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| Titel |
Observations of XCO2 and XCH4 with ground-based high-resolution FTS at Saga, Japan, and comparisons with GOSAT products |
| VerfasserIn |
H. Ohyama, S. Kawakami, T. Tanaka, I. Morino, O. Uchino, M. Inoue, T. Sakai, T. Nagai, A. Yamazaki, A. Uchiyama, T. Fukamachi, M. Sakashita, T. Kawasaki, T. Akaho, K. Arai, H. Okumura |
| 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 ; 8, no. 12 ; Nr. 8, no. 12 (2015-12-17), S.5263-5276 |
| Datensatznummer |
250116726
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| Publikation (Nr.) |
 copernicus.org/amt-8-5263-2015.pdf |
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| Zusammenfassung |
| Solar absorption spectra in the near-infrared region have been continuously
acquired with a ground-based (g-b) high-resolution Fourier transform
spectrometer (FTS) at Saga, Japan, since July 2011. Column-averaged dry-air
mole fractions of greenhouse gases were retrieved from the measured spectra
for the period from July 2011 to December 2014. Aircraft measurements of
CO2 and CH4 for calibrating the g-b FTS data were performed in
January 2012 and 2013, and it is found that the g-b FTS and aircraft data
agree to within ± 0.2 %. The column-averaged dry-air mole fractions
of CO2 and CH4 (XCO2 and XCH4) show increasing trends,
with average growth rates of 2.3 and 9.5 ppb yr−1,
respectively, during the ∼ 3.5 yr of observation. We compared
the g-b FTS XCO2 and XCH4 data with those derived from
backscattered solar spectra in the short-wavelength infrared (SWIR) region
measured with Thermal And Near-infrared Sensor for carbon
Observation–Fourier Transform Spectrometer (TANSO-FTS) onboard the
Greenhouse gases Observing SATellite (GOSAT): NIES SWIR Level 2 products
(versions 02.xx). Average differences between TANSO-FTS and g-b FTS data
(TANSO-FTS minus g-b FTS) are 0.40 ± 2.51 and −7.6 ± 13.7 ppb
for XCO2 and XCH4, respectively. Using aerosol information
measured with a sky radiometer at Saga, we found that the differences
between the TANSO-FTS and g-b FTS XCO2 data are moderately negatively
correlated with aerosol optical thickness and do not depend explicitly on
aerosol size. In addition, from several aerosol profiles measured with lidar
located right by the g-b FTS, we were able to show that the presence of
cirrus clouds tends to cause an overestimation in the TANSO-FTS XCO2
retrieval, while high aerosol loading in the lower troposphere tends to
cause an underestimation. |
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