Arctic Ice Movember Update

Click on image to enlarge

Arctic Ice Extents have roughly doubled since the Sept. minimum and are now up to 10M km2.  The last 1/3 of maximum will take until March, principally because several basins are frozen over and cannot add coverage.  To date, Beaufort and CAA (Canadian Archipelago) are full, as are Laptev and East Siberian on the Russian side.  Kara is 3/4 covered and the Central Arctic wil add only 3% from here.

During the first half of November we can see at the bottom Beaufort  and East Siberian filling in, leaving only Chukchi with open water.  On the right, Both Baffin and Hudson bays are now growing more strongly.   At the top Kara ice extent has reached 75% of its March maximum.

The graph compares extents over the first 17 days of November.
NHday321

2017 has reached 9.9M km2, 2007 nearly the same, and both are close to the 10 year average of 10M km2.  2012 lags 300k km2 lower than 2017, while 2016 is 877k km2 behind.  At this point MASIE and SII are tracking the 10-year average, with SII about 200k km2 lower.

The Table below shows where ice is located on day 321 in regions of the Arctic ocean. 10 year average comes from 2007 through 2016 inclusive.

Region 2017321 Day 321
Average
2017-Ave. 2016304 2017-2016
 (0) Northern_Hemisphere 9904268 10013895 -109626 9026577 877691
 (1) Beaufort_Sea 1052982 1067181 -14199 1056304 -3322
 (2) Chukchi_Sea 449182 702958 -253776 616755 -167573
 (3) East_Siberian_Sea 1076201 1077799 -1598 1087137 -10936
 (4) Laptev_Sea 897845 897517 328 896732 1113
 (5) Kara_Sea 696550 649727 46822 254492 442058
 (6) Barents_Sea 68869 174077 -105208 25907 42962
 (7) Greenland_Sea 394494 499069 -104575 390593 3901
 (8) Baffin_Bay_Gulf_of_St._Lawrence 761453 552922 208531 524708 236745
 (9) Canadian_Archipelago 852865 851728 1137 853180 -315
 (10) Hudson_Bay 460631 273706 186925 185679 274952
 (11) Central_Arctic 3158068 3183076 -25008 3077808 80260

The deficits to average are primarily in Chukchi, also Barents and Greenland Seas. Surpluses are large in Hudson and Baffin Bays, along with Kara Sea.

Footnote

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this analysis, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and uses modern technologies to continue the long and honorable tradition of naval ice charting.  More on this at my post Support MASIE Arctic Ice Dataset

Movember Foundation encourages growing mustaches in support of men’s health and fitness.

 

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Like Your Arctic with Ice?

An imposing panorama of an ice-fjord floating along the bone-chilling water in Svalbard. From Daily Mail

Arctic ice extent went over 9M km2 yesterday, or about 60% of annual maximum.  Several seas are already maxed out:  Laptev, East Siberian, Canadian Archipelago.  The image below shows the refreezing this month.

Click on image to enlarge.

At the bottom watch Beaufort Sea filling in.  On the middle right Baffin Bay steadily adds ice, while Hudson bay starts from its top, but also gets fast ice way down the western coastline into James Bay.  At the top center is Svalbard with Greenland Sea growing on its right, and Kara and Barents filling in on its left.

Dr. Judah Cohen from Atmospheric and Environmental Research (AER) saw this coming.  From his blog November 6 2017:

The forecast for November (Figure 13a) shows cold temperatures in Canada that extend into the Eastern US. The cold temperatures in Canada seem likely but the cold temperatures in the Eastern US will likely depend on the strength of Greenland blocking. The forecast for Eurasia is relatively mild and I think that the forecast is likely to be wrong. In my opinion the predicted blocking across northern Eurasia favors more widespread cold than predicted by the CFS especially across Siberia and East Asia.

My thoughts on the weather pattern over the next several weeks  By Brett Anderson, AccuWeather senior meteorologist  11/08/2017, 4:30:48 PM

Interesting weather pattern setting up across North America as we progress through November and get into early December.

–A series of potent, Pacific storms will likely impact southern BC and the U.S. Pacific Northwest between Nov. 13 and 23. Expect several rounds of heavier rain and gusty winds for Vancouver Island and the mainland coast. Heavy snowfall for the Coastal Range and Rockies should help set the ski season off on a good start.

–A strong Arctic, cold front will press southward through Ontario and Quebec on Thursday. Behind the front, rain showers will quickly change to snow showers and a brief, heavier snow squall. There is the potential for brief whiteout conditions with any squall from southern and eastern Ontario through southern Quebec late Thursday afternoon and into the night. These squalls can quickly drop visibility making travel dangerous for motorists, especially on highways. Roads will generally be wet Thursday afternoon, but untreated roads may briefly get snow covered and icy Thursday evening and night as temperatures rapidly fall below the freezing mark.

In addition to the cold, northwesterly winds will be quite strong Thursday night into early Friday with gusts in the 60- to 80-km/h range from eastern Ontario through Quebec and into western New Brunswick.

Dr. Cohen’s view of the winter Arctic climate system is posted in Snowing and Freezing in the Arctic

Sea Ice Index Updates to v.3.0

In October 2012 Arctic sea ice doubled in extent.

As of October 20, 2017, NOAA@NSIDC Releases Sea Ice Index, Version 3.0

Text below from SII webpage explains the changes in versions.

NOAA@NSIDC is pleased to announce the release of Sea Ice Index Version 3 (V3). V3 changes the way the monthly average area and extent data values are calculated. The way monthly average area and extent images are created remains the same as in V2. All daily data remain the same as in V2.

The V3 method simply averages daily extent values, while the V2 method derived monthly average values from the gridded monthly-average concentration field. The change is in response to questions about what seemed to be an inconsistency between daily and monthly values. When users summed daily values, and then divided by number of days in a month to get a monthly average value, that number was different, and sometimes quite different, from the monthly average numbers we presented. Both the V2 and V3 methodologies are valid and defensible ways of representing passive microwave-derived sea ice concentration data, but the goal of this change is to better match the understanding of the user community as the product evolves through time.

Values will change slightly. V3 monthly average areas are slightly greater than those from V2. Conversely, V3 monthly average extents are slightly less than V2. Trends will change slightly as well. These are small changes, as the following images for March, over the entire time series, illustrate. Extent is on the left and area is on the right. Windnagel et al. (2017) offers additional analysis on why V3 areas are higher than V2 and V3 extents are lower than V2, along with a simple example. With the update to V3, there are no considerable differences in conclusions that can be made about the overall trends in sea ice area or extent.

Details are in this report: Sea Ice Index Version 3 Analysis. NSIDC Special Report 19.

The Sea Ice Index version 3 dataset is available here

Background:

Several posts at this blog compare results from MASIE and SII. Walt Meier, head of Sea Ice Index (SII) and colleagues did a comparison of the two datasets, published in October 2015. SII went from version 1 to v.2 in 2016, and then in January 2017 from v.2.0 to v.2.1, with some changes in past values.

One of the biggest discrepancies in the past with previous SII versions arose in the Month of October, and it is timely that version 3.0 appears now. The dataset is now available with past calculations according to v3, and the past can be compared in advance of 2017 monthly results.

For comparison, the graphs below show October monthly averages for MASIE compared to SII v.2 and SII v.3., 2007 through 2016.

Click on image to enlarge.

It seems clear that SIIv.3 is a big improvement relative to MASIE. And as well, October 2017 results are coming in with the two datasets tracking quite closely.

MASIE: “high-resolution, accurate charts of ice conditions”
Walt Meier, NSIDC, October 2015 article in Annals of Glaciology.

Barents Sea Ice-Free. How Come?

Might maritime activities, such as shipping, oil extraction, fishing etc. be having an effect on Barents Sea ice extents?  Arnd Bernaerts has an informative post up at his blog: They warm-up the Arctic! Shipping, Off-Shore, Science etc.!

Dr. Bernaerts explains:

It is not known which alterations shipping, naval forces, research vessels and off-shore industry cause in the Arctic Ocean sea-body structure, whether ice covered or not, and the subsequent impact on the annual sea ice and the polar-weather, called climate change. Bad that science has no idea about this human Arctic warming aspect. Worse, science has never rose, or ever been willing to raise and investigate the subject. At least you will face a hard time to find anything in this respect.

When considering the possible impact of ocean uses on climate change, any activities at sea north of the Polar Circle is a multifold higher than in any other Ocean region. Between the Arctic Ocean and the Equator the climatic impact of human activities the difference could be several hundred, if not thousand times, due to extreme narrow structure margin concerning water temperature and salinity. The temperature range in the upper 150 meter sea surface level is minus 2° to plus 4°C. Arctic salinity is down to 30ppt in places, while the oceans vary between 34ppt and 36ppt. So far it is statistics, and they are ‘wrong’ if not properly applied.

Navigating and other ocean uses in Arctic sea areas without knowing the impact is irresponsible. Navigating through compact ice is even worse, as the force of ship screws may travel over long distances, with significant changes to sea temperatures and salinity.

Summary

The whole article is informative and raises important questions (and not for the first time).  Time to stop obsessing over CO2, the “magic” gas, and try to understand real human impacts.

A Russian liquid gas tanker (LNG) “Christophe de Margerie” just set two Arctic records few weeks ago (Details). The ship not only traveled through the Arctic in record time, but has done so without the use of an icebreaker escort. She is the first of a total of 15 planned LNG carriers that will be gradually deployed.

 

Arctic Ice Coasting Sept. 12

Crystal Serenity touring in the Arctic Northwest Passage 2016 and 2017.

With the most typical day for annual minimum a week away, watching Arctic ice is like watching an ocean liner coasting to a halt before reversing engines.  A recent post reported that ice extents  are stabilizing around 4.7M km2 in recent days, and more importantly, some refreezing in the central seas.  As discussed in Arctic Heart Beat, the marginal shelf seas seldom have ice at annual minimum, typically on or about day 260.  The image below shows the progression of ice extents from 2007 to 2017 on day 254 with six days to go.

Click on image to enlarge.

 

Yesterday was day 254 and the graph below shows 2017 compared with other years and the decadal average during the last 3 weeks.

For the last week MASIE and SII are showing the same extent, now about 70k km2 above the 10 year average.  Only four years in the decade had more ice on this day.  2007 is 300k km2 lower, 2016 500k km2 lower, and at the bottom is 2012 1.1M km2 below 2017.  A recent post on August storms discussed the dramatic impact on 2012 and 2016, which is evident as well in the chart.  The table compares 2017, decadal average and 2007 for the regions containing ice at this time.

Region 2017254 Day 254
Average
2017-Ave. 2007254 2017-2007
 (0) Northern_Hemisphere 4652293 4583359 68934 4349612 302681
 (1) Beaufort_Sea 393863 480306 -86443 599679 -205815
 (2) Chukchi_Sea 131705 173275 -41570 74733 56973
 (3) East_Siberian_Sea 279268 286737 -7468 311 278957
 (4) Laptev_Sea 205794 149612 56182 247496 -41702
 (5) Kara_Sea 18486 29190 -10705 62274 -43788
 (6) Barents_Sea 4313 25209 -20896 7384 -3071
 (7) Greenland_Sea 107969 211322 -103353 324789 -216820
 (8) Baffin_Bay_Gulf_of_St._Lawrence 45146 22235 22911 21406 23740
 (9) Canadian_Archipelago 370958 262283 108675 210083 160875
 (10) Hudson_Bay 1432 11057 -9625 16552 -15120
 (11) Central_Arctic 3092201 2931173 161028 2783651 308551

The deficits continue to be on the Pacific side, especially Beaufort, and also Greenland Sea is down this year.  These are more than offset by large surpluses in the Central Arctic and Canadian Archipelago, and also Laptev.  East Siberian sea also has surplus ice this year compared to 2007.

aer Atmospheric and Environmental Research

September 5, 2017 Dr. Judah Cohen of AER posted his monthly forecast for the Arctic and NH based on the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO).  Excerpts below.

The AO is currently slightly negative (Figure 1), reflective of mostly positive geopotential height anomalies across the Arctic and mixed geopotential height anomalies across the mid-latitudes of the NH (Figure 2). Geopotential height anomalies are mostly negative across Greenland and Iceland (Figure 2), and therefore the NAO is slightly positive.
Figure 1. (a) The predicted daily-mean near-surface AO from the 00Z 5 September 2017 GFS ensemble. Gray lines indicate the AO index from each individual ensemble member, with the ensemble-mean AO index given by the red line with squares.

The AO is predicted to straddle neutral next week as geopotential height anomalies remain mixed across the Arctic. Similarly, with mixed geopotential height anomalies stretching across Greenland and Iceland, the NAO will likely be near neutral as well.  

(Note: AO and NAO are signed differently than one might expect; the reference point is outside the Arctic itself.  Thus negative phases of these indices mean higher pressures in the Arctic and lower outside, while positive phases indicate lower pressures in the Arctic.  Now that the Arctic sun is setting, the main issue for ice extent is storminess which requires low Arctic pressures.)

Impacts

It is the first week of fall, a season of transition from summer to winter. One important sign IMO of this seasonal transition is the return of the polar vortex in the stratosphere. The models predict the possible formation of the polar vortex sometime next week. Starting in October, I will be watching variability in the polar vortex for signs of pattern changes in the weather across the NH.

Another sign of the seasonal transition is the minimum in Arctic sea ice extent, which will be achieved in the coming days and/or weeks. The trajectory of sea ice melt has slowed since early August. In my last blog I suggested the possibility that the sea ice minimum could be similar to the years 2008 and 2010 and that is looking more likely but is difficult to predict. Over the coming months, I will be following Arctic sea ice variability for signs of the severity of the upcoming winter. Our understanding for how anomalies in sea ice extent influence the weather in the mid-latitudes is still immature IMO but I do think that important progress has been made recently.

Another sign of the transition from summer to winter is the return of snowfall to the NH. Snowfall over the sea ice in August probably helped retard the melt of sea ice and snowfall is now even occurring over Siberia and Alaska but is still very regionalized. Again I will be monitoring the advance of snow cover extent across the continents for signs of the strength of the polar vortex and the possible resultant weather.

Finally I find it interesting that while the atmospheric circulation has transitioned from the dominant summer pattern across Eurasia it has not across North America. The dominant summer pattern across Eurasia was ridging across Europe (with the exception of Northern Europe) and East Asia but with troughing in Western Asia. The forecast for the coming weeks is the opposite with troughs across Europe and East Asia but ridging in Western Asia. This is an overall cooler pattern than the dominant summer pattern. However across North America there are no similar signs of transition. The dominant summer pattern was strong ridging across western North America and troughing in eastern North America and at least for now that pattern looks to continue for much of the month of September. I don’t know the reason behind the persistent western ridge/eastern trough pattern across North America but how long this pattern can persist will obviously have important implications for the weather across North America in the coming months.

Summary

Bottom line, looks like September weather will be ordinary in the Arctic with seasonal cooling in the NH.  Dr. Cohen also thinks the annual ice extent minimum will be near average for the decade.  While the monthly average is final only at September end, this week will set the tone and likely result.

 

 

Early Arctic Minimum?

It is a few days earlier than usual, but MASIE shows ice extents  stabilizing near 4.7M km2 in recent days, and more importantly, some refreezing in the central seas.  As discussed in Arctic Heart Beat, the marginal shelf seas seldom have ice at annual minimum, typically on or about day 260.  The image below shows the progression of ice extents from 2007 to 2017.

Yesterday was day 251 and the graph below shows 2017 compared with other years and the decadal average during the last 3 weeks.

At this point MASIE and SII are showing the same extent, about 100k km2 above the 10 year average.  2007 is 250k km2 lower, 2016 500k km2 lower, and at the bottom is 2012 1.1M km2 below 2017.  The table compares 2017, decadal average and 2007 for the regions containing ice at this time.

Region 2017251 Day 251
Average
2017-Ave. 2007251 2017-2007
 (0) Northern_Hemisphere 4716948 4619900 97048 4467771 249177
 (1) Beaufort_Sea 409067 492365 -83298 643868 -234801
 (2) Chukchi_Sea 133345 185601 -52257 95240 38105
 (3) East_Siberian_Sea 279966 301146 -21180 311 279655
 (4) Laptev_Sea 196236 152840 43396 252479 -56243
 (5) Kara_Sea 22449 30277 -7828 59593 -37144
 (6) Barents_Sea 23123 20028 3095 5882 17240
 (7) Greenland_Sea 116132 196719 -80586 315125 -198993
 (8) Baffin_Bay_Gulf_of_St._Lawrence 46799 21575 25224 17173 29626
 (9) Canadian_Archipelago 374084 268736 105348 236583 137501
 (10) Hudson_Bay 1191 11933 -10743 22646 -21455
 (11) Central_Arctic 3113399 2937746 175653 2817614 295785

The deficits continue to be on the Pacific side, especially Beaufort, and also Greenland Sea is down this year.  These are more than offset by large surpluses in the Central Arctic and Canadian Archipelago, and also Laptev.  East Siberian sea also has surplus ice this year compared to 2007.

aer Atmospheric and Environmental Research

September 5, 2017 Dr. Judah Cohen of AER posted his monthly forecast for the Arctic and NH based on the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO).  Excerpts below.

The AO is currently slightly negative (Figure 1), reflective of mostly positive geopotential height anomalies across the Arctic and mixed geopotential height anomalies across the mid-latitudes of the NH (Figure 2). Geopotential height anomalies are mostly negative across Greenland and Iceland (Figure 2), and therefore the NAO is slightly positive.
Figure 1. (a) The predicted daily-mean near-surface AO from the 00Z 5 September 2017 GFS ensemble. Gray lines indicate the AO index from each individual ensemble member, with the ensemble-mean AO index given by the red line with squares.

The AO is predicted to straddle neutral next week as geopotential height anomalies remain mixed across the Arctic. Similarly, with mixed geopotential height anomalies stretching across Greenland and Iceland, the NAO will likely be near neutral as well.  

(Note: AO and NAO are signed differently than one might expect; the reference point is outside the Arctic itself.  Thus negative phases of these indices mean higher pressures in the Arctic and lower outside, while positive phases indicate lower pressures in the Arctic.  Now that the Arctic sun is setting, the main issue for ice extent is storminess which requires low Arctic pressures.)

Impacts

It is the first week of fall, a season of transition from summer to winter. One important sign IMO of this seasonal transition is the return of the polar vortex in the stratosphere. The models predict the possible formation of the polar vortex sometime next week. Starting in October, I will be watching variability in the polar vortex for signs of pattern changes in the weather across the NH.

Another sign of the seasonal transition is the minimum in Arctic sea ice extent, which will be achieved in the coming days and/or weeks. The trajectory of sea ice melt has slowed since early August. In my last blog I suggested the possibility that the sea ice minimum could be similar to the years 2008 and 2010 and that is looking more likely but is difficult to predict. Over the coming months, I will be following Arctic sea ice variability for signs of the severity of the upcoming winter. Our understanding for how anomalies in sea ice extent influence the weather in the mid-latitudes is still immature IMO but I do think that important progress has been made recently.

Another sign of the transition from summer to winter is the return of snowfall to the NH. Snowfall over the sea ice in August probably helped retard the melt of sea ice and snowfall is now even occurring over Siberia and Alaska but is still very regionalized. Again I will be monitoring the advance of snow cover extent across the continents for signs of the strength of the polar vortex and the possible resultant weather.

Finally I find it interesting that while the atmospheric circulation has transitioned from the dominant summer pattern across Eurasia it has not across North America. The dominant summer pattern across Eurasia was ridging across Europe (with the exception of Northern Europe) and East Asia but with troughing in Western Asia. The forecast for the coming weeks is the opposite with troughs across Europe and East Asia but ridging in Western Asia. This is an overall cooler pattern than the dominant summer pattern. However across North America there are no similar signs of transition. The dominant summer pattern was strong ridging across western North America and troughing in eastern North America and at least for now that pattern looks to continue for much of the month of September. I don’t know the reason behind the persistent western ridge/eastern trough pattern across North America but how long this pattern can persist will obviously have important implications for the weather across North America in the coming months.

Summary

Bottom line, looks like September weather will be ordinary in the Arctic with seasonal cooling in the NH.  Dr. Cohen also thinks the annual ice extent minimum will be near average for the decade.  While the monthly average is final only at September end, the next week will set the tone and likely result.

 

 

Sept. Weather Forecast Arctic & NH

aer Atmospheric and Environmental Research

September 5, 2017 Dr. Judah Cohen of AER posted his monthly forecast for the Arctic and NH based on the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO).  Excerpts below.

The AO is currently slightly negative (Figure 1), reflective of mostly positive geopotential height anomalies across the Arctic and mixed geopotential height anomalies across the mid-latitudes of the NH (Figure 2). Geopotential height anomalies are mostly negative across Greenland and Iceland (Figure 2), and therefore the NAO is slightly positive.
Figure 1. (a) The predicted daily-mean near-surface AO from the 00Z 5 September 2017 GFS ensemble. Gray lines indicate the AO index from each individual ensemble member, with the ensemble-mean AO index given by the red line with squares.

The AO is predicted to straddle neutral next week as geopotential height anomalies remain mixed across the Arctic. Similarly, with mixed geopotential height anomalies stretching across Greenland and Iceland, the NAO will likely be near neutral as well.  

(Note: AO and NAO are signed differently than one might expect; the reference point is outside the Arctic itself.  Thus negative phases of these indices mean higher pressures in the Arctic and lower outside, while positive phases indicate lower pressures in the Arctic.  Now that the Arctic sun is setting, the main issue for ice extent is storminess which requires low Arctic pressures.)

Impacts

It is the first week of fall, a season of transition from summer to winter. One important sign IMO of this seasonal transition is the return of the polar vortex in the stratosphere. The models predict the possible formation of the polar vortex sometime next week. Starting in October, I will be watching variability in the polar vortex for signs of pattern changes in the weather across the NH.

Another sign of the seasonal transition is the minimum in Arctic sea ice extent, which will be achieved in the coming days and/or weeks. The trajectory of sea ice melt has slowed since early August. In my last blog I suggested the possibility that the sea ice minimum could be similar to the years 2008 and 2010 and that is looking more likely but is difficult to predict. Over the coming months, I will be following Arctic sea ice variability for signs of the severity of the upcoming winter. Our understanding for how anomalies in sea ice extent influence the weather in the mid-latitudes is still immature IMO but I do think that important progress has been made recently.

Another sign of the transition from summer to winter is the return of snowfall to the NH. Snowfall over the sea ice in August probably helped retard the melt of sea ice and snowfall is now even occurring over Siberia and Alaska but is still very regionalized. Again I will be monitoring the advance of snow cover extent across the continents for signs of the strength of the polar vortex and the possible resultant weather.

Finally I find it interesting that while the atmospheric circulation has transitioned from the dominant summer pattern across Eurasia it has not across North America. The dominant summer pattern across Eurasia was ridging across Europe (with the exception of Northern Europe) and East Asia but with troughing in Western Asia. The forecast for the coming weeks is the opposite with troughs across Europe and East Asia but ridging in Western Asia. This is an overall cooler pattern than the dominant summer pattern. However across North America there are no similar signs of transition. The dominant summer pattern was strong ridging across western North America and troughing in eastern North America and at least for now that pattern looks to continue for much of the month of September. I don’t know the reason behind the persistent western ridge/eastern trough pattern across North America but how long this pattern can persist will obviously have important implications for the weather across North America in the coming months.

Summary

Bottom line, looks like September weather will be ordinary in the Arctic with seasonal cooling in the NH.  Dr. Cohen also thinks the annual ice extent minimum will be near average for the decade.

 

 

Arctic Ice Uncertainties

Northern Hemisphere Spatial Coverage

As noted in the September Outlook Arctic Ice, NOAA’s Sea Ice Index (SII) typically shows less ice than MASIE from National Ice Center (NIC). SII is a satellite product processed from passive microwave sensors. MASIE (Multisensor Analyzed Sea Ice Extent) adds other sources such as satellite imagery and field observations to produce high resolution ice charts for navigational purposes.

A post in 2016 NOAA Is Losing Arctic Ice showed how discrepancies between the two datasets vary considerably throughout the year, usually lower in SII except for October. Walt Meier directs the SII production and published a study in October 2015 comparing SII and MASIE, also discussed in that post.

In 2016 NOAA upgraded from SII version 1 to version 2, and later to version 2.1. The latest documentation says few datapoints were changed in v2.1, and that anomalies were unchanged. My cursory look seemed to confirm that. However, on closer inspection, there are significant differences between v1 and v2 (which carry over to v2.1). This post describes those differences.

I prepared two spreadsheet arrays for SIIv1 and SIIv2.1 and then a third array to calculate the differences. The graph below shows the results for 2006 to 2015 inclusive, being the years for which datapoints can be compared with MASIE.

It is clear that V2.1 is systematically lower than V1, on average -200k km2. The differences are less than 100k km2 the first four months, then increase May, June, July, before shrinking again in August and September. The big changes come in the last months, especially October. The October correction is not surprising. The comparison by Meier and in my post discussed large SII surpluses over MASIE in October that did not appear credible.

The graph is limited to one decade since that is the period to be compared with MASIE. The spreadsheet shows that the differences are typical of the whole dataset going back to 1979, albeit with considerable variety through the years. The graph below shows the month by month differences for all years through 2015.

As stated before, the average all years difference in green is comparable to the last decade. Differences were calculated by subtracting v1 from v2, since v2 is mostly lower. However, as the Min Diff line shows, v2 was higher for some datapoints, notably in July. The Max Diff shows that some Octobers were changed by as much as 1M km2. The dotted lines show the standard deviation for the average differences, which averaged  +/- 90k km2.

Summary

It is challenging to estimate Arctic ice extents. NOAA is to be commended for recognizing the erroneous October values, and correcting them. Clearly some of that overall diminishing of extents by 200k km2 derives from removing the bogus surpluses.

Those claiming that SII is for certain and MASIE is dubious need to reconsider. MASIE has its own challenges but is reasonably consistent in recent years. Meanwhile SII had to improve its product, resulting in changes to past values in the dataset. While error ranges are not available for these statistics, the standard deviation gives some indication of the variability in the estimates.

Fortunately, it appears that the critical months of March and September have not changed much in the new SII version.  However, it is not encouraging to see SII averages for the last two months -500k km2 below MASIE.  See September Outlook Arctic Ice

It is a good thing that several agencies and methods are involved in the effort to measure and understand Arctic ice dynamics. It is not good to claim certainty for a single record or to ignore the errors that are found along the way. It is wise to remember that measuring anything in the Arctic is difficult.

September Outlook Arctic Ice

2017: August Report from Sea Ice Prediction Network

For the August Report there were 37 contributions with the median Outlook value for September 2017 Arctic sea ice extent of 4.5 million square kilometers with quartiles of 4.2 and 4.8 million square kilometers (See Figure 1 in the Overview section, below). These values are unchanged from the July Report, which is consistent with the moderating impact of summer 2017 Arctic weather. The range is 3.1 to 5.5 million square kilometers in August, unchanged from the July Outlook. To place this Outlook in context, recently observed values were 4.3 million square kilometers in 2007, 3.6 million square kilometers in 2012, and 4.7 million square kilometers in 2016. 

These are predictions for the September 2017 monthly average ice extent as reported by NOAA Sea Ice Index (SII). This post provides a look at the 2017 Year To Date (YTD) based on monthly averages comparing MASIE and SII datasets. (10 year average is 2007 to 2016 inclusive)

The graph puts 2017 into recent historical perspective. Note how 2017 was below the 10-year average for the first 4 months, then recovered to match average in May and has maintained average through August. The outlier 2012 provided the highest March maximum as well as the lowest September minimum, coinciding with the Great Arctic Cyclone that year.  2007 began the decade with the lowest minimum except for 2012.  SII 2017 is running below MASIE and is currently just below MASIE 2007 and 2012.

The table below provides the numbers for comparisons.

Monthly 2017 2017 2017 2017-10yr Ave 2017-10yr Ave 2017-
2007
Averages MASIE SII SII
Deficit
MASIE SII MASIE
Jan 13.503 13.174 -0.329 -0.418 -0.512 -0.259
Feb 14.478 14.112 -0.366 -0.363 -0.440 -0.173
Mar 14.509 14.273 -0.236 -0.544 -0.542 -0.114
Apr 13.941 13.760 -0.180 -0.412 -0.446 0.246
May 12.838 12.618 -0.220 0.075 -0.138 0.412
June 10.975 10.720 -0.255 0.069 -0.218 0.148
July 8.383 7.901 -0.482 0.024 -0.206 0.367
Aug 6.006 5.472 -0.533 0.051 -0.185 0.421

The first two columns are the 2017 YTD shown by MASIE and SII, with the SII deficits in column three.  The difference has doubled the last two months and averaged -325k km2 for the YTD. Column four shows MASIE 2017 compared to MASIE 10 year average, while column five shows SII 2017 compared to SII 10 year average.  YTD MASIE is -190k km2 to average and SII is -336k km2 to average.  The last column shows MASIE 2017 holding an August surplus of 421k km2 over 2007.  For the YTD 2017 is 131k km2 higher than 2007, overcoming this year’s deficits in the early months.

For more on SII versions 1 and 2 differences see Arctic Ice Uncertainties

Summary

The experts involved in SIPN are expecting SII 2017 September to be higher than 2007 and slightly lower than 2016.  The way MASIE is going, this September looks to go higher than 2016 unless some bad weather intervenes.

Footnote:

Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:

MASIE is rigorous, reliable, serves as calibration for satellite products, and continues the long and honorable tradition of naval ice charting using modern technologies. More on this at my post Support MASIE Arctic Ice Dataset

MASIE: “high-resolution, accurate charts of ice conditions”
Walt Meier, NSIDC, October 2015 article in Annals of Glaciology.

Serenity Faces Ice Aug.30

Click on image to enlarge.

August 31 and Sept. 1 Updates Below

h/t to angech for asking an interesting question:  What are the chances of an early refreezing in the Northwest Passage?  It provoked me to look more into the recent history of ice extents in the CAA (Canadian Arctic Archipelago).

The image above shows the years in the last decade closest to 2017 in terms of ice present in the CAA.  Only 2014 had more ice in that region than this year: 513k km2 compared to 464k km2 at day 240.  It appears that CAA annual minimum typically occurs at day 260, the same as the overall NH minimum.  The image above also shows that 2009 with 388k km2 provides the closest analog to this year for the amount of ice in McClintock Bay just in front of Serenity. The image below gives the progression in 2009 from day 244 to 270.

As of 10:30 EST this morning Serenity is located as shown in image below along with ice extent reported by MASIE for yesterday.  Ship tracking is provided by marinevesseltraffic.com  and shows that Serenity is now in convoy with two icebreakers ahead of her.

Canadian ice chart from yesterday showing Serenity and escort worked their way through the water and thinner green ice, but with some thicker stuff ahead.

Serenity will make it through with such assistance, which was largely unnecessary last year.  And as the above shows, 2014 would have been close to impossible.

UPDATE 16:30 EST

The convoy has reached the southern tip of Prince of Wales Island and are turning northeast. It appears they will sail along the thin shore ice, presumably headed for the western entrance of Bellot Strait which passes through to Prince Regent channel.

UPDATE 7:00AM EST AUG. 31

Serenity convoy is about to enter Bellot Strait.  Waiting for a cargo ship to exit the channel.

UPDATE 9:00AM EST Aug. 31

Cruisemapper shows Serenity has entered the Strait following her icebreaker.

Update 12:00 PM EST Aug. 31

Serenity and icebreaker escort have emerged from Bellot Strait into Prince Regent channel and are turning north.  Next destination may well be Devon Island with some interesting things that were seen last year.  See Mars in the Arctic

Update 7:00 AM EST Sept. 1, 2017

Serenity and icebreaker are anchored just off Beechey Island at the southwestern tip of Devon Island.