A case study on the intrusions of the dust and smoke aerosols and their direct radiative impacts on the surface heating
摘要
The aerosol subtypes and their distinct aerosol radiative effects are highly uncertain components in the global climate model due to the lack of observations at the required spatiotemporal scales, especially the vertical variation. In this study, the radiative effects of dust and smoke aerosols and their responses to boundary layer processes using Micro Pulse Lidar (MPL) observations conducted at Solapur (17.6°N, 75.9°E, 510 m a.m.s.l.), a rain-shadow region, India, during June 2023, are reported. Three important events characterized by the presence of an elevated aerosol layer (EAL), intrusions of dust and smoke aerosols, and fumigation with associated radiative forcing and heating rates were explored. The EAL observed during 17–19 June 2023 at ~ 1.5–4.0 km is mainly attributed to dust aerosols (~ 90%) with a depolarization ratio > 0.2. The event with intrusion of smoke plumes, constituted mainly of black carbon, with a depolarization ratio < 0.1. The strong fumigation event revealed that the heating rate within the boundary layer (below ~ 1.0 km) was nearly double that observed on weak fumigation days. The heating rates varied between 0.43 ± 0.04 K/day on weak fumigation days and 0.79 ± 0.07 K/day on strong fumigation days. The enhanced atmospheric heating rates are also observed at the dust/smoke residing altitudes. The average aerosol extinction within the boundary layer is ~ 0.30 ± 0.06 km⁻¹, while ~ 0.24 ± 0.08 km⁻¹ from the free troposphere indicates a significant contribution from elevated aerosol layers. During the campaign period, an overall radiative forcing was estimated to be 20.65 ± 6.18 Wm⁻² in the atmosphere, and at the surface − 31.38 ± 5.40 Wm−2, at the top of the atmosphere is about − 10.72 ± 2.40 Wm−2.