Wave climate bias reduction by ocean, sea ice, and iceberg coupling within Earth System Modeling

The Southern Ocean has a consistently extreme wave climate, with significant wave heights frequently exceeding 5 m. Large waves generated in this area affect many other global regions, especially the west coasts of North America, South America, and Australia, via swell propagation. Altimeter observations show that over the last 2 decades, there has been a significant trend toward increasing wind speeds in high latitudes that correspond to an increase in extreme wave heights. Given the effect of the Southern ocean has on the global wave climate, this increasing trend in wave heights raises the importance of accurately modelling waves in this region. Several validation studies have shown that global, third-generation spectral wave models have a consistent positive wave height bias in the Southern Ocean. These biases will ultimately feedback into the climate system via cross-component couplings with waves. In this work, we investigate coupled feedbacks of two mitigating processes on the simulated wave climate. First, dissipation introduced through wave-iceberg interactions damps significant wave heights. Second, ocean surface currents, including ocean eddies in the Antarctic Circumpolar Current, modify the relative wind speed responsible for wave generation. Accounting for the nonlinear combination of these effects has the potential to increase the accuracy of Southern Ocean wave predictions and illustrates how cross-component physical processes may affect global wave climate.