Picture: Maldives by Saud Edum (Unsplash).

Marine heatwaves (MHWs) are persistent extreme temperatures in the ocean. They have a negative impact on marine life, fisheries, and tourism, and are becoming more frequent and more intense. One way to understand how MHWs form, intensify and decay is by analysing results from computer simulations of the ocean.

However, these simulations are a simplification of reality and depending on how they are designed they represent different aspects of the ocean circulation. It is still unknown how much the resolution of an ocean simulation matters when representing MHWs.

In this work, CLEX researchers compared the performance of three ocean simulations – with low, medium and high resolutions – when representing MHWs.

They found that, regardless of their resolution, all simulations have weaker, longer, and less-frequent MHWs, when compared with the real world. Despite these differences, they found that simulations with medium and high resolutions realistically represent global spatial patterns of MHWs. However, the ocean simulation with high resolution is preferable when studying regional patterns of MHWs.

These results show how simulated MHWs differ from the real-world, helping us to improve ocean simulations to be more realistic. In addition, we now better understand how computer simulations of future oceans, under climate change conditions, represent these extreme events.