An observational study of the response of the upper atmosphere of Mars to lower atmospheric dust storms

Abstract

Solar cycle variations in solar radiation create notable changes in the Martian ionosphere, which have been analysed with Mars Express plasma datasets in this paper. In general, lower densities and temperatures of the ionosphere are found during the low solar activity phase, while higher densities and temperatures are found during the high solar activity phase. In this paper, we assess the degree of influence of the long term solar flux variations in the ionosphere of Mars. Key words: solar cycle; ionosphere of Mars; TEC. Variaciones de la ionosfera de Marte debidas al ciclo solarResumen La radiación solar en cada fase del ciclo solar crea importantes variaciones en la ionosfera de Marte, las cuales son analizadas en este artículo con datos de la sonda Mars Express. En general, las densidades y temperaturas más bajas de la ionosfera se encuentran durante la fase de baja actividad solar, mientras que las densidades y temperaturas más elevadas se encuentran durante la fase de alta actividad solar. Este artículo evalúa el efecto que las variaciones del flujo solar tienen a largo plazo en la ionosfera. Palabras clave: ciclo solar; ionosfera de Marte; TEC.

Recovery and validation of Mars ionospheric electron density profiles from Mariner 9

“…This unusual behavior was immediately noted by the early investigators, who attributed it to the subsidence of the neutral atmosphere during the waning phase of a tremendous dust storm McElroy 1977). The steady descent of the ionospheric peak during the primary mission of Mariner 9 becomes noticeably clearer when peak altitudes are updated from being referenced to the Mariner-era areoid (Kliore et al 1972b) to being referenced to the MOLA areoid (Withers and Pratt 2013). Withers and Pratt (2013) showed how peak altitude dropped steadily from 150 to 140 km from orbit 1 to 79.…”

“…The steady descent of the ionospheric peak during the primary mission of Mariner 9 becomes noticeably clearer when peak altitudes are updated from being referenced to the Mariner-era areoid (Kliore et al 1972b) to being referenced to the MOLA areoid (Withers and Pratt 2013). Withers and Pratt (2013) showed how peak altitude dropped steadily from 150 to 140 km from orbit 1 to 79. This cannot be attributed to solar zenith angle effects.…”

“…Even larger densities likely occurred at earlier times during this remarkable storm". The ionospheric peak has also been observed to change during other dust events (e.g., Bougher et al 2001;Wang and Nielsen 2003;Withers and Pratt 2013). However, the effects of a dust storm on the topside ionosphere have not been addressed previously.…”

“…They have found, with the support of additional datasets, that the altitude of the peak electron density increases with increasing solar zenith angle (Hantsch and Bauer 1990;Luhmann and Brace 1991;Shinagawa 1996;Stewart and Hanson 1982;Zhang et al 1990). They have discovered that the ionospheric peak altitude is elevated significantly during dust storms (Hantsch and Bauer 1990;Kliore et al 1973;Luhmann and Brace 1991;Shinagawa 1996;Stewart and Hanson 1982;Wang and Nielsen 2003;Withers and Pratt 2013;Zhang et al 1990). …”

Variaciones de la ionosfera de Marte debidas al ciclo solar

“…Moreover, the planet is also a major source of variability in the ionosphere, as dust storms, thermal atmospheric tides, crustal magnetic fields, or the topography itself modulate the behaviour of the ionosphere (e.g. Shinagawa and Cravens, 1989;Witasse, 2000;Withers et al, 2003;Morel et al, 2004;Wang and Nielsen, 2004;Mendillo et al, 2006;Nĕmec et al, 2011;Zou et al, 2011;Withers et al, 2012a, b;González-Galindo et al, 2013;Withers and Pratt, 2013;Bougher et al, 2015;Matta et al, 2015;Sánchez-Cano et al, 2015b. However, the solar cycle is the factor that plays the most important long-term role in ionospheric variability, as each solar cycle phase produces changes in the neutral atmosphere, in the ionospheric temperatures and in the densities.…”