Inorganic carbon and pH levels in the Rockall Trough 1991–2010

McGrath, Triona; Kivimäe, Caroline; Tanhua, Toste; Cave, Rachel; McGovern, Evin

doi:10.1016/j.dsr.2012.05.011

Cited by 27 publications

(28 citation statements)

References 71 publications

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“…Within the 68 % confidence intervals, the NA-SPSS pH trend is consistent with both of these local trends. In the North Atlantic subtropical seasonally stratified (NA-STSS) biome, there are no time series data to compare with, but its trend of −0.0018 ± 0.0003 yr −1 is consistent with a trend of ∼ −0.0020 yr −1 observed in the Rockall Trough by McGrath et al (2012). In the North (NA-STPS) and South (SA-STPS) Atlantic subtropical permanently stratified biomes, the pH trend is the same, but the RMSE values indicate larger interannual variability in the southern biome (Table 1).…”

Section: Long-term Trends In Phmentioning

confidence: 67%

Trends and drivers in global surface ocean pH over the past 3 decades

et al. 2015

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Abstract.We report global long-term trends in surface ocean pH using a new pH data set computed by combining f CO 2 observations from the Surface Ocean CO 2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981-2011 and 1991-2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ∼ 70 % of all biomes and a mean rate of decrease of 0.0018 ± 0.0004 yr −1 for 1991-2011. We are not able to calculate a global trend for 1981-2011 because too few biomes have enough data for this. In half the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean CO 2 chemistry remaining in a transient equilibrium with the increase in atmospheric CO 2 . In the remaining biomes, deviations from such equilibrium may reflect that the trend of surface ocean f CO 2 is not equal to that of the atmosphere, most notably in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.

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Section: Long-term Trends In Phmentioning

confidence: 67%

Trends and drivers in global surface ocean pH over the past 3 decades

et al. 2015

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“…The storage rates of DIC and DICabio in the southern parts of regions A and B are significantly higher than for the northern parts, and conform better to published estimates of C ant in the region. For instance, a recent study by McGrath et al (2012) found storage rates of C ant in the Rockall Trough of 1.2 mol m −2 a −1 for the layer between 200 and 2000 m. The oxygen and AOU storage rates are close to neutral in the southern parts of regions A and B, i.e. similar to other areas further south in the Atlantic.…”

Section: Discussionmentioning

confidence: 88%

Changes in column inventories of carbon and oxygen in the Atlantic Ocean

Tanhua

2012

Biogeosciences

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Abstract. Increasing concentrations of dissolved inorganic carbon (DIC) in the interior ocean are expected as a direct consequence of increasing concentrations of CO 2 in the atmosphere. This extra DIC is often referred to as anthropogenic carbon (C ant ), and its inventory, or increase rate, in the interior ocean has previously been estimated by a multitude of observational approaches. Each of these methods is associated with hard to test assumptions since C ant cannot be directly observed. Results from a simpler concept with fewer assumptions applied to the Atlantic Ocean are reported on here using two large data collections of carbon relevant bottle data. The change in column inventory on decadal time scales, i.e. the storage rate, of DIC, respiration compensated DIC and oxygen is calculated for the Atlantic Ocean. We report storage rates and the confidence intervals of the mean trend at the 95 % level (CI), reflecting the mean trend but not considering potential biasing effects of the spatial and temporal sampling. For the whole Atlantic Ocean the mean trends for DIC and oxygen are non-zero at the 95 % confidence level: DIC: 0.86 (CI: 0.72-1.00) and oxygen: −0.24 (CI: −0.41-(−0.07)) mol m −2 yr −1 . For oxygen, the whole Atlantic trend is dominated by the subpolar North Atlantic, whereas for other regions the O 2 trends are not significant. The storage rates are similar to changes found by other studies, although with large uncertainty. For the subpolar North Atlantic the storage rates show significant temporal and regional variation of all variables. This seems to be due to variations in the prevalence of subsurface water masses with different DIC and oxygen concentrations leading to sometimes different signs of storage rates for DIC compared to published C ant estimates. This study suggest that accurate assessment of the uptake of CO 2 by the oceans will require accounting not only for processes that influence C ant but also additional processes that modify CO 2 storage.

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“…A very small portion of this may be related to the lower salinity observed, however such a large difference is unlikely to be true. This negative offset in the 2009 TA data had previously been observed through the water column (therefore not due to CaCO 3 formation) and so was not included in McGrath et al (2012a). Preliminary results suggest that this parameter will be adjusted in the second version of the GLODAP database, which is currently being developed.…”

Section: Secondary Quality Controlmentioning

confidence: 99%

“…It is unclear why the TA CRMs for Batch 102 used for CE10002 had a slightly larger offset than other batches. Vertical profiles of final TA concentrations from this survey were cross-checked with TA profiles from CE12001 and two WOCE (World Ocean Circulation Experiment) surveys in the same region (McGrath et al, 2012a). All suggest that there is no problem/offset in the TA results generated from this batch.…”

Section: Quality Controlmentioning

confidence: 99%

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

McGrath

Kivimäe

McGovern

et al. 2013

Earth Syst. Sci. Data

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Abstract. This paper describes the sampling and analysis of biogeochemical parameters collected in the Rockall Trough in January/February of 2009, 2010, 2011 and 2012. Sampling was carried out along two transects, one southern and one northern transect each year. Samples for dissolved inorganic carbon (DIC) and total alkalinity (TA) were taken alongside salinity, dissolved oxygen and dissolved inorganic nutrients (total-oxidized nitrogen, nitrite, phosphate and silicate) to describe the chemical signatures of the various water masses in the region. These were taken at regular intervals through the water column. The data are available on the CDIAC database, http://cdiac.ornl.gov/ftp/oceans/Rockall_Trough/. Data coverage and parameter measuredRepository-Reference:

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Inorganic carbon and pH levels in the Rockall Trough 1991–2010

Abstract: The accumulation of anthropogenic CO 2 in the oceans is altering seawater carbonate chemistry. Monitoring carbonate parameters is therefore necessary to understand potential impacts on ocean ecosystems. Total alkalinity (A T ) and dissolved inorganic

Cited by 27 publications

References 71 publications

Trends and drivers in global surface ocean pH over the past 3 decades

Trends and drivers in global surface ocean pH over the past 3 decades

Changes in column inventories of carbon and oxygen in the Atlantic Ocean

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

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