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Messages - Michael Hauber

Pages: 1 ... 15 16 [17]
801
Consequences / Re: 2014 El Nino?
« on: July 04, 2014, 09:25:13 AM »
Most ENSO events peak around January, so if it forms late it is likely to be weak.  One exception was 86/87/88 which was weak in the first year but in the second year instead of collapsing it continued to build.

I've also noticed that many ENSO events tend to build in the 2nd and 4th quarters of the year.  The first quarter is when the last ENSO event dies, and often there is a pause roughly in the 3rd quarter until the ENSO event has another late burst for a Dec or Jan peak.

802
Arctic sea ice / Re: What the Buoys are telling
« on: July 04, 2014, 04:35:20 AM »
Dry Adiabatic lapse rate from 850hp to surface would be about 12 degrees warming.  Models show 850hp temps near the pole at near 0, and a generally high pressure = descending air mass.  So temps near the surface at 10 degrees aren't unreasonable.  The actual surface of the ice must be 0 degrees or lower until the ice is all melted and that is what the satellites and models would probably pick up.  Not sure how fast the temperature can rise as you move away from the ice, but air is a good insulator, so if its still perhaps 10 degrees by the top of the bouy or wherever the thermometer is is possible?

Then consider solar heating of the shield around the thermometer.  For the normal situation of measuring temp over grass there is lots of solar heating of the grass anyway (thats why the air for the first few 10s of metres above the surface gets hot) so solar heating of a white box around the thermometer is probably not an issue.  Over ice the solar energy goes into melting instead of heating, so heating of the enclosure might be more of an issue even for a nice white well ventillated box.  But of course if solar heating is inflating the temp of the thermometer in the bouy this reflects increased melting of the ice.  The important thing would be making sure the measurement is consistent over time and between bouys. 

803
Consequences / Re: 2014 El Nino?
« on: July 03, 2014, 04:33:54 AM »
More like a westerly wind burst has produced a cyclone, which according to the models will head north and take the westerlies away from the equator.

804
Consequences / Re: 2014 El Nino?
« on: July 03, 2014, 12:32:00 AM »


The current forecast shows a further burst of trade winds over the top of the existing upwelling Kelvin Wave, and cool water already lurking underneath the surface in the central Pacific.  If this forecast eventuates I think we will see an abrupt transition from positive to negative nino 3.4, and game over for this El Nino.

Can it go so far as a transition to La Nina?  The recent drop in ocean heat content is unprecedented (since 1980, so not a huge period of time, and not much negative PDO which may or may not matter), and usually occurs during the transition from moderate or strong El Nino to La Nina.  And usually early in the year.  If we fail to see an El Nino eventuate this will be the strongest spike in warm water that has not resulted in an El Nino by about 50% (next strongest is 2008).

805
Arctic sea ice / Re: The 2014 Melting Season
« on: July 02, 2014, 11:35:08 PM »
The models seem pretty consistent on introducing some semi-persistent trough/low pressure activity around Laptev/Kara area.  This will push winds and warmth into the Laptev and there is probably enough open water there for some wave action as well. 

Perhaps what has been missing the last few weeks is some low pressure around the edge of the Arctic to get winds blowing into the Arctic instead of lazily circling a big high pressure in the middle.

Will the current rapid rates of extent drop in IJIS climb even further?  Although Hudson/Baffin are pretty much near their ends now.

806
2.75-3.00

The weather seems a bit coolish, and lack of surface melt.  But how we could fail to beat a year like 2008 with 6 years of warming and the large areas of open water in Chukchi/Beaufort/Laptev?

807
Arctic sea ice / Re: The 2014 Melting Season
« on: July 02, 2014, 01:33:31 AM »
Curious how the warm tongue from Canada in the 925 HP just stops dead when it hits the Beaufort.  SLP suggests the winds should be carrying this air mass into the Arctic.

808
Arctic sea ice / Re: The 2014 Melting Season
« on: July 01, 2014, 06:20:12 AM »

This year volume will be at least roughly tied with 2010.


If volume is only as low as 2010 that would be an interesting result.  A quadratic trend up to 2012 suggested minimum volume reaching 0 around 2016 or so.  The uptick in 2013 put volume right in the upper ranges of expected variation around this trend.  If this trend was to continue I'd expect a new volume record this year.  Something more like 2010 would in my mind confirm that 2013 was the start of a slow down in the death spiral to something more like the Gompertz curve and a postponement of ice free Arctic for at a few years or maybe decades.

809
Arctic sea ice / Re: The 2014 Melting Season
« on: July 01, 2014, 04:51:33 AM »
June is over.  And no June cliff to speak of.  This could mean a serious slow down later in the season if lack of albedo feedback via melt ponds has the impact expected by many.

Why no June cliff?  The start was cold but the last couple weeks have been much warmer and plenty of high pressure for sunshine.  And open water has increased at a rapid rate in the Laptev and to a lesser extent Beaufort and Chukchi as well.  Perhaps the weather has been warm around the edges but cold in the middle.  Perhaps lots of snow in winter is slowing down melt pond formation - and also making for thinner ice due to snow insulation.  Perhaps the sensors are fooled by fog this year.  Or maybe its not warm outside and cold inside, but cold on top and warm underneath.  The ARC SST chart hints at unusually warm water in the Pacific side of the Arctic basin.  If the melt is being driven strongly from underneath we might see a strong melt late in the season after the surface melt finishes.

And July has begun.  Looking at IJIS extent this is the month where the contenders are separated from the pretenders.  Melt in the peripheral regions is complete, and it becomes all about the central regions.  I also suspect that July is the month with the highest input of solar radiation in the Arctic Ocean.  More sunlight comes in during June, but with solistice on the 21st it would not be by a large amount, and I guess the increased open water and surface melt in July would more than make up for this.  Unless cloudier conditions in July block the sun out, which we certainly seem to have seen in some years.

During previous July's 2006, 2010 and 2011 all faded away from commanding positions at the head of the pack.  I sometimes wander how much of the 2010/2011 slow down was due to the bad weather at that time, and how much was due to stronger conditions of the central pack and an end to melt in the peripheral regions.    July saw 2007 made its big move leaving pre-2009 years in the dust and overtaking 2010 and 2011.

However sometimes there are significant moves in August as well with 2013 falling from near the front to well behind, 2008 making a surge from well back to be just pipped at the post by 2007, and 2012 breaking away from a neck and neck race with 2007 to set a significant record. 

810
Arctic sea ice / Re: The 2014 Melting Season
« on: June 29, 2014, 08:59:01 AM »
The wedge of open water from Laptev pointed towards the pole is ominous.  Its also interesting to see the East side shows lots of large floes, and the west seems to be mostly broken up too small to see individual floes.  Perhaps this has formed on the boundary between thicker ice from the ESS tongue and thinner ice initially formed in Laptev during winter and then pushed towards the pole by winds and currents. 

Its quite interesting comparing the position of this open water to other years - at minimum.  The ice edge there is already in about the same place as minimum during 08,09 and 13.

811
Arctic sea ice / Re: The 2014 Melting Season
« on: June 29, 2014, 04:01:41 AM »

If that warmth mixed to the surface well the ice would melt out completely every summer.


To melt out 2 metres of ice would take enough energy to heat the entire atmosphere above by 16 degrees.  Considering we are probably talking maybe 20-30% of the atmosphere that is above 0, and I've almost never seen a temp 16 above 0 then the entire lot could mix with the surface maybe a dozen or more times over during the summer before melting through the ice.  If there is only a partial mix then you could be mixing every 3-4 days for 90 days and still not melt all the ice.

812
Arctic sea ice / Re: The 2014 Melting Season
« on: June 28, 2014, 11:13:34 PM »
GFS and ECMWF both pick up on a big low near Iceland.  Might generate some swells to impact the Atlantic side of the Arctic?  And the east coast of Greenland for sure.  ECMWF has it further south and some of the impact blocked by Iceland, whereas GFS shows it closer.

813
Arctic sea ice / Re: The 2014 Melting Season
« on: June 28, 2014, 12:28:07 PM »

Can you give me examples of how much of an effect it has say 0c 850mb temps versus 10c 850mb temps.  Both full sunshine, same surface pressure.


If the temperature is 10c warmer at 850mb I would bet big dollars it will also be warmer at the surface.  Unless some effect such as cloud shading, or melting/evaporation/albedo changes etc causes a localised cooling or heating at the surface.

A few days ago the high and low pressure around beaufort lined up nicely to see warm air drawn from the north American continent and this was seen in the models with a tongue of 8-12 degree temps at 850 intruding onto the Beaufort.  This resulted in one of the more spectacular transitions I've seen with the Beaufort ice going from solid and white non-melting ice to grey/blue broken up strongly melting ice.  As the winds in this region have weakened and become less southerly the 850 temps have cooled and the melt has reduced (at least according to Jaxa).  Current model runs suggest that in the coming week there will be less intrusion of warm air from outside the Arctic, and it is no surprise that 850 temps are predicted to cool.  I'd expect surface melt on the ice to slow as well reflecting a genuinely cooler air mass - however I'm not sure if a generally slack high pressure dominated pattern may result in less clouds and  more sunshine to keep melt going at the same speed.

I'm also quite surprised that despite the apparently warm Arctic conditions MODIS continues to show significant areas of orange non-surface melt areas in the Arctic - mostly between Greenland/Canadian Archipelago and North Pole.  In 2013 everything not hidden by clouds turned red nearly a week ago, and in 2012 two or three weeks ago.

814
Arctic sea ice / Re: The 2014 Melting Season
« on: June 28, 2014, 01:35:39 AM »
Interesting observation.  I've kind of given up looking closely at Arctic region SSTs because so often it seems that warm SSTs following melt rather than predicting melt.  However I know a pulse of warm water from Pacific was one of the factors associated with the 2007 melt.  Looking at satellite SSTs in the Bering Straight seems to show definitely warmer water than this time 2012, and similar to 2007.  There was quite a lot of warm southerly wind pushing into this area in winter and spring, so maybe this is now starting to have an effect.  Even if the incursion started in the coldest part of the year the Pacific water 100 metres down should be relatively toasty compared to the Arctic waters.

815
Arctic sea ice / Re: The 2014 Melting Season
« on: June 25, 2014, 12:06:10 AM »
Yes, the third factor is weather.

A big factor with 2012 cyclone was the fact that the Siberian ice tongue had almost pinched off a large island of ice just before it started.  The ice here was weak, and close to surrounded by water, so was the perfect target to be wiped out by the storm.

The significance of a strong early Beaufort and Laptev melt is the chance of again pinching off a large island out of the Siberian ice tongue (thicker ice towards Siberia that usually seems hardest to melt last and has been a significant feature at minimum extent in most years except 2007 and 2012).

816
Arctic sea ice / Re: The 2014 Melting Season
« on: June 24, 2014, 11:15:11 PM »
Here is a somewhat subjective assessment of where we stand compared to 2012 according to Wipneus regional graphs for area (first post of Home Brew thread).  I've ordered the regions in a very rough order of my opinion of which ones matter most to the final result.

Central basis:  ??
Laptev Sea:  1-2 weeks ahead.
Beaufort:  Coming from a long way behind to be equal on the day.
Chukchi Sea: 1-2 weeks ahead
East Siberia Sea:  1-2 weeks ahead.
Greenland: 1-2 weeks ahead. (perhaps signifying poor export)
Canadian Archipelago:  1 week ahead.
Barents:  maybe 1 week behind.
Kara Sea:  3-4 weeks behind.
Baffin: near enough equal.
Hudson:  near enough equal.

A question mark for the central basin.  The areas were near enough equal a couple days ago, but an uptick has pushed 2014 up a bit.  And a bit on CAB is a lot more overall as its a big region.  Its also to early for any significant melt, and a lot more of the variation is due to sensor issues with clouds etc.  Its pretty clear from MODIS 3-6-7 that there has been a lot more melt ponding in 2012 than this year.  The two factors in my mind that will control the central basin melt are the melt ponding - clear lead to 2012, and incursion of open water from adjacent regions - where I think it is pretty clear that 2014 has the current lead.

817
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: June 24, 2014, 08:03:28 AM »
On area 2014 has quite quickly caught up to 2012 in Beaufort - but may rise up a bit when the current torch ends.  Still behind there on extent.  The other areas 2014 are behind on 2012 is Kara - big time, and the central Arctic Basin - which is critically important but I'm not sure how reliable the measure is until we see real drops in this area (eg consider 2013 vs 2012).

All other areas 2014 is equal or ahead of 2012.

818
Arctic sea ice / Re: The 2014 Melting Season
« on: June 22, 2014, 12:59:10 PM »

I'm not sure a agree with your assessment that current ice conditions are more favorable than 2013.  That seems like a stretch to me

Amount of surface melt appears to be less than 2013.  But there is much more to 'current ice conditions' than surface melt such as ice thickness etc.  I also think 2014 is 99% likely to have less ice than 2013, because we have more open water in the Arctic basin, and 2013 was overall an extreme outlier (in my view) and there is no sign of a repeat of these conditions this year.

819
Arctic sea ice / Re: The 2014 Melting Season
« on: June 22, 2014, 10:29:43 AM »
Comparing regional areas and extent courtesy of Wipneus  home brew thread, 2014 is ahead of 2012 in Chukchi and Laptev, and behind in Beaufort and in Kara.  Kara is a massive difference accounting for much of 2012's large lead over 2014.  Presumably Kara will melt out and this won't matter much, but that argument was very popular in 2013.  Current conditions seem to be enough for 2014 to maintain its lead in Chukchi and Laptev.  However with a torch currently in effect over the Beaufort 2014 is catching up quite quickly in this area and with the forecast continuing to keep the pressure up in this area could possibly overtake 2012 within a week or so, to be ahead of 2012 in all key regions except Kara.

At the same time a check of 3-6-7 channel on Modis shows large areas of red (=surface melt) but still large areas of orange (no melt).  In contrast 2012 saw nearly all red from early in June, and 2013 showed all visible areas as melt from several days ago.  Personally I think 2013 was better set up for a strong melt at this stage in the season than many give credit for and it poor weather later in the season that played a big part in the low amount of melt by September.

If surface melt ponding is as important as some think, this season could continue to struggle.  This season could be an interesting test for this theory.

820
Arctic sea ice / Re: May melt ponds do not matter
« on: June 19, 2014, 12:33:54 AM »
Melt ponds that form in May might have perhaps twice as much time as those that form in late June to absorb sunlight.  However there are ten times as many melt ponds forming in late June.  And ponds that form in May will be mostly in areas that will melt out well before the end of the melting season.

I've downloaded NSIDC extent data to quickly calculate a standard error (as standard deviation, not sure if that is exactly right) for a forecast based on fitting a linear and quadratic trend.  These are 0.56 for linear and 0.49 for the quadratic.  The standard error for end of May melt pond fraction predictions was 0.5.

821
Consequences / Re: 2014 El Nino?
« on: June 18, 2014, 11:12:18 PM »
Seven day GFS forecast starting to show westerlies near the dateline.

822
Arctic sea ice / Re: May melt ponds do not matter
« on: June 18, 2014, 11:00:07 PM »

It is of course possible that any correlation between early season melt ponding and the minimum is picking up two factors. Albedo pre-conditioning, and the prevalence of FYI across much of the pack (increasing open water formation efficiency). For strong statistical correlations to emerge we really need the post 2007 and post 2010 periods to extent for a few more decades.  ;)

This is stated in the paper.  Melt pond fraction is calculated on a model, and validated against observations were possible, similar to PIOMAS volume.  Running their model they are able to observe that pre-conditioning such as thin and first year ice are very significant.  First year ice melts at a cooler temperature, and thin ice is flatter so a given amount of melt water will spread further.

And of course we should be able to get perfect correlations once the Arctic is ice free :P

823
Arctic sea ice / Re: The 2014 Melting Season
« on: June 18, 2014, 10:55:50 PM »
The algorithms aren't perfect.  Lets say the error is 1% - that would sound pretty good.  Then the error would be about 90k for current area.  Then lets say from one day to the next it changes from a strong negative to strong positive error.  Thats a 180k swing in arctic area - and so daily changes are not particularly reliable.  But comparing an area minimum of say 3.1m one year with 3.5m another year, and an error of 1% means you can make a useful comparison and be quite confident the difference is significant.

824
Arctic sea ice / May melt ponds do not matter
« on: June 18, 2014, 11:41:35 AM »
I refer to recent paper which seems to imply that the September minimum is largely determined by the melt pond fraction in May.  However my analysis is that the strength of the relationship is an effect of overfitting the model, and that in actual fact melt pond fraction in late June is a better indicator of final minimum, and that it is not a significantly better predictor than a simple extrapolation of the long term trend.

First, the correlation between melt pond fraction and September minimum is quite impressive at over 0.8.  Hindcasts made with this method have an average error of 0.33 million km2.

However I've always been suspicious as there is usually almost no melt pond visible from satellite in the central Arctic area until early to mid June.  Figure 1 of the paper reveals that the typical melt pond fraction at the end of may is around 2% at the end of May.  Figure 2 shows that the area of the Arctic for which melt ponds are measured excludes the Hudson Bay and Sea of Okhotsk, but includes much of the Bering Strait, the Baffin bay, Greenland Sea, Barents Sea and Kara see.  At the end of May surely nearly all the melt ponds must be in such fringe areas if the total fraction is only 2%.  How can this determine the fate of the central ice in September? 

A key issue that is not immediately obvious, is the fact that the melt pond fraction is not a straightforward calculation of total melt pond area divided by total ice area.  A geographic weighting is applied with a different rating for each of 1000s of grid squares.  This raised the possibility that the strong correlation is not due to causation, but is due to overfitting the model due to having too many variables available to tweak.  In particular imagine any grid square that has melt ponds in one particular year, but not in any other year.  The weighting for this square can then be tweaked to change the model prediction for that year without affecting the prediction for other years.  Obviously there is a limit to this otherwise the correlation would be perfect instead of good.  But it may cause a stronger correlation than a purely physical causal relationship would otherwise suggest.  I suspect this may explain why there is a better correlation early on in May - there are more opportunities to find grid squares that affect only 1 or a small number of years whereas by July most grid squares would affect many or most years.

One good way to prevent such overfitting is to train the model on data for some of the years, and attempt to use the model to predict the result in other years.  This is done in the paper by making a 'forecast' for each year by using only data for years before that year.  This is effectively what would have been forecast if the method in the paper was used to actually forecast that year when the results for that year (and future years) are not yet available.

The results are much less impressive and suggest that some type of overfitting effect is at play.  The standard error for the end of May melt pond fraction prediction increases from 0.33 to 0.5.  The error for the prediction using melt pond fraction up to June 25 goes from being worse than end of May to being better (0.36 to 0.41).  A prediction error of 0.5 to my eyes looks to be no better than the average error for making a prediction based purely on extrapolating the long term trend, although I'm not motivated enough to try and download the data and perform a calculation to confirm this.

825
Arctic sea ice / Re: The 2014 Melting Season
« on: June 18, 2014, 07:45:48 AM »
Ice in the beaufort is still quite solid, and with most of the wind running parrallel to shore I don't see much scope for significant declines in the short term.  However surface melt is already taking off with a big increase in last 24 hrs shown by latest MODIS and the current conditions will certainly weaken the ice for future stat drops.  The current pattern also tends to push ice and cooler air towards Laptev which is currently the most significant weak point in the central pack.  June cliff about to start?  I thought so a week or so ago and was wrong, but the current pattern looks to be stronger, and with more summer power behind it.

Kara is getting blasted by strong winds and big heat so should see strong declines.  It was all going to melt anyway.  Of most interest to me is what will happen on the Atlantic side of the north pole.  The ice surface hear is still nice and white and cold, but divergence has created a loose floes with plenty of small pieces of open water.  Later in this pattern the high will ridge towards this region and hit it with sunshine, presumably soaking significant amounts of heat into the water between the floes.  Also the wind will be at times very strong with low pressure in the north Atlantic causing a tight gradient.  Much of this wind will be roughly parrallel to the ice edge (but pushing this ice towards Fram), but some of the time it will be towards the ice on a long fetch - so potentially some very large waves.

Also I've had a good hard look at the melt pond in May paper and think I've spotted some serious flaws, but it won't be until later that I'll get my act together and explain why.

826
Arctic sea ice / On this day in history
« on: June 16, 2014, 11:38:18 AM »
Comparing Jaxa views  On 15th June:

2014: Melt ponding visible on ESS fast ice, and in a corner of the Beaufort.
2013: Significantly less open water in Chukchi, Beaufort and Laptev seas.  Some melt ponding from Beaufort through to ESS.
2012: Lots of melt ponding over Pacific side of Arctic basin, less open water Laptev, more Beaufort, and similar in Chukchi.  Much less ice in Kara, although as a fringe region this may have less impact.
2011: Melt ponding noticeable on ESS fast ice only.  Similar amount of open water in Laptev, Beaufort and Chukchi.  Much less ice in Kara
2010: Melt ponding on ESS fast ice, and some in ESS.  Less open water in Laptev and Chukchi, more in the Beaufort.
2009:  Melt ponding visible on ESS fast ice, and corner of Beaufort.  Less open water in Laptev, similar in Chukchi and Beaufort.
2008: Significant melt ponding in Beaufort.  Almost no open water Laptev, similar in Chukchi, major open water in Beaufort.
2007: Suprisingly little melt ponding visible in Jaxa, but massive melt ponding around this day in IUP and CT.  Less open water in Laptev, more in Chukchi, similar in Beaufort.  Dramatic trail of open water behind Wrangel Island as the ice is pushed strongly away from Pacific side towards Greenland.
Early 1980s (from CT):  Usually no open water in Laptev or Beaufort, lower ice years comparable to higher modern years in Chukchi, but generally more ice.  Dramatically more ice in Kara almost always full and Barents sometimes full.  Bafin, Hudson and East of Greenland, roughly similar to modern conditions on casual inspection, but probably more ice if I looked close enough.

827
Arctic sea ice / Re: The 2014 Melting Season
« on: June 16, 2014, 03:14:08 AM »
Forecasts at 5-7 days can be ok - but often wrong in the details even though the large scale set up may be roughly correct.  And it is often the details that matter.  For a local weather watcher its whether a storm system is overhead or a hundred k away.  Or at this time of year whether a heat plume from subtropical Asia makes it 3000k to reach the Arctic, or only 2500k to fall short.

I think the big high in the Beaufort looks very likely, but whether it pulls quite as much heat in as ECMWF thinks it might (much more than GFS latest run) is uncertain and depends on how well it connects with heat being drawn from USA north through Canada.  This will condition the Arctic well for further melt, but at the moment the Beaufort is behind a bit on melt and I think it needs a bit of softening before we see any meaningful extent reduction.  Although I expect we may start to see the June cliff rear its head with some significant melt ponding in this area.  Later in the 7 day forecast A huge and intense tongue of heat off the Eurosian continent approaches the Arctic, and models seem to think only the edge will impact the Kara/Laptev sea.  A little further away and nothing will happen in the Arctic, a little further into the Arctic and the results could be spectacular.  Other than the potential for this heat blast there doesn't look to be a lot of reason to expect significant melt in the currently weak Laptev area.

Seemingly unnoticed on this forum Baffin has been motoring along for a couple weeks, and Hudson is starting to get into gear as well, with well above average loss in both areas according to CT regionals.  Forecasts show continuing strong heat in both areas.  Surprising after the polar vortex winter - but I think Baffin may have missed the worst of the polar vortex.  And it seems that early summer has been hot enough in Hudson that thicker ice there only delayed the faster melt.


828
Arctic sea ice / Re: The 2014 Melting Season
« on: June 14, 2014, 07:15:56 AM »
I tried hunting a few of the references you posted using google scholar, couldn't find some of them (I'd especially like to look at dong et al 2013), and found nothing definitive on the topic.  I did find a paper by Shupe et al in 2004 (link) which does some detailed analysis on this topic and finds that in the Arctic clouds cause cooling except for 'a few weeks in the middle summer' when the sun is strong enough that direct solar radiation is more important.


829
Arctic sea ice / Re: The 2014 Melting Season
« on: June 14, 2014, 06:29:10 AM »
High pressure systems not only let more sunlight in - they cause air to descend which causes warming.  Perhaps we should look more in the mid levels as what I understand is that it is upper level ridging that causes the strongest descending air and worst heat waves.  There does seem to be a strong link between high pressure and increased ice loss in the last few years - but some significant exceptions with GAC 2012 at the top.

Jaxa is showing the first significant sign of surface melting within the Arctic basin (exlcuding ESS area fast ice).  This is later than 2012 and 2007, but about par for other years since 2007.  Interestingly enough I would judge 2013 to have the third most significant surface melting within the Arctic basin as judged by Jaxa for this date.

At the same time significant areas of reduced concentration are appearing all through the Atlantic/European side of the central Arctic basin, similar to what happened in 2013.

830
Was going to vote 4-4.25 but looks like I was too slow.

We are behind 2007 and 2012 in surface melt and general ice quality as best I can judge, but I think we are equal with other years, and definitely ahead of 2013.  Given 2007 was 7 years ago and had the thicker ice pack to deal with I think we should still be in with a good chance of beating 2007.  The Laptev bite is huge and late season should make it a good chance to break down the tongue of ice towards the East Siberian Sea - which has been present in all years other than 2007 and 2012.  If we have a low pressure dominated rest of melting season the rotation will push the open water in the Laptev towards this region.

The weather this year seems to be variable with alternating bouts of good and bad melting weather.  We had the polar vortex move over America in winter, and now with summer in full swing there is hints of the coldest air moving into Atlantic - America was colder in winter, but now with summer the Atlantic will be colder than America, so perhaps there is a reason for this switch.  If the polar vortex wanders into the Atlantic in a similar manner to its winter trips to America the melt season could be given a serious boost.

The current pattern has a series of lows pushing in from Siberia through the center of the Arctic and out to the Atlantic.  Although it brings cooler and cloudier conditions as in 2013, the troughing, and movement of the pressure systems results in more heat being pulled from nearby land masses, and increased export ice into the Atlantic, while still tending to cause diversion and holes in the ice pack.  If the variation in weather follows up with sunshine then instead of the sun warming up a large area of open water to 5 or 10 degrees the heat in the water will quickly have an ice floe travel over it and the energy will melt ice instead.  There has been a lot of movement of ice out into the Barents sea since at least spring, and the divergence between this movement and the transport of ice down the coast of Greenland is probably part of why the Atlantic side of the central Arctic is looking a little raggy.

831
Arctic sea ice / Re: The 2014 Melting Season
« on: May 29, 2014, 01:26:49 AM »
I doubt much will happen in the ESS in the next week or two.  Significant open water generally does not appear until July and it isn't even June yet.  The center of the high pressure is in Beaufort, so the maximum sunshine and warming from sinking air will be elsewhere.  And the winds are mostly parrallel to the shore, so the ice won't be strongly pulled away by wind.

And there is still a huge chunk of fast ice in ESS that will tend to spread out if it melts.

Perhaps a change to forecast could shift the wind direction to pull the ice away, and perhaps it won't be hot enough to break up the fast ice for a little while yet.

832
Arctic sea ice / Re: The 2014 Melting Season
« on: May 28, 2014, 11:56:56 AM »
The models seem consistent enough that we can be fairly confident of seeing some significant high pressure at warm enough temperatures for surface melt for at least a good slice of the next week.

I've done a bit more hunting through Cryosphere Today history, and 2007 and to a lesser extent 2012 stand out as having wide areas of reduced concentration within the pack (and not just near the edge) that I believe is caused by melt ponding.  In 2007 the start is about June 7, and now it looks like we may see the same thing happen even earlier this year.  Whether we see the double whammy of big high pressure and hot atmosphere temps (i.e. yellow to red on the 850 temp or 500 thickness charts) is yet to be seen, but I think big high and mild temps that we look certain to get is dramatic enough.

833
Arctic sea ice / Re: The 2014 Melting Season
« on: May 28, 2014, 12:55:54 AM »
Most of the melt at this time of year is typically on the Atlantic side and the current set up is pushing cooler air and exporting ice towards the Atlantic.  The bad conditions for ice are mostly hitting the Pacific side of the Arctic, and I don't see much potential for signficant reduction in extent yet.  The ice is fairly compact up to the coast still and as it starts to melt it will tend to spread out.  Unless winds are pushing offshore.  I think this factor also affects area as it takes some spreading of the ice pack before any noticeable reduction in concentration is registered.  Also note at some stage the large area of fast ice on the ESS coast will fragment and this will temporarily tend to reduce the open water area that has formed in this region.  The first week of July in 2007 was the earliest I've seen significant open water form within the Arctic basin on the Pacific side.

What I will be closely watching is for the appearance of the 'June Cliff'.  Looking through Cryosphere Today large areas of reduced concentration - presumably melt ponds - started appearing around the Beaufort to ESS from about the 2nd week in 07 and 12.  I would expect that the current set up should produce air temps a little above freezing at ground level, and high insolation, so should be a good to start melt ponding.  Whether its enough to register with the CT sensors I don't know, and it will be interesting to see if the June Cliff can be initiated a week earlier than either 07 or 12.

I've also noticed that Hudson bay is being hit by quite warm temperatures, and has been for a week or so.  The ice is still above average and only a moderate reduction in area so far.  Not sure if thats because of thick ice because of the Arctice vortex taking its walk into N America, or if the Hudson is always hot by this time of year and the current conditions are typical. 

However the polyna at the north side of the Baffin bay area seems to be larger than most recent years despite the presumed effect of the vortex in winter, and no particularly favourable conditions for melt that I've noted so far this spring in that region.   I'm guessing there is warm water there.

834
Consequences / Re: 2014 El Nino?
« on: May 23, 2014, 01:58:02 AM »
Oops, I should have checked instead of relying on memory.  I was out by a year and meant 2005.  There was also some follow up westerly activity during that year, but not enough to keep things going.  The Kelvin wave was in January to March and could be considered the last gasp of the 04/05 event. 

In cases following a previous years El Nino there is much greater chance of a significant upwelling wave due to the Rossby wave effect - the previous years Kelvin waves bounce off South America as slow Rossby waves and often bounce off the south east Asian land masses sometime early in the following year as upwelling Kelvin waves.  I've read various authorative sources stating this as fact, but I've never been able to actually find a west moving Rossby wave in the subsurface data....

835
Consequences / Re: 2014 El Nino?
« on: May 23, 2014, 12:08:38 AM »
I've looked at the 2012 failed El Nino, and also the 2004 case where there was an extreme Kelvin wave around Feb that was looking fairly similar to 97.  In both cases TAO data shows a complete absence of westerly wind activity west of the dateline resulting in the warm water in the east fading out after the last Kelvin wave from the last burst of westerly wind passes through.

836
Arctic sea ice / Re: The 2014 Melting Season
« on: May 22, 2014, 08:06:27 AM »
Actually I think its more like 2012.  The weather kept changing, hinting at massively favourable ice loss patterns, but never getting it fully together.  But ice extent kept dropping at near record rates until the big storm blew the record away.

I've often noticed that a factor in 2007 was the early entry of the melt front from the Pacific.  An early extention of the melt front from the Bering straight area into Beaufort and ESS gave a nice long melt front and allowed faster melting during early July.

Later in the season the attack on the ESS ice tongue is a factor.  In 2009-2011 this tongue held up well and late season melt was slower.  In 2008 and 2012 early incroads from Beaufort and Laptev tended to pinch off the tongue.  In 2008 high rates of melting were achieved late season as the tongue was pinched off and partially melted out, and in 2012 the record was beaten as a good portion of the tongue was completely isolated from the main pack and melted out, effectively giving a second melt front in the Arctic.

Also I noticed today that this is not the earliest date of significant open water in ESS area.  Cryosphere Today shows significant open water earlier than this year in this region, and the result was an extreme melt (by pre-2000 stamdards) of the ESS area by September.

837
Consequences / Re: Global Surface Air Temperatures
« on: May 14, 2014, 12:59:36 AM »
History shows minimal response in global temperatures during Jan-Nov of the first year of an El Nino, and temperatures then jumping up in Dec and more so Jan, and continuing warm through much of first half of the second year. 

Having run through the numbers in some detail for UAH I'd expect 2014 to almost certainly not be a record year, with my current calculated projection at 0.31 and a record of 0.42.  I project 2015 to be around 0.5, and the year will probably be a record, but a weak temperature increase similar to say 2006 could still see the record missed. 

With a quick eyeball on GISS, I notice we are slightly behind the target, and with a small December jump the most likely result I'd guess on a 50/50 chance for this year, and an almost certainty for 2015.

838
I think this is the storm to watch out for.  It is late in the season so water temps are at their warmest, and the ice at its thinnest.  And with the sun about to set, the clouds won't matter.  Of course being late in the season there isn't much time to make a big difference.  But maybe a couple big days might see this year push up the leader board a little.

839
Arctic sea ice / Re: The Cause of the Muted Melt of 2013?
« on: August 21, 2013, 12:16:35 AM »

I think we will find some of our answers in the dynamics of heat transfer with the oceans, and how that part of the system's temperature and chemistry affect current flow and heat transfer with other components of climate.  A specific example of how much this is changing seems to me to be exemplified by how the North Atlantic has come to dominate the Norwegian and Barent's seas, and to a lesser degree the Greenland sea, by way of more energy being swept north in Gulf Stream/North Atlantic Drift.   We might be well served to explore changes in SST and deeper, elsewhere to understand what's happening north of 70 degrees.

It seems reasonable to guess than speeding up the gulf stream may result in increased warm water being pushed from the Atlantic to the Arctic, at the same time as increased surface heat may be transferred to the deep ocean due to bottom water formation in this area.  It is tantalising that by my reckoning the recent slow down in temperatures started in 2007 when temperatures fell unusually rapidly from the El Nino driven peak in Jan 2007 to the La Nina driven low in Jan 2008. 

However I've only ever heard about the gulf stream slowing down.  And there does not appear to be any significant increase in temperature of the North Atlantic since 2007 (eg calculate 2007-2012 anomalies vs 2000-2006 in GISS map viewer).  However since 2007 there has been a significant cooling of waters in areas of the Pacific associated with La Nina/PDO activity - the eastern and central tropics, the far east, and the far north and south, so I suspect that any increase in transfer of heat from the surface to depths of the ocean is happening in the Pacific driven by ENSO.

840
Arctic sea ice / Re: The Cause of the Muted Melt of 2013?
« on: August 20, 2013, 11:38:09 PM »
Quote
With regards the 1981 to 2010 climatology, the influence of 4/30 years will be very small.

When calculating anomalies, sum(1980=>2010) = 0

So considering that sum(1977-->2006) = sum(1977-->1979)+sum(1980-->2010)-sum(2007-->2010)
then sum(1977-->2006) = sum(1977-->1979) - sum(2007-->2010)

And if 2007 to 2010 have a common pattern 1977 to 1979 may cancel each other out to some extent and the 2007 to 2010 term would dominate.

841
Arctic sea ice / Re: The Cause of the Muted Melt of 2013?
« on: August 20, 2013, 07:12:36 AM »
In recent years the ice has been melting faster than models predict.  And the globe has been warming slower than the models predict.  Is it not reasonable that in both cases the variation is temporary and longer term climate behavior will trend closer to the model?  It is quite possible that we will see a 'recovery' of Arctic ice in the future, and possible that this may be starting now.

The correlations posted are interesting.  In particular I note that we did not return to the pre-2007 pattern this year, but rather reversed the 2007-2012 pattern.  The correlation with the 2007-2012 pattern is not near zero, but as strongly negative as it had been positive from 07-12.  And this year continues a mild negative correlation with the pre 2006 pattern.  So perhaps the post 2007 pattern has not ended, but simply flipped into a reverse mode, and so it could easily flip back to the 2007-2012 pattern next year.  Or continue in reverse mode for several more years....

There is an issue with calculating the 1977-2006 pattern is that it is based on an anomaly vs the 1980 to 2010 climo.  This means that if there was an 'average' pattern that the Arctic was in until a switch to a new pattern in 2007 that when 4 years of the new pattern are added then the baseline will look like a weak version of the new pattern.


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