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| Titel |
Ensemble forecasting with a stochastic convective parametrization based on equilibrium statistics |
| VerfasserIn |
P. Groenemeijer, G. C. Craig |
| 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 ; 12, no. 10 ; Nr. 12, no. 10 (2012-05-24), S.4555-4565 |
| Datensatznummer |
250011167
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| Publikation (Nr.) |
 copernicus.org/acp-12-4555-2012.pdf |
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| Zusammenfassung |
| The stochastic Plant-Craig scheme for deep convection was implemented in the
COSMO mesoscale model and used for ensemble forecasting. Ensembles
consisting of 100 48-h forecasts at 7 km horizontal resolution were
generated for a 2000×2000 km domain covering central Europe. Forecasts were
made for seven case studies characterized by different large-scale
meteorological environments. Each 100 member ensemble consisted of 10 groups
of 10 members, with each group driven by boundary and initial conditions
from a selected member from the global ECMWF Ensemble Prediction System. The
precipitation variability within and among these groups of members was
computed, and it was found that the relative contribution to the ensemble
variance introduced by the stochastic convection scheme was substantial,
amounting to as much as 76% of the total variance in the ensemble in one
of the studied cases. The impact of the scheme was not confined to the grid
scale, and typically contributed 25–50% of the total variance even after
the precipitation fields had been smoothed to a resolution of 35 km. The
variability of precipitation introduced by the scheme was approximately
proportional to the total amount of convection that occurred, while the
variability due to large-scale conditions changed from case to case, being
highest in cases exhibiting strong mid-tropospheric flow and pronounced
meso- to synoptic scale vorticity extrema. The stochastic scheme was thus
found to be an important source of variability in precipitation cases of
weak large-scale flow lacking strong vorticity extrema, but high convective
activity. |
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