A Multilayer, 1-D Solar Radiative Transfer Algorithm that Accounts for Subgrid-Scale Cloud Variability
نویسنده
چکیده
A multi-layer, one-dimensional (1-D) solar radiative transfer algorithm that accounts for subgrid-scale cloud variability is presented. This algorithm was implemented in the National Center for Atmospheric Research (NCAR)-Community Climate Model (CCM) broadband column model. A subset of its validation is shown here using a three-dimensional (3-D) inhomogeneous cloud field generated by a cloudresolving model. Reference calculations were obtained by a 3-D Monte Carlo (MC) simulation. The new code operates on horizontally averaged information, such as cloud fraction, mean, and variance of cloud optical depth, and reduces plane-parallel, homogeneous (PPH)-biases for top of atmosphere (TOA) albedo and surface absorptance by typically more than 85%. Moreover, its estimates of atmospheric heating rate usually differ from MC values by less than 10%.
منابع مشابه
HARRIS AND FOUFOULA-GEORGIOU: CLOUD MODEL DOWNSCALING Subgrid variability and stochastic downscaling of modeled clouds: Effects on radiative transfer computations for rainfall retrieval
The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) Goddard Profiling (GPROF) rainfall retrieval algorithm is an inversion type algorithm, which uses numerical cloud models and radiative transfer schemes to simulate the brightness temperatures that the TMI would see, thereby allowing one to relate hydrometeor profiles to brightness temperature. The variability in modeled hydro...
متن کاملA novel approach for introducing cloud spatial structure into cloud radiative transfer parameterizations
Subgrid-scale variability is one of the main reasons why parameterizations are needed in largescale models. Although some parameterizations started to address the issue of subgrid variability by introducing a subgrid probability distribution function for relevant quantities, the spatial structure has been typically ignored and thus the subgrid-scale interactions cannot be accounted for physical...
متن کاملAccounting for Unresolved Clouds in a 1D Infrared Radiative Transfer Model. Part II: Horizontal Variability of Cloud Water Path
A 1D infrared radiative transfer model that handles clouds with subgrid-scale horizontal variability is developed and tested. It assumes that fluctuations in cloud absorptance optical depth k across layers (and collections of layers) can be described by gamma distributions. Unlike homogeneous clouds, flux incident at a level inside a horizontally inhomogeneous cloud requires explicit computatio...
متن کاملStatistical characteristics of cloud variability. Part 2: Implication for parameterizations of microphysical and radiative transfer processes in climate models
The effects of subgrid cloud variability on grid-average microphysical rates and radiative fluxes are examined by use of long-term retrieval products at the Tropical West Pacific, Southern Great Plains, and North Slope of Alaska sites of the Department of Energy’s Atmospheric Radiation Measurement program. Four commonly used distribution functions, the truncated Gaussian, Gamma, lognormal, and ...
متن کاملA Novel Approach for Introducing 3D Cloud Spatial Structure Into 1D Radiative Transfer
For original submission and image(s), see ARM Research Highlights http://www.arm.gov/science/highlights/ Research Highlight Subgrid-scale variability is one of the main reasons why parameterizations are needed in large-scale models. Similarly, subpixel-scale cloud heterogeneity also plagues satellite retrievals of cloud and aerosol properties. Cloud heterogeneity, to some extent, can be represe...
متن کامل