Effective albedo estimates for the Metropolitan Area of São Paulo using empirical sky-view factors

Morais, Marcos Vinicius Bueno de; Marciotto, Edson R.; Guerrero, Viviana Vanesa Urbina; Freitas, Edmílson Dias de

doi:10.1016/j.uclim.2017.06.007

Cited by 13 publications

(5 citation statements)

References 31 publications

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“…The use of "urban-types" criterion instead of the local climate zones (LCZs, [32]) is due to the fact that the first is used for setting up the model urban surface configuration. This configuration has been used in several investigations in MASP by other researchers [6,31,33,34]. Thus, for the sake of consistency and comparability with previous works, we kept the urban classification system as it was originally programmed in the model, although the parameter values can be changed.…”

Section: Sky-view Factormentioning

confidence: 99%

Implementation of Observed Sky-View Factor in a Mesoscale Model for Sensitivity Studies of the Urban Meteorology

et al. 2018

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Abstract:The sky view factor (SVF) is an important radiometric parameter for assessing the canopy energy budget of urban areas. There are several methods to determine the SVF observationally. The most common is taking a photo with a digital camera equipped with a fish-eye lens and then converting ratio of sky area to canopy area into SVF. However, most urban canopy models use this variable as derived from idealized canopy geometry. To evaluate the effect of inputting observed SVFs in numerical models, we evaluated a mesoscale model's performance in reproducing surface wind and surface temperature when subjected to different ways of SVF prescription. The studied area was the Metropolitan Area of São Paulo (MASP) in Brazil. Observed SVFs were obtained for 37 sites scattered all over the MASP. Three simulations, A, B, and C, with different SVF and aspect-ratio prescriptions, were performed to analyze the effect of SVF on the urban canopy parameterization: Simulation A (standard) used the original formulation of the Town Energy Budget (TEB) model, computing the SVFs from the aspect-ratios; Simulation B used the observed SVFs, but keeps aspect-ratios as original; and Simulation C used the aspect-ratios computed from observed SVFs. The results show that in general inputting observed SVFs improves the model capability of reproducing temperature at surface level. The comparison of model outputs with data of regular meteorological stations shows that the inclusion of observed values of SVFs enhances model performance, reducing the RMSE index by up to 3 • C. In this case, the model is able to better reproduce the expected effects in the wind field, and consequently the temperature advection, of the urban boundary layer to a large urban area. The result of Simulation C shows that the surface wind and temperature intensity for all urban types is higher than those of Simulation A, because of the lower values of the aspect ratio. The urban type with high density of tall buildings increase up to 1 m s −1 in the wind speed, and approximately 1 • C in temperature, showing the importance of a better representation of the urban structure and the SVF database improvement.

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Section: Sky-view Factormentioning

confidence: 99%

Implementation of Observed Sky-View Factor in a Mesoscale Model for Sensitivity Studies of the Urban Meteorology

et al. 2018

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“…The process of urbanization has greatly changed the urban surface coverage and spatial function structure. This has caused a change in the surface albedo and the release of a large amount of human heat, both of which have large driving effects on the UHI effect [45,57,58]. Therefore, Zhengzhou can be used to study the driving mechanisms of the UHI effect in a rapidly urbanizing area.…”

Section: Introductionmentioning

confidence: 99%

Spatio-Temporal Evolution Analysis of the Urban Heat Island: A Case Study of Zhengzhou City, China

2018

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During the progress of urbanization in China, a large number of natural landscapes have been replaced by impervious surfaces. The strong interference from human activities has led to the intensification of urban heat island (UHI) effects and has had a negative influence on the health of residents. Zhengzhou, as a new representative city of rapid urbanization, can be used as a case study for UHI. This study built an inversion model of the land surface temperature (LST) of Zhengzhou

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“…Nevertheless, there is an equivalence between the aspect ratio and a more robust parameter: the sky view factor (SVF). Based on SVFs, the amount of radiant energy impinging a surface (roof, wall or street/ground) can be calculated or measured for any geometry [47,[54][55][56][57].…”

Section: Aspect Ratiomentioning

confidence: 99%

Energetics of Urban Canopies: A Meteorological Perspective

Marciotto

Morais

2021

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The urban climatology consists not only of the urban canopy temperature but also of wind regime and boundary layer evolution among other secondary variables. The energetic input and response of urbanized areas is rather different to rural or forest areas. In this paper, we outline the physical characteristics of the urban canopy that make its energy balance depart from that of vegetated areas and change local climatology. Among the several canopy characteristics, we focus on the aspect ratio h/d and its effects. The literature and methods of retrieving meteorological quantities in urban areas are reviewed and a number of physical analyzes from conceptual or numerical models are presented. In particular, the existence of a maximum value for the urban heat island intensity is discussed comprehensively. Changes in the local flow and boundary layer evolution due to urbanization are also discussed. The presence of vegetation and water bodies in urban areas are reviewed. The main conclusions are as follows: for increasing h/d, the urban heat island intensity is likely to attain a peak around h/d≈4 and decrease for h/d>4; the temperature at the pedestrian level follows similar behavior; the urban boundary layer grows slowly, which in combination with low wind, can worsen pollution dispersion.

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Effective albedo estimates for the Metropolitan Area of São Paulo using empirical sky-view factors

Cited by 13 publications

References 31 publications

Implementation of Observed Sky-View Factor in a Mesoscale Model for Sensitivity Studies of the Urban Meteorology

Implementation of Observed Sky-View Factor in a Mesoscale Model for Sensitivity Studies of the Urban Meteorology

Spatio-Temporal Evolution Analysis of the Urban Heat Island: A Case Study of Zhengzhou City, China

Energetics of Urban Canopies: A Meteorological Perspective

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