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wayne

interesting discussion about albedo, however sea ice absorbs sunlight @75 North altitude when the sun is 3 degrees above the horizon. Perhaps the models need some tweaking.

wayne

75 degrees north latitude of course

Bill Fothergill

On albedo and incidence angles...

Those interested in the subject might care to look at this article from the Journal of Geophysical Research...
http://onlinelibrary.wiley.com/doi/10.1029/2009JF001444/pdf

In particular, have a decko at Fig 9b on page 8 (of 15).

A little care is required over the terminology. When I was doing light physics at school, and in 1st year Uni -it might have been during the Cretaceous, or possibly earlier - angles were always taken relative to a line at right angles to the plane of interest. (Otherwise known as the normal.)

However, when dealing with the sun, there can be confusion. The Solar Zenith Angle is indeed measured from the normal, but the Solar Elevation Angle is, as the name suggests, the angle measured from the horizon.

When the sun is low in the sky - low Elevation Angle, high Zenith Angle - it can indeed glint in a dazzling fashion off water, or ice, or tarmac. Similarly, if one is flying over the Pacific near the equator at lunchtime, one can also see a great dazzling orb reflected off the water.

One of the things people forget when talking about low sun glinting off, say, water, is that there is also a direct path from the sun to the back of one's eyeball.

The suggestion that this kind of stuff is unknown to scientists is simply embarrassing.

iceman

@Neven "Plenty of snap potential, but first all of this 'heat' (it's temperature anomaly, so still plenty cold, just not megacold) needs to get out of the way, and by the time it does, it'll probably be too late for a snap:"

This will be entertaining to watch. A week from now the extent gains in Barentsz and Baffin/Newfoundland will be trailing off or reversing. Looks like not much contribution from Okhotsk by then. Meanwhile an extent drop in Kara from melting and compaction. Will Kara refreeze before the newly-formed thin ice melts elsewhere?

iceman

edit: gains in Bering not Barentsz

VaughnA

The suggestion that this kind of stuff is unknown to scientists is simply embarrassing."

Bill, spot on.

I am also waiting for Cincinnatus to publish a longer list than I of valid and reliable studies that provide good evidence that climate change is a matter of natural variation and that human activities have nothing to do with it.....haven't seen a longer list than mine from anyone in fact. (See my post in "Thinner and Thinner" about my list.)

Neven

A larger jump today of 48K is reported by JAXA. The snap has begun. 246K left to go.

Bill Fothergill

@ Nev

Yep, we are seeing some synchronised swimming from JAXA and NSIDC. As you and many others know, JAXA reports on a 2-day average basis, so their recent massive rebounds match well with the 111k sq km rise in the NSIDC daily numbers seen over the last 3 days.

By the time NSIDC posts the data for 13th March, we will start to see if their 5-day Charctic figures are showing any significant upward motion.

cheers bill f

Neven

The forecast has changed again, with cold and northerlies all around now! I'm not so sure any longer that the preliminary max from Feb 15th is safe. Things could get tight.

iceman

Interesting that this year will have either the earliest extent maximum or (perhaps) the latest. It's an extreme instance of a sinusoidal characteristic that OSweetMrMath pointed out on ASIF: the function is flattish near its maximum, which makes the timing hard to predict.

wayne

these latest are sea ice shoreline gains, not quite unexpected, the SST's where there is the greatest potential extent advances are simply too warm. Baffin Bay is the one to watch because it was quite cold over the winter and I suspect a lag in its descent in extent. The Cold Temperature North Pole is weakening over Hudson Strait and a new one is showing over Alaska, this changes the configuration of the Jet stream substantially. The huge Atlantic Arctic vortex heat engine is finally fading. Check out the very warm temperatures much throughout Midwestern North America, the cold air is vanishing fast in the South.

Neven

The increase has come to a (temporary) halt, as JAXA reports a small drop of 9498 km2. So that's another day gone by and 256K left to go.

Man, this is so exciting. ;-)

Al Rodger

I reckon that unless there is some big big reason to think otherwise, two more days of SIE faffing about with no sign of a rise and I would call 15th Feb as the maximum. JAXA gives the latest SIE (13th March) as more than 250,000 sq km below 15th Feb and there are no years on the JAXA record that have gained/regained that amount of SIE from this date on. All bar 2003 managed less than 150,000 and by 15th March 2003, the gain/regain was below 200,000 and dropping by the day.
In fact, I would give it just one day and call it tomorrow.
(Of course the last time I made a sea ice announcement, the big trend stalled the very next day.)

Neven

Hi Al, good to read you.

JAXA gives the latest SIE (13th March) as more than 250,000 sq km below 15th Feb and there are no years on the JAXA record that have gained/regained that amount of SIE from this date on. All bar 2003 managed less than 150,000 and by 15th March 2003, the gain/regain was below 200,000 and dropping by the day.

Yes, but on the other hand, no years on the JAXA record have been as low as now, meaning there's a lot more re-freezing potential.

I've seen some things in the forecast for Wednesday and Thursday that I'd like to see play out before calling the max. Which of course I won't do. ;-)

Neven

Another 24 hours gone, and yet again JAXA reports a minimal drop of 129 km2.

It will now take a real shocker to startle the crows. :-)

Al Rodger

Well, I threatened to do it so I shall. The comment that there is less ice so more open sea in line of fire (or frost) is greater which could allow a bigger rise - that is true. But it hasn't been evident within the JAXA numbers. 2003 is the biggest post-13th March rise in JAXA but there was over a million sq km more ice back then.
I did a quick check at the NSIDC ch Arctic page and, guess what, over the same period the biggest post-13th March increase there was actually just last year, 2014, when 225,000 sq km was added. But to top the NSIDC February figure, 2015 would need 230,000 sq km.
So, bravely, I say we have seen the maximum Arctic daily SIE for 2015 back in February.

It is a safer bet to say that 2015 will see a record daily low. JAXA is presently 440,000 sq km below that daily record and NSIDC 380,000.

All that said, the headline figure is always the highest monthly NSIDC average and it looks pertty certain that will be the February figure of 14.41M sq km, the previous record being 14.43M sq km in March 2006. For March 2015 to exceed the Feb 2015 average, the average for the rest of March would have to be 14.50M sq km to the end of the month, that is 200,000 sq km above the latest figure, from tomorrow and right to March 31st. I don't see that happening.

Bill Fothergill

Since about the 8th of March, I've thought that the NSIDC monthly record low for March (2006) could possibly be under threat.

As AL has indicated above, that is now starting to look like a distinct probability. The NSIDC daily for the 13th has been revised downward, and the value shown for the 14th isn't doing much to bump the average upwards. All 5 daily values constituting the rolling 5 day figure on Charctic are now within 33k sq kms of each other, so there are no "cheap" gains to be made over the next few days.

The Charctic value for the 14th stands at 14.321 million sq kms, a value that 2006 effectively reached on the 24th. Unless something significant happens very, very soon, 2015 will definitely end up with the lowest NSIDC March average seen thus far.

Not only that, unless there is some significant upward movement, 2015 is also going to start April with a pretty low extent.

wayne

take it this way, this years max is old news before it becomes news.
But it is good to wait for an official pronouncement.

The best thing to do while we wait is to differentiate 2013-14 with 2014-15. After all last year's ice was about the same extent when it went the other way. There is likely less sea ice thickness than March 2014. Does it make sense that less sea ice extent is coupled with greater average thickness?

Kevin O'Neill

Wayne - "Does it make sense that less sea ice extent is coupled with greater average thickness?"

Intuitively, no. But there are confounding factors - especially transport. Which year saw more and older ice pushed out the Fram and Nares?

wayne

Kevin, I would tend to believe less movement during the summer of 2013. But more loss of sea ice in the North Atlantic sector during the same period. But 2014 summer melt had greater open water in Arctic ocean Gyre area , the traditional place where pack ice is thickest.

Jim Hunt

Kevin/Wayne,

I currently find myself taking issues of export and the like from the PIOMAS thread on here over to the forum:

http://forum.arctic-sea-ice.net/index.php/topic,1149.msg47797.html#msg47797

Al Rodger

So having heard me call the minimum as that back in February, the Jaxa SIE stops its faffing about and puts on 69k over two days. Still 186k to go before my bravery turns into foolhardiness.

I might have been less brave given a bit of anslysis I was prompted to do by an enquiry elsewhere. The later timing of the SIE maximum can be made to look a bit illusory, lots of noise on an underlying trend that can appear very small.
For instance, the NSIDC climatology maximum for 1981-2010 gives a timing very close to the average JAXA timing for 2003-2014.
But it occurred to me that the NSIDC monthly data allows a comparison of the average ice in February and the average ice in March all the way back to 1979. And that shows quite a strong trend, but only since the mid 1990s = 24k/yr +/-10k (2sd). When I have a few moments, I double-check that result and try to convert it into a shift of timing in the maximum.
What does stand out is that average Feb SIE had not exceeded average March SIE since the mid 1990s. But that looks mighty likely this year.

Philip

the Cryosphere today SIA has not changed much for about a week. Getting less and less likely that there will be a big freeze.

http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html

from day 65 13,008040 to day 73 13,001980.

Neven

the Jaxa SIE stops its faffing about and puts on 69k over two days.

Indeed, and the forecast is for more cold and northerlies in the Bering AND the Barentsz. I'm going to try and write an update later today.

Werther

The excitement over the yearly max is just a detail within the bigger story. I've come to see 'winter power' as important.
These small samples of NCEP/NCAR show -4-+4 dC temp anomaly on 1000Mb. Period 1/10 to 15/03, winters 12-13, 13-14, 14-15.

 photo Winter Power small_zpspsbxltjp.jpg

Make your own judgement. I'll get back to this later, but look at the difference in the Barentsz-Kara and Baffin regions.

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