Tracking the variable North Atlantic sink for atmospheric CO2

3 páginas, 1 tabla, 3 figuras.-- Watson, Andrew J. ... et al.The oceans are a major sink for atmospheric carbon dioxide (CO2). Historically, observations have been too sparse to allow accurate tracking of changes in rates of CO2 uptake over ocean basins, so little is known about how these vary. Here, we show observations indicating substantial variability in the CO2 uptake by the North Atlantic on time scales of a few years. Further, we use measurements from a coordinated network of instrumented commercial ships to define the annual flux into the North Atlantic, for the year 2005, to a precision of about 10%. This approach offers the prospect of accurately monitoring the changing ocean CO2 sink for those ocean basins that are well covered by shipping routes.Peer reviewe

Net sea-air CO2 flux uncertainties in the Bay of Biscay based on the choice of wind speed products and gas transfer parameterizations

25 páginas, 4 figuras, 1 tablaThe estimation of sea-air CO2 fluxes are largely dependent on wind speed through the gas transfer velocity parameterization. In this paper, we quantify uncertainties in the estimation of the CO2 uptake in the Bay of Biscay resulting from using different sources of wind speed such as three different global reanalysis meteorological models (NCEP/NCAR 1, NCEP/DOE 2 and ERA-Interim), one regional high-resolution forecast model (HIRLAM-AEMet) and QuikSCAT winds, in combination with some of the most widely used gas transfer velocity parameterizations. Results show that net CO2 flux estimations during an entire seasonal cycle may differ up to 240% depending on the wind speed product and the gas exchange parameterization. The comparison of satellite and model derived winds with observations at buoys advises against the systematic overestimation of NCEP-2 and the underestimation of NCEP-1. In this region, QuikSCAT has the best performing, although ERA-Interim becomes the best choice in areas near the coastline or when the time resolution is the constraint.This work was developed and funded by the ECO project (MCyT REN2002-00503/MAR) and EU FP7 project CARBOCHANGE “Changes 5 in carbon uptake and emissions by oceans in a changing climate” under agreement no. 264879Peer reviewe

Reconstruction of the seasonal cycle of air–sea CO2 fluxes in the Strait of Gibraltar

The present study reports and discusses water surface fCO2 measurements from 36 cruises in the Strait of Gibraltar made over an eleven-year period (1997 to 2009). Underway measurements of sea surface CO2 fugacity (fCO2sw), sea surface temperature (SST) and sea surface salinity (SSS) compiled during the cruises were analysed and integrated into a single database which provided the resolution/sensitivity required for an examination of the seasonal variability of the fCO2sw; these data allowed the reconstruction of the climatological seasonal cycle for the year 2005. The seasonal cycle of both SST and SSS was found to be within the range of the thermohaline signature of the North Atlantic Surface Water, which is the main water mass that flows into the Mediterranean Sea through the Strait of Gibraltar at the surface. The seasonal distribution of fCO22005 was characterised by a monthly minimum value of 334 ± 12 μatm in May, followed by a gradual increase to a maximum of 385 μatm during late summer, due to the warming of surface waters. The spatial variability of fCO2sw observed in the area also indicated that superimposed phenomena, occurring at scales other than seasonal, could affect the dissolved CO2 distribution. In particular, intense vertical mixing processes generated by internal waves in this region may have an impact on the surface fCO2sw on a tidal scale. Seasonal CO2 cycle dynamics indicated that the surface waters of the Strait of Gibraltar acted as an atmospheric CO2 source during summer and autumn and a CO2 sink during winter and spring. When these sink/source strengths are integrated on an annual basis, the Strait of Gibraltar was close to equilibrium with atmospheric CO2, resulting in a neutral atmosphere-ocean exchange (− 0.06 ± 0.12 mol C m− 2 yr− 1).Funding for this work was provided by the CARBOOCEAN IP of the European Commission (511176GOCE) and by the Spanish Ministry of Education and Sciences through the Projects CAIBEX (CTM2007-66408) and (CTM2006-26206-E/MAR). Author Mercedes de la Paz acknowledges the financial support of the CSIC postdoctoral program JAE-Doc.Peer reviewe

North Atlantic CO2 sink variability revealed by the Go-Ship A25-OVIDE section

EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022.-- This work is distributed under the Creative Commons Attribution 4.0 LicenseAbout 30% of the carbon dioxide derived from human activities (CANTH) has been absorbed by the ocean (DeVries, 2014; Gruber et al., 2019; Friedlingstein et al., 2021), with the North Atlantic (NA) being one of the largest CANTH sinks per unit area (Khatiwala et al., 2013; Sabine et al., 2004). In the NA, oceanic CANTH uptake strongly relies on the meridional overturning circulation and the associated regional winter deep convection. In fact, the formation and deep spreading of Labrador Sea Water stands as a critical CANTH gateway to intermediate and abyssal depths. The NA CANTH uptake has fluctuated over the years according to changes in the North Atlantic Oscillation. Biennial observation of the marine carbonate system along the Go-Ship A25-OVIDE section has allowed us assessing the decadal and interannual variability of the CANTH storage in the subpolarNA from 2002 to 2021. In this study, we investigate 1) the trend of CANTH and 2) the relationship between the CANTH saturation, the apparent oxygen utilization, and the ventilation of the water masses between the A25-OVIDE section and the Greenland-Iceland-Scotland sills during 2002-2021. We divided the A25-OVIDE section into three main basins (Irminger, Iceland, and Eastern NA). Our results show that the Irminger Basin presents a more homogenous CANTH profile and higher CANTH saturation values at depth than the other two basins, which is related to the pronounced convective activity in the Irminger Basin. In contrast, the Eastern NA Basin has higher CANTH values at the surface due to its higher surface temperature, but its deep water masses show the lowest CANTH values since they are the less ventilated in the section. Our analysis also reveals that, overall, the NA CANTH storage has increased during 2002-2021, but varied according to the ventilation changes. While the Eastern NA water masses experienced a relatively constant, although shallower, average ventilation, the Irminger and Iceland Basins underwent a less steady CANTH uptake pattern characterized by alternating periods of strong and weak CANTH storageN

FICARAM-15 Cruise Report 20th March – 22nd May 2013 on board BIO Hespérides by the Group FICARAM

54 páginas, 19 figuras, 3 anexosThe FICARAM-15 is the fifteenth repetition of a section conducted in 1994. This section is part of the international program GOSHIP (http://www.go-ship.org/CruisePlans.html) to develop a globally coordinated network of sustained hydrographic sections as part of the global ocean/climate observing system. The objective of the FICARAM-15 cruise is to investigate the temporal evolution of the anthropogenic carbon and evaluate the CO2 absorption capacity of the South Atlantic region, the Equatorial zone, and the subtropical region of Azores-Gibraltar in the North Atlantic. This cruise is supported by the CATARINA project funded by the Ministry of Economy and Competitiveness (CTM2010-17141) and is part of the European Union FP7 project CARBOCHANGE (http://carbochange.b.uib.no/). The objective of FICARAM-15 cruise is framed in the CATARINA project conducted by the tasks I.2.1 (air-sea CO2 exchange) I.3 (ventilation of water masses), I.4.1 (zonal variability of N2O and CH4), I.4.2 (anthropogenic carbon storage), I.4.4 (saturation horizon of calcium carbonate along the section) and I.5.4 (evolution of the acidification rates). Another component of the FICARAM-15 cruise aims to examine the biological and biogeochemical mechanisms that hinder total dissolved organic carbon (DOC) remineralisation in marine systems, taking a multidisciplinary perspective and applying many different approaches. This is the global objective of the Spanish project DOREMI (CTM2012-34294) that joins this FICARAM-15 cruise.During the FICARAM cruise the physical oceanography group was responsible for collecting the following data sets: CTD and XBT data; vessel-mounted ADCP and lowered ADCP; continuous thermosalinograph. Physical oceanographers participated in the cruise financed through Project “Tipping Corners in the Meridional Overturning Circulation” (TIC-MOC), CTM2011-28867. The FICARAM-15 cruise was organized in two phases with a common sampling. LEG 1: From Punta Arenas (Chile) to Recife (Brazil): 62 stations. Chief Scientist: Aida F. Ríos, PI of CATARINA project LEG 2: From Recife (Brazil) to Cartagena (Spain): 46 stations Chief Scientist: Celia Marrasé, PI of DOREMI project This report contains the sampling of all the variables at each station along the FICARAM section, as well as the analysis of the biogeochemical variables and the preliminary results. The principal investigator of the DOREMI project produced another report with the common sampling section, showing the analysis and results of the experiments on dissolved organic matter carried out on board.This cruise is supported by the CATARINA project funded by the Ministry of Economy and Competitiveness (CTM2010-17141) and is part of the European Union FP7 project CARBOCHANGE (http://carbochange.b.uib.no/)Peer reviewe

Accurate monitoring of the North Atlantic air-sea CO2 flux from a network of voluntary observing ships

Ocean Sciences Meeting, March 2-7, 2008, Orlando, FloridaSince the start of 2005 under the EU’s Carbo-Ocean project, we have participated in co-ordinated observations of sea surface pCO2 and related variables from a network of commercial vessels in the North Atlantic. Typically five vessels are operating at any one time. The observations can be used to reconstruct the sea-surface pCO2 field, and thence estimate air-sea fluxes, with unprecedented resolution and accuracy. Using the observations for the calendar year 2005, we use a variety of geostatistical methods to derive the precision with which regional fluxes can be obtained. The observations are generalized to the entire N Atlantic from 10N to 65N by exploiting relations between surface pCO2, SST and mixed layer depth. Using semi-variograms or an empirical technique of selective data deletion applied to the residuals, we obtain a 1-sigma uncertainty of 6% on the annual flux into the region as a whole. This is very much more precise than has been possible for any comparable region of the world (land or ocean) up to nowN

Impactos ecológico y socioeconómico del cambio en el afloramiento ibérico

II Seminário Ibérico IGBP - Mudança global, Lisboa, 4-5 Novembro 2010Las regiones costeras de afloramiento están entre las más productivas de los océanos. La componente meridional del viento que genera la entrada de aguas ricas en nutrientes en la capa fótica y su variabilidad determina esta productividad. Distintos autores han sugerido que en un escenario de calentamiento global se producirá un fortalecimiento general. Este cambio tendría significativos impactos ecológicos, especialmente en las pesquerías. El análisis de larga escala del afloramiento costero en la Península Ibérica contrariamente muestra un debilitamientoN

Advancing real-time pH sensing capabilities to monitor coastal acidification as measured in a productive and dynamic estuary (Ría de Arousa, NW Spain)

18 pages, 9 figures.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)Ocean acidification has critical impacts on marine ecosystems, but presents knowledge gaps on the ecological impacts requiring large-scale monitoring of physicochemical conditions to predict biological responses to ocean pH projections. The threat is especially significant in coastal regions like upwelling areas which are more sensitive and appear to respond more rapidly to anthropogenic perturbations. These ecosystems, such as the northwest coast of the Iberian Peninsula are characterized by complex physical and biogeochemical interactions, supporting enormous biological productivity and productive fisheries. The distribution of pH in upwelling systems has high variability on short temporal and spatial scales preventing a complete picture of acidification, which exhibit long-term pH rates markedly different from the measured in open waters. This motivation to significantly expand the coverage of pH monitoring in coastal areas has driven us to develop an autonomous pH monitoring instrument (from now on SURCOM) based on the Honeywell Durafet® pH electrode. A relevant feature is that SURCOM transmits near real-time pH and temperature measurements every 10.5 min through SIGFOX®, a low-power, low-bandwidth network for data transmission. This very careful design allows us to achieve a very low power consumption for the complete system resulting in 3 years of full autonomy with no other need than external cleaning and calibration. In this paper we describe the setup and the data set obtained by a SURCOM instrument over 240 days in a highly productive and dynamic coastal ecosystem, the Rıá de Arousa embayment, providing valuable information on the performance of these low-cost and highly stable sensors, with potential for improving the pH variability description in nearshore systems and for reinforcing the monitoring-modeling of coastal acidificationFunding for AV was received from AtlAzul (0755_ATLAZUL_6_E) co-funded by the INTERREG V-A Spain-Portugal Cooperation Program (POCTEP) 2014-2020. Funding for XP comes from Observatorio TIAMAT project (2715-2021) funded by the Autonomous Agency of National Parks of the Ministry for Ecological Transition and Demographic Challenge. This work has also been supported from the MarRISK project (0262_MarRISK_1_E) co-funded by INTERREG V-A Spain-Portugal Cooperation Program (POCTEP) 2014-2020 and from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 820989 (COMFORT). This work was also contributed by WATER:iOS CSIC PTIPeer reviewe

Atmospheric CO2 measurements and error analysis on seasonal air-sea CO2 fluxes in the Bay of Biscay

12 páginas, 5 figuras, 1 tablaAtmospheric molar fraction of CO2 (xCO2atm) measurements obtained on board of ships of opportunity are used to parameterize the seasonal cycle of atmosphericxCO2 (xCO2atm) in three regions of the eastern North Atlantic (Galician and French offshore and Bay of Biscay). Three selection criteria are established to eliminate spurious values and identify xCO2atm data representative of atmospheric background values. The filtered data set is fitted to seasonal curve, consisting of an annual trend plus a seasonal cycle. Although the fitted curves are consistent with the seasonal evolution of xCO2atm data series from land meteorological stations, only ship-board measurements can report the presence of winter xCO2atm minimum on Bay of Biscay. Weekly air–sea CO2 flux differences (mmol C·m− 2 day− 1) produced by the several options of xCO2atm usually used (ship-board measurements, data from land meteorological stations and annually averaged values) were calculated in Bay of Biscay throughout 2003. Flux error using fitted seasonal curve relative to on board measurements was minimal, whereas land stations and annual means yielded random (− 0.2 ± 0.3 mmol C·m− 2·day− 1) and systematic (− 0.1 ± 0.4 mmol C·m− 2 day− 1), respectively. The effect of different available sources of sea level pressure, wind speed and transfer velocity were also evaluated. Wind speed and transfer velocity parameters are found as the most critical choice in the estimate of CO2 fluxes reaching a flux uncertainty of 7 mmol C·m− 2·day− 1 during springtime. The atmospheric pressure shows a notable relative effect during summertime although its influence is quantitatively slight on annual scale (0.3 ± 0.2 mmol C·m− 2·day− 1). All results confirms the role of the Bay of Biscay as CO2 sink for the 2003 with an annual mean CO2 flux around − 5 ± 5 mmol C m− 2 day− 1.This work was developed and funded within the ECO project (MCyT REN2002-00503/MAR) and the European Commission (EU FP6 CARBOOCEAN Integrated Project, Contract No. 511176-2). “Diputation de Pontevedra” financed X.A. Padin with a predoctoral grant.Peer reviewe

Anthropogenic carbon dioxide in the South Atlantic western basin

23 páginas, 4 figurasThe meridional WOCE line A17 was conducted during the austral summer of 1994 parallel to the eastern South American coast, from 55°S to 10°S, where one of the main limbs of the North Atlantic Deep Water (NADW), i.e., the southward-flowing Deep Western Boundary Current (DWBC) is found. Full-depth profiles of pH, total alkalinity and total inorganic carbon were measured and checked with analytical CO2 certified reference materials (CRMs), providing a high-quality dataset with good internal consistency for the CO2 system parameters that is well suited for anthropogenic CO2 (CANT) estimation. For the first time in the westernAtlantic basin the CANT has been calculated using four independent approaches and results are compared. The methods considered are the CFC-based TTD method and the φCT°, TrOCA and ∆C* carbon system-based back-calculation methods. All four methods have produced CANT distribution patterns that are in general good agreement: maximum concentrations of CANT (50–60 μmol kg− 1) are predicted for the upper warm SouthAtlantic central waters from the tropical gyres, while the minima (~ 5 μmol kg− 1) are located in the old northward-flowing branch of Circumpolar Deep Water. There are, however, some discrepancies detected. The TrOCA method yields the highest overall [CANT] values, even over the theoretical limit of CANT saturation for 1994 in the upper layers. The ∆C* approach consistently yielded negative estimates of CANT below 2800 dbar, even after correcting a reported − 8 μmol kg− 1 bias in the alkalinity measurements of the WOCE A17 line. The main overall difference between the four methods corresponds to the relative CANT maximum associated with the lower limb of NADW: this structure is well identified in the φCT° and TTD methods but seems to disappear in the case of TrOCA and ∆C*. In agreement with other intercomparison studies of CANT, the specific inventories are significantly higher (~ 45%) than those reported in the GLODAP database obtained from the ΔC* method. This suggests that the SouthAtlantic stores more CANT than initially expected, particularly towards the southernmost tip of the WOCE A17 line, close to the Southern Ocean. The φCT°, TrOCA and TTD methods confirm an increasing tendency of CANT specific inventories south from the Equator, while the ΔC* method shows a decreasing trend south from 35°SThis work was developed and funded by the European Commission within the 6th Framework Programme (EU FP6 CARBOOCAN Integrated Project, Contract no. 511176) and by the Xunta de Galicia within the INCITE framework (M4AO project PGIDIT07PXB402153PR). Marcos Vázquez- Rodríguez was funded by the Consejo Superior de Investigaciones Científicas (CSIC) I3P predoctoral grant program REF.: I3P-BPD2005.Peer reviewe