Arctic -measurements of winter sea ice 2020/21 | Polarjournal
Arctic sea ice appears to have reached its maximum extent on March 21, 2021, marking the seventh lowest extent in 43 years of satellite measurements. (Image: NASA)

On March 21, 2021, Arctic sea ice likely reached its maximum extent for the winter of 2020/21 at 5.71million square miles, matching 2007 for the seventh lowest extent of sea ice cover in the Arctic. The maximum extent this year is 336’000 square miles below the average maximum from 1981 to 2010 of 6.04 square miles.

In 2021, the largest sea ice extent was measured on March 21. 2017, at the minus record the peak was measured 2 weeks earlier. (Image: Ice Data Center, Boulder)

On March 7, 2017, 5.56 million square miles was the lowest level since measurements had begun 39 years earlier. Only a fraction more ice was recorded in 2018. At 5.61 million square miles, 2015 and 2016 were third on the minus list.

Global Change Observation Mission

The GCOM mission consists of two series of satellites, for monitoring changes in water circulation and for climate change. The GCOM-W, with an on-board microwave radiometer, monitors precipitation, vapor levels, wind speed over the ocean, seawater temperature, water levels on land surfaces, and snow depths.

GCOM is a project for long-term monitoring of changes in the environment. As part of Japan’s contributions to GEOSS (Global Earth Observation System of Systems), GCOM will be in operation for 10 to 15 years. On May 18, 2012, the first satellite GCOM-W1 (nicknamed “Shizuku”) was launched and on December 23, 2017, the second satellite “GCOM-C1” (nicknamed “Shikisai”) was launched into orbit. (Foto: NASA)

GCOM-W1 monitors microwaves naturally emitted from the ground, sea surface and atmosphere using six different frequency bands from 7 GHz to 89 GHz. The strength of a natural microwave is determined by its properties and moisture, including the surface condition and temperature of the material.

Heiner Kubny, PolarJournal

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