Ion Friction and Quantification of the Geomagnetic Influence on Gravity Wave Propagation and Dissipation in the Thermosphere-Ionosphere: GRAVITY WAVE DAMPING BY ION FRICTION
Ion Friction and Quantification of the Geomagnetic Influence on Gravity Wave Propagation and Dissipation in the Thermosphere-Ionosphere: GRAVITY WAVE DAMPING BY ION FRICTION
复制标题
热层-电离层中重力波传播和耗散的离子摩擦和地磁影响的量化：离子摩擦的重力波阻尼
DOI：
10.1002/2017ja024785
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Hartogh, Paul
中科院分区：
文献类型：
--
作者：
Medvedev, Alexander S.;Yiğit, Erdal;Hartogh, Paul
中性粒子和离子在热层-电离层（TI）中的运动通常不一致，因为存在地磁场和影响等离子体的相关电磁力。离子与重力波（GW）引起的中性粒子运动的碰撞对后者施加阻尼。我们推导出一个实用的公式GW谐波的垂直阻尼率占的几何形状的地磁场和GW的传播方向。该公式可用于从低层大气延伸到中层和热层的大气环流模式的GW效应的参数化。通过TI中的离子-中性相互作用对GW谐波的垂直阻尼取决于地磁场的几何形状，而不是后者的强度。在地磁坐标系中，在赤道方向传播的谐波的离子阻尼在两极上最大，在赤道上减小到零。在纬向传播的波在所有纬度上都受到离子的均匀影响。考虑到各向异性，在F区产生的GW阻力变化超过100 m s-1d-1，冷却/加热速率超过15 K d-1，GW温度扰动方差超过5 K。
Motions of neutrals and ions in the thermosphere‐ionosphere (TI) do not, generally, coincide due to the presence of the geomagnetic field and associated electromagnetic forces affecting plasma. Collisions of ions with gravity wave (GW)‐induced motions of neutrals impose damping on the latter. We derive a practical formula for the vertical damping rate of GW harmonics that accounts for the geometry of the geomagnetic field and the direction of GW propagation. The formula can be used in parameterizations of GW effects developed for general circulation models extending from the lower atmosphere into the mesosphere and thermosphere. Vertical damping of GW harmonics by ion‐neutral interactions in the TI depends on the geometry of the geomagnetic field but not the strength of the latter. The ion damping of harmonics propagating in the meridional direction (in the geomagnetic coordinates) maximizes over the poles and reduces to zero over the equator. Waves propagating in the zonal direction are uniformly affected by ions at all latitudes. Accounting for the anisotropy produces changes in the GW drag in theFregion of more than 100 m s−1d−1, cooling/heating rates of more than 15 K d−1, and in GW temperature variance of disturbances by more than 5 K.