R/vpd.apsim.r

In weaana: Analysis the Weather Data

# * Author:    Scott Chapman (Scott.Chapman@csiro.au)
# * Created:   09/04/2010
# *

# Calculate the vpd using apsim method
# 
# Calculate the vpd using apsim method
# @param maxt The maximum temperature
# @param mint The minimum temperature
# @return vpd calculated APSIM method
vpd.apsim <- function( maxt, mint )
{
    vpd <- 0.1 * 0.75 * ( 6.1078 * exp( ( 17.269 * maxt ) / ( 273.3 + maxt ) )
                   - 6.1078 * exp ( ( 17.269 * mint ) / ( 273.3 + mint ) ) )
    vpd[ vpd < 0.01 ] <- 0.01
    return( vpd )
}