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John Christensen
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"All models including ECMWF are indicative of the storm lasting well into next month..." I do not see that: ECMWF medium-range has the cyclone significantly weakened by Wednesday next week and by Saturday the minimum SLP is above 1000mb: http://www.ecmwf.int/en/forecasts/charts/medium/ensemble-mean-and-spread-four-standard-parameters?time=2016082500,0,2016082500&parameter=MSLP&area=NorthernHemisphere I wouldn't be concerned about a forecast going beyond nine days, but a week from now we will know if there is potential for another cyclone to develop.
Toggle Commented 2 days ago on 2016 Arctic cyclone, update 3 at Arctic Sea Ice
Ominous: The DMI forecast of sea ice drift seems to confirm the ecmwf forecast, which has worsened since yesterday: http://ocean.dmi.dk/anim/index.uk.php With the cyclone displacing itself towards Barents/Kara, winds will be strong from the north through Fram and ice drift in a southerly direction is certainly picking up. Perfect mix for late season ice volume drop..
Toggle Commented 2 days ago on 2016 Arctic cyclone, update 3 at Arctic Sea Ice
Final blow? From ecmwf it seems like the cyclone will provide a final blow this weekend and then become disorganized with overall higher SLP across the CAB developing next week.
Toggle Commented 2 days ago on 2016 Arctic cyclone, update 3 at Arctic Sea Ice
Hi Rob, I will get back to you on the note above, but also wanted to share this article from 2010 by Ogi and Yamazaki, where the statistic correlation between summer AO (NAM in this paper) and Sept SIE is discussed. It also addresses long-term trends in the AO index: https://www.researchgate.net/publication/44444524_Trends_in_the_Summer_Northern_Annular_Mode_and_Arctic_Sea_Ice
Toggle Commented 2 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
A couple of months ago I tested this hypothesis and added it somewhere on this blog: What if positive AO (increased cloudiness) during Oct-Dec and negative AO (clear skies) during Apr-June would make enough impact on solar radiation on surface temperatures to have any impact on summer Arctic sea ice melting? Sorted with highest number (most cloudy in late fall and most clear skies in late spring) to lowest, this is how the latest 10 years came out (Note that I only had April and May 2016 available for this, so assumed June '16 would be neutral): Year Fall/spring AO influence 2012 1,67 2016 1,42 2014 0,95 2008 0,81 2009 0,53 2007 0,30 2006 -1,07 2010 -1,10 2015 -1,22 2013 -1,58 2011 -1,62 Since this list placed 2012 1st, 2016 2nd, and 2013 second last, I would say the AO has some predictive skill, although it is just one factor to consider.
Toggle Commented 3 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Agreed, as I have mentioned a number of times, the positive impact of June/July 2016 has been no match for the negative impact accumulated since last fall. Whether the negative impact of the current late summer cyclones will fully negate the positive impact from June/July is still to be seen, but may be on the balance.
Toggle Commented 3 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Agreed that the forecast looks ominous Cato: On the DMI forecasting model you see how a larger area of thick ice is entering Fram: http://ocean.dmi.dk/anim/index.uk.php
Toggle Commented 3 days ago on 2016 Arctic cyclone, update 3 at Arctic Sea Ice
Hi Rob - you are very welcome! Ogi and Rigor had a great paper on this from 2013: https://www.researchgate.net/publication/258757950_Trends_in_Arctic_sea_ice_and_the_role_of_atmospheric_circulation They suggest a primarily cyclonic pattern from 1979-1996 and then anticyclonic from 1996-2010, and you will find in this paper specific wintertime wind patterns to look for, which could be helpful for your model. Wintertime AO does show trends at decadal level, but does not fully follow the periods mentioned above, so I am checking if there could be a difference between AO and the NAM (Northern hemisphere Annual Mode) to explain this. Wintertime AO index from NOAA: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/JFM_season_ao_index.shtml
Toggle Commented 3 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Hi viddaloo, You said: "choosing only 2 months for determining 'Ice Gain' versus 'Ice Loss' seems a bit like cherrypicking." Now, remember what I wanted to check was: "The atmospheric pattern of this summer fits that described for a typical ice gain year" Therefore, I was not trying to assess the entire year, but just the statement above, and then it makes very good sense selecting data for the summer months.
Toggle Commented 3 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
At least I share that obsession with the scientific community.. ;-)
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Well, I guess you can put me in that boat together with the NSIDC, the PIOMAS team at the University of Washington, and others posting on this subject in the Journal of Geophysical Research - I really do not mind.
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Well wayne, I really think it is OK to use PIOMAS as a source for a reasoned argument, and most reasoned contributors on this blog seem to share that idea, given the monthly updates and consequent discussions. You can also dismiss papers from the NSIDC and other research labs in a broad sweep, it just does not bring you much credibility.
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
To assess the impact of atmospheric pattern changes on ice melting, I prefer looking at ice volume, and if you look at June-July PIOMAS numbers(Roughly day 150-210), then you will see that the melting in 2015 was 12,718KM3, while in 2016 it was just 11,996KM3 in the same period, although by June 1st we thought we were going to see a continuation of the rapid extent and volume decline achieved during spring.
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Hi viddaloo, Sorry, I should have elaborated; all of my comments above have been around the conditions (E.g. snow cover, sea ice, preceding winter atmospheric pattern, etc.) and how these have shaped the atmospheric pattern of this summer. The atmospheric pattern of this summer fits that described for a typical ice gain year, as decribed by Screen et al, but that is far from saying we will have more ice than a year ago. That will not happen as we were already about 1,000KM3 short by the beginning of the month, and we should be further behind 2015 volume by Sept. 1 due to the current cyclones. If you read the articles - or Neven's excellent blog entry 'On Persistent Cyclones' - you will see that cyclones tend to preserve sea ice, when they occur in June/July, but that there is no preserving effect for late season cyclones. And this is what we are all looking at, as it is rare to have a large cyclone roaming the CAB this late in August.
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
If anyone did not notice yet, 2016 is not an outlier, as we had predominantly positive AO index during the preceding winter, which then according to literature should increase the probability of positive AO during summer also, resulting in more cyclones. On the other hand, 2007, 2012, and 2013 were all outliers: 2007 and 2012 were preceded by positive AO during winter, so in principle should have had cyclonic weather during summer, but this did not happen, so those years had both unfavorable winter and summer seasons, resulting in immense sea ice reductions. 2013 was just as exceptional in the sense that the preceding winter was dominated by negative AO (=increased snow cover, lower temps), but still was followed by strong cyclones in the summer of 2013, resulting in unexpected gain in ice volume from a year-over-year perspective.
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
And finally, Screen et al also reconfirm the atmospheric patterns associated with ILYs and IGYs: "In the ILYs, a high pressure center is located in the Beaufort Sea and pressures above 1014 hPa are found over most of the Arctic Ocean. The wind is predominantly anticyclonic with a local closed circulation in the Beaufort Sea and a larger jetlike circulation from the Chukchi Sea toward the Barents Sea. By contrast in the IGYs, the Beaufort Sea high pressure center is much weaker and smaller, and there is low pressure centered over the central Arctic Ocean but extending to much of the basin. The wind is predominantly cyclonic around a midpoint in the central Arctic Ocean." I would say this summer fits the typical IGY quite well.
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Screen et al (2011) also observe: "In addition to the fewer cyclones in the central Arctic during ILYs [Ice Loss Years], the most striking difference between the cyclone trajectories in ILYs and IGYs is the almost complete absence of cyclones tracking from the North Atlantic, the Greenland, Norwegian and Barents Seas, and northern Eurasia into the central Arctic during ILYs. During IGYs [Ice Gain Years], a substantial number of cyclones form in these regions, migrate poleward and reach the central Arctic Ocean."
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
2) If 1) is true, then did these cyclones "help preserve the sea ice" as you assert ? Yes, see Screen et al 2011 (Dramatic interannual changes of perennial Arctic sea ice linked to abnormal summer storm activity), from the abstract, as referred by Neven back in 2013 in 'On Persistent Cyclones': "Strong relationships are revealed between the September sea ice changes and the number of cyclones in the preceding late spring and early summer. In particular, fewer cyclones over the central Arctic Ocean during the months of May, June, and July appear to favor a low sea ice area at the end of the melt season. Years with large losses of sea ice are characterized by abnormal cyclone distributions and tracks: they lack the normal maximum in cyclone activity over the central Arctic Ocean, and cyclones that track from Eurasia into the central Arctic are largely absent. Fewer storms are associated with above‐average mean sea level pressure, strengthened anticyclonic winds, an intensification of the transpolar drift stream, and reduced cloud cover, all of which favor ice melt. It is also shown that a strengthening of the central Arctic cyclone maximum helps preserve the ice cover, although the association is weaker than that between low cyclone activity and reduced sea ice. The results suggest that changes in cyclone occurrence during late spring and early summer have preconditioning effects on the sea ice cover and exert a strong influence on the amount of sea ice that survives the melt season."
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Hi Rob, Thank you, and I suspect these arguments to be valid. Here is what Serreze and Barrett found: 1) Is there any evidence that cyclones in summer became more common when ice extent (or land snow cover) was low ? Yes, indeed, as has been found by Serreze, Ogi et al, and others. Ogi et al (The summertime annular mode in the Northern Hemisphere and its linkage to the winter mode, 2004) said: "The wintertime NAM/AO is linked to the summer atmospheric circulation. Summer atmospheric anomalies are similar to the summer NAM. The winter NAM and subsequent summer NAM have significant lagged correlations. The link between the winter NAM and the summer NAM can be interpreted as a preferred transition from one mode in winter to a similar mode in summer. For example, a winter circulation in a positive phase of the winter NAM is likely to be followed by a summer circulation in a positive phase of the summer NAM. Similarly, negative phase will likely follow negative phase. The continuation of the same phase in summer is possibly facilitated by springtime boundary conditions such as snow cover, as suggested by Ogi et al. [2003a, 2003b]. When the polarity of the winter NAO/AO is positive, spring-summer snow cover over the Arctic coasts of Eurasia and North America is reduced, which in turn enhances the meridional thermal contrast between the colder Arctic Ocean and the surrounding warmer continents. The larger thermal contrast could favor a positive polarity of the summer NAM by triggering enhanced eddy activity along the Arctic frontal zone [Serreze et al., 2001]."
Toggle Commented 4 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
Much appreciated, thank you Bill! In addition, your number is for the full NH SIA and not just the Arctic Ocean SIA, where the anomaly should be somewhat less, since e.g. Hudson and the other most southerly seas do not apply. Therefore, with the significantly reduced snow cover, as argued by Serreze and Barrett, the conditions for developing the barocline have improved. All of that being said, I am just saying that we are still using the same framework to understand what is happening: The NH temperature increases would explain why the cyclonic weather pattern appear to have strengthened, and why cyclones could possibly endure longer towards the end of August, compared to the 'old normal'.
Toggle Commented 5 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
So the ice extent is down 10% from 12 years ago. However, the NH snow cover has been in top-4 negative anomaly since February 2016, with a June negative anomaly of 3.8MKM2 - roughly four times as much as the sea ice anomaly. This has brought the snow less land areas of June 2016 much closer to the Arctic Ocean, supporting the barocline. If you want to refute that you can calculate the respective albedo values.
Toggle Commented 5 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
"in summer there is a whole lot less of sea ice" Exactly how much has the sea ice area of mid-June of the Arctic Ocean dropped in the past decade - 'a whole lot'??
Toggle Commented 5 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
wayne, Not sure this time is well spent, but OK: "What High Albedo with lesser sea ice extent?" OK, let's just focus on this for now. So this is the albedo difference between the Arctic Ocean and snow-free land by mid-June, when the barocline developed. As you very well know the ice extent by that time - in the Arctic Ocean - has not changed much since 2007. We did have the opening in Beaufort, but that's it. You still have a very significant blanket of ice during summer solstice with a high albedo compared to neighboring snow free land areas. Are you saying that the early opening in the Beaufort should disrupt the overall albedo of the entire ice pack in the Arctic Ocean, where Beaufort is very marginally placed, or what are you really saying??
Toggle Commented 5 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
wayne, You may chose to ignore science, which is fine with me. I will not comment on this any further.
Toggle Commented 5 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice
And to the question, whether Arctic summer cyclones assist in advecting loads of warm and humid air onto the sea ice, the SB article notes: "The coastal baroclinicity is sharpest over northeastern Siberia and north of Alaska, where topography appears to help “trap” the cold Arctic Ocean air." That the barocline is strongest in these two areas in the summer months should now be obvious due to the significant size of land areas in relative limited distance from much colder water/ice surfaces.
Toggle Commented 5 days ago on 2016 Arctic cyclone, update 2 at Arctic Sea Ice