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MODULE MODULE_ICAO 2
!------------------------------------------------------------------------------!
! Collection of functions to compute h, p and t using standard atmosphere
! t is the temperaure in K,
! h is the height in m (h=0 at 1013.25hPa)
! P is pressure in Pa
!
! References:
! ----------
! Vasiljevic et al. 1992: ECMWF 3D Variational data assimilation
! of conventional observations
! In proceedings of the ECMWF Workshop on Variational assimilation, with
! special emphasis on three dimensional aspects. 9-12 November 1992, pp 389-435
!
! F. VANDENBERGHE, March 2001
!------------------------------------------------------------------------------!
include 'constants.inc'
include 'missing.inc'
REAL, PARAMETER :: p_0 = 101325., & ! ICAO reference pressure Pa
t_0 = 288., & ! ICAO reference temperature K
lambda = 0.0065, & ! ICAO temperature lapse rate K/m
alpha = lambda * gasr / g ! ICAO constant (no unit)
REAL :: height_max_icao
CONTAINS
!------------------------------------------------------------------------------!
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FUNCTION t_from_h_icao (h) RESULT (t)
IMPLICIT NONE
REAL :: h, t
t = t_0 - lambda * h
END FUNCTION t_from_h_icao
!------------------------------------------------------------------------------!
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FUNCTION t_from_p_icao (p) RESULT (t)
IMPLICIT NONE
REAL :: p, t
t = t_0 *(p / p_0) ** alpha
END FUNCTION t_from_p_icao
!------------------------------------------------------------------------------!
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FUNCTION h_from_p_icao (p) RESULT (h)
IMPLICIT NONE
REAL :: p, h
h = t_0 / lambda * (1. - (p / p_0) ** alpha)
END FUNCTION h_from_p_icao
!------------------------------------------------------------------------------!
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FUNCTION p_from_h_icao (h) RESULT (p)
IMPLICIT NONE
REAL :: p, h, one_over_alpha
one_over_alpha = 1. /alpha
p = p_0 * (1. - lambda * h / t_0)** one_over_alpha
END FUNCTION p_from_h_icao
!------------------------------------------------------------------------------!
END MODULE MODULE_ICAO