Arctic Cyclone Activity and the Beaufort High

2021 ◽  
pp. 1-22
Author(s):  
Jessica S. Kenigson ◽  
M.-L. Timmermans
Keyword(s):  
Regime Shift ◽  
The Arctic ◽  
Cyclone Activity ◽  
Sea Level Pressure ◽  
Nordic Seas ◽  
Beaufort Gyre ◽  
Time Periods ◽  
Freshwater Reservoir ◽  
Gyre Circulation ◽  
Activity Indices

AbstractThe Beaufort High (BH) and its accompanying anticyclonic winds drive the Arctic Ocean’s Beaufort Gyre, the major freshwater reservoir of the Arctic Ocean. The Beaufort Gyre circulation and its capacity to accumulate or release freshwater relies on the BH intensity. The migration of Nordic Seas cyclones into the Arctic has been hypothesized to moderate the strength of the BH. We explore this hypothesis by analyzing reanalysis sea-level pressure (SLP) fields to characterize the BH and identify and track cyclones north of 60°N during 1948-2019. A cluster analysis of Nordic Seas cyclone trajectories reveals a western pathway (through the Arctic interior) associated with a relatively weak BH and an eastern pathway (along the Arctic periphery) associated with a relatively strong BH. Furthermore, we construct cyclone activity indices (CAIs) in the Arctic and Nordic Seas which take into account multiple cyclone parameters (number, strength, duration). There are significant correlations between the BH and the CAIs in the Arctic and Nordic Seas during 1948-2019, with anomalously strong cyclone activity related to an anomalously weak BH, and vice versa. We show how the Arctic and Nordic Seas CAIs experienced a regime shift towards increased cyclone activity between the first four decades analyzed (1948-1988) and the most recent three decades (1989-2019). Over the same two time periods, the BH exhibits a weakening. Increased cyclone activity and an accompanying weakening of the BH may be consistent with expectations in a warming Arctic, and has implications for Beaufort Gyre dynamics and freshwater.

Cold and Fresh Biases of the Arctic Atlantic Water Layer in CMIP6 Models; Potential Origin and Implications

2020 ◽  
Author(s):  
Narges Khosravi ◽  
Nikolay Koldunov ◽  
Qiang Wang ◽  
Sergery Danilov ◽  
Claudia Hinrichs ◽  
...  
Keyword(s):  
Water Layer ◽  
Atlantic Water ◽  
The Arctic ◽  
Sea Level Pressure ◽  
Climate Signal ◽  
Nordic Seas ◽  
East Greenland Current ◽  
Gyre Circulation ◽  
Rule Out ◽  
Potential Origin

<p><span>We examined the Arctic Atlantic Water (AW) layer in the CMIP6 models. Climatological means of temperature and salinity at 400 m depth from multi-model averages are compared with observations, showing significant biases in both variables. Based on the currently available data, we showed that the CMIP6 models have cold and fresh biases in the Arctic AW layer, and warm and saline biases in the East Greenland Current. The temperature biases are comparable to the climate signal magnitude for temperature, predicted by the CMIP6 models for the end of the 21st century. For salinity, the biases are shown to be even more pronounced than the predicted signals. CMIP6 models also show positive sea-level pressure (SLP) and sea-surface height </span>(SSH) <span>biases in the Nordic Seas. </span>We argue <span>that the identified SLP bias leads to an anomalously weak cyclonic gyre circulation in the Nordic seas, as shown through positive SSH bias. This could cause weaker AW inflow through the Fram Strait, which explains the detected hydrography biases in the AW layer. While we do not rule out other possible factors contributing to the weak AW flow to the Arctic Ocean, we suggest that the identified ocean biases within the CMIP6 models are at least partially driven b</span>y<span> atmospheric origins.</span></p>

scholarly journals Arctic Ocean surface geostrophic circulation 2003–2014

2017 ◽  
Vol 11 (4) ◽  
pp. 1767-1780 ◽  
Author(s):  
Thomas W. K. Armitage ◽  
Sheldon Bacon ◽  
Andy L. Ridout ◽  
Alek A. Petty ◽  
Steven Wolbach ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Decadal Variability ◽  
Arctic Basin ◽  
Ocean Surface ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Atmospheric Forcing ◽  
Geostrophic Currents ◽  
Beaufort Gyre ◽  
Gyre Circulation

Abstract. Monitoring the surface circulation of the ice-covered Arctic Ocean is generally limited in space, time or both. We present a new 12-year record of geostrophic currents at monthly resolution in the ice-covered and ice-free Arctic Ocean derived from satellite radar altimetry and characterise their seasonal to decadal variability from 2003 to 2014, a period of rapid environmental change in the Arctic. Geostrophic currents around the Arctic basin increased in the late 2000s, with the largest increases observed in summer. Currents in the southeastern Beaufort Gyre accelerated in late 2007 with higher current speeds sustained until 2011, after which they decreased to speeds representative of the period 2003–2006. The strength of the northwestward current in the southwest Beaufort Gyre more than doubled between 2003 and 2014. This pattern of changing currents is linked to shifting of the gyre circulation to the northwest during the time period. The Beaufort Gyre circulation and Fram Strait current are strongest in winter, modulated by the seasonal strength of the atmospheric circulation. We find high eddy kinetic energy (EKE) congruent with features of the seafloor bathymetry that are greater in winter than summer, and estimates of EKE and eddy diffusivity in the Beaufort Sea are consistent with those predicted from theoretical considerations. The variability of Arctic Ocean geostrophic circulation highlights the interplay between seasonally variable atmospheric forcing and ice conditions, on a backdrop of long-term changes to the Arctic sea ice–ocean system. Studies point to various mechanisms influencing the observed increase in Arctic Ocean surface stress, and hence geostrophic currents, in the 2000s – e.g. decreased ice concentration/thickness, changing atmospheric forcing, changing ice pack morphology; however, more work is needed to refine the representation of atmosphere–ice–ocean coupling in models before we can fully attribute causality to these increases.

scholarly journals Arctic Ocean geostrophic circulation 2003-2014

2017 ◽  
Author(s):  
Thomas W. K. Armitage ◽  
Sheldon Bacon ◽  
Andy L. Ridout ◽  
Alek A. Petty ◽  
Steven Wolbach ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Decadal Variability ◽  
Arctic Basin ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Atmospheric Forcing ◽  
Geostrophic Currents ◽  
Beaufort Gyre ◽  
Ice Conditions ◽  
Gyre Circulation

Abstract. Monitoring the surface circulation of the ice-covered Arctic Ocean is generally limited in space, time or both. We present a new 12-year record of geostrophic currents at monthly resolution in the ice-covered and ice-free Arctic Ocean and characterise their seasonal to decadal variability from 2003-2014, a period of rapid environmental change in the Arctic. Geostrophic currents around the Arctic basin increased in the late '00s, with the largest increases observed in summer. Currents in the southeastern Beaufort gyre accelerated in late 2007 with higher current speeds sustained until 2011, after which they decreased to speeds representative of the period 2003-2006. The strength of the northwestward current in the southwest Beaufort gyre more than doubled between 2003 and 2014. This pattern of changing currents is linked to shifting of the gyre circulation to the northwest during the time period. The Beaufort gyre circulation and Fram Strait current are strongest in winter, modulated by the seasonal strength of the atmospheric circulation. Eddy kinetic energy is also larger in winter and we find high eddy activity congruent with features of the seafloor bathymetry. The variability of Arctic Ocean geostrophic circulation highlights the interplay between seasonally variable atmospheric forcing and ice conditions, on a backdrop of long term changes to the Arctic sea ice-ocean system. Studies point to various mechanisms influencing the observed increase in Arctic Ocean surface stress, and hence geostrophic currents, in the '00s – e.g. decreased ice concentration/thickness, changing atmospheric forcing, changing ice pack morphology – however more work is needed to refine the representation of atmosphere-ice-ocean coupling in models before we can fully attribute causality to these increases.

scholarly journals 90 years of Arctic Ocean Exploration at the Woods Hole Oceanographic Institution

2020 ◽  
Vol 48 (3) ◽  
pp. 164-198
Author(s):  
A.Yu. Proshutinsky ◽  
J.M. Toole ◽  
R.A. Krishfield ◽  
D.M. Anderson ◽  
C.J. Ashjian ◽  
...  
Keyword(s):  
Time Series Data ◽  
World Ocean ◽  
Satellite Communications ◽  
Series Data ◽  
Upper Ocean ◽  
Woods Hole Oceanographic Institution ◽  
Research Education ◽  
Beaufort Gyre ◽  
Freshwater Reservoir ◽  
Gyre Circulation

In 2020, the Woods Hole Oceanographic Institution (WHOI) celebrates 90 years of research, education, and exploration of the World Ocean. Since inception this has included Arctic studies. In fact, WHOI’s first technical report is on the oceanographic data obtained during the submarine “Nautilus” polar expedition in 1931. In 1951 and 1952, WHOI scientists supervised the collection of hydrographic data during the U.S. Navy SkiJump I & II expeditions utilizing ski-equipped aircraft landings in the Beaufort Sea, and inferred the Beaufort Gyre circulation cell and existence of a mid-Arctic ridge. Later classified studies, particularly concerning under-ice acoustics, were conducted by WHOI personnel from Navy and Air Force ice camps. With the advent of simple satellite communications and positioning, WHOI oceanographers began to deploy buoys on sea ice to obtain surface atmosphere, ice, and upper ocean time series data in the central Arctic beginning in 1987. Observations from these first systems were limited technologically to discrete depths and constrained by power considerations, satellite throughput, as well as high costs. As technologies improved, WHOI developed the drifting Ice-Tethered Profiler (ITP) to obtain vertically continuous upper ocean data several times per day in the ice-covered basins and telemeter the data back in near real time to the lab. Since the 1980s, WHOI scientists have also been involved in geological, biological, ecological and geochemical studies of Arctic waters, typically from expeditions utilizing icebreaking vessels, or air supported drifting platforms. Since the 2000s, WHOI has maintained oceanographic moorings on the Beaufort Shelf and in the deep Canada Basin, the latter an element of the Beaufort Gyre Observing System (BGOS). BGOS maintains oceanographic moorings via icebreaker, and conducts annual hydrographic and geochemical surveys each summer to document the Beaufort Gyre freshwater reservoir that has changed significantly since earlier investigations from the 1950s–1980s. With the experience and results demonstrated over the past decades for furthering Arctic research, WHOI scientists are well positioned to continue to explore and study the polar oceans in the decades ahead

scholarly journals Dipole Anomaly in the Winter Arctic Atmosphere and Its Association with Sea Ice Motion

2006 ◽  
Vol 19 (2) ◽  
pp. 210-225 ◽  
Author(s):  
Bingyi Wu ◽  
Jia Wang ◽  
John E. Walsh
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
Arctic Basin ◽  
The Arctic ◽  
Positive Phase ◽  
Laptev Sea ◽  
Nordic Seas ◽  
Beaufort Gyre ◽  
Arctic Atmosphere ◽  
The Laptev Sea

Abstract This paper identified an atmospheric circulation anomaly–dipole structure anomaly in the Arctic atmosphere and its relationship with winter sea ice motion, based on the International Arctic Buoy Program (IABP) dataset (1979–98) and datasets from the National Centers for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) for the period 1960–2002. The dipole anomaly corresponds to the second-leading mode of EOF of monthly mean sea level pressure (SLP) north of 70°N during the winter season (October–March) and accounts for 13% of the variance. One of its two anomalous centers is stably occupied between the Kara Sea and Laptev Sea; the other is situated from the Canadian Archipelago through Greenland extending southeastward to the Nordic seas. The dipole anomaly differs from one described in other papers that can be attributed to an eastward shift of the center of action of the North Atlantic Oscillation. The finding shows that the dipole anomaly also differs from the “Barents Oscillation” revealed in a study by Skeie. Since the dipole anomaly shows a strong meridionality, it becomes an important mechanism to drive both anomalous sea ice exports out of the Arctic Basin and cold air outbreaks into the Barents Sea, the Nordic seas, and northern Europe. When the dipole anomaly remains in its positive phase, that is, negative SLP anomalies appear between the Kara Sea and the Laptev Sea with concurrent positive SLP over from the Canadian Archipelago extending southeastward to Greenland, there are large-scale changes in the intensity and character of sea ice transport in the Arctic basin. The significant changes include a weakening of the Beaufort gyre, an increase in sea ice export out of the Arctic basin through Fram Strait and the northern Barents Sea, and enhanced sea ice import from the Laptev Sea and the East Siberian Sea into the Arctic basin. Consequently, more sea ice appears in the Greenland and the Barents Seas during the positive phase of the dipole anomaly. During the negative phase of the dipole anomaly, SLP anomalies show an opposite scenario in the Arctic Ocean and its marginal seas when compared to the positive phase, with the center of negative SLP anomalies over the Nordic seas. Correspondingly, sea ice exports decrease from the Arctic basin flowing into the Nordic seas and the northern Barents Sea because of the strengthened Beaufort gyre. The finding indicates that influences of the dipole anomaly on winter sea ice motion are greater than that of the winter AO, particularly in the central Arctic basin and northward to Fram Strait, implying that effects of the dipole anomaly on sea ice export out of the Arctic basin become robust. The dipole anomaly is closely related to atmosphere–ice–ocean interactions that influence the Barents Sea sector.

scholarly journals Holocene dynamics in the Bering Strait inflow to the Arctic and the Beaufort Gyre circulation based on sedimentary records from the Chukchi Sea

2016 ◽  
Author(s):  
Masanobu Yamamoto ◽  
Seung Il Nam ◽  
Leonid Polyak ◽  
Daisuke Kobayashi ◽  
Kenta Suzuki ◽  
...  
Keyword(s):  
North Atlantic ◽  
Chukchi Sea ◽  
The Arctic ◽  
Bering Strait ◽  
The Holocene ◽  
The North ◽  
Beaufort Gyre ◽  
The North Atlantic ◽  
Gyre Circulation

Abstract. The Beaufort Gyre (BG) and the Bering Strait inflow (BSI) are important elements of the Arctic Ocean circulation system and major controls on the distribution of Arctic sea ice. We report records of the quartz/feldspar and chlorite/illite ratios in two sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BG circulation and the BSI during the Holocene. The quartz/feldspar ratio, a proxy of the BG strength, gradually decreased during the Holocene, suggesting a long-term decline in the BG strength, consistent with orbitally-controlled decrease in summer insolation. We suppose that the BG rotation weakened as a result of increasing stability of sea-ice cover at the margins of the Canada Basin, driven by decreasing insolation. Millennial to multi-centennial variability in the quartz/feldspar ratio (the BG circulation) is consistent with fluctuations in solar irradiance, suggesting that solar activity affected the BG strength on these timescales. The BSI, approximated by the chlorite/illite record, shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of an overall weaker Aleutian Low. This middle Holocene strengthening of the BSI was coeval with intense subpolar gyre circulation in the North Atlantic. We propose that the BSI is linked with the North Atlantic circulation via an atmospheric teleconnection between the Aleutian and Icelandic Lows. A correspondence between the Holocene variability of the BSI and North Atlantic Drift suggests that this connection is involved in a mechanism muting salinity changes in the North Atlantic, and thereby stabilizing the Atlantic Meridional Overturning Circulation.

Atmospheric Forcing on the Barents Sea Winter Ice Extent

2006 ◽  
Vol 19 (19) ◽  
pp. 4772-4784 ◽  
Author(s):  
Asgeir Sorteberg ◽  
Børge Kvingedal
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
The Arctic ◽  
Atmospheric Forcing ◽  
Mean Flow ◽  
Cyclone Activity ◽  
Sea Ice Extent ◽  
Nordic Seas ◽  
The Barents Sea ◽  
The Mean

Abstract The atmospheric forcing on the Barents Sea ice extent during winter [December–February (DJF)] has been investigated for the period 1967–2002. The time series for the sea ice extent is updated and includes the winter of 2005, which marks a new record low in the wintertime Barents Sea ice extent, and a linear trend of −3.5% decade−1 in the ice extent was found. Covariability between the Barents Sea ice extent and the atmospheric mean seasonal flow and the synoptic cyclones has been discussed separately. For the mean flow, linear correlations and regression analysis reveal that anomalous northerly (southerly) winds prevail in the Nordic Seas during winters with extensive (sparse) Barents Sea ice extent. Some of the variability in the mean flow is captured by the North Atlantic Oscillation (NAO); however, the wintertime link between the Barents Sea ice extent and the NAO is moderate. By studying the cyclone activity in the high-latitude Northern Hemisphere using a dataset of individual cyclones, two regions that influence the wintertime Barents Sea ice extent were identified. The variability in the northward-moving cyclones traveling into the Arctic over East Siberia was found to covary strongly with the Barents Sea ice extent. The main mechanism is believed to be the change in the Arctic winds and in ice advection connected to the cyclones. In addition, cyclone activity of northward-moving cyclones over the western Nordic Seas was identified to strongly influence the Barents Sea ice extent. This relationship was particularly strong on decadal time scales and when the ice extent lagged the cyclone variability by 1–2 yr. The lag indicates that the mechanism is related to the cyclones’ ability to modulate the inflow of Atlantic water into the Nordic Seas and the transport time of oceanic heat anomalies from the Nordic Seas into the Barents Sea. Multiple regression indicates that the two mechanisms may explain (or at least covary with) 46% of the wintertime Barents Sea variance over the 1967–2002 period and that 79% of the decadal part of the ice variability may be predicted 2 yr ahead using information about the decadal cyclone variability in the Nordic Seas.

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