北太平洋风暴轴的三维空间结构

文中利用最新的0.5°×0.5°分辨率QuikSCAT(QuikBird Satellite Microwave Scatterometer Sea Winds Data)海面风场资料、NCEP(National Center for Environmental Prediction)的10 m高度风场资料和全球客观再分析资料,对1999-2005年冬季(1月)和夏季(7月)北太平洋风暴轴的三维空间结构进行了分析,发现冬季北太平洋风暴轴的强度较强,呈明显的纬向拉伸带状分布特征,位置偏南.夏季北太平洋风暴轴的强度较弱,位置偏北.根据不同高度上位势高度方差的水平分布特征,绘制了北太平洋风暴轴的三维结构示意图.利用高分辨率QuikSCAT资料对风暴轴特征的刻画更为细致,不但验证了Nakamu-ra在南大洋发现的双风暴轴现象,而且还发现在北太平洋和北大西洋下层分别存在"副热带风暴轴"和"副极地风暴轴"两个风暴轴.对1999-2005年冬季北太平洋气旋和反气旋的移动路径进行的统计分析,为北太平洋"双风暴轴"的存在提供了强有力的证据.

Three-dimensional structure of storm track over the North Pacific

Storm track is a region where in the synoptic eddy activity is statistically most prevalent and intense. At daily weather charts, it roughly corresponds to the mean trajectories of cyclones or anticyclones. In this paper, the recent 0.5°×0.5° horizontal resolution QuikSCAT (QuikBird Satellite Microwave Scatterometer Sea Winds Data) wind data, NCEP (National Center for Environmental Prediction) 10 m-height wind data and the global reanalysis data at various pressure-levels are employed to document the spatial structure of storm track over the North Pacific in the winter (January) and summer (July) from 1999 to 2005. It is found that in winter the intensity of storm track over the North Pacific is stronger and its position is located in lower-latitude with showing distinct zonal shaped distribution. While in summer, the intensity of storm track over the North Pacific is weaker and its position is located in higher-latitude. Based upon the characteristics of horizontal distributions of geopotential height variance at various pressure levels, three dimensional schematic diagrams of storm track in winter and summer are plotted, respectively. Further analyses of high-resolution QuikSCAT wind data indicate that this data can depict the storm track in detail. Not only some previous results on double storm tracks over the Southern Oceans detected by Nakamura are confirmed, but also some new discoveries about double storm tracks over the North Pacific and the North Atlantic, named as subtropical storm track and subpolar storm track respectively, are found. The statistical analyses of cyclone tracks and anticyclone tracks in the winters from 1999 to 2005 over the North Pacific provided a solid evidence for the existence of double storm tracks over the North Pacific.