The 3rd Chinese National Arctic Research Expedition （CHINARE-Arctic III） was carried out from July to September in 2008. The partial pressure of CO2 （pCO2） in the atmosphere and in surface seawater were determined...The 3rd Chinese National Arctic Research Expedition （CHINARE-Arctic III） was carried out from July to September in 2008. The partial pressure of CO2 （pCO2） in the atmosphere and in surface seawater were determined in the Bering Sea during luly 11-27, 2008, and a large number of seawater samples were taken for total alkalinity （TA） and total dissolved inorganic carbon （DIC） analysis. The distributions of CO2 parameters in the Bering Sea and their controlling factors were discussed. The pCO2 values in surface seawater presented a drastic variation from 148 to 563 laatm （1 μatm = 1.013 25× 10-1Pa）. The lowest pCOz values were observed near the Bering Sea shelf break while the highest pCO2 existed at the western Bering Strait. The Bering Sea generally acts as a net sink for atmospheric CO2 in summer. The air-sea CO2 fluxes in the Bering Sea shelf, slope, and basin were estimated at -9.4, -16.3, and -5.1 mmol/（m2.d）, respectively. The annual uptake of CO2 was about 34 Tg C in the Bering Sea.展开更多
P CO 2 of air and seawater samples from the East China Sea (ECS) were measured in situ in autumn, 1994. Ocean currents, terrestrial fluviation, biological activities, etc.,P CO 2 characters in air and seawater were in...P CO 2 of air and seawater samples from the East China Sea (ECS) were measured in situ in autumn, 1994. Ocean currents, terrestrial fluviation, biological activities, etc.,P CO 2 characters in air and seawater were investigated. CO 2 flux and its character in the East China Sea are discussed on the basis of theP CO 2 profiles of air and seawater. It was clear that the nearshore was the source of CO 2; and that the outer sea area was the sink of CO 2; and that the shelf area of the ECS is a net sink for atmospheric CO 2 in autumn.展开更多
The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean...The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean and atmosphere(i.e.air-sea O_(2)flux),which is one of the major contributors to uncertainties in the O_(2)-based estimations of the carbon uptake.Here,we explore the variability of air-sea O_(2)flux with the use of outputs from Coupled Model Intercomparison Project phase 6(CMIP6).The simulated air-sea O_(2)flux exhibits an obvious warming-induced upward trend(~1.49 Tmol yr−2)since the mid-1980s,accompanied by a strong decadal variability dominated by oceanic climate modes.We subsequently revise the O_(2)-based carbon uptakes in response to this changing air-sea O_(2)flux.Our results show that,for the 1990−2000 period,the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr−1 respectively,overall consistent with estimates derived by the Global Carbon Project(GCP).An enhanced carbon uptake is found in both land and ocean after year 2000,reflecting the modification of carbon cycle under human activities.Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.展开更多
The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investiga...The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investigated. We used observation-based data of fCO2, surface-ocean CO2 partial pressure (pCO2sea), wind speed and sea surface temperature (SST) to analyze the relationship between the NAO and fCO2 of the subtropical and subpolar NA in winter and summer on the interannual time scale. Based on power spectrum estimation, there are significant interannual signs with a 2–6 year cycle in the NAO indexes and area-averaged fCO2 anomalies in winter and summer from 1980 to 2015. Regression analysis with the 2–6 year filtered data shows that on the interannual scale the response of the fCO2 anomalies to the NAO has an obvious meridional wave-train-like pattern in winter, but a zonal distribution in summer. This seasonal difference is because in winter the fCO2 anomalies are mainly controlled by the NAO-driven wind speed anomalies, which have a meridional distribution pattern, while in summer they are dominated by the NAO-driven SST anomalies, which show distinct zonal difference in the subtropical NA. In addition, in the same season, there are different factors controlling the variation of pCO2sea in different regions. In summer, SST is important to the interannual variation of pCO2sea in the subtropical NA, while some biogeochemical variables probably control the pCO2sea variation in the subpolar NA.展开更多
A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface m...A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface microlayer(SML) ,subsurface layer(SSL) and surface layer(SL) . The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order:pCO2 SML> pCO2 SSL> pCO2 SL. The highest values were found in March for all SML,SSL and SL,followed by those in April,and the lowest were in May. The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude,there was a significant negative correlation between it and latitude,i.e.,'high latitude low pCO2'. By using four calculation models,the carbon dioxide fluxes(FC O2) in spring in the Yellow and South China Seas,which were found to act as a 'sink' of atmospheric CO2,were preliminarily estimated on the basis of the pCO2 data in the SML to be -7.00×106 t C and -22.35×106 t C,respectively. It is suggested that the FC O2calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL.展开更多
A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospher...A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospheric CO 2 concentration and different future scenarios （called Rep- resentative Concentration Pathways, or RCPs）. The RCPs in this paper follow the design of Inter- governmental Panel on Climate Change （IPCC） for the Fifth Assessment Report （AR5）. The model results show that the ocean absorbs CO 2 from atmosphere and the absorbability will continue in the 21st century under the four RCPs. The net air-sea CO 2 flux increased during the historical time and reached 1.87 Pg/a （calculated by carbon） in 2005; however, it would reach peak and then decrease in the 21st century. The ocean absorbs CO 2 mainly in the mid latitude, and releases CO 2 in the equator area. However, in the Antarctic Circumpolar Current （ACC） area the ocean would change from source to sink under the rising CO 2 concentration, including RCP4.5, RCP6.0, and RCP8.5. In 2100, the anthropogenic carbon would be transported to the 40 S in the Atlantic Ocean by the North Atlantic Deep Water （NADW）, and also be transported to the north by the Antarctic Bottom Water （AABW） along the Antarctic continent in the Atlantic and Pacific oceans. The ocean pH value is also simulated by the model. The pH decreased by 0.1 after the industrial revolution, and would continue to decrease in the 21st century. For the highest concentration sce- nario of RCP8.5, the global averaged pH would decrease by 0.43 to reach 7.73 due to the absorption of CO 2 from atmosphere.展开更多
Estimating the multi-year average air-sea CO_(2) flux over a large area usually involves the use of monthly mean variables from the atmosphere and ocean.Ignoring sub-monthly processes will blur the oceanic carbon cycl...Estimating the multi-year average air-sea CO_(2) flux over a large area usually involves the use of monthly mean variables from the atmosphere and ocean.Ignoring sub-monthly processes will blur the oceanic carbon cycle,especially when the synoptic and sub-seasonal scale processes are significant,like in the South China Sea(SCS).Based on an empirical relationship between the partial pressure of CO_(2) in water and the sea surface temperature(SST),we recalculated the air-sea CO_(2) flux of the SCS with daily products of atmospheric reanalysis and SST.Our results show that the sub-monthly process contributes 10%of the total CO_(2) flux of the SCS and can even alter the sign of the CO_(2) flux in the spring.In the near-surface coupling process,intramonthly variations in surface winds play the dominant role,except in regions with significant ocean eddies.The co-spectrum analysis of SST and wind speed reveals the most essential oscillation of>20 days.Therefore,a product of the sea surface environment for 10-day intervals can better estimate the air-sea CO_(2) flux over the SCS than monthly data.展开更多
Data on the distribution of dissolved inorganic carbon (DIC) were obtained from two cruises in the North Yellow Sea (NYS) and off the Qingdao Coast (QC) in October, 2007. Carbonate parameters were calculated. The conc...Data on the distribution of dissolved inorganic carbon (DIC) were obtained from two cruises in the North Yellow Sea (NYS) and off the Qingdao Coast (QC) in October, 2007. Carbonate parameters were calculated. The concentrations of DIC are from 1.896-2.229 mmolL-1 in the NYS and from 1.939-2.032 mmolL-1 off the QC. In the southwest of the NYS, DIC in the upper layers decreases from the north of the SP (Shandong Peninsula) shelf to the center of the NYS; whereas in the lower layers DIC increases from the north of the SP shelf to the center of the NYS and South Yellow Sea. In the northeast of the NYS, DIC in all layers in- creases from the YR (Yalu River) estuary to the centre of the NYS. The distribution of DIC in NYS can be used as an indicator of Yellow Sea Cold Water Mass (YSCWM). Air-sea CO2 fluxes were calculated using three models and the results suggest that both the NYS and the QC waters are potential sources of atmospheric CO2 in October.展开更多
We applied a season-reliant empirical orthogonal function(S-EOF) analysis based on the results of the Community Earth System Model, version 1-Biogeochemistry, to seasonal mean air-sea CO_2 flux over the western North ...We applied a season-reliant empirical orthogonal function(S-EOF) analysis based on the results of the Community Earth System Model, version 1-Biogeochemistry, to seasonal mean air-sea CO_2 flux over the western North Pacific(WNP)(0°–35°N, 110°E–150°E). The first leading mode accounts for 29% of the total interannual variance, corresponding to the evolution of the El Ni-Southern Oscillation(ENSO) from its developing to decaying phases. During the ENSO developing phase in the summer and fall, the contribution of surface seawater CO_2 partial pressure anomalies is greater than that of gas transfer/solubility anomalies, which contribute to increasing oceanic CO_2 uptake over the WNP. During the ENSO mature phase in the winter, the anomalous southwesterly northwest of the western North Pacific anticyclone(WNPAC) reduces the surface wind speed in the China marginal sea and thus decreases oceanic CO_2 uptake by reducing the gas transfer coefficient. In the subsequent spring, the WNPAC maintains with an eastward shift in position. The anomalous southwesterly warms sea surface temperatures in the China marginal sea by reducing evaporation and thus decreases oceanic CO_2 uptake by enhancing surface seawater CO_2 partial pressure. This process, rather than the effect of decreasing gas transfer coefficient, dominates CO_2 flux anomalies in the spring.展开更多
This study reports the surface water partial pressure of CO_(2)(pCO_(2))and air-sea CO_(2)fluxes on the East China Sea shelf off the Changjiang estuary in August 2023.Surface water pCO_(2)ranged from 110μatm to 910μ...This study reports the surface water partial pressure of CO_(2)(pCO_(2))and air-sea CO_(2)fluxes on the East China Sea shelf off the Changjiang estuary in August 2023.Surface water pCO_(2)ranged from 110μatm to 910μatm with an average value of 427±154μatm.Air-sea CO_(2)fluxes in the surveyed area ranged from-20.6 mmol m-2d-1to 35.9 mmol m-2d-1and averaged 3.0±8.9 mmol m-2d-1(a moderate source),which was contrary to this region generally being a CO_(2)sink during summer.Changjiang discharge played a key role in regulating surface water pCO_(2);the decreased Changjiang discharge in August 2023 increased surface water pCO_(2)on the adjacent inner shelf substantially,and the high sea surface temperature further elevated the surface water pCO_(2).The combined effect of drought and high temperatures in August 2023 turned the study area from a CO_(2)sink to a CO_(2)source.Under the context of global change,climate events such as floods,droughts and heatwaves occur more frequently,which will continue to add more complexity to CO_(2)sink/source evaluations in large river-dominated marginal seas and suggest further research is needed.展开更多
This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and th...This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and the Bohai Sea. Emphasis is given to CO_2 fluxes across the air-sea interface and their controls. The net flux of CO_2 degassing from the China Seas is estimated to be9.5±53 Tg C yr^(-1). The total riverine carbon flux through estuaries to the China Seas is estimated as 59.6±6.4 Tg C yr^(-1). Chinese estuaries annually emit 0.74±0.02 Tg C as CO_2 to the atmosphere. Additionally, there is a very large net carbon influx from the Western Pacific to the China Seas, amounting to ～2.5 Pg C yr^(-1). As a first-order estimate, the total export flux of particulate organic carbon from the upper ocean of the China Seas is 240±80 Tg C yr^(-1). This review also attempts to examine current knowledge gaps to promote a better understanding of the carbon cycle in this important region.展开更多
Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross...Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross primary production and net community production of the mixed layer zone,respectively.Although there is a substantial advantage in refining the gas exchange term and water column vertical mixing calibration,application of mixed layer depth history to the gas exchange term and its contribution to reducing indices error are unclear.Therefore,two cruises were conducted in the slope regions of the northern South China Sea in October 2014(autumn)and June 2015(spring).Discrete water samples at Station L07 in the upper 150 m depth were collected for the determination ofδ^(17)0,δ^(18)O,and the O_(2)/Ar ratio of dissolved gases.Gross oxygen production(GOP)was estimated using the triple oxygen isotopes of the dissolved O_(2),and net oxygen production(NOP)was calculated using O_(2)/Ar ratio and O_(2)concentration.The vertical mixing effect in NOP was calibrated via a N_(2)O based approach.GOP for autumn and spring was(169±23)mmol/(m^(2)·d)(by O_(2))and(189±26)mmol/(m^(2)·d)(by O_(2)),respectively.While NOP was 1.5 mmol/(m^(2)·d)(by O_(2))in autumn and 8.2 mmol/(m^(2)·d)(by O_(2))in spring.Application of mixed layer depth history in the gas flux parametrization reduced up to 9.5%error in the GOP and NOP estimations.A comparison with an independent O_(2)budget calculation in the diel observation indicated a26%overestimation in the current GOP,likely due to the vertical mixing effect.Both GOP and NOP in June were higher than those in October.Potential explanations for this include the occurrence of an eddy process in June,which may have exerted a submesoscale upwelling at the sampling station,and also the markedly higher terrestrial impact in June.展开更多
In the east of China＇s seas, there is a wide range of the continental shelf. The nutrient cycle and the carbon cycle in the east of China＇s seas exhibit a strong variability on seasonal to decadal time scales. On th...In the east of China＇s seas, there is a wide range of the continental shelf. The nutrient cycle and the carbon cycle in the east of China＇s seas exhibit a strong variability on seasonal to decadal time scales. On the basis of a regional ocean modeling system（ROMS）, a three dimensional physical-biogeochemical model including the carbon cycle with the resolution（1/12）°×（1/12）° is established to investigate the physical variations, ecosystem responses and carbon cycle consequences in the east of China＇s seas. The ROMS-Nutrient Phytoplankton Zooplankton Detritus（NPZD） model is driven by daily air-sea fluxes（wind stress, long wave radiation, short wave radiation, sensible heat and latent heat, freshwater fluxes） that derived from the National Centers for Environmental Prediction（NCEP） reanalysis2 from 1982 to 2005. The coupled model is capable of reproducing the observed seasonal variation characteristics over the same period in the East China Sea. The integrated air-sea CO_2 flux over the entire east of China＇s seas reveals a strong seasonal cycle, functioning as a source of CO_2 to the atmosphere from June to October, while serving as a sink of CO_2 to the atmosphere in the other months. The 24 a mean value of airsea CO_2 flux over the entire east of China＇s seas is about 1.06 mol/（m^2·a）, which is equivalent to a regional total of3.22 Mt/a, indicating that in the east of China＇s seas there is a sink of CO_2 to the atmosphere. The partial pressure of carbon dioxide in sea water in the east of China＇s seas has an increasing rate of 1.15 μatm/a（1μtm/a=0.101 325Pa）, but p H in sea water has an opposite tendency, which decreases with a rate of 0.001 3 a^（–1） from 1982 to 2005.Biological activity is a dominant factor that controls the pCO_2 air in the east of China＇s seas, and followed by a temperature. The inverse relationship between the interannual variability of air-sea CO_2 flux averaged from the domain area and Ni？o3 SST Index indicates that the carbon cycle in the east of China＇s seas has a high correlation with El Ni？o-Southern Oscillation（ENSO）.展开更多
基金The National Natural Science Foundation of China (NSFC) under contract Nos 40976116 and 40531007the Fujian Science Foundation under contract No.2009J06025+3 种基金the SOA Youth Foundation Grant under contract No.2012538the Chinese Projects for Investigations and Assessments of the Arctic and Antarctic under contract Nos CHINARE2012: 01-04, 02-01, 03-04, 04-03, 04-04, and CHINARE2013: 01-04, 02-01, 03-04, 04-03, 04-04the Chinese International Cooperation Projects under contract Nos IC201114, IC201201, IC201308, and HC120601the Scientific Research Foundation of Third Institute of Oceanography, SOA under contract Nos 2012006 and 2014006
文摘The 3rd Chinese National Arctic Research Expedition （CHINARE-Arctic III） was carried out from July to September in 2008. The partial pressure of CO2 （pCO2） in the atmosphere and in surface seawater were determined in the Bering Sea during luly 11-27, 2008, and a large number of seawater samples were taken for total alkalinity （TA） and total dissolved inorganic carbon （DIC） analysis. The distributions of CO2 parameters in the Bering Sea and their controlling factors were discussed. The pCO2 values in surface seawater presented a drastic variation from 148 to 563 laatm （1 μatm = 1.013 25× 10-1Pa）. The lowest pCOz values were observed near the Bering Sea shelf break while the highest pCO2 existed at the western Bering Strait. The Bering Sea generally acts as a net sink for atmospheric CO2 in summer. The air-sea CO2 fluxes in the Bering Sea shelf, slope, and basin were estimated at -9.4, -16.3, and -5.1 mmol/（m2.d）, respectively. The annual uptake of CO2 was about 34 Tg C in the Bering Sea.
文摘P CO 2 of air and seawater samples from the East China Sea (ECS) were measured in situ in autumn, 1994. Ocean currents, terrestrial fluviation, biological activities, etc.,P CO 2 characters in air and seawater were investigated. CO 2 flux and its character in the East China Sea are discussed on the basis of theP CO 2 profiles of air and seawater. It was clear that the nearshore was the source of CO 2; and that the outer sea area was the sink of CO 2; and that the shelf area of the ECS is a net sink for atmospheric CO 2 in autumn.
基金the World Climate Recruitment Programme’s (WCRP) Working Group on Coupled Modelling (WGCM)the Global Organization for Earth System Science Portals (GO-ESSP)+2 种基金jointly supported by the National Science Foundation of China (Grant Nos. 41991231, 91937302)the China 111 project (Grant No. B13045)supported by Supercomputing Center of Lanzhou University
文摘The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean and atmosphere(i.e.air-sea O_(2)flux),which is one of the major contributors to uncertainties in the O_(2)-based estimations of the carbon uptake.Here,we explore the variability of air-sea O_(2)flux with the use of outputs from Coupled Model Intercomparison Project phase 6(CMIP6).The simulated air-sea O_(2)flux exhibits an obvious warming-induced upward trend(~1.49 Tmol yr−2)since the mid-1980s,accompanied by a strong decadal variability dominated by oceanic climate modes.We subsequently revise the O_(2)-based carbon uptakes in response to this changing air-sea O_(2)flux.Our results show that,for the 1990−2000 period,the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr−1 respectively,overall consistent with estimates derived by the Global Carbon Project(GCP).An enhanced carbon uptake is found in both land and ocean after year 2000,reflecting the modification of carbon cycle under human activities.Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.
基金supported jointly by the National Key Research and Development Program of China (Grant No. 2016YFB0200800)the National Natural Science Foundation of China (Grant No. 41530426)
文摘The differences in the influences of the North Atlantic Oscillation (NAO) on the air–sea CO2 fluxes (fCO2) in the North Atlantic (NA) between different seasons and between different regions are rarely fully investigated. We used observation-based data of fCO2, surface-ocean CO2 partial pressure (pCO2sea), wind speed and sea surface temperature (SST) to analyze the relationship between the NAO and fCO2 of the subtropical and subpolar NA in winter and summer on the interannual time scale. Based on power spectrum estimation, there are significant interannual signs with a 2–6 year cycle in the NAO indexes and area-averaged fCO2 anomalies in winter and summer from 1980 to 2015. Regression analysis with the 2–6 year filtered data shows that on the interannual scale the response of the fCO2 anomalies to the NAO has an obvious meridional wave-train-like pattern in winter, but a zonal distribution in summer. This seasonal difference is because in winter the fCO2 anomalies are mainly controlled by the NAO-driven wind speed anomalies, which have a meridional distribution pattern, while in summer they are dominated by the NAO-driven SST anomalies, which show distinct zonal difference in the subtropical NA. In addition, in the same season, there are different factors controlling the variation of pCO2sea in different regions. In summer, SST is important to the interannual variation of pCO2sea in the subtropical NA, while some biogeochemical variables probably control the pCO2sea variation in the subpolar NA.
基金This work was supported by the Key Project of the National Natural Science Foundation of China(No.40490263)the National Natural Science Foundation of China(Nos.40706040,40376022 and 40606023)+1 种基金the Doctoral Program for Higher Education(20030423007)Scientific Research Promotional fund for Middle-age and Young Scientist of Shandong Province(2007BS08015).
文摘A multilayer study of pCO2 for the Yellow and South China Seas in the surface waters was conducted based on data from four cruises sponsored by the China SOLAS Project in 2005 and 2006,including data for the surface microlayer(SML) ,subsurface layer(SSL) and surface layer(SL) . The carbon fluxes across the air-sea interface were calculated. The results showed that the pCO2 values in the surface waters of the study area decreased in the following order:pCO2 SML> pCO2 SSL> pCO2 SL. The highest values were found in March for all SML,SSL and SL,followed by those in April,and the lowest were in May. The pCO2 values had a significant positive correlation with temperature or salinity. While there was no relationship between pCO2 and longitude,there was a significant negative correlation between it and latitude,i.e.,'high latitude low pCO2'. By using four calculation models,the carbon dioxide fluxes(FC O2) in spring in the Yellow and South China Seas,which were found to act as a 'sink' of atmospheric CO2,were preliminarily estimated on the basis of the pCO2 data in the SML to be -7.00×106 t C and -22.35×106 t C,respectively. It is suggested that the FC O2calculated on the basis of pCO2 data in the SML is more reliable than that calculated on the basis of those in the SL.
基金The 973 Project under contract Nos 2010CB950300 and 2010CB950500the Key Project of the National Natural Science Foundation of China under contract No. 40730842+1 种基金the Public Science and Technology Research Funds projects of ocean under contract No. 201105019the International Cooperation Project of Ministry of Science and Technology of China under contract No. S2011GR0348
文摘A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospheric CO 2 concentration and different future scenarios （called Rep- resentative Concentration Pathways, or RCPs）. The RCPs in this paper follow the design of Inter- governmental Panel on Climate Change （IPCC） for the Fifth Assessment Report （AR5）. The model results show that the ocean absorbs CO 2 from atmosphere and the absorbability will continue in the 21st century under the four RCPs. The net air-sea CO 2 flux increased during the historical time and reached 1.87 Pg/a （calculated by carbon） in 2005; however, it would reach peak and then decrease in the 21st century. The ocean absorbs CO 2 mainly in the mid latitude, and releases CO 2 in the equator area. However, in the Antarctic Circumpolar Current （ACC） area the ocean would change from source to sink under the rising CO 2 concentration, including RCP4.5, RCP6.0, and RCP8.5. In 2100, the anthropogenic carbon would be transported to the 40 S in the Atlantic Ocean by the North Atlantic Deep Water （NADW）, and also be transported to the north by the Antarctic Bottom Water （AABW） along the Antarctic continent in the Atlantic and Pacific oceans. The ocean pH value is also simulated by the model. The pH decreased by 0.1 after the industrial revolution, and would continue to decrease in the 21st century. For the highest concentration sce- nario of RCP8.5, the global averaged pH would decrease by 0.43 to reach 7.73 due to the absorption of CO 2 from atmosphere.
基金supported by the National Key Research and Development Program of China (Grant No. 2023YFF0805502)the Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant No. SML2022SP401)+1 种基金the Ocean Negative Carbon Emissions (ONCE) Programthe National Natural Science Foundation of China (Grant No. 42305078)
文摘Estimating the multi-year average air-sea CO_(2) flux over a large area usually involves the use of monthly mean variables from the atmosphere and ocean.Ignoring sub-monthly processes will blur the oceanic carbon cycle,especially when the synoptic and sub-seasonal scale processes are significant,like in the South China Sea(SCS).Based on an empirical relationship between the partial pressure of CO_(2) in water and the sea surface temperature(SST),we recalculated the air-sea CO_(2) flux of the SCS with daily products of atmospheric reanalysis and SST.Our results show that the sub-monthly process contributes 10%of the total CO_(2) flux of the SCS and can even alter the sign of the CO_(2) flux in the spring.In the near-surface coupling process,intramonthly variations in surface winds play the dominant role,except in regions with significant ocean eddies.The co-spectrum analysis of SST and wind speed reveals the most essential oscillation of>20 days.Therefore,a product of the sea surface environment for 10-day intervals can better estimate the air-sea CO_(2) flux over the SCS than monthly data.
文摘Data on the distribution of dissolved inorganic carbon (DIC) were obtained from two cruises in the North Yellow Sea (NYS) and off the Qingdao Coast (QC) in October, 2007. Carbonate parameters were calculated. The concentrations of DIC are from 1.896-2.229 mmolL-1 in the NYS and from 1.939-2.032 mmolL-1 off the QC. In the southwest of the NYS, DIC in the upper layers decreases from the north of the SP (Shandong Peninsula) shelf to the center of the NYS; whereas in the lower layers DIC increases from the north of the SP shelf to the center of the NYS and South Yellow Sea. In the northeast of the NYS, DIC in all layers in- creases from the YR (Yalu River) estuary to the centre of the NYS. The distribution of DIC in NYS can be used as an indicator of Yellow Sea Cold Water Mass (YSCWM). Air-sea CO2 fluxes were calculated using three models and the results suggest that both the NYS and the QC waters are potential sources of atmospheric CO2 in October.
基金supported by the National Natural Science Foundation of China(Grant Nos.41330423,41420104006)Jiangsu Collaborative Innovation Center for Climate Change
文摘We applied a season-reliant empirical orthogonal function(S-EOF) analysis based on the results of the Community Earth System Model, version 1-Biogeochemistry, to seasonal mean air-sea CO_2 flux over the western North Pacific(WNP)(0°–35°N, 110°E–150°E). The first leading mode accounts for 29% of the total interannual variance, corresponding to the evolution of the El Ni-Southern Oscillation(ENSO) from its developing to decaying phases. During the ENSO developing phase in the summer and fall, the contribution of surface seawater CO_2 partial pressure anomalies is greater than that of gas transfer/solubility anomalies, which contribute to increasing oceanic CO_2 uptake over the WNP. During the ENSO mature phase in the winter, the anomalous southwesterly northwest of the western North Pacific anticyclone(WNPAC) reduces the surface wind speed in the China marginal sea and thus decreases oceanic CO_2 uptake by reducing the gas transfer coefficient. In the subsequent spring, the WNPAC maintains with an eastward shift in position. The anomalous southwesterly warms sea surface temperatures in the China marginal sea by reducing evaporation and thus decreases oceanic CO_2 uptake by enhancing surface seawater CO_2 partial pressure. This process, rather than the effect of decreasing gas transfer coefficient, dominates CO_2 flux anomalies in the spring.
基金supported by the National Natural Science Foundation of China(Grant Nos.42141001,42188102)the National Key R&D Projects(Grant No.2022YFC3105302)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB42000000)。
文摘This study reports the surface water partial pressure of CO_(2)(pCO_(2))and air-sea CO_(2)fluxes on the East China Sea shelf off the Changjiang estuary in August 2023.Surface water pCO_(2)ranged from 110μatm to 910μatm with an average value of 427±154μatm.Air-sea CO_(2)fluxes in the surveyed area ranged from-20.6 mmol m-2d-1to 35.9 mmol m-2d-1and averaged 3.0±8.9 mmol m-2d-1(a moderate source),which was contrary to this region generally being a CO_(2)sink during summer.Changjiang discharge played a key role in regulating surface water pCO_(2);the decreased Changjiang discharge in August 2023 increased surface water pCO_(2)on the adjacent inner shelf substantially,and the high sea surface temperature further elevated the surface water pCO_(2).The combined effect of drought and high temperatures in August 2023 turned the study area from a CO_(2)sink to a CO_(2)source.Under the context of global change,climate events such as floods,droughts and heatwaves occur more frequently,which will continue to add more complexity to CO_(2)sink/source evaluations in large river-dominated marginal seas and suggest further research is needed.
基金supported by the National Natural Science Foundation of China (Grant Nos.91328202 & 91428308)the Major Scientific Research Program of the Ministry of Science and Technology (Grant No. 2015CB954001)+1 种基金the Marine Public Welfare Project of the State Oceanic Administration (Grant No. 201505003-3)the Global Change Program (Grant No. GASI-0301-02-02)
文摘This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and the Bohai Sea. Emphasis is given to CO_2 fluxes across the air-sea interface and their controls. The net flux of CO_2 degassing from the China Seas is estimated to be9.5±53 Tg C yr^(-1). The total riverine carbon flux through estuaries to the China Seas is estimated as 59.6±6.4 Tg C yr^(-1). Chinese estuaries annually emit 0.74±0.02 Tg C as CO_2 to the atmosphere. Additionally, there is a very large net carbon influx from the Western Pacific to the China Seas, amounting to ～2.5 Pg C yr^(-1). As a first-order estimate, the total export flux of particulate organic carbon from the upper ocean of the China Seas is 240±80 Tg C yr^(-1). This review also attempts to examine current knowledge gaps to promote a better understanding of the carbon cycle in this important region.
基金The National Key Research and Development Programs of China of the Ministry of Science and Technology under contract Nos 2020YFA0608301,2014CB441503the National Natural Science Foundation of China under contract Nos 41976042,41776122+1 种基金the Fundamental Research Funds for the Central Universitiesthe Taishan Scholars Program of Shandong Province,China。
文摘Quantifying the gross and net production is an essential component of carbon cycling and marine ecosystem studies.Triple oxygen isotope measurements and the O_(2)/Ar ratio are powerful indices in quantifying the gross primary production and net community production of the mixed layer zone,respectively.Although there is a substantial advantage in refining the gas exchange term and water column vertical mixing calibration,application of mixed layer depth history to the gas exchange term and its contribution to reducing indices error are unclear.Therefore,two cruises were conducted in the slope regions of the northern South China Sea in October 2014(autumn)and June 2015(spring).Discrete water samples at Station L07 in the upper 150 m depth were collected for the determination ofδ^(17)0,δ^(18)O,and the O_(2)/Ar ratio of dissolved gases.Gross oxygen production(GOP)was estimated using the triple oxygen isotopes of the dissolved O_(2),and net oxygen production(NOP)was calculated using O_(2)/Ar ratio and O_(2)concentration.The vertical mixing effect in NOP was calibrated via a N_(2)O based approach.GOP for autumn and spring was(169±23)mmol/(m^(2)·d)(by O_(2))and(189±26)mmol/(m^(2)·d)(by O_(2)),respectively.While NOP was 1.5 mmol/(m^(2)·d)(by O_(2))in autumn and 8.2 mmol/(m^(2)·d)(by O_(2))in spring.Application of mixed layer depth history in the gas flux parametrization reduced up to 9.5%error in the GOP and NOP estimations.A comparison with an independent O_(2)budget calculation in the diel observation indicated a26%overestimation in the current GOP,likely due to the vertical mixing effect.Both GOP and NOP in June were higher than those in October.Potential explanations for this include the occurrence of an eddy process in June,which may have exerted a submesoscale upwelling at the sampling station,and also the markedly higher terrestrial impact in June.
基金The National Key Research and Development Program of China under contract No.2016YFC1401605the National Key Research and Development Program of China under contract No.2016YFC1401605+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA 1102010403the National Natural Science Foundation of China under contract Nos 41222038,41206023 and 41076011the Public Science and Technology Research Funds projects of Ocean of China under contract No.201205018the Guangdong Provincial Key Laboratory of Fishery Ecology and Environment under contract No.LFE-2015-3
文摘In the east of China＇s seas, there is a wide range of the continental shelf. The nutrient cycle and the carbon cycle in the east of China＇s seas exhibit a strong variability on seasonal to decadal time scales. On the basis of a regional ocean modeling system（ROMS）, a three dimensional physical-biogeochemical model including the carbon cycle with the resolution（1/12）°×（1/12）° is established to investigate the physical variations, ecosystem responses and carbon cycle consequences in the east of China＇s seas. The ROMS-Nutrient Phytoplankton Zooplankton Detritus（NPZD） model is driven by daily air-sea fluxes（wind stress, long wave radiation, short wave radiation, sensible heat and latent heat, freshwater fluxes） that derived from the National Centers for Environmental Prediction（NCEP） reanalysis2 from 1982 to 2005. The coupled model is capable of reproducing the observed seasonal variation characteristics over the same period in the East China Sea. The integrated air-sea CO_2 flux over the entire east of China＇s seas reveals a strong seasonal cycle, functioning as a source of CO_2 to the atmosphere from June to October, while serving as a sink of CO_2 to the atmosphere in the other months. The 24 a mean value of airsea CO_2 flux over the entire east of China＇s seas is about 1.06 mol/（m^2·a）, which is equivalent to a regional total of3.22 Mt/a, indicating that in the east of China＇s seas there is a sink of CO_2 to the atmosphere. The partial pressure of carbon dioxide in sea water in the east of China＇s seas has an increasing rate of 1.15 μatm/a（1μtm/a=0.101 325Pa）, but p H in sea water has an opposite tendency, which decreases with a rate of 0.001 3 a^（–1） from 1982 to 2005.Biological activity is a dominant factor that controls the pCO_2 air in the east of China＇s seas, and followed by a temperature. The inverse relationship between the interannual variability of air-sea CO_2 flux averaged from the domain area and Ni？o3 SST Index indicates that the carbon cycle in the east of China＇s seas has a high correlation with El Ni？o-Southern Oscillation（ENSO）.
