Monday 23 January 2006 at 2.00pm @ the JAC
Brad Sandor
Space Science Institute, Boulder, Colorado
"Mapping Chemistry and Dynamics of the Venus and Mars Atmospheres"
ABSTRACT:
We use the JCMT to observe sub-mm absorption lines of trace molecular
species in the atmospheres of Mars and Venus. When these planets
present their largest apparent diameters (Mars at opposition, Venus
at inferior conjunction), the JCMT beam is placed at numerous
(5 on Mars, 11 on Venus) distinct locations on each planetary disk,
to obtain spatial mapping of each absorption line. Observations at
other planetary geometries are used as hemisphere-average measurements
of time variability, with which we study diurnal, seasonal, and
interannual forcings.
Each observed molecular line provides an abundance measurement
for that molecule (12CO, 13CO, HDO, H2O2, SO2, SO). Shape of
each line is dominated by collisional (pressure) broadening,
such that data primarily characterize the middle atmosphere of each
planet. The high s/n lines 12CO and 13CO provide measurements of
temperature as a function of altitude. Further, 12CO and 13CO line
centers are Doppler shifted by planetary winds, such that observations
at off-center disk locations yield large-scale wind measurements.
Details of our discoveries, interpretations, and ongoing studies
will be discussed.
Recent publications derived from JCMT data:
-
Clancy, R.T., B.J. Sandor, and G.H. Moriarty-Schieven,
A Measurement of the 362 GHz Absorption Line of Mars Atmospheric
H2O2. Icarus, 168. 116--121. 2004.
- Clancy, Sandor, & Moriarty-Schieven, Sub-millimeter Observations
of Mars Atmospheric H2O2 and Doppler Winds, 36th COSPAR Scientific
Assembly, Paris, France, 18-24 July, 2004a.
- Clancy, R.T., B.J. Sandor, and G.H. Moriarty-Schieven,
Observational Definition of the Venus Mesopause: Vertical Structure,
Diurnal Variation, and Short-Term Instability. Icarus, 161. 1-16. 2003.
Related publication derived from mm-wave (Kitt Peak, AZ) data:
-
Sandor, B.J., and R.T. Clancy. Water Vapor Variations in the
Venus Mesosphere from Microwave Spectra. Icarus, 177. 129--143.
2005.
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