Calculate the humidity


INTERFACE:

   subroutine humidity(hum_method,hum,airp,tw,ta)
DESCRIPTION:

This routine calculated the saturation vapour pressure at SST and at air temperature, as well as the saturation specific humidty and the specific humidity. For the latter, four methods are implemented, and the method has to be chosen in the namelist file airsea.nml as parameter hum_method, see section 5.2.1 for details.


USES:

   use airsea_variables, only: kelvin,const06,rgas
   use airsea_variables, only: es,ea,qs,qa,rhoa
   IMPLICIT NONE
INPUT PARAMETERS:
   integer, intent(in)                 :: hum_method
   REALTYPE, intent(in)                :: hum,airp,tw,ta
OUTPUT PARAMETERS:
REVISION HISTORY:
   Original author(s): Adolf Stips, Hans Burchard & Karsten Bolding
DEFINED PARAMETERS:
   REALTYPE, parameter       :: a1=6.107799961
   REALTYPE, parameter       :: a2=4.436518521e-1
   REALTYPE, parameter       :: a3=1.428945805e-2
   REALTYPE, parameter       :: a4=2.650648471e-4
   REALTYPE, parameter       :: a5=3.031240396e-6
   REALTYPE, parameter       :: a6=2.034080948e-8
   REALTYPE, parameter       :: a7=6.136820929e-11
LOCAL VARIABLES:
   REALTYPE        :: rh,twet,twet_k,dew,dew_k



Karsten Bolding 2012-12-28