摘要
利用1948年1月～2004年12月逐月NCEP/NCAR的全球1000 hPa、850 hPa、700 hPa、600 hPa、500 hPa、400 hPa、300 hPa、200 hPa、150 hPa、100 hPa的10层经向格点风,计算了全球越赤道气流和年变化,分析了全球850 hPa越赤道气流通道的时、空变化特征。指出在研究的时间段内,全球850 hPa越赤道气流有明显的长期趋势变化和年代际变化。近57年,6～8月的45～50°E、5～9月的105～115°E、5～9月和5～11月的130～140°E、2～4月的20～25°E的越赤道气流有明显的加强,6～8月的50～35°W的越赤道气流减弱。夏季索马里的越赤道气流,平均每10年增强0.25 m/s,而130～140°E,5～9月的越赤道气流,平均每10年增强0.32 m/s。奇异谱分析表明,850 hPa越赤道气流的年代际变化和趋势变化的方差贡献达到35%～45%。年际变化的方差贡献不超过30%,还指出夏季太平洋的越赤道气流的强度变化与南方涛动有明显关系,弱南方涛动时,有强的越赤道气流。而索马里急流强度与北大西洋涛动有弱的正相关。
By using monthly NCEP/NCAR meridional gridpoint wind data at the levels of 1 000, 850, 700, 600, 500, 400, 300, 200, 150 and 100 hPa from 1948 to 2004, the intensity of global cross-equatorial flow is calculated. The spatial and temporal variation of global cross-equatorial flows at the 850 hPa level are shown and discussed. The results show that the strength of the 850 hPa global cross-equatorial flows represent obviously long-term variation and interdecadal change during the period. Evidence suggests that the cross-equatorial flow of the passages at 45-50 °E in June to August, 105-115 °E in May to September, 130- 140 °E in May to September and May to November and 20-25 °E in February to April intensified and that the cross-equatorial flow of the passages at 50-35°W in June to August weaken in the past 57 years, with an increase of 0.25m/s/10a for summer Somali cross-equatorial flow and increase of 0.32 m/s/10a for cross-equatorial flow at 130-140 °E in May to September. The results of Singular Spectrums Analysis （SSA） for the time series of cross-equatorial flow indicate that for the cross-equatorial flow at 850 hPa, the interdecadal and long-term trend changes have 35%-45%, and the interannual variation has no more than 30%, in variance contribution. The results also reveal that the interannual variation of intensity of the cross-equatorial flow in summer in the Pacific has significantly correlated with Southern Oscillation. With weak Southern Oscillation, strong Cross-equatorial flow in Pacific will happen. But summer Somali Jet only has little positive correlation with NAO.
出处
《热带气象学报》
CSCD
北大核心
2007年第4期326-332,共7页
Journal of Tropical Meteorology
基金
国家自然科学基金(40275018
90411008)
热带海洋气象科学研究基金
中国气象局热带季风重点开放实验室共同资助
关键词
越赤道气流
气候变化
趋势
奇异谱分析
南方涛动
Cross-equatorial flow
climatic change
trend change
Singular Spectrums analysis Southern Oscillation
