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Vine Copula Ensemble Downscaling for Precipitation Projection Over the Loess Plateau Based on High‐Resolution Multi‐RCM Outputs
Author(s) -
Sun Chaoxing,
Huang Guohe,
Fan Yurui,
Zhou Xiong,
Lu Chen,
Wang Xiuquan
Publication year - 2021
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2020wr027698
Subject(s) - downscaling , loess plateau , copula (linguistics) , precipitation , climatology , environmental science , climate model , vine copula , geology , climate change , meteorology , mathematics , soil science , econometrics , geography , oceanography
A vine copula‐based ensemble downscaling (VCED) framework is proposed to jointly downscale the projected precipitation from multiple regional climate models (RCMs). This approach can effectively reduce the biases inherent to precipitation projections from different RCMs and thus provide more reliable ensemble projections. The proposed approach was applied to RCM projections over the Loess Plateau of China, which features complex topography and various climatic zones. Precipitation projections from 7 RCMs were used, and 21 sets of downscaling results were obtained. The performance of the VCED in reproducing historical precipitation across the Loess Plateau was evaluated using mean absolute error (MAE), the Taylor diagram, and the rank histogram (RH). The proposed VCED approach was found to be more effective than quantile mapping and bivariate copula methods in achieving robust precipitation projections. Overall flat RH diagrams indicate that the ensemble prediction and observations have strong consistency in distribution. Future precipitation changes of two 30‐year periods (i.e., the 2050s and 2080s) under two Representative Concentration Pathway (RCP) scenarios (RCP 4.5 and RCP 8.5) over the Loess Plateau were then analyzed after postdownscaling processes. The results show that the average annual precipitation over the Loess Plateau may increase by 8.4%–11.4% under the RCP 4.5 scenario and by 9.3%–17.5% under RCP 8.5. The projected precipitation in the south‐central parts of the Loess Plateau would be significantly reduced whereas those of the other parts be significantly increased.