On the occurrence of photochemical oxidants at high latitudes

Results from an ozone monitoring programme during the summers of 1975 and 1976 in the lower Telemark area (ca. 59°N) in Norway shows that elevated ozone concentrations (up to 120 ppb) occurred, mainly during prevailing high pressure situations. Wind trajectory analyses indicate that the elevated ozone concentrations in part seem to be generated from locally emitted precursors, and in part are associated with long range transport in north-western Europe.