EUREC4A mission proposal - Elucidating the Role of Cloud-Circulation Coupling in Climate

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Shallow convection in the trade-wind region is the most frequent type of clouds on Earth. How will these clouds react to global warming? This open question is one of the largest uncertainty in determining the climate sensitivity, which is defined as ratio between global temperature increase and CO2 increase. Both coarse-resolution global climate models as well as eddy-resolving models with grid spacing in the order of 100 m provide very different predictions how shallow convection will respond to changed environmental conditions. Comprehensive observations of both the cloud structures and the ambient influencing factors, in particular the large scale dynamics, are needed to advance model development and to constrain climate predictions. The French-German measurement campaign EUREC4A (Elucidating the Role of Cloud-Circulation Coupling in Climate) will face this challenge: The German research aircraft HALO will jointly with the French research aircraft ATR42 collect a unique dataset describing shallow convection east of Barbados from 20 January to 20 February 2020. HALO equipped with an extensive suite of remote sensing sensors onboard will fly high above the clouds to observe its structure and to assess the large-scale dynamical state of the atmosphere by releasing dropsondes along large circles. In parallel, the ATR42 will fly within the cloud layer to measure the cloud geometry and microphysical composition. The experiment will be complemented by research vessels analyzing the ocean-atmosphere exchange and the Barbados Cloud Observatory, which provides a long-term reference point using ground-based remote sensing.