Nature 312, 431 - 434 (29 November 1984); doi:10.1038/312431a0

Observations and theory of the solar semidiurnal tide in the mesosphere of Venus

Stephen B. Fels^*, J. T. Schofield^†‡ & David Crisp^*‡

^*Geophysical Fluid Dynamics Laboratory/NOAA, Princeton University, Princeton, New Jersey 08542, USA
^†Department of Atmospheric Physics, University of Oxford, Oxford OX1 3PU, UK
^‡Present addresses: Jet Propulsion Laboratory, California Institute of Tedlnology, Pasadena, 91109, USA (J.T.S.); Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA (D.C.).

The Orbiter Infrared Radiometer experiment, aboard the 1978 Pioneer Venus mission, produced strong evidence for the existence of a semidiurnal solar tide in the mesosphere of Venus¹. At the same time, measurements in situ of radiative fluxes and cloud particle distribution, in other Pioneer Venus experiments, have provided much information about the structure of the solar heating and infared cooling there²⁻⁴, making it possible to calculate the thermal tidal forcing functions with confidence, and also allowing good estimates of the radiative dissipation rates to be made. Because the structure of tidal fields depends sensitively on that of the background zonal mean wind velocity, U(, z), a knowledge of the sources and sinks of tidal energy and of the actual structure of the tide should allow one to infer the behaviour of U. We show here that a physically reasonable mean flow can be found that leads to theoretically predicted tides that are in excellent agreement with those observed. Our zonal mean flow shows a maximum velocity of 130 ms^-1 at 70 km, decreasing dramatically to 0 at 88 km, and a jet-like meridional structure that deviates strongly from solid-body rotation.

References

1.	Schofield, J. T. & Taylor, F. W. Q. Jl R. Met. Soc. 109, 57−80 (1983). | Article |
2.	Kawabata, K. et al. J. geophys. Res. 85, 8129−8140 (1980).
3.	Knollenberg, R. G. et al. J. geophys. Res. 85, 8059−8081 (1980).
4.	Tomasko, M. G. , Doose, L. R. , Smith, P. H. & Odell, A. P. J. geophys. Res. 85, 8167−8186 (1980).
5.	Schofield, J. T. & Diner, D. J. Nature 305, 116−119 (1983). | ISI |
6.	Schubert, G. et al. J. geophys. Res. 85, 8007−8025 (1980).
7.	Chapman, S. & Lindzen, R. S. Atmospheric Tides (Reidel, Dordrecht, 1970).
8.	Pechmann, J. B. thesis, Calif. Inst. Technology (1983).
9.	Lindzen, R. S. J. atmos. Sci. 28, 609−622 (1971). | Article | ISI |
10.	Andrews, D. G. & McIntyre, M. E. J. atmos. Sci. 33, 2031−2048 (1976). | Article | ISI |
11.	Crisp, D. thesis, Princeton Univ. (1983).
12.	Rossow, W. B. , Del Genio, A. D. , Limaye, S. S. , Travis, L. D. & Stone, P. H. J. geophys. Res. 85, 8107−8128 (1980).
13.	Elson, L. S. Geophys. Res. Lett. 6, 720−722 (1979). | ISI |
14.	Crisp, D. & Young, A. T. Icarus 35, 182−188 (1978). | Article | ISI |
15.	Fels, S. B. in Proceedings of the Third Conference on Atmospheric and Oceanic Waves and Stability, 44 (Am. Met. Soc., Boston, 1981).