Modelling spatiotemporal variations of the canopy layer urban heat island in Beijing at the neighbourhood scale

Biggart, Michael; Stocker, Jenny; Doherty, Ruth M.; Wild, Oliver; Carruthers, David; Grimmond, Sue; Fu, Pingqing; Kotthaus, Simone

doi:10.5194/acp-21-13687-2021

Cited by 13 publications

(4 citation statements)

References 84 publications

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“…At night, as the suburbs were cooled by longwave radiation from the ground, while urban areas released building heat storage and anthropogenic heat emissions, the massive temperature difference between urban and rural sites increased the intensity of the heat island, and the maximum UHI intensity reached approximately 68C on the nights of 28 and 29 August. Biggart et al (2021) also showed the results that summer daytime cold island and nighttime UHI in Beijing.…”

Section: A Diurnal Variation and Spatial Distribution Of Uhimentioning

confidence: 84%

Observation and Simulation of Low-Level Jet Impacts on 3D Urban Heat Islands in Beijing: A Case Study

Lin

Wang

Yan

et al. 2022

Journal of the Atmospheric Sciences

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In this study, we focused on the impacts of the planetary boundary layer (PBL) low-level jet (LLJ) on the horizontal distribution, vertical development, and 3-D structure of urban heat island (UHI). Observational datasets were collected from 224 automatic weather stations (AWSs), and an intensive sounding experiment was conducted in Beijing from 28 August to 2 September 2016. 3-D simulations were operated by the Weather Research and Forecasting (WRF) model. The results show the following: Ri was smaller than 0.25 at both urban and suburban stations near the surface when LLJ was present. Through turbulent mixing, the LLJ extended the horizontal distribution of the canopy UHI downwind and increased the total UHI area by approximately 1 × 103 km2. The temperature lapse rate in the urban area was 0.7°C/100 m with LLJ, twice that in the absence of an LLJ. The jet enhanced the vertical mixing above the urban area, accompanied by a near-surface TKE up to 0.52 m2 s−2, elevating the vertical UHI development height to 200 m. The LLJ is capable of increasing the temperature of the downwind urban area by a maximum of 8.5°C h−1 through warm advection. The temperature advection in the upper air caused by LLJ also tilted the 3-D UHI structure as a plume. Results reproduced the process by which LLJ affect the 3-D UHI structure through turbulence and advection, and could also provide ideas regarding the influence of LLJ in other PBL processes.

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Section: A Diurnal Variation and Spatial Distribution Of Uhimentioning

confidence: 84%

Observation and Simulation of Low-Level Jet Impacts on 3D Urban Heat Islands in Beijing: A Case Study

Lin

Wang

Yan

et al. 2022

Journal of the Atmospheric Sciences

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“…Most satellites are not able to provide continuous record at short intervals due to orbit and revisit period constraints, and so are ineffective in monitoring and modelling the nocturnal UHI. The 3D nature of cities, in particular restricts sensor's potential to view all surfaces [14].Computational model simulation includes the 3D tools or software to investigate the effect of the urban morphology on wind velocity, thermal comfort, temperature variations, and spatial distribution of air pollution and also helps in comparing the effects of urban planning purposes on local climate zone [15]. At an appropriate scale, computational simulation can help to bridge the spatial gap between the surface based field observations, which are generally local and remote sensing data, which are not able to determine all related thermal fluxes, despite considerable improvement in the resolution and accuracy.…”

Section: Introductionmentioning

confidence: 99%

Urban Heat Island and Building Energy Consumption

Panwar,

Jindal,

Sneh

2024

IOP Conf. Ser.: Earth Environ. Sci.

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The change of natural land cover to impervious surfaces, dense built forms in cities causes built areas to experience high temperature than surrounding suburbs. This leads to urban heat island phenomenon which affects the microclimate. Despite the various studies supporting the importance of urban fabric, there is still a need to demonstrate how the urban surfaces can impact the temperature of surrounding areas. The purpose of this study is to determine the temperature change due to urban fabric by analyzing the role of materials having different albedo, reflectance and vegetation in changing the air and surface temperatures within a city. Existing case of an institutional campus (State University of Visual and Performing Arts, Rohtak, India) is undertaken for examining the temperature change at different urban surfaces by using the ENVI-met simulation software. The study area is analyzed for two scenarios involving the existing case (EC), proposed case (PC) scenario to understand the impact of different surface materials and vegetation on temperature. Surface and air temperature in both scenarios are extracted at two different heights-pedestrian level and canopy level. It is analyzed that different urban surfaces and construction materials play an effective role in varying the surface temperature and heat island intensities. Result shows potential benefits of increasing the albedo and reflectivity of pavements and roofs inside the city which helps in lowering surface temperature of walls and roofs and also lowering the air temperature around the surfaces. Along with this, vegetation also play an important role by creating a cooler environment by shading and reducing the surfaces temperature of built surfaces in an area. Therefore, adapting to essential urban green strategies can save city’s future from risks of urban heat islands.

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“…Ichinose et al, 1999;Fan and Sailor, 2005), subsequently contributing to higher cooling demand for buildings (Santamouris et al, 2001;Takane et al, 2019). In winter Q F can contribute to the intensity of the urban heat island (Biggart et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Revising the definition of anthropogenic heat flux from buildings: role of human activities and building storage heat flux

2022

Self Cite

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Abstract. Buildings are a major source of anthropogenic heat emissions, impacting energy use and human health in cities. The difference in magnitude and time lag between building energy consumption and building anthropogenic heat emission is poorly quantified. Energy consumption (QEC) is a widely used proxy for the anthropogenic heat flux from buildings (QF,B). Here we revisit the latter's definition. If QF,B is the heat emission to the outdoor environment from human activities within buildings, we can derive it from the changes in energy balance fluxes between occupied and unoccupied buildings. Our derivation shows that the difference between QEC and QF,B is attributable to a change in the storage heat flux induced by human activities (ΔSo-uo) (i.e. QF,B=QEC-ΔSo-uo). Using building energy simulations (EnergyPlus) we calculate the energy balance fluxes for a simplified isolated building (obtaining QF,B, QEC, ΔSo-uo) with different occupancy states. The non-negligible differences in diurnal patterns between QF,B and QEC are caused by thermal storage (e.g. hourly QF,B to QEC ratios vary between −2.72 and 5.13 within a year in Beijing, China). Negative QF,B can occur as human activities can reduce heat emission from a building but this is associated with a large storage heat flux. Building operations (e.g. opening windows, use of space heating and cooling system) modify the QF,B by affecting not only QEC but also the ΔSo-uo diurnal profile. Air temperature and solar radiation are critical meteorological factors explaining day-to-day variability of QF,B. Our new approach could be used to provide data for future parameterisations of both anthropogenic heat flux and storage heat fluxes from buildings. It is evident that storage heat fluxes in cities could also be impacted by occupant behaviour.

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Modelling spatiotemporal variations of the canopy layer urban heat island in Beijing at the neighbourhood scale

Cited by 13 publications

References 84 publications

Observation and Simulation of Low-Level Jet Impacts on 3D Urban Heat Islands in Beijing: A Case Study

Observation and Simulation of Low-Level Jet Impacts on 3D Urban Heat Islands in Beijing: A Case Study

Urban Heat Island and Building Energy Consumption

Revising the definition of anthropogenic heat flux from buildings: role of human activities and building storage heat flux

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