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| Titel |
Evaluations of carbon fluxes in tropical regions estimated by top-down and bottom-up approaches |
| VerfasserIn |
Kazutaka Murakami, Takahiro Sasai, Tsuneo Matsunaga, Makoto Saito, Shamil Maksyutov, Tatsuya Yokota |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108781
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| Publikation (Nr.) |
 EGU/EGU2015-8551.pdf |
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| Zusammenfassung |
| Many researchers have been trying to reveal distribution of carbon flux for understanding
global carbon cycle dynamics. There are two approaches of estimating carbon fluxes
using satellite observation data, and these are generally referred to as top-down and
bottom-up approaches. These approaches are different in that the top-down approach
estimates the carbon flux by using the distributions of CO2 concentration and an
atmospheric transport model, on the other hand, the bottom-up approach estimates the
flux by using the ground surface information (e.g. leaf area, surface temperature)
from the satellite data and a biosphere model. However, many uncertainties are
still remain in carbon flux estimations, because the true values of carbon flux are
still unclear and the estimations vary with the type of the model (e.g. a transport
model, a terrestrial biosphere model) and input data (e.g. satellite data, climate
data). But the satellite-based carbon flux estimations with reduced uncertainty will
be very efficient for identifications of large emission area and terrestrial carbon
stock regions. In this study, we evaluated the carbon flux estimations in tropical
regions from two approaches. We used GOSAT L4A CO2 flux data as top-down
approach estimations, CarbonTracker (CT2013) flux data as top-down approach
estimations (used no satellite data, only ground observations), and net ecosystem
productions (NEP) estimated by the diagnostic type biosphere model BEAMS as
bottom-up approach estimations. GOSAT (Greenhouse gases Observing SATellite)
launched on January 2009 is first satellite to measure the concentrations of GHGs
(CO2, CH4) from space. GOSAT have two sensors that TANSO-FTS (Thermal And
Near infrared Sensor for carbon Observation - Fourier Transform Spectrometer) is
measuring CO2 and CH4 column amount, and TANSO-CAI (Thermal And Near infrared
Sensor for carbon Observation - Cloud and Aerosol Imager) is imaging the states
of atmosphere and land surface and return to same place at three days intervals.
GOSAT L4A data product is the monthly CO2 flux estimations for 64 sub-continental
regions and is estimated by using GOSAT FTS SWIR L2 XCO2 data. CT2013
estimated the surface CO2 fluxes using atmospheric CO2 sampling observations and
the atmospheric transport model. BEAMS NEP is estimated by MODIS data and
climate data. This flux is only natural land CO2 flux, so we used anthropogenic and
biomass burning CO2 emissions same as used in GOSAT L4A data. We compared
with results of these approaches in tropical regions from June 2009 to October
2012. These regions are little observation data and are high uncertainties about flux
estimations. The temporal patterns for this period were indicated similar trends between
GOSAT, CT2013, and BEAMS in many sub-continental regions. But annual net
carbon fluxes averaged three years (2009/06 – 2012/05) were difference in these
estimations (GOSAT: 2.5 GtC/year, CT2013: 1.0 GtC/year, BEAMS: 2.0 GtC/year). |
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