Temporal variability of waves at the proton cyclotron frequency upstream from Mars: Implications for Mars distant hydrogen exosphere

• Main Authors: Bertucci, Cesar, Romanelli, Norberto Julio, Gomez, Daniel Osvaldo
• Language: unknown
• Published: 2013
• Subjects: Exosphere; Hydrogen; Mars; Pick-up; Thermosphere; Waves; Direct measurement; Mars global surveyor; Plasma wave generation; Southern latitudes; Temporal variability; Cyclotron resonance; Pickups; Protons; Solar energy; corona; density; Mars Pathfinder; orbit determination; polar region; solar activity; temporal variation; wave field; Argentina; South Pole; South pole
• Online Access: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00948276_v40_n15_p3809_Bertucci; https://hdl.handle.net/20.500.12110/paper_00948276_v40_n15_p3809_Bertucci

We report on the temporal variability of the occurrence of waves at the local proton cyclotron frequency upstream from the Martian bow shock from Mars Global Surveyor observations during the first aerobraking and science phasing orbit periods. Observations at high southern latitudes during minimum-to-mean solar activity show that the wave occurrence rate is significantly higher around perihelion/southern summer solstice than around the spring and autumn equinoxes. A similar trend is observed in the hydrogen (H) exospheric density profiles over the Martian dayside and South Pole obtained from a model including UV thermospheric heating effects. In spite of the complexity in the ion pickup and plasma wave generation and evolution processes, these results support the idea that variations in the occurrence of waves could be used to study the temporal evolution of the distant Martian H corona and its coupling with the thermosphere at altitudes currently inaccessible to direct measurements. © 2013. American Geophysical Union. All Rights Reserved. Fil:Bertucci, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Romanelli, N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Gomez, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.