Moisture export by shallow convective mixing during EUREC4A

In 2020, the EUREC⁴A (ElUcidating the RolE of Clouds-Circulation Coupling in ClimAte) field mission set out to investigate the role of shallow convective mixing in regulating trade cumulus and their influence on global climate. Recent results from this mission refute the idea that shallow convective mixing reduces cloudiness, as previous studies had argued. Instead, they suggest that shallow convective mixing is positively correlated with cloudiness when both are modulated by mesoscale circulations. Here, we provide independent evidence that further substantiates these findings. Using the unprecedented collection of water isotopic data sampled during EUREC⁴A, we derive estimates of total moisture exported from the sub-cloud layer by shallow convective mixing. We also derive vertical profiles of exported sub-cloud layer moisture, which allow us to investigate how shallow convective mixing alters the vertical structure of thermodynamic quantities and clouds. We show a strong association between the amount of moisture exported, the top-heaviness of the exported-moisture profile, the trade wind inversion height, and the average cloud top altitude. All increase when large cloud decks are present, indicating a role for mesoscale convective organization. We extend the analysis with remotely sensed isotope ratios in order to investigate the associations between mixing, moisture export, and cloudiness on larger scales (in both time and space) and to examine the conditions that favor convective organization at the mesoscale.