A MODELING STUDY OF NORTHWEST PACIFIC SSTA EFFECT ON PACIFIC STORM TRACK DURING WINTER

A T_(42)L_9 GCM integration is adopted to investigate in detail the effect of Northwest Pacific sea surface temperature anomaly(SSTA)on the Pacific storm track(PST)during winter.Results show that warm(cold)Northwest Pacific SSTA can give rise to significantly increased (decreased)baroelinicity on the north side of the anomaly area and its downstream in such a way as to make the Pacific storm track strengthen(weaken)in its entrance where the 500 hPa synoptic perturbation height variance,kinetic energy,and low-level upward and poteward transient eddy temperature fluxes who exhibit similar features to those of mid-latitude barolinic waves in their developing phases,show great enhancement for the warm case,suggesting that the Pacific track can be reconstructed in its west side only as a result of an external forcing,viz.,warm Northwest Pacific SSTA during winter.

北半球冬季风暴轴维持的一种可能机制

利用对欧洲中期天气预报中心（ＥＣＭＷＦ）每日客观分析资料所作的观测分析及Ｔ４２Ｌ９大气环流模式（ＧＣＭ）所作的数值试验结果，提出了外热源强迫是北半球冬季风暴轴维持的一种可能机制，并试图给出了影响过程的物理图象。

冬季西北太平洋海表温度异常对太平洋风暴轴影响的数值试验

采用Ｔ＿２１Ｌ＿５大气环流模式，详细探讨了冬季西北太平洋海表温度异常对太平洋风暴轴的影响。结果表明：冬季西北太平洋暖海表温度异常能显著增强异常区北侧及下游地区的斜压性，天气尺度扰动方差、扰动动能以及涡动热量通量等也在此风暴轴的入口区得到增强，由此揭示出外热源强迫对太平洋风暴轴的维持和发展起重要作用。

冬季赤道西太平洋海温异常对太平洋风暴轴影响的数值试验

采用Ｔ４２Ｌ９大气环流模式，研究了冬季赤道西太平洋海表温度异常对太平洋风暴轴的影响。结果表明：冬季赤道西太平洋正ＳＳＴＡ能显著增强风暴轴区域天气尺度扰动的强度，与风暴轴发展有关的涡动热量通量和动量通量也在风暴轴的入口区得到增强，由此揭示出低纬外热源强迫对太平洋风暴轴的维持和发展起重要作用。