Aerosol optical properties relevant to regional remote sensing of CCN activity and links to their organic mass fraction: airborne observations over Central Mexico and the US West Coast during MILAGRO/INTEX-B - Shinozuka, Y.; Clarke, A. D.; DeCarlo, P. F.; Jimenez, J. L.; Dunlea, E. J.; Roberts, G. C.; Tomlinson, J. M.; Collins, D. R.; Howell, S. G.; Kapustin, V. N.; McNaughton, C. S.; Zhou, J. (Atmos. Chem. Phys., 2009)