Groundbreaking research has revealed that the influence of the El Niño-Southern Oscillation (ENSO) extends far beyond the tropics, impacting Atlantic weather patterns a full year after the initial event. This discovery could revolutionize long-range weather forecasting, enabling meteorologists to better prepare for and adapt to the effects of this global climate phenomenon.
Ripple Effect Across the Atlantic
Scientists at the U.K.’s Meteorological Office have found that a potentially strong force of nature, one of the most influential some would say in terms of pattern weather climate, holds sway not only over tropical regions but much more widely across North and south America, Europe and Asi. Their research, published in the prestigious journal Science, shows that ENSO affects Atlantic weather patterns for all of the first year following the original event.
This delayed tropical forcing of the extratropics is equally powerful to contemporaneous response, but with an opposite sign. The researchers say an El Niño event, which raises the odds of cold winters in the UK, can produce a mild winter next year. This can, in turn, give rise to a La Niña event which takes exactly one year to propagate eastwards around the globe leading to negative North Atlantic Oscillation (NAO) and hence a much harsher winter.
Solving the Mysteries of Extreme Winters
The research also demonstrates that some of the UK’s most extreme winters can only be interpreted if we know what type of ENSO event occurred the previous winter. In related phenomena, the effects of El Niño (or La Niña) are often magnified if they are followed by the occurrence of La Niña (or El Niño).
For example, the La Niña of 1974/75 and 1999-2000 was followed by the El Niño of 1982/83 whilst in 1968/69, 1976/77 and also that of 2009/10 we saw this process, which would lead to the colder weather at the time. Yet the UK had mild and stormy winters in 1988/89, 1998/99 and 2007/08 following an El Niño by a La Niña To that point, meteorologists will also be better prepared to prepare and respond to these wild weather events with this newly discovered information.
Improving long-term climate forecasting
This finding has significant implications for our understanding of ENSO, say the research team led by Professor Adam Scaife from the Met Office and University of Exeter), and for long-range weather forecasting.
“That means that after El Niño events we are more likely to have positive NAO the next winter and after La Niña events negative NAO one year later,” said Scaife. “The results from this research have significant implications for ENSO and, by extension, our predictability of winter climate variability as well as how we interpret long-range predictions.
The improved insight on the teleconnections and things like the impacts of ENSO could in turn be used by meteorologists to include these patterns into climate models, thus resulting in more reliable long-range weather forecasting. This development could revolutionize preparation for the effects of global climate patterns across many industries and communities.
