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Avalanches, breathers, and flow reversal in a continuous Lorenz-96 model
R Blender1, J Wouters, V Lucarini
1Meteorologisches Institut, KlimaCampus, Universität Hamburg, Hamburg, Germany.
Summary
A discrete Lorenz model approximation reveals avalanche-like breather solutions. These solutions, driven by weak forcing, reverse the mean flow through wave-mean flow interaction, mimicking sandpile avalanches.
Area of Science:
- Atmospheric Dynamics
- Nonlinear Systems
- Computational Physics
Background:
- The study builds upon the discrete model proposed by Lorenz in 1996, focusing on atmospheric dynamics.
- Investigates energy-conserving but non-Hamiltonian systems, relevant to complex physical phenomena.
Purpose of the Study:
- To derive and analyze a one-dimensional long-wave approximation of the discrete Lorenz model.
- To explore the emergence of nonlinear excitation and diffusion effects within this simplified model.
- To understand the mechanism behind mean flow reversal induced by external forcing.
Main Methods:
- Derivation of a one-dimensional long-wave approximation for the discrete Lorenz model.
- Application of low-order truncation to analyze model behavior.
- Investigation of weak external forcing on the zonal mean flow.
Main Results:
- Identification of avalanche-like breather solutions under weak external forcing.
- Demonstration of mean flow reversal driven by wave-mean flow interaction.
- Characterization of the underlying mechanism as an outburst-recharge process, analogous to sandpile avalanches.
Conclusions:
- The derived model successfully reproduces complex dynamics, including mean flow reversal.
- Wave-mean flow interaction is identified as a key mechanism for generating these dynamic reversals.
- The findings offer insights into nonlinear phenomena in simplified atmospheric models, drawing parallels with self-organized criticality.
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