scholarly journals Atmospheric CO2 Exchange With the Biosphere and the Ocean

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 503-509 ◽  
Author(s):  
Roger Bergh ◽  
Reidar Nydal
Keyword(s):  
Mixed Layer ◽  
Deep Ocean ◽  
Co2 Exchange ◽  
Time Dependent ◽  
Atmospheric Co2 ◽  
South Pole ◽  
Ocean Mixed Layer ◽  
The South ◽  
Mauna Loa

We model the exchange of carbon between the different reservoirs (atmosphere, ocean mixed layer, deep ocean and biosphere). The influence of the biosphere is investigated using two extreme assumptions: 1) no net biospheric effect and 2) biospheric uptake of CO2 proportional to the atmospheric content of CO2 and time-dependent deforestation. Observations of atmospheric CO2 at Mauna Loa and the South Pole may be fit by both these assumptions.

scholarly journals Contribution of Biological Effects to the Carbon Sources/Sinks and the Trophic Status of the Ecosystem in the Changjiang (Yangtze) River Estuary Plume in Summer as Indicated by Net Ecosystem Production Variations

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1264 ◽  
Author(s):  
Yifan Zhang ◽  
Dewang Li ◽  
Kui Wang ◽  
Bin Xue
Keyword(s):  
Mixed Layer ◽  
Yangtze River ◽  
River Estuary ◽  
Co2 Exchange ◽  
Atmospheric Co2 ◽  
Yangtze River Estuary ◽  
Biological Processes ◽  
Ecosystem Production ◽  
Near Shore ◽  
Exchange Flux

We conducted 24-h real-time monitoring of temperature, salinity, dissolved oxygen, and nutrients in the near-shore (M4-1), front (M4-8), and offshore (M4-13) regions of the 31° N section of the Changjiang (Yangtze) River estuary plume in summer. Carbon dioxide partial pressure changes caused by biological processes (pCO2bio) and net ecosystem production (NEP) were calculated using a mass balance model and used to determine the relative contribution of biological processes (including the release of CO2 from organic matter degradation by microbes and CO2 uptake by phytoplankton) to the CO2 flux in the Changjiang River estuary plume. Results show that seawater in the near-shore region is a source of atmospheric CO2, and the front and offshore regions generally serve as atmospheric CO2 sinks. In the mixed layer of the three regions, pCO2bio has an overall positive feedback effect on the air–sea CO2 exchange flux. The contribution of biological processes to the air–sea CO2 exchange flux (Cont) in the three regions changes to varying extents. From west to east, the daily means (±standard deviation) of the Cont are 32% (±40%), 34% (±216%), and 9% (±13%), respectively. In the front region, the Cont reaches values as high as 360%. Under the mixed layer, the daily means of potential Conts in the near-shore, front, and offshore regions are 34% (±43%), 8% (±13%), and 19% (±24%), respectively. The daily 24-hour means of NEP show that the near-shore region is a heterotrophic system, the front and offshore regions are autotrophic systems in the mixed layer, and all three regions are heterotrophic under the mixed layer.

scholarly journals Observation Based Budget and Lifetime of Excess Atmospheric Carbon Dioxide

2021 ◽  
Author(s):  
Stephen E. Schwartz
Keyword(s):  
Mixed Layer ◽  
Atmospheric Carbon Dioxide ◽  
Deep Ocean ◽  
Compartment Model ◽  
Turnover Time ◽  
Atmospheric Co2 ◽  
Anthropogenic Emissions ◽  
Terrestrial Biosphere ◽  
Subsequent Decrease ◽  
Tightly Coupled

Abstract. The global budgets of CO2 and of excess CO2 (i.e., above preindustrial) in the biogeosphere are examined by a top-down, observationally constrained approach. Global stocks in the atmosphere, mixed-layer and deep ocean, and labile and obdurate terrestrial biosphere, and fluxes between them are quantified; total uptake of carbon by the terrestrial biosphere is constrained by observations, but apportionment to the two terrestrial compartments is only weakly constrained, requiring examination of sensitivity to this apportionment. Because of near equilibrium between the atmosphere and the mixed-layer ocean and near steady state between the atmosphere and the labile biosphere, these three compartments are tightly coupled. For best-estimate present-day anthropogenic emissions the turnover time of excess carbon in these compartments to the deep ocean and obdurate biosphere is 67 to 158 years. Atmospheric CO2 over the Anthropocene is accurately represented by a five-compartment model with four independent parameters: two universal geophysical quantities and two, specific to CO2, treated as variable. The model also accurately represents atmospheric radiocarbon, particularly the large increase due to atmospheric testing of nuclear weapons and the subsequent decrease. The adjustment time of excess atmospheric CO2, evaluated from the rate of decrease following abrupt cessation of emissions, is 78 to 140 years, consistent with the turnover time, approaching a long-time floor of 15–20 % of the value at the time of cessation. The lifetime of excess CO2 found here, several-fold shorter than estimates from current carbon-cycle models, indicates that cessation of anthropogenic emissions atmospheric would result in substantial recovery of CO2 toward its preindustrial value in less than a century.

scholarly journals Analysis of a 39-year continuous atmospheric CO<sub>2</sub> record from Baring Head, New Zealand

2013 ◽  
Vol 10 (4) ◽  
pp. 2683-2697 ◽  
Author(s):  
B. B. Stephens ◽  
G. W. Brailsford ◽  
A. J. Gomez ◽  
K. Riedel ◽  
S. E. Mikaloff Fletcher ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Seasonal Cycle ◽  
Southern Oscillation ◽  
Atmospheric Co2 ◽  
Co2 Uptake ◽  
South Pole ◽  
The South ◽  
Wide Range

Abstract. We present an analysis of a 39-year record of continuous atmospheric CO2 observations made at Baring Head, New Zealand, filtered for steady background CO2 mole fractions during southerly wind conditions. We discuss relationships between variability in the filtered CO2 time series and regional to global carbon cycling. Baring Head is well situated to sample air that has been isolated from terrestrial influences over the Southern Ocean, and experiences extended episodes of strong southerly winds with low CO2 variability. The filtered Baring Head CO2 record reveals an average seasonal cycle with amplitude of 0.95 ppm that is 13% smaller and 3 weeks earlier in phase than that at the South Pole. Seasonal variations in a given year are sensitive to the timing and magnitude of the combined influences of Southern Ocean CO2 fluxes and terrestrial fluxes from both hemispheres. The amplitude of the seasonal cycle varies throughout the record, but we find no significant long-term seasonal changes with respect to the South Pole. Interannual variations in CO2 growth rate in the Baring Head record closely match the El Niño-Southern Oscillation, reflecting the global reach of CO2 mole fraction anomalies associated with this cycle. We use atmospheric transport model results to investigate contributions to seasonal and annual-mean components of the observed CO2 record. Long-term trends in mean gradients between Baring Head and other stations are predominately due to increases in Northern Hemisphere fossil-fuel burning and Southern Ocean CO2 uptake, for which there remains a wide range of future estimates. We find that the postulated recent reduction in the efficiency of Southern Ocean anthropogenic CO2 uptake, as a result of increased zonal winds, is too small to be detectable as significant differences in atmospheric CO2 between mid to high latitude Southern Hemisphere observing stations.

scholarly journals A study of time-dependent primary productivity in a natural upper-ocean mixed layer using a biophysical model

1996 ◽  
Vol 18 (8) ◽  
pp. 1295-1322 ◽  
Author(s):  
Daniel Kamykowski ◽  
Gerald S. Janowitz ◽  
Gary J. Kirkpatrick ◽  
Robert E. Reed
Keyword(s):  
Mixed Layer ◽  
Primary Productivity ◽  
Time Dependent ◽  
Biophysical Model ◽  
Upper Ocean ◽  
Ocean Mixed Layer

The Southeast Pacific Warm Band and Double ITCZ

2010 ◽  
Vol 23 (5) ◽  
pp. 1189-1208 ◽  
Author(s):  
Hirohiko Masunaga ◽  
Tristan S. L’Ecuyer
Keyword(s):  
Mixed Layer ◽  
Deep Convection ◽  
Tropical Rainfall Measuring Mission ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Ocean Mixed Layer ◽  
The South ◽  
Surface Heat Fluxes ◽  
Double Itcz ◽  
Southeast Pacific

Abstract The east Pacific double intertropical convergence zone (ITCZ) in austral fall is investigated with particular focus on the growing processes of its Southern Hemisphere branch. Satellite measurements from the Tropical Rainfall Measuring Mission (TRMM) and Quick Scatterometer (QuikSCAT) are analyzed to derive 8-yr climatology from 2000 to 2007. The earliest sign of the south ITCZ emerges in sea surface temperature (SST) by January, followed by the gradual development of surface convergence and water vapor. The shallow cumulus population starts growing to form the south ITCZ in February, a month earlier than vigorous deep convection is organized into the south ITCZ. The key factors that give rise to the initial SST enhancement or the southeast Pacific warm band are diagnosed by simple experiments. The experiments are designed to calculate SST, making use of an ocean mixed layer “model” forced by surface heat fluxes, all of which are derived from satellite observations. It is found that the shortwave flux absorbed into the ocean mixed layer is the primary driver of the southeast Pacific warm band. The warm band does not develop in boreal fall because the shortwave flux is seasonally so small that it is overwhelmed by other negative fluxes, including the latent heat and longwave fluxes. Clouds offset the net radiative flux by 10–15 W m−2, which is large enough for the warm band to develop in boreal fall if it were not for clouds reflecting shortwave radiation. Interannual variability of the double ITCZ is also discussed in brief.

scholarly journals Analysis of a 39-yr continuous atmospheric CO<sub>2</sub> record from Baring Head, New Zealand

2012 ◽  
Vol 9 (10) ◽  
pp. 15237-15277 ◽  
Author(s):  
B. B. Stephens ◽  
G. W. Brailsford ◽  
A. J. Gomez ◽  
K. Riedel ◽  
S. E. Mikaloff Fletcher ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Seasonal Cycle ◽  
Southern Oscillation ◽  
Atmospheric Co2 ◽  
Co2 Uptake ◽  
South Pole ◽  
The South ◽  
Wide Range

Abstract. We present an analysis of a 39-yr record of continuous atmospheric CO2 observations made at Baring Head, New Zealand, filtered for steady CO2 mole fractions during southerly wind conditions. We discuss relationships between variability in the filtered CO2 time series and regional to global carbon cycling. Baring Head is well situated to sample air that has been isolated from terrestrial influences over the Southern Ocean, and experiences extended periods of strong southerly winds with low CO2 variability. The filtered Baring Head CO2 record reveals an average seasonal cycle with amplitude of 0.95 ppm that is 13% smaller and 3 weeks earlier in phase than that at the South Pole. Seasonal variations in a given year are sensitive to the timing and magnitude of the combined influences of Southern Ocean CO2 fluxes and terrestrial fluxes from both hemispheres. The amplitude of the seasonal cycle varies throughout the record, but we find no significant long-term seasonal changes with respect to the South Pole. Interannual variations in CO2 growth rate in the Baring Head record closely match the El Niño/Southern Oscillation, reflecting the global reach of CO2 mole fraction anomalies associated with this cycle. We use atmospheric transport model results to investigate contributions to seasonal and annual-mean components of the observed CO2 record. Long-term trends in mean gradients between Baring Head and other stations are predominately due to increases in Northern-Hemisphere fossil-fuel burning and Southern Ocean CO2 uptake, for which there remains a wide range of future estimates. We find that the postulated recent reduction in the efficiency of Southern Ocean anthropogenic CO2 uptake as a result of increased zonal winds is too small to be detectable as significant differences in atmospheric CO2 between mid- to high-latitude Southern Hemisphere observing stations.

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