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| Titel |
Mechanisms for synoptic variations of atmospheric CO2 in North America, South America and Europe |
| VerfasserIn |
N. C. Parazoo, A. S. Denning, S. R. Kawa, K. D. Corbin, R. S. Lokupitiya, I. T. Baker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 23 ; Nr. 8, no. 23 (2008-12-10), S.7239-7254 |
| Datensatznummer |
250006493
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| Publikation (Nr.) |
 copernicus.org/acp-8-7239-2008.pdf |
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| Zusammenfassung |
| Synoptic variations of atmospheric CO2 produced by interactions between
weather and surface fluxes are investigated mechanistically and
quantitatively in midlatitude and tropical regions using continuous in-situ
CO2 observations in North America, South America and Europe and forward
chemical transport model simulations with the Parameterized Chemistry
Transport Model. Frontal CO2 climatologies show consistently strong,
characteristic frontal CO2 signals throughout the midlatitudes of North
America and Europe. Transitions between synoptically identifiable CO2
air masses or transient spikes along the frontal boundary typically
characterize these signals. One case study of a summer cold front shows
CO2 gradients organizing with deformational flow along weather fronts,
producing strong and spatially coherent variations. In order to
differentiate physical and biological controls on synoptic variations in
midlatitudes and a site in Amazonia, a boundary layer budget equation is
constructed to break down boundary layer CO2 tendencies into components
driven by advection, moist convection, and surface fluxes. This analysis
suggests that, in midlatitudes, advection is dominant throughout the year
and responsible for 60–70% of day-to-day variations on average, with
moist convection contributing less than 5%. At a site in Amazonia,
vertical mixing, in particular coupling between convective transport and
surface CO2 flux, is most important, with advection responsible for
26% of variations, moist convection 32% and surface flux 42%.
Transport model sensitivity experiments agree with budget analysis. These
results imply the existence of a recharge-discharge mechanism in Amazonia
important for controlling synoptic variations of boundary layer CO2,
and that forward and inverse simulations should take care to represent moist
convective transport. Due to the scarcity of tropical observations at the
time of this study, results in Amazonia are not generalized for the tropics,
and future work should extend analysis to additional tropical locations. |
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