Sea surface CO2 fugacity in the southwestern South Atlantic Ocean: An evaluation based on satellite-derived images

Liutti, Ciro Cataneo; Kerr, Rodrigo; Monteiro, Thiago; Orselli, Iole B.M.; Ito, Rosane Gonçalves; Garcia, Carlos Alberto Eiras

doi:10.1016/j.marchem.2021.104020

Cited by 14 publications

(9 citation statements)

References 93 publications

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“…Conversely, the lowest SSS and p CO 2 were found in years (2009 and 2012–2014) marked by heavy flooding associated with the La Niña phase and warming of the tropical South Atlantic (Marengo & Espinoza, 2016; Tyaquiçã et al., 2017). Such climatic events add complexity to the dynamics of the carbon cycle in the western Tropical Atlantic Ocean (Kucharski et al., 2016) and require further investigation using observations, models (Louchard et al., 2021), reanalysis products and satellite imagery (e.g., Liutti et al., 2021; Valerio et al., 2021) to constrain their relative importance to regional biogeochemistry.…”

Section: Discussionmentioning

confidence: 99%

Contrasting Sea‐Air CO₂ Exchanges in the Western Tropical Atlantic Ocean

Monteiro

Batista

Henley

et al. 2022

Global Biogeochemical Cycles

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The western Tropical Atlantic Ocean is a biogeochemically complex region due to the structure of the surface current system and the large freshwater input from the Amazon River coupled with the dynamics of precipitation. Such features make it difficult to understand the dynamics of the carbon cycle, leading to contrasting estimates in sea‐air CO2 exchanges in this region. Here, we demonstrate that these contrasting estimates occur because the western Tropical Atlantic Ocean can be split into three distinct sub‐regions in terms of the sea‐air CO2 exchanges. The sub‐region under the North Brazil Current domain acts as a weak annual CO2 source to the atmosphere, with low interannual variability. The sub‐region under the North Equatorial Current influence acts as an annual CO2 sink, with great temporal variability. The third sub‐region under the Amazon River plume influence shows greater interannual variability of CO2 exchanges, but it always acts as a net oceanic sink for CO2. Despite this large spatial variability, the entire region acts as a net annual CO2 sink of −1.6 ± 1.0 mmol m−2 day−1. Importantly, the Amazon River plume waters drive 87% of the CO2 uptake in the western Tropical Atlantic Ocean. In addition, we found a significant increasing trend in sea surface CO2 partial pressure in the North Brazil Current and North Equatorial Current waters. Such trends are more pronounced than the increase in atmospheric CO2 partial pressure, revealing the sensitivity of carbon dynamics in these sub‐regions to global climate change.

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Section: Discussionmentioning

confidence: 99%

Contrasting Sea‐Air CO₂ Exchanges in the Western Tropical Atlantic Ocean

Monteiro

Batista

Henley

et al. 2022

Global Biogeochemical Cycles

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“…The southern coast of South America is strongly influenced by riverine water input that reduces the total alkalinity and therefore causes an increase in pCO 2 (sw) (Liutti et al, 2021). This is associated with an increased supply of nutrients which in turn enhances NPP, though the main drivers of pCO 2 (sw) in this region are still total alkalinity and SST (Liutti et al, 2021). This potentially explains the positive correlation between pCO 2 and both NCP and NPP (Fig.…”

Section: Trends In Inter-annual Pco 2 and Co 2 Fluxmentioning

confidence: 99%

“…Aguiar et al ( 2018) also showed intense seasonal upwelling events in this region that are driven by wind and currents. The southern coast of South America is strongly influenced by riverine water input that reduces the total alkalinity and therefore causes an increase in pCO 2 (sw) (Liutti et al, 2021). This is associated with an increased supply of nutrients which in turn enhances NPP, though the main drivers of pCO 2 (sw) in this region are still total alkalinity and SST (Liutti et al, 2021).…”

Section: Trends In Inter-annual Pco 2 and Co 2 Fluxmentioning

confidence: 99%

Identifying the biological control of the annual and multi-year variations in South Atlantic air–sea CO₂ flux

et al. 2022

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Abstract. The accumulation of anthropogenic CO2 emissions in the atmosphere has been buffered by the absorption of CO2 by the global ocean, which acts as a net CO2 sink. The CO2 flux between the atmosphere and the ocean, which collectively results in the oceanic carbon sink, is spatially and temporally variable, and fully understanding the driving mechanisms behind this flux is key to assessing how the sink may change in the future. In this study a time series decomposition analysis was applied to satellite observations to determine the drivers that control the sea–air difference of CO2 partial pressure (ΔpCO2) and the CO2 flux on seasonal and inter-annual timescales in the South Atlantic Ocean. Linear trends in ΔpCO2 and the CO2 flux were calculated to identify key areas of change. Seasonally, changes in both the ΔpCO2 and CO2 flux were dominated by sea surface temperature (SST) in the subtropics (north of 40∘ S) and were correlated with biological processes in the subpolar regions (south of 40∘ S). In the equatorial Atlantic, analysis of the data indicated that biological processes are likely a key driver as a response to upwelling and riverine inputs. These results highlighted that seasonally ΔpCO2 can act as an indicator to identify drivers of the CO2 flux. Inter-annually, the SST and biological contributions to the CO2 flux in the subtropics were correlated with the multivariate El Niño–Southern Oscillation (ENSO) index (MEI), which leads to a weaker (stronger) CO2 sink in El Niño (La Niña) years. The 16-year time series identified significant trends in ΔpCO2 and CO2 flux; however, these trends were not always consistent in spatial extent. Therefore, predicting the oceanic response to climate change requires the examination of CO2 flux rather than ΔpCO2. Positive CO2 flux trends (weakening sink for atmospheric CO2) were identified within the Benguela upwelling system, consistent with increased upwelling and wind speeds. Negative trends in the CO2 flux (intensifying sink for atmospheric CO2) offshore into the South Atlantic gyre were consistent with an increase in the export of nutrients from mesoscale features, which drives the biological drawdown of CO2. These multi-year trends in the CO2 flux indicate that the biological contribution to changes in the air–sea CO2 flux cannot be overlooked when scaling up to estimates of the global ocean carbon sink.

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“…Ocean (Kucharski et al, 2016) and require further investigation using observations, models (Louchard et al, 2021), reanalysis products and satellite imagery (e.g., Valerio et al, 2021;Liutti et al, 2021) to constrain their relative importance to regional biogeochemistry.…”

Section: Accepted Articlementioning

confidence: 99%

Contrasting sea-air CO2 exchanges in the western Tropical Atlantic Ocean

Monteiro¹,

Batista²,

Machado³

et al. 2022

Preprint

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The western Tropical Atlantic Ocean is a biogeochemically complex region due to the structure of the surface current system and the large freshwater input from the Amazon River coupled with the dynamics of precipitation. Such features make it difficult to understand the dynamics of the carbon cycle, leading to contrasting estimates in sea-air CO2 exchanges in this region. Here we demonstrate that these contrasting estimates occur because the western Tropical Atlantic Ocean can be split in three distinct regions regarding the sea-air CO2 exchanges. The region under the North Brazil Current domain, acting as a weak annual CO2 source to the atmosphere, with low interannual variability. The region under the North Equatorial Current influence, acting as an annual CO2 sink zone, with great temporal variability. The third region is under the Amazon River plume influence, and has greater interannual variability of CO2 exchanges, but it always acts as an ocean CO2 net sink. Despite this large spatial variability, the entire region acts as a net annual CO2 sink of &#8211;1.6 &#177; 1.0 mmol m&#8211;2 day&#8211;1. Importantly, the Amazon River plume waters drive 87% of the CO2 uptake in the western Tropical Atlantic Ocean. In addition, we found a significant increase trend in sea surface CO2 partial pressure in North Brazil Current and North Equatorial Current waters. Such trends are greater than the increase in atmospheric CO2 partial pressure, revealing the sensitivity of carbon dynamics in these regions against a global climate change scenario. Since several studies have put efforts to elucidate the snapshots sea-air CO2 exchanges, we have expanded our knowledge about their spatial and temporal dynamics. Our findings shed a comprehensive light on the risk of extrapolation in estimating sea-air CO2 exchanges from regional snapshots. Hence, in addition to pointing out questions that still need to be answered on the CO2-carbonate system our study may be useful for the sampling design of future studies in this region. This should significantly improve the performance of complex coupled ocean-biogeochemical models to provide more robust information about the natural behaviour and changes that the western Tropical Atlantic Ocean is experiencing.

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Sea surface CO2 fugacity in the southwestern South Atlantic Ocean: An evaluation based on satellite-derived images

Cited by 14 publications

References 93 publications

Contrasting Sea‐Air CO₂ Exchanges in the Western Tropical Atlantic Ocean

Contrasting Sea‐Air CO₂ Exchanges in the Western Tropical Atlantic Ocean

Identifying the biological control of the annual and multi-year variations in South Atlantic air–sea CO₂ flux

Contrasting sea-air CO2 exchanges in the western Tropical Atlantic Ocean

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Sea surface CO2 fugacity in the southwestern South Atlantic Ocean: An evaluation based on satellite-derived images

Cited by 14 publications

References 93 publications

Contrasting Sea‐Air CO2 Exchanges in the Western Tropical Atlantic Ocean

Contrasting Sea‐Air CO2 Exchanges in the Western Tropical Atlantic Ocean

Identifying the biological control of the annual and multi-year variations in South Atlantic air–sea CO2 flux

Contrasting sea-air CO2 exchanges in the western Tropical Atlantic Ocean

Contact Info

Product

Resources

About

Contrasting Sea‐Air CO₂ Exchanges in the Western Tropical Atlantic Ocean

Contrasting Sea‐Air CO₂ Exchanges in the Western Tropical Atlantic Ocean

Identifying the biological control of the annual and multi-year variations in South Atlantic air–sea CO₂ flux