亚洲夏季风环流结构与热带印度洋偶极型海温异常

使用T42L28大气环流模式就夏季风时期大气对印度洋海温偶极子型异常的响应进行了数值试验研究，结果表明，印度洋偶极子型海温异常可以引起感热和潜热加热异常并进而形成异常辐合辐散，导致热带印度洋及其邻近地区夏季降水异常。同时此热带扰动可激发或造成中纬度异常波列。通过改变季风区温度场分布，偶极子型海温强迫可以影响大气的正／斜压环流结构和斜压性强弱。强的纬向风垂直切变趋向于靠近海洋异常偏暖的地区。不论是正偶极子型强迫或负偶极子型强迫，西太平洋暖池和东亚地区的大气环流均出现异常并激发出中纬度的异常波列，但异常类型并未显著反相。

Simulated Structural Changes of Asian Summer Monsoon Circulation in Association with Indian Ocean Dipole SSTAs

The response of the atmospheric circulation to the Indian Ocean dipole(IOD) sea surface temperature anomalies(SSTA) during boreal summer has been investigated in the present article using a T42L28 atmospheric general circulation model.The IOD is able to induce anomalous changes in surface fluxes of both the sensible heat and latent heat,causing the anomalous divergence in the troposphere,and henceforth resulting in the anomalous rainfall in the tropical Indian Ocean and its surrounding regions.The IOD SST anomalies force the atmosphere to change its temperature spatial distributions,which induces the modifications of the monsoon circulation baroclinicity.Both the barotropic and baroclinic structures of the monsoon circulation are hence to change.The stronger vertical shear of the zonal wind is simulated in the regions above and around the warming pole of the dipole.Interestingly,if the atmosphere is forced either by the positive IOD SSTA or by the negative IOD SSTA,the apparently anomalous changes of circulations appear in both the warming pool region in western Pacific and East Asia.However,the scenarios of the anomalous circulations with the forcing of positive IOD SSTA are found not to be opposite to those with the negative IOD events.Furthermore,the IOD SSTA is able to change the circulations not only in the tropical region but also in the extra tropics,suggesting the anomalous wave disturbances in the westerlies in the Northern Hemisphere.