近60年气候冷暖波动背景下西太平洋副高特征的变异及其与海温关系的变化

VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS CHANGEABLE RELATIONSHIP WITH SST UNDER THE BACKGROUNG OF COLD OR WARM CLIMATE FLUCTUATION IN THE RECENT 60 YEARS

采用国家气候中心的副高特征指数资料,美国NCEP/NCAR再分析资料和NOAA的海温资料,利用高斯滤波、滑动平均及相关、合成分析等方法,研究了气候冷暖波动背景下西太平洋副热带高压特征的变异及可能原因。结果表明,随着近60 a气候冷暖波动,副高最显著的变化特征为面积扩大、强度加强、脊点西伸、南界南扩,各指数的年际波动均有所加大。副高强度和西脊点与北半球温度变化具有较好的一致性,但脊线位置变化则相对独立,副高强度及其年际变率在1980年代末显著加强,西脊点在1990年代初显著西伸,其年际变率在1990年代末显著增强,脊线位置呈现北-南-北的摆动,其年际变率在1990年代末显著增强。随着气候变暖,赤道中东太平洋冬季海温升高与副高强度增强的关系有所减弱,与脊点西伸的关系则有所加强,范围扩大;北太平洋冬季海温降低与脊线位置南移的关系有所减弱,但与脊点西伸的关系则有所加强;热带西太平洋冬季海温降低与强度增强、脊点西伸的关系有所加强。气候偏暖期Hadley环流加强、南移的主导作用,以及Walker环流上升支减弱辅助作用,使夏季副高呈现强度加强、面积增大、南扩的特征。

Using subtropical high index data from the National Climate Center, NCEP/NCAR reanalysis data and the NOAA sea surface temperature data and based on the Gaussian filter, moving average and the methods of correlation and synthesis analysis, this study discusses the West Pacific subtropical high （WPSH） and possible reasons for its variation under the background of cold or warm climate fluctuation. The results show that for the climate fluctuation in the recent 60 years, the most significant change of WPSH is the expanding of the area. At the same time, the intensity of WPSH has intensified, the westernmost ridge point has extended westward, and the southern boundary has expanded. The interannual variability of all WPSH indexes has increased. The intensity and the westernmost ridge point of WPSH are consistent with global warming, but the ridge line is dif- ferent. The intensity and its interannual variability of WPSH intensified in the late 1980s, the westernmost ridge point has extended westward in the early 1990s and its interannual variability has intensified in the late 1990s. The ridge line has experienced shifts of north, south and then north again and its interannual variability has also intensified in the late 1990s. As the climate warming, the positive correlation between the equatorial central- eastern Pacific sea surface temperature （SST） in winter and the intensity of WPSH was weakened, but the west- ward extension of west ridge point was enhanced and expanded; The positive correlation between the North Pacific SST in winter and the southward of ridge line was weakened, but the westward extension of west ridge point was enhanced; The negative correlation between the Tropical Western Pacific SST in winter and the intensity of WPSH was increased, and the westward extension of the ridge was strengthened. In the warmer climate period, with the strengthening and southward shift of Hadley circulation and the weakening of Walker circulation＇s rising branch, the summer WPSH have strengthened, expanded, and shifted to the south.