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Messages - Greenbelt

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1
Arctic sea ice / Re: The 2020 melting season
« on: August 08, 2020, 03:11:02 PM »
The weather models seem to want to set up another bit of strong flow from the Atlantic through the pole to central Siberia in the five day period.  What this will do to the ice measures I couldn't say, but in general it seems that wind starts to dominate sun at some point in August as a ice volume reducer.

3
Arctic sea ice / Re: The 2020 melting season
« on: July 29, 2020, 02:52:18 AM »
Some changes near the Alaska coast. Top is July 28, bottom is July 25


4
Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 01:50:07 AM »
Regarding compaction or not, I keep going back to the Polarstern pic from late June.  If ice like that is being regarded as compact, I think it could in fact pack together a lot tighter.  Click for high res.

5
Arctic sea ice / Re: The 2020 melting season
« on: July 19, 2020, 12:42:29 AM »
Today's Worldview big picture is beautiful.

6
Arctic sea ice / Re: The 2020 melting season
« on: July 18, 2020, 03:54:50 PM »
I noticed that the EPS ensemble forecasts were nearly identical the last two runs with average of a 990s mb low in the Beaufort. The 12z operational yesterday with the extreme deep low must have been a bit of an outlier maybe? Or just that the forecast models are freaking out a little bit with all the warmth and now a surge of moisture into the Arctic. Caveat: I like tracking the weather, but have no real meteorological knowledge, so take my interpretations with appropriate caution.
https://tropicaltidbits.com/analysis/models/?model=ecmwf-ens&region=nhem&pkg=z500_mslp&runtime=2020071800&fh=156

7
Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 06:57:11 PM »
Looks like the 7-day forecast is coming into better focus with the GAAC drifting to the ESS and (finally) dissipating, low pressure entering from Russia along the Atlantic ice margin bringing rain to the central Arctic and, along with the GAAC, bringing very warm air northward from Siberia, and then a possible broad low pressure maybe in sub 990mb range consolidating in the Beaufort region with maybe some sunny high pressure along the Atlantic.

8
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 08:54:05 PM »
So ECMWF Days 1-3 strengthens the GAAC from 1029mb to 1034. Days 4-6 shifts the GAAC toward the ESS allowing very warm southerly winds off Siberia to fetch far into the Central Arctic. Then Days 7-8 rapidly develops a sub 980mb low.  That model does not like ice.

9
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 02:25:26 AM »

So the ice sheet had definitely broken up somewhat several weeks ago.  But the current view looks much more uniform and solid.  And much more liquid on the surface.  Is it because the floes are now mostly too small to be seen individually?  Has the recent high pressure driven compaction pushed it all back together into one sheet?  Are the faint white lines currently visible that look a bit like reverse cracks pressure ridges or something else?

I have no answers only more questions! And more pics.  Look at this spot: https://worldview.earthdata.nasa.gov/?v=-804286.5994982878,274771.1967389671,-454590.599498288,478760.53007230035&p=arctic&t=2020-07-13-T23%3A42%3A44Z

The honeycomb pattern replaced the floe-y pattern in only 8 days' time.
First pic is July 1 of this year.
Second pic is July 9 this year
Third pic is August 13 (!) of 2019

10
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 01:31:52 AM »

Mostly quite compact, and the question is how thick is it?  And how fast is it losing ice?  Last year I noted compactness of much of a similar area around this time to be a big reason to not expect a record year.  This year we have much stronger surface melt conditions,and a significant although not yet huge lead in extent over all other years.  I also note that a lot of this compact ice is starting to get small holes in it.  My interpretation is transition from a mostly solid sheet to lots of jammed together floes with some gaps where they don't quite fit right.  I will be watching closely to see how much these holes grow and spread.

Location

Same location June 23 attached pic.  Granted some ice drift in that time gap, but interesting to me how the ice with visible floes becomes the honeycomb pattern when top melt kicks in. I think this section of ice now likely looks a lot like that Polarstern helicopter photo that Oren posted earlier in this thread.

11
Arctic sea ice / Re: The 2020 melting season
« on: July 13, 2020, 08:32:01 PM »
12z Euro still has the big circular beautiful terrifying High pressure right in the middle of Arctic on Day 5.

12
Arctic sea ice / Re: MOSAiC news
« on: July 13, 2020, 12:41:46 AM »
The surprise to me is that the ice in that general area of the Mosaic floe didn't look that bad on Worldview on June 30 when that helicopter picture of the Polarstern was taken.  With the clear skies over so much of the Arctic recently, it now looks like vast areas in worse shape than this, at least to the untrained eye.

13
Arctic sea ice / Re: MOSAiC news
« on: July 12, 2020, 08:49:25 PM »
The phys.org article contains a stunning picture from June 30. Click for higher res.

14
Arctic sea ice / Re: The 2020 melting season
« on: July 12, 2020, 02:36:58 PM »
One impact of the persistent GAAC might be to push some of that thick ice in the Beaufort toward the soon-to-be open and warm waters of the ESS by August.  Main areas of thicker ice per HYCOM highlighted.

15
Arctic sea ice / Re: The 2020 melting season
« on: July 11, 2020, 11:29:35 PM »
The ten mile cube north of Elsemere Island today and July 7. The slice just the east on july 7 seems now to the north (and smaller)

16
Arctic sea ice / Re: The 2020 melting season
« on: July 10, 2020, 11:22:57 PM »
How can you tell the difference on a satellite photo between a ice covered in melt ponds and frozen ice that isn't covered by snow?  Both would appear blue from a distance and I don't think most satellite photos have the resolution to show the difference.  Is there something I'm missing?

Here's a natural color Worldview pic from June 26 (much bluer in most areas) vs. the same area from today July 10.  That ice didn't refreeze, it just has less standing water on it is my interpretation. The bluish tint seems to fade to grayish as the melt pond drain I think.

17
Arctic sea ice / Re: The 2020 melting season
« on: July 08, 2020, 08:35:02 PM »
And there is it -- ECMWF has shifted to be almost identical to GFS in position and strength of GAAC through Day 6 and Day 7.  I need to go take a walk...

18
Arctic sea ice / Re: The 2020 melting season
« on: July 08, 2020, 06:20:22 PM »
In addition to maintaining the big high at about 1030mb for another week, the GFS op also seems toward another southerly wind event with warm Siberian air carried northward toward the pole and eventually the Fram.

19
Arctic sea ice / Re: The 2020 melting season
« on: July 08, 2020, 02:25:18 PM »
If I'm doing it right, this is a comparison of the same approx area I posted yesterday, this time from today's Worldview vs. June 28 of this year. Still true color mode.  I know there is some ice drift, so it's possible we're not comparing exactly the same ice. But I'm wondering how the large intact-looking blobs seem to meld toward the honeycomb pattern in just over a week's time.
https://worldview.earthdata.nasa.gov/?v=-890112,329216,-539904,533504&p=arctic&t1=2020-06-28-T11%3A50%3A34Z&l1=Reference_Labels(hidden),Reference_Features(hidden),Coastlines,VIIRS_NOAA20_CorrectedReflectance_TrueColor(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&ca=false

20
Arctic sea ice / Re: The 2020 melting season
« on: July 07, 2020, 09:38:01 PM »
I took a couple of Worldview true color closeups from today and same date and location in 2012.  Approx location shown in red in the 3rd pic.  There was a bit of cloud and maybe fog in the 2012, but it certainly looks like 2020 melt ponding more extensive at this date. Is that a correct interpretation? Or was 2012 beyond bluing at this point and into the grey zone of drained meltponds?  Or just too cloudy or indistinct to be sure?

21
Arctic sea ice / Re: The 2019 melting season
« on: August 22, 2019, 12:06:38 AM »
Yes good job ^^ joke aside, GFS has been really behind the curve lately.
What's a GFS?
It's the U.S. Global Forecast System, the computer weather model that drives the nullschool illustrations.
If you look at the nullschool menu bar you see this:  Source | GFS / NCEP / US National Weather Service

22
Arctic sea ice / Re: The 2019 melting season
« on: August 21, 2019, 08:55:36 PM »
Seems like a 980mb low in the central Arctic on day 4 would do more to stir up vulnerable ice than a 970mb low in the CAA on day 2?  My hunch is this storm won't be persistent enough to really get the ice moving and the thermoclines mixing, but I am always surprised...

23
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 10:34:09 PM »
I've been somewhat hesitant to post about the weather forecast, but this week's forecast is too interesting to ignore. For about a week now, the models have been predicting a big surface high over the East Siberian sea, with surface low pressure around the Atlantic ice front/Barents and moderately low pressure as well around the eastern Alaskan coast toward the Beaufort sea. For example compare today's ECMWF initialization shown below with that of seven days ago, and you can see that last week's forecast for today verified quite closely: https://tropicaltidbits.com/analysis/models/?model=ecmwf&region=nhem&pkg=z500_mslp&runtime=2019080612&fh=168

What is interesting to me is that the op EC model keeps today's pattern roughly in place for the next week. The GFS and Canadian also support that idea, with the ESS high arcing gradually toward the Alaskan coast and the Atlantic side low drifting over the central ice.  Regardless of the nuances, the Siberian coast heat wave and the consistent southerly winds from the Laptev sea area should test Friv's hypothesis.  Friv had suggested up thread that the ESS didn't melt out early enough this year to allow the open water to warm enough that it could really attack the CAB ice late in the season.  That seemed reasonable at the time, but this extended warm period along Siberia, and the extended periods of southerly winds from Asia toward the pole makes it interesting. I wonder if there is still enough sun power to really heat that newly open water along the ESS and Laptev, and if the fetch of southerly wind would be enough to transport some of that warmth toward the central ice over the next week or two?

24
Arctic sea ice / Re: The 2019 melting season
« on: July 25, 2019, 10:04:51 PM »
Ice in the Greenland Sea likely to take a beating as the heatwave shifts up to Scandinavia and then west to merge with the Polar High.  I'm very curious to watch what happens all along the Atlantic ice front this next week.

25
Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 07:26:04 PM »
To my untrained eyes, the forecast of a big dipole event this coming weekend now seems highly likely, with GFS now very similar to other models and solid ensemble support, with 1030mb high ranging from Fram to Beaufort and 1000mb low along the Siberian coast.  This is 12z today GFS operational for 0z Saturday. I just hope this weather pattern doesn't last too long -- at longer, more uncertain time ranges, the models are still showing a lot of 1020mb high pressure ideas in various locations within the central basin.


26
Arctic sea ice / Re: The 2019 melting season
« on: July 16, 2019, 08:22:26 PM »
The near-term outlook looks to me to be rather poor for ice volume on the Atlantic side.  Winds around the big surface high pressure may push rather weak ice back into the Laptev Sea area, where it may melt in relatively warm seas perhaps.  Although Fram export would seem to stay stopped under this pattern, the Atlantic front may shrink back toward the pole a little maybe. There are some areas on the Atlantic side of the pole where the ice looks to me on Worldview to be a bit more contiguous and less rubble strewn than some prior years, so the weather this week may help melt an area that was looking a little bit more resilient this year? Despite the cooler air temp forecast in the ESS and Beaufort, I think much of the ice in those areas is doomed over the next two months due to warm water. Now the Atlantic may take a hit from still-strong sun for a few days at least?

27
Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 08:13:21 PM »
Yay more long-term forecasts that'll never be referenced again.
Hmmm. I try to check the weekly forecast each weekend. So far this season I think the 5-7 day forecasts have been remarkably accurate. We had advance notice of the large ESS high that torched the Laptev and ESS, advance of the low that traversed the arctic, advance of the recent Greenland-toward-ESS ridge, advance of the current rapid Fram export, and so on. For this week we can use the forecasts to watch out for a wind and heat event in the Barentz, a heat wave with jet stream to nearly the arctic in Alaska, and lower pressure in Siberia coasts mostly. The ensembles are still showing a classic dipole with high on the Canadian side and low pressure along Russia. Below is was the operational GFS for today from 7 days ago -- to my eyes the models have been predicting the main patterns quite accurately for many weeks now. After 5-7 days the operational models can generate some fanciful results to be disregarded, of course.  Nevertheless, I find tracking the forecasts a week ahead very useful for trying to learn what sorts of weather leads to better or worse melting conditions, which is a challenging question even for our experts I think. If Neven thinks the weather forecast discussion is clogging this main thread I think we could create a different thread for the looking ahead perhaps.

28
Arctic sea ice / Re: The 2019 melting season
« on: July 01, 2019, 09:23:36 PM »
I haven't looked at the ensembles or anything, but the 12z operational GFS and ECMWF forecasts look a bit different for next week. Both seem to agree on the major heat pulses into the Kara/Barentz seas and also into the Pacific side from the predicted Alaska heat wave. But GFS brings back higher pressure over the central basin, while EC looks like a bit lower pressures. After Day 7 GFS continues to build high pressure while Euro has a storm. This could be a good test of whether the new GFS has made an improvement over its past poorer predictions than the Euro in the arctic. Another bad (for the ice) week to come I think regardless.
Here's GFS a week or so from today. Euro below for the same time about.



29
Arctic sea ice / Re: The 2019 melting season
« on: June 27, 2019, 04:16:09 AM »
Top part of this picture (near Beaufort/Chukchi boundary) is dominated by much smaller floes that are too small to see individually at this resolution.  Bottom half is much larger floes with many individually discernable.  The rough boundary is also marked by much more discoloured ice - I believe that is algae?  Or is it dust and/or smoke? 
I had always assumed the gray ice at the edges had lost most of its structural rigidity and was mostly floating very low to the waterline and much infused with sea water, rather than algae. Would love to know the answer from experts.

30
Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 04:01:38 PM »
Area and extent are imperfect indicators, but at least can be directly and fairly reliably measured, unlike, say, volume. Area and extent numbers and maps from the various outfits that produce them (NOAA, uni Bremen, Jaxa ...) stay in general agreement while what volume maps exist are much more idiosyncratic.

My main idea is that we stop referring to changes in area and extent as "melting" or "freezing."  Volume measures, however imperfect, indicate melt or freeze.  Although long-term trends in area and extent measures are certainly correlated with melt/freeze, short term changes in the extent and area measures do not necessarily indicate overall melting or freezing situation. Extent can increase due to dispersion etc., even where there is overall melting. I think using the shorthand of "melt" or "freeze" with area and extent measures may be a source of confusion sometimes.

31
Arctic sea ice / Re: The 2019 melting season
« on: June 25, 2019, 02:13:53 AM »
Looking ahead to the next week, the models are suggesting that the relatively cooler temperatures over the Barentz and Kara seas over the last week will shift to above normal temperatures.
This the forecast surface air temp anomaly from GFS for next Sunday the last day of June:


32
Arctic sea ice / Re: The 2019 melting season
« on: June 24, 2019, 09:08:35 PM »
How did the D8-D10 forecasts that were posted here 5/10/15/20/25/30 days ago pan out?
Was just looking. Tropicaltidbits.com makes it super easy to compare forecasts from 7 days ago with the current initialization.  A week ago (top pic), ECMWF predicted a 1033mb ridge off the ESS; today they're initializing at 1028 in the same place (bottom pic).  A pretty good forecast!  However, the huge 1040+ high that the 8-10 day forecasts had put over the central Arctic has been lowered dramatically in the new forecast runs.  Both EC and GFS have it more elongated from ESS toward Greenland and about about 1032mb, with small lows in the CAA and deeper low in the Barentz. So thankfully not the basin dominating super-high that was predicted, but still should have lots sun and still quite a bit of export to the Atlantic I think.


33
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 09:04:12 PM »
Looking that the 12z operational model guidance, it seems very likely to have a 1030mb surface high in the ESS region over the next few days, along with a persistent low in the Kara Sea area.
The question is whether the huge 1040mb high develops later on, and if that low stays positioned to push a lot of ice further south in the Atlantic. The ECMWF Day 6-10 forecast certainly looks to me like it would be a disaster for the ice if it verified. Here's Day 2 (highly likely).

34
Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 11:56:27 PM »
Regardless of the fires, that Worldview shows well the north-to-south dividing line between warmer than average airmass (east/left of the N-S cloudbank toward the Bering) and cooler (west/right toward Europe). 

35
Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 03:03:16 PM »
Really? I am feeling the EC forecast has become pretty variable even at three or four day... maybe just a feeling. The overall picture, run to run, is quite turbulent.
Yes, I see your point. I should have used the word stationary (implying location) rather than stable (implying run to run forecast stability) in my post. Of course, the models will flip flop around at that time range. But I think the signal is strong enough to be worth watching.

36
Arctic sea ice / Re: The 2019 melting season
« on: June 18, 2019, 08:51:07 PM »
Two things of interest looking at today's model guidance for the next week. First, that new low that enters the Arctic from central Asia is projected to scoot very quickly across to the Canadian archipelago. Second, the persistence of the high pressure over the East Siberian sea -- GFS has it lasting into July (!) and ECMWF 12z operational shows the high continuing to build out well over a week. (Usual caveats that 5-10 day predictions not necessarily reliable etc. etc.)

37
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: June 11, 2019, 06:56:40 PM »
Noticed prediction for very warm temps across most of Greenland this week.  Jet stream his highly N-S and very wavy across N America today.

38
Arctic sea ice / Re: The 2019 melting season
« on: June 01, 2019, 12:45:53 AM »
Looks like the Mackenzie river water is just starting to hit the fast ice at the mouth of the delta. Looking at past years on Worldview, this doesn't look too much earlier than usual for the 2010s, but seems clearly earlier than usual for 2000-2010s. Top pic is May 31 2019 (today) bottom pic is June 1 on the year 2000 (19 years ago).


39
Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 03:17:09 AM »
Subsidence is a pretty useful precise term in meteorology. Would you also complain about a pilot using precise jargon like "elevator" or "horizontal stabilizer" or "trim" to explain an aviation concept? If you want explanation using layman's terms, feel free to ask, preferably in a different thread. This thread watches the ice and the weather etc. Mackenzie delta.

40
Arctic sea ice / Re: The 2019 melting season
« on: May 24, 2019, 01:14:49 AM »
This river delta in the general area of Prudhoe Bay on the north slope of Alaska appears to have started spilling water into the ice of the last couple days.

41
Arctic sea ice / Re: The 2019 melting season
« on: May 01, 2019, 03:04:37 AM »
This was ECMWF's forecast for tomorrow from 7 days ago.  Pretty similar to the setup we're actually expecting tomorrow, with strong high pressure from the Beaufort coast to Greenland, and low pressure in the Kara Sea area. I know the models are often wrong, but they are also often right, at least out 7 days.

42
Arctic sea ice / Re: The 2018 melting season
« on: August 26, 2018, 11:15:21 PM »
Here we go again with the weather forecast.

The last big storm predicted in (some of) the model forecasting didn't verify. However, the prediction of stormy weather and windy conditions spanning much of the central Arctic seems fairly robust. I will be interested to see if the wind and waves finally dissipate the fragile looking ice throughout the ESS and toward the Beaufort.

43
Arctic background / Re: USCGC Healy: scientific missions to the Arctic
« on: August 20, 2018, 02:08:08 AM »
Rain and ice

44
Arctic sea ice / Re: The 2018 melting season
« on: August 13, 2018, 10:44:43 PM »
On the Pacific side, it will be fun to watch the Healy, now at 71.6n and headed north. Water temp 6.8C
http://icefloe.net/uscgc-healy-track-map
http://icefloe.net/Aloftcon_Photos/

45
Arctic sea ice / Re: Latest PIOMAS update (August)
« on: August 12, 2018, 03:19:50 AM »
Ultimately, volume is the single best metric. We should have a poll. This will be one more poll in which I will never participate

Whether volume, extent, or area, I think these 365 day trailing averages are the most useful statistics for explaining sea ice loss.

46
Arctic sea ice / Re: The 2018 melting season
« on: August 09, 2018, 11:50:55 PM »
As the high pressure slides east along the Siberian coast, low pressure builds in, mostly following along the coast from the Atlantic side. That should bring lots of southerly winds, first in the Laptev area, eventually in the East Siberian sea. If we believe ECMWF, winds could be quite strong, pushing scattered ice mostly toward the central main pack I think. After a few days, the EC model deepens the low down below 980mb for a couple days, which could really stir things up. We'll see!


47
Arctic sea ice / Re: The 2018 melting season
« on: August 08, 2018, 03:44:56 AM »
This setup would seem to greatly expand the Laptev bite!  Important hedge, the ECMWF, often best in the 5-7 day time frame, isn't nearly as amplified.

48
Arctic sea ice / Re: The 2018 melting season
« on: August 07, 2018, 04:30:06 PM »
Here's my dumb (but verifiable) prediction for five weeks from now.  Assuming a lot of this late-season heat on the continents continues to work it's way north and a mostly sunny regime on the East Siberian side.

Did I measure this correctly?

As noted above, I think lots of ice will survive in the CAA also, but didn't include that in my highly scientific forecast!  There are also a lot of very large floes outside the red line in the direction of Alaska, so some of those will count for extent and area in the final tally.  I was just mainly sketching the highly compacted central area!

49
Arctic sea ice / Re: The 2018 melting season
« on: August 07, 2018, 02:02:53 AM »
Here's my dumb (but verifiable) prediction for five weeks from now.  Assuming a lot of this late-season heat on the continents continues to work it's way north and a mostly sunny regime on the East Siberian side.

50
Arctic sea ice / Re: The 2018 melting season
« on: July 14, 2018, 02:19:12 AM »
Worldview pics of the Wrangel Island area and coast from June 22 (top) and today (bottom). Today's image was quite clear after many days of clouds and smoke.


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