Large-Scale Urban Heating and Pollution Domes over the Indian Subcontinent

Abstract

The unique geographical diversity and rapid urbanization across the Indian subcontinent give rise to large-scale spatiotemporal variations in urban heating and air emissions. The complex relationship between geophysical parameters and anthropogenic activity is vital in understanding the urban environment. This study analyses the characteristics of heating events using aerosol optical depth (AOD) level variability, across 43 urban agglomerations (UAs) with populations of a million or more, along with 13 industrial districts (IDs), and 14 biosphere reserves (BRs) in the Indian sub-continent. Pre-monsoon average surface heating was highest in the urban areas of the western (42 °C), central (41.9 °C), and southern parts (40 °C) of the Indian subcontinent. High concentration of AOD in the eastern part of the Indo-Gangetic Plain including the megacity: Kolkata (decadal average 0.708) was noted relative to other UAs over time. The statistically significant negative correlation (−0.51) between land surface temperature (LST) and AOD in urban areas during pre-monsoon time illustrates how aerosol loading impacts the surface radiation and has a net effect of reducing surface temperatures. Notable interannual variability was noted with, the pre-monsoon LST dropping in 2020 across most of the selected urban regions (approx. 89% urban clusters) while it was high in 2019 (for approx. 92% urban clusters) in the pre-monsoon season. The results indicate complex variability and correlations between LST and urban aerosol at large scales across the Indian subcontinent. These large-scale observations suggest a need for more in-depth analysis at city scales to understand the interplay and combined variability between physical and anthropogenic atmospheric parameters in mesoscale and microscale climates.

Effect of COVID-19 Lockdown on Urban Heat Island Dynamics in Prague, Czechia

“…The authors hypothesized that this warming was related to anticyclonic weather conditions prevailing across a large part of Europe in spring 2020 and decreased concentrations of aerosols, which enhanced the amount of solar radiation incoming to the land surface. This could have enhanced the positive radiation balance during the lockdown period [21,[50][51][52]. These findings highlight the important role of the natural variability of temperature and solar radiation that cannot be attributed to variations in AHF during lockdown.…”

Urban cooling potential and cost comparison of heat mitigation techniques for their impact on the lower atmosphere

“…Unfortunately, urban heating in tropical locations has not received sufficient attention, and studies on this topic remain limited in number, poorly understood, and scientifically unexplored (Chakraborty et al, 2023;Khan et al, 2020Khan et al, , 2022a. Monitoring different components of surface energy balance (SEB) in many highly urbanized tropical cities remains a significant challenge due to instrumentation limitations, cost, and the need for longterm commitment to measurements.…”