Aerosol-induced Radiative Cooling in the Nocturnal Boundary Layer*

Longwave radiative cooling significantly affects the thermal profiles in the Nocturnal Boundary Layer (NBL), influencing mist, fog, dew, Lifted Temperature Minimum (LTM), and pollution dispersion. Current weather forecasting models often overlook aerosols in the longwave (LW) band, leading to inaccurate simulations of LW cooling and temperature profiles in the NBL. Our extensive field experiments at the Kempegowda International Airport, Bengaluru, combined with numerical simulations using a one-dimensional radiation-conduction model that includes aerosol-radiation interactions, reveal that aerosol-induced cooling impacts the temperature profiles several hundred meters into the boundary layer. Notably, this cooling can cause the air layer above the surface to be 2-6 K cooler than the soil surface (LTM), which is contrary to the belief that the ground cools faster than adjacent air layers after sunset. This research highlights the urgent need to incorporate aerosol-induced radiative cooling into numerical weather prediction models to accurately forecast temperature profiles within the NBL.