Joint probability analysis of precipitation extremes in China under the changing climate

Different precipitation extreme indices represent various aspects of extreme events, such as total amount and intensity. The changes in joint probabilities of different combinations of extreme precipitation indices, such as extreme precipitation amount, intensity, fractional contribution to annual precipitation days, and consecutive wet periods, are analyzed. The daily precipitation outputs from CMIP5 Earth System Models are statistically downscaled to the site scale. The joint probability distributions of the site-scale extreme indices are constructed based on Copula. Results show that the joint probability behaviors of extremes change are projected to change considerably in the future scenarios. The co-occurrences of consecutive wet and dry days are expected to decrease. The joint extreme heavy precipitation events with large total amount and high intensity are expected to increase, indicating higher risk of floods in China. Furthermore, North China may face higher risk of co-occurrence of severe floods and droughts in the same year. The changes in joint probabilities of precipitation extremes are projected to be more considerable even under RCP2.6, a low-emission future scenario. The joint probability distribution shift can be explained by the changes in marginal distributions and bivariate relationships between extreme indices.