| 1. |
- Grundström, Maria, 1979, et al.
(author)
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Variation and co-variation of PM10, particle number concentration, NOx and NO2 in the urban air - Relationships with wind speed, vertical temperature gradient and weather type
- 2015
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In: Atmospheric Environment. - : Elsevier Ltd. - 1352-2310. ; 120, s. 317-327
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Journal article (peer-reviewed)abstract
- Atmospheric ultrafine particles (UFP; diameter < 0.1 μm) represent a growing global health concern in urban environments and has a strong link to traffic related emissions. UFP is usually the dominating fraction of atmospheric particle number concentrations (PNC) despite being a minor part of total particle mass. The aim of this study was to empirically investigate the relationship between PNC and other air pollutants (NOX, NO2 and PM10) in the urban environment and their dependence on meteorology and weather type, using the Lamb Weather Type (LWT) classification scheme. The study was carried out in Gothenburg, Sweden, at an urban background site during April 2007-May 2008. It was found that daily average [PNC] correlated very well with [NOx] (R2 = 0.73) during inversion days, to a lesser extent with [NO2] (R2 = 0.58) and poorly with [PM10] (R2 = 0.07). Both PNC and NOx had similar response patterns to wind speed and to the strength of temperature inversions. PNC displayed two regimes, one strongly correlated to NOx and a second poorly correlated to NOx which was characterised by high wind speed. For concentration averages based on LWTs, the PNC-[NOx] relationship remained strong (R2 = 0.70) where the windy LWT W deviated noticeably. Exclusion of observations with wind speed >5 ms-1 or ΔT < 0 °C from LWTs produced more uniform and stronger relationships (R2 = 0.90; R2 = 0.93). Low wind speeds and positive vertical temperature gradients were most common during LWTs A, NW, N and NE. These weather types were also associated with the highest daily means of NOx (~30 ppb) and PNC (~10 000 # cm-3). A conclusion from this study is that NOx (but not PM10) is a good proxy for PNC especially during calm and stable conditions and that LWTs A, NW, N and NE are high risk weather types for elevated NOx and PNC. © 2015.
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| 2. |
- Jung, M. I., et al.
(author)
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Contrasting synoptic weather patterns between non-dust high particulate matter events and Asian dust events in Seoul, South Korea
- 2019
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 214
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Journal article (peer-reviewed)abstract
- The serious degradation of regional air quality is a critical social issue in East Asia despite continuous efforts to reduce the emission of pollutants and their precursors. To better understand high-pollution events in this region, the synoptic weather patterns associated with springtime non-dust high PM10 (High PM10) events and Asian Dust events in Seoul, South Korea, are examined for the 2001–2018 period. It is shown that the two high-pollution events accompany different atmospheric circulations. While High PM10 events are associated with weak surface cyclonic circulations over the Southeast China, Asian Dust events are characterized by strong cyclones over Northeast China. Composite weather maps show that mid-tropospheric circulation anomalies are exactly the opposite between the two events with anticyclonic anomalies over the Korean Peninsula for High PM10 events but cyclonic anomalies for Asian Dust events. The cluster analyses further reveal that High PM10 events are not determined by a single dominant weather pattern. They are associated with surface cyclonic circulations from southeastern China to the Sea of Okhotsk, anticyclonic circulations around the Korean Peninsula or their mixtures. This result is in contrast with the Asian Dust events which are primarily driven by vertically well-organized continental cyclones. © 2019 Elsevier Ltd
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| 3. |
- Klingberg, Jenny, 1978, et al.
(author)
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Variation in ozone exposure in the landscape of southern Sweden with consideration of topography and coastal climate
- 2012
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 47, s. 252-260
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Journal article (peer-reviewed)abstract
- Ozone concentrations ([O3]) and meteorological parameters were measured with a mobile monitoring station at two coastal and five inland sites in southwest Sweden. Three of the five inland sites were located topographically low and two high compared to the surrounding landscape. In addition, [O3] data from six permanent monitoring stations in southern Sweden were analysed in relation to the positions of the measurement sites in the landscape. [O3] was also measured with passive diffusion samplers at two other sites. Both the diurnal temperature range (DTR) and the diurnal [O3] range (DOR) were to a large extent explained by the strength of the nocturnal temperature inversions at the sites. To investigate the influence of topography, the relative altitude of the sites was defined as the average altitude within a 3 km radius subtracted from the altitude of the site. Statistically significant relationships were obtained for average [O3] as well as DOR with relative altitude. Inland low sites experienced stronger nocturnal temperature inversions, lower average [O3] and larger DOR compared to inland high and coastal sites. Relative altitude was found to be superior to site altitude in explaining the variation of average [O3] and DOR in the landscape. This study underlines the importance of including local topography, as well as vicinity to the coast, in modelling [O3] and in O3 environmental risk assessments.
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| 4. |
- Oh, H. R., et al.
(author)
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Long-range transport of air pollutants originating in China: A possible major cause of multi-day high-PM10 episodes during cold season in Seoul, Korea
- 2015
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 109, s. 23-30
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Journal article (peer-reviewed)abstract
- Massive air pollutants originating in China and their trans-boundary transports are an international concern in East Asia. Despite its importance, details in the trans-boundary transport of air pollutants over East Asia and its impact on regional air quality remain to be clarified. This study presents an evidence which strong support that aerosols emitting in China play a major role in the occurrence of multi-day (≥4 days) severe air pollution episodes in cold seasons (October through March) for 2001-2013 in Seoul, Korea, where the concentration of PM10 (particulates with diameters≤10μm) exceeds 100μgm-3. Observations show that these multi-day severe air pollution episodes occur when a strong high-pressure system resides over the eastern China-Korea region. In such weather conditions, air pollutants emitted in eastern China/southwestern Manchuria are trapped within the atmospheric boundary layer, and gradually spread into neighboring countries by weak lower tropospheric westerlies. Understanding of trans-boundary transports of air pollutants will advance the predictability of local air quality, and will encourage the development of international measures to improve air quality. © 2015 Elsevier Ltd.
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| 5. |
- Olofson, K. Frans G., 1976, et al.
(author)
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Urban aerosol evolution and particle formation during wintertime temperature inversions
- 2009
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 43, s. 340-346
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Journal article (peer-reviewed)abstract
- Aerosol temporal and spatial distributions during wintertime temperature inversions in Gothenburg, Sweden, have been characterized by ground-based and airborne particle measurements combined with lidar measurements. Ground inversions frequently developed during evenings and nights with stable cold conditions, and the low wintertime insolation often resulted in near neutral boundary layer conditions during day-time. Under these conditions ground level aerosol concentrations peaked during morning rush hours and often remained relatively high throughout the day due to inefficient ventilation. The particle number concentrations decreased slowly with increasing altitude within the boundary layer, and measurements slightly above the boundary layer suggested limited entrainment of polluted air into the free troposphere. High concentrations of ultrafine particles were observed throughout the boundary layer up to altitudes of 1100 m, which suggested that nucleation took place within the residual layer during the night and early morning. Recently formed particles were also observed around midday when the layer near ground was ventilated by mixing into the boundary layer, which indicated that ultrafine particles were either transported down from the residual layer to ground level or formed when the polluted surface layer mixed with the cleaner air above.
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| 6. |
- Pleijel, Håkan, 1958, et al.
(author)
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A method to assess the inter-annual weather-dependent variability in air pollution concentration and deposition based on weather typing
- 2016
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 126, s. 200-210
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Journal article (peer-reviewed)abstract
- Annual anomalies in air pollutant concentrations, and deposition (bulk and throughfall) of sulphate, nitrate and ammonium, in the Gothenburg region, south-west Sweden, were correlated with optimized linear combinations of the yearly frequency of Lamb Weather Types (LWTs) to determine the extent to which the year-to-year variation in pollution exposure can be partly explained by weather related variability. Air concentrations of urban NO2, CO, PM10, as well as O3 at both an urban and a rural monitoring site, and the deposition of sulphate, nitrate and ammonium for the period 1997–2010 were included in the analysis. Linear detrending of the time series was performed to estimate trend-independent anomalies. These estimated anomalies were subtracted from observed annual values. Then the statistical significance of temporal trends with and without LWT adjustment was tested. For the pollutants studied, the annual anomaly was well correlated with the annual LWT combination (R2 in the range 0.52–0.90). Some negative (annual average [NO2], ammonia bulk deposition) or positive (average urban [O3]) temporal trends became statistically significant (p < 0.05) when the LWT adjustment was applied. In all the cases but one (NH4 throughfall, for which no temporal trend existed) the significance of temporal trends became stronger with LWT adjustment. For nitrate and ammonium, the LWT based adjustment explained a larger fraction of the inter-annual variation for bulk deposition than for throughfall. This is probably linked to the longer time scale of canopy related dry deposition processes influencing throughfall being explained to a lesser extent by LWTs than the meteorological factors controlling bulk deposition. The proposed novel methodology can be used by authorities responsible for air pollution management, and by researchers studying temporal trends in pollution, to evaluate e.g. the relative importance of changes in emissions and weather variability in annual air pollution exposure.
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