热带印度洋和太平洋ISO活动特征的异同

Similarities and Differences of ISO Activity Characteristics over the Tropical Indian Ocean and Pacific

基于再分析资料,对比分析了热带印度洋和太平洋地区大气季节内振荡(ISO)活动特征的异同。结果表明:印度洋和西太平洋地区ISO活动中心在4月和10月存在季节性跳跃,并且ISO在西太平洋地区活动中心位置南北跳跃的经向距离较印度洋偏大。ISO较强的活动中心也是ISO强度年较差较大的地区,并且各个活动中心ISO强度达到最强的时间存在明显的差异。ISO活动存在显著的年际和年代际变化,在20世纪80年代ISO的活动强度和变化趋势都存在一个明显的转折。夏季印度洋和西太平洋地区ISO都存在较强的北传,赤道地区印度洋ISO强度较强,而赤道以外地区西太平洋ISO强度较强;并且ISO在西太平洋地区北传的速度较印度洋偏慢。无论是冬季还是夏季,当ISO活跃于印度洋和西太平洋时,ISO的空间分布和垂直结构特征都有着明显的差异。

The characteristics of atmospheric Intraseasonal Oscillation(ISO)activity over the tropical Indian Ocean and the Pacific are compared based on the reanalysis data.The results show seasonal jumps in the ISO activity centers over the Indian Ocean and the western Pacific in April and October.In addition,the meridional jumping distance of the ISO activity center over the western Pacific is larger than that over the Indian Ocean.The activity centers of stronger ISO are also the areas with greater annual amplitude in ISO intensity,and the ISO intensity of each activity center reached the peak at significantly different times.Considerable interannual and interdecadal variation is observed in ISO activity,and the intensity and variation trend of ISO show an obvious turning point in the 1980s.In summer,a strong northward propagation of ISO occurs over the Indian Ocean and the western Pacific.The equatorial ISO over the Indian Ocean is stronger than the ISO beyond the equator,and the ISO beyond the equator over the western Pacific is stronger than the equatorial ISO.Moreover,the northward propagation of ISO is slower over the western Pacific Ocean than over the Indian Ocean.When the ISO is active over the Indian Ocean and Western Pacific in winter and summer,its spatial distribution and vertical structure characteristics are obviously discrepant.