Meteor‐radar observed mesospheric semi‐annual oscillation (SAO) and quasi‐biennial oscillation (QBO) over Maui, Hawaii
Meteor‐radar observed mesospheric semi‐annual oscillation (SAO) and quasi‐biennial oscillation (QBO) over Maui, Hawaii
复制标题
DOI：
10.1029/2011jd016123
复制
发表时间：
2012-03
影响因子：
--
通讯作者：
Tao Li;A. Liu;Xian Lu;Zhenhua Li;S. Franke;G. Swenson;X. Dou
中科院分区：
文献类型：
--
作者：
Tao Li;A. Liu;Xian Lu;Zhenhua Li;S. Franke;G. Swenson;X. Dou
[1]本文观测了北方副热带中层顶区的半年振荡（SAO）的变化，并讨论了其成因和强迫意义。利用夏威夷毛伊岛伊利诺斯大学流星雷达测量的水平风廓线（20.7°N，156.3°W）和欧洲中期天气预报中心（ECMWF）中期资料的对比分析发现，冬季80-90 km附近的西风明显强于夏季西风，与平流层SAO在1 hPa（150 km）附近是反相的。在10 hPa（130 km）附近，平流层准两年振荡（QBO）的东风位相时，中层SAO的东风位相较强，西风位相时较弱，表明平流层QBO对中层SAO的调制作用。中层QBO在80 km附近的振幅约为5 m/s。它在10 hPa附近与平流层QBO同相，在1 hPa附近与类QBO振荡反相。重力波（GW）和准两日波（QTDW）活动与中间层SAO和QBO的相关性表明，GW的拖曳和QTDW的Eliassen-Palm通量散度可能对中间层SAO的QBO调制有贡献.冬季热带平流层上部东风在QBO西风位相比东风位相向北方亚热带推进更远。这可能会影响中纬度向西传播的GW的向上传播，从而影响北方副热带中层上部的西向GW强迫。
[1] We observed the variations of the semi-annual oscillation (SAO) in the mesopause region of northern subtropics, and we describe its origin and forcing implications. Using the measurements of horizontal wind profiles made by the University of Illinois meteor radar in Maui, Hawaii (20.7°N, 156.3°W) from May 2002 to June 2007 and the European Centre for Medium-Range Weather Forecasts (ECMWF) interim data set, we find that the mesospheric SAO, with the winter westerly near 80–90 km clearly stronger than the summer westerly, is out of phase with the stratospheric SAO near 1 hPa (∼50 km). The mesospheric SAO easterly is strong during the easterly phase and weak during the westerly phase of the stratospheric quasi-biennial oscillation (QBO) near 10 hPa (∼30 km), suggesting the modulation of the mesospheric SAO by the stratospheric QBO. The mesospheric QBO has an amplitude of approximately 5 m/s near 80 km. It is in phase with the stratospheric QBO near 10 hPa and out of phase with the QBO-like oscillation near 1 hPa. The correlation of the gravity wave (GW) and the quasi-two-day wave (QTDW) activities with the mesospheric SAO and QBO suggests that the GW drags and the QTDW Eliassen-Palm flux divergences likely contribute to the QBO modulation of the mesospheric SAO. The winter easterly wind in the tropical upper stratosphere pushes further into the northern subtropics during the QBO westerly phase than during the easterly phase. This may have impacts on the upward propagation of westward-propagating GWs originated from the middle latitudes, and thus the westward GW forcing in the upper mesosphere of northern subtropics.