HYGEOS participated in the 10 years of AERIS

AERIS is one of the four French Earth Observation data centres integrated in the Data Terra research infrastructure. It collects and processes atmospheric observations acquired by ground-based instruments, satellites, balloons, aircraft and drones. AERIS data includes all atmospheric components that are disseminated to the scientific community. For many years now, HYGEOS has developed a close partnership with the AERIS/ICARE data service centre.

Recently, HYGEOS has created dynamic masks of Deep Convective Clouds (DCC) generated, at the acquisition time of the sun-synchronous satellite, using concomitant observations of geostationary sensors. Furthermore, many properties of extreme DCC are retrieved, among them the statistics of the optical depth, of the effective radius of cloud top, of the particles size or the temperature of the cloud top. The DCC are used by CNES for the absolute calibration of visible and near-infrared bands of Sentinel-2/MSI and Sentinel-3/OLCI sensors. Selecting the DCCs with geostationary sensors observations allows a global coverage of the Earth. This ensures a lower uncertainty than other absolute calibration methods.

HYGEOS has also developed, in collaboration with SPASCIA, a software to detect on an automated way the extreme atmospheric events and classify the plumes (biomass fires, volcanoes, urban pollution, …). The methodology relies on the Principal Analysis Component of Level 1 measurements of hyperspectral sounding interferometer. This detection is essential for warning systems. The software is currently in validation and acceptance phase. Then, in a first time, a daily map of detected events will be available on the AERIS portal. In a second time, the products will be available at the AERIS/ICARE data service centre. This work has been presented as a poster at the “10 years of the AERIS data” conference on 27-28 January 2025.

In addition, HYGEOS supports continuously the AERIS/ICARE data service centre with the secondment of HYGEOS expert, C. Tétard. In particular, he manages the software implementing the algorithm BASIC-Evolution to retrieve the vertical profiles of aerosol extinctions, mass concentrations and lidar ratio from the synergetic combination of lidar and in-situ measurements of photometers, aethalometers and nephelometers. The data of the lidar of the Meteo-France network as well as of the Aerosol, Cloud, Trace gases Research InfraStructure over France (ACTRIS-FR) network are operationally processed by this algorithm relying on a classical Klett Fernald inversion. This addresses environmental challenges linked to the air quality by identifying the nature of aerosols and monitoring the plumes. Results were presented as a poster at the “10 years of the AERIS data” conference on 27-28 January 2025.

HYGEOS expert is also in charge of the software implementing the Generalized Aerosol Retrieval from Radiometric and Lidar Combination (GARRLIC) algorithm, developed by the Laboratoire d’Optique Atmosphérique, based upon the Generalized Retrieval of Aerosol and Surface Properties (GRASP) algorithm. This synergetic approach combines primary data obtained from sun/sky photometer (spectral extinction aerosol optical depth and spectral radiance from almucantar measurement) and elastic attenuated backscatter lidar profiles at one or several wavelengths. The objective is to produce as much as possible aerosol optical and micro-physical properties such as extinction, absorption, scattering, single scattering albedo profiles, angstrom exponent, refractive index, … In AERIS/ICARE data service centre, about 25 ACTRIS lidars in France and Europe are operationally exploited by this methodology. Output products will be accessible through the ACTRIS Data Center portal.