scholarly journals A hypothesis on variability of surface water <italic>p</italic>CO<sub>2</sub> under the rapid sea-ice retreat during summer in the Arctic Ocean

2016 ◽  
Vol 61 (21) ◽  
pp. 2419-2425
Author(s):  
LiQi CHEN ◽  
Di QI ◽  
ZhongYong GAO ◽  
LiYang ZHAN ◽  
Heng SUN ◽  
...  
Keyword(s):  
Surface Water ◽  
Sea Ice ◽  
Arctic Ocean ◽  
The Arctic ◽  
The Arctic Ocean ◽  
Ice Retreat ◽  
Sea Ice Retreat

scholarly journals Contributions of advection and melting processes to the decline in sea ice in the Pacific sector of the Arctic Ocean

2019 ◽  
Vol 13 (5) ◽  
pp. 1423-1439 ◽  
Author(s):  
Haibo Bi ◽  
Qinghua Yang ◽  
Xi Liang ◽  
Liang Zhang ◽  
Yunhe Wang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Melting Process ◽  
The Arctic ◽  
Positive Trend ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Ice Retreat ◽  
The Mean ◽  
Sea Ice Retreat

Abstract. The Pacific sector of the Arctic Ocean (PA, hereafter) is a region sensitive to climate change. Given the alarming changes in sea ice cover during recent years, knowledge of sea ice loss with respect to ice advection and melting processes has become critical. With satellite-derived products from the National Snow and Ice Center (NSIDC), a 38-year record (1979–2016) of the loss in sea ice area in summer within the Pacific-Arctic (PA) sector due to the two processes is obtained. The average sea ice outflow from the PA to the Atlantic-Arctic (AA) Ocean during the summer season (June–September) reaches 0.173×106 km2, which corresponds to approximately 34 % of the mean annual export (October to September). Over the investigated period, a positive trend of 0.004×106 km2 yr−1 is also observed for the outflow field in summer. The mean estimate of sea ice retreat within the PA associated with summer melting is 1.66×106 km2, with a positive trend of 0.053×106 km2 yr−1. As a result, the increasing trends of ice retreat caused by outflow and melting together contribute to a stronger decrease in sea ice coverage within the PA (0.057×106 km2 yr−1) in summer. In percentage terms, the melting process accounts for 90.4 % of the sea ice retreat in the PA in summer, whereas the remaining 9.6 % is explained by the outflow process, on average. Moreover, our analysis suggests that the connections are relatively strong (R=0.63), moderate (R=-0.46), and weak (R=-0.24) between retreat of sea ice and the winds associated with the dipole anomaly (DA), North Atlantic Oscillation (NAO), and Arctic Oscillation (AO), respectively. The DA participates by impacting both the advection (R=0.74) and melting (R=0.55) processes, whereas the NAO affects the melting process (R=-0.46).

scholarly journals The spatial and interannual dynamics of the surface water carbonate system and air–sea CO<sub>2</sub> fluxes in the outer shelf and slope of the Eurasian Arctic Ocean

Ocean Science ◽  
2017 ◽  
Vol 13 (6) ◽  
pp. 997-1016 ◽  
Author(s):  
Irina I. Pipko ◽  
Svetlana P. Pugach ◽  
Igor P. Semiletov ◽  
Leif G. Anderson ◽  
Natalia E. Shakhova ◽  
...  
Keyword(s):  
Time Series ◽  
Surface Water ◽  
High Resolution ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Outer Shelf ◽  
The Arctic ◽  
Arctic Seas ◽  
Carbonate System ◽  
The Arctic Ocean

Abstract. The Arctic is undergoing dramatic changes which cover the entire range of natural processes, from extreme increases in the temperatures of air, soil, and water, to changes in the cryosphere, the biodiversity of Arctic waters, and land vegetation. Small changes in the largest marine carbon pool, the dissolved inorganic carbon pool, can have a profound impact on the carbon dioxide (CO2) flux between the ocean and the atmosphere, and the feedback of this flux to climate. Knowledge of relevant processes in the Arctic seas improves the evaluation and projection of carbon cycle dynamics under current conditions of rapid climate change. Investigation of the CO2 system in the outer shelf and continental slope waters of the Eurasian Arctic seas (the Barents, Kara, Laptev, and East Siberian seas) during 2006, 2007, and 2009 revealed a general trend in the surface water partial pressure of CO2 (pCO2) distribution, which manifested as an increase in pCO2 values eastward. The existence of this trend was defined by different oceanographic and biogeochemical regimes in the western and eastern parts of the study area; the trend is likely increasing due to a combination of factors determined by contemporary change in the Arctic climate, each change in turn evoking a series of synergistic effects. A high-resolution in situ investigation of the carbonate system parameters of the four Arctic seas was carried out in the warm season of 2007; this year was characterized by the next-to-lowest historic sea-ice extent in the Arctic Ocean, on satellite record, to that date. The study showed the different responses of the seawater carbonate system to the environment changes in the western vs. the eastern Eurasian Arctic seas. The large, open, highly productive water area in the northern Barents Sea enhances atmospheric CO2 uptake. In contrast, the uptake of CO2 was strongly weakened in the outer shelf and slope waters of the East Siberian Arctic seas under the 2007 environmental conditions. The surface seawater appears in equilibrium or slightly supersaturated by CO2 relative to atmosphere because of the increasing influence of river runoff and its input of terrestrial organic matter that mineralizes, in combination with the high surface water temperature during sea-ice-free conditions. This investigation shows the importance of processes that vary on small scales, both in time and space, for estimating the air–sea exchange of CO2. It stresses the need for high-resolution coverage of ocean observations as well as time series. Furthermore, time series must include multi-year studies in the dynamic regions of the Arctic Ocean during these times of environmental change.

The impact of shallow stratification on air-sea CO2 flux in the summer Arctic Ocean

2021 ◽  
Author(s):  
Yuanxu Dong ◽  
Dorothee Bakker ◽  
Thomas Bell ◽  
Peter Liss ◽  
Ian Brown ◽  
...  
Keyword(s):  
Surface Water ◽  
Wind Speed ◽  
Sea Ice ◽  
Surface Temperature ◽  
Arctic Ocean ◽  
The Arctic ◽  
Near Surface ◽  
Ice Melt ◽  
The Arctic Ocean ◽  
The Impact

&lt;p&gt;Air-sea carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) flux is often indirectly estimated by the bulk method using the i&lt;em&gt;n-situ&lt;/em&gt; air-sea difference in CO&lt;sub&gt;2&lt;/sub&gt; fugacity and a wind speed dependent parameterisation of the gas transfer velocity (&lt;em&gt;K&lt;/em&gt;). In the summer, sea-ice melt in the Arctic Ocean generates strong shallow stratification with significant gradients in temperature, salinity, dissolved inorganic carbon (DIC) and alkalinity (TA), and thus a near-surface CO&lt;sub&gt;2&lt;/sub&gt; fugacity &amp;#160;(&lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt;) gradient. This gradient can cause an error in bulk air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux estimates when the &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; is measured by the ship&amp;#8217;s underway system at ~5 m depth. Direct air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux measurement by eddy covariance (EC) is free from the impact of shallow stratification because the EC CO&lt;sub&gt;2&lt;/sub&gt; flux does not rely on a &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; measurement. In this study, we use summertime EC flux measurements from the Arctic Ocean to back-calculate the sea surface &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; and temperature and compare them with the underway measurements. We show that the EC air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux agrees well with the bulk flux in areas less likely to be influenced by ice melt (salinity &gt; 32). However, in regions with salinity less than 32, the underway &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; is higher than the EC estimate of surface &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; and thus the bulk estimate of ocean CO&lt;sub&gt;2&lt;/sub&gt; uptake is underestimated. The &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; difference can be partly explained by the surface to sub-surface temperature difference. The EC estimate of surface temperature is lower than the sub-surface water temperature and this difference is wind speed-dependent. Upper-ocean salinity gradients from CTD profiles suggest likely difference in DIC and TA concentrations between the surface and sub-surface water. These DIC and TA gradients likely explain much of the near-surface &lt;em&gt;f&lt;/em&gt;CO&lt;sub&gt;2w&lt;/sub&gt; gradient. Accelerating summertime loss of sea ice results in additional meltwater, which enhances near-surface stratification and increases the uncertainty of bulk air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux estimates in polar regions.&lt;/p&gt;

scholarly journals Preliminary Screening for Microplastic Concentrations in the Surface Water of the Ob and Tom Rivers in Siberia, Russia

2020 ◽  
Vol 13 (1) ◽  
pp. 80
Author(s):  
Yulia A. Frank ◽  
Egor D. Vorobiev ◽  
Danil S. Vorobiev ◽  
Andrey A. Trifonov ◽  
Dmitry V. Antsiferov ◽  
...  
Keyword(s):  
Surface Water ◽  
Arctic Ocean ◽  
River System ◽  
The Arctic ◽  
Preliminary Screening ◽  
Freshwater Systems ◽  
Ob River ◽  
The Arctic Ocean ◽  
Abundance And Diversity ◽  
Blank Spot

To date, the largest Russian rivers discharging to the Arctic Ocean remain a “blank spot” on the world map of data on the distribution of microplastics in freshwater systems. This study characterizes the abundance and morphology of microplastics in surface water of the Ob River and its large tributary, the Tom River, in western Siberia. The average number of particles for the two rivers ranged from 44.2 to 51.2 items per m3 or from 79.4 to 87.5 μg per m3 in the Tom River and in the Ob River, respectively. Of the recovered microplastics, 93.5% were less than 1 mm in their largest dimension, the largest group (45.5% of total counts) consisted of particles with sizes range 0.30–1.00 mm. Generally, microfragments of irregular shape were the most abundant among the Ob and Tom samples (47.4%) and exceeded microfibers (22.1%), microfilms (20.8%), and microspheres (9.74%) by average counts. Results from this study provide a baseline for understanding the scale of the transport of microplastics by the Ob River system into the Arctic Ocean and add to currently available data on microplastics abundance and diversity in freshwater systems of differing global geographic locations.

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