Universität zu Köln

Peter, Kerstin, Paetzold, Martin, Molina-Cuberos, Gregorio ORCID: 0000-0002-5664-7028, Witasse, Olivier, Gonzalez-Galindo, F., Withers, Paul, Bird, Michael K., Haeusler, Bernd, Hinson, David P., Tellmann, Silvia and Tyler, G. Leonard (2014). The dayside ionospheres of Mars and Venus: Comparing a one-dimensional photochemical model with MaRS (Mart Express) and VeRa (Venus Express) observations. Icarus, 233. S. 66 - 83. SAN DIEGO: ACADEMIC PRESS INC ELSEVIER SCIENCE. ISSN 1090-2643

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Abstract

The electron density distributions of the lower ionospheres of Mars and Venus are mainly dependent on the solar X-ray and EUV flux and the solar zenith angle. The influence of an increasing solar flux is clearly seen in the increase of the observed peak electron density and total electron content (TEC) of the main ionospheric layers. The model Ionization in Atmospheres (IonA) was developed to compare ionospheric radio sounding observations, which were performed with the radio science experiments MaRS on Mars Express and VeRa on Venus Express, with simulated electron density profiles of the Mars and Venus ionospheres. This was done for actual observation conditions (solar flux, solar zenith angle, planetary coordinates) from the bases of the ionospheres to 160 km altitude. IonA uses models of the neutral atmospheres at ionospheric altitudes (Mars Climate Database (MCD) v4.3 for Mars; VenusGRAM/VIRA for Venus) and solar flux information in the 0.5-95 nm wavelength range (X-ray to EUV) from the SOLAR2000 data base. The comparison between the observed electron density profiles and the IonA profiles for Mars, simulated for a selected MCD scenario (background atmosphere), shows that the general behavior of the Mars ionosphere is reproduced by all scenarios. The MCD low solar flux/clear atmosphere and low solar flux/MY24 scenarios agree best (on average) with the MaRS set of observations, although the actual Mars atmosphere seemed to be still slightly colder at ionospheric altitudes. For Venus, the VenusGRAM model, based on VIRA, is too limited to be used for the IonA simulation of electron density profiles. The behavior of the V2 peak electron density and TEC as a function of solar zenith angle are in general reproduced, but the peak densities and the TEC are either over- or underestimated for low or high solar EUV fluxes, respectively. The simulated V2 peak altitudes are systematically underestimated by 5 km on average for solar zenith angles less than 45 and the peak altitudes rise for zenith angles larger than 60. The latter is the opposite of the observed behavior. The explanation is that VIRA and VenusGRAM are valid only for high solar activity, although there is also very poor agreement with VeRa observations from the recent solar cycle, in which the solar activity increases to high values. The disagreement between the observation and simulation of the Venus electron density profiles proves, that the true encountered Venus atmosphere at ionospheric altitudes was denser but locally cooler than predicted by VIRA. (C) 2014 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Peter, Kerstin UNSPECIFIED UNSPECIFIED UNSPECIFIED Paetzold, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Molina-Cuberos, Gregorio UNSPECIFIED orcid.org/0000-0002-5664-7028 UNSPECIFIED Witasse, Olivier UNSPECIFIED UNSPECIFIED UNSPECIFIED Gonzalez-Galindo, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Withers, Paul UNSPECIFIED UNSPECIFIED UNSPECIFIED Bird, Michael K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Hinson, David P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tellmann, Silvia UNSPECIFIED UNSPECIFIED UNSPECIFIED Tyler, G. Leonard UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-439713
DOI:	10.1016/j.icarus.2014.01.028
Journal or Publication Title:	Icarus
Volume:	233
Page Range:	S. 66 - 83
Date:	2014
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Place of Publication:	SAN DIEGO
ISSN:	1090-2643
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language UPPER-ATMOSPHERE; SOLAR-CYCLE; ELECTRON-TEMPERATURE; NEUTRAL ATMOSPHERE; PEAK; FIELD; IONS Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/43971