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SPI_SPEI: Compute SPI and SPEI drought indices
This application allows to calculate the drought index SPI and SPEI. Currently the following indexes have been implemented:
- SPI adjusted to a gamma function: Calculate the SPI index, defined by McKee et al. (1993), adjusted to a gamma function in the form described by Lloyd-Hughes and Saunders (2002). The reference implementation can be consulted at:http://ccc.atmos.colostate.edu/standardizedprecipitation.php.
- 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.
- SPEI 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.
Syntax:
- SPI_SPEI Method Mode PrecipFile /DIR
- SPI_SPEI Method Mode PrecipFile TemFile [/DIR]
- SPI_SPEI Method Mode PrecipFile TemFilep_ET EvapoOption [/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:
- EST for Station
- RAS for Rasters
- 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 by the SPEI method) in station mode.
- TemFile
(Temperature file -
Input parameter): Text file with a list of temperature rasters (for SPEI method and raster mode only).
- TemFilep_ET
(Temperature file or evapotranspiration -
Input parameter): Text file with a list of temperature or evapotranspiration rasters (for SPEI method and raster mode only).
- EvapoOption
(Evapotranspiration option -
Input parameter): This parameter is only used in the case of SPEI and in RASTER mode, and it is used to specify how ET is computed. If no value is specified, or if ET_THORN_1948 is specified, the program assumes that the file TemFilep_ET contains the list of rasters with temperature data, and PET is computed using the Thornthwaite (1948) method. If ET_RASTER is specified, the program assumes that TemFilep_ET contains the list of rasters where each cell directly contains ET data (for example, from MODIS, etc.) in mm/month. If more flexibility in the units is required, please write to suport@miramon.uab.cat
Modifiers:
/DIR= (Output folder) Output folder where the result files will be saved. If not specified, they will be saved in the input file directory. (Output parameter)