November 30, 2025Open Access

Characterizing trade‐wind shallow convection regimes in the open sea with a synergy of ship‐based vertical profiling observations

Key Points

Precipitation in trade-wind shallow convection affects the water cycle and thermodynamic conditions, showing a clear disparity between cloud types.
Congestus clouds, containing three times more liquid water than shallow clouds, precipitate more frequently with 71% occurrence compared to 7% in shallow clouds.
Remote sensing techniques employed aboard the RV Maria S. Merian during 2020 provided vital insight into the vertical velocity and cloud dynamics.
This analysis highlights the need for high-resolution modeling to further understand precipitation life cycles and their impact on climate.

Abstract

Abstract Precipitation occurs frequently in observed shallow convection across the Northern Atlantic Trades. Despite its central role in shaping the water cycle, it remains challenging to quantify how much and when precipitation occurs, and how precipitation shapes its immediate thermodynamic and dynamic environment. Here we make use of the synergy of active profiling remote sensing aboard the RV Maria S. Merian during the Elucidating the Role of Clouds–Circulation Coupling in Climate (A) field study in 2020. We investigate the thermodynamic and dynamic conditions before, during, and after precipitation using a statistical approach. By distinguishing between shallow and congestus profiles according to observed cloud geometrical thickness, we find that congestus clouds occur more frequently than shallow (21% and 9% of profiles), contain three times more liquid water (60 vs. ), and precipitate more often (71% vs. 7%). Shallow clouds, as a precursor stage to congestus, show little variability during the day, while congestus clouds maximize at night. Convection is initiated in shallow clouds located in patches of humidity moister than the clear‐sky state, sometimes coupled with sea‐surface induced changes in the sub‐cloud layer. At the congestus stage, microphysical and thermodynamic processes trigger further cloud and precipitation growth in the cloud layer. In shallow conditions, virga induce a cooling and moistening anomaly in the sub‐cloud layer that fosters cold‐pool development. In precipitating congestus clouds, dry, cold air is found in sub‐cloud and cloud layers. By analyzing a case study with multiple datasets, we recorded a variation in the vertical velocity field at cloud top associated with the development of precipitation and connected with a change in mesoscale cloud patterns. The statistics presented, as well as the case study, can serve as a benchmark dataset for studying the precipitation life cycle in high‐resolution modeling.

Read Full Paperexternally

Mark Helpful

Bookmark

Relay

View Full Paper