Development of a European HSRL airborne facility – MULTIPLY

MULTIPLY – Development of a European HSRL airborne facility, is a ESA-ESTEC project which proposes the development of a novel multi-wavelength HSRL system (3b + 2a + 3d) for airborne operation, capable of retrieving the aerosol extinction, backscatter and depolarization profile distributions. The system will be designed to be especially compact and robust, both optically and mechanically. This will be addressed during the Phase A of the project.

The integration of the HSRL system on board of a EUFAR (EUropean Facility for Airborne Research) research aircraft will be addressed during the Phase B of the project. The new lidar system operation will be tested for in flight operation and further validated during a dedicated experimental campaign that will take place over a number of European lidar stations, members of EARLINET (European Aerosol Research Lidar NETwork).

The present efforts in climate modeling are far from being sufficient for providing realistic numbers on the influence of anthropogenic aerosols on the state of the atmosphere (e.g. IPCC 2013; CCSP report: Chin et al., 2009; Houghton et al., 2007). To improve this unsatisfactory situation, future space-borne aerosol lidar missions must allow an accurate characterization of the aerosol in terms of aerosol type, vertical layering, light extinction and absorption properties, and microphysical properties including a proper monitoring of the long-range transport of anthropogenic particles like haze or smoke, natural aerosols like volcanic ash, mineral dust, marine particles, and especially mixtures of the mentioned aerosol types on a regional to hemispheric scale.

The airborne HSRL (3b + 2a + 3d) will enable:

• A refined aerosol typing and discrimination of highly depolarizing cirrus clouds from strongly depolarizing aerosol particles, e.g. mineral dust and fresh volcanic ash, weakly depolarizing forest-fire smoke, and non-depolarizing pollution (for example sulfate particles), based on its 3d capabilities;
• The retrieval of profiles of microphysical particle properties (size distribution, complex refractive index, volume and surface concentrations) as well as of the refractive index characteristics (absorption, scattering, SSA) leading ultimately to the quantification of the aerosol radiative forcing (accuracy better than 1 W/m²), based on its 3b + 2a capabilities;
• Direct comparison of the lidar products to the space-borne systems (ADM-Aeolus, EarthCARE) when the aircraft flies/crosses underneath the orbit of the space lidar;
• Synergies / cross-validation against airborne in situ instrumentation (particle size distribution, chemical composition and optical properties – e.g. scattering and absorption coefficients).