Caio Alencar de Matos¹, Eduardo Landulfo¹, Walter Morinobu Nakaema¹, Sandro Toshio Uehara¹, Patricia Sawamura¹, Ani Sobral Torres¹

¹Instituto de Pesquisas Energéticas e Nucleares

A backscattering Lidar system in the city of São Paulo (23º33’S, 46º44’W), which provides a vertical profile of the aerosol backscatter coefficient at 532nm, has been used to determine the height of the mixed layer. The Mixed Layer (ML) is the lowest layer of the PBL during the day. On its top of the ML there is a thermal inversion which difficult the dissipation of the pollution. It is of great importance to know the height of this layer, and the evolution during the day. It was developed four methods to make the determination of the ML heights, taking the range-corrected Lidar signal with appropriate background subtraction. The methods used were the visual, derivative where the lower derivative of the signal is the mixed layer height, logarithm which is similar with the derivative, but first was calculated the logarithm of the signal, and the ideal function method, that is finding a best fit to an idealized function. Until now the most reliable method is the logarithm, however the ideal function method still has to be adapted in the LabView platform and implemented in the Mathematica Software Tool.