function_f (10/01/04)

CRHM Platform

f(t, u, Pa, Ht, Zwind, Zref)

  • Calculates the interval Drying Power for modules evap and evap2.

Units

  • (mm/kPa/Interval)

Inputs

  • t (°C) - air temperature.
  • Pa (kP) - atmospheric pressure.
  • u (m/s) - wind speed.
  • Ht (m) - crop height.
  • Zwind (m) - wind measurement height.
  • Zref (m) - temperature/humidity measurement height.

Returns

  • return( (0.622 * kappa*kappa * rhoa(t, Pa) * u * Interval*3600*24) / (Pa * x1 * x2))

where

d0 = 0.67*Ht and Z0 = 0.14*Ht

x1 = log( (Zwind-d0)/(Z0))

x2 = log( (Zref-0.67*Ht)/(Z0))

rhoa(t, Pa) = Density of air at (t, Pa).

kappa = 0.4 von Karman constant.

Interval = fraction of day.

Reference