Normal Arctic Ice End of Feb. 2023

With the end of February, nearly all of the Arctic ocean basins are frozen over, so the growth of ice extent slows down, reaching its annual maximum mid-March.  According to MASIE February on average adds 500k km2, and this year the growth was 880k km2, erasing a starting deficit and matching the month end average. The few basins that can grow ice this time of year tend to fluctuate and alternate waxing and waning, which appears as a see saw pattern in these images.  For example, this year the two Pacific basins combined were slightly above average, but Okhotsk is 33% in surplus, while Bering is 26% in deficit to their last March maximums.

The month of February 2023 was remarkable for a wobbly Polar vortex, which cycles freezing polar air south, replacing it with incursions of warmer air into the Arctic, and then reverses the effect. This results in rising and falling freezing rates.  The graph below shows the ice recovery for February 2023, the 17-year average and some recent years.

The graph (cyan) shows February 2023 starting with a 284k km2 deficit to average, several up and downs in the growth rate, until matching average at month end. 2020 also ended average with a steady refreezing rate.   SII (Sea Ice Index) tracked well below MASIE this month showing 400k km2 lower extent than MASIE yesterday.

February Ice Growth Despite See Saws in Atlantic and Pacific

As noted above, this time of year the Arctic adds ice on the fringes since the central basins are already frozen over.  The animation above shows the Okhotsk (upper left) and Bering (lower left) see saw.  Okhotsk grew steadily to reach 133% of its last maximum, while Bering waffled up and down, ending the month ~100k km2 higher and 74% of its max.

On the right, Atlantic side Barents at the top fluctuated and added little ice ending at 56% of its max.  On the lower right, Baffin Bay, and Greenland Sea (center right) show another see saw.  Greenland Sea waffled adding`80k km2, ending  at 96% of max, while Baffin Bay steadily added 300k km2 to reach 90% of maximum.

The table below presents ice extents in the Arctic regions for day 31 (Jan. 31) compared to the 17 year average and 2018.

Region 2023059 Day 59 Average 2023-Ave. 2018059 2023-2018
 (0) Northern_Hemisphere 14878631 14899627 -20996 14485052 393579
 (1) Beaufort_Sea 1070966 1070314 652 1070445 521
 (2) Chukchi_Sea 966006 965374 632 965971 35
 (3) East_Siberian_Sea 1087137 1087106 32 1087120 18
 (4) Laptev_Sea 897845 897836 9 897845 0
 (5) Kara_Sea 884398 926234 -41836 922905 -38507
 (6) Barents_Sea 442032 631999 -189967 544938 -102906
 (7) Greenland_Sea 745952 611275 134677 473064 272889
 (8) Baffin_Bay_Gulf_of_St._Lawrence 1624859 1519162 105697 1786606 -161747
 (9) Canadian_Archipelago 854843 853331 1511 853109 1734
 (10) Hudson_Bay 1260903 1260417 487 1260838 66
 (11) Central_Arctic 3185508 3213856 -28349 3065181 120326
 (12) Bering_Sea 627138 664021 -36884 336065 291073
 (13) Baltic_Sea 81571 98009 -16437 123280 -41709
(14) Sea_of_Okhotsk 1132332 1058413 73919 1069898 62433

The table shows the only major deficit to average appears in Barents seas, more than offset by surpluses in Greenland Sea and Baffin Bay. These few peripheral basins are the only remaining regions with additional ice extent to add.

The polar bears have a Valentine Day’s wish for Arctic Ice.


And Arctic Ice loves them back, returning every year so the bears can roam and hunt for seals.


Seesaw accurately describes Arctic ice in another sense:  The ice we see now is not the same ice we saw previously.  It is better to think of the Arctic as an ice blender than as an ice cap, explained in the post The Great Arctic Ice Exchange.

via Science Matters

March 1, 2023 at 11:29AM

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