Previous posts showed 2021 Arctic Ice fell short of breaking the 15M km2 ceiling mid March due to a February Polar Vortex disruption.  As we shall see below, another smaller PV disruption is now occurring accelerating the normal spring melting season.  The graph above shows that the March monthly average has varied little since 2007, typically around the SII average of 14.7 M km2.  Of course there are regional differences as described later on.

Dr. Judah Cohen at AER provides an image of how this latest PV disruption appears:

The High pressure areas were forecast to warm over the Pacific Arctic basins, and extending over to the European side, while the cold Low area is presently extending down into North America, bringing some snow on April 1 in Montreal (no joke).  The effect on Arctic Ice is shown in the animation below:

Over the last 10 days, Okhotsk upper left lost 180k km2 while Bering lower left lost half that with a slight recovery yesterday.  Barents Sea upper right lost 145k km2 over the same period.  The effect on NH total ice extents is presented in the graph below.

The graph above shows ice extent through March comparing 2021 MASIE reports with the 14-year average, other recent years and with SII.  After drawing close to average by day 80, 2021 ice extents dropped sharply and at March end matched both 2020 and 2007.  Despite losses from this PV event, the 2020 March monthly average ended up comparable to other years, as seen in the chart at the top.  In fact, the SII dataset of monthly gains and losses shows March 2021 gained slightly over end of February, compared to a 200k km2 loss for the average March.

 

The table below shows the distribution of sea ice across the Arctic regions.

Region	2021090	Day 090 Average	2021-Ave.	2007090	2021-2007
(0) Northern_Hemisphere	14266634	14692014	-425380	14222916	43718
(1) Beaufort_Sea	1070689	1070177	512	1069711	978
(2) Chukchi_Sea	966006	964100	1907	966006	0
(3) East_Siberian_Sea	1087137	1086134	1003	1074908	12229
(4) Laptev_Sea	897827	896838	989	884340	13487
(5) Kara_Sea	935023	916581	18442	892157	42866
(6) Barents_Sea	602392	649566	-47174	441970	160422
(7) Greenland_Sea	620574	658050	-37476	686312	-65739
(8) Baffin_Bay_Gulf_of_St._Lawrence	1243739	1438412	-194673	1217467	26272
(9) Canadian_Archipelago	854597	852959	1638	850127	4470
(10) Hudson_Bay	1260903	1254727	6176	1229995	30908
(11) Central_Arctic	3192844	3234463	-41619	3242237	-49393
(12) Bering_Sea	549939	736829	-186890	814788	-264849
(13) Baltic_Sea	33543	608741	-27331	45897	-12354
(14) Sea_of_Okhotsk	942085	861234	80850	794657	147428

Overall NH extent March 31 was below average by 425k km2, or 3%.  The bulk of the deficit is seen in Bering and Baffin, along with Barents Sea.  Okhotsk remains above average in spite of recent losses.  The onset of spring melt is as usual in most regions.