Characteristics of compound heat and drought events during the spring maize growing season in Northeast China Based on a novel daily-scale analysis framework

Study Region: The Northeast China (NEC) is located in the northeastern part of China (117.78 degrees E- 135.08 degrees E, 38.71 degrees N-53.55 degrees N). Study focus: To address the limitations in previous studies that could not monitor compound heat and drought events (CHDEs) at a daily-scale during crop growing seasons, we developed a daily- scale method for analyzing CHDEs. New hydrological insights for the region: We found: (1) CHDE frequency, duration, and severity were higher in the south and west of NEC, especially in the vegetative growth stage (VGS) compared to the reproductive stage (RGS). (2) Compared to 1961-1990, during 1991-2020, most stations showed more severe CHDEs during the EGS, VGS and RGS of spring maize. (3) Throughout the entire period (1961-2020) and the earlier period (1961-1990), drought-dominated CHDEs were more frequent during the EGS and VGS of spring maize. In the later period (1991-2020), heat- dominated CHDEs became more prevalent. For RGS, drought-dominated CHDEs were more likely in both the entire period and the later period, while heat-dominated CHDEs were more common during the earlier period. This research advances understanding of CHDEs in spring maize and offers a novel daily-scale framework for crop CHDE analysis.