title: SPIRALE: a multispecies in situ balloonborne instrument with six tunable diode laser spectrometers.
abstract: 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.
authors.affiliation: Laboratoire de Physique et Chimie de l'Environnement, Unité Mixte Recherche 6115, CNRS-Université d'Orléans, 3A Avenue de la Recherche Scientifique, 45071 Orleans, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Moreau
authors.forename: Claude
authors.initials: C
authors.lastname: Robert
authors.forename: Valéry
authors.initials: V
authors.lastname: Catoire
authors.forename: Michel
authors.initials: M
authors.lastname: Chartier
authors.forename: Claude
authors.initials: C
authors.lastname: Camy-Peyret
authors.forename: Nathalie
authors.initials: N
authors.lastname: Huret
authors.forename: Michel
authors.initials: M
authors.lastname: Pirre
authors.forename: Luc
authors.initials: L
authors.lastname: Pomathiod
authors.forename: Gilles
authors.initials: G
authors.lastname: Chalumeau