Locations where the cold thermal pressure balances the magnetic pressure in the Martian ionosphere

 

An investigation of the locations where the bulk thermal pressure is balanced by magnetic pressure in the Martian ionosphere is reported on. We present a statistical study in which we characterize the location where the plasma and magnetic pressures are equal to one another. The data, recorded by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, have been analyzed from the transition altitude in which the ionospheric ions become magnetized, up to an altitude of ~800km. The electron temperature and density measurements for the plasma thermal pressure were made by the Langmuir Probe and Waves (LPW) instrument, and the magnetic field strength for determining the magnetic pressure was measured by the Magnetometer (MAG) instrument. The three major trends in this pressure balance are: (a) the magnetic pressure is always larger, (b) a clear transition at low altitudes from thermal pressure to magnetic pressure is observed, and (c) the dominant pressure is changing back and forth between the two over a range of altitudes. The findings are studied in congruence with orbital parameters of the MAVEN satellite (including solar local time, latitude, location with respect to crustal fields) to divulge possible explanations of the transition between pressures.