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- Kilbo Edlund, Karl, et al.
(författare)
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High-resolution dispersion modelling of PM2.5, PM10, NOx and NO2 exposure in metropolitan areas in Sweden 2000‒2018 – large health gains due to decreased population exposure
- 2024
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Ingår i: Air Quality, Atmosphere and Health. - 1873-9318 .- 1873-9326.
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Tidskriftsartikel (refereegranskat)abstract
- Ambient air pollution remains the major environmental cause of disease. Accurate assessment of population exposure and small-scale spatial exposure variations over long time periods is essential for epidemiological studies. We estimated annual exposure to fine and coarse particulate matter (PM2.5, PM10), and nitrogen oxides (NOx, NO2) with high spatial resolution to examine time trends 2000‒2018, compliance with the WHO Air Quality Guidelines, and assess the health impact. The modelling area covered six metropolitan areas in Sweden with a combined population of 5.5 million. Long-range transported air pollutants were modelled using a chemical transport model with bias correction, and locally emitted air pollutants using source-specific Gaussian-type dispersion models at resolutions up to 50 × 50m. The modelled concentrations were validated using quality-controlled monitoring data. Lastly, we estimated the reduction in mortality associated with the decrease in population exposure. The validity of modelled air pollutant concentrations was good (R2 for PM2.5 0.84, PM10 0.61, and NOx 0.87). Air pollution exposure decreased substantially, from a population weighted mean exposure to PM2.5 of 12.2µgm−3 in 2000 to 5.4µgm−3 in 2018. We estimated that the decreased exposure was associated with a reduction of 2719 (95% CI 2046–3055) premature deaths annually. However, in 2018, 65%, 8%, and 42% of residents in the modelled areas were still exposed to PM2.5, PM10, or NO2 levels, respectively, that exceeded the current WHO Air Quality Guidelines for annual average exposure. This emphasises the potential public health benefits of reductions in air pollution emissions.
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| 2. |
- Lindvall, Jenny, 1981-
(författare)
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The Representation of Atmospheric Boundary Layer Processes in Global Climate Models
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The atmospheric boundary layer is the lowest part of the atmosphere, which is in direct contact with the surface. It is here, in this turbulent layer, that the exchange of heat, moisture and momentum between the surface and the atmosphere takes place. This thesis examines how well the boundary layer is described in global climate models with particular focus on the representation of the diurnal cycle. Two versions of the Community Atmosphere Model (CAM) that employ different turbulence parameterizations are evaluated in the same model framework. It is found that both overestimate the amplitude of the diurnal cycles of near-surface variables compared to observations from flux tower sites. The 10-m wind is much lower in CAM5 than in CAM4 due to the Turbulent Mountain Stress (TMS) parameterization of subgrid orography in CAM5. Additionally, the diurnal temperature range (DTR) is studied in a large set of models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The model discrepancies are large both in simulations of the present day and in projections of the future. A correlative approach is used to assess which parameters are important for the model differences in DTR. No single parameter is found to be responsible, but clouds play an important role in all seasons and so do the evaporative fraction in summer. The diurnal cycles of these CMIP5 models are also evaluated against flux tower observations. The diurnal cycle of temperature is well captured, while most variables show a large inter-model spread. A subset of the models are analyzed deeper regarding their vertical boundary layer structure for a flux site in Oklahoma. A substantial warm summer bias is revealed in the models. Finally, the impact of TMS and changes in the vertical diffusion in CAM5 is studied. It is found that, although the inclusion of TMS leads to an improved large-scale circulation, the wind turning becomes too strong, which adds to the overestimation of the ageostrophic flow in the boundary layer. Instead, increasing the diffusivity in stable conditions tends to both degrade the large-scale circulation and cause an underestimated wind turning in the boundary layer.
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