The influence of green areas on nocturnal temperatures in a high latitude city (Göteborg, Sweden)

Upmanis, Hillevi; Eliasson, Ingegärd; Lindqvist, Sven

doi:10.1002/(sici)1097-0088(199805)18:6<681::aid-joc289>3.0.co;2-l

Cited by 234 publications

(168 citation statements)

References 9 publications

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“…Later, cooling rates decreased and showed a similar, decreasing pattern at all sites throughout the night. Intraurban comparisons also showed a similar pattern with two different cooling phases (Upmanis et al, 1998;Chow and Roth, 2006;Erell and Williamson, 2007;Holmer et al, 2007). Holmer et al (2007) proposed that site-dependent differential cooling around sunset was dominated by radiative divergence and sensible heat flux cooling, which both are influenced by the geometry of the buildings that can be expressed as the SVF.…”

Section: Introductionmentioning

confidence: 64%

Evening evapotranspirative cooling in relation to vegetation and urban geometry in the city of Ouagadougou, Burkina Faso

Holmer

Thorsson

Lindén

2012

Intl Journal of Climatology

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Intra-urban cooling in the city of Ouagadougou, capital of Burkina Faso in the Sahel zone of West Africa, was studied during the dry seasons in 2003, 2004 and 2007. The aim was to see how vegetation, built structure and position within the built-up area influenced the nocturnal cooling. Cooling was divided into two phases. In Phase 1 (16 : 00-20 : 00 hours LST = CET), cooling was very different between the sites while in Phase 2 (20 : 00-06 : 00 hours LST), cooling rates differed insignificantly and the whole area cooled almost at the same rate. Thus the temperature differences between the sites developed during these few hours in Phase 1 were preserved during the rest of the night. In Phase 1, Evening Evapotranspirative Cooling was intensive at vegetated sites that cooled almost twice as fast as sparsely vegetated. This was indicated by a humidity rate (increase of specific humidity per hour) that was high at a vegetated site, but considerably lower at a sparsely vegetated. In Phase 2 the humidity rate was slightly negative with little difference between the sites. After a division in vegetated and sparsely vegetated sites built structure (sky view factor) were shown to influence cooling, but no influence of the position within the built-up area was traced. Thus, the site-specific properties dominated cooling, giving large intra-urban temperature differences. The study also showed the importance of considering a large enough source area to account for micro-scale advection.

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Section: Introductionmentioning

confidence: 64%

Evening evapotranspirative cooling in relation to vegetation and urban geometry in the city of Ouagadougou, Burkina Faso

Holmer

Thorsson

Lindén

2012

Intl Journal of Climatology

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“…For example, a study of four U.S. cities by Grimmond and Oke (1995) showed that the Bowen ratio decreases as irrigated green space increases. The presence of evaporating surfaces can also decrease the magnitude of the heat island effect (Upmanis et al 1998;Sailor 1995;Avissar 1996). Our simulations show that the summer daytime Bowen ratio is strongly correlated with the percent pervious area ( Fig.…”

Section: ͑1͒mentioning

confidence: 70%

An Urban Parameterization for a Global Climate Model. Part II: Sensitivity to Input Parameters and the Simulated Urban Heat Island in Offline Simulations

Oleson

Bonan

Feddema

et al. 2008

Journal of Applied Meteorology and Climatology

102

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In a companion paper, the authors presented a formulation and evaluation of an urban parameterization designed to represent the urban energy balance in the Community Land Model. Here the robustness of the model is tested through sensitivity studies and the model's ability to simulate urban heat islands in different environments is evaluated. Findings show that heat storage and sensible heat flux are most sensitive to uncertainties in the input parameters within the atmospheric and surface conditions considered here. The sensitivity studies suggest that attention should be paid not only to characterizing accurately the structure of the urban area (e.g., height-to-width ratio) but also to ensuring that the input data reflect the thermal admittance properties of each of the city surfaces. Simulations of the urban heat island show that the urban model is able to capture typical observed characteristics of urban climates qualitatively. In particular, the model produces a significant heat island that increases with height-to-width ratio. In urban areas, daily minimum temperatures increase more than daily maximum temperatures, resulting in a reduced diurnal temperature range relative to equivalent rural environments. The magnitude and timing of the heat island vary tremendously depending on the prevailing meteorological conditions and the characteristics of surrounding rural environments. The model also correctly increases the Bowen ratio and canopy air temperatures of urban systems as impervious fraction increases. In general, these findings are in agreement with those observed for real urban ecosystems. Thus, the model appears to be a useful tool for examining the nature of the urban climate within the framework of global climate models.

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“…However, few studies document the extent of the influence of parks. A park of about 150 ha can have an impact up to about a kilometre away in favourable conditions (Upmanis et al 1998) but the influence of two smaller parks studied was less marked. Although there have been studies on the cooling impact of parks covering a few dozen hectares within the fabric of a city, no-one has assessed the influence that landscape developments of several thousand km 2 , as envisaged here for Greater Paris, would have.…”

Section: Heat-waves Urban Heat Island and Urban Vegetationmentioning

confidence: 99%

“Grand Paris”: regional landscape change to adapt city to climate warming

Masson

Lion²,

Ambenje³

et al. 2012

Climatic Change

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"Grand Paris" is a study carried out by ten teams of researchers and city planners in the aim of putting forward general guidelines for Paris urban area's evolution by 2030. All the teams suggest making the area "greener" in some way, to combat climate warming by CO 2 sequestration. Our team also shows that extending the nearby forests by 30 %, favouring short farm-to-consumer circuits and using lighter coloured building materials will decrease the urban heat island, reducing the mortality during heat waves as well as the need for air-conditioning. These results lead us to reverse the way of thinking urban planning: the geographic and natural aspects should replace the urban infrastructure as a driver for planning urban development. This new strategy allows city changes on quite a large scale, that will have a favourable impact in terms of economics, leisure activities, greenhouse gas emissions and the local microclimate.

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The influence of green areas on nocturnal temperatures in a high latitude city (Göteborg, Sweden)

Cited by 234 publications

References 9 publications

Evening evapotranspirative cooling in relation to vegetation and urban geometry in the city of Ouagadougou, Burkina Faso

Evening evapotranspirative cooling in relation to vegetation and urban geometry in the city of Ouagadougou, Burkina Faso

An Urban Parameterization for a Global Climate Model. Part II: Sensitivity to Input Parameters and the Simulated Urban Heat Island in Offline Simulations

“Grand Paris”: regional landscape change to adapt city to climate warming

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