Tropospheric methane retrieved from ground-based near-IR solar absorption spectra
Abstract
High-resolution near-infrared solar absorption spectra recorded between 1977 and 1995 at the Kitt Peak National Solar Observatory are analyzed to retrieve column abundances of methane (CH_4), hydrogen fluoride (HF), and oxygen (O_2). Employing a stratospheric "slope equilibrium" relationship between CH_4 and HF, the varying contribution of stratospheric CH_4 to the total column is inferred. Variations in the CH_4 column due to changes in surface pressure are determined from the O_2 column abundances. By this technique, CH_4 tropospheric volume mixing ratios are determined with a precision of ∼0.5%. These display behavior similar to Mauna Loa in situ surface measurements, with a seasonal peak-to-peak amplitude of approximately 30 ppbv and a nearly linear increase between 1977 and 1983 of 18.0 ± 0.8 ppbv yr^(−1), slowing significantly after 1990.
Additional Information
© 2003 American Geophysical Union. Received 14 June 2003; revised 2 October 2003; accepted 29 October 2003; article first published online 13 December 2003. We thank the Kitt Peak personnel who acquired these spectra. We thank Linda Brown, Ming Luo, James Randerson, and Zhonghua Yang for helpful discussions. We acknowledge the NOAA CMDL and GAGE/AGAGE networks for the use of their data. R.A.W. acknowledges support from NSF and the California Institute of Technology. P.O.W. and G.C.T. acknowledge support from NASA. Research at JPL, California Institute of Technology, is performed under contract with NASA.Attached Files
Published - grl17293.pdf
Supplemental Material - grl17293-sup-0001-README.txt
Supplemental Material - grl17293-sup-0002-TableS1_1.txt
Supplemental Material - grl17293-sup-0003-TableS1_2.txt
Supplemental Material - grl17293-sup-0004-TableS3_1.txt
Supplemental Material - grl17293-sup-0005-FigureS2_1.eps
Supplemental Material - grl17293-sup-0006-FigureS3_1.eps
Supplemental Material - grl17293-sup-0007-FigureS3_2.eps
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Additional details
- Eprint ID
- 46587
- Resolver ID
- CaltechAUTHORS:20140701-074803639
- NSF
- Caltech
- NASA/JPL/Caltech
- Created
-
2014-07-01Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences