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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 8 hours ago 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 3 days ago 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 4 days ago 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: http://www.ncdc.noaa.gov/cag/time-series/us 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 4 days ago 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 4 days ago 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. https://farm4.staticflickr.com/3858/15166606982_47c6d17e6b_o." This is not correct. See this article from DMI explaining the exceptional high in 2012: http://onlinelibrary.wiley.com/doi/10.1002/joc.3743/abstract 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: http://www.arctic.noaa.gov/reportcard/greenland_ice_sheet.html 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 4 days ago 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 5 days ago 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: http://globalweatherlogistics.com/seaiceforecasting/gfs.850mb.height.vort.arctic.html 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 7 days ago 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 7 days ago 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
Adding a few more years for reference: Year Day 243 Volume Y2Y Diff. 2001 12431 2002 10975 -11.71% 2003 10439 -4.88% 2004 10157 -2.70% 2005 9543 -6.05% 2006 9395 -1.55% 2007 6652 -29.20% 2008 7823 17.60% 2009 7235 -7.52% 2010 4838 -33.13% 2011 4607 -4.77% 2012 3932 -14.65% 2013 5574 41.76% 2014 7220 29.53% As you see we had a major drop in volume already back in 2002, then the record-setting drop in 2007 (in Kkm^3), and finally the largest interannual drop in 2010 (in %) followed by additional decline in 2011 and 2012. While the longterm downward trend has been clear for a long time, you cannot fully explain the 33% drop in volume in 2010 by increase in forcing caused by CO2 increase. Since these extraordinary drops therefore are partly caused by atmospheric or other factors working to enhance the AGW effect, it will also necessarily be the case that the same factors in the opposite mode will reduce or even for a year or two neutralize the AGW effect. There is no more to it. We observe the ice and we learn. If the ice gains additional volume in 2015 and then additional volume in 2016, perhaps the PIOMAS team needs to consider either the angle of the trend line or if it should not be linear, but none of this would change the fact that the Arctic sea ice is in decline. I will stop now, Neven, anticipating your PIOMAS update and comments.
Toggle Commented Sep 5, 2014 on Ever sailed to 85N? at Arctic Sea Ice
jdallen, I am sure it will. 'Recovery' depends on the vantage point and my vantage point in the note above was the catastrophic year of 2012. Adding a few more years in the volume comparison below for last day of August, you see that even last year the ice volume had recovered (sorry, can't help myself here) to exceed the volume of 2011 and 2010, thus having more than restocked what was lost in 2012. In 2014, the Arctic ice volume has increased over last year by nearly the same increase in volume, getting close to the 2009 level. But as stated above, the current volume still does not stand any comparison to pre-2007 conditions. Year Day 243 Volume Y2Y Diff. 2006 9395 2007 6652 -29.20% 2008 7823 17.60% 2009 7235 -7.52% 2010 4838 -33.13% 2011 4607 -4.77% 2012 3932 -14.65% 2013 5574 41.76% 2014 7220 29.53% Area and extent numbers are similar to 2013, but with average thickness around 1.40 meters compared to 1.10-1.15 meters last year, the difference is significant in ice compactness and quality. Casting doubts around the validity of PIOMAS data I don't think is helping your case, since PIOMAS is both one of the best models in place to assess Arctic ice volume, and secondly that anyone looking at the trend lines for ice volume at the PIOMAS site, will be left with no lack of clarity as to where we are headed..
Toggle Commented Sep 5, 2014 on Ever sailed to 85N? at Arctic Sea Ice
Hi Neven, I had used the CT archive, as I either don't know how to search the AMSR2 image archive, or it is not there. It seems, however, when comparing Bremen maps with other ice concentration maps, e.g. from DMI, that Bremen cuts away low concentration areas (30% or less), which is why I made the note regarding CT showing a small area of 30%. I guess it all depends on the chosen vessel in the end.. ;-) http://ocean.dmi.dk/arctic/icedrift_anim/index.uk.php Steve, I know there is a lot of sensitivity with a word like "recovery", but just look at ice volume for the last day of August for 2012, '13 and '14: Year KM^3 Y2Y Increase 2012 3932 2013 5574 41.76% 2014 7220 29.53% The volume having nearly doubled in two years is recovery in my vocabulary. It still doesn't mean the ice is in good shape, as it was in an extremely poor state two years ago, which comparison to any year prior to 2007 will show.
Toggle Commented Sep 5, 2014 on Ever sailed to 85N? at Arctic Sea Ice
Regarding IJIS Sept mean extent, as I wrote on July 25: "Based on weather in the past couple of weeks, low temps/cloud cover plus outlook for AO and NAO, I would no longer be surprised, if 2014 Sept extent and area will be in tight competition with 2013. I find it unlikely that Sept extent should be less than 5.0M KM^2 at this point." I will stick to that estimate, with a best estimate for Sept. mean extent to be 5.4-5.6Mkm^2.
Chris Reynolds, Thank you very much for your response. The AO and NAO are two very different indicators, since the AO has to do with highs and lows within the Arctic region, while NAO provides information about North-Atlantic atmospheric conditions. From a relationship perspective, it seems that positive NAO during summer months allow Arctic lows to enter the Arctic region from the Kara/Laptev area, causing a higher probability of the AO turning positive (causing Arctic cyclones), as it did in 2013. The same way, a negative NAO during summer months appear to have some correlation with AO turning negative (Arctic highs), but this is less clear. There has been a lot of research on winter-time NAO impact on Arctic conditions, but much less on NAO during summer, so any references are anecdotal and not well documented. I have a simple theory on NAO based on these principles: - Negative NAO index during DJFM is good for Arctic sea ice - For the remainder of the year, a positive NAO index is good for Arctic sea ice - Non-decided NAO index (-0.8 - +0.8) eliminates the NAO as a factor for Arctic sea ice preservation Why Negative NAO during DJFM is good for Arctic sea ice: - Inflow of warmer, moist Atlantic air increases precipitation/snow cover in Arctic regions as well as Greenland - Increase of snow cover on sea ice, delaying the onset of spring melting - Increase of Arctic heat sink effect, lowering NH temperatures, makes use of surplus Arctic cold in deep winter where ice growth is limited Why Positive NAO for the remainder of the year is good for Arctic sea ice: - Heat energy from Atlantic moisture moves east across Northern Europe prior to entering the Arctic region, causing less heat to enter the Arctic There are certainly other important factors involved, but against the records of ice extent there has been a very good correlation, although I admit I have not run the calculations. I would not use area data for summer sea ice due to the known uncertainty of this metric during summer months.
" It's much wider and further into the pack, further than I have ever seen it go." Well, on Sept. 1, 2012, the Laptev Bite went further towards the Pole than this year by simple visual difference from open water to the blurred area around the Pole: http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=09&fd=01&fy=2012&sm=09&sd=01&sy=2014 Also, on Sept. 1, 2013, we had open water much closer to the Pole than Sept. 1 this year, only with a small branch of 30% concentration slush ice in the way: http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=09&fd=01&fy=2013&sm=09&sd=01&sy=2014 With regards to level of damage to the ice from the Laptev side, I would argue this year therefore is slightly better than the previous two years, but only slightly, since the starting point of every season only is as good, as where things were left off at the end of the prior season. Since the Atlantic side of the Arctic has been battered hard for a number of years now, it is not surprising that recovery is very slow here, while it has been more substantial in the Canadian/Pacific side and from there towards the Pole.
Toggle Commented Sep 4, 2014 on Ever sailed to 85N? at Arctic Sea Ice
Hi Chris, Thank you for the extensive analysis/review of this years melting season. While I am in agreement with your overall analysis and conclusion, I was wondering why you did not cover at all the NAO. Since the NAO has been in a negative phase during summer months of 2007 - 2012, but positive or neutral in 2013 and 2014, it would seem reasonable to discuss how the change in athmospheric circulation during summer months impacted the conditions either favoring or to some degree slowing down ice melting.
Lewis, Neven, "Neven - to what extent does the pronounced cold patch east of Spitzbergen in the SST Anomalies plot reflect a lack of penetration by the Gulf Stream ? Very good question, Lewis. I'm wondering the same." Let me help: The cold patch on the Atlantic side of the Arctic is caused by the NAO being near neutral much of this summer. I have referenced the NAO data for prior summers a number of times, so will not repeat this, so let me instead refer to DMI in their analysis of the record melt in Greenland in July 2012: "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. This circulation pattern advected relatively warm southerly winds over the western flank of the ice sheet, forming a ‘heat dome’ over Greenland that led to the widespread surface melting. Both sea-surface temperature and sea-ice cover anomalies seem to have played a minimal role in this record melt, relative to atmospheric circulation." http://onlinelibrary.wiley.com/doi/10.1002/joc.3743/abstract So if you want to know more about the Atlantic side of the Arctic, you need to know about the NAO.. ;-)
Toggle Commented Aug 25, 2014 on ASI 2014 update 8: neck and neck at Arctic Sea Ice
Regarding the Laptev Bite: DMI has some great tools to see what is happening: http://ocean.dmi.dk/anim/index.uk.php When you select 'ice thickness' you see how the ice is being weakened all the way to the Pole and then turning towards the Atlantic side. With the 'surface current' and more significantly with the 'ice drift' view, you see that the warm waters of the Laptev Sea is moving under the ice, probably causing significant bottom melt and destabilization of the ice. The low currently right above Franz Josef Lands combined with melt water from Siberian rivers should be main factors, so with the low moving towards the western side of the Arctic, the current should ease, allthough this low will cause plenty of water/ice mixing, which will at least deteriorate the edges of the pack around the Arctic in the coming days. I would think this major low is probably causing the last major melting event of the season, as temperatures have started going down with the sun moving south.
Toggle Commented Aug 22, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
wayne, Everybody is aware that the models used to estimate sea ice area and extent have limitations. They provide estimates. The models do have some value from a comparative year-over-year perspective, when you compare e.g. CT Area estimates for August '14 against CT Area estimates for prior summers. In addition, there is value in the the relationship between e.g. CT Area and IJIS Extent, due to the difference in how these models calculate ice area and extent.
Toggle Commented Aug 21, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
Hi Pete, You are right that it is interesting to analyze ice loss from max to min and that we see variance here. Below I added PIOMAS ice volume for day 105 (near max) and day 212 (end of July) for 2003, 07, 12, 13, and 14: Year Day 105 Day 212 Diff. 2003 27319 13149 14170 2007 23798 9172 14626 2012 23144 6676 16468 2013 23261 7795 15466 2014 23115 9575 13540 As you see, we did not start out this year at a favorable position, but weather was siding with the ice, not bringing much heat to the Arctic region. When you look at the numbers above, it is also interesting that the melting in 2007 was not as extreme as has often been referenced, but that primarily there was a significant reduction in winter ice build-up in 2006-07. This lack of freeze can be seen on CT area for fall/early winter of '06, and the reason IMO can be found on the NAO index, which shows a sharp negative spike for the same period, indicating a strong flow of Atlantic moisture moving North and delaying the ice build-up: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/month_nao_index.shtml
Toggle Commented Aug 20, 2014 on PIOMAS August 2014 at Arctic Sea Ice
OMG, the Arctic snow rabbit Manneken Pis has entered the stage today: http://ocean.dmi.dk/arctic/weather/arcticweather_imagecontainer.php
Toggle Commented Aug 20, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice