37th DPS Meeting, 4-9 September 2005
Session 54 Moon, Mercury and Venus
Oral, Thursday, September 8, 2005, 4:20-6:00pm, Law LG19

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[54.05] Cloud-Level Winds on Venus

T. Tavenner (New Mexico State University), E.F. Young (South West Research Institute), J. Murphy (New Mexico State University), M. A. Bullock, S. Coyote, S. Rafkin (South West Research Institute)

We have observed the nightside of Venus at 2.3 microns during a 10 day period with the IRTF on Mauna Kea. Each morning observation covered a 3-hour span, sufficient to determine the major cloud motions for each day. These observations have allowed us to construct movies of lower cloud motion, derive cloud-level winds, and identify transient features in the observed Venusian wind field.

The lower cloud deck of Venus (48-52 km), is backlit by 2.3 micron thermal radiation emanating from about 35 km. We acquired both spectra and K-filter images centered at 2.26 microns with the SpeX instrument on the IRTF. By allowing the spectrometer slit to drift over the disk of Venus, we obtained spectral image cubes from 0.8 to 2.5 microns simultaneously with the images. By taking the sharpest 5% of those images in our data set we are typically able to achieve 0.5 arcsec resolution over the disk, or 220km resolution at the equator.

In this talk we will present our processed images, cloud-motion movies, and derived wind speeds. Comparisons with previous ground-based (Crisp et al. 1991) and spacecraft (Carlson et al. 1991) datasets will be made, and the implications of our results for understanding the atmospheric circulation in Venus' lower cloud levels.

This work was supported by NASA's Infrared Telescope Facility and by the NASA Planetary Astronomy Program.

Carlson, R.W. et al., Science, 253, 1541-1548, 1991.; Crisp, D., et al., Science, 253, 1538-1541, 1991.

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Bulletin of the American Astronomical Society, 37 #3
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