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| Titel: |
Application of the Volatility-TDMA Technique to Determine the Number Size Distribution and Mass Concentration of Less Volatile Particles |
| Auteur: |
Frey, Anna Rose, Diana Wehner, Birgit Muller, Thomas Cheng, Yafang Wiedensohler, Alfred Virkkula, Aki |
| Verschenen in: |
Aerosol science and technology |
| Paginering: | Jaargang 42 (2008) nr. 10 pagina's 817-828 |
| Jaar: |
2008-10 |
| Inhoud: |
A Volatility-Tandem-Differential-Mobility-Analyzer (VTDMA) and a Differential Mobility Particle Sizer (DMPS) were used to determine the number and mass concentration of externally mixed aerosol particles in urban background air. In the VTDMA the less-volatile (LV) particle fraction was measured at 300°C for particles in the size range 20-250 nm. The LV particle fraction was converted to the number concentration of LV particles (NLV) and the mass concentration (MLV). MLV was compared with the mass concentration of black carbon (MBC) measured by a Multi-Angle Absorption Photometer (MAAP). The DMPS and VTDMA data were used for calculating scattering and absorption coefficients (σSP and σAP) with a Mie model and compared with σSP and σAP measured with a TSI nephelometer and the MAAP. The model was run by assuming external and internal mixing of absorbing and scattering aerosol. The best fit of measured and modeled σSP and σAP was sought by varying the refractive index. During periods dominated by local emissions LV particle fraction 〈ϕLV 〉 was high ( >0.2). In these cases, the MLV and the modeled σAP assuming external mixing agreed well with the measured MBC and σAP, respectively. For the long-range transported aerosol 〈ϕLV 〉 was small ( <0.1) and MBC was higher than MLV. For the whole period the average (± std) refractive index was 1.55 (± 0.09) - 0.04 (±0.02)i when internal mixing was assumed. When 〈ϕLV 〉 was >0.2 the average refractive index of LV particles was 1.96 - 0.8 (±0.18)i when σAP was modeled assuming external mixing. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 3 van 8 gevonden artikelen
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