@Article{acp-5-1-2005, AUTHOR = {Scheele, M. P. and Siegmund, P. C. and Velthoven, P. F. J.}, TITLE = {Stratospheric age of air computed with trajectories based on various 3D-Var and 4D-Var data sets}, JOURNAL = {Atmospheric Chemistry and Physics}, VOLUME = {5}, YEAR = {2005}, NUMBER = {1}, PAGES = {1--7}, URL = {http://www.atmos-chem-phys.net/5/1/2005/}, ISSN = {1680-7316} }