Sulfate Aerosol Properties Derived from Combining Coincident ACE-FTS and SAGE III/ISS Measurements

Combining infrared aerosol transmittance spectra from the Atmospheric Chemistry Experiment Fourier trans -form spectrometer (ACE-FTS) and visible/near infrared extinction information from coincident SAGE III/ISS measurements, the properties of stratospheric sulfate aerosols are derived under various conditions. Assuming a bimodal size log-normal distribution (rather than a monomodal one) is required to properly characterize the spectra. Analysis is performed for enhanced sulfate conditions following two recent volcanic eruptions, the Raikoke eruption in 2019 and the Hunga Tonga-Hunga Ha'apai eruption in 2022, as well as for measurements under background sulfate conditions. The traditional analysis approach of assuming a monomodal distribution likely contributes to the large uncertainties for the impact of sulfate aerosols on climate.