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| Titel |
Assimilating remotely sensed cloud optical thickness into a mesoscale model |
| VerfasserIn |
D. Lauwaet, K. Ridder, P. Pandey |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 19 ; Nr. 11, no. 19 (2011-10-14), S.10269-10281 |
| Datensatznummer |
250010125
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| Publikation (Nr.) |
 copernicus.org/acp-11-10269-2011.pdf |
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| Zusammenfassung |
| The Advanced Regional Prediction System, a mesoscale atmospheric model, is
applied to simulate the month of June 2006 with a focus on the near surface
air temperatures around Paris. To improve the simulated temperatures which
show errors up to 10 K during a day on which a cold front passed Paris, a
data assimilation procedure to calculate 3-D analysis fields of specific
cloud liquid and ice water content is presented. The method is based on the
assimilation of observed cloud optical thickness fields into the Advanced
Regional Prediction System model and operates on 1-D vertical columns,
assuming that the horizontal background error covariance is infinite, i.e.
an independent pixel approximation. The rationale behind it is to find
vertical profiles of cloud liquid and ice water content that yield the
observed cloud optical thickness values and are consistent with the
simulated profile. Afterwards, a latent heat adjustment is applied to the
temperature in the vertical column. Data from several meteorological
stations in the study area are used to verify the model simulations. The
results show that the presented assimilation procedure is able to improve
the simulated 2 m air temperatures and incoming shortwave radiation
significantly during cloudy days. The scheme is able to alter the position
of the cloud fields significantly and brings the simulated cloud pattern
closer to the observations. As the scheme is rather simple and
computationally inexpensive, it is a promising new technique to improve the
surface fields of retrospective model simulations for variables that are
affected by the position of the clouds. |
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