Trade cumulus cold pool properties during the ATOMIC and EUREC4A field campaign season

Abstract:

In the trade cumulus regime, cold pools appear as (nearly) cloud-free areas measuring tens to approximately 200 km across. They form when evaporating precipitation generates downdrafts that descend to the surface and spread out. The cooler, moister, and denser surface air suppresses buoyancy-driven turbulence and the re-emergence of trade cumulus clouds in the cold pool for approximately one day. The gust front associated with the outward spread of the cold pool can mechanically lift surface air parcels and initiate convection along the cold pool periphery, creating characteristic arcs or rings of cumulus clouds. By redistributing moisture from moist to dry patches and suppressing convection in the moist patches, cold pools may oppose convective aggregation. The relationship of cold pools to cloud cover is a topic of ongoing research.

The Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) was designed to study the relationship between shallow convection and large-scale meteorological and oceanic conditions in the trade cumulus regime. It took place, together with its European counterpart, the EUREC⁴A field campaign, in January-February 2020 in the Atlantic Ocean east of Barbados. We use satellite imagery from sun-synchronous (Aqua and Terra) and geostationary (GOES series) satellites to study the occurrence and properties of cold pools east of Barbados in the season of the ATOMIC and EUREC⁴A field campaigns. We use ERA5 reanalysis data to determine large scale conditions that promote and inhibit the presence of cold pools, and attempt to establish correlations and mechanistic relationships between the large scale conditions and cold pool properties.