Daily evolution of atmospheric gas pollutants vertical profile in a coastal mediterranean area

In this work we present a tomographic-like methodology for the retrieval of the vertical profile of nitrogen dioxide (NO₂) and ozone (O₃) in the boundary layer from ground based remote sensing measurements. A set of NO₂ and O₃ slant column densities at different elevation angles can be obtained with the Differential Optical Absorption Spectroscopy (DOAS) technique used in the multiple axis configuration. Measurements have been carried out in the Presidential Estate at Castel Porziano (Rome) using this technique, in the frame of a programme started in 1994 for studying and monitoring the Estate´s environment, in the period from September to November 2006. The retrieval of information on the vertical profile of a trace gas obtained from slant column density DOAS measurements requires: (1) the simulation of the radiative transfer in the atmosphere for Air Mass Factor (AMF) calculation concerning the target trace gases; (2) the application of inversion schemes to derive the vertical profile of the gas pollutants under interest using the AMF matrix as the kernel of the inversion algorithm. In this paper the first retrieved vertical profiles of NO₂ and O₃ and their time evolution during the day are presented and discussed.