Winter measurements of oceanic biogeochemical parameters in the Rockall Trough (2009–2012)

McGrath, Triona; Kivimäe, Caroline; McGovern, Evin; Cave, Rachel; Joyce, E.

doi:10.5194/essd-5-375-2013

Cited by 8 publications

(5 citation statements)

References 18 publications

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“…Here we show the salinities from the CTD sensor (after calibration toward bottle salinity samples on the same cruise) and there is a clear temporal trend in the offsets. Trends in salinity have been observed in this area (McGrath et al 2013) and although the overall trend is toward increasing salinity, that trend has slowed down, or even reversed, during the last decade. During the GLODApv2 work this trend in the offsets was therefore recognized as real, but even accounting for that the cruise was too low and therefore adjusted up.…”

Section: Pressure Range (Db)mentioning

confidence: 91%

A toolbox for secondary quality control on ocean chemistry and hydrographic data

Lauvset

Tanhua

2015

Limnol. Oceanogr. Methods

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High quality, reference measurements of chemical and physical properties of seawater are of great importance for a wide research community, including the need to validate models and attempts to quantify spatial and temporal variability. Whereas data precision has been improved by technological advances, the data accuracy has improved mainly by the use of certified reference materials (CRMs). However, since CRMs are not available for all variables, and use of CRMs does not guarantee bias-free data, we here present a recently developed Matlab toolbox for performing so-called secondary quality control on oceanographic data by the use of crossover analysis. This method and how it has been implemented in this toolbox is described in detail. This toolbox is developed mainly for use by sea-going scientists as a tool for quickly assessing possible bias in the measurements that can-hopefully-be remedied during the expedition, but also for possible post-cruise adjustment of data to be consistent with previous measurements in the region. The toolbox, and reference data, can be downloaded from the Carbon Dioxide Information Analysis Center (CDIAC): http:// cdiac.ornl.gov/ftp/oceans/2nd_QC_Tool_V2/.Chemical and physical hydrographic measurements in the ocean have a long history during which the quality of the measurements have, in general, increased with time. With the quality of a measurement we mean both the precision and the accuracy; the latter being of great importance for inter-comparability of measurements conducted by different research teams, and for the quantification of temporal and spatial variability or trends. The accuracy of measurements can be increased by the use of certified reference materials (CRMs) as is common practice for carbonate system measurements and salinity. For instance, the introduction of CRMs for dissolved inorganic carbon (DIC) and total alkalinity during the WOCE period practically eliminated cruise-to-cruise biases in these parameters (e.g., Johnson et al. 1998). However, CRMs are not available for all variables or used on each cruise and measurements performed without the aid of CRMs are more prone to show biases, although the use of CRMs is no guarantee for accurate measurements as several factors can lead to biases, such as incorrectly quantified standard concentrations, the CRM concentration range being different from the samples, or other analytical difficulties. Overall, improvements in the instrumentation has reduced the achievable precision to about 2 lmol kg 21 for DIC and, with the use of CRMs, an accuracy better than 5 lmol kg 21 can be routinely obtained. We strongly recommend using CRMs whenever possible for your measurements, to increase the accuracy of oceanographic data, and for facilitating detection and quantification of trends. One way of verifying the accuracy of measurements conducted during an oceanographic cruise is by so-called secondary quality control (2 nd QC). It is important to note that 2 nd

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Section: Pressure Range (Db)mentioning

confidence: 91%

A toolbox for secondary quality control on ocean chemistry and hydrographic data

Lauvset

Tanhua

2015

Limnol. Oceanogr. Methods

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“…Dates of surveys and number of surface samples are shown in Table 1 and station positions in Fig. 1 (see McGrath et al (2013) for a detailed description of sampling, analysis and quality control procedures for all chemical parameters). On all surveys, a Seabird SBE 911 conductivitytemperature-depth (CTD) rosette system was employed.…”

Section: Methodsmentioning

confidence: 99%

The Inorganic Carbon Chemistry in Coastal and Shelf Waters Around Ireland

McGrath

McGovern

Cave

et al. 2015

Estuaries and Coasts

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The wintertime spatial distribution of carbonate parameters in outer estuarine and coastal waters around Ireland is described from total alkalinity (TA) and dissolved inorganic carbon (DIC) data collected between 2010 and 2013. Due to predominantly limestone bedrock of their river catchments, the River Shannon and Barrow, Nore and Suir River system export high concentrations (>3800 μmol kg −1 ) of TA to their estuarine and inshore coastal waters where estuarine alkalinity decreases with increasing salinity. TA is lower in rivers with a non-calcareous bedrock, with positively correlated alkalinitysalinity relationships in both the Lee and Foyle outer estuaries. Winter pCO 2 in the Shannon, Barrow/Nore/Suir and Lee estuaries is supersaturated relative to atmospheric CO 2 , while pCO 2 in the outer Liffey estuary is slightly lower than atmospheric CO 2 in three consecutive winters, indicative of a CO 2 sink. Winter pCO 2 is close to atmospheric equilibrium along the western shelf and through the centre of the Irish Sea, while it is a CO 2 sink across the North Channel. While aragonite was supersaturated in most Irish waters, it was close to undersaturation in both the Lee estuary, attributed to its low alkalinity freshwater source, and Barrow/Nore/Suir estuary related to the flux of high concentrations of DIC from this river system. The seasonal impacts on inorganic carbon chemistry was also investigated by comparing winter and summer data collected between 2009 and 2013 along two transects in western coastal waters and along the western shelf edge. DIC was~60 μmol kg −1 lower in summer relative to winter in the coastal transects and 39 μmol kg −1 lower along the shelf edge, accompanied by depleted nutrients and supersaturation of dissolved oxygen during summer, indicative of primary production. TA was generally higher in summer relative to winter corresponding with a decrease in nitrate, indicating that primary production dominated the TA distribution over calcification. An exception to this was at two stations along the shelf edge where TA was lower in summer relative to winter (51 μmol kg −1 ) and coincides with high reflectance in satellite images from a coccolithophore bloom at the time of sampling. While pCO 2 was close to atmospheric equilibrium along the shelf edge during winter, this area was a CO 2 sink during summer, apart from the stations where calcification was likely occurring resulting in elevated CO 2 relative to atmospheric concentrations.

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“…Several investigations have evaluated the drivers, trends and impacts of OA in the western NASPG at the Irminger and Iceland basins (e. g. Fontela et al, 2020;García-Ibáñez et al, 2021, 2016Perez et al, 2018;Pérez et al, 2021;Ríos et al, 2015), while few studies have addressed it along the Rockall Trough (e. g. McGrath et al, 2013, 2012a, 2012b, Humphreys et al, 2016 due to lack of repeated hydrographic sections or time-series stations and subsequent limitation of continuous surface-to-bottom data. The high longitudinal variability in the NASPG caused by the influence of different circulation patterns and water masses (García-Ibáñez et al, 2018 introduced several physicochemical heterogeneities between the Irminger and Iceland with the Rockall basin (Ellett et al, 1986;McGrath et al, 2013McGrath et al, , 2012bHolliday et al, 2000). These differences in the distributions of Marine Carbonate System (MCS) variables should be considered to improve our understanding of OA in the entire North Atlantic.…”

Section: Introductionmentioning

confidence: 99%

Ocean Acidification trends and Carbonate System dynamics in the North Atlantic Subpolar Gyre during 2009–2019

Curbelo-Hernández,

Pérez,

González-Dávila

et al. 2024

Preprint

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Abstract. The CO2-carbonate system dynamics in the North Atlantic Subpolar Gyre (NASPG) were evaluated between 2009 and 2019. Data was collected aboard eight summer cruises through the CLIVAR 59.5º N section. The Ocean Acidification (OA) patterns and the reduction in the saturation state of calcite (ΩCa) and aragonite (ΩArag) in response to the increasing anthropogenic CO2 (Cant) were assessed within the Irminger, Iceland and Rockall basins during a poorly-assessed decade in which the physical patterns reversed in comparison with previous well-known periods. The observed cooling, freshening and enhanced ventilation increased the interannual rate of accumulation of Cant in the interior ocean by 50–86 % and the OA rates by close to 10 %. The OA trends were 0.0013–0.0032 units yr-1 in the Irminger and Iceland basin and 0.0006–0.0024 units yr-1 in the Rockall Trough, causing a decline in ΩCa and ΩArag of 0.004–0.021 and 0.003–0.0013 units yr-1, respectively. The Cant-driven rise in total inorganic carbon (CT) was the main driver of the OA (contributed by 53–68 % in upper layers and >82 % toward the interior ocean) and the reduction in ΩCa and ΩArag (>64 %). The transient decrease in temperature, salinity and AT collectively counteracts the CT-driven acidification by 45–85 % in the upper layers and in the shallow Rockall Trough and by <10 % in the interior ocean. The present investigation reports the acceleration of the OA within the NASPG and expands knowledge about the future state of the ocean.

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Winter measurements of oceanic biogeochemical parameters in the Rockall Trough (2009–2012)

Cited by 8 publications

References 18 publications

A toolbox for secondary quality control on ocean chemistry and hydrographic data

A toolbox for secondary quality control on ocean chemistry and hydrographic data

The Inorganic Carbon Chemistry in Coastal and Shelf Waters Around Ireland

Ocean Acidification trends and Carbonate System dynamics in the North Atlantic Subpolar Gyre during 2009–2019

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