spi: Calculate Standardized Precipitation Index (SPI)

In flogrc/piflow: Precipitation and discharge analysis tools with zoo vector

Description

Calculate SPI and the drought specifications with the length, the drought type and the intensity

Usage

spi(prec_data, time_step = 12, distribution = "gamma")

Arguments

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)

Value

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)

Author(s)

Florine Garcia ([e-mail])

Pierre L'Hermite ([e-mail])

References

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

See Also

plot_trend: plot the index

Examples

How to use function

flogrc/piflow documentation built on May 24, 2019, 7:34 a.m.