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Impact of MIE-Resonances on the Atmospheric Absorption of Water CloudsClouds strongly modulate radiative transfer processes in the Earth's atmosphere. Studies, which simulate bulk properties of clouds, such as absorption, require methods that accurately account for multiple scattering among individual cloud particles. Multiple scattering processes are well described by MIE-theory, if interacting particles have a spherical shape. This is a good assumption for water droplets. Thus, simulations for water clouds (especially for interactions with solar radiation) usually apply readily available MIE-codes. The presence of different drop-sizes, however, necessitates repetitive calculations for many sizes. The usual representation by a few sizes is likely to miss contributions from densely distributed, sharp resonances. Despite their usually narrow width, integrated over the entire size-spectrum of a cloud droplet distribution, the impact of missed resonances could add up. The consideration of these resonances tends to increase cloud extinction and cloud absorption. This mechanism for a larger (than by MIE-methods predicted) solar absorption has the potential to explain observational evidence of larger than predicted cloud absorption at solar wavelengths. The presentation will address the absorption impact of added resonances for typical properties of water clouds (e.g. drop size distributions, drop concentrations and cloud geometry). Special attention will be given to scenarios with observational evidence of law than simulated solar absorption; particularly if simultaneous measurements of cloud micro- and macrophysical properties are available.
Document ID
20020081028
Document Type
Conference Paper
Authors
Wiscombe, W. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Kinne, S. (Maryland Univ. Baltimore County Catonsville, MD United States)
Nussenzveig, H. (Instituto de Fisica Rio de Janerio, Brazil)
Lau, William K. M.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Meteorology and Climatology
Meeting Information
American Meteorological Society 11th Conference on Atmospheric Radiation(Ogden, UT)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.