| 1. |
- Eliasson, Ingegärd, 1961-, et al.
(författare)
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Climate and behaviour in a Nordic city
- 2007
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Ingår i: LANDSCAPE AND URBAN PLANNING. - 0169-2046. ; 82:1-2, s. 72-84
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Tidskriftsartikel (refereegranskat)abstract
- Four urban public spaces, representing various designs and microclimates, were investigated in Gothenburg, Sweden, in order to estimate how weather and microclimate affect people in urban outdoor environments. The research strategy was both multidisciplinary and interdisciplinary and included scientists from three disciplines: architecture, climatology and psychology. The project is based on common case studies carried out during four seasons, including measurements of meteorological variables, interviews and observations of human activity at each place. Multiple regression analysis of meteorological and behavioural data showed that air temperature, wind speed and clearness index (cloud cover) have a significant influence on people's assessments of the weather, place perceptions and place-related attendance. The results support the arguments in favour of employing climate sensitive planning in future urban design and planning projects, as the physical component of a place can be designed to influence the site-specific microclimate and consequently people's place-related attendance, perceptions and emotions.
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| 2. |
- Franzén, Lars, 1950-, et al.
(författare)
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The potential peatland extent and carbon sink in Sweden, as related to the Peatland / Ice Age Hypothesis
- 2012
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Ingår i: Mires and Peat. - 1819-754X. ; 10:artikel nr 08
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Tidskriftsartikel (refereegranskat)abstract
- Peatlands cover approximately 65,600 km2 (16 %) of the Swedish land area. The available areas suitable for peatland expansion are far from occupied after ca. 12,000 years of the present interglacial. We estimate the potential extent of peatland in Sweden, based on slope properties of possible areas excluding lakes and glaciofluvial deposits. We assume no human presence or anthropic effects, so the calculation is speculative. It may have been relevant for previous interglacials. We calculate the potential final area of peatlands in three scenarios where they cover all available land with different maximum slope angles (1−3 º) using a Digital Elevation Model (DEM). The three scenarios yield potential peatland areas of 95,663 km2 (21 % of total available area), 168,287 km2 (38 %) and 222,141 km2 (50 %). The relative increases from the present 65,600 km2 are 46, 157 and 239 % respectively. The slope scenarios give CO2 uptake rates of 8.9−10.8, 18.1−22.4 and 24.6−30.5 Mt yr−1. Under global warming conditions with isotherms moved northwards and to higher altitudes, following an increase of raised bog area, the CO2 uptake rates might increase to 12.2−13.8, 24.4−27.7 and 33.5−37.9 Mt yr−1; i.e. up to 4.3−4.9 vpb of atmospheric CO2. If we make the speculative extrapolation from Sweden to all high latitude peatlands, and assume that all suitable areas with slope angle ≤ 3 ° become occupied, the global peatland CO2 sink might approach 3.7 Gt yr−1 (about 2 vpm yr−1) and potentially cause a net radiative cooling approaching 5 W m−2.
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| 3. |
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| 4. |
- Johansson, Lars, 1972-, et al.
(författare)
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Statistical modelling of pedestrian wind speed using high‐resolution digital surface models
- 2012
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Ingår i: The Eight International Conference on Urban Climates. ; :abstract 183
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Konferensbidrag (övrigt vetenskapligt)abstract
- Spatial variations of near ground wind speed (2magl) within urban areas are simulated by using a statistical model. The model is built upon the statistical relationship between derivatives extracted from digital surface models characterizing urban geometries (sky view factor, fetch, frontal area index) and wind speed, using statistical regression techniques. The geometric parameters are calculated for a number of urban settings in Gothenburg, Sweden. Wind speed patterns are derived using the three-dimensional microclimate model, ENVI-met. The model closely estimate the wind speed within-the major parts of the model domains such as in squares, and narrow streets as well as canyons perpendicular to the incoming wind direction. However, the output wind speed patterns are largely different from the wind speed simulated by ENVI-met in wide streets and around buildings where wind speed is high. Statistical models, as presented here, would be useful for not only climatologist/ meteorologist but also urban designers to consider wind modes depending on urban geometries and also to estimate thermal comfort influenced by wind.
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| 5. |
- Lindberg, Fredrik, 1974-, et al.
(författare)
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3D modelling of vegetation within a 2D model – evaluation and application
- 2012
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Ingår i: The Eight International Conference on Urban Climates.. ; :abstract nr 180
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Konferensbidrag (övrigt vetenskapligt)abstract
- The SOlar and LongWave Environmental Irradiance Geometry (SOLWEIG) model simulates spatial variations of 3D radiation fluxes and mean radiant temperature (Tmrt) as well as shadow patterns in complex urban settings. Here, a new vegetation scheme is presented and evaluated. A new shadow casting algorithm for complex vegetation structures makes it possible to obtain continuous images of shadow patterns and sky view factors taking both buildings and vegetation into account. The model is evaluated using 5 days of integral radiation measurements at two sites within a square surrounded by low-rise buildings and vegetation in Göteborg, Sweden (57°N). There is good agreement between modelled and observed values of Tmrt. Furthermore, SOLWEIG is used to examine vegetation and building morphology characteristics through a north-south LiDAR transect across the megacity of London. It is shown that the contribution of vegetation to the shadowing and reduction of Tmrt at ground level is higher during summer than in autumn. The results from these simulations highlight that vegetation can be most effective at reducing heat stress within dense urban environments in summer. The daytime average Tmrt is found to be lowest in the densest urban environments due to shadowing; foremost from buildings but also from trees. It is clearly shown that this method could be used to quantify the influence of vegetation on Tmrt within the urban environment. The results presented in this paper highlight a number of possible climate sensitive planning practices for urban areas at the local scale.
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| 6. |
- Lindberg, Fredrik, 1974-, et al.
(författare)
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Characteristics of the mean radiant temperature in high latitude cities—implications for sensitive climate planning applications
- 2013
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Ingår i: International Journal Of Biometeorology. - 0020-7128. ; s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of how the mean radiant temperature (T mrt ) is affected by factors such as location, climate and urban setting contributes to the practice of climate sensitive planning. This paper examines how T mrt varies within an urban setting and how it is influenced by cloudiness. In addition, variations of T mrt in three high latitude cities are investigated in order to analyse the impact of geographical context and climate conditions. Results showed large spatial variations between sunlit and shaded areas during clear weather conditions, with the highest values of T mrt close to sunlit walls and the lowest values in the areas shaded by buildings and vegetation. As cloudiness increases, the spatial pattern is altered and the differences are reduced. The highest T mrt under cloudy conditions is instead found in open areas where the proportion of shortwave diffuse radiation from the sky vault is high. A regional comparison between three Swedish coastal cities showed that T mrt during summer is similar regardless of latitudinal location. On the other hand, large differences in T mrt during winter were found. Shadows, both from buildings and vegetation are the most effective measure to reduce extreme values of T mrt . However, extensive areas of shadow are usually not desired within outdoor urban environments at high latitude cities. One solution is to create diverse outdoor urban spaces in terms of shadow and also ventilation. This would provide individuals with access to a choice of thermal environments which they can use to assist their thermal regulation, based on personal needs and desires.
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| 7. |
- Lindberg, Fredrik, 1974-, et al.
(författare)
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Mapping areas of potential slope failures in cohesive soils using a shadow-casting algorithm – A case study from SW Sweden
- 2011
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Ingår i: Computers and Geotechnics. ; 38, s. 791-799
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Tidskriftsartikel (refereegranskat)abstract
- When performing landslide susceptibility mapping of rotational slides in fine grained soils, slope algorithms found in common GIS software have two major shortcomings. Firstly, these types of terrain algorithms only consider the slope angle at the surface. Secondly, the algorithm is local by its design i.e. it only considers neighbouring pixels. Due to the behaviour of a retrogressive rotational landslide, it would be more preferable to consider slope information as a predetermined cross-section angle from the base of the slope. This paper presents a new method using shadow casting algorithms for preliminary landslide susceptibility mapping in cohesive soils. A case study from western Sweden is also presented.
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| 8. |
- Lindberg, Fredrik, 1974-
(författare)
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Modelling the urban climate using a local governmental database
- 2007
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Ingår i: Meteorological Applications. ; 14:3, s. 263-273
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Tidskriftsartikel (refereegranskat)abstract
- In this study, local government digital spatial data are used to describe urban geometry and analyse spatial variations of the urban climate within the central areas of Göteborg, Sweden. A high-resolution raster digital elevation model (1 m pixel resolution) consisting of building structures and ground heights is derived from a local government geo-database, as well as land use patterns and artificial heat sources. Parameters such as the sky view factor (SVF) and daily averages of solar radiation are calculated. Results obtained from the model are compared with intra-urban air temperature variations which are derived from mobile measurements, as well as surface temperature variations derived from thermal infrared images. Results show that high-resolution digital elevation models in raster format are very useful sources of data for the investigation of intra-urban temperature variations. Results also show that the areal mean of SVF correlates with intra-urban air temperature variations to a higher degree than SVF that is taken from a point source location. The correlation between the modelled SVF and surface temperature is high during both spring and winter. Adding information about daily averages of global radiation for the spring measurement causes the correlation between SVF and surface temperature variations to increase. Copyright © 2007 Royal Meteorological Society
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| 9. |
- Lindberg, Fredrik, 1974-
(författare)
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Modelling the urban microclimate using local governmental 3-d raw data
- 2006
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Ingår i: Lindqvist, S, Grimmond, CBS, (eds.), The sixth International Conference on Urban Climate. ; s. 867-870
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Konferensbidrag (refereegranskat)abstract
- The access and quality of digital spatial data covering urban areas have increased substantially in recent decades. As a result new methods using different kinds of spatial data within the field of urban climatology has been developed. This paper illustrates how digital data could be used to analyze spatial variations of the urban climate using a detailed Digital Elevation Model (DEM). Parameters such as the Sky View Factor (SVF) and insolation properties are modeled using municipality data covering the central areas of the city of Göteborg in Sweden. Model validation is conducted using hemispheric photographs and meteorological measurements.
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| 10. |
- Lindberg, Fredrik, 1974-, et al.
(författare)
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Nature of vegetation and building morphology characteristics across a city: Influence on shadow patterns and mean radiant temperatures in London
- 2011
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Ingår i: Urban Ecosystems. ; 14:4, s. 617-634
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Tidskriftsartikel (refereegranskat)abstract
- Vegetation and building morphology characteristics are investigated at 19 sites on a north-south LiDAR transect across the megacity of London. Local maxima of mean building height and building plan area density at the city centre are evident. Surprisingly, the mean vegetation height (zv3) is also found to be highest in the city centre. From the LiDAR data various morphological parameters are derived as well as shadow patterns. Continuous images of the effects of buildings and of buildings plus vegetation on sky view factor (SVF) are derived. A general reduction of SVF is found, indicating the importance of including vegetation when deriving SVF in urban areas. The contribution of vegetation to the shadowing at ground level is higher during summer than in autumn. Using these 3D data the influence on urban climate and mean radiant temperature (Tmrt) is calculated with SOLWEIG. The results from these simulations highlight that vegetation can be most effective at reducing heat stress within dense urban environments in summer. The daytime average Tmrt is found to be lowest in the densest urban environments due to shadowing, foremost from buildings but also from trees. It is clearly shown that this method could be used to quantify the influence of vegetation on Tmrt within the urban environment. The results presented in this paper highlight a number of possible climate sensitive planning practices for urban areas at the local scale (i.e. 102- 5×10^3 m).
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