Guy Moreau,1
Claude Robert,1
Valéry Catoire,1
Michel Chartier,1
Claude Camy-Peyret,2
Nathalie Huret,1
Michel Pirre,1
Luc Pomathiod,1
and Gilles Chalumeau1
1G. Moreau, C. Robert, V. Catoire (Valery.Catoire@cnrs-orleans.fr), M. Chartier, N. Huret, M. Pirre, L. Pomathiod, and G. Chalumeau are with the Laboratoire de Physique et Chimie de l’Environnement (LPCE), Unité Mixte Recherche 6115, CNRS-Université d’Orléans, 3A Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France.
2Laboratoire de Physique Moléculaire pour l’Atmosphere et l’Astrophysique (LPMAA), Université Pierre et Marie Curie, 75252 Paris Cedex 05, France.
Guy Moreau, Claude Robert, Valéry Catoire, Michel Chartier, Claude Camy-Peyret, Nathalie Huret, Michel Pirre, Luc Pomathiod, and Gilles Chalumeau, "SPIRALE: a multispecies in situ balloonborne instrument with six tunable diode laser spectrometers," Appl. Opt. 44, 5972-5989 (2005)
The balloonborne SPIRALE (a French acronym for infrared absorption spectroscopy by tunable diode lasers) instrument has been developed for in situ measurements of several tracer and chemically active species in the stratosphere. Laser absorption takes place in an open Herriott multipass cell located under the balloon gondola, with six lead salt diode lasers as light sources. One mirror is located at the extremity of a deployable mast 3.5 m below the gondola, enabling the measurement of very low abundance species throughout a very long absorption path (up to 544 m). Three successful flights have produced concentration measurements of O3, CO, CO2, CH4, N2O, NO2, NO, HNO3, HCl, HOCl, COF2, and H2O2. Fast measurements (every 1.1 s) allow one to obtain a vertical resolution of 5 m for the profiles. A detection limit of a few tens of parts per trillion in volume has been demonstrated. Uncertainties of 3%–5% are estimated for the most abundant species rising to about 30% for the less abundant ones, mainly depending on the laser linewidth and the signal-to-noise ratio.
Wolfgang Gurlit, Rainer Zimmermann, Carsten Giesemann, Thomas Fernholz, Volker Ebert, Jürgen Wolfrum, Ulrich Platt, and John P. Burrows Appl. Opt. 44(1) 91-102 (2005)
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The absorption path length L is indicated.
For each laser, experimental absolute central microspectra wavenumbers
and wavenumber bandwidths Δ
are indicated.
Written in italics in the lower part of the boxes are the species contained in reference absorption cells whose lines provide absolute wavenumbers.
Table 2
Sensitivity Calculations on Concentration for Variations of Temperature T, Pressure P, Pressure-Broadening Coefficient γair, and Laser Linewidth Δvl at Low and High Pressures, Considering Two Laser Linewidths During a Concentration Retrieval (Concentration Variation Δc/c in Percent)
Parameter Variation
Laser Linewidth Δvl
Δc/c with ΔT = 0.5 K
Δc/c with ΔP = 0.1 hPa or 0.5 hPa
Δc/c with Δγair = 0.005 γair γair = 2 GHz
Δc/c with Δ (Δvl) = 0.1 Δvl
Total Retrieval Error (%)
Low P
Narrow (10 MHz)
0.45
0.8
0.2
0.5
1.1
Broad (70 MHz)
0.45
0.8
0.2
5.0
5.1
High P
Narrow (10 MHz)
0.75
0.8
1.6
0.1
2.0
Broad (70 MHz)
0.75
0.8
1.6
1.0
2.2
Note: The resulting precision on c (total retrieval error) is the square root of the quadratic sum of concentration variations (ΔP = 0.1 hPa at low P or 0.5 hPa at high P).
Table 3
Estimated Uncertainties (1σ of Gaussian Distribution) for Three SNR values (100, 10, and 1), Related to Absorption (Respectively, 10−2, 10−3, and 10−4), Considering the Random Sources of Errors
The absorption path length L is indicated.
For each laser, experimental absolute central microspectra wavenumbers
and wavenumber bandwidths Δ
are indicated.
Written in italics in the lower part of the boxes are the species contained in reference absorption cells whose lines provide absolute wavenumbers.
Table 2
Sensitivity Calculations on Concentration for Variations of Temperature T, Pressure P, Pressure-Broadening Coefficient γair, and Laser Linewidth Δvl at Low and High Pressures, Considering Two Laser Linewidths During a Concentration Retrieval (Concentration Variation Δc/c in Percent)
Parameter Variation
Laser Linewidth Δvl
Δc/c with ΔT = 0.5 K
Δc/c with ΔP = 0.1 hPa or 0.5 hPa
Δc/c with Δγair = 0.005 γair γair = 2 GHz
Δc/c with Δ (Δvl) = 0.1 Δvl
Total Retrieval Error (%)
Low P
Narrow (10 MHz)
0.45
0.8
0.2
0.5
1.1
Broad (70 MHz)
0.45
0.8
0.2
5.0
5.1
High P
Narrow (10 MHz)
0.75
0.8
1.6
0.1
2.0
Broad (70 MHz)
0.75
0.8
1.6
1.0
2.2
Note: The resulting precision on c (total retrieval error) is the square root of the quadratic sum of concentration variations (ΔP = 0.1 hPa at low P or 0.5 hPa at high P).
Table 3
Estimated Uncertainties (1σ of Gaussian Distribution) for Three SNR values (100, 10, and 1), Related to Absorption (Respectively, 10−2, 10−3, and 10−4), Considering the Random Sources of Errors