Arctic Ice Marches On

MASIE ice extents reported March 8 through 31, 2017.

This time of year the heart of the Arctic is frozen solid, and the only changes occur in the marginal seas.  Above shows the Atlantic basins, especially Kara, Barents, Greenland Sea and Baffin Bay.  All of them seesawed during the month, with some fall off at the end, especially noticeable in Gulf of St. Lawrence (counted with Baffin Bay).

Meanwhile on the Pacific side, Bering fluctuated, while Okhotsk lost extent steadily toward month end.

Context

The monthly ice extent average for March provides indication of any year’s annual maximum, prior to melting down to the September annual minimum. Sometimes a lower March extent yields a lower September extent, but not always: 2012 had both the highest maximum and lowest minimum in the last 11 years. That was the year of the Great Arctic Cyclone, and an outlier in the record.

Looking at the 11-year averages in the MASIE data set, the pattern in round numbers is:
Maximum: 15.0 M km2
Minimum: 4.8 M km2
Loss: 10.2 M km2
Loss: 68.0 % of maximum

So about 2/3 of the maximum extent is lost, varying from 66 to 70%. Obviously, all the factors affecting ice extents are in play: (Water, Wind and Weather) with the September outcome uncertain, but likely to be in the range observed.

March 2017 in Comparison

As has been reported, ice formation this year has been sluggish compared to other years. The graph below shows March 2017 compared with the 11 year average, and with 2006 and 2016, as well as SII (Sea Ice Index).

This March started below average, lost sllghtly until the third week, then recovered some before dropping off at the end. 2006 dropped off more rapidly than 2017, while 2016 ended near average. SII showed lower extents all month but drew close at the end.

The Table below shows Day 90 extents across the Arctic Seas compared to averages and 2006, the lowest recent year.

Region 2017090 Day 090
Average
2017-Ave. 2006090 2017-2006
 (0) Northern_Hemisphere 14228992 14791162 -562170 13913402 315590
 (1) Beaufort_Sea 1070445 1070018 427 1068683 1762
 (2) Chukchi_Sea 966006 965297 709 959091 6915
 (3) East_Siberian_Sea 1086168 1085794 374 1084627 1541
 (4) Laptev_Sea 897845 896573 1272 897773 71
 (5) Kara_Sea 831189 924617 -93428 922164 -90974
 (6) Barents_Sea 525362 656247 -130885 623912 -98550
 (7) Greenland_Sea 705581 661500 44081 604935 100645
 (8) Baffin_Bay_Gulf_of_St._Lawrence 1467334 1426694 40641 1026934 440401
 (9) Canadian_Archipelago 853214 852652 562 851691 1523
 (10) Hudson_Bay 1260903 1251383 9521 1240389 20514
 (11) Central_Arctic 3247995 3235035 12960 3241074 6921
 (12) Bering_Sea 702504 847340 -144836 662863 39640
 (13) Baltic_Sea 29767 75051 -45284 129348 -99580
 (14) Sea_of_Okhotsk 575084 830273 -255189 588167 -13083
 (15) Yellow_Sea 0 99 -99 1067 -1067
 (16) Cook_Inlet 7318 5460 1858 5462 1856

The marginal seas in the Atlantic and Pacific make the 2017 deficits to average: especially Barents, Kara, Bering and Okhotsk. Those seas usually lose all their ice by September. 2017 Surpluses in Greenland Sea and Baffin Bay are smaller, but make most of the difference with 2006.

2017 Outlook

March this year averaged 14.509 M Km2 compared to the 11 year average of 14.986 M km2, a deficit of 478k km2 or 3.2% down. That suggests that a typical melt later this year would result in a minimum of about 4.5 or 4.6 M km2, slightly down from the 11 year average of 4.8M km2.

Sea Ice Index (SII) typically shows less ice than MASIE, and SII reports a 2017 March average ice extent of 14.273 M km2 compared to SII 11 year March average of 14.842, a drop of 569k km2 or 3.8%.  Folks relying on SII may be expecting a lower September minimum, perhaps even breaking the present plateau of ice extents since 2007.  That remains to be seen.

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