A method for analyzing how various parts of clouds influence each other's brightness -: art. no. 4706

[ 1] This paper proposes a method for obtaining new information on three- dimensional ( 3- D) radiative effects that arise from horizontal radiative interactions in heterogeneous clouds. Unlike current radiative transfer models, it can not only calculate how 3- D effects change radiative quantities at any given point but can also determine which areas contribute to these 3- D effects, to what degree, and through what mechanisms. The new method uses Monte Carlo radiative transfer simulations to generate numerous photon trajectories through the cloud field, and then it examines the radiative processes along each trajectory. After describing the proposed method, the paper illustrates its new capabilities both for detailed case studies and for the statistical processing of large data sets. Because the proposed method makes it possible, for the first time, to link a particular change in cloud properties to the resulting 3- D effect, it can be used to develop new types of radiative transfer parameterizations. Encouraging initial results suggest that such parameterizations will be able to incorporate 3- D effects in practical applications currently limited to 1- D theory, such as remote sensing of cloud properties and dynamical cloud modeling.