| 1. |
- Song, Yanling, et al.
(författare)
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Rain-season trends in precipitation and their effect in different climate regions of China during 1961–2008
- 2011
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 6:3, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Using high-quality precipitation data from 524 stations, the trends of a set of precipitation variables during the main rain season (May–September) from 1961 to 2008 for different climate regions in China were analysed. However, different characteristics were displayed in different regions of China. In most temperate monsoon regions (north-eastern China), total rain-season precipitation and precipitation days showed decreasing trends; positive tendencies in precipitation intensity were, however, noted for most stations in this region. It is suggested that the decrease in rain-season precipitation is mainly related to there being fewer rain days and a change towards drier conditions in north-eastern China, and as a result, the available water resources have been negatively affected in the temperate monsoon regions. In most subtropical and tropical monsoon climate regions (south-eastern China), the rain-season precipitation and precipitation days (11–50, with > 50 mm) showed slightly positive trends. However, precipitation days with ≤ 10 mm decreased in these regions. Changes towards wetter conditions in this area, together with more frequent heavy rainfall events causing floods, have a severe impact on peoples' lives and socio-economic development. In general, the rain-season precipitation, precipitation days and rain-season precipitation intensity had all increased in the temperate continental and plateau/mountain regions of western China. This increase in rain-season precipitation has been favourable to pasture growth.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Achberger, Christine, 1968, et al.
(författare)
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State of the Climate in 2011
- 2012
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Ingår i: Bulletin of the American Meteorological Society. - 0003-0007. ; 93:7
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale climate patterns influenced temperature and weather patterns around the globe in 2011. In particular, a moderate-to-strong La Nina at the beginning of the year dissipated during boreal spring but reemerged during fall. The phenomenon contributed to historical droughts in East Africa, the southern United States, and northern Mexico, as well the wettest two-year period (2010-11) on record for Australia, particularly remarkable as this follows a decade-long dry period. Precipitation patterns in South America were also influenced by La Nina. Heavy rain in Rio de Janeiro in January triggered the country's worst floods and landslides in Brazil's history. The 2011 combined average temperature across global land and ocean surfaces was the coolest since 2008, but was also among the 15 warmest years on record and above the 1981-2010 average. The global sea surface temperature cooled by 0.1 degrees C from 2010 to 2011, associated with cooling influences of La Nina. Global integrals of upper ocean heat content for 2011 were higher than for all prior years, demonstrating the Earth's dominant role of the oceans in the Earth's energy budget. In the upper atmosphere, tropical stratospheric temperatures were anomalously warm, while polar temperatures were anomalously cold. This led to large springtime stratospheric ozone reductions in polar latitudes in both hemispheres. Ozone concentrations in the Arctic stratosphere during March were the lowest for that period since satellite records began in 1979. An extensive, deep, and persistent ozone hole over the Antarctic in September indicates that the recovery to pre-1980 conditions is proceeding very slowly. Atmospheric carbon dioxide concentrations increased by 2.10 ppm in 2011, and exceeded 390 ppm for the first time since instrumental records began. Other greenhouse gases also continued to rise in concentration and the combined effect now represents a 30% increase in radiative forcing over a 1990 baseline. Most ozone depleting substances continued to fall. The global net ocean carbon dioxide uptake for the 2010 transition period from El Nino to La Nina, the most recent period for which analyzed data are available, was estimated to be 1.30 Pg C yr(-1), almost 12% below the 29-year long-term average. Relative to the long-term trend, global sea level dropped noticeably in mid-2010 and reached a local minimum in 2011. The drop has been linked to the La Nina conditions that prevailed throughout much of 2010-11. Global sea level increased sharply during the second half of 2011. Global tropical cyclone activity during 2011 was well-below average, with a total of 74 storms compared with the 1981-2010 average of 89. Similar to 2010, the North Atlantic was the only basin that experienced above-normal activity. For the first year since the widespread introduction of the Dvorak intensity-estimation method in the 1980s, only three tropical cyclones reached Category 5 intensity level-all in the Northwest Pacific basin. The Arctic continued to warm at about twice the rate compared with lower latitudes. Below-normal summer snowfall, a decreasing trend in surface albedo, and above-average surface and upper air temperatures resulted in a continued pattern of extreme surface melting, and net snow and ice loss on the Greenland ice sheet. Warmer-than-normal temperatures over the Eurasian Arctic in spring resulted in a new record-low June snow cover extent and spring snow cover duration in this region. In the Canadian Arctic, the mass loss from glaciers and ice caps was the greatest since GRACE measurements began in 2002, continuing a negative trend that began in 1987. New record high temperatures occurred at 20 m below the land surface at all permafrost observatories on the North Slope of Alaska, where measurements began in the late 1970s. Arctic sea ice extent in September 2011 was the second-lowest on record, while the extent of old ice (four and five years) reached a new record minimum that was just 19% of normal. On the opposite pole, austral winter and spring temperatures were more than 3 degrees C above normal over much of the Antarctic continent. However, winter temperatures were below normal in the northern Antarctic Peninsula, which continued the downward trend there during the last 15 years. In summer, an all-time record high temperature of -12.3 degrees C was set at the South Pole station on 25 December, exceeding the previous record by more than a full degree. Antarctic sea ice extent anomalies increased steadily through much of the year, from briefly setting a record low in April, to well above average in December. The latter trend reflects the dispersive effects of low pressure on sea ice and the generally cool conditions around the Antarctic perimeter.
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| 6. |
- Achberger, Christine, 1968, et al.
(författare)
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The Nordic and Baltic Countries
- 2012
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Ingår i: Bulletin of The American Meteorological Society -. - 0003-0007 .- 1520-0477. ; 93:7
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Tidskriftsartikel (refereegranskat)
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Achberger, Christine, 1968, et al.
(författare)
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The surface winds of Sweden during 1999-2000
- 2006
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 26:2, s. 159-178
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Tidskriftsartikel (refereegranskat)abstract
- This study aims at increasing our understanding of the regional wind climate in Sweden. Spatial and temporal patterns of the surface winds are presented for the years 1999-2000. Annual mean wind speeds range between 2 and 5 m/s with high values at exposed mountainous sites and on islands off the coast. Combining wind speed and direction into mean wind velocities shows that flow conditions are stronger and more coherent in space in southern Sweden than in central and northern Sweden. The spatial scale, defined as the distance between stations when the correlation for wind speed drops to similar to 0.37, was determined by pairwise correlations between all possible station pairs. Scales range from 38 to 530 km for wind speed and from 40 to 830 km for wind direction depending on the region. They tend to be smaller in central and northern Sweden, where the more pronounced relief has a larger influence on the local wind conditions. The strength and the timing of the annual and diurnal wind speed cycle have been estimated for each station. Amplitudes of the annual cycle are greater at exposed sites and correlate generally well with annual mean wind speeds. Monthly mean wind speeds peak in winter in southern Sweden, but peak in other seasons in the remaining regions. In winter, weaker pressure gradients over northern Sweden and surface-near temperature inversions contribute to weaker surface winds. Diurnal cycles vary in strength between summer and winter. Compared to the last normal climate period (1961-1990), 1999-2000 is characterized by the increased occurrence of westerly and southerly geostrophic flow. Copyright (C) 2005 Royal Meteorological Society.
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| 11. |
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| 12. |
- Berghauser Pont, Meta, 1972, et al.
(författare)
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Using urban form to increase the capacity of cities to manage noise and air quality
- 2023
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Ingår i: Urban Morphology. - 1027-4278. ; 27:1, s. 51-70
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Tidskriftsartikel (refereegranskat)abstract
- The top two environmental factors adversely affecting human health in Europe are air and noise pollution, with road traffic being the largest source. Urban density plays an important role in reducing car traffic. However, the benefits of reduced emissions per capita can still mean higher emissions locally, because of the number of people in the area. Therefore, this paper investigates how morphological parameters influence the local distribution of noise and air pollution. A parametric approach, based on the Spacematrix method, is used to study the impact of morphological parameters on the distribution of air and noise pollution, controlling for traffic mode, flows and speed. To compare the impact of exposure to noise and air pollution, their respective health burden is calculated using disability-adjusted life years (DALYs). The results, based on 31 models of different forms, show that the degree of openness greatly affects performance with opposite effects for noise and air pollution. Building types with slightly open yards, like open corner blocks, may provide an attractive compromise solution due to their relatively good noise exposure situation at the same time as the dispersion of air pollutants improves. Adding sound absorbing vegetation is an effective measure to mitigate noise, especially for blocks with openings, limiting the propagation of sound into the yard. Further, densification is beneficial for health if the increase in density does not increase traffic volume in the same proportion. Densification by adding towers on a perimeter building block gives the best results for health as it combines a less noisy yard, thanks to the enclosure of the yard with towers, which enhances turbulent mixing of air within the street canyon.
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| 13. |
- Blunden, Jessica, et al.
(författare)
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State of the Climate in 2012
- 2013
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 94:8, s. S1-S258
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Tidskriftsartikel (refereegranskat)abstract
- For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Nevertheless, other large-scale climate patterns and extreme weather events impacted various regions during the year. A negative phase of the Arctic Oscillation from mid-January to early February contributed to frigid conditions in parts of northern Africa, eastern Europe, and western Asia. A lack of rain during the 2012 wet season led to the worst drought in at least the past three decades for northeastern Brazil. Central North America also experienced one of its most severe droughts on record. The Caribbean observed a very wet dry season and it was the Sahel's wettest rainy season in 50 years. Overall, the 2012 average temperature across global land and ocean surfaces ranked among the 10 warmest years on record. The global land surface temperature alone was also among the 10 warmest on record. In the upper atmosphere, the average stratospheric temperature was record or near-record cold, depending on the dataset. After a 30-year warming trend from 1970 to 1999 for global sea surface temperatures, the period 2000-12 had little further trend. This may be linked to the prevalence of La Ni a-like conditions during the 21st century. Heat content in the upper 700 m of the ocean remained near record high levels in 2012. Net increases from 2011 to 2012 were observed at 700-m to 2000-m depth and even in the abyssal ocean below. Following sharp decreases in to the effects of La Ni a, sea levels rebounded to reach records highs in 2012. The increased hydrological cycle seen in recent years continued, with more evaporation in drier locations and more precipitation in rainy areas. In a pattern that has held since 2004, salty areas of the ocean surfaces and subsurfaces were anomalously salty on average, while fresher areas were anomalously fresh. Global tropical cyclone activity during 2012 was near average, with a total of 84 storms compared with the 1981-2010 average of 89. Similar to 2010 and 2011, the North Atlantic was the only hurricane basin that experienced above-normal activity. In this basin, Sandy brought devastation to Cuba and parts of the eastern North American seaboard. All other basins experienced either near-or below-normal tropical cyclone activity. Only three tropical cyclones reached Category 5 intensity-all in Bopha became the only storm in the historical record to produce winds greater than 130 kt south of 7 N. It was also the costliest storm to affect the Philippines and killed more than 1000 residents. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June both reached new record lows. June snow cover extent is now declining at a faster rate (-17.6% per decade) than September sea ice extent (-13.0% per decade). Permafrost temperatures reached record high values in northernmost Alaska. A new melt extent record occurred on 11-12 July on the Greenland ice sheet; 97% of the ice sheet showed some form of melt, four times greater than the average melt for this time of year. The climate in Antarctica was relatively stable overall. The largest maximum sea ice extent since records begain in 1978 was observed in September 2012. In the stratosphere, warm air led to the second smallest ozone hole in the past two decades. Even so, the springtime ozone layer above Antarctica likely will not return to its early 1980s state until about 2060. Following a slight decline associated with the global 2 emissions from fossil fuel combustion and cement production reached a record 9.5 +/- 0.5 Pg C in 2011 and a new record of 9.7 +/- 0.5 Pg C is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, to 392.6 ppm. In spring 2012, 2 concentration exceeded 400 ppm at 7 of the 13 Arctic observation sites. Globally, other greenhouse gases including methane and nitrous oxide also continued to rise in concentration and the combined effect now represents a 32% increase in radiative forcing over a 1990 baseline. Concentrations of most ozone depleting substances continued to fall.
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| 14. |
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| 15. |
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| 16. |
- Burauskaite-Harju, Agne, et al.
(författare)
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Characterizing and visualizing spatio-temporal patterns in hourly precipitation records
- 2012
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer. - 0177-798X .- 1434-4483. ; 109:3-4, s. 333-343
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Tidskriftsartikel (refereegranskat)abstract
- We develop new techniques to summarize and visualize spatial patterns of coincidence in weather events such as more or less heavy precipitation at a network of meteorological stations. The cosine similarity measure, which has a simple probabilistic interpretation for vectors of binary data, is generalized to characterize spatial dependencies of events that may reach different stations with a variable time lag. More specifically, we reduce such patterns into three parameters (dominant time lag, maximum cross-similarity, and window-maximum similarity) that can easily be computed for each pair of stations in a network. Furthermore, we visualize such threeparameter summaries by using colour-coded maps of dependencies to a given reference station and distance-decay plots for the entire network. Applications to hourly precipitation data from a network of 93 stations in Sweden illustrate how this method can be used to explore spatial patterns in the temporal synchrony of precipitation events.
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| 17. |
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| 18. |
- Chen, Deliang, 1961, et al.
(författare)
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Projecting future local precipitation and its extremes for Sweden
- 2015
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Ingår i: Geografiska Annaler. - : Informa UK Limited. - 0435-3676 .- 1468-0459. ; 97:1, s. 25-39
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Tidskriftsartikel (refereegranskat)abstract
- A procedure to obtain future local precipitation characteristics focused on extreme conditions has been developed based on a weather generator. The method involves six major steps: (1) the weather generator was calibrated using observed daily precipitation at 220 Swedish stations during 1961–2004; (2) present and future daily precipitation characteristics for the Swedish stations from two global climate models, namely ECHAM5 and HadCM3, were used to calculate weather generator parameters for the present and future climates at global climate model spatial scales; (3) the ratio of the weather generator parameters for the present climate simulated by the global climate models to those calculated for each station falling into the global climate model grid box were computed for all the stations; (4) these ratios were also assumed to be valid in the future climate, that way the future parameters for each station for the global climate model projected future climate could be calculated; (5) using the estimated future parameters of the weather generator, the future daily precipitation at each station could be simulated by the weather generator; (6) the simulated daily precipitation was used to compute eight indices describing mean and extreme precipitation climates. The future mean and extreme precipitation characteristics at the stations under the Second Report on Emission Scenarios A2 scenario were obtained and presented. An overall increasing trend for frequency and intensity of the indices are identified for the majority of the stations studied. The developed downscaling methodology is relatively simple but useful in deriving local precipitation changes, including changes in the precipitation extremes.
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| 19. |
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| 20. |
- Chen, Deliang, 1961, et al.
(författare)
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Using statistical downscaling to quantify the GCM-related uncertainty in regional climate change scenarios: A case study of Swedish precipitation
- 2006
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Ingår i: Advances in Atmospheric Sciences. - 0256-1530. ; 23:1, s. 54-60
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Tidskriftsartikel (refereegranskat)abstract
- There are a number of sources of uncertainty in regional climate change scenarios. When statistical downscaling is used to obtain regional climate change scenarios, the uncertainty may originate from the uncertainties in the global climate models used, the skill of the statistical model, and the forcing scenarios applied to the global climate model. The uncertainty associated with global climate models can be evaluated by examining the differences in the predictors and in the downscaled climate change scenarios based on a set of different global climate models. When standardized global climate model simulations such as the second phase of the Coupled Model Intercomparison Project (CMIP2) are used, the difference in the downscaled variables mainly reflects differences in the climate models and the natural variability in the simulated climates. It is proposed that the spread of the estimates can be taken as a measure of the uncertainty associated with global climate models. The proposed method is applied to the estimation of global-climate-model-related uncertainty in regional precipitation change scenarios in Sweden. Results from statistical downscaling based on 17 global climate models show that there is an overall increase in annual precipitation all over Sweden although a considerable spread of the changes in the precipitation exists. The general increase can be attributed to the increased large-scale precipitation and the enhanced westerly wind. The estimated uncertainty is nearly independent of region. However, there is a seasonal dependence. The estimates for winter show the highest level of confidence, while the estimates for summer show the least.
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| 21. |
- Forssén, Jens, 1968, et al.
(författare)
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Effect of urban morphology and greening on noise and air pollution - case studies including disease burden estimates
- 2022
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Ingår i: Internoise 2022 - 51st International Congress and Exposition on Noise Control Engineering.
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Konferensbidrag (refereegranskat)abstract
- Exposure of both noise and air pollution due to road traffic in urban environments has been calculated and evaluated for multiple cases. A model study in an urban setting used 31 cases of building morphologies and traffic concentration. An evaluating second set was based on a real case of an arterial road transformed into a boulevard. Besides the effect of building morphology, the effects of driving speed, electric vehicles and urban greening were studied. The levels of noise exposure (Lden and Lnight at housing façades) and air pollution (NO2 and PM10 at sidewalks and yards) were calculated as input to estimating the health impact using DALY (Disability-Adjusted Life Years). Concluding from the results, the best solution from a noise perspective is closed blocks with green roofs, while the best solution concerning air quality is point buildings or closed blocks with added high towers. Urban greening was shown to improve the noise situation in general whereas air quality varied due to the interaction between wind speed, dispersion, and filtering effect of leaves. Urban planning guidelines were formulated, including also suggestions of traffic concentration by locating all local traffic to a single widened road as well as transitioning to electric vehicles in combination with reduced vehicle speed.
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| 22. |
- Forssén, Jens, 1968, et al.
(författare)
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GOD LUFT- OCH LJUDMILJÖ I STADSPLANERINGEN – EN STUDIE I BYGGNADSTYPOLOGI OCH GRÖNSKA FÖR GOD LUFT- OCH LJUDMILJÖ
- 2022
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Byggnadstypologier och bebyggelsetäthet är variabler inom stadsplanering sompåverkar miljön vid våra bostäder i form av ljudnivåer och luftföroreningar orsakadeav vägtrafik, vilket i sin tur inverkar på välbefinnande och hälsa. I forskningsprojektetMaGNA har vi undersökt bebyggelsens påverkan på buller- och luftkvalitet ivistelsemiljöer som ansluter till bostäder, inklusive ljudnivåer vid fasader. Med hjälpav modell- och fallstudier har olika typer av kvartersstruktur och byggnadsmorfologisimulerats, och exponering för buller- och luftföroreningar har beräknats.För att kunnajämföra buller och luft har vi gjort beräkningar av deras hälsoeffekter genom att skattafunktionsjusterade levnadsår så kallade DALYs. Resultaten visar att hälsoeffekterna avbåde ljud- och luftmiljön påverkas av bebyggelsens utformning och täthet samt gerrekommendationer om utformning för bästa möjliga miljö.
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| 23. |
- Forssén, Jens, 1968, et al.
(författare)
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Road traffic noise disease burden estimates for a model study of varying urban morphology cases
- 2021
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Ingår i: Proceedings of INTER-NOISE 2021 - 2021 International Congress and Exposition of Noise Control Engineering. - : Institute of Noise Control Engineering (INCE).
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Konferensbidrag (refereegranskat)abstract
- In a model study containing 31 different building morphologies in an urban setting, road traffic noise exposure has been calculated and analysed. For five of the building morphologies also vegetation surfaces on facades and roofs were studied. The facade exposure levels were analysed for both smaller (single-sided) flats and larger (floor-through) flats, considering the direct exposure from the roads as well as the non-direct exposure at noise-shielded positions like inner yards, applying a noise mapping software in combination with a prediction model for the non-direct exposure. Using noise indicators Lden and Lnight, the disease burden, in terms of DALY (Disability-Adjusted Life Years) per person, was estimated and analysed, via predictions of annoyance and sleep disturbance. As general trends, perimeter blocks were shown to perform better than morphologies with less enclosed yards and densification was shown to result in improved performance, assuming a constant traffic flow. In addition, complementing the perimeter blocks with towers was shown to enable improvement. Furthermore, traffic concentration by locating all local traffic to a single road was shown to be beneficial, increasingly so by widening the road. The use of facade vegetation was shown to result in significant overall improvement.
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| 24. |
- Haeger-Eugensson, Marie, et al.
(författare)
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Air Quality Modeling in Dense Urban Areas at Ground Level—CFD, OSM or Gauss?
- 2021
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Ingår i: Springer Proceedings in Complexity. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 2213-8684 .- 2213-8692. ; , s. 265-270
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Konferensbidrag (refereegranskat)abstract
- There is an ongoing intensive urban densification in many cities. The need for advanced modeling methods that realistically simulate dispersion at ground level in complex urban areas have increased. As more modeling is done outside usual model communities, guidelines supporting the selection of suitable models is needed. Dispersion of air pollutants in street canyons is affected by width, height, length and building structure. Studies show that concentration of NO2 in street canyons can become 5-times higher, compared to open conditions. Since Gaussian models cannot simulate dispersion at ground level in dense urban settlements models that include 3D information (buildings) is therefore required, such as CFD or OSM models to obtain realistic results. The purpose of the project is to investigate the effect from building on air quality and giving recommendations to authorities and consultants helping with model choices. This is based on calculations with three different model types, CFD, OSM and Gaussian for four urban environments, from dense to open suburban areas using the same input. Validation was done with continuous measurements of NO2 at each site. The CFD modeling gave best results at all sites, the OSM modeling quality varied between the sites, with slight to about 50% underestimation. The Gaussian modeling generally underestimated the concentration with 50%. The aspect ratio H/W ≥ 0.7 favors development of vortices and lateral dispersion of pollutants in street canyons. It was shown that with at least this aspect ratio locally emitted NO2 frequently becomes at least 2–3 times higher compared an open road case. A methodology has been developed visualized in a flow chart, for help choosing an appropriate model for each environment. Most important factors are; street canyon structure; local concentration level; proximity to high emissions/risk of leakage into calculation area.
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| 25. |
- Hanssen-Bauer, I., et al.
(författare)
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Statistical downscaling of climate scenarios over Scandinavia
- 2005
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Ingår i: Climate Research. - : Inter-Research Science Center. - 0936-577X .- 1616-1572. ; 29:3, s. 255-268
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Tidskriftsartikel (refereegranskat)abstract
- Studies from recent years involving development and application of statistical downscaling models for Scandinavia (mainly Norway and Sweden) are reviewed. In most of the studies linear techniques were applied. Local temperature and/or precipitation were predictands in a majority of the studies. Large-scale temperature fields, either from 2 m or 850 hPa, were found to be the best predictors for local temperature, while a combination of atmospheric circulation indices and tropospheric humidity information were the best predictors for local precipitation. Statistically downscaled temperature scenarios for Scandinavia differ depending on climate model, emission scenario and downscaling strategy. There are nevertheless several common features in the temperature scenarios. The warming rates during the 21st century are projected to increase with distance from the coast and with latitude. In most of Scandinavia higher warming rates are projected in winter than in summer. For precipitation, the spread between different scenarios is larger than for temperature. A substantial part of the projected precipitation change is connected to projected changes in atmospheric circulation, which differ considerably from one model integration to another. A tendency for increased large-scale humidity over Scandinavia still implies that projections for the 21st century typically indicate increased annual precipitation. This tendency is most significant during winter. In northern Scandinavia the projections tend to show increased precipitation also during summer, but several scenarios show reduced summer precipitation in parts of southern Scandinavia. Comparisons with results from global and regional climate models indicate that both regional modeling and statistical downscaling add value to the results from the global models.
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