Departamento de Física
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Browsing Departamento de Física by Subject "Absorption"
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- Absorption Ångström exponents of aerosols and light absorbing carbon (LAC) obtained from in situ data in Covilhã, central PortugalPublication . Mogo, Sandra; Cachorro, Victoria; de Frutos, Ángel M; Rodrigues, A.A field campaign was conducted from October 2009 to July 2010 at Covilhã, a small town located in the region of Beira Interior (Portugal) in the interior of the Iberian Peninsula. The ambient light-absorption coefficient, σ(a) (522 nm), obtained from a Particle Soot Absorption Photometer (PSAP), presented a daily mean value of 12.1 Mm⁻¹ (StD = 7.3 Mm⁻¹). The wavelength dependence of aerosol light absorption is investigated through the Ångström parameter, α(a). The α(a) values for the pair of wavelengths 470-660 nm ranged from 0.86 to 1.47 during the period of measurements. The PSAP data were used to infer the mass of light absorbing carbon (LAC) and the daily mean varied from 0.1 to 6.8 μg m⁻³. A detailed study of special events with different aerosol characteristics is carried out and, to support data interpretation, air masses trajectory analysis is performed.
- Absorption coefficients of aerosols obtained from in situ data in Covilhã, central PortugalPublication . Mogo, Sandra; Cachorro, Victoria; De Frutos, Ángel MSince October 2009 an aerosol measurement data set was started at Covilhã, a small town located in the region of Beira Interior (Portugal) ain the interior a of the Iberian Peninsula. a Until July 2010, the ambient light-absorption coefficient, σ (470 nm), σ (522 nm) and σ (660 nm), presented a daily mean value of 14.2Mm-1 (StD=8.6Mm-1), 12.1Mm-1 (StD=7.3Mm-1) and 9.6Mm-1 (StD=5.7Mm-1), respectively. Monthly variations and daily cycle are presented in this work.
- Comparing surface measurement of black carbon and columnar AERONET inferred contents during the “El Arenosillo 2004 summer campaignPublication . Mogo, Sandra; Cachorro, Victoria; De Frutos, Ángel M; De La Rosa, Jesús D; Sorribas, MarDuring the summer of 2004 a field campaign was carried out at the El Arenosillo Atmospheric Sounding Station (ESAt), near Huelva, South-Western Spain. The campaign was designed to obtain experimental data on aerosol in situ absorption, size distribution, chemical composition, and columnar optical properties but this paper deals only with the evaluation of the absorbent aerosol. A Dekati cascade impactor and a PM10 Graseby-Andersen high volume sampler were used to collect aerosol fractions over filters. In this paper an estimation is made for the concentration of black carbon at ground level, using the absorption coefficients obtained from a filter transmission method. The values obtained are highly variable and range from 31 ng m-3 to 770 ng m-3. The high volume sampler filters were analyzed for elemental carbon with a thermal- optical method (LECO). The black carbon concentration is also compared with the columnar level retrieved from aerosol absorption optical depth derived from inversion of a sun-photometer data inside the AERONET framework.