Comparison of Different Sea Surface Temperature Measurements

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Comparison of Different Sea Surface Temperature
Measurements

• LCDR IVO J. PRIKASKY

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Overview

• Motivation
• Collection methods
• Instrumentation
• Statistical Analysis and results
• Conclusions

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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

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Depths of SST Measurement Considerations

• Skin SST
• Depth of about 10 microns
• Measured by radiometers
• Bulk SST
• Depth gt 1 mm
• Buoys, ships intake
• Bucket/thermometer

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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 6.5 -14 microns
• Denoted as ASST

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Collection Methods Skin Temp cont.

• Hand-held Radiometers

• Heitronics KT-19 Radiometer
• Measurements _at_ 30 deg angle
• - Pointed _at_ the sky for LW sky T
• Stated accuracy 0.5 deg C
• Denoted as Heit

• Omega Radiometer
• Measurements _at_ 30 deg angle
• Measures 8-14 microns
• Did not work well
• Denoted as Omega

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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 ships discharge

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Corrections

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

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General Analysis
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Time Series H/H Radiometers
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T. Series Bridge Mount. Radiometers
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Time Series - Bulk Methods
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Difference with Seachest
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Conclusions

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

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Questions?