ExAtRa: Extra-Atmospheric Radiation
In ClimClass: Climate Classification According to Several Indices

Description Usage Arguments Details Value Author(s) See Also Examples

Calculates Extra-Atmospheric Radiation. Called by function arid for Thornthwaite's index.

1	ExAtRa(DOY, latitude, Gsc = 0.082, unit = "mm", T = 12)

`DOY`	day of the year.
`latitude`	latitude in degrees (negative for S emishpere).
`Gsc`	solar constant in MJ m-2 min-1 (default: 0.0820).
`unit`	unit for solar radiation. Accepted values are "mm" and "MJ".
`T`	temperature in degrees C. Default is 12.

If unit = "mm", the calculated value represents the water height evaporated by solar radiation, calculated by the latent heat for vaporization. Otherwise (unit = "MJ") output is the solar radiation energy in MJ. Temperature T is used only for the assessment of latent heat of vaporization, when unit = "mm".

The daily extra-atmospheric solar radiation energy, espressed either in MJ or in mm of evaporated water.

Emanuele Eccel

arid

data(Trent_climate)
# creates a vector with middle days for every month in a year
quinci   <- paste(15,"/",1:12,"/",2014,sep="")
posixlt  <- strptime(quinci, format="%d/%m/%Y")
yDay     <- posixlt$yday+1  # field yday starts from 0
latitude<-46  

# generates 12 values, one for each month
coeff_rad<- ExAtRa(DOY=yDay,latitude=latitude, unit="mm")