Observed atmospheric concentrations of CO2 and data on the partial pressures of CO2 in surface ocean waters are combined to identify globally significant sources and sinks of CO2. The atmospheric data are compared with boundary layer concentrations calculated with the transport fields generated by a general circulation model (GCM) for specified source-sink distributions. In the model the observed north-south atmospheric concentration gradient can be maintained only if sinks for CO2 are greater in the Northern than in the Southern Hemisphere. The observed differences between the partial pressure of CO2 in the surface waters of the Northern Hemisphere and the atmosphere are too small for the oceans to be the major sink of fossil fuel CO2. Therefore, a large amount of the CO2 is apparently absorbed on the continents by terrestrial ecosystems.

https://science.sciencemag.org/content/sci/247/4949/1431.full.pdf

Observational contrains on the global atmospheric co2 budget.

The first 12 years (1974--1985) of continuous atmospheric CO/sub 2/ measurements from the NOAA GMCC programs at the Mauna Loa Observatory in Hawaii are analyzed. Hourly and daily variations in the concentration of CO/sub 2/ due to local sources and sinks are described, with subsequent selection of data representing background concentrations. A digital filtering technique using the fast Fourier transform and low-pass filters was used to smooth the selected data and to separate the seasonal cycle from the long-term increase in CO/sub 2/. The amplitude of the seasonal cycle was found to be increasing at a rate of 0.05/plus minus/0.02 ppm yr/sup /minus/1/. The average growth rate of CO/sub 2/ was 1.42/plus minus/0.02 ppm yr/sup /minus/1/, and the fraction of CO/sub 2/ remaining in the atmosphere from fossil fuel combustion was 59%. A comparison between the Mauna Loa continuous CO/sub 2/ data and the CO/sub 2/ flask sample data from the sea level site at Cape Kumukahi, Hawaii, showed that the amplitude of the seasonal cycle at Cape Kumakahi was 23% larger than at Mauna Loa, with the phase of the cycle at Mauna Loa lagging the cycle at Cape Kumukahi by about 1-2 weeks. /copyright/ American Geophysical Union 1989

http://www.catskill.net/denisenorris/ThoningK_JGR89.pdf

Atmospheric carbon dioxide at Mauna Loa Observatory: 2. Analysis of the NOAA GMCC data, 1974–1985

The concentration of atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii is reported for eight years (1964-1971) of a long term program to document the effects of the combustion of coal, petroleum, and natural gas on the distribution of CO, in the atmosphere. The new data, when combined with earlier data, indicate that the annual average CO, concentration rose 3.4 '% between 1959 and 1971. The rate of rise, however, has not been steady. In the mid-1960's it declined. Recently it has accelerated. Similar changes in rate have been observed at the South Pole and are evidently a global phenomenon.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.2153-3490.1976.tb00701.x

Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii

Phenomena related to the natural carbon cycle as the 14 C distribution between atmosphere and ocean and the atmospheric response to the input of fossil fuel CO 2 and of 14 C produced in nuclear weapon tests have been quantitatively discussed by other authors using box models. However the exchange coefficients derived from the natural 14 C distribution do not agree with those valid to describe the short-term phenomena. A model consisting of a well mixed atmospheric box coupled to a long-term biosphere, of an ocean surface box and a diffusive deep ocean is discussed. The dynamic parameters were derived from the preindustrial 14 C distribution in atmosphere and ocean. A consistent description of phenomena with completely different characteristic times is possible, because in the box diffusion model the flux from mixed layer to deep sea increases for decreasing time constants of the perturbations. This is in contrary to box models where it is essentially independent of the time constants if they are smaller than a few hundred years. Due to this fact our model is valid for predictions of the atmospheric CO 2 response to the various possible future CO 2 input time functions. DOI: 10.1111/j.2153-3490.1975.tb01671.x

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.2153-3490.1975.tb01671.x

A box diffusion model to study the carbon dioxide exchange in nature

Current knowledge of the world carbon budget is reviewed with special emphasis on the question of whether the biota is a source or a sink for CO/sub 2/. The analysis shows through convergent lines of evidence that the biota is not a sink and may be a source of CO/sub 2/ as large or larger than the fossil fuel source. The issue is important because of the potential that changes in the CO/sub 2/ content of air have for changing climate worldwide. Various analyses suggest that human activities in the near future could release large additional amounts of CO/sub 2/ into the atmosphere with results that are substantially unpredictable.

https://science.sciencemag.org/content/sci/199/4325/141.full.pdf

The Biota and the World Carbon Budget

Six years of measurements (1963–1968) of carbon dioxide in the troposphere and the lower stratosphere are presented. The data reveal an average annual increase of the CO 2 -content of 0.7 ± 0.1 ppm/year, while during this time the annual industrial output has increased from about 1.9 ppm to 2.3 ppm/year. Thus the increase in the atmosphere is about 1/3 of the total output. Considerations of the possible increase of vegetative assimilation due to the higher CO 2 -content of the atmosphere reveals that this is at most 1/4 of the output, probably considerably less. The net transfer to the oceans thus is at least equal to 1/2 of the industrial output. The transfer rate across the sea surface seems effective enough not to represent an appreciable resistance and the decisive factor for determining this transfer therefore is the ocean circulation or turn over rate. The figures quoted indicate that 20–25% of the world oceans must have been available during the time of rapid increase of the industrial output of CO 2 (the last 30–50 years) to explain the rather large amount that has been withdrawn from the atmosphere. Still a continued increase of the fossil fuel combustion as forecast by OECD implies that the CO 2 -content of the atmosphere at the end of the century will be between 370 ppm and 395 ppm as compared with 320 ppm, the average value for 1968. The amplitude of the seasonal variation is found to be about 6.5 ppm at 2 km and 3.5 ppm in the uppermost part of the troposphere. The phase shift of the seasonal variation between these two levels is 25–30 days. On the basis of these data a vertical eddy diffusivity K = 2·10 5 cm 2 sec ?1 is derived. The amplitude of the seasonal variation in the lower stratosphere, 11–12 km, is less than 1 ppm and the phase is delayed at least 1 1/2 month as compared with the upper troposphere. DOI: 10.1111/j.2153-3490.1970.tb00508.x

Variations of the carbon dioxide content of the atmosphere in the northern hemisphere

Measurements of the CO 2 content in the troposphere and lower stratosphere are presented. The seasonal variations at 5 km, 7 km, 9 km and 11 km at 60° are shown, at the last to levels both in tropospheric and stratospheric air. A comparison with previous data confirms that an annual increase of the CO 2 content of the atmosphere by 0.7 ppm occurs. Data from the Indian Ocean and the Atlantic Ocean (30° N) are presented. DOI: 10.1111/j.2153-3490.1966.tb00221.x

Space and time variations of the CO 2 content of the troposphere and lower stratosphere

Variations of carbon dioxide in the atmosphere have been investigated by the analysis of 188 flask samples taken from an airplane at heights up to 3 km during the period 1957 to 1961. The carbon dioxide concentration changes considerably from one time to another. Above 1000 m the range is 308 to 320 ppm, the average 314 ppm. The range and average both increase towards the ground. A seasonal variation in concentration is noted. The amplitude of the variation decreases with increasing height above the ground. The minimum occurs in summer and the maximum in the winter at all altitudes. Some of the seasonal variations at ground level as previously obtained from the Scandinavian network for carbon dioxide sampling do not show up in the analyses from upper levels. DOI: 10.1111/j.2153-3490.1962.tb00120.x

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.2153-3490.1962.tb00120.x

Variations in concentration of carbon dioxide in the free atmosphere

Investigations of the atmospheric CO 2 content have shown that marked differences between samples collected in the troposphere and stratosphere exist (Bischof, 1965; Bischof & Bolin, 1966; Bischof, 1971). Using all data available from flights during 1963–68, a significant change in amplitude and phase of the annual cycle was found when comparing the variations at 12 km with those at lower levels (Bolin & Bischof, 1970). A separation between tropospheric and stratospheric samples was, however, not undertaken, because the data was not adequate. If including samples from the years 1969–71, a data separation clearly shows the change in amplitude and phase between upper troposphere and lower stratosphere. The results are presented below and compared with data obtained at Scripps Institution of Oceanography. The data also show that the annual increase of CO 2 in the atmosphere is increasing by about 0.09 ppm/year 2 . DOI: 10.1111/j.2153-3490.1973.tb00615.x

Carbon dioxide concentration in the upper troposphere and lower stratosphere. III

Ozone measured in cabin air on 14 flights over polar areas shows maximum concentrations during Spring. Ozone numbers close to atmospheric values were found in the air entering the cabin through the air conditioning system but a reduction to about half of this value takes place immediately within the cabin air. Aircraft with recirculating cabin air showed an additional reduction by about 25%. Maximum concentrations are considerably higher and the duration of such periods longer than those reported in FAA Technical Report ADS-5 in which, however, data from polar areas during O3 maximum are missing. Ozone destruction effects within the pressurization system as claimed in the FAA report are doubtful. Although O3 reduction occurs within the cabin air, the threshold value of 0.1 ppm. for breathing air was surpassed in about 75 % of the flight time (8 to 10 hr between Copenhagen and Seattle) and maximum concentrations (0.4 ppm during 4 hr and 0.6 ppm during 1 hr) were found to be close to critical values recommended by the Environmental Protection Agency. Assuming that no O3 destruction takes place in the pressurization system, O3 concentrations exceeding 1 ppm, can be expected to enter the cabin at flight levels for commercial flight on polar routes during Spring. Some experiences during periods of high O3 concentrations were increasing irritation in the eyes and the respiratory tract, effects different from those associated with low humidity in cabin air.

Walter Bischof

Papers

Variations of the carbon dioxide content of the atmosphere in the northern hemisphere

Space and time variations of the CO 2 content of the troposphere and lower stratosphere

Variations in concentration of carbon dioxide in the free atmosphere

Carbon dioxide concentration in the upper troposphere and lower stratosphere. III

Ozone measurements in jet airliner cabin air