Atmospheric aerosol optical properties and their relation to other aerosol chemical-physical properties are key factors to understanding the influence on climate change, air quality and the consequent impact on human health. In this work we present the results of the four-years (2015-2018) data-analysis of aerosols extensive properties such as Scattering Ångstrom Exponent (SAE), Single Scattering Albedo (SSA), asymmetry parameter (g), as well as meteorological observations and equivalent black carbon mass concentration (eBC). They were measured at three GAW regional observatories (Donateo et al, 2018) in the South of Italy: ECO (Lecce), LMT (Lamezia Terme) and CGR (Capo Granitola). Aerosol scattering (?sc) and backscattering (?bsc) coefficients were measured by using a nephelometer (model 3563, TSI Inc., St. Paul, MN, USA), operating at three wavelengths (450 nm, 550 nm, and 700 nm) with a temporal resolution of 1 min (Anderson et al, 1996). The aerosol absorption coefficient at 635 nm was measured with Thermo Scientific(TM) 5012 Multi-Angle Absorption Photometer (MAAP) (Petzold et al, 2005). From the mean values of SAE450_700 (1.73 ECO, 1.93 LMT) and SSA (0.81 ECO, 0.78 LMT) observations can be argued that ECO and LMT are mainly influenced by ultrafine particles, while CGR, with mean values of SAE and SSA of 1.15 and 0.87, respectively, is characterized by natural sources, mainly marine. In all stations, g550 is very similar, 0.68 at CGR and 0.63 at LMT, with the greatest value (0.70) at ECO. In general, the scattering coefficients show higher values compared to data observed in northern European sites. SAE presents lower values respect to East and Central Europe, especially at CGR, due to the influence of Saharan dust and sea salt particles. In order to analyse the behaviour of the aerosols optical properties in the cold and warm season in the three observatories, two different datasets have been considered for each observatory: cold (from October to March) and warm period (from April to September). As expected, three observatories exhibited low values of SSA, during the cold season, 0.87 at CGR, 0.78 at LMT and 0.80 at ECO, which confirm an increment of industrial/traffic and wood combustion contributions. SSA values are very similar in warm and cold period, especially in the middle part of the day. The daily pattern for eBC concentration and SSA at ECO and LMT was essentially influenced by local activities, namely due to vehicular traffic while wood burning was the main source contributed to eBC concentration in the remote site of CGR. The meteorological conditions influence the aerosol optical properties at the three stations as observed by bivariate statistical analysis of eBC, SAE450_700, SSA, b, and g respect to wind velocity and direction. All our results show a negative radiative forcing of aerosols, with mean values of -58.8 at CGR, -45.4 at LMT and -55.9 at ECO.
Characterization of the aerosol optical properties at three GAW regional sites in the South of Italy
Donateo A;TLo Feudo;CRCalidonna;DContini;
2020
Abstract
Atmospheric aerosol optical properties and their relation to other aerosol chemical-physical properties are key factors to understanding the influence on climate change, air quality and the consequent impact on human health. In this work we present the results of the four-years (2015-2018) data-analysis of aerosols extensive properties such as Scattering Ångstrom Exponent (SAE), Single Scattering Albedo (SSA), asymmetry parameter (g), as well as meteorological observations and equivalent black carbon mass concentration (eBC). They were measured at three GAW regional observatories (Donateo et al, 2018) in the South of Italy: ECO (Lecce), LMT (Lamezia Terme) and CGR (Capo Granitola). Aerosol scattering (?sc) and backscattering (?bsc) coefficients were measured by using a nephelometer (model 3563, TSI Inc., St. Paul, MN, USA), operating at three wavelengths (450 nm, 550 nm, and 700 nm) with a temporal resolution of 1 min (Anderson et al, 1996). The aerosol absorption coefficient at 635 nm was measured with Thermo Scientific(TM) 5012 Multi-Angle Absorption Photometer (MAAP) (Petzold et al, 2005). From the mean values of SAE450_700 (1.73 ECO, 1.93 LMT) and SSA (0.81 ECO, 0.78 LMT) observations can be argued that ECO and LMT are mainly influenced by ultrafine particles, while CGR, with mean values of SAE and SSA of 1.15 and 0.87, respectively, is characterized by natural sources, mainly marine. In all stations, g550 is very similar, 0.68 at CGR and 0.63 at LMT, with the greatest value (0.70) at ECO. In general, the scattering coefficients show higher values compared to data observed in northern European sites. SAE presents lower values respect to East and Central Europe, especially at CGR, due to the influence of Saharan dust and sea salt particles. In order to analyse the behaviour of the aerosols optical properties in the cold and warm season in the three observatories, two different datasets have been considered for each observatory: cold (from October to March) and warm period (from April to September). As expected, three observatories exhibited low values of SSA, during the cold season, 0.87 at CGR, 0.78 at LMT and 0.80 at ECO, which confirm an increment of industrial/traffic and wood combustion contributions. SSA values are very similar in warm and cold period, especially in the middle part of the day. The daily pattern for eBC concentration and SSA at ECO and LMT was essentially influenced by local activities, namely due to vehicular traffic while wood burning was the main source contributed to eBC concentration in the remote site of CGR. The meteorological conditions influence the aerosol optical properties at the three stations as observed by bivariate statistical analysis of eBC, SAE450_700, SSA, b, and g respect to wind velocity and direction. All our results show a negative radiative forcing of aerosols, with mean values of -58.8 at CGR, -45.4 at LMT and -55.9 at ECO.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
