Quantile delta-mapped spatial disaggregation analysis for summertime compound extremes over China

The compound extremes have received a widespread attention. A quantile delta-mapped spatial disaggregation (QDMSD) method has been developed to analyze summertime compound dry-warm (CDDW) and wet-warm (CDWW) extremes in historical (1980–2014) and future (2030–2099). The evaluation results show that QDMSD has an improvement in reproducing precipitation relative to the bias correction and spatial disaggregation (BCSD) model. QDMSD could also reasonably reproduce the mean temperature and precipitation in sub-regions of China at monthly and interannual scales. The downscaled results indicate that the projected changes in two parameters (i.e., occurrence frequency and averaged duration) would increase under SSP5-8.5. CDDW is projected to occur in northwest and central China under SSP2-4.5, while it would expand to eastern China under SSP5-8.5. Projected CDWW events will occur frequently in southwestern, northeastern, central, and eastern China under SSP5-8.5. Under SSP5-8.5, the annual increase in the averaged duration of CDDW could reach 4 days/event, with an annual increment of 1.2 event in frequency. For CDWW, the annual increment in averaged duration could reach 0.4 day/event, with an annual increment of 0.1 event in frequency. The factorial analysis results imply that GCMs are the primary source for the uncertainty of projections in the 2050s (i.e., 2030–2064). In the 2080s (i.e., 2065–2099), the emission scenarios are the major uncertain factor for CDDW. For CDWW, the GCMs are the dominant factor. These findings could support policy-making to address potential risks from compound extremes across multiple sectors (e.g., agriculture, industry and food security).