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Infrared radiative effects of desert dust in the Mediterranean during the long dust season of summer 2021

TitoloInfrared radiative effects of desert dust in the Mediterranean during the long dust season of summer 2021
Tipo di pubblicazionePresentazione a Congresso
Anno di Pubblicazione2024
AutoriPelliccia, Giorgia Proietti, Meloni Daniela, Di Iorio Tatiana, Sferlazzo Damiano Massimo, Pace Giandomenico, and Di Sarra Alcide
Data di pubblicazione2024
EditoreAIP Publishing
Conference LocationThessaloniki, Greece

The central Mediterranean during summer 2021 has been characterized by synoptic conditions leading to an extended period with dust transport from the Sahara desert. In particular, very stable and persistent conditions with elevated values of the aerosol optical depth occurred in the second half of June and early July. In this study we integrate ground-based observations to determine the atmospheric conditions and derive the radiative effect produced by the Saharan dust aerosol at the surface in the IR spectral region. As shown by previous studies, desert dust produces a non negligible radiative effect in the IR, which partly offsets that acting in the solar spectral range. The determination of the surface radiative effect requires that the IR irradiance without aerosol is known. The summer 2021 dataset for Lampedusa has been analyzed in order to determine the downwelling IR irradiance without Saharan dust by means of an empirical formula. The application of this formula has allowed to reliably determine the downwelling IR irradiance without dust with an estimated accuracy of about 3 Wm-2; thus, the IR radiative effect was calculated as the difference between the measured irradiance and that estimated with the empirical formula. The mean value of the IR radiative effect (ARF) is 13.4 Wm-2, producing a radiative effect efficiency (FE), i.e. the radiative effect per unit optical depth, of 26.3 Wm-2. The mean estimated uncertainty on ARF is about 30%. We also used MODTRAN6 radiative transfer model to calculate the IR radiative effect in a selected case characterized by high aerosol optical depth. The radiative effect obtained in the selected case is in good agreement with that derived with the empirical method. © 2024 Author(s).

Citation Key12201