Calendar Event Details
AEROCENTER: Guoyong Wen
Affiliation: GESTAR/Morgant State University
Event Date: Tuesday, March 31, 2015
Location: G133
Time: 11:00 AM
Assessing a Simple Two-Layer Model for Correcting Clear Sky Reflectance Enhancement Near Clouds Using LES/SHDOM Generated Radiances
The passive retrieval of aerosol properties near clouds is challenging, because sunlight reflected from clouds can significantly enhance the reflectance in nearby clear regions. Ignoring these 3D radiative effects can lead to biases in aerosol retrievals, which can in turn lead to poor characterization of aerosol radiative effects and aerosol-cloud interactions. In earlier studies we developed a simple two-layer model (2LM) to estimate the cloud-induced clear-sky radiance enhancement due to radiative interaction between boundary-layer clouds and the clear-sky molecular layer above. I will present an error analysis for the 2LM-estimated enhancements by comparing them to Spherical Harmonic Discrete Ordinate Method (SHDOM)-modeled full 3D enhancements for a large number of cumulus cloud fields simulated by the UCLA large eddy simulation (LES) model. Focusing on a short wavelength (i.e., the 0.47 micrometers MODIS blue band), we find that the 2LM model (cloud-molecular interaction) accounts for 70% of the 3D enhancement. This framework allows for exploring enhancements from other radiative interactions. Cloud-surface and cloud-aerosol interactions explain an additional 16% and 13%, respectively. This means that a more sophisticated model, that combines aerosol-cloud, cloud-surface and cloud-aerosol interactions, can account for nearly 99% of the total 3D enhancement at 0.47 micrometers.
Posted or updated: Monday, March 16, 2015
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