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Standardized Precipitation Evaporation Index for the Upper Green River Basin (1896-2017)


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Assal, T.J., 2018, Standardized Precipitation Evaporation Index for the Upper Green River Basin (1896-2017): U.S. Geological Survey data release,


The standardized precipitation evapotranspiration index (SPEI) was summarized for the Upper Green River Basin to quantify climate variability over the last century. The SPEI incorporates both precipitation and temperature data, therefore the index has the capacity to include the effects of temperature variability on drought. The SPEI considers the difference between precipitation and potential evapotranspiration to calculate a climatic water balance at a given time scale (Vicente-Serrano et al. 2010). The number of standard deviations the climatic water balance deviates from the long-term mean for a given time period represents the SPEI for the time period. Here, I calculated the SPEI for each water year (Oct–Sept) between 1896 and [...]


Point of Contact :
Timothy J Assal
Process Contact :
Timothy J Assal
Originator :
Timothy J Assal
Metadata Contact :
Timothy J Assal
Distributor :
U.S. Geological Survey - ScienceBase
SDC Data Owner :
Fort Collins Science Center
USGS Mission Area :

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The data were produced as an approach to quantify the effects of temperature and the frequency and intensity of wet and dry patterns across the study area and to specifically place the 2012 drought in a historical perspective.
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  • Fort Collins Science Center (FORT)
  • USGS Data Release Products



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DOI doi:10.5066/P9VLM7Z6

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