Dust Aerosol and Water Vapor Radiative Effects: A Multi-Campaign Analysis of ASKOS and ORCESTRA/PERCUSION Over the Atlantic

Aerosols significantly attenuate solar radiation and influence atmospheric thermodynamic stability, particularly over regions like the Atlantic, impacting Earth's energy budget and climate through radiative heating or cooling. Quantifying these effects is challenging due to aerosol diversity and complexity. For desert dust particles, the difficulty lies in defying their opticalproperties and accurately monitoring their extensive distribution. This study aims to assess the radiative effects of dust aerosols and water vapor (WV), and their impact on atmospheric heating rates, by adopting non-spherical particle shapes and their intrinsic microphysical and optical properties during severe dust events. To achieve this, ground-based, airborne, and satellite observations are employed along with Radiative Transfer (RT) modeling, and more precisely the libRadtran RT package (Mayer and Kylling, 2005; Emde et al., 2016). The study utilizes data from two experimental campaigns – ASKOS and ORCESTRA/PERCUSION – both conducted in the Atlantic region during peak trans-Atlantic dust transport periods, in summers of 2022 and 2024. In the frame of the ASKOS ESA Joint Aeolus Tropical Atlantic Campaign (JATAC), we utilized ground-based remote sensing and airborne in-situ observations, including solar radiation and airborne meteorological profiles. Microphysical properties from UAVs, MOPSMAP (Gasteiger and Wiegner, 2018) and TAMUdust2020 (Saito et al., 2021) scattering databases were used to derive dust optical properties considering a mixture of spheroidal and irregular-hexahedra shapes. Multi-wavelength lidar measurements contributed to the validation of the optical properties and dust vertical distribution. RT simulations incorporated WV concentration, to investigate dust-WV-solar radiation interactions under clear sky conditions. The simulated broadband shortwave radiation was, finally, compared with the ground-based solar radiation measurements. A second case study was performed, leveraging ORCESTRA/PERCUSION campaign (https://orcestra-campaign.org/percusion.html) synergistic airborne measurements. This campaign incorporated a comprehensive suite of airborne instruments, providing, amongst others, radiationmeasurements, meteorological profiles, and extensive lidar measurements. Radiation at the top of the atmosphere (TOA) from the EarthCARE ESA mission supported comprehensive closure studies at TOA and at aircraft level.