Gregorio et al. (2025) Nonlinear Dynamic Aspects of Generalized Frosts in the Pampa Húmeda of Argentina

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Atmosphere
• Year: 2025
• Date: 2025-11-07
• Authors: María José De Gregorio, Gabriela V. Müller
• DOI: 10.3390/atmos16111268

Research Groups

Not explicitly stated in the provided text. The study focuses on the Pampa Húmeda of Argentina.

Short Summary

This study investigates the dynamical and physical mechanisms behind short-lived (0DP) generalized frosts in the Pampa Húmeda, revealing that nonlinear interactions, particularly the divergent term of the Rossby Wave Source (RWS) equation, are crucial for both their formation and rapid dissipation.

Objective

• To investigate the dynamical and physical mechanisms that sustain short-lived (0DP) generalized frost events, emphasizing the nonlinear interactions represented by the Rossby Wave Source (RWS) equation.

Study Configuration

• Spatial Scale: Regional to continental (Pampa Húmeda of Argentina, eastern Pacific Ocean, South America, southwestern Atlantic).
• Temporal Scale: Synoptic to sub-daily (events lasting less than one day, rapid weakening and dissipation).

Methodology and Data

• Models used: Diagnostic equations, specifically the Rossby Wave Source (RWS) equation and its decomposition into advective and divergent terms.
• Data sources: Composite analysis of atmospheric fields (pressure, temperature, wind, and geopotential height), implying the use of atmospheric reanalysis or observational data.

Main Results

• 0DP frost events are linked to abrupt cold air intrusion associated with enhanced upper-level troughs over the eastern Pacific Ocean and transient surface anticyclones over South America.
• Linear analysis alone was insufficient to explain the rapid weakening and dissipation of the circulation.
• Nonlinear analysis using the RWS equation showed that the advective term acts primarily as an initial trigger, deepening troughs and favoring meridional cold air advection.
• The divergent term of the RWS equation dominates the events, representing 63–67% of the affected area. This term reinforces ridges, promotes subsidence, and favors clear sky conditions, thereby enhancing nocturnal radiative cooling and frost formation.
• Positive anomalies of the divergent RWS term strengthen the ridge and advect cold air over the Pampa Húmeda, while subsequent negative anomalies over the southwestern Atlantic act as sinks of wave activity, leading to the rapid dissipation of the synoptic configuration.
• The same nonlinear mechanism that generates favorable conditions for frost development also determines their lack of persistence.

Contributions

• Demonstrates that the short-lived nature of 0DP frosts is not due to the absence of dynamical forcing, but rather to specific nonlinear processes that both enable and constrain their occurrence.
• Highlights the importance of incorporating nonlinear diagnostics, such as the Rossby Wave Source, to improve the understanding and prediction of short-lived atmospheric extreme events.

Funding

Not explicitly stated in the provided text.

Citation

@article{Gregorio2025Nonlinear,
  author = {Gregorio, María José De and Müller, Gabriela V.},
  title = {Nonlinear Dynamic Aspects of Generalized Frosts in the Pampa Húmeda of Argentina},
  journal = {Atmosphere},
  year = {2025},
  doi = {10.3390/atmos16111268},
  url = {https://doi.org/10.3390/atmos16111268}
}