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A 3-D Reconstruction of a Regional-Scale Cloud Field from Satellite Data for Use in a Broadband Monte Carlo Radiative Transfer Model

Galinsky, V., Ramanathan, V., Boer, E., Podgorny, I., and Vogelmann, A. M., Center for Atmospheric Sciences-Scripps Institution of Oceanography
Eighth Atmospheric Radiation Measurement (ARM) Science Team Meeting

The absence of realistic 3-D cloud fields and their associated radiative transfer in current general circulation models (GCM) or radiative transfer models may result in large inconsistencies in the Earth's energy budget calculations. We investigate these effects by reconstructing the regional-scale, 3-D cloud field structure from multi-spectral satellite imagery. From this reconstruction, we compute the radiative fluxes using a broadband Monte Carlo model. 3-D fields of optical depths and cloud top heights are retrieved from Japanese Geostationary Meteorological Satellite (GMS-4) data over the tropical western Pacific using simple models of visible and infrared radiative transfer and cloud/clear-sky detection. The corresponding cloud microphysical properties cannot be retrieved from the two spectral windows available in the GMS data. Therefore, the cloud optical depth to geometrical depth conversion is roughly approximated using microphysical properties simulated by a numerical model and observed from aircraft in the general region and time period. Broadband fluxes and cloud heating rates for the regional-scale 3-D cloud fields are computed by a Monte Carlo model run on a CRAY T3E massive parallel processing computer (see Vogelmann et al. abstract for model description). A first-order validation of the computed fluxes is made through a comparison with in situ Regional Atmospheric Modeling System (RAMS) aircraft data. This model will provide important insights into the problem of cloud parameterization with the help of real satellite data (see Ramanathan and Boer abstract), and through comparisons with coincident output from a regional cloud model (see Zhang and Ramanathan abstract). Future improvements of the model are straightforward, as soon as more detailed data and self consistent microphysical information become available. Also, the availability of two-instrument/two-satellite view data may allow the inclusion of horizontal fluxes resulting from the variability in cloud top heights. The next step is to apply the satellite and regional cloud models to data for the Southern Great Plains (SGP) site where we may compare the output fields to observations in the region.

Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).