Variability of the Martian thermosphere during eight Martian years as simulated by a ground‐to‐exosphere global circulation model. Issue 11 (27th November 2015)

• Record Type: Journal Article
• Authors: González‐Galindo, F.; López‐Valverde, M. A.; Forget, F.; García‐Comas, M.; Millour, E.; Montabone, L.
• Is Part Of: Journal of geophysical research. Volume 120:Issue 11(2015:Nov.)
• Page Start: 2020
• Page End: 2035
• Publication Date: 2015-11-27
• Subjects: Mars -- exobase -- temperatures -- variability -- GCM; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1002/2015JE004925
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: Using a ground‐to‐exosphere general circulation model for Mars we have simulated the variability of the dayside temperatures at the exobase during eight Martian years (MY, from MY24 to MY31, approximately from 1998 to 2013), taking into account the observed day‐to‐day solar and dust load variability. We show that the simulated temperatures are in good agreement with the exospheric temperatures derived from Precise Orbit Determination of Mars Global Surveyor. We then study the effects of the solar variability and of two planetary‐encircling dust storms on the simulated temperatures. The seasonal effect produced by the large eccentricity of the Martian orbit translates in an aphelion‐to‐perihelion temperature contrast in every simulated year. However, the magnitude of this seasonal temperature variation is strongly affected by the solar conditions, ranging from 50 K for years corresponding to solar minimum conditions to almost 140 K during the last solar maximum. The 27 day solar rotation cycle is observed on the simulated temperatures at the exobase, with average amplitude of the temperature oscillation of 2.6 K but with a significant interannual variability. These two results highlight the importance of taking into account the solar variability when simulating the Martian upper atmosphere and likely have important implications concerning the atmospheric escape rate. We also show that the global dust storms in MY25 and MY28 have a significant effect on the simulated temperatures. In general, they increase the exospheric temperatures over the low latitude and midlatitude regions and decrease them in the polar regions. Key Points: Eight Martian years simulated with global model including day‐to‐day variable solar flux and dust Important effect of solar cycle and solar rotation on simulated exobase temperatures Significant effects of planetary‐encircling dust storms on simulated exobase temperatures