Abstract
Variations in the surface boundary layer carbon dioxide concentration (<CO2>) during the 1971 growing season have been analyzed in terms of three periodicities. The diurnal periodicity has an amplitude maximum in the vegetation canopy, of up to 100 vpm, and this diminishes with increasing height above the surface. This variation is driven by the daytime intake of carbon dioxide by the vegetation in photosynthesis and the nighttime release through plant and soil respiration. Spectral analysis of the <CO2> shows the presence of irregular variations, with periods between 3 and 5 days, that appear to be related to synoptic scale weather patterns. Highest <CO2> is found in air that has most recently come from the Pacific Ocean and <CO2> decreases with longer trajectories over land causing a difference of up to 7 vpm in the daily minimum. A 28 vpm decrease in mean daily <CO2> from June to September is considered part of the annual <CO2> variation.
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Claims 5
Claim · model-written summary
Diurnal carbon dioxide variation reached 100 vpm in the canopy and diminished with height.
Verbatim
t0“native grassland”
e0“The diurnal periodicity has an amplitude maximum in the vegetation canopy, of up to 100 vpm, and this diminishes with increasing height above the surface.”
Claim · model-written summary
Daytime photosynthetic intake and nighttime plant and soil respiration drove the diurnal carbon dioxide variation.
Verbatim
t0“native grassland”
e0“This variation is driven by the daytime intake of carbon dioxide by the vegetation in photosynthesis and the nighttime release through plant and soil respiration.”
Claim · model-written summary
Irregular carbon dioxide variations had 3 to 5 day periods and appeared linked to synoptic weather.
- Taxon
- native grasslandt0
- Outcome
- irregular variationse0
- Value
- between 3 and 5 dayse0
- Qualifier
- appear to be related to synoptic scale weather patternse0
- Setting
- synoptic scale weather patternse0
Not reportedDirection
Verbatim
t0“native grassland”
e0“Spectral analysis of the <CO2> shows the presence of irregular variations, with periods between 3 and 5 days, that appear to be related to synoptic scale weather patterns.”
Claim · model-written summary
Carbon dioxide fell with longer trajectories over land, differing by up to 7 vpm in daily minima.
Verbatim
t0“native grassland”
e0“<CO2> decreases with longer trajectories over land causing a difference of up to 7 vpm in the daily minimum.”
Claim · model-written summary
Mean daily carbon dioxide decreased 28 vpm from June to September.
Verbatim
t0“native grassland”
e0“A 28 vpm decrease in mean daily <CO2> from June to September is considered part of the annual <CO2> variation.”