西北太平洋一个超强爆发性气旋的分析

Analyses of a Super Explosive Cyclone over the Northwestern Pacific

利用NCEP(National Centers for Environmental Prediction)提供的CFSv2(Climate Forecast System Version 2)资料和日本高知大学提供的MTSAT-1R(Multi-functional Transport Satellites-1R)卫星红外波段反照率资料,对2013年1月发生在西北太平洋上的一个超强爆发性气旋进行了研究,利用天气分析和诊断分析等方法,详细分析了该爆发性气旋的结构特征。发现该气旋在爆发性发展的后期位于高空急流的北侧,高空的强辐散有利于气旋的发展。气旋上空500hPa的低压槽在14日12UTC显著加深,槽前的正涡度平流有利于海平面气压降低。与气旋伴随的冷锋存在鼻状结构,在800hPa以下,假相当位温随高度降低,低层大气呈对流性不稳定状态。利用涡度方程对气旋进行诊断分析,发现平流项和拉伸项为气旋涡度变化的主要贡献项。设计了围绕气旋中心15(°)×15(°)的区域,发现不同时刻的沿区域四边积分的环流、区域内面积平均的非绝热加热、水汽通量散度和垂直速度4个物理量存在正反馈过程,即气旋爆发性发展的前期存在类似CISK的正反馈机制。

The structure of a super explosive cyclone which occurred over the Northwestern Pacific in January,2013 was investigated by using CFSv2（Climate Forecast System Version 2）data supplied by NCEP（National Centers for Environmental Prediction）,and MTSAT-1R（Multi-functional Transport Satellites-1R）data provided by Kochi University of Japan.It was found that the cyclone was located in the north of the 300 hPa jet stream during the later developing stage.The upper-level divergence provided favorable condition for development of explosive cyclone.A trough at 500 hPa developed at 12 UTC 14January,2013,and the vorticity advection there would intensify this explosive cyclone.There was nose structure in cold front accompanied with this explosive cyclone.The pseudo-equivalent potential temperature dropped with height,which suggested that the air was in convectively instable state.By analyzing the vorticity equation,it was found that advection term and stretching term were the major contribution terms for vorticity change of this cyclone.We built a 15（°）×15（°）domain around the cyclone center,and analyzed the horizontal circulation along the four sides of this domain,area-mean diabatic heating,area-mean vertical velocity,area-mean horizontal convergence of moisture flux within this 15（°）×15（°）domain,and found that there was a positive feedback mechanism which was similar to CISK（Conditional Instability of the Second Kind）in earlier development stage of this explosive cyclone.