浙江省极端降水时空分布及其城市化效应特征研究OA

Against the backdrop of global climate change,extreme precipitation events have become increas-ingly frequent and intense,posing severe challenges to regional water security,ecological stability,and socio-economic development worldwide.Accelerated global warming has intensified the hydrological cycle,shorten-ing the recurrence period of extreme precipitation and increasing its intensity by 10%-20%,with China showing a polarized"southward increase and northward decrease"pattern.As a typical subtropical monsoon region on China's southeast coast,Zhejiang Province is highly vulnerable to extreme precipitation due to the combined ef-fects of atmospheric circulation,complex hilly topography,and rapid urbanization,making it a key area for study-ing regional extreme climate dynamics.However,existing studies on extreme precipitation in the region often focus on single-dimensional characteristics such as intensity or frequency and rely on static urban-suburban classi-fications to assess urbanization impacts,failing to fully capture the synergistic evolution of multi-dimensional fea-tures or precipitation's dynamic responses to urban expansion.To address this,this study systematically analyzed the spatiotemporal patterns,trend characteristics,and urbanization effects of extreme precipitation in Zhejiang Province from 1960 to 2020 using daily precipitation data from 67 national meteorological stations.It selected 12 extreme precipitation indices recommended by the Expert Team on Climate Change Detection and Indices,covering three dimensions:intensity,frequency,and persistence.Trend analyses were conducted using three com-plementary methods:Mann-Kendall,PreWhitening Mann-Kendall(to eliminate autocorrelation),and Extreme-Point Symmetric Mode Decomposition(to extract long-term trends).To more accurately quantify urbanization impacts,41 stations that transitioned from suburban to urban areas between 1990 and 2020 were dynamically classified based on 30m-resolution land cover data,with their precipitation trends compared before and after ur-banization to isolate natural variability.The results showed:①Over 61 years,11 of the 12 indices trended up-ward,with only consecutive dry days decreasing.Total precipitation,extreme precipitation above the 95th per-centile,and extreme heavy precipitation above the 99th percentile increased significantly by 3.93 mm/year,3.58 mm/year,and 2.06 mm/year respectively,indicating a surge in cumulative high-intensity rainfall.Consecu-tive wet days increased by 0.02 days/year,while consecutive dry days decreased by 0.09 days/year,reflecting en-hanced precipitation continuity.②Spatially,extreme precipitation showed a"less in the north,more in the south"pattern,with marked differences between coastal and mountainous areas.High-value zones for intensity indices(e.g.,maximum 1-day precipitation exceeding 117 mm,extreme precipitation above the 95th percentile exceeding 852 mm)concentrated in typhoon-influenced southeastern coastal regions and western mountainous areas affected by orographic lifting.③Trend tests revealed that Extreme-Point Symmetric Mode Decomposition effectively captured long-term trends,while PreWhitening Mann-Kendall improved assessment objectivity by re-ducing autocorrelation.However,combining the two risked local trend reversals,requiring method-specific inter-pretation.Most indices showed significant trends at specific stations,with fewer dry days,more wet days,and generally rising frequency,intensity,and total volume of moderate-to-high intensity precipitation.④Urbaniza-tion significantly amplified precipitation amount and intensity:its contribution rates to days with daily precipita-tion≥50 mm and extreme heavy precipitation above the 99th percentile reached 111.9%and 182.7%respective-ly,with post-1990 trends of these indices shifting from decreasing to increasing,directly reflecting the growing impact of urban expansion.This study's innovations include:integrating intensity-frequency-persistence dimen-sions to reveal the synergistic evolution of extreme precipitation;comparing multi-method trend tests to clarify their applicability and limitations;using dynamically transitioning urban-suburban stations to quantify urbaniza-tion impacts,avoiding biases from static classifications.The findings enhance understanding of regional extreme precipitation dynamics under climate change and urbanization,providing critical scientific support for flood disas-ter mitigation,urban planning optimization,and ecological hydrological regulation in Zhejiang Province and simi-lar monsoon-influenced coastal regions.