water (version 0.8)

hourlyET: Calculates ET using Penman Monteith hourly formula

Description

Calculates ET using Penman Monteith hourly formula

Usage

hourlyET(WeatherStation, hours, DOY, long.z = WeatherStation$long,
  ET.instantaneous = FALSE, ET = "ETr", height = 2, lat, long, elev)

Arguments

WeatherStation

a data frame with all the needed fields (see example)

hours

time of the day in hours in 24hs format

DOY

day of year

long.z

longitude for local time

ET.instantaneous

Logical. True if you want to calculate instantaneous ET instead of hourly ET. See Details.

ET

"ETo" for short crops, similar to clipped, cool-season grass; or "ETr" for tall crops, similar to 0.5 m tall full-cover alfalfa.

height

weather station sensors height in meters

lat

latitude of weather station in decimal degrees. Negative values for south latitude

long

longitude of weather station in decimal degrees. Negative values for west longitude

elev

elevation of weather station in meters

Value

ET hourly in mm.h-1

Details

The only difference on instantaneous ET is how the hour is interpreted. On FALSE, and for example at 11:00, ET is calculated between 10:00 and 11:00, on TRUE Et is calculated at 11:00 hs.

References

Allen 2005 ASCE

Examples

# NOT RUN {
WeatherStation  <- data.frame(wind=4.72,
                              RH=59, 
                              temp=24.3,
                              radiation=675, 
                              height=2.2, 
                              lat=-35.37, 
                              long=71.5946, 
                              elev=124)
  hourlyET(WeatherStation, hours=10.5, DOY=363, long.z=71.635)
# }