Atmospheric sulfur isotopic anomalies recorded at Mt. Everest across the Anthropocene

Increased anthropogenic-induced aerosol concentrations over the Himalayas and Tibetan Plateau have affected regional climate, accelerated snow/glacier melting, and influenced water supply and quality in Asia. Although sulfate is a predominant chemical component in aerosols and the hydrosphere, the contributions from different sources remain contentious. Here, we report multiple sulfur isotope composition of sedimentary sulfates from a remote freshwater alpine lake near Mount Everest to reconstruct a two-century record of the atmospheric sulfur cycle. The sulfur isotopic anomaly is utilized as a probe for sulfur source apportionment and chemical transformation history. The nineteenth-century record displays a distinct sulfur isotopic signature compared with the twentieth-century record when sulfate concentrations increased. Along with other elemental measurements, the isotopic proxy suggests that the increased trend of sulfate is mainly attributed to enhancements of dust-associated sulfate aerosols and climate-induced weathering/erosion, which overprinted sulfur isotopic anomalies originating from other sources (e.g., sulfates produced in the stratosphere by photolytic oxidation processes and/or emitted from combustion) as observed in most modern tropospheric aerosols. The changes in sulfur cycling reported in this study have implications for better quantification of radiative forcing and snow/glacier melting at this climatically sensitive region and potentially other temperate glacial hydrological systems. Additionally, the unique Δ³³S-δ³⁴S pattern in the nineteenth century, a period with extensive global biomass burning, is similar to the Paleoarchean (3.6-3.2 Ga) barite record, potentially providing a deeper insight into sulfur photochemical/thermal reactions and possible volcanic influences on the Earth's earliest sulfur cycle.

Visualizing Volcanic Clouds in the Atmosphere and Their Impact on Air Traffic

Volcanic eruptions are not only hazardous in the direct vicinity of a volcano, but they also affect the climate and air travel for great distances. This article sheds light on the Grímsvötn, Puyehue-Cordón Caulle, and Nabro eruptions in 2011. The authors study the agreement of the complementary satellite data, reconstruct sulfate aerosol and volcanic ash clouds, visualize endangered flight routes, minimize occlusion in particle trajectory visualizations, and focus on the main pathways of Nabro's sulfate aerosol into the stratosphere. The results here were developed for the 2014 IEEE Scientific Visualization Contest, which centers around the fusion of multiple satellite data modalities to reconstruct and assess the movement of volcanic ash and sulfate aerosol emissions. Using data from three volcanic eruptions that occurred in the span of approximately three weeks, the authors study the agreement of the complementary satellite data, reconstruct sulfate aerosol and volcanic ash clouds, visualize endangered flight routes, minimize occlusion in particle trajectory visualizations, and focus on the main pathways of sulfate aerosol into the stratosphere. This video provides animations of the reconstructed ash clouds. https://youtu.be/D9DvJ5AvZAs.