DPS 2001 meeting, November 2001
Session 10. Worlds Inside 1 AU Posters
Displayed, 9:00am Tuesday - 3:00pm Saturday, Highlighted, Tuesday, November 27, 2001, 5:00-7:00pm, French Market Exhibit Hall

[Previous] | [Session 10] | [Next]


[10.07] Microwave Remote Sensing of the Temperature and Distribution of Sulfur Compounds in the Lower Atmosphere of Venus

J.M. Jenkins (SETI Inst./NASA A.R.C.), M.A. Kolodner (Johns Hopkins Univ./A.P.L.), B.J. Butler (N.R.A.O.), S.H. Suleiman (TRW), P.G. Steffes (Georgia Tech)

A dual-wavelength radio frequency observation of Venus was performed on April 5, 1996 with the Very Large Array to investigate potential variations in the vertical and horizontal distribution of temperature and the sulfur compounds sulfur dioxide (SO2) and sulfuric acid vapor (H2SO4(g)) in the Venus atmosphere. Brightness temperature maps were produced which feature significantly darkened polar regions compared to the brighter low-latitude regions at both observed frequencies. This is the first time such polar features have been seen unambiguously in radio wavelength observations of Venus. Vertical profiles of temperature and abundance of H2SO4(g) were retrieved from the maps given an assumed sub-cloud abundance of SO2. The results indicate a substantially higher abundance of H2SO4(g) at high latitudes (above 45o) than in the low-latitude regions. The temperature profiles are significantly warmer than the profile obtained by the Pioneer Venus sounder probe at altitudes <20-40 km (depending on location). The H2SO4(g) profiles obtained at high latitudes are consistent with those derived from the Magellan radio occultations, peaking at around 8 ppm at an altitude of 46 km and decaying rapidly away from that altitude. At low latitudes, no significant H2SO4(g) is observed. This contrasts with Mariner 10 measurements between 44 and 50 km which followed saturation abundance to ~9 ppm at ~47 km. Our results are also not consistent with the value of 130 ppm for SO2 reported by Bézard et al. (1993) from near-IR measurements. Such a high abundance of SO2, along with their cooler assumed temperature structure, is not supported by our data - either a lower abundance of SO2 or higher atmospheric temperature is required. The retrieved temperature profile and higher abundance of H2SO4(g) in polar regions is consistent with a strong equatorial to polar cloud level Hadley cell type circulation in the atmosphere of Venus.


[Previous] | [Session 10] | [Next]