Puneeta Pandey

Urban heat island (UHI) is the phenomenon where urban areas possess higher temperature than its surrounding rural areas. The present review examines the factors contributing to the UHI effect and the challenge faced by Indian cities in the context of environmental sustainability and health by referring to the literature of more than 40 cities between 2005 and 2023. The present study reviewed already available research which utilizes remote sensing techniques to study the UHI. This study mainly includes satellite data studies; while some fixed station studies, field observations and instrument measurement studies were also incorporated. The current scenario of UHI research in India highlights that the larger cities are studied the most and the smaller but developing cities still need to be explored for the UHI research. The identified key drivers of UHI are vegetation loss, impervious surface, unplanned urban agglomeration, anthropogenic heat and aggravated energy consumption. Different methods have been studied including different simulation techniques used in UHI research. Furthermore, the present review highlights how India can advance towards creating a more resilient, sustainable, and healthful urban environment through integration of green infrastructure, and execution of policies such as Heat Action Plan (HAP) aimed at mitigating UHI impacts. Finally, this study highlights future key directions to examine understudied UHI layers, i.e., Atmospheric and canopy layer UHI, smaller or medium sized urban centers and encouraged to study the region-specific factors such as topography, morphology and socio-economic factors in order to facilitate sustainable and resilient urban planning in India.

Stubble burning is an emerging environmental issue in Northern India, which has severe implications for the air quality of the region. Although stubble burning occurs twice during a year, first during April–May and again in October–November due to paddy burning, the effects are severe during October–November months. This is exacerbated by the role of meteorological parameters and presence of inversion conditions in the atmosphere. The deterioration in the atmospheric quality can be attributed to the emissions from stubble burning which can be perceived from the changes observed in land use land cover (LULC) pattern, fire events, and sources of aerosol and gaseous pollutants. In addition, wind speed and wind direction also play a role in changing the concentration of pollutants and particulate matter over a specified area. The present study has been carried out for the states of Punjab, Haryana, Delhi, and western Uttar Pradesh to study the influence of stubble burning on the aerosol load of this region of Indo-Gangetic Plains (IGP). In this study, the aerosol level, smoke plume characteristics, long-range transport of pollutants, and affected areas during October–November from year 2016 to 2020 were examined over the Indo-Gangetic Plains (Northern India) region by the satellite observations. By MODIS-FIRMS (Moderate Resolution Imaging Spectroradiometer-Fire Information for Resource Management System) observations, it was revealed that there was an increase in stubble burning events with the highest number of events being observed during the year 2016 and then a decrease in the number of events in subsequent years from 2017 to 2020. MODIS observations revealed a strong AOD gradient from west to east. The prevailing north-westerly winds assist the spread of smoke plumes over Northern India during the peak burning season of October to November. The findings of this study might be used to expand on the atmospheric processes that occur over northern India during the post-monsoon season. The pollutant, smoke plume features, and impacted regions of biomass-burning aerosols in this region are critical for weather and climate research, especially given the rising trend in agricultural burning over the previous two decades. Graphical Abstract