EUREC4A-iso: Full collection of isotopic measurements in water vapor, precipitation, and seawater during EUREC4A

In early 2020, an international team set out to investigate trade wind cumulus clouds and their coupling to the large-scale circulation through the field campaign EUREC⁴A: ElUcidating the RolE of Clouds‐Circulation Coupling in ClimAte. Among a number of innovative observational strategies, EUREC⁴A deployed a large network of water isotopic measurements collectively known as EUREC⁴A-iso. Measurements of water vapor concentration and water vapor isotope ratios were made with seven laser-based analyzers. Two analyzers made collocated near-surface measurements at the Barbados Cloud Observatory (BCO), two made airborne measurements to the east of Barbados aboard the French ATR-42 and the US NOAA WP-3D Orion, and three made near-surface measurements over the open ocean from aboard the French research vessel <i>L'Atalante</i>, the German research vessel <i>Meteor</i>, and the US NOAA research vessel <i>Ronald H. Brown</i>. These three ships also collected rainwater and seawater for isotopic analysis. In addition, precipitation was collected for isotopic analysis at the BCO and from aboard the German research vessel <i>Maria S. Merian</i>. The aircraft regularly measured water vapor isotope ratios between 150 m above sea level and the mid-free troposphere. Most seawater samples were taken within 10 m of the surface; however, some were taken at several km depth.

In addition to the in-situ data, the EUREC⁴A-iso collection includes remotely sensed H₂O-HDO or H₂O-&delta;D pairs from the satellite-borne instruments IASI and TROPOMI. These water vapor data have been repackaged into custom subsets that cover a large region around Barbados for the period in which the 2020 field campaign occurred. Even though the remote sensors exhibit vastly different sensitivities to the atmosphere than the isotopic analyzers deployed during EUREC⁴A, they provide large-scale spatial and temporal context for the in-situ data, thus supporting efforts to understand shallow convective processes and their role in climate.

All field data from the campaign time period are publicly available even if affected by known biases, as is the case for high-altitude aircraft measurements, one of the two BCO water vapor time series, and a select number of rain and seawater samples from the ships. Full descriptions of the in-situ and remotely sensed measurements, including information about their post-processing corrections, uncertainty characterizations, and quality-control flags, are provided in Bailey et al. (2022).