Retrieval of Gas Pollutants Vertical Profile in the Boundary Layer by Means of Multiple-Axis DOAS

This paper presents a methodology for the retrieval of the vertical profile of atmospheric gas pollutants in the boundary layer from ground-based remote sensing measurements. Nitrogen dioxide (NO₂) and ozone (O₃) slant column amounts were obtained with the differential optical absorption spectroscopy (DOAS) technique used in the multiple-axis configuration (referred to as multiaxis DOAS). The measurements were carried out in the Presidential Estate at Castel Porziano (near Rome) from September to November 2006, within a program started in 1994 for studying and monitoring the Estate´s environment. The retrieval of information on trace gas vertical profiles from the slant column amounts requires as follows: (1) the simulation of the radiative transfer in the atmosphere for air mass factor calculation and (2) the application of inversion schemes. This paper illustrates and discusses the vertical profiles of NO₂ and O₃ obtained from multiaxis DOAS measurements and their daily evolution on October 29, 2006.