Interannual linkage between Arctic/North Atlantic Oscillation and tropical Indian Ocean precipitation during boreal winter
Interannual linkage between Arctic/North Atlantic Oscillation and tropical Indian Ocean precipitation during boreal winter
复制标题
北极/北大西洋涛动与北半球冬季热带印度洋降水之间的年际联系
DOI：
10.1007/s00382-013-1681-4
复制
发表时间：
2014-02-01
期刊：
影响因子：
4.6
通讯作者：
Gao, Miaoni
中科院分区：
文献类型：
--
作者：
Gong, Dao-Yi;Gao, Yongqi;Gao, Miaoni
本文分析了1979-2009年北极涛动(AO)/北大西洋涛动（NAO）与热带印度洋（TIO）冬季降水的年际关系。发现它们之间存在显著的同时遥相关。去除厄尔尼诺/南方涛动和印度洋偶极子信号后，AO/NAO与TIO降水（0°~ 10a°S, 60°~ 80a°E）的相关系数为+0.56，与AO/NAO-出射长波辐射的相关系数为-0.61一致。研究了与AO/ nao -降水联系有关的大气和海洋特征。在正AO/NAO冬季，受西风带引导的罗斯比波在北纬30度和东经70度左右的对流层上层引发持续的正位势高度，并伴有较强的中东急流。同时，有异常的向下空气运动，增强了对流层中下层的气压。增强的阿拉伯高压在北印度洋上空带来了异常北风。因此，异常的跨赤道气流增强了热带辐合带。另一方面，由风应力旋度引起的异常的Ekman输运辐合使中心TIO的温跃层加深。ITCZ的增强和上层海洋热含量的异常都有利于TIO中部的原位降水。研究了卑尔根气候模式第2版IPCC AR4历史气候模拟（1850-1999）中AO/NAO-TIO降水协变。模拟结果较好地再现了印度洋降水异常（特别是沿ITCZ的对流降水）以及相应的地面风、200 hPa反气旋大气环流和上层海洋热含量。观测和模拟的相似性支持了AO/NAO-TIO降水联系的物理稳健性。
In the study authors analyzed the interannual relationship between the Arctic Oscillation (AO)/North Atlantic Oscillation (NAO) and the tropical Indian Ocean (TIO) precipitation in boreal winter for the period 1979-2009. A significant simultaneous teleconnection between them is found. After removing the El Nio/Southern Oscillation and Indian Ocean dipole signals, the AO/NAO and the TIO precipitation (0A degrees-10A degrees S, 60A degrees-80A degrees E) yield a correlation of +0.56, which is also consistent with the AO/NAO-outgoing longwave radiation correlation of -0.61. The atmospheric and oceanic features in association with the AO/NAO-precipitation links are investigated. During positive AO/NAO winter, the Rossby wave guided by westerlies tends to trigger persistent positive geopotential heights in upper troposphere over about 20A degrees aEuro"30A degrees N and 55A degrees aEuro"70A degrees E, which is accompanied by a stronger Middle East jet stream. Meanwhile, there are anomalous downward air motions, strengthening the air pressure in mid-lower troposphere. The enhanced Arabian High brings anomalous northern winds over the northern Indian Ocean. As a result the anomalous crossing-equator air-flow enhances the intertropical convergence zone (ITCZ). On the other hand, the anomalous Ekman transport convergence by the wind stress curl over the central TIO deepens the thermocline. Both the enhanced ITCZ and the anomalous upper ocean heat content favor in situ precipitation in the central TIO. The AO/NAO-TIO precipitation co-variations in the IPCC AR4 historical climate simulation (1850-1999) of Bergen Climate Model version 2 were investigated. The Indian Ocean precipitation anomalies (particularly the convective precipitation along the ITCZ), in conjunction with the corresponding surface winds and 200 hPa anticyclonic atmospheric circulation and upper ocean heat contents were well reproduced in simulation. The similarity between the observation and simulation support the physical robustness of the AO/NAO-TIO precipitation links.