A new region-aware bias-correction method for simulated precipitation in areas of complex orography
Regional climate modelling is used to simulate 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 two high-resolution (2 km) climate simulations...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/11/2231/2018/gmd-11-2231-2018.pdf |
| Summary: | Regional climate modelling is used to simulate 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 two high-resolution (2 km) climate
simulations of precipitation in the Alpine region, evaluate their performance
over Switzerland 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 the disturbances
to the physical consistency inherent in all statistical corrections of
simulated data. <br><br>
The simulations span the period 1979–2005 and are carried out with the
Weather Research and Forecasting model (WRF), driven by the ERA-Interim
reanalysis (hereafter WRF-ERA), and the Community Earth System Model
(hereafter WRF-CESM). The simulated precipitation is in both cases validated
against observations in Switzerland. In a first step, the area 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. Conversely, WRF-CESM 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 of simulated
precipitation is greatly preserved. |
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| ISSN: | 1991-959X 1991-9603 |