Model of photoelectron impact ionization within the high latitude ionosphere at Mars: Comparison of calculated and measured electron density

Ionization Efficiency in the Dayside Martian Upper Atmosphere

“…No substantial diurnal and solar cycle variations are suggested by the data, except for an insignificant trend of reduced ionization efficiency approaching the terminator. At the top of the atmosphere, the median ionization efficiencies are 0.19±0.03 for CO 2 and 0.27±0.04 for O, respectively, in fair agreement with various model results covering a range of solar irradiance levels from low to high solar activities and a range of solar illumination angles from subsolar to nearterminator (e.g., Fox & Yeager 2006;Haider et al 2006;Nicholson et al 2009). These values are useful for fast calculations of the total ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models.…”

“…These controlling factors include solar EUV/X-ray flux, measured by the Extreme Ultraviolet Monitor (EUVM; Eparvier et al 2015), the neutral atmospheric density, measured by the Neutral Gas and Ion Mass Spectrometer (NGIMS; Mahaffy et al 2015b), as well as the differential electron intensity, measured by the Solar Wind Electron Analyzer (SWEA; Mitchell et al 2016). The above sources of data, publicly available at the MAVEN Science Data Center (https://lasp.colorado.edu/maven/sdc/public/), are utilized in this study to determine the ionization efficiency, which is then compared with existing model results (e.g., Fox & Yeager 2006;Haider et al 2006;Nicholson et al 2009). The present study is complementary to various modeling efforts made to understand the photoelectron energy spectrum observed near Mars (e.g., Sakai et al 2015;Peterson et al 2016), but with a special emphasis on secondary ionization as an important effect of photoelectron production.…”

D, E, and F layers in the daytime at high‐latitude terminator ionosphere of Mars: Comparison with Earth's ionosphere using COSMIC data

“… Bougher et al [2004] did not find a clear trend of electron density with solar zenith angle in the 448 profiles of MGS data set at F region (125–145 km) between solar zenith angles 75° and 87°. Haider et al [2006] using 32 electron density profiles of MGS found that E region (100–112 km) electron densities are independent on solar zenith angles between ∼77° and 82°. Recently Mahajan et al [2007] have analyzed 807 electron density profiles of MGS.…”

“…The values of the first and the second peaks were observed to be ∼8.6 × 10 4 cm −3 and 2.5–4.0 × 10 4 cm −3 , respectively. We have reproduced these ionization peaks as owing to impact of solar EUV (90–1025.7 Å) and X‐ray (10–90 Å) photons, respectively, with the upper atmosphere of Mars [ Haider et al , 2002, 2006]. Ma et al [2004], Ma and Nagy [2007], and Duru et al [2008] have also studied upper ionosphere of Mars using three dimensional models.…”

Longitudinal distribution of thermospheric densities and ionization rates in the upper atmosphere of Mars at mid-latitude using MGS ACC data

“…The MGS accelerometer data have been used for studies of global features and dynamical properties of neutral atmosphere (Bougher et al, , 2004Haider et al, 2006;Keating et al, 1998;Seth et al, 2006a,b;Tolson et al, 2000;Withers et al, 2003;. The analysis of these aerobraking data sets confirms a strong coupling of the lower and upper atmosphere of Mars and the references therein).…”