Influence of vegetation and building geometry on the spatial variations of air temperature and cooling rates in a high‐latitude city

Konarska, Janina; Holmer, Björn; Lindberg, Fredrik; Thorsson, Sofia

doi:10.1002/joc.4502

Cited by 80 publications

(37 citation statements)

References 48 publications

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“…The effect of evapotranspiration on nocturnal cooling has been reported at vegetated sites in Ouagadougou, Burkina Faso (Holmer et al, 2013) and Gothenburg, Sweden (Konarska et al, 2015a). The cooling rates at vegetated sites in Ouagadougou were almost twice more than sparsely vegetated sites (Holmer et al, 2013).…”

Section: Other Factors Affecting Cooling Ratesmentioning

confidence: 98%

“…the heterogeneity of surface materials, evapotranspiration from vegetation, the release of anthropogenic heat, air humidity and advection of cooler/warmer air from surroundings. Oke (1981) and Konarska et al (2015a) suggest that SVF explains >80% of the spatial variation of UHI/IUHI intensities or cooling rates; thus, the residual percent can be explained by those factors.…”

Section: Other Factors Affecting Cooling Ratesmentioning

confidence: 99%

“…The influence of evapotranspiration from vegetation or natural surfaces on cooling rates was ignored. Compared with the radiative effect of trees and bushes obscuring the sky, the evapotranspiration effect was found to be less significant (Spronken‐Smith and Oke, ; Konarska et al , ). The impact of anthropogenic heat was also ignored as coolers/heaters are not commonly used in Sweden between May and September.…”

Section: Study Site and Observational Datamentioning

confidence: 99%

“…R 2 > 0.8 (Oke, ; Konarska et al , ). Oke () suggests that SVF explains most of IUHI intensities given similar surface materials within a single urban area but Konarska et al () found that SVF is the most important factor controlling cooling rates even in comparison between non‐vegetated sites and vegetated sites. As described above, the physical concepts of UHI/IUHI intensities and cooling rates and their relationships with meteorological variables and site characteristics have been established.…”

Section: Introductionmentioning

confidence: 99%

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Intra‐urban nocturnal cooling rates: development and evaluation of the NOCRA model

Onomura

Holmer

Lindberg

et al. 2016

Meteorological Applications

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ABSTRACT:A nocturnal cooling rate model (NOCRAM) to simulate nocturnal air temperature at urban sites is presented. The model is designed for urban planners, practitioners and researchers who demand meteorological information for urban planning and research applications. The model is based on the concept of nocturnal cooling, progressing in two distinct phases, i.e. site-dependent cooling around sunset and site-independent cooling from about 1 or 2 h after sunset until sunrise. Cooling rates are usually determined predominantly by prevailing weather conditions (i.e. clearness of the sky and wind speed), followed by maximum daily air temperature and by sky view factors. Second phase cooling is chiefly determined by sky clearness and wind speed. The findings and statistical results from the analysis of observational data during warm months (May-September) from Gothenburg, Sweden, as well as from past studies, were used. The model requires standard meteorological variables (i.e. wind speed, incoming short-wave radiation, air temperature, relative air humidity, air pressure) at a reference station as well as geometrical information (i.e. the sky view factor of the site and the geographical co-ordinates of the reference meteorological station). The model simulates the characteristic development of cooling rates in the two phases at open sites and built-up sites with different sky view factors under a wide range of weather conditions in warm months. Using the modelled cooling rates, nocturnal air temperature is estimated easily with the accuracy of root mean square error (RMSE) ≤1.54 ∘ C and R 2 ≥0.78.

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Section: Other Factors Affecting Cooling Ratesmentioning

confidence: 98%

Section: Other Factors Affecting Cooling Ratesmentioning

confidence: 99%

Section: Study Site and Observational Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Intra‐urban nocturnal cooling rates: development and evaluation of the NOCRA model

Onomura

Holmer

Lindberg

et al. 2016

Meteorological Applications

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“…Nature-based solutions, such as the increase of urban vegetation, are often encouraged to mitigate UHI and decrease surface runoff as part of a sustainable urban development (Lim and Lu, 2016;Roth, 2007;Bowler et al, 2010;Pataki et al, 2011;Li et al, 2014;Gillner et al, 2015). For instance, urban trees provide shade for pedestrians and evaporative cooling (Bowler et al, 2010;Konarska et al, 2016), while an increase in ground vegetation can further provide storm water retention (Berland et al, 2017). In addition to urban climate and water regulation, urban vegetation also provides other ecosystem services, for example, carbon storage (Nowak and Crane, 2002), enhanced biodiversity (Grimm et al, 2008), and aesthetic, cultural and health benefits (Salmond et al, 2016;Ng et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0)

Meili¹,

Manoli²,

Burlando³

et al. 2019

Preprint

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Abstract. Increasing urbanization is likely to intensify the urban heat island effect, decrease outdoor thermal comfort and enhance runoff generation in cities. Urban green spaces are often proposed as a mitigation strategy to counteract these adverse effects and many recent developments of urban climate models focus on the inclusion of green and blue infrastructure to inform urban planning. However, many models still lack the ability to account for different plant types and oversimplify the interactions between the built environment, vegetation, and hydrology. In this study, we present an urban ecohydrological model, Urban Tethys-Chloris (UT&C), that combines principles of ecosystem modelling with an urban canopy scheme accounting for the biophysical and ecophysiological characteristics of roof vegetation, ground vegetation and urban trees. UT&C is a fully coupled energy and water balance model that calculates 2 m air temperature, 2 m humidity, and surface temperatures based on the infinite urban canyon approach. It further calculates all urban hydrological fluxes, including transpiration as a function of plant photosynthesis. Hence, UT&C accounts for the effects of different plant types on the urban climate and hydrology, as well as the effects of the urban environment on plant well-being and performance. UT&C performs well when compared against energy flux measurements of eddy covariance towers located in three cities in different climates (Singapore, Melbourne, Phoenix). A sensitivity analysis, performed as a proof of concept for the city of Singapore, shows a mean decrease in 2 m air temperature of 1.1 °C for fully grass covered ground, 0.2 °C for high values of leaf area index (LAI), and 0.3 °C for high values of Vc,max (an expression of photosynthetic activity). These reductions in temperature were combined with a simultaneous increase in relative humidity by 6.5 %, 2.1 %, and 1.6 %, for fully grass covered ground, high values of LAI, and high values of Vc,max, respectively. Furthermore, the increase of pervious vegetated ground is able to significantly reduce surface runoff. These results show that urban greening can lead to a decrease in urban air temperature and surface runoff, but this effect is limited in cities characterized by a hot, humid climate.

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Location matters: planting urban trees in the right places improves cooling

Wang

Zhou

Jiao

2022

Frontiers in Ecol & Environ

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Available space and other resources associated with urban greening initiatives are limited, yet demand for urban cooling to mitigate high urban temperatures is growing. Consequently, identifying the best locations for urban greening to maximize the cooling effects of the urban tree canopy (UTC) is taking on new urgency. We present a cross‐city comparison and show how cooling efficiency (CE) varies spatially within a city. CE tends to be higher in locations with less UTC due in part to evapotranspiration from non‐uniformly distributed trees, but results from a subtropical city included within our comparison underscore the strong effect of a city’s background climate on CE. Mapping the spatial variation of CE can guide tree planting to enhance the cooling effects of UTC, expand the role trees play in urban adaptation to local warming, and help achieve urban sustainability.

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Influence of vegetation and building geometry on the spatial variations of air temperature and cooling rates in a high‐latitude city

Cited by 80 publications

References 48 publications

Intra‐urban nocturnal cooling rates: development and evaluation of the NOCRA model

Intra‐urban nocturnal cooling rates: development and evaluation of the NOCRA model

An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0)

Location matters: planting urban trees in the right places improves cooling

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