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Proceedings Paper

Column abundance of atmospheric CH4 and precipitable water measurements from ground-based infrared solar spectra
Author(s): Heli Wei; Qinghong Liu; Qingshan Xu; Fengsheng Zhao; Zhengfang Song
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Paper Abstract

Infrared solar spectra were measured automatically by an infrared solar spectrometer (ISS) capable of 0.4 cm-1 resolution. Good signal-o-noise ratio (SNR) and relatively high resolution made it possible to select unsaturated, temperature insensitive intervals for a specific absorption gas with minimal overlap by other interfering gases. In the wavelength range of 3.410-3.438μm, the absorption is mainly due to atmospheric methane and water vapor. A line-by-line (LBL) computation method was used to calculate theoretical atmospheric absorption. By adjusting the total column density to obtain an exact agreement between the calculated and observed absorption, the total column density of atmospheric methane and water vapor were obtained. In the paper, some result observed by ISS for more than one year were reported. Since the April of 1997, we have been monitoring the column abundances of atmospheric CH4 and H2O continually on every clear cloudless day with the method indicated above. The results show that CH4 has little variation in one day, but has considerable seasonal variation. More than one high density peaks were found, two of which occurred in hot summer and cold winter, and the smallest value was found in spring. The reason is explained as emissions of local sources and atmospheric transport. The precipitation of column water vapor has a largely variation even in one day, the smallest precipitation appeared in winter, the biggest value was found in hot summer, seasonal variation could be as large as 40 times.

Paper Details

Date Published: 18 August 1998
PDF: 8 pages
Proc. SPIE 3501, Optical Remote Sensing of the Atmosphere and Clouds, (18 August 1998); doi: 10.1117/12.317732
Show Author Affiliations
Heli Wei, Anhui Institute of Optics and Fine Mechanics (China)
Qinghong Liu, Anhui Institute of Optics and Fine Mechanics (China)
Qingshan Xu, Anhui Institute of Optics and Fine Mechanics (China)
Fengsheng Zhao, Anhui Institute of Optics and Fine Mechanics (China)
Zhengfang Song, Anhui Institute of Optics and Fine Mechanics (China)

Published in SPIE Proceedings Vol. 3501:
Optical Remote Sensing of the Atmosphere and Clouds
Jinxue Wang; Beiying Wu; Toshihiro Ogawa; Zheng-hua Guan, Editor(s)

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