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A comparative study of rapidly and slowly rotating dynamical regimes in a terrestrial general circulation modelAs a preliminary step in the development of a general circulation model for general planetary use, a simplified vesion of thef GISS Model I GCM has been run at various rotation periods to investigate differences between the dynamical regimes of rapidly and slowly rotating planets. To isolate the dynamical processes, the hydrologic cycle is suppressed and the atmosphere is forced with perpetual annual mean solar heating. All other parameters except the rotation period remain fixed at their terrestrial values. Experiments were conducted for rotation periods of 2/3, 1, 2, 4, 8, 16, 64 and 256 days. The results are in qualitative agreement with similar experiments carried out previously with other GCMs and with certain aspects of one Venus GCM simulation. As rotation rate decreases, the energetics shifts from baroclinc to quasi-barotropic when the Rossby radius of deformation reaches planetary scale. The Hadley cell expands poleward and replaces eddies as the primary mode of large-scale heat transport. Associated with this is a poleward shift of the baroclinic zone and jet stream and a reduction of the equator-pole temperature contrast. Midlatitude jet strength peaks at 8 days period, as does the weak positive equatorial zonal wind which occurs at upper levels at all rotation periods. Eddy momentum transport switches from poleward to equatorward at the same period. Tropospheric mean static stability generally increases in the tropics and decreases in midlatitudes as rotation rate decreases, but the global mean static stability is independent of rotation rate. The peak in the eddy kinetic energy spectrum shifts toward lower wavenumbers, reaching wavenumber 1 at a period of 8 days. Implications of these results for the dynamics of Venus and Titan are discussed. Specifically, it is suggested that the extent of low-level convection determines whether the Gierasch mechanism contributes significantly to equatorial superrotation on these planets.
Document ID
19870056624
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Del Genio, Anthony D.
(NASA Goddard Institute for Space Studies New York, United States)
Suozzo, Robert J.
(Sigma Data Services Corp. New York, United States)
Date Acquired
August 13, 2013
Publication Date
March 15, 1987
Publication Information
Publication: Journal of the Atmospheric Sciences
Volume: 44
ISSN: 0022-4928
Subject Category
Lunar And Planetary Exploration
Accession Number
87A43898
Distribution Limits
Public
Copyright
Other

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