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John Christensen
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Hi Ghoti Of Lod, Thank you for the interest! The 3 month running mean of the NAO has been used primarily to perform causal analysis of NAO impact during winter months, while there has been little focus on NAO during summer months. You see the impact of the current cyclone very clearly on the DMI graphs, such as in the latest image, where temperatures have increased significantly in the cyclone impacted area near the Pole: If strong westerlies (positive NAO) caused this North Atlantic low to travel further, before it reached the central Arctic Basin, then the low could have lost 15-20% of its energy, compared to a negative NAO situation, where the low could would have followed a more direct route to the Arctic Basin. I will check if DMI has done more analysis on this.
One more update on the Arctic low: DMI has a great graphic showing that as of yesterday the cyclone seems to have put the ice into significant motion with a current speed similar to what you see in ice-free waters (Select surface current and Arctic Sea): This seems to be possible, as the strongest winds of the cyclone follows the same area, where we saw what appeared to be an undercurrent of warm waters leaving the Laptev Sea in a counterclockwise movement towards the Pole and then south into Barents Sea between Svalbard and Franz Josef Lands from late July into September. No doubt that this movement of ice and mixing with top water layers will delay freeze in the area, helped by the temperature increase caused by the cyclone, as is clearly visible on the DMI 60N weather graphic. The next strong Atlantic fall cyclone is shaping up between Greenland and Iceland, and with NAO moving towards neutral state the cyclone may take a more direct path to the central Arctic Basin.
Sorry, let me retract my last comment: The jet stream apparently moved a bit south over the weekend, so that by Sunday it was crossing Norway rather than going around the Scandinavian peninsula on the north and then going south: Due to the new position and probably the strong blocking high over Siberia, the jet stream had a less pronounced northern direction just east of the Scandinavian peninsula. The low therefore seemed to follow the road of least resistance moving straight North. This event has now played out with the center of the low placed between Franz Josef Lands and the Pole by Monday morning, European time: Regarding the question of the impact of NAO on Arctic sea ice, let me summarize from this event: - NAO index was medium strong and positive (1.5), increasing westerlies across Northern Atlantic - This caused the cyclone to move to Norway from its prior position just north of Iceland, which is an ENE direction - The cyclone then entered the Barents Sea, now in a NE direction - Finally, it got redirected going straight North, where it seems it will dump its final load of moisture across the central area of the ice pack - The positive NAO therefore did not prevent the low from entering the Arctic - but it significantly extended the distance for the low to reach the Arctic from Iceland, in which time the system is reduced from a heat/energy perspective
Last comment on the North Atlantic low, which has now become an Arctic low: What I did not spot a couple of days ago was the high developing over the CAA, which attracts the North Atlantic low, breaking it into two, where the majority of energy now moves straight North from the northern-most point of Norway and across Franz Josef Lands towards the Pole. A minor fraction will follow the jet stream moving south-east towards the Ural mountain range: You can see this play out on the CT forecast:
For those who can read Norwegian, an update on this storm: As is stated there, they expect precipitation as rain and not snow, but in Northern parts of the country up to 140mm in two days, which is a lot.
On Atlantic moisture, NAO and the Arctic. As you see from DMI's 60N weather image there is currently a massive low covering nearly the entire Norwegian Sea, or about 5,000,000KM^2: Now, if the NAO had currently been strongly negative, this low would move straight North, bringing a tremendous amount of moisture into the center of the Arctic region, which would delay/slow down sea ice accumulation there. While the low is still at a distance, pressure gradients in the central Arctic are low, so the weather is relatively quiet, dominated by a much weaker low centered in the Laptev Sea (also not surprising given the open water there). The low pressure gradients have allowed surface temperatures on the DMI 60N image (above link) to move below -15C for the first time this season in a small area between the Pole and Beaufort. The NAO is right now positive, but not strongly: However, this should be sufficient in ensuring that the massive low moves North-East skirmishing the Norwegian mountain ranges, dumping loads of snow there/releasing heat, before the low probably enters the Barents Sea near the Russian North coast. The current jet stream then would push the low south due to a blocking high in Siberia, but IMO it might as well cut its own path towards Kara and then Laptev causing still massive precipitation, but with a considerably colder core temperature when reaching central Arctic areas than we would have seen under strongly negative NAO. It will be interesting to watch how this plays out the next two-three days, as it should be a classic example of how the NAO steers the North-Atlantic lows.
Hi mark, Being on the overall skeptical side of matters myself and recognizing the way scientific paradigms limit the perspectives even of scientists, as well as being ever hopeful/optimistic on behalf of the resilience of Arctic sea ice, I need to agree with others here that it is of little value to point to the state of the climate a thousand years ago, or otherwise at the high level to question what is happening. This blog is focused on Arctic Sea Ice, and being just this, it is extremely valuable from my perspective, to try and understand the nature and weight of the different factors impacting Arctic sea ice. This will increase our knowledge and improve estimations of what will happen in the next 5, 10 and 50 years, both to the ice and the World we live in. Being further along on the skeptical line, you should have a close look at PIOMAS data, look at the graphs, download the daily volume readings, check interyear changes, etc., and you will realize that it does not matter what weather we had a thousand years ago - or 6,000 years ago where we had an increased and significant warm spell. The Arctic sea ice is disappearing, rather rapidly..
Hi Colorado Bob, Thank you for your comment. And yes; I am sure he is very capable of measuring and do not doubt the numbers. We know volume is decreasing faster than area or extent, which affirms his measurements. It is the generalization and conclusion he makes, which does not appear to be scientifically based - unless he is just stating that the 0.8 meters of ice in his area of measurement could melt away in one to two years, which is certainly possible, agreed. If he did refer to the Arctic as a whole and state it is possible for the Arctic sea ice to melt away in less than two years, then he needs to substantiate the argument, as this is an extreme standpoint, to say the least.
Yes, I fully agree with you Neven.
Sorry, I should have simplified the metric: One gigaton equals 1KM^3 of water, ie. about 1.1KM^3 of ice in a compressed state. The 12 gigaton of precipitation therefore corresponds to about 13KM^3 added to the ice sheet, being 2% of the 530KM^3 mean growth for the entire freezing season (1990-2011 reference), and this low is likely to provide further accumulation as it moves North today and tomorrow.
On Atlantic lows: A significant Atlantic low moving towards the Arctic dumped a very significant amount of precipitation on Greenland yesterday, adding an impressive 12 Gigaton of snow (Corresponding to 12,000,000,000,000 liters of water in one day): As you see on the "Accumulated" tab, the Surface Mass Balance has been positive since September 1st due to the above-normal level of Atlantic lows moving North along the east coast of Greenland. The same lows, which have extended the Arctic sea ice melting for another week this year.
Colorado Bob, In all fairness, the statement from Professor Wadhams seems to be more political than scientific, leading up to the climate discussions taking place tomorrow. PIOMAS has average sea ice thickness at around 1.40M, so it was not really "the Arctic sea ice" on average that was 0.8M, but probably the average in the area surveyed this summer by the Oden (which was near Laptev and ESS and not on the CAA side of the Arctic). To note that Arctic sea ice in general could melt out in one to two warm summers, making this seem like a probable scenario, does not have scientific validity, as the chance of this happening must be very insignificant. Professor Mark Serreze was included in the same article: "Professor Mark Serreze, director of NSIDC – who will also speak at the Royal Society – agreed with Professor Wadhams that the ice cap was disappearing and added that it would eventually shrink below one million square kilometres (386,000 square miles), therefore reaching the definition of an "ice-free Arctic". He did, however, add that he believed that this would take longer that Professor Wadhams predicted."
Thanks Chris! I would be interested in knowing what the DMI ice team thinks of the possible impact of a strong NAO index, so may try to reach to them.
Toggle Commented Sep 16, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Thank you for another great update Neven! - and your perseverance in spite of all the distraction above. I just had one note to your comment on the DMI 80N: "And even though temps are now dropping on the DMI 80N temperature graph, we're not yet seeing the upward spikes that usually indicate that the Arctic Ocean is massively releasing its heat so that it can refreeze" You are correct, but that is a good thing (from the ice/polar bear perspective): We are not seeing the spikes yet because the ice condition near the Pole has slightly improved since last year this time, and improved a lot since two years ago at this time. The temperature could drop just a bit more, before the spikes start occurring - which they certainly will given the immense Laptev Bite this year.
Hi Chris, It is correct that the NAO is a subset of the AO - the NAO is simply the Atlantic component of the AO. I am interested in the NAO, since this oscillation shows in one mode (negative) an increase in Atlantic moisture moving north into the Arctic region, while in the opposite mode (positive) less moisture moving north from the Atlantic. It is interesting to analyze if this transport of Atlantic moisture impacts the Arctic sea ice and SST during summer months. Since I specifically am interested in analyzing a hypothesis on the transport of Atlantic moisture and the NAO is just a subcomponent of the overall AO, which includes the entire Northern Hemisphere, why on Earth would it have relevance to use AO numbers and not NAO numbers for the analysis of Atlantic moisture transport???
Toggle Commented Sep 13, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Michigan March 2014 was fifth coldest on record and not far from record cold. You find the four most severe Arctic outbreaks during the month of March in Michigan in the period of 1899-1960, where severe Arctic outbreaks in general were much more frequent. The argument from Dr. Francis as has previously been discussed, seems still to be theoretical and not yet reflected in actual climate data, but if you believe so please show this.
Toggle Commented Sep 12, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Hi Susan Anderson, You wrote: "With some hesitation I'd like to address the Arctic incursions we've been experiencing in parts of the US and Europe. They affect me when I'm in New Jersey (my parents' house, up for sale, has lost value due to multiple storm events and damage, and cleanup work has been extensive with ice downed trees and new deaths in the garden from the deep freezes), but are much worse to the west and south, particularly where freezing is not a regular occurrence (Georgia, for example). Other regions are quite hot, it's that central bulge coming down through Canada that has been repeating and has not stopped even over the summer." You need to look at the US temperature record: When you do that, you see these temperature deviations and rankings (Coldest year since 1895 being '1') for the winter months of 2014 for NJ and Georgia: New Jersey: Jan: -3.6, 22nd Feb: -1.0, 44th Mar: -3.9, 18th Georgia: Jan: -6.0, 6th Feb: +1.3, 76th Mar: -2.5, 29th The largest deviation of these two states for the winter months of 2014 was January in Georgia, ranking 6th coldest. Please note here that the five Januaries with stronger Arctic outbreaks all were prior to 1980.. Indiana was near the center of the Arctic outbreaks and had Jan, Feb, and March ranking 10th, 13th, and 13th coldest. Please do some more research on the actual temperatures yourself, but all you will find is that the past winter was cold in the eastern US, but it can only be considered really cold on the backdrop of many warm winters in the past 10-15 years..
Toggle Commented Sep 12, 2014 on PIOMAS September 2014 at Arctic Sea Ice
"Yes the AO/NAO are essentially the same thing." No. The AO is very broadly defined across the northern hemisphere, while the NAO specifically shows the relation between Iceland lows and Azores highs - which is an important index. AO: "The Arctic oscillation (AO) or Northern Annular Mode/Northern Hemisphere Annular Mode (NAM) is an index (which varies over time with no particular periodicity) of the dominant pattern of non-seasonal sea-level pressure variations north of 20N latitude, and it is characterized by pressure anomalies of one sign in the Arctic with the opposite anomalies centered about 37–45N." Negative AO therefore typically causes the Arctic jet stream to become more wobbly, while a positive NAO tends to have the opposite effect. Last winter we had a positive AO, but wobbly jet stream, so Arctic weather was clearly impacted from elsewhere, which Jai has pointed out. NAO: "Through fluctuations in the strength of the Icelandic low and the Azores high, it controls the strength and direction of westerly winds and storm tracks across the North Atlantic. It is part of the Arctic oscillation, and varies over time with no particular periodicity." As I see it, the AO is too broadly defined to be useful, while the NAO and the PNA provides an improved level of insight into how atmospheric conditions in the Northern Pacific and Northern Atlantic are influencing Arctic weather and ice conditions.
Toggle Commented Sep 12, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Chris and Neven, I still find that you are both off track with regards to the influence and importance of the NAO. Chris wrote: "3) The AO/NAO has not in the past been associated with the unusually high geopotential heights seen over Greenland." This is not correct. See this article from DMI explaining the exceptional high in 2012: Key note from this article: "Our analysis allows us to assess the relative contributions of these two key influences to both the extreme melt event and ongoing climate change. In 2012, as in recent warm summers since 2007, a blocking high pressure feature, associated with negative NAO conditions, was present in the mid-troposphere over Greenland for much of the summer." And see this article (NOAA) comparing the conditions in Greenland in 2013 to the 2007-12 period: From this article: "Meteorological Conditions In contrast to the previous six summers, summer 2013 was characterized by a positive North Atlantic Oscillation (NAO) and persistently lower-than-normal 500 hPa geopotential heights. Consequently, warm, southerly air masses were diverted eastward away from Greenland and cool northerly airflow in west Greenland (see Fig. 4 in the essay on Air Temperature) promoted cooler, wetter and cloudier weather than normal, and less melting than in recent years, as reported above. This is reflected in the NSAT data (Table 7), which show that during the summer months (June, July, August) NSAT values were generally near or below one standard deviation of anomalies relative to the 1981-2010 baseline period, indicating that summer 2013 NSATs were "normal" with respect to that period. " Are you sure you want to hold on to that argument above?
Toggle Commented Sep 12, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Neven, you wrote: "2014 in principle was similar to 2007-2012, atmospherically speaking" I really do not think so - let me again provide the NAO JJA perspective: 2007: -1 at max/short period 2008: -2.5 at max 2009: -1.8 at max/short period 2010: -2.3 at max/extensive period 2011: -2.1 at max/short period 2012: -2.7 at max/extensive period 2013: +1.1 at max 2014: -1.3 at max/short period From this: 1) 2007, 2009, 2013, and 2014 had weak NAO signals, where 3 of 4 (2009, 2013, and 2014) were rebound years. 2) 2010 and 2012 had the combination of strong negative NAO and extensive period and had the strongest ice losses of these years. Prior to 2008, strong negative NAO during summer months was quite uncommon, and since 1979 only occured in 1980, 1993 and 1998..
Toggle Commented Sep 11, 2014 on PIOMAS September 2014 at Arctic Sea Ice
And a note to counter my reliance on placing a lot of weight on simple indices like the NAO: We have NAO slightly positive, which should reduce moisture transport to the Arctic, but note the stationary low west of France/Spain and the high across North-Western Europe, which in the coming days will lead to the opening of a highway of Atlantic heat and moisture to the Arctic region in spite of the NAO index. This shows just how difficult it is to analyze past weather patterns without looking at the weather surrounding the Arctic in great detail.
Toggle Commented Sep 9, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Chris wrote: "I'm looking at the atmosphere for the answer as to why 2014 was such a boring melt season." The question is really, whether you find the primary driver of change is weather or AGW. Let me illustrate: A - Moderate/weather perspective: 2007 was a special melt year with excessive transport via Fram combined with very high in-situ melting in Beaufort caused by high pressure and weather conditions overall. 2007 was then followed by a number of years (2008, 2010, 2011, and 2012) with highly negative NAO during summer months, bringing excessive heat and moisture to the Arctic, widening the sea ice loss established in 2007. This summer: Since the ice-loss of 2007-2012 was excessive due to special conditions in place, it would only require normal atmospheric and weather conditions for the sea ice to regain some of the excessive volume lost in prior years. vs. B. AGW superceeding weather: 2007 was finally the evidence that Arctic sea ice cannot withstand the onslaught of additional heat accumulated in the atmosphere and oceans due to AGW. This was inevitable. Subsequent ice loss until 2012 only confirmed this, and shows Arctic sea ice loss accelerating due to the loss of MYI and overall poor compactness/integrity of the ice pack. This summer: Requires identifying the special conditions allowing ice volume loss June-September to be the lowest since 1996. While it should be clear to all that AGW is changing our climate (Well, not clear to all, as we see above), the overall recognition of increased forcing due to increase in CO2 does not help to understand inter-year changes, so I lean towards point A, when trying to understand what is happening each specific year, making it different or similar to other years. Also, I would note that summer volume loss in the 1990s was taking place at lower latitudes than now due to the higher extent numbers back then, so also in this respect it is not surprising to me that the remaining ice will have a certain level of protection due to its position in the high north. People seem to expect a sudden crash of Arctic sea ice in front of their eyes, but consider that even with the increase in volume this year, we have witnessed a reduction in volume of 40% from 2001 to 2014, which is alarming. To conclude, IMO this boring melting season saw an increase in sea ice volume due to the absence of special atmospheric conditions, weather or current. A small recovery, but not changing the longterm path towards an ice-free Arctic.
Toggle Commented Sep 9, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Hi Neven, Thank you for another great PIOMAS update for August! It is overall a great update, but I have a comment on the PICT metric, where you wrote: "..the 2014 trend line on our PICT graph made a deep dive followed by a steep climb during August. This probably has to do with CT SIA finally starting to drop faster from mid-August onwards, meaning that the volume gets spread over a smaller ice pack, and thus average thickness goes up." As also commented on the ASI 8 update, I would say that the drop in PICT early August (apparent thinning of ice thickness) to a significant extent was caused by a decrease in melt ponds, which makes CT area numbers show reduced or no melt (Day 215-229 on the CT Area chart). So if you keep the area number unchanged, but PIOMAS registers volume loss, it will look like thinning of the pack. The same way, when warmer air entered the Arctic from day 229, this increased surface temperatures and melt ponds, which caused area numbers to go down again, and PICT to go up, creating lots of 'noise' and challenges of seeing actual change in ice thickness. I don't know if this can be helped. Dividing PIOMAS by IJIS extent would eliminate the melt pond noise, but would introduce an unrealistic measure for thickness. Ideally an indicator for 'melt pond-fraction' should be used to establish a more reliable CT area number..
Toggle Commented Sep 8, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Thank you for the analysis Chris! However: You are testing for a direct correlation between the NAO value and the summer ice extent. What I mentioned in my hypothesis (on the SEARCH thread), was that an 'undecided' NAO value would eliminate NAO as a factor, which therefore means that summers where this is the case, it is not valuable for analysis (at least for my hypothesis). - and it is quite likely my guestimated NAO values for when it has an impact, are quite wrong. Since you did not find much difference between area and extent data, I did this: List years since 1979, where the NAO index reached a negative value of at least 2 (strong negative NAO), and then added: * = Happened during summer, and # = Resulted in significant CT Area decline This is what it looks like: 1993: * # 1998: * # 2005: 2006: 2008: * # 2010: * # 2011: * # 2012: * # Based on this, it appears that: - Most periods with strong periods of negative NAO occured within the last 10 years, and - If this occured during summer months, CT area turns sharply towards a negative anomaly either immediately or with 4-6 weeks delay I would also note that the strong negative NAO during the fall of 2006 fits nicely with the record low CT area reached that same fall. The big challenge of course is the tremendously short period, but it does look like a pattern to me. Thoughts?
Toggle Commented Sep 5, 2014 on Ever sailed to 85N? at Arctic Sea Ice
Fully agreed Kevin.
Toggle Commented Sep 5, 2014 on Ever sailed to 85N? at Arctic Sea Ice