Contribution of clouds to radiative diabatic heating and cooling, from synergy of airborne lidar, radar, and imager observations

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Clouds can be organized in different ways: from randomly scattered shallow cumulus clouds up to mesoscale systems which can influence global dynamic processes by diabatic heating and cooling which is a limiting factor in current weather prediction systems. To fill gaps in our knowledge of the spatial and temporal distribution of diabatic heat sources and sinks, a 3D characterization of cloud macro- and microphysics is indispensable.Aim of this proposal is to add our spectral visible and near infrared imager specMACS to the NARVAL- 2/NAWDEX instrumentation, which is strongly supported by both mission teams (see umbrella proposals). Similar to the upcoming EarthCARE satellite mission (scheduled 2018), the payload would combine vertical sounding radar and lidar with passive spectral imaging in parallel viewing direction. The imaging component would complement the nadir-viewing active sensors with important information on representativity across flight-track and add the possibility to retrieve cloud microphysical properties. The sensor was already successfully flown on the HALO mission ACRIDICON 2014 with horizontal viewing direction.With the completed instrumentation we want to answer the following research questions:> How large is the information gain by adding the imager to the lidar/radar measurements?> How do cloud microphysics connect with water vapor concentrations along Warm Conveyor Belts?> How do cloud macro- and microphysics evolve during the lifetime of a cloud system?> How large is the cloud contribution to diabatic radiiative heating and cooling? To answer these questions, we apply for two PhD projects:Project 1 will focus on spatial distributions of cloud microphysics of convective clouds through all stages of their life-cycle. Thermodynamic phase, effective radius, and optical thickness will be derived through adaptation of existing retrievals. Important improvements are expected by including cloud geometry information for the complete imager swath derived from a combination of radar, lidar, and imager based methods.Project 2 will focus on the microphysics of high ice clouds. Ice water content, particle size, and particle concentration will be derived using a synergistic lidar/radar/imager retrieval. Spectral radiance observations will be added to an existing lidar/radar method as an additional constraint and a means to extend information from the along-track line to a wider swath around the flight path. Both projects will use their results to reconstruct three dimensional cloud macro- and microphysics and, based on these, will quantify how strong clouds act as a source and sink of diabatic heat (radiative heating and cooling and latent heat). They therefore contribute directly to research area B "Formation, Evolution and Radiative Effects of Clouds and Precipitation" of the HALO priority program and are important contributions to the central goals of NAWDEX and NARVAL-2.