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  • Author or Editor: Igor V. Polyakov x
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Igor V. Polyakov
,
Roman V. Bekryaev
,
Genrikh V. Alekseev
,
Uma S. Bhatt
,
Roger L. Colony
,
Mark A. Johnson
,
Alexander P. Maskshtas
, and
David Walsh

Abstract

Arctic atmospheric variability during the industrial era (1875–2000) is assessed using spatially averaged surface air temperature (SAT) and sea level pressure (SLP) records. Air temperature and pressure display strong multidecadal variability on timescales of 50–80 yr [termed low-frequency oscillation (LFO)]. Associated with this variability, the Arctic SAT record shows two maxima: in the 1930s–40s and in recent decades, with two colder periods in between. In contrast to the global and hemispheric temperature, the maritime Arctic temperature was higher in the late 1930s through the early 1940s than in the 1990s. Incomplete sampling of large-amplitude multidecadal fluctuations results in oscillatory Arctic SAT trends. For example, the Arctic SAT trend since 1875 is 0.09 ± 0.03°C decade−1, with stronger spring- and wintertime warming; during the twentieth century (when positive and negative phases of the LFO nearly offset each other) the Arctic temperature increase is 0.05 ± 0.04°C decade−1, similar to the Northern Hemispheric trend (0.06°C decade−1). Thus, the large-amplitude multidecadal climate variability impacting the maritime Arctic may confound the detection of the true underlying climate trend over the past century. LFO-modulated trends for short records are not indicative of the long-term behavior of the Arctic climate system. The accelerated warming and a shift of the atmospheric pressure pattern from anticyclonic to cyclonic in recent decades can be attributed to a positive LFO phase. It is speculated that this LFO-driven shift was crucial to the recent reduction in Arctic ice cover. Joint examination of air temperature and pressure records suggests that peaks in temperature associated with the LFO follow pressure minima after 5–15 yr. Elucidating the mechanisms behind this relationship will be critical to understanding the complex nature of low-frequency variability.

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Igor V. Polyakov
,
Tom P. Rippeth
,
Ilker Fer
,
Matthew B. Alkire
,
Till M. Baumann
,
Eddy C. Carmack
,
Randi Ingvaldsen
,
Vladimir V. Ivanov
,
Markus Janout
,
Sigrid Lind
,
Laurie Padman
,
Andrey V. Pnyushkov
, and
Robert Rember

Abstract

A 15-yr duration record of mooring observations from the eastern (>70°E) Eurasian Basin (EB) of the Arctic Ocean is used to show and quantify the recently increased oceanic heat flux from intermediate-depth (~150–900 m) warm Atlantic Water (AW) to the surface mixed layer and sea ice. The upward release of AW heat is regulated by the stability of the overlying halocline, which we show has weakened substantially in recent years. Shoaling of the AW has also contributed, with observations in winter 2017–18 showing AW at only 80 m depth, just below the wintertime surface mixed layer, the shallowest in our mooring records. The weakening of the halocline for several months at this time implies that AW heat was linked to winter convection associated with brine rejection during sea ice formation. This resulted in a substantial increase of upward oceanic heat flux during the winter season, from an average of 3–4 W m−2 in 2007–08 to >10 W m−2 in 2016–18. This seasonal AW heat loss in the eastern EB is equivalent to a more than a twofold reduction of winter ice growth. These changes imply a positive feedback as reduced sea ice cover permits increased mixing, augmenting the summer-dominated ice-albedo feedback.

Open access
Igor V. Polyakov
,
Vladimir A. Alexeev
,
Igor M. Ashik
,
Sheldon Bacon
,
Agnieszka Beszczynska-Möller
,
Eddy C. Carmack
,
Igor A. Dmitrenko
,
Louis Fortier
,
Jean-Claude Gascard
,
Edmond Hansen
,
Jens Hölemann
,
Vladimir V. Ivanov
,
Takashi Kikuchi
,
Sergey Kirillov
,
Yueng-Djern Lenn
,
Fiona A. McLaughlin
,
Jan Piechura
,
Irina Repina
,
Leonid A. Timokhov
,
Waldemar Walczowski
, and
Rebecca Woodgate

No Abstract available.

Full access
Igor V. Polyakov
,
Leonid A. Timokhov
,
Vladimir A. Alexeev
,
Sheldon Bacon
,
Igor A. Dmitrenko
,
Louis Fortier
,
Ivan E. Frolov
,
Jean-Claude Gascard
,
Edmond Hansen
,
Vladimir V. Ivanov
,
Seymour Laxon
,
Cecilie Mauritzen
,
Don Perovich
,
Koji Shimada
,
Harper L. Simmons
,
Vladimir T. Sokolov
,
Michael Steele
, and
John Toole

Abstract

Analysis of modern and historical observations demonstrates that the temperature of the intermediate-depth (150–900 m) Atlantic water (AW) of the Arctic Ocean has increased in recent decades. The AW warming has been uneven in time; a local ∼1°C maximum was observed in the mid-1990s, followed by an intervening minimum and an additional warming that culminated in 2007 with temperatures higher than in the 1990s by 0.24°C. Relative to climatology from all data prior to 1999, the most extreme 2007 temperature anomalies of up to 1°C and higher were observed in the Eurasian and Makarov Basins. The AW warming was associated with a substantial (up to 75–90 m) shoaling of the upper AW boundary in the central Arctic Ocean and weakening of the Eurasian Basin upper-ocean stratification. Taken together, these observations suggest that the changes in the Eurasian Basin facilitated greater upward transfer of AW heat to the ocean surface layer. Available limited observations and results from a 1D ocean column model support this surmised upward spread of AW heat through the Eurasian Basin halocline. Experiments with a 3D coupled ice–ocean model in turn suggest a loss of 28–35 cm of ice thickness after ∼50 yr in response to the 0.5 W m−2 increase in AW ocean heat flux suggested by the 1D model. This amount of thinning is comparable to the 29 cm of ice thickness loss due to local atmospheric thermodynamic forcing estimated from observations of fast-ice thickness decline. The implication is that AW warming helped precondition the polar ice cap for the extreme ice loss observed in recent years.

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