Calibration of Microcats

 

It was not possible to download data from the CTD itself so the data have been used to check that they are all operating in the same way and giving similar results.

 

 

Microcats without pressure readings dipped on 03/10/2002 with 1242 data points

 

Temperature

 

Matrix of correlation coefficients

Microcat Serial Numbers

  0955   2490     2491    2492    2493

0955    |1.0000 0.9997 0.9999 0.9998 1.0000

2490    |0.9997 1.0000 0.9999 1.0000 0.9997

2491    |0.9999 0.9999 1.0000 1.0000 0.9999

2492    |0.9998 1.0000 1.0000 1.0000 0.9998

2493    |1.0000 0.9997 0.9999 0.9998 1.0000

 

Least squares line fitting - Temperature

                                    Slope               Intercept

0995 v 2490                0.9995             -0.0012

 

2490 v 2491                0.9999             0.0023

 

2491 v 2492                0.9994             0.0010 

 

2492 v 2493                1.0005             -0.0003

 

 

Conductivity

 

Matrix of correlation coefficients

Microcat Serial Numbers

  0955   2490     2491    2492    2493

0955    |1.0000 0.9998 0.9999 0.9999 1.0000

2490    |0.9998 1.0000 0.9998 1.0000 0.9997

2491    |0.9999 0.9998 1.0000 0.9999 0.9999

2492    |0.9999 1.0000 0.9999 1.0000 0.9998

2493    |1.0000 0.9997 0.9999 0.9998 1.0000

 

 

Least squares line fitting - Conductivity

                                    Slope               Intercept

0995 v 2490                0.9992             0.0030

 

2490 v 2491                1.0001             -0.0005

 

2491 v 2492                0.9994             0.0027 

 

2492 v 2493                1.0008             -0.0027

 

Microcats with pressure reading dipped on 29/09/002 with 353 data points

 

Temperature

 

Matrix of correlation coefficients

Microcat Serial Numbers

   2486     2487    2488    2489

2486    |1.0000 0.9999 0.9999 0.9998

2487    |0.9999 1.0000 0.9997 0.9996

2488    |0.9999 0.9997 1.0000 1.0000

2489    |0.9998 0.9997 1.0000 1.0000

 

 

 

Least squares line fitting - Temperature

                                    Slope               Intercept

2486 v 2487                0.9997             0.0020

 

2486 v 2488                0.9990             0.0092

 

2486 v 2489                0.9973             0.0247

 

 

Conductivity

 

Matrix of correlation coefficients

Microcat Serial Numbers

   2486     2487    2488    2489

2486    |1.0000 0.9995 0.9999 0.9998

2487    |0.9995 1.0000 0.9995 0.9993

2488    |0.9999 0.9995 1.0000 1.0000

2489    |0.9998 0.9993 1.0000 1.0000

 

 

 

Least squares line fitting - Conductivity

                                    Slope               Intercept

2486 v 2487                0.9948             0.0200

 

2486 v 2488                0.9983             0.0055

 

2486 v 2489                0.9977             0.0085

 

 

 

 

 

 

 

 

 

 

 

Pressure

 

Matrix of correlation coefficients

Microcat Serial Numbers

   2486     2487    2488    2489

2486    |1.0000 1.0000  1.0000 1.0000

2487    |1.0000 1.0000  1.0000 1.0000 

2488    |1.0000 1.0000  1.0000 1.0000 

2489    |1.0000 1.0000  1.0000 1.0000 

 

 

 

Least squares line fitting - Conductivity

                                    Slope               Intercept

2486 v 2487                0.9986             -0.4557

 

2486 v 2488                0.9991             -1.1304

 

2486 v 2489                0.9987             -1.0077

 

 

 

Microcat Sn 1715 was dipped on it own on 30th September so no cross checking is possible.

 

 

 

 

Conclusion

 

The above values indicate that there are no significant differences in the relative values measured by these Microcats for temperature or conductivity.

There are significant constant differences between pressure readings taken by different Microcats.

Another calibration dip with a fully functional CTD will be required to determine any constant calibration factors to be applied to the  readings.