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Describe low sea ice extent within the Chukchi Sea

November 2017 will almost definitely be remembered not for total Arctic ice extent, which was once the Zero.33 lowest recorded over the length of satellite observations, nonetheless for the file low extent within the Chukchi Sea. Here’s a key home for Arctic Ocean gain admission to, and is an indicator of oceanographic influences on sea ice extent.

Overview of prerequisites


Figure 1. Arctic sea ice extent for November 2017 was once 9.Forty six million sq. kilometers (Three.sixty 5 million sq. miles). The magenta line reveals the 1981 to 2010 moderate extent for that month. Sea Ice Index knowledge. In regards to the files

Credit: National Snow and Ice Knowledge Center
Excessive-resolution portray

Arctic sea ice extent for November 2017 averaged 9.Forty six million sq. kilometers (Three.sixty 5 million sq. miles), the Zero.33 lowest within the 1979 to 2017 satellite file. This was once 1.24 million sq. kilometers (479,000 sq. miles) under the 1981 to 2010 moderate and 830,000 sq. kilometers (321,000 sq. miles) above the file low November extent recorded in 2016. Extent at the tip of the month was once under moderate over the Atlantic facet of the Arctic, essentially within the Barents and Kara Seas, a minute above moderate in western Hudson Bay, nonetheless a long way under moderate within the Chukchi Sea. This continues a pattern of under-moderate extent on this region that has persevered for the final twelve months.

Circumstances in context


Figure 2. The graph above reveals Arctic sea ice extent as of December Three, 2017, along with each day ice extent knowledge for five previous years. 2017 is shown in blue, 2016 in inexperienced, 2015 in orange, 2014 in brown, 2013 in crimson, and 2012 in dotted crimson. The 1981 to 2010 median is in dusky grey. The grey areas across the median line existing the interquartile and interdecile ranges of the files. Sea Ice Index knowledge.

Credit: National Snow and Ice Knowledge Center
Excessive-resolution portray

Ice growth at some level of November 2017 averaged 80,one hundred sq. kilometers (30,900 sq. miles) per day. This was once stronger than the in sort price for the month of 69,600 sq. kilometers (26,900 sq. miles) per day. Ice growth was once severely speedy interior Hudson Bay, Baffin Bay, and the Kara Sea.

November air temperatures at 925 hPa (about Three,000 feet above sea level) get been above moderate over in actuality all the Arctic Ocean, with illustrious warmth spots (larger than 6 levels Celsius, or eleven levels Fahrenheit above the 1981 to 2010 moderate) over the Chukchi Sea and north of Svalbard. The abnormal warmth within the Chukchi Sea not not as much as in piece manifests the intensive open water on this region, nonetheless a pattern of winds blowing in from the southwest additionally looks to get had an affect. The warmth north of Svalbard is extra clearly related to the in sort pattern of atmospheric circulation over the month, with an home of low tension centered over the Norwegian Sea and an home of excessive tension centered north of the Taymyr Peninsula combining to transport warmth air into the region.

November 2017 when compared to previous years


Figure Three. Month-to-month November ice extent for 1979 to 2017 reveals a decline of 5.14 % per decade.

Credit: National Snow and Ice Knowledge Center
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The linear price of sea ice decline for November is fifty five,000 sq. kilometers (21,200 sq. miles) per twelve months, or 5.14 % per decade. Take from our previous put up that NSIDC just currently revised the manner in which month-to-month moderate extents are computed, which has minor impacts on computed trends.

Delivery water within the Chukchi Sea


Figure four. The draw at high reveals an evaluation of sea ice concentrate on November 30, 2017 within the home of the Bering and Chukchi Seas. The graph at bottom reveals the mixed sea ice focus from 1978 to 2017, essentially based totally on Sea Ice Index knowledge.

Credit: Rick Thoman of the NOAA National Weather Carrier Alaska Region
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Basically based utterly on an evaluation by Rick Thoman of the NOAA National Weather Carrier, as of 19 November, ice extent within the mixed Beaufort and Chukchi Seas sector was once the bottom ever noticed within the ocean ice file (Figure four). This was once largely driven by the dearth of sea ice at some level of the Chukchi Sea. By the tip of November, the Beaufort Sea was once entirely ice-covered. The NOAA evaluation makes use of the NSIDC Sea Ice Index knowledge residing. As mentioned in our June 7 put up, the present boom of the ice quilt on this region seemingly has its origin as a long way operate final twelve months, when warmth prerequisites favored the persistence of open water within the Chukchi Sea into December of 2016.

Stable winds from the north came about for about a days at the tip of March and early April, pushing ice southward within the Bering Sea, breaking apart the ice within the Chukchi Sea, and even flushing some ice out during the Bering Strait. We additionally urged a that that it is in all probability you’ll well per chance factor in role of a solid oceanic warmth influx to the Chukchi Sea through Bering Strait. In reinforce of this gaze, within the summer season of 2017, Rebecca Woodgate of the College of Washington, Seattle, crusing on the overview vessel Norseman II, recovered mooring knowledge that indicated an early arrival of heat ocean water within the strait, about a month sooner than the in sort. This resulted in June ocean temperatures that get been Three levels Celsius (5 levels Fahrenheit) above moderate. Greater ocean temperatures in summer season plays a astronomical role within the timing of when the ice will fabricate but but again in iciness. There would possibly be seemingly a vital quantity of heat closing within the tip layer of the ocean, that could well well must be misplaced to the ambiance and outer home sooner than the region turns into fully ice covered.

Low Antarctic sea ice extent


Figure 5a. Antarctic sea ice focus from AMSR2, in %, for November 28, 2017. The Maud Upward push polynya is seen at high.

Credit: College of Bremen
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Figure 5b. Puny tabular icebergs are seen within the marginal ice zone of the northern Weddell Sea on November 22, 2017 at some level of a NASA Operation IceBridge flight.

Credit: NASA/John Sonntag
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In the Southern Hemisphere, where it is miles unhurried spring, sea ice declined at a faster-than-moderate tempo after the very unhurried-season October 12 most extent. This resulted in the Zero.33-lowest November moderate month-to-month extent within the satellite file, at the serve of 1986 and 2016. Sea ice extent was once shut to-moderate in all areas in addition to the Weddell Sea, where extent is at a satellite-period file low.

The atmospheric circulation for November exhibited a extraordinarily solid wave-Three pattern. In a wave-Three pattern, there are three main low-tension areas across the continent separated by three excessive-tension areas. Air temperatures for the month get been shut to-moderate in most areas except for the jap Weddell Sea, according to the reduced sea ice extent there.

The Maud Upward push Polynya (Figure 5a) persevered to develop through November, as increased sunshine and air temperatures allowed the upwelling warmth water to lengthen the opening within the floating sea ice quilt. On the foundation of December,  retreat of the ocean ice edge remodeled the polynya to a astronomical embayment within the ocean ice quilt.

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