As reported at the 9th GLOBE Annual Meeting, Richard Roettger and students at Ramey School, Aguadila, PR, conducted the first successful calibration of GLOBE water vapor instruments in 2004, by forcing GLOBE water vapor instrument data to produce agreement with values derived from a nearby GPS-MET site at Isabela, PR. Since the calibration was conducted, Ramey School has continued to report water vapor data, which provides a unique opportunity for long-term comparisons against the GPS-MET data. It is interesting to note that Ramey School reported data throughout 2005, while GPS-MET data are missing for most of the second half of 2005.
The agreement between the GLOBE water vapor instrument and the GPS-MET data continues to be excellent, as shown in these figures. GPS-MET data consist of averages from satellite radio signals over a half-hour, whereas the GLOBE water vapor data represent an "instantaneous" measurement of water vapor between the observer and the sun. Thus, the agreement is remarkable considering that these two instruments are measuring water vapor in two different ways, over different parts of the sky. Expanding the x-axis scale shows the diurnal signal available from the GPS-MET data. The excellent agreement between the two measurements is still evident over this expanded time scale.
You can get the Ramey School's WV data here, as a comma-separated text file. On Windows
computers, the .txt file may automatically open in Notepad. The .csv file may open in Excel. If the
file appears as a "page," you can just save it.
wv116.txt
wv116.csv
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| 2005 |
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| 2006 |
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| 2006 detail |