|
|
| Temporal Variability and Latitudinal Jets in Venus's Zonal Wind Profiles |
| Presentation Time: Wednesday, 11:40 a.m. - 11:50 a.m. |
Eliot F. Young1, M. A. Bullock1, T. Tavenner2, S. Coyote3, J. R. Murphy2
1Southwest Research Inst., 2New Mexico State University, 3Consultant. |
| Presentation Number: 62.08 |
| Facility Keywords:
IRTF |
We have observed Venus's night hemisphere from NASA's IRTF (Infrared Telescope Facility) during each inferior conjunction since 2001 to quantify the motion of features in Venus's lower and middle cloud decks. We now present latitudinal profiles from 11 nights, obtained in May and July 2004, February 2006 and September 2007.
In about 7 of the 11 nights there are zonal jets near 45N and/or -50S, with speed differentials of 5 to 15 m/s relative to the adjacent equatorward latitude bands. These jets may be evidence of episodic Hadley cell-type circulation. About half of the nights show relatively constant velocity profiles between the latitudes of 50N to 50S, suggesting that considerable mixing is taking place between latitudes. Our most remarkable result is the temporal variability in the median zonal speeds from day to day. For example, the median velocity near the equator increases from 53 to 65 m/s over the period from July 11 - 13, 2004, and increases from 65 to 82 m/s over the period from Sept. 9 - 11, 2007. These velocity changes are too great to be due to the tracking of clouds that are in the middle vs. lower cloud deck, nor can they be caused by clouds that occupy different altitudes; a velocity variation of 25% corresponds to an altitude difference of 15 km, based on vertical profiles of zonal windspeeds from tracking of Pioneer Venus and Venera descent probes. Fifteen km is greater than the expected variation in either cloud base.
VIRTIS observations of Venus's southern hemisphere were also obtained in September 2007 and should be able to corroborate or contradict the observed variations.
This work was supported by NASA's Planetary Astronomy and Atmospheres programs. |
| |
|
|
|
|
|
|
The Online Abstract Submission and Invitation System
© 1996 - 2010 Coe-Truman Technologies, Inc. All rights reserved.
|
|
|
|
|
|
