Evidence of urban heat island impacts on the vegetation growing season length in a tropical city

Abstract. The urban heat island (UHI) is a common effect caused by urbanization and has been studied to evaluate the thermal condition in cities worldwide. However, most previous UHI analyses are performed in major metropolitan cities. This study conducts a spatiotemporal analysis of UHI in a rapidly expanding low-density suburban centre and determines how bio-productive land covers react and the extent of the disturbance to each land cover based on time series land surface temperatures extracted from Landsat 7 ETM+ images. Two methods applied and compared are the single exponential decay method, which measures UHI footprint (UHIFP) on vegetation phenology, and the two dimensional Gaussian surface, which quantifies the influence based on distance from the local urban perimeter. Three spectral indices (Normalized Difference Vegetation Index (NDVI), Moisture Index (NDMI), and the Enhanced Vegetation Index (EVI)) were extracted and the residuals from the Gaussian model were compared based on these indices in order to better understand the thermal variations of each land cover within a UHI. The results show that the UHIFP of the studied low-density suburban centre is 1.4 times larger than the size of the urban centre, marginally smaller than previous analyses performed within high-density metropolises. All vegetated land covers experienced their maximum cooling effects before reaching the UHIFP perimeter while urban surfaces begin to diverge from the Gaussian model outside of the UHIFP. The residuals of sparse vegetation maintained strong correlations with each index throughout the growing season while NDMI retained the strongest relationships with every land cover. This study has helped us better understand the UHI effects of small communities with varied vegetation phonology based on the distribution of built-up pervious and impervious surfaces within the neighbourhood structure. The similar results from both methods indicate a strong urban cover influence overpowering the dominant distribution of agricultural surfaces throughout the growing season.

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Investigation of Urbanization Effects on Land Surface Phenology in Northeast China during 2001–2015

10.20944/preprints201701.0051.v1 ◽

2017 ◽

Author(s):

Rui Yao ◽

Lunche Wang ◽

Xin Huang ◽

Xian Guo ◽

Zigeng Niu ◽

...

Keyword(s):

Urban Heat Island ◽

Rural Area ◽

Land Surface ◽

Northeast China ◽

Growing Season ◽

Temporal Variations ◽

Urban Heat Island Intensity ◽

Heat Island ◽

Land Surface Phenology ◽

Urban Heat

The urbanization effects on land surface phenology (LSP) have been investigated by many studies, but few studies focused on the temporal variations of urbanization effects on LSP. In this study, we used the MODIS EVI, MODIS LST data and China’s Land Use/Cover Datasets (CLUDs) to investigate the temporal variations of urban heat island intensity and urbanization effects on LSP in Northeast China during 2001–2015. Land surface temperature (LST) and phenology differences between urban and rural areas represented the urban heat island intensity and urbanization effects on LSP, respectively. Mann-kendall nonparametric test and Sen's slope were used to evaluating the trends of urbanization effects on LSP and urban heat island intensity. The results indicated that the average land surface phenology (LSP) during 2001–2015 was characterized by high spatial heterogeneity. The start of the growing season (SOS) in old urban area had become earlier and earlier than rural area and the differences of SOS between urbanized area and the rural area changed greatly during 2001–2015 (−0.79 days/year, p < 0.01). Meanwhile, the length of the growing season (LOS) in urban and adjacent areas had become increasingly longer than rural area especially in urbanized area (0.92 days/year, p < 0.01), but the differences of the end of the growing season (EOS) between urban and adjacent areas did not change significantly. Next, the UHII increased in spring and autumn during the whole study period. Moreover, the correlation analysis indicated that the increasing urban heat island intensity in spring contributed greatly to the increases of urbanization effects on SOS, but the increasing urban heat island intensity in autumn did not lead to the increases of urbanization effects on EOS in Northeast China.

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Orographic effects on calculation of the urban heat island intensity

Оптика атмосферы и океана ◽

10.15372/aoo20180208 ◽

2018 ◽

Keyword(s):

Urban Heat Island ◽

Urban Heat Island Intensity ◽

Heat Island ◽

Orographic Effects ◽

Urban Heat

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

Media Komunikasi Geografi ◽

10.23887/mkg.v21i1.24429 ◽

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.

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

Seminar Nasional Geomatika ◽

10.24895/sng.2018.3-0.1022 ◽

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.

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