Linying WANG and Xing YUAN

Key Laboratory of Regional Climate–Environment for Temperate East Asia,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

1.Introduction

The electronic supplementary material includes the correlation among hydrometeorological variables(Fig.S1),the sensitivity test for Type II flash drought frequency to precipitation and soil moisture thresholds used for the definition(Fig.S2),and the composite circulation pattern for heat extremes evolution(Fig.S3).

Fig.S1.Ensemble-mean correlation between(a)precipitation and soil moisture,(b)temperature and ET,(c)temperature and soil moisture,and(d)ET and soil moisture for 1979–2010.The ensemble means are the averages of the correlation from each reanalysis product.

Fig.S2.Ensemble-mean frequency (events per decade) for Type II flash drought with different thresholds for the definition.(a)T anomaly>one standard deviation,ET anomaly<0,and precipitation percentile(P%)<40%.(b–d)are the same as(a),but with P%<30%,soil moisture percentile(q(θ))<40%,or q(θ)<30%.The ensemble means are the averages of the frequency from each reanalysis product.

Fig.S3.The same as Fig.6,but for ensemble-mean composite circulation patterns before and after heat extremes over(a,b,c)southern China,(d,e,f)northern China.The black dots represent the regions with anomalies exceeding the 95%confidence level estimated by using bootstrapping 1000 times.