[snow hope]

Well my time of 1544 - 3:44 pm was close! Pity I was out by 5 days though. ;)

[ldavidcooke]

Hey All;

I decided to jump in and offer my best guess of 19 April 2008 at about 1600 hours or 4 PM locally.

Dave

[admin]

Blimey - How time flies, didn't realise it had come round again! 29th April at 3.30pm

[ldavidcooke]

Hey All,

It looks like Dave Clarke may be on to something, the 2007 and 1999 ice thicknesses look similar to this year and the dates ranged from 27 to 29 April. I definitely missed my guess as the river has not even gotten any open water at this time and the ice core still appears to exceed 40 inches. Amazing seeing how the Arctic Ice had a record melt last year and one of the warmest NH winters last year and yet the Global Warming has had little impact on this event. One would have expected last year to run around the same as 1993 and yet it was nearly four weeks later. Now this year looks to be even later then last and yet the ice was of similar thickness.

Dave Cooke

[snow hope]

28th April 1500

[StratoQ]

Another year gone by. Last year it was 6th May 10:53 (did anyone pick May?!) Any takers for this year?

http://www.nenanaakiceclassic.com/Ice%20Conditions.html

I'll go 2nd May 13:30

[ldavidcooke]

Hey All,

Well this year the ice thickness looks similar to 2003 and 1996 and winter weather. 2007 though the ice thickness was similar there was abnormally high insolation. Where as in 2003 there were a spat of higher day time temperatures. Even so, it would seem that the range should be between 29 Apr and 5 May. If we were to take the median I think StratoQ is pretty close. On the other hand we have the character of the river below and with the warming of the past decade it appears there is a double peak to the current distribution. The former long term median appears to be centered around 7 May, where the current median appears to be centered around 29 April. As this appears to be more of a normal winter in this zone , I think I will split the difference and suggest a median of around 3 May.

This then would suggest for a ice thickness target in the 5 May range in the pre-GW grouping, with the center median of around 3 May suggesting a 2 day swing on either side of the side. The question is should the value for this year be closer to the former 7 May peak or the modern 29 April peak. If I were expecting a drastic increase in temperatures and sunlight in the region I would select the low side, similar to StraoQ. However, the forecast appears cloudy and day time temps below 50 F, with night time temps below 28 F for the next nine days. If the cloudiness remains, I am going long on this one.

My estimate will be my anniversary, corrected for the local time difference of -4 hours, this leaves me with 5 May at 0630.

Cheers!
Dave Cooke

[StratoQ]

Yes Dave, the ice thickness is still quite healthy as we fast approach May. Looking back at previous years both 2003 and 1994 had decent coatings well into April and yet break-up occurred before May. So it seems it all can change quite suddenly.

 

[StratoQ]

Looks like the end may soon be nigh. Recent update:

The last ice measurement we took was on April 23 the ice was 42.7 inches thick. There will be no more ice measurements this year due to the ice conditions. There is water on top of the ice on the banks of the Tanana River. There are no open holes yet on the Tanana River.

The Nenana River went out late Saturday afternoon, and the water flow is cutting into the Tanana River ice. The Nenana River runs into the Tanana River about 1/2 downstream from where the Tripod is standing on the Tanana River.

The ice on the Tanana River generally breaks up about 2 weeks to 10 days after the Nenana River goes out.

The 5 day forecast for the week of April 27th is daytime temperatures between 60 and 70 degrees and between 38 and 41 degrees in the evenings. If temperatures reach 70 and stay warm we will start seeing more action with ice melt and the ice could go out as early as this coming weekend.

 

[ldavidcooke]

Hey All,

Well, it looks like all bets here are off. Seems that the 10 day window of the lower river going out and the tripod falling over was compressed to 7 days.

http://www.nenanaaki...Conditions.html

Thanks to StratoQ for hosting this years activities. Hope to see everyone playing next year.

Cheers!
Dave Cooke

[StratoQ]

Thanks Dave.

It does seem a notoriously difficult thing to predict. You think over 42" of ice not so long ago would prove somewhat resilient - but I suppose there are many factors at play - not to mention the wide temp fluctuations.

 

[ldavidcooke]

Hey All;

Here we go another year and another opportunity... This year the ice thickness appears most similar to 1989, 1997, and 1999. Of these we have two values in the teens of April and one in the 20's.

I will be trying a bit different approach this year and abandon wishful thinking. My off the top priliminary est. of the last measurable day will be in the 14 Apr to 21 Apr range with the actual ice breakup to follow 7 days rather then the traditional 10 days later. I will firm this up this evening.

Cheers!
Dave

[ldavidcooke]

Hey All,

Well what do you know, the river actually held out till the 4th of May at 4:24pm local. This places the event clearly in the center of the old pattern.

What with the slamming of extremes here below the 40th parallel, north of here they have been having cooler then the normal conditions of the last decade. Yet, above the 50th parallel they are worried as the ice coverage is falling off very fast. (Amazing, simply amazing, I can appreciate the hand of a supreme power in all of this...)

Cheers!
Dave

[StratoQ]

Yes Dave. This graphic of Northern Hemisphere April temp anomalies shows a big contrast between the very warm Eurasia and cold Canada/Greenland.

 

 

[ldavidcooke]

Hey Niall,

Notice that the center of the colder temps over N.A. happen to be identical to the location of the much higher then normal temperatures seen last Summer/Fall. Does this suggest that the pole has shifted, or that the weather center of circulation has shifted?

Given the recent NASA observation that most of the Arctic warmth can be attributed to the convective transport of Equatorial/Temperate warmth at mid-levels in the atmosphere, likely due to radiative capping by GHGs. I am still curious if this is true, as in any case the N. Jet Stream should have receded towards the perimeter of the Arctic Circle during the depth of Winter. Instead the variation of the path has continued the seasonal transitional aberration at up to an additional 35 Deg. South (down to 25 Deg. N), normally only seen around the time period of the Spring and Autumnal Equinoxes.

This certainly raises the question of what are the drivers or defines the pattern of the Jet Streams (both Polar and ITCZ). Looking at your image it would appear that the center of circulation shifted and the Eur-Asian warmth was unprecedented. The question is what could have shifted the atmospheric flow from a latitudnal/zonal to a longitudnal/hemispheric? Convection cannot explain this shift nor can changes in atmospheric radiative cooling.

This appears to be a atmospheric wobble in the extreme, almost like you would expect of a tidal locked planet (See: http://en.wikipedia....i/Tidal_locking ) to appear. As the rotation and tilt of the Earth has changed very little over the last 100 years, it appears that this change has it's origin in something that science has yet to unveil. I suspect that it has to do with the difference between land heating and ocean heating; however, I have nothing to support this hypothesis.

Cheers!
Dave

[StratoQ]

Some scientists believe it may be attributable to actual arctic sea ice loss.

Dr. James Overland of NOAA Pacific Marine Environmental Laboratory (PMEL) recently noted a link between low sea ice and a weak polar vortex in 2005, 2008, and the past two winters, all years with very low September sea ice extent. Earlier work by Jennifer Francis of Rutgers University and colleagues also suggested a relationship between autumn sea ice levels and mid-latitude winter conditions. Judah Cohen, at Atmospheric and Environmental Research, Inc., and his colleagues propose another idea—a potential relationship between early snowfall in northern Siberia, a negative phase of the Arctic Oscillation, and more extreme winters elsewhere in the Northern Hemisphere.

The trend over here (for some time) has been for a significant decline in December mean temperatures. Nov and Jan may be going that way too whereas most other months are warming. Whatever the reason there appears to be a distinct lack of westerlies in recent times and far more meridional flows.  

[ldavidcooke]

Hey Niall,

The weird thing this year in addition to the odd warm/cool conditions the Winter 2010-11 N. Polar vortex was one of the strongest in 3 decades. This vortex strength was noted as the cause for the most severe decline in Stratospheric Ozone in the last 2 decades...

Cheers!
Dave

[ldavidcooke]

Hey Niall,

I suspect Dr. Overland's observations to be a symptom and not a cause. Advect a lot of "hot air" towards the poles and the cyclonic should grow unless it is occurring at a mid to high level in the atmosphere then as it cools it acts as a high level anti-cyclonic. I venture to guess the Stratospheric Ozone diminishing could be related as well.

Reduced sea ice and ocean transported insolation/salinity add to the poleward heat flow, enhancing the atmospherics when in-phase (Neg AO/strongly Neg NAO), take them out of phase and we have a more normal or Positive AO with a more Positive NAO. At issue is the reduction in Neutral occurrances of decadal oscillation.

Looking at the two equally potent systems that formed would seem characteristic of the decadal AO with a split flow one (warm/cyclonic) centered over the EurAsian landmass the other (cold/anti-cyclonic) over and fed by the oceans, centered over N.A.

The recent NASA study seems to support the idea of blocking conditions adding to the warmth feeding the poles via storm transported heat flow. The issue as I see it is determining the processes involved and the function that the N. and S. Northern Hemisphere Jet Streams play in either distributing or concentrating the hemispheric heat flow.

Cheers!
Dave

[ldavidcooke]

Hey Niall,

After re-reading my last post I can see where it maybe confusing, let me try to put things into perspective:

1. Ever year, regardless, there will be ice loss. The amount has two main effects, one the increase or delay in the on-set of the winter anti-cyclonic and a stable/eliptical N. Jet Stream.

2. As the Summer cyclonic diminishes in the Western Artic the Eastern anti-cyclonic advances from Siberia and becomes predominate. Putting the AO in a more Positive pattern. As long as the Western Surface Low diminishes then we see what we generally think of as a normal pattern.

However, under unusual Blocking conditions the Western Surface Low does not form and the normal moist heat flow rather then encircling the Arctic Circle actually gets wrapped around the Siberian High.

This then begs the question what spawned the Blocking condition? Was it diminished Arctic Ice; No, if that were the case we would never have had complete Arctic Sea ice coverage.

Was the Blocking condition the result of excessive Equatorial Heat being capped by AGW or GHGs: This appears more likely as the warm pulse would have displaced the Arctic cold pushing it East and South. This explains the cooler then normal Eastern Arctic and both the early and cooler then normal N.A. 2010-11 Winter. The problem with this line of reasoning is why. Why, after 20 years of CO2 exceeding 380ppm and higher equatorial advection in the recent past, did the current Blocking condition dominate?

Many may want to suggest Sunspots others may want to suggest a change in the ENSO/Southern Hemisphere patterns. There is no support for these suggestions in the public data sets.

So why now and why so much energy concentration...? Ozone?; Unlikely, Methane?; Unlikely Most everything at this time points to volconic/smoke aerosols and increases in cloud cover changes. So if we venture into this region, albedo changes, is this likely the dominate Blocking driver?: Unlikely; I suspect it will probabily prove out to be many and possibly all the above which causes the Blocking condition. This then begs a follow up as to why these events are occurring at their extremes and at a similar point in time.

Cheers!
Dave

[StratoQ]

Dave, like you, I do find the synoptic changes of recent years intriguing/perplexing/confusing and it is a real "human" condition to try and go and search for a "best" explanation. In you last post you muse over many of the climate forcing agents. But why try and narrow it down to one culprit at this juncture?  I would agree most with your last comment - many causes. 

It gets even more difficult when you try and make sense of it on a global basis. So, hope you dont mind me focussing on what has been happening over here in NW Europe. I've been looking at the mean temp stats for my area, comparing the first decade of the 21st century with 1961-1990 data. As with the CET figures, they show that December has bucked the warming trend (spectacularily so, last December). It is worth noting that the jan to jul mean range is approx 5C to 16 C. Small compared to the US, so a decadal departure of >1C is kind of a big deal here. Have you any similar type figures for your area?

The December anomaly I find of particular interest. From memory, back in the 70/80's,  I can recall many stormy, mild Decembers (especially in the first 2 to 3 weeks), driven along by a very active jet. Comparing the satellite ice extent images of say 1979 with last year, shows by Dec 1st the ice edge was far more advanced then along eastern Greenland/Barents and Kara Seas. I cant help but be drawn to a belief that the  slow autumnal progression of ice extent at the fringes of the north Atlantic/Arctic is producing many complex effects. Not just albedo (given that it is late autumn - this may not be all that significant compared to high summer) but SST's, elevated arctic surface temps, thermohaline circulation, Arctic Ocean open water increasing early snowfall. How do these land/sea changes then impact on the atmosphere - and in particular the northern jet vs northern anticyclonic block?

Of course we also have the CO2, GHG's, Ozone, aerosols,volcanic dust, TSI changes going on, but say taking Svalbard as a particular location, have the changes in these climate forcing agents (from 1979-2011) had as much an impact on their particular climate as the ice decline has?

As we said earlier - many causes! Here is the mean temp data breakdown by month for my area: