Tensor Based Spatiotemporal Attribution of Compound Dry Heat Exposure in the Lanzhou–Xining Urban Agglomeration from 2000 to

Xiao Wang¹Ailin He¹Donghui Zhang²Senhao Liu³Zhijie Zhang⁴Siyuan Ren^5*

• ¹Sichuan Minzu College, Kangding, China
• ²China Academy of Space Technology, Beijing, China
• ³Chongqing University, Chongqing, China
• ⁴The University of Arizona, Tucson, United States
• ⁵University of Birmingham, Birmingham, United Kingdom

Compound dry–heat exposure is an increasingly dominant climate risk in arid and high-altitude urban regions, yet its spatiotemporal evolution and attribution mechanisms remain poorly understood. Focusing on the Lanzhou–Xining urban agglomeration from 2000 to 2025, this study develops a high-resolution analytical framework to disentangle the structural interplay between dry–heat forcing and population exposure. A three-dimensional temperature cube—comprising 305 monthly dry-bulb layers—encodes each pixel as a high-dimensional temporal vector, enabling fine-grained construction of three compound dry–heat indices (CDH1-3) that capture surface thermal intensity, radiative saturation, and hydrothermal imbalance. Six exposure metrics (EXP1-6) are derived to represent demographic, ecological, and infrastructural vulnerability dimensions. Using annual XGBoost models and SHAP analysis, we quantify the evolving contribution of each CDH driver to different exposure pathways. The results reveal four distinct coupling regimes: an early temperature-dominated phase (2000–2004), a radiative intensification period (2005–2011), a compound maturation stage (2012–2018), and a post-2019 fragmentation era marked by extreme attribution volatility and spatial heterogeneity. Notably, CDH3 emerges as a latent but volatile disruptor, This is a provisional file, not the final typeset article especially for soil-moisture-related exposure (EXP6), while CDH2 assumes a dominant and structurally embedded role in vegetation-constrained zones. Our findings highlight the asymmetric and threshold-sensitive nature of dry–heat exposure dynamics and emphasize the need for multidimensional adaptation strategies targeting radiative redistribution, evaporative buffering, and localized risk governance.