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function ADTG = sw_adtg(S,T,P) |
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|
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% SW_ADTG Adiabatic temperature gradient |
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%=========================================================================== |
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% SW_ADTG $Revision: 1.4 $ $Date: 1994/10/10 04:16:37 $ |
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% Copyright (C) CSIRO, Phil Morgan 1992. |
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% |
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% adtg = sw_adtg(S,T,P) |
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% |
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% DESCRIPTION: |
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% Calculates adiabatic temperature gradient as per UNESCO 1983 routines. |
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% |
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% INPUT: (all must have same dimensions) |
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% S = salinity [psu (PSS-78) ] |
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% T = temperature [degree C (IPTS-68)] |
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% P = pressure [db] |
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% (P may have dims 1x1, mx1, 1xn or mxn for S(mxn) ) |
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% |
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% OUTPUT: |
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% ADTG = adiabatic temperature gradient [degree_C/db] |
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% |
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% AUTHOR: Phil Morgan 92-04-03 (morgan@ml.csiro.au) |
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% |
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% DISCLAIMER: |
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% This software is provided "as is" without warranty of any kind. |
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% See the file sw_copy.m for conditions of use and licence. |
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% |
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% REFERENCES: |
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% Fofonoff, P. and Millard, R.C. Jr |
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% Unesco 1983. Algorithms for computation of fundamental properties of |
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% seawater. Unesco Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39 |
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% |
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% Bryden, H. 1973. |
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% "New Polynomials for thermal expansion, adiabatic temperature gradient |
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% and potential temperature of sea water." |
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% DEEP-SEA RES., 1973, Vol20,401-408. |
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%========================================================================= |
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|
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%------------- |
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% CHECK INPUTS |
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%------------- |
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if nargin ~= 3 |
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error('sw_adtg.m: Must pass 3 parameters ') |
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end %if |
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|
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% CHECK S,T,P dimensions and verify consistent |
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[ms,ns] = size(S); |
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[mt,nt] = size(T); |
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[mp,np] = size(P); |
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|
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|
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% CHECK THAT S & T HAVE SAME SHAPE |
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if (ms~=mt) | (ns~=nt) |
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error('check_stp: S & T must have same dimensions') |
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end %if |
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|
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% CHECK OPTIONAL SHAPES FOR P |
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if mp==1 & np==1 % P is a scalar. Fill to size of S |
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P = P(1)*ones(ms,ns); |
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elseif np==ns & mp==1 % P is row vector with same cols as S |
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P = P( ones(1,ms), : ); % Copy down each column. |
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elseif mp==ms & np==1 % P is column vector |
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P = P( :, ones(1,ns) ); % Copy across each row |
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elseif mp==ms & np==ns % PR is a matrix size(S) |
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% shape ok |
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else |
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error('check_stp: P has wrong dimensions') |
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end %if |
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[mp,np] = size(P); |
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|
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|
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|
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% IF ALL ROW VECTORS ARE PASSED THEN LET US PRESERVE SHAPE ON RETURN. |
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Transpose = 0; |
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if mp == 1 % row vector |
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P = P(:); |
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T = T(:); |
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S = S(:); |
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|
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Transpose = 1; |
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end %if |
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%***check_stp |
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|
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%------------- |
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% BEGIN |
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%------------- |
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a0 = 3.5803E-5; |
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a1 = +8.5258E-6; |
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a2 = -6.836E-8; |
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a3 = 6.6228E-10; |
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|
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b0 = +1.8932E-6; |
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b1 = -4.2393E-8; |
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|
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c0 = +1.8741E-8; |
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c1 = -6.7795E-10; |
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c2 = +8.733E-12; |
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c3 = -5.4481E-14; |
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|
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d0 = -1.1351E-10; |
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d1 = 2.7759E-12; |
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|
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e0 = -4.6206E-13; |
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e1 = +1.8676E-14; |
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e2 = -2.1687E-16; |
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|
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ADTG = a0 + (a1 + (a2 + a3.*T).*T).*T ... |
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+ (b0 + b1.*T).*(S-35) ... |
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+ ( (c0 + (c1 + (c2 + c3.*T).*T).*T) + (d0 + d1.*T).*(S-35) ).*P ... |
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+ ( e0 + (e1 + e2.*T).*T ).*P.*P; |
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|
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if Transpose |
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ADTG = ADTG'; |
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end %if |
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|
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return |
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%========================================================================== |
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