Comparative Analysis of Phased Impact on Hunan of Typhoon Chaba
Based on the conventional observation data,reanalysis data and dual-polarization radar data,combined with the Hybrid Single Particle Lagrangian Integrated Trajectory Model(HYSPLIT),the water vapor sources and dual-polarization characteristic of the three stages(the pre-TC squall line,typhoon inverted trough and low pressure)in Hunan of being affected by the typhoon"Chaba"in 2022 are compared and analyzed.The characteristics of short-term and short-term typhoon precipitation are discussed.① The water vapor during the stage of pre-TC squall line mainly comes from the western Pacific and the Poyang lake,and is transported to northern Hunan along the easterly wind outside the typhoon,which converges with the northeasterly wind.The stage is characterized by cumulus precipitation features,with band-shaped echoes and a lower centroid.The column of differential reflectivity factor(ZDR)extends beyond 7km,the value of ZDR,specific differential phase(KDP)and correlation coefficient(CC)are larger at 2km altitude.It shows that large flat raindrops with high number concentration are dominant in this stage.② The water vapor in the inverted typhoon trough stage is transported from the South China Sea and western Pacific,and is transported to central Hunan along the southeast airflow in front of the trough.The stage shows stratus precipitation characteristics.The low-level profile reflectivity factor ZH,KDP and ZDR values are significantly low,while the value of CC is large.The raindrops with low number concentration are thus indicated as being dominant in this stage and the convection is weak.CC has a bright band feature at 5km altitude.The continuous spiral rain belt of stratiform cloud causes a"train effect"heavy rainfall.③ The water vapor in the stage of the low pressure phase mainly comes from the Indochina Peninsula,Beibu Gulf and South China Sea and it is transported to southeastern and northeastern Hunan with the low pressure.The stage is characterized by mixed precipitation,similar to the pre-TC squall line stage,which exhibits low centroid features and a wide area of high values of KDP(≥1.7 º/km)in the mid-to-low levels.Compared to the first stage,the ZDR intensity is weaker.It shows that the raindrops with high concentra-tion are predominant in this stage.The research results contribute to understanding the precipitation characteristics under the influence of typhoon.
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