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| Titel |
Simulations of column-averaged CO2 and CH4 using the NIES TM with a hybrid sigma-isentropic (σ-θ) vertical coordinate |
| VerfasserIn |
D. A. Belikov, S. Maksyutov, V. Sherlock, S. Aoki, N. M. Deutscher, S. Dohe, D. Griffith, E. Kyrö, I. Morino, T. Nakazawa, J. Notholt, M. Rettinger, M. Schneider, R. Sussmann, G. C. Toon, P. O. Wennberg, D. Wunch |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 4 ; Nr. 13, no. 4 (2013-02-15), S.1713-1732 |
| Datensatznummer |
250017656
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| Publikation (Nr.) |
 copernicus.org/acp-13-1713-2013.pdf |
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| Zusammenfassung |
| We have developed an improved version of the National Institute for
Environmental Studies (NIES) three-dimensional chemical transport model (TM)
designed for accurate tracer transport simulations in the stratosphere, using
a hybrid sigma-isentropic (σ-θ) vertical coordinate that
employs both terrain-following and isentropic parts switched smoothly around
the tropopause. The air-ascending rate was derived from the effective heating
rate and was used to simulate vertical motion in the isentropic part of the
grid (above level 350 K), which was adjusted to fit to the observed age of
the air in the stratosphere. Multi-annual simulations were conducted using
the NIES TM to evaluate vertical profiles and dry-air column-averaged mole
fractions of CO2 and CH4. Comparisons with balloon-borne observations
over Sanriku (Japan) in 2000–2007 revealed that the tracer transport
simulations in the upper troposphere and lower stratosphere are performed
with accuracies of ~5% for CH4 and SF6, and ~1% for
CO2 compared with the observed volume-mixing ratios. The simulated
column-averaged dry air mole fractions of atmospheric carbon dioxide
(XCO2) and methane (XCH4) were evaluated against daily ground-based
high-resolution Fourier Transform Spectrometer (FTS) observations measured at
twelve sites of the Total Carbon Column Observing Network (TCCON) (Bialystok,
Bremen, Darwin, Garmisch, Izaña, Lamont, Lauder, Orleans, Park Falls,
Sodankylä, Tsukuba, and Wollongong) between January 2009 and January 2011.
The comparison shows the model's ability to reproduce the site-dependent
seasonal cycles as observed by TCCON, with correlation coefficients typically
on the order 0.8–0.9 and 0.4–0.8 for XCO2 and XCH4, respectively, and
mean model biases of ±0.2% and ±0.5%, excluding Sodankylä,
where strong biases are found. The ability of the model to capture the tracer
total column mole fractions is strongly dependent on the model's ability to
reproduce seasonal variations in tracer concentrations in the planetary
boundary layer (PBL). We found a marked difference in the model's ability to
reproduce near-surface concentrations at sites located some distance from
multiple emission sources and where high emissions play a notable role in the
tracer's budget. Comparisons with aircraft observations over Surgut (West
Siberia), in an area with high emissions of methane from wetlands, show
contrasting model performance in the PBL and in the free troposphere. Thus,
the PBL is another critical region for simulating the tracer total column
mole fractions. |
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