SOLWEIG 1.0 – Modelling spatial variations of 3D radiant fluxes and mean radiant temperature in complex urban settings

Lindberg, Fredrik; Holmer, Björn; Thorsson, Sofia

doi:10.1007/s00484-008-0162-7

Cited by 381 publications

(205 citation statements)

References 23 publications

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“…the SOLWEIG model (Lindberg et al, 2008), RayMan (Matzarakis et al, 2010), the TUF-3D model (Krayenhoff and Voogt, 2007), the TUF-IOBES model (Yaghoobian and Kleissl, 2012, based on TUF-3D), TEB (Masson, 2000), or SUEWS (Järvi et al, 2011). These models treat some physical processes (e.g.…”

Section: Urban Climatementioning

confidence: 99%

PALM-USM v1.0: A new urban surface model integrated into the PALM large-eddy simulation model

et al. 2017

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Abstract. Urban areas are an important part of the climate system and many aspects of urban climate have direct effects on human health and living conditions. This implies that reliable tools for local urban climate studies supporting sustainable urban planning are needed. However, a realistic implementation of urban canopy processes still poses a serious challenge for weather and climate modelling for the current generation of numerical models. To address this demand, a new urban surface model (USM), describing the surface energy processes for urban environments, was developed and integrated as a module into the PALM large-eddy simulation model. The development of the presented first version of the USM originated from modelling the urban heat island during summer heat wave episodes and thus implements primarily processes important in such conditions. The USM contains a multi-reflection radiation model for shortwave and longwave radiation with an integrated model of absorption of radiation by resolved plant canopy (i.e. trees, shrubs). Furthermore, it consists of an energy balance solver for horizontal and vertical impervious surfaces, and thermal diffusion in ground, wall, and roof materials, and it includes a simple model for the consideration of anthropogenic heat sources. The USM was parallelized using the standard Message Passing Interface and performance testing demonstrates that the computational costs of the USM are reasonable on typical clusters for the tested configurations. The module was fully integrated into PALM and is available via its online repository under the GNU General Public License (GPL). The USM was tested on a summer heat-wave episode for a selected Prague crossroads. The general representation of the urban boundary layer and patterns of surface temperatures of various surface types (walls, pavement) are in good agreement with in situ observations made in Prague. Additional simulations were performed in order to assess the sensitivity of the results to uncertainties in the material parameters, the domain size, and the general effect of the USM itself. The first version of the USM is limited to the processes most relevant to the study of summer heat waves and serves as a basis for ongoing development which will address additional processes of the urban environment and lead to improvements to extend the utilization of the USM to other environments and conditions.

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Section: Urban Climatementioning

confidence: 99%

PALM-USM v1.0: A new urban surface model integrated into the PALM large-eddy simulation model

et al. 2017

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“…Several methods are available to calculate the SVF based on fisheye images: The SVF can be calculated using analytical methods that derive the horizon limitation from geometric properties of the urban canyon (Johnson & Watson, 1984); vector-based methods that calculate the SVF from projected building envelopes on the sky using a 3D building database (Chen et al, 2012;Gál et al 2009;Gál & Unger, 2014;Unger, 2009); raster-based methods that use digital elevation models (DEMs) or DSMs to estimate SVFs based on pixel heights or shadow casting (Gál et al, 2009;Lindberg & Grimmond, 2011;Lindberg et al, 2008;Ratti, Baker, & Steemers, 2005;Zakšek, Oštir, & Kokalj, 2011), and photographic methods that use fisheye imagery of the upper hemisphere Chapman & Thornes, 2004;Grimmond, Potter, Zutter, & Souch, 2001;Holmer, Postgård, & Eriksson, 2001). The hemispheric horizon limitation is usually projected on a 2D plane to calculate the amount of visible sky in the scene.…”

Section: Sky View Factor Calculationmentioning

confidence: 99%

Sky View Factors from Synthetic Fisheye Photos for Thermal Comfort Routing—A Case Study in Phoenix, Arizona

Middel

Lukasczyk

Maciejewski

2017

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The Sky View Factor (SVF) is a dimension-reduced representation of urban form and one of the major variables in radiation models that estimate outdoor thermal comfort. Common ways of retrieving SVFs in urban environments include capturing fisheye photographs or creating a digital 3D city or elevation model of the environment. Such techniques have previously been limited due to a lack of imagery or lack of full scale detailed models of urban areas. We developed a web based tool that automatically generates synthetic hemispherical fisheye views from Google Earth at arbitrary spatial resolution and calculates the corresponding SVFs through equiangular projection. SVF results were validated using Google Maps Street View and compared to results from other SVF calculation tools. We generated 5-meter resolution SVF maps for two neighborhoods in Phoenix, Arizona to illustrate fine-scale variations of intra-urban horizon limitations due to urban form and vegetation. To demonstrate the utility of our synthetic fisheye approach for heat stress applications, we automated a radiation model to generate outdoor thermal comfort maps for Arizona State University's Tempe campus for a hot summer day using synthetic fisheye photos and on-site meteorological data. Model output was tested against mobile transect measurements of the six-directional radiant flux density. Based on the thermal comfort maps, we implemented a pedestrian routing algorithm that is optimized for distance and thermal comfort preferences. Our synthetic fisheye approach can help planners assess urban design and tree planting strategies to maximize thermal comfort outcomes and can support heat hazard mitigation in urban areas.

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“…Finally, the software "SOLWEIG" [31] was used for the computation of the fourth SVF raster map. The software was developed as a tool for modeling the spatial variations of radiant fluxes and mean radiant temperature in complex urban settings, and in fact, the computation of the SVF is only an intermediate product.…”

Section: Svf Maps From Lidar Datamentioning

confidence: 99%

Integration of Aerial Thermal Imagery, LiDAR Data and Ground Surveys for Surface Temperature Mapping in Urban Environments

Mandanici¹,

Conte²,

Girelli³

2016

Remote Sensing

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A single-band surface temperature retrieval method is proposed, aiming at achieving a better accuracy by exploiting the integration of aerial thermal images with LiDAR data and ground surveys. LiDAR data allow the generation of a high resolution digital surface model and a detailed modeling of the Sky-View Factor (SVF). Ground surveys of surface temperature and emissivity, instead, are used to estimate the atmospheric parameters involved in the model (through a bounded least square adjustment) and for a first assessment of the accuracy of the results. The RMS of the difference between the surface temperatures computed from the model and measured on the check sites ranges between 0.8°C and 1.0°C, depending on the algorithm used to calculate the SVF. Results are in general better than the ones obtained without considering SVF and prove the effectiveness of the integration of different data sources. The proposed approach has the advantage of avoiding the modeling of the atmosphere conditions, which is often difficult to achieve with the desired accuracy; on the other hand, it is highly dependent on the accuracy of the data measured on the ground.

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SOLWEIG 1.0 – Modelling spatial variations of 3D radiant fluxes and mean radiant temperature in complex urban settings

Cited by 381 publications

References 23 publications

PALM-USM v1.0: A new urban surface model integrated into the PALM large-eddy simulation model

PALM-USM v1.0: A new urban surface model integrated into the PALM large-eddy simulation model

Sky View Factors from Synthetic Fisheye Photos for Thermal Comfort Routing—A Case Study in Phoenix, Arizona

Integration of Aerial Thermal Imagery, LiDAR Data and Ground Surveys for Surface Temperature Mapping in Urban Environments

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