Rso {MeTo}

Clear-sky solar radiation (Rso)

Description

Clear-sky solar radiation for daily and shorter periods.

Usage

Rso(
  x,
  lat.rad = NULL,
  lat.deg = NULL,
  long.deg = NULL,
  elev,
  tl,
  control = list(Lz = 345)
)

Arguments

x

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

lat.rad

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

lat.deg

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

long.deg

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

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).

control

list for control parameters and empirical factors defined in controlDefaults and constDefaults (see Details)

Details

x:

must be provided as.numeric (1-366) or as a common date-time object (e.g, POSIXct, POSIXlt, and Date objects). All formats for which is.timepoint from the lubridate package returns TRUE can be used

control:

Lz:
longitude of the centre of the local time zone (degrees west of Greenhich)
- 0 for Greenwich
- 345 for Germany
- 330 for Cairo (Egypt)
- 255 for Bangkok (Thailand)
- 75, 90, 105 and 120 for Eastern, Central, Rocky Mountain and Pacific time zones (United States)
Lz is only needed if calculation period is shorter 1 day.

for day, hour and shorter periods

References

eq. 37; 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

# --------------------------------------------
#  Daily period
# --------------------------------------------

Rso(x = 135, elev = 1, lat.deg = -22.9)

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

Rso(x = as.POSIXct('2018-10-01 12:30'), tl = 1, elev = 8, lat.deg = 16.2,
    long.deg = 343.75, control = list(Lz = 15))