Finescale Spiral Rainbands Modeled in a High-Resolution Simulation of Typhoon Rananim (2004)  

作　　者：李青青 端义宏 余晖 傅刚 

机构地区：[1]Shanghai Typhoon Institute,Laboratory of Typhoon Forecast Technique/CMA [2]National Meteorological Centre,China Meteorological Administration [3]Laboratories of Ocean-Atmosphere Interaction and Climate and Physical Oceanography,Department of Marine Meteorology,Ocean University of China

出　　处：《Advances in Atmospheric Sciences》2010年第3期685-704,共20页大气科学进展（英文版）

基　　金：supported by the National Basic Research Program of China (2009CB421505);the National Natural Science Foundation of China under Grants Nos.40730948;the National Natural Science Foundation of China under Grants Nos.40575030;the National Natural Science Foundation of China under Grants Nos.40705024;the Shanghai Typhoon Foundation (2009ST09);supported by the National Nature Science Foundation of China under the Grant No.40675060;the program of the Ministry of Science and Technology of the People's Republic of China (2006AA09Z151);the program of China Meteorological Administration(GYHY200706031)

摘　　要：Finescale spiral rainbands associated with Typhoon Rananim （2004） with the band length ranging from 10 to nearly 100 km and band width varying from 5 to 15 km are simulated using the Fifth-Generation NCAR/Penn State Mesoscale Model （MM5）. The finescale rainbands have two types： one intersecting the eyewall and causing damaging wind streaks, and the other distributed azimuthally along the inner edge of the eyewall with a relatively short lifetime. The formation of the high-velocity wind streaks results from the interaction of the azimuthal flow with the banded vertical vorticity structure triggered by tilting of the horizontal vorticity. The vertical advection of azimuthal momentum also leads to acceleration of tangential flow at a relatively high Mtitude. The evolution and structures of the bands are also examined in this study. Further investigation suggests that the boundary inflection points are related tightly to the development of the finescale rainbands, consistent with previous findings using simple symmetric models. In particular; the presence of the level of inflow reversal in the boundary layer is a crucial factor controlling the formation of these bands. The near-surface wavy peaks of vertical vorticity always follow the inflection points in radial flow. The mesoscale vortices and associated convective updrafts in the eyewall are considered to strengthen the activity of finescale bands, and the updrafts can trigger the formation of the bands as they reside in the environment with inflow reversal in the boundary layer.Finescale spiral rainbands associated with Typhoon Rananim （2004） with the band length ranging from 10 to nearly 100 km and band width varying from 5 to 15 km are simulated using the Fifth-Generation NCAR/Penn State Mesoscale Model （MM5）. The finescale rainbands have two types： one intersecting the eyewall and causing damaging wind streaks, and the other distributed azimuthally along the inner edge of the eyewall with a relatively short lifetime. The formation of the high-velocity wind streaks results from the interaction of the azimuthal flow with the banded vertical vorticity structure triggered by tilting of the horizontal vorticity. The vertical advection of azimuthal momentum also leads to acceleration of tangential flow at a relatively high Mtitude. The evolution and structures of the bands are also examined in this study. Further investigation suggests that the boundary inflection points are related tightly to the development of the finescale rainbands, consistent with previous findings using simple symmetric models. In particular; the presence of the level of inflow reversal in the boundary layer is a crucial factor controlling the formation of these bands. The near-surface wavy peaks of vertical vorticity always follow the inflection points in radial flow. The mesoscale vortices and associated convective updrafts in the eyewall are considered to strengthen the activity of finescale bands, and the updrafts can trigger the formation of the bands as they reside in the environment with inflow reversal in the boundary layer.

关 键 词：finescale rainbands dynamic and thermodynamic structure boundary layer instabilities Typhoon Rananim 

分 类 号：P444[天文地球—大气科学及气象学]