长江流域高温事件识别中两类阈值方法对比研究OA

Against the backdrop of global climate change,the frequent occurrence of extreme high-temperature events has ex-acerbated the water resource supply-demand imbalance in the Changjiang River Basin.To objectively characterize the spatiotem-poral distribution and evolutionary trends of high-temperature events in the Changjiang River Basin,this study utilized daily max-imum temperature data from 735 national meteorological stations within the basin from 1961 to 2022.Regional high-temperature events during the warm season in the upper and middle-lower reaches of the Changjiang River were identified using both abso-lute and relative threshold approaches.A comparative analysis of the applicability and sensitivity of these two approaches was per-formed from multiple perspectives,including occurrence frequency,spatiotemporal distribution,and comprehensive intensity.The results indicate that:① The absolute threshold approach identified 299 and 383 high-temperature events in the upper and mid-dle-lower reaches of the Changjiang River,respectively,whereas the relative threshold approach identified 423 and 410 events.The relative threshold approach was more sensitive to high-temperature events in the upper reaches of the Changjiang River.②Events identified by the absolute threshold approach were concentrated in July and August,whereas those identified by the relative threshold approach were more evenly distributed from May to September.The absolute threshold approach was more responsive to periods of extreme high temperature.③ The duration of events identified by the absolute threshold approach ranged from 7.1 to 8.7 days,compared with an average of 5.4 days for events identified by the relative threshold approach.The absolute threshold approach enabled more stable identification of the duration of high-temperature events.④ The consistency rate of typical high-temperature years identified by the two approaches reaches 60%.Both approaches indicated that the frequency and intensity of re-gional high-temperature events have exhibited a significantly increasing trend over the past 60 years.The extremity of high-temperature events has increased notably since the 21st century.The relative threshold approach is more sensitive to climate change,whereas the absolute threshold approach is superior in characterizing high-intensity extreme high-temperature events.The research findings can provide a scientific reference for research and adaptive responses to high-temperature events in river basins.