Rare and Extreme Wildland Fire in Sakha in 2021

Abstract The presented picture of the month is a superposition of spaceborne lidar observations and high-resolution temperature fields of the ECMWF Integrated Forecast System (IFS). It displays complex tropospheric and stratospheric clouds in the Arctic winter of 2015/16. Near the end of December 2015, the unusual northeastward propagation of warm and humid subtropical air masses as far north as 80°N lifted the tropopause by more than 3 km in 24 h and cooled the stratosphere on a large scale. A widespread formation of thick cirrus clouds near the tropopause and of synoptic-scale polar stratospheric clouds (PSCs) occurred as the temperature dropped below the thresholds for the existence of cloud particles. Additionally, mountain waves were excited by the strong flow at the western edge of the ridge across Svalbard, leading to the formation of mesoscale ice PSCs. The most recent IFS cycle using a horizontal resolution of 8 km globally reproduces the large-scale and mesoscale flow features and leads to a remarkable agreement with the wave structure revealed by the spaceborne observations.

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Using ship-borne observations of methane isotopic ratio in the Arctic Ocean to understand methane sources in the Arctic

10.5194/acp-2019-595 ◽

2019 ◽

Author(s):

Antoine Berchet ◽

Isabelle Pison ◽

Patrick M. Crill ◽

Brett Thornton ◽

Philippe Bousquet ◽

...

Keyword(s):

Arctic Ocean ◽

Large Scale ◽

Transport Model ◽

Isotopic Ratio ◽

The Arctic ◽

Isotopic Ratios ◽

Air Masses ◽

Remote Areas ◽

The Arctic Ocean

Abstract. Due to the large variety and heterogeneity of sources in remote areas hard to document, the Arctic regional methane budget remain very uncertain. In situ campaigns provide valuable data sets to reduce these uncertainties. Here we analyse data from the SWERUS-C3 campaign, on-board the icebreaker Oden, that took place during summer 2014 in the Arctic Ocean along the Northern Siberian and Alaskan shores. Total concentrations of methane, as well as isotopic ratios were measured continuously during this campaign for 35 days in July and August 2014. Using a chemistry-transport model, we link observed concentrations and isotopic ratios to regional emissions and hemispheric transport structures. A simple inversion system helped constraining source signatures from wetlands in Siberia and Alaska and oceanic sources, as well as the isotopic composition of lower stratosphere air masses. The variation in the signature of low stratosphere air masses, due to strongly fractionating chemical reactions in the stratosphere, was suggested to explain a large share of the observed variability in isotopic ratios. These points at required efforts to better simulate large scale transport and chemistry patterns to use isotopic data in remote areas. It is found that constant and homogeneous source signatures for each type of emission in the region (mostly wetlands and oil and gas industry) is not compatible with the strong synoptic isotopic signal observed in the Arctic. A regional gradient in source signatures is highlighted between Siberian and Alaskan wetlands, the later ones having a lighter signatures than the first ones. Arctic continental shelf sources are suggested to be a mixture of methane from a dominant thermogenic origin and a secondary biogenic one, consistent with previous in-situ isotopic analysis of seepage along the Siberian shores.

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Influence of Atlantic inflow on the freshwater content in the upper layer of the Arctic basin

Arctic and Antarctic Research ◽

10.30758/0555-2648-2019-65-4-363-388 ◽

2019 ◽

Vol 65 (4) ◽

pp. 363-388

Author(s):

G. V. Alekseev ◽

A. V. Pnyushkov ◽

A. V. Smirnov ◽

A. E. Vyazilova ◽

N. I. Glok

Keyword(s):

Fresh Water ◽

Large Scale ◽

Barents Sea ◽

Lower Boundary ◽

Arctic Basin ◽

Water Layer ◽

Atlantic Water ◽

Water Masses ◽

The Arctic ◽

The North

Inter-decadal changes in the water layer of Atlantic origin and freshwater content (FWC) in the upper 100 m layer were traced jointly to assess the influence of inflows from the Atlantic on FWC changes based on oceanographic observations in the Arctic Basin for the 1960s – 2010s. For this assessment, we used oceanographic data collected at the Arctic and Antarctic Research Institute (AARI) and the International Arctic Research Center (IARC). The AARI data for the decades of 1960s – 1990s were obtained mainly at the North Pole drifting ice camps, in high-latitude aerial surveys in the 1970s, as well as in ship-based expeditions in the 1990s. The IARC database contains oceanographic measurements acquired using modern CTD (Conductivity – Temperature – Depth) systems starting from the 2000s. For the reconstruction of decadal fields of the depths of the upper and lower 0 °С isotherms and FWC in the 0–100 m layer in the periods with a relatively small number of observations (1970s – 1990s), we used a climatic regression method based on the conservativeness of the large-scale structure of water masses in the Arctic Basin. Decadal fields with higher data coverage were built using the DIVAnd algorithm. Both methods showed almost identical results when compared. The results demonstrated that the upper boundary of the Atlantic water (AW) layer, identified with the depth of zero isotherm, raised everywhere by several tens of meters in 1990s – 2010s, when compared to its position before the start of warming in the 1970s. The lower boundary of the AW layer, also determined by the depth of zero isotherm, became deeper. Such displacements of the layer boundaries indicate an increase in the volume of water in the Arctic Basin coming not only through the Fram Strait, but also through the Barents Sea. As a result, the balance of water masses was disturbed and its restoration had to occur due to the reduction of the volume of the upper most dynamic freshened layer. Accordingly, the content of fresh water in this layer should decrease. Our results confirmed that FWC in the 0–100 m layer has decreased to 2 m in the Eurasian part of the Arctic Basin to the west of 180° E in the 1990s. In contrast, the FWC to the east of 180° E and closer to the shores of Alaska and the Canadian archipelago has increased. These opposite tendencies have been intensified in the 2000s and the 2010s. A spatial correlation between distributions of the FWC and the positions of the upper AW boundary over different decades confirms a close relationship between both distributions. The influence of fresh water inflow is manifested as an increase in water storage in the Canadian Basin and the Beaufort Gyre in the 1990s – 2010s. The response of water temperature changes from the tropical Atlantic to the Arctic Basin was traced, suggesting not only the influence of SST at low latitudes on changes in FWC, but indicating the distant tropical impact on Arctic processes.

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Using ship-borne observations of methane isotopic ratio in the Arctic Ocean to understand methane sources in the Arctic

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-3987-2020 ◽

2020 ◽

Vol 20 (6) ◽

pp. 3987-3998 ◽

Cited By ~ 3

Author(s):

Antoine Berchet ◽

Isabelle Pison ◽

Patrick M. Crill ◽

Brett Thornton ◽

Philippe Bousquet ◽

...

Keyword(s):

Arctic Ocean ◽

Large Scale ◽

Oil And Gas ◽

Lower Stratosphere ◽

Transport Model ◽

Isotopic Ratio ◽

Oil And Gas Industry ◽

The Arctic ◽

Isotopic Ratios ◽

Air Masses

Abstract. Characterizing methane sources in the Arctic remains challenging due to the remoteness, heterogeneity and variety of such emissions. In situ campaigns provide valuable datasets to reduce these uncertainties. Here we analyse data from the summer 2014 SWERUS-C3 campaign in the eastern Arctic Ocean, off the shore of Siberia and Alaska. Total concentrations of methane, as well as relative concentrations of 12CH4 and 13CH4, were measured continuously during this campaign for 35 d in July and August. Using a chemistry-transport model, we link observed concentrations and isotopic ratios to regional emissions and hemispheric transport structures. A simple inversion system helped constrain source signatures from wetlands in Siberia and Alaska, and oceanic sources, as well as the isotopic composition of lower-stratosphere air masses. The variation in the signature of lower-stratosphere air masses, due to strongly fractionating chemical reactions in the stratosphere, was suggested to explain a large share of the observed variability in isotopic ratios. These results point towards necessary efforts to better simulate large-scale transport and chemistry patterns to make relevant use of isotopic data in remote areas. It is also found that constant and homogeneous source signatures for each type of emission in a given region (mostly wetlands and oil and gas industry in our case at high latitudes) are not compatible with the strong synoptic isotopic signal observed in the Arctic. A regional gradient in source signatures is highlighted between Siberian and Alaskan wetlands, the latter having lighter signatures (more depleted in 13C). Finally, our results suggest that marine emissions of methane from Arctic continental-shelf sources are dominated by thermogenic-origin methane, with a secondary biogenic source as well.

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Freshwater pulses in the eastern Arctic Ocean during Saalian and Early Weichselian ice-sheet collapse

Quaternary Research ◽

10.1016/j.yqres.2003.07.008 ◽

2003 ◽

Vol 60 (3) ◽

pp. 243-251 ◽

Cited By ~ 26

Author(s):

Jochen Knies ◽

Christoph Vogt

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Large Scale ◽

Barents Sea ◽

The Arctic ◽

Fram Strait ◽

Nordic Seas ◽

The Arctic Ocean ◽

Transpolar Drift ◽

Mis 5

AbstractImproved multiparameter records from the northern Barents Sea margin show two prominent freshwater pulses into the Arctic Ocean during MIS 5 that significantly disturbed the regional oceanic regime and probably affected global climate. Both pulses are associated with major iceberg-rafted debris (IRD) events, revealing intensive iceberg/sea ice melting. The older meltwater pulse occurred near the MIS 5/6 boundary (∼131,000 yr ago); its ∼2000 year duration and high IRD input accompanied by high illite content suggest a collapse of large-scale Saalian Glaciation in the Arctic Ocean. Movement of this meltwater with the Transpolar Drift current into the Fram Strait probably promoted freshening of Nordic Seas surface water, which may have increased sea-ice formation and significantly reduced deep-water formation. A second pulse of freshwater occurred within MIS 5a (∼77,000 yr ago); its high smectite content and relatively short duration is possibly consistent with sudden discharge of Early Weichselian ice-dammed lakes in northern Siberia as suggested by terrestrial glacial geologic data. The influence of this MIS 5a meltwater pulse has been observed at a number of sites along the Transpolar Drift, through Fram Strait, and into the Nordic Seas; it may well have been a trigger for the North Atlantic cooling event C20.

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Interannual characteristics of an 80 km resolution diagnostic Arctic ice–ocean model

Annals of Glaciology ◽

10.1017/s0260305500009861 ◽

1991 ◽

Vol 15 ◽

pp. 155-162 ◽

Cited By ~ 4

Author(s):

John E. Ries ◽

William D. Hibler

Keyword(s):

Ocean Circulation ◽

Large Scale ◽

Eddy Viscosity ◽

Barents Sea ◽

Arctic Basin ◽

Ocean Model ◽

The Arctic ◽

Atmospheric Forcing ◽

Ice Edge ◽

Arctic Ice

Seasonal simulations with large-scale coupled ice–ocean models have reproduced many features of the ice and ocean circulation of the Arctic Ocean and the Greenland and Norwegian seas (e.g. Hibler and Bryan, 1987; Semtner, 1987). However, the crude resolution and high lateral eddy viscosity used by these models prevent the simulation of many of the smaller-scale seasonal features and tend to produce sluggish circulation. Similarly, the use of a single year’s atmospheric forcing prevents the simulation of features on an interannual time-scale. As an initial step towards addressing these issues, an 80 km diagnostic Arctic ice–ocean model is constructed and integrated over a three-year period using daily atmospheric forcing to drive the model. To examine the effect of topographic resolution and eddy viscosity on model results, similar simulations were performed with a 160 km-resolution model. The results of these simulations are compared with one another, with buoy drift in the Arctic Basin, and with observed ice-edge variations. The model results proved most sensitive to changes in horizontal resolution. The 80 km results provided a more realistic and robust circulation in most areas of the Arctic and improved the modelled ice edge in the Barents Sea, while also successfully simulating the interannual variation in the region. Although it performed better than the 160 km model, the 80 km model still produced too large an ice extent in the Greenland Sea. No significant improvement in the ice-edge prediction was observed by varying the lateral eddy viscosity. The results indicate that problems remain in the vertical resolution in shallow regions, in treating penetrative convection, and in the simulation of inflow into the Arctic Basin through the Fram Strait.

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Inferring Circulation and Lateral Eddy Fluxes in the Arctic Ocean’s Deep Canada Basin Using an Inverse Method

Journal of Physical Oceanography ◽

10.1175/jpo-d-17-0190.1 ◽

2018 ◽

Vol 48 (2) ◽

pp. 245-260 ◽

Cited By ~ 7

Author(s):

Hayley V. Dosser ◽

Mary-Louise Timmermans

Keyword(s):

Inverse Method ◽

Large Scale ◽

Barents Sea ◽

Function Analysis ◽

Water Layer ◽

Atlantic Water ◽

Canada Basin ◽

The Arctic ◽

Central Basin ◽

Beaufort Gyre

AbstractThe deep waters in the Canada Basin display a complex temperature and salinity structure, the evolution of which is poorly understood. The fundamental physical processes driving changes in these deep water masses are investigated using an inverse method based on tracer conservation combined with empirical orthogonal function analysis of repeat hydrographic measurements between 2003 and 2015. Changes in tracer fields in the deep Canada Basin are found to be dominated by along-isopycnal diffusion of water properties from the margins into the central basin, with advection by the large-scale Beaufort Gyre circulation as well as localized, vertical mixing playing important secondary roles. In the Barents Sea branch of the Atlantic Water layer, centered around 1200-m depth, diffusion is shown to be nearly twice as important as advection to lateral transport. Along-isopycnal diffusivity is estimated to be ~300–600 m2 s−1. Large-scale circulation patterns and lateral advective velocities associated with the anticyclonic Beaufort Gyre are inferred, with an average speed of 0.6 cm s−1. Below about 1500 m, along-isopycnal diffusivity is estimated to be ~200–400 m2 s−1.

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Coreless winters in the European sector of the Arctic and their synoptic conditions

Polish Polar Research ◽

10.2478/v10183-012-0007-2 ◽

2012 ◽

Vol 33 (1) ◽

pp. 19-34 ◽

Cited By ~ 3

Author(s):

Ewa Bednorz ◽

Krzysztof Fortuniak

Keyword(s):

Air Temperature ◽

Large Scale ◽

Barents Sea ◽

The Arctic ◽

The North ◽

Circulation Types ◽

Synoptic Conditions ◽

Before And After ◽

Icelandic Low ◽

European Sector

Coreless winters in the European sector of the Arctic and their synoptic conditions The coreless winters (i.e. not having a cold core) were distinguished in four stations within the European sector of the Arctic. Anomalies of the frequency of the Niedźwiedź's (2011) circulation types were calculated separately for the mid-winter warm months and for cold months preceding and following the warm-spells. Furthermore, composite and anomaly maps of the sea level pressure as s well as anomaly maps of the air temperature at 850 gpm (geopotential meters) were constructed separately for the mid-winter warm events and for the cold months before and after warming. Different pressure patterns were recognized among the days of mid-winter warm spells, using the clustering method. The occurrence of coreless winters in the study area seems to be highly controlled by the position, extension and intensity of large scale atmospheric systems, mainly the Icelandic Low. When the Low spreads to the east and its centre locates over the Barents Sea the inflow of air masses from the northern quadrant is observed over the North Atlantic. This brings cold air of Arctic origin to the islands and causes an essential drop in the air temperature. Such situation takes place during the cold months preceding and following the warm mid-winter events. During the warm spells the Icelandic Low gets deeper-than-usual and it is pushed to the northeast, which contributes to the air inflow from the southern quadrant.

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Interannual characteristics of an 80 km resolution diagnostic Arctic ice–ocean model

Annals of Glaciology ◽

10.3189/1991aog15-1-552-162 ◽

1991 ◽

Vol 15 ◽

pp. 155-162 ◽

Cited By ~ 2

Author(s):

John E. Ries ◽

William D. Hibler

Keyword(s):

Ocean Circulation ◽

Large Scale ◽

Eddy Viscosity ◽

Barents Sea ◽

Arctic Basin ◽

Ocean Model ◽

The Arctic ◽

Atmospheric Forcing ◽

Ice Edge ◽

Arctic Ice

Seasonal simulations with large-scale coupled ice–ocean models have reproduced many features of the ice and ocean circulation of the Arctic Ocean and the Greenland and Norwegian seas (e.g. Hibler and Bryan, 1987; Semtner, 1987). However, the crude resolution and high lateral eddy viscosity used by these models prevent the simulation of many of the smaller-scale seasonal features and tend to produce sluggish circulation. Similarly, the use of a single year’s atmospheric forcing prevents the simulation of features on an interannual time-scale. As an initial step towards addressing these issues, an 80 km diagnostic Arctic ice–ocean model is constructed and integrated over a three-year period using daily atmospheric forcing to drive the model. To examine the effect of topographic resolution and eddy viscosity on model results, similar simulations were performed with a 160 km-resolution model. The results of these simulations are compared with one another, with buoy drift in the Arctic Basin, and with observed ice-edge variations. The model results proved most sensitive to changes in horizontal resolution. The 80 km results provided a more realistic and robust circulation in most areas of the Arctic and improved the modelled ice edge in the Barents Sea, while also successfully simulating the interannual variation in the region. Although it performed better than the 160 km model, the 80 km model still produced too large an ice extent in the Greenland Sea. No significant improvement in the ice-edge prediction was observed by varying the lateral eddy viscosity. The results indicate that problems remain in the vertical resolution in shallow regions, in treating penetrative convection, and in the simulation of inflow into the Arctic Basin through the Fram Strait.

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Analysis of the Arctic System for Freshwater Cycle Intensification: Observations and Expectations

Journal of Climate ◽

10.1175/2010jcli3421.1 ◽

2010 ◽

Vol 23 (21) ◽

pp. 5715-5737 ◽

Cited By ~ 193

Author(s):

Michael A. Rawlins ◽

Michael Steele ◽

Marika M. Holland ◽

Jennifer C. Adam ◽

Jessica E. Cherry ◽

...

Keyword(s):

Arctic Ocean ◽

River Discharge ◽

General Circulation ◽

Large Scale ◽

Barents Sea ◽

Dominant Role ◽

General Circulation Models ◽

The Arctic ◽

Observation System ◽

Freshwater Flux

Abstract Hydrologic cycle intensification is an expected manifestation of a warming climate. Although positive trends in several global average quantities have been reported, no previous studies have documented broad intensification across elements of the Arctic freshwater cycle (FWC). In this study, the authors examine the character and quantitative significance of changes in annual precipitation, evapotranspiration, and river discharge across the terrestrial pan-Arctic over the past several decades from observations and a suite of coupled general circulation models (GCMs). Trends in freshwater flux and storage derived from observations across the Arctic Ocean and surrounding seas are also described. With few exceptions, precipitation, evapotranspiration, and river discharge fluxes from observations and the GCMs exhibit positive trends. Significant positive trends above the 90% confidence level, however, are not present for all of the observations. Greater confidence in the GCM trends arises through lower interannual variability relative to trend magnitude. Put another way, intrinsic variability in the observations tends to limit confidence in trend robustness. Ocean fluxes are less certain, primarily because of the lack of long-term observations. Where available, salinity and volume flux data suggest some decrease in saltwater inflow to the Barents Sea (i.e., a decrease in freshwater outflow) in recent decades. A decline in freshwater storage across the central Arctic Ocean and suggestions that large-scale circulation plays a dominant role in freshwater trends raise questions as to whether Arctic Ocean freshwater flows are intensifying. Although oceanic fluxes of freshwater are highly variable and consistent trends are difficult to verify, the other components of the Arctic FWC do show consistent positive trends over recent decades. The broad-scale increases provide evidence that the Arctic FWC is experiencing intensification. Efforts that aim to develop an adequate observation system are needed to reduce uncertainties and to detect and document ongoing changes in all system components for further evidence of Arctic FWC intensification.

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