Toward a mechanistic characterisation of marine heatwaves

Overview

Marine heatwaves present significant challenges for mechanistic understanding due to limitations in conventional detection methodologies. Standard pointwise approaches, which identify events relative to fixed thresholds at individual grid points, have facilitated global-scale analyses but obscure the spatiotemporal coherence and physical drivers of these events. This study extends kinematic frameworks that treat marine heatwaves as evolving spatiotemporal entities by incorporating explicit driver attribution. The research quantifies how dominant forcing mechanisms vary across marine heatwave lifecycles and develops methods to characterize event-scale features in relation to underlying atmospheric and oceanic processes.

Methods and approach

The methodology treats marine heatwaves as coherent spatiotemporal objects rather than isolated point observations, enabling tracking of events throughout their evolution. A normalisation framework is introduced that preserves event-scale characteristics while permitting composite analyses across multiple heatwaves. The approach identifies and quantifies dominant forcing mechanisms throughout marine heatwave lifetimes and links evolving event characteristics to their physical drivers. Application to the Tasman Sea, selected for its complex atmosphere-ocean interaction regime, provides empirical evaluation of the framework's capacity to reveal distinct atmospheric and oceanic conditions at different evolutionary stages.

Key Findings

The analysis demonstrates that marine heatwave evolution is shaped by distinct atmospheric and oceanic conditions that vary systematically across different stages of event development. By explicitly tracking marine heatwaves as evolving entities and attributing their characteristics to specific physical drivers, the study reveals previously obscured mechanistic relationships between forcing mechanisms and heatwave dynamics. The normalisation framework successfully enables composite analyses across multiple events while preserving their spatial and temporal characteristics, facilitating identification of driver-dependent features and their relationship to event-scale properties.

Implications

The mechanistic characterization framework advances understanding of marine heatwave physics by moving beyond pixel-based detection toward event-scale analysis that captures spatiotemporal coherence and driver attribution. Enhanced characterization of the relationship between physical drivers and evolving marine heatwave properties provides a foundation for improved predictive capabilities. The methodology is transferable to additional ocean regions and can inform development of prediction systems that explicitly account for the dominant forcing mechanisms operating during different phases of heatwave development. Recognition of driver-dependent variability in marine heatwave evolution has implications for understanding regional climate impacts and designing targeted monitoring strategies.