HR: 10:35h
AN: P32A-02    [Abstracts]
TI: Climatology of Mars Thermosphere and Exospheric Temperatures
AU: * Keating, G M
EM: g.m.keating@larc.nasa.gov
AF: The George Washington University, 1 Old Oyster Point Road, Suite 200, Newport News, VA 23602, United States
AU: Bougher, S W
EM: bougher@umich.edu
AF: University of Michigan, Space Research Building, Ann Arbor, MI 48109-2143, United States
AU: Theriot, M E
EM: m.e.theriot@larc.nasa.gov
AF: The George Washington University, 1 Old Oyster Point Road, Suite 200, Newport News, VA 23602, United States
AU: Tolson, R H
EM: r.h.tolson@larc.nasa.gov
AF: National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666, United States
AB: The accelerometer experiment facility aboard Mars Reconnaissance Orbiter (MRO) obtained neutral density measurements and inferred temperature measurements 100km to 170km over the entire Southern Hemisphere of Mars in 2006. When combined with our previous accelerometer experiments on Mars Global Surveyor and Mars Odyssey, global measurements are obtained showing variations with latitude, seasons, day/night, aphelion/perihelion, and solar activity. The measurements also show a stability of climatology when compared with MEX Stellar Occultation measurements. Temperatures are found to be fairly constant within 40° latitude of the equator rising with altitude due to solar euv radiation absorption at higher altitudes. Exospheric temperatures are discovered to be near 130 K on the nightside (3am) and near 200K on the dayside (3pm). MTGCM models are about the same as observed at night, but somewhat warmer than observed on the dayside. The cooler dayside observations may indicate somewhat less atmospheric escape than the MTGCM temperatures would predict. We have discovered winter polar warming in the lower thermosphere from the accelerometer measurements. Apparently, meridional flow from the summer to winter hemisphere results in strong adiabatic heating near the winter pole causing the warming. This effect is stronger at winter North Pole than winter South Pole apparently due to the planet being near perihelion at North Pole winter.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 0350 Pressure, density, and temperature
DE: 0355 Thermosphere: composition and chemistry
DE: 5210 Planetary atmospheres, clouds, and hazes (0343)
DE: 5405 Atmospheres (0343, 1060)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting