云辐射强迫效应对热带气旋发展和结构的影响
投稿时间: 2015-04-21  最后修改时间: 2016-01-14  点此下载全文
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葛旭阳 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044 xuyang@nuist.edu.cn 
许可 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
马悦 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
徐海明 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
基金项目:国家重点基础研究发展计划(973计划)项目(2015CB452803);灾害天气国家重点实验室开放课题(2014LASW-B08);江苏省高校自然科学研究重大项目(14KJA170005)
中文摘要:利用高分辨率中尺度WRF-ARW模式,进行云辐射强迫效应对热带气旋(Tropical Cyclone,TC)发展和结构影响的敏感性试验研究。结果表明,云辐射强迫效应主要通过改变TC云区的辐射分布影响对流活动,进而影响TC的发展和结构。在TC发展阶段,TC内区对流云区云顶的强烈辐射冷却作用和云层内部的辐射增温过程降低了TC中上层的静力稳定度,中下层的变化相对不明显。总体上考虑云辐射效应的试验更易激发出更多更强的对流活动,有利于TC的发展及TC尺度的增大。鉴于云辐射强迫对TC的影响,在TC数值预报中需要更加重视云辐射强迫效应。
中文关键词:云辐射强迫 效应  热带气旋  气旋发展  气旋结构
 
Impacts of cloud-radiative forcing on tropical cyclone intensification and structure
Abstract:Numerous studies have shown that the structure and intensity of tropical cyclones have been restricted by themselves,as well as the interaction between the airflow and boundary layer,the thermal variations of the sea,and so on.With the numerical model widely used in the weather forecast,there has been increasingly great attention paid to the parameterization scheme of the atmospheric model.Numerous findings have shown that the various physical parameterization processes have obvious effects on simulating tropical cyclones.The impacts of the cloud-radiative forcing(CRF) on tropical cyclones is a complicated process,depending on the cloud microphysics parameterization model.Different aerosol distributions hold different CRF.Some studies have shown that solar radiation affects the structure and tracks of tropical cyclones,in which case the CRF will remain a key overhang.Therefore,this work carries out the study of the sensitivity of cloud radiation on the effects of tropical cyclones,and discusses the possible influences of cloud radiation on the development and structure of typhoons.
In order to highlight the influences of CRF on TC,as well as to avoid the disturbance of uncertainty random circumstance factors such as underlying surface and the interaction between TC and environment,two sets of sensitivity simulations were conducted using the high-resolution Weather Research and Forecasting(WRF) model(WRF-ARW)(version 3.3.1).The simulations were solved using bidirectional double nesting,in which every domain had a 241×241 grid point,the horizontal resolution ratio was 9 km and 3 km,and the vertical direction was divided into 28 layers.The cloud microphysical scheme adopted WSM6.The initial conditions originate from an ideal cyclonic vortex which was symmetric.The initial wind speed was 8 ms-1,and the maximum wind radius was 125 km.The tangential wind speed of the initial vortex decreased with height.For the sake of simplicity,this paper uses the f plane.The latitude of the center was 15°N.The underlying surface was a uniform ocean,the sea surface temperature was set to 29℃,and the influence of large-scale atmosphere was neglected.According to the setting wind field,the quality field and thermodynamics field elements were obtained by solving the nonlinear equilibrium equation.The cloud-radiative forcing(CRF) in the WRF was controlled by the namelist parameter “iCloud”.When iCloud=1,the CRF effect was considered in the simulation.Conversely,when iCloud=0,the CRF effects were excluded.Through the comparison of the above two simulations,we can obtain the influence of the CRF effect on the development of TC.
The results show that,mainly by changing the tropical cyclone radiation distribution,the CRF had an effect on the convective activity,as well as the tropical cyclone structure and size.In the development process,the strong cooling along the anvil top and weak warming in the cloudy regions under the forcing of cloud and radiation could reduce the static stability at the middle-upper levels,while the change of the middle-lower levels was relatively less significant.The convective activity of the tropical cyclone was enhanced by the CRF.The tropical cyclone developed faster and had a larger size in the case with the CRF than without it.In view of the considerable impacts of the CRF on the size and strength of tropical cyclone,it is necessary to pay more attention to the CRF in the numerical prediction of tropical cyclones.
keywords:cloud-radiative forcing  tropical cyclone  cyclone intensification  cyclone structure
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