Greenhouse gas measurements over a 144 km open path in the Canary Islands

Brooke, J. S. A.; Bernath, P. F.; Kirchengast, G.; Thomas, C. B.; Wang, J.-G.; Tereszchuk, K. A.; González Abad, G.; Hargreaves, R. J.; Beale, C. A.; Harrison, J. J.; Schweitzer, S.; Proschek, V.; Martin, P. A.; Kasyutich, V. L.; Gerbig, C.; Kolle, O.; Loescher, A.

A new technique for the satellite remote sensing of greenhouse gases in the atmosphere via the absorption of short-wave infrared laser signals transmitted between counter-rotating satellites in low Earth orbit has recently been proposed; this would enable the acquisition of a long-term, stable, global set of altitude-resolved concentration measurements. We present the first ground-based experimental demonstration of this new infrared-laser occultation method, in which the atmospheric absorption of CO 2 near 2.1 μm was measured over a ~144 km path length between two peaks in the Canary Islands (at an altitude of ~2.4 km), using relatively low power diode lasers (~4 to 10 mW). The retrieved CO 2 volume mixing ratio of 400 ppm (±15 ppm) is consistent within experimental uncertainty with simultaneously recorded in situ validation measurements. We conclude that the new method has a sound basis for monitoring CO 2 in the free atmosphere; other greenhouse gases such as methane, nitrous oxide and water vapour can be monitored in the same way.



Brooke, J. S. A. / Bernath, P. F. / Kirchengast, G. / et al: Greenhouse gas measurements over a 144 km open path in the Canary Islands. 2012. Copernicus Publications.


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