Revisiting summertime hot extremes in China during 1961-2015: Overlooked compound extremes and significant changes

Summertime hot extremes in China are categorized into three distinct types, i.e., independent hot days, independent hot nights, and compound events, based on differing configurations between daily maximum and minimum temperature. Linear trends for multiple indictors of these subtypes and traditionally defined hot days/nights exhibited remarkable differences in significance, magnitude, and even sign, especially for events involving daytime extremes. Thus, some significant changes masked in conventional analyses are successfully uncovered. Particularly, the dominance of independent hot days has decayed significantly, accompanied by a rapid boom of compound events and/or independent hot nights in different regions. These nighttime-accentuated hot extremes have exhibited significant increases in duration, intensity, and spatial extent, with much stronger trends detected in severest events.