资源环境科技发展态势分析平台

Results on day-to-night aerosol parameters retrieved from the Cimel 318CE-T photometer, operating at Lecce_University (40°20′N, 18°6′E) since October 2016, are reported. The paper aims to contribute either to the studies on the 318CE-T capability for monitoring aerosols in a wide range of moon's illumination and cycles and to the studies on day-to-night columnar aerosol properties by sun-sky-lunar photometry. The reliability of lunar AODs has firstly been evaluated by analysing the AOD differences calculated from the average of the last 1 h of daytime data (AOD_SS) and the first 1 h of nocturnal data (AOD_MR), respectively. Similarly, AOD_MS and AOD_SR values have been calculated from the average of the last 1 h of nocturnal data and the first 1 h of daytime data, respectively. We found that the AOD differences (AOD_SS – AOD_MR) and (AOD_MS – AOD_SR) were within the accuracy of solar AODs. Pairwise comparison, correlation coefficients, root mean square errors, and mean bias of AOD_SS versus AOD_MR and AOD_MS versus AOD_SR also supported the lunar data reliability. The statistical analysis of solar and corresponding lunar daily means has shown that monthly and seasonal AODs from solar and lunar photometry measurements, respectively, are characterized by similar metrics. Monthly and seasonal Ångström exponents (Å) calculated at the 440–870 nm wavelength pair from daily solar and lunar AODs are also characterized by similar metrics. More specifically, pairwise comparisons by the Mann-Whitney test have shown that lunar and solar AOD and Å datasets, based on daily means, are not significantly different in all the months and the seasons at the p-level < 0.02. On the contrary, pairwise comparisons have shown that the Ångström differences (ΔÅ) calculated from solar and lunar Å daily means are statistically different mainly in winter and autumn, likely for the high relative humidity at night-time. Therefore, ΔÅ has been the only intensive parameter characterized by significant day-to-night changes in autumn and winter, according to the measurement dataset of this paper. Some case studies have been analysed/discussed to support the paper's main results and show the seasonal changes of the aerosol properties.