The Relationship of Drought Frequency and Duration to Time Scales. Mckee, T. B., Doesken, N. J., & Kleist, J. ![The Relationship of Drought Frequency and Duration to Time Scales [link]](https://bibbase.org/img/filetypes/link.svg "link")
Paper abstract bibtex [Excerpt: Introduction] 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. [\n] Usable water sources include soil moisture, ground water, snowpack, streamflow and reservoir storage. Any impacts of drought associated with water demand exceeding water supply originate with one or more of these five usable supplies. The time period from the arrival of precipitation until water is available in each useable form differs greatly. Water uses also have characteristic time scales. Consequently, the impacts of a water deficit are a complex function of water source and water use. The time scale over which precipitation deficits accumulate becomes extremely important and functionally separates different types of drought. Agricultural (soil moisture) droughts, for example, typically have a much shorter time scale than hydrologic (groundwater, streamflow and reservoir) droughts. [\n] Many examples are available where quantitative links have been established between precipitation deficits and drought impacts in particular water use areas. These use-specific relationships will likely continue to be expanded to assist in crop yield predictions, hydroelectric power projections and in many other drought-sensitive fields. However, the importance of monitoring and assessing water supply from a general climate perspective beginning with precipitation has not diminished. [\n] 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. [...] [\n] The purpose of the following discussion is to propose an indicator and definition of drought which could serve as a versatile tool in drought monitoring and analysis. This indicator requires only one input variable, could be applied in a similar way to precipitation, snowpack, streamflow, reservoir storage, soil moisture, and ground water, recognizes a variety of time scales, and provides information on precipitation deficit, percent of average and probability. [A functional definition of drought] [\n] [...] The Standardized Precipitation Index (SPI) is calculated in the following sequence. [::] A monthly precipitation data set is prepared for a period of m months, ideally a continuous period of at least 30 years. [::] A set of averaging periods are selected to determine a set of time scales of period j months where j is 3, 6, 12, 24, or 48 months. These represent arbitrary but typical time scales for precipitation deficits to affect the five types of usable water sources. The data set is moving in the sense that each month a new value is determined from the previous j months. [::] Each of the data sets are fitted to the Gamma function to define the relationship of probability to precipitation. [::] Once the relationship of probability to precipitation is established from the historic records, the probability of any observed precipitation data point is calculated and used along with an estimate of the inverse normal to calculate the precipitation deviation for a normally distributed probability density with a mean of zero and standard deviation of unity. This value is the SPI for the particular precipitation data point. [\n] [...] [Summary] A new definition of drought has been proposed which explicitly specifies time scales and utilizes a standardized precipitation index. Drought frequency decreases inversely and duration increases linearly with time scale. Frequency and duration of random climate and actual climate are very similar. The new definition allows a consistent set of information to be calculated including drought beginning, ending, intensity, and magnitude. It also produces monitoring information of index values, probability, percent of average, and precipitation deficit during drought. Beginning in the fall of 1992, the SPI will be used as an experimental drought monitoring tool in Colorado. Operational evaluations will then be performed as experience is gained relating SPI values to actual impacts.
@article{mckeeRelationshipDroughtFrequency1993,
title = {The Relationship of Drought Frequency and Duration to Time Scales},
author = {Mckee, Thomas B. and Doesken, Nolan J. and Kleist, John},
date = {1993-01},
url = {http://mfkp.org/INRMM/article/14027580},
abstract = {[Excerpt: Introduction] 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.
[\textbackslash n] Usable water sources include soil moisture, ground water, snowpack, streamflow and reservoir storage. Any impacts of drought associated with water demand exceeding water supply originate with one or more of these five usable supplies. The time period from the arrival of precipitation until water is available in each useable form differs greatly. Water uses also have characteristic time scales. Consequently, the impacts of a water deficit are a complex function of water source and water use. The time scale over which precipitation deficits accumulate becomes extremely important and functionally separates different types of drought. Agricultural (soil moisture) droughts, for example, typically have a much shorter time scale than hydrologic (groundwater, streamflow and reservoir) droughts.
[\textbackslash n] Many examples are available where quantitative links have been established between precipitation deficits and drought impacts in particular water use areas. These use-specific relationships will likely continue to be expanded to assist in crop yield predictions, hydroelectric power projections and in many other drought-sensitive fields. However, the importance of monitoring and assessing water supply from a general climate perspective beginning with precipitation has not diminished.
[\textbackslash n] 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. [...]
[\textbackslash n] The purpose of the following discussion is to propose an indicator and definition of drought which could serve as a versatile tool in drought monitoring and analysis. This indicator requires only one input variable, could be applied in a similar way to precipitation, snowpack, streamflow, reservoir storage, soil moisture, and ground water, recognizes a variety of time scales, and provides information on precipitation deficit, percent of average and probability.
[A functional definition of drought]
[\textbackslash n] [...]
The Standardized Precipitation Index (SPI) is calculated in the following sequence.
[::] A monthly precipitation data set is prepared for a period of m months, ideally a continuous period of at least 30 years.
[::] A set of averaging periods are selected to determine a set of time scales of period j months where j is 3, 6, 12, 24, or 48 months. These represent arbitrary but typical time scales for precipitation deficits to affect the five types of usable water sources. The data set is moving in the sense that each month a new value is determined from the previous j months.
[::] Each of the data sets are fitted to the Gamma function to define the relationship of probability to precipitation.
[::] Once the relationship of probability to precipitation is established from the historic records, the probability of any observed precipitation data point is calculated and used along with an estimate of the inverse normal to calculate the precipitation deviation for a normally distributed probability density with a mean of zero and standard deviation of unity. This value is the SPI for the particular precipitation data point.
[\textbackslash n] [...]
[Summary]
A new definition of drought has been proposed which explicitly specifies time scales and utilizes a standardized precipitation index. Drought frequency decreases inversely and duration increases linearly with time scale. Frequency and duration of random climate and actual climate are very similar. The new definition allows a consistent set of information to be calculated including drought beginning, ending, intensity, and magnitude. It also produces monitoring information of index values, probability, percent of average, and precipitation deficit during drought.
Beginning in the fall of 1992, the SPI will be used as an experimental drought monitoring tool in Colorado. Operational evaluations will then be performed as experience is gained relating SPI values to actual impacts.},
keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-14027580,bioclimatic-predictors,droughts,high-impact-grey-literature,high-impact-publication,multi-scale,precipitation,predictors,standardized-precipitation-index}
}
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{"_id":"SBafdDcSCgv6zSyLX","bibbaseid":"mckee-doesken-kleist-therelationshipofdroughtfrequencyanddurationtotimescales","authorIDs":[],"author_short":["Mckee, T. B.","Doesken, N. J.","Kleist, J."],"bibdata":{"bibtype":"article","type":"article","title":"The Relationship of Drought Frequency and Duration to Time Scales","author":[{"propositions":[],"lastnames":["Mckee"],"firstnames":["Thomas","B."],"suffixes":[]},{"propositions":[],"lastnames":["Doesken"],"firstnames":["Nolan","J."],"suffixes":[]},{"propositions":[],"lastnames":["Kleist"],"firstnames":["John"],"suffixes":[]}],"date":"1993-01","url":"http://mfkp.org/INRMM/article/14027580","abstract":"[Excerpt: Introduction] 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. [\\n] Usable water sources include soil moisture, ground water, snowpack, streamflow and reservoir storage. Any impacts of drought associated with water demand exceeding water supply originate with one or more of these five usable supplies. The time period from the arrival of precipitation until water is available in each useable form differs greatly. Water uses also have characteristic time scales. Consequently, the impacts of a water deficit are a complex function of water source and water use. The time scale over which precipitation deficits accumulate becomes extremely important and functionally separates different types of drought. Agricultural (soil moisture) droughts, for example, typically have a much shorter time scale than hydrologic (groundwater, streamflow and reservoir) droughts. [\\n] Many examples are available where quantitative links have been established between precipitation deficits and drought impacts in particular water use areas. These use-specific relationships will likely continue to be expanded to assist in crop yield predictions, hydroelectric power projections and in many other drought-sensitive fields. However, the importance of monitoring and assessing water supply from a general climate perspective beginning with precipitation has not diminished. [\\n] 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. [...] [\\n] The purpose of the following discussion is to propose an indicator and definition of drought which could serve as a versatile tool in drought monitoring and analysis. This indicator requires only one input variable, could be applied in a similar way to precipitation, snowpack, streamflow, reservoir storage, soil moisture, and ground water, recognizes a variety of time scales, and provides information on precipitation deficit, percent of average and probability. [A functional definition of drought] [\\n] [...] The Standardized Precipitation Index (SPI) is calculated in the following sequence. [::] A monthly precipitation data set is prepared for a period of m months, ideally a continuous period of at least 30 years. [::] A set of averaging periods are selected to determine a set of time scales of period j months where j is 3, 6, 12, 24, or 48 months. These represent arbitrary but typical time scales for precipitation deficits to affect the five types of usable water sources. The data set is moving in the sense that each month a new value is determined from the previous j months. [::] Each of the data sets are fitted to the Gamma function to define the relationship of probability to precipitation. [::] Once the relationship of probability to precipitation is established from the historic records, the probability of any observed precipitation data point is calculated and used along with an estimate of the inverse normal to calculate the precipitation deviation for a normally distributed probability density with a mean of zero and standard deviation of unity. This value is the SPI for the particular precipitation data point. [\\n] [...] [Summary] A new definition of drought has been proposed which explicitly specifies time scales and utilizes a standardized precipitation index. Drought frequency decreases inversely and duration increases linearly with time scale. Frequency and duration of random climate and actual climate are very similar. The new definition allows a consistent set of information to be calculated including drought beginning, ending, intensity, and magnitude. It also produces monitoring information of index values, probability, percent of average, and precipitation deficit during drought. Beginning in the fall of 1992, the SPI will be used as an experimental drought monitoring tool in Colorado. Operational evaluations will then be performed as experience is gained relating SPI values to actual impacts.","keywords":"*imported-from-citeulike-INRMM,~INRMM-MiD:c-14027580,bioclimatic-predictors,droughts,high-impact-grey-literature,high-impact-publication,multi-scale,precipitation,predictors,standardized-precipitation-index","bibtex":"@article{mckeeRelationshipDroughtFrequency1993,\n title = {The Relationship of Drought Frequency and Duration to Time Scales},\n author = {Mckee, Thomas B. and Doesken, Nolan J. and Kleist, John},\n date = {1993-01},\n url = {http://mfkp.org/INRMM/article/14027580},\n abstract = {[Excerpt: Introduction] 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.\n\n[\\textbackslash n] Usable water sources include soil moisture, ground water, snowpack, streamflow and reservoir storage. Any impacts of drought associated with water demand exceeding water supply originate with one or more of these five usable supplies. The time period from the arrival of precipitation until water is available in each useable form differs greatly. Water uses also have characteristic time scales. Consequently, the impacts of a water deficit are a complex function of water source and water use. The time scale over which precipitation deficits accumulate becomes extremely important and functionally separates different types of drought. Agricultural (soil moisture) droughts, for example, typically have a much shorter time scale than hydrologic (groundwater, streamflow and reservoir) droughts.\n\n[\\textbackslash n] Many examples are available where quantitative links have been established between precipitation deficits and drought impacts in particular water use areas. These use-specific relationships will likely continue to be expanded to assist in crop yield predictions, hydroelectric power projections and in many other drought-sensitive fields. However, the importance of monitoring and assessing water supply from a general climate perspective beginning with precipitation has not diminished.\n\n[\\textbackslash n] 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. [...]\n\n[\\textbackslash n] The purpose of the following discussion is to propose an indicator and definition of drought which could serve as a versatile tool in drought monitoring and analysis. This indicator requires only one input variable, could be applied in a similar way to precipitation, snowpack, streamflow, reservoir storage, soil moisture, and ground water, recognizes a variety of time scales, and provides information on precipitation deficit, percent of average and probability.\n\n[A functional definition of drought]\n\n[\\textbackslash n] [...]\n\nThe Standardized Precipitation Index (SPI) is calculated in the following sequence.\n\n[::] A monthly precipitation data set is prepared for a period of m months, ideally a continuous period of at least 30 years. \n\n[::] A set of averaging periods are selected to determine a set of time scales of period j months where j is 3, 6, 12, 24, or 48 months. These represent arbitrary but typical time scales for precipitation deficits to affect the five types of usable water sources. The data set is moving in the sense that each month a new value is determined from the previous j months. \n\n[::] Each of the data sets are fitted to the Gamma function to define the relationship of probability to precipitation.\n\n[::] Once the relationship of probability to precipitation is established from the historic records, the probability of any observed precipitation data point is calculated and used along with an estimate of the inverse normal to calculate the precipitation deviation for a normally distributed probability density with a mean of zero and standard deviation of unity. This value is the SPI for the particular precipitation data point.\n\n[\\textbackslash n] [...]\n\n[Summary]\n\nA new definition of drought has been proposed which explicitly specifies time scales and utilizes a standardized precipitation index. Drought frequency decreases inversely and duration increases linearly with time scale. Frequency and duration of random climate and actual climate are very similar. The new definition allows a consistent set of information to be calculated including drought beginning, ending, intensity, and magnitude. It also produces monitoring information of index values, probability, percent of average, and precipitation deficit during drought.\n\nBeginning in the fall of 1992, the SPI will be used as an experimental drought monitoring tool in Colorado. Operational evaluations will then be performed as experience is gained relating SPI values to actual impacts.},\n keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-14027580,bioclimatic-predictors,droughts,high-impact-grey-literature,high-impact-publication,multi-scale,precipitation,predictors,standardized-precipitation-index}\n}\n\n","author_short":["Mckee, T. B.","Doesken, N. 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