@Article{acpd-4-4489-2004,
AUTHOR = {Scheele, M. P. and Siegmund, P. C. and van Velthoven, P. F. J.},
TITLE = {Stratospheric age of air computed with trajectories based on various 3-D-Var and 4-D-Var data sets},
JOURNAL = {Atmospheric Chemistry and Physics Discussions},
VOLUME = {4},
YEAR = {2004},
NUMBER = {4},
PAGES = {4489--4506},
URL = {http://www.atmos-chem-phys-discuss.net/4/4489/2004/},
ISSN = {1680-7367}
}