ssd2igl: Convert sunshine duration to global radiation
In rsachse/limnotools: Help Tools of TU Dresden's Limnology Workgroup

Description Usage Arguments Value Examples

The function converts values of sunshine duration (in hours) to global radiation (in J/cm2/d)

1	ssd2igl(S, doy, a = 0.25, b = 0.5, rho = 50.29)

`S`	Sunshine duration (hours)
`doy`	Julian day (for northern hemisphere only)
`a, b, rho`	site specific conversion parameters, must be fitted to measured data

vector of converted values

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function(S, doy, a=0.25, b=0.5, rho=50.29) {
  xi <- 0.0172 * doy - 1.39
  S0 <- 12.3 + sin(xi) * (4.3 + (rho - 51))/6
  Rex <- 245 * (9.9 + 7.08 * sin(xi) + 0.18 * (rho - 51) * (sin(xi) - 1))
  Rex * (a + b * S/S0)
  }