Sea surfacepCO2and O2dynamics in the partially ice-covered Arctic Ocean

Islam, Fakhrul; DeGrandpre, Michael D.; Beatty, Cory M.; Timmermans, Mary‐Louise; Krishfield, Richard A.; Toole, John M.; Laney, Samuel R.

doi:10.1002/2016jc012162

Cited by 18 publications

(27 citation statements)

References 69 publications

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“…However, if one considers the volumetric rate, then NCP is larger in the summer than in the fall due to deeper mixed layers in the fall (Figure S1b and Table S2). The NCP rates calculated here from 2012 agree well the mean NCP (4.9 mmol O 2 ·m −2 ·d −1 ) calculated from diel cycles of dissolved oxygen and pCO 2 from ice tethered profilers records in a similar location and timeframe (Islam et al, ).…”

Section: Resultssupporting

confidence: 80%

“…Indeed in 2012, winds are significantly correlated with both GOP and NCP (Table S3). Additionally, observations from ice‐tethered profiles, in conjunction with the cruise data, show that near the end of the 2012 cruise (on 5 September), a storm was observed with increased wind speeds, the mixed layer deepened, and some nitrate was detectable within the mixed layer, which could in turn have led to increased production (Islam et al, ). Furthermore, also in 2012, a major gale in the Arctic occurred just before sampling on the cruise commenced (Parkinson & Comiso, ), and thus, the higher production we observe in 2012 could in part be related to nutrients upwelled during that storm.…”

Section: Discussionmentioning

confidence: 99%

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Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Sandwith

Williams

et al. 2019

JGR Oceans

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The Arctic Ocean is experiencing profound environmental changes as the climate warms. Understanding how these changes will affect Arctic biological productivity is key for predicting future Arctic ecosystems and the global CO2 balance. Here we use in situ gas measurements to quantify rates of gross oxygen production (GOP, total photosynthesis) and net community production (NCP, net CO2 drawdown by the biological pump) in the mixed layer in summer or fall from 2011 to 2016 in the Beaufort Gyre. NCP and GOP show spatial and temporal variations with higher values linked with lower concentrations of sea ice and increased upper ocean stratification. Mean rates of GOP range from 8 ± 1 to 54 ± 9 mmol O2·m−2·d−1 with the highest mean rates occurring in summer of 2012. Mean rates of NCP ranged from 1.3 ± 0.2 to 2.9 ± 0.5 mmol O2·m−2·d−1. The mean ratio of NCP/GOP, a measure of how efficiently the ecosystem is recycling its nutrients, ranged from 0.04 to 0.17, similar to ratios observed at lower latitudes. Additionally, a large increase in total photosynthesis that occurred in 2012, a year of historically low sea ice coverage, persisted for many years. Taken together, these data provide one of the most complete characterizations of interannual variations of biological productivity in this climatically important region, can serve as a baseline for future changes in rates of production, and give an intriguing glimpse of how this region of the Arctic may respond to future lack of sea ice.

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Section: Resultssupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Sandwith

Williams

et al. 2019

JGR Oceans

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“…ITPs are equipped with CTD instruments for observing the ocean’s thermohaline stratification and may also include sensors that sample, for example, dissolved oxygen (Timmermans et al, 2010), bio-optical properties (Laney et al, 2014), and ocean currents (Ice-Tethered Profiler with Velocity – ITV-V: Thwaites et al, 2011; Cole et al, 2015). In addition, instruments measuring temperature-conductivity, pCO 2 , dissolved O 2 and pH have been affixed to the tether above the profiling interval (e.g., Islam et al, 2017). Deployments may be done from ice camps (supported by fixed-wing aircraft or helicopters) or ships.…”

Section: In Situ Observations Of Temperature and Salinitymentioning

confidence: 99%

Polar Ocean Observations: A Critical Gap in the Observing System and Its Effect on Environmental Predictions From Hours to a Season

et al. 2019

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There is a growing need for operational oceanographic predictions in both the Arctic and Antarctic polar regions. In the former, this is driven by a declining ice cover accompanied by an increase in maritime traffic and exploitation of marine resources. Oceanographic predictions in the Antarctic are also important, both to support Antarctic operations and also to help elucidate processes governing sea ice and ice shelf stability. However, a significant gap exists in the ocean observing system in polar regions, compared to most areas of the global ocean, hindering the reliability of ocean and sea ice forecasts. This gap can also be seen from the spread in ocean and sea ice reanalyses for polar regions which provide an estimate of their uncertainty. The reduced reliability of polar predictions may affect the quality of various applications including search and rescue, coupling with numerical weather and seasonal predictions, historical reconstructions (reanalysis), aquaculture and environmental management including environmental emergency response. Here, we outline the status of existing near-real time ocean observational efforts in polar regions, discuss gaps, and explore perspectives for the future. Specific recommendations include a renewed call for open access to data, especially real-time data, as a critical capability for improved sea ice and weather forecasting and other environmental prediction needs. Dedicated efforts are also needed to make use of additional observations made as part of the Year of Polar Prediction (YOPP; 2017–2019) to inform optimal observing system design. To provide a polar extension to the Argo network, it is recommended that a network of ice-borne sea ice and upper-ocean observing buoys be deployed and supported operationally in ice-covered areas together with autonomous profiling floats and gliders (potentially with ice detection capability) in seasonally ice covered seas. Finally, additional efforts to better measure and parameterize surface exchanges in polar regions are much needed to improve coupled environmental prediction.

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“…To address this sampling gap, we have been deploying pCO 2 and pH sensors on year-round moorings and ice-tethered profilers (ITPs; Krishfield et al, 2008;Toole et al, 2011) in the Canada Basin since 2012 (Islam et al, 2016(Islam et al, , 2017. This study focuses on a pCO 2 time series recorded on a subsurface mooring at~30-m depth from October 2014 to September 2015 in the northwest Canada Basin (Figure 1).…”

Section: 1029/2019jc015109mentioning

confidence: 99%

Inorganic Carbon and pCO₂ Variability During Ice Formation in the Beaufort Gyre of the Canada Basin

et al. 2019

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Solute exclusion during sea ice formation is a potentially important contributor to the Arctic Ocean inorganic carbon cycle that could increase as ice cover diminishes. When ice forms, solutes are excluded from the ice matrix, creating a brine that includes dissolved inorganic carbon (DIC) and total alkalinity (AT). The brine sinks, potentially exporting DIC and AT to deeper water. This phenomenon has rarely been observed, however. In this manuscript, we examine a ~1 year pCO2 mooring time series where a ~35‐μatm increase in pCO2 was observed in the mixed layer during the ice formation period, corresponding to a simultaneous increase in salinity from 27.2 to 28.5. Using salinity and ice based mass balances, we show that most of the observed increases can be attributed to solute exclusion during ice formation. The resulting pCO2 is sensitive to the ratio of AT and DIC retained in the ice and the mixed layer depth, which controls dilution of the ice‐derived AT and DIC. In the Canada Basin, of the ~92 μmol/kg increase in DIC, 17 μmol/kg was taken up by biological production and the remainder was trapped between the halocline and the summer stratified surface layer. Although not observed before the mooring was recovered, this inorganic carbon was likely later entrained with surface water, increasing the pCO2 at the surface. It is probable that inorganic carbon exclusion during ice formation will have an increasingly important influence on DIC and pCO2 in the surface of the Arctic Ocean as seasonal ice production and wind‐driven mixing increase with diminishing ice cover.

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Sea surfacepCO₂and O₂dynamics in the partially ice-covered Arctic Ocean

Cited by 18 publications

References 69 publications

Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Polar Ocean Observations: A Critical Gap in the Observing System and Its Effect on Environmental Predictions From Hours to a Season

Inorganic Carbon and pCO₂ Variability During Ice Formation in the Beaufort Gyre of the Canada Basin

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Sea surfacepCO2and O2dynamics in the partially ice-covered Arctic Ocean

Cited by 18 publications

References 69 publications

Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Polar Ocean Observations: A Critical Gap in the Observing System and Its Effect on Environmental Predictions From Hours to a Season

Inorganic Carbon and pCO2 Variability During Ice Formation in the Beaufort Gyre of the Canada Basin

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Product

Resources

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Sea surfacepCO₂and O₂dynamics in the partially ice-covered Arctic Ocean

Inorganic Carbon and pCO₂ Variability During Ice Formation in the Beaufort Gyre of the Canada Basin