November Arctic Refreezing

Oppsummering: Månedlig utbredelse av havis i Arktis i løpet av 2017 har tatt seg opp og kan nå sammenliknes med tidligere dekade

Kilde: Global Warming Policy Forum (GWPF)

Forfatter: Ron Clutz, Science Matters 03.12.2017

Artic Ice - figur 1.png


 

The formation of ice this year shows solid concentrations in the central Arctic.  Watch the November refreezing of Arctic marginal seas from the center outward.

At the top, open water in Chukchi is shrinking while neighboring Beaufort and East Siberian seas freeze completely. On the left, Hudson Bay starts with fast ice on the western shore, now growing extent strongly.  On the right, Kara ice cover is 90% complete.
The table shows ice extents in the regions for 2017, 10 year averages and 2016 for day 334. Decadal averages refer to 2007 through 2016 inclusive.

Artic Ice - figur 2.png

Note that 2017 in both MASIE and SII tracked the 10 year average, slightly lower throughout.  SII is now about 240k km2 less than MASIE. 2012 grew strongly to approach the 10 year average, recovering after being decimated by the August Great Arctic Cyclone. 2007 lags behind, and the lackluster 2016 recovery is also evident. The narrative from activist ice watchers is along these lines:  2017 minimum was not especially low, but it is very thin.  “The Arctic is on thin ice.”  They are basing that notion on PIOMAS, a model-based estimate of ice volumes, combining extents with estimated thickness.  That technology is not mature, with only a decade or so of remote sensing. The image below from AARI shows widespread thick ice at end of November 2017.

The formation of ice this year shows solid concentrations in the central Arctic.  Watch the November refreezing of Arctic marginal seas from the center outward.

Region

2017334

Day 334
Average

2017-Ave.

2016334

2017-2016

 (0) Northern_Hemisphere

10966755

11073358

-106603

10123083

843672

 (1) Beaufort_Sea

1070445

1069141

1304

1070445

0

 (2) Chukchi_Sea

560938

852508

-291570

720442

-159503

 (3) East_Siberian_Sea

1068113

1085310

-17197

1087137

-19024

 (4) Laptev_Sea

897845

897809

36

897845

0

 (5) Kara_Sea

843397

794994

48403

486630

356767

 (6) Barents_Sea

248423

266718

-18295

56217

192206

 (7) Greenland_Sea

512025

546103

-34078

434402

77623

 (8) Baffin_Bay_Gulf_of_St._Lawrence

728933

695198

33735

722702

6231

 (9) Canadian_Archipelago

853109

852805

303

853180

-71

 (10) Hudson_Bay

774499

561038

213460

331472

443027

 (11) Central_Arctic

3189555

3205221

-15667

3144344

45210

 

NH extent is close to average with the only large deficit in Chukchi.  Most seas are nearly average with a large surplus in Hudson offsetting Chukchi.  Both seas are now refreezing strongly.

Summary

Earlier observations showed that Arctic ice extents were low in the 1940s, grew thereafter up to a peak in 1977, before declining.  That decline was gentle until 1994 which started a decade of multi-year ice loss through the Fram Strait.  There was also a major earthquake under the north pole in that period.  In any case, the effects and the decline ceased in 2007, 30 years after the previous peak.  Now we have a plateau in ice extents, which could be the precursor of a growing phase of the quasi-60 year Arctic ice oscillation.

 

Background on MASIE Data Sources

MASIE reports are generated by National Ice Center from the Interactive Multisensor Snow and Ice Mapping System (IMS). From the documentation, the multiple sources feeding IMS are:

Platform(s) AQUA, DMSP, DMSP 5D-3/F17, GOES-10, GOES-11, GOES-13, GOES-9, METEOSAT, MSG, MTSAT-1R, MTSAT-2, NOAA-14, NOAA-15, NOAA-16, NOAA-17, NOAA-18, NOAA-N, RADARSAT-2, SUOMI-NPP, TERRA

Sensor(s): AMSU-A, ATMS, AVHRR, GOES I-M IMAGER, MODIS, MTSAT 1R Imager, MTSAT 2 Imager, MVIRI, SAR, SEVIRI, SSM/I, SSMIS, VIIRS

Summary: IMS Daily Northern Hemisphere Snow and Ice Analysis

The National Oceanic and Atmospheric Administration / National Environmental Satellite, Data, and Information Service (NOAA/NESDIS) has an extensive history of monitoring snow and ice coverage.Accurate monitoring of global snow/ice cover is a key component in the study of climate and global change as well as daily weather forecasting.

The Polar and Geostationary Operational Environmental Satellite programs (POES/GOES) operated by NESDIS provide invaluable visible and infrared spectral data in support of these efforts. Clear-sky imagery from both the POES and the GOES sensors show snow/ice boundaries very well; however, the visible and infrared techniques may suffer from persistent cloud cover near the snowline, making observations difficult (Ramsay, 1995). The microwave products (DMSP and AMSR-E) are unobstructed by clouds and thus can be used as another observational platform in most regions. Synthetic Aperture Radar (SAR) imagery also provides all-weather, near daily capacities to discriminate sea and lake ice. With several other derived snow/ice products of varying accuracy, such as those from NCEP and the NWS NOHRSC, it is highly desirable for analysts to be able to interactively compare and contrast the products so that a more accurate composite map can be produced.

The Satellite Analysis Branch (SAB) of NESDIS first began generating Northern Hemisphere Weekly Snow and Ice Cover analysis charts derived from the visible satellite imagery in November, 1966. The spatial and temporal resolutions of the analysis (190 km and 7 days, respectively) remained unchanged for the product’s 33-year lifespan.

As a result of increasing customer needs and expectations, it was decided that an efficient, interactive workstation application should be constructed which would enable SAB to produce snow/ice analyses at a higher resolution and on a daily basis (~25 km / 1024 x 1024 grid and once per day) using a consolidated array of new as well as existing satellite and surface imagery products. The Daily Northern Hemisphere Snow and Ice Cover chart has been produced since February, 1997 by SAB meteorologists on the IMS.

Another large resolution improvement began in early 2004, when improved technology allowed the SAB to begin creation of a daily ~4 km (6144×6144) grid. At this time, both the ~4 km and ~24 km products are available from NSIDC with a slight delay. Near real-time gridded data is available in ASCII format by request.

In March 2008, the product was migrated from SAB to the National Ice Center (NIC) of NESDIS. The production system and methodology was preserved during the migration. Improved access to DMSP, SAR, and modeled data sources is expected as a short-term from the migration, with longer term plans of twice daily production, GRIB2 output format, a Southern Hemisphere analysis, and an expanded suite of integrated snow and ice variable on horizon.

http://www.natice.noaa.gov/ims/ims_1.html

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

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