The North Atlantic has a ‘memory’ of up to two decades

Dec. 3 () –

The North Atlantic Ocean has a memory of approximately one to two decades, significantly exceeding previous estimates of a few years, requires new research.

Oceanic memory refers to the persistence of ocean conditions and is an important source of predictability in the climate system beyond meteorological timescales. However, the fundamental question of “how long does the ocean remember?” has not been clear. The difficulty in identifying oceanic memory is due to the continuous changes in atmospheric forcing that mask the long-term effects of ocean circulation.

As reported in an article published in the magazine Geophysical Research Letters, The University of Liverpool research team was able to quantify ocean memory by tracking the evolution of ocean temperatures in response to a single extreme atmospheric event. The authors found that there are fast and slow responses that imply an immediate atmospheric effect on the surface temperature and a late redistribution of ocean heat.

The authors attribute the extended memory of the North Atlantic Ocean to the slow pace of changes in ocean circulation and heat transport.

Their findings suggest that fluctuations in ocean temperatures exert a significant influence on regional climates, like air temperaturesfor more than a decade.

It also offers support for the idea that careful analyzes of observations can improve future climate projections over a decade.

Dr Hemant Khatri, from the School of Environmental Sciences at the University of Liverpool and lead author of the paper, said in a statement: “The study addresses a fundamental question of what ocean memory really is. The new ocean memory framework reveals the physical mechanisms responsible for multi-year ocean memory and paves the way for new methods of evaluating climate models.”

Professor Ric Williams, also from the University of Liverpool and co-author of the paper, said: “This is the first time we have been able to measure ocean memory. We found that, in contrast to observation-based estimates, state-of-the-art climate models They significantly underestimate oceanic memory, estimating it at only eight to ten years. This significant discrepancy in oceanic memory. could have substantial implications for the accuracy of these models’ decadal climate predictions“.

“Our work shows how the ocean affects our climate and how understanding ocean temperature changes leads to better skill over the next decade in climate projections.”