A major source of uncertainty in regional climate model (RCM) simulations arises from the parameterisation of sub-grid scale convection. With increasing model resolution, approaching the so-called convection permitting scale, it is possible to switch off most of the convection parameterisations. A set of simulations using COSMO-CLM model has been carried out at different resolutions in order to investigate possible improvements and limitations resulting from increased horizontal resolution. For our analysis, 30 years were simulated in a triple nesting setup with 50, 7 and 2.8 km resolutions, with ERA40 reanalysis data at the lateral boundaries of the coarsest nest. The investigation area covers the state of Baden-Württemberg in southwestern Germany, which is a region known for abundant orographically induced convective precipitation. A very dense network of high temporal resolution rain gauges is used for evaluation of the model simulations. The purpose of this study is to examine the differences between the 7 and 2.8 km resolutions in the representation of precipitation at sub-daily timescales, and the atmospheric conditions leading to convection. Our results show that the highest resolution of RCM simulations significantly improves the representation of both hourly intensity distribution and diurnal cycle of precipitation. In addition, at convection permitting scale the atmospheric fields related to convective precipitation show a better agreement with each other. The results imply that higher spatial resolution partially improves the representation of the precipitation field, which must be the way forward for regional climate modelling.
Benefit of convection permitting climate model simulations in the representation of convective precipitation
G. Fosser,G. Fosser,S. Khodayar,Peter Berg
Published 2014 in Climate Dynamics
ABSTRACT
PUBLICATION RECORD
- Publication year
2014
- Venue
Climate Dynamics
- Publication date
Unknown publication date
- Fields of study
Physics, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- 2.8 km resolution
The innermost model grid spacing used in the simulations.
- 7 km resolution
The intermediate model grid spacing used in the simulations.
- baden-württemberg
The southwestern German region used as the evaluation area for precipitation comparisons.
- convection-permitting scale
A model-resolution regime fine enough to explicitly represent most convective processes.
- convective precipitation
Precipitation produced by convective atmospheric processes.
- cosmo-clm model
A regional climate model used here to run nested simulations at multiple horizontal resolutions.
Aliases: COSMO-CLM
- diurnal cycle of precipitation
The within-day timing pattern of precipitation occurrence or intensity.
- era40 reanalysis data
The reanalysis dataset used to prescribe the lateral boundary conditions for the outermost simulation nest.
Aliases: ERA40 reanalysis
- hourly intensity distribution
The distribution of precipitation intensities measured or simulated on an hourly basis.
- rain gauges
A dense network of precipitation measurements collected at high temporal resolution for model evaluation.
- triple nesting setup
A nested simulation design with outer, middle, and inner grids at progressively finer resolution.
Aliases: triple nesting
REFERENCES
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