Total electron content in the Martian atmosphere: A critical assessment of the Mars Express MARSIS data sets

Journal
Date Issued
2015
Author(s)
Sánchez-Cano, B.
•
Morgan, D. D.
•
Witasse, O.
•
Radicella, S. M.
•
Herraiz, M.
•
•
•
•
•
Kofman, W.
•
Grima, C.
•
Mouginot, J.
•
Gurnett, D. A.
•
Lester, M.
•
Blelly, P. -L.
•
Opgenoorth, H.
•
Quinsac, G.
DOI
Description
Acknowledgments B.S.‐C. and M.L. acknowledge support through STFC grant ST/K001000/1. Also, B.S.‐C. acknowledges the Spanish project AYA2011‐29967‐C05‐02, the Complutense Predoctoral Fellowship that she had until 17 June 2014 and two scientific stays at ESTEC of the European Space Agency by ESTEC Faculty support funding. D.M. was supported at The University of Iowa under contract 1224107 with the Jet Propulsion Laboratory. The Mars Express MARSIS AIS raw data and the first years of MARSIS subsurface data [ Mouginot et al. , ] were downloaded from the European Space Agency Planetary Science Archive ( http://www.rssd.esa.int/psa ). The rest of MARSIS subsurface data can be requested either to the authors of this manuscript or to the authors of Mouginot et al. [ ] and Cartacci et al . [2013]. The NeMars data are the results of the empirical model described at Sánchez‐Cano et al. [ ]. All data will be available on request to the author ( bscmdr1@leicester.ac.uk ). The authors thank the Mars Upper Atmosphere Network (MUAN) led by H. Opgenoorth for fruitful discussions at their semiannual meetings. Michael Liemohn thanks the reviewers for their assistance in evaluating this paper.
Abstract
The total electron content (TEC) is one of the most useful parameters to evaluate the behavior of the Martian ionosphere because it contains information on the total amount of free electrons, the main component of the Martian ionospheric plasma. The Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) radar is able to derive TEC from both of its operation modes: (1) the active ionospheric sounding (AIS) mode and (2) the subsurface mode. TEC estimates from the subsurface sounding mode can be computed from the same raw data independently using different algorithms, which should yield similar results. Significant differences on the dayside, however, have been found from two of the algorithms. Moreover, both algorithms seem also to disagree with the TEC results from the AIS mode. This paper gives a critical, quantitative, and independent assessment of these discrepancies and indicates the possible uncertainty of these databases. In addition, a comparison between the results given by the empirical model of the Martian ionosphere developed by Sánchez-Cano et al. (2013) and the different data sets has been performed. The main result is that for solar zenith angles higher than 75°, where the maximum plasma frequency is typically small compared with the radar frequencies, the two subsurface algorithms can be confidently used. For solar zenith angles less than 75°, where the maximum plasma frequency is very close to the radar frequencies, both algorithms suffer limitations. Nevertheless, despite the solar zenith angle restrictions, the dayside TEC of one of the two algorithms is consistent with the modeled TEC.
Volume
120
Issue
3
Start page
2166
Uri
Url
Issn Identifier
2169-9380
Ads BibCode
2015JGRA..120.2166S
Rights
open.access
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