Rnl | R Documentation |
Net longwave radiation (Rnl).
Rnl( x, Tmax = NULL, Tmin = NULL, Rhmax = NULL, Rhmin = NULL, Rs = NULL, lat.rad = NULL, lat.deg = NULL, long.deg = NULL, elev, actVP = NULL, tl, Tmean = NULL, Rhmean = NULL, control = list() )
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)] |
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 |
see |
elev |
station elevation above sea level [m] |
actVP |
Actual vapor pressure [kPa]. If Rhmax, Rhmin and Rhmean are NULL |
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 length of x is date-time object with length of 1. |
Tmean |
mean temperature [degreeC] during the time period (for periods shorter than a day) |
Rhmean |
Mean air humidity [percent] (for periods shorter than a day or if Rhmax and Rhmin are missing) |
control |
list for control parameters and empirical factors (see Details and |
must be provided as.numeric (1-366) or as a common date-time object (e.g, POSIXct, POSIXlt or Date objects). All formats for which is.timepoint from the lubridate package returns TRUE can be used
Lz:
longitude of the centre of the local time zone (degrees west of Greenwich)
- 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.
est.ratio.Rs.Rso:
Rs/Rso is used to represent cloud cover. For hourly or shorter periods during the nighttime,
the ratio Rs/Rso is set equal to the Rs/Rso calculated for a time period occurring 2-3 hours before sunset.
If single values during nighttime are calculated Rs/Rso ration 2-3 hours before sunset can not be calculated
and an approximation is needed. Following Allen (1999) one can assume Rs/Rso = 0.4 to 0.6 during nighttime periods
in humid and subhumid climates and Rs/Rso = 0.7 to 0.8 in arid and semiarid climates. A value of Rs/Rso = 0.3 presumes
total cloud cover.
Rnl net outgoing longwave radiation [MJ(/m2 time)]
eq. 39 of reference
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).
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