Quantifying the mixing of trade-wind cumulus during the NEPHELAE-EUREC4A field campaign with remotely piloted aircraft
Maury, Nicolas ; Roberts, Gregory C. ; Couvreux, Fleur ; Verdu, Titouan ; Narvor, Pierre ; Lacroix, Simon ; Hattenberger, Gautier
During the Network for studying Entrainment and microPHysics of cLouds using Adaptive Exploration (NEPHELAE)-ElUcidating the RolE of Cloud-Circulation Coupling in ClimAte (EUREC4A) field campaign in January and February 2020 in Barbados, remotely piloted aircraft (RPA) were implemented to characterise the structures of trade-wind cumulus for a total of 40 flights. Two observation methods were tested: one making racetracks to get statistics on the cumulus clouds and a new sampling strategy using sensor-driven adaptive sampling to track an individual cloud autonomously throughout its lifetime. It appears from the statistics that there are two types of cohabiting cloud population, with small-diameter clouds (transect lengths less than 500 m) being less buoyant than larger clouds (transect lengths greater than 500 m). Also, this statistical study shows that cumulus clouds do not have an adiabatic core. These results are compared with individual clouds tracked by adaptive sampling, which also show that the core of the cumulus clouds is diluted by the environment. A comparison with high-resolution large-eddy simulations shows that these numerical studies tend to underestimate mixing in the whole cloud.</p>
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