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Third Intercomparison of Radiation Codes in Climate Models

Title: Third Intercomparison of Radiation Codes in Climate Models: Longwave Cloudy Sky Benchmarks and Comparisons with Approximate Methods.
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Name(s): Kablick, George P., III, author
Ellingson, Robert G., professor directing thesis
Cai, Ming, committee member
Liu, Guosheng, committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2008
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: As a continuation to the shortwave phase of the third Intercomparison of Radiation Codes in Climate Models (ICRCCM III) by Barker et al. (2003), this study establishes longwave benchmarks for inhomogeneous cloud fields and compares the performance of three approximate, one-dimensional (1D) radiation models. The benchmarks are calculated using a correlated-k three-dimensional Monte Carlo (3DMC) algorithm that is validated via comparisons to line-by-line calculations for simple atmospheres. The approximate methods include an independent pixel approximation (IPA) and two cloud-overlap schemes: maximum/random (MRO) and random (RO). The test cases are the same as those used in the shortwave ICRCCM III, and were generated from various cloud resolving models (CRMs). These cases represent a variety of inhomogeneous cloud types that are important radiative forcing mechanisms of general circulation models (GCMs). Domain-averaged fluxes and heating rates from these six "real cloud" atmospheres show that the IPA is consistently more accurate than the cloud-overlap models with respect to the benchmarks. For example, comparisons of model results for the ATEX case yield a maximum cloud layer heating rate error of -20 K/day from using cloud-overlap models, whereas the IPA error is only -2.5 K/day. These differences can be attributed to the 3D effects of cloud radiation, and indicate the need to refine longwave 1D climate radiation codes so that they compensate for unresolved clouds.
Identifier: FSU_migr_etd-3405 (IID)
Submitted Note: A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Summer Semester, 2008.
Date of Defense: July 8, 2008.
Bibliography Note: Includes bibliographical references.
Advisory Committee: Robert G. Ellingson, Professor Directing Thesis; Ming Cai, Committee Member; Guosheng Liu, Committee Member.
Subject(s): Meteorology
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_etd-3405
Owner Institution: FSU

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Kablick, G. P. (2008). Third Intercomparison of Radiation Codes in Climate Models: Longwave Cloudy Sky Benchmarks and Comparisons with Approximate Methods. Retrieved from http://purl.flvc.org/fsu/fd/FSU_migr_etd-3405