seem (version 1.0)

Sun functions: Solar radiation functions

Description

Functions to calculate sun elevation angle and solar radiation by hour, and maximum daily. Applies to one day or sequence of multiple consecutive days. Also included is azimuth by hour and atmospheric effects.

Usage

sun.dec(nday)
sun.elev.max(nday,lat)
sun.rad.yr(nday,lat,Lm)
sun.elev.hr(nday, lat,hr.noon)
sun.rad.hr(nday,lat,hr.noon,Lm,sdr=0)
sun.rad.hr.mult(nday,lat,Lm,sdr=0,sw.plot=T)
sun.path(nday,lat)
sun.atmos(nday,lat,rho)

Arguments

nday

day of the year

lat

latitude

Lm

max radiation in the day

hr.noon

hour with respect to noon, negative for hours before noon, and positive for hours after noon

sdr

An optional argument with default value zero is the standard deviation of noise or variability to be imposed on the hourly radiation

sw.plot

optional logical variable to decide to plot the results

rho

reflectivity

Value

• dec
  declination
• elev
  maximum sun elevation angle for the day or for each hr of the day
• rad
  radiation for the day, for each hour of teh day, or for the running hour in multiple days
• hr.cum
  total running hr for multiple days
• hr.noon
  hour with respect to noon
• azi
  azimuth
• I0
  ET solar radiation kW/m2
• A
  atmospheric effect
• opt.depth
  optical depth
• air.mass
  air mass
• I
  matrix containing IB=direct baeam, ID=diffuse, IR=reflected, and IT=total

Details

sun.dec: calculates declination for a given day of the year sun.elev.max: maximum sun elevation angle for a given day sun.rad.yr: uses the annual average of maximum radiation in the day Lm to convert maximum elevation into radiation. sun.elev.hr: Sun elevation by hour during the day requires an argument for the hour with respect to noon. Elevation is made zero when the calculation yields negative values. sun.rad.hr: uses the annual average of maximum radiation in the day Lm to convert elevation by hour into radiation by hour (optionally can impose variability). sun.rad.hr.mult:calculates hourly radiation for multiple consecutive days. sun.path: calculates sun elevation and azimuth by hour of the day. sun.atmos: calculates atmospheric effects.

References

Acevedo M.F. 2012. Simulation of Ecological and Environmental Models. CRC Press.

Masters G. 2004. Renewable and Efficient Electric Power Systems, Wiley-IEEE Press.

See Also

Primary productivity functions PPrates.depth, PP.Steele, DO.PP.pond

Examples

# day of year
nday <- seq(1,365); nd <- length(nday)
dec <- sun.dec(nday)

lat = c(-32,-23.45,23.45,32); nl <- length(lat)
elev <- matrix(nrow=nd,ncol=nl)
for(i in 1:nl) elev[,i] <- sun.elev.max(nday,lat[i])

nday <- seq(1,365); nd <- length(nday)
Lm = c(500,600); nl <- length(Lm)
lat <- 32.90
rad <- matrix(nrow=nd,ncol=nl)
for(i in 1:nl) rad[,i] <- sun.rad.yr(nday,lat,Lm[i])

# latitude tropic, and dallas (DFW)
lat = c(23.45,32.90); nl <- length(lat)
nday = c(15,81,180); nd <- length(nday)
hr.noon <- seq(-12,+12,0.1); nh <- length(hr.noon)
elev <- matrix(nrow=nh,ncol=nl);rad <- matrix(nrow=nh,ncol=nl)
j=1
for(i in 1:nl){
elev[,i] <- sun.elev.hr(nday[j],lat[i],hr.noon)
rad[,i] <- sun.rad.hr(nday[j],lat[i],hr.noon,Lm=600)
}
elev <- matrix(nrow=nh,ncol=nd);rad <- matrix(nrow=nh,ncol=nd)
j=2
for(i in 1:nd){
 elev[,i] <- sun.elev.hr(nday[i],lat[j],hr.noon)
 rad[,i] <- sun.rad.hr(nday[i],lat[j],hr.noon,Lm=600)
}
# latitude dallas (DFW)
lat = 32.90; nday = c(39:41); Lm=600
X <- sun.rad.hr.mult(nday,lat,Lm,sdr=0,sw.plot=TRUE)