From: Jérôme de La Noë [delanoe@observ.u-bordeaux.fr] Sent: Wednesday, July 18, 2001 03:40 AM Agency OBX Station Bordeaux WOUDC StationID 419 Calibration/inter-comparison of Dobson #49. This instrument has participated in 3 intercomparison campaigns since we have it in Bordeaux: 1- in 1990, at Observatoire de Haute Provence (responsible Bob Evans, NOAA/CMDL) 2- in 1995, at LKO, Arosa, Switzerland (responsible Bob Evans, NOAA/CMDL) 3- in 1999, at LKO, Arosa, Switzerland (responsible Bob Evans, NOAA/CMDL). The results of the two last campaigns follow. ------------------------------------------ DOBSON Intercomparaison Arosa 30 July 1995 ------------------------------------------ Original Calibration Data : N-tables from July 1990, Obseravtoire Haute Provence OHP intercomparaison Reference Standard Lamp Values for lamps 49/2H1, 49/3H1 and 49/4H1 Lamp test results are not used for data processing at home station Initial Calibration Results : 30 July 1990 d_Na:+0.12 d_Nc:+0.07 d_Nd:+0.06 The d_Nad values implies an average +0.04% error in calculated ozone values, Mu=1.15 to 3.2, Total Ozone = 300 Dobson Units. Work Performed. This instrument was cleaned, gaskets replaced, GQP was cleaned, etc. Wedges were not, as they cannot be removed without disconnecting encoder system. Interior was dirty and filmed, right side mirror is fogged. Results of intercomparaison show that the instrument's G-tables remain unchanged, but the level shifted. ------------------------------------------ DOBSON Intercomparaison Arosa 25 July 1999 ------------------------------------------ Original Calibration Data : N-tables from 30 July 1995, Arosa LKO intercomparaison Reference Standard Lamp Values for lamps 49/2H1, 49/3H1 and 49/4H1 Lamp test results are not used for data processing at home station Initial Calibration Results : 25 July 1995 d_Na:-1.2 d_Nc:-1.0 d_Nd:-1.0 d_Nad:-0.2 The d_Nad values implies an average +0.3% error in calculated ozone values, Mu=1 to 3, Total Ozone = 300 Dobson Units. Work Performed. * Discharge lamp test was performed - the resulkts matched the existing Q-table * Optical Symmetry checked and found to be very clean * Interior and Optics were inspected and found to be very clean. Final Intercomparaison : Not applied, as the instrument is within calibration limits to D065 Highest Difference against the standard for ADDSGQP observations in Mu range 1.15 to 3.2 was +0.6% in total ozonz, at low Mu. The instrument was compared to D065 on three separate days, and repeated the results within 0.5% based on the differences in the Nad values. The 25 July 1999 intercomparaison was chosen, as it was the clearest conditions of three days. The instrument has an encoder mounted on the wedge to record the wedge position electronically. For a wedge calibration to be performed, this encoder will have to be removed. This procedure was beyond the facilities and time of this intercomparaison. The operators are encouraged to have the wedge calibration checked at the Region VI DCC in Hohenpeissenberg, Germany within the next several years. Comments about the last sentence above: due to a lot of work and lack of money, it is not possible to organize the wedge calibration in 2001. But we will do our best to plan such an operation in 2002. ----------------------------------------------------------------------------- Jerome de La Noe Observatoire de Bordeaux Universite Bordeaux1/CNRS/INSU B.P.89, 33270 Floirac, France Tel.: 05 57 77 61 56 or 33 5 57 77 61 56 Fax : 05 57 77 61 55 or 33 5 57 77 61 55 Switchboard: 05 57 77 61 00 or 33 5 57 77 61 00 E-mail: delanoe@observ.u-bordeaux.fr Visit the Bordeaux Observatory http://www.observ.u-bordeaux.fr -----------------------------------------------------------------------------