An investigation into the influence of tidal forcing on <i>F</i> region equatorial vertical ion drift using a global ionosphere‐thermosphere model with coupled electrodynamics

Millward, G. H.; Müller‐Wodarg, I. C. F.; Aylward, A. D.; Fuller‐Rowell, T. J.; Richmond, A. D.; Moffett, R. J.

doi:10.1029/2000ja000342

Cited by 176 publications

(176 citation statements)

References 36 publications

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“…Solving for these effects selfconsistently is complex due to the global nature of the electrodynamical coupling (see e.g. Millward et al, 2001). The extent of these effects on Saturn is not known, although, like the Earth, Saturn has a strong equatorial magnetic field.…”

Section: Electrodynamicsmentioning

confidence: 99%

Polar heating in Saturn's thermosphere

et al. 2005

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Abstract.A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983;Festou and Atreya, 1982) and auroral H + 3 temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000). We find that a polar heat source is consistent with both the Smith et al. determination of T ∞ ∼400 K at ∼30 • N and auroral H + 3 temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004). However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T ∞ ∼800 K at ∼4 • N and the auroral H + 3 temperatures simultaneously.

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Section: Electrodynamicsmentioning

confidence: 99%

Polar heating in Saturn's thermosphere

et al. 2005

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“…Because these inputs are based on long-term averages, it is difficult to catch particular temporal and spatial variation of magnetospheric energy input during a geomagnetic storm, thus limiting the predictability of CTIPe. For more details on CTIPe, see Fuller-Rowell et al (1996), Millward et al (1996Millward et al ( , 2001, and Codrescu et al (2012). The best way to understand the role of a physics-based magnetospheric input would be to compare the OpenGGCM-CTIM results with the CTIM results.…”

Section: Openggcm-ctimmentioning

confidence: 99%

Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

Connor

Zesta

Fedrizzi

et al. 2016

J. Space Weather Space Clim.

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The magnetosphere is a major source of energy for the Earth's ionosphere and thermosphere (IT) system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the stormtime dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM) coupled with the Coupled Thermosphere Ionosphere Model (CTIM). OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD) equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe). CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at~400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset, which in turn effectively heats the thermosphere and causes the neutral density increase at 400 km altitude.

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“…[7] Recent modeling of global thermospheric mass density, using thermosphere and ionosphere general circulation models [Roble and Ridley, 1994;Richmond et al, 1992;Millward et al, 2001;Ridley et al, 2006], demonstrates a notable capability to reproduce observed seasonal and annual variation [e.g., Qian et al, 2009;Fedrizzi et al, 2012]. While the climatological variation of the global density is well emulated by models, regional density structures and short-term density variations are not necessarily well represented.…”

Section: Introductionmentioning

confidence: 99%

Thermospheric mass density specification using an ensemble Kalman filter

2013

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[1] This paper presents an application of ensemble Kalman filtering (EnKF) to a general circulation model of the thermosphere and ionosphere. It is designed to incorporate the feedback between plasma and neutral variables in both the analysis and forecast steps of filtering so that thermospheric parameters can be inferred from ionospheric observations and vice versa. We make a case that the global neutral density specification can greatly benefit from this approach based on a number of filtering experiments conducted under the assumption of no model bias. Specific observations considered are (i) neutral mass densities obtained from the accelerometer experiment on board the CHAMP satellite and (ii) electron density profiles obtained from the COSMIC/FORMOSAT-3 mission. Assimilation of the neutral mass density obtained from the CHAMP mission into the TIEGCM is shown to improve the neutral density specification in the vicinity of satellite orbits, but is short of making a global impact unless accompanied by the estimation of the primary driver of the density variability such as solar EUV flux. On the other hand, assimilation of the COSMIC/FORMOSAT-3 electron density profiles into the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) is far more effective than the CHAMP neutral density in terms of improving the global neutral mass density specification. This suggests a synthesis of thermospheric and ionospheric observations into the general circulation model, brought about with the help of the latest EnKF techniques, can effectively increase the geophysical information content of observations.

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An investigation into the influence of tidal forcing on F region equatorial vertical ion drift using a global ionosphere‐thermosphere model with coupled electrodynamics

Cited by 176 publications

References 36 publications

Polar heating in Saturn's thermosphere

Polar heating in Saturn's thermosphere

Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

Thermospheric mass density specification using an ensemble Kalman filter

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