Southwestern Atlantic Cyclone Tracks and Semi-Lagrangian Lorenz Energy Cycle (LEC) diagnostics (1979–2020)

Overview and purpose Extratropical cyclones in the Southwestern Atlantic exhibit substantial variability in dynamical and thermodynamical structure. To support reproducibility and enable independent analyses, this dataset compiles, for each tracked system and each time step along its track: (i) storm position and a tracking-based intensity metric, and (ii) regional Lorenz Energy Cycle (LEC) terms estimated in a semi-Lagrangian (storm-following) control volume. The resulting time series enable investigations of storm energetics, life-cycle evolution, and contrasts across genesis environments. Data sources and cyclone tracking Atmospheric fields used for the energetic calculations are derived from the ERA5 reanalysis. Cyclone trajectories originate from a TRACK-based identification of storm centers using 850-hPa relative vorticity (ζ850). Track selection follows standard quality-control practices (e.g., minimum lifetime/displacement thresholds and exclusion of predominantly continental systems), ensuring a focus on synoptic-scale cyclones relevant to the Southwestern Atlantic. Spatial focus and genesis-region classification The dataset targets cyclones forming near the South American coast, classified into three genesis regions: eastern Argentina (ARG), La Plata River basin (LA-PLATA), and southeast Brazil (SE-BR). These labels are provided in the region column and support stratified analyses by genesis environment. Life-cycle phase attribution Each cyclone track is segmented into objective life-cycle phases using CycloPhaser, which identifies key stages from the temporal evolution of the storm-centered vorticity time series (and its tendency), based on peaks and troughs that mark transitions. Phase labels are stored in the period column as: incipient, intensification, mature, and decay. Semi-Lagrangian Lorenz Energy Cycle diagnostics LEC terms are computed in a storm-following (semi-Lagrangian) rectangular domain of 15°×15° centered on the cyclone position at each UTC time step. This moving control volume is designed to emphasize energetics directly associated with the storm while reducing contamination from neighboring synoptic systems. The dataset includes: Energy reservoirs (AZ, AE, KZ, KE; typically J m⁻²), Conversion terms (CA, CE, CK, CZ; typically W m⁻²), Boundary flux terms (BAZ, BAE, BKZ, BKE; W m⁻²) and boundary pressure-work terms (BΦZ, BΦE; W m⁻²), Diabatic generation (GZ, GE; W m⁻²), Time tendencies of reservoirs (finite differences; W m⁻²), and Residual terms (RGZ, RGE, RKZ, RKE; W m⁻²) representing unresolved processes and numerical closure. File structure and missing values The CSV is provided in long format: each row corresponds to a single UTC time step of a cyclone (track_id) with associated location, classification, and energetics. Some variables may contain NaN values at specific timestamps (e.g., when a diagnostic is not available or not computed for that step). Users are advised to mask/filter missing values prior to statistical analyses. Variable dictionary (key fields) track_id: unique cyclone identifier date (UTC): timestamp for each track step lon vor, lat vor: cyclone-center longitude/latitude (degrees) vor42: filtered and normalized ζ850 used as a tracking/intensity metric, stored as a positive-only quantity and scaled by 1×10⁵ (i.e., vor42 = 1e5 × ζ850_filtered_normalized, with sign convention adjusted to be non-negative) region: genesis region (ARG, LA-PLATA, SE-BR) period: life-cycle phase (incipient, intensification, mature, decay) Az, Ae, Kz, Ke: LEC reservoirs (J m⁻²) Cz, Ca, Ce, Ck: LEC conversion terms (W m⁻²) BAz, BAe, BKz, BKe: boundary flux terms (W m⁻²) BΦZ, BΦE: boundary pressure-work terms (W m⁻²) Gz, Ge: diabatic generation of APE (W m⁻²) ∂Az/∂t, ∂Ae/∂t, ∂Kz/∂t, ∂Ke/∂t: reservoir tendencies (finite differences; W m⁻²) RGz, RGe, RKz, RKe: residual generation/dissipation terms (W m⁻²)