Arctic Sea Ice

2015 minimum overview, part 2

This is a continuation of Part 1, wherein I posted several graphs and maps depicting the 2015 minimum, and the weather conditions leading up to it (Tamino has a great blog post showing the long-term sea ice extent trends, all of them, not just the cherry-picked, meaningless one the GWPF selected to mislead).

Before jumping into the ice age and volume data that is (perhaps) most interesting, intriguing, but also incomplete, I want to refer to one more factor that - besides weather conditions and ocean heat flux - can play an important role in how a single melting season plays out: land snow cover.

Here are the monthly Northern Hemisphere snow cover anomaly graphs from the Rutger University Global Snow Lab during the melting season:

It's clear snow cover got pretty low during June and July. It's a bit of a chicken-or-the-egg kind of mutual influence thing, with an albedo feedback leading to warming over land, leading to increased snow melt, etc. which then starts to influence the Arctic and its sea ice as well. There's been ongoing speculation on this correlation between land snow cover and sea ice for years now, and my guess is that there's a there there, but as it isn't the only influence, it's hard to quantify it. Either way, it has to do with (global) warming, as attested by commenter Al Rodger's guest blog a few years ago: The untold drama of Northern snow cover.

And so we turn to multi-year ice. I'll repost this animation from a blog post I posted two weeks ago, showing how virtually all of the older, thicker multi-year ice on the Pacific side of the Arctic has melted out this melting season:

2015 minimum overview, part 1

A week has passed by since the melting season ended and the minimum on all sea ice extent and area graphs has been reached. During this week I've been collecting images that show various aspects of this year's melting story, which will be accompanied by short explanations/interpretations.

Such an overview must inevitably start with an image showing the shape of the ice pack, and the University of Bremen has put up a great sea ice concentration map that also shows the ice pack outlines at the end of record melting seasons 2007 and 2012, as well as the 1981-2010 average:

2012 (cyan) clearly had less ice, but there are a couple of spots where this year had less ice than in 2007 (red). The September graph for ADS-NIPR/JAXA sea ice extent shows how close 2015 came to the lower years, slipping right below 2011 and ending in 3rd position:

The same can't be said of the Cryosphere Today sea ice area graph. 2015 ended relatively low there too, but at the top of the bundle of trend lines, in 6th position:

Minimum and MYI

The lowest point has been reached on all sea ice area and extent graphs, and so the melting season has ended. I'll have more on the details later this week, but here's a quick preview of one of the most important features of this melting season, and that's the decimation of multi-year ice (MYI) on the Pacific side of the Arctic.

Here's a nice video that shows how the melting season developed and ended, based on AMSR2 data. It's made by Felicia Brise of the University of Hamburg, and I've taken the liberty to upload it to YouTube:

There's a stunning contrast between the destruction on the Pacific side of the Arctic, and the relative stable and compact situation on the Atlantic side of the Arctic, even though the ice there was thinnest at the start of the melting season. In fact, this region of first-year ice was so large that it even covered the North Pole, perhaps for the first time on record. I even speculated in my 2014/2015 Winter analysis that under the right conditions the North Pole could become ice-free this year.

But the opposite happened, the first-year ice on the Atlantic side was spared (there was also remarkably little transport of ice through Fram Strait) and it was the multi-year ice on the Pacific side that took barrage after barrage of warm, sunny weather. Now that the ice age distribution maps (developed by J. Maslanik and C. Fowler, and currently produced by M. Tschudi of CCAR) have been updated, we can see how things have proceeded since my last blog post on the subject three weeks ago:

As expected, all of the 5+-year old ice on the Pacific side of the Arctic has disappeared in truly spectacular fashion. As there wasn't that much 4-year old ice to begin with, there will be less of the oldest class of ice next year. On the other hand a lot of the 3-year old ice (green) will become 1 year older, and as said, first-year ice (dark blue) got off lightly.

Nevertheless, it seems that part of the rebound in MYI that happened since 2012 has been wiped out (something I speculated about almost two months ago in this guest blog for the Guardian Environment page). We'll know how much exactly when the NSIDC puts up their monthly analysis two weeks from now. Of course, ice age doesn't necessarily tell us how thick the ice is - this isn't our (grand)fathers' Arctic anymore - but it gives us an idea of long-term changes in the Arctic.

Another indicator is sea ice volume, both modelled and observed. To know whether 2015 will dip below rebound years 2013 and 2014, we'll also have to wait a week or two for the PIOMAS model to be updated. Either way, yet another fascinating melting season is now behind us. Thanks for watching.

ASI 2015 update 7: to compact or not to compact

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2014 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

September 1st 2015

Look at the sea ice concentration animation at the top right. Notice how the final frame suddenly is whiter than the preceding frame? That's a sign that we have entered the final phase of the melting season, when temperatures drop and melt ponds within the ice pack freeze over again. Sea ice concentration goes up, and the NSIDC SIC map becomes whiter.

But the Pacific side of the Arctic is still bluish. During the past two weeks the disintegration of that part of the ice pack has continued, spurred on by a late cyclone that further stressed the region (see special blog post on the matter) and increased the area that consists of a mix of ice floes and open water. The compaction potential of this region will probably decide where this melting season will end up on the various sea ice area and extent graphs.

And this end result still holds interest, because - somewhat surprisingly - the 2015 melting season could still achieve a top 3 minimum. Surprising, because the melting season started out with more volume, more multi-year ice, saw little and late preconditioning during May and June, and - despite a killer July - there has been relatively little transport and compaction this year.

With melting momentum mostly out of the picture now, it all comes down to compaction.

Sea ice area (SIA)

Here's the latest Cryosphere Today SIA chart, to which I've added preliminary data as calculated by Wipneus:

2015 SIPN Sea Ice Outlook: August report

The third and last Sea Ice Outlook of this year has been published. The SIO is organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2015 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Scroll down to the bottom to see the results from this year's Arctic Sea Ice Forum polls that were held at the same time as the periods preceding the SIO monthly submission deadlines.

Here's the summary for the August report:

The median August Outlook for September 2015 Arctic sea ice extent is 4.8 million square kilometers (km²), 200,000 km² lower than the June and July medians. The quartile range is 4.2 to 5.2 million km² (see Figure 1 in the Overview section, below). Contributions are based on a range of methods: statistical, dynamical models, estimates based on trends, and subjective information. The overall range (excluding an extreme outlier) is 2.7 to 5.6 million km². The low end of the range dropped substantially from July (3.3 million km²), due to one new contribution, while the high end changed only slightly from July (5.7 million km²).

The median's decrease from the June and July values reflects rather rapid ice loss during July. The drop is mostly due to lower statistical and mixed statistical/heuristic contributions (Figure 2), because these methods are generally at least partially based on extrapolation from current/previous conditions whereas modeling contributions are generally not.

Read the entire report here.

And here's the figure showing all the projections (click for a larger version):

2015 SIPN Sea Ice Outlook: July report

The second Sea Ice Outlook of this year has been published. The SIO is organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2015 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Here's the summary for the July report:

The median Outlook for September 2015 Arctic sea ice extent is 5.0 million square kilometers (km²), which is the same as the June Outlook median. The quartile range is 4.4 to 5.2 km² (see Figure 1 in the Overview section, below). Contributions are based on a range of methods: statistical, numerical models, estimates based on trends, and subjective information. The overall range (excluding an extreme outlier) is 3.3 to 5.7 million km². The median Outlook value is up from the July 2014 median value of 4.8 million km². These values compare to observed values of 4.3 million km² in 2007, 4.6 million km² in 2011, 3.6 million km² in 2012, and 5.3 million km² in 2014. In general, the heuristic approaches forecast a mean September extent around 4.1 million km², whereas the statistical and dynamical modeling approaches both suggest mean September extent near 5.1 million km², with the dynamical modeling contributions showing a narrower range.

The lack of significant change between this month and last is largely related to the fact that most contributors did not change their forecast for July. Another factor could be the lack of significant atmospheric or oceanic forcing that would result in a large change from the June forecasts. A discussion of 11 dynamical model contributions shows no major differences compared to last month's report. This month's report also includes results from three regional predictions and a discussion of current ice and atmospheric conditions.

Read the entire report here.

And here's the figure showing all the projections (click for a larger version):

The September minimums for the last 10 years (in millions km2, found here):

2015 SIPN Sea Ice Outlook: June report

The first Sea Ice Outlook of this year has been published. The SIO is organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2015 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Here's the summary for the June report:

The median Outlook value for September 2015 sea ice extent is 5.0 million square kilometers with quartiles of 4.4 and 5.2 million square kilometers (See Figure 1 in the full report, below). Contributions are based on a range of methods: statistical, numerical models, estimates based on trends, and subjective information. We have a large spread in the Outlook contributions, which is not surprising given the wide-ranging observed values for the September extent in the past few years. The overall range (excluding an extreme outlier) is 3.3 to 5.7 million square kilometers. The median Outlook value is up from 4.7 million square kilometers in 2014. These values compare to observed values of 4.3 million square kilometers in 2007, 4.6 million square kilometers in 2011, 3.6 million square kilometers in 2012 and 5.3 million square kilometers in 2014.

Read the entire report here.

And here's the figure showing all the projections (click for a larger version):

The September minimums for the last 10 years (in millions km2, found here):

    2005: 5.57
    2006: 5.92
    2007: 4.30
    2008: 4.73
    2009: 5.39
    2010: 4.93
    2011: 4.63
    2012: 3.63
    2013: 5.35
    2014: 5.28

Again, it's nice to see some people who comment here and /or on the Forum to have again submitted contributions, like Rennie, Cole, Hamilton, Dekker and of course Chris Reynolds. Chris' projection of 5.15 million km2 for the September average is right between that of Schröder's 5.1 million km2 - whose projection I discussed in this recent blog post concerning melt ponds during May- and that of Zhang's 5.2 million km2, based on the PIOMAS model. These are among the best sources of projections (melt ponds and ice thickness) in my opinion, and so Chris' projection looks well-based and solid for the time being.

SIPN Call for Contributions to 2015 Sea Ice Outlook

Most of you interested in this and thinking about contributing a prediction, probably know about it already, but for those of you who don't: you can send in your prediction to the Sea Ice Outlook as organised by the Sea Ice Prediction Network under the umbrella of the Arctic Research Consortium of the United States (ARCUS).

Details are below:

The Sea Ice Prediction Network (SIPN) announces a call for Sea Ice
Outlook (SIO) contributions to the June report (based on May data):

- The firm submission deadline is 6:00 p.m. (AKDT) on Friday, 12 June 2015.
- Guidelines for contributors can be found at:
http://www.arcus.org/sipn/sea-ice-outlook/2015/june/call
- All submissions should be sent to: sio2015@arcus.org

The Sea Ice Outlook (SIO) provides an open process for those interested in Arctic sea ice to share predictions and ideas about the monthly September minimum sea ice extent. The monthly reports contain a variety of perspectives from advanced numerical models to qualitative perspectives from citizen scientists. All past contributors as well as new participants are encouraged to submit Outlooks this year. A post-season report will provide an in-depth analysis of factors driving sea ice extent this summer as well as explore the scientific methods for predicting seasonal ice extent.

For the June Outlook report, pan-Arctic and regional outlooks will be accepted and spatial forecasts and maps are particularly encouraged. A short executive summary and summary of methods are required this year.

Contributors should review the submission guidelines for detailed instructions and templates including:

- Core requirements for pan-Arctic contributions,
- Additional (optional) items for pan-Arctic contributions,
- Regional Outlooks, and
- Figures and data.

Detailed submission guidelines for contributions are available at:
http://www.arcus.org/sipn/sea-ice-outlook/2015/june/call.

For questions, contact Betsy Turner-Bogren, ARCUS
Email: betsy@arcus.org

Naturally, I'll be reporting on the SIO every month (as I do every year). After all, predicting the annual outcome of the melting season is one of the most exciting scientific challenges in cryospheric sciences.

ASI 2014 update 9: minimum around the corner

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2013 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

September 14th 2014

The 2014 melting season is about to end. The end result is very similar to that of last year, despite large differences between both melting seasons. Last year the Arctic was dominated by persistent cyclones, keeping things cold and cloudy. This year there were more bouts of sunny weather, but it seems little heat was imported from lower latitudes. A lack of strong pressure gradients also caused relatively little movement and export, clearly to be seen on the Atlantic side of the Arctic, where in the last couple of years (even last year, see here) an onslaught had taken place.

At the same time, on the Pacific side of the Arctic, the ice that had been strengthened due to last year's rebound, managed to hold out through much of the melting season, although the late momentum seems to be sustaining the melting season now (together with weather, of course). Large areas of very thin ice and milky wisps in the Beaufort, Chukchi and Eastern Siberian Seas are disappearing, keeping many a trend line dropping on sea ice graphs.

But most of this weak ice will be saved by the bell, like we saw in 2010 and 2011, and the 2014 melting season will basically end up at the same level as last year and 2009. If not today, then later this week.

Sea ice area (SIA)

The season may already have turned the corner on the Cryosphere Today graph, after having dipped 71K below last year's minimum on the same date as last year:

Pinpointing the minimum

UPDATE September 16th:

Given another uptick and the current weather forecast, I'm ready to call the minimum for IJIS SIE V1 on September 12th at 5,000,313 km2. Apparently the high was too big and the pressure gradient too low to prolong things (see below).

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This blog post should perhaps have been written last week, but better late than never, right? Although it could even be too late, as the minimum might have occured already in some data sets. But if there's one thing I did right on this blog so far, it's calling the IJIS sea ice extent minimum! So let's forget all the rest and keep doing what we're good at.

Pinpointing the minimum is a slightly tricky business, especially this year with all the thin ice that didn't melt out. On the one hand this causes a lot of compaction (and some last melting) potential, but this might be offset by faster freeze-up due to all the open water between floes. Either way, it's the atmospheric situation that determines when the minimum occurs in September.

I personally re-invented this wheel back in 2010, the first melting season that was covered on the Arctic Sea Ice Blog, when comparing the end of the melting season with previous ones in a series called End Zone. In the third instalment I covered the influence of atmospheric pressure on the timing of season's end. As I wrote at the time: