Influences of Different PBL Schemes on Secondary Eyewall Formation and Eyewall Replacement Cycle in Simulated Typhoon Sinlaku (2008)  

作　　者：张玉涛 蒋星鑫 谭本馗 

机构地区：[1]Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University

出　　处：《Acta meteorologica Sinica》2013年第3期322-334,共13页

基　　金：Supported by the National Basic Research and Development(973)Program of China(2009CB421504);National Natural Science Foundation of China(40921160380)

摘　　要：The effects of different planetary boundary layer （PBL） processes on the secondary eyewall formation （SEF） and eyewall replacement cycle （ERC） in Typhoon Sinlaku （2008） are investigated by using the Weather Research and Forecasting （WRF） model with six different PBL schemes. The SEF and ERC have been successfully simulated with all the six PBL schemes and the mechanism for the SEF and ERC proposed in our previous study has been reconfirmed. It is demonstrated that both the intensification of the storm and the inward-moving outer spiral rainband contribute to the SEF. After the SEF, the associated diabatic heating enhances the secondary eyewall further, and the transfer of moist air from outer region to the primary eyewall is cut off by the secondary eyewall. In such a way, the primary eyewall dies and an ERC completes. It is found that some simulated features of the SEF and ERC, such as the time and location of the SEF and duration of the ERC, do vary from one simulation to another. In order to describe the features of the SEF and ERC quantitatively, a concentric eyewall index （CEI） is defined and a threshold of the CEI is suggested to determine the onset of the secondary eyewall. The differences in the simulated SEF and ERC are discussed and some possible causes are suggested. In addition, based on the CEI threshold and the conservation law of angular momentum, a formula to predict the location of SEF is also proposed and applied to all the six simulations. The success and failure of the formula are then discussed.The effects of different planetary boundary layer （PBL） processes on the secondary eyewall formation （SEF） and eyewall replacement cycle （ERC） in Typhoon Sinlaku （2008） are investigated by using the Weather Research and Forecasting （WRF） model with six different PBL schemes. The SEF and ERC have been successfully simulated with all the six PBL schemes and the mechanism for the SEF and ERC proposed in our previous study has been reconfirmed. It is demonstrated that both the intensification of the storm and the inward-moving outer spiral rainband contribute to the SEF. After the SEF, the associated diabatic heating enhances the secondary eyewall further, and the transfer of moist air from outer region to the primary eyewall is cut off by the secondary eyewall. In such a way, the primary eyewall dies and an ERC completes. It is found that some simulated features of the SEF and ERC, such as the time and location of the SEF and duration of the ERC, do vary from one simulation to another. In order to describe the features of the SEF and ERC quantitatively, a concentric eyewall index （CEI） is defined and a threshold of the CEI is suggested to determine the onset of the secondary eyewall. The differences in the simulated SEF and ERC are discussed and some possible causes are suggested. In addition, based on the CEI threshold and the conservation law of angular momentum, a formula to predict the location of SEF is also proposed and applied to all the six simulations. The success and failure of the formula are then discussed.

关 键 词：eyewall replacement cycle secondary eyewall formation PBL scheme 

分 类 号：P444[天文地球—大气科学及气象学] TP331[自动化与计算机技术—计算机系统结构]