Limitations of AERONET SDA product in presence of cirrus clouds

Highlights: • Total irradiance (direct plus diffuse) was computed for various aerosol plus cloud models for a sun/sky radiometer with the full field of view of 1.2° that corresponds to AERONET instrument. • Synthetic data demonstrate that application of SDA to cloud contaminated measurements of aerosol optical depth can produce significant errors in the apparent optical depth fine mode retrievals. • SDA retrievals can be affected when applied to a mixture of fine dominated aerosol and mineral dust aloft. The paper discusses certain limitations on applicability of Spectral Deconvolution Algorithm (SDA) to aerosol optical depth spectral measurements contaminated by cirrus clouds. Analysis of the synthetic data demonstrates that application of SDA to cloud contaminated measurements can produce significant errors in the apparent optical depth fine mode retrievals. Such application can produce results that just look reasonable and physically admissible but in fact can be relatively far from the truth and therefore can be misleading.