envirem (version 2.3)

monthlyPET: monthly PET

Description

Monthly potential evapotranspiration

Usage

monthlyPET(Tmean, RA, TD, tempScale = 1)

Value

rasterStack of monthly PET in mm / month

Arguments

Tmean

rasterStack of monthly mean temperature

RA

rasterStack of monthly extraterrestrial solar radiation

TD

rasterStack of monthly temperature range

tempScale

integer; scaling factor for the temperature data, see envirem for additional details.

Author

Pascal Title

Details

PET = 0.0023 * RA * (Tmean + 17.8) * TD ^ 0.5

References

Hargreaves, G. L., Hargreaves, G. H., & Riley, J. P. (1985). Irrigation water requirements for Senegal River basin. Journal of Irrigation and Drainage Engineering, 111, 265-275.

Zomer, R.J., Trabucco, A., Bossio, D.A. & Verchot, L.V. (2008). Climate change mitigation: A spatial analysis of global land suitability for clean development mechanism afforestation and reforestation. Agriculture, Ecosystems and Environment, 126, 67-80.

Zomer, R.J., Trabucco, A., Van Straaten, O. & Bossio, D.A. (2006) Carbon, Land and Water: A Global Analysis of the Hydrologic Dimensions of Climate Change Mitigation through Afforestation/Reforestation. International Water Management Institute Research Report 101. Colombo, Sri Lanka.

Examples

# \donttest{
# Find example rasters
rasterFiles <- list.files(system.file('extdata', package='envirem'), full.names=TRUE)
env <- stack(rasterFiles)

# identify the appropriate layers
meantemp <- grep('mean', names(env), value=TRUE)
solar <- grep('solrad', names(env), value=TRUE)
maxtemp <- grep('tmax', names(env), value=TRUE)
mintemp <- grep('tmin', names(env), value=TRUE)

# read them in as rasterStacks
meantemp <- stack(env[[meantemp]])
solar <- stack(env[[solar]])
maxtemp <- stack(env[[maxtemp]])
mintemp <- stack(env[[mintemp]])
tempRange <- abs(maxtemp - mintemp)

monthlyPET(meantemp, solar, tempRange, tempScale = 10)
# }