Crawford, J., R. E. Shetter, B. Lefer, B. Cantrell, W. Junkermann, S. Madronich, and J. Calvert (2003), Cloud impacts on UV spectral actinic flux observed during the International Photolysis Frequency Measurement and Model Intercomparison (IPMMI), J. Geophys. Res., 108, 8545, doi:10.1029/2002JD002731.