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P-maker
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We have now passed the minimum and some important players have passed a sharp corner. Today, it was announced that the World's largest toy producer has decided to end commercial activities with Shell -mainly after a public (6 million people signed up!) manifestation. Read the full story here: http://www.thelocal.dk/20141009/lego-drops-shell-after-greenpeace-campaign
Yolo - ” If the tar sands are fully exploited it's game over. Terry” c.f. http://forum.arctic-sea-ice.net/index.php/topic,861.msg37848.html#msg37848 Dear Terry No it’s not! The tar sands may eventually become our rescue. Think of a scenario, where the Arctic tundra starts to disintegrate in earnest -full scale - across the Northern Hemisphere. Under those circumstances, it would be wonderful to have a close-by reserve of asphalt at hand. Think about a situation, where greenhouse gases (CO2 in a dry disintegration process and CH4 in a wet disintegrating scenario) are threatening our common survival. Having the World’s largest reserve of asphalt readily at hand would soon become a nice and easy way to cover the surface of the melting tundra before complete destruction takes place. To help refreeze the tundra big scale, we would most likely need a cheap white surface dressing to recover albedo losses (due to vanishing snow cover), In this case, we have a small producer of white stripes in Denmark, who may come in handy at one time (see http://www.luxol.dk/index.php?lang=en). It would be outright stupid, if the Canadians chose to convert their tar sands into liquids and pipe them to the Atlantic coast. The market for fossil oil products would most likely be gone by the time they reach the coast, and they would have lost their biggest opportunity to contribute meaningfully to a “soft landing”. Actually, I think the Canadians have a moral obligation to conserve the tar sands for later use to the benefit of the World’s more vulnerable populations. So, with XL keystone decision just around the corner, and with the minimum of intelligence displayed by our Canadian friends, I think I’m still barely within the limits of this thread…
Mark, you seem to be trawling right now. First you were asking about historical facts. Then you were insinuating that solar and magnetic cycles were driving the whole thing. Now you even revert to questioning the details of an event which took place more than 150 years ago. Why not come back to the present. Give us an estimate of the future based om your apparent knowledge – or please address the future consequences of our current misbehaviours – such at the dwindling sea ice. When Viddaloo comes up with a diagrame like this: http://forum.arctic-sea-ice.net/index.php?topic=994.msg36817;topicseen#msg36817 it does not make sense to walk your way. Seventeen years from now, you may also face the brutal reality of your children or grandchildren: No more ice at all! No more seasons to enjoy! No more life to sustain. You should be a shame of yourself!
Mark, you seem to have missed some of the discussions taking place last year. The first remark I would like to refer you to is from early August 2013. Back then I alluded to a specific situation, when moist air masses from the Mexican Gulf and the Eastern Pacific converged and rose over Mexico for an extended period of some weeks. http://neven1.typepad.com/blog/2013/07/second-storm.html?cid=6a0133f03a1e37970b01901e9abeaa970b#comment-6a0133f03a1e37970b01901e9abeaa970b The flow of warm moist air aloft could be followed through the first (now obsolete) link. As described in the text, the stream of moist air took a course from the Caribbean to Denmark, where it led to unseasonably warm and moist weather. The second remark stems from later in August 2013, when an “atmospheric river” ran all the way from the Caribbean to the Barents sea. http://neven1.typepad.com/blog/2013/08/third-storm.html?cid=6a0133f03a1e37970b0192ac890f93970d#comment-6a0133f03a1e37970b0192ac890f93970d On that occasion, I tried to do a rough back-of-the-envelope calculation to illustrate the existence of a single temporary Hadley cell circulation at that time. Please have a look at these events and try to explain how you wish to introduce solar cycles or magnetism in this new reality we seem to be facing.
Jai, I admire your stamina during these difficult times. You showed elegantly ( see http://earth.nullschool.net/#2014/05/12/0300Z/wind/isobaric/850hPa/orthographic=-166.96,64.74,560 ), that from the 12 May 2014 (and throughout most of May and June) advection of massive amounts of latent heat (at 850 hPa) started from the Northern Pacific across the Arctic Ocean all the way to Denmark. You also took the time to show us the accompanying surface video from Buoy 10 (see http://obuoy.datatransport.org/monitor#buoy10/movie ). Apart from the wall to wall cloud cover, I also noticed a continuous supply of ice needles from the sky and constant snow drifting on the ice surface. These signs bear witness that condensation took place aloft and surface temperatures were well below 0 C, as also shown by the DMI 80N+ graph. In another thread, I alluded to the unusual dewfall over Denmark during this same time interval (see http://neven1.typepad.com/blog/2014/09/piomas-september-2014.html?cid=6a0133f03a1e37970b01b8d067e45e970c#comment-6a0133f03a1e37970b01b8d067e45e970c ). Apparently this advection of moisture across the North Pole was the main explanation for many of the phenomena observed this summer. Finally, you came up with a fine link to a new Korean study, which clearly shows that extensive cloud cover in May and June is preserving the ice over the summer. The only critical thing is, that apparently the climate models have not yet been able to pick up this idea...
Neven, since you ask.. There may be another explanation, but it is difficult to stick the arguments together, because some of the diagrams I need to explain are hidden in various threads on the Forum. The main story goes like this (details may come later): One diagram showed that in recent years, the volume loss was most conspicuous in Jun, May and possibly Apr. Losses in Jul, Aug & Sep were pretty linear (boring). At the same time we have not seen any melt ponds in recent years, which to some have been a kind of a mystery. 2013 may have an obvious reason (persistent lows), whereas 2014 may require another explanation. The only way to lose extensive amounts of sea ice without forming melt ponds , is – as far as know – sublimation. Could it be that the atmosphere in spring (after spring equinox) is now warming so rapidly (due to build-up of GHGs), that ice and snow has simply started to sublimate instead of melting?. We have seen the most dramatic cryospheric changes in the NH snow cover in May & Jun (without the usual spring floodings). This development is now paralleled by massive losses of sea ice during the same months (without the melt ponds). Once we cross the summer solstice, the atmosphere in the NH starts cooling and consequently we should see the opposite of sublimation (i.e. condensation) taking place large-scale. I myself have been living mostly in mid-latitude climates, and I have been used to this effect (called dewfall which has been most prominent in Aug and Sep) all my life. Suddenly this year in spring and early summer, I have for the first time experienced substantial dewfall in May, Jun & Jul. I was wondering how this came about, but could not find an immediate explanation. (This change came after a winter season, where I also experienced drizzle in a so far unprecedented manner, but that is another story).. However, after reading the thought-provoking paper on the melt vs sublimation process, I came to realize that this change from melting to sublimation large-scale should also have implications for the dewfall (what goes up – must come down). So if this dewfall-effect is not picked up by models, we will not be able to project when the remaining sea ice will be gone. I do realize that dewfall does not really melt any ice, because the heat energy will stay up in the air, whereas the dew will fall onto the ice or the adjacent ocean area (with a temperature close to 0 deg C). The same issue is with drizzle, which is also a way of removing excess moisture from maritime air masses (leaving the heat energy above the clouds), when these air masses are advected over land areas. So to sum up: As long as we don’t measure dewfall, we will not be able to understand what happened with the sea ice this year.
Toggle Commented Sep 11, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Gents ( and remaining ladies…) Sitting here on the Normandy coast with a cold beer helps to clarify your thoughts and systemize your reflections. Experiences from a long list of field experiments in the Arctic puts some of your remarks above into context. Here are my main views: 1) The potential rapidity of melt is a reflection of the ice formation process 2) The mixed bag of current Arctic sea ice qualities precludes any robust statements about a “poof” this year 3) The future may guide us to a more clever risk management approach Ad 1) The Russians have a wonderful word: “Naled” (pronounced naljot! I believe). It is a type of ice which is formed in the middle of winter, when freshwater breaks to the surface. In Greenland, I have seen this type of ice formed in front of a glacier, when late summer melt water eventually emerged from underneath the front and spread out over a lake already covered with ice. The vertical ice crystals were > 0.5 m long and 2-3 cm across – like a white, clear and crisp version of columnar basalt. During the summer “heat” (0-5 C), these columns would tumble down in front of your eyes. In less the a day half a meter of solid ice may disappear, if the formation process is of this type. Ad 2) As A-team has so vividly demonstrated on the Forum, glacier ice at the bottom of the Jakobshavn Isbræ is a mélange of various sorbet types. It is evident that the crystals in this type of glacier ice consist of all kinds of tiny, agile, flexible and scalable pieces. Above this dynamic zone near the bottom of the glacier, you will find clear, cold, crisp and big ice crystals. I believe that x-ray pictures show these to be 2-3 cm across. Thus when you walk down the glacier, your boots will meet melting ice similar to glass in the beginning and then, when you start walking into sorbet ice, the sound from your boots change immediately. Thus the history of deformation of the ice will also make an imprint on the ice quality. Apparently small and big ice crystals melt at the same rate on the surface, so it is not easy (apart from the sound) to say whether you have crossed the line. Ad 3) As time goes by, we will have to await how the Arctic sea ice is formed in the next few years. Some of it will be based on “flash freezing” – leading to amorphous ice - like when a cold katabatic wind comes off the Greenland ice sheet in the autumn. Some of it may be formed from regular “plate ice”, as we have seen in open ocean situations over the years, and some of it may be of the “Naled”-type, if the Greenland ice sheet delivers freshwater on top of already formed sea ice in the middle of the winter. I think I’ll go to the beach now and see the tides come in. Cheers P
Toggle Commented Aug 5, 2014 on Poof, it's gone at Arctic Sea Ice
Bob If you really wish to go OT, why not try something like this: http://www.aqua.dtu.dk/english/News/2014/05/140514_Bluefin_Tuna_caught_hunting_for_mackerel which tells a story of unprecedented bycatches off the East Coast of Greenland in August 2012. On one hand, the story of global tuna fishing is as depressing as the story of whale hunting and sea ice disappearance. On the other hand, this story also gives us a glimpse of hope, that one day in the not so distant future, the last Atlantic bluefin tuna on this planet will be able to swim across the Arctic Ocean and meet up with the last surviving Pacific bluefin tuna, and - who knows - get together for a fresh start...
Toggle Commented May 31, 2014 on Greenland 2013 in review at Arctic Sea Ice
Jai, I think you are spot on! Since 2004, the Earth has been heated up due to GHG emissions to such an extent, that natural ”heat pumps” were dominating global climate. Both 2004, -5, -6 & possibly 2007 were dominated by tropical cyclones, which were essentially evaporator-dominated heat pumps on a global scale. It was the evaporation of waste amounts of humid air over the Tropical Oceans, that drove these Tropical heat pumps. The end result was a cooling of the Tropical oceans (also known as a decade of La Nina’s or a halt in global warming). Since 2012, the Earth has moved into a condensator-dominated “Chiller”-mode, which is dominated by persistent Arctic cyclones. Condensation in the cold cores of these phenomena takes out energy from the surface of the Arctic Ocean (hence the below normal 80N+ surface temperatures in recent years from DMI) and delivers heat aloft. It is the condensation of the humid air from lower latitudes, which drives the Arctic chillers. A shift of lower latitude high pressure cells may contribute, but essentially it is the chillers driving the process. As long as we have cold ice in the Arctic Ocean (and high pressures with sublimation of snow over the continents) during spring, we will have this chilling effect in operation. At some stage in the future, the chiller will start working before the Arctic marginal seas have cooled down. This means that the evaporation of warm marginal seas water will lead to a late autumn/winter humidity content in the air, which requires more surface cooling than the sea ice can provide. The result will be a perennial ice-free Arctic Ocean.
Toggle Commented May 15, 2014 on PIOMAS May 2014 at Arctic Sea Ice
A new observation-based Nature paper is out: http://www.nature.com/news/climate-science-understand-arctic-methane-variability-1.15196 trying to make the link between melt ponds and methane emissions. It turns out that 2007 had the highest growth rate in atmospheric methane concentrations.
Toggle Commented May 15, 2014 on More on melt ponds at Arctic Sea Ice
Derek, really off topic... On the Forum, Jai Mitchell just posted this link: http://earth.nullschool.net/#2014/05/19/0600Z/wind/surface/level/overlay=mean_sea_level_pressure/equirectangular=-32.05,-40.34,819 Looking at the circulation patterns in the North and South Atlantic on the 19th May, one could get the impression, that two tropical cyclones are forecasted...
Toggle Commented May 14, 2014 on PIOMAS May 2014 at Arctic Sea Ice
OT to Neven Congratulations – Austria won the Eurovision Song Contest with this song; ”Waking in the rubble…. …. …. And rise like a phoenix Out of the ashes Seeking rather than vengeance Retribution You were warned Once I'm transformed Once I’m reborn You know I will rise like a phoenix But you’re my flame ” “You know who you are - we are unity and we are unstoppable." C.f. http://www.bbc.com/news/entertainment-arts-27360310
Toggle Commented May 11, 2014 on PIOMAS May 2014 at Arctic Sea Ice
Thank you for putting this up so quickly Neven. Please correct a typo (29,900 should be 22,900). Cheers P
Toggle Commented May 8, 2014 on PIOMAS May 2014 at Arctic Sea Ice
Neven Nice to know that you have the eastern part of your roof top reserved for solar panels to provide a hot morning shower for you and your famlily. In case you seek inspiration as to what you can do for your local community, here is a fresh example of up-scaling: http://www.whogreen.com/Dronninglund-Solar-City-Heat/ and the video: https://www.youtube.com/watch?v=8o5nAMGkbaw It’s the World’s largest of its kind: 36,000 sq m of solar panels and a heat pond containing 63,000 cu m of 90 C water. This plant will provide appr. 50 % of all heating needed in the nearby town of Dronninglund. The plant manager, Johan Frey is planning to visit Berlin and Austria in the near future to tell the full story…
Toggle Commented May 5, 2014 on Getting ready at Arctic Sea Ice
Excuse me! With all due respect, your suggestions are highly misleading our young novellist. The most likely course for an object left on the North Pole around AD 1800 would be the following: Two trips around the Arctic Ocean with the sea ice in the Beaufort Gyre – roughly 5 years in total (+/- a couple of years). Exit one autumn day through the Fram Strait with the MYI also known locally as “Storis”. Drifting south along East Greenland for half a year and then drifting north on the west coast of Greenland for another six months – 1 year in total. Ice floe may eventually end up in the Disko Bay area, where it is: 1) either eaten by a whale for breakfast (highly unlikely), or it may 2) be washed up on top of an iceberg from the Jakobshavn glacier following a major calving event Sitting on top of the giant Iceberg, it will slowly cross the Baffin Bay and start its journey southwards along the east coast of Canada. 2-3 years later it will appear off New Foundland on top of a piece of black ice. In the dense fog during the summer night, it will not be noticed by a Basque cod fisherman and the object will be caught up in the wooden wreckage of his boat. This driftwood will then be taken across the Atlantic ocean by winds and currents, eventually reaching the Barents Sea a couple of years later. The object will be frozen into the pack ice north of Svalbard and slowly drift towards the North Pole. So the object will most likely be back at the North Pole some 12 years after it had started its journey… After doing 18 rounds like this since AD 1800, the object is most likely on its way to melt out just north of Novaja Zemlja later this summer, where it will be washed ashore as a symbol of the recklessness of leaving unidentified objects on the North Pole ;o)
Toggle Commented Apr 7, 2014 on Research for a novel at Arctic Sea Ice
Chris, I told you, it would be difficult to find each other in a dark tunnel... However, I was referring to your diagram #5 with the label: "Summer Jet Record Wet after 2007 - GPH.png". Hope this helps. I will need more time to dig into Francis et al. (2009) and other links you provide.
Chris, Coming from either end of a black tunnel and try to meet in the middle, may still be a bit difficult. I will however give it a try. As I read Jennifer’s hypothesis, she claims that the gradient between the tropics (highest GPH) and the Arctic (lowest GPH) at the top of the dense troposphere (~250-300 hPa) is now less steep than in the old days, because the Arctic has warmed more than the tropics. Hence the Jet Stream is slower now and the phase speed of the Rossby waves has gone down and the meanders (horizontally) are wider now. So far so good. You then try to introduce the Coriolis force, which – to my knowledge - has not changed in recent years. It will presumably affect all the stream flows I mentioned. Could we please leave this apparent force aside for a moment as an explanatory factor. I hope we can agree, that gravity is driving all the flows I mentioned? I agree that the Coriolis Force is influencing the meandering pattern, but hope you also agree, that inertia is not driving the process we are discussing? I really like your diagrams at: https://drive.google.com/folderview?id=0B3pB-kdzoLU3WkloQVg1Z09uNUE&usp=sharing – the 1st one clearly illustrates the spiraling pattern of the Jet Stream. Presumably it is driven by evaporation over the warmer parts of the Atlantic and the Pacific oceans, then circles the NH once before it fiddles out over the Arctic. Either the moisture in the Jet Stream precipitates out or the flow descends to a lower pressure level. Maybe somewhat similar to the Colorado River, which runs out of moisture before it hits the Pacific Ocean. Your 5th diagram clearly shows the changing “atmospheric topography” through which the Jet Stream has been flowing in recent wet UK summers – that means the Jet Stream has been running east on the southern side of the Greenland high and then straight into the “valley” over the UK and then all the way up to the Russian rim of the Arctic Ocean. I think this leaves open the possibility, that advection aloft via the Jet Stream may both explain the recent wet summers in the UK as well as the vanishing sea ice to some extent. On re-reading Francis & Vavrus, 2012: (http://marine.rutgers.edu/~francis/pres/Francis_Vavrus_2012GL051000_pub.pdf ), I could not help noticing in Fig 4, that over the past 15 years, the 500 hPa troughs over the western Atlantic (during Summer) and the eastern US (during Autumn) have become more narrow. This is an indication, that the jet stream waves have become more compressed. It will be interesting to see, whether the shortening of the Jet Stream wave length is now also taking place during the winter months. If this is the case, we may have found an explanation for your very wet Winter weather this year.
SH (Scott?) Fascinating read at the LDEO site you referred me to: http://www.ldeo.columbia.edu/res/div/ocp/drought/medieval.shtml I took note of the very thorough analysis of past mega-droughts you presented. It stroke me that, in the years of those Medieval mega-droughts in your place (~AD 936, 1021-51, 1130-70, 1240-65, 1360-82), we had Nordic people living comfortably in southern Greenland and no multi-year sea ice off the east coast of Greenland. On the other hand, we have often wondered, why our Viking ancestors took their long boats south in those years, raping, plundering and drinking their way through Paris, Rome and Cairo. If your hypothesis is right, and if the summer weather was miserable in Scandinavia (and the British Isles for that matter), no wonder they fled south. Chris, I will come back to your response in the morning. Cheers P
Part 2 Again, according to my old textbook, meanders in rivers deposit material on the convex bar and erosion takes place on the concave bank. By analogy this would mean that the Jet Stream would deposit energy over the Pacific Hot Spot and “erode” Arctic air masses over the Bering Sea. Similarly over the Atlantic: High SSTs are being reinforced south of the UK and Arctic air is being “eroded” north of Scandinavia, as we see with the dwindling sea ice around Svalbard. Apparently, the Polar Jet Stream above 250 hPa has been stronger this winter, whereas the Jet Stream below this level has been weaker. This weakening of the Jet Stream may be an extension of the general weakening of the observed Hadley Cell circulation since May/June last year. In the absence of a strong weather-forming Jet, I will again postulate, that basic climatology takes over. This includes the important influence of topographical barriers, such as the Rocky Mountains, which Jennifer also mentions. Acknowledging that the Rockies is a solid topographical barrier to the lower parts of the Jet Stream, it has been fascinating to see the persistence of the ridge and through pattern over the North Pacific/American continent these past 18 months. Various Jet Stream “films” exposed on the ASI blog show, that the wavelength is shortened (waves are compressed) and the waves get “stuck” on the western side of the Rockies, whereas the wave patterns on the eastern side have been more variable over the course of the past year and a half. As the atmosphere picks up moisture from the warmer Tropical and Subtropical oceans, this high “load” in combination with a weaker Jet Stream may have helped to maintain a “stuck and convoluted meander” west of the Rockies. The jet bends south over North America and helps to pull down Arctic air for months on end as we have seen. When the dry and cold air mass leaves the continent, the turbulent air picks up moisture again from the warm Gulf Stream and new storm systems intensify, as they cross the Atlantic and hammer into the British Isles. Previously, I have alluded to the “lack of weather” under the “new normal”. Similarly, it may now be the case, that the Rockies have come to play a more dominant role because the traditional strong temperature gradient between the Tropics and the Arctic has diminished – eventually leading to a more permanently weaker Jet Stream. It is also quite likely, that this “stuck pattern” has now finally been demolished by the onset of early spring in the Northern Hemisphere. Now the warming has started in the Tropics and Subtropics in earnest, and the temperature difference relative to the Arctic has just about exceeded the threshold for a viable Hadley Cell. Come March/April and - if the temperature gradient again goes below the threshold - we are back to “the new normal”. If Kevin and Jennifer could agree on a common indicator (such as duration of Jet Stream flow with sinuosity > 1.5) it would be extremely interesting to see whether this indicator shows an increasing trend over the past 15 years. On the other hand, if Kevin could “tweak” his model to include atmospheric water vapor as a driving force behind a more meandering Jet Stream, then the two of them might be able to resolve the issue, and we would have more reliable climate models.
Chris, Thanks for sharing your thoughts with us. As I read through your wise reflections, I also had a chance to listen to the podcast with Jennifer and Kevin sorting out the giant Jet Stream issue. Earlier this Boreal winter, the “stuck meander” over the North Pacific/North American continent did spur the discussions in another thread. More recently, the “stuck meander” over the UK has been the key issue. I took the time to re-read my old textbook on the subject of meanders to look for an analogy, which may help to explain the phenomenon. Meanders are – according to Gregory & Walling, 1973: 247-257 – a common feature of many natural systems. A number of factors influence the wave length of these features – including the amount of material transported in the stream. When the amount of material in the stream increases, the wavelengths get shorter and the meanders get wider. A few examples serve to illustrate the huge natural variability of these phenomena: 1) meanders on glacier surfaces transport melted ice (H2O) (see http://onlinelibrary.wiley.com/doi/10.1002/jgrf.20135/abstract ), 2) meanders on the surface of karst landscapes transport dissolved CaCO3, 3) meanders in ocean currents transport dissolved sea salt (NaCl), 4) meanders in tidal streams transport flocculated clay minerals, 5) meanders in river valleys transport bottom load and suspended sediments 6) meanders in “atmospheric rivers” transport mainly evaporated H2O. By analogy it is inferred that an increase in atmospheric water vapor content due to anthropogenic global warming should lead to shorter wavelengths, or - if you wish - larger meanders. Hence the hypothesis put forward by Jennifer (http://thinkprogress.org/climate/2013/04/16/1867371/video-explains-how-loss-of-arctic-ice-weakens-jet-stream-amplifies-extreme-weather/) could be tested using a simple measure of the wave length of the Jet Stream meanders (e.g. duration of flow with sinuosity > 1.5). If the wavelength has been systematically shortened over the past few decades, this should not necessarily indicate, that the temperature difference between the Tropics and the Arctic has decreased. Alternatively, a link from a wavier Jet Stream to increased evaporation from tropical and subtropical oceans areas may be substantiated. End of part 1.
Chris, You have several times stated your conviction, that recent wet summers in the UK are due to loss of Arctic sea ice. I was just wondering, whether this paper is on your “to do” list, when it comes to reading during the weekend: http://www.ametsoc.org/2012extremeeventsclimate.pdf see Tett et al. p. 532-535 in particular. Simon is a distinguished professor at the university of Edinburgh, and a former top scientist at the UK Hadley Centre. He has so far not been able to reproduce a connection between wet UK summers this century and dwindling sea ice in the Arctic. Apparently, either his model experiment is flawed or your assumptions are wrong. I would appreciate, if you could comment on this discrepancy at your convenience.
In the old days, the most popular navy song in those tracts went like this: “Rule Britannia!, Britannia rule the waves…” According to Armitage (2000) "Rule, Britannia'" was the most lasting expression of the conception of Britain and the British Empire that emerged in the 1730s, "predicated on a mixture of adulterated mercantilism, nationalistic anxiety and libertarian fervour". Nowadays, with 44 feet waves pounding her coastlines, with tidal waves running up her estuaries and with flood waves washing down her river valleys, I think the lyrics must go more like this: “.. Britannia ruled by waves!”
Toggle Commented Feb 14, 2014 on Looking for winter weirdness 2014 at Arctic Sea Ice
John Please have a look at the Barrow Web Cam: http://seaice.alaska.edu/gi/observatories/barrow_webcam and the Healy Web Cam: http://icefloe.net/Aloftcon_Photos/index.php?album=2013 and the North Pool Web Cam: http://psc.apl.washington.edu/northpole/NPEO2013/18.jpg and the Canadian Met Service analysis: http://weather.gc.ca/data/analysis/935_100.gif and the DMI NE Greenland satellite imagery: http://ocean.dmi.dk/arctic/images/MODIS/NEW/201308141358.jpg and the ECMWF 240h forecast: http://www.wetterzentrale.de/topkarten/fsecmeur.html and tell me once more that all of this is the result of a negative feedback. You’d better put the kettle on for that cup of coffee you promised me a while ago. My bike is pumped and ready to roll! Cheers P
Toggle Commented Aug 14, 2013 on Third storm at Arctic Sea Ice
The third Persistent Arctic Cyclone (PAC-C Aug13) died off a couple of days ago. It lasted six days – peaked below 980 hPa - and fulfilled the general criteria suggested earlier ahead of “PAC-B Jul13” (see http://neven1.typepad.com/blog/2013/07/the-naming-of-arctic-cyclones.html ) . A few questions were raised during this event, e.g. whether this was a real “storm”?. In Denmark we use the term “snowstorm” when at least 10 cm of snow falls within 6 hours and wind speeds exceed 10 m/s. Similar criteria are used in lowland parts of Sweden and Germany. New evidence from a recent GRL paper ( http://onlinelibrary.wiley.com/doi/10.1002/grl.50517/pdf ) point to the fact, that even moderate winds (8-12 m/s) have a significant impact on the heat transfer from ocean to ice. Measurements taken north of Svalbard last year on a 0.8 m thick ice floe documented that - during windy conditions (similar to conditions this year during PAC-B & -C) - the heat flux from the ocean increased to near 70 W/m2. Others have asked about the energy source for this storm. Advection of moist air from much lower latitudes (as alluded to here: http://neven1.typepad.com/blog/2013/07/second-storm.html?cid=6a0133f03a1e37970b01901e9abeaa970b#comment-6a0133f03a1e37970b01901e9abeaa970b ) may be one of the sources, leading to condensation and snow fall over the ice pack. A rough back-of-the-envelope calculation gave a record low (since 1948) SST gradient from the Caribbean to the Barents Sea of roughly 17 K (30-13 deg C) during the storm. The distance is roughly 11,000 km, which means that the average gradient is around 0.0015 K/km. This number happens to be in the same ballpark as the Equator to Pole temperature gradient applied by W. Langford (see the second diagram in slide 25 in his presentation: http://www.fields.utoronto.ca/programs/scientific/10-11/biomathstat/Langford_W.pdf ). It is a disturbing fact that such a low temperature gradient may have led to direct advection of moist air all the way from the Caribbean to the Barents Sea at the same time as the low was churning in the Arctic. If NH single cell configuration and persistent Arctic cyclones is one and the same thing, we may indeed be closer to the tipping point, than we thought. The lasting impact from this particular cyclone remains to be seen, as the clouds disappear later in the melting season. Recent photos from some of the buoys show up to 15 cm of fresh snow on the remaining ice floes, which may affect both albedo and insulation of the sea ice. Do I have to mention, that a new deep Arctic cyclone has appeared in the far end of the current weather forecasts…
Toggle Commented Aug 14, 2013 on Third storm at Arctic Sea Ice
OLN, allow me to suggest PAC-C "Cyclops" Aug13 as an appropriate name in line with previous suggestions for PAC-A "Avatar" and PAC-B "Bush". More on the Cyclops can be found here: http://en.wikipedia.org/wiki/Cyclops Cheers P