DOI: 10.1002/2017JA024861
Scopus记录号: 2-s2.0-85041064874
论文题名: Origins of the Thermosphere-Ionosphere Semiannual Oscillation: Reformulating the “Thermospheric Spoon” Mechanism
作者: Jones M. ; Jr. ; Emmert J.T. ; Drob D.P. ; Picone J.M. ; Meier R.R.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 1 起始页码: 931
结束页码: 954
语种: 英语
英文关键词: atmospheric tides
; gravity waves
; semiannual oscillation
; thermosphere-ionosphere
; thermospheric spoon mechanism
; thermospheric transport
英文摘要: We demonstrate how Earth's obliquity generates the global thermosphere-ionosphere (T-I) semiannual oscillation (SAO) in mass density and electron density primarily through seasonally varying large-scale advection of neutral thermospheric constituents, sometimes referred to as the “thermospheric spoon” mechanism (TSM). The National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) is used to isolate the TSM forcing of this prominent intraannual variation (IAV) and to elucidate the contributions of other processes to the T-I SAO. An ∼30% SAO in globally averaged mass density (relative to its global annual average) at 400 km is reproduced in the TIME-GCM in the absence of seasonally varying eddy diffusion, tropospheric tidal forcing, and gravity wave breaking. Artificially, decreasing the tilt of Earth's rotation axis with respect to the ecliptic plane to 11.75° reduces seasonal variations in insolation and weakens interhemispheric pressure differences at the solstices, thereby damping the global-scale, interhemispheric transport of atomic oxygen (O) and molecular nitrogen in the thermosphere and reducing the simulated global mass density SAO amplitude to ∼10%. Simulated T-I IAVs in mass density and electron density have equinoctial maxima at all latitudes near the F2 region peak; this phasing and its latitude dependence agree well with empirically inferred climatologies. When tropospheric tides and gravity waves are included, simulated IAV amplitudes and their latitudinal dependence also agree well with empirically inferred climatologies. Simulated meridional and vertical transport of O due to the TSM couples to the upper mesospheric circulation, which also contributes to the T-I SAO through O chemistry. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114802
Appears in Collections: 气候减缓与适应
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作者单位: Space Science Division, U.S. Naval Research Laboratory, Washington, DC, United States; Voluntary Emeritus Program, U.S. Naval Research Laboratory, Washington, DC, United States; Department of Physics and Astronomy, George Mason University, Fairfax, VA, United States
Recommended Citation:
Jones M.,Jr.,Emmert J.T.,et al. Origins of the Thermosphere-Ionosphere Semiannual Oscillation: Reformulating the “Thermospheric Spoon” Mechanism[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(1)