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Title: Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c

Here, a new approach for modeling photolysis rates ( J values) in atmospheres with fractional cloud cover has been developed and is implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observations of the vertical correlation of cloud layers, Cloud-J 7.3c provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud combinations by four quadrature atmospheres produces mean J values in an atmospheric column with root mean square (rms) errors of 4 % or less compared with 10–20 % errors using simpler approximations. Cloud-J is practical for chemistry–climate models, requiring only an average of 2.8 Fast-J calls per atmosphere vs. hundreds of calls with the correlated cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections, is also incorporated into Cloud-J.
Authors:
 [1]
  1. Univ. of California, Irvine, CA (United States). Earth System Science Dept.
Publication Date:
Grant/Contract Number:
SC0012536; SC-0012536
Type:
Published Article
Journal Name:
Geoscientific Model Development (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development (Online); Journal Volume: 8; Journal Issue: 8; Journal ID: ISSN 1991-9603
Publisher:
European Geosciences Union
Research Org:
Univ. of California, Irvine, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1210106
Alternate Identifier(s):
OSTI ID: 1454258

Prather, M. J.. Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c. United States: N. p., Web. doi:10.5194/gmd-8-2587-2015.
Prather, M. J.. Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c. United States. doi:10.5194/gmd-8-2587-2015.
Prather, M. J.. 2015. "Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c". United States. doi:10.5194/gmd-8-2587-2015.
@article{osti_1210106,
title = {Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c},
author = {Prather, M. J.},
abstractNote = {Here, a new approach for modeling photolysis rates (J values) in atmospheres with fractional cloud cover has been developed and is implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observations of the vertical correlation of cloud layers, Cloud-J 7.3c provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud combinations by four quadrature atmospheres produces mean J values in an atmospheric column with root mean square (rms) errors of 4 % or less compared with 10–20 % errors using simpler approximations. Cloud-J is practical for chemistry–climate models, requiring only an average of 2.8 Fast-J calls per atmosphere vs. hundreds of calls with the correlated cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections, is also incorporated into Cloud-J.},
doi = {10.5194/gmd-8-2587-2015},
journal = {Geoscientific Model Development (Online)},
number = 8,
volume = 8,
place = {United States},
year = {2015},
month = {8}
}