Impact of Land Use Land Cover (LULC) on the physical processes of a dense fog episode: A case study using WRF model from the National Capital Region, India

The rapid growth in population and urban development has attracted considerable scientific attention due to its impact on the local and regional atmospheric environment. Given its scientific significance, in this study, we employ the Weather Research and Forecasting (WRF) model to investigate the physical mechanisms underlying the impact of Land Use Land Cover (LULC) changes on the fog life cycle of a recent dense fog episode in January 2021. The model domain covers the Delhi National Capital Region (NCR) at a resolution of 2 km. We conducted two sensitivity experiments: The control run (CNTL), representing the current LULC, and the Experimental run (EXP), by integrating the land use conditions from 2004. Results from these experiments suggest that the model reasonably reproduces the near-surface meteorological conditions and vertical profiles during the severe fog episode. Over the past two decades, urban and built-up areas and dryland croplands increased by 119.73% and 118.97%, most of which were converted from irrigated croplands and other vegetated areas. We noticed that the increase in urban areas has led to an advancement in fog dissipation by about 1–2 h. The early dissipation also results in modifying the Liquid Water Path (LWP), consequently forming fog holes. Moreover, this phenomenon is likely to escalate if urban areas continue to develop in the future. We further attribute the near-surface soil moisture as a primary factor influencing the early lifting and dissipation of the fog layer by affecting surface fluxes (quantified by Bowen Ratio (BR)) and Turbulent Kinetic Energy (TKE), and expediting the heating (0.5°C–2°C) and drying (5%–20%) of the near-surface boundary layer (<500m from the land surface).