Columnar aerosol optical properties in the Po Valley, Italy, from MFRSR data

Mazzola, Mauro; Lanconelli, Christian; Lupi, Angelo; Busetto, Maurizio; Vitale, Vito; Tomasi, Claudio

doi:10.1029/2009jd013310

Cited by 32 publications

(27 citation statements)

References 59 publications

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“…7 for Avignon (<ÅE> = 1.43) and Ispra (<ÅE> = 1.51) over Western Europe were influenced by industrial, urban, and traffic pollutants, such as ammonium salts of sulphate and nitrate (González et al, 2000;Benkovitz et al, 1996;Kambezidis and Kaskaoutis, 2008;Mazzola et al, 2010). The seasonal variation ofÅE is small as the major source during the year is industrial pollutant.…”

Section: Western Europementioning

confidence: 99%

Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations

et al. 2012

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Abstract. Regular aerosol observations based on wellcalibrated instruments have led to a better understanding of the aerosol radiative budget on Earth. In recent years, these instruments have played an important role in the determination of the increase of anthropogenic aerosols by means of long-term studies. Only few investigations regarding longterm trends of aerosol optical characteristics (e.g. aerosol optical thickness (AOT) andÅngström exponent (ÅE)) have been derived from ground-based observations. This paper aims to derive and discuss linear trends of AOT (440, 675, 870, and 1020 nm) andÅE (440-870 nm) using AErosol RObotic NETwork (AERONET) level 2.0 spectral observations. Additionally, temporal trends of coarse-and fine-mode dominant AOTs (CdAOT and FdAOT) have been estimated by applying an aerosol classification based on accurateÅE andÅngström exponent difference (ÅED). In order to take into account the fact that cloud disturbance is having a significant influence on the trend analysis of aerosols, we introduce a weighted least squares regression depending on two weights: (1) monthly standard deviation (σ t ) and (2) number of observations per month (n t ).Temporal increase of FdAOTs (440 nm) prevails over newly industrializing countries in East Asia (weighted trends; +6.23 % yr −1 at Beijing) and active agricultural burning regions in South Africa (+1.89 % yr −1 at Mongu). On the other hand, insignificant or negative trends for FdAOTs are detected over Western Europe (+0.25 % yr −1 at Avignon and −2.29 % yr −1 at Ispra) and North America (−0.52 % yr −1 for GSFC and −0.01 % yr −1 at MD Science Center). Over desert regions, both increase and decrease of CdAOTs (+3.37 % yr −1 at Solar Village and −1.18 % yr −1 at Ouagadougou) are observed depending on meteorological conditions.

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Section: Western Europementioning

confidence: 99%

Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations

et al. 2012

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“…In other sites in the Western Mediterranean like Avignon, Ispra, Rome, Toulon and Lecce, AOD(440 nm) and α(440-870 nm) are larger than those obtained in Granada and in other more polluted sites in the Iberian Peninsula such as Valencia and Barcelona. This is because these cities (Avignon, Ispra, Rome, Toulon and Lecce) are urban areas with high local anthropogenic emissions and quite affected by highly polluted air-masses from Europe (e.g., Pace et al, 2006;Santese et al, 2008;Mazzola et al, 2010). In addition, they are also affected by Saharan dust intrusions (e.g., Perrone et al, 2005;Santese et al, 2008;Meloni et al, 2007;Pavese et al, 2009).…”

Section: Inter-comparison With Surrounding Aeronet Stationsmentioning

confidence: 99%

Columnar aerosol properties from sun-and-star photometry: statistical comparisons and day-to-night dynamic

et al. 2012

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Abstract. This work presents the first analysis of longterm correlative day-to-night columnar aerosol optical properties. The aim is to better understand columnar aerosol dynamic from ground-based observations, which are poorly studied until now. To this end we have used a combination of sun-and-star photometry measurements acquired in the city of Granada (37.16 • N, 3.60 • W, 680 m a.s.l.; South-East of Spain) from 2007 to 2010. For the whole study period, mean aerosol optical depth (AOD) around 440 nm (±standard deviation) is 0.18 ± 0.10 and 0.19 ± 0.11 for daytime and nighttime, respectively, while the mean Angström exponent (α) is 1.0 ± 0.4 and 0.9 ± 0.4 for daytime and nighttime. The ANOVA statistical tests reveal that there are no significant differences between AOD and α obtained at daytime and those at nighttime. Additionally, the mean daytime values of AOD and α obtained during this study period are coherent with the values obtained in the surrounding AERONET stations. On the other hand, AOD around 440 nm present evident seasonal patterns characterised by large values in summer (mean value of 0.20 ± 0.10 both at daytime and nighttime) and low values in winter (mean value of 0.15 ± 0.09 at daytime and 0.17 ± 0.10 at nighttime). The Angström exponents also present seasonal patterns, but with low values in summer (mean values of 0.8 ± 0.4 and 0.9 ± 0.4 at dayand night-time) and relatively large values in winter (mean values of 1.2 ± 0.4 and 1.0 ± 0.3 at daytime and nighttime). These seasonal patterns are explained by the differences in the meteorological conditions and by the differences in the strength of the aerosol sources. To take more insight about the changes in aerosol particles between day and night, the spectral differences of the Angström exponent as function of the Angström exponent are also studied. These analyses reveal increases of the fine mode radius and of the fine mode contribution to AOD during nighttime, being more remarkable in the summer seasons. These variations are explained by the changes of the local aerosol sources and by the meteorological conditions between daytime and nighttime, as well as aerosol aging processes. Case studies during summer and winter for different aerosol loads and types are also presented to clearly illustrate these findings.

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“…Although the study of Kaufman et al (2000) revealed that Terra and Aqua measurements can represent the annual average value within 2 % error, still, the incomplete temporal samplings of aerosol optical properties may be incapable of faithfully reproducing the diurnal variations of aerosol optical properties, especially for SSA and g. Therefore, the aerosol optical properties are usually assumed to be constants (Sena et al, 2013;Myhre, 2009) or with negligible variability through the day of interest (Remer and Kaufman, 2006). So far, significant diurnal changes of AOD have been frequently observed in many polluted regions around the world (Zhang et al, 2012;Mazzola et al, 2010;Smirnov et al, 2002), but diurnal changes of SSA and g for ambient aerosol are rarely investigated.…”

Section: Introductionmentioning

confidence: 99%

Diurnal variations of aerosol optical properties in the North China Plain and their influences on the estimates of direct aerosol radiative effect

et al. 2015

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Abstract. In this paper, the diurnal variations of aerosol optical properties and their influences on the estimation of daily average direct aerosol radiative effect (DARE) in the North China Plain (NCP) are investigated based on in situ measurements from Haze in China campaign. For ambient aerosol, the diurnal patterns of single scattering albedo (SSA) and asymmetry factor (g) in the NCP are both highest at dawn and lowest in the late afternoon, and quite different from those of dry-state aerosol. The relative humidity (RH) is the dominant factor which determines the diurnal pattern of SSA and g for ambient aerosol. Basing on the calculated SSA and g, several cases are designed to investigate the impacts of the diurnal changes of aerosol optical properties on DARE. The results demonstrate that the diurnal changes of SSA and g in the NCP have significant influences on the estimation of DARE at the top of the atmosphere (TOA). If the full temporal coverage of aerosol optical depth (AOD), SSA and g are available, an accurate estimation of daily average DARE can be achieved by using the daily averages of AOD, SSA and g. However, due to the lack of full temporal coverage data sets of SSA and g, their daily averages are usually not available. Basing on the results of designed cases, if the RH plays a dominant role in the diurnal variations of SSA and g, we suggest that using both SSA and g averaged over early morning and late afternoon as inputs for radiative transfer model to improve the accurate estimation of DARE. If the temporal samplings of SSA or g are too few to adopt this method, either averaged over early morning or late afternoon of both SSA and g can be used to improve the estimation of DARE at the TOA.

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Columnar aerosol optical properties in the Po Valley, Italy, from MFRSR data

Cited by 32 publications

References 59 publications

Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations

Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations

Columnar aerosol properties from sun-and-star photometry: statistical comparisons and day-to-night dynamic

Diurnal variations of aerosol optical properties in the North China Plain and their influences on the estimates of direct aerosol radiative effect

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