Remotely operable compact instruments for measuring atmospheric CO<sub>2</sub> and CH<sub>4</sub> column densities at surface monitoring sites
Remotely operable compact instruments for measuring atmospheric CO<sub>2</sub> and CH<sub>4</sub> column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA) with a resolution enough to resolve rotational l...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2010-08-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/3/1103/2010/amt-3-1103-2010.pdf |
| Summary: | Remotely operable compact instruments for measuring atmospheric CO<sub>2</sub> and CH<sub>4</sub> column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA) with a resolution enough to resolve rotational lines of CO<sub>2</sub> and CH<sub>4</sub> in the regions of 1565–1585 and 1674–1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI) to obtain the CO<sub>2</sub> column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO<sub>2</sub> and CH<sub>4</sub> column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570–1575 nm were analyzed by the FFPI. The <i>I</i><sub>0</sub> and <i>I</i> values in the Beer-Lambert law equation to obtain CO<sub>2</sub> column density were deduced by modulating temperature of the FFPI, which offered column CO<sub>2</sub> with the statistical error less than 0.2% for six hours measurement. |
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| ISSN: | 1867-1381 1867-8548 |