# First Lidar Campaign in the Industrial Sites of Volta Redonda-RJ and Lorena-SP, Brazil
## 4 Data Retrieval and Results
### Volta Redonda and Lorena Campaigns  
The lidar data were collected in the Escola de Engenharia de Lorena (EEL) at Universidade de Sao Paulo-USP (22.4152\({}^{\circ}\)S and 45.1194\({}^{\circ}\)W, 524 m above sea level) and in the Escola de Engenharia Industrial Metalurgica de Volta Redonda-EEIMVR at Universidade Federal Fluminense-UFF (22.5160\({}^{\circ}\)S and 44.1046\({}^{\circ}\)W, 340 m above sea level). Figure 1b,c present the locations (red pins) where the lidar apparatus was placed during the Lorena and Volta Redonda campaigns. In Figure 1c, the yellow contour indicates the CSN area. The periods of data collection were from 31 May until 24 July 2014, in Lorena, and from 6 November until 9 December 2018, in Volta Redonda. In the latter campaign, the weather was rainy and only measurements performed from 4 December 17:10 until 5 December 6:20 local time were selected to be presented in this paper. The lidar system was the only single remote sensing instrument employed during the measurement campaigns in Volta Redonda and Lorena. Considering a small underestimation of CALIOP lidar ratio values of \(1.4\%\pm 8.0\%\) for polluted continental aerosol type and \(-7.3\%\pm 13.0\%\) for polluted dust reported in [65], we used the CALIOP data products as reference to constrain the lidar ratio value in order to retrieve the backscatter profiles. Based on the mean lidar ratio values obtained from the boxplot analysis (Figures 3 and 4) and the aerosol classification frequency presented in Figure 5, a fixed lidar ratio value of \(L_{aer}=55\pm 22\) sr was used in order to retrieve the backscatter aerosol profiles for both campaigns. We first report on the results related to the Lorena campaign. Due to the very dry period in the 2014 Southern Hemisphere winter, the low frequency of rain provided several good quality measurements. The aerosol backscatter profiles corresponding to three representative days measured in bins of 100 s are presented in Figure 6. They were obtained by using the Klett inversion given by Equation (8). The background of the lidar measurement \(\mathcal{B}\mathcal{G}\) was determined by performing the linear fit described by Equation (5) considering an altitude range \(z\) from 6000 m to 7000 m a.g.l. On general, one can observe a large concentration of aerosols restricted to low altitudes, with aerosol boundary layer typically at \(z\lesssim 500\) m a.g.l., mainly at the beginning of the day. As the atmosphere is heated by the solar radiation the aerosols are dispersed with a consequent increase of the atmospheric layer, reaching a maximum of \(z\sim 1000\) m a.g.l. at \(\sim\)15:00 local time. While a clean atmosphere can be observed in the aerosol backscatter profiles corresponding to 13 June (panel a in Figure 6), those corresponding to 4 June (panel c) illustrate a day with \(\beta_{aer}\) reaching a high value of 0.004 km\({}^{-1}\) sr\({}^{-1}\). In particular, on 26 June (panel b), an aerosol layer at \(\sim\)3000 m a.g.l. can be observed at the beginning of the measurement. Besides that, a narrow region in altitude can also be observed in the end of the afternoon at \(\sim\)1000 m a.g.l. on 26 June and 1 July with smaller values of \(\beta_{aer}\) indicating intake of clear air. For the Lorena lidar campaign, the HYSPLIT trajectory model [53; 54] was employed to calculate the air mass backward trajectories and derive information from where, when and which altitude aerosol layers were transported. Five-day (120 h) back trajectories of air masses starting at the Lorena coordinates were calculated using the GDAS database from the Global Data Assimilation System for different altitudes ranging from 500 to 4000 m a.g.l. For this particular case, the back-trajectories started on the 26 June at 06:00 UTC with all plume altitude levels of 500, 1000, 2000, 3000 and 4000 m a.g.l. In this case it is clearly seen in Figure 7 that aerosol plumes come originally from the north and northwestern regions of Brazil, and the central portion of South America.