This page contains information related to my 2005 DPS abstract.
New VLA Observations of Mars Atmospheric Water Vapor
B.J. Butler NRAO
J.G. Johnston NRAO
R.T. Clancy SSI
M.A. Gurwell CfA
The presence of water vapor in the atmosphere of Mars is becoming increasingly recognized as a key element of that planet's climate. Previous studies have characterized latitudinal and seasonal variations in the quantity and transport of water vapor, but detailed information regarding its distribution as a function of altitude, and how that changes with season, is still lacking. One method of determining the vertical distribution is via spectroscopic observations of the 1.35-cm rotational transition (Clancy et al. 1992, Icarus, 100, 48; Clancy et al. 1996, Icarus, 122, 36). Shortly after the 2003 opposition, such observations were conducted with the Very Large Array (VLA). The observations were taken on four dates, in two high resolution configurations of the VLA. These observations provide a good combination of sensitivity and spatial resolution for mapping the martian atmospheric water vapor. The shape of the line can be used to infer a vertical profile, and spatial variations around the limb give information on the latitudinal and local time distributions of water vapor. The season on Mars during these observations (Ls=265-285, around southern summer solstice) is of particular interest, as the water vapor supplied to the atmosphere from the south polar cap at that time appears to vary significantly from year to year. These observations can be compared to a number of contemporaneous observations from other instruments, including the Mars Global Surveyor Thermal Emission Spectrometer (MGS TES), the Submillimeter Wave Astronomy Satellite (SWAS) and the Submillimeter Array (SMA). Results from the preliminary analysis of these new data will be presented and implications discussed. (Grossman & Muhleman 1992, BAAS, 24, 954).
The observations were all done at the Very Large Array (the VLA is operated by the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.), which is a collection of 27 radio antennas spread out on the plains of San Augustin, New Mexico.
Last Modified on 2005Jul01