印度洋海盆增暖及ENSO对西北太平洋热带气旋活动的影响
Impact of Indian Ocean Basin Warming and ENSO on Tropical Cyclone Activities over the Western Pacific
-
摘要: 本文主要分析1950～2010年间印度洋海盆增暖和西北太平洋热带气旋(TC)活动的关系, 并与ENSO对西北太平洋TC活动的影响相比较, 结果表明:印度洋海盆异常增暖与西北太平洋地区总TC生成年频数尤其是弱TC相关较好, 印度洋海盆异常增暖, 西北太平洋地区为异常的反气旋, 对流抑制, 降水偏少, 不利于TC的生成, 反之亦然。而ENSO对西北太平洋热带气旋的影响, 主要体现在对强TC的年生成频数的影响, El Niño 发展年, 季风槽加深东伸, TC生成位置偏东, 由于TC在海洋上的生命史较长, TC的平均强度偏强, 因而强TC年生成频数偏多;La Niña发展年, 季风槽较浅, TC生成位置偏西, TC的平均强度偏弱, 强TC年生成频数偏少。但是ENSO指数与强TC年频数的相关有着年代际的变化, 在1950～1969年和1990～2009年间, ENSO指数和强TC年频数相关很好, 分别为0.532和0.687, 而在1970～1989这二十年间, 两者相关很弱, 只有0.081。Abstract: The relationship between warming of the Indian Ocean basin and tropical cyclones (TCs) in the Western North Pacific (WNP) was investigated and compared with that between El Niño-Southern Oscillation (ENSO) and TCs in the WNP. Abnormal warming of the Indian Ocean basin is correlated well with the total TC frequency (especially for weak TCs) in the WNP. Warming of the Indian Ocean basin occurs during the abnormal anticyclone in the WNP, which suppresses convection and TC generation, and vice versa. ENSO affects mainly the frequency of intense TCs in the WNP. In an El Niño development year, the monsoon trough deepens and stretches eastward, causing TCs to be borne eastward. Because TCs have longer lifetimes over the ocean, the frequency of intense TCs increases. In a La Niña development year, the monsoon trough is shallow, causing TCs to be borne westward, decreasing the frequency of intense TCs. The relationship between ENSO and the frequency of intense TCs also exhibits a decadal variation. The correlation coefficient of the ENSO index and TC frequency was 0.532 and 0.687 in 1950-1969 and 1990-2009, respectively, whereas it was only 0.081 in 1970-1989.
下载: