Future changes in the frequency of extreme droughts over China based on two large ensemble simulations

Wei Li (1) , Rongyun Pan (2, 1) , Zhihong Jiang (3) , Yang Chen (4, 5) , Laurent Li (6) , Jing-Jia Luo (1) , Panmao Zhai (5) , Yuchen Shen (7) , Jinhua Yu (3)

1 NUIST - Nanjing University of Information Science and Technology
2 Shanghai Mental Health Center
3 KLME - NUIST - Key Laboratory of Meteorological Disaster [Nanjing University]
4 Southeast University [Jiangsu]
5 CAMS - Chinese Academy of Meteorological Sciences
6 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
7 JiangSu University

Future changes in the frequency of extreme drought events are of vital importance for risk assessment and relevant policy making. But a reliable estimation of their probability is intrinsically challenging due to limited available observations or simulations. Here, we use two large ensemble simulations, 50 members from CanESM2 and 40 members from CESM1 under the future RCP8.5 scenario, to elaborate a reliable projection of the 100-yr drought events (once in a century) under different warming levels. It is however necessary to first remove systematic biases for the simulated temperature and precipitation through a bias-correction method based on quantile mapping. Droughts are diagnosed with the standardized precipitation evapotranspiration index (SPEI), which considers both precipitation and potential evapotranspiration (PET, involving temperature). The results show that the frequency of extreme droughts increases with the continued global warming. Some differences between the two ensembles are also observed, especially for high warming levels. The Chinaaveraged probability of 100-yr droughts that occur once in a century in the current climate increase by a factor of 1.52 (1.44) and 1.90 (2.02) under 1.58C and 28C warming levels in CanESM2-LE (CESM1-LE), respectively. A simple statistical scheme shows that the increasing future risk of extreme droughts is mainly due to the increasing effect of PET on the occurrence of extreme drought events, while the effect of precipitation almost keeps constant with global warming.

Mots clés: Asia; Drought; Extreme events; Statistical techniques

Domaines: Météorologie

Wei Li, Rongyun Pan, Zhihong Jiang, Yang Chen, Laurent Li, et al.. Future changes in the frequency of extreme droughts over China based on two large ensemble simulations. Journal of Climate, 2021, pp.1. ⟨10.1175/jcli-d-20-0656.1⟩. ⟨hal-03288031⟩