Universität zu Köln

Paetzold, M., Bird, M. K., Haeusler, B., Peter, K., Tellmann, S. and Tyler, G. L. (2016). Comment on the paper Mars Express radio occultation data: A novel analysis approach by Grandin et al. (2014). J. Geophys. Res-Space Phys., 121 (10). S. 10578 - 10592. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9402

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Abstract

In their recent paper, Grandin et al. (2014) claim to have developed a novel approach, principally a ray tracing method, to analyze radio sounding data from occulted spacecraft signals by planetary atmospheres without the usual assumptions of the radio occultation inversion method of a stratified, layered, symmetric atmosphere. They apply their new approach to observations of the Mars Express Radio Science (MaRS) experiment and compare their resulting temperature, neutral number density, and electron density profiles with those from MaRS, claiming that there is good agreement with the observations. The fact is, however, that there are serious disagreements in the most important altitude ranges. Their temperature profile shows a 30 K shift or a 300 sigma (1 sigma standard deviation = 0.1 K for the MaRS profile near the surface) difference toward warmer temperatures at the surface when compared with MaRS, while the MaRS profile is in best agreement with the profile from the Mars Climate Data Base V5.0 (MCD V5.0). Their full temperature profile from the surface to 250 km altitude deviates significantly from the MCD V5.0 profile. Their ionospheric electron density profile is considerably different from that derived from the MaRs observations. Although Grandin et al. (2014) claim to derive the neutral number density and temperature profiles above 200 km, including the asymptotic exosphere temperature, it is simply not possible to derive this information from what is essentially noise.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Paetzold, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bird, M. K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Peter, K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tellmann, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tyler, G. L. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-259238
DOI:	10.1002/2015JA021955
Journal or Publication Title:	J. Geophys. Res-Space Phys.
Volume:	121
Number:	10
Page Range:	S. 10578 - 10592
Date:	2016
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9402
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SCIENCE EXPERIMENT; ATMOSPHERE; VENUS; IONOSPHERE; UNCERTAINTIES; MARINER-10; MODEL; MASS Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/25923