Since 1988, I have been involved in numerical modeling of the physics and chemistry of the atmosphere. I have used mesoscale models to investigate human and natural (e.g. fire, volcanic eruptions, anthropogenic emissions, land-use changes) impacts on weather, air quality and climate. In close cooperation with hydrologists and geologists I coupled a hydrologic and meteorological model and developed an integrative hydrometeorological model. I worked with computer scientists on optimizing chemistry transport models for parallel computers. I led several projects to study ground water recharge, dry deposition of reactive atmospheric trace gases, water availability under changed climate conditions, the impact of land-use changes on evapotranspiration, cloud and precipitation formation, and impacts of various emission sources on air quality and weather. From 1999 to 2001 I was honored as a Heisenberg Fellow for Physical Hydrology, a prestigious award conferred by the DFG. My scientific career in America dates back to 1989, when I worked as a visiting graduate student at the ASRC of the State University of New York (SUNY) at Albany. In 2000, I worked at the National Center for Atmospheric Research (NCAR) at Boulder, Colorado. In 2001, I joined the University of Alaska Fairbanks (UAF). At UAF, I continue my research direction with special focus on air quality issues of the Arctic and continue my teaching activities. Since 1995, in Germany and the United States, I have taught cloud physics, satellite meteorology, physical hydrometeorology, paleoclimatology, parameterization of hydrometerological processes, numerical modeling and parameterization methods, mesoscale dynamics, introduction to computational meteorology and introduction to atmospheric sciences.