Ionospheric Electrodynamics Modeling

Richmond, A. D.; Maute, Astrid

doi:10.1002/9781118704417.ch6

Cited by 75 publications

(74 citation statements)

References 80 publications

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“…Specifically, X-ray, extreme ultraviolet (EUV), and far ultraviolet solar fluxes are parameterized following Solomon and Qian (2005), which are then scaled by the EUVAC model (Richards et al, 1994) that relies upon the F10.7 solar index and its 81-day average. The reader is referred to Roble et al (1988), Richmond et al (1992), Qian (2014), and Richmond and Maute (2014), and references therein for the historical and recent developments of the TIE-GCM. The reader is referred to Roble et al (1988), Richmond et al (1992), Qian (2014), and Richmond and Maute (2014), and references therein for the historical and recent developments of the TIE-GCM.…”

Section: Tie-gcm Simulations and Methodologymentioning

confidence: 99%

The Effects of Vertically Propagating Tides on the Mean Dynamical Structure of the Lower Thermosphere

2019

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Numerical experiments performed with the National Center for Atmospheric Research thermosphere‐ionosphere‐electrodynamics general circulation model forced with an observationally based diurnal and semidiurnal tidal spectrum are utilized to investigate the physical processes by which the dissipation of vertically propagating tides act to alter the zonally and diurnally averaged (“zonal‐mean”) dynamical state of the thermosphere. Below 150 km the largest contributors to the zonal‐mean zonal wind distribution are the pressure gradient, Coriolis, and the tidally driven momentum flux divergence terms, the latter being about half the former two. Ion drag plays a smaller role in the lower thermosphere but becomes increasingly important at higher altitudes (i.e., above ∼150 km). We also find that the tidally driven heat flux divergence term contributes to the generation of zonal‐mean zonal winds through its coupling into the pressure gradient term. Tidally induced zonally and diurnally averaged zonal wind changes achieve values of up to 30 m/s in the lower thermosphere, of which about a third can be traced to the heat flux divergence. Tidal amplitudes used to force the thermosphere‐ionosphere‐electrodynamics general circulation model lower boundary represent conservative estimates, since they are based on forcing by a multiyear 60‐day mean tidal climatology, which significantly underestimates their amplitudes at any given time. Eliassen‐Palm Fluxes further support the conclusion that the heat flux divergence has a statistically significant direct impact on the zonal‐mean zonal wind balance in the lower thermosphere.

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Section: Tie-gcm Simulations and Methodologymentioning

confidence: 99%

The Effects of Vertically Propagating Tides on the Mean Dynamical Structure of the Lower Thermosphere

2019

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“…The upper boundary ranges from 400 to 700 km, depending on solar activity. The electrodynamics are calculated as described by Richmond and Maute [] in a Modified Magnetic Apex coordinate system [ Richmond , ] with a reference height of 90 km. Magnetic longitude and latitude are constant along geomagnetic field lines.…”

Section: Modelmentioning

confidence: 99%

“…Above 350 km, the electron temperature is extrapolated along field lines based on the temperature and vertical gradient at 350 km, as described by Titheridge []. The nighttime ionization rates are spatially uniform, as given by Richmond and Maute [] for the TIEGCM. Although the lifetimes of molecular ions are sufficiently long at night that transport may become important [ Haerendel et al , ], this transport is neglected.…”

Section: Modelmentioning

confidence: 99%

Electrodynamics of the equatorial evening ionosphere: 1. Importance of winds in different regions

2015

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The importance of winds at different altitudes and latitudes for the electrodynamics of the low-latitude evening ionosphere is examined with a model of the global coupled ionosphere-thermosphere system. The model reproduces the main observed features of the evening equatorial plasma vortex and the prereversal enhancement (PRE) of the vertical drift. The electrodynamics is driven primarily by the zonal wind forced by the diurnally varying zonal pressure-gradient force. The zonal wind lags the zonal pressure-gradient force owing to inertia. When ion drag is important, the time lag of the wind behind the pressure gradient force is shortened, and the high-altitude evening wind turns eastward earlier than the wind at lower altitudes, where ion drag is less important. Therefore, a vertical shear of the zonal wind tends to develop at altitudes around the transition between small and large ion drag at the bottom of the F region. This wind shear is closely associated with the vertical shear in the zonal convection velocity that is part of the evening plasma vortex. Unlike previous studies, we find that the winds driving the PRE lie mainly on field lines with apexes above the peak of the equatorial F layer, field lines that extend in magnetic latitude out to nearly 30• and encompass the entire evening equatorial ionization anomaly region. Contrary to previous suggestions, the westward convection in the bottomside of the evening plasma vortex is found to weaken, rather than strengthen, the PRE. Daytime winds have relatively little influence on the low-latitude evening electrodynamics.

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“…Subgrid‐scale gravity waves are parameterized with a modified Lindzen []‐type scheme that is extended to include molecular damping effects in the lower thermosphere. A more complete description of the TIME‐GCM can be found in Roble and Ridley [] and Roble [, ] with the electrodynamics described by Richmond and Maute [].…”

Section: Time‐gcmmentioning

confidence: 99%

Upper thermospheric responses to forcing from above and below during 1–10 April 2010: Results from an ensemble of numerical simulations

Hagan

Häusler

et al. 2015

JGR Space Physics

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In this report we examine the spatial and temporal variability of the quiescent thermosphere leading up to and after the 5 April 2010 geomagnetic disturbance. We attribute the dominant driver of this variability to a combination of tides generated in situ and in the troposphere, stratosphere, and mesosphere. We identify nonmigrating tidal signatures attributable to the latter source that are ubiquitous, persistent, and significant at all thermospheric latitudes. Further, these perturbations underlie the upper atmospheric response to solar geomagnetic disturbances and are measurably altered, along with their migrating counterparts, during the storm. Our investigation is centered on a series of National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model simulations during 1-10 April 2010, including an optimal simulation with lower boundary forcing based on Modern-Era Retrospective Analysis for Research and Application reanalysis data and upper boundary forcing based on satellite and ground magnetometer measurements and the Assimilative Mapping of Ionospheric Electrodynamics procedure and three diagnostic simulations. The differences between the optimal and diagnostic simulations allow us to quantify thermospheric variability attributable to solar geomagnetic forcing and dynamical effects propagating into the thermosphere from below. We find that they can be comparable at high latitudes for some nonmigrating tidal components.

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Ionospheric Electrodynamics Modeling

Cited by 75 publications

References 80 publications

The Effects of Vertically Propagating Tides on the Mean Dynamical Structure of the Lower Thermosphere

The Effects of Vertically Propagating Tides on the Mean Dynamical Structure of the Lower Thermosphere

Electrodynamics of the equatorial evening ionosphere: 1. Importance of winds in different regions

Upper thermospheric responses to forcing from above and below during 1–10 April 2010: Results from an ensemble of numerical simulations

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