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SPI_SPEI: Computing of 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 /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).
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)