bluewave Posted December 22, 2016 Share Posted December 22, 2016 We just extended the current 4 SD AO streak to 8 DJFM's in a row. This surpasses the previous 6 year streak from 75-76 to 80-81. Peak DJFM AO values reaching 4SD or more since 1960: 16-17...12/21...+4.600 15-16...12/22...+4.503....1/16...-4.898 14-15...3/8/15..+5.588 13-14...12/15...+4.303 12-13....3/20....-5.588 11-12...12/2....+4.350 10-11...12/18...-5.265 09-10..12/21....-5.821 07-08...1/24....+4.598 04-05...1/5...+4.703....2/26...-4.337 03-04...1/17...-4.387 00-01...1/25....-4.854 97-98...1/10...-4.269 95-96...12/19...-4.353 92-93...1/14...+5.245 91-92...12/17..+4.704 89-90...2/26...+5.911 88-89...1/14...+5.582 85-86...3/23....+4.253 84-85...1/19.....-6.226 83-84...12/27...+4.460 82-83...1/18....+4.426 80-81...3/4.....-4.313 79-80..12/2...+5.040 78-79...1/25...-4.387 77-78...2/5....-5.921...3/20...+4.180 76-77...1/15...-7.433 75-76...2/25..+4.172 69-70...3/5....-6.365 68-69...2/13..-5.282 67-68...3/16..+4.917 65-66...1/28...-5.130 62-63...1/21...-5.010 61-62...3/14...-4.417 59-60..1/28...-4.108 Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 23, 2016 Share Posted December 23, 2016 Very interesting data. Unfortunately, the not all (and probably most) variables that lead to extreme AO outcomes are not well understood, so it's difficult to be sure whether the current stretch is unusual or within the bounds of internal variability. It may be plausible that Arctic Amplification might be contributing to a higher likelihood of extremes in recent years, but that remains little more than a hypothesis, especially as the AO's internal variability is high. A number of the above extreme cases coincided with or followed abnormally high Arctic temperatures, but there were exceptions. Such warmth might be a precursor or at least precondition the atmosphere to increase the probability of such extremes. That, too, is little more than a hypothesis. Link to comment Share on other sites More sharing options...
bluewave Posted December 23, 2016 Author Share Posted December 23, 2016 10 hours ago, donsutherland1 said: Very interesting data. Unfortunately, the not all (and probably most) variables that lead to extreme AO outcomes are not well understood, so it's difficult to be sure whether the current stretch is unusual or within the bounds of internal variability. It may be plausible that Arctic Amplification might be contributing to a higher likelihood of extremes in recent years, but that remains little more than a hypothesis, especially as the AO's internal variability is high. A number of the above extreme cases coincided with or followed abnormally high Arctic temperatures, but there were exceptions. Such warmth might be a precursor or at least precondition the atmosphere to increase the probability of such extremes. That, too, is little more than a hypothesis. Don, there was a study back in 2009 looking at NAO variability over 218 years using corals. It came to the conclusion that the NAO swings increased with warmer temperatures. But we will probably need more data and studies to know if what we are experiencing is within the range on internal variability or not. https://www.whoi.edu/page.do?pid=83537&tid=3622&cid=54686&c=2 Study links swings in North Atlantic Oscillation variability to climate warming The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions. “Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.” “As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.” Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 24, 2016 Share Posted December 24, 2016 16 hours ago, bluewave said: Don, there was a study back in 2009 looking at NAO variability over 218 years using corals. It came to the conclusion that the NAO swings increased with warmer temperatures. But we will probably need more data and studies to know if what we are experiencing is within the range on internal variability or not. https://www.whoi.edu/page.do?pid=83537&tid=3622&cid=54686&c=2 Study links swings in North Atlantic Oscillation variability to climate warming The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions. “Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.” “As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.” Thank you very much. I look forward to reading the paper. Link to comment Share on other sites More sharing options...
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