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John Christensen
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Great entry on the storm and obliteration of the MYI arm Neven! Just one note on your conclusion: "The Beaufort and Chukchi Seas proved to be yet again the multi-year ice graveyard instead of the transit they used to be when older ice would make a round-trip around the Arctic.." Cryosphere SIA data for Chuckchi shows that the SIA at minimum was less than 50kkm2 in: 1979, 1984, 1986, 1990, 1993, and then pretty much since 1996. Beaufort was around or less than 100kkm2 in: 1979, 1981, 1982, 1987, 1989, 1993, 1995, and then largely since 1997. It would therefore seem reasonable to conclude that these seas have melted out lots of MYI also back in the 1980s and 1990s, just that the chance of the MYI melting out in summer if present in the Beaufort or Chuckchi has increased to nearly full certainty from what was previously quite likely.
Toggle Commented 2 days ago on Arm's race (and a storm) at Arctic Sea Ice
Yes, the cyclone entering via Bering should finish off the MYI detachment and provide a good level of compaction in the Western Arctic, lowering SIE significantly, while the SIA should fare slightly better with melting ponds starting to freeze over.
Jim Hunt, The news media is all involved in the climate discussion. There are powerful economic interests on both sides, and given these interests - together with the need to please their audience, I don't see any chance that news media can be trusted overall. The Guardian ended an article with this great quotation recently: (http://www.theguardian.com/us-news/2015/aug/20/california-drought-blame-global-warming) "Jessica Blunden, a Noaa climate scientist, said that heat records like this were “getting to be a monthly thing”." This remark seems unbalanced and not warranted by observed data, and The Guardian chose it as the ending paragraph to increase the shock effect rather than checking if this could be valid. My point is that news media - and even scientists - have other interests than describing to us as accurately as possible, what is happening, and what will happen. I am not trying to get into a discussion here, and would suggest we focus on what is happening with the ice.
Toggle Commented 5 days ago on Jakobshavn record retreat at Arctic Sea Ice
DavidR, Great observation: I had never reviewed the year after a larger El Nino and so had not spotted this relationship. Looking at 1983 (El Nino ends) and 1984, PIOMAS data shows that in 1984 after reaching nearly the same max. volume as the year before, the volume declined faster from mid-March to end-June compared to 1983, and freezing was also reduced in late-Sep/Oct. of 1984 compared to 1983.
"a massive detachment of multi-year ice (I'll have more on that in a couple of days when all of the detached ice has melted out)" The fate of this MYI detachment will probably be the cliffhanger exciting question for the end of this melting season. I agreed back on Aug. 20 that this should melt out, but with the lowering of the air temps, the forecast, and the limited heat energy remaining in the nearby waters, I am no longer sure this detachment will be parting with us this year.
One note on the meaning of the DMI 80N temperature in the main melting season (Approx. days 165-230): It seems that the 80N temperature is comprised of two main factors: 1)Actual heat transported into the central Arctic area, plus heat created in situ by radiation 2) Energy exchange between water and air in open water areas Because we now have much larger areas of open water in the 80N area compared to prior decades, the energy exchange between water and air seems to reverse the overall temperature signal. Let's consider 1967: The Arctic region was dominated by low pressure areas in May, June, and July, but still the 80N temperature on multiple occasions was above the long-term average, which is opposite to what we have seen in 2013 and 2014 low-pressure summer months. Compare with 2009: Both June and July saw strong high-pressure areas across the Arctic, but the 80N temp stayed significantly below the long-term average for most of the main melting season. I would speculate that the reason why the 80N temp in 1967 was high, was that the ice cover in the 80N area was complete/near complete, allowing very little energy/cold from the water to be exchanged with the air. In 2009, on the other hand, the 80N temp stayed low. This was probably not because of lack of heat energy created above water level, but because the broken ice pack allowed a high level of cold energy from the water to be exchanged with the air. The 80N temps in the main melting seasons of 2012, 2013, and 2014 stayed low for the same reason: Very broken and scattered ice packs in the high north allowed lots of cold energy to be released to the air. In 2015, however, the ice pack in the 80N area has had less cracks and fewer areas of open water, resulting in the 80N temp again being able to spike above the long-term average, simply because the water/air energy exchange at least in this most northerly area has been reduced compared to prior years.
Toggle Commented Aug 20, 2015 on ASI 2015 update 6: one more high at Arctic Sea Ice
Thank you for a great update Neven, I am in full agreement with status assessment and conclusion. Regarding the forecast for high-pressure: After the next 3-5 days of relatively high-pressure, NOAA has forecasted a deepening of the high-pressure (negative AO index): http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml At this late stage of the melting season, this should be ideal in reducing winds (reduce ice/water mixing), keep the ice from compacting and allow more heat to escape. We will see how far this goes as to slow down melting in the coming couple of weeks - interesting!
Toggle Commented Aug 20, 2015 on ASI 2015 update 6: one more high at Arctic Sea Ice
Sorry; I need to retract that last piece: I had read the 2013 paper as saying that a factor 2 heat content increase of the IC was larger than a factor 3.6 increase of the Baffin Current, which may not be the case, and the circulation changes in the Baffin Current may therefore have played a more prominent role.
Toggle Commented Aug 19, 2015 on Jakobshavn record retreat at Arctic Sea Ice
Hi A-Team, Yes, I have read the more recent papers, both by Myers and Ribergaard (2013) as well as the new papers by Gladish et al (2015), but kept the reference to the 2008 paper, which has the most basic explanation as well as a nice graphic of the sub-glacial fjord in response to Tanada1945 above. What is new and most clearly pronounced is that more emphasis is placed on the East and West Greenland Currents (EGC and WGC), which are surface currents, in explaining the changes in water temperature impacting the Jakobshavn icefjord (Gladis et al, 2015, p. 60): "They [EGC and WGC] are sometimes as warm as 2C in summer and 6C in autumn at a[density level of] 27.0.." "Temperature variability in East/West Greenland Current polar waters therefore impacts the thermal boundary conditions of Jakobshavn Glacier." But - and this is a significant limitation, (Footnote #4, page 60 of the same 2015 paper): "It is ambiguous whether a typical East/West Greenland Current polar water parcel maintains a relatively constant salinity during its journey around Greenland, being warmed by surface fluxes, or whether West Greenland Current polar water parcels are actually the product of mixing between very cold and very low-salinity PSW and pure Irminger Current waters where they meet south of Denmark Strait. In the first case, the fjord basin temperature could be sensitive to changes in summer air–sea heat fluxes in the Greenland boundary currents, and in the second case it would be more sensitive to changes in mixing at the density front between the East Greenland Current and Irminger Current." So, it is actually hard to tell how significant the EGC (surface current) is, when explaining the impact of the WGC on the ice fjord basin temperature. And then finally from the 2015 paper (Page 60 also): However, as Myers and Ribergaard (2013) proposed to explain the warming of Disko Bay polar waters around 1997, a shift in the fraction of West Greenland Current polar waters compared to Baffin Current polar waters entering Disko Bay would also bring about major temperature changes, impacting not just the above-sill waters in Ilulissat Icefjord but also the basin waters." Myers and Ribergaard 2013 explains the impact of the Baffin Current: "This study presents hydrographic data from Disko Bay, additionally revealing that there was also a significant warming of the cold polar water entering Disko Bay from the mid-to-late 1990s onward. This layer, which lies at a depth of ~30–200 m, warmed by 1°–2°C. The heat content of the polar water layer increased by a factor of 3.6 for the post-1997 period compared to the period prior to 1990. The heat content in the west Greenland Irminger water layer between the same periods increased only by a factor of 2, but contained more total heat. The authors suggest that the changes in the polar water layer are related to circulation changes in Baffin Bay." As seen above the heat content change in the mid/late 90s was more significant with the Irminger Current than with the polar waters coming out of Baffin Bay, i.e. the Irminger Current remaining as the more significant factor. That said; for a very significant event to take place, you often need the confluence of several factors to create a perfect storm, and that seems to be what happened with the result that the Jakobshavn glacier went from a nearly immobile state to rapid retreat by the end of the 1990s.
Toggle Commented Aug 19, 2015 on Jakobshavn record retreat at Arctic Sea Ice
Last key point to make regarding the warm pulse from the Irminger Current in 1997 (Which can be seen initiated in 1996, page 5, figure 4 in the same article) and text: "Given an ocean-forced mechanism for Jakobshavn Isbræ, the question remains: what drives the change in the subsurface ocean? The warm, subsurface waters off the west Greenland coast are fed from the east by the subpolar gyre of the North Atlantic, via the Irminger current. Since the mid-1990s, observations show a warming of the subpolar gyre, and the northern Irminger Basin. A key source of variability in the forcing of the subpolar gyre is the North Atlantic Oscillation (NAO). A major change in the behaviour of the NAO was observed during the winter of 1995–1996, when it switched from a prolonged positive phase with strong westerly winds to a negative phase with weaker winds. The net effect of the change was to weaken the subpolar gyre with the consequence of moving the subpolar frontal system (the boundary between cold polar waters and warm subpolar waters) from an easterly position to a more westerly one. Such a large-scale change in the subpolar gyre allowed warm subpolar waters to spread westward, beneath colder surface polar waters, and consequently on and over the west Greenland continental shelf (Fig. 4)." This change in NAO happens to be the same that can be observed in the AO index, which went from strongly positive (Arctic low-pressure dominance combined with more northerly and stronger jet stream flow) to a negative index (Arctic high-pressure and weakened jet stream flow). From the AO data this extreme positive AO index event is visible as starting in August 1988 and ending rather abruptly by the end of March 1995. The duration and strength of this event is unprecedented in the 1950-2015 AO index record - but again; given the special geography of the Jakobshavn glacier fjord and the documented retreat of the glacier front between 1851 and 1964, there must have been prior occurrences of warm, salty water from the Irminger Current flowing into the Jakobshavn glacier fjord.
Toggle Commented Aug 18, 2015 on Jakobshavn record retreat at Arctic Sea Ice
Following the argument from the article above, it is probably quite rare for such a pulse of warm water to make it into the Jakobshavn fjord, as the glacier front was practically immobile from 1964 - 2001, after having receded significantly earlier in the 20th century.
Toggle Commented Aug 18, 2015 on Jakobshavn record retreat at Arctic Sea Ice
@Tanada1945, Look at this excellent article, page 2, figure D: http://ocean.dmi.dk/staff/mhri/Docs/Holland_et_al_NatureGeoscience2008.pdf The fjord is very deep and goes far inland under the current south part of the glacier tongue, which explains why this area is receding. As the article also argues, the major calving events tend to follow events, where warmer than usual sea water from the Irminger Current makes it across the threshold at the entry of the glacier fjord. Given the geography it seems like this glacier would continue to retreat, as it has done since measurements started in 1849. From the article also: "We argue that the 1997 warm, subsurface pulse in Disko Bay flooded the Jakobshavn ocean fjord, and that warm bottom waters have been there since."
Toggle Commented Aug 18, 2015 on Jakobshavn record retreat at Arctic Sea Ice
From the abstract of the article and as mentioned above: "..evaporation rates (i.e., moisture flux) increased between August and October.. increasing the water vapor feedback and cloud cover." "..warming skin temperatures and radiative responses to increased water vapor and cloud cover in autumn delay freeze-up." As I mentioned in my entry above, this argument does not seem to be well supported by data, which indicates that the chance of cloud cover in the Arctic region is governed by the atmospheric circulations as expressed in the AO index. I have used the monthly AO index values from the NOAA site and calculated the averages for each calendar month for the whole period as well as per decade to spot any trends (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table) NOTE: With random weather each decade should have a chance of having the most extreme value (positive or negative AO) in more than three months of the year (3.42 to be exact out of 24 occurrences) January: Average (1950-2015) -0.39 Average (1986-1995) 0.70 Average (2006-2015) -0.15 Average (1996-2005) -0.37 Average (1950-1959) -0.47 Average (1966-1975) -0.65 Average (1956-1965) -0.89 Average (1976-1985) -0.99 Comment: January is typically dominated by high-pressure (HP) and clear skies (-0.39). The period of 1986-95 was extreme with a very positive AO index value (0.70) indicating overall pervasive low-pressure (LP) across the Arctic region in this decade. 2006-15 had overall clear skies, but less so than the long-term average. February: Average (1950-2015) -0.43 Average (1986-1995) 0.22 Average (1996-2005) 0.14 Average (2006-2015) -0.38 Average (1950-1959) -0.67 Average (1966-1975) -0.75 Average (1976-1985) -0.79 Average (1956-1965) -0.96 Comment: Again a month dominated by HP with 1986-95 as the main decade deviating, followed by 1996-2005, while 2006-15 was very close to long-term average and had overall HP across the Arctic. March: Average (1950-2015) -0.16 Average (1986-1995) 0.80 Average (2006-2015) 0.22 Average (1966-1975) -0.22 Average (1996-2005) -0.35 Average (1976-1985) -0.38 Average (1950-1959) -0.65 Average (1956-1965) -0.75 Comment: Less pronounced HP in long-term average, again 1986-1995 as extreme LP decade, but also 2006-15 as mainly LP. April: Average (1950-2015) 0.12 Average (2006-2015) 0.57 Average (1966-1975) 0.09 Average (1976-1985) 0.07 Average (1956-1965) 0.06 Average (1986-1995) 0.04 Average (1996-2005) -0.02 Average (1950-1959) -0.11 Comment: April is the month of the whole year with overall lowest air pressure in the Arctic region. 2006-15 saw stronger LP values than any other decade, but not as strong as 1986-95 for the months of January and March. May: Average (1950-2015) 0.01 Average (2006-2015) 0.20 Average (1996-2005) 0.15 Average (1956-1965) 0.09 Average (1986-1995) 0.09 Average (1966-1975) 0.06 Average (1976-1985) -0.16 Average (1950-1959) -0.38 Comment: A month on the balance, but again with 2006-15 with more pronounced LP areas than in other decades. This month had very small deviations between decades. June: Average (1950-2015) -0.01 Average (1966-1975) 0.14 Average (1986-1995) 0.11 Average (1976-1985) 0.07 Average (1996-2005) 0.01 Average (1956-1965) -0.09 Average (2006-2015) -0.20 Average (1950-1959) -0.30 Comment: Another month on the balance with 1966-75 having stronger LP areas than other decades and 1950-59 having the most pronounced clear skies. July: Average (1950-2015) -0.13 Average (1966-1975) -0.01 Average (1986-1995) -0.04 Average (1996-2005) -0.04 Average (1950-1959) -0.08 Average (1976-1985) -0.17 Average (1956-1965) -0.32 Average (2006-2015) -0.36 Comment: After April (mainly LP areas) and May and June in neutral positions, July typically is dominated by HP areas, where 2006-2015 had the highest value, closely followed by 1956-65. August: Average (1950-2015) -0.14 Average (1986-1995) 0.13 Average (1996-2005) -0.03 Average (1976-1985) -0.04 Average (2006-2015) -0.20 Average (1966-1975) -0.23 Average (1950-1959) -0.26 Average (1956-1965) -0.50 Comment: August on average is similar to July and saw 1986-95 as the only decade dominated by LP areas (as also seen for many other months). 2006-15 is right in the middle near the long-term average. September: Average (1950-2015) -0.02 Average (2006-2015) 0.17 Average (1986-1995) 0.00 Average (1996-2005) -0.02 Average (1966-1975) -0.04 Average (1976-1985) -0.06 Average (1950-1959) -0.10 Average (1956-1965) -0.19 Comment: A month on the balance as seen for May and June also. 2006-15 had the strongest LP areas of any decade. While all of the decades are very close together, maybe this is the indicator showing the increased moisture flux? If so, the signal is not strong compared to deviations seen for other decades in other months. October: Average (1950-2015) 0.00 Average (1956-1965) 0.34 Average (1986-1995) 0.21 Average (1950-1959) 0.20 Average (1966-1975) 0.04 Average (1976-1985) -0.09 Average (1996-2005) -0.18 Average (2006-2015) -0.28 Comment: A fourth month on the balance and interestingly had 1956-65 with strongest LP areas. Also very interesting is that 2006-15 saw the strongest HP areas/clear skies, which seems to fully contradict the argument from the article about increased cloud cover in autumn months.. November: Average (1950-2015) -0.10 Average (1986-1995) 0.40 Average (2006-2015) 0.34 Average (1976-1985) -0.03 Average (1966-1975) -0.08 Average (1996-2005) -0.20 Average (1956-1965) -0.66 Average (1950-1959) -0.67 Comment: November turns back trending toward clear skies, but with strong deviations between decades. 1986-95 reappears with strong LP areas followed by 2006-15. December: Average (1950-2015) -0.19 Average (1986-1995) 0.37 Average (2006-2015) 0.01 Average (1966-1975) -0.11 Average (1950-1959) -0.20 Average (1976-1985) -0.36 Average (1956-1965) -0.49 Average (1996-2005) -0.53 Comment: Winter is approaching, so December has slightly stronger HP areas in the long-term average. 1986-95 again showing strong LP areas with 2006-15 on the balance. All Months: Average (1950-2015) -0.12 Average (1986-1995) 0.25 Average (2006-2015) -0.01 Average (1996-2005) -0.12 Average (1966-1975) -0.15 Average (1976-1985) -0.24 Average (1950-1959) -0.31 Average (1956-1965) -0.36 Comment: For all calendar months the long-term average shows a tendency towards HP areas, where 1986-95 deviates most significantly with overall strong LP areas and cloud cover. 2006-15 is seen as overall on the balance between negative and positive values. Overall, it seems like atmospheric patterns and multi-decadal oscillations are the main forces to consider, when determining the chance of cloud cover or clear skies in the Arctic. The decline in the Arctic sea ice area and extent cannot explain why the decade of 1986-95 had such strong and persistent periods of low pressure across the Arctic region. Secondly, it would seem to be clear that beyond the short-term significant impact of clear skies and cloud cover on the ice (Compare weather in July 2015 to July 2013) that on an annual scale the ice will fare better, when the atmospheric patterns and oscillations provide high pressure areas across the Arctic region and that the longer term trend in the AO index therefore will either assist in reducing the Arctic sea ice cover or keep the ice with us a bit longer..
Toggle Commented Aug 18, 2015 on A wetter and warmer Arctic at Arctic Sea Ice
And this is what a study by Colombia, NOAA, and the NASA Goddard Center concluded after thorough analysis of the 2011-14 California drought: "The current drought, though extreme, is not outside the range of California hydro-climate variability and similar events have occurred before. Although there has been a drying trend in California since the late 1970s, when considering the full observational record since 1895, there is no appreciable trend to either wetter or drier California winters." "Our conclusion that the drought was caused by natural variability and not human-induced climate change is in part based on the CMIP5 models, which project wetter conditions in central to northern California in winter but drier conditions in spring." http://cpo.noaa.gov/sites/cpo/MAPP/Task%20Forces/DTF/californiadrought/california_drought_report.pdf And this, finally, will be my last comment on California precipitation, unless of course an entire thread would be opened to discuss rainfalls in this beautiful state..
Toggle Commented Aug 13, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
Remko - you will need to explain yourself a bit further regarding the RRR (And sorry for having a further remark on this Neven!) You said: "Your list contains single years. But if you are looking for a 'Stuck' like the RRR, you will have to finds groups of like years, e.g. 2011 until and including 2015. So: was 1898 just a single very dry year, or was it member of a stretch of 3-5 years that each were (almost) as dry?" And you said: "It [water consumption]does not affect raw precipitation numbers. Climate change is about those raw numbers." So, Remko, please pay very careful attention to the California annual precipitation raw numbers from NOAA: http://www.ncdc.noaa.gov/cag/time-series/us 2010: 10th wettest year, since 1895 2011: 37th driest year, - 2012: Slightly wetter than normal 2013: Driest year on record 2014: 43rd driest year There is no multi-year very dry occurrence here, unless you consider 43rd and 37th rankings 'very dry'. Multi-year droughts in California were primarily 1928-1930, 1946-1949, and 1987-1991, and other groups of years would be in competition also, whereas - in the bigger picture of California climate history - 2013 and the RRR was a one-year event. Thoughts on that?
Toggle Commented Aug 13, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
From the article: "The study found that moisture flux timed to ice melt also correlated with increases in heat-holding cloud cover in late fall and mid-winter, reduced cloud cover over the Beaufort Sea in summer along with earlier onset of seasonal melt and later onset of seasonal refreeze, the study found." It find this item a bit spurious and perhaps a result of analyzing data only for a very short period. Following the argument of the article and the paper, it should follow that after the record melt in the summer of 2012, the late fall of 2012 and winter months 2012/13 should have higher than normal cloud cover, which you can detect in the air pressure level. However, as seen here (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/month_ao_index.shtml), the weather patterns decided to provide mainly high pressure and cloud-free skies in that winter following the record low ice cover, which then allowed ice to rebuild and the summer of 2013 to become a rebound year. Looking at the AO index going back to 1950, it is very difficult to identify a trend that winters are becoming more prone to low pressures and that summers are becoming more prone to high pressures. Overall, it seems like we are moving to a pattern with higher incidence of high pressure across the Artic region (See here: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/JFM_season_ao_index.shtml), which as we know will have opposite impact on the ice, depending on if the high pressure is present during summer or winter months.
Toggle Commented Aug 12, 2015 on A wetter and warmer Arctic at Arctic Sea Ice
Sorry Neven; this will be the last OT comment on California precipitation: Jenny, I have not studied Western US or California precipitation patterns in particular and will recommend you check out data and possibly research projects on NOAAs website. They have excellent searches on the 'Climate at a Glance' page for view and download http://www.ncdc.noaa.gov/cag/time-series/us and they have previously been helpful with providing particular data upon request. Also, I unfortunately had used a graphic which missed December precipitation, which moved a few years around in ranking and also shows 2012 with above average precipitation - regarding that RRR.. wayne and Remko, What is interesting about the AO is that it provides information about the degree to which the Arctic region has cloud cover or not, not the amounts or particular location of high or low pressures. And why is clear skies in the Arctic important (= negative AO index)? Because: Mid-summer weeks: Clear skies increase the temperature and fraction of melt ponds at the center of the high pressure area. Late summer/early fall, the balance will tip and clear skies will cause melt ponds to freeze over and shorten the period, before which sea ice starts rebuilding. Winter-months: Clear skies deepen the Arctic freeze, builds ice quicker and reduces influx of warmer/moist air from mid-latitudes. The AO index is just a reflection of weather patterns and shows just how important the weather patterns are for the Arctic ice, as observers of this blog can testament when comparing the past three melting seasons - especially the period of mid-May to mid-July where clear skies or cloud cover is crucial as factor in explaining what happens to the ice below. Buildup for 2012 - Ideal ice-crushing AO scenario: Very positive AO during 2011-12 winter(Strong low pressure areas during winter months, slowing down ice accumulation) and negative AO during 2012 summer (Clear skies, increased melting) Buildup for the 2013 rebound year - Ideal ice-preserving AO scenario: Negative AO during 2012-13 winter months (Increased ice accumulation) and positive AO during 2013 summer months with the lingering low pressure areas providing cloud cover, keeping temps down and melt pond fractions low). If the AO index would obtain positive and negative values with no pattern or trend at all, then it would be just another weather pattern providing noise in the models. However, that is not the case, as it has shown long-term trends, which NOAA tracks on another excellent page: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/JFM_season_ao_index.shtml If we are indeed moving to a regime of predominantly negative AO index, then the Arctic region will experience longer periods of clear skies, which I speculate could assist in preserving the ice to some degree, based on a hypothesis that clear skies will benefit the ice perhaps eight months of the year and be destructive to the ice for about four months. Pure speculation on these periods though, and I am following the DMI 80N temp and pressure maps closely these days to see, when the coin will flip..
Toggle Commented Aug 3, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
"the great Greenland melt resulting in the cool pool south of Greenland" As a frequent observer of the Greenland ice sheet and DMI SST, I can assure you that the cool pool south of Greenland was present, while the accumulation of the Greenland ice sheet was above normal, which was until the last week of June. I would blame the cool pool on the unusual cold temperatures across Greenland this spring. http://polarportal.dk/en/groenlands-indlandsis/nbsp/isens-overflade/
Toggle Commented Jul 31, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
@Remko, Overall California saw very high precipitation levels in the period of 1904-1916, so something definitely had gotten stuck. If we had been around on this blog it would surely had been labeled the Decade of Drenching - DOD. The drought levels in 2011 and 2012 comparatively were very minor at 10-15% below average and only mattered, because; A. They were followed by the extreme drought of 2013, and B. Water consumption on the US west coast has sky-rocketed. Seriously though, I will have a good look at the papers, thanks, and will probably not have any further response for a while.
Toggle Commented Jul 31, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
On the RRR: If extraordinary weather patterns was a new phenomenon in California, then the RRR would be a great example of the climate being based on new mechanics/principles. However, looking at precipitation history for California including the three wettest and driest years this seems to be unfounded: 1898: 2. driest year 1909: 2. wettest year 1929: 3. driest year 1983: 1. wettest year 1998: 3. wettest year 2013: 1. driest year http://www.weatherwest.com/wp-content/uploads/2013/12/ytd_anom.png When you look at other climate records on NOAA you will also see that deviations from average temperature at a US state-wide level have not increased in the past couple of decades - deviations which are typically caused by ridges getting stuck.. http://www.ncdc.noaa.gov/temp-and-precip/state-temps/ If you can show any reference to research using actual climate records, NOAA, Met-office, etc., indicating that temperature deviations (Cold or hot spells by quarter or year) are getting more frequent or more pronounced, then please share.
Toggle Commented Jul 31, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
Thank you for the update Neven! Regarding the DMI SST images: It appears DMI is having problems with their sensors or how the data is translated, which you will notice in the Bay of Bengal, in a couple of places of the eastern Pacific and possibly in the northern Pacific: http://ocean.dmi.dk/satellite/index.uk.php With these errors it is difficult to tell if the temp indication errors are one-sided, or if hot areas are exaggerated as well. Remko said: ""surrounded by high pressure from all sides" - the circumpolar band about 65 tot 70° N. A completely new phenomenon, I've seen it first during Hurricane Sandy which by it made a unique and devastating track. It's something that didn't occur before.. I have to contend with completely new weather charts exhibiting completely new dynamics." Not quite Remko; please read the excellent blog entry by Neven "On persistent cyclones", where references point out that it is not unusual for a cyclone to persist in the Arctic Basin during the summer period, surrounded by high pressure areas on the northern continents. This phenomenon is caused mainly by the difference in temperature between the cold Arctic Ocean surface temps compared to surrounding continental areas. You also mentioned: "It is part of the 'Stuck Pattern Syndrome', the stall of planetary waves described by e.g. Jennifer Francis, caused by Arctic Amplification." Dr. Jennifer Francis has a peculiar theory, which IMO seems to ignore conventional atmospheric physics. Conventional theory would argue that the pattern and strength of the jet stream is tightly related to the relative strength of high and low pressure in the Arctic region: NSIDC: http://nsidc.org/icelights/2012/02/02/the-arctic-oscillation-winter-storms-and-sea-ice/ J.M.Wallace: http://research.jisao.washington.edu/wallace/ncar_notes/#4Signatures And even Wikipedia (which has the best graphical illustration): https://en.wikipedia.org/wiki/Arctic_oscillation In short, with negative AO we will experience more blocking patterns and a wavier jet stream, while a positive AO (low pressures in the Arctic) will cause the jet stream to strengthen and move further North. Dr. Jennifer Francis argues that the 'waviness' of the jet stream is an indication that it is weakening due to Arctic amplification. When you look at the DJFM AO index (https://en.wikipedia.org/wiki/Arctic_oscillation#/media/File:Arctic_Oscillation.svg) you will note that it was anomalously high (positive) from around 1990, which resulted in a strong, more northerly and less wavy jet stream in general for the past 20 years. However, now the AO index is fluctuating and could possibly be turning to a primarily negative regime for the next 20-30 years, which according to conventional theory would cause the jet stream to weaken, move further south and become more wavy. Therefore, it is correct that the jet stream has become weaker and more wavy since 1990, but in order to have some scientific validity, Dr. Jennifer Francis would need to show that the weakening and waviness of the jet stream could not have been a result of the change in the AO index, and secondly that the current jet stream is weaker and wavier than it was in the 1940s – 1980s, when the AO index also was primarily negative. Personally, I think it will be interesting if we indeed are moving to a more negative AO regime and look forward to see, how that may impact – reduce or accelerate – the warming of the Arctic region.
Toggle Commented Jul 31, 2015 on ASI 2015 update 5: late momentum at Arctic Sea Ice
September extent: 5.4 +/- 0.2 Factors in my consideration: - Still more volume in central Arctic basin compared to last year (Waiting for latest PIOMAS numbers to confirm) - Current extent now a bit higher than 2013 and 2014 However - the unknown factor seems to be the forecast: AO seems to stay medium-negative leading to higher air pressure, less cloud cover. While this should lead to less oceanic heat and moisture reaching the Arctic, it will increase in situ melting, which is still significant only a couple of weeks since mid-summer..
Sorry, missed to include the AO JFM trend for reference: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/JFM_season_ao_index.shtml
Hi wayne - yes, it has been a while, probably nearly a year since my last comments. I am researching papers on oscillations and these days I am inclined to consider the AO as the main oscillation impacting the Arctic - and I admit it is not very inventive to pick this one.. ;-) The AO standardized index for January-March shows how the Arctic region during winter months was dominated by high pressures and presumably less humidity and lower temperatures from around 1950 - 1987. Then for 1987 - 2010, winter months had a significantly lower air pressure regime, which should result in more winter-time moisture and higher temperatures = less ice-building potential. From 2010, this has reversed again with a trend towards a winter-time Arctic high pressure regime, which could possibly explain the ice 'recovery' and certainly should explain the winter-time cold spells in the US and North Western Europe that follow a negative AO. I do not see this changing the long-term trend of Arctic ice decline, but is helpful in understanding year-by-year changes. I therefore do not follow why Dr Jennifer Francis isn't investigating the interaction between the AO and the jet stream bulges, as this is a known relationship (https://en.wikipedia.org/wiki/Arctic_oscillation), or at least work scientifically to show that the jet stream is bulging, while the AO is positive (Arctic low pressure/high humidity due to melting and open water), which is what she basically is postulating. I will go back to lurking..
@wayne, It is hard to predict - especially about the future. Check out these recent predictions, which were not made by 'annoying' or 'contrarian' people, but very nice people of scientific reputation, who have promoted these predictions at conferences, senate hearings and many other forums: Professor Wieslaw Maslowski (2007): Ice-free Arctic by 2013 http://www.abc.net.au/am/content/2007/s2117573.htm "A US-based team has told a conference in California that the northern polar waters could be ice-free in summer by 2013." Prof. Waslowski elaborates on that: "So there is a feedback loop that may accelerate this harder (phonetic) in a linear sense. Mainly they're forcing from the atmosphere, forcing from the ocean. The ice will Albedo effect which is simply where you remove ice, you heat, you warm the ocean, which can melt more ice even further, and those kind of feedbacks are actually in place in Arctic right now, which is possibly causing this accelerated melt." Professor Peter Wadhams (2011): Ice-free Arctic by 2015 (http://www.telegraph.co.uk/news/earth/environment/globalwarming/8877491/Arctic-sea-ice-to-melt-by-2015.html) "It is really showing the fall-off in ice volume is so fast that it is going to bring us to zero very quickly. 2015 is a very serious prediction and I think I am pretty much persuaded that that's when it will happen." Professor Wieslaw Maslowski (2013): Ice-free Arctic by 2016 +/- 3 years (http://www.theguardian.com/environment/earth-insight/2013/dec/09/us-navy-arctic-sea-ice-2016-melt) "Given the estimated trend and the volume estimate for October–November of 2007 at less than 9,000 km3, one can project that at this rate it would take only 9 more years or until 2016 ± 3 years to reach a nearly ice-free Arctic Ocean in summer" As we need to assume both professors know their field of science quite well, it seems like they have taken on a political role, trying to influence the political discussion even if this means stretching to the fullest what can be predicted out of the scientific data, they have available. I could have included an equal number of quotes or estimates from the other side of the political spectrum, which are equally ignoring the scientific reality and believe we are having no measureable impact on the environment. This is personally why I am interested in this field; I am skeptic of environmental messages and predictions, as they have a political bias and it is very hard to distinguish the scientific content from that political bias.