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SPI_SPEI: Compute SPI and SPEI drought indices
Direct access to online help: SPI_SPEI
Access the application from the menu: "Tools | Image processing | Computing SPI and SPEI drought indices"
Presentation and options
This application allows to calculate the drought index SPI and SPEI. Currently the following calculation methods have been implemented:
SPI adjusted to Pearson III:
Calculate the SPI index, defined by McKee et al. (1993), adjusted based on Pearson III, etc, in the form described by Vicente_Serrano et al. (2009). The reference implementation can be consulted at: http://digital.csic.es.
PEI adjusted based on a Log Logistic distribution:
Calcula l'índex SPEI, Calculate the SPI index, defined by McKee et al. (1993), adjusted based on a Log Logistic distribution, in the form described by Vicente_Serrano et al. (2009). The reference implementation can be consulted at: http://digital.csic.es.
Dialog box of the application
Syntax
Syntax:
- SPI_SPEI Method Mode PrecipFile IntervalTemps [/DIR]
- SPI_SPEI Method Mode PrecipFile TempFile IntervalTemps [/DIR]
- SPI_SPEI Method Mode PrecipFile FitxTemp_ET IntervalTemps OpcioEvapo [/DIR]
Parameters:
- Method
(Method -
Input parameter): Calculation method:
- SPI_GAMMA for SPI set to a gamma function.
- SPI_PEARSON for SPI set based on Pearson III.
- SPEI_LLOG for SPEI adjusted based on a Logistic Log distribution.
You can ask the program to fill in the lost values with an average between the two previous and next values by adding "_FS" to the name of the index you want to calculate.
- Mode (Input parameter): Mode:
- ESTACIO for Station
- RASTER for Raster
- PrecipFile
(Precipitation file -
Input parameter): Precipitation file corresponding to a file with a list of precipitation rasters in raster mode or a precipitation text file (and temperatures for the SPEI method) in station mode.
- IntervalTemps
(Time interval -
Input parameter): Time interval, in months, for which the index is calculated. Typical values: 1, 3, 6, 12, 24 and 48 months.
- TempFile
(Temperature file -
Input parameter): Text file with a list of temperature rasters (SPEI method and raster mode only).
- FitxTemp_ET
(Temperature or evapotranspiration file -
Input parameter): Text file with a list of temperature or evapotranspiration rasters (SPEI method and raster mode only)
- OpcioEvapo
(Evapotranspiration option -
Input parameter): This parameter is only used for SPEI in RASTER mode and specifies how ET is calculated. If no value is indicated, or ET_THORN_1948 is indicated, the program assumes that TemFilep_ET contains the list of rasters with temperature data, and ETP is calculated using the Thornthwaite 1948 method. If ET_RASTER is indicated, the program assumes that TemFilep_ET contains rasters where each cell directly contains ET data (e.g. from MODIS, etc.) in mm/month. If you need more flexibility in units, please write to suport@miramon.uab.cat
Modifiers:
/DIR= (Output directory) Output directory where result files will be saved. If not indicated, they will be saved in the input file directory. (Input parameter)
