Comprehensive drought detection, spatiotemporal variations, and attribution across different agricultural climate zones in Eastern China using a copula-based drought index

The Agricultural Comprehensive Areas in Eastern China (ACAEC) are increasingly exposed to severe and frequent droughts under climate change and rising extremes, posing significant threats to agricultural production. However, there is a lack of comprehensive, large-scale drought assessments in the ACAEC, and the spatiotemporal evolution patterns and driving mechanisms remain unclear. This study proposes a novel framework that develops a Copula-based Multivariate Standardized Drought Index (MSDI) for 2001–2020, constructed from the Standardized Precipitation Index (SPI) and Standardized Soil Moisture Index (SSI) using precipitation data (station-scale, National Meteorological Information Center) and root-zone soil moisture (1 km, National Tibetan Plateau Data Center). Based on this index, we combined the Mann-Kendall and Sen’s slope tests, which quantify temporal trends, with a Center-of-Gravity model that traces spatial migration, thereby providing a complementary assessment of drought evolution across Northeastern China (NEC), Huang-Huai-Hai (HHH), the Middle and Lower Reaches of the Yangtze River (MLRYR), and Southern China (SC). Additionally, we employed XGBoost and SHAP to quantify the contributions of various drivers to MSDI in different climatic zones. Our findings reveal a general worsening of drought conditions across ACAEC, characterized by a southward shift and increasing frequency, intensity, and severity of short-term events. While NEC shows slight improvement, drought severity in other regions has intensified beyond the regional average. Attribution analysis highlights SOL and DTR as dominant drivers in NEC and HHH (35.5 % and 39.1 %, respectively), whereas RH, NDVI, and PET exert greater influence in MLRYR and SC (38.6 % and 50.0 %, respectively). Based on these mechanisms, we proposed region-specific drought mitigation strategies to enhance sustainable agriculture, food security, and disaster resilience in China.