1981 .

(3 publications)

M. Ackerman, C. Lippens, and C. Muller. Stratospheric aerosols properties from earth limb photography. Nature, 292:587-591, August 1981. [ bib | DOI | ADS link ]

Aerosol abundance and size distributions at various altitudes in the stratosphere are determined by means of balloon-borne observation, at three wavelengths of visible sunlight that have been scattered by the earth limb. In keeping with their strong forward-scattering properties, aerosols re-emit little light at an azimuth angle 180 deg away from the direction of the sun. The limb radiance observed in this case is used to subtract Rayleigh scattering, and to isolate aerosol scattering at all azimuths angle 180 deg away from the direction of the sun. The limb radiance observed in this case is used to subtract Rayleigh scattering, and to isolate aerosol scattering at all azimuths while taking into account the Rayleigh phase function. The data obtained confirm that the phase function can, within experimental uncertainties, be represented by the Henyey-Greenstein function. The stratospheric aerosol size dealt with is in the range 0.04-0.4 microns.

K. Laval, R. Sadourny, and Y. Serafini. Land surface processes in a simplified general circulation model. Geophysical and Astrophysical Fluid Dynamics, 17:129-150, 1981. [ bib | DOI | ADS link ]

The land surface processes as parameterized for the current version of the L.M.D. General Circulation Model are described. The model predicts ground temperature for bare soil, ice and snow; the treatment of ground hydrology involves a prediction of soil moisture and snow depth. The parameterization is tested on a 90-day integration using a sectorial model with artificial modelling of continents and orography; sea surface temperature, surface albedo and ice cover are given assigned values based on climatological data for January. The resulting distributions of hydrological and thermodynamic variables at the Earth's surface are discussed.

K. Laval, H. Le Treut, and R. Sadourny. Effect of cumulus parameterization on the dynamics of a general circulation model. Geophysical and Astrophysical Fluid Dynamics, 17:113-127, 1981. [ bib | DOI | ADS link ]

The purpose of this study is to test a modification of the parameterization of convection in a general circulation model. The analysis is done with a sectorial model. Its resolution is 11 levels and 1625 grid points. In version A of the model, we use a moist convective adjustment (M.C.A.) wherever the air is conditionally unstable and saturated; in version B, we add a convective scheme to M.C.A. in the case of conditionally unstable but not saturated air. This last scheme is based on the parameterization of Kuo (1965). We compare zonal means and energy cycles of the two versions; improvements in version B seem substantial, essentially in latitude-height distribution of energy variables.