Researchers at the University of Liverpool have developed a novel method to measure ocean memory, revealing that the North Atlantic Ocean retains memory for nearly two decades—far longer than previously estimated.
A research team led by the University of Liverpool has introduced a novel method to measure ocean memory, revealing that the North Atlantic Ocean retains its memory for about one to two decades—far exceeding earlier estimates of just a few years.
Ocean memory refers to the persistence of ocean conditions and is a major source of predictability in the climate system beyond weather time scales. However, the fundamental question of “how long does the ocean remember?” has been unclear. The difficulty in identifying ocean memory is due to continual changes in atmospheric forcing masking the longer-term effects of ocean circulation.
New Framework to Measure Ocean Memory
Reported in a paper published in Geophysical Research Letters, the 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 find that there are fast and slow responses involving an immediate atmospheric effect on surface temperature and a delayed ocean redistribution of heat.
The authors attribute the extended memory of the North Atlantic Ocean to the slow pace of changes in the ocean circulation and heat transport.
Their findings suggest that fluctuations in ocean temperatures exert a significant influence on regional climates, such as air temperatures, for over a decade.
It also offers support that careful analyses of observations may enhance future climate projections over a decade.
Dr. Hemant Khatri, from the University of Liverpool and lead author of the paper, said: “The study addresses a fundamental question of what ocean memory truly is. The new ocean memory framework reveals physical mechanisms responsible for multi-year ocean memory and paves the way for new methods for evaluating climate models.”
Professor Ric Williams, from the University of Liverpool and co-author of the paper, said: “This is the first time we’ve been able to measure ocean memory. We find that, in contrast to observation-based estimates, state-of-the-art climate models significantly underestimate ocean memory, estimating it at only 8-10 years. This significant discrepancy in ocean memory could have substantial implications for the accuracy of decadal climate predictions from these models.”
“Our work shows how the ocean affects our climate and how understanding the ocean temperature changes leads to enhanced skill over the next decade in climate projections.”
Reference: “An Ocean Memory Perspective: Disentangling Atmospheric Control of Decadal Variability in the North Atlantic Ocean” by Hemant Khatri, Richard G. Williams, Tim Woollings and Doug M. Smith, 12 October 2024, Geophysical Research Letters.
DOI: 10.1029/2024GL110333
The study involves the University of Liverpool, the University of Oxford, and UK Met Office with support from UKRI NERC.
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9 Comments
“Ocean memory refers to the persistence of ocean conditions and is a major source of predictability in the climate system beyond weather time scales.”
It sounds like the authors are describing what mathematicians call auto-correlation, which is more descriptive than attributing the sentient-creature property of memory to non-sentient things.
Problem lies in the hyphenated word “auto-correlation”. KISS.
Alas that most humans are mathematically illiterate, although pounds, shillings and pence still make more sense to this old fogey than the wretched decimal system. Did you realise that the kilometre is 50 standard cricket pitches long, plus/minus an inch or two, and that the number of ounces to the pound can be counted by the thumb on the adjacent 4 fingers, as can the number of pennies to the shilling?
And using one’s left hand one can tot-up the number of shillings to the Crown, which is a very Babylonian number used to locate positions on, and to navigate around, the globe, possible even by satellites. However, I am not so sure about the use of 80 ounces, although at one penny per ounce there would be 240 ounces to the pound.
If you count in binary, one can handle numbers up to 31 on the left hand. The base assumed is important. Using both hands, one can count to (2^10)-1 or 1,023. That is assuming one doesn’t have arthritis in their hands.
Rob – 80 ounces is 2 big bottles of whiskey:)
But you won’t buy whisky at 10 bob a bottle……….
Actually, I usually write the word as “autocorrelation.” However, I anticipated that some pendant would complain about misspelling it, so I went with what Microsoft’s Spell Check recommended.
The spelling is of no bother; not a hanging offence. Just the concept behind the word and what it implies might be found confusing by some.
So, it doesn’t remember German U-boats?