Sub-solar electron temperatures in the lower Martian ionosphere Journal Article uri icon

Overview

abstract

  • Martian sub-solar electron temperatures obtained below 250 km are; examined using data obtained by instruments on the Mars Atmosphere; Evolution Mission (MAVEN) during the three sub-solar deep dip campaigns; and a one-dimensional fluid model. This analysis was done because of the; uncertainty in MAVEN low electron temperature observations at low; altitudes and the fact that the Level 2 temperatures reported from the; MAVEN Langmuir Probe and Waves (LPW) instrument are more than 400 Kelvin; above the neutral temperatures at the lowest altitudes sampled; (~120 km). These electron temperatures are well above; those expected before MAVEN was launched. We find that an empirical; normalization parameter, neutral pressure divided by local electron; heating rate, organized the electron temperature data and identified a; similar altitude (~160 km) and time scale; (~2,000 s) for all three deep dips. We show that MAVEN; data are not consistent with a plasma characterized by electrons in; thermal equilibrium with the neutral population at 100 km. Because of; the lack data below 120 km and the uncertainties of the data and the; cross sections used in the one dimensional fluid model above 120 km, we; cannot use MAVEN observations to prove that the electron temperature; converges to the neutral temperature below 100 km. However, the lack of; our understanding the electron temperature altitude profile below 120 km; does not impact our understanding of the role of electron temperature in; determining ion escape rates because ion escape is determined by; electron temperatures above 180 km.

publication date

  • November 4, 2019

has restriction

  • hybrid

Date in CU Experts

  • May 27, 2021 7:27 AM

Full Author List

  • Peterson WK; Andersson L; Ergun RE; Thiemann EMB; Pilinski MD; Thaller SA; Fowler CM; Mitchell DL; Benna M; Yelle R

author count

  • 11

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