CADDIWA
Clouds-Atmospheric Dynamics–Dust Interactions in West Africa
Abstract
The first overarching objective of the Clouds-Atmospheric Dynamics–Dust Interactions in West Africa (CADDIWA) airborne campaign is to assess dust aerosol related effects, namely the direct radiative effect (DRE), the semi-direct radiative effect (SRE) and the indirect radiative effect (IRE), on atmospheric dynamics in the complex coastal environment offshore of Senegal in different dust load conditions and in a variety of synoptic conditions (monsoon intensity, Saharan heat low intensity and location, …). The second overarching objective is to contribute to the CAL/VAL of the recently launched ADM-Aeolus space mission.
To achieve our goals, we will make use of the very comprehensive, unprecedentedly flown payload on the SAFIRE Falcon 20. For the occasion, the SAFIRE Falcon 20 will be equipped with the RALI system, a sideway pointing lidar, PLASMA, radiometers, dropsondes, field mills, in situ dynamics, thermodynamics and aerosol/cloud microphysics probes. The CADDIWA aircraft campaign, based on the deployment of the SAFIRE Falcon 20 in the tropical environment of Cape Verde, offshore of Senegal from 6 to 25 September 2021, will be part of a larger experimental consortium that will operate under the umbrella of the “Joint Aeolus Tropical Atlantic
Campaign” (JATAC) supported by ESA.. It will be coordinated with the deployment of 2 other aircraft (the DLR Falcon 20) and the NASA DC8, as well as with several ground-based supersites, which will provide complementary observations of interest for our assessment.
Scientific, technical, programmatic context
The CADDIWA project aims investigating cloud-atmospheric dynamics-dust interactions (CADDI) in West Africa, in a region where they are strong, and to date very poorly accounted for in numerical weather prediction (NWP) models. For instance, Vogel et al., 2018 have shown that NWP models have very low skills in tropical Africa. This is because (i) Tropical Africa is characterized by the world-wide largest degree of mesoscale convective organization which is a challenge for convection schemes, (ii) current NWP models struggle to realize the coupling between tropical waves and the mean atmospheric flow as well as
with the advection of dust and MCSs, and (iii) because observational networks are very limited over West Africa.
The project will contribute to enhance knowledge of CADDI in West Africa and, in turn, their representation in research and NWP models as well as assess the worth of new satellitebased observations using a state-of-the-art aircraft instruments mimicking the payload of
space missions launched recently launched or in preparation.
A very challenging payload is envisaged. For the occasion, the SAFIRE Falcon 20 will be equipped with the RALI system, a sideway pointing lidar, PLASMA, radiometers, dropsondes, field mills, in situ dynamics, thermodynamics and aerosol/cloud microphysics probes.
CADDIWA will provide worthy information on how well these missions will monitor winds, aerosols and clouds at different vertical levels in comparison with aircraft measurements and what limits the quality of the retrievals. CADDIWA will be part of larger consortium that will operate under the umbrella of the Aeolus CAL/VAL Tropical Campaign supported by ESA which is scheduled to take place in July 2020 in Cape Verde.
CADDIWA will contribute to the overall Aeolus CAL/VAL effort, but not only, as it has science objectives of its own. Nevertheless, because CADDIWA aims at investigate the link between dust, clouds and the atmospheric circulation, it makes perfect sense to deploy the SAFIRE Falcon at the same time as the two other aircraft (the DLR Falcon 20 and the NASA DC8), as well as with the ground-based supersites, participating to the Aeolus CAL/VAL Tropical
Campaign.
Flights area of interest
- Cabo Verde – Sal
Air bases
Specific instruments on board
- The SAFIRE Falcon 20 which will be equipped with:
LNG lidar (plain backscatter at 532 and 1064 nm, high spectral resolution, Doppler capability and polarization at 355 nm): 37°and nadir pointing (aerosols, wind, ice clouds), - RASTA Doppler cloud Radar (95 GHz) – up to 6 antennas: in-cloud horizontal and vertical wind, cloud μphysics, Horizontally pointing ALIAS lidar (extinction and polarisation at 355 nm),
- IR radiometer CLIMAT (brightness temperature 8-10-12 μm),
- LW/SW up- and down-looking fluxes (broadband),
- Dropsonde launching (profiles of T, p, hum, u, v)
- Aerosol size distribution UHSAS et FSSP 40 nm -1000nm
- Aerosol size distributionFSSP300 0.3µm-20µm
- Cloud droplets size distribution CDP 2-50 μm,
- Cloud droplets size distribution 2DS
- In situ PTU & wind.
Principal Investigator / Project manager
Other participants
CNRS, CNES, Météo-France, LaMP, LISA, LAERO