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Najdeno v: ključnih besedah
Ključne besede: black carbon, source apportionment, planetary boundary layer
Objavljeno: 02.11.2016; Ogledov: 4603; Prenosov: 0
Polno besedilo (53,39 KB)

Najdeno v: ključnih besedah
Ključne besede: black carbon, source apportionment, radon, planetary boundary layer, lidar
Objavljeno: 10.10.2017; Ogledov: 4362; Prenosov: 218
Polno besedilo (136,72 KB)

Najdeno v: ključnih besedah
Ključne besede: very high energy, CTA, extragalactic source
Objavljeno: 16.02.2018; Ogledov: 2675; Prenosov: 128
Polno besedilo (651,65 KB)

Opis: Four perfluorocarbon tracer dispersion experiments were carried out in central London, United Kingdom in 2004. These experiments were supplementary to the dispersion of air pollution and penetration into the local environment (DAPPLE) campaign and consisted of ground level releases, roof level releases and mobile releases; the latter are believed to be the first such experiments to be undertaken. A detailed description of the experiments including release, sampling, analysis and wind observations is given. The characteristics of dispersion from the fixed and mobile sources are discussed and contrasted, in particular, the decay in concentration levels away from the source location and the additional variability that results from the non-uniformity of vehicle speed.
Najdeno v: ključnih besedah
Povzetek najdenega: ...of dispersion from the fixed and mobile sources are discussed and contrasted, in particular, the...
Ključne besede: dapple, perfluorocarbon, tracer, mobile source
Objavljeno: 18.07.2019; Ogledov: 2189; Prenosov: 0
Polno besedilo (265,68 KB)

Opis: Delhi is one of the most polluted cities worldwide and a comprehensive understanding and deeper insight into the air pollution and its sources is of high importance. We report 5 months of highly time-resolved measurements of non-refractory PM2.5 and black carbon (BC). Additionally, source apportionment based on positive matrix factorization (PMF) of the organic aerosol (OA) fraction is presented. The highest pollution levels are observed during winter in December/January. During that time, also uniquely high chloride concentrations are measured, which are sometimes even the most dominant NR-species in the morning hours. With increasing temperature, the total PM2.5 concentration decreases steadily, whereas the chloride concentrations decrease sharply. The concentrations measured in May are roughly 6 times lower than in December/January. PMF analysis resolves two primary factors, namely hydrocarbon-like (traffic-related) OA (HOA) and solid fuel combustion OA (SFC-OA), and one or two secondary factors depending on the season. The uncertainties of the PMF analysis are assessed by combining the random a-value approach and the bootstrap resampling technique of the PMF input. The uncertainties for the resolved factors range from ±18% to ±19% for HOA, ±7% to ±19% for SFC-OA and ±6 % to ±11% for the OOAs. The average correlation of HOA with eBCtr is R2 = 0.40, while SFC-OA has a correlation of R2 = 0.78 with eBCsf. Anthracene (m/z 178) and pyrene (m/z 202) (PAHs) are mostly explained by SFC-OA and follow its diurnal trend (R2 = 0.98 and R2 = 0.97). The secondary oxygenated aerosols are dominant during daytime. The average contribution during the afternoon hours (1 pm–5 pm) is 59% to the total OA mass, with contributions up to 96% in May. In contrast, the primary sources are more important during nighttime: the mean nightly contribution (22 pm–3 am) to the total OA mass is 48%, with contributions up to 88% during some episodes in April.
Najdeno v: ključnih besedah
Ključne besede: New Delhi, PM2.5, Source apportionment, PMF
Objavljeno: 20.07.2020; Ogledov: 1757; Prenosov: 0
Polno besedilo (4,71 MB)