A Theoretical and Numerical Study of Urban Heat Island–Induced Circulation and Convection

2008 ◽  
Vol 65 (6) ◽  
pp. 1859-1877 ◽  
Author(s):  
Ji-Young Han ◽  
Jong-Jin Baik
Keyword(s):  
Urban Heat Island ◽  
Gravity Wave ◽  
Vertical Velocity ◽  
Three Dimensional ◽  
Internal Gravity Wave ◽  
Three Dimensions ◽  
Heat Island ◽  
Upward Motion ◽  
Additional Dimension ◽  
Urban Heat

Abstract Urban heat island–induced circulation and convection in three dimensions are investigated theoretically and numerically in the context of the response of a stably stratified uniform flow to specified low-level heating that represents an urban heat island. In a linear, theoretical part of the investigation, an analytic solution for the perturbation vertical velocity in a three-dimensional, time-dependent, hydrostatic, nonrotating, inviscid, Boussinesq airflow system is obtained. The solution reveals a typical internal gravity wave field, including low-level upward motion downwind of the heating center. Precipitation enhancement observed downwind of urban areas may be partly due to this downwind upward motion. The comparison of two- and three-dimensional flow fields indicates that the dispersion of gravity wave energy into an additional dimension results in a faster approach to a quasi-steady state and a weaker quasi-steady flow well above the concentrated heating region in three dimensions. In a nonlinear, numerical modeling part of the investigation, extensive dry and moist simulations using a nonhydrostatic, compressible model with advanced physical parameterizations [Advanced Regional Prediction System (ARPS)] are performed. While the maximum perturbation vertical velocity in the linear internal gravity wave field exists in the downwind region close to the heating center, the maximum updraft in three-dimensional dry simulations propagates downwind and then becomes quasi stationary. In three-dimensional moist simulations, it is demonstrated that the downwind upward motion induced by an urban heat island can initiate moist convection and result in downwind precipitation. The cloud induced by the downwind upward motion grows rapidly to become deep convective clouds. Heavy rainfalls are localized in a region not far from the heating center by a convective precipitating system that is nearly stationary. The differences in results between two and three dimensions are explained by the presence of (moist) convergence in an additional dimension. The numerical simulation results indicate that the intensity and horizontal structure of the urban heat island affect those of circulation and convection and hence the distribution of surface precipitation.

scholarly journals Construction of Cooling Corridors with Multiscenarios on Urban Scale: A Case Study of Shenzhen

2020 ◽  
Vol 12 (15) ◽  
pp. 5903
Author(s):  
Jiansheng Wu ◽  
Si Li ◽  
Nan Shen ◽  
Yuhao Zhao ◽  
Hongyi Cui
Keyword(s):  
Urban Heat Island ◽  
Three Dimensions ◽  
Cooling Effect ◽  
Control Line ◽  
Heat Island ◽  
Rapid Urbanization ◽  
Administrative Region ◽  
Total Length ◽  
Urban Heat ◽  
Pass Through

Under the background of rapid urbanization, the urban heat island (UHI) effect is becoming increasingly significant. It is very important for the sustainable development of cities to carry out quantitative research on the mitigation of the UHI effect at an urban scale. Taking Shenzhen as an example, this paper puts forward a method for building a cooling corridor for the city with multiscenarios based on the theory of ecological security pattern (ESP), which can realize quantitative planning of the spatial layout of urban green infrastructure (UGI) to alleviate the UHI effect. In this study, cooling sources are identified from the three dimensions of habitat quality, landscape connectivity, and the capacity to provide cooling ecosystem services. The cooling corridors that are superior at cooling, isolation, and ventilation are selected and optimized. The results show that the identified ecological cooling source area accounts for 33.18% of the total area of Shenzhen, and more than 85% of the area falls within the scope of the basic ecological control line of Shenzhen. There are 48 cooling corridors with a total length of 289.17 km in the cooling priority scenario, which mostly pass through the high-temperature and subhigh-temperature areas of each administrative region and city, providing a good cooling effect but poor feasibility. There are 48 corridors with a total length of 326.66 km in the isolation priority scenario, which mostly pass through the administrative region boundary and have a weak connection with the urban heat island, avoiding the built-up areas with strong human activities. As consequence, cooling is relatively achievable, but its effect is not ideal. There are 47 corridors with a total length of 368.06 km in the ventilation priority scenario, including many urban main roads and river systems that fully utilize the area’s strong natural wind conditions and realize various functions; however, the cooling effect is suboptimal. Corridors with great potential in cooling, isolation, ventilation, and noise reduction were determined after comprehensive optimization.

scholarly journals THREE-DIMENSIONAL SIMULATION OF URBAN HEAT ISLAND

1985 ◽  
Vol 28 (235) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo SAITOH ◽  
Kozo FUKUDA
Keyword(s):  
Urban Heat Island ◽  
Three Dimensional ◽  
Heat Island ◽  
Urban Heat ◽  
Dimensional Simulation

scholarly journals Numerical Investigation on the Urban Heat Island Effect by Using a Porous Media Model

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4681
Author(s):  
Tingzhen Ming ◽  
Shengnan Lian ◽  
Yongjia Wu ◽  
Tianhao Shi ◽  
Chong Peng ◽  
...  
Keyword(s):  
Porous Media ◽  
Urban Heat Island ◽  
Three Dimensional ◽  
Anthropogenic Heat ◽  
Heat Island ◽  
Circular Structure ◽  
Porous Media Model ◽  
Urban Heat ◽  
Artificial Heat ◽  
The Impact

The urban heat island (UHI) effect resulted from urbanization as well as industrialization has become a major environmental problem. UHI effect aggravates global warming and endangers human health. Thus, mitigating the UHI effect has become a primary task to address these challenges. This paper verifies the feasibility of a three-dimensional turbulent porous media model. Using this model, the authors simulate the urban canopy wind-heat environment. The temperature and flow field over a city with a concentric circular structure are presented. The impact of three factors (i.e., anthropogenic heat, ambient crosswind speed, and porosity in the central area) on turbulent flow and heat transfer in the central business district of a simplified city model with a concentric circular structure were analyzed. It is found that the three-dimensional turbulent porous media model is suitable for estimating the UHI effect. The UHI effect could be mitigated by reducing the artificial heat and improving the porosity of the central city area.

scholarly journals URBAN HEAT ISLAND MICRO-MAPPING VIA 3D CITY MODEL

2018 ◽  
Vol XLII-4/W10 ◽  
pp. 201-207 ◽  
Author(s):  
U. Ujang ◽  
S. Azri ◽  
M. Zahir ◽  
A. Abdul Rahman ◽  
T. L. Choon
Keyword(s):  
Solar Radiation ◽  
Urban Heat Island ◽  
Three Dimensional ◽  
Building Design ◽  
Development Planning ◽  
Heat Island ◽  
Sustainable Building ◽  
3D City Models ◽  
Urban Heat ◽  
City Models

<p><strong>Abstract.</strong> Urban Heat Island (UHI) phenomenon has been a topic of intense study over the past several years. However, to visualise UHI model is still an issue. Common visualisation of UHI by using digital thematic maps shows that it is hard to perceive its impacts especially in a sophisticated micro-area such as in urbanized cities. Moreover, different building façade’s material gives different UHI value. Therefore, there is a need in computing and visualising this phenomenon in three-dimensional (3D) perspectives. Recently, the development of 3D city modelling shows the potential of solving these gaps. This can be seen from the characteristics of 3D city models that are suitable in representing micro-areas (complex cities) for UHI studies. Based on this issue, this research aims to produce a 3D UHI model by using 3D city models as a tool for efficient and sustainable building design. The main objective is to produce a new approach in visualising UHI in 3D perspectives by instigating 3D city models. Thus, the UHI effect could be predicted precisely by calculating the building façades value. This research explores the 3D shadow analysis, 3D solar radiation and 3D orientation analysis in UHI modelling via 3D city models. From the analyses, the results show that the 3D city models are capable in presenting the solar radiation value for each building façade. Furthermore, this approach can be used to simulate future UHI analysis-prediction and advantageous for pre-development planning.</p>

Analisis Pengaruh Kerapatan Vegetasi Terhadap Suhu Permukaan dan Keterkaitannya Dengan Fenomena UHI

2020 ◽  
Vol 21 (1) ◽  
pp. 99
Author(s):  
Dewi Miska Indrawati ◽  
Suharyadi Suharyadi ◽  
Prima Widayani
Keyword(s):  
Urban Heat Island ◽  
Landsat 8 ◽  
Heat Island ◽  
Landsat 8 Oli ◽  
Urban Heat ◽  
Split Window Algorithm

Kota Mataram adalahpusat dan ibukota dari provinsi Nusa Tenggara Barat yang tentunya menjadi pusat semua aktivitas masyarakat disekitar daerah tersebut sehingga menyebabkan peningkatan urbanisasi. Semakin meningkatnya peningkatan urbanisasi yan terjadi di perkotaan akan menyebabkan perubahan penutup lahan, dari awalnya daerah bervegetasi berubah menjadi lahan terbangun. Oleh karena itu, akan memicu peningkatan suhu dan menyebabkan adanya fenomena UHI dikota Mataram.Tujuan dari penelitian ini untuk mengetahui hubungan kerapatan vegetasi dengan kondisi suhu permukaan yang ada diwilayah penelitian dan memetakan fenomena UHI di Kota Mataram. Citra Landsat 8 OLI tahun 2018 yang digunakan terlebih dahulu dikoreksi radiometrik dan geometrik. Metode untuk memperoleh data kerapatan vegetasi menggunakan transformasi NDVI, LST menggunakan metode Split Window Algorithm (SWA) dan identifikasi fenomena urban heat island. Hasil penelitian yang diperoleh menunjukkan kerapatan vegetasi mempunyai korelasi dengan nilai LST. Hasil korelasi dari analisis pearson yang didapatkan antara kerapatan vegetasi terhadap suhu permukaan menghasilkan nilai -0,744. Fenomena UHIterjadi di pusat Kota Mataram dapat dilihat dengan adanya nilai UHI yaitu 0-100C. Semakin besar nilai UHI, semakin tinggi perbedaan LSTnya.

PERUBAHAN PENUTUP LAHAN DAN KERAPATAN VEGETASI TERHADAP URBAN HEAT ISLAND DI KOTA SURAKARTA

2019 ◽  
Vol 3 ◽  
pp. 641
Author(s):  
Nafisatul Baroroh ◽  
Pangi Pangi
Keyword(s):  
Urban Heat Island ◽  
Heat Island ◽  
Urban Heat

Secara fisik, perkembangan perkotaan dapat terlihat dari perubahan penduduknya yang semakin bertambah dan semakin padat. Menurut data Badan Pusat Statistik, jumlah penduduk Kota Surakarta tahun 2000 yaitu sebesar 490.214 jiwa dan meningkat ±23.957 jiwa di tahun 2016. Pertumbuhan penduduk dan pembangunan yang pesat akan menyebabkan perubahan penggunaan lahan demi menunjang aktifitas penduduk yang seringkali mengakibatkan benturan kepentingan sehingga mengakibatkan menurunnya kualitas lingkungan. Hal itu disebabkan oleh semakin terdesaknya alokasi lahan untuk vegetasi. Perubahan lahan vegetasi yang tergantikan oleh jalan, bangunan dan struktur lain akan lebih banyak menyerap panas matahari dan memantulkannya, sehingga menyebabkan suhu permukaan di kota naik. Akibatnya semakin banyak titik-titik panas yang terbentuk sehingga menyebabkan perubahan unsur-unsur cuaca dan iklim sebagai pemicu terjadinya Urban Heat Island (UHI). Sesuai dengan uraian tersebut, maka tujuan penelitian ini adalah untuk menganalisis perubahan penutup lahan dan kerapatan vegetasi terhadap Urban Heat Island di Kota Surakarta. Metode analisis yang digunakan yaitu analisis deskriptif dan pengolahan data spasial. Berdasarkan hasil dari analisis menunjukkan bahwa jenis penutup lahan yang mendominasi adalah permukiman dan lahan terbangun, serta kelas kerapatan vegetasi didominasi oleh vegetasi jarang. Kemudian untuk distribusi suhu permukaan di Kota Surakarta secara keseluruhan tahun 1994, 2000 dan 2017 nilainya berubah, dimana rentang suhunya berkisar antara 21 C – 24 C (terendah) sampai dengan 34 C – 37 C (tertinggi). Perubahan suhu yang terjadi inilah mengindikasikan terjadinya fenomena Urban Heat Island di Kota Surakarta. Berdasarkan hal tersebut, maka dapat disumpulkan bahwa terdapat perubahan jenis penutup lahan dan juga kelas kerapatan vegetasi yang terjadi terhadap Urban Heat Island di Kota Surakarta.

OVERVIEW OF URBAN HEAT ISLAND (UHI) PHENOMENON TOWARDS HUMAN THERMAL COMFORT

2017 ◽  
Vol 16 (9) ◽  
pp. 2097-2111 ◽  
Author(s):  
Mohanadoss Ponraj ◽  
Yee Yong Lee ◽  
Mohd Fadhil Md Din ◽  
Zainura Zainon Noor ◽  
Kenzo Iwao ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Urban Heat Island ◽  
Heat Island ◽  
Human Thermal Comfort ◽  
Urban Heat
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