Evaluation of ozone measurement data at the sites Birkenes, Jeløya and Prestebakke over the period 1988-1995.

This report gives a summary of the work performed by Michie! Roemer during his stay at NILU in summer 1997. His study revealed discrepancies in trends between three sites (Birkenes, Prestebakke and Jeløya) located in the same region of Norway. This report gives an evaluation of factors that may explain the discrepancy. Finally some recommendations with respect to data quality objectives are given.