Aug 03 2007
Entrainment-Mixing and Radiative Transfer Simulation in Boundary Layer Clouds
Here’s an important new paper about the the effects of mixing on the radiation budget of low level clouds. I haven’t had time to totally digest it yet. When I do, I’ll probably post my comments in a new thread. This is related to the research that I’m doing now, so I need to make sure I didn’t get scooped!
Chosson, F., J.L. Brenguier, and L. Schüller, 2007: Entrainment-Mixing and Radiative Transfer Simulation in Boundary Layer Clouds. J. Atmos. Sci., 64, 2670–2682.
In general circulation models, clouds are parameterized and radiative transfer calculations are performed using the plane-parallel approximation over the cloudy fraction of each model grid. The albedo bias resulting from the plane-parallel representation of spatially heterogeneous clouds has been extensively studied, but the impact of entrainment-mixing processes on cloud microphysics has been neglected up to now. In this paper, this issue is examined by using large-eddy simulations of stratocumulus clouds and tridimensional calculations of radiative transfer in the visible and near-infrared ranges. Two extreme scenarios of mixing are tested: the homogeneous mixing scheme with constant concentration and reduced droplet sizes, against the inhomogeneous mixing scheme, with reduced concentration and constant droplet sizes. The tests reveal that entrainment-mixing effects at cloud top may substantially bias the simulated albedo. In the worse case, which corresponds to a fragmented and thin stratocumulus cloud, the albedo bias changes from ?3% to ?31% when using both mixing schemes alternatively.
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One Response to “Entrainment-Mixing and Radiative Transfer Simulation in Boundary Layer Clouds”
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There is a mistake in this paper, Fig.3 and 4 are interverted (but not the legends). Send me a mail, I am interested in your research, I want to speak a bit about what you’re doing.
by,
Fred.