An assessment of the Atlantic and Arctic sea–air CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; fluxes, 1990–2009

Schuster, Ute; McKinley, Galen A.; Bates, Nicholas R.; Chevallier, F.; Doney, Scott C.; Fay, Amanda R.; González‐Dávila, Melchor; Gruber, Nicolas; Jones, S. D. M.; Krijnen, Justin; Landschützer, Peter; Lefèvre, Nathalie; Manizza, Manfredi; Mathis, Jeremy T.; Metzl, Nicolas; Olsen, Are; Rı́os, Aida F.; Rödenbeck, Christian; Santana‐Casiano, J. Magdalena; Takahashi, Taro; Wanninkhof, Rik; Watson, Andrew

doi:10.5194/bg-10-607-2013

Cited by 194 publications

(215 citation statements)

References 86 publications

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“…They therefore tend to show greater temporal and spatial variability than open oceans, and are more affected by human activities (Cameron and Pritchard, 1963;Alongi, 1998;Chen and Tsunogai, 1998;Rabouille et al, 2001;Chen, 2002Chen, , 2003Chen, , 2004Slomp and Van Cappellen, 2004;Beusen et al, 2005;Chavez et al, 2007;Doney et al, 2007;Radach and Patsch, 2007;Peng et al, 2008;Seitzinger et al, 2010;Dürr et al, 2011;Jiang et al, 2013). However, unlike the open oceans, in which millions of observations have been made and the air-sea exchanges of CO 2 have been valued using various developed models (such as by Khatiwala et al, 2013;Schuster et al, 2013;Wanninkhof et al, 2013), coastal waters have been relatively poorly examined.…”

Section: C-t a Chen Et Al: Air-sea Exchanges Of Co 2 In The Worldmentioning

confidence: 99%

Air–sea exchanges of CO2 in the world's coastal seas

et al. 2013

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Abstract. The air-sea exchanges of CO 2 in the world's 165 estuaries and 87 continental shelves are evaluated. Generally and in all seasons, upper estuaries with salinities of less than two are strong sources of CO 2 (39 ± 56 mol C m −2 yr −1 , positive flux indicates that the water is losing CO 2 to the atmosphere); mid-estuaries with salinities of between 2 and 25 are moderate sources (17.5 ± 34 mol C m −2 yr −1 ) and lower estuaries with salinities of more than 25 are weak sources . Mixing with low-pCO 2 shelf waters, water temperature, residence time and the complexity of the biogeochemistry are major factors that govern the pCO 2 in estuaries, but wind speed, seldom discussed, is critical to controlling the air-water exchanges of CO 2 . The total annual release of CO 2 from the world's estuaries is now estimated to be 0.10 Pg C yr −1 , which is much lower than published values mainly because of the contribution of a considerable amount of heretofore unpublished or new data from Asia and the Arctic. The Asian data, although indicating high pCO 2 , are low in sea-to-air fluxes because of low wind speeds. Previously determined flux values rely heavily on data from Europe and North America, where pCO 2 is lower but wind speeds are much higher, such that the CO 2 fluxes are higher than in Asia. Newly emerged CO 2 flux data in the Arctic reveal that estuaries there mostly absorb rather than release CO 2 .Most continental shelves, and especially those at high latitude, are undersaturated in terms of CO 2 and absorb CO 2 from the atmosphere in all seasons. Shelves between 0 and 23.5 • S are on average a weak source and have a small flux per unit area of CO 2 to the atmosphere. Water temperature, the spreading of river plumes, upwelling, and biological production seem to be the main factors in determining pCO 2 in the shelves. Wind speed, again, is critical because at high latitudes, the winds tend to be strong. Since the surface water pCO 2 values are low, the air-to-sea fluxes are high in regions above 50 • N and below 50 • S. At low latitudes, the winds tend to be weak, so the sea-to-air CO 2 flux is small. Overall, the world's continental shelves absorb 0.4 Pg C yr −1 from the atmosphere.

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Section: C-t a Chen Et Al: Air-sea Exchanges Of Co 2 In The Worldmentioning

confidence: 99%

Air–sea exchanges of CO2 in the world's coastal seas

et al. 2013

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“…These fluxes carry several errors associated with sparse coverage of data, wind speed measurements and gas transfer coefficients (see Sweeney et al, 2007, for more discussion). Following Gruber et al (2009) and Schuster et al (2013) we estimate the uncertainty on all sea-air flux observations to be ∼ 50 %. In our subsequent analysis and comparison with different models and inversions, we define CO 2 flux and pCO 2 observations as these climatologies.…”

Section: Observationsmentioning

confidence: 99%

“…Sea-air CO 2 fluxes for ocean models and inversions were calculated as a median and the variability as a median absolute deviation (MAD; Gauss, 1816), consistent with Schuster et al (2013) and Lenton et al (2013). The MAD is the value where one half of all values are closer to the median than the MAD, and is a useful statistic for excluding outliers in data sets.…”

Section: Calculation and Assessment Of Sea-air Co 2 Fluxesmentioning

confidence: 99%

Sea–air CO2 fluxes in the Indian Ocean between 1990 and 2009

et al. 2013

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Abstract. The Indian Ocean (44 • S-30 • N) plays an important role in the global carbon cycle, yet it remains one of the most poorly sampled ocean regions. Several approaches have been used to estimate net sea-air CO 2 fluxes in this region: interpolated observations, ocean biogeochemical models, atmospheric and ocean inversions. As part of the RECCAP (REgional Carbon Cycle Assessment and Processes) project, we combine these different approaches to quantify and assess the magnitude and variability in Indian Ocean sea-air CO 2 fluxes between 1990 and 2009. Using all of the models and inversions, the median annual mean sea-air CO 2 uptake of −0.37 ± 0.06 PgC yr −1 is consistent with the −0.24 ± 0.12 PgC yr −1 calculated from observations. The fluxes from the southern Indian Ocean (18-44 • S; −0.43 ± 0.07 PgC yr −1 ) are similar in magnitude to the annual uptake for the entire Indian Ocean. All models capture the observed pattern of fluxes in the Indian Ocean with the following exceptions: underestimation of upwelling fluxes in the northwestern region (off Oman and Somalia), overestimation in the northeastern region (Bay of Bengal) and underestimation of the CO 2 sink in the subtropical convergence zone. These differences were mainly driven by lack of atmospheric CO 2 data in atmospheric inversions, and poor simulation of monsoonal currents and freshwater discharge in ocean biogeochemical models. Overall, the models and inversions do capture the phase of the observed seasonality for the entire Indian Ocean but overestimate the magnitude. The predicted sea-air CO 2 fluxes by ocean biogeochemical models (OBGMs) respond to seasonal variability with strong phase lags with reference to climatological CO 2 flux, whereas the atmospheric inversions predicted an order of magnitude higher seasonal flux than OBGMs. The simulated interannual variability by the OBGMs is weaker than that found by atmospheric inversions. Prediction of such weak interannual variability in CO 2 fluxes by atmospheric inversions was mainly caused by a lack of atmospheric data in the Indian Ocean. The OBGM models suggest a small strengthening of the sink over the period 1990-2009 of −0.01 PgC decade −1 . This is inconsistent with the observations in the southwestern Indian Ocean that shows the growth rate of oceanic pCO 2 was faster than the observed atmospheric CO 2 growth, a finding attributed to the trend of the Southern Annular Mode (SAM) during the 1990s.Published by Copernicus Publications on behalf of the European Geosciences Union. 7036

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“…Atlantic, with relatively fewer observations and little modeling analysis. To date, there is limited analysis of interannual variability or long-term trend in the ocean-atmosphere CO 2 flux, and there are marked discrepancies for the tropical Atlantic among the various approaches [Schuster et al, 2013]. Moreover, while both the tropical Pacific and Atlantic Oceans are referred to as upwelling regions, the differences and similarities of carbon fields between the two basins have not been analyzed in detail.…”

Section: Introductionmentioning

confidence: 99%

Seasonal to decadal variations of sea surface pCO₂ and sea‐air CO₂ flux in the equatorial oceans over 1984–2013: A basin‐scale comparison of the Pacific and Atlantic Oceans

Wang

Murtugudde

Hackert

et al. 2015

Global Biogeochemical Cycles

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The equatorial Pacific and Atlantic Oceans release significant amount of CO 2 each year. Not much attention has been paid to evaluating the similarities and differences between these two basins in terms of temporal variability. Here we employ a basin-scale, fully coupled physical-biogeochemical model to study the spatial and temporal variations in sea surface pCO 2 and air-sea CO 2 flux over the period of 1984-2013 in the equatorial Pacific and Atlantic Oceans. The model reproduces the overall spatial and temporal variations in the carbon fields for both basins, including higher values to the south of the equator than to the north, the annual maximum sea surface pCO 2 in boreal spring, and the annual peak in sea-to-air CO 2 flux in boreal fall in the upwelling regions. The equatorial Pacific reveals a large interannual variability in sea surface pCO 2 , which is associated with the El Niño-Southern Oscillation. As a contrast, there is a strong seasonality but little interannual variability in the carbon fields of the equatorial Atlantic. The former is driven by the variability of dissolved inorganic carbon but the latter by sea surface temperature. Our model estimates an average sea-to-air CO 2 flux of 0.521 ± 0.204 Pg C yr À1 for the tropical Pacific (18°S-18°N, 150°E-90°W), which is in good agreement with the observation-based estimate (0.51 ± 0.24 Pg C yr À1 ). On average, sea-to-air CO 2 flux is 0.214 ± 0.03 Pg C yr À1 in the tropical Atlantic (10°S-10°N), which compares favorably with observational estimates.

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An assessment of the Atlantic and Arctic sea–air CO<sub>2</sub> fluxes, 1990–2009

Cited by 194 publications

References 86 publications

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Sea–air CO<sub>2</sub> fluxes in the Indian Ocean between 1990 and 2009

Seasonal to decadal variations of sea surface pCO₂ and sea‐air CO₂ flux in the equatorial oceans over 1984–2013: A basin‐scale comparison of the Pacific and Atlantic Oceans

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An assessment of the Atlantic and Arctic sea–air CO&lt;sub&gt;2&lt;/sub&gt; fluxes, 1990–2009

Cited by 194 publications

References 86 publications

Air–sea exchanges of CO&lt;sub&gt;2&lt;/sub&gt; in the world's coastal seas

Air–sea exchanges of CO&lt;sub&gt;2&lt;/sub&gt; in the world's coastal seas

Sea–air CO&lt;sub&gt;2&lt;/sub&gt; fluxes in the Indian Ocean between 1990 and 2009

Seasonal to decadal variations of sea surface pCO2 and sea‐air CO2 flux in the equatorial oceans over 1984–2013: A basin‐scale comparison of the Pacific and Atlantic Oceans

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An assessment of the Atlantic and Arctic sea–air CO<sub>2</sub> fluxes, 1990–2009

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Sea–air CO<sub>2</sub> fluxes in the Indian Ocean between 1990 and 2009

Seasonal to decadal variations of sea surface pCO₂ and sea‐air CO₂ flux in the equatorial oceans over 1984–2013: A basin‐scale comparison of the Pacific and Atlantic Oceans