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| Titel |
Carbon budget estimation by inverse modeling with atmospheric CO2 concentrations from surface and CONTRAIL measurements |
| VerfasserIn |
Yosuke Niwa, Toshinobu Machida, Yousuke Sawa, Hidekazu Matsueda, Ryoichi Imasu, Masaki Satoh |
| 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 |
250049333
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| Zusammenfassung |
| A great deal of understanding of the global and regional carbon budget helps us to perform a
reliable prediction of future climate with an earth system model. However, the accuracy of
CO2 source/sink estimation by inverse modeling, which is one of the leading methods to
estimate regional carbon budget, is not very high because of sparse observational data
coverage. The recent evolving aircraft measurements of CO2 in a three-dimensional
view are expected to provide new constraints on the estimation of surface CO2
fluxes.
In this study, regionally divided carbon budgets are estimated by inverse modeling using
surface measurement networks and aircraft measurements from Comprehensive
Observation Network for Trace gases by Airliner (CONTRAIL). The CONTRAIL project
has started since late 2005 and a huge amount of atmospheric CO2 data has been
obtained covering altitudes between the earth’s surface to the upper-troposphere
and lower-stratosphere, latitudes between the boreal high-latitudes to the austral
mid-latitudes. Monthly mean observational data from GLOBALVIEW-CO2, which
mostly consists of surface measurements, and CONTRAIL are used in this inverse
analysis. The CONTRAIL data measured both vertically over each airport and
horizontally at the cruising altitude are used. The inversion method is based on the
Bayesian statistics and the approach of the TransCom 3 is used. To relate atmospheric
concentrations to surface fluxes, a three-dimensional transport model is employed. In this
study, Nonhydrostatic ICosahedral Atmosphere Model (NICAM)-based transport
model (NICAM-TM) is used with prescribed CO2 flux data of fossil fuel emission,
respiration/photosynthesis in terrestrial biosphere and atmosphere-ocean exchange. The
transport simulations of atmospheric CO2 are performed by low-resolution version of
NICAM; the horizontal grid interval is about 240 km. The analyzed period is five years
during 2005—2009 and meteorological fields in each year are used to drive the transport
model with the nudging method. The inversion setup is similar to TransCom 3,
but number of flux regions to be estimated is 42. Land regions are divided into 31
according to vegetation types and the same 11 ocean regions as TransCom 3 are
used.
A preliminary result of forward simulation with the prescribed fluxes shows that the
transport model has good performance for reproducing general features of three-dimensional
structure of CO2 observed by CONTRAIL. However, some discrepancies between the
simulation and CONTRAIL are found in horizontal gradient even in the upper-troposphere
during summer, indicating that aircraft measurements have significant impacts on flux
estimates when vertical transport is efficient. The inversion results will be discussed in the
presentation. |
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