Surface energy exchange in a dense urban built-up area based on two-year eddy covariance measurements in Sakai, Japan

Ando, Tomoya; Ueyama, Masahito

doi:10.1016/j.uclim.2017.01.005

Cited by 25 publications

(16 citation statements)

References 43 publications

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“…In recent years, more flux sites have been installed; however, the coverage does not yet address the global diversity or range of urban areas (Kotthaus and Grimmond, 2014a). Most previous observations of urban energy balances were conducted in mid-and low-latitude cities with moderate or hot climates (Velasco et al, 2005;Coutts et al, 2009;Velasco et al, 2011;Park et al, 2016;Roth et al, 2016;Ando and Ueyama, 2017), whereas only a few observations have been carried out in severe cold regions.…”

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confidence: 99%

Effects of snow cover on urban surface energy exchange: Observations in Harbin, China during the winter season

Shui

Liu

Xiao

et al. 2018

Intl Journal of Climatology

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The surface energy balance over Harbin, one of the major cities in severe cold regions of China, is examined during the snow‐covered and snow‐melt periods (January 11 to April 20, 2017) using radiation and eddy covariance measurements. Comparisons of radiation and energy fluxes from fresh snow, cold snow, melting snow, and snow‐free periods revealed that the presence of snow cover has a considerable impact on the radiation and energy balances. The daytime net radiation was mostly dissipated as sensible heat flux with a fraction of 43% during the fresh snow periods. During the cold snow periods, the daytime fraction of sensible heat flux decreased to 31% and most available energy was stored in the urban surfaces. During the melting snow periods, since the snowmelt process consumed a considerable portion of available energy, the daytime fraction of sensible heat flux decreased about 20% when compared to the cold snow periods, while the daytime fraction of latent heat flux increased about 50% due to the evaporation of melt water. After the snow melted, the ratio of daytime latent heat flux decreased because vegetation was not yet active during the snow‐free periods and the Bowen ratio increased from 2.3 (melting snow periods) to 5.9 (snow‐free periods).

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confidence: 99%

Effects of snow cover on urban surface energy exchange: Observations in Harbin, China during the winter season

Shui

Liu

Xiao

et al. 2018

Intl Journal of Climatology

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“…A very high spatial resolution is needed to understand city scale processes, particularly when urban greening is a crucial factor, as urban green spaces often cover small areas and are scattered throughout the cities. In situ observations, including dense networks of meteorological measurements in urban environments and the associated land surface fluxes are available for a very small number of cities (e.g., Ando & Ueyama, 2017; Kotthaus & Grimmond, 2012; H. C. Ward et al., 2013) and even in those they are localized. An alternative is offered by satellite retrievals of the earth's surface temperature, which have provided fine resolution data for decades now (e.g., Wan, 2008), allowing global scale SUHI estimations (e.g., Chakraborty & Lee, 2019; Clinton & Gong, 2013).…”

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Urban Forests as Main Regulator of the Evaporative Cooling Effect in Cities

et al. 2021

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Higher temperatures in urban areas expose a large fraction of the human population to potentially dangerous heat stress. Green spaces are promoted worldwide as local and city‐scale cooling strategies but the amount, type, and functioning of vegetation in cities lack quantification and their interaction with urban climate in different settings remains a matter of debate. Here we use state‐of‐the‐art remote sensing data from 145 city clusters to disentangle the drivers of surface urban heat islands (SUHI) intensity and quantify urban‐rural differences in vegetation cover, species composition, and evaporative cooling. We show that nighttime SUHIs are affected mostly by abiotic factors, while daytime SUHIs are highly correlated with vegetation characteristics and the wetness of the background climate. Magnitude and seasonality of daytime SUHIs are controlled by urban‐rural differences in plant transpiration and leaf area, which explain the dependence of SUHIs on wetness conditions. Leaf area differences are caused primarily by changes in vegetation type and a loss of in‐city forested areas, highlighting the importance of maintaining “natural reserves” as a sustainable heat mitigation policy.

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“…Virtually all observed and modeled estimates of the components of the energy balance of urban surfaces have been made since 1970 (Arnfield 2003). Recently, the majority of urban SEB observations were conducted in Europe and North America (e.g., Grimmond and Oke 2002;Nemitz et al 2002;Christen and Vogt 2004;Velasco et al 2011;Goldbach and Kuttler 2013;Chow et al 2014;Kotthaus and Grimmond 2014a,b), while only a few were conducted in Asia (e.g., Moriwaki and Kanda 2004;Liu et al 2012;Miao et al 2012;Ao et al 2016a;Ando and Ueyama 2017;Roth et al 2017). Several studies focused on the (sub)tropical regions that are reviewed by Tejeda-Martínez and Jáuregui-Ostos (2005) as well as , for instance, the one by Velasco et al (2011) and Roth et al (2017).…”

Section: Introductionmentioning

confidence: 99%

“…Several studies focused on the (sub)tropical regions that are reviewed by Tejeda-Martínez and Jáuregui-Ostos (2005) as well as , for instance, the one by Velasco et al (2011) and Roth et al (2017). However, very limited studies have been conducted in the humid subtropical climate regions (Cfa, classified by Köppen climate classification), including those in Shanghai, China (Ao et al 2016a), Tokyo, Japan (Moriwaki and Kanda 2004), and Sakai, Japan (Ando and Ueyama 2017). Furthermore, there is a dearth of robustly measured SEB data from dense urban core areas with local climate zone 1 (LCZ 1) (Stewart and Oke 2012), according to the review by Oke et al (2017).…”

Section: Introductionmentioning

confidence: 99%

Local-Scale Urban Energy Balance Observation under Various Sky Conditions in a Humid Subtropical Region

Shi

2019

Journal of Applied Meteorology and Climatology

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The present study presents local-scale urban energy balance observations under various sky conditions in a humid subtropical region. The study site is a typical urban residential area in Guangzhou in which building density is 38%, vegetation coverage is 36%, and mean building height is 21 m. The observation was conducted at a 110-m-high tower using the eddy covariance technique from September to November 2016. The median diurnal pattern and daily maxima were achieved for all radiation components and turbulent fluxes. The Bowen ratio (β) results indicated a predominant role for sensible heat flux (QH) in the daytime and latent heat flux (QE) at night. The sky conditions played a significant part in the urban surface energy exchanges, showing that the median daily maxima of net radiation (Q*), QH, storage heat flux (ΔQS), surface albedo, and β all present a consistent order from large to small for clear, cloudy, and rainy days and a different order of rainy, clear, and cloudy days for QE. The mean daytime QH/Q*, QE/Q*, ΔQS/Q*, and β changed with urban density, while QE/Q* and β also varied with vegetation fraction. Furthermore, the adaptability of net all-wave radiation parameterization (NARP), objective hysteresis model (OHM), and local-scale urban meteorological parameterization scheme (LUMPS) were validated, given the index of agreements of 0.998 and 0.951 for Q* and ΔQS and the reasonable RMSEs for QH and QE. The present study helps to verify and improve the parameterizations of energy exchange over an urban surface in the humid subtropical region.

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Surface energy exchange in a dense urban built-up area based on two-year eddy covariance measurements in Sakai, Japan

Cited by 25 publications

References 43 publications

Effects of snow cover on urban surface energy exchange: Observations in Harbin, China during the winter season

Effects of snow cover on urban surface energy exchange: Observations in Harbin, China during the winter season

Urban Forests as Main Regulator of the Evaporative Cooling Effect in Cities

Local-Scale Urban Energy Balance Observation under Various Sky Conditions in a Humid Subtropical Region

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