PUBLICATIONS Journal of Geophysical Research: Atmospheres RESEARCH ARTICLE A new dynamical downscaling approach with GCM 10.1002/2014JD022958 bias corrections and spectral nudging Key Points: Zhongfeng Xu1 and Zong-Liang Yang2,3 • Both GCM and RCM biases should be constrained in regional climate 1RCE-TEA and Young Scientist Laboratory, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, projection 2 3 • The NDD approach significantly RCE-TEA, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, Department of Geological improves the downscaled climate Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA • NDD is designed for regional climate projection at various time scales Abstract To improve confidence in regional projections of future climate, a new dynamical downscaling Supporting Information: (NDD) approach with both general circulation model (GCM) bias corrections and spectral nudging is developed • Figures S1–S4 and assessed over North America. GCM biases are corrected by adjusting GCM climatological means and • Figure S1 variances based on reanalysis data before the GCM output is used to drive a regional climate model (RCM). • Figure S2 • Figure S3 Spectral nudging is also applied to constrain RCM-based biases. Three sets of RCM experiments are integrated • Figure S4 over a 31 year period. In the first set of experiments, the model configurations are identical except that the initial and lateral boundary conditions are derived from either the original GCM output, the bias-corrected GCM output, Correspondence to: orthereanalysisdata.Thesecondset of experiments is the same as the first set except spectral nudging is applied. Z.-L. Yang,
[email protected] The third set of experiments includes two sensitivity runs with both GCM bias corrections and nudging where the nudging strength is progressively reduced.