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Messages - Nightvid Cole

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101
Arctic sea ice / Re: IJIS
« on: July 12, 2015, 12:10:58 AM »

Unless we start seeing a number of multi-century drops in the next few weeks, it's going to be hard to set anew record this year.  We may need a "Super GAC-12" in late August to stir up and flush out a massive amount of rubble.

I'm in no way predicting a larger melt in 2015 than what happened in 2012, but it seems like we need to pay a lot of attention to thickness and concentration.  A very large but thin and broken area of ice could disappear very quickly.

I would not be surprised to see some surprises later in July / August.

If you wouldn't be surprised to see it, then is it really a surprise?   :D

102
Greenland and Arctic Circle / Re: Greenland 2015 Melt Season
« on: July 11, 2015, 09:24:31 PM »
Well, NSIDC melt did not go up as I expected. Their map shows high melt in the Northeast part, but not in the southern part. This is a little weird - even the ADS/VISHOP RGB suggests more melt over southern Greenland than that (though less than on July 9th.)

I wonder why these sources seem to be a bit misaligned...

103
Arctic sea ice / Re: IJIS
« on: July 11, 2015, 03:35:54 PM »
IJIS SIE decrease has picked up, but not as much as I thought it would.

Indeed. In fact, extent continues to lag further and further behind many previous years including 2012 and 2014, with the lag growing larger with each passing day. The current extent is 684k higher than that measured in 2012 on the same day; that's the largest gap so far this year between the two seasons, and that's all the more surprising given that just a few short months ago, 2014 had more than a million km2 less ice than did 2012.

One telling statistic: for the last ten years, here are the number of extent century drops recorded over the two-week period just passed:

2006: 4
2007: 9
2008: 0
2009: 6
2010: 2
2011: 7
2012: 8
2013: 13
2014: 8
2015: 3

Obviously century breaks aren't the most accurate statistic around--but the lack of them this summer certainly fills in parts of the overall picture.

Given the amount of ice yet to melt in Hudson and Baffin Bay, and the large regions of low-concentration ice in Chukchi and Beaufort Seas which is unusual for this early in the season, I predict:

1. At some point this month, IJIS extent will experience a dramatic acceleration in its decrease, with many century breaks;

2. By July 31st, IJIS extent should be within the lowest 3; and I would not be surprised if it is the all-time low for July 31st.

Furthermore, I would not be even slightly surprised if the *average* daily decrease between 7/10 and 7/31 is in excess of 100k km^2...

104
DMI puts it in mid-August, while PIOMAS puts it in September! Do we have clues from submarine data or other sources as to which one is right and which is wrong?

105
Arctic sea ice / Re: What the Buoys are telling
« on: July 11, 2015, 01:01:11 AM »
Obuoy9 now definitely looks melting, maybe it needed time to show the effect or maybe the stronger wind combined with high temperatures makes the difference. Also striking how a thin layer of fog dropped the temperature on 7/8th July.

Did the fog drop the temperature, or did the lower temperature cause the fog to form from the moisture in the air?

106
Arctic sea ice / Re: The 2015 melting season
« on: July 11, 2015, 12:55:29 AM »
Really? The shattering there goes up to about 80 degrees North.  This is 2013, at 87 degrees North, with the Pole itself at the bottom edge of the picture, just left of centre.
http://1.usa.gov/1KTYvfZ
Indeed, but we all remember that 2013 was the year of the persistent cyclones, and it is only logical for patches of open water within the ice pack to show up.

But this year there are very little diverging winds, especially in the past week with the shattering going ever further inwards, under high pressure clear skies.

I'm not saying it is unprecedented (perhaps it is), but this is all happening in situ! That's my point, not that there's open water nearing the pole (we're used to that, happens during winter even), but the fact that it isn't caused by winds, but by in situ melting.

And look at what it's doing to Wipneus' compactness graph:



Look at the dark blue trend line for the Uni Hamburg 3.125x3.125 resolution. Amazing.

Quote
It's looking quite bad, but I'm not yet ready to say it'll be as bad as 2012, or even 2010/2011.
I didn't say it either. And I don't say it because I don't think it. As things stand now, I still don't see this year make it to the top 3, but I'm not as certain of it as I was 2-3 weeks ago.

If you pushed me, I'd say that unless something happens soon to protect the Beaufort/Chukchi, then we're looking at a year quite like 2010, where there was a bunch of old ice in the Beaufort which got massacred by a huge high pressure dome, leading to a big volume drop but no new extent record.  It'll precondition things for bad years in 2016/2017, and I'd certainly expect dramatic new records by 2020 - but I'm not going to call it for this year.
Agreed. The Pacific side of the Arctic is incredibly important for sea ice pack health, and it's been under relentless attacks since the early start of the melting season.

I can't for the life of me find the Wipneus compactness page - where is it?

107
Greenland and Arctic Circle / Re: Greenland 2015 Melt Season
« on: July 11, 2015, 12:21:43 AM »
Based on my eyeballing of today's melt from MODIS/Terra 4km, there should be an uptick when NSIDC updates tomorrow, since the melting surface area has expanded and only the region inside the orange polygons is not melting, AFAICT:


108
Arctic sea ice / Re: The 2015 melting season
« on: July 10, 2015, 03:31:03 PM »
Though the probabilities are obviously biased high (as Slater et al. even go on to admit), here is the latest Slater map:


109
Arctic sea ice / Re: 2015 sea ice area and extent data
« on: July 09, 2015, 06:03:52 PM »
I doubt that draining melt ponds would cause the concentration to go up that much in any one place. A melt pond that has been there long enough to lose its fresh water would have also been there long enough to have a good shot at turning into an outright melt hole, especially on first-year ice.
Do you have a bath?  If so, how big is the plughole? You can drain an acre of melt pond through a 1 metre hole.


Ok, but if the effective freeboard of the bottom of the melt pond is negative, then even with a drain, some water will remain in the pond at gravitational fluid (isostatic) equilibrium.

110
Arctic sea ice / Re: The 2015 melting season
« on: July 09, 2015, 02:10:31 PM »
OSISAF/MyOcean is showing now that the <85% concentration area now occupies a "solid majority" of the Arctic Ocean:

111
Arctic sea ice / Re: 2015 sea ice area and extent data
« on: July 09, 2015, 01:54:29 PM »
I doubt that draining melt ponds would cause the concentration to go up that much in any one place. A melt pond that has been there long enough to lose its fresh water would have also been there long enough to have a good shot at turning into an outright melt hole, especially on first-year ice. If this happens, the area not covered by ice is still there, only now in the form of a melt hole instead of a melt pond. On the other hand, if the ice disintegrates into much smaller floes and spreads to cover the surface again, then this could cause concentration to go up.

I would argue that a more plausible explanation for these upticks is clouds. Though thin clouds don't affect the lower-frequency SSMI/S sensor as easily as the higher-frequency AMSR2, thick clouds still do it.

I don't have time at the moment to show a series of images that makes it visually clear how to see the impact of clouds on the concentration maps, but suffice it to say that if you have a MODIS image of well-defined cloud bands over heavily ponded ice, and open a browser window side-by-side with a CT or Bremen map of the same day*, it will be obvious what's going on, with only cursory inspection.

*BEWARE of the delay in CT maps - the labeled date is incorrect, and the actual date lags by 2-3 days.

112
I found another correlation - this time between the region of ice concentration >60% on August 05 , XXXX (also from MyOcean source) correlated with the NSIDC September monthly coverage in XXXX.

2012:



2013:



2014:



I intend to use this for my August submission to SIPN, because the y-intercept for the linear regression is just 0.6452 M km^2 (The ideal value is zero). I can thus argue that the MyOcean-derived red region is my Ansatz for the shape of the ice pack in September, though I will still use the full linear regression against pixel count for my extent guess. Of course this will have to wait for either a forecast or data for August 5, 2015 to be available. In the meantime, my July SIPN prediction is a repeat of June.


113
Arctic sea ice / Re: The 2015 melting season
« on: July 08, 2015, 02:04:55 PM »
I believe the short term effect of blocking the sun in July is more imporatnt than resultant albedo later in regards to sea ice, except maybe the very thick MY floes. In Greenland it's the opposite.

I noticed that the article mentions that smoke can also lead to heating of higher layers of atmosphere compared to the surface and that this may actually inhibit cloud formation. If this occurs, some of the reduced insolation would be offset by the increase in insolation from reduced clouds.

114
Permafrost / NH snow cover for June is second lowest on record
« on: July 08, 2015, 04:03:14 AM »
See chart. (Note: This only includes land snow, not snow on sea ice, so this is a separate measurement from the very low June snow seen on sea ice this year).


115
Arctic sea ice / Re: Arctic Image of the Day
« on: July 07, 2015, 10:29:39 PM »
Is the eagle welcoming the ice to the endangered species list?

No, it's leaving the Arctic before the polar bears get too hungry!

Is that a hole through its heart or lung?  Or does it 'just miss' this time?

It's a mark from when it was attacked by an Arctic fox - fortunately it escaped.

 :)

116
Arctic sea ice / Re: The 2015 melting season
« on: July 07, 2015, 01:56:06 PM »
Ice concentration is now <85% across about half of the Arctic Ocean (horizontally scrollable image):

 

117
Arctic sea ice / Re: 2015 sea ice area and extent data
« on: July 06, 2015, 05:48:39 PM »
On the other hand is it at all possible to detrend what goes on in the Arctic with what goes on elsewhere? As I stated before and you have in no way denied, it is not an isolated environment.
You can not detrend the weather in England from what occurs in the Caribbean or what is happening in Greenland, they are all linked.
The extent in the Arctic is linked to the amount of snowfall on the ice, the SST of the Arctic, lows and highs, rainfall, wind direction, fires ..... all of which are governed far more by outside Arctic influences then by the Arctic itself especially in its current state. The problem science has is that the more chaotic things get the more trouble science has at defining what is important or how much each influence has importance. The less ASI you have the more chaotic everything becomes. The more chaotic thins become the less you can detrend anything because everything starts impacting everything else more and more.
Example: up to about 2000ish when you had a very high min extent, the jet stream was very fast smooth and very predictable. With that cam fairly predictable overall seasonal weather patterns. Now the jet stream wanders all over the place, seasonal weather patterns in any given geographical location have become more and more unusual, ocean currents are now starting to noticeably change etc.
BUT the greatest influences are no longer IMO based on multidecadal impacts, it is much more on the impacts of systems being sent into the Arctic that get their start far further away.
When a blocking high gets setup over Greenland systems get stuck over North America and systems in the Pacific then are tending to end up going into the Arctic. At the same time systems coming up the East coast of NA hit that high and either go west and push things north of Greenland into the Arctic or go east and because of a vacuum type effect end up going into the Arctic. These are not decadal systems these are just regular systems that always move around. The problem with that Greenland blocking high is that if the ice extent had been high it would have been located over the north pole. All this trying to say that you can no longer decouple the Arctic from the globe because chaos reigns supreme.

I'll show you one example. Here is a plot of July-August temperatures averaged over the tropics, year by year:

http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=23.5&lat2=-23.5&lon1=0&lon2=360&iseas=1&mon1=6&mon2=7&iarea=1&typeout=2&Submit=Create+Timeseries

and here is the same for the Arctic:

http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=90&lat2=66.5&lon1=0&lon2=360&iseas=1&mon1=6&mon2=7&iarea=1&typeout=2&Submit=Create+Timeseries

You can open them side by side in two browser windows and see that, apart from the overall warming trend, the individual warm/cool years in one series don't line up with those in the other series.

118
Arctic sea ice / Re: Arctic Image of the Day
« on: July 06, 2015, 05:32:52 PM »
High Concentration Ice "eagle" (my drawing on CT map):



119
Medvedev's planning to increase the capacity of the Northern Sea Route by 20 times over the next 15 years, from the current 4 million tons to 80 million tons, alongside planning other developments in the region.  The heat released from, turbulence caused by, and direct mechanical damage to ice from cargo ships passing through in this way are doubtless all tiny things compared to the major inputs for sea ice melting, but this is probably not good news for arctic sea ice, all the same.

My concern would be over soot emissions causing an increased "dark snow" effect in the Arctic.

120
Arctic sea ice / Re: 2015 sea ice area and extent data
« on: July 06, 2015, 04:45:39 PM »
LRC1962 and DavidR,

There is a lag of several months between El Nino region SST's and global temps; also, there's no evidence of correlation of detrended global temps with detrended Arctic temps over a relevant period (say, 1980-present or 1981-2010).

Yes, some mixing does occur, but so what? That could lead to a positive correlation, or it could lead to a negative correlation (since warm air going into the Arctic would be expected to occur simultaneously with cold air flowing out of the Arctic and thus reducing temperatures elsewhere), or, it could lead to a zero correlation.

You simply don't have any justification at all for inferring from year-to-year fluctuations of El Nino, PDO, or global temps to temps in the Arctic, except on a multidecadal (climate) basis.

The mere existence of atmospheric mixing does nothing to change that.

121
Arctic sea ice / Re: The 2015 melting season
« on: July 06, 2015, 04:32:12 PM »
I wonder why bottom ~half of the picture was not transmitted.

I think I can see why they didn't show the full image . . .

Nice...

122
Arctic sea ice / Re: Making sense of irregular data
« on: July 06, 2015, 04:27:12 PM »
I have followed the arctic ice graphs for some years and notice the attempts to gain a long term insight from annual (or monthly)  linear data which by it's very nature is irregular even chaotic, due to prevailing weather rather than climate changes.   However the irregularities are disguising the real data, so better if they were filtered or weighted down. The ice which remains in Hudson bay is irrelevant to the annual min. extent, it will be all gone come September. In addition to current graphs, I suggest to display data such as piomass, ice thickness in a more limited area (say with 75deg N) or by applying a spatial  algorithm  that would give a better understanding of trends.
Various interpolation methods are described here www.knmi.nl/bibliotheek/knmipubIR/IR2009-04.pdf

Huh? "Interpolation" is what you do to deal with gaps in a set of data, not what you do if you want to only look at a subset of the data.


123
Arctic sea ice / Re: The 2015 melting season
« on: July 05, 2015, 06:09:02 PM »
@Jim Hunt

Wow.

Holy smokes, if that's remotely accurate we're going to see some incredible drops in area and extent over the next couple of weeks.

It probably isn't remotely accurate. I mean, why the sharp division between the areas north and south of 80N?

I've been wondering the same thing myself for quite some time. The 80N "boundary" seems to be quite ancient as far as the models go - even in older versions of ARC you can see it showing up in their SST maps during the summer in several years - notably 2012, 2013, and this year.

124
Arctic sea ice / Re: 2015 sea ice area and extent data
« on: July 05, 2015, 04:54:44 PM »
" el ninos beginning in summer of a given year appear to have no discernible impact on September extent."

That's true, but hasn't this El Nino been building for a lot longer than this summer?

You've got links to data, feel free to demonstrate it. :)
There are a number of indicators that the impact  of this El Nino may  be different  than previous ones.

1:  This year  the SOI has been reasonably  negative since August last  year:
http://www.bom.gov.au/climate/current/soihtm1.shtml
compared to  1982 and 1997  where it  was neutral or positive until the northern spring. 

2: the 1982 El Nino was impacted by the El Chichon volcanic eruption in April 1982 which would have reduced global temperature increases, however a record global temperature, and Sea Ice extent minimum occurred the following year.
https://en.wikipedia.org/wiki/El_Chichon

3. The Pacific Decadal Oscillation Index sat  above +2 for four months from December to  March this year:
http://research.jisao.washington.edu/pdo/PDO.latest
The last time this happened was June - Sept  1997; and every time it  has happened we have seen global temperature records in that year or the subsequent year.

So, given that all the precursors of significant warming were in  place from late last year, I  believe there is the possibility of significant impact this year.

Arctic sea ice is only impacted by local forcing, not global temperatures. This forcing can include temperature, dew point, shortwave and longwave radiation (upwelling and downwelling), wind, sea surface temperature and salinity, waves, and other factors.

At the level of changes in climate, which take place over multidecadal and longer time scales, local temperatures and global temperatures are very tightly correlated, for both natural climate changes observable from paleoclimate data, and also from human-induced climate change which is easiest to observe in the records of the most recent decades (i.e. the 1980s and later).

However, when it comes to weather changes that cause year-to-year fluctuations in Arctic ice extent, area, and volume, there is no reason to presume a correlation with year-to-year global weather fluctuations.

 

125
Arctic sea ice / Re: Records and oddities
« on: July 05, 2015, 04:07:01 AM »
The concentration of ice on August 1 tells you with almost zero uncertainty what the final pack will look like (size and shape). Here is the example from 2012 with a threshold of 65% concentration:


126
Arctic sea ice / Re: The 2015 melting season
« on: July 04, 2015, 11:07:49 PM »


Of course the model expects huge drops - it classifies that ice as only ~5 cm thick!!!

127
Arctic sea ice / Re: Latest PIOMAS update (July)
« on: July 04, 2015, 10:42:10 PM »
Mathematically the zero thickness band needs upper and lower limits, those limits have been chosen as shown. Zero thickness band is open water, not very thin ice, this is by definition.

No, "open water" is a thickness of precisely 0, not a thickness of < 0.1m!!!

The bands are bands of thickness within the grid box upon which the equation set of the model operates, moving ice volume up and down through the bands according to the modelled processes.

When you take grid box effective thickness the situation is different, a gbet if 0.1m may indeed represent dispersed ice, which in theory could be thick chunks in a lot of open water.

Typing on a very bouncy bus! Hope I make sense.

PS just occurred to me that if lower limit of zero band were zero exactly ut might make the equations crash.

I don't get it. What happens when ice first "grows" from zero thickness? There is necessarily a time when it is not zero, but is less than 0.1m. How is this handled by the model?

128
1.97 M km^2, from the linear regression of CT areas against mid-June snowcover - i.e. the same technique used for NSIDC extent.

129
I will stick with 3.26 M km^2 because concentration seems to be dropping ahead of schedule, thus corroborating the snow data used to make the prediction in June. I have had to carefully examine MODIS images and "mentally remove" the clouded areas from concentration plots - and the areas with a concentration low enough to melt by September seem to line up well with what was suggested by mid-June snow-cover from MyOcean. I call it a confirmation.

130
Arctic sea ice / Re: The 2015 melting season
« on: July 04, 2015, 03:16:30 PM »
Near 30 C (86 F) on Wrangel Island!!!  :o


131
Arctic sea ice / Re: Latest PIOMAS update (July)
« on: July 04, 2015, 01:55:41 PM »
Nightvid, Oren,

The bands are given in my post on PIOMAS Gice, from the paper by Dr Zhang, they're shown in the image below.


Since negative thicknesses are physically nonsensical, shouldn't you use 0.05 as the thickness to calculate the volume of the "0" band, since it represents thicknesses from -0.1 to 0.1 and thus physically must be 0 to 0.1, with a middle of 0.05?

In other words, volume = area * 0.05, not area * 0?

OR, alternatively, would this lead to the entire open water portion of the domain making a spurious contribution to the volume?

Is there any distinction between "real" zero and "very very thin" ice?

132
Arctic sea ice / Re: Latest PIOMAS update (July)
« on: July 04, 2015, 01:57:18 AM »
Actually the animation confirms the 1 m thinning of the ice from Beaufort to Laptev and part of the CAB. So no surprise about something I still dont understand. What caused such thinning in this particular June month? Storms?

In Beaufort the av thickness is about or less than 1m, but because of open water, the MYI floes probably are 1.5 to 2 m thick.

If the PIOMAS sub grid thickness distribution is right (it probably is more or less) then here are the June GICE sub grid thickness distributions for post 2010 years in Beaufort. So for example, the thickness band centred on 20.62m thick has a volume of 12.78km^3, this is intended to represent the bands of ridged ice in pressure ridges across the pack.

Thickness   2010   2011   2012   2013   2014   2015
0m   0.00   0.00   0.00   0.00   0.00   0.00
0.26m   16.43   19.59   13.77   11.52   18.25   14.34
0.71m   36.53   3.62   5.80   10.43   26.04   22.26
1.46m   110.35   94.96   74.72   197.02   147.39   108.75
2.61m   126.56   268.06   184.41   340.86   201.56   173.55
4.23m   64.11   139.46   115.87   180.58   98.31   104.71
6.39m   30.05   47.07   39.45   73.73   40.41   42.82
9.1m   26.82   38.47   26.54   69.89   32.41   36.58
12.39m   26.98   42.87   28.50   78.66   32.39   39.20
16.24m   26.90   45.16   28.44   80.30   30.86   39.79
20.62m   8.27   18.05   7.37   21.16   4.45   12.78
25.49m   2.96   5.90   2.39   6.85   1.29   4.30

This also answers the concerns about PIOMAS disagreeing with one point in a million km^2 area (519000km^2 for Beaufort, 584000km^2 for Chukchi). What you see in Wipneus's plots is the grid box effective thickness. The relationship between the effective thickness and the sub grid thickness distributions is explained here:
http://dosbat.blogspot.co.uk/2015/04/what-is-piomas-gice.html

There is no discrepancy between PIOMAS and the single points from bouys, this issue is why point data like Buoys were not used in the Schweiger et al 2011 intercomparison study. Moored ULS sounders were used, but they are fixed to the sea ice, and sea ice movement can present the range of actual thickness.

PIOMAS has a bias: From Schweiger et al 2011 "PIOMAS appears to overestimate thin ice thickness and underestimate thick ice, yielding a smaller downward trend than apparent in reconstructions from observations."

PIOMAS gain since June 2012.


Ok, this makes sense. One minor quibble - the 0.000m thickness band is obviously only those with thicknesses less than or equal to 0.00m - otherwise the volume would not be zero. It is *not* a band centered on 0.00m.

So I'd assume that, likewise, "0.26m" is thicknesses UP TO 0.26m, not "centered on" 0.26m, and so on. Right?

133
Arctic sea ice / Re: Latest PIOMAS update (July)
« on: July 03, 2015, 08:53:46 PM »
It is absolutely, positively weird just how thick PIOMAS thinks the ice off the CAA and Greenland have now become. If we are to believe it, that ice has gone from ~2.5 m in 2012 to > 4 m in 2015. This is a 70% increase in thickness!

What's even stranger still is that PIOMAS seems to have started seriously straying away from anything with a semblance of reality - the buoys on the Pacific side of the CAB are unanimous in telling us that this ice did not get above 2 - 2.05 m in thickness this past winter, and most of them topped out at only around 1.75 m. Yet PIOMAS thinks it got up to almost 2.5 m.

Also, TOPAZ4 seems to agree with Cryosat as well as ADS/VISHOP in telling us that the thick ice of 2014 on the CAA side of the Arctic had in fact moderated in thickness this year in winter and in spring. Quite to the contrary, PIOMAS is saying that this ice got even thicker, for a third straight year!!!

I am truly surprised by this. PIOMAS seemed to be a good model, or so I thought. Now it basically has gone its own way and is disagreeing with every other model and observation. Why????

A few weeks ago I had a look at the IceBridge QuickLook data, which can be downloaded at this page.  These data confirm that the sea ice north of the CAA was thicker in March 2015 than in preceding years.  Moreover, the same is true for the sea ice in Eastern Beaufort Sea.  That seems to be in good agreement with PIOMAS.

Regarding Cryosat, this recent paper by Ricker et al. 2015 may be relevant.  The paper suggest that Cryosat overestimated the sea ice freeboard and thickness north of the CAA during the 2013/2014 freezing season, due to snow backscatter of the radar signal.  Here are the concluding paragraphs of the Ricker et al. paper (see especially the first one):

Quote
An exceptional high snow depth and early accumulation during the freezing season 2013/2014 north of Canada, shown by IMB measurements and indicated by Operation IceBridge snow depth retrievals, might have lead to the major increase of CryoSat-2 multiyear ice freeboard in November 2013 for this region. By quantifying the impact on CryoSat-2 sea ice thickness retrievals, we obtain a mean multiyear ice thickness bias of 1.4 m, if it is assumed that the main scattering horizon is given by the snow-ice interface.

We conclude that snowfall can have a significant impact on CryoSat-2 range measurements and therefore on ice freeboard, thickness, and volume. The assumption that the CryoSat-2 main scattering horizon is given by the snow-ice interface cannot be justified in regions with a thick snow layer. Finally, this study also shows that there is a strong need for more data and knowledge about the seasonal cycle of snow distribution and properties on sea ice.

Thanks - the Ricker et al. paper was quite interesting, and does explain a lot. It also seems unsurprising in light of the fact that it seems that microwaves' penetrating power of lots of things seems to often be overstated - yet in reality, even light things scatter and block microwaves quite a bit. The same phenomenon probably accounts for why clouds block the passive microwave data so easily, why bad weather interrupts satellite TV, and cell phone signals get cut out so easily. In all these cases, it seems the assumption (though incorrect) is that dielectrics are transparent, even though in reality they are not - as observation demonstrates.

However, this still does not solve the paradox of why TOPAZ4 and PIOMAS get such dramatically different answers, nor does it explain why PIOMAS disagrees with the buoy observations about ice thickness in the Beaufort/Chukchi sector of the CAB.


134
Arctic sea ice / Re: Latest PIOMAS update (July)
« on: July 03, 2015, 06:15:22 PM »
It is absolutely, positively weird just how thick PIOMAS thinks the ice off the CAA and Greenland have now become. If we are to believe it, that ice has gone from ~2.5 m in 2012 to > 4 m in 2015. This is a 70% increase in thickness!

What's even stranger still is that PIOMAS seems to have started seriously straying away from anything with a semblance of reality - the buoys on the Pacific side of the CAB are unanimous in telling us that this ice did not get above 2 - 2.05 m in thickness this past winter, and most of them topped out at only around 1.75 m. Yet PIOMAS thinks it got up to almost 2.5 m.

Also, TOPAZ4 seems to agree with Cryosat as well as ADS/VISHOP in telling us that the thick ice of 2014 on the CAA side of the Arctic had in fact moderated in thickness this year in winter and in spring. Quite to the contrary, PIOMAS is saying that this ice got even thicker, for a third straight year!!!

I am truly surprised by this. PIOMAS seemed to be a good model, or so I thought. Now it basically has gone its own way and is disagreeing with every other model and observation. Why????


135
Greenland and Arctic Circle / Re: Greenland 2015 Melt Season
« on: July 03, 2015, 02:02:10 PM »
CCI hints at a plume of 20-40mm precipitable water forming off Greenland's west coast in a week, carried in by Southerly winds. This is exactly what we saw in 2012 in the 1-2 days immediately preceding the monster melt.  :o

136
Arctic sea ice / Re: IJIS
« on: July 03, 2015, 01:35:29 PM »
IJIS:

9,387,654 km2(July 2, 2015)down 44,050 km2 from previous.

...and 8th lowest.

137
Arctic sea ice / Re: The 2015 melting season
« on: July 02, 2015, 08:53:38 PM »
if you look at the series of images, you can also see how the melt ponds are expanding.

Now, one weird thing for me:
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2015183000000-2015183000500.250m.jpg

Today we have a quite good view on the rapidly progressing Chukchi bite, first time in a week. If you look at the edge between ice and free ocean next to Wrangel, there is a very prominent, quite brilliant white edge. Why?

The band of clouds, you mean?

138
Arctic sea ice / Re: 2015 sea ice area and extent data
« on: July 02, 2015, 04:53:01 PM »
Well the June figures for NSIDC extent are in, and at just 1.864 M km^2  its the smallest drop since 2004 which fell just over 1.2 M km^2.  At the time 2004 was the 9th lowest on record but by the end of the season it had dropped to 3rd lowest on record.

We didn't even get near the statistical 260 K anomalous drop that we normally see on July 1st.  The only  recent time we haven't seem this drop on July 1st it showed up on July 2nd so it will be interesting to see what  tomorrow brings.

All in all still an interesting season where anything can happen if the el Nino starts to  bite.

El nino is probably totally irrelevant. In the satellite record, el ninos beginning in summer of a given year appear to have no discernible impact on September extent. The two strongest ones began in 1982 and 1997 - and the September extent even in those extreme years was well within the range of the years just before and just after it. I should also add that one of those years was above the linear trendline and the other was below it, but not significantly so.

I think it is safe to conclude that even a monster El nino starting this summer should have no detectable effect on September 2015 ice extent. It is safe to ignore it.

139
Arctic sea ice / Re: The 2015 melting season
« on: July 02, 2015, 01:50:11 PM »
Ready or not, here basin-wide melt ponds come: (Source: MyOcean, taken from http://met.no/OSISAF.b7C_w7HM06.ips)


140
Arctic sea ice / Re: The 2015 melting season
« on: July 01, 2015, 09:27:33 PM »
The map shows a significant probability of ice in Hudson Bay, even though it is normally ice free at that time of year, so I do not believe it.

Yeah, I agree that the map isn't to be trusted. The model is "dumb" in the sense that it is given information about how much ice exists at each concentration, but not where the ice is.  It's interesting that it is fairly successful with so little information, but turning the calculation into a map doesn't really make that much sense - it's just the concentration map with a caxis (color axis) remapping.

Perhaps the problem could be remedied by accounting for April or May PIOMAS thickness. Hudson is only ~1m thick, while the ice in the CAB is about double that.

141
Arctic sea ice / Re: The 2015 melting season
« on: July 01, 2015, 06:48:36 PM »
It's almost identical to today's sea ice concentration map. Surely something will melt in the next 75 days?

Edit: Oops, make that 50 days, but still . . .

The map is the *probability* of ice cover at all, not the concentration. A value of 50% means a 50% chance of any ice at all (>15% conc.)

142
Arctic sea ice / Re: The 2015 melting season
« on: July 01, 2015, 05:17:13 PM »
Slater forecast has interesting spatial pattern:


143
Arctic sea ice / Re: The 2015 melting season
« on: June 30, 2015, 10:03:05 PM »
I'd love to be able to interpret these forecasts like some of you can. Where can one go to learn about that? Any MOOCs to take?

1. https://en.wikipedia.org/wiki/Buys_Ballot's_law

2. Experience...


144
Arctic sea ice / Re: The 2015 melting season
« on: June 30, 2015, 02:55:25 PM »
IF the forecast holds, there will be a huge WAA over Chukchi and ESS in about 5 days. In Beaufort HP dominated weather will make its presence..

In about 6 days, a heat dome will reach Hudson and toast the ice in combo with some winds too...

Baffin is under fire too soon...

Single, double or triple century breaks anyone?

//LMV


Once Lake Erie & Lake Ontario finally melt out things may slow down again.

Terry


Hmmmm, perhaps we could assimilate some data from unanimous boater reports of open water and lake surface water temperatures far too high for ice to be possible?  ;)

145
Developers Corner / Cloud masking?
« on: June 29, 2015, 06:46:14 PM »
Anybody know how to get cloud data that's used to create declouded TERRA images over the Arctic? I'd like to be able to decloud other Arctic data as well - i.e. to create declouded AMSR2 maps and the like.

146
Arctic sea ice / Re: What the Buoys are telling
« on: June 29, 2015, 03:47:58 AM »
I have never seen quite as bizarre shaped an ice floe as this one:


147
Greenland and Arctic Circle / Summer 2015 Alaska Wildfire Thread
« on: June 28, 2015, 03:21:05 PM »
It has now gotten so bad that air quality in Fairbanks has reached dangerous levels:

Issued by The National Weather Service
Fairbanks, AK
Fri, Jun 26, 5:21 pm AKDT
... AIR QUALITY ALERT IN EFFECT UNTIL 5 PM AKDT MONDAY...
THE FAIRBANKS NORTH STAR BOROUGH AIR QUALITY DIVISION HAS ISSUED AN AIR QUALITY ALERT... IN EFFECT UNTIL 5 PM AKDT MONDAY.
THE FAIRBANKS NORTH STAR BOROUGH AIR QUALITY IS CURRENTLY CLASSIFIED AS UNHEALTHY AND EXCEEDS THE EPA HEALTH LIMIT FOR FINE PARTICULATE POLLUTION. PEOPLE WITH RESPIRATORY OR HEART DISEASE... THE ELDERLY AND CHILDREN SHOULD AVOID PROLONGED EXERTION; EVERYONE ELSE SHOULD LIMIT PROLONGED EXERTION.
FOREST FIRE SMOKE AND LOCAL AIR QUALITY CONTINUES TO REMAIN HIGHLY VARIABLE. THE NATIONAL WEATHER SERVICE HAS FORECAST HIGHER HUMIDITY AND RAIN SHOWERS OVER THE WEEKEND... WHICH WILL HELP TO IMPROVE AIR QUALITY... BUT WILL NOT COMPLETELY ELIMINATE THE SMOKE. SO THE FAIRBANKS NORTH STAR BOROUGH IS FORECASTING AIR QUALITY TO VARY FROM UNHEALTHY TO MODERATE AS SMOKE MIXED WITH RAIN SHOWERS MOVES THROUGH THE AREA. IN ORDER TO MORE ACCURATELY JUDGE THE PARTICULATES FROM SMOKE IN YOUR IMMEDIATE AREA... PLEASE USE THE JUDGING PARTICULATE LEVELS CHART FOUND ON THE FAIRBANKS NORTH STAR BOROUGH AIR QUALITY WEBSITE.
NOTE THAT AIR QUALITY READINGS ARE FROM MONITORING STATIONS IN FAIRBANKS AND NORTH POLE AND MAY NOT BE REPRESENTATIVE IN YOUR AREA. PARTICULATE CONCENTRATIONS WILL BE HIGHER IN THE COOLER OVERNIGHT HOURS... AND WILL VARY WITH WIND DIRECTION AND PROXIMITY TO A FIRE. IF YOU ARE SENSITIVE TO RESPIRATORY PROBLEMS AND EXPERIENCE ANY EFFECTS PLEASE FOLLOW THE INSTRUCTIONS OF YOUR PHYSICIAN.



Above: Smoke has also moved to North parts of the state, as seen on this TERRA image taken from NASA web site (Scroll bar is at bottom of image).


148
Arctic sea ice / Re: The 2015 melting season
« on: June 27, 2015, 06:54:04 PM »
That is gtreat piece of knowledge Bruce, thx.

A few days ago it was also about winds transporting heat from sea sutrface in Chukchi into the Atctic ice, and as LMV showed us several times, that did not happen. Rather the opposite, the region has cooled down a bit. Saved some ice!!

For big July melting two big questions are: will finally ESS and Laptev will open up soon enough?? Once open, they can have a melt runaway and affect CAB with some sun still heating up.
And, will those nice MYI floes in Beaufort and the thick ice in Chukchi melt out? Things have slowed down so much that a really warm windy sunny weather had to come.

You seem to think that the melting of the ice pack proceeds from the outer edges inwards and that peripheral melting causes central Arctic melting.

But this is not the case - the ice melts from the top surface and from the bottom surface. You can indeed have melting on the lateral surface of ice floes, but the lateral melting from the edges of the pack is not what gets you to the September minimum - simple back of the envelope calculations suggest that the melting from action at the edges of the ice pack is orders of magnitude too slow.

In essence, all the melting is local. While you can certainly have short-range effects such as warm water from open areas undercutting ice elsewhere, the speeds of water and ice motion are too slow for the ice cover in the peripheral seas in July to impact the ice near the North pole by September.

You could literally delete all ice in the peripheral areas right now and the impact on the North Pole ice by September would be too small to detect.

All ice melt is local.

149
Arctic sea ice / Re: The 2015 melting season
« on: June 27, 2015, 02:07:12 PM »
The concentration is slightly falling in the area inside the violet oval. I expected a somewhat more dramatic reduction, but this still confirms the uptick in melting there as suggested by MODIS.

CT should follow suit, when they (finally) have their map for 6/26 available.

150
Arctic sea ice / Re: The 2015 melting season
« on: June 27, 2015, 01:49:21 PM »
In big contrast to CC_Reanalyzer, UiB satellite data make following estimation of the snow cover in the Arctic showing that there's still vast areas with more than 50 cm of snow northeast of Svalbard. Also, the western part of Laptev Sea still have 30-60 cm of snow depth.

The main question now is how reliable is this result?

See more at: http://www.iup.uni-bremen.de:8084/databrowser.html#tab=tabs-browser&day=26&month=5&year=2015&img={%22image%22:%22image-1%22,%22sensor%22:%22AMSR_SNOW%22,%22color%22:false,%22region%22:%22Arctic%22}  Click for full size!

//LMV

That's just bizarre. 50-60 cm snow depth on Atlantic side when ice surface melt is happening, despite the fact that these depths are rare even for April as measured by buoys?

I just cannot take this source seriously (any more than we could take PIPS seriously in 2010/2011 when it was giving 4 meter ice thicknesses for rapidly melting first year ice).  :-X

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