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| Titel |
Downscaling heavy rainfall in the subtropics – a simple approach for dynamical nesting |
| VerfasserIn |
H. Huebener, K. Born, M. Kerschgens |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: Observation, Prediction and Verification of Precipitation (EGU Session 2006) ; Nr. 10 (2007-04-26), S.9-16 |
| Datensatznummer |
250007847
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| Publikation (Nr.) |
 copernicus.org/adgeo-10-9-2007.pdf |
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| Zusammenfassung |
| The simulation of local scale precipitation with nested models often suffers
from large errors in the boundary rows. Advection of precipitation into the
model domain of the small scale model can lead to an overestimation of
precipitation in the boundary grid cells of the nested model and a drying of
the interior grid area. Consequently, the finer scale structure of rainfall
events of the small scale model can not evolve. These errors result from
three main sources: "dynamical", "scale", and "parameterization" problems.
As a first step to reduce the "parameterization" boundary errors, we propose
a nesting procedure where rainwater from the driving larger scale model is
converted to cloud water in the smaller scale model. The nesting method is
applied to a case study of heavy rainfall in semi-arid southern Morocco. The
results show the elimination of erroneous excessive rainfall in the boundary
rows and slightly enhanced rainfall in the interior of the nested model
domain. Additionally, fine scale structures in the precipitation patterns
develop. The excessive surface runoff is clearly diminished in comparison to
the standard nesting procedure. The proposed approach enables scale
consistent precipitation patterns resulting from model physics and
grid-resolution of the smaller scale model for the complete model domain. |
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