Refractive indices of aerosols in the upper troposphere and lower stratosphere

A new instrument for simultaneously measuring aerosol diameter from 0.4–10 µm 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°S to 50°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.