Newer
Older
function [minerror] = tsg_accuracy(hMainFig, PARA, dtTsg)
%
% Give the accuracy of TSG salinity/temperature measurement based on
% SeaBird specifications, to use as the minimum error on measurements
% see http://www.seabird.com/products/spec_sheets/38data.htm
% http://www.seabird.com/products/spec_sheets/3Sdata.htm
% http://www.seabird.com/products/spec_sheets/21data.htm
% http://www.seabird.com/products/spec_sheets/45data.htm
%
% Get the tsg and sample structures from the application
% ------------------------------------------------------
tsg = getappdata( hMainFig, 'tsg_data');
if strcmp( PARA, 'SSTP')
if strcmp( tsg.TYPE_TINT, 'SBE38') | strcmp( tsg.TYPE_TINT, 'SBE3S')
% Accuracy of intake temperature is 0.001�C for SBE38/SBE3S sensors
minerror=0.001;
else
% Assume the same for other sensors
minerror=0.001;
end
end
if strcmp( PARA, 'SSJT')
if strcmp( tsg.TYPE_TSG, 'SBE45')
% Accuracy of jacket temperature is 0.002�C for SBE45 TSG
minerror=0.002;
else
% Accuracy of jacket temperature is 0.01�C for SBE21 TSG
minerror=0.01;
end
end
if strcmp( PARA, 'SSPS')
if strcmp( tsg.TYPE_TSG, 'SBE45')
% Accuracy of temperature/conductivity is 0.002�C/0.005mS/cm for SBE45 TSG
errT=0.002;
errC=0.005;
else
% Accuracy of temperature/conductivity is 0.01�C/0.01mS/cm for SBE21 TSG
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
errT=0.01;
errC=0.01;
end
if ~isempty( tsg.SSJT_CAL)
T = tsg.SSJT_CAL(dtTsg);
else
T = tsg.SSJT(dtTsg);
end
if ~isempty( tsg.CNDC_CAL)
C = tsg.CNDC_CAL(dtTsg);
else
C = tsg.CNDC(dtTsg);
end
% salinity error is computed from temperature/conductivity errors
% by error propagation in the salinity equation
% see Emery and Thomson, Data analysis methods in phys. oceano., p.273
R=C/sw_c3515();
rt = sw_salrt(T);
Rt=R./rt;
%Rt is a function of C,T
%error on Rt : err(Rt)^2=(d(Rt)/dC*errC)^2+(d(Rt)/dT*errT)^2
dRtdC=1./(rt*sw_c3515());
c68 = 1.00024;
c0 = 0.6766097;
c1 = 2.00564e-2;
c2 = 1.104259e-4;
c3 = -6.9698e-7;
c4 = 1.0031e-9;
dRtdT=c68*R.*(c1+(2*c2+(3*c3+4*c4*T).*T*c68).*T*c68)./(rt.^2);
errRt=sqrt((dRtdC*errC).^2+(dRtdT*errT).^2);
%S is a function of Rt,T
%error on S: err(S)^2=(dS/dRt*errRt)^2+(dS/dT*errT)^2
del_T68 = T * 1.00024 - 15;
Rtx = sqrt(Rt);
a0 = 0.0080;
a1 = -0.1692;
a2 = 25.3851;
a3 = 14.0941;
a4 = -7.0261;
a5 = 2.7081;
b0 = 0.0005;
b1 = -0.0056;
b2 = -0.0066;
b3 = -0.0375;
b4 = 0.0636;
b5 = -0.0144;
k = 0.0162;
dSdRt=(a1+(2*a2+(3*a3+(4*a4+5*a5*Rtx).*Rtx).*Rtx).*Rtx)./(2*Rtx)...
+(del_T68./(1+k*del_T68)).*(b1+(2*b2+(3*b3+(4*b4+5*b5*Rtx).*Rtx).*Rtx).*Rtx)./(2*Rtx);
dSdT=(b0+(b1+(b2+(b3+(b4+b5.*Rtx).*Rtx).*Rtx).*Rtx).*Rtx)./((1+k*del_T68).^2);
errS=sqrt((dSdRt.*errRt).^2+(dSdT.*errT).^2);
minerror=errS;
end
end