INTERCOMPARISON OF UV VISIBLE SPECTROMETERS FOR MEASUREMENTS OF STRATOSPHERIC NO2 FOR THE NETWORK FOR THE DETECTION OF STRATOSPHERIC CHANGE

During the period May 12-23, 1992, seven groups from seven countries m et in Lauder, New Zealand, to intercompare their remote sensing instru ments for the measurement of atmospheric column NO2 from the surface. The purpose of the intercomparison was to determine the degree of inte rcomparability and to qualify instruments for use in the Network for t he Detection of Stratospheric Change (NDSC). Three of the instruments which took part in the intercomparison are slated for deployment at pr imary NDSC sites. All instruments were successful in obtaining slant c olumn NO2 amounts at sunrise and sunset on most of the 12 days of the intercomparison. The group as a whole was able to make measurements of the 90 degrees solar zenith angle slant path NO2 column amount that a greed to about +/- 10% most of the time; however, the sensitivity of t he individual measurements varied considerably. Part of the sensitivit y problem for these measurements is the result of instrumentation, and part is related to the data analysis algorithms used. All groups lear ned a great deal from the intercomparison and improved their results c onsiderably as a result of this exercise.