|
Titel |
Error correlation between CO2 and CO as constraint for CO2 flux inversions using satellite data |
VerfasserIn |
H. Wang, D. J. Jacob, M. Kopacz, D. B. A. Jones, P. Suntharalingam, J. A. Fisher, R. Nassar, S. Pawson, J. E. Nielsen |
Medientyp |
Artikel
|
Sprache |
Englisch
|
ISSN |
1680-7316
|
Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-02), S.7313-7323 |
Datensatznummer |
250007662
|
Publikation (Nr.) |
copernicus.org/acp-9-7313-2009.pdf |
|
|
|
Zusammenfassung |
Inverse modeling of CO2 satellite observations to better quantify
carbon surface fluxes requires a chemical transport model (CTM) to
relate the fluxes to the observed column concentrations. CTM transport error
is a major source of uncertainty. We show that its effect can be reduced by
using CO satellite observations as additional constraint in a joint
CO2-CO inversion. CO is measured from space with high precision, is
strongly correlated with CO2, and is more sensitive than CO2 to
CTM transport errors on synoptic and smaller scales. Exploiting this
constraint requires statistics for the CTM transport error correlation
between CO2 and CO, which is significantly different from the
correlation between the concentrations themselves. We estimate the error
correlation globally and for different seasons by a paired-model method
(comparing GEOS-Chem CTM simulations of CO2 and CO columns using
different assimilated meteorological data sets for the same meteorological
year) and a paired-forecast method (comparing 48- vs. 24-h GEOS-5 CTM
forecasts of CO2 and CO columns for the same forecast time). We find
strong error correlations (r2>0.5) between CO2 and CO columns
over much of the extra-tropical Northern Hemisphere throughout the year, and
strong consistency between different methods to estimate the error
correlation. Application of the averaging kernels used in the retrieval for
thermal IR CO measurements weakens the correlation coefficients by 15% on
average (mostly due to variability in the averaging kernels) but preserves
the large-scale correlation structure. We present a simple inverse modeling
application to demonstrate that CO2-CO error correlations can indeed
significantly reduce uncertainty on surface carbon fluxes in a joint
CO2-CO inversion vs. a CO2-only inversion. |
|
|
Teil von |
|
|
|
|
|
|