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

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.