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| Titel |
Carbon fluxes and transport in North America: A new perspective from three-dimensional CO2 sampling |
| VerfasserIn |
Cyril Crevoisier, Colm Sweeney, Manuel Gloor, Jorge Sarmiento, Pieter Tans |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056036
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| Zusammenfassung |
| By yielding a three-dimensional coverage of the continent, the new sampling strategy of
atmospheric CO2 vertical profiles over North America from the NOAA/ESRL Global
Monitoring Division aircraft network gives a unique opportunity to study mass exchange
pathways in the troposphere across North America and to design new methods for estimating
surface fluxes.
We use regular aircraft measurements of vertical CO2 profiles (0-8km) performed by
NOAA/ESRL Global Monitoring Division at 19 locations, covering most of North America,
once to twice a month since 2004, in the framework of the North American Carbon Program.
Their analysis reveals strong signatures of CO2 exchanges over the continent: strong CO2
gradient between the boundary layer and the free troposphere, South to North and West to
East CO2 gradients due to transport and flux distribution vegetation uptake and respiration,
and fossil fuel emissions. Based on the clear coherence of the spatial patterns in the data,
we use analyzed wind fields to estimate the transport and surface fluxes creating
this mole fraction difference and to highlight mass exchange pathways over North
America.
By balancing air mass in- and outflows into a control volume put on top of North America
and solving for the surface fluxes, we find a moderate sink of 0.51±0.39PgC.yr-1 for the
period 2004-2006 for the coterminous US, in excellent agreement with forest-inventories
based estimates of the first North American State of the Carbon Cycle Report (SOCCR), and
averaged climate conditions. We find that the highest uptake occurs in the Midwest states and
in the Southeast. This partitioning is in good agreement with estimates of crop uptake, which
proves to be a significant part of the US atmospheric sink, and of secondary forest regrowth in
the East.
Provided that vertical profile measurements are continued, our study offers an
independent means to study interannual variation of the tropospheric CO2 across North
America and to link regional carbon fluxes to climate drivers. |
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