1,721,008 research outputs found
Correlation between ground-based aerosol optical depth and TOMS aerosol index: a comparison between measurements and MODTRAN simulations
No full textA comparison between simulated data and measurements performed by means of a spectroradiometer has been done. We searched a correlation between Aerosol Optical Depth, measured the over a wide spectral range, and TOMS Aerosol Index, which is satellite retrieved. This comparison has been done for both desertic aerosol (measurements taken in Namibia, 1998) and rural aerosol (measurements realized in Southern Italy, 2000 and 2001). At the same time, the simulation code MODTRAN has been used, in order to obtain both synthetic Aerosol Optical Depth and Aerosol Index. Finally, we compared measured and simulated correlation, finding, a good agreement for desertic aerosol
Rivelazione di BC, BrC e OC mediante etalometro AE31 in siti caratterizzati da differenti emissioni
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Aerosol characterization in a semi-rural site in South-Italyby combined in-situ and ground-based remote sensingmeasurements
No full textHigh resolution radiometric together with in-situ gravimetric and aethalometer
measurements have been performed in a semi-rural site in Southwest Italy (Tito Scalo,
40° 35’ N, 15° 41’ E, 750m a.s.l) to derive aerosols optical and physical properties. The
measurement site is located in the Mediterranean area and this condition allows to
monitor aerosol properties variation due to the influence of air masses with different
origin. In particular, dust particles from Saharan desert could be present together with
polluted and smoke aerosol mainly from Central and Eastern Europe. Moreover marine
particles are an almost constant component both from the Mediterranean itself and from
the Atlantic Ocean. Some anthropogenic local sources impact the site, such as few little
plants and a main road. Columnar properties have been inferred by a high resolution
(1.5 nm) spectroradiometer Ocean Optics (400nm-800nm) to derive Aerosol Optical
Depths (AODs), Ångström turbidity parameters and size distributions, while daily
mass size distributions at the ground have been obtained by a 13 stages impactor.
Finally, Black Carbon (BC) concentrations have been measured during the campaign
by using an aethalometer and, combining all these measurements, it has been possible to
obtain a closure between aerosol optical and physical properties
Black Carbon and Organic Components in the Atmosphere of Southern Italy: Comparing Emissions from Different Sources and Production Processes of Carbonaceous Particles
Full text linkInitial measurements of black carbon (BC) content at both 880 and 370 nm, obtained in two sites in southern Italy by an aethalometer, have been analyzed. The sites are located in the same region (Basilicata), but are affected by different emission sources. In one case the main source of BC is related to vehicular traffic from a nearby freeway. Data were collected, although not continuously, during 2008, 2009 and 2010. In the second case, a fresh crude-oil pre-treatment plant continuously burns petroleum-derived products, thus contributing to emissions of both carbonaceous matter and its organic component. The corresponding data-set was collected in the period January–April 2011. At the first site, two daily peaks were found for the BC content, typical of vehicles emissions, with maximum values ranging from 2000 ng/m3 to 4700 ng/m3 found during weekdays. This behavior disappears at the weekend or when polluted air-masses from north-east Europe are transported over the measurement site. At the second site, two daily peaks were never found, suggesting that crude oil chemical processes were the main source of the emissions. In this case, the maximum BC values ranged between 1000–8000 ng/m3, depending on the processes occurring at the fresh crude-oil pre-treatment plant. Moreover, the estimated level of BC at 370 nm was higher than that of BC at 880 nm in all months, expect for April, indicating a clear organic component in atmospheric aerosols. Finally, based on a best-fit procedure applied to the seven wavelengths’ absorption coefficients, aerosols with different spectroscopic properties have been detected at these two sites
Integrated measurements for aerosol properties detection in a rural site in South-Italy.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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