et_0: The FAO Penman-Monteith crop reference evapotranspiration

Description Usage Arguments References Examples

Description

The panel of experts recommended in May 1990 the adoption of the FAO Penman-Monteith combination method as a new standard for reference evapotranspiration and advised on procedures for calculation of the various parameters (http://www.fao.org/docrep/X0490E/x0490e06.htm)

Usage

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et_0(Alt, Lat, Dates, Tavg = NA, Tmax, Tmin, Rh = NA, RHmax = NA,
  RHmin = NA, Sd = NA, Rs = NA, Ws, Rads = F)

Arguments

Alt

station altitude (m)

Lat

latitude in degrees (WGS84; EPSG:4326)

Dates

date field reprezenting days of measurements

Tavg

daily mean temperature (ºC)

Tmax

daily maximum temperature (ºC)

Tmin

daily minimum temperature (ºC)

Rh

daily mean relative humidity (%)

RHmax

daily maximum relative humidity (%)

RHmin

daily minimum relative humidity (%)

Sd

daily sunshine duration (hours)

Rs

daily global solar radiation (MJ m-2 day-1)

Ws

daily wind speed (m/s) at 2m above ground level

Rads

if is TRUE return shortwave and longwave radiation

References

http://www.fao.org/docrep/X0490E/x0490e08.htm

Examples

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data(buc_baneasa)
# convert wind speed form 10 magl to 2 magl
ws2m <- wind_log(buc_baneasa$Ws,10, 0.1, 2)
# compute ET0
et <- et_0( Alt = 90, Lat = 44.51072, Dates = as.Date(buc_baneasa$Date),
Tmax = buc_baneasa$Tmax, Tmin = buc_baneasa$Tmax, Rh = buc_baneasa$Rh,
Sd = buc_baneasa$Sd, Ws = ws2m)
plot(buc_baneasa$Date, buc_baneasa$Sd, type = "l")

alexdum/climatetools documentation built on May 11, 2019, 11:31 p.m.