2016 Arctic cyclone, update 2

So, the storm has been raging for a while now. The latest Environment Canada weather map shows it's at 984 hPa.

According to this tweet by PhD climatologist Brian Brettschneider a IABP buoy from the University of Washington measured a lowest central pressure of 966.5 hPa, which is somewhat lower than the 968 hPa reported by Environment Canada (see previous update):

This animation of Uni Bremen sea ice concentration maps for the past 4 days shows how the ice has started to follow the winds. Also notice how far open water is reaching into the ice pack now, almost getting past 85N:

The impact on the extent and area graphs isn't as outspoken as in 2012, because there was a lot of weak, preconditioned ice back then that was poised to go poof. But make no mistake, the current exceptional weather is keeping 2016 in the race for that top 3 position when the minimum is reached next month.

Cryosphere Today sea ice area as calculated by the inimitable Wipneus has 2016 in second place now:

And on the JAXA sea ice extent graph yesterday's century break was followed by a solid 73K, keeping the 2016 trend line close to 2007, which had a couple of slow days around this time, so 2016 could be second here too this weekend:What will the storm do next? Here's what the ECMWF forecast model has to say about that for the coming 6 days (click for a larger version, and go to the ASIG Forecasts page for daily forecasts):

The storm's pressure will hover around a respectable 980 hPa for a couple of days, but after the weekend some serious re-intensification is forecast!

Here's another animation of the entire 11-day ECMWF forecast, as provided by the Tropical Tidbits website, so we can see what the cyclone's central pressure will be:

This is serious sh... stuff. This is just 2-3 days out and so it is quite likely now that the storm will re-intensify to reach another bottom central pressure of 972 hPa, with possibly a few days of lower than 980 hPa to follow. We may be receiving an answer to one of the two questions I posed yesterday, much sooner than expected: Can this storm be labelled a Great Arctic Cyclone as well?

Yesterday it seemed as if this could become the not Great, but All Right Arctic Cyclone of 2016, but now I'm tempted to say this storm is another GAC, the second in just five melting seasons. Maybe it's just coincidence, or maybe this has something to do with it:

These images depict sea surface temperature anomalies as reported by DMI. On the left it's 2012 a week from now, on the right it's the latest image (yesterday). As you can see, exceptional sea surface temperatures all over the Arctic. The open water in the Beaufort Sea may not be as warm as it was in 2012 - it's warmer everywhere else - but it's warm enough to do some serious bottom melting damage to all the ice that is moving towards it, in the wake of the storm's massive winds. And then there's the waves and the churning and the Ekman pumping...

Looks like we may get an answer to that other question soon as well: What will this do to the ice? Stay tuned, if you weren't already.

Comments

[Artful Dodger]

Thanks for the update, Neven.

I wonder how much warm water has mixed into the surface layer by this nearly-stationary low-pressure field?

Oh for $8M and some air-deployable underwater drones! Data is Golden (Blogs r Cheap ;) and either the Louis or Odin is in just the right place to deploy them and collect the data.

Or in a pinch launch an USN C-130 from Thule... Very deep sigh if we miss this data.

But who knows, we may yet see this data, just knot in real time.

Cheers,
Lodger

[viddaloo]

Sorry for the effed up Y–axis scale on the attached CAB chart! 2016 CAB area officially went off the chart!

Big: http://i.imgur.com/9OGILSk.png

[Neven]

Indeed, Lodger. Some real-time data from drones or buoys would be greatly appreciated, not just by us.

JAXA reported another solid drop of 85K. If today more than 55K of ice melts/vanishes, 2016 will be in second position.

Over on the Forum I posted the latest CAJAX compactness graph, which shows this year is currently lowest in the 2007-2016 record. This means the pack is highly dispersed, lots of ice surrounded by open water, and high compaction potential.

[Neven]

And Robertscribbler has another post on the situation: Warm Arctic Storm Tearing Sea Ice to Shreds amidst Big 2016 Heat Spike

[iceman]

"Eggbeater August"

[viddaloo]

3rd forecast for the autumn minimum extent: #[email protected] km²

http://wunderground.com/blog/viddaloo/arctic-sea-ice-collapse-19-july17-august-annual-average-extent

[Jim Hunt]

Meet the new cyclone. same as the old cyclone?

Today's 00Z ECMWF forecast for tomorrow morning:

http://GreatWhiteCon.info/2016/08/the-great-arctic-cyclone-of-2016/#Aug-19

The high resolution AMSR2 Arctic sea ice area has reduced by another 133.5 thousand square kilometers since yesterday. A similar drop tomorrow will take us below the 2015 minimum.

[wayne]

as expected! Jim

How do you get this data so early?

[wayne]

http://eh2r.blogspot.ca/2016/08/challenge-to-1-minima-sea-water.html

as expected reference :)

Not like contrarians who predicted coming ice age, we on the Neven's site, have a good batting average, enough for the big leagues.

[wayne]

how quiet is it on WUWT? I wonder.......

[Paul Klemencic]

The GAC 2012 caused ice extent to drop 1.5 million sq km in fifteen days, albiet from a higher starting point (6.0 M). The storm started with over 2.2 million sq km at risk in the E. Siberian, Chukchi, and Beaufort regions, and took out about 60% of this ice in just over two weeks.

The current storm started with 5.3M, and should take out between 1.0-1.3 million in fifteen days. At the end of August, we will have only 4.0-4.3 million left, well ahead of 2007 melt levels, and trailing only 2012.

If I have time, I will put up a comment summarizing the observations and heat balance information that I posted in 2011/2012. This storm has a remarkable coincidence in many respects to the GAC 2012. There is room for some very interesting informed speculation. I view this event as a breakthrough event, showing the 2012 GAC was not a existing system statistical anomaly, but a new event signifying fundamental changes in the Arctic, and by extension, an effect on the NH mid-latitude weather systems.

[Bill Fothergill]

@ Jim "Meet the new cyclone. same as the old cyclone"

Who are you quoting?

[Jenny E. Ross]

Paul said:

"There is room for some very interesting informed speculation. I view this event as a breakthrough event, showing the 2012 GAC was not a existing system statistical anomaly, but a new event signifying fundamental changes in the Arctic, and by extension, an effect on the NH mid-latitude weather systems."

This is precisely what I have been thinking, but I don't even remotely have the expertise to do the necessary rigorous analysis. Paul, I'll eagerly await more from you (and perhaps others) about this.

Cheers,
Jenny

[Joe_nilo]

"There is room for some very interesting informed speculation. I view this event as a breakthrough event, showing the 2012 GAC was not a existing system statistical anomaly, but a new event signifying fundamental changes in the Arctic, and by extension, an effect on the NH mid-latitude weather systems."

In other words, "the New Normal."

[Jim Hunt]

Bill - I'm paraphrasing The Who. A musical interlude?

https://youtu.be/ZgubG-MOPT4

Meanwhile the "new cyclone" was down to 976 hPa by lunchtime UTC. Here's the 12Z ECMWF forecast for lunchtime tomorrow:

Wayne - Do you mean the ECMWF maps? I use MeteoCiel as a one stop shop for "weather" forecasts. Alternatively, the AMSR2 data comes courtesy of Wipneus.

[D]

If the premise that more open water in the Arctic is causing stronger storms is true, then we should be seeing stronger storms in the Barents sea as well as the central Arctic.

We'll see how the ECMWF forecast at 216 hours pans out. As we have recently seen forecasts for the Arctic beyond 3 or 4 days usually fail.

But 954mb forecast for the Barents sea at least shows that the model is picking up an effect of the energy stored in the much warmer than normal waters there.

I think we can reasonably hypothesize that increasing levels of oceanic heat are leading to stronger storms in the Arctic in August and September by destabilizing the atmosphere. A cold, reflective intact layer of ice leads to a cold, stable layer of air at the surface. When that ice is gone, atmospheric stability decreases in the early Arctic fall.

-Fish

[Jim_dowling]

Here Fish's insane ECMWF forecast for 9 days time - 954mb in the Arctic.

[Jim_dowling]

Let me try again.

[D]

You have to take those 9 day forecasts with a margarita glass lined with salt.

http://www.tropicaltidbits.com/analysis/models/gfs/2016081918/gfs_mslp_pcpn_atl_36.png

The north Atlantic has phenomenal amounts of stored heat and that heat is pushing towards the Arctic. With all that heat there's likely to be trouble from Florida to the Kara sea.

The models are telling us something even if the details don't pan out this time.

[r w Langford]

Not a pleasant time to be a real or polar bear.
Sorry for the OT, back to lurking.

[wayne]

Jim Dowling,

954 mb is very possible, the temperature contrast fuels abound, I do vaguely recall such slp lows in the past, but not in summer.

Jim,

ECMWF Low pressure forecast at Meteo Ciel is doing something I have rarely witnessed. If it happens it would be quite exceptional. A cyclone tracking exactly the opposite course it does, towards NW Europe instead of from NW Europe.

D,

The fuel is from warmer open water instead of sea ice, convection a-paloza.

[shwarzbarry]

I've been following the MASIE 4k res chart for a while now, and 2016 has fairly consistently been below 2012 recently, until just the last few days.

https://nsidc.org/data/masie/masie_plots.html

How much store should I set in this product? I understand the advice that it should not be used for long-term analysis, but is it also not very useful for the short-term?

[Eli Rabett]

Thanks to all for the discussion.

[Neven]

According to Environment Canada the storm is currently at 971 hPa. Impressive!

I'm going to try to do another update tonight or tomorrow. The August SIO is also out.

[Neven]

How much store should I set in this product? I understand the advice that it should not be used for long-term analysis, but is it also not very useful for the short-term?

In the short term it's probably the most accurate product, because human operational analysts look at a large set of data sources to determine where the ice edge is. Automated satellite sensor data can be (temporarily) thrown off by things like clouds and flash melting.

As for long term consistency: I looked at the data this past spring and there clearly is a break somewhere in 2010-2011, meaning that years prior to that are too low compared to the years after that. I was in contact with people at NIC and NSIDC and they told me that it's difficult to find the exact reason, but they expect it might have to do with the introduction of ASCAT around that time (which helped to see more ice, so to speak).

[TomLav]

Another way to view how the GAC2016 moved the ice around over the last week: OSISAF ice drift data.

[navegante]

It is scary to read what realist commenters have to say lately at the forum, like,
http://forum.arctic-sea-ice.net/index.php/topic,1493.msg86965.html#msg86965
LMV and others as well. Neven you also seem somehow alarmed

[Neven]

I've been alarmed since 2007, navegante. ;-)

The forecast is very fickle the further out you go. I don't know what to make of it.

As far as the numbers go, my focus is still on whether this melting season can end up in the top 3. I'm not expecting it will come very close to the 2012 record, but you never know.

[Jim Hunt]

Wayne - I reckon the 72 hour ECMWF forecast is starting to look plausible:

http://GreatWhiteCon.info/2016/08/the-great-arctic-cyclone-of-2016/#Aug-20

Here's what today's 00Z shows for Tuesday:

Another battering for the MIZ on the Siberian side of the Arctic?

[wayne]

Jim,

"lots of catching up to do"

is correct to say that, but the potential for greater melt than 2012 is in the cards, with huge areas of messed up sea ice badly broken up from their packs, lots of ice floes are surrounded by water. And heat engine GAC's feasting on temperature contrasts and moisture injections. This GAC2 heading towards NW Europe is simply astounding.

However, the main feature of 2016 melt season is the apparent slowness in ice movement:

http://eh2r.blogspot.ca/2016/08/sea-ice-floes-are-still-not-moving-very.html

Every year I noticed significant sea ice movement with short time gif animations, not this year, despite very strong Cyclones. The Gyre current boosted by a great spring presence of anticyclones, is still a force to contend with.

[Artful Dodger]

Hi Folks,

Regardless of the final Summer minimum this year, the icepack faces another real threat this Fall/Winter.

With the current separation of the pack at the Lavtev Bight (from 45E to 135E), there is a real risk that the transpolar drift pushes ALL of the multiyear sea ice from the European sector out of the central Arctic via Fram Straight before the next melt season. Constant bleeding.

The loss of multiyear ice over Winter would be devastating, given that it takes 2 years to reform MYI with the appropriate low salitity via the brine rejection mechanism.

This leaves the remaining reduced MYI pack (about 2M km^2 or so Werther?) to oppose the forces of any GAC17 or GAC18.

OMNIMOUS. Think I go read some Goethe.

Cheers,
Lodger

[AbbottisGone]

..referring to the last two maps on sea surface temperatures of 2012 v 2016:

"So, was 2012 defined by the very curious looking Beaufort sea surface temperature anomaly?"

[AbbottisGone]

The Warm Storm Generator

Heat in the Arctic doesn’t just emerge there. It comes, largely, in the form of energy transfer.

Heat-trapping gasses warm the atmosphere in an uneven fashion. The way these gasses absorb solar radiation results in more heat trapping during the dark of night. And the Arctic experiences a thing called polar night which lasts for months.

As a result, the Arctic already gets a slightly more powerful nudge from global warming than the rest of the world. As the cold begins to fail in the Arctic, a number of amplifying feedbacks come into play that further multiply the warmth.

<<

(this is from Robert Scribblers blog... it's all fascinating/news to me!) (Why is more heat absorbed at night??)

[Werther]

Lodger, hi,

Good to hear from you! I’d suggest reading ‘Journey to Italy’, which has a nice, laid back sense, being a diary of an early tourist trip made by one who has the magic eye for the artistic side.

On remaining multi year ice, your assumption of about 2 Mkm2 is quite accurate. I had day 233 in my CAD frame this morning. The remaining 1 Mkm2 ‘safe haven’ still shows the best concentration. But it has almost lost its former ‘mesh-structure’. Just under 200Kkm2 left, pressed against the entrance of Nares Strait in the Lincoln Sea.

The cyclone, which centered about 335 km NNW of Ellesmere yesterday, has messed up the N of CAA part of the ‘safe haven’.

With the help of Ascat and the 2015 ice age map, I suppose all of the 1 Mkm2 ‘safe haven’ is MYI 3-5 and more years old. Then there’s a neighbouring stretch, about 700Kkm2, reaching from Fram Strait, just along the Pole, up to the Beaufort sector on the latitude of McClintock Sound, which varies between 3 and 5 years old and is mostly in bad shape.

The flawed and battered ‘arms’ in the direction of Wrangel Island are made up by 4-5 year old MYI in the process of elimination.
I’d say it’s about 100Kkm2, however, there are lots of small particles floating free over the whole Bering sector.

All of the ice in the direction of the Laptev Sea is FYI. This feature was protected through domination of light, counterclock-wise winds.

All together, it’s a weak, almost terrible, situation. Given that the ’12 pack at minimum still had a large high concentration core (which isn’t that large now) and also considering the ’13 and ’14 lower melt years (which let more volume being spared), I think at minimum this year volume will again be near the lowest ever.

[navegante]

@ Werther hi, I counted the battered 'arms' as FYI ridged and thickened by compression during February to May. I don't think the MYI went so far.
Lost the track of the ice age maps. Are they updated in a different Web page?

[Olivier Del Rio]

"(this is from Robert Scribblers blog... it's all fascinating/news to me!) (Why is more heat absorbed at night??)" The sentence is a bit misleading. Actually, nights and winters warm more than summer and day. This is a fingerprint of the greenhouse warming. Warming in summer and day is due also to the sun, and not only due to greenhouse effect, so the increasing greenhouse effect is not as visible and is more diluted. And in Arctic water vapor can potentially have a stronger feedback effect because water vapor is near zero in the old climate of Arctic. Despite "cold" air temperatures -everything is relative...- SSTs were extraordinarily warm and precipitable water was near record levels in 2016. Hence, the downpours with some staggering amount of rainfalls in 24 hours, and strong downward IR radiations. To illustre the point of Robert (hoping I made no mistake with the weighting of superficy ^^" ), downward longwave radiation flux for the Arctic in June-July from the reanalysis :

http://www.climatvisu.fr/images/Autres/DWLRF_quot.png

http://www.climatvisu.fr/images/Autres/DWLRF_mensuel.png

Third highest after 2012 and 2016, but in fact indistinguishable from 2006.

For SSTs, according to the reanalysis, water temperature were second highest only behind 2012, and precipitable water third behind 2012 and 2006 (a thin hair ahead of 1998)...
http://www.climatvisu.fr/images/Autres/SST_TPW.png
Robert has a good point pointing to warm and humid Arctic. It was already perceptible in others years, but in 2016 there is clearly a paradigm shift with strong, warm, moist cyclonism which can destroy ice as easily as a strong ridge. Neven wonders itself if this can be a consequence of the warming. No strong evidence here of course, but some hints indicate that is could well be the case. Early snow retreat can enhanced the temperature gradient near the shores of Arctic, and so brings cyclonism. In 2010 it was also the case. No big cyclone in 2010, but some potent ones still, with strong warm moist air advection (up to +20°C à 850 hPa in July....). In 2016 it was even worst and sea ice could not sustained the assault. We are still a bit short of subtropical and tropical cyclone but I don't think that the future of the Arctic is set to be made of high pressure area and clear skies. And forecast from the models are gloomy, showing consistently a strong advection of warm air with belligerent winds over the already weak area of sea ice.
http://www.climatvisu.fr/images/Autres/ECMOPNH00_168_2.png
Race is not over yet and we could well see a very late minimum not so greater than 2012.

[John Christensen]

"a new event signifying fundamental changes in the Arctic",
"The New Normal",
"The fuel is from warmer open water instead of sea ice",
"heat engine GAC's",
"The Warm Storm Generator"

Beyond the fact that the current GAC is battering the sea ice by wind action and increased surface current greatly enhancing mixing, I do not any reason justifying any of the labels mentioned above.

Why:
1) August is in fact the second most common month for cyclone activity in the central Arctic Ocean, following the leading month of July very closely.
2) The overall surface temperature of the sea-ice covered area is about normal - DMI 80N temps have in fact been consistently below normal for more than one week.
3) The current cyclone has developed and is maintained exactly the way described by Serreze & Barrett (2007) and others before them.

However, after reviewing existing literature again, I would argue that the increased land temperature (due to AGW) relative to constant temperatures over the remaining sea ice (remember that surface temperatures over sea ice will remain near constant, until the ice is gone), should in fact increase the frequency and strength of summer cyclones in the CAB, strengthening the barocline between landareas and sea-ice, which on average over the summer months will help preserve the sea ice.

The 'old' rules therefore still apply and can explain, why we may expect these cyclones to become even more frequent and stronger, without involving open water areas in the equation.

Chris Reynold seemed to join this argument back in June as well.

[wayne]

John,

The literature does not comprise up to date realities. DMI is a model, not surface or upper air real data. We have very little real data from the region. Increase Cyclonic activity in July and August are naturally the result of NH temperature contrasts vanishing, with winter gone, there is more cyclonic activity because there is more energy allowing it to do so, especially If there is less sea ice, which occurs naturally. The cyclone season gets prolonged with less winter afoot, this is our literature: summer 2013-14-15-16 extended cyclonic activity. Example, hurricanes drop dead when hitting land surfaces, exactly what happens to cyclones when they hit sea ice cooled surfaces. They are not spanned over sea ice, but live by sea ice open water boundaries.

"The current cyclone has developed and is maintained exactly the way described by Serreze & Barrett (2007) and others before them."

Please describe what they wrote instead of citing their work. Prior to 2007 was a different science world. Doesn't over all warmer temperatures make for a better longer cyclone season? You argue like cyclones can occur any time of the year and that ice don't matter, very muddy explanation. So because it is colder over the Arctic Ocean with respect to land surfaces, there are more cyclones? Can't wait for this to happen during spring time, like last spring? Remember?

[wayne]

They are not spawned over sea ice, right? Let us think a little more.

[wayne]

August 21 apparent small 28K extent drop is an illusion by cause of scattering of the lee side of sea ice shores.

http://eh2r.blogspot.ca/2016/08/compaction-vs-scattering-sea-ice.html

There are 3 cyclones over the Arctic Ocean now all contributing to more scattering which does not register extent drops until the scattering thins the pack to be vulnerably broken up. This illusion would be less if extent grid thresholds were much smaller.

[AbbottisGone]

I was thinking the 28K drop was an illusion,.. especially considering Wipneus on the forum was pointing out the possible joining of the very lightly concentrated ice through the pole toward the tip of Greenland.

** 3 cyclones you say!

---> "Muy Interesante!!" <---

[John Christensen]

Hi wayne,

If you actually read the cited articles, it is very odd that you do not seem to retain the scientific message in these, as the main arguments have been made very accessible.

However, let me try again.

Below, I have added your arguments and then provided the relevant text from Serreze and Barrett, The Summer Cyclone Maximum over the Central Arctic Ocean, 2007, hereafter just ‘SB’ followed by comments:

1. On why cyclones appear over the Arctic Ocean during summer and why they are centered near the Pole, above the sea ice:

wayne:

”Increase[d] Cyclonic activity in July and August are naturally the result of NH temperature contrasts vanishing, with winter gone, there is more cyclonic activity because there is more energy allowing it to do so, especially If there is less sea ice, which occurs naturally.”
“The cyclone season gets prolonged with less winter afoot, this is our literature: summer 2013-14-15-16 extended cyclonic activity”

SB: Differential atmospheric heating between [ice-covered] Arctic Ocean and snow-free land:

“A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean. Its seasonal onset is linked to the following: an eastward shift in the Urals trough, migration of the 500-hPa vortex core to near the pole, and development of a separate region of high-latitude baroclinicity. The latter two features are consistent with differential atmospheric heating between the Arctic Ocean and snow-free land.”

SB: On period for summer cyclones in the CAB:

“Particularly striking .. is the distinct summer pattern of high cyclone center counts over the central Arctic Ocean, focused at about 85°N along the date line (the summer cyclone maximum herein). Onset of the pattern is seen as a sharp increase in activity between May and June. Activity peaks in July and August and then declines sharply between August and September.”

SB collecting the argument of the placement of the vortex, differential heating, and location of the cyclones:

“Building on Serreze et al. (2001), the migration of the 500-hPa vortex to over the pole and the development of the frontal zone both point to a role of differential atmospheric heating between the Arctic Ocean and snow-free land. While there is 24-h daylight over the Arctic Ocean in summer, the high albedo of the sea ice cover and the low-level stratus that dominate the region mean that much of the downwelling solar radiation is returned back to space. Furthermore, as shown in the recent Arctic energy budget analysis by Serreze et al. (2007), based on data from ERA-40, there is a strong downward net surface heat flux in July of about 100 W m_2, and of 75 and 45 W m_2 in June and August, respectively (a flux from the atmosphere into the underlying ocean), for the Arctic Ocean as a whole. This flux is associated with melt of the sea ice cover and (primarily over coastal open water areas) seasonal replenishment of oceanic sensible heat storage. For July, the net surface flux is actually larger that the horizontal convergence of atmospheric energy into the Arctic Ocean region. It follows that the 500-hPa vortex will want to shift to over the cold Arctic Ocean with broadly symmetric flow around it. Cyclones migrating into the cyclone maximum region, along with those generated over the region itself, will tend to track around the vortex and eventually occlude.”

Comment:

Therefore wayne, what you seem to have turned upside down is the ‘temperature contrast’ argument: It is not vanishing; the temperature contrast was always there, and with rising land surface temperatures, reduced snow cover, and sea ice still keeping CAB SST relatively low, the temperature contrast has probably increased over the past decade.

2. Origin of summer cyclones in the Arctic Ocean:

wayne:

“Example, hurricanes drop dead when hitting land surfaces, exactly what happens to cyclones when they hit sea ice cooled surfaces”
“They are not spa[w]ned over sea ice, but live by sea ice open water boundaries. They are not spawned over sea ice, right?”

SB on Arctic summer cyclone origin:

“the majority of systems contributing to the summer cyclone maximum originated outside of the region (79% of the total). Most of these externally formed systems were generated over a broad swath of the Eurasian continent, sometimes from distant source regions, or over the Arctic Ocean in close proximity to the cyclone maximum region. Very few contributing systems were generated over either North America or the North Pacific.
A few entered from the northern North Atlantic, and Norwegian and Greenland Seas.

The remaining 21% of the contributing systems formed within the cyclone maximum region itself.

To summarize, based on the cyclone detection and tracking algorithm used here, the summer cyclone maximum of the central Arctic Ocean appears largely as a “collection zone” for systems, especially those generated over Eurasia. There is also some generation within the Arctic Ocean and the cyclone maximum region itself. Recall from earlier discussion that the summer Arctic frontal zone is expressed along a wide swath of the Eurasian coast, but is especially prominent over northeastern Eurasia (roughly the 65°–70°N, 140°–170°E region).
Pointing to the impact of the Arctic frontal zone [The barocline caused by differential atmospheric heating], many of the latter can be identified as preexisting tropospheric waves along the Eurasian coast. The North Pacific, the North Atlantic, and North America are insignificant as source regions.”

Comment:

As you see from the article, 21% of the cyclones originate from the central Arctic Ocean, i.e. above sea ice, while the majority origins out of the Eurasian continent. The cyclones identified as ‘preexisting tropospheric waves along the Eurasian coast’ feed from the barocline, which again is based on the ‘differential in atmospheric heating’ between sea-ice and land-areas.

Finally SB discuss AO index, coastal Arctic Snow cover and correlation with Arctic summer cyclones:

“a positive winter phase of the NAM [=negative AO index] fosters less snow cover over the Arctic coast of Eurasia and North America, which can then enhance the summer thermal contrast between the land and Arctic Ocean, favoring a positive summer NAM [=negative AO index] by triggering enhanced eddy activity along the Arctic frontal zone (Ogi et al. 2003).”

Comment:

A reduced snow cover on coastal areas by the Arctic Ocean, can enhance the difference in atmospheric heating between land and sea-ice areas, which can enhance the development of the barocline, which again triggers cyclones in the CAB.

In summary wayne; to understand summer cyclones in the Arctic, you need to take into account the specific geographic and atmospheric conditions, which are different from those providing hurricanes, mid-latitude storms, or Arctic region depressions in other seasons.

[John Christensen]

And to the question, whether Arctic summer cyclones assist in advecting loads of warm and humid air onto the sea ice, the SB article notes:

"The coastal baroclinicity is sharpest over northeastern Siberia and north of Alaska, where topography appears to help “trap” the cold Arctic Ocean air."

That the barocline is strongest in these two areas in the summer months should now be obvious due to the significant size of land areas in relative limited distance from much colder water/ice surfaces.

[Olivier Del Rio]

And another important point I think, that I let aside sorry. Thickness was really high during this months of June and July, and correlates well with water vapor of course. This points to an increase importance of latent heat and some warm core process. Open waters early in the season could warm and reach values trailing only behind 2012. This is even more evident with the latest GFS which show clearly warm core process near Ostrov Vize.
http://www.climatvisu.fr/images/Autres/138_5_nh.gif
http://www.climatvisu.fr/images/Autres/138_4_nh.gif
http://www.climatvisu.fr/images/Autres/154.phase2.png
Of course, the IFS is not as fool, but nevertheless it is an extraordinary achievement to see a model able to at least stabilize a low pressure area with showers activity more than baroclinic activity.
For June and July, only 2010 and 2012 saw higher 1000 - 500 thickness for such low pressure. And overall, it is the 8th highest tickness, which is quite extraordinary given that recent warm high pressure brought records high thickness for Arctic.

http://www.climatvisu.fr/images/Autres/thickness.png

[wayne]

Hi John

You seem to miss this part:

"While there is 24-h daylight over the Arctic Ocean in summer, the high albedo of the sea ice cover and the low-level stratus that dominate the region mean that much of the downwelling solar radiation is returned back to space. "

What High Albedo with lesser sea ice extent?

On Vanishing temperature contrasts?

Have you read the surface maps lately between eastern Siberia and current Arctic Ocean temperatures?

The 500 mb low heights vary throughout summer, not necessarily at the Pole. they were more at the periphery of Arctic shores.

The paper is very interesting but has nothing to do with current great drops in extent. You confuse an old paper with current reality.

[wayne]

Yes indeed , publish the same year of the greatest summer dipole with a massive High near the Pole...... 2007. The past changed quickly from that year on.

[John Christensen]

wayne,

You may chose to ignore science, which is fine with me. I will not comment on this any further.

[wayne]

John

I do science every day, you can not go on confusing without a fierce response.

[Olivier Del Rio]

Ostrov Vrangelya in my last message sorry, OStrov Vize is toward the Atlantic side. And as I was looking foirecasts, I missed what was happening... 55.8 mm in 24h at Grise Fiord!!!! http://ogimet.com/cgi-bin/gsynres?ind=71971&decoded=yes&ndays=20&ano=2016&mes=08&day=22&hora=12

http://www.climatvisu.fr/images/Autres/2016082012_4_nh.gif

Absolutly insane, totaly crazy. Probably the highest 24h hour rainfall total in the whole Arctic.

Environnement Canada counts rainfall 06Z to 06Z so for the 19th, 20th, 21rd, total are 27.8 - 28.1 - 29.3 mm!!!! Totaly crazy. The month to date is 125.7 mm, probably something like 400% of the "normal" O.O Holly shit!

[John Christensen]

wayne,

Not sure this time is well spent, but OK:

"What High Albedo with lesser sea ice extent?"

OK, let's just focus on this for now.

So this is the albedo difference between the Arctic Ocean and snow-free land by mid-June, when the barocline developed. As you very well know the ice extent by that time - in the Arctic Ocean - has not changed much since 2007. We did have the opening in Beaufort, but that's it. You still have a very significant blanket of ice during summer solstice with a high albedo compared to neighboring snow free land areas.

Are you saying that the early opening in the Beaufort should disrupt the overall albedo of the entire ice pack in the Arctic Ocean, where Beaufort is very marginally placed, or what are you really saying??

[wayne]

John

I am saying that: over all sea ice is thinner year round, there is greater heat flux to the Arctic atmosphere year round, in summer there is a whole lot less of sea ice. Even 2013, I remember well with amazement the vast loose icescape. And that it is over all more conducive for cyclones, even in winter. There has always been a vortex or vortices, they spin around like tops, one always affects the others, a disturbance in the icescape , more open water, favours the presence of cyclones to persist longer, doing in turn their own spinning affecting the entire Polar vortex system, including the jet stream. Here is NASA's take:

http://globalnews.ca/news/2893850/nasa-releases-video-of-melting-polar-ice-caps/

These guys are really good, except for one of their models :(

[John Christensen]

"in summer there is a whole lot less of sea ice"

Exactly how much has the sea ice area of mid-June of the Arctic Ocean dropped in the past decade - 'a whole lot'??

[wayne]

'a whole lot'??

Ja:

2003 2004 2005 2006 2007
11152488 10997731 10689154 10521469 10779498
2008 2009 2010 2011
10841416 10948591 10286293 10143886
2012 2013 2014 2015 2016
10133848 10844208 10580914 10283797 9993628

[John Christensen]

So the ice extent is down 10% from 12 years ago.

However, the NH snow cover has been in top-4 negative anomaly since February 2016, with a June negative anomaly of 3.8MKM2 - roughly four times as much as the sea ice anomaly.

This has brought the snow less land areas of June 2016 much closer to the Arctic Ocean, supporting the barocline.

If you want to refute that you can calculate the respective albedo values.

[Susan Anderson]

I'm getting a suggestion on the side that what is going on is not entirely different from a Sudden Stratospheric Warming (SSW) which normally happens in winter. I'm skeptical, but would like an expert opinion. My meteorologist friend responded to the suggestion with this (a couple of days ago):

I think it looks like a classic polar vortex cutoff low that is now centered just west of Ellsmere Island. Usually, such a strong vortex only occurs in winter, but this thing is definitely something new as far as I can tell. Granted, polar vortex circulations are much larger in winter and cover most of the sub-Arctic on average while also sometimes becoming displaced over Canada or Siberia with all that means for unseasonable cold and storminess for the affected areas. But until now, as the vortex circulation has shrunk during the summer it has also become much weaker, not like this monster! Typical SSWs occur when a very warm flow enters the Stratosphere off the Tibetan Plateau and the Himalayas which stick way up into the tropopause and lower stratosphere during winter. But this feature just looks too unique with its own developmental sequence that most likely can be attributed to the warming Arctic Basin and lessening of sea ice than what used to be.

I also include this link to a neat BBC exposition for anyone needing a refresher on SSW (2:22 minutes). As I remember it, SSW's are followed by months of cold. https://www.youtube.com/watch?v=gps2Q1n8oZE

wrt my off topic to viddaloo, Tamino's link was all about mathematics. Sorry it didn't occur to me how it would appear. I'll try to avoid going too far off the reservation again.

[Bill Fothergill]

@ Wayne & John C

In fairness, the question asked was... "Exactly how much has the sea ice area of mid-June of the Arctic Ocean dropped in the past decade?"

Comparing individual daily values from one year to the next is rather fraught: one can certainly make the case that the monthly average for June is likely to be more indicative of any underlying trend. (Although a decade is far too short to have any real statistical significance.)

Using the NSIDC monthly averages (in millions of square kilometres) for the average June Arctic sea ice area over the last 10 years...

2006 8.36
2007 8.18
2008 8.8
2009 9.21
2010 8.3
2011 8.48
2012 8.07
2013 8.9
2014 8.71
2015 8.66
2016 8.09

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/

Using Excel's SLOPE function to do the work for me, by my reckoning, the period 2006-2016 exhibits a loss of approximately 5 thousand sq kms per annum for the June averages.

[wayne]

Susan,

That was a good opinion indeed!

Bill,

naa, daily extent numbers capture the moment, an average messes up this image.

John,

A couple of things, saying that there is low pressure heights at the Pole during summer is like saying there is always high pressure heights at the equator. Snow is a good topic, it varies a great deal, as was this year. The over all larger polar vortex, may be affected by where it lasts longer.

[John Christensen]

Much appreciated, thank you Bill!

In addition, your number is for the full NH SIA and not just the Arctic Ocean SIA, where the anomaly should be somewhat less, since e.g. Hudson and the other most southerly seas do not apply.

Therefore, with the significantly reduced snow cover, as argued by Serreze and Barrett, the conditions for developing the barocline have improved.

All of that being said, I am just saying that we are still using the same framework to understand what is happening: The NH temperature increases would explain why the cyclonic weather pattern appear to have strengthened, and why cyclones could possibly endure longer towards the end of August, compared to the 'old normal'.

[shwarzbarry]

Neven,

In the short term it's [MASIE] probably the most accurate product, because human operational analysts look at a large set of data sources to determine where the ice edge is.

Thanks for the reply. Why, then, has MASIE been little mentioned here while positing ASI is in 3rd place for the last few weeks? Having been following MASIE and noting the disparity, I wondered if this product had been abandoned for some reason, in favour of the less precise long-term SI coverage products.

MASIE has had 2016 leading or equal to 2012 over the last few weeks, so why were other products referred to and MASIE ignored when MASIE is supposedly more accurate for near real-time observations of extent? Today again, MASIE has sea ice extent lower than 2012. What am I to make of that?

[Jim Hunt]

Phase 3 of GAC 2016 is now down to 971 hPa:

http://GreatWhiteCon.info/2016/08/the-great-arctic-cyclone-of-2016/#Aug-22

There's also high pressure over Greenland, although 400 pixels aren't enough to show it! Note the closely packed isobars at the bottom right of the image however.

[Kevin McKinney]

Hi, AbbottIsGone--

One (fruitful, I hope) way to think of the greenhouse effect's patterns of warming is that they don't involve so much actual warming as diminished cooling.

So it's only logical that night-time and winter-time temperatures will be the most affected. A pretty stark example is the DMI 'north of 80' temperature reanalysis: there's little change over the years in summer temps, but marked warming for the winter months.

[Rob Dekker]

Hi John,
You make a valid argument, and it may indeed be that due to land snow cover decline in summer that summer cyclones on the Arctic would become more commonplace.
Two questions about that :

1) Is there any evidence that cyclones in summer became more common when ice extent (or land snow cover) was low ?

2) If 1) is true, then did these cyclones "help preserve the sea ice" as you assert ?

[John Christensen]

Hi Rob,

Thank you, and I suspect these arguments to be valid.
Here is what Serreze and Barrett found:

1) Is there any evidence that cyclones in summer became more common when ice extent (or land snow cover) was low ?

Yes, indeed, as has been found by Serreze, Ogi et al, and others.

Ogi et al (The summertime annular mode in the Northern Hemisphere and its linkage to the winter mode, 2004) said:

"The wintertime NAM/AO is linked to the summer atmospheric circulation. Summer atmospheric anomalies are similar to the summer NAM. The winter NAM and subsequent summer NAM have significant lagged correlations.
The link between the winter NAM and the summer NAM can be interpreted as a preferred transition from one mode in winter to a similar mode in summer. For example, a winter circulation in a positive phase of the winter NAM is likely to be followed by a summer circulation in a positive phase of the summer NAM. Similarly, negative phase will likely follow negative phase. The continuation of the same phase in summer is possibly facilitated by springtime boundary conditions such as snow cover, as suggested by Ogi et al. [2003a, 2003b]. When the polarity of the winter NAO/AO is positive, spring-summer snow cover over the Arctic coasts of Eurasia and North America is reduced, which in turn enhances the meridional thermal contrast between the colder Arctic Ocean and the surrounding warmer continents.
The larger thermal contrast could favor a positive polarity of the summer NAM by triggering enhanced eddy activity along the Arctic frontal zone [Serreze et al., 2001]."

[John Christensen]

2) If 1) is true, then did these cyclones "help preserve the sea ice" as you assert ?

Yes, see Screen et al 2011 (Dramatic interannual changes of perennial Arctic sea ice linked to abnormal summer storm activity), from the abstract, as referred by Neven back in 2013 in 'On Persistent Cyclones':

"Strong relationships are revealed between the September sea ice changes and the number of cyclones in the preceding late spring and early summer. In particular, fewer cyclones over the central Arctic Ocean during the months of May, June, and July appear to favor a low sea ice area at the end of the melt season. Years with large losses of sea ice are characterized by abnormal cyclone distributions and tracks: they lack the normal maximum in cyclone activity over the central Arctic Ocean, and cyclones that track from Eurasia into the central Arctic are largely absent. Fewer storms are associated with above‐average mean sea level pressure, strengthened anticyclonic winds, an intensification of the transpolar drift stream, and reduced cloud cover, all of which favor ice melt.
It is also shown that a strengthening of the central Arctic cyclone maximum helps preserve the ice cover, although the association is weaker than that between low cyclone activity and reduced sea ice. The results suggest that changes in cyclone occurrence during late spring and early summer have preconditioning effects on the sea ice cover and exert a strong influence on the amount of sea ice that survives the melt season."

[John Christensen]

Screen et al (2011) also observe:

"In addition to the fewer cyclones in the central Arctic during ILYs [Ice Loss Years], the most striking difference between the cyclone trajectories in ILYs and IGYs is the almost complete absence of cyclones tracking from the North Atlantic, the Greenland, Norwegian and Barents Seas, and northern Eurasia into the central Arctic during ILYs. During IGYs [Ice Gain Years], a substantial number of cyclones form in these regions, migrate poleward and reach the central Arctic Ocean."

[John Christensen]

And finally, Screen et al also reconfirm the atmospheric patterns associated with ILYs and IGYs:

"In the ILYs, a high pressure center is located in the Beaufort Sea and pressures above 1014 hPa are found over most of the Arctic Ocean. The wind is predominantly anticyclonic with a local closed circulation in the Beaufort Sea and a larger jetlike circulation from the Chukchi Sea toward the Barents Sea.
By contrast in the IGYs, the Beaufort Sea high pressure center is much weaker and smaller, and there is low pressure centered over the central Arctic Ocean but extending to much of the basin. The wind is predominantly cyclonic around a midpoint in the central Arctic Ocean."

I would say this summer fits the typical IGY quite well.

[John Christensen]

If anyone did not notice yet, 2016 is not an outlier, as we had predominantly positive AO index during the preceding winter, which then according to literature should increase the probability of positive AO during summer also, resulting in more cyclones.

On the other hand, 2007, 2012, and 2013 were all outliers: 2007 and 2012 were preceded by positive AO during winter, so in principle should have had cyclonic weather during summer, but this did not happen, so those years had both unfavorable winter and summer seasons, resulting in immense sea ice reductions.
2013 was just as exceptional in the sense that the preceding winter was dominated by negative AO (=increased snow cover, lower temps), but still was followed by strong cyclones in the summer of 2013, resulting in unexpected gain in ice volume from a year-over-year perspective.

[viddaloo]

I would say this summer fits the typical IGY quite well.

But you cannot seriously call 2016 an Ice Gain Year, surely? We have the lowest Annual Average Extent ever, and it's been constantly down every day since March (when it was only slightly up, before the 90–days of lowest ever daily extents).

[John Christensen]

Hi viddaloo,

Sorry, I should have elaborated; all of my comments above have been around the conditions (E.g. snow cover, sea ice, preceding winter atmospheric pattern, etc.) and how these have shaped the atmospheric pattern of this summer.

The atmospheric pattern of this summer fits that described for a typical ice gain year, as decribed by Screen et al, but that is far from saying we will have more ice than a year ago. That will not happen as we were already about 1,000KM3 short by the beginning of the month, and we should be further behind 2015 volume by Sept. 1 due to the current cyclones.

If you read the articles - or Neven's excellent blog entry 'On Persistent Cyclones' - you will see that cyclones tend to preserve sea ice, when they occur in June/July, but that there is no preserving effect for late season cyclones. And this is what we are all looking at, as it is rare to have a large cyclone roaming the CAB this late in August.

[viddaloo]

Good, thanks for your informative explanation.

The latest Ice Gain Year in terms of a higher Annual Average Extent at the end of the year compared to the last before that, is 2013, that of course gained tremendously compared to 2012.

In Norway we call that "jumping after Wirkola", who was an exceptional ski–jumper. 2012 finished 9.95* million km2 on Dec 31, and 2013 was 10.42. 2015 was 10.11 and 2016 is currently 9.97 million km2 AAE.

*) My 9.95 for 2012 is based on 365 days only, but 2012 was leap year, with 366 days. With all 366 days the average extent for 2012 is higher than the current 2016 average of 9.97 million km2.

[John Christensen]

To assess the impact of atmospheric pattern changes on ice melting, I prefer looking at ice volume, and if you look at June-July PIOMAS numbers(Roughly day 150-210), then you will see that the melting in 2015 was 12,718KM3, while in 2016 it was just 11,996KM3 in the same period, although by June 1st we thought we were going to see a continuation of the rapid extent and volume decline achieved during spring.

[wayne]

PIOMAS numbers? Hoy mate, PIOMAS has had no systematic grid in site confirmation to its credit. It is a model, like DMI north of 80, like there is no Upper Air sounding over the entire Arctic Ocean, again a model interpolation for data. Being skeptical of their outputs is a healthy practice.

[wayne]

Despite what an ancient 2007 paper says, in terns of recent iceless events, thinner sea ice and much more wide open water have had a huge impact on the entire Arctic circulation system, these recent strong Cyclones are a sign of the times. There has been no equivalents when there was more ice. Yes, there has been small little cyclone spin offs born from on a larger cyclone in the past with healthier ice cap, but they dropped dead rather quickly. Now cyclones last and spin new ones, and last to spin new ones.

[John Christensen]

Well wayne, I really think it is OK to use PIOMAS as a source for a reasoned argument, and most reasoned contributors on this blog seem to share that idea, given the monthly updates and consequent discussions.

You can also dismiss papers from the NSIDC and other research labs in a broad sweep, it just does not bring you much credibility.

[wayne]

Your credibility is not in question, your grasp of the subject is!

[John Christensen]

Well, I guess you can put me in that boat together with the NSIDC, the PIOMAS team at the University of Washington, and others posting on this subject in the Journal of Geophysical Research - I really do not mind.

[wayne]

Using models is OK, with a skeptical mind. The best models have verification observations, such as very capable Global Temperature models. Thousands of stations to prove them right. Some do not have anything, PIOMAS for instance. My credibility is unfortunately made by my predictions, of course which came through. Nothing serious, just reality was foreseen.

http://eh2r.blogspot.ca/2016/04/2016-annual-spring-projection-made-by.html

My peer is the future , not an obsessed over the AO Dane.

[John Christensen]

At least I share that obsession with the scientific community.. ;-)

[wayne]

John,

Oh really? Is that why they fail ? By using the AO? They are better than that...

[viddaloo]

To assess the impact of atmospheric pattern changes on ice melting, I prefer looking at ice volume, and if you look at June-July PIOMAS numbers(Roughly day 150-210), then you will see that the melting in 2015 was 12,718KM3, while in 2016 it was just 11,996KM3 in the same period, although by June 1st we thought we were going to see a continuation of the rapid extent and volume decline achieved during spring.

Fine, but choosing only 2 months for determining 'Ice Gain' versus 'Ice Loss' seems a bit like cherrypicking. If we look at PIOMAS volume, again in an Annual Average way, then 2015 was the latest Ice Gain Year in terms of a higher Annual Average Volume at the end of the year compared to the last before that. In fact, all 2013, 2014 and 2015 were Ice Gain Years by this measure. But 2015 only by a small margin (15.35 thousand km3, versus 15.26 in 2014) and mostly due to the first half of the year, not July—December.

Is 2016 an Ice Gain Year? Not so much! In 2016 the Annual Average Volume graph has fallen every single day. The last year to fall every day of the year was 2010. But by August 23rd 2016 has fallen way more than both 2010 and 2007, which also fell every day of the year. 1981 fell more than 2016 from Jan 1 to Aug 23, but that's a while back: On January 1st 1981 annual average volume was close to 25000 km3, while January 1st 2016 AAV rounds down to 15000 km3. And no single day in 2016 had *daily* sea ice volume above 23000 km3.

So for year–over–year 'net' ice volume loss, 2016 is the greatest Ice Loss Year in at least 35 years. And that's going by PIOMAS' pretty conservative model estimates.

[John Christensen]

Hi viddaloo,

You said:

"choosing only 2 months for determining 'Ice Gain' versus 'Ice Loss' seems a bit like cherrypicking."

Now, remember what I wanted to check was:

"The atmospheric pattern of this summer fits that described for a typical ice gain year"

Therefore, I was not trying to assess the entire year, but just the statement above, and then it makes very good sense selecting data for the summer months.

[Rob Dekker]

John, thank you for your elaborate explanation of the causality pattern (winter AO causing low snow cover causing summer AO causing summer cyclones causing ice extent changes), and thank you for the scientific papers that sustain the individual steps.

I find this reasoning plausible, but because of the long chain of effects, I wonder how 'strong' the correlation is between the starting point (winter AO) and the end point (summer minimum ice extent).

If it is strong, then the effect you describe should be very useful as a predictor for summer ice extent, and thus be of interest to ARCUS/SIPN.

Also one additional question : Is there any indication that the winter AO is changing over the past decades ? Or is it simply random ?

[John Christensen]

Hi Rob - you are very welcome!

Ogi and Rigor had a great paper on this from 2013:

https://www.researchgate.net/publication/258757950_Trends_in_Arctic_sea_ice_and_the_role_of_atmospheric_circulation

They suggest a primarily cyclonic pattern from 1979-1996 and then anticyclonic from 1996-2010, and you will find in this paper specific wintertime wind patterns to look for, which could be helpful for your model.

Wintertime AO does show trends at decadal level, but does not fully follow the periods mentioned above, so I am checking if there could be a difference between AO and the NAM (Northern hemisphere Annual Mode) to explain this.

Wintertime AO index from NOAA:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/JFM_season_ao_index.shtml

[viddaloo]

Now, remember what I wanted to check was:

"The atmospheric pattern of this summer fits that described for a typical ice gain year"

Fair enough, I'm just saying your fitting 'Ice Gain Year' seems to be the worst Ice Loss Year ever in recorded history.. :)

[John Christensen]

Agreed, as I have mentioned a number of times, the positive impact of June/July 2016 has been no match for the negative impact accumulated since last fall.

Whether the negative impact of the current late summer cyclones will fully negate the positive impact from June/July is still to be seen, but may be on the balance.

[wayne]

Rob,

Using the AO for ice predictions is only coincidentally useful. Has no real value or high precision expertise in doing so. It is too big, it is clumsy by size, has huge disparities, like AO+ can have a huge high in the Arctic. Furthermore most times has no meaning, like now when cyclones are pulverizing sea ice, like now when Siberian temperatures are nearly equal to Arctic Ocean. It is not a surprise that those who you it or integrate it into their prediction model, fail.

[wayne]

those who use it,,,,, ultimately will have bad predictions

[D]

Wayne, I think that those papers are using large multi-year patterns that involve increased oceanic heat flow into the Arctic ocean, not the atmospheric pattern details necessary to understand why a year like 2007 had such a low sea ice extent.

There are multi-year atmospheric circulation patterns that increase the flow of Atlantic ocean water into the Arctic. The AO does show this large-scale effect. Those papers aren't wrong, but they aren't very helpful for predicting the details this years minimum extent, area and volume. They can help you understand multiple year trends and variations.

-Fish

[wayne]

Bingo ! D

"but they aren't very helpful for predicting the details this years minimum extent, area and volume. They can help you understand multiple year trends and variations."

But some people do not unfortunately think alike, so for this reason
and in memory of the late show with Paul Shaffer (the real genius on late night with D L):

Here is top ten reasons why the AO is a marginal, low signal bearing, incompetent prediction tool for sea ice:

#1 It does explain something, it is a convenient simplification of pressure over a huge area of our planet. That is what it is mainly used for. Not for sea ice :C

#2 It has to be interpreted differently depending on location and time. So predicting AO+ for June and July means cooling, for somewhere in the Northern world not necessarily the Arctic. AO- means more insolation for somewhere in the world. The same can be applied for any season or period of the year.

#3 Less or more atmospheric pressure can be a destructive or constructive force for sea ice at different times of the year, so this is how AO index is not used correctly. For instance, in winter AO- including a HIGH over Beaufort area can be very destructive for sea ice, AO+ with a persistent LOW over Beaufort is a destructive element for sea ice as well., less accretion. Null is the result of its usage for predictions then.

#4 – Lets say dominant AO+ is calculated to be for the summer, the logical conclusion would be to assume a cool Arctic. As is often the case, not so, in June and July a dominant AO+ may also have lower pressure in the Arctic, many South in origin Cyclones have destructive powers over sea ice especially on the ice pack shores, again AO+ or AO- may be destructive or preservative for sea ice.

#5 Integration of AO index into sea ice models would give tragically confusing outputs. I am sure big computers with AI would love to be called HIP. But its better being the Tragically HIP, rock on Gordie!

#6 The AO has no predictive powers over where the LOWS or HIGHS would be, it is a bland general indication index for Global circulation implications. Usually has some importance over temperatures due to the inferred trans locations of the jet stream associated with Pressure distribution over the entire Northern Hemisphere.

#7 Using the AO in a very specialized way, segmenting it for every little detail per region is a waste of time, because it is better to use the actual causations of Higher or Lower pressures, ie , planetary waves, sea water temperatures, extent and thickness of sea ice and snow on ground. AO can't explain where they are.

#8 A prediction of AO + or - is not strictly dedicated to the Arctic, even though the name: ARCTIC with Oscillation.

#9 AO’s don’t explain where snow is going to fall during winter, snow extent on the ground has huge implications for general circulation of the Polar vortex.

#10 Those who use AO as a predictive tool have to break down the weather image per region, and spend a great deal of effort explaining what a Lower or Higher pressure for a good segment the entire Northern Hemisphere has to do with their region. As often the case a AO+ or - has different meaning, depending on the real space, time and other weather factors, the latter should be more carefully scrutinized. Forcing the AO into the picture is to put it simply: quite silly!

[John Christensen]

A couple of months ago I tested this hypothesis and added it somewhere on this blog:

What if positive AO (increased cloudiness) during Oct-Dec and negative AO (clear skies) during Apr-June would make enough impact on solar radiation on surface temperatures to have any impact on summer Arctic sea ice melting?

Sorted with highest number (most cloudy in late fall and most clear skies in late spring) to lowest, this is how the latest 10 years came out (Note that I only had April and May 2016 available for this, so assumed June '16 would be neutral):

Year Fall/spring AO influence
2012 1,67
2016 1,42
2014 0,95
2008 0,81
2009 0,53
2007 0,30
2006 -1,07
2010 -1,10
2015 -1,22
2013 -1,58
2011 -1,62

Since this list placed 2012 1st, 2016 2nd, and 2013 second last, I would say the AO has some predictive skill, although it is just one factor to consider.

[wayne]

Common John

What to make of 2007?

tisk tisk

[wayne]

And my goodness, 2008, man was it sunny then. I got hundreds more sun pictures than usual to prove it!

[Rob Dekker]

John said :

What if positive AO (increased cloudiness) during Oct-Dec and negative AO (clear skies) during Apr-June would make enough impact on solar radiation on surface temperatures to have any impact on summer Arctic sea ice melting?

To see if there is something to this argument (of winter/spring AO affecting Sea ice minimum), I decided to run your (2006-2015) AOwinter - AOspring numbers through linear regression against the September ice extent numbers.

The result is interesting. The correlation R = -0.415, which is not particularly good (only explains 17 % of the variance in Sept ice extent), but it is not bad either (it is better than linear extrapolation).
Also the sign is as expected : High AO in winter followed by low AO in spring cause a decrease in Sept sea ice minimum. That is encouraging.

On the other hand, to be frank, your time period (of just 10 years) is too short. Linear regression takes 2 data points away, so with 8 data points there is a significant risk of statistical "over-fitting" (so the 17% is optimistic).

So predictive value of this AO formula is not strong, but may serve as an loose indicator of what's to come the next summer.

P.S. Your AO formula would have predicted 4.45 for 2012 and predicts 4.50 for 2016. Standard deviation 560 k km^2.

[John Christensen]

Hi Rob,

I will get back to you on the note above, but also wanted to share this article from 2010 by Ogi and Yamazaki, where the statistic correlation between summer AO (NAM in this paper) and Sept SIE is discussed.
It also addresses long-term trends in the AO index:

https://www.researchgate.net/publication/44444524_Trends_in_the_Summer_Northern_Annular_Mode_and_Arctic_Sea_Ice