Heatwave magnitude quantization and impact factors analysis over the Tibetan Plateau

Abstract

More frequent and intense heatwave events (HWEs) on the Tibetan Plateau (TP) present substantial threats to the ecological and hydrological systems. However, understanding the changes in HWEs is limited, primarily from analyses at individual stations or single elements (glaciers, lakes). Here, using refined data, we quantify the heatwave magnitude by aggregating multiple indicators into a comprehensive index and explore the influence of environmental factors on the heatwave magnitude over the TP. Our findings indicate that the heatwave magnitude has significantly increased since the 21st century, especially in autumn. From 1979-2000 to 2000-2022, the heatwave magnitude hotspots migrated toward the northwestern TP, whereas the regions with the most rapid increase shifted in the opposite direction. During the inter-seasonal, from spring to winter, the migration direction of the heatwave magnitude hotspots changed from the northwest in the first 22 years (1979-2000) to the southeast in the recent 22 years (2001-2022). We also find that downwardshortwave radiation plays a significant role in the spatial heterogeneity of the heatwave magnitude, and the heatwave magnitude is also influenced by elevation and land cover. The elevation-dependence of the heatwave magnitude has become more pronounced in the recent 22 years, with a high heatwave magnitude migrating to the higher elevations. Furthermore, the increase in the heatwave magnitude is most rapid in water bodies during this period, which may impact the utilization of water resources. The findings of this study are essential for mitigating the disaster effects of HWEs.