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During a solar eclipse the solar irradiance reaching the top-of-atmosphere(TOA) is reduced in the Moon shadow. The solar irradiance is commonly measuredby Earth observation satellites before the start of the solar eclipse and isnot corrected for this reduction, which results in a decrease of the computedTOA reflectances. Consequently, air quality products that are derived from TOAreflectance spectra, such as the ultraviolet (UV) Absorbing Aerosol Index(AAI), are distorted or undefined in the shadow of the Moon. The availabilityof air quality satellite data in the penumbral and antumbral shadow duringsolar eclipses, however, is of particular interest to users studying theatmospheric response to solar eclipses. Given the time and location of a pointon the Earth's surface, we explain how to compute the obscuration during asolar eclipse taking into account wavelength-dependent solar limb darkening.With the calculated obscuration fractions, we restore the TOA reflectances andthe AAI in the penumbral shadow during the annular solar eclipses on 26December 2019 and 21 June 2020 measured by the TROPOMI/S5P instrument. In thecorrected products, the signature of the Moon shadow disappeared, but only ifwavelength-dependent solar limb darkening is taken into account. We concludethat the correction method of this paper can be used to detect real AAI risingphenomena during a solar eclipse and has the potential to restore any otherproduct that is derived from TOA reflectance spectra. This would resolve thesolar eclipse anomalies in satellite air quality measurements and would allowfor studying the effect of the eclipse obscuration on the composition of theEarth's atmosphere from space.

Restoring the top-of-atmosphere reflectance during solar eclipses: a proof of concept with the UV Absorbing Aerosol Index measured by TROPOMI