A. Christen is Full Professor at the Chair of Environmental Meteorology of the University of Freiburg, Germany where he teaches fundamentals in weather, climate, climate change and urban climate. Previously, he was Associate Professor in the Department of Geography and in the Atmospheric Science Program at the University of British Columbia, Vancouver. His research focuses on interactions between complex land surfaces - including cities - and the atmosphere. He develops new methods to quantify, attribute and model the exchange of energy, water and trace-gases between complex land surfaces and the atmosphere, in order to benefit applications such as climate-sensitive urban design, air pollution and emission management, urban weather forecasting and climate modeling.