Spatiotemporal characteristics of regional high temperature processes in Shaanxi Province from 1971 to 2024

Based on the daily maximum temperature data from 95 national meteorological stations of Shaanxi Province from 1971 to 2024, the regional high temperature process (RHTP) in Shaanxi Province is identified objectively, following the operational method adopted by the Shaanxi Climate Center. Subsequently, the spatiotemporal characteristics are investigated by using methods such as linear trend estimation, correlation coefficients, moving averages, and the Mann-Kendall test. The following conclusions are drawn: high temperature events in Shaanxi Province are primarily concentrated in the central-eastern Guanzhong Plain and the Ankang River Valley of southern Shaanxi. Both the frequency and strength of high temperature events in Shaanxi Province are generally higher in the south and east and lower in the north and west. The RHTP occur with an annual average frequency of four times, predominantly between mid-June and mid-August. For each process, the mean duration reaches 4 days, and the average intensity typically ranges between 36 ℃ and 37 ℃. Against the backdrop of global climate warming, both the frequency and strength of high temperature events in Shaanxi Province have increased over the past 54 years. The RHTP in Shaanxi Province have exhibited pronounced climate change characteristics during this period. These include increased frequency, enhanced intensity, prolonged duration, expanded spatial coverage, advanced onset, delayed termination, and strengthened comprehensive intensity. These changing characteristics initially emerged in the late 1990s and have become particularly pronounced since the beginning of the 21st century.