EUREC4A Campaign, Cruise No. MSM89, 17. January - 20. February 2020, Bridgetown (Barbados) - Bridgetown (Barbados), The ocean mesoscale component in the EUREC4A++ field study

The MSM89 expedition of Maria S Merian was a contribution to the international research initiative EUREC4A (www.eurec4a.eu). The cruise was carried out in concert with the M161 campaign on RV METEOR (Germany) and the EUREC4A-OA campaign on NO L’ATALANTE (France). Airplane and drone operations as well as well as continuous observations from the ground-based site on the Island of Barbados (BCO) were considered during the MSM89 campaign. Moreover, the cruise was coordinated with ships and Saildrone© operations in the context of the US American ATOMIC project. The overall goal of the EUREC4A field campaign was to collect observational data that will enable research on dynamic and thermodynamic processes in the atmosphere and ocean that will bring the understanding of the role of clouds in the climate system to a new level. MSM89 had its focus on the ocean/atmosphere coupling across ocean mesoscale vortices. For this purpose, both ocean and atmosphere profile measurements were carried out to observe the temporal evolution and spatial heterogeneity of the atmospheric and oceanic boundary layer. Autonomous observing platforms (underwater glider) and a ship towed platform (Cloudkite) augmented the ship-based observations. Incubation experiments were performed to determine Nitrogen fixation rates, the gas exchange for carbon dioxide and oxygen uptake

Ship- and island-based atmospheric soundings from the 2020 EUREC⁴A field campaign

International audienceTo advance the understanding of the interplay among clouds, convection, and circulation, and its role in climate change, the EUREC4A and ATOMIC field campaigns collected measurements in the western tropical Atlantic during Jan-uary and February 2020. Upper-air radiosondes were launched regularly (usually 4-hourly) from a network consisting of the Barbados Cloud Observatory (BCO) and four ships within 51–60 ◦W, 6–16 ◦N. From January 8 to February 19, a total of 812 radiosondes measured wind, temperature and relative humidity. In addition to the ascent, the descent was recorded for 82 % of the soundings. The soundings sampled changes in atmospheric pressure, winds, lifting condensation level, boundary layer depth, and vertical distribution of moisture associated with different ocean surface conditions, synoptic variability, and mesoscale convective organization. Raw (Level-0), quality-controlled 1-second (Level-1), and vertically gridded (Level-2) data in NetCDF format (Stephan et al., 2020) are available to the public at AERIS (https://doi.org/10.25326/62). The methods of data collection and post-processing for the radiosonde data set are described here