Here we present an ~2000 year high-resolution glaciochemical record from the South Pole. Significant changes in chemical concentrations, accumulation rate, stable water isotopes and deuterium excess records are captured during the period ~1400-1700 CE, indicating a reorganization of atmospheric circulation that occurred in two steps: ~1400-1425 CE and ~1650-1700 CE. Major declines in dust and SO42- concentrations are observed ~1400 CE suggesting poleward contraction of the southern circumpolar vortex and potential intensification of westerly air flow, accompanied by a sea ice decrease in the Weddell Sea and potentially also in the Indian sector of the Southern Ocean. The changes in stable water isotopes, deuterium excess, NO3- concentration and accumulation rate characterize a second shift in atmospheric reorganization between 1650-1700 CE, reflecting increased marine air mass intrusions and subsequent reduction of the katabatic winds, and a shift to a colder moisture source for South Pole precipitation. These internally consistent changes involving atmospheric circulations and sea ice conditions are also in line with those identified for the recent period, and include associations with the large-scale teleconnections of El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM).

An extended-range Single-Particle Soot Photometer (SP2) coupled to a Marin-5 nebulizer was used to measure the refractory black carbon (rBC) mass and number size distributions in 1004 samples from a West Antarctica snow/firn core. The SP2 was calibrated using Aquadag and a Centrifugal Particle Mass Analyzer for BC particles ranging from 0.5 to 800 fg. Our results from 1.03 x 10 particles indicate a significant contribution of rare, large particles of mass-equivalent diameter (D) > 500 nm to the total rBC mass (36%), while small particles (D < 100 nm) are abundant but contribute < 8% to total rBC mass. We observed a mass median diameter (MMD) of 160 nm, smaller than reported for snow comparing to other regions of the globe, but similar to East Antarctica rBC size distributions. In addition, we observed a secondary mode at 1880 nm, possibly originated from a combination of rBC aging processes in the atmosphere and particle agglomeration during snow formation/deposition. We compared two sets of samples from different seasons (wet vs. dry), and observed different contributions of large particles to the total rBC mass of each. Particles with D > 500 nm contributed 45% and 33% of the total rBC mass for the wet and dry season, respectively, indicating that larger particles are more common during the wet season. Post-depositional processes (millimeter thick melt layers) have been observed in some samples, although they did not change the observed median diameter. This study provides the first detailed rBC size distribution from West Antarctica.

Current changes in tropical South America due to atmospheric warming, deforestation, and glacier retreat impact moisture and water exchange between the Amazon basin and the Andes. Thus, a deeper understanding of past atmospheric variability is crucial for developing strategies for climate and environmental change scenarios in this region. Within this context, we investigated an 18-year firn core drilled at the Illimani to interpret its aerosol composition (trace elements and major ions) in relation to seasonal processes, particularly atmospheric circulation over the Amazon basin. The resulting 21st-century record showed reduced Cr contamination over the Altiplano in comparison to the late 20th century, which was probably related to reduced emissions from mining activities. Sulfur records suggest the influence of volcanic eruptions in 2006 (Rabaul) and 2014 (Nyamuragira-Nyiragongo). Overall, the aerosol composition was mainly modulated by precipitation variability over the Altiplano at both annual and seasonal timescales. However, Mn was enriched due to strengthened low-level jets in the Amazon basin during the dry season, especially in 2015. This was corroborated by the reanalysis data. Furthermore, Mn, Co, and Fe showed an unprecedented peak in the record during the wet season of 2014, which was consistent with the arrival of a dust plume from Africa over Amazonia. Therefore, the Mn enrichment record can be used as a new proxy for obtaining information about the South American Low-Level Jet, and, when considered together with more elements, might also indicate snow layers that were possibly loaded with aerosols from Africa.