MeTo (version 0.1.1)

Rn: Net radiation (Rn)

Description

Difference between the incoming net shortwave radiation (Rns) and the outgoing net longwave radiation (Rnl).

Usage

Rn(
  x,
  Tmax = NULL,
  Tmin = NULL,
  Rhmax = NULL,
  Rhmin = NULL,
  Rs = NULL,
  n = NULL,
  elev,
  lat.rad = NULL,
  lat.deg = NULL,
  long.deg = NULL,
  Rhmean = NULL,
  actVP = NULL,
  Tmean = NULL,
  tl,
  control = list()
)

Arguments

x

date-time object or day of the year (must be date-time object if calculation period is shorter than a day)

Tmax

maximum temperature [degreeC] during 24-hour period (for daily values)

Tmin

minimum temperature [degreeC] during 24-hour period (for daily values)

Rhmax

daily maximum of air humidity [percent] (for daily values)

Rhmin

daily minimum of air humidity [percent] (for daily values)

Rs

incoming solar radiation [MJ/(m2 time)]

n

Actual hours of sunshine. Used to calculate Rs if missing.

elev

station elevation above sea level [m]

lat.rad

latitude [rad]. Use either lat.rad or lat.deg. Latitude is positive for the northern hemisphere and negative for the southern hemisphere

lat.deg

latitude [degree]. Use either lat.deg or lat.rad. Latitude is positive for the northern hemisphere and negative for the southern hemisphere

long.deg

longitude of the measurement site (degrees east of Greenwich) (for periods < 1 day)

Rhmean

Mean air humidity [percent] for periods < day or if Rhmax and Rhmin are missing

actVP

Actual vapor pressure [kPa]. If Rhmax, Rhmin and Rhmean are NULL

Tmean

Mean air temperature [degree C] for periods < day

tl

length of calculation period [hour] (1 for hourly period, 0.5 for a 30-minute period or 24 for daily period). Only needed if x is date-time object with length of 1.

control

list for control parameters and empirical factors (see Details)

Value

net radiation

Details

for daily and hourly calculations

References

Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration-Guidelines for computing crop water requirements-FAO Irrigation and drainage paper 56. FAO, Rome, 300(9).

See Also

Rns, Rnl

Examples

# NOT RUN {
# --------------------------------------------
#  Daily period
# --------------------------------------------

Rn(x = 105, n = 8.5, elev = 2, actVP = 2.85, Tmax = 34.8,
   Tmin = 25.6, lat.deg = 13.73)

Rn(x = 135, elev = 1, Rs = 14.5, Tmax = 25.1, Tmin = 19.1,
   lat.deg = -22.9, actVP = 2.1)

# --------------------------------------------
#  Hourly period
# --------------------------------------------

Rn(x = as.POSIXct(c('2018-10-01 14:30', '2018-10-01 15:30')), Tmean = c(38, 37.8),
   Rhmean = c(52, 52.2), Rs = c(2.450, 2.1), elev = 8, lat.deg = 16.2,
   long.deg = 343.75, control = list(Lz = 15))

Rn(x = as.POSIXct('2018-10-01 14:30'), Tmean = 38, Rhmean = 52, tl = 1, Rs = 2.450,
   elev = 8, lat.deg = 16.2, long.deg = 343.75, control = list(Lz = 15))

# }