Refractive, indices of aerosols in the upper troposphere and lower stratosphere

A new instrument for simultaneously measuring aerosol diameter from 0.4 - 10 mu m and the refractive index between 1.30 - 1.60 has recently been flown on the NASA ER-2 aircraft during a stratospheric measurement campaign. Average stratospheric refractive indices varied from 1.40 to 1.42 over a latitude range from 70 degrees S to 50 degrees N and from 1.34 to 1.46 over a vertical range from 4 - 20 km. The measured stratospheric refractive indices do not agree well with theoretical predictions and vertical profiles suggest the presence of non-spherical or absorbing particles in the altitude range of 7 - 9 km.