冬季北太平洋风暴轴的年际型态及其与大气环流的关系

利用NCEP/NCAR再分析资料,运用31点带通数字滤波、线性相关和合成分析方法,研究了1961/1962—2010/2011年冬季北太平洋风暴轴西部、东部区域强度指数的年际演变特征,划分了风暴轴的典型型态,并进一步探讨了与同期北半球500 hPa位势高度场和SLP的关系。结果表明:风暴轴气候态的极大值区域位于中纬度北太平洋中西部,最大值点的频数集中区域和均方差分布的异常中心都有两个。风暴轴西部和东部区域强度指数(WI和EI)的年际演变具有独立性,典型型态可分为单、双中心型两类。WI(EI)指数与北半球500 hPa位势高度场的相关分布类似于WP(PNA)遥相关型;单中心型风暴轴偏强时,极涡南扩,平均槽加深;呈双中心型时,极涡明显偏西。WI(EI)指数与SLP的相关分布类似于NPO(NAO)遥相关型;单中心型风暴轴偏强(弱)时,SLP距平场呈AO遥相关型的正(负)异常位相。

Interannual patterns of winter North Pacific storm track and its relationship with atmospheric circulation

Based on the NCEP/NCAR reanalysis data,using the methods of 31-point band-pass digital filter,linear correlation and composite analysis,this paper studies interannual variations of the western and eastern intensity index(WI and EI) of North Pacific storm track in winter from 1961/1962 to 2010/2011,defines interannual typical patterns of the storm track,and further discusses their relationships with 500 hPa geopotential height and sea level pressure(SLP) fields over Northern Hemisphere.Results show that:(1)Winter North Pacific storm track is characterized by a single maximum region in the climatological mean and two maximum regions of both mean square error distribution and climatological frequency concentration areas of maximum point at each year.(2)Interannual variations of WI and EI are partially independent,and winter North Pacific storm track can be further defined as two typical patterns(single-center pattern and double-center pattern).(3)The correlation distribution of WI(EI) with 500 hPa geopotential height field is analogous to WP(PNA) teleconnection pattern.When the single-center pattern storm track is strong,the polar vortex expands southward and the three average troughs deepen.When the double-center pattern storm track exists,the polar vortex is significantly westward.(4)The correlation distribution of WI(EI) with SLP field is analogous to NPO(NAO) teleconnection pattern.When the single-center pattern storm track is strong(week),SLP anomaly field presents a positive (negative) phase of AO teleconnection pattern.