Thesis of Marie-thérèse El Kattar

Amphithéâtre Pierre Glorieux (CERLA) Thesis defense of Marie-thérèse El Kattar - laboratory LOA Abstract : To quantify the influence of human activities on the evolution of atmospheric composition, accurate and continuous measurements are essential. Ground-based high-spectral-resolution infrared measurements are an efficient way to obtain accurate tropospheric abundances of different gaseous species, in particular greenhouse gases (GHGs) such as CO2 and CH4. Many ground-based spectrometers are used in the NDACC and TCCON networks to validate the Level 2 satellite data, but their large dimensions and heavy mass make them inadequate for field campaigns. To overcome this drawback, the use of portable spectrometers was recently investigated. In this context, the work of this thesis consisted in characterizing the instrumental prototype CHRIS (Compact High-Spectral-Resolution Infrared Spectrometer). This instrument has unique characteristics such as its high spectral resolution (0.135 cm-1 non-apodized) and its wide spectral range (680 to 5200 cm-1). Its main objective is the characterization of gases and aerosols in the thermal and shortwave infrared regions. Therefore, it requires high radiometric precision and accuracy, which are obtained by performing spectral and radiometric calibrations as well as the characterization of its instrumental line shape. Furthermore, CHRIS’s capabilities to retrieve vertical CO2 and CH4 profiles are presented through a complete information content analysis, a channel selection and an error budget estimation in the attempt to join ongoing campaigns such as MAGIC (Monitoring of Atmospheric composition and Greenhouse gases through multi-Instruments Campaigns) to monitor GHGs and validate the actual and future space missions such as IASI-NG and Microcarb.