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热带印度洋与热带太平洋是全球海气耦合最活跃的区域之一,两者的海温场中均存在着显著的年际变化模态,而且这两个洋盆间的海温异常模态间是相互联系的.本文采用一个复杂的全球海气耦合模式,模拟了两组分别包含和不包含热带印度洋海温年际变化对热带大气强迫的耦合试验,对比研究印度洋海温年际变化在厄尔尼诺事件演变中的贡献.结果表明,热带印度洋海温年际变化的存在使得厄尔尼诺事件的成熟期强度增加,且在厄尔尼诺的发展年秋季出现明显的快速增长.但在厄尔尼诺衰亡年,热带印度洋海温年际变化却使得热带太平洋暖海温减弱甚至转变为冷海温,使得厄尔尼诺事件的演变周期减短.具体来讲,发生于厄尔尼诺发展年的印度洋偶极子正异常事件能够在热带印度洋东部到热带西太平洋之间强迫出一支异常的下沉气流及异常Walker环流,加强原有的西太平洋低层西风异常,通过海洋平流及波动调整过程增强厄尔尼诺期间太平洋的暖海温异常;而在厄尔尼诺衰亡年出现的印度洋全洋盆增暖则在南亚季风爆发的背景下,在印度大陆上空产生一支明显的异常上升气流,激发西太平洋东传的Kelvin波及低层大气的东风异常,削弱了热带太平洋洋面的西风异常,促使厄尔尼诺从暖位相向冷位相转化,并使得西北太平洋出现反气旋式大气环流和降水的减少.因此,印度洋海温偶极子模态主要影响厄尔尼诺事件的发展阶段,而印度洋海温洋盆一致变化模态显著影响厄尔尼诺事件的衰亡阶段,两者均可通过改变大气环流而遥强迫太平洋海域.
The tropical Indian Ocean and the tropical Pacific Ocean are one of the most active areas of global ocean-atmosphere coupling. Both of them have significant interannual variation modes in the SST field, and the SST anomalies between the two ocean basins are Inter-related.In this paper, a complex global model of ocean-atmosphere coupling was used to simulate the coupling experiments of two sets of inter-annual variations of tropical Indian Ocean sea temperature with and without tropical oceanic forcing, and to compare the interannual variations of SST in the Indian Ocean between the El Nino events The results show that the interannual variation of SST in the tropical Indian Ocean increases the maturity of the El Niño event and shows a clear and rapid increase in El Nino's development in the fall.However, during the El Ni 衰 decay years, In the tropical Pacific, however, the warm SST decreases or even changes to cold SST, which shortens the evolutionary period of the El Nino event.Particularly, positive anomalies of the Indian Ocean dipole occurring in the El Niño years can occur from the eastern tropical Indian Ocean to the tropical Western Pacific forced an abnormal sinking airflow and abnormal Walker circulation, strengthening the original West The westerly anomalies in the lower level of the Pacific Ocean enhance the warm SST anomaly in the Pacific Ocean during El Niño through the processes of ocean advection and fluctuation. In the El Niño decay year, the warming of the whole ocean basin occurred over the Indian continent in the background of the onset of the South Asian monsoon An obvious anomalous upwelling airstream triggered Kelvin waves eastward in the western Pacific and easterly anomalies in the lower atmosphere, weakening the westerly anomalies over the tropical Pacific Ocean, prompting El Niño to transform from warm to cold phases and causing anti-cyclonic Atmospheric circulation and precipitation reduction.Therefore, the dipole mode of the Indian Ocean SST mainly affects the development stage of the El Niño event, while the consistent change mode of the SSTP of the Indian Ocean significantly affects the stage of El Nino event decay, both of which can be achieved by changing the atmospheric circulation The remote forced the Pacific Ocean.