Impact of local atmospheric intraseasonal variability on mean sea ice state in the Arctic Ocean

The Arctic atmosphere shows significant variability on intraseasonal timescales of 10-90 days. The intraseasonal variability in the Arctic sea ice is clearly related to that in the Arctic atmosphere. It is well-known that the Arctic mean sea ice state is governed by the local mean atmospheric state. However, the response of the Arctic mean sea ice state to the local atmospheric intraseasonal variability is unclear. The Arctic atmospheric intraseasonal variability exists in both the thermodynamical and dynamical variables. Based on a sea ice-ocean coupled simulation with a quantitative sea ice budget analysis, this study finds that: 1) the intraseasonal atmospheric thermodynamical variability tends to reduce sea ice melting through changing the downward heat flux on the open water area in the marginal sea ice zone, and the intraseasonal atmospheric dynamical variability tends to increase sea ice melting by a combination of modified air-ocean, ice-ocean heat fluxes and sea ice deformation. 2) The intraseasonal atmospheric dynamical variability increases summertime sea ice concentration in the Beaufort Sea and the Greenland Sea but decreases summertime sea ice concentration along the Eurasian continent in the East Siberia-Laptev-Kara Seas, resulting from the joint effects of the modified air-ocean, ice-ocean heat fluxes, the sea ice deformation, as well as the mean sea ice advection due to the changes of sea ice drift. The large spread in sea ice in the CMIP models may be partly attributed to the different model performances in representing the observed atmospheric intraseasonal variability. Reliable modeling of atmospheric intraseasonal variability is an essential condition in correctly projecting future sea ice evolution.

Model evaluation of short-lived climate forcers for the Arctic Monitoring and Assessment Programme: a multi-species, multi-model study

The Arctic atmosphere is warming rapidly and its relatively pristine environment is sensitive to the long-range transport of atmospheric pollutants. While carbon dioxide is the main cause for global warming, short-lived climate forcers (SLCFs) such as methane, ozone, and particles also play a role in Arctic climate on near-term time scales. Atmospheric modelling is critical for understanding the abundance and distribution of SLCFs throughout the Arctic atmosphere, and is used as a tool towards determining SLCF impacts on climate and health in the present and in future emissions scenarios. In this study, we evaluate 18 state-of-the-art atmospheric and Earth system models, assessing their representation of Arctic and Northern Hemisphere atmospheric SLCF distributions, considering a wide range of different chemical species (methane, tropospheric ozone and its precursors, black carbon, sulfate, organic aerosol, and particulate matter) and multiple observational datasets. Model simulations over four years (2008–2009 and 2014–2015) conducted for the 2021 Arctic Monitoring and Assessment Programme (AMAP) SLCF assessment report are thoroughly evaluated against satellite, ground, ship and aircraft-based observations. The results show a large range in model performance, with no one particular model or model type performing well for all regions and all SLCF species. The multi-model mean was able to represent the general features of SLCFs in the Arctic, though vertical mixing, long-range transport, deposition, and wildfire emissions remain highly uncertain processes. These need better representation within atmospheric models to improve their simulation of SLCFs in the Arctic environment.

Nitrous oxide and methane in a changing Arctic Ocean

Human activities are changing the Arctic environment at an unprecedented rate resulting in rapid warming, freshening, sea ice retreat and ocean acidification of the Arctic Ocean. Trace gases such as nitrous oxide (N2O) and methane (CH4) play important roles in both the atmospheric reactivity and radiative budget of the Arctic and thus have a high potential to influence the region’s climate. However, little is known about how these rapid physical and chemical changes will impact the emissions of major climate-relevant trace gases from the Arctic Ocean. The combined consequences of these stressors present a complex combination of environmental changes which might impact on trace gas production and their subsequent release to the Arctic atmosphere. Here we present our current understanding of nitrous oxide and methane cycling in the Arctic Ocean and its relevance for regional and global atmosphere and climate and offer our thoughts on how this might change over coming decades.

Continuous CO2 and CH4 Observations in the Coastal Arctic Atmosphere of the Western Taimyr Peninsula, Siberia: The First Results from a New Measurement Station in Dikson

Atmospheric observations of sources and sinks of carbon dioxide (CO2) and methane (CH4) in the pan-Arctic domain are highly sporadic, limiting our understanding of carbon turnover in this climatically sensitive environment and the fate of enormous carbon reservoirs buried in permafrost. Particular gaps apply to the Arctic latitudes of Siberia, covered by the vast tundra ecosystems underlain by permafrost, where only few atmospheric sites are available. The paper presents the first results of continuous observations of atmospheric CO2 and CH4 dry mole fractions at a newly operated station “DIAMIS” (73.30° N, 80.31° E) deployed on the edge of the Dikson settlement on the western coast of the Taimyr Peninsula. Atmospheric mole fractions of CO2, CH4, and H2O are measured by a CRDS analyzer Picarro G2301-f, which is regularly calibrated against WMO-traceable gases. Meteorological records permit screening of trace gas series. Here, we give the scientific rationale of the site, describe the instrumental setup, analyze the local environments, examine the seasonal footprint, and show CO2 and CH4 fluctuations for the daytime mixed atmospheric layer that is representative over a vast Arctic domain (~500–1000 km), capturing both terrestrial and oceanic signals.

Large seasonal and interannual variations of biogenic sulfur compounds in the Arctic atmosphere (Svalbard; 78.9° N, 11.9° E)

Seasonal to interannual variations in the concentrations of sulfur aerosols (< 2.5 µm in diameter; non sea-salt sulfate: NSS-SO42-; anthropogenic sulfate: Anth-SO42-; biogenic sulfate: Bio-SO42-; methanesulfonic acid: MSA) in the Arctic atmosphere were investigated using measurements of the chemical composition of aerosols collected at Ny-Ålesund, Svalbard (78.9∘ N, 11.9∘ E) from 2015 to 2019. In all measurement years the concentration of NSS-SO42- was highest during the pre-bloom period and rapidly decreased towards summer. During the pre-bloom period we found a strong correlation between NSS-SO42- (sum of Anth-SO42- and Bio-SO42-) and Anth-SO42-. This was because more than 50 % of the NSS-SO42- measured during this period was Anth-SO42-, which originated in northern Europe and was subsequently transported to the Arctic in Arctic haze. Unexpected increases in the concentration of Bio-SO42- aerosols (an oxidation product of dimethylsulfide: DMS) were occasionally found during the pre-bloom period. These probably originated in regions to the south (the North Atlantic Ocean and the Norwegian Sea) rather than in ocean areas in the proximity of Ny-Ålesund. Another oxidation product of DMS is MSA, and the ratio of MSA to Bio-SO42- is extensively used to estimate the total amount of DMS-derived aerosol particles in remote marine environments. The concentration of MSA during the pre-bloom period remained low, primarily because of the greater loss of MSA relative to Bio-SO42- and the suppression of condensation of gaseous MSA onto particles already present in air masses being transported northwards from distant ocean source regions (existing particles). In addition, the low light intensity during the pre-bloom period resulted in a low concentration of photochemically activated oxidant species including OH radicals and BrO; these conditions favored the oxidation pathway of DMS to Bio-SO42- rather than to MSA, which acted to lower the MSA concentration at Ny-Ålesund. The concentration of MSA peaked in May or June and was positively correlated with phytoplankton biomass in the Greenland and Barents seas around Svalbard. As a result, the mean ratio of MSA to the DMS-derived aerosols was low (0.09 ± 0.07) in the pre-bloom period but high (0.32 ± 0.15) in the bloom and post-bloom periods. There was large interannual variability in the ratio of MSA to Bio-SO42- (i.e., 0.24 ± 0.11 in 2017, 0.40 ± 0.14 in 2018, and 0.36 ± 0.14 in 2019) during the bloom and post-bloom periods. This was probably associated with changes in the chemical properties of existing particles, biological activities surrounding the observation site, and air mass transport patterns. Our results indicate that MSA is not a conservative tracer for predicting DMS-derived particles, and the contribution of MSA to the growth of newly formed particles may be much larger during the bloom and post-bloom periods than during the pre-bloom period.

Accurate continuous observations of carbon dioxide and methane dry mole fractions in the arctic atmosphere near the Dikson settlement, Siberia

&lt;div&gt; &lt;p&gt;&lt;span&gt;Measurements of the atmospheric sources and sinks of carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) and methane (CH&lt;sub&gt;4&lt;/sub&gt;) in the pan-Arctic domain are extremely sparse that limits our knowledge of carbon cycling over this dramatically sensitive environment and making predictions about a fate of carbon conserved in currently frozen ground. Especially critical are the gaps in the arctic latitudes of Siberia, covered by the vast permafrost underlain tundra, where only few continuous atmospheric observation stations are currently operational.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;We present the first two years of accurate continuous observations of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; dry mole fractions at the new atmospheric carbon observation station located near the Dikson settlement (73.33&amp;#176; N, 80.34&amp;#176; E) on the seashore of the western part of the Taimyr Peninsula in Siberia. Data quality control of trace gas measurements is achieved by regular calibrations against WMO-traceable reference gases from pressurized dry air tanks filled at the Max Planck Institute for Biogeochemistry (Jena, Germany). Associated meteorological variables permit evaluation of the climate variability of the local environment and provide a background for screening and interpreting the greenhouse gases (GHG) data records.&amp;#160;&lt;/span&gt;&lt;span&gt;Here we summarize the scientific rationale of the new site, give technical details of the instrumental setup, analyse the local environments and present CO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt; and CH&lt;/span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;span&gt; fluctuations in the arctic atmosphere. Along with the temporal variability of GHG&amp;#8217;s, we provide an overview of the angular distribution of detected GHG signals in the region and their input to the atmospheric fluctuations on the measurement site. Observation records deal with the daytime mixed layer and may be considered as representative throughout the vast area (~500&amp;#8211;1000 km), and cover the period from September 2018 to September 2020.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;The &lt;/span&gt;&lt;span&gt;reported study&lt;/span&gt;&lt;span&gt; was funded by Russian Foundation for Basic Research, Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science, project number 20-45-242908, RFBR project &lt;/span&gt;&lt;span&gt;18-05-60203&lt;/span&gt;&lt;span&gt; and &lt;/span&gt;&lt;span&gt;by the Max Planck Society (Germany)&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;

Сlimate-active aerosol components in the Siberian Arctic, by data from new-developed research aerosol station on island Bely

&lt;p&gt;Black carbon is a short - living climate forcer, it plays a significant role especially in the Arctic environment due to heating the atmosphere and changing the radiation balance while depositing on snow and ice. Analysis of black carbon (BC) in the Arctic atmosphere shows a contribution of anthropogenic combustion of fossil fuels and natural wildfires to the Arctic atmosphere chemistry as well as of the main characteristics of Arctic aerosol pollution. Presently, assessments of the environment and climate change in the Siberian Arctic are strongly complicated by an existing lack of knowledge about emission sources, quantity, and composition of the aerosol pollution defining the impacts on an Arctic ecosystem.&lt;/p&gt;&lt;p&gt;Research aerosol station is firstly installed on island Bely located in Kara sea, Siberian Arctic. It takes place on the pathway of air mass from the Northern Siberia region of high anthropogenic and gas flaring activity to the Arctic. Presently, assessments of the environment and climate change in this region are strongly complicated by an existing lack of knowledge about emission sources, quantity and composition of the aerosol pollution defining the impacts on an Arctic ecosystem. Aethalometer and aerosol sampling system is continuously operated on the aerosol station in order to analyze black carbon and chemical characteristics including ionic and elemental composition. Annual BC trend obtained from august 2019 to September 2020 shows the typical Arctic aerosol tendency of a seasonal variability, disturbed by episodes of large-scale emission transportation.&lt;/p&gt;&lt;p&gt;Unprecedented&amp;#160;high BC is observed in September 2020 at the research aerosol station on the island Bely. The BC concentrations early in September were exceeded 20 times the arctic background. They are found to be even higher than the highest arctic haze concentrations observed in December 2019.&amp;#160;&amp;#160; Monthly averaged black carbon concentration in September 2020 exceeded 3 times that one in previous summer months. Such strong event is a result of large-scale air mass transportation from Eurasian continent in the period of strong wildfires in western Siberia, namely in Krasnoyarsk Kray and Yakutia, where around one million hectares of forest were burned out in August 2020.&amp;#160;&lt;/p&gt;&lt;p&gt;Basic researches of aerosol characteristics as a tracer of anthropogenic emissions are supported by Russian Fond for Basic Research, project &amp;#8470;18-60084.&lt;/p&gt;&lt;p&gt;.&lt;/p&gt;

Large seasonal and interannual variations of biogenic sulfur compounds in the Arctic atmosphere (Svalbard; 78.9° N, 11.9° E)

Seasonal to interannual variations in the concentrations of sulfur aerosols (