Durry G, Megie G
Institut Pierre-Simon-Laplace, Service d'Aéronomie, Centre National de la Recherche Scientifique, B.P. 3, 91371 Verrières-le-Buisson Cedex, France.
Appl Opt. 2000 Oct 20;39(30):5601-8. doi: 10.1364/ao.39.005601.
A distributed-feedback InGaAs laser diode emitting near 1.393 microm is used in conjunction with an optical multipass cell that is open to the atmosphere to yield ambient water-vapor measurements by infrared absorption spectroscopy. To obtain the high dynamic range for the measurements that is required for continuous water-vapor monitoring in the upper troposphere and the lower stratosphere, we used a simple circuit that combined differential and direct detection. Furthermore, the laser emission wavelength was tuned to balance the steep decrease in H2O concentration with altitude by sweeping molecular transitions of stronger line strengths. The technique was implemented by use of the Spectromètre à Diodes Laser Accordables (SDLA), a tunable diode laser spectrometer operated from a stratospheric balloon. Absorption spectra of H2O in the 5-30-km altitude range obtained at 1-s intervals during recent balloon flights are reported. Water-vapor mixing ratios were retrieved from the absorption spectra by a fit to the full molecular line shape in conjunction with in situ pressure and temperature measurements, with a precision error ranging from 5% to 10%.
一个发射波长接近1.393微米的分布反馈式铟镓砷激光二极管与一个向大气开放的光学多程池配合使用，通过红外吸收光谱法进行环境水汽测量。为了获得对流层上部和平流层下部连续水汽监测所需的高测量动态范围，我们使用了一个结合差分检测和直接检测的简单电路。此外，通过扫描具有较强谱线强度的分子跃迁，调整激光发射波长，以平衡H2O浓度随高度的急剧下降。该技术通过可调节二极管激光光谱仪（SDLA）实现，这是一种从平流层气球上操作的可调谐二极管激光光谱仪。报告了在最近的气球飞行期间以1秒间隔获得的5至30公里高度范围内H2O的吸收光谱。通过结合原位压力和温度测量对全分子线形进行拟合，从吸收光谱中反演出水汽混合比，精度误差范围为5%至10%。
