Bias correction of temperature and precipitation over China for RCM simulations using the QM and QDM methods
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Bias correction of temperature and precipitation over China for RCM simulations using the QM and QDM methods Yao Tong1,2,3 · Xuejie Gao1,2 · Zhenyu Han4 · Yaqi Xu3 · Ying Xu4 · Filippo Giorgi5 Received: 4 March 2020 / Accepted: 26 August 2020 © The Author(s) 2020
Abstract Two different bias correction methods, the quantile mapping (QM) and quantile delta mapping (QDM), are applied to simulated daily temperature and precipitation over China from a set of 21st century regional climate model (the ICTP RegCM4) projections. The RegCM4 is driven by five different general circulation models (GCMs) under the representative concentration pathway RCP4.5 at a grid spacing of 25 km using the CORDEX East Asia domain. The focus is on mean temperature and precipitation in December–January–February (DJF) and June–July–August (JJA). The impacts of the two methods on the present day biases and future change signals are investigated. Results show that both the QM and QDM methods are effective in removing the systematic model biases during the validation period. For the future changes, the QDM preserves the temperature change signals well, in both magnitude and spatial distribution, while the QM artificially modifies the change signal by decreasing the warming and modifying the patterns of change. For precipitation, both methods preserve the change signals well but they produce greater magnitude of the projected increase, especially the QDM. We also show that the effects of bias correction are variable- and season-dependent. Our results show that different bias correction methods can affect in different way the simulated change signals, and therefore care has to be taken in carrying out the bias correction process. Keywords Regional climate model · Bias correction · Quantile delta mapping · China
1 Introduction While general circulation models (GCMs) produce important climate change information on the global scale, they are still characterized by an excessively coarse resolution to provide information for impact studies. Regional climate models (RCMs) with higher horizontal resolution have been widely used in recent decades (Giorgi 2019) to downscale GCM simulations and provide fine scale regional climate information. They can be especially useful for the East Asia * Xuejie Gao [email protected] 1
Climate Change Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
2
University of Chinese Academy of Sciences, Beijing, China
3
Yingkou Meteorological Bureau, Yingkou, China
4
National Climate Center, China Meteorological Administration, Beijing, China
5
The Abdus Salam International Center for Theoretical Physics, Trieste, Italy
region, whose climate is dominated by the East Asia monsoon and is characterized by a large diversity both in space and time. As reported in previous studies, high resolution RCM simulations show better performance in reproducing present day climate over China, and particularly the development of the East Asia monsoon (Gao et al. 2006). In addi
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