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Detailed Reference Information |
Mayr, H.G., Harris, I., Hartle, R.E. and Hoegy, W.R. (1978). Diffusion model for the upper atmoshpere of venus. Journal of Geophysical Research 83: doi: 10.1029/JA083iA09p04411. issn: 0148-0227. |
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On the basis of a linear theory it is shown that wind-induced diffusion associated with large-scale circulation is the Venus atmosphere leads to nighttime bulges in O (consistent with the Dickinson and Ridley model), He, and H. The effect on He is very large with a 243-day rotation period of the atmosphere, yielding an upper limit for th maximum/minimum diurnal density ratio of -1000. This ratio is much smaller for H (max/min of -4) due to the greater importance of exospheric flow, which acts (like for He) as a damping mechanism. For the faster rotation period of 4 days consistent with the motions of the cloud tops, the diurnal variation of O is significantly reduced, contributing to an increse by a factor of two in the horizontal wind velocity. The same effect significantly reduces the He variations to an increase by a factor of 7 from day to night. The results suggest that composition and wind measurements provide valuable information on the rotation rate of the cytherean thermosphere. |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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