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What does RALI allow one to characterise ?

Among the different cloud properties which are required to characterise a cloud and its interactions with radiation or its representation in models, this active remote sensing combination allows the following cloud parameters to be documented:

  • The macrophysical (or «morphological») properties of clouds and aerosols - the type of particle (cloud or aerosol), the top, base and thickness of cloud and aerosol layers, which are essential characteristics to estimate the radiative budget.

  • The microphysical and radiative properties of clouds and aerosols - The type of aerosol, the cloud phase (liquid, solid, mixed) and the layer-mean or vertically-resolved microphysical properties for each water phase can be obtained either via the lidar alone, the radar alone, or the combination.

Want to know more about microphysical and macrophysical cloud/aerosols properties ? RALI measurements are perfect for you !

RALI is not alone

We have very active collaborations with Lamp (Laboratoire de Métérologie Physique), and most of the time, RALI is associated with in-situ measurements. The capability of combining remote sensing measurements is an amazing opportunity to cover a very wide range of scales for cloud studies. In-situ measurements are ideal for studying very local and fine cloud processes and we use RALI measurements to access to larger scales. In-situ measurements are limited to the altitude of the aircraft while radar and lidar give access to vertical profiles of cloud properties. By providing in-situ expertise and measurements, Lamp give us the opportunity to validate and improve our retrieval techniques. On the other hand, our remote sensing measurements bring extra information which can complete in-situ measurements. For instance when no bulk IWC measurements are available the combination of Particle size distribution and reflectivity factor allows one to infer mass size relationships.

RALI as a spaceborne demonstrator/validator

RALI is also an excellent spaceborne measurement validator and demonstrator. RALI has been used to validate A-Train (CloudSat/CALIPSO) measurements and retrievals. RALI is currently the only airborne platform with a 95GHz Doppler radar and a high spectral resolution lidar at 355nm, which makes it a perfect demonstrator of EarthCare measurements.

Examples of RALI results

  • Polar clouds : Here is an example of RALI results during the POLARCAT campaign.
  • Tropical clouds : Illustration of the RASTA measurements for characterising African anvils during the Megha-Tropique validation campaign.