Heatwaves Also Hit the Ocean. Why?

How ‘rivers in the sky‘ influence sea temperatures

an image of the atmosphere

This is a summary of a story written by Julie Leibach on Nicholas School of the Environment.

Just like on land, the ocean environment can experience heatwaves. These periods of abnormally high ocean temperatures can last for weeks or even months, with potentially severe ecological and economic consequences.

Researchers from the Nicholas School of the Environment have identified a connection between marine heatwaves and moving bands of moisture in the air, called atmospheric rivers. Their study, funded by NASA, could potentially lead to improved predictions of marine heatwaves and a better understanding of how climate change factors in. 

Atmospheric rivers spend ample time over oceans, where they can influence sea surface temperatures through various processes that move heat around. The researchers wanted to see if interactions between atmospheric rivers and the sea surface might play a role in marine heatwaves.

Using data collected from satellites, ships and other instruments, the team identified atmospheric rivers and marine heatwaves that occurred in the North Pacific and North Atlantic oceans, outside of the tropics, from 1982 to 2023. Both types of phenomena are known to be more active and severe in these regions than in other parts of the ocean.

Through statistical analysis, the team found a particularly strong association between atmospheric rivers and marine heatwaves that unfolded differently depending on the region and season. In winter, for example, unusually active atmospheric rivers occurred a couple of days before marine heatwaves peak, suggesting that the former influence the latter. By contrast, in summer, fewer atmospheric rivers preceded marine heatwaves.

The findings highlight the need for improved understanding of ocean-atmosphere interactions in the context of climate change, according to Shineng Hu, a climate scientist who oversaw the study.

“Marine heatwaves have been stronger and more frequent under global warming, because the ocean absorbs most excess heat trapped by rising greenhouse gases. Atmospheric rivers also tend to become more intense as the air gets warmer and moister, according to our previous study,” Hu says. “How interactions between these events might respond to climate change is what we are trying to understand next.”

Full the full article, go to Nicholas School of the Environment.