The Max Planck CloudKite (MPCK): High-Resolution Airborne Measurements of Turbulence and Cloud Microphysics

Abstract. We present the airborne Max Planck CloudKite (MPCK) platform, an instrumented tethered aerostat for atmospheric and cloud research, together with its first dedicated measurement system, the Advanced Max Planck CloudKite (MPCK⁺) instrument, designed for high-resolution observations of cloud microphysics and turbulence up to 2 km above ground level. The platform and instrument design are described, and their performance is evaluated through laboratory characterisation, wind-tunnel experiments, and multiple field campaigns over land and aboard research vessels. These evaluations also include assessments of mounting strategies and flight stability. The MPCK⁺ instrument combines advanced airborne imaging techniques: inline holography, which characterises particle size, concentration, and shape in three dimensions, and particle image velocimetry (PIV), implemented here for the first time in an in-situ airborne setting. Together, they enable co-located, high-cadence observations of cloud microphysics and turbulence. Intercomparisons with conventional probes (e.g. cloud droplet probes and pitot tubes) show consistent measurements of bulk quantities, while MPCK⁺ uniquely provides spatially resolved, co-located particle and flow fields, enabling direct observation of localised cloud microphysics–turbulence interactions inaccessible to conventional non-imaging instrumentation. Field performance evaluations demonstrate robust measurements of droplet size, concentration, and turbulence properties across a wide range of cloud conditions. These results demonstrate that the MPCK platform and MPCK⁺ instrument provide an advanced observational capability for studying cloud microphysics–turbulence interactions, bridging micrometre-scale resolution with continuous sampling over tens of kilometres.