= Dobson-Brewer absolute calibration campaign =

IzoBrewerCalibration

In this campaign World total ozone reference standards from Dobson and Brewer and European regional standards participate in a join campaign which the three main objectives

*Verify the calibration of Standard. *Compare the calibration levels of the regional standard defined by both direct comparison and by Langley Plot Method. *To investigate the precision of the Langley Plot method.

The world Dobson standard is managed by NOAA/ESRL/GMD the Brewer world standard is a triad of instruments managed by MSC, one of this triad will be present at the campaign. The European references from the Regional Dobson Calibration Center - Europe and Regional Brewer Calibration Center-Europe which host the intercomparison. Comparison between world reference instruments and regional calibration center is performed regularly. These Comparisons are performed during the regular intercomparison organized WMO-GAW Calibration centers. During this campaigns World Traveling instrument and/or and Regional reference instruments travel to the campaign place and transfer the calibration by side by side comparison. The Langley Absolute calibration is a method who takes the sun as reference and the instruments can be independently calibrated. The atmospheric conditions and scientific infrastructure and personal of the Izaña allows the Absolute calibration of the instruments.

This comparison between references also will help to clarify the differences between Dobson and Brewer in the early 90s found in some European Dobson-Brewer stations http://www.agu.org/pubs/crossref/1998/97JD03650.shtml Arosa Stahelin,1998, http://www.atmos-chem-phys-discuss.net/6/5839/2006/acpd-6-5839-2006.html Vanizeck 2006.