GOME OBSERVATIONS OF TROPOSPHERIC BRO IN NORTHERN HEMISPHERIC SPRING AND SUMMER 1997

Measurements from the Global Ozone Monitoring Experiment GOME have bee n analysed for tropospheric BrO in the northern hemispheric spring and summer 1997. Tropospheric excess columns have been determined by subt racting measurements from a longitude range which is assumed to repres ent background conditions. From February until the end of May enhanced tropospheric BrO columns are observed over the Hudson Bay area and pa rts of the Canadian Arctic. This large and persistent event has not be en reported before and can only be explained by a large local source o f bromine. In addition, from March to May other,smaller and shorter tr opospheric BrO events are detectable along the coast lines of the Arct ic Sea and over the polar ice. They correspond to the ground-based obs ervations of enhanced tropospheric BrO reported from several stations in the high Arctic.