MT BROCKEN, A SITE FOR A CLOUD CHEMISTRY MEASUREMENT PROGRAM IN CENTRAL-EUROPE

We present results from the Brocken Cloud Chemistry Measurement Projec t (BROCCMON) which started in 1991. Since 1992 the full programme is r unning, based on continuous measurements (e.g. trace gases, meteorolog y, liquid water content), cloud water sampling and analysis and intens ive measurement campaigns. The observed high variability of cloud wate r composition we explain with cloud dynamic and microphysical behaviou r of clouds and differences in the air mass characteristics. During th e measurement period 1992-1994 we observed an increase in cloud water acidity (by a factor of 3) and we found photochemical conditions typic ally for summersmog situations. Our preliminary data also show that an understanding of tropospheric ozone balance would be incomplete witho ut consideration of chemical processes within clouds. A long-term goal of our programme is to establish a cloud chemistry climatology which is representative for the region.