Function ps = mollier_ps_magnus(T,pb);
psu = mollier_ps_magnus(T);
returns the saturation vapour pressure in Pa
for the given air temperature in degrees C
and total pressure (or barometric pressure)
pb in Pa.
The approximation in Magnus form is:
ps = A * exp( B * T / (C + T) ),
where A, B and C are constants.
Alduchov and Eskridge 1996 propose for the
"saturation vapour pressure of pure water vapour
over a plane surface of water" (in Pa):
psu = 610.94 * exp( 17.625 * T / (243.04 + T) ).
[equation 21 of their paper]
From this, they recommend to calculate the
saturation vapour pressure of "moist air above
a plane surface of water":
ps = psu * 1.00071 * exp( 0.0000045 .* pb / 100 ).
[equation 22 of their paper]
If the second input argument is not given,
psu is returned.
The valid range of T for this approximation
is obtained by calling m-file mollier_ps_lim_magnus.m.
See also the m-files:
mollier_Td_magnus.m
mollier_ps_ashrae2013.m
mollier_ps_baehr.m
mollier_ps_tetens.m
Reference:
Alduchov, O.A.; Eskridge, R.E. (1996). "Improved Magnus
form approximation of saturation vapor pressure".
Journal of Applied Meteorology, vol. 35 (4), pp. 601–609.
(c) 2026 fabien van mook
2026.08.20 release of this file within package "fvm-mollier" under GNU GPLv3+
