In situ Measurement of H2O and CH4 with Telecommunication Laser Diodes in the Lower Stratosphere: Dehydration and Indication of a Tropical Air Intrusion at Mid-Latitudes |
| |
| Authors: | Georges Durry Alain Hauchecorne Joelle Ovarlez Henri Ovarlez Ivan Pouchet Virginie Zeninari Bertrand Parvitte |
| |
| Institution: | (1) Service d'Aéronomie, Institut Pierre-Simon-Laplace (IPSL), UMR 7620, B.P.3, F-91371 Verrières-le-Buisson Cédex, France;(2) Laboratoire de Météorologie Dynamique, UMR 8539, Ecole Polytechnique, F-91128 Palaiseau, Cédex, France;(3) Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR 6089, Université de Reims-Champagne-Ardenne, F-51687 Reims, Cédex, France |
| |
| Abstract: | Telecommunication laser diodes emitting near 1.39  m and 1.65 m in combination with direct-differential absorption spectroscopy are efficient tools to monitor in situ stratospheric H2O andCH4 with a good precision error (a few percents), a high temporal resolution (ranging from 10 ms to 1 s), a large dynamic range in the concentration measurements (four orders of magnitude) and a high selectivity in the analyte species. To illustrate the capability of laser probing technique, we report balloonborne H2Oand CH4 simultaneous measurements obtained on October 2001 atmidlatitudes (43° N). The H2O vertical profile achieved with the lasersensor in the lower stratosphere is compared with the H2O data yielded by a balloonborne frost-point hygrometer. The total hydrogen mixing ratio in the lower stratosphere, 2CH4] + H2O], appears to beconstant at 7.5 ± 0.1 ppmv. Nevertheless, an unexpected largedehydration of  0.5 ppmv was detected by both the laser sensor and thehygrometer between 16 km and 23 km. We suspect the occurrence of a tropicalair intrusion into mid-latitudes. We support this interpretation using a high-resolution advection model for potential vorticity. |
| |
| Keywords: | analytical method balloon diode laser field measurements methane water vapor stratosphere |
| 本文献已被 SpringerLink 等数据库收录！ |
|
