The Martian thermosphere/ionosphere at high and low solar activities

Fox, Jane L.; Zhou, Peiguang; Bougher, S. W.

doi:10.1016/0273-1177(95)00751-y

Cited by 113 publications

(126 citation statements)

References 29 publications

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“…• SZA compares favorably with that calculated previously (∼1.75 × 10 5 cm −3 ) by Fox et al (1995) for solar maximum conditions. Another test of the reliability of the simulated dayside O/CO 2 mixing ratio is the calculated value of the O • SZA is about half that observed by the Viking RPA (6.0-7.0) at 45…”

Section: Planet-b Moi Conditions: No Dustsupporting

confidence: 81%

“…CO 2 , CO, N 2 , O, Ar, and O 2 densities are plotted. The dayside profiles are not unlike those estimated previously for Mariner 6-7 conditions (see Bougher et al, 1990;Fox et al, 1995). The nightside profiles are pure speculation, since no neutral thermosphere data presently exist to provide a constraint.…”

Section: Planet-b Moi Conditions: No Dustmentioning

confidence: 53%

“…This suggests that our O-mixing ratios are slightly too small for these solar maximum conditions. Larger O-mixing ratios can be obtained by using the improved solar EUV fluxes of Tobiska (1991), especially shortward of 250 A, which will also enhance the magnitude of the electron density at the peak (see Fox et al, 1995). In general, we have confidence that our photochemical ion scheme is realistic near the ionospheric peak region.…”

Section: Planet-b Moi Conditions: No Dustmentioning

confidence: 74%

“…Over the past 10-years, the NCAR terrestrial Thermosphere-Ionosphere General Circulation Model (TIGCM) has been adapted to the unique fundamental parameters, physics, and inputs appropriate to the Mars upper atmosphere (Bougher et al, 1988(Bougher et al, , 1990(Bougher et al, , 1993Fox et al, 1995;Bougher, 1995;Bougher et al, 1997). This Mars Thermospheric General Circulation Model (MTGCM) has been successfully used to address the upper atmospheric structure and dynamics above ∼70 km.…”

Section: Mtgcm Hydrodynamic Modelmentioning

confidence: 99%

“…These assumptions are sufficient for our MT-GCM simulations, since the relevant recombination rates and charge exchange reactions affecting dayside photochemical ions (below 200 km) are only weakly temperature dependent. Most key neutral-ion reactions and rates employed in the MTGCM formulation are identical to those used by Fox (1993) and Fox et al (1995).…”

Section: Mtgcm Input Parameters For October 1999mentioning

confidence: 99%

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The Mars thermosphere-ionosphere: Predictions for the arrival of Planet-B

Bougher

Shinagawa

2014

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Section: Planet-b Moi Conditions: No Dustsupporting

confidence: 81%

Section: Planet-b Moi Conditions: No Dustmentioning

confidence: 53%

Section: Planet-b Moi Conditions: No Dustmentioning

confidence: 74%

Section: Mtgcm Hydrodynamic Modelmentioning

confidence: 99%

Section: Mtgcm Input Parameters For October 1999mentioning

confidence: 99%

See 3 more Smart Citations

The Mars thermosphere-ionosphere: Predictions for the arrival of Planet-B

Bougher

Shinagawa

2014

Earth Planet Sp

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An observational study of the influence of solar zenith angle on properties of the M1 layer of the Mars ionosphere

2015

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Citation:Fallows, K., P. Withers, and M. Matta Here we introduce an automated and repeatable method for determining properties of the M1 and M2 layers simultaneously in 5600 Mars Global Surveyor radio occultation profiles of dayside electron density. The results support previous findings for M1 and M2 subsolar peak densities and the dependence of peak densities on solar zenith angle. The ratio of M1 peak density to M2 peak density remains constant at 0.4 for 70• , in contrast with previous numerical simulations. The M1 altitude increases with solar zenith angle with a lengthscale, L 1 = 2.5 km, which is about half that of the M2 layer, L 2 = 5.2 km, indicating that the two layers become increasingly separated at high solar zenith angles. The vertical width of the M1 layer, H 1 , decreases from 7 km to 5 km as solar zenith angle increases from 70• to 90• , whereas the vertical width of the M2 layer, H 2 , increases from 10 km to 14 km. The prediction of ideal Chapman theory that both the widths H i and the lengthscales L i equal the neutral scale height is not supported by observations. These findings provide meaningful observational constraints for numerical models, which are known to have trouble reproducing observations and observed trends associated with the M1 layer.

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Numerical simulations of the influence of solar zenith angle on properties of the M1 layer of the Mars ionosphere

2015

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The M1 layer of the Mars ionosphere is one of its most significant features, second only to the M2 layer. Observations have shown how the physical properties of this layer depend on solar zenith angle (SZA) and solar irradiance, but these trends have not yet been explored in detail by numerical simulations. Hence, the full implications of the observational findings for the M1 layer's behavior have not been established. Here we use the Boston University Mars Ionosphere Model to simulate the M1 layer over a period of 6 months. In order to adequately reproduce the SZA dependence of the observed M2 peak density, an ad hoc isothermal electron temperature profile was required. This representation was motivated by detailed energy balance calculations that predict relatively small variations in electron temperature at the M2 peak. We find several model results consistent with observations: the simulated M1 peak density is effectively proportional to Ch(SZA) −0.5 , where Ch is the Chapman function; the ratio of M1 to M2 peak electron densities is independent of SZA; the simulated M1 peak altitude decreases with increasing solar irradiance; and the simulated difference in altitude between the M1 and M2 layers increases with SZA at the observed rate. Due to limitations in the assumed neutral atmosphere, the simulated increase in M1 peak altitude with increasing solar zenith angle is significantly greater than observed. In both simulations and observations, limitations in representing the width of the M1 layer prevent meaningful comparisons and connections to the neutral scale height.

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The Martian thermosphere/ionosphere at high and low solar activities

Cited by 113 publications

References 29 publications

The Mars thermosphere-ionosphere: Predictions for the arrival of Planet-B

The Mars thermosphere-ionosphere: Predictions for the arrival of Planet-B

An observational study of the influence of solar zenith angle on properties of the M1 layer of the Mars ionosphere

Numerical simulations of the influence of solar zenith angle on properties of the M1 layer of the Mars ionosphere

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