Impact of the April 2024 Ruang volcanic eruption on the Asian Tropopause Aerosol Layer: insights from Balloon measurements

Stratospheric aerosols play a crucial role in Earth's radiative balance and atmospheric chemistry. Their sources and properties are influenced by various factors, including volcanic eruptions, biomass burning (PyroCbs), and the Asian Tropopause Aerosol Layer (ATAL). The ATAL, a prominent feature of the Asian Summer Monsoon (ASM), extends from the eastern Mediterranean across India to western China at altitudes of 13-18 km.Recent volcanic eruptions have significantly impacted the stratosphere, with varying characteristics such as the magnitude and altitude of the eruption, the injected mass, and the resulting aerosol composition. These eruption characteristics, combined with the dynamics of the Asian Monsoon Anticyclone (AMA), and the pre-existing chemical state of the ATAL, contribute to complex and diverse aerosol properties within this region.The Balloon measurement campaign of the ATAL (BATAL) project utilizes balloon-borne instruments to investigate the optical, physical, and chemical properties of the ATAL. Since its inception a decade ago, BATAL has employed optical particle counters, balloon-borne radiosondes, and aerosol collectors to characterize ATAL aerosols. These measurements are further complemented by satellite and ground-based lidar observations to enhance our understanding of aerosol sources and transport mechanisms. Understanding the different sources of stratospheric aerosols over Asia is critical to differentiate the impacts of anthropogenic and natural aerosols on the climate and monsoon hydrological cycle. In the summer of 2024, after a four-year hiatus due to the COVID-19 pandemic, the BATAL project resumed measurements in India. Our observations revealed a complex scenario where the UTLS was influenced by both the ATAL and the transport of aerosols from the Ruang volcanic eruption, which occurred in April 2024. By analyzing data from a suite of instruments, including balloon-borne optical particle counters, backscatter sondes, and aerosol samplers. This analysis will enable us to compare the characteristics of ATAL and volcanic aerosols and discuss the implications of these findings for understanding their combined impact on the atmosphere.