This book is based on a doctoral thesis submitted to the Faculty of Mathematics, Informatics, and Natural Science at the University of Hamburg in 2009. The preparation of this thesis would not have been possible without the advice and help I got from many people. First of all I want to thank Prof. Dr. Gerhard Lammel for guiding me through the entire time with well-balanced motivation and criticism, speci¿c questions, and goodhumoured advice, and for giving me the freedom to shape my selfmotivation and independence. My work and living was ¿nanced by the International Max Planck Research School for Maritime Affairs, and during the last month also by the Max Buchner Research Foundation. Thank you very for your trust in me. Thank you also to the directors and coordinators of the IMPRS-MA for providing an intersting education program, which opened my mind for issues I never would got in touch with otherwise. I am obliged to Dr. Hans Feichter for hosting me in his group, providing me an inspiring working environment and supporting me without any form of reimbursement. Thanks to all colleagues and friends from the former Aerosol Chemistry group, especially Dr. Francesca Guglielmo for inspiration, education and endless debugging support. I would like to express my thanks also to Dr. Helmut Haak for technical support, and Dr. Ernst Maier-Reimer, Dr. Jochen Segschneider, and Dr. Katharina Six for valuable comments. Many thanks to my of¿ce mates, Semeena, Alvaro, Angelika, Christine, and Katrin ´ for making of¿ce hours the most enjoyable. Special thanks to Chris, whose patient proof reading, editing and drawings helped shaping this manuscript. Finally, I would like to thank my family and f