Seas in hot water – marine heatwaves on the move; following the heat.

Abstract

Over the past decade marine heatwaves (MHWs) have gained increased attention due to their long-lasting impacts on marine ecosystems and the services they provide. These unusual, warm-water events have occurred throughout the global ocean, often having the most severe impacts along the coast. As ocean temperatures continue to rise due to anthropogenic greenhouse gas forcing, MHWs are expected to become more frequent, intense, and longer-lasting. This raises concerns for how dangerous MHWs may become in the future. This dissertation provides new insights into the spatiotemporal evolution of marine heatwaves using a global network of satellite and in situ observations. This work first describes the role of the ocean and atmosphere in driving upper ocean temperature seasonally using a mixed layer heat budget, which is essential to diagnosing the drivers of MHWs. The roles of subsurface temperature, salinity, and density are also examined with respect to the persistence and penetration of recent Northeast Pacific MHWs. Lastly, a new tracking algorithm is proposed to characterize the spatiotemporal evolution of MHWs globally, and to understand the sensitivities of spatial resolution and chosen thresholds in the detection of MHWs. This collection of work contributes to the eventual forecast of MHWs that will assist marine managers in mitigating the harmful impacts from these events in the future.