基于COSMIC卫星观测数据的平流层重力波的全球分布特征研究

本文利用2007年1月至2012年12月的COSMIC卫星温度剖线,从中提取了垂直波长在3~10 km的重力波扰动信息,进而分析了全球平流层大气重力波的分布特征.赤道地区低平流层重力波表现出明显的准两年变化,这种变化与风场的准两年变化具有明显的相关性,向下发展速度约为1 km/月;赤道地区高平流层(35 km以上区域)的重力波活动则存在明显的半年变化.中高纬度重力波活动主要表现为冬季强夏季弱.在南极地区存在着与急流的时间、空间以及强度变化密切相关的重力波分布特征,这说明在南极极夜急流是非常重要的一个重力波源;而在北极极夜急流的作用则没有那么强.此外,通过考察不同高度的重力波活动特征,我们发现:30 km以下重力波活动较强区域主要在赤道地区且与强对流区分布基本吻合,地形诱发的以及与天气系统相关的强重力波活动在该高度范围内同样出现;而在30 km以上的区域重力波活动强度分布则会出现与平流层爆发性增温以及极夜急流有关的变化.

An investigation of the global morphology of stratosphere gravity waves based on COSMIC observations

Using the temperature profiles obtained by COSMIC satellite from January 2007 to December 2012, we have investigated the global morphology of stratospheric gravity waves (GWs) with vertical wavelength from 3 to 10 km. In the tropical region, the activities of GWs show clear quasi-biennial oscillation (QBO) structure, and correlate well with the QBO zonal wind with a downward speed of approximately 1 km per month. At the upper stratosphere (above 35 km) in the tropical region, the GWs illustrate clear semi-annual oscillations (SAOs) variation. In the mid- and high- latitudes, the GWs exhibit evident annual variations with maximum value during winter and minimum value during summer. Further, the GWs over the South Pole are linked with polar jet, which indicates the importance of the polar jet in generating the GWs. On the other hand, below 30 km, the GWs are strong over the tropical region and agree with the deep convection region, while, above 30 km, the GWs have some relation with the stratospheric sudden warming (SSW) and night-time polar jet.