Three-dimensional pathways of Saharan dust export over the North Atlantic during the CADDIWA field campaign

International audienceMassive amounts of desert dust uplifted over the Sahara are exported over the North Atlantic. They play a major environmental role over this region, impacting the Earth radiative budget, atmospheric dynamics and thermodynamics, cloud properties, atmospheric composition, and biogeochemistry. These multiple impacts of Saharan dust can also affect the evolution of mesoscale convective systems (MCS) formed over West Africa that may lead to the formation of tropical cyclones over the North Atlantic. A better understanding of these aspects, also influenced by African Easterly waves, is the primary objective of the “Clouds-Atmospheric Dynamics-Dust Interactions in West Africa - CADDIWA ” field experiment that took place on September 2021. The current presentation will provide a comprehensive description of the three-dimensional (3D) distribution of Saharan dust and its pathways of export over the North Atlantic during CADDIWA. This will be analysed with respect to the location and evolution of the MCS travelling over the region. This characterisation will be done using a suite of observations which will be compared with dust simulations. The objective is to analyse the difference in terms of abundance and 3D distribution of dust between the cases where MCSs lead to cyclogenesis and those not evolving that way.The ensemble of datasets describing the Saharan dust distribution will be inter-compared and their consistency verified. Twice-daily satellite thermal infrared hyperspectral measurements from IASI will be used to document the 3D distribution of desert dust for cloud-free conditions using the AEROIASI approach (Cuesta et al., 2015; 2020). Further details will be provided by nadir-pointing lidar measurements from AEOLUS and CALIOP space sensors, and from the RALI airborne instruments, in terms of transects of aerosol profiles and winds. In addition to aerosol backscatter profiles, AEOLUS and LNG-RALI will provide aerosol extinction profiles, provided their high spectral resolution capabilities. Observations from MODIS and VIIRS of aerosol optical depth will inform on the horizontal distribution of desert dust. Airborne in situ measurements of the size distribution and intensive optical properties of desert dust, such as the angstrom exponent, will be compared to those used as a priori properties of dust within the satellite dust retrievals (particularly for IASI). These satellite and airborne measurements will be confronted with simulations from the Meso-NH and WRF-CHIMERE, contributing with an all-sky and hourly 3D description