Journal of Arid Meteorology ›› 2025, Vol. 43 ›› Issue (1): 1-10.DOI: 10.11755/j.issn.1006-7639-2025-01-0001

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A meteorological drought index based on cumulative precipitation and cumulative evaporation

PAN Yongdi1,2(), XIAO Jingjing3(), PAN Yanhua4, SHI Jie5   

  1. 1. Wenzhou Meteorological Bureau of Zhejiang Province,Wenzhou 325027,Zhejiang,China
    2. Wenzhou Key Laboratory of Typhoon Observations & Forecasting,Wenzhou 325027,Zhejiang,China
    3. Zhejiang Climate Center,Hangzhou 310052,China
    4. Wencheng Meteorological Bureau of Zhejiang Province,Wencheng 325300,Zhejiang,China
    5. Dingxi Agricultural Testing Station,Dingxi 743000,Gansu,China
  • Received:2024-06-07 Revised:2024-07-23 Online:2025-02-28 Published:2025-03-14

一种基于累积降水与累积蒸发的气象干旱指数

潘永地1,2(), 肖晶晶3(), 潘彦华4, 石界5   

  1. 1.浙江省温州市气象局,浙江 温州 325027
    2.温州市台风监测预报技术重点实验室,浙江 温州 325027
    3.浙江省气候中心,浙江 杭州 310052
    4.浙江省文成县气象局,浙江 文成 325300
    5.甘肃省定西市农试站,甘肃 定西 743000
  • 通讯作者: 肖晶晶(1984—),男,主要从事作物气象及干旱风险研究。E-mail:xiojingjing2005@163.com。
  • 作者简介:潘永地(1971—),男,正高级工程师,硕士,主要从事农业气象方面研究。E-mail:648679519@qq.com
  • 基金资助:
    浙江省基础公益计划项目(LGF22D050007);浙江省气象局重点项目(2022ZD07)

Abstract:

To overcome the limitation of traditional meteorological drought indices, which rely on historical climatic probability data of the same period for calculation, this paper establishes a meteorological drought index that can reflect the degree of soil drought but only requires current precipitation and evaporation data. Based on the soil water balance equation and in conjunction with the standard classification of soil drought levels, this study utilizes the relationship between the evaporation intensity of the dry soil surface layer and the water surface, along with soil evaporation calculation methods, to derive the expressions of the critical lines representing various drought levels within the cumulative precipitation-cumulative evaporation coordinate system. The four derived expressions of critical lines correspond to four drought grades, namely, mild drought, moderate drought, severe drought, and extreme drought, respectively. Through a forward daily rolling calculation, the point where the cumulative precipitation and cumulative evaporation coordinates are farthest from their respective critical line is identified as the maximum distance point for that critical line. The drought level is determined by the coordinate point that is located in the highest drought level region and has the maximum distance from the nearest lower critical line. The drought index is then constructed based on the distances from this coordinate point to each critical line. The drought index established in this study reflects the level of soil drought. The drought index calculated using the soil drought level distance index model presented in this paper is compared with soil moisture measurement data and drought disaster records. The results indicate that the variations in the drought index presented in this paper exhibit a high negative correlation with changes in soil moisture and a strong consistency with actual drought impacts. The drought index proposed in this study possesses advantages such as clear physical meaning, convenient calculation, and short response time scale, making it of great significance for practical drought monitoring operations.

Key words: accumulated precipitation, accumulated evaporation, meteorology, drought index

摘要:

为了克服传统气象干旱指数在计算时依赖历史同期气候概率数据的不足,本文建立了能够反映土壤干旱程度但只需当期降水量、蒸发量资料的气象干旱指数。根据土壤水分平衡方程,结合土壤干旱等级,利用干土层表土蒸发强度与水面蒸发强度关系和土壤蒸发计算方法,推导出在累积降水量-累积蒸发量坐标系中的各干旱等级临界线表达式,4条临界线表达式分别对应轻旱、中旱、重旱、特旱4个干旱等级。通过前向逐日滚动计算,将累积降水量、累积蒸发量构成的坐标点到相应临界线距离最大的点作为该临界线的最大距离点,在各临界线最大距离点中以位于最高干旱等级区且离下方最近临界线距离最大的坐标点确定干旱等级,由该坐标点到各临界线的距离构造土壤干旱等级距离指数,反映土壤干旱等级。将土壤干旱等级距离指数与土壤水分测量数据和干旱灾情记录进行比较,发现该指数变化与土壤水分变化高度负相关,与实际干旱影响有很高的一致性。土壤干旱等级距离指数具有物理意义明确、计算方便、时间尺度短等优点,对干旱监控实际业务具有重要意义。

关键词: 累积降水量, 累积蒸发量, 气象, 干旱指数

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