Wintertime fCO2 Variability in the Subpolar North Atlantic Since 2004

Fröb, Friederike; Olsen, Are; Becker, Meike; Chafik, Léon; Johannessen, Truls; Reverdin, Gilles; Omar, Abdirahman M

doi:10.1029/2018gl080554

Cited by 25 publications

(40 citation statements)

References 66 publications

(163 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These independent estimates confirm that in the NASPG the observed long-term DIC trend and derived trends for f CO 2 and pH in surface waters (Table 2, are mostly linked with anthropogenic CO 2 uptake. The same conclusion was drawn for the subpolar mode waters found in subsurface layers in the NASPG (Vázquez-Rodríguez et al, 2012;García-Ibáñez et al, 2016;Fröb et al, 2018). For example, based on data collected in 1981, Vázquez-Rodríguez et al (2012 estimated that 75 % of the observed pH decrease (−0.0019 yr −1 ) in the subarctic intermediate waters (SAIW) in the Irminger Basin is due to anthropogenic DIC.…”

Section: Long-term Trend and Anthropogenic Comentioning

confidence: 53%

“…For example, based on data collected in 1981, Vázquez-Rodríguez et al (2012 estimated that 75 % of the observed pH decrease (−0.0019 yr −1 ) in the subarctic intermediate waters (SAIW) in the Irminger Basin is due to anthropogenic DIC. García-Ibáñez et al (2016), incorporating four additional cruises (2010-2015), estimated a pH decrease of around −0.0018 yr −1 over 1991-2015 in the subpolar mode waters (SPMW) found at around 200-300 m in the Irminger Basin. They also conclude that in the SPMW the pH decrease is dominated by DIC increase (+0.82 µmol kg −1 yr −1 ) through anthropogenic CO 2 (C-ant trend of +0.9 µmol kg −1 yr −1 ) but this is modulated by a pH increase over time due to an increase in alkalinity (about +0.11 µmol kg −1 yr −1 ).…”

Section: Long-term Trend and Anthropogenic Comentioning

confidence: 99%

See 1 more Smart Citation

Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)

Leseurre¹,

Monaco²,

Reverdin³

et al. 2020

Biogeosciences

Self Cite

View full text Add to dashboard Cite

Abstract. The North Atlantic is one of the major ocean sinks for natural and anthropogenic atmospheric CO2. Given the variability of the circulation, convective processes or warming–cooling recognized in the high latitudes in this region, a better understanding of the CO2 sink temporal variability and associated acidification needs a close inspection of seasonal, interannual to multidecadal observations. In this study, we investigate the evolution of CO2 uptake and ocean acidification in the North Atlantic Subpolar Gyre (50–64∘ N) using repeated observations collected over the last 3 decades in the framework of the long-term monitoring program SURATLANT (SURveillance de l'ATLANTique). Over the full period (1993–2017) pH decreases (−0.0017 yr−1) and fugacity of CO2 (fCO2) increases (+1.70 µatm yr−1). The trend of fCO2 in surface water is slightly less than the atmospheric rate (+1.96 µatm yr−1). This is mainly due to dissolved inorganic carbon (DIC) increase associated with the anthropogenic signal. However, over shorter periods (4–10 years) and depending on the season, we detect significant variability investigated in more detail in this study. Data obtained between 1993 and 1997 suggest a rapid increase in fCO2 in summer (up to +14 µatm yr−1) that was driven by a significant warming and an increase in DIC for a short period. Similar fCO2 trends are observed between 2001 and 2007 during both summer and winter, but, without significant warming detected, these trends are mainly explained by an increase in DIC and a decrease in alkalinity. This also leads to a pH decrease but with contrasting trends depending on the region and season (between −0.006 and −0.013 yr−1). Conversely, data obtained during the last decade (2008–2017) in summer show a cooling of surface waters and an increase in alkalinity, leading to a strong decrease in surface fCO2 (between −4.4 and −2.3 µatm yr−1; i.e., the ocean CO2 sink increases). Surprisingly, during summer, pH increases up to +0.0052 yr−1 in the southern subpolar gyre. Overall, our results show that, in addition to the accumulation of anthropogenic CO2, the temporal changes in the uptake of CO2 and ocean acidification in the North Atlantic Subpolar Gyre present significant multiannual variability, not clearly directly associated with the North Atlantic Oscillation (NAO). With such variability it is uncertain to predict the near-future evolution of air–sea CO2 fluxes and pH in this region. Thus, it is highly recommended to maintain long-term observations to monitor these properties in the next decade.

show abstract

Section: Long-term Trend and Anthropogenic Comentioning

confidence: 53%

Section: Long-term Trend and Anthropogenic Comentioning

confidence: 99%

Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)

Leseurre¹,

Monaco²,

Reverdin³

et al. 2020

Biogeosciences

Self Cite

View full text Add to dashboard Cite

show abstract

“…The 2005 and 2008 cruise data have been released as part of the GLODAPv2 data synthesis . Similar water column carbonate measurements were also carried out in April 2015 on R/V GO Sars (Fröb et al, 2019). The 2015 cruise covered an east-west section perpendicular to the Norwegian west coast (59.3°N, 3-4°E; Figure 1, blue filled circles) and the data are available at https://cchdo.ucsd.edu/cruise/58GS20150410.…”

Section: Cruise Datamentioning

confidence: 81%

Trends of Ocean Acidification and pCO₂ in the Northern North Sea, 2003–2015

et al. 2019

Self Cite

View full text Add to dashboard Cite

For continental shelf regions, the long‐term trend in sea surface carbon dioxide (CO2) partial pressure (pCO2) and rates of ocean acidification are not accurately known. Here, we investigate the decadal trend of observed wintertime pCO2 as well as computed wintertime pH and aragonite saturation state (Ωar) in the northern North Sea, using the first decade long monthly underway data from a voluntary observing ship covering the period 2004–2015. We also evaluate how seawater CO2 chemistry, in response to physical and biological processes, drives variations in the above parameters on seasonal and interannual timescales. In the northern North Sea, pCO2, pH, and Ωar are subject to strong seasonal variations with mean wintertime values of 375 ± 11 μatm, 8.17 ± 0.01, and 1.96 ± 0.05. Dissolved inorganic carbon is found to be the primary driver of both seasonal and interannual changes while total alkalinity and sea surface temperature have secondary effects that reduce the changes produced by dissolved inorganic carbon. Average interannual variations during winter are around 3%, 0.1%, and 2% for pCO2, pH, and Ωar, respectively and slightly larger in the eastern part of the study area (Skagerrak region) than in the western part (North Atlantic Water region). Statistically significant long‐term trends were found only in the North Atlantic Water region with mean annual rates of 2.39 ± 0.58 μatm/year, −0.0024 ± 0.001 year‐1, and −0.010 ± 0.003 year‐1 for pCO2, pH, and Ωar, respectively. The drivers of the observed trends as well as reasons for the lack of statistically significant trends in the Skagerrak region are discussed.

show abstract

“…Estimates based on summer-only data typically show large interannual variations (Thomas et al, 2007;Salt et al, 2013), which led to the conclusion that here the interannual variability masks the actual long term trend. The approach to use winter-only data (Fröb et al, 2019;Omar et al, 2019), on the other hand, is based on the assumption that during this season the influence of biological processes is negligible and therefore winter data can be used to establish a baseline trend. However, also using winter-only data has its drawbacks.…”

mentioning

confidence: 99%

The northern European shelf as increasing net sink for CO2

Becker¹,

Olsen²,

Landschützer³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. We developed a simple method to refine existing open ocean maps towards different coastal seas. Using a multi linear regression we produced monthly maps of surface ocean fCO2 in the northern European coastal seas (North Sea, Baltic Sea, Norwegian Coast and in the Barents Sea) covering a time period from 1998 to 2016. A comparison with gridded SOCAT v5 data revealed standard deviations of the residuals 0&#8201;&#177;&#8201;26&#8201;&#956;atm in the North Sea, 0&#8201;&#177;&#8201;16&#8201;&#956;atm along the Norwegian Coast, 0&#8201;&#177;&#8201;19&#8201;&#956;atm in the Barents Sea, and 2&#8201;&#177;&#8201;42&#8201;&#956;atm in the Baltic Sea.We used these maps as basis to investigate trends in fCO2, pH and air-sea CO2 flux. The surface ocean fCO2 trends are smaller than the atmospheric trend in most of the studied region. Only the western part of the North Sea is showing an increase in fCO2 close to 2&#8201;&#956;atm&#8201;yr&#8722;1, which is similar to the atmospheric trend. The Baltic Sea does not show a significant trend. Here, the variability was much larger than possibly observable trends. Consistently, the pH trends were smaller than expected for an increase of fCO2 in pace with the rise of atmospheric CO2 levels. The calculated air-sea CO2 fluxes revealed that most regions were net sinks for CO2. Only the southern North Sea and the Baltic Sea emitted CO2 to the atmosphere. Especially in the northern regions the sink strength increased during the studied period.

show abstract

Wintertime fCO₂ Variability in the Subpolar North Atlantic Since 2004

Cited by 25 publications

References 66 publications

Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)

Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)

Trends of Ocean Acidification and pCO₂ in the Northern North Sea, 2003–2015

The northern European shelf as increasing net sink for CO<sub>2</sub>

Contact Info

Product

Resources

About

Wintertime fCO2 Variability in the Subpolar North Atlantic Since 2004

Cited by 25 publications

References 66 publications

Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)

Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993–2017)

Trends of Ocean Acidification and pCO2 in the Northern North Sea, 2003–2015

The northern European shelf as increasing net sink for CO&lt;sub&gt;2&lt;/sub&gt;

Contact Info

Product

Resources

About

Wintertime fCO₂ Variability in the Subpolar North Atlantic Since 2004

Trends of Ocean Acidification and pCO₂ in the Northern North Sea, 2003–2015

The northern European shelf as increasing net sink for CO<sub>2</sub>