The Max Planck Cloud Kite

Abstract

Most of the Earth's atmosphere is covered with clouds, which significantly affect incoming and outgoing radiation and thus the Earth's energy balance. Clouds are a source of considerable uncertainty in weather and climate models. Their size ranges from submillimeters, where cloud microphysics is important, to hundreds of kilometers, where they affect weather and climate. The complex coupling of cloud and turbulent flow dynamics at these scales makes clouds difficult to understand. In addition, several long-standing important puzzles, such as the existence and/or presence of cloud holes (regions without droplets) and the sharpness of cloud boundaries, remain unsolved. Given the high Reynolds numbers in atmospheric clouds (Re~10^6-10^9), laboratory-generated flows (with few exceptions) and direct numerical simulations are not yet capable of achieving cloud-like flow dynamics. Therefore, field studies and, in particular, airborne measurements performed far from the Earth's topographic influences can approach the correct range of parameter space relevant to naturally occurring clouds.We have developed the Max Planck CloudKite, which consists of a balloon-kite aerostat and a suite of scientific instruments for simultaneous measurements of aerosols and turbulence features in the atmospheric boundary layer and in clouds. Cloudkite is an independent platform capable of characterizing the atmospheric boundary layer and low-lying clouds within the boundary layer (<2 km) at almost any location on Earth. It has been successfully deployed in remote regions of the Atlantic aboard research vessels and also in northern Finland within the Arctic Circle. The cloud-resolving probe is equipped with Particle Image/Tracking Velocimetry (PIV/PTV), Inline Holographic Particle Imaging, Fast Cloud Droplet Probe (FCDP), multi-hole pitot tubes, and humidity, temperature and pressure sensors. In addition, 10 WinDart units, including aerosol spectrometers and 3D ultrasonic sensors, are installed on the tether to fully characterize the atmospheric boundary layer and clouds simultaneously. Overall, the results will greatly improve our understanding of cloud evolution and spatial structure, as well as cloud-aerosol interactions, which is urgently needed to address climate change challenges.