THE RELATIONSHIP OF DROUGHT FREQUENCY AND DURATION TO TIME SCALES
THE RELATIONSHIP OF DROUGHT FREQUENCY AND DURATION TO TIME SCALES
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发表时间：
1993
期刊：
影响因子：
6.7
通讯作者：
T. Mckee;N. Doesken;J. Kleist
中科院分区：
文献类型：
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作者：
T. Mckee;N. Doesken;J. Kleist
1.0导言五个实际问题成为重要的任何分析干旱。其中包括：1）时间尺度，2）概率，3）降水量不足，4）定义对降水量和五个供水变量的应用，以及5）定义与干旱影响的关系。干旱的频率、持续时间和强度都成为依赖于隐含或明确建立的时间尺度的函数。我们在为科罗拉多的决策者提供干旱信息方面的经验是，他们需要以概率、缺水和供水量占平均值的百分比表示的当前条件，并使用最近的气候历史（过去30到100年）作为比较的基础。目前还没有一种单一的干旱定义或分析方法能够很好地解决所有这些问题。在过去使用的各种定义和干旱监测方法中，迄今为止在美国使用最广泛的是帕尔默干旱指数（Palmer，1965年），但它的弱点（Alley，1984年）常常限制了它的明智应用。例如，帕尔默指数没有定义时间尺度，但确实固有地存在。干旱的定义一直是干旱监测和分析的绊脚石。Wilhite和Glantz（1985年）完成了对几十种干旱定义的彻底审查，并确定了六个总的类别：气象、气候、大气、农业、水文和水管理。Dracup等人（1980年）也审查了定义。所有观点似乎都同意，干旱是一段时间内降水不足造成的水分不足的状况。困难主要涉及短缺累积的时间段，以及降水量短缺与可用水源短缺的关系和随之而来的影响。
1.0 INTRODUCTION Five practical issues become important in any analysis of drought. These include: 1) time scale, 2) probability, 3) precipitation deficit, 4) application of the definition to precipitation and to the five water supply variables, and 5) the relationship of the definition to the impacts of drought. Frequency, duration and intensity of drought all become functions that depend on the implicitly or explicitly established time scales. Our experience in providing drought information to a collection of decision makers in Colorado is that they have a need for current conditions expressed in terms of probability, water deficit, and water supply as a percent of average using recent climatic history (the last 30 to 100 years) as the basis for comparison. No single drought definition or analysis method has emerged that addresses all these issues well. Of the variety of definitions and drought monitoring methods used in the past, by far the most widely used in the United States is the Palmer Drought Index (Palmer, 1965), but its weaknesses (Alley, 1984) frequently limit its wise application. For example, time scale is not defined for the Palmer Index but does inherently exist. The definition of drought has continually been a stumbling block for drought monitoring and analysis. Wilhite and Glantz (1985) completed a thorough review of dozens of drought definitions and identified six overall categories: meteorological, climatological, atmospheric, agricultural, hydrologic and water management. Dracup et al. (1980) also reviewed definitions. All points of view seem to agree that drought is a condition of insufficient moisture caused by a deficit in precipitation over some time period. Difficulties are primarily related to the time period over which deficits accumulate and to the connection of the deficit in precipitation to deficits in usable water sources and the impacts that ensue.