Solar cycle effects on the ion escape from Mars

Abstract

Solar cycle effects on the escape of planetary ions from Mars are investigated using Mars Express Analyzer of Space Plasmas and Energetic Atoms 3 data from June 2007 to January 2013. Average and median tail fluxes of low‐energy (<300 eV) heavy ions (O+, O2+), derived from the full data set covering 7900 orbits, are highly correlated with the solar activity proxies F10.7 and the sunspot number, Ri. The average heavy ion escape rate increased by a factor of ≈ 10, from ≈ 1 · 1024 s−1 (solar minimum) to ≈ 1 · 1025 s−1 (solar maximum). Combining data from this, and other studies, an empiric model/expression is derived for the Martian escape rate versus solar activity F10.7 and Ri. The model is a useful tool to derive the accumulated ion escape rate from Mars based on historical records of solar activity, with potentials back to the young Sun époque.

Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

“…Our calculated total ion escape rate for SOLARMIN conditions is ∼2 ×10 24 s −1 , in reasonable agreement with the MEX data as shown in Figure 4 in Lundin et al [2013]. For SOLARMAX conditions, the calculated result is 7.06 ×10 24 s −1 , which is also reasonably consistent with the ion escape rate estimate from MEX data, ∼1 ×10 25 s −1 [Lundin et al, 2013]. The increasing trend of the ion escape rate with solar activity is somewhat different from that reported by Lundin et al [2013] (a factor of ∼10).…”

“…In other words, different solar cycles can affect the ion escape rate by a factor of ∼3.3 based on our simulations. Our calculated total ion escape rate for SOLARMIN conditions is ∼2 ×10 24 s −1 , in reasonable agreement with the MEX data as shown in Figure 4 in Lundin et al [2013]. For SOLARMAX conditions, the calculated result is 7.06 ×10 24 s −1 , which is also reasonably consistent with the ion escape rate estimate from MEX data, ∼1 ×10 25 s −1 [Lundin et al, 2013].…”

“…For SOLARMAX conditions, the calculated result is 7.06 ×10 24 s −1 , which is also reasonably consistent with the ion escape rate estimate from MEX data, ∼1 ×10 25 s −1 [Lundin et al, 2013]. The increasing trend of the ion escape rate with solar activity is somewhat different from that reported by Lundin et al [2013] (a factor of ∼10). One possible explanation is that we did not include the neutral wind in our simulations, which can greatly affect the ion loss [Brecht and Ledvina, 2014b].…”

“…Recently, the study of the solar wind interaction with Mars upper atmosphere/ionosphere has received a great deal of attention, especially the investigation of ion escape rates due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. A number of papers reporting on the measurement of ion escape rates by the ASPERA-3 instrument on the Mars Express spacecraft have also been published [e.g., Barabash et al, 2007;Lundin et al, 2008Lundin et al, , 2009Lundin et al, , 2013Nilsson et al, 2011]. In Lundin et al [2013], they reported that the average heavy ion escape rate is increased by a factor of ∼10, from ∼1 ×10 24 s −1 (solar minimum) to ∼1 ×10 25 s −1 (solar maximum).…”

“…A number of papers reporting on the measurement of ion escape rates by the ASPERA-3 instrument on the Mars Express spacecraft have also been published [e.g., Barabash et al, 2007;Lundin et al, 2008Lundin et al, , 2009Lundin et al, , 2013Nilsson et al, 2011]. In Lundin et al [2013], they reported that the average heavy ion escape rate is increased by a factor of ∼10, from ∼1 ×10 24 s −1 (solar minimum) to ∼1 ×10 25 s −1 (solar maximum). On the other hand, both Verigin et al [1991] (by Phobos-2 observations) and Nilsson et al [2011] suggested that high solar activity leads to ∼2.5 times higher ion escape rate than the low solar activity result.…”