Dynamical downscaling of surface air temperature and precipitation using RegCM4 and WRF over China
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Dynamical downscaling of surface air temperature and precipitation using RegCM4 and WRF over China Shibo Gao1 Received: 23 February 2020 / Accepted: 2 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Two long continuous regional climate simulations over China have been carried out using the Regional Climate Model version 4 (RegCM4) and Weather Research and Forecasting model (WRF). The Simulations are forced by NCEP Reanalysis II data with a horizontal grid spacing of 30 km during 1981–2010. It is demonstrated that the RegCM4 and WRF had pronounced temperature and precipitation downscaling ability, producing more regional details and smaller biases than the driving R2. Overall, WRF tended to better capture the temperature and precipitation pattern and magnitude, daily temperature frequency, the monsoon rain belt movement, and seasonal precipitation variations over most wet regions, while larger deficits than RegCM4 were shown over some dry regions. The extreme precipitation indices of the two RCMs were quite different, with strong regional and seasonal dependence. WRF was better at simulating the annual mean temperature and precipitation trends, with higher spatial pattern correlations. The optimal ensemble approach combining the advantages of RegCM4 and WRF showed improved simulation compared to the individual models. The optimal ensemble reduced the annual temperature biases from the two models by 15–30%, and increased the precipitation spatial pattern correlations by 0.08–0.13. Further works are needed to improve the performances of the ensemble approach by using more RCMs. Keywords Dynamical downscaling · RCMs · Surface air temperature · Precipitation · Optimal ensemble approach
1 Introduction Climate models have proven to be effective tools for investigating the climate system and climate change. Over recent years, the Coupled Model Inter-comparison Project 5 (CMIP5) has developed a large number of climate simulations from global climate models (GCMs) (Taylor et al. 2012). Although these GCMs can capture the main largescale circulation characteristics, studies into their application to regional climate simulations are limited because their resolutions are 100–300 km, which is too coarse to obtain useful information on climate features at a regional scale (Oreskes et al. 2010; Kitoh et al. 2013). Furthermore,
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05326-y) contains supplementary material, which is available to authorized users. * Shibo Gao [email protected] 1
Department of Atmospheric Sciences, Agronomy College, Shenyang Agricultural University, Shenyang 110866, China
physical processes are not accurately resolved at these resolutions, which poses additional disadvantages for accurately representing regional climates (Gao et al. 2015). China is characterized by unique topography, landscapes and monsoon climates, with Tibetan Plateau in the west, the western Pacific Ocean in the east, and complex coastlin
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