Tropical stratospheric circulation deduced from satellite aerosol data
Tropical stratospheric circulation deduced from satellite aerosol data
复制标题
根据卫星气溶胶数据推导出的热带平流层环流
作者：
C. Trepte;M. Hitchman
大型热带火山喷发的火山物质扩散情况为了解平流层下层的环流提供了线索。在此，我们根据1979 - 1981年以及1984 - 1991年期间获取的气溶胶层卫星观测的纬向平均剖面图来推断平流层的运动。通过研究热带火山喷发后的气溶胶分布，我们发现向极传输在对流层顶上方几公里的高度很容易发生，而在21 - 28公里的高度范围内，气溶胶往往停留在赤道20°以内。我们进一步推断，在这一高层区域的气溶胶分布受准两年振荡的相位控制。当存在东风切变时，气溶胶在赤道上方上升，而当存在西风切变时，相对于平流层平均环流在赤道上方出现下沉。根据气溶胶分布情况，我们认为热带平流层可被视为通过热带对流层顶进入平流层的微量成分的一个临时储存库。
THE dispersal of volcanic material from large tropical eruptions provides insight into the circulation of the lower stratosphere. Here we infer stratospheric motions from zonal mean cross-sections of satellite observations of the aerosol layer taken during 1979–81 and 1984–91. By examining the aerosol distribution following volcanic eruptions in the tropics, we find that poleward transport occurs readily at altitudes within a few kilometres above the tropopause, whereas in the altitude range of 21–28 km, aerosols tend to remain within 20° of the Equator. We further deduce that the aerosol distribution in this upper regime is controlled by the phase of the quasibiennial oscillation. When the easterly shear is present, aerosols are lofted over the Equator, whereas when the westerly shear is present, descent relative to the mean stratospheric circulation occurs over the Equator. From the aerosol distributions, we suggest that the tropical stratosphere may be regarded as a temporary reservoir for trace constituents entering the stratosphere through the tropical tropopause.