1961—2022年四川省区域性干旱过程识别及时空演变特征

Identification and Spatiotemporal Evolution Characteristics of Regional Drought Processes in Sichuan Province from 1961 to 2022

利用四川142个国家气象站1961—2022年逐日气温、降水资料,基于气象干旱综合指数(MCI)及其区域性干旱过程识别方法,分析四川区域性干旱时空变化特征。结果表明:(1)1961—2022年四川识别239次区域性干旱过程,平均3.9次/a,综合强度为较强等级以上占比49.4%;过程开始11月最多,9月最少;过程频次1960年代和1990年代偏少,1970年代、1980年代和21世纪以来相对偏多。(2)四川省区域性干旱过程的综合强度呈显著增强趋势,主要是过程影响范围增加趋势明显,平均每10 a增加3.7站,而过程强度和持续天数的变化趋势均不明显。(3)四川省各地干旱日数变化趋势各异,盆地及攀西地区干旱频发态势明显,常见4种区域干旱分型,分别是盆西南型、盆东北型、盆西北型和攀西型。(4)2022年四川省发生4次区域性干旱过程,过程频次接近常年水平,年度干旱综合评价为近10年来偏强。区域性干旱过程识别结果与业务实际和灾情验证比较吻合,综合强度指标对干旱事件的影响有一定表征能力,可本地化业务应用于四川区域性干旱过程监测评估。

Using the daily temperature and precipitation data from 142 national meteorological stations in Sichuan from 1961 to 2022,based on the Meteorological Drought Comprehensive Index(MCI)and its regional drought process identification method,the spatiotemporal variation characteristics of regional drought in Sichuan were analyzed.The results show that:(1)From 1961 to 2022,239 regional drought processes in Sichuan were identified,with an average of 3.9 times/a,and the comprehensive intensity above the strong level was 49.4%.The process started in November at most and September at least.The process frequency was relatively low in the 1960s and 1990s,and relatively high in the 1970s,1980s,and 21st century.(2)The comprehensive intensity of regional drought processes in Sichuan Province shows a significant increasing trend,mainly due to the significant increase in the scope of process impact,with an average increase of 3.7 stations every 10 years.However,the trend of changes in process intensity and duration days is not significant.(3)The trend of drought days varies across the Sichuan province,with frequent droughts occurring in the basin and Panxi region.There are four common regional drought types,which are southwest basin type,northeast basin type,northwest basin type,and Panxi basin type.(4)In 2022,four regional drought processes occurred in Sichuan Province,and the frequency was close to the annual level.The comprehensive evaluation of annual drought showed that it was relatively strong in the past 10 years.The identification results of regional drought processes are in good agreement with the business practice and disaster verification.The comprehensive intensity index has a certain characterization ability on the impact of drought events,and can be localized and applied to the monitoring and evaluation of regional drought processes in Sichuan.