Arctic Sea Ice Extent, Area, and Volume

[csnavywx]

Can gradually see the late season ice pack of the next decade taking shape this time of year. 2016 and this year are good examples with a solid compacted half moon-shaped slab up against the CAA where the remaining MYI is located and an arc of weakened FYI from the Beaufort side right across the pole. A warmer summer would have melted that arc and left the MYI in place.

Weather gets much more hostile over the next few days, which will open the Pacific bite up even more, but it's much too late in the season for any of the compacted FYI/MYI to be melted away. It could definitely make a run at tying last year or 2007, though and leave a lot of scattered patches at the minimum. As we saw last year, that tends to re-freeze pretty quickly in late Sep and Oct. Just not quite warm enough to maintain open ocean that far north yet.

[ORH_wxman]

Update for 2017....

 

Extent is still tracking pretty low...basically in a dead heat right now with 2016 for 4th lowest, though I would be surprised if it kept up pace since 2016 had breathtaking losses late in the month with a ton of vulnerable nearly-melted-out ice in the ESS and managed to finish 2nd lowest...2017 has no such vast areas so vulnerable, so we'd expect a slowdown relative to 2016. That said, there is still room for a pretty low result, top 5 lowest is still definitely within reach and you still cannot quite rule out 2nd lowest if the weather was absolutely hostile to the max. But the race may be more with 2011/2015.

 

Area is a bit of a different story...the ice is pretty compact...not nearly as spread out as some other years. So area is running higher than extent in the rankings.

 

Here are the August 17th (based on 8/16 satellite scan) area numbers by year:

2017: 3.69 million sq km

2016: 3.26

2015: 3.51

2014: 4.53

2013: 4.10

2012: 2.92

2011: 3.32

2010: 3.92

2009: 3.95

2008: 3.67

2007: 3.23

 

 

2008 is currently the closest match, then 2015 is next closest. 2008 finished at 3.00 million sq km while 2015 finished at 3.09 million sq km. The ice pack is currently more compact than both of those years so it wouldn't be shocking if it finished higher...however, it is also probably thinner out on the PAC side, so that could offset the compactness some and still produce area losses that are more comparable to a dispersed ice pack....weather of course will be a factor too, so we'll just have to see. A finish anywhere from 3rd lowest to 7th lowest is still plausible on area...I think 2012 and 2016 are now safely out of reach as well as 2009, 2013, and 2014.

[bluewave]

One of the greatest early August anomaly decreases on the PIOMAS with the cool and stormy pattern in the Arctic. Also among the strongest polar vortex patterns for the first half of August.  

 

 

 

 

 

 

 

[PhillipS]

Apologies if I'm splitting hairs, Bluewave, but August didn't see an increase in Arctic SIV, it saw a decrease in the anomaly.  Arctic SIV continued to drop, albeit at a slower rate.  

[bluewave]

7 hours ago, PhillipS said:

Apologies if I'm splitting hairs, Bluewave, but August didn't see an increase in Arctic SIV, it saw a decrease in the anomaly.  Arctic SIV continued to drop, albeit at a slower rate.  

 

No problem. We may be able to further decline the anomaly if we can avoid the historic warmth that we saw last Oct-Dec. That may set the volume up to come into next summer a little better than we saw this year. The state of the sea ice next summer will then come down whether the less hostile 2013-2017 stronger polar vortex pattern can prevail another year. Or the 2007-2012 dipole pattern makes a return. Be interesting to see how many more years the 2012 can hold on. The reversal of the summer pattern in 2013 turned out to be a surprise that people didn't think was possible during the fall of 2012. But some studies came out in early 2013 that mentioned this possibility. Long term sea ice decline with increases or decreases in the short term rate.

[ORH_wxman]

26 minutes ago, Weatherdude88 said:

We are currently in an unprecedented slow down in this melting season. Looking at JAXA sea ice extent data for the past 5 days (8.14-8.20), here is how this year compares to previous years. All of this in a time frame were weather was considered unfavorable by most. Where is the heat? 

 

 

We had a really compact ice pack with very few regions of very low concentration so it is not a huge surprise that we've seen a stall in extent while area has resumed its drop (after stalling earlier). The weather was never that great for losing a lot of extent this past week...we did get that cyclone earlier, but it never got nearly as intense as the 2012 cyclone and it occurred over a pack that was not nearly as shredded as 2012.

 

 

[ORH_wxman]

6 minutes ago, Weatherdude88 said:

 

 

Hence my earlier comment. Extent was bound to fall more in line with area before the end of the melt season, where historically we generally see a less compact northern hemisphere cryosphere. The positioning of the high latitude ice was "icing" on the cake. We may indeed see a record early minimum this year. My prediction is August 31st. Let's see what happens.

 

We would need perfect weather I think to get a minimum in August for extent...I don't think it's ever happened in the jaxa record. Earliest I could find was 9/1 in 1997...looks like 1988 was 9/2. It admittedly might be a little easier to get a min in August with less ice extent than previous years if there's some open water pretty close to the pole...as that will tend to freeze much earlier than the peripheral areas. We sort of saw this last year when we had a min on 9/7...pretty early.

Area has twice had minimums in August...2005 and 1986 I believe. Both were on August 31st I believe.

[Sundog]

20 hours ago, ORH_wxman said:

We would need perfect weather I think to get a minimum in August for extent...I don't think it's ever happened in the jaxa record. Earliest I could find was 9/1 in 1997...looks like 1988 was 9/2. It admittedly might be a little easier to get a min in August with less ice extent than previous years if there's some open water pretty close to the pole...as that will tend to freeze much earlier than the peripheral areas. We sort of saw this last year when we had a min on 9/7...pretty early.

Area has twice had minimums in August...2005 and 1986 I believe. Both were on August 31st I believe.

 

I would be more impressed with early minimums decades ago when the ice was much more widespread and therefore had more vulnerable ice to give back. 

 

Getting an early minimum when all the easy ice is already melted and all we have is a compact core left is not as impressive, it's almost expected.  

 

What is impressive is how we continue to shed ice most years despite losing all the vulnerable ice well before the end of the season. Shows you how pathetic the cryosphere has been over the last 15 years. 

[ORH_wxman]

44 minutes ago, Sundog said:

 

I would be more impressed with early minimums decades ago when the ice was much more widespread and therefore had more vulnerable ice to give back. 

 

Getting an early minimum when all the easy ice is already melted and all we have is a compact core left is not as impressive, it's almost expected.  

 

What is impressive is how we continue to shed ice most years despite losing all the vulnerable ice well before the end of the season. Shows you how pathetic the cryosphere has been over the last 15 years. 

There hasn't been any trend in minimum date since records began...but it's possible we start seeing it trend earlier if we get more years with open water close to the pole. But years like 2007 and 2012 had pretty late minimums...so the open waters those years did not facilitate early mins. It is still almost entirely weather dependent.

[stadiumwave]

1 hour ago, Sundog said:

 

I would be more impressed with early minimums decades ago when the ice was much more widespread and therefore had more vulnerable ice to give back. 

 

Getting an early minimum when all the easy ice is already melted and all we have is a compact core left is not as impressive, it's almost expected.  

 

What is impressive is how we continue to shed ice most years despite losing all the vulnerable ice well before the end of the season. Shows you how pathetic the cryosphere has been over the last 15 years. 

 

Lol...ok

[BillT]

how would the area and extent of a baseball diamond differ?    isnt the extent of the field also its area expressed in square meters? how far something extends is part of its AREA of coverage isnt it?

[ORH_wxman]

5 minutes ago, BillT said:

how would the area and extent of a baseball diamond differ?    isnt the extent of the field also its area expressed is square meters? how far something extends is part of its AREA of coverage isnt it?

The definition of extent is anywhere within a grid cell that is >15% ice coverage/concentration. So if a 10km by 10km grid cell had 50% ice concentration, then it is classified as 100km² of ice extent. However, area calculates this as 50km² of ice coverage because it takes concentration into account. The reason we even had extent in the first place is because we didn't have satellites that could view the ice in very high resolution...the grid cells were typically 25km by 25km....because ice moves a lot and the satellites also pick up some false ice or false water (when melt ponding occurs), the extent method was deemed more consistent and a conservative measurement of the ice.

As we get higher and higher resolution of satellites, we will probably eventually get to the point where area is equal to extent. But for historical comparison, NASA still uses the 25km grid size method...using a smaller one like from AMSR2 (as low as 3km) and comparing it to 25km cells wouldn't be an apples to apples comparison. JAXA has tried to adjust for these differences in their own historical data.

[BillT]

ty for the answer so it is 2 ways of expressing the SAME amount of ice that shows a very different picture, of the SAME amount of ice.....

[Jonger]

2 years in a row with a brick wall ending.

We might not go below 5 km2 on Jaxa.

50/50 on that one.

[ORH_wxman]

33 minutes ago, Jonger said:

2 years in a row with a brick wall ending.

We might not go below 5 km2 on Jaxa.

50/50 on that one.

There is zero chance we stay above 5 million sq km on jaxa...we are already down to 5,047,907 on jaxa. The lowest loss in recent years I could find between now and the min was 2014 when we lost only 500k of extent. If you go back to 2006, then that year lost only 300k from here to the min. Most years seem to lose between 600-800k of extent from here on out which would put us in the 4.2-4.4 range. A couple years lost around 900k...so we could end up as low as 4.1 or as high as 4.7 if we use the extremes as end points.

We prob won't lose the higher amounts given how compact the ice pack is, but we will still easily be in the mid 4s on jaxa without a problem IMHO.

 

NSIDC is a different story as it tends to run about 200k higher...jaxa had that revision in their method about 3 years ago which made it less compatible with NSIDC.

[Sophisticated Skeptic]

On 8/21/2017 at 10:30 AM, Weatherdude88 said:

We are currently in an unprecedented slow down in this melting season. Looking at JAXA sea ice extent data for the past 5 days (8.14-8.20), here is how this year compares to previous years. All of this in a time frame were weather was considered unfavorable by most. Where is the heat? 

 

 

 

It's called bio-engineering to the rescue.

[WinterWxLuvr]

3 hours ago, Sophisticated Skeptic said:

 

It's called bio-engineering to the rescue.

That would likely be the death of us all.

[Sophisticated Skeptic]

On 8/22/2017 at 8:05 PM, WinterWxLuvr said:

That would likely be the death of us all.

 

I dunno. It could help at times as well.

Like if they dropped a few million tons of ice cubes in the Gulf ahead of Harvey right now.  Otherwise that thing is gonna go to town.  88 degree water temps in it's path.

[ORH_wxman]

1 hour ago, bluewave said:

NSIDC is currently tracking between 2015 and 2016. The September average extent in 2015 was 4.63 million sq km and 4.72 in 2016. The 2012 record of 3.61 remains elusive since the dipole pattern reversed in 2013.

Both 2015 and 2016 had extreme losses in extent the final week of August, so I'd expect 2017 to separate from them more by 9/1 on NSIDC. Jaxa is a little less obvious as 2015 didn't have as steep a drop late as NSIDC had.

The U Bremen AMSR2 is probably a little more like NSIDC:

 

 

 

[WidreMann]

11 hours ago, ORH_wxman said:

Both 2015 and 2016 had extreme losses in extent the final week of August, so I'd expect 2017 to separate from them more by 9/1 on NSIDC. Jaxa is a little less obvious as 2015 didn't have as steep a drop late as NSIDC had.

The U Bremen AMSR2 is probably a little more like NSIDC:

 

 

 

Temperatures are now averaging above normal 80 north and neither the GFS nor Euro look great for continued cold temps. At least we don't have big storms messing things up. That's the saving grace. I bet we'll see a drop in the next two weeks, but it seems majorly unlikely to beat 2012, or even last year, I think.

[bluewave]

Update from NSIDC:

https://nsidc.org/arcticseaicenews/

Ice retreat from August 1 to August 21 averaged 73,000 square kilometers (28,000 square miles) per day. This was faster than the 1981 to 2010 average rates of ice loss of 57,300 square kilometers (22,000 square miles) per day, but slower than in 2012, which exhibited the fastest rate of ice loss compared to any other August in the passive microwave satellite data record. Normally the rate of ice retreat slows in August as the sun starts to dip lower in the sky. The rate of ice loss was more rapid at the beginning of August, slowing down considerably starting on August 17.

Air temperatures the first two weeks of August were 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) cooler than the 1981 to 2010 average throughout the Arctic Ocean and over Greenland and the North Atlantic. The lowest air temperatures relative to the long-term average were found in coastal regions of the Kara and Barents Seas, continuing the pattern seen throughout much of this summer. Cooler than average conditions within the Central Arctic were a result of persistent cold-core cyclones. These cyclones have not been as large or as strong as the Great Arctic Cyclones of 2012 and 2016, despite the central pressure of one of these systems dropping down to 974 hPa on August 10. In addition, these cyclones are located closer towards the pole within the consolidated ice pack, where they are less likely to cause significant ice loss, as did the 2012 Great Arctic Cyclone in the Chukchi Sea.

While air temperatures start to drop in August, ice melt continues through the month as heat gained in the ocean mixed layer during summer continues to melt the ice from below and from the sides. Sea surface temperatures have been up to 5 degrees Celsius (9 degrees Fahrenheit) above average near the coastal regions, but generally near average or slightly below average along the ice edge in the Beaufort and Chukchi Seas

[Jonger]

On 8/22/2017 at 8:05 PM, WinterWxLuvr said:

That would likely be the death of us all.

No it wouldn't.

[WinterWxLuvr]

3 hours ago, Jonger said:

No it wouldn't.

LOL, if humans were actually as smart as we think they are.

Keep dreaming.

[Poimen]

Forgive me if this is addressed elsewhere, but can someone explain the difference between the NSIDC numbers and Wipneus' numbers posted on the Arctic Sea Ice forums? According to his figures, extent and area have only declined since the 25th. Why is there such a discrepancy? 

[ORH_wxman]

2 minutes ago, Poimen said:

Forgive me if this is addressed elsewhere, but can someone explain the difference between the NSIDC numbers and Wipneus' numbers posted on the Arctic Sea Ice forums? According to his figures, extent and area have only declined since the 25th. Why is there such a discrepancy? 

One is using SSMI/S satellite, the other is using AMSR2. The SSMI/S (which is what NSIDC uses) tends to be a bit more volatile on a day to day basis...the two data sources will generally track the same direction over a period of weeks, but within a small timespan such as a few days, you might see some differences.

[raindancewx]

NSIDC has sea ice extent on 8/29/17 higher than 2007, 2011, 2012, 2015, 2016.

Outside chance the lowest extent date ends up above 2008 too?

[donsutherland1]

Arctic sea ice extent is mirroring the evolution of the summer 2014 decline very closely. That would imply a minimum figure of between 4.4 million and 4.5 million square kilometers.

https://s26.postimg.org/64xg85hrt/Arctic08292017.jpg

[bluewave]

Typical post 2012 summer with stronger polar vortex conditions preventing a challenge to the 2012 record minimum extent. This summer was right down the middle between 2013-2014 and 2015-2016.

 

 

 

 

[ORH_wxman]

PIOMAS updated for the end of August...

 

Looks like we've inched above 2016 for 4th lowest now...2011 was also lower and 2012 has gone well into the depths. Close race with 2010 too for the min volume, though I think we'll finish a little lower than 2010 but stay higher than 2016.

[ORH_wxman]

We may be on "minimum area watch" right now...On September 1st, the NSIDC (what CT SIA used when they were functioning) dropped to 2.99 million sq km. It then rebounded significantly before declining again, though the declines have been weak and we remain 130k above the minimum at 3.12 million sq km. If September 1st was indeed the minimum area, it would be the earliest area min since 2005 when the minimum occurred on August 31st. August 31st is also tied for the earliest area minimum with 1987.

If 2.99 million sq km ends up being the minimum area, this would be 5th lowest. Only 2012, 2016, 2011, and 2007 were lower...it is nearly tied with 2008 which finished at an even 3.00 million sq km. It is still possible that area makes one more push and we achieve a new low...if it drops below 2.90 million sq km, then it could surpass 2007 and 2011. But time is rapidly running out and the weather does not look conductive to a big 2nd week September area decrease. Any push would have to come from the Atlantic side most likely (and very soon in the next couple days) since there's still some southerly wind there from a Kara low...but the Pacific side may see ice growth over the next week as a very cold low moves over the CAA and adjacent CAB. 

 

In a reversal of position from mid-August, extent is currently only 6th lowest or 7th lowest depending on the source you use (jaxa vs NSIDC). Recall that extent had been running more like 3rd lowest a few weeks ago....but the higher area ranking back then suggested that the extent was unlikely to compact like last year and 2015 did late in the season, so we fell behind the pace of those years. Extent is currently at its season minimum...it is not clear when the min will occur...it might be in about 2-3 days if that cold low materializes in the CAA/CAB which will help promote ice growth in the Beaufort/adjacent areas on very cold north and east winds.