OMI aerosol measurements: AI (OMI Aerosol Index)
The aerosol index is a measure of how much the wavelength dependence of backscattered UV radiation from an atmosphere containing aerosols (Mie scattering, Rayleigh scattering, and absorption) differs from that of a pure molecular atmosphere (pure Rayleigh scattering).
Quantitatively, the aerosol index AI is defined to be
AI = 100 log10( I360Meas / I360Calc )
where I360Meas = the measured 360 nm OMI radiance
and where I360Calc = the calculated 360 nm OMI radiance for a Rayleigh atmosphere
Under most conditions, the AI is positive for absorbing aerosols and negative for nonabsorbing aerosols (pure scattering).