Scientists in the College of California Irvine have proven that the phenomenon referred to as Atlantic Multidecadal Oscillation (AMO) -- an all natural pattern of variation in North Atlantic ocean surface temps that switches between an optimistic and negative phase every 60-70 years -- can impact an atmospheric circulation pattern, referred to as North Atlantic Oscillation (NAO), that influences the temperature and precipitation within the Northern Hemisphere in the winter months.
Once the AMO is within its positive phase and also the ocean surface temps are warmer, the research has proven the primary effect in the winter months would be to promote the negative phase from the NAO which results in "obstructing" episodes within the North Atlantic sector, permitting cold temperature systems to exist within the eastern US and Europe.
The outcomes happen to be released today, Wednesday 2 April, in IOP Publishing's journal Environment Research Letters.
To reach their results, the scientists combined findings in the past century with climate simulations from the atmospheric reaction to the AMO.
Based on their findings, ocean surface temps within the Atlantic can depend on 1.5 ?C warmer within the Gulf Stream region throughout the positive phase from the AMO in comparison towards the negative, cooler phase. The weather simulations claim that these anomalies in ocean surface temps can enjoy a predominant role in marketing the modification within the NAO.
Lead authors from the study Yannick Peings and Gudrun Magnusdottir stated: "Our results indicate the primary aftereffect of the positive AMO in the winter months would be to promote the appearance of the negative phase from the NAO. An adverse NAO in the winter months usually goes hands-in-hands with cold temperature within the eastern US and north-the european union.Inch
The findings also suggest that it requires around 10-fifteen years prior to the positive phase of AMO has any important effect around the NAO. The reason behind this lag is unknown however, a reason may be that AMO phases make time to develop fully.
Because the AMO has been around an optimistic phase because the early the nineteen nineties, it might have led towards the extreme winters that both US and Europe have observed recently.
The scientists warn, however, the future evolution from the AMO remains uncertain, with lots of factors potentially affecting the way it interacts with atmospheric circulation designs, for example Arctic ocean ice loss, alterations in photo voltaic radiation, volcanic eruptions and levels of green house gases within the atmosphere.
The AMO also shows strong variability in one year to another additionally towards the changes seen every 60 - 70 years, which causes it to be hard to attribute specific extreme winters towards the AMO's effects.
Reacting towards the extreme weather that held the eastern coast of america this winter, Yannick Peings ongoing: "Unlike the 2012/2013 winter, this winter had rather low values from the AMO index and also the pattern of ocean surface temperature anomalies wasn't in conjuction with the typical positive AMO pattern. Furthermore, the NAO was mostly positive having a relatively mild winter over Europe."
"It is therefore unlikely the positive AMO performed a determining role around the new england of america, although further jobs are essential to answer this. This kind of event is in conjuction with the large internal variability from the atmosphere, along with other exterior forcings might have performed a job.
"Our future studies will turn to compare the function from the AMO in comparison to Arctic ocean ice anomalies, which are also proven to affect atmospheric circulation designs and promote cooler, more extreme winters."
