Urban Heat Island research using remote sensing: A bibliometric review with special reference to India

Climate change is one of the prime concerns in the contemporary world, mainly due to the global proliferation of urban areas. This leads to the Urban Heat Island (UHI) effect, where the temperature of the city core is warmer than its non-urban surroundings and is known to affect inhabitants' lives. To better understand the phenomenon, Remote Sensing has proved to be a valuable tool for studying the phenomenon, its physics and its implications. Due to India's exponential urbanisation, studying the UHI effect and developing tailored mitigation policies is critical. This review intends to assist researchers, policymakers, and institutions by aiding informed decision-making for future research trajectory and policy formulation through an extensive review of the research studies conducted on the UHI effect using Remote Sensing and subsequently comparing the research status of India vis-a-vis the world. By incorporating rigid inclusion and exclusion criteria consisting of various keywords, top citations, and publication year range of the past 15 years, i.e., 2009 to 2023, a total of 94 papers out of a pool of 576 articles were meticulously reviewed for bibliometric trends, technical specifications and methodologies. These papers were also scoped for proposed mitigation strategies, if any. The review finds that the number of papers published saw a two-fold growth after 2015, which was the year when the Paris Agreement was signed. Globally, this number declined in 2020 due to the COVID-19 pandemic, while in the case of India, this effect became evident in 2021. Within India, North and North-Eastern regions need more studies in this subject matter. A review of satellites and sensors employed in these papers revealed that none of the satellites used were Indian, indicating a gap in disseminating the technical database and the need to increase technical capacity for research purposes. Additionally, studies using remote sensing technologies to study the UHI effect do not explore or suggest any mitigation strategies, leaving a gap in this remote sensing-led UHI research area.