Sensitivity of Marine Heatwave Metrics to Ocean Model Resolution

Sustained extreme temperature events in the ocean, referred to as marine heatwaves (MHWs), generate substantial ecological, social, and economic impacts. Ocean models provide insights to the drivers, persistence, and dissipation of MHWs. However, the sensitivity of MHW metrics to ocean model resolution is unknown. Here, we analyze global MHW metrics in three configurations of a global ocean-sea ice model at coarse (1◦), eddy-permitting (0.25◦), and eddy-rich (0.1◦) resolutions. We show that all configurations qualitatively represent broad-scale global patterns of MHWs. These simulated MHWs are, however, weaker, longer-lasting, and less frequent than in observations. The 0.1◦ configuration, despite local biases, performs best both globally and regionally. Based on these results, model projections of future MHW metrics using coarse-resolution models are expected to be biased toward weaker and less frequent MHWs, when compared with results using an eddy-rich model.The authors thank the Consortium for Ocean-Sea Ice Modeling in Australia (COSIMA; www.cosima.org.au), funded by the Australian Research Council through its Linkage Program (LP160100073), for making the ACCESS-OM2 suite of models available in https://doi.org/10.5281/zenodo