/[MITgcm]/MITgcm/model/src/seawater.F
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Contents of /MITgcm/model/src/seawater.F

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Revision 1.6 - (show annotations) (download)
Tue Mar 16 00:08:27 2010 UTC (14 years, 2 months ago) by jmc
Branch: MAIN
CVS Tags: checkpoint64y, checkpoint64x, checkpoint64z, checkpoint64q, checkpoint64p, checkpoint64s, checkpoint64r, checkpoint64u, checkpoint64t, checkpoint64w, checkpoint64v, checkpoint64i, checkpoint64h, checkpoint64k, checkpoint64j, checkpoint64m, checkpoint64l, checkpoint64o, checkpoint64n, checkpoint64a, checkpoint64c, checkpoint64b, checkpoint64e, checkpoint64d, checkpoint64g, checkpoint64f, checkpoint63p, checkpoint63q, checkpoint63r, checkpoint63s, checkpoint63l, checkpoint63m, checkpoint63n, checkpoint63o, checkpoint63h, checkpoint63i, checkpoint63j, checkpoint63k, checkpoint63d, checkpoint63e, checkpoint63f, checkpoint63g, checkpoint63a, checkpoint63b, checkpoint63c, checkpoint64, checkpoint65, checkpoint63, checkpoint65h, checkpoint65i, checkpoint65b, checkpoint65c, checkpoint65a, checkpoint65f, checkpoint65g, checkpoint65d, checkpoint65e, checkpoint62g, checkpoint62f, checkpoint62e, checkpoint62d, checkpoint62k, checkpoint62j, checkpoint62i, checkpoint62h, checkpoint62o, checkpoint62n, checkpoint62m, checkpoint62l, checkpoint62s, checkpoint62r, checkpoint62q, checkpoint62p, checkpoint62w, checkpoint62v, checkpoint62u, checkpoint62t, checkpoint62z, checkpoint62y, checkpoint62x
Changes since 1.5: +3 -3 lines 
avoid unbalanced quote (single or double) in commented line
1 C $Header: /u/gcmpack/MITgcm/model/src/seawater.F,v 1.5 2009/10/22 04:33:59 jmc Exp $
2 C $Name: $
3
4 #include "CPP_OPTIONS.h"
5
6 C-- File seawater.F: routines that compute quantities related to seawater.
7 C-- Contents
8 C-- o SW_PTMP: function to compute potential temperature
9 C-- o SW_TEMP: function to compute in-situ temperature from pot. temp.
10 C-- o SW_ADTG: function to compute adiabatic temperature gradient
11 C-- (used by both SW_PTMP & SW_TEMP)
12
13 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
14
15 CBOP
16 C !ROUTINE: SW_PTMP
17 C !INTERFACE:
18 _RL FUNCTION SW_PTMP (S,T,P,PR)
19
20 C !DESCRIPTION: \bv
21 C *=============================================================*
22 C | S/R SW_PTMP
23 C | o compute potential temperature as per UNESCO 1983 report.
24 C *=============================================================*
25 C
26 C started:
27 C Armin Koehl akoehl@ucsd.edu
28 C
29 C ==================================================================
30 C SUBROUTINE SW_PTMP
31 C ==================================================================
32 C S :: salinity [psu (PSS-78) ]
33 C T :: temperature [degree C (IPTS-68)]
34 C P :: pressure [db]
35 C PR :: Reference pressure [db]
36
37 C !USES:
38 IMPLICIT NONE
39
40 C !INPUT/OUTPUT PARAMETERS:
41 _RL S,T,P,PR
42
43 C !FUNCTIONS:
44 _RL sw_adtg
45 EXTERNAL sw_adtg
46
47 C !LOCAL VARIABLES
48 _RL del_P ,del_th, th, q
49 _RL onehalf, two, three
50 PARAMETER ( onehalf = 0.5 _d 0, two = 2. _d 0, three = 3. _d 0 )
51 CEOP
52
53 C theta1
54 del_P = PR - P
55 del_th = del_P*sw_adtg(S,T,P)
56 th = T + onehalf*del_th
57 q = del_th
58 C theta2
59 del_th = del_P*sw_adtg(S,th,P+onehalf*del_P)
60
61 th = th + (1 - 1/sqrt(two))*(del_th - q)
62 q = (two-sqrt(two))*del_th + (-two+three/sqrt(two))*q
63
64 C theta3
65 del_th = del_P*sw_adtg(S,th,P+onehalf*del_P)
66 th = th + (1 + 1/sqrt(two))*(del_th - q)
67 q = (two + sqrt(two))*del_th + (-two-three/sqrt(two))*q
68
69 C theta4
70 del_th = del_P*sw_adtg(S,th,P+del_P)
71 SW_PTMP = th + (del_th - two*q)/(two*three)
72
73 RETURN
74 END
75
76 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
77
78 CBOP
79 C !ROUTINE: SW_TEMP
80 C !INTERFACE:
81 _RL FUNCTION SW_TEMP( S, T, P, PR )
82 C !DESCRIPTION: \bv
83 C *=============================================================*
84 C | S/R SW_TEMP
85 C | o compute in-situ temperature from potential temperature
86 C *=============================================================*
87 C
88 C REFERENCES:
89 C Fofonoff, P. and Millard, R.C. Jr
90 C Unesco 1983. Algorithms for computation of fundamental properties of
91 C seawater, 1983. _Unesco Tech. Pap. in Mar. Sci._, No. 44, 53 pp.
92 C Eqn.(31) p.39
93 C
94 C Bryden, H. 1973.
95 C New Polynomials for thermal expansion, adiabatic temperature gradient
96 C and potential temperature of sea water.
97 C DEEP-SEA RES., 1973, Vol20,401-408.
98
99 C !USES:
100 IMPLICIT NONE
101 C === Global variables ===
102
103 C !INPUT/OUTPUT PARAMETERS:
104 C === Routine arguments ===
105 C S :: salinity
106 C T :: potential temperature
107 C P :: pressure
108 C PR :: reference pressure
109 _RL S, T, P, PR
110 CEOP
111
112 C !FUNCTIONS:
113 _RL sw_adtg
114 EXTERNAL sw_adtg
115
116 C !LOCAL VARIABLES:
117 _RL del_P ,del_th, th, q
118 _RL onehalf, two, three
119 PARAMETER ( onehalf = 0.5 _d 0, two = 2. _d 0, three = 3. _d 0 )
120
121 C theta1
122 C-- here we swap P and PR in order to get in-situ temperature
123 C del_P = PR - P ! to get potential from in-situ temperature
124 del_P = P - PR ! to get in-situ from potential temperature
125 del_th = del_P*sw_adtg(S,T,P)
126 th = T + onehalf*del_th
127 q = del_th
128 C theta2
129 del_th = del_P*sw_adtg(S,th,P+onehalf*del_P)
130
131 th = th + (1 - 1/sqrt(two))*(del_th - q)
132 q = (two-sqrt(two))*del_th + (-two+three/sqrt(two))*q
133
134 C theta3
135 del_th = del_P*sw_adtg(S,th,P+onehalf*del_P)
136 th = th + (1 + 1/sqrt(two))*(del_th - q)
137 q = (two + sqrt(two))*del_th + (-two-three/sqrt(two))*q
138
139 C theta4
140 del_th = del_P*sw_adtg(S,th,P+del_P)
141 SW_temp= th + (del_th - two*q)/(two*three)
142
143 RETURN
144 END
145
146 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
147
148 CBOP
149 C !ROUTINE: SW_ADTG
150 C !INTERFACE:
151 _RL FUNCTION SW_ADTG (S,T,P)
152
153 C !DESCRIPTION: \bv
154 C *=============================================================*
155 C | S/R SW_ADTG
156 C | o compute adiabatic temperature gradient as per UNESCO 1983 routines.
157 C *=============================================================*
158 C
159 C started:
160 C Armin Koehl akoehl@ucsd.edu
161
162 C !USES:
163 IMPLICIT NONE
164
165 C !INPUT/OUTPUT PARAMETERS:
166 _RL S,T,P
167
168 C !LOCAL VARIABLES:
169 _RL a0,a1,a2,a3,b0,b1,c0,c1,c2,c3,d0,d1,e0,e1,e2
170 _RL sref
171 CEOP
172
173 sref = 35. _d 0
174 a0 = 3.5803 _d -5
175 a1 = +8.5258 _d -6
176 a2 = -6.836 _d -8
177 a3 = 6.6228 _d -10
178
179 b0 = +1.8932 _d -6
180 b1 = -4.2393 _d -8
181
182 c0 = +1.8741 _d -8
183 c1 = -6.7795 _d -10
184 c2 = +8.733 _d -12
185 c3 = -5.4481 _d -14
186
187 d0 = -1.1351 _d -10
188 d1 = 2.7759 _d -12
189
190 e0 = -4.6206 _d -13
191 e1 = +1.8676 _d -14
192 e2 = -2.1687 _d -16
193
194 SW_ADTG = a0 + (a1 + (a2 + a3*T)*T)*T
195 & + (b0 + b1*T)*(S-sref)
196 & + ( (c0 + (c1 + (c2 + c3*T)*T)*T) + (d0 + d1*T)*(S-sref) )*P
197 & + ( e0 + (e1 + e2*T)*T )*P*P
198
199 RETURN
200 END
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