HR: 0830h
AN: NG51A-0833    [PDF]
TI: Radiative Transfer Through Stratified Multifractal Clouds
AU: * Grosdidier, Y
AF: McGill University, Dept. of Physics, 3600 University St., Montreal, PQ H3A 2T8 Canada
AU: Watson, B P
EM: bwatson@stlawu.edu
AF: St. Lawrence University, Dept. of Physics, Canton, NY 13617 United States
AU: Lovejoy, S
EM: lovejoy@physics.mcgill.ca
AF: McGill University, Dept. of Physics, 3600 University St., Montreal, PQ H3A 2T8 Canada
AU: Schertzer, D
AF: CEREVE Ecole Nationale des Ponts et Chausse‚s, 6-8, avenue Blaise Pascal, Cite Descartes, 77455 France
AB: Analysis of nearly 1000 satellite and in situ cloud radiances has shown in both infrared and visible wavelengths, over ranges spanning thousands of kilometers down to less than a meter, that the radiances are multifractal to within 1.5% per octave in scale (or better). In order to model this, we need reliable multifractal models of the liquid water density. We first discuss some technical points needed to obtain accurate mulitfractal statistics: these include the issues of numerical stability and the need to make corrections both for structures larger than the simulation region and smaller than a pixel. We then use a variety of techniques (e.g., Monte Carlo, and Green's function) to simulate the radiative transfer in the clouds and we relate (scale by scale) the resulting radiation fields and the (anomalous) scattering statistics to those of the cloud. We compare and contrast our results with those of the low variability "bounded cascade" model in which the multifractality is essentially destroyed by successive truncation of singularities as the cascade proceeds to smaller scales.
DE: 3220 Nonlinear dynamics
DE: 3250 Fractals and multifractals
SC: Nonlinear Geophysics [NG]
MN: 2003 Fall Meeting