1997 .

(3 publications)

F. Forget and R. T. Pierrehumbert. Warming Early Mars with Carbon Dioxide Clouds That Scatter Infrared Radiation. Science, 278:1273, 1997. [ bib | DOI | ADS link ]

P. L. Read, M. Collins, F. Forget, R. Fournier, F. Hourdin, S. R. Lewis, O. Talagrand, F. W. Taylor, and N. P. J. Thomas. A GCM climate database for mars: for mission planning and for scientific studies. Advances in Space Research, 19:1213-1222, 1997. [ bib | DOI | ADS link ]

The construction of a new database of statistics on the climate and environment of the Martian atmosphere is currently under way, with the support of the European Space Agency. The primary objectives of this database are to provide information for mission design specialists on the mean state and variability of the Martian environment in unprecedented detail, through the execution of a set of carefully validated simulations of the Martian atmospheric circulation using comprehensive numerical general circulation models. The formulation of the models used are outlined herein, noting especially new improvements in various schemes to parametrize important physical processes, and the scope of the database to be constructed is described. A novel approach towards the representation of large-scale variability in the output of the database using empirical eigenfunctions derived from statistical analyses of the numerical simulations, is also discussed. It is hoped that the resulting database will be of value for both scientific and engineering studies of Mars' atmosphere and near-surface environment.

M. E. Ockert-Bell, J. F. Bell, J. B. Pollack, C. P. McKay, and F. Forget. Absorption and scattering properties of the Martian dust in the solar wavelengths. Journal of Geophysical Research, 102:9039-9050, 1997. [ bib | DOI | ADS link ]

A new wavelength-dependent model of the single-scattering properties of the Martian dust is presented. The model encompasses the solar wavelengths (0.3 to 4.3 μm at 0.02 μm resolution) and does not assume a particular mineralogical composition of the particles. We use the particle size distribution, shape, and single-scattering properties at Viking Lander wavelengths presented by Pollack et al. [1995]. We expand the wavelength range of the aerosol model by assuming that the atmospheric dust complex index of refraction is the same as that of dust particles in the bright surface geologic units. The new wavelength-dependent model is compared to observations taken by the Viking Orbiter Infrared Thermal Mapper solar channel instrument during two dust storms. The model accurately matches afternoon observations and some morning observations. Some of the early morning observations are much brighter than the model results. The increased reflectance can be ascribed to the formation of a water ice shell around the dust particles, thus creating the water ice clouds which Colburn et al. [1989], among others, have predicted.