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Messages - aslan

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Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 23, 2020, 03:18:35 PM »
Mercator's take on SST's.
amsr2, awi dev v103 overlaid onto mercator 0m ocean temperature, sep4-oct22  (7MB)
Ok, from your animation is it correct to say all the regions susceptible to warming from Atlantic Waters are already covered by ice or about to be covered? (exception Barents and Kara but we know those two seas are already lost to climate change)
It seems to me the anomalously warm Laptev and ESS areas are basically over the shallow shelf, which will have a record heat release (consistent with the record heat income from GAAC and the season in general). So no Atlantic warmth here to speak about.

The Laptev sea extent beyond the shelf (and so the heat anomaly, by the way). Intrusion of Atlantic waters are discernible on the salinity maps of the mercator. (P.S. : And acknoledging that the heat and salinity extent beyond the Laptev into the central bassin, even under the sea ice).

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 23, 2020, 03:15:23 PM »

Have you seen the snow extent growth over Siberia and Western Canada? Anything to comment or you only rejoice on the bad feedbacks?

Apart from this, the weather is about to become propitious for a quick rebound of sea ice next week.

Speaking of a great peril does not sound too much like being merry and joyfull... And for the snow extent, it is no news that late Autumn snow extent is not showing a significant decrease lately. It is even more the case this year. But this fact has not prevented ongoing anomalous warmth up to now. Which is still this case this year, as temperatures are still above normal overall in Siberia, no matter the snow extent. And for the quick rebound in ice extent we will see.

Can that be set for a narrower palette gamut (called squeeze at WorldView vs outlier clamp at CMEMS)? The bins are too large to resolve temperatures in the -2 to 0 and 0 to 2 ranges on the last frame of Nov 7th. The shoreline color seems off, not clear what temperature it is. Overall it does not seem that unreasonable: very little advance in the ice pack but with the stage still not set for rapid closure with so much open water between 0 to 2ºC.

There is also the SSTs from the coral watch of the NESDIS :

Same picture, Laptev and even more Chukchi sea are not going to freeze tomorow...

Top level directory of the files are here :

And the direct link for this year :

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 23, 2020, 08:41:20 AM »
What I am trying to bring up is that extent by itself is only an indication of when ice thickening can possibly begin, and with the current extreme delay in the Asian sea ice extent, the ice growth in thickness is being delayed. While historically some areas of the Asian seas have had slow growth in extent, 2020 is the first year on record (as far as I know) that will likely still have an ice free NE passage on Nov 1. (And not just dodging ice, but wide a open sea lane.) The fear is that if this continues much longer even with eventual universal 100% extent on the Asian side, that first year ice will not have a chance for a 'normal' gain in thickness. Instead of >1M ice, much of the Asian sea ice could end the freezing season in a very fragile state leading to much earlier breakup and melt in 2021. Already basically the whole of the Asian side has lost a month of thickness growth, where in previous years a fairly large percentage of those seas had already started that growth.

It is a rough estimate, but if you use the correlation of Freezing Degrees Day (FDD) with ice thickness, you need ~5500 FDD to go to 2m first year ice, and ~3500 FDD to go to 1.5 meters. October is usually worth ~300 to ~400 FDD in the Arctic, so it can make a significant dent into the ice growth.
To give some more numbers, for Ostrov kotel'nyj for example. Mean temperature from 1st of October to 30th of April over the last 10 years (2010-2019) was -20.8°C, which is about 4400 - 4500 FDD. If you count from the 1st of November, this leads to 4100 - 4200 FDD. And if you ignore November and start the ice thickening the 1st of December, it makes only 3800 - 3900 FDD. This is ignoring the risk that oceanic heat flux could be strong enough this winter to weaken this correlation. If ice growth does not start in a hurry on the Siberian side, the winter would probably not be able to fully erase the memory of this melting season. Which is a great peril, as up to the last years, winter was always cold and long enough to at least bring Arctic back to some kind of a "2m FYI" state, helping to stabilize the system.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 21, 2020, 06:39:45 PM »
After the storm of this mid October I was also wondering myself what are the consequences of the open water on synoptic forcings for ascent. As a remainder, vertical velocity are stronger for a same forcing with lower static stability. I don't know if there is studies about this subject, or if it is a significant effect, but it is an open question for me. This is probably linked to the displacement of the eddy driven jet, but I am not aware of any study really looking specifically at the consequences of this reduced static stability. This is also leading to higher wind speed at surface, as seen with the last storm. On top of that, strong inversion over ice pack, and now over the continent, is on juxtaposition of this low static stability, leading to increased baroclinic instability. But what is the magnitude of this effect ? I am really clueless. To illustrate, I have compute a crude static stability parameter, by subtracting potential temperature at 700 hPa and at 950 hPa, normalized by the thickness 700 - 950 hPa. All of this multiplied by 10 to better seen what is going on. Below 0, the atmosphere is superadiabatic, and everything above is subadiabatic. Over mountains (like, said, the Rockies...), results are of course useless, as the model interpolate trough the terrain. Maps are for, in order, the 21st to the 24th at 00Z. Didn't try to average trough time, the computer would probably have hoist the white flag before the end... We can see a persistent area of low stability over the Siberian seas.

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: October 21, 2020, 06:47:10 AM »

Almost half a million km2 less than 2019 and more than a million km2 less versus 2012, 2016 and 2007!  :o

This said, in 2007 at this time of the year, we were about 1.0 to 1.5 millions km² below the previous daily record, 2005 (something like 6 to 6.5 millions km² in 2007 versus 7.5 to 8 millions km² in 2005).

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 19, 2020, 03:59:11 PM »
For what is worth (not much, admittedly), but the surface analysis of GFS (the GDAS) did not show a significant drop for SST during the week-end. The image is the difference of surface temperature (sea or land) between the 19 at 00Z and the 15 at 00Z. Over land, there is definitively nothing to analysis. However, for SST, even though not too much weight has to be given, it is still showing something. Surface analysis even show some patches of more than 1°C rise in SST. But what all this show is that the storm did not lead to a massive drop in SST.

P.S. : Better image this way

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 15, 2020, 05:41:55 PM »
I think it is worth remembering we are living on Earth not Mars... We have a layer of gas above ours heads which is not transparent to IR. Even in the old, dark, dry Arctic of the past it was impossible to radiate an infinite amount of heat to space. There is always an upper limit. A temperature inversion in the low layer, even in Siberia in the 1880s could not have been greater to ~ -25°C. At some point, even in an absolutely dark and dry Arctic a point of equilibrium will be reached. And on top of that amount of heat lost to space is not primarily a function of the temperature at surface, it is not the case, definitively. The temperature at surface is not totally decorrelated from the heat lost to space of course. But there is an atmosphere above surface, in the end. It is Earth here, not Mars... Heat has to go trough the atmosphere before, and there is on the road CO2, CH4, H2O in every states possible, etc... And now that Arctic is providing a lot of heat and moisture, we are seeing a new state where there is a layer of clouds and moisture in the low layers which is isolating the surface, with temperature between 0 and -5°C at 2 meters versus -20°C to -30°C at 2 meters in the case there is no clouds.
Holy mother of Einstein, it is Earth here, not Mars !
The picture which follows is the forecast for Saturday for a given model. It is the minimum for the temperature of brilliance in infrared (10.8 microns) for the all day. Scale is from blue for the warmest (~0°C) to white (~ -40°C) going trough the brown / beige / I don't know which color (-10°C to -20°C). There is also the isolign for the surface temperature of -2°C to roughly approximate the edge of sea ice (more or less, we all see what the shape of sea ice currently). Over Beaufort, yes we are radiating at 0°C (blue color) and we are losing heat to space. But over Chukchi, ESS, Laptev, Kara, Barents, we have a layer of clouds as thick as the troposphere. And the temperature of brilliance is -20°C to -40°C. The temperature of brilliance is more directly correlated to heat lost to space than surface temperature. This really means, this really means, that during the storm, we are not going to radiate heat toward space at ~0°C from the ocean. We are going to radiate heat at -20°C or -30°C or -40°C. And there is a factor 1.5 to 2 between the radiation from a black body at 0°C and a black body at -30°C or something. The heat stirred by the storm is heat at ~0°C, the heat lost to space is heat at -30°C, and there is a ratio of 1.5 to 2 between the two... I made the same map but with the mean of the IR temperature from Friday to Thurday. The ice sheet is high and dry, radiating at -30°C and isolating the ocean at 0°C below. The Beaufort is, yes, a good heat sink fully radiating toward space. But for the siberian side, the clouds are here as the ice sheet, isolating the surface below. Even with a mean over 5 days, almost all the siberian side is forecasted to be isolated.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 15, 2020, 03:41:17 PM »
There's always been enough incoming heat to melt all the ice, the issue has been meager re-distribution by double diffusion staircases prior to export back out the Fram. However the downward trend in sea ice has brought a change-over from atmospheric to marine dominance of the energy balance.

As the buoyancy gradient (thermohalocline) begins dissipating from more shear and turbulence attributable to more open water resulting from sea ice decline, the heat brought nearer to the surface just leads to more sea ice decline, a runaway positive feedback that the authors see as immune to climate change mitigation efforts.

Not sure how that works.

Let's take this weekend as example. Strong winds are going to pull some (or a lot) of heat excess to the open ocean surface, which is continuously going to be released to the atmosphere (much colder than the ocean surface) and to the space. It is not going to lead to more sea ice decline, since in the following days darkness is an almost infinite sink of heat excess until next Spring. So this weekend is going to lead to less heat stored beneath.

Where in the preceding paragraph am I wrong?

The Arctic in winter is not an infinite heat sink. Definitively NOT. There is a thing names moisture and another names cloud which is in play,

and there is also the fact that heat builds up in summmer in Arctic, and the heat transported from the tropics - a region where the bilan is strongly positive - etc. Arctic in winter is not an infinite heat sink. And never was one by the way. It is not a proof, but just look at the correlation between Nh and T at Ostrov Vize here for example :

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 15, 2020, 10:50:59 AM »
This is the second mentioning of "shoaling" in recent days, see also A-Teams post above:

Weakening of Cold Halocline Layer Exposes Sea Ice to Oceanic Heat in the Eastern Arctic Ocean
IV Polyakov, T Rippeth et al
J. Climate (2020) 33 (18): 8107–8123. free full

"The upward release of AW heat is regulated by the stability of the overlying halocline, which we show has weakened substantially in recent years. Shoaling of the AW has also contributed ...

I understand shoaling to mean what happens to waves as the approach shallower water (shoals) . According to Wikipedia shoaling happens when depth is less than half the wavelength.

Other meanings are "becoming shallower" and also when aquatic organisms group together (e.g. a shoal of herring).

So how does that fint into the bigger picture of an open ocean as Aslan seems to talk about, and what is meant by a phrase like "shoaling of the Atlantic Waters" as in the paper quoted by A-Team?

Err I am not really good at speaking english. AW are below the halocline. With waves, mixing weakens the halocline and allow heat transfer from the AW. For me shoaling means that AW are "less deep" and nearer to surface, with increased heat flux.

For the baroclinicity, I have added the vorticity (blue, positive, and red negative) and T'w in black. We can see that near the surface, the strong inversion is associated with the gradient in wind speed. This also creates shear and then vorticity. We have, as usual, shear zone and vorticity to the left and right to the LLJ, but near the surface there is also vorticity associated with the shear zone at the interface between sea ice and open ocean. But the max of vorticity over sea ice in the lowest 500 meters is really linked to the interface between sea ice and open ocean, it is not linked to the shear due to the deceleration of wind speed.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 15, 2020, 09:57:15 AM »
This means a stronger broclinic zone, with more clouds and moisture keeping the Arctic warm, and it means a weaker halocline with more mixing and shoaling of the Atlantic waters. By the way, even though the anomalies of temperatures are less extreme, the islands of the russian arctic are still running for the hottest month of October in record from the Barents to the East Siberian sea :

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 15, 2020, 09:09:55 AM »
On top of all the retroaction already described, there is also the fact that an open ocean generate less friction, and the lack of an inversion increase even more the wind speed at surface. This is visible for the storm of Friday and Saturday. The low level jet brings stronger winds at surface over open ocean than sea ice. The cross section is from south to north, trough the low level jet for Saturday at 12Z. Higher wind speed reached the surface open ocean.

P.S. ; One important point... For the map, it is wind speed at 500m, not surface. There is two LLJs, one over sea ice and one over open ocean, but strong winds at 10m are only found over open ocean.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 09, 2020, 08:16:46 PM »
It’s not that it is good. It is that there are physical reasons (Stefan-Boltzmann Law) to expect that the more energy you make available now, the more energy will radiate out to space during the NH night.

It's you who are confusing the whole thing. Plank feedback (function of T^4) is well known but others feedback also: lapse rate, water vapor, clouds, etc. Overall, climate sensitivity is 3 degres to doubling co2. Nothing new. With your reasoning, more co2 would mean a cooling earth. Open arctic in winter is stable state. Point in case: barents and bering sea, kara sea in 2012 and 2016, likely laptev sea winter 2021. You are pushing this topic off road with unbased statement. Open arctic in winter is definitively not a giant radiator cooling down the earth. It is a stable system from an energy POV.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 08, 2020, 02:41:55 PM »
Yes, Arctic was ice free many times in the geological time. It is true that loosing ice cover in winter would in theory implies a massive heat loss by longwave radiation to space, but things are not as simple as "If I pull out your blanket, you are going to freeze to death.". And there is over factors at play. This discussion will lead us off topic if we continue, but an ice free Arctic means also a complete reorganization of the atmospheric and oceanic circulation.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 08, 2020, 02:25:37 PM »
This article pretty much ignore clouds or overall atmospheric circulation, or anything else, and is just saying that if you remove sea ice, a lot, lot, lot of energy will be radiated to space in winter. Yes of course, nothing new. But it is likely that things will not proceed as linearly. Studies and measures are showing that it seems likely that open water during fall and winter is going to destabilize the PBL. Implying more clouds and moisture, which is going to limit the amount of heat lost to space. And atmospheric circulation, and oceanic circulation, and etc... are also going to respond to an ice free Arctic and establish a new equilibrium which is definitively not going to be the same that "all else equal excepted for sea ice".

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: October 08, 2020, 01:33:38 PM »

Both the ESS and the Laptev sea ice extent are at record lows. Perhaps of the greatest interest, given the high heat content of the sea, will be how long before the Laptev re-freeze happens, and how quickly.

Small quibble, but in 2007 ESS area and extent was even lower. And this metric bottoms out lately, the 3rd of October. But we are not far away (25 000 km² for area, not zero but almost) and still loosing ice. But overall, the Russian side (ESS + Laptev + Kara + Barents) is at a record low, and still loosing ice, which is pretty impressive.

P.S. : Graphs made in a hurry... (and, it is the same idea with extent by the way)

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 06, 2020, 12:41:40 PM »
To illustrate, a set of graph for the period August - Septemeber. Record for Gmo Im. E. K. Federova, breaking its record by 2.2°C (cap Tcheliouskine),or 3.5 sigma above the most recent 30 years mean... And there is ~ 1500 km between Heiss (Polargmo or wmo 20046) and Hatanga (20891), which squared is ~ 2 millions km²

Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 06, 2020, 11:59:06 AM »
Not sure if this is autocorrelated with the current low extent but the temperature anomaly forecast in the arctic and especially siberian seas is extreme, hovering around +15C.
Keep in mind the image below is the forecasted 10-day average. Usually you'd see quite low anomalies on such a map because such long term forecasts tend to go up and down and thus even out the average. But now the forecast just stays red hot in the ESS and Laptev for the entire 10-day period without pause.
Laptev-ESS seas venting out their energy excess?

I would expect an acceleration of refreezing around the pack this week in view of Freegrass animations, but it is difficult to say.

I doubt it. There is still a massive amount of oceanic heat and it is still looking like the halocline has taken a hit. And massive heat wave is still ongoing, no matter the temperature at 850 hPa. And this is not only a matter of absolute magnitude of the anomaly. October is probably going to be less extreme than September from a certain point of view. I mean, in term of deviation to the norm, the month of September was probably the most extreme month ever recorded anywhere on earth, no exaggeration. Ostrov Golomyanyj (data since the 30s...) has broken its monthly mean temperature by 3.3°C ! Ostrov Vize by 1.6°C after breaking the monthly record of august by 2.3. Same idea for Kotel'nyj, Izvestij Tsik, Dikson, Heiss (Polargmo), Hatanga etc... As an illustration, September mean temperature for Ostrov Kotel'nyj (WMO 21432). I have never heard of a heat wave so extreme over a two month period, and this is over an area of 2 millions of km² or something like that. Even though October will be extremely warm, such deviation is not likely in October (hopefully…). But in any case, there is really something ongoing on the Atlantic side. It will take more than a week of seasonal cooling for resorbing these anomalies.

Arctic sea ice / Re: The 2020/2021 freezing season
« on: September 25, 2020, 09:26:00 AM »
Well. With Mosaic basically proving that the best piece of ice in the best position on the Atlantic side of the Lomonosov ridge LOST thickness on its entire transit from October to may, from 7m to 5m, through constant bottom melt, and never froze it's soggy core. And now that they can cruise at open water efficiency, from laptev to Fram north of 86 latitude, and never register any fresh freezable layer...
 There appears to be no such thing as a Arctic sea ice freezing season anymore in this half of the Arctic basin.
Therefore I suggest a poll to rename this forum the SiAlCa sea ice forum. Hopefully there will be a few years while those elements hydrated minerals can still stay cold enough to remain solid on those sectors polar seas. Unlike Venus.
Wry and somewhat twisted that this bad half joke may sound.

On the Atlantic side, it is looking like that the halocline has taken a serious hit. And the weather is totaly nuts on the russian islands. As of the 24th, the record of the most crazy anomaly is probably for Ostrov Golomnjannyj. The current mean temperature, 4.7°C, is 4° (!) above the old record of 2012, and even 2°C above the warmest month ever recorded, August 1932. Every day have broken their daily record, 15 days had a Tx above the old monthly record, and even one Tn was above the monthly record of Tx... And all of this with 71 mm of rain (and I mean, really rain, liquid water at 5°C), wich is more than three time the normal monthly precipitation amount. From Ostrov Heiss to Ostrov Kotel'Nyj, crossing Khatanga and Ostrov Vize, mean monthly temperature are going to be 2 to 4°C above previous record, and going to be more than 3 sigma above normal. Seing such and anomaly over such an area (we are speaking of something like more than 2 millions of km² or 0.5% of Earth surface) for a monthly mean is unprecedent.

Arctic sea ice / Re: The 2020 melting season
« on: September 17, 2020, 09:42:24 PM »
It's not just a SST thing in the Barents, Kara and Laptev seas. The heat goes town to 30m or more. Compare the 30 m Arctic temperatures of this year with 2019 on Mercator ocean and you will see that there's much more ocean heat on the Atlantic side this year than last. On the other hand, there's less heat on the Pacific side. Over both sides, there's much more heat this year, but there is almost always a see saw effect in the Arctic between the Atlantic and Pacific.

It is too bad we don't have buoy. With melt still ongoing noth of 85°N it is looking like that the halocline has taken a hit and Atlantic layer is pushing upward. Salinity at surface is higher than in 2019 also, implying a reduced stability. The high salinity is also to be compared to the high freshwater input this year.

Arctic sea ice / Re: The 2020 melting season
« on: September 15, 2020, 08:39:22 AM »
As a testimony of the disruption ongoing on the Atlantic front, the extraordinary heatwave is still ongoing for the Russian islands of the Barents and Kara. For weather stations with such a long record, this is crazy. Up to the 15th of Septembrer, the mean of temperature (the mean...) is above the old monthly record of September. And it is raining, raining, raining.
For Ostrov Vize, with the exception of the 10th, every day since the 14th of August is a record, and the old monthly record of 2015 has been broken twelve days as of now... The month of September is for the moment the warmest month ever recorded, ahead of August 2020
For Ostrov Golomjanjy, every day of September has been a record, and the old monthly record of 2016 has been broken eleven times.

Arctic sea ice / Re: The 2020 melting season
« on: September 03, 2020, 09:14:40 PM »
While the weather forecasts for storms entering the arctic have been incorrect or overly optimistic, what is impressive to me is the current weather history of strong winds blowing north from the laptev/kara shores over the ice (and the fact that these were present in the forecasts 5 days out for the last 10 days at least. That length of time for a consistent 20-30+km/hr wind over the very open arctic ocean and into the ice edge has built up significant wave height that must be propagating some distance into the ice.

The only source I know of that provides an actual indication of wave close to the ice edge indicates 5-6 ft with 5-6 second period - not long swell so not as destructive to the ice behind the edge.

The forecast continues this wind through the next 4 days.

It is the Arctic Ocean here, not Hawaii. Even though I understand what you mean, even a 6 second period is quite significant for the Arctic. I think I have never seen a wave period greater than 10 seconds in the Arctic basin proper, even in 2012 or in 2016 (not counting the Kara sea were some long swells from Atlantic can be worst, of course). On top of that, wave period is probably going to be higher. I am not sure where you draw your values, but for now the forecast is for a wave period of at least 6 to 8 seconds. The strongest winds are likely to be over ice, but even in this case the fetch will probably be quite enough for this kind of value.

P.S : For ones who like esoteric diagramm...

Arctic sea ice / Re: The 2020 melting season
« on: September 03, 2020, 08:38:23 AM »
August 29 - September 2.

The tail is melting quite fast!

And it is not over yet.

Again, about the GAC during the month of August 2012, the minimum pressure was quite low, but environmental pressure also. And winds are function of pressure gradient, not pressure. The IFS this morning is going down to 974 hPa. But, there is an anticyclone over the coast, with pressure up to almost 1025 hPa. In 2012, pressure along the coast were around 1010 hPa. Going from 1010 to 965 hPa is about the same (45 hPa of difference) than going from 1025 to 980 hPa (45 hPa of difference). Admittedly, total kinetic energy was greater in 2012 than what is forecasted for Monday, but overall a 980 hPa low embedded in a 1020 hPa high is able to do a lot of damages also. To illustrate, the wind in meters per second analyzed by GFS at 00Z the seventh of August 2012. Maximum winds are around 30 kts (15 m/s), which is also maximum winds forecasted by models on Monday. Again, the GAC of 2012 was probably worst with a greater total kinetic energy, but overall the absolute minimum pressure of a low is quite not the full story. This is going to be a really rough ride and it is really bad, even though we are more than 10 hPa away of the lowest pressure of the GAC 2012.

P.S. : Did not see that at first glance, but IFS 00Z is pushing above 40 kts at surface on Monday 12Z O.o ouch...

Arctic sea ice / Re: The 2020 melting season
« on: September 01, 2020, 04:05:19 PM »
Today's images and slow animation (slightly larger version on twitter)...

The drop in concentration in the Beaufort in the last 24 hours is somewhat concerning.

Easterlies and waves are probably hitting the Beaufort sea. Winds up to 30kt from the east, for the southern part of the arm of ice :

And models are showing waves of up to 3 meters with a period of up to 7 seconds. It is not the big washing, but way enough for some floes to go "poof".

Arctic sea ice / Re: Updating the ASIG
« on: August 25, 2020, 09:10:27 AM »
I've updated the Forecasts page, as none of the images were working. Unfortunately, there aren't any good SLP forecast maps out there, either GFS or ECMWF. Tropical Tidbits has a good one, but it's for the Northern Hemisphere, so you can't see much detail when it's in the size I'm using for the Forecasts page. So, I was forced to use to the Climate Reanalyzer MSLP/Precipitation map which lacks the geopotential height colours for a quick glance.

Oh, well...

I'm a bit late, but have you consider this site ?

Arctic sea ice / Re: The 2020 melting season
« on: August 25, 2020, 08:54:26 AM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!
It’s funny how the big storm over Greenland Gap never gets to fully realize
It's been like that for over a month now, where big apocalyptic storms get announced on the long term forecast, but never materialize.

GFS really needs to find a way to improve their long term forecast. Or just stop making them, because this is useless...

Models don't work this way.

For Franz Josef Land, record high temperature for the last decade of August, record high daily rainfall and near record gust speed for August :

Old value : 16 mm in 24h (August 89), 5.5°C (August 2019 and August 1978)

P.S. : And there is a ~500 km gap between WMO station 01011 (Kvitoya) and WMO station 20046 (Polargmo Im. on Heis Island - Ostrov Kheysa). The worst of the storm on Sunday and Monday was in this gap.

Arctic sea ice / Re: The 2020 melting season
« on: August 22, 2020, 12:15:57 AM »
And, as an illustration, 63.4 millimeters of rain in 1 hour at Sandefjord Gjekstad, highest hourly rainfall rate for Norway. Old record was 54.9 mm in 1 hour at Asker. The thermal wave, consequence of Kyle and Ellen, is by no mean a joke. No matter the exact to the nearest decimal of the min pressure for the North Pole, this is going to be bad for the atlantic front.

Arctic sea ice / Re: The 2020 melting season
« on: August 20, 2020, 01:49:10 PM »
It is not useful to look at exact number for weather forecast. This is why there is the feeling of coin flipping. That the models go back and forth for exact min pressure at the nearest hPa or max surface wind at the nearest km/h is normal and should not be confusing the forecast. Models are still a bit unsure about the deepening of the low, but in any way and in any case, a wave in the frontal boundary from the complex low linked to ex Kyle, now storm Ellen, is going to deepen. The details of the exact minimum pressure and of which exact wave in the front and of the exact km/h of the max wind and so on are not really relevant. We can be 100% that a low is going to deepen from a wave in this complex, and that it is going to be a wild ride for the Atlantic side. And the ranges of some physical parameters are not going to evolve in the coming days. Precipitable water is forecasted to reached 25 - 30 millimeters in the warm air advection and this is not going to change, strong winds of 30 - 35 kts are also a sure thing, I am ready to bet on thunderstorms northward of the 80°N also, etc... That the low go to the 970s or stall in the bottom of the 980s hPa or that lightning strike will be here or there is asking too much, and is not really the biggest question. The difference between a 980 hPa low with 34 kts of wind and 29 mm / 24 h of rain at max, which develops from this wave, or a 975 hPa low with 36 kt of wind and 31 mm /24 h at max which develops from that wave, is not significant. Weather forecasting is not reading model outputs and going back and forth with them. This is going to be a significant event for the Atlantic side, with the injection of tropical moisture from Kyle, and with implications for planetary rossby waves train, no matter the exact unit of this or that parameter.

Arctic sea ice / Re: The 2020 melting season
« on: August 20, 2020, 09:50:19 AM »
silly question .. would the weather models have any concept of how wet the ice is atm ? If they see it like piomass sees it they may be surprised by developments .  b.c.

No they don't, sea ice is parametrized in the models with fixed constants. It would be way to complex to explicitly model the sea ice for a weather model running every six hours. And yes, models can be underestimating cyclogenesis, which is no news. But this is not only a problem with sea ice. Cyclogenesis is a complex process and is hard to forecast. But in the Arctic, with all the changes ongoing, this is worst, yes. As a side note, models are again forecasting explicitly thunderstorms above the boundary layer on the Atlantic and Pacific side. I did not fully check the models from 00Z today, but IFS or ARP are going on for over 30 millimeters of rain (and rain, no sleet or snow) in 24h for Franz Joseph Land this week-end ! This is crazy. And even up to 85°N, they are going with thunderstorms and a good 20 mm per 24 hours. Sea ice on the Atlantic side is going to be wash out.

For Beaufort Sea, as already said, the warm air advection on the flank of the anticyclone is going to be bad. Even though there is no deep low, there is enough pressure gradient for some significant winds (field of 15 - 25 kts), and with the help of Coriolis, with the fetch of open waters, etc... Waves are going to be pretty significant for the Arctic, from the south east to the south (wave period up to 6  to 8 seconds). This not a big event, but again locally and given the sore state of sea ice in this corner of the Arctic, and the fact that there is a lot to loss, etc... Beaufort Sea is likely to continue its nose dive in the coming days.

Arctic sea ice / Re: The 2020 melting season
« on: August 03, 2020, 12:21:34 PM »
Sorry I don't have the mean to fully exploit the dataset for MERRA reanalysis, but as an illustration. For June, net surface shortwave (~ solar) flux was high, but not as high as in 2019. Last year was quite extraordianry from this point of view. The first map is for 2020, the second is for 2019 and the third is the difference, 2020 minus 2019. We will see what did happened in July (MERRA data are available around the 20th for the preceding month).

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 04:40:10 PM »
It can be noted also that there is a surge event ongoing for the northern coast of Alaska. I don't have knowledge of a station measuring waves height for Arctic coast of Alaska, but at least there is a surge of about 0.5 meters since the 27th of July at Prudhoe. Waves will pill up above, and as sea level is already high, tops of waves reach even higher level. As a side note, waters levels at Prudhoe are higher than in 2012. In 2019 waters levels were even higher than, now, but were not as long lasting.

Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 07:42:05 AM »
About wave activity, it can be noted that Indian Ocean was a strong source until lately. Pacific convection was a bit muted, but a dipole dominated over Indian Ocean, and a stationary MJO stucked in phase 2- 3 in June and July, with propagation of a wave train over Pacific and a reinforced subtropical jet here. But what is really curious is the strong source of wave activity from Arctic. I mean, I really don't remember seeing such a source independently from the mid latitudes and tropics.

Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 09:06:58 AM »
Ok correction, 978 hPa at 144 hours... Come on Brive ! XD Forecaster widsdom, when the IFS is stable and going stronger step by step and hPa by hPa, follow the trend. Again it is not a GAC but the cyclone is going to destroy the last stronghold of this year, the Beaufort sea. We are really going to go trough the floor.

Lol wow... yeah, tonight’s Euro would be disasterous for the Beaufort. I don’t think the previous run with  the 980mb was too terrible. Pretty transient with some rain and warmth briefly pumped in, but not persistent enough to make a huge huge impact in the Beaufort via wind and waves imo. Most of the relentless warmth would’ve been over the CAA. Certainly wasn’t trying to argue it was good though, just worth watching. And now even more so for sure!

Tonight’s run would be bad bad bad news.  Relentless wind and waves pulverizing the sea ice and rubble for days. Some are overestimating the Beaufort ice, considering it a stronghold this year. But it looks terrible on satellite and the concentration maps.  A storm like this would absolutely wreck it.

Yes ;) I agree with you, to be precise I said stronghold, but it was more exactly to say that it is where there is still lot of ice, and so huge losses possible. But yeah, Beaufort sea ice is weakening and is not looking especially "strong".

Arctic sea ice / Re: The 2020 melting season
« on: July 23, 2020, 08:05:06 AM »

4. Will a strong cyclone develop on the Pacific side? Right now both the GFS/Euro are forecasting a 980mb LP on day 5. The storm doesn’t look too terrible, but if a bigger/stronger/persistent cyclone does develop in this area that would be trouble for the vast amount of vulnerable ice/rubble in the Beaufort.

I kindly disagree, the forecast is looking incredibly bad for Beaufort sea over the end of the week-end. The cyclone which was forecasted to try to bomb out from the Laptev sea fizzle out, but now the machine is running full steam ahead. Each minima is pumping warm, moist air from the continent, and in the front a new low developps and push air pressure lower and lower. We are going for a persistence of cyclones rotating over Beaufort sea. IFS 12Z is reaching 980 hPa at H+120, we will see the 00Z but this is definitively a bad setup. It is not THE big one, but action will take place over Beaufort sea and act to disper sea ice here. On top of that, we still have convective instability above the boundary layer with high rain rate, locally up to 15 - 20mm in 6 hours. The washing machine is on.

P.S. : I didn't see answer from Friv' but I agree with him. And the 00Z of the IFS is still going down to 983 hPa...

Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 09:08:29 PM »

The IFS did remember what a thunderstorm of the free atmosphere means. No surprise here. Fasten your seat belt we are going for a wild ride for weather forecast -& probably for sea ice also-. Anticyclone are so anoying, now it is time for real weather forecast and putting balls on the desk :D

Arctic sea ice / Re: The 2020 melting season
« on: July 17, 2020, 01:56:44 PM »
As Friv pointed out, there is lifting occuring from the warm air coming from the siberian coast above the boundary layer. It is becoming a new normal, but still on the scale of weather craziness this easily reached the batshit crazy level... Soundings are the ones forecasted from IFS 12Z (cf. the picture from wetterzentrale) over ESS and Laptev, in the ridge of warm Theta'w. If the forecast verifies as it is, this means thunderstorms. This is also probably adding instability to the forecast.

Sorry for quoting myself, but this is really going to be an important point. There is a first low east of Taymyr and Severna Zemlya, from now to H+120, going down to ~995 hPa at 72h - 96h. This first low is going to bring a massive surge of heat from Siberia, and rough sea over Laptev bite tanks to the fetch of the now open Lapev sea. But, in this massive surge of heat, isentropic lift and thunderstorms are likely, wich is going to bring cyclogenesis. This secondary low starting from the front of the first low is the one to look. Like last year and one or other years before, isentropic lift and buoyancy is going to be an important factor, thanks to the reccord warmth ongoing. And like others years, it is way more likely that models are underestimating the deepening of this low than the other way round. This can be seen comparing precipitations from the 00Z and the 06Z of GFS. The GFS 06Z is way waty worst for sea ice than the 00Z, and one reason is probably due to stronger thunderstorms and higher max rain rate forecasted in the 96H - 120H range in the front of the first low. The 00Z is reaching "only" 10 - 15mm in 06 hours -this already qualify as bath crazy for Arctic...-, the 06Z is reaching more than 30 (30 !!!) mm in 06h under the strongest cells. Don't ask why the 06Z is total mayhem for sea ice....

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: November 02, 2019, 08:00:40 PM »
Daily gain 170 k, 46 k MORE than the 2010's average of 124 k.

Still very high, and just three seas (ESS, Laptev & Kara) gained 164 k of that total.


I think this is an important point. The biggest difference with 2016 is the Kara Sea and to a lower extent the ESS. Kara Sea has seen quite unexpectedly high sea ice gain and is ahead of the most recent years (2016 and after I mean). Big gain in ESS and Laptev is a fatality, nothing can make for shallow waters and fresh water. But now that the sea ice has hit the hard land, ESS and Laptev can't see any more gain, this two seas are already near the 100% mark. If Kara sea is not able to sustain the surge in gain, it is likely that a stall in Arctic sea ice extent will happen. As for now, the great battle of this winter for Chuckchi and Barents sea is starting, and easy ice gain are likely over. I am quite ready to bet that Kara Sea will not be able to sustain the pace, and that we are going to see stall shocking the extent growth like in 2016. The biggest hope for now I think is the Beaufort Sea, the only sea which can keep things up for now I think.

Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 19, 2019, 12:17:23 PM »
Even for the Arctic Ocean, we will be hard press to end the winter with at least a 2m first year ice, putting the risk of a memory of this summer. The islands on the russian side are nearing or breaking record which are only a few years old, like Ostrov Vrangel :

versus 2016 :

Or Ostrov Kotelnyj :

versus 2018

Or Ostrov Vize :

versus 2016 :

And again, a layer of low level clouds is keeping in check the refreze, as shown for example with Ostrov Vrangel between 300 and 600 meters since the end of the Summer :

And SSTs are still extrememly warm, locally up to 7 or 8 (!) °C. And with the clouds in place, cooling is going to be slow. It is a sure bet that southern Chukchi would not freeze before December or January, and it is increasingly likely that this sea could not fully refreeze before the end of the winter.
For now, the downward IR flux at surface is a bit less averaged over Arctic comapred to record holder 2018 and 2016, meaning a bit more heat is escaping the furnace of the Arctic. But we are starting with an ocean wich is way warmer than in 2016 or 2018 and to cool down this thing this small diff is not enough...

Consequences / Re: Forests: An Endangered Resource
« on: September 27, 2019, 05:48:20 PM »
Yes, it is already some years that horse chestnut is screaming its sorrow and pain. It is often question of Amazon or Indonesia or California... but here in northeastern France trees are dying everywhere, it is crazy. Bark beetle are eating away forest, and relentless heatwaves are drying trees. You can't walk 5 meters in any forest without spotting dead trees after dead trees, of any species, old one or young one. Leaves are already falling here, which is really early -and while temperatures are still high and there is no frost still-.

In the mean, around 10% to 20% trees are dying now. With an annual harvest of 12 millions m3 it is at least 2 millions m3 of damaged wood for this year for France. But locally up to 80% to 90% (!) of trees are dry and dead. Hornbeam, beech, spruce, ash, douglas, you name it.

Here it is named a "sanitary crisis", but it is no longer a crisis as it is only worst years after years. It was already very, very bad in 2018, and "only" very bad years before. It is just that mass mortality is growing more massive years after years. And in Deutshland or in Switzerland it is no better.

Arctic sea ice / Re: The 2019 melting season
« on: September 06, 2019, 11:44:13 AM »
Sum of forces is definitively not the same. Ice and water does not respond in the same way to winds. And there is also hydrostatic equilibrium, 100 hPa is worth one meter of sea level, but zero point zero meter of ice level. And of course in the end gravity would even out the sea level if the winds stop blowing.

Arctic sea ice / Re: The caa-greenland mega crack
« on: September 03, 2019, 09:47:01 PM »
Yes thanks longwalks ;) If there is specfic interest for the Nare Strait, the work of A. Münchow is worth citing :

"The established flow of seawater from Pacific to Atlantic Oceans through the Arctic has been attributed to higher sea level in the Pacific (Wijffels et al. 1992), associated with the lower salinity of Pacific waters. Sea level in the Atlantic may be more than 0.5 m lower than in the Pacific and 0.1–0.3 m lower than in the Arctic (Muench 1971). More accurate estimates of steric forcing have yet to be determined, but it is probably safe to conclude that much of the drop in sea level between Arctic and Atlantic Ocean occurs along the 530-km length of Nares Strait, thereby providing the impetus for the fluxes that we have measured.'

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 03, 2019, 02:40:21 PM »
Without wanting to look harsh, but I think the discussion is taking a bad way. I am not a specialist of this question, but a big missing piece of data is the problem of land versus ocean distribution in Northern Hemisphere. I mean, in winter, ice edge is constrained more by geography (coast of Russia and Canada) than by physics (warming / cooling atmosphere, ocean currents, and so on). Which is no longer the case in Summer, where ice edge is, but for Greenland, in open Ocean and can retreat as the thermodynamics warrants. This is probably why seasonal cycle changed dramatically after 2005. Until 2005, ice was still mostly bounded by the coast, even in Summer. Now, ice has all the possibility to expand and retreat without being imped by the coasts. One possibility is to look instead at sea ice edge latitude. Doing this, difference between Summer and Winter is lessened and the downward trend is more even.
On top of that, captain obvious helping, it should be noted that sea ice area can't go negative. But this has the implication also that the downward trend should go to zero sooner rather than later, as there is no more ice to melt in summer. Losing 2 million squared km when you have like 20 million at hand is almost nothing, losing 2 million squared km when you have like 1 million at hand is impossible... This is probably the first big answer to the question "why trend is so irregular and the seasonal cycle has gone mad ?".

It should be noted also that from this point of view, the situation is “worsening” on the Pacific side. When the edge was in the Bering Sea, there was still some width to “yielded” big loses. Now that the edge is in the bottleneck of the strait, even a retreat of 1° North –which is quite significant– would amount to almost zero ice area loss. Zero time a thousand km is still zero :p We will have to wait for ice edge in winter to reached Beaufort / Chukchi / ESS for seeing anew some significant ice loss for the Pacific side. Same on the Atlantic side, as Barents and Kara Sea are zeroing, going further North will become complicated in the short term. It will happened in the decades to come of course, but over the course of the coming years, variability of winter sea ice as seen from the metric of extent will probably still be dampened, even if the warming speed up bigly.

P.S. And on top of that "simple" geographical explanation, geaography also lead to "energy yield" vastly different from Winter to Summer. Land and Ocean distribution are also responsible for bigly different thermal answer in Summer and in Winter under the same forcing. We will also probably have to wait that the Ocean becomes an "heat accumulator" in winter for seing warming speeding up in Arctic.

Arctic sea ice / Re: The caa-greenland mega crack
« on: September 03, 2019, 06:42:42 AM »
This topic has drowned into the abyss of this forum, but the mega crack is still here and alive. And there is still sign of melt going on. To justify, Kap Moris Jesup hit 10.3°C the last day of August, a record for this time of year. And to the the North of Ellesmere, the Nares strait export has lead to a big, big hole. Fortunately the season is ending.

An unspoken consequence, here in northeastern part of France, is the sanitary situation of forests. Some plants are dying like never. Spruce, european spruce, beech, ash, bilberry etc... Many plants and trees are dying. And some are still alive but are on the brink of disaster like apple trees or more generally fruits trees which are not enough vernalized in winter. In my valley, there are big brown patches everywhere, like pictures in this article : And in the forest, we can't walk an hundred meters without seeing a tract of land which is dead. In Swiss, there is even a declaration of emergency ... Consequences will be long lasting but big : flooding of the wood market with lower quality tree, increase risk of accidents, increase risk of forest fire, loss of biodiversity etc... The financial burden for some villages could be unbearable in years to come, as many rural towns have big incomes from the trade of wood. I don't know what a valley here could look like without beech, spruce, apples and cherries...

The rest / Re: Are you hoping for a global civilisational collapse?
« on: August 27, 2019, 02:01:34 PM »
It is ongoing, but I am not hoping for it, just preparing and praying the Lord. And reading ancient books from the late Roman Empire. But I am not a big fan of the world "collapse". Collapse will not happens instantly nor globally, but is an already ongoing step downward trend with some periods of temporary improvements, being better or worst here and there, and it is not going to be a global catastrophe over a day or so. Humans are often fascinated by big catastrophes, but the collapse of a civilization never followed this path.

I had problems voting here because I think the concept of collapse as given here is a bit of a straw man. I don't think it likely that it will be Armageddon, with hardly any survivors... but I'm sure there will, at some point, be a major reduction in population, and a reversion to a largely agrarian society in places that aren't used to such lifestyles. Many indigenous cultures will carry on, under trying conditions. What I expect to be the main symptom of collapse is the loss of the framework that allows intensive industrial civilisation. First there will be food shortages, then public unrest and lawlessness, then a new equilibrum will emerge later. The skills and knowledge to survive as sustainable communities still exist, although yes, life would be less comfortable. And yes, I expect this to happen (at least in part) within a few decades.

I fully agree. I am trying to build a sustainable community in my neighborhood, reviving ancient practices from the past.

Arctic sea ice / Re: The 2019 melting season
« on: August 24, 2019, 09:27:12 AM »
Models are trending deeper and deeper. Below 970 hpa will as forecasted now make this complex looking like a GAC. Brace yourself for ice armagedon.....

Arctic sea ice / Re: The 2019 melting season
« on: August 20, 2019, 09:02:24 PM »
If it was 500 or 1000 km toward Beaufort, it would be a party of ice destruction.
In that location it smells season brake of an already braking season.

Again, this is definitively not the opinion of the Euro guy. I am ready to bet that this boy will be closer to the reality than GFS. The IFS at 120h - 144h is extraordinarily bad and the IFS at 96-192h is "only" really, really bad. There is a lot of energy to dissipate and the GFS, sitting like a big fat guy in his chair and waiting God knows what's sighing "Energy, which energy?" is really not a credible option in my opinion. Also, IFS (00Z or 12Z of this day) is able to go to a warm seclusion. This point is also not in favor of GFS. From the season, we have learned that the Arctic is under steroids and a cold, dreary frontolysis is not looking likely. Perhaps I am badly mistaken and fooling myself, but for me this is not looking like anything serious.
The point is really not about the deepening low above the archipelago. Now, every one is ok for a deep low over this region. But after, some models like IFS are able to let the low spinning, with a new feeding of energy from Atlantic and Eurasia, while GFS is letting this thing dying.
Perhaps it is the hour where Denethor is whispering the antithesis of your one signature to the lasts floes of sea ice still standing : "Why do the fools fly? Better to die sooner than later. For die we must."

Arctic sea ice / Re: The 2019 melting season
« on: August 18, 2019, 01:24:17 AM »
As CSNavywx noted a while back, ridges tend to persist and the models often underestimate the persistence. We should not ignore the latest Euro model run. We'll know that the threat to the ice is over when temperatures drop and area losses stop. The recent slowdown in extent losses was associated with a rapid drop in area, an indication that the melt season has not yet stalled out. The DMI 80N graph shows the melt season has gone into extra time.

I don't think that this means this year will catch up with 2012, but there's still time for surprises.

Yes, GFS is probably lost in the wilderness again. I have put also Arpege, a french model which is not often look but is often good and is a close friend of IFS, despite being coded quite differently. At 96-120 h, the low over north Pole must be closely monitored. It is not deep, but again it is deepening against a strong ridge. And so, a sub 995 hPa low vs a top 1025 hPa high result in a strong low level jet over CAB. I don't have all the tools for an analysis, but it also likely that the high and the low are feeding each over. Stronger high with warmer air mass is probably enhancing the baroclinic zone trough stronger temp gradient and stronger wind speed, helping the low to deepen. No GAC again, but these recurrent, nasty low battling strong highs are not helping. A solution like GFS with a broad low sipping a cold drink and waiting I don't know what would be way better but it is not really the most likely outcome.

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 17, 2019, 08:34:25 PM »
Yes it is probably the explanation, despite Copernicus showing data available since 2006. And yes it is really frustrating to be blind while the Beaufort sea is beaten like never. The beaufort gyre is quite an important thing, but who know what is really happening ?

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 17, 2019, 04:53:35 PM »
I make a quick map to compare 2019 on the 26th of August (forecast from Mercator) to mean from 2016, 2017, 2018. I don't know why, I was not able to download data for prior years, I don't know why... Excepted for the Barents sea which is cooler than over the 3 previous years (also the case for SSTs with a true base period), everywhere the warmth is showing, and even in the central basin there is streams of abnormally warm temperature.

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 16, 2019, 04:54:21 PM »
And now ITP 110 has hoisted the white flag and surrender. No news since two weeks. Too bad, as Mercator is showing extreme warmth in Beaufort. It should have been interesting to see what really happens here. The build up of heat shown at 30m and 100m is like nothing ever seen. Will this have an influence on refreeze season ? And Mercator was shown to be warming not enough compared to ITP 100. Depite this, in part of the Beaufort Sea, the big mess is going on and on, with a loosening of the stratification and a build up of energy wich is beyond superlatives and the "spot the difference" game ... Where now the Pacific layer and the halocline ? Where is the freshening and the cooling ? I don't know where we are going at this pace, but here we go.

P.S. : There is no special reason for a comparison with 2016, it was only to give a point of reference for a year wich was in its own quite bad for Arctic.

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