Abstract.
We describe a near-infrared in situ tunable diode laser spectrometer developed for atmospheric measurements of CH4 in the upper troposphere and lower stratosphere (UT/LS). The instrument is designed to provide fast-response (0.5–1 Hz) measurements and operate autonomously on the NASA WB-57F high-altitude aircraft. A single-mode InGaAsP distributed feedback laser diode operating at 1.6537 μm scans continuously over the R(3) rotation–vibration transition in the 2ν3 band. We use a direct absorption technique incorporating a custom-designed long path length (252 m) low-volume (3.6 L) astigmatic Herriott cell. The present detection sensitivity is 5×1010 molecules cm-3, corresponding to ∼20 ppbv in the UT/LS, with the main limit to instrument precision being background optical interference fringes. In-flight performance is demonstrated by presentation of recent data.
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Received: 25 January 2002 / Revised version: 5 April 2002 / Published online: 21 August 2002
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Richard, E., Kelly, K., Winkler, R. et al. A fast-response near-infrared tunable diode laser absorption spectrometer for in situ measurements of CH4 in the upper troposphere and lower stratosphere. Appl Phys B 75, 183–194 (2002). https://doi.org/10.1007/s00340-002-0935-3
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DOI: https://doi.org/10.1007/s00340-002-0935-3