河北省春季潜在蒸散量变化特征与成因

潜在蒸散量（ET₀）是区域能量平衡和水分平衡的重要组成部分，通过探讨其历史演化规律及成因对优化调整农业生产结构及水资源合理配置至关重要。基于河北省及周边地区1968—2018年24个典型气象站点逐日气象数据，利用Penman-Monteith模型、敏感性分析、M-K检验法及空间插值方法分析了河北省ET₀时空分布特征及其影响因素。结果表明:（1）从时间分布来看，51年间，河北省春季ET₀多年均值为353.20 mm，呈下降趋势，下降幅度为-1.679 mm/10 a，其周期变化存在35年主周期及20年次周期；空间上呈现由西北向东南半环状递减趋势。（2）从影响因素来看，春季ET₀变化对平均气温、最高气温、最低气温、日照时数和平均风速均表现正敏感；对相对湿度表现为负敏感，对各个气象因子敏感程度依次为相对湿度 > 最高气温 > 日照时数 > 平均风速 > 平均气温 > 最低气温。（3）从成因的空间分布上看，河北省北部地区ET₀变化的主导气候影响因子为平均气温，中部及西部地区为相对湿度，南部及偏东部地区则转变为平均风速。研究成果可为研究区水资源综合评价及农业生产工作提供一定参考。

Characteristics and Causes of Potential Evapotranspiration in Spring in Hebei Province

Potential evapotranspiration (ET₀) is an important part of regional energy balance and water balance. It is very important to optimize and adjust agricultural production structure and rational allocation of water resources by discussing its historical evolution rules and causes. Based on the daily meteorological data of 24 typical meteorological stations in Hebei Province from 1968 to 2018, the spatial and temporal distribution of ET₀ in Hebei Province and its influencing factors were analyzed by using Penman-Monteith model, sensitivity analysis, M-K test method and spatial interpolation method. The results are as follows. (1) From the point of time distribution, the annual mean value of ET₀ in spring in Hebei Province is 353.20 mm in 51 years, with a decreasing trend of -1.679 mm/decade, and its periodic variation has 35-year main cycle and 20-year cycle; The changes of ET₀ in spring are positively sensitive to mean air temperature, maximum temperature, minimum temperature, sunshine duration and mean wind speed from the northwest to the southeast. (2) In terms of influencing factors, the variation of ET₀ in spring is positively sensitive to the mean temperature, the maximum temperature, the lowest temperature, the sunshine duration and the average wind speed. The sensitivity to the relative humidity is negative, and the sensitivity to various meteorological factors follows the order:relative humidity > maximum temperature > unshine hours > mean wind speed > mean temperature > minimum temperature. (3) From the spatial distribution of the causes, the dominant climatic factors of ET₀ change in northern Hebei Province are mean temperature, relative humidity in central and western regions, and mean wind speed in southern and eastern regions. The research results can provide scientific guidance for the comprehensive evaluation of water resources and the actual agricultural production.