资源环境科技发展态势分析平台

We present the analysis of four years of measurements by a CL51 ceilometer in Burjassot (39.51 N, 0.42 W), a research station in the western Mediterranean coast. The 1-min resolution profiles of the CL51 are corrected, calibrated, grouped and cloud-screened to create a 1-h resolution database of aerosol backscatter profiles at 910 nm (beta(a)) spanning from July 2013 to August 2017. A total of 21,247 beta(a) profiles are obtained, covering 58% of the considered period. The analysis of the beta(a) profiles as a function of the main aerosol in the atmosphere reveals that dust arrives at Burjassot mainly in the form of elevated layers, with a highest impact between 1 and 4 km. The beta(a) profiles obtained throughout the year show a strong seasonal trend: in summer we obtain, on average, the highest beta(a) coefficients distributed over a stratified profile; on the contrary, in winter the mean beta(a) coefficients have the lowest value and decrease exponentially with height. Our observations indicate that these seasonal changes are related to seasonal changes in the distribution of dust and to the wind direction at surface level. Regarding this last point we observe that conditions favoring aerosol re-circulation and thermal internal boundary layer lead to the highest beta(a) values and to the stratification of the aerosol profile. On the contrary, when these mechanisms are impeded we find lower beta(a) values and no aerosol layering. Finally, we observed that the beta(a) follows a daily cycle that varies depending on the season the wind regime.