Dayside Electron Density Depletions Observed by the MAVEN Langmuir Probe and Waves Instrument

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Tristan David Weber1, Laila Andersson1, Robert Ergun2, Christopher M Fowler3, Adam K Woodson3, Michiko W Morooka4, Anders I Eriksson5, Gregory T Delory6, James P McFadden7, Jasper S Halekas8, David L Mitchell7 and John E P Connerney9, (1)University of Colorado at Boulder, Boulder, CO, United States, (2)Univ Colorado, Boulder, CO, United States, (3)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (4)University of Colorado, Laboratory for Atmospheric and Space Research, Boulder, CO, United States, (5)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (6)University of California, Space Sciences Laboratory, Berkeley, CA, United States, (7)University of California Berkeley, Berkeley, CA, United States, (8)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (9)NASA Goddard Space Flight Center, Greenbelt, MD, United States
It is currently not well understood whether ionospheric particle escape at Mars is dominated by steady-state escape processes or by strong episodic events. Direct observations of strong ionospheric depletion events are therefore useful in determining their relative importance. During several orbital passes on the dayside of Mars, the Langmuir Probe and Waves instrument on the MAVEN spacecraft has observed intense depletions in electron density at low altitudes (~300km) accompanied by high bulk electron temperatures (~1eV). The local environment during these density reductions exhibits features of shocked solar wind plasma, and therefore likely represents a compression to low altitudes of the boundary layer between the ionosphere and the solar wind. Here we will present the characteristics of these low-density warm plasma regions, with discussion of their implications on solar wind forcing of the Martian ionosphere.