Crisp, D. and Ingersoll, A. P. and Hildebrand, C. E. and Preston, R. A. (1990) VEGA Balloon meteorological measurements. In: Venus Atmosphere: proceedings of Workshop IX of the COSPAR 27th plenary meeting. Advances in Space Research. No.10 . Pergamon Press , Oxford, pp. 109-124. ISBN 0-08-040160-0 http://resolver.caltech.edu/CaltechAUTHORS:20121207-152714009
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The VEGA Balloons obtained in-situ measurements of pressure, temperature, vertical winds, cloud density, ambient illumination, and the frequency of lightning during their 48 hour flights in the Venus middle cloud layer (50 to 55 km altitude). In addition, the VLBI tracking experiment provided measurements of balloon positions and horizontal winds along their trajectories. We have used these measurements to develop a comprehensive description of the meteorology of the Venus middle cloud layer. The static stability is usually positive, with values ranging from 0 to 2.0 K/km. There is a 6.5 K offset between the VEGA-1 and VEGA-2 temperature profiles. This large horizontal temperature gradient is probably associated with an east-west temperature disturbance that drifts with the prevailing winds. Vertical winds are large (1–3 m/s) and variable, with turbulent episodes lasting about one hour. This turbulence is associated with upward heat fluxes that range from 0 to 350 W/m^2. Cloud density decreases with altitude. No completely cloud-free regions were observed. No lightning was detected. VLBI tracking results indicate zonal wind speeds of 69.4 and 66.0 m/s for VEGA-1 and VEGA-2, respectively. VEGA-1 observed little meridional transport, but VEGA-2 measured 2.5 m s^(−1) northward winds, which pushed it almost 500 km toward the equator during its flight.
|Item Type:||Book Section|
|Additional Information:||© 1989 COSPAR. We gratefully acknowledge the moral and financial support of Dr. Henry Brinton and the NASA Planetary Atmospheres Program (NAGW-58). This work was also supported by the Jet Propulsion Laboratory. Finally, we wish to acknowledge the assistance of the staffs of the 20 observatories around the world that participated in the VLBI experiment. Contribution number 4715 from the Division of Geological and Planetary Sciences, California Institute of Technology.|
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|Official Citation:||D. Crisp, A.P. Ingersoll, C.E. Hildebrand, R.A. Preston, VEGA Balloon meteorological measurements, Advances in Space Research, Volume 10, Issue 5, 1990, Pages 109-124, ISSN 0273-1177, 10.1016/0273-1177(90)90172-V. (http://www.sciencedirect.com/science/article/pii/027311779090172V)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||10 Dec 2012 17:08|
|Last Modified:||10 Dec 2012 17:08|
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