Lecture Typifying air masses and sources at Birkenes in southern Norway by combining ACTRIS observables and model tools. Fiebig, M.; Aas, W.; Solberg, S.; Schmidbauer, N.; Fjæraa, A.M.; Yttri, K.E.; Hamburger, T.; Lunder, C.R.; Myhre, C.L.; Wisthaler, A.; Tørseth, Hansen, G. Publication details Presented at 4th ACTRIS General Meeting, Clermont-Ferrand, France, 10-13 June 2014.