72 lines
2.6 KiB
Text
72 lines
2.6 KiB
Text
National Environmental Public Health Tracking Network
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Standard Precipitation Evapotranspiration Index (SPEI) Metadata
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Publication Date
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01/11/2017
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Background
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The Standardized Precipitation Evapotranspiration Index (SPEI) is an extension of the
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widely used Standardized Precipitation Index (SPI). The SPEI is designed to take into
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account both precipitation and potential evapotranspiration (PET) in determining
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drought. Thus, unlike the SPI, the SPEI captures the main impact of increased
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temperatures on water demand. Like the SPI, the SPEI can be calculated on a range of
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timescales from 1-48 months. At longer timescales (>~18 months), the SPEI has been
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shown to correlate with the self-calibrating PDSI (sc-PDSI). If only limited data are
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available, such as temperature and precipitation, PET can be estimated with the simple
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Thornthwaite method. In this simplified approach, variables that can affect PET such as
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wind speed, surface humidity and solar radiation are not accounted for. The dataset
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includes one-month SPEI values for every contiguous US county and the District of
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Columbia monthly from 1895-2016.
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The dataset has been compiled to estimate wetness and dryness of a particular area.
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This is important for the agriculture as well as health sectors. The data can be used to
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examine local and national trends in drought information.
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Data Values
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Range from -3 (dry) to +3 (wet). 0 indicates normal conditions. Missing data is noted as
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-99,99,
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Geographic Scale
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Data includes all counties in the lower 48 states plus the District of Columbia.
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& Scope
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Time Period January 1, 1895 — December 31, 2016. Known to be accurate as of time period end date.
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Raw Data Data were downloaded from the National Oceanic and Atmospheric Administration
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Processing (NOAA) server and were originally provided as monthly values at a 5km grid. Distance
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weighting functions were applied to constrain the drought values to a specific US county.
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No data were lost or omitted during calculation. All data that were available were used.
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Data will be updated on an ad hoc basis, when necessary.
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Additional Vicente-Serrano, Sergio M. & National Center for Atmospheric Research Staff (Eds). Last
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Information
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modified 18 Jul 2015. "The Climate Data Guide: Standardized Precipitation
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Evapotranspiration Index (SPEI)." Retrieved from
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https://climatedataguide.ucar.edu/climate-data/standardized-precipitation-
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evapotranspiration-index-spei.
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Vicente-Serrano, Sergio M., Santiago Begueria, Juan |. L6pez-Moreno, 2010: A
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Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation
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Evapotranspiration Index. J. Climate, 23, 1696-1718.
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