基于三维识别的温州市气象干旱事件演变特征分析OA

To overcome the limitations of previous analyses examining drought evolution from solely temporal or spatial perspectives and to better capture the complete developmental process of meteorological drought events,this study employs a three-dimensional(3D)drought identification method integrating spatiotemporal connectivity,based on the SPI-3,to systematically reveal the spatiotemporal dynamic evolution patterns of meteorological drought events in Wenzhou City,a pivotal coastal area in southeastern China.The methodology involves defining drought events as coherent spatiotemporal clusters where the SPI-3 is below the moderate drought threshold(-1),meticulously tracking their initiation,migration,expansion,contraction,and termination.The analysis utilizes high-quality monthly precipitation data(1961-2019)from 22 meteorological stations,spatially interpolated to a 1-km resolution grid,alongside SRTM DEM data for topographical context.The core 3D identification process comprises two key steps:first,identifying independent drought patches in each month by merging contiguous drought grids and applying an area threshold(≈1.6%of the study area,193.6 km²);second,temporally connecting patches across consecutive months based on spatial overlap exceeding this threshold,thereby constructing 3D drought structures characterized by duration,area,intensity(volume),and centroids.Results identify 131 distinct meteorological drought events in Wenzhou from 1961 to 2019.Temporally,overall trends in drought duration,area,and intensity show a fluctuating decline,with distinct phases:a significant decrease before 1995,an increase followed by a decrease between 1995 and 2005,and relatively stable duration/intensity but fluctuating area post-2005,indicating a shift towards more widespread but less intense/short-lived events.Seasonally,droughts exhibit high incidence in summer(27.53%)and autumn(26.96%),with October(13.7%)and July(13.0%)being the peak months.Spatially,drought centers are predominantly concentrated in inland areas farther from the coast,with Yongjia,Ouhai,Ruian,and Pingyang districts experiencing particularly long-duration and high-intensity events,highlighting a clear correlation with topography and land-sea position.Analysis of the ten most severe events and detailed 3D case studies demonstrates that the reconstructed spatiotemporal evolution—including development paths,changing spatial footprints,and centroid migration—aligns remarkably well with historical drought records from Wenzhou.This consistency robustly validates the reliability and practical utility of the proposed SPI-based 3D identification method.Consequently,this study not only provides novel insights into the intricate spatiotemporal dynamics of droughts in a complex coastal environment but also offers a refined methodological framework for improved regional drought monitoring,dynamic tracking,and early warning.The findings furnish a detailed scientific basis for formulating targeted drought risk prevention,control strategies,and resilience enhancement in Wenzhou and similar monsoonal coastal regions.