Electrodynamics of the equatorial evening ionosphere: 2. Conductivity influences on convection, current, and electrodynamic energy flow
Electrodynamics of the equatorial evening ionosphere: 2. Conductivity influences on convection, current, and electrodynamic energy flow
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赤道傍晚电离层的电动力学：2.电导率对对流、电流和电动能流的影响
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
T. Fang
中科院分区：
文献类型：
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作者：
A. Richmond;T. Fang
我们分析了傍晚赤道等离子体涡旋和垂直漂移的反转前增强（PRE）如何受到与风有关的E和F区域电导率分布的影响，通过与全球电离层-等离子体模型耦合的热层-电离层-电动力学大气环流模型的数值模拟。的夜侧电势满足近似最小化原则，统一的水平和垂直分量的等离子体对流的风和电导率分布的连接。阐明了E区和F区电导率对对流和电流闭合的相对作用。赤道电离异常（EIA）区域附近的纬向风是驱动对流（包括PRE）的主要能量来源。E区通过对与考林流相关的纬向对流的拖曳，帮助调节纬向对流和纬向对流。对于大的夜间E区电导率，纬向对流的额外阻力来自彼得森电导。最小化原理有利于从较低而不是较高的磁峰高度向EIA区域流入等离子体，只要E区域Cowling电导不是太大。这种向上/极向的流入最大化的场线，穿越较低的F层附近的赤道边缘的EIA区域，产生一个PRE与最大的垂直速度内的赤道F层。
We analyze how the evening equatorial plasma vortex and the prereversal enhancement (PRE) of the vertical drift are influenced by the distributions of conductivity in the E and F regions in relation to the wind, through numerical simulations with the thermosphere‐ionosphere‐electrodynamics general circulation model coupled with the global ionosphere‐plasmasphere model. The nightside electric potential satisfies an approximate minimization principle that unifies the connection of the horizontal and vertical components of plasma convection to the wind and conductivity distributions. The relative roles of E and F region conductivities on the convection and current closure are clarified. Evening time F region zonal winds at latitudes that encompass the equatorial ionization anomaly (EIA) region provide the main energy source to drive the convection, including the PRE. The E region helps regulate both the meridional and the zonal convection through drag on the meridional convection associated with Cowling current. For large nighttime E region conductivities, additional drag on the zonal convection comes from the Pedersen conductance. The minimization principle favors meridional plasma inflow to the EIA region from lower rather than higher magnetic apex heights, so long as the E region Cowling conductance is not too large. This upward/poleward inflow maximizes on field lines that traverse the lower F layer near the equatorward edge of the EIA region, producing a PRE with maximum vertical velocity within the equatorial F layer.