摘要
利用１９５８～１９９８ 年ＮＣＥＰ／ＮＣＡＲ再分析月平均１００ ｈＰａ 高度场和风场资料， 依据大气环流观测事实及天气学原理， 较客观地定义了描述南亚高压活动的特征参数， 然后对南亚高压的年际及年代际变化特征进行了系统的诊断分析。发现北半球中低纬１００ ｈＰａ 环流异常具有空间整体性和时间持续性， 即北半球中低纬１００ ｈＰａ 环流同时加强或同时减弱， 并且其整体异常具有明显的年代际变化。南亚高压面积和强度的变化存在３．８ 年的振荡周期，与ＥＮＳＯ 的循环周期一致。南亚高压的中心和脊线在夏季较为稳定，较大的年际差异出现在春季。高压面积和强度的年际变化最明显， 并且面积大、强度强的年份往往与ＥｌＮｉｎｏ 年相对应。南亚高压的位置和强度还存在明显的年代际变化， 自１９７８ 年以后， 冬半年南亚高压脊线南移， 中心东移， 面积增大， 强度增强， 夏半年南亚高压的位置变化不很明显， 但是面积和强度也增大增强。这种年代际异常与低层大气系统及赤道太平洋海温的年代际异常一致。南亚高压强度距平与热带海洋ＳＳＴＡ 密切相关， 与印度洋海区的同期相关最好。南亚高压强度异常对印度洋ＳＳＴＡ 的响应时间为０～５ 个月， 对赤道中东太平洋ＳＳＴＡ 的响应时间为?
The interannual and interdecadal variations of the South Asia High (SAH) are studied by use of the 40-year (1958～1998) NCEP/NCAR monthly mean reanalysis data It is found that there are integrity and consistency in the 100 hPa height field during the Northern Hemisphere summer, the geopotential heights at the 100 hPa level increase or decrease simultaneously Such kind of anomalies can also last a long period The variations of both the area and the intensity of the SAH have an oscillation period of 3 8 years, which is consistent with that of the ENSO Both the locations of the center and the ridge line of the SAH are relatively stable in summer while obviously different with interannual variations in spring The remarkably interannual variations of the area and the intensity of the SAH occur throughout the year, and the large area and the strong intensity are always in correspondence with the El Nio year Since 1978, the ridge line of the SAH migrates southward and its center shifts eastward, meanwhile, its area and intensity increase year by year Such an interdecadal variation corresponds to the interdecadal anomalies in the low level atmosphere and SSTA of the equatorial Pacific The results also show that, there is a good correlation between the intensity anomalies of the SAH and the tropical ocean SSTA The response time for intensity anomalies of the SAH to Indian Ocean SSTA is 0～5 month while to middle and eastern equatorial Pacific, 4～6 month Such a fairly good lead-lag correlation perhaps manifests the propagation of the teleconnection phenomenon among the climate system Due to the obviously interannual and interdecadal variations of the SAH, we suggest that the SAH be also considered as a strong signal to the climate system and we study and predict the regional climate anomaly by analyzing the anomaly of the SAH
出处
《大气科学》
CSCD
北大核心
2000年第1期67-78,共12页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目!"我国重大气候灾害的形成机理和预测理论的研究"
国家自然科学基金!49735170
大气科学和地球
关键词
南亚高压
年际变化
年代际变化
气压
South Asia high
interannual variation
interdecadal variation
