Ricardo de Camargo

This study presents a climatological assessment of the Lorenz Energy Cycle (LEC) applied to South Atlantic cyclones, using a Semi-Lagrangian framework. Over 6,700 cyclones were identified from ERA5 reanalysis (1979–2020), and LEC components were computed and averaged across four objectively defined life cycle phases: incipient, intensification, mature, and decay. Results reveal a coherent energy transfer structure: baroclinic conversions dominate during intensification, while barotropic conversions peak during the mature phase and reach magnitudes 2–3 times larger than baroclinic counterparts. Diabatic generation of eddy available potential energy plays a secondary but relevant role, particularly during intensification, occasionally surpassing baroclinic contributions. Eddy kinetic energy imports are most significant during the early phases, reinforcing development. Despite substantial variability among systems, an EOF analysis shows that most cyclones share a common energy structure, with variability manifesting as amplification or suppression of specific pathways. The leading EOFs are linked to differences in cyclone intensity, genesis region, and seasonality. Among the most intense systems, distinct clusters emerge with varying energetic configurations, some dominated by baroclinic processes, others by barotropic conversions or enhanced diabatic generation. These findings demonstrate that South Atlantic cyclones encompass a spectrum of dynamical behaviors and can be classified based on their energy cycle characteristics. This study provides the first large-sample application of the Semi-Lagrangian LEC to extratropical cyclones in the South Atlantic and highlights the importance of barotropic processes in their development. The results offer a robust framework for interpreting cyclone energetics and establish a comprehensive baseline for classifying these systems.

Cyclone Akará was the third documented tropical cyclone in the South Atlantic, undergoing a rare subtropical-to-tropical transition in February 2024. This study investigates the dynamical, thermodynamical, and energetic evolution of Akará using a diagnostic framework combining the Lorenz Energy Cycle (LEC) and heat and vorticity budgets. Akará originated in a post-frontal, weakly baroclinic environment characterized by warm sea surface temperatures (>28$\circ C$), strong ocean-atmosphere thermal contrast, and low vertical wind shear. These conditions favored convective activity and led to the development of a symmetric warm core, initially supported by latent heat release and interaction with an upper-level cutoff low. As the system intensified, it transitioned into a tropical cyclone, exhibiting a deep warm core and organized convection. Stratospheric air intrusions were identified during and after the tropical transition, contributing to upper-tropospheric warming and enhancing cyclone intensification. Heat and vorticity budget analyses revealed how vertical motion, latent heat release, and vortex stretching shaped the storm’s three-dimensional structure and contributed to its deepening. During the mature stage, Akará reached peak intensity while moving over cooler waters. Although convective activity decreased, the warm core was sustained—likely through continued stratosphere-troposphere interactions and strong barotropic energy conversions at low and mid levels. The combined use of LEC and budget diagnostics proved effective in disentangling the physical mechanisms behind Akará's evolution, offering valuable insight into the dynamics of rare South Atlantic tropical transitions. Expanding such analyses to other events is essential to improve our understanding and forecasting of tropical cyclogenesis in this basin.

CycloPhaser is a Python package designed to detect and analyze extratropical cyclone life cycles from central relative vorticity data. It enables researchers in meteorology and atmospheric sciences to automatically identify key stages of cyclone development, such as intensification, decay, and mature phases, using the vorticity series and its derivatives. By leveraging vorticity data, CycloPhaser helps scientists study cyclones across various regions and timeframes, contributing to improved understanding of cyclone energetics and behavior.