*IF DEF,CONTROL                                                            GLW1F404.3      
CLL======== FUNCTION ATG =================================                 ATG.2      
C ******************************COPYRIGHT******************************    GTS2F400.343    
C (c) CROWN COPYRIGHT 1995, METEOROLOGICAL OFFICE, All Rights Reserved.    GTS2F400.344    
C                                                                          GTS2F400.345    
C Use, duplication or disclosure of this code is subject to the            GTS2F400.346    
C restrictions as set forth in the contract.                               GTS2F400.347    
C                                                                          GTS2F400.348    
C                Meteorological Office                                     GTS2F400.349    
C                London Road                                               GTS2F400.350    
C                BRACKNELL                                                 GTS2F400.351    
C                Berkshire UK                                              GTS2F400.352    
C                RG12 2SZ                                                  GTS2F400.353    
C                                                                          GTS2F400.354    
C If no contract has been raised with this copy of the code, the use,      GTS2F400.355    
C duplication or disclosure of it is strictly prohibited.  Permission      GTS2F400.356    
C to do so must first be obtained in writing from the Head of Numerical    GTS2F400.357    
C Modelling at the above address.                                          GTS2F400.358    
C ******************************COPYRIGHT******************************    GTS2F400.359    
C                                                                          GTS2F400.360    
CLL CODED BY :      OSCAR  ALVES   22/2/93                                 ATG.3      
CLL REVIEWED BY:                                                           ATG.4      
CLL                                                                        ATG.5      
CLL ADIABATIC TEMPERATURE GRADIENT DEG C PER DECIBAR                       ATG.6      
CLL REF: BRYDEN, H. 1973, DEEP-SEA RES., 20 , 401-408                      ATG.7      
CLL UNITS:                                                                 ATG.8      
CLL       PRESSURE        P       DECIBARS                                 ATG.9      
CLL       TEMPERATURE     T       DEGREES C. (IPTS-68)                     ATG.10     
CLL       SALINITY        S       (PSS-78)                                 ATG.11     
CLL       ADIABATIC       ATG     DEGREES CELCIUS PER DECIBAR              ATG.12     
CLL                                                                        ATG.13     
CLL PRESSURE IS "OCEANOGRAPHIC " PRESSURE EQUAL TO ABSOLUTE                ATG.14     
CLL PRESSURE MINUS ONE ATMOPSPHERE                                         ATG.15     
CLL                                                                        ATG.16     
CLL CHECK VALUE:  ATG=3.2559758e-04               -CRAY 64 BIT             ATG.17     
CLL                  =3.2559758000000D-04         -IEEE 64 BIT             ATG.18     
CLL FOR: P=10000.0, T=40.0, S=40.0                                         ATG.19     
CLLEND                                                                     ATG.20     
C*L                                                                        ATG.21     

        REAL FUNCTION ATG(P,T,S)                                            2ATG.22     
                                                                           ATG.23     
        IMPLICIT NONE                                                      ATG.24     
                                                                           ATG.25     
C-- DEFINE ARGUMENTS                                                       ATG.26     
        REAL                                                               ATG.27     
     &  P     ! PRESSURE (DECIBARS)                                        ATG.28     
     & ,T     ! TEMPERATURE (DEG C)                                        ATG.29     
     & ,S     ! SALINITY (PSU)                                             ATG.30     
                                                                           ATG.31     
C-- DEFINE LOCAL VARIABLES                                                 ATG.32     
        REAL DS     ! SALINITY-35.0                                        ATG.33     
C                                                                          ATG.34     
                                                                           ATG.35     
        DS=S-35E0                                                          ATG.36     
        ATG= (((-2.1687E-16*T+1.8676E-14)*T-4.6206E-13)*P                  ATG.37     
     &     + ((2.7759E-12*T-1.1351E-10)*DS+((-5.4481E-14*T                 ATG.38     
     &     + 8.733E-12)*T-6.7795E-10)*T+1.8741E-8))*P                      ATG.39     
     &     + (-4.2393E-8*T+1.8932E-6)*DS                                   ATG.40     
     &     + ((6.6228E-10*T-6.836E-8)*T+8.5258E-6)*T+3.5803E-5             ATG.41     
                                                                           ATG.42     
        RETURN                                                             ATG.43     
        END                                                                ATG.44     
*ENDIF                                                                     GLW1F404.4