*** QSATW * - function to compute saturation vapor humidity from temperature
PURPOSE
-------
** METHOD
------
Given temperature T (PT), the saturation vapor pressure es(T)
(FOES(PT)) is computed by integration of the Clapeyron equation
from the triple point temperature Tt (XTT) and the saturation vapor
pressure of the triple point es(Tt) (XESTT), i.e
The reduction due to salinity is compute with the factor 0.98 (reduction of 2%)
es(T)= 0.98*EXP( alphaw - betaw /T - gammaw Log(T) )
with :
alphaw (XALPW) = LOG(es(Tt))+ betaw/Tt + gammaw Log(Tt)
betaw (XBETAW) = Lv(Tt)/Rv + gammaw Tt
gammaw (XGAMW) = (Cl -Cpv) /Rv
Then, the specific humidity at saturation is deduced.
EXTERNAL
--------
NONE
IMPLICIT ARGUMENTS
------------------
Module MODD_CST : comtains physical constants
XALPW : Constant for saturation vapor pressure function
XBETAW : Constant for saturation vapor pressure function
XGAMW : Constant for saturation vapor pressure function
REFERENCE
---------
Book2 of documentation of Meso-NH
Zeng, X., Zhao, M., and Dickinson, R. E., 1998 : Intercomparaison of bulk
aerodynamic algorithm for the computation of sea surface fluxes using
TOGA COARE and TAO data. Journal of Climate, vol 11, nb 10, pp 2628--2644
AUTHOR
------
C. Lebeaupin * Meteo France *
MODIFICATIONS
-------------
Original 6/04/2005
0. DECLARATIONS
------------
0.1 Declarations of arguments and results
2. COMPUTE SATURATION HUMIDITY
---------------------------
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| real, | intent(in), | DIMENSION(klon) | :: | PT | ||
| real, | intent(in), | DIMENSION(klon) | :: | PP |