MeTo (version 0.1.1)

estG: Estimate soil heat flux (G)

Description

Estimate soil heat flux (G) for periods shorter than a day.

Usage

estG(
  x,
  Rs,
  Tmean,
  Rhmean,
  lat.rad = NULL,
  lat.deg = NULL,
  long.deg = NULL,
  elev = 1,
  tl,
  control = list(albedo = 0.23, Lz = 345, est.ratio.Rs.Rso = NA)
)

Arguments

x

date-time object (see details)

Rs

incoming solar radiation [MJ/(m2 time)]

Tmean

Mean air temperature [degreeC]

Rhmean

Mean air humidity [percent]

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)

elev

station elevation above sea level [m]

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 defined in controlDefaults and constDefaults (see Details)

Details

during daylight periods G is estimated to be Rn x 0.1 During nighttime G = Rn x 0.5. Day is defined for extraterrestrial radiation > 0.

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).

Examples

# NOT RUN {
estG(x = as.POSIXct(c('2018-10-01 14:30', '2018-10-01 15:00')), Tmean = 38, Rhmean = 52, Rs = 2.450,
     elev = 8, lat.deg = 16.21, long.deg = 343.75, control = list(Lz = 15))

estG(x = as.POSIXct('2018-10-01 02:30'), Tmean = 28, Rhmean = 90, tl = 1, Rs = 0, elev = 8,
     lat.deg = 16.2, long.deg = 343.75, control = list(Lz = 15, est.ratio.Rs.Rso = 0.8))

estG(x = as.POSIXct('2018-10-01 14:30'), Tmean = 38, Rhmean = 52, tl = 1, Rs = 2.450, elev = 8,
     lat.deg = 16.21, long.deg = 343.75, control = list(Lz = 15))

# }