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Titel |
Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c |
VerfasserIn |
M. J. Prather |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 8, no. 8 ; Nr. 8, no. 8 (2015-08-14), S.2587-2595 |
Datensatznummer |
250116507
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Publikation (Nr.) |
copernicus.org/gmd-8-2587-2015.pdf |
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Zusammenfassung |
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. |
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