Origins of the Thermosphere‐Ionosphere Semiannual Oscillation: Reformulating the |Thermospheric Spoon| Mechanism
By:
Published on 2018 by
Abstract: 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 F 2 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. Key Points: The thermosphere‐ionosphere (T‐I) semiannual oscillation (SAO) naturally arises from orbital geometry The T‐I SAO is sensitive to changes in Earth's obliquity via the thermospheric spoon in TIME‐GCM Dynamically driven oxygen chemistry in the upper mesosphere also affects the T‐I SAO in TIME‐GCM.
This Book was ranked at 41 by Google Books for keyword oscillating.
Book ID of Origins of the Thermosphere‐Ionosphere Semiannual Oscillation: Reformulating the |Thermospheric Spoon| Mechanism's Books is UAaTtgEACAAJ, Book which was written by have ETAG "ty5z7nbSZYo"
Book which was published by since 2018 have ISBNs, ISBN 13 Code is and ISBN 10 Code is
Reading Mode in Text Status is false and Reading Mode in Image Status is false
Book which have " Pages" is Printed at BOOK under Category
This Book was rated by Raters and have average rate at ""
This eBook Maturity (Adult Book) status is NOT_MATURE
Book was written in en
eBook Version Availability Status at PDF is falseand in ePub is false
Book Preview
0 komentar:
Posting Komentar