大气季节内振荡对印度洋—西太平洋地区热带低压/气旋生成的影响

文中利用EOF分析大气季节内振荡 (MJO)的时空变化的方法 ,研究了 1996年 9月～ 1997年 6月间的MJO活动对生成在印度洋—西太平洋海域的热带低压 /气旋的影响。结果发现 ,除西北太平洋之外 ,发生在其他区域的热带低压 /气旋有半数以上生成在向东移动的MJO的湿位相中。伴随MJO的向东传播 ,热带低压 /气旋平均生成位置也随之向东移动 ,而生成在西北太平洋的热带低压 /气旋分别受到向东和向西传播的MJO影响

MODULATION OF TROPICAL DEPRESSION/CYCLONE OVER THE INDIAN-WES TERN PACIFIC OCEANS BY MADDEN-JULIAN OSCILLATION

The Madden-Julian Oscillation(MJO) is a dominant mode ofintraseasonal variability in the tropical atmosphere;it is characterized by an eastward propagating tropical convective anomalies and associated with circulation anomalies with a time period between 30 to 60 days.Since Madden and Julian firstly observed the MJO (Madden and Julian,1971),it has been extensively studied in the past decades.Studies suggested that the MJO has a baroclinic mixed Kelvin and Rossby wave structure in the Indian and the western Pacific Oceans,where the equatorial wave is strongly coupled to convection with eastward propag ation in convection atroughly 5 m/s. Kelvin waves propagate eastward out of the convective regions is at phase speeds of 10~12 m/s(Hendon and Salby,1994),and is generally manifested as an east ward propagating,equatorialy-trapped,wave number one,baroclinic oscillation in the tropical wind field (Madden and Julian,1994).