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Measuring Total Column Water Vapor by Pointing an Infrared Thermometer at the SkyA 2-year study affirms that the temperature (Tz) indicated by an inexpensive ($20 to $60) IR thermometer pointed at the cloud-free zenith sky provides an approximate indication of the total column water vapor (precipitable water or PW). PW was measured by a MICROTOPS II sun photometer. The coefficient of correlation (r2) of the PW and Tz was 0.90, and the rms difference was 3.2 mm. A comparison of the Tz data with the PW provided by a GPS site 31 km NNE yielded an r2 of 0.79, and an rms difference of 5.8 mm. An expanded study compared Tz from eight IR thermometers with PW at various times during the day and night from 17 May to 18 October 2010, mainly at the Texas site and 10 days at Hawaii's Mauna Loa Observatory (MLO). The best results of this comparison were provided by two IR thermometers models that yielded an r2 of 0.96 and an rms difference with the PW of 2.7 mm. The results of both the ongoing 2-year study and the 5-month instrument comparison show that IR thermometers can measure PW with an accuracy (rms difference/mean PW) approaching 10%, the accuracy typically ascribed to sun photometers.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Mims, Forrest M., III (Geronimo Creek Observatory TX, United States)
Chambers, Lin H. (NASA Langley Research Center Hampton, VA, United States)
Brooks, David R. (Drexel Univ. Philadelphia, PA, United States)
Date Acquired
August 25, 2013
Publication Date
October 1, 2011
Publication Information
Publication: Bulletin of the American Meteorological Society
Volume: 92
Issue: 10
Subject Category
Instrumentation and Photography
Report/Patent Number
Funding Number(s)
WBS: WBS 565980.
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