BUBBLE – an Urban Boundary Layer Meteorology Project

Rotach, Mathias W.; Vogt, Roland; Bernhofer, Christian; Batchvarova, Ekaterina; Christen, Andreas; Clappier, Alain; Feddersen, Berend; Gryning, Sven Erik; Martucci, Giovanni; Mayer, Helmut; Mitev, Valery; Oke, T. R.; Parlow, Eberhard; Richner, Hans; Roth, Matthias; Roulet, Yves-Alain; Ruffieux, Dominique; Salmond, Jennifer; Schatzmann, Michael; Voogt, James A.

doi:10.1007/s00704-004-0117-9

Cited by 347 publications

(246 citation statements)

References 46 publications

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“…The first recorded evapotranspiration measurements in urban areas based on this method were performed by Grimmond et al (1993) in Sacramento (USA) and Grimmond and Oke (1995) as comparative energy balance studies in four North American cities. Many other studies followed, performed especially in cities located at mid-latitudes, such as Christchurch (SpronkenSmith, 2002), Basel (Christen and Vogt, 2004;Rotach et al, 2005) and Łódź (Offerle et al 2006a(Offerle et al , 2006b). Meanwhile, a large number of investigations has been conducted in subtropical cities [e.g., Los Angeles (Grimmond et al, 1996), Mexico City (Barradas et al, 1999), Marseille (Grimmond et al, 2004), Tokyo (Moriwaki 144 A. GOLDBACH AND W. KUTTLER and Kanda, 2004), Ouagadougou (Burkina Faso; Offerle et al, 2005), Miami (Newton et al, 2007) and Cairo (Frey et al, 2011)] and in cities located at high latitudes [e.g., Edinburgh (Nemitz et al, 2002) and Helsinki (Vesala et al, 2008)].…”

Section: Introductionmentioning

confidence: 99%

Quantification of turbulent heat fluxes for adaptation strategies within urban planning

Goldbach

Kuttler

2012

Intl Journal of Climatology

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ABSTRACT:With the objective of quantifying turbulent heat fluxes in areas with various types of urban land use to improve living and environmental conditions through better urban planning, comparative energy balance measurements using the eddy-covariance (EC) technique were conducted in Oberhausen (Germany) between 15 August 2010 and 15 April 2011. The results of this paper show that the sensible heat flux (Q H ) is 20% higher and that the latent heat flux (Q E ) is 90% lower at an urban site (URB) compared to a suburban site (SUB). Green spaces in cities counteract the growing thermal stresses on city dwellers and therefore represent a possible urban climate mitigation measure. This positive effect may be reduced or lost entirely during long periods of drought. The Bowen ratio (Q H /Q E ) increased from 0.65 to 2.8 with decreasing soil moisture at the SUB, and the monthly average Q E value decreased from 94 W m −2 (August 2010, heavy precipitation) to only 47 W m −2 (March 2011, dry period), providing impressive evidence of this relationship. Considering the aspects of urban climate, the creation of urban green spaces can only be effective if an optimum water supply is provided. Furthermore, additional planning recommendations are given for urban planners within cities located at mid-latitudes, as derived from the measured results.

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Section: Introductionmentioning

confidence: 99%

Quantification of turbulent heat fluxes for adaptation strategies within urban planning

Goldbach

Kuttler

2012

Intl Journal of Climatology

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“…The index ratio of CTRL is 6. Observation by Rotach et al (2005) indicated that maximum SH were about 300 W m 2 to 400 W m 2 in midsummer at Basel, Switzerland.…”

Section: Sensitivity Experiments For Thermal Effectmentioning

confidence: 99%

“…However, we do not focus on the quantitative estimation of the urban heat flux but on the relation between the urban shallow clouds and the contrast of heat flux, so that we chose the simple urban expression, which allows to easily control sensible heat flux in the urban area. We are going to clarify the relation between cloud and heat flux by sensitivity experiments that cover the range of urban heat fluxes obtained by the past studies (Kusaka et al 2001;Rotach et al 2005). In the sensitivity experiments, the heat contrast between the urban and the rural areas is controlled by the soil moisture at the urban grid points, which is set to 75%, 85%, and 100% for Cases U75, U85, and N00, respectively.…”

Section: Numerical Model Designmentioning

confidence: 99%

Numerical Experiments on Fair-Weather Clouds Forming over the Urban Area in Northern Tokyo

Inoue

Kimura

2007

SOLA

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On clear, calm summer days, cloud lines are often observed above the expanding urban area along the railroads from Tokyo. The cloud lines were simulated using a numerical model with a simplified urban surface parameterization. The horizontal distributions of the simulated clouds agree well with the observed clouds in satellite images. Some sensitivity tests indicate that the urban thermal effect enhances cloud formation but suppresses clouds in the adjacent rural area. The simulated clouds are consistent with the observations when the urban maximum sensible heat flux is substantially larger than the rural one. With a reduction of the thermal contrast, cloud suppression in the rural area is gradually weakened. The mechanisms of the cloud contrast are as follows: 1) Thermals form in the mixed layer above the land surface. 2) Because of the larger sensible heat flux, the mixed layer tends to be higher in the urban area; thus, thermals reach the lifting condensation level more easily than they do in the rural area.3) The wide compensating downdrafts of the strong urban thermals cover the entire rural area and suppress thermals and clouds there.

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“…As part of a COST Action to examine the application of meteorology to urban air pollution problems, particular attention was paid to estimating airflow in this layer (Fisher et al 2005). Rotach et al (2005) suggest that the friction velocity at any height ( ) ( * z u ) within the RSL above the displacement height (that is, from d to z*) may be parameterised against the value at the top of the RSL (which may be obtained from the log profile), This COST approach was evaluated using wind observations acquired as part of the Basel UrBan Boundary Layer Experiment (BUBBLE) ), which included instruments located within both urban and rural settings. The results showed that eq.…”

Section: Literature Reviewmentioning

confidence: 99%

Estimating the wind resource in an urban area: A case study of micro-wind generation potential in Dublin, Ireland

Sunderland¹,

Mills

Conlon³

2013

Journal of Wind Engineering and Industrial Aerodynamics

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The micro-turbine wind market in cities faces significant challenges due to the complexities associated with the urban terrain but, if a renewable solution to increasing energy demand is to be achieved, energy conversion systems where populations are concentrated, that is cities, must be considered. This research evaluates the urban wind resource by employing a physically-based empirical model to link wind observations at a conventional meteorological site to those acquired at urban sites. The approach is based on urban climate research that has examined the effects of varying surface roughness on the wind-field between and above buildings. Here, this is applied to link observations at Dublin Airport, outside the urban area, to those made at an urban and suburban site in Dublin where instruments were placed near roof-level and well above roof height. The log model to describe the vertical wind profile is tested against observations made over the course of a year. It is shown to have sufficient accuracy to assess the potential for micro-turbine energy generation in cities and illustrates that the urban wind resource can be evaluated from measurements made at a nearby site, adjusted for the urban site location. HighlightsThe article investigates if a viable wind resource, worth exploiting, exists at an accessible height above a city (Dublin, Ireland) Urban climatology and the simple logarithmic profile, are employed to successfully extrapolate the wind resource at the city Airport into an associated suburban and urban location, to a height between 1.5 and 2 times the respective average building height at both locations The analysis shows that in conjunction with urban surface roughness, the urban frictional velocity must also be considered for urban wind resource modelling Other models are utilised to investigate the nature of the wind resource below the recognised lower limit of the logarithmic profile, namely the power law and a methodology primarily developed for urban air pollution modelling The research is provided a renewable energy context by considering the productivity of a commercially available wind generator. The results show that the wind resource available at roughly twice the average building height at either an urban and suburban location is worth harnessing, but within a very short height reduction, the wind resource depletion renders the consideration economically unviable.

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BUBBLE – an Urban Boundary Layer Meteorology Project

Cited by 347 publications

References 46 publications

Quantification of turbulent heat fluxes for adaptation strategies within urban planning

Quantification of turbulent heat fluxes for adaptation strategies within urban planning

Numerical Experiments on Fair-Weather Clouds Forming over the Urban Area in Northern Tokyo

Estimating the wind resource in an urban area: A case study of micro-wind generation potential in Dublin, Ireland

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