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USCRN Soil Moisture/Temperature Workshop March 3-5, 2009 Oak Ridge, TN. Temperature characterization of the Hydra II. Tilden Meyers NOAA/OAR/Air Resources Lab. Objectives With the new extended temperature range, characterize the overall accuracy of the Stevens Hydra II from -30 to +50 C
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USCRN Soil Moisture/Temperature Workshop March 3-5, 2009 Oak Ridge, TN Temperature characterization of the Hydra II Tilden Meyers NOAA/OAR/Air Resources Lab
Objectives • With the new extended temperature range, characterize the overall accuracy of the Stevens Hydra II from -30 to +50 C • Examine the repeatability of the results • Examine the consistency from probe to probe
Methodology Use the USCRN temperature calibration system to evaluate the performance of 3 Hydra II extended temperature range probe. System has NIST traceable PRT's and capable of calibrating from -60 to 60 C
Used the output of the SDI-12 reported temperature, which was determined from the traditional Steinhart-Hart equation that relates the measured resistance of a 200 k resistor (5 volt excitation) to temperature.
Conclusions • Repeatability was larger than expected with standard deviations of about +/- 0.1 C • Overall accuracy seemed acceptable from -20 to 40, but larger excursions at range limits of the probe. • Probe to Probe range was about 0.3, with larger differences at the extremes.