无旋转风分量在台风“桑美”急剧增强和急剧减弱过程中的分析和应用  

Analysis and Application of Irrotational Wind Component in the Drastically Increasing and Decreasing Processes of 'Saomai' Typhoon

作　　者：邓涤菲[1,2] 周玉淑[1] 

机构地区：[1]中国科学院大气物理研究所,北京100029 [2]中国科学院研究生院,北京100049

出　　处：《高原气象》2011年第2期406-415,共10页Plateau Meteorology

基　　金：国家重点基础研究发展规划项目(2009CB421505);科技部公益性行业(气象)科研专项(GYHY200906004);国家自然科学基金项目(41075044;41075079)共同资助

摘　　要：利用日本气象厅区域谱模式(RSM)的20 km分辨率再分析资料,对2006年第8号台风"桑美"在近海急剧增强和登陆后急剧减弱时的高低层辐散、辐合特征进行了对比分析。结果表明,利用调和—余弦计算方法得到的无旋转风分量较散度场能更明显地反映台风"桑美"在近海急剧增强和登陆后急剧减弱时的风场变化特征。在台风急剧增强过程中,台风"桑美"的无旋转风分量在850 hPa层上有一个从辐散变为辐合的过程;而在台风急剧减弱过程中,高层的无旋转风分量变化不明显,中低层的辐合层厚度降低,低层无旋转风分量的辐合大大加强,辐合最强区从台风外围转移至台风中心,使得低层辐合大于高层辐散,并最终导致台风中心逐渐被填塞。对台风"桑美"无旋转风分量变化的分析表明,无旋转风分量的变化对台风急剧增强和急剧减弱有一定的指示作用。当资料分辨率较高时,用无旋转风分量的分布来分析台风低层辐合、高层辐散的动力结构较以前只用一个标量场(散度)的分析更为清晰,且分解后的风分量可以直接给出台风中无旋转风和无辐散风分布的结构特点。Using the Regional Spectrum Model（RSM） reanalysis data from Janpan Meteorology Agency with a horizontal resolution of 20 km and a time interval of 6 h,the convergence and divergence characteristics of the lower and upper levels of the super typhoon ＇Saomai＇（0608） in the drastically increasing and decreasing processes were analyzed.The results show that the irrotational wind component is obtained from the limited regional harmonic-cosine series expansion wind partition method is more than the wind horizontal divergence to significantly reflect the variation characteristic of wind field in the processes of increasing and decreasing of ＇Saomai＇.When ＇Saomai＇ significantly increases over some distance offshore,there is a change of irrotational wind component from divergence to convergence on 850 hPa;when ＇Saomai＇ decreases,the irrotational wind divergence intensification almost does not change in the upper level,and the thickness of convergence level reduces in the middle and lower level,but the convergence of irrotational wind component abruptly strengthens in the lower level,the strongest wind convergence region shifts from the outside cloud wall areas to the inner part of the eye of typhoon ＇Saomai＇,which makes the convergence of lower level exceeds the divergence of upper levels,and causes the typhoon center filled up.So the irrotational wind component has some indicative functions in the wind change of increasing and decreasing processes of typhoon,especially when the horizontal resolution is relative high,from the scalar quantity-horizontal wind divergence,it can not analyze clearly the dynamic structure of wind convergence in the lower level and divergence in the upper level,but the irrotiontal wind component is more intuitional and clear to reflect this structure.

关 键 词：台风“桑美” 无旋转风分量 辐合 辐散 

分 类 号：P444[天文地球—大气科学及气象学]