Comparison of measured 3.8-microm scattering from naturally occurring aerosols with that predicted by measured...

Recent field measurements of scattered 3.8-microm laser radiation from naturally occurring aerosols were made during a 4-week period in coastal Southern California. Simultaneously, aerosol distribution measurements were made, which, in conjunction with Mie scattering theory, gave estimates of the volume scattering coefficient at the various angles. A comparison shows that (a) calculated volume scattering coefficients generally decrease more rapidly in angle than measurements indicate; (b) on the average, the calculation gives volume backscattering coefficients that are a factor of 2 larger than measured but underpredicts forward scattering by 33%. A second unrelated observation of interest is that volume scattering coefficients in the visible showed 65% correlation with 3.8-microm backscatter (177 degrees ) coefficients.