1. Comparison of Different Sea Surface Temperature Measurements
LCDR IVO J. PRIKASKY

2. Overview Motivation Collection methods Instrumentation
Statistical Analysis and results
Conclusions

3. Why do we need accurate SST measurements?
EM/EO prediction of refractive properties
0.5 deg C difference significant for evaporative duct height
Used in Met/Oceano models
Remote sensing verification
Aircraft
Satellite

4. Depths of SST Measurement Considerations
Skin SST
Depth of about 10 microns
Measured by radiometers
Bulk SST
Depth > 1 mm
Buoys, ship’s intake
Bucket/thermometer

5. Collection Methods – Skin Temp
Bridge mounted Radiometers
OS43L IR Sensor
Aimed at 45 deg
LW radiation between 8-14 microns
Denoted as OSST
Apogee IRT-P Sensor
Aimed at 45 deg
Measures LW radiation
Between microns
Denoted as ASST

6. Collection Methods – Skin Temp cont.
Hand-held Radiometers
Heitronics KT-19 Radiometer
30 deg angle
- the sky for LW sky T
Stated accuracy deg C
Denoted as Heit
Omega Radiometer
30 deg angle
Measures 8-14 microns
Did not work well
Denoted as Omega

7. Collection Methods – Bulk Temperature
Boom Probe – did not work
Bucket
Hourly measurements
Calibrated using ice water, +.2 deg
C error
Depth of measurement varied
Seachest
Intake 2.5 meters deep
Recorded by UDAS
Away from ship’s discharge

8. Corrections Instrument calibration
Unknown except for bucket – determined +.2 deg C
For radiometers, specular reflection corr.
Using formula
Applied to all radiometer measurments

9. General Analysis Seachest 11.22 0.98 Bucket 10.32 1.11 Heit 11.02 0.95
Measurement Type
Mean (deg C)
Std. Deviation (deg C)
Seachest
11.22
0.98
Bucket
10.32
1.11
Heit
11.02
0.95
Omega
7.79
1.80
ASST
8.56
4.49
OSST
8.78
1.61

10. Time Series – H/H Radiometers

11. T. Series – Bridge Mount. Radiometers

12. Time Series - Bulk Methods

13. Difference with Seachest
Measurement Type
Mean (deg C)
Std. Deviation (deg C)
Heit-seach.
0.4328
1.3105
Heitcor-seach.
1.1275
Bucket-seach.
1.4168
ASST-seach.
1.5666
1.7007
ASSTcor-seach.
1.9267
OSST-seach.
2.2314
1.4983
OSSTcor-seach.
1.4467

19. Conclusions Seachest Temp appears to be most reliable Human factor!
Little correlation among different measurements
Instrument calibration critical
Measuring SST accurately is challenging

20. Questions?