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arXiv · 2012.12427

Open-path Dual-comb Spectroscopy for Multispecies Trace Gas Detection in the 4.5 {\mu}m to 5 {\mu}m Spectral Region

Fabrizio R. Giorgetta·Jeff Peischl·Daniel I. Herman·Gabriel Ycas·Ian Coddington·Nathan R. Newbury·Kevin C. Cossel
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Abstract

Open-path dual-comb spectroscopy provides multi-species atmospheric gas concentration measurements with high precision. Here, we extend open-path dual comb spectroscopy to the mid-infrared 5 {\mu}m atmospheric window, enabling atmospheric concentration retrievals of the primary greenhouse gases, N$_2$O, CO$_2$, and H$_2$O as well as the criterion air pollutants O$_3$ and CO across 600 m and 2 km round-trip paths. We demonstrate measurements over a five-day period at two-minute temporal resolution with 80% uptime. The achieved precision is sufficient to resolve the atmospheric concentration variations of the multiple gas species; retrieved dry mixing ratios of CO and N$_2$O are in good agreement with a co-located point sensor. In addition, the retrieved ratio of excess CO vs CO$_2$ agrees with similar urban studies but disagrees with the US National Emission Inventory by a factor of 3. Our retrieved ratio of excess N$_2$O vs CO$_2$ exhibits a plume-dependent value, indicating the variability of sources of the greenhouse gas N$_2$O.

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Fabrizio R. Giorgetta, Jeff Peischl, Daniel I. Herman, Gabriel Ycas, Ian Coddington, Nathan R. Newbury, Kevin C. Cossel. 2020-12-23. Open-path Dual-comb Spectroscopy for Multispecies Trace Gas Detection in the 4.5 {\mu}m to 5 {\mu}m Spectral Region. https://arxiv.org/abs/2012.12427

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