Characterizing summertime chemical boundary conditions for airmasses entering the US West Coast - Pfister, G. G.; Parrish, D. D.; Worden, H.; Emmons, L. K.; Edwards, D. P.; Wiedinmyer, C.; Diskin, G. S.; Huey, G.; Oltmans, S. J.; Thouret, V.; Weinheimer, A.; Wisthaler, A. (Atmos. Chem. Phys., 2011)