Long-term variability in the mesosphere and lower thermosphere and its relation with the lower atmsophere

中层和低层热层的长期变化及其与低层大气的关系

基本信息

批准号：
15540420
负责人：
MIYOSHI Yasunobu
金额：
$ 1.47万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540420/
关键词：
atmospheric coupling process below and above long-term variability general circulation general circulation model atmospheric tides Kelvin wave 惑星波大気重力波大気の長周期振動

项目摘要

A new general circulation model (GCM) which contains the region from the ground surface to the exobase has been developed, and used to investigate behavior of the migrating diurnal tide for equinox condition. We studied day-to-day variations of migrating diurnal and semidiurnal tides in the mesosphere and thermosphere and their relation with migrating diurnal tides generated in the lower atmosphere. For example, fluctuations of the migrating diurnal amplitude with periods of 17-18 and 25 days are found in the height range from 20 to 300 km, indicating dynamical coupling between the mesosphere and thermosphere and the lower atmosphere.By using the GCM, excitation mechanism of intraseasonal oscillation of the zonal mean zonal wind in the equatorial mesosphere and lower thermosphere (MLT) were investigated. Wave-mean flow interaction with ultra fast Kelvin waves and diurnal tides is important for driving the intraseasonal oscillation. Not only the migrating diurnal tide but also the non-migrating diurnal tide plays an important role in excitation of the intraseasonal oscillation. Intraseasonal variations of amplitudes of the ultra fast Kelvin waves and the diurnal tides are found at height range from 20 to 90 km heights. Intraseasonal variations of amplitudes of these waves are closely related with variations of the moist convective activity.Interannual variation of the semiannual oscillation in the equatorial MLT was investigated. Upward propagating gravity waves in the MLT are modulated by interannual variation of the zonal wind in the lower stratosphere associated with the Quasi-Biennial Oscillation. This QBO modulated gravity wave activity in the MLT produces interannual variation of the semiannual oscillation.

已经开发了一种新的一般循环模型（GCM），该模型包含从地面到exobase的区域，并用于研究equinox条件的迁移昼夜潮汐的行为。我们研究了中层和热层中昼夜潮汐和半潮期潮汐的日常变化，以及它们与下层大气中产生的昼夜潮汐的关系。例如，在20到300 km的高度范围内发现，迁移的昼夜幅度的波动在17-18和25天之间，表明中层和热层之间的动态耦合以及较低的大气层和较低的大气。通过GCM，使用GCM，激励机制，较低的骨骼振荡机制较低的骨骼平均值和均等型均等型均等型均等型均匀的菌株。调查。与超快速开尔文波和昼夜潮汐的波平均流相互作用对于驱动季节内振荡很重要。不仅迁移的昼夜潮流，而且非迁移的昼夜潮汐在激发季节内振荡中起着重要作用。超快速开尔文波和昼夜潮汐幅度振幅的季节内变化在20到90 km的高度范围为20至90公里。这些波的振幅的季节内变化与潮湿的对流活动的变化密切相关。研究了赤道MLT中半年度振荡的年龄差异变化。 MLT中的向上传播重力波通过与准双年生振荡相关的下层平流层中的纬向风变化来调节。 MLT中的QBO调节重力波活性会产生半年度振荡的年度变化。