calc_zenith_angle: Calculate zenith angle as in...

In USGS-R/streamMetabolizer: Models for Estimating Aquatic Photosynthesis and Respiration

Calculate zenith angle as in http://education.gsfc.nasa.gov/experimental/July61999siteupdate/inv99Project.Site/Pages/solar.insolation.html

Description

Calculate zenith angle as in http://education.gsfc.nasa.gov/experimental/July61999siteupdate/inv99Project.Site/Pages/solar.insolation.html

Usage

calc_zenith_angle(
  latitude,
  declination.angle,
  hour.angle,
  format = c("degrees", "radians")
)

Arguments

latitude	numeric value or vector indicating the site latitude in decimal degrees (never radians or deg-min-sec, no matter what format is) between -90 (South Pole) and 90 (North Pole).
declination.angle	numeric value or vector, in the units specified by format, indicating the declination angle.
hour.angle	numeric value or vector, in the units specified by format, indicating the angle.
format	The format of both the output. May be "degrees" or "radians".

Examples

zendf <- data.frame(
  lat=rep(c(0,20,40,60), each=24*4),
  jday=rep(rep(c(1,101,201,301), each=24), times=4),
  hour=rep(c(0:12,13.5:23.5), times=4*4))
zendf <- transform(zendf,
  dec=streamMetabolizer:::calc_declination_angle(jday),
  hragl=streamMetabolizer:::calc_hour_angle(hour))
zendf <- transform(zendf,
  zen=streamMetabolizer:::calc_zenith_angle(lat, dec, hragl))
## Not run: 
library(ggplot2)
ggplot(unitted::v(zendf), aes(x=hour, y=zen, color=jday, group=jday)) +
  geom_line() + facet_wrap(~lat) +
  ggtitle('zenith angles by latitude (panels) and day of year (colors)')

## End(Not run)

USGS-R/streamMetabolizer documentation built on Aug. 15, 2023, 7:50 a.m.