EUREC4A, the Field Study, is a European initiative with a US contribution through ATOMIC Opens external link in current window.  It is a cap-stone field study of World Climate Research Programme's Grand Science Challenge on Clouds, Circulation and Climate Sensitivity. EUREC4A will take place between 20 January and 20 February 2020 with operations based out of Barbados.

EUREC4A aims at advancing understanding of the interplay between clouds, convection and circulation and their role in climate change: How resilient or sensitive is the shallow cumulus cloud amount to variations in the strength of convective mixing, surface turbulence and large-scale circulations? How do the radiative effects of water vapor and clouds influence shallow circulations and convection? What are the implications for the spatial organization of clouds and convection in the tropics, and for climate sensitivity?

To address these questions the core, and presently supported, EUREC4A measurements will focus on quantifying how cloud amount in shallow cumulus layers responds to changes in the large-scale environment, and how shallow clouds affect the radiation field and contribute to convective aggregation. The measurements will also test retrievals of cloud and atmospheric properties, and numerical simulations of shallow cumulus cloud regimes by large-eddy simulation, weather prediction and climate models. Through international cooperation complementary objectives could be explored. These range from investigations of the role of ocean mesoscale eddies in air-sea interactions and the organization of shallow clouds, to the much broader question of the dynamics of the Atlantic Tropical Convergence Zone.

The nucleus for the EUREC4A Field Study involves the deployment of two research aircraft (the German HALO and the French ATR42), an array of research vessels, advanced ground based remote sensing, a new generation of sophisticated satellite remote sensing and state-of-the-art turbulence-resolving modelling (100 m, over thousands of km). These operations build on a decade of measurements in the tropical Atlantic, initiated with the establishment of the Barbados Cloud Observatory in 2010, and continued with two aircraft campaigns with HALO: NARVAL in December 2013, and NARVAL2 in August 2016 (information about these experiments is provided here).

EUREC4A operations will focus on an area over the shelf oceans east of Barbados (57 W 13 N) for a six week period between 12 January and and 23 February 2020, with aircraft operations between 20 January and 20 February 2020. More information about EUREC4A is available here [link to the EUREC4A paper].

An exciting component of EUREC4A is that high resolution modelling will be performed in support of field operations. For NARVAL2, through the DWD sponsored HErZ cooperation with MPI-M, 2.5 km cloud resolving simulations were being performed over the entire tropical Atlantic. These simulations included a 1.25 km nest over the western Atlantic and a yet finer (300 m) simulation nest over the area of flight operations. A prototype simulation, showing the wind field is illustrated in the animated gif below. During EUREC4A we anticipate being able to perform 300 m resolution simulations over the entire domain with finer (50-100 m) nested simulations over the flight area. Link to the DKRZ cloud storage system.

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