ABSTRACT

Surface urban heat island (SUHI) is a major anthropogenic alteration of Earth’s surface and can influence the local thermal environment by altering the surface energy flux balances. Researchers have paid much attention to SUHI studies in the last decades; still, its geospatial variability over a larger area is poorly understood. Detailed research is required to understand the mechanism and dynamics of SUHI along with its different driving variables. Hence in this study, we quantified the diurnal, seasonal, and interannual variation of SUHI intensity (SUHII) over 150 major Indian cities situated over different climatic zones using MODIS data from 2003 to 2018. The results reveal urban cool islands occurrence over the hot desert, hot steppe, and tropical monsoon climatic zone during daytime in both summer (−0.25 to −0.17°C) and winter (−0.33 to 0.17°C) season. In contrast, nighttime SUHII shows clear evidence of positive urban heat island irrespective of climatic region and seasonal variation of 0.48–1°C in summer and 0.46–1.32°C in winter is seen. The Mann–Kendall and Sen’s slope estimator tests are used to detect the trend of the SUHII during the study period, which suggests a higher percentage of cities showing an increasing trend of SUHII for urban heat islands than the cities of the urban cool island. Pearson’s correlation and stepwise multiple linear regression model determine the possible SUHII controlling variable over different climatic zones. During the daytime, the SUHII’s distribution is controlled by vegetation, evapotranspiration, and thermal inertia in the summer/winter season. Whereas, it is linked tightly to built-up intensity, white sky albedo, and thermal inertia in both seasons during nighttime. Overall, we found that the stepwise multiple linear regression model can explain the SUHII variance more in the daytime (>0.8) than in nighttime (>0.7, except for tropical cities) and more in understanding the SUHII behaviors for cool cities as compared to hot cities. Moreover, this study also quantifies the significant control of thermal inertia and soil moisture in understating urban heat and cool island behavior over different climatic zones.

摘要

地表城市热岛 (SUHI) 是地球表面的主要人为改变，可以通过改变地表能量通量平衡来影响当地的热环境。在过去的几十年里，研究人员非常关注 SUHI 研究；尽管如此，人们对其在更大区域内的地理空间变化知之甚少。需要详细研究以了解 SUHI 的机制和动力学及其不同的驱动变量。因此，在本研究中，我们使用 2003 年至 2018 年的 MODIS 数据量化了位于不同气候带的 150 个印度主要城市的 SUHI 强度 (SUHII) 的日、季和年际变化。 、炎热草原和热带季风气候区在夏季（-0.25 至 -0.17°C）和冬季（-0.33 至 0. 17°C) 季节。相比之下，夜间 SUHII 显示出明显的城市热岛效应，而与气候区域无关，并且可以看到夏季 0.48-1°C 和冬季 0.46-1.32°C 的季节性变化。Mann-Kendall 和 Sen 的斜率估计器检验用于检测研究期间 SUHII 的趋势，这表明城市热岛的 SUHII 呈上升趋势的城市比例高于城市冷岛城市。Pearson 相关性和逐步多元线性回归模型确定了不同气候带上可能的 SUHII 控制变量。在白天，SUHII 的分布受植被、蒸散和夏季/冬季的热惯性控制。鉴于它与建筑强度、白色天空反照率密切相关，和夜间两个季节的热惯性。总体而言，我们发现逐步多元线性回归模型在白天（>0.8）比夜间（>0.7，热带城市除外）更能解释 SUHII 方差，并且与炎热城市相比，更能理解凉爽城市的 SUHII 行为。城市。此外，本研究还量化了热惯性和土壤湿度在低估不同气候带上的城市热岛和冷岛行为方面的显着控制。