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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2025-08-21 0:45 |
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Conference: Bucharest University Faculty of Physics 2025 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
A dynamical model for the diurnal cycle of shallow and storm convection
Authors:
Cristian Vraciu
Affiliation:
Faculty of Physics, University of Bucharest
Horia Hulubei National Institute of Physics and Nuclear Engineering
E-mail
cv.vraciu@gmail.com
Keywords:
Storms, Non-linearity, Convection
Abstract:
Accurately predicting the diurnal cycle of deep convection is essential for a wide range of applications, including daily weather forecasting, aviation safety, climate modeling, and resource management. However, current weather and climate models frequently fail to capture the timing of deep convective events with precision, often forecasting the peak of convective precipitation and storm initiation prematurely. This study attributes such timing errors to the omission of cloud-convection interactions in many existing models. These interactions, which act as rapid feedback mechanisms on timescales comparable to the transition from shallow to deep convection during a diurnal cycle [1], are largely absent. Instead, conventional convective parameterization schemes typically assume interactions between convection and a homogeneous environment, resulting in feedback processes that are too slow to reflect the true timing of the diurnal cycle.
To address this limitation, this research introduces a unified cloud-convection model that captures both cloud-convection and convection-environment interactions, applicable across both shallow and deep convection regimes. The model consists of a set of prognostic equations governing the fractional area of various cloud types and the convective updraft velocity at multiple atmospheric levels. Additionally, drawing on the framework established by Arakawa and Schubert [2], a prognostic equation is included to represent the feedback of clouds on the large-scale environment for each cloud category.
The model is evaluated using idealized large-eddy simulations of the shallow-to-deep convective transition within a diurnal cycle, demonstrating promising results. Furthermore, the role of cold pools is explored through simulations in which their effects are suppressed, providing insights into their influence on convection dynamics. The prognostic model proposed here lays the groundwork for a new generation of cumulus parameterization schemes, offering a unified representation of cloud-convection processes and consistent treatment of both shallow and deep convection.
References:
[1] Vraciu, C. V., Savre, J., & Colin, M. (2025). The rapid transition from shallow to precipitating convection as a predator-prey process. Journal of Advances in Modeling Earth Systems, 17(2), e2024MS004630.
[2] Arakawa, A., & Schubert, W. H. (1974). Interaction of a cumulus cloud ensemble with the large-scale environment, Part I. Journal of the Atmospheric Sciences, 31(3), 674-701.
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