Studying non-equilibrium turbulence inside and around cumulus clouds

Estimating the characteristics of turbulence in a changing environment, where assumptions about stationarity and homogenity do not necessarily hold true, is burdened with error. Clouds can be thought of as an example of such environment in which many non-stationarities, inhomogenities and sudden changes are present. A number of recent research works address the problem of the equilibrium Taylor’s law and its failure in the presence of rapid changes of the system.The main idea of this work is to calculate C-epsilon from in-situ airborne measurements of atmospheric turbulence, where the flow conditions in the investigated region are unknown a priori and only limited information, that is 1D intersections of the flow field along the flight track, are available. By studying the dependence of C-epsilon on Reλ, we can identify whether turbulence is in- or out of equilibrium. We can also recover information about temporal tendencies in the investigated region by comparing C-epsilon with its equilibrium value C0. We focus on the data from the EUREC4A (Elucidating the role of clouds-circulation coupling in climate) campaign, collected near Barbados, and most importantly, the data from the inside and outside clouds. We treat the cloud as a disturbance in the flow field, but we also analyse its surroundings.Preliminary results show that indeed C-epsilon value inside a cloud is different than its equilibrium value, indicating active production of turbulence. We compare the results calculated for clouds at varying heights and different days.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)