSITY CHANGE ON PRECIPITATION DISTRIBUTION OVER THE NORTHWESTERN PACIFIC

LI Kewei; ZHANG Aoqi; LI Weibiao

doi:10.16032/j.issn.1004-4965.2023.066

Abstract：Previous studies have revealed the close relationships between the intensity change and rainband distributions of tropical cyclones.However,their quantitative characteristics over the northwestern Pacific are yet to be revealed.In this paper,we used the CMA best track dataset and the GPM IMERG precipitation data from June to September 2000-2018.The tropical cyclones over the northwestern Pacific were classified into five categories,namely initiating,slowly strengthening,rapidly strengthening,stable,and weakening typhoons,respectively.The precipitation distribution as well as its changes for various types of tropical cyclones was studied based on a mobile cyclonic coordinate system.It is shown that the radial rainfall of initiating cyclones peaks at 10 km and 40 km away from cyclonic centers,respectively;the radial rainfall of rapidly strengthening cyclones peaks at 10 km and 30 km away from cyclonic centers,respectively;the radial precipitation distributions for both the slowly strengthening and weakening cyclones present a unimodal distribution,with the peaks appearing at 40 km,and 60 km to the centers,respectively.A significant positive correlation exists between the rainfall change of the inner rainband and cyclonic intensity change,whereas a negative correlation exists between the change of the outer rainband and cyclonic intensity change.Moreover,the precipitation changes in various azimuths of cyclonic centers respond differently to intensity change.Specifically,the decrease of precipitation in weakening cyclones mainly occurs on the west side,which is likely related to the cyclonic landing process.These findings could provide observational evidence for the model of tropical cyclones over the northwestern Pacific.