get.PAR: Estimates Photosynthetically Active Radiation at the Earth's...

In gholtgrieve/gassyPants: Functions Useful for Working With Gasses Dissolved in Water

Description

Estimates 'blue-sky' photosynthetically active radiation (PAR) at the Earth's surface for a given location and timeframe. Considers both direct and diffuse radiation, but does not consider topographic or atmospheric effects.

Usage

get.PAR(lat, long, localHour, DOY, tz, masl = 0.001, aspect = 0.001, slope = 0.001, trans = 0.7)

Arguments

lat	Latitude in decimal degrees
long	Longitude in decimal degrees
localHour	Local time of day expressed as a decimal (i.e., 1:15 pm == 13.25)
DOY	Ordinal day of year ranging between 1 and 366 (1 == Jan 1; 366 == Dec 31 on a leap year.)
tz	Time zone expressed as hours from UTC (i.e., Pacific Standard Time == -8)
masl	Meters above sea level
aspect	Aspect of the land being modeled in degrees. Defaults to 180 (south).
slope	Slope of the land being modeled in degree. Defaults to 0.001 (flat).
trans	Atmospheric transmissivity (Fraction of extra-terrestrial solar radiation reaching the Earth's surface under cloudless conditions). Ranges from 0-1. Defaults to 0.7, which is a very approximate average.

Value

Photosynthetically active radiation (PAR) in units of microEinstiens s-1 m-2

Note

Specific PAR values are aproximations based on ideal (and probably unrealistic) condtions.

Author(s)

Gordon W. Holtgrieve ([e-mail])

References

Venkiteswaran et al. 2007 Gates 1966 Jellison and Melack 1993 McCree 1972

gholtgrieve/gassyPants documentation built on May 9, 2019, 5:02 a.m.