In recent years, airborne microplastics have been identified in a range of remote environments. However, data throughout the Southern Hemisphere, in particular Antarctica, are largely absent to date. We collected snow samples from 19 sites across the Ross Island region of Antarctica. Suspected microplastic particles were isolated and their composition confirmed using micro-Fourier transform infrared spectroscopy (µFTIR). We identified microplastics in all Antarctic snow samples at an average concentration of 29 particles L⁻¹, with fibres the most common morphotype and polyethylene terephthalate (PET) the most common polymer. To investigate sources, backward air mass trajectories were run from the time of sampling. These indicate potential long-range transportation of up to 6000 km, assuming a residence time of 6.5 d. Local sources were also identified as potential inputs into the environment as the polymers identified were consistent with those used in clothing and equipment from nearby research stations. This study adds to the growing body of literature regarding microplastics as a ubiquitous airborne pollutant and establishes their presence in Antarctica.

Coupled Model Intercomparison Project Phase 6 (CMIP6) models are analyzed using an established cloud clustering methodology. This enables a comparison of cloud representation in models and observations. The simulation of stratocumulus clouds over the Southern Ocean is shown to have changed substantially from earlier generation models. The CMIP6 models analyzed show stratocumulus clouds now occur more often in simulations than in International Satellite Cloud Climatology Project (ISCCP) observations, but are not bright enough compared to Clouds and the Earth's Radiant Energy System (CERES) data. This is in contrast to the “too few, too bright” problem, which has characterized prior model simulations of stratocumulus clouds, particularly over the Southern Ocean. The cloud clusters also enable the calculation of mean and compensating shortwave cloud radiative effect (SW CRE) errors from model data. The compensating errors are shown to be much larger than mean errors suggesting the CMIP6 models still have much to improve in their cloud representation. A statistically significant negative relationship between the mean and compensating errors in SW CRE over the Southern Ocean is identified. This relationship is observed elsewhere, but is only significant over the Southern Ocean. This implies model tuning efforts are hiding biases in the representation of clouds in this region. CMIP6 models have been shown to have a higher equilibrium climate sensitivity (ECS) relative to CMIP5 simulations. The link between ECS and SW CRE mean and compensating errors is investigated but no evidence of a relationship between these variables was found.

The seasonal, geographical, and altitudinal dependence of gravity wave activity in the lower stratosphere over Antarctica is presented. Gravity wave activity is estimated by calculating potential energy, E_p, from radio occultation profiles obtained by the Challenging Minisatellite Payload/Global Positioning System (CHAMP/GPS) experiment. Significant seasonal variation of wave activity is observed. Smaller wave activity in summer is attributed to waves with small phase velocities experiencing critical level filtering. At other times of the year, when wave activity is large, less filtering occurs and the strong background wind is likely to cause Doppler shifting of waves to longer vertical wavelengths, which can reach larger amplitudes before saturating. Relationships between gravity wave activity and geographic location indicate that topography is a strong source for wave activity especially over the Antarctic Peninsula. However, wind rotation in this area was found to reduce the wave energy in summer at certain altitudes. A strong enhancement of wave energy is observed at the edge of the polar vortex. Again, reduced critical level filtering and Doppler shifting in the area of the jet are likely to be major causes for this finding. Possible limitations to this study due to observational filtering are discussed.

A function that approximates atmospheric tidal behavior in the polar regions is described. This function is fitted to multistation radar measurements of wind in the mesosphere and lower thermosphere with the aim of obtaining a latitude‐longitude‐height description of the variation of tides over the whole Antarctic continent. Archival wind data sets are combined with present‐day ones to fill the spatial distribution of the observations and to reduce the potential effects of spatial aliasing. Multiple years are combined through the compilation of monthly station composite days, yielding results for each month of the year. Despite potential problems associated with year‐to‐year variations in the tidal phase, a useful climatology of Antarctic zonal and meridional tidal wind components is compiled. The results of the fits reproduce the major features of the high‐latitude tidal wind field: the dominance of the semidiurnal migrating mode in the winter months and the presence of a semidiurnal zonal wave number one component in the summer months. It is also found that the summer semidiurnal tide contains a zonal wave number zero component.