A better quantification and physical understanding of how clouds respond to warming, and hence Earth’s Equilibrium Climate Sensitivity is recognized as one of the Grand Challenges of Climate Science. Research over the past decades has advanced to the point that testable hypotheses have been articulated, and these motivate “Elucidating the Role of Cloud-Circulation Coupling in Climate” (EUREC4A). The EUREC4A field campaign in January and February 2020 in the vicinity of Barbados will elucidate how the macrophysical properties of trade-cumuli depend on the dynamic and thermodynamic properties of the environment in which the clouds form. As two primary objectives, we will
- Quantify cloud macrophysical properties as a function of the large scale environment in the winter trades of the North Atlantic, and
- Provide a reference data set for modelling and remote sensing clouds and circulation in the trades. More specifically, EUREC4A aims to answer the following key questions of climate modelling and prediction:
- What controls the convective mass flux, mesoscale organization, and depth of shallow clouds?
- How does the cumulus cloud amount in the trade wind boundary layer vary with turbulence, convective mixing and large-scale circulations, and what impact does this variation have on the atmospheric radiation field?
EUREC4A will build on the NARVAL program of measurements (NARVAL and NARVAL 2) to use HALO to characterize both the large-scale (30–50,000 km2) environment in which clouds form, and the radiative properties of the clouds therein. What is new about EUREC4A is the combination of the HALO measurements with other observation systems. HALO and the French research aircraft ATR-42 are the core platforms of EUREC4A. The French ATR-42 operated by the “Service des Avions Francais Instrumente´s pour la Recherche en Environnement” (SAFIRE), which will fly in the shallow cloud layer to constrain cloud macrophysical properties, in-situ microphysics and turbulent mixing processes.