中间层顶区域大气平均风场年和半年振荡的全球结构

Annual and Semi-Annual Oscillations of Zonal Mean Winds in the Mesopause Region

利用2003~2011年TIDI(TIMED Doppler Interferometer)风场观测数据研究了中间层顶区域80~105 km纬向平均风场年振荡和半年振荡振幅和相位的全球分布结构,并给出了它们的年际变化。在热带地区,纬向风半年振荡最显著。振幅峰值中心位于南半球10°S^20°S范围,出现与平流层半年振荡类似的相对于赤道不对称的分布,并且振幅峰值与以前在该区域的研究结果存在较大差别。在中高纬度地区,纬向风和经向风被年振荡所控制。纬向风在高度100 km以下中高纬度都存在振幅大值中心;经向风年振荡只出现在两半球中纬度高度95 km以下,并且南北半球振幅峰值中心分布不一致。分析结果还显示年振荡和半年振荡振幅存在显著地年际变化,相位的年际变化则较小,但北半球热带地区经向风年振荡振幅和相位表现出2年周期的变化。

In this study the authors analyzed the global structures and inter-annual variations of the annual and semi-annual oscillations of the zonal mean winds in the mesopause region from 80 to 105 km, using nine years （2003-2011） of TIDI （TIMED Doppler Interferometer） observations. In the tropical regions, mean zonal winds dominate the semi-annual oscillation; peak amplitudes occur between 10°S and 20°S, with similar results for the semi-annual oscillation in the stratospheric zonal winds; the amplitudes of the TIDI observations are much smaller than previous results for the mesosphere using other measurement techniques. In the middle and high latitudes, zonal winds and meridional winds are dominated by annual oscillation. The annual oscillation of the zonal winds has two maximum centers in the middle and high latitudes below 100 km. The annual oscillation of the meridional winds is only found at the middle latitudes below 95 km, and the amplitude centers are distributed differently in the Northern and Southern Hemispheres. Results also show that the amplitudes of the annual and semi-annual oscillations in the zonal and meridional winds have significant inter-annual variations with nearly no change in phases. However a two-year period change, both in the amplitude and phase of the annual oscillation of the meridional winds, was found in the northern tropics.