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| Titel |
A method for colocating satellite XCO2 data to ground-based data and its application to ACOS-GOSAT and TCCON |
| VerfasserIn |
H. Nguyen, G. Osterman, D. Wunch, C. O'Dell, L. Mandrake, P. Wennberg, B. Fisher, R. Castano |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 8 ; Nr. 7, no. 8 (2014-08-19), S.2631-2644 |
| Datensatznummer |
250115878
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| Publikation (Nr.) |
 copernicus.org/amt-7-2631-2014.pdf |
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| Zusammenfassung |
Satellite measurements are often compared with higher-precision ground-based
measurements as part of validation efforts. The satellite soundings are
rarely perfectly coincident in space and time with the ground-based
measurements, so a colocation methodology is needed to aggregate "nearby"
soundings into what the instrument would have seen at the location and time
of interest. We are particularly interested in validation efforts for
satellite-retrieved total column carbon dioxide (XCO2), where
XCO2 data from Greenhouse Gas Observing Satellite (GOSAT)
retrievals (ACOS, NIES, RemoteC, PPDF, etc.) or SCanning Imaging Absorption
SpectroMeter for Atmospheric CHartographY (SCIAMACHY) are often colocated and
compared to ground-based column XCO2 measurement from Total
Carbon Column Observing Network (TCCON).
Current colocation methodologies for comparing satellite measurements of
total column dry-air mole fractions of CO2 (XCO2) with
ground-based measurements typically involve locating and averaging the
satellite measurements within a latitudinal, longitudinal, and temporal
window. We examine a geostatistical colocation methodology that takes a
weighted average of satellite observations depending on the "distance" of
each observation from a ground-based location of interest. The "distance"
function that we use is a modified Euclidian distance with respect to
latitude, longitude, time, and midtropospheric temperature at 700 hPa. We
apply this methodology to XCO2 retrieved from GOSAT spectra by the ACOS team, cross-validate the
results to TCCON XCO2 ground-based data, and present some
comparisons between our methodology and standard existing colocation methods
showing that, in general, geostatistical colocation produces smaller
mean-squared error. |
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