Description Usage Arguments Value Author(s) References See Also Examples
Calculate SPI and the drought specifications with the length, the drought type and the intensity
1 | spi(prec_data, time_step = 12, distribution = "gamma")
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prec_data |
[zoo] rainfall monthly data in zoo class with date in %Y-%m-%d |
time_step |
[numeric] by default = 12, time step to sum monthly data (1, 3, 6, 9, 12, 24 and 48) |
distribution |
[character] distribution of data (log_Logistic, gamma, grev, genlog, normal) |
list that contains
spi [zoo] zoo with the spi values with date in %Y-%m-%d
drought_type [zoo] zoo with the type of the period for each month
drought_number [data.frame] dataframe with the number of different period by type
Extwet (spi > 2)
Verywet (1.99 > spi > 1.5)
Wet (1.49 > spi > 1)
Normal (0.99 > spi > -0.99)
Dry (-1 > spi > -1.49)
VeryDry (-1.5 > spi > -1.99)
ExtDry (-2 > spi)
Florine Garcia (florine.garcia@gmail.com)
Pierre L'Hermite (pierrelhermite@yahoo.fr)
McKee, T.B., Doesken, N.J., & Kleist, J. (1993) The relationship of drought frequency and duration of time scales. Eighth Conference on Applied Climatology, American Meteorological Society http://www.droughtmanagement.info/literature/AMS_Relationship_Drought_Frequency_Duration_Time_Scales_1993.pdf
plot_trend
: plot the index
1 | How to use function
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