Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/gmd-2017-329
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Model evaluation paper
13 Feb 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Geoscientific Model Development (GMD).
A new region-aware bias correction method for simulated precipitation in the Alpine region
Juan José Gómez-Navarro1,2,3, Christoph C. Raible1,2, Denica Bozhinova1,2, Olivia Martius2,4, Juan Andrés García-Valero3,5, and Juan Pedro Montávez3 1Climate and Environmental Physics, University of Bern, Bern, Switzerland
2Oeschger Centre for Climate Change Research, Bern, Switzerland
3Department of Physics, University of Murcia, Murcia, Spain
4Institute of Geography, University of Bern, Bern, Switzerland
5AEMET, Agencia Estatal de Meteorología, Spain
Abstract. Regional climate modelling is used to better capture the hydrological cycle, which is fundamental for climate impact investigations. However, the output of these models is affected by biases that hamper its direct use in impact modelling. Here, we present and evaluate the performance of two high-resolution (2 km) climate simulations of precipitation in the Alpine region and develop a new bias correction technique for precipitation suitable for complex topography. The latter is based on quantile mapping, which is applied separately across a number of non-overlapping regions defined through cluster analysis. This technique allows removing prominent biases while it aims at minimising disturbances to the physical consistency of the simulation.

The simulations span the period 1979–2005 and are carried out with the Weather Research and Forecasting model (WRF), driven by the reanalysis ERA-Interim (hereafter WRF-ERA), and the Community Earth System Model (hereafter WRF-CESM). The simulated precipitation is in both cases validated against observations. In a first step, Switzerland is classified into regions of similar temporal variability of precipitation. Similar spatial patterns emerge in all datasets, with a clear Northwest-Southeast separation following the main orographic features of this region. The daily evolution and the annual cycle of precipitation in WRF-ERA closely reproduces the observations. This is in contrast to WRF-CESM, which shows a different seasonality with peak precipitation in Winter and not in Summer as in the observations or in WRF-ERA. The application of the new bias correction technique minimises systematic biases in the WRF-CESM simulation, and substantially improves the seasonality, while the temporal and physical consistency among simulated variables is preserved.


Citation: Gómez-Navarro, J. J., Raible, C. C., Bozhinova, D., Martius, O., García-Valero, J. A., and Montávez, J. P.: A new region-aware bias correction method for simulated precipitation in the Alpine region, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2017-329, in review, 2018.
Juan José Gómez-Navarro et al.
Juan José Gómez-Navarro et al.
Juan José Gómez-Navarro et al.

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Short summary
We carry out and compare two high-resolution simulations of the Alpine region in the period 1979–2005. We aim to improve the understanding of the local mechanisms leading to extreme events in this complex region. We compare both simulations to precipitation observations to assess the model performance, and attribute major biases to either model or boundary conditions. Further, we develop a new bias correction technique to remove systematic errors in simulated precipitation for impact studies.
We carry out and compare two high-resolution simulations of the Alpine region in the period...
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