Evaluation and Recommendations for Improving the Accuracy of an Inexpensive Water Temperature Logger

S. J. Lentz, J. H. Churchill, C. Marquette, J. Smith

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Onset's HOBO U22 Water Temp Pros are small, reliable, relatively inexpensive, self-contained temperature loggers that are widely used in studies of oceans, lakes, and streams. An in-house temperature bath calibration of 158 Temp Pros indicated root-mean-square (RMS) errors ranging from 0.01° to 0.14°C, with one value of 0.23°C, consistent with the factory specifications. Application of a quadratic calibration correction substantially reduced the RMS error to less than 0.009°C in all cases. The primary correction was a bias error typically between -0.1° and 0.15°C. Comparison of water temperature measurements from Temp Pros and more accurate temperature loggers during two oceanographic studies indicates that calibrated Temp Pros have an RMSerror of~0.02°C throughout the water column at night and beneath the surface layer influenced by penetrating solar radiation during the day. Larger RMS errors (up to 0.08°C) are observed near the surface during the day due to solar heating of the black Temp Pro housing. Errors due to solar heating are significantly reduced by wrapping the housing with white electrical tape. © 2013 American Meteorological Society.
Original languageEnglish (US)
Pages (from-to)1576-1582
Number of pages7
JournalJournal of Atmospheric and Oceanic Technology
Issue number7
StatePublished - Jul 2013
Externally publishedYes


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