Analysis of agricultural land exposure to Compound Dry-Heat Events in Northeast China

Northeast China (NEC) In the context of global climate change, frequent Compound Dry-Heat Events (CDHEs) severely threaten the sustainable agricultural development of the NEC. This study investigates the spatiotemporal evolution of CDHEs and their impacts on agricultural land exposure. We used high-resolution gridded meteorological data (1960–2022) and remote sensing land-use data (1992–2022), constructed a Bivariate Dry-Heat Index (BDHI) by coupling SPI and STI, and employed Sen's slope, Mann-Kendall test, kernel density estimation, dynamic degree model, gridded exposure assessment, and wavelet analysis to quantify CDHEs’ spatiotemporal patterns, agricultural land changes, and exposure driving mechanisms. CDHEs in the NEC exhibited a significant intensification trend, with annual occurrence days increasing from 70 to approximately 180 days and high-value areas expanding spatially. Agricultural land exposure presented a first decreasing then increasing pattern, with hotspots centered on the Greater Khingan Range; the area of high-exposure zones in 2010–2022 was 2.3 times that in the 1990s. Climatic factors accounted for 98.8% of exposure changes, significantly more than land use (0.9%) and their interaction (0.3%). This study provides a new methodological framework for agricultural climate risk assessment and scientific support for regional food security and climate change adaptation management. • A novel index (BDHI) is developed to identify Compound Dry-Heat Events (CDHEs) in agricultural regions of Northeast China. • CDHEs have intensified since 2003–2007, with the annual number of days increasing from 70 to 180. • Agricultural exposure first declines then rises, with high-exposure areas expanding to 2.3 times their 1990s extent. • Climatic factors account for 98.8% of exposure changes, supporting food security strategies.