北太平洋风暴轴异常变化特征及其与纬向风场的关系研究

摘要本文通过对300 hPa5、00 hPa和850 hPa的北太平洋风暴轴(PST)的异常研究,分别提取出两个主异常模态进行比较。分析表明在三层的第一主模态都主要对应有PST异常的准10 a的周期变化;而对300 hPa和500 hPa的第二主模态,以及850 hPa的第三模态,对应有更长时间的趋势变化。进一步通过相关的分析,说明PST的异常从低层到高层的变化存在一定的一致性。通过PST与纬向风场在300 hPa的相关分析发现,两个模态与纬向风场的异常在空间上都呈同位相的分布,说明高层纬向风场异常与PST发展可能存在一种互相反馈的作用。进一步通过斜压增长率和水平两维的E-P通量矢的合成分析发现,这种反馈作用,无论从纬向风场异常所产生的环境斜压增长条件的改变,还是从平均动能与扰动动能的转化关系,都是存在的。

ANALYSIS OF THE NORTH PACIFIC STORM TRACK ANOMALY AND THE RELATIONSHIP WITH ZONAL WIND

The first two leading modes of the anomalious north Pacific storm track(PST) with vertical structure are investigated.It is found that the first leading mode shows a quasi-decadal of PST variation,and the second leading mode shows a trend of PST.By the correlating analysis with zonal wind field,it is found that the two leading modes are on the same phase of the zonal anomaly wind field,which implies that there may be a feedback between PST and zonal wind field.Therefore,by using the eddy growth rate and horizontal E-P flux,it shows that the feedback between PST and zonal wind is represented either from the Eddy growth rate or from the translation from mean kinetic energy to transient kinetic energy.