Spatiotemporal variation and scenario projections of heat wave during 1961–2100 in the Loess Plateau

Understanding the spatiotemporal characteristics of heat wave (HW) is vital for both natural systems and human populations. The Loess Plateau is located in a climate transition zone and is highly sensitive to climate change. Therefore, it is crucial to study HW in this region. Based on instrumental measurements, climate model data, atmospheric circulation data and HW metrics, this study comprehensively analyses past and future HW changes in the Loess Plateau and the influencing factors. From 1961 to 2019, the metrics for daytime heat wave(DHW) and nighttime heat wave(NHW) were as follows: duration (9.28/9.72 days), frequency (1.34/1.4 times, mean intensity (6.24/4.69 °C), maximum intensity (7.83/6.05 °C), and cumulative heat (44.45/32.63 °Cd). All metrics displayed an increasing trend (p < 0.05(NHW)). Geographically, the northern Loess Plateau exhibited the highest intensity and cumulative heat, whereas the southern region experienced longer HW. The solar flux index, western Pacific subtropical high area index, and western Pacific subtropical high intensity index were identified as the primary factors influencing HW in the Loess Plateau. By the end of the 21st century, both the duration and cumulative heat of HW are projected to rise significantly. NHW, in particular, will see extended durations and greater cumulative heat compared to DHW.