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C $Header: /u/gcmpack/MITgcm/model/src/seawater.F,v 1.10 2015/02/15 16:47:32 mlosch Exp $ |
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C $Name: $ |
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#include "CPP_OPTIONS.h" |
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|
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C-- File seawater.F: routines that compute quantities related to seawater. |
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C-- Contents |
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C Seawater (SW) librabry routines |
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C-- o SW_PTMP: function to compute potential temperature |
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C-- o SW_TEMP: function to compute in-situ temperature from pot. temp. |
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C-- o SW_ADTG: function to compute adiabatic temperature gradient |
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C-- (used by both SW_PTMP & SW_TEMP) |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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CBOP |
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C !ROUTINE: SW_PTMP |
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C !INTERFACE: |
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_RL FUNCTION SW_PTMP (S,T,P,PR) |
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|
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C !DESCRIPTION: \bv |
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C *=============================================================* |
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C | S/R SW_PTMP |
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C | o compute potential temperature as per UNESCO 1983 report. |
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C *=============================================================* |
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C |
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C started: |
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C Armin Koehl akoehl@ucsd.edu |
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C |
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C ================================================================== |
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C SUBROUTINE SW_PTMP |
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C ================================================================== |
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C S :: salinity [psu (PSS-78) ] |
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C T :: temperature [degree C (IPTS-68)] |
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C P :: pressure [db] |
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C PR :: Reference pressure [db] |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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_RL S,T,P,PR |
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|
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C !FUNCTIONS: |
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_RL sw_adtg |
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EXTERNAL sw_adtg |
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|
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C !LOCAL VARIABLES |
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_RL del_P ,del_th, th, q |
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_RL onehalf, two, three |
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PARAMETER ( onehalf = 0.5 _d 0, two = 2. _d 0, three = 3. _d 0 ) |
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CEOP |
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|
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C theta1 |
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del_P = PR - P |
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del_th = del_P*sw_adtg(S,T,P) |
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th = T + onehalf*del_th |
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q = del_th |
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C theta2 |
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del_th = del_P*sw_adtg(S,th,P+onehalf*del_P) |
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|
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th = th + (1 - 1/sqrt(two))*(del_th - q) |
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q = (two-sqrt(two))*del_th + (-two+three/sqrt(two))*q |
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|
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C theta3 |
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del_th = del_P*sw_adtg(S,th,P+onehalf*del_P) |
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th = th + (1 + 1/sqrt(two))*(del_th - q) |
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q = (two + sqrt(two))*del_th + (-two-three/sqrt(two))*q |
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|
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C theta4 |
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del_th = del_P*sw_adtg(S,th,P+del_P) |
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SW_PTMP = th + (del_th - two*q)/(two*three) |
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|
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RETURN |
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END |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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CBOP |
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C !ROUTINE: SW_TEMP |
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C !INTERFACE: |
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_RL FUNCTION SW_TEMP( S, T, P, PR ) |
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C !DESCRIPTION: \bv |
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C *=============================================================* |
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C | S/R SW_TEMP |
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C | o compute in-situ temperature from potential temperature |
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C *=============================================================* |
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C |
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C REFERENCES: |
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C Fofonoff, P. and Millard, R.C. Jr |
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C Unesco 1983. Algorithms for computation of fundamental properties of |
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C seawater, 1983. _Unesco Tech. Pap. in Mar. Sci._, No. 44, 53 pp. |
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C Eqn.(31) p.39 |
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C |
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C Bryden, H. 1973. |
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C New Polynomials for thermal expansion, adiabatic temperature gradient |
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C and potential temperature of sea water. |
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C DEEP-SEA RES., 1973, Vol20,401-408. |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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C === Global variables === |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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C === Routine arguments === |
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C S :: salinity |
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C T :: potential temperature |
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C P :: pressure |
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C PR :: reference pressure |
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_RL S, T, P, PR |
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CEOP |
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|
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C !FUNCTIONS: |
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_RL sw_ptmp |
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EXTERNAL sw_ptmp |
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|
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SW_temp = SW_PTMP (S,T,PR,P) |
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|
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RETURN |
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END |
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|
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C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----| |
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|
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CBOP |
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C !ROUTINE: SW_ADTG |
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C !INTERFACE: |
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_RL FUNCTION SW_ADTG (S,T,P) |
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|
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C !DESCRIPTION: \bv |
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C *=============================================================* |
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C | S/R SW_ADTG |
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C | o compute adiabatic temperature gradient as per UNESCO 1983 routines. |
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C *=============================================================* |
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C |
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C started: |
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C Armin Koehl akoehl@ucsd.edu |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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_RL S,T,P |
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|
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C !LOCAL VARIABLES: |
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_RL a0,a1,a2,a3,b0,b1,c0,c1,c2,c3,d0,d1,e0,e1,e2 |
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_RL sref |
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CEOP |
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|
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sref = 35. _d 0 |
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a0 = 3.5803 _d -5 |
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a1 = +8.5258 _d -6 |
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a2 = -6.836 _d -8 |
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a3 = 6.6228 _d -10 |
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b0 = +1.8932 _d -6 |
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b1 = -4.2393 _d -8 |
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c0 = +1.8741 _d -8 |
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c1 = -6.7795 _d -10 |
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c2 = +8.733 _d -12 |
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c3 = -5.4481 _d -14 |
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d0 = -1.1351 _d -10 |
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d1 = 2.7759 _d -12 |
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e0 = -4.6206 _d -13 |
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e1 = +1.8676 _d -14 |
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e2 = -2.1687 _d -16 |
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SW_ADTG = a0 + (a1 + (a2 + a3*T)*T)*T |
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& + (b0 + b1*T)*(S-sref) |
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& + ( (c0 + (c1 + (c2 + c3*T)*T)*T) + (d0 + d1*T)*(S-sref) )*P |
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& + ( e0 + (e1 + e2*T)*T )*P*P |
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|
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RETURN |
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END |
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