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John Christensen
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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 6 hours ago 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 6 hours ago on ASI 2014 update 7: late momentum at Arctic Sea Ice
wayne, you need to study.. Try this: http://neven1.typepad.com/blog/2010/08/area-vs-extent.html Or this, to get the detailed version and a possible technical solution: http://www.the-cryosphere.net/6/431/2012/tc-6-431-2012.pdf From the latter paper: "The retrieved MODIS sea ice concentration shows, that sea ice concentration derived from microwave sensors underestimates the actual sea ice concentration by 40 %."
Interesting article on decline in Arctic ice snow cover: http://climate.nasa.gov/news/1140/
Sorry; I calculated CAPIE based on the latest numbers from CT area and IJIS extent, but as the CT is a day or two behind IJIS, I did not calculate based on numbers from the same day and therefore overestimated the CAPIE value. The actual value should be 75-76% based on numbers from the same day, which is still very high, but not off the charts.
Hi philiponfire and wayne, The difference between area and extent calculation is the reason. When you look at the comparative images of CT area of 8/7 and 8/14 this year, you see why the area number is not going down: http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=08&fd=14&fy=2014&sm=08&sd=07&sy=2014 In the Beaufort and ESS, you see ice concentration levels increasing from 60% to 80-90% in many areas. This will cause the CT area to increase, but will have no impact on calculation of ice extent at DMI, ROOS, or IJIS. Evidently, ice concentration did not go up from 60 to 80-90%, however. Models calculating ice area tend to include melt ponds as open water. When melt ponds either freeze over or have a fresh snow cover, the satellite again will see it as ice, and bingo: The ice area has increased, even though in fact, the satellite is just again recognizing the ice, which was always there.. In the past week, the reduction in melt ponds across Beaufort and the ESS in particular was about the same as the actual melt around the edges of the pack, so the area number has stayed 'flat'. This is why, as I believe Neven has explained a number of times, many scientists monitor ice extent during summer, or both area and extent, and why the CAPIE number is very interesting. Calculated yesterday, CT area / IJIS extent was 79.45%, which is extremely high, as you see from Neven's graph above, meaning we currently have a very consolidated pack with unusually few melt ponds. I hope this helps.
But agreed, the CT area numbers are remarkable!
Hi philiponfire, Yes, the edge of the pack is still melting, overall reducing the volume of ice. However, as melt ponds are being snowcovered or freeze over, this will increase the area number (satellite sensors used for area calculations 'see' melt ponds as water). CAPIE shows the relationship between area and extent, and as unusually high this year, explaning this phenomena.
Agreeing with jdallen that we should focus on the ice - or lack of the same.
Hi Christoffer, """To add to the above map is a link with number of fires in 2014: 365 & number of hectares affected: 2,856,670.90"" That's almost 3 times larger area than all cultivated farmland in Norway...phew!" Interesting to chose Norway for that metric - of all countries in the world, only Singapore has a lower percentage of agricultural land in percentage of country area.. ;-) http://www.helgilibrary.com/indicators/index/agricultural-land-area-as-of-country-land-area Other noteworthy elements of agriculture in Norway (in case there would be anyone wanting to contemplate any relationship between Norwegian agricultural statistics and forest fires): The agricultural production in Norway covers 50% of their need for food and employs about 2% of their workforce. But they do like their oil, these Norwegians..
Hi Blaine, "Of the major single dimension projections of the surface pressure field, the NAO is proably the best predictor of sea ice melt. Take a look at the slightly postive NAO pressure field for July, though. That's a lot of sunshine over the Arctic Ocean, even with the slightly postive NAO." You are mixing two indices here: The NAO tells something about blocking highs in the Northern Atlantic. When the NAO is negative more heat moves northward into Barentz and swirls counterclockwise into the Arctic. When the NAO is positive, the Atlantic heated moisture moves east across Northern Europe and losses energy, before it enters the Arctic from around the Laptev Sea. The AO, however, is an indicator of Arctic high and low pressures - i.e. clear skies vs. cloudiness and storms. Negative AO means high pressure, positive AO low pressure. Both indices for July were weak in their signal, both sligthly negative meaning predominantly clear skies, but relatively low heat influx from the Atlantic side. I say relatively low, as the sligthly negative NAO should still allow some heat moving North, but this is still low compared to prior summers of 2008, 2009, 2010, 2011, and 2012, as you see here: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/month_nao_index.shtml What is scary is that the summer of 2007 looks very similar to 2014, but with the main difference (Not considering here the major impact of Fram transport in '07) that the negative AO came earlier, so to Neven's point, maybe the setup in late April - mid May is so crucial, as the early formation of e.g. melt ponds will enhance the consequences of weather conditions favorable to ice melting later in the season..
Hi Neven, "In the meantime we watch what this late momentum can still achieve and whether 2014 might still end up below 2013. The race is on." While it is still too early for a verdict, I would say the past three days have shown that the vast high across the western Arctic did not manage to impact area or extent much, at least as seen on IJIS, CT, ROOS, and DMI. Not saying the rendering of data compared to reality is exact, but compared to 2012 and 2013 by the same models, melting has slowed down these past few days. What IMO makes this possible - in addition to the temporal distance from solstice - is the lack of heat transported to the Arctic as indicated via the NAO index. As you see from the link, the summer months of 2008, 2009, 2010, 2011, and 2012 had significant negative NAO index between -1 and -2 or beyond -2, while the NAO was positive during the summer of 2013 and only sligthly negative (0 - -1) this summer so far: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/month_nao_index.shtml One could argue that significantly negative NAO had become part of the new normal in the post-2007 Arctic environment, which would have accelerated the breakdown of Arctic sea ice, but with the data from 2012 and 2013, it appears the NAO is still following whatever natural or chaotic variability pattern. If the current NAO forecast holds, it will move to the -1 - -2 area in a couple of days, so let's see if this will change things, elevating temperatures, allowing more melt ponds to form, before the NAO will get closer to neutral again about a week from now.
Hi wayne, I appreciate your patience with me - yes, I see that the area to the right (between the Pole and Franz Josef Land) is of significantly lower concentration. CT did not indicate this, but now (8/10) indicates a 60% concentration in this area, which seems reasonable. The sensors and algorithms have always had challenges providing accurate measurement, but since we are using the same approach for measuring (as broken as it may be, e.g. overstating the ice area), we have comparable information between each year, unless you find we have a special situation this year, which would fool the sensors to a more significant degree than prior years?
Toggle Commented Aug 11, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
Hi wayne, Your link shows broken ice and low concentrations all the way to the Pole, but the date of the images is 8/28-2013, not 8/5-2014. When you look at the latest image (8/11-2014), you see the ice has cracks and some melt ponds, but overall has good concentration near the Pole. "Melting has to be virtually all but done before it gets counted". You would need to discount the integrity of the PIOMAS model to claim this. The combined area for Beaufort and Chuckchi is slightly higher than last year, so certainly there will still be melting, but my point above was that we need a 700K km^2 drop in area in the CAB to align with 2013. The ice being thicker overall, I do not see how this level of melting can be realized, but let's see..
Toggle Commented Aug 11, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
And finally - as is true for any classic battle - how the melting season ends will be decided at the center, in the CAB, where we currently have 1-200K km^2 ice more than last year (CT area), and last year the CAB dropped another 500K km^2 between now and minimum due to the low concentration values in many areas and near the Pole, and continued lows. With the lack of heat transport (near neutral NAO) or Fram transport, and near consistent low 80N DMI temps, and with the high weakening shortly, but no significant low entering the CAB, it seems the CAB will fare significantly better in 2014 than 2013, which again very likely will cause area, extent and volume numbers to exceed those of the 2013 melting season for the entire Arctic area.
Toggle Commented Aug 10, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
I am terrible with links and images, but the latest DMI 60N temp image shows exactly the night on the 'western side' with negative temps from the CAA across to the ESS (10.56PM CET): http://ocean.dmi.dk/arctic/weather/arcticweather.uk.php
Toggle Commented Aug 10, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
Thanks again Neven for a great update! I am nearly always in complete agreement with you, but for this update maybe slightly less so. As was discussed last summer, I had indicated that weather for great ice conservation would be different for late spring/early summer, as compared to late summer, as also seemed to be in agreement with the articles of your great entry 'On persistent cyclones'. As much as arctic lows/stormy weather is great in keeping temps down for late spring/early summer, as well as spreading ice/keeping ice cover up, the opposite should become the case at some point in August: The ice does not support well any increased mixing with the top water layers, which by now have been considerably heated. Secondly, by now the sun is moving south (midnight sun at around 78N only) and Beaufort, Chuckhi, ESS, and Laptev again changes between daylight and probably 3-4 hours of night, so that with a high pressure, temperatures will drop to negative temperatures for some hours every day, slowing down the melting process. Not sure if that date in August has been reached, where a high is better for ice conservation than a low, or if by now, both scenarios would have similar impact, and that other factors such as Fram transport and NAO/Atlantic heat transport are the remaining factors of major influence left.. The NAO could be turning slightly more negative in the coming week, which I would be more concerned about, but let's see if this materializes: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao_index_ensm.shtml
Toggle Commented Aug 10, 2014 on ASI 2014 update 7: late momentum at Arctic Sea Ice
Great update, thanks Neven! D, Agreed that Atlantic heat is there, but unless we see the NAO going significantly negative, little of that heat will invade the Arctic. The NAO forecast shows a sligthly negative forecast for the next week in the 0 - -1 area, but prior summers have shown you need negative NAO of -1 - -2 for heat transfer to pick up significantly (which many recent years have had, but not 2012 and 2013): http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html
Toggle Commented Aug 6, 2014 on PIOMAS August 2014 at Arctic Sea Ice
Hi Pete W, I would agree with your point, if you are trying to say that the AMO is important, and that there is a nice correlation between the current warm phase of the AMO and the Hadcrut temps for 20-60N, with the graph that you mentioned. Global Warmning fanatics will probably claim that the AMO is rather irrelevant, while climate change deniers will claim that changes in the AMO is driving the temperature change and CO2 is irrelevant, or a miniscule factor. The truth evidently is between the two extremes: - There is a strong correlation between the phase of the AMO and changes in global surface temperatures - BUT, the global temperature in the negative AMO phase of early 1960's to 1995 did not quite return to the level of the last negative AMO phase, early 1900's - 1930 - And yes, the change from negative to positive AMO phase seems to explain part of the global temperature increase reaching the peak in 98' combined with the strong El Nino, and also is part of the explanation why the global temperature did not continue increasing as fast after 98' Then consider PIOMAS ice volume data: January 1, 1980: 25.039 km^3 January 1, 1994: 22.321 km^3 January 1, 2008: 16.648 km^3 It dropped 10.9% between 1980 and 1994, and then 25.4% between 1994 and 2008. So, yes, the move from negative to positive AMO had a significant impact, but it only accelerated, what was already happening. There is therefore no return to prior state of ice e.g. 10 years ago, even if we have impressive ice area and extent numbers these days. If ice volume would reach the level 10 years ago, we can talk..
Toggle Commented Aug 2, 2014 on ASI 2014 update 6: slow times at Arctic Sea Ice
Hi wayne, The argument for area going up during melting conditions would be that movement and fragmentation of the ice pack causes cracks and leads to appear, which drains melt ponds from the ice surface. It would be plausible that melt ponds prior to 2007 could remain for longer periods - resting on a stable MYI pack - and that in recent years we are seeing increasingly that the many, fine fragmentations of the thinner, primarily FYI pack causes melt ponds to be drained, not freezing up. Melt ponds trick the sensors providing us area numbers into believing ice is replaced by water, so when a melt pond is drained, the sensor will see the ice area increasing. If draining of melt ponds outweigh actual ice area reduction caused by melting, the area number will go up. This is why we still like the extent number also, to review both in comparison, since the extent number does not have the 'melt pond flaw'.
Toggle Commented Jul 30, 2014 on ASI 2014 update 6: slow times at Arctic Sea Ice
Hi wayne, Extent and area will under certain conditions move in the same direction, but under other conditions move in opposite direction: General freezing conditions: - Both area and extent increase General melting conditions, little wind/current: - Both area and extent decrease Melting conditions, strong wind/depression: - Can temporarily cause extent to increase due to fragmentation, and can also cause area to increase due to reduction in melt ponds Melting conditions, medium wind/ice compaction: - Can cause area to drop slightly or even to increase if slight fragmentation takes place and melt ponds are reduced, but extent to drop significantly due to melt and compaction at edges The lack of drop in area this year and last year during the last week of July, I would mainly see as consequence of reduction in melt ponds, which outweighs level of melting at the edges of the pack.
Toggle Commented Jul 29, 2014 on ASI 2014 update 6: slow times at Arctic Sea Ice
Thanks for the feedback Neven! The impact of AO on arctic ice mass changes is less obvious, and I prefer also tracking forecasts to get more details on where the lows and highs are positioned. However, the NAO appear to impact both Greenland and the eastern/central Arctic, which e.g. DMI has described in this update for July 2013: http://polarportal.dk/en/greenland/reports/072013/ And from this update: Greenland's seasonal weather patterns are strongly influenced by the North Atlantic Oscillation (NAO). This is a regional scale pattern of high and low air pressure systems that can alternately cause cold air from the north to dominate the island (the positive mode) or allows warmer air from the south to move over the ice sheet (in the negative mode).The pattern of a cooler early July and warmer late July with more extensive melt correlates very clearly with a switch from a positive mode to a negative mode in the North Atlantic Oscillation index which occurred 15th – 18th July. The negative mode of the NAO persisted for much of the record setting 2012 season, promoting the delivery of warmer air and clear skies but has been less prominent this year. This summer the long stable period of hot sunny weather experienced in Denmark and northern Europe has in part been a consequence of the positive mode with a high pressure system centred over Scotland and to the south west of the British Isles. In contrast, this North Atlantic see-saw means that Greenland had rather cooler weather until the later part of the month when the change occurred. In late July (25th – 28th) the melt area expanded to such a large extent that the model results were confirmed by satellite observations from the MODIS sensor which showed melting in the Saddle region. This is unusual though not unprecedented and coincided with positive daily mean temperatures (up to 1.5 oC) recorded at at an elevation of 1850 m at the PROMICE KAN-U weather station for 3 days in a row (Figure 2). A further interesting feature of the melt area this year is the relatively high melt seen in Northern Greenland.
Toggle Commented Jul 29, 2014 on ASI 2014 update 6: slow times at Arctic Sea Ice
Great analysis, thanks Neven, and very much in agreement with your conclusions. I rarely hear your opinion on the NAO, but as you see we are likely to keep hovering around near neutral NAO index, which IMO will keep intrusion of warmer, moist air from the Atlantic reduced. The Barents Sea is very cold (relatively), when compared to every year since 2007, and I see no other good reason than lack of Atlantic airborne heat transport since late spring. 2008, 2009, 2010, 2011, and 2012 all had significant negative NAO index during summer months: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/month_nao_index.shtml 2007 however, would still be a different story, as NAO and AO for the summer months of this year don't fully explain what happened, and lack of ice cover in the 2006/07 freezing season was probably an important precursor also. Back to the current: On the bi-daily DMI 60N weather updates it seems like the night temperatures are starting to dip below freezing, as the 'western' and 'eastern' Arctic shows colder temps alternated by each update. I agree that given the forecast and consolidated central pack we should see reduced (though not stalled) melting in the coming week, unless the next low should cause significant water mixing in the periferal seas.
Toggle Commented Jul 29, 2014 on ASI 2014 update 6: slow times at Arctic Sea Ice
@wayne, Having following the entire process closely the past 4-5 years, I do not see in comparision between this year and last year at this date that an imminent crash is likely. Look at CT for 7/24 for '14 and '13: http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=07&fd=24&fy=2014&sm=07&sd=24&sy=2013 You see that the Beaufort was equally disintegrated last year, while Chuckchi, ESS, and the triangle between Laptev, the Pole and Franz Josef Lands all was more disintegrated a year ago. Yes, it was saved by the bell last year, which a significant low spreading the remaining ice, and low temps preventing that huge crash, which otherwise seemed likely. A reason why the crash did not happen, was that SST was quite low, relatively. Right now we have about 400K km^2 more ice area than 12 months ago, and with similar temps (dmi 80N), I would suspect most of the difference to be due to an increase in compactness of the ice, although the disintegrated ice pack last year probably also supported relatively few melt ponds - as direct consequence of the disintegration. The forecast has a larger and stronger cyclone moving to near the Pole this week, which will keep temps down, but should cause additional disintegration of ice at border areas, so agree that it will be interesting to watch to what degree the near-coast warm waters will mix with ice and cause rapid melting. The higher compactness of ice centrally in the CAB this year, however, should cause less mixing with top-water, so reduced melting in the CAB. Let's see..
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.