The ASKOS experiment for desert dust science applications

The Joint Aeolus Tropical Atlantic Campaign (JATAC) has been conducted in summer/autumn 2021 at the Cape Verde, with the main aim to provide reference measurements for the validation of the Aeolus products and to collect information for ESA’s upcoming missions such as EarthCARE. Next to an impressive airborne fleet from AVATAR-T and CADDIWA components, situated on the island of Sal, intensive ground-based remote sensing and airborne in situ measurements performed on and above Mindelo in the framework of the ASKOS experiment. Specifically, a full ACTRIS remote sensing super site was deployed in Mindelo, Sao Vicente, including a multiwavelength-Raman-polarization lidar PollyXT, an AERONET sun photometer, a Scanning Doppler wind lidar, a microwave radiometer and a cloud radar. Additionally, ESA’s novel reference lidar system EVE, a combined linear/circular polarization lidar with Raman capabilities, was deployed, which can mimic the observations of the space-borne lidar onboard AEOLUS. Moreover, for 2 weeks in September, a light-weight airplane performed in-situ measurements in the aerosol layers around the island, in altitudes up to 3 km.

Here, will quickly introduce the measurements and present first results on the aerosols observed. Focus is given in the intensive September period, where very different aerosol conditions were observed above and around Mindelo. Usually, the marine boundary layer was up to 1 km and was topped by the Saharan Air Layer (SAL) reaching up to 6 km altitude. Three different dust events were observed. The first one had significant spatiotemporal homogeneity, which is ideal for Cal/Val objectives. The second one had strong horizontal and vertical gradients in composition and concentration and a significant anthropogenic component, making it ideal for an in-depth analysis with the synergistic dataset. After 22 of September, volcanic aerosols from the la Palma volcano were captured, mixed in the local boundary layer and partly above in the dust layer of the 3^rd dust event and relevant Aeolus overpass.

As a next step, science application studies are anticipated, using the wealth of information provided by ASKOS and JATAC campaigns, including already the following applications in the framework of ESA and EU projects:

• Long-range transport of the coarse and giant dust particles;
• Impact of non-sphericity on dust transport;
• Impact of electric charge on dust dynamics;
• Dust particle orientation;
• Impact of dust on radiation and dynamics;

Impact of dust deposition on ocean biogeochemistry;