中东太平洋赤道辐合带的季节和年际变化特征

Seasonal and Interannual Variation Characteristics of the Intertropical Convergence Zone in the Central East Pacific

摘要: 为了研究中东太平洋赤道辐合带在不同时间尺度上的变化特征，本文采用1979~2017年GPCP (Global Precipitation Climatology Project) 2.5˚ × 2.5˚全球逐月平均降水资料，着重研究了CEP-ITCZ关键区域(180˚W~110˚W, 2.5˚S~22.5˚N)，结果表明：1) 从月变化尺度上来看，纬向上，CEP-ITCZ是一个东西震荡过程，整体经历了东移加强(3月~8月)，西撤稳定(9月~11月)，西移衰退(12月~次年2月)三个阶段；经向上，CEP-ITCZ是一个南北振动过程，3至9月份CEP-ITCZ整体逐渐北跳，从9月份到次年的2月份开始南撤，逐渐退至原来位置，9月份时北跳至最北处；2) 从季节变化尺度上来看，四季CEP-ITCZ总体呈现一个发展，旺盛，平缓，衰退的过程。位置上，CEP-ITCZ整体夏秋季偏北，冬春季偏南；3) 从年际变化尺度上来看，CEP-ITCZ是一个西移发展，东移衰弱交替变化的波动过程，2010年之前，CEP-ITCZ的波动通常为2~4年一个周期，2010年以后CEP-ITCZ的波动幅度开始加剧，周期变得不稳定；4) 在强厄尔尼诺发生时，CEP-ITCZ整体位置随之大幅度南撤，到达峰值状态时南撤至最南处，之后开始北退回到原来位置。同时每年的1月、2月、3月、4月、12月，CEP-ITCZ强度与nino3.4指数有很大的相关性；而在全年的12个月中，CEP-ITCZ面积指数与nino3.4指数均有很大的相关性。

Abstract: In order to study the variation characteristics of the Central East Pacific-Intertropical Convergence Zone (CEP-ITCZ) on different time scales, based on the Global Precipitation Climatology Project 2.5˚ × 2.5˚ global monthly mean Precipitation data from 1979 to 2017, this paper focuses on the CPE-ITCZ key region (180˚W~110˚W, 2.5˚S~22.5˚N), the results show that: 1) from the perspective of monthly change scale, the CEP-ITCZ is an east-west oscillation process, which has experienced three stages: eastward strengthening (March~August), westward retreating stable (September~November), westward retreating declining (December~February). In latitudinal direction, CEP-ITCZ is a north-south vibration process. From March to September, the whole CEP-ITCZ gradually jumps northward, and from September to February of the next year, it starts to retreat southward and gradually falls back to its original position. In September, it jumps northward to its northernmost point. 2) From the perspective of seasonal variation scale, the four seasons of CEP-ITCZ generally show a process of development, prosperity, gentle, and decline. In terms of location, CEP-ITCZ is north in summer and autumn, and south in winter and spring. 3) From the perspective of annual variation scale, the inter-annual variation of CEP-ITCZ is a westward development. Before 2010, the fluctuation of CEP-ITCZ was usually a cycle of 2~4 years. After 2010, the fluctuation range of CEP-ITCZ began to increase and the cycle became unstable. 4) During the occurrence of strong El Nino, the position of CEP-ITCZ then retreated south to the most south when it reached the peak state, and then began to retreat north to the original position. In January, February, March, April and December, CEP-ITCZ intensity was significantly correlated with nino3.4 index. In the 12 months of whole year, the CEP-ITCZ area index and nino3.4 index have a great correlation.