The OASIS Observatory Using Ground-Based Solar Absorption Fourier-Transform Infrared Spectroscopy in the Suburbs of Paris (Créteil-France)

Ground-based Fourier-transform infrared (FTIR) solar absorption spectroscopy has led to a number of significant advances in our understanding of the atmosphere by providing information on the vertical distribution of various trace gases. Previously used to analyse solar absorption spectra measured at high-resolution in unpolluted sites, the retrieval code PROFFIT has been adapted to deal with spectra recorded at medium spectral resolution with a Bruker Optics Vertex 80 FTIR spectrometer. As one of the major instruments of the experimental observatory named OASIS (Observations of the Atmosphere by Solar Infrared Spectroscopy), this instrument is dedicated to the study of air composition in the suburbs of Paris. Accurate measurements of the most important atmospheric pollutants are indeed essential to improve the understanding and modelling of urban air pollution processes. Located in an urban region, OASIS enables to monitor key pollutants such as NOx, O3, CO and VOCs. In this chapter, 5 years intercomparison study with on-ground and satellite measurements for O3 and CO is reported, demonstrating the performances of a medium-resolution ground-based instrument and especially confirming its capability for tropospheric ozone monitoring.