Increasing springtime ozone mixing ratios in the free troposphere over western North America.

Cooper, O.R.; Parrish, D.D.; Stohl, A.; Trainer, M.; Nédeléc, P.; Thouret, V.; Cammas, J.P.; Oltmans, S.J.; Johnson, B.J.; Tarasick, D.; Leblanc, T.; McDermid, I.S.; Jaffe, D.; Gao, R.; Stith, J.; Ryerson, T.; Aikin, K.; Campos, T.; Weinheimer, A.; Avery, M.A.