EUREC<sup>4</sup>A

Abstract

Abstract. The science guiding the EUREC4A campaign and its measurements are presented. EUREC4A comprised roughly five weeks of measurements in the downstream winter trades of the North Atlantic – eastward and south-eastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or, or the life-cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso (200 km) and larger (500 km) scales, roughly four hundred hours of flight time by four heavily instrumented research aircraft, four global-ocean class research vessels, an advanced ground-based cloud observatory, a flotilla of autonomous or tethered measurement devices operating in the upper ocean (nearly 10000 profiles), lower atmosphere (continuous profiling), and along the air-sea interface, a network of water stable isotopologue measurements, complemented by special programmes of satellite remote sensing and modeling with a new generation of weather/climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from Brazil Ring Current Eddies to turbulence induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice.

Measurements from the RV <i>Ronald H. Brown</i> and related platforms as part of the Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC)

“…A Marine Atmospheric Emitted Radiance Interferometer (M-AERI) was mounted on the port side O2 deck rail (two levels above the main deck) (Minnett et al, 2001). It measured the spectra of infrared emission from the sea surface and atmosphere for the derivation of skin sea surface temperature and lower troposphere profiles of temperature and humidity (Szczodrak et al, 2007). A W-band Doppler vertically pointing cloud radar was housed in a container on the O2 deck for the measurement of vertical profiles of non-precipitating and lightly precipitating clouds (Moran et al, 2012).…”

“…ATOMIC took place in the boreal winter to study shallow convection and low, liquid clouds at a time of year when other cloud types are mostly absent. ATOMIC is the United States complement to the Elucidating the Role of Clouds Circulation Coupling in Climate Campaign (EUREC 4 A) (Bony et al, 2017;Stevens et al, 2021). Together, ATOMIC and EUREC 4 A involved four research vessels, four research aircraft, land-based observations from Barbados, and uncrewed seagoing and aerial vehicles.…”

Integrated water vapour content retrievals from ship-borne GNSS receivers during EUREC<sup>4</sup>A

“…Despite these limitations, the quality of sea-borne IWV retrievals is promising, even though it is still lower than that obtained for terrestrial stations. Compared to conventional meteorological instruments, the root mean square (rms) of differences generally varies between 2 and 3 kg m −2 (Fujita et al, 2014;Shoji et al, 2017;Wang et al, 2019;Liu et al, 2019), while the rms of differences with numerical weather prediction models ranges from 1 to 3 kg m −2 (Boniface et al, 2012;Wang et al, 2019;Fourrié et al, 2019).…”

JOANNE : Joint dropsonde Observations of the Atmosphere in tropical North atlaNtic meso-scale Environments

“…Most circles were flown along a fixed circular path, called the EUREC 4 A-circle (Stevens et al, 2021), which was planned with the centre coordinates as 57.72°W, 13.30°N and a diameter of roughly 220 km. The location of the sonde launches shown in Fig.…”