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Wind direction‐dependent statistical downscaling of precipitation applied to the Upper Danube catchment
Author(s) -
Schipper Janus Willem,
Frueh Barbara,
Pfeiffer Andreas,
Zaengl Guenther
Publication year - 2011
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.2084
Subject(s) - downscaling , precipitation , climatology , environmental science , climate model , general circulation model , climate change , scale (ratio) , drainage basin , meteorology , geology , geography , oceanography , cartography
Simulating regional climate has become increasingly important during the last decade. Although general circulation models reproduce today's global‐scale climate reasonably well, regional and even local effects need to be simulated by regional‐scale climate models, which provide substantially higher resolutions. The study presented here was aimed at statistically downscaling precipitation simulations of a regional climate model onto a 1 km grid for hydrological modeling of a catchment of roughly 75,000 sq km. The area of interest is the upper Danube catchment, which is located in southern Germany and partly in Austria, Switzerland, and Italy (Alpine area). Simulating regional climate of such a large area (approx. 450 × 450 km) at this high resolution over many years is limited by the computer resources available. An approach to gain 1 km precipitation simulations over climatological periods of time is to apply a statistical downscaling method. The downscaling method applied was used in a regional climate model, which was in turn nested in a global circulation model. The time period for verification was 1991–2001. Two types of the same downscaling method based on the climatological relationship between the observed and simulated precipitation patterns are used. The first type is based on precipitation patterns only. The second type additionally uses the wind direction and wind speed dependence of precipitation patterns in the Alpine area. It will be shown that both downscaling types improve the simulation results significantly for the complete verification period. Although both types are limited by the performance of the course grid model output, the wind‐dependent type improves the results even more, especially on days with a distinct wind‐dependent precipitation pattern. Copyright © 2011 Royal Meteorological Society