Abstract: We analyze the long-range transport to high latitudes of a smoke particle filament originating from the extratropics plume after the Australian wildfires colloquially known as “Black Saturday” on 7 February and report the first Antarctic stratospheric lidar characterization of such aerosols. Using a high-resolution transport/microphysical model, we show that the monitoring cloud/aerosol lidar instrument operating at the French Antarctic station Dumont d'Urville (DDU, 66°S to 140°E) recorded a signature of those aerosols. The 532 nm scattering ratio of this filament is comparable to typical moderate stratospheric volcanic plume, with values between 1.4 and 1.6 on the first and third days of March above DDU station at around the 14 and 16 km altitude, respectively. A dedicated model is described and its ability to track down fine optical signatures is validated against Antarctic lidar elastic aerosol and DIAL ozone measurements. Using 1 month of tropical Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data to support a relatively simple microphysical scheme, we report modeled aerosol presence above DDU station after advection of the aerosol size distribution. In situ measurements also report associated positive ozone anomaly. This case study provides evidence that biomass burning events injecting significant amounts of material up to stratospheric altitudes can be transported toward high latitudes. We highlight a potential imprint of smoke particles on the Antarctic atmosphere over larger time scales. Any underestimation of the global impact of such deep particle transport will lead to uncertainties in modeling the associated chemical or radiative effects, especially in polar regions, where specific microphysical and chemical processes take place.

Abstract: Significant environmental changes have already been documented in the Southern Ocean (e.g. sea water temperature increase and salinity drop) but its marine life is still incompletely known given the heterogeneous nature of biogeographic data. However, to establish sustainable conservation areas, understanding species and communities distribution patterns is critical. For this purpose, the ecoregionalization approach can prove useful by identifying spatially explicit and well-delimited regions of common species composition and environmental settings. Such regions are expected to have similar biotic responses to environmental changes and can be used to define priorities for the designation of Marine Protected Areas. In the present work, a benthic ecoregionalization of the Southern Ocean is proposed based on echinoids distribution data and abiotic environmental parameters. Echinoids are widely distributed in the Southern Ocean, they are taxonomically and ecologically well diversified and documented. Given the heterogeneity of the sampling effort, predictive spatial models were produced to fill the gaps in between species distribution data. A first procedure was developed using Gaussian Mixture Models (GMM) to combine individual species models into ecoregions. A second, integrative procedure was implemented using the Generalized Dissimilarity Models (GDM) to model and assemble species distributions. Both procedures were compared to propose benthic ecoregions at the scale of the entire Southern Ocean.

Abstract: In vertebrates, developmental conditions can affect not only fledging success but also the phenotype of the offspring, with potential long-term consequences on adult performance. However, surprisingly the potential impact of anthropogenic disturbance on developing chicks is rarely investigated, notably in Antarctic wildlife. In this study, we specifically investigated the effects of repeated nest visits, capture, and handling on offspring survival and several complementary offspring phenotypic traits in the Snow Petrel (Pagodroma nivea) chicks after thermal emancipation. We did not find any significant effect of our disturbance protocol on the morphology (body size, body mass, body condition), the physiology (breath rate, stress-induced corticosterone levels) and the behaviour (defense behaviour) of developing Snow Petrels. This specific disturbance protocol did not have any significant effect on chick survival, but there was a non-significant trend towards a lower survival for the disturbed group (p = 0.1006), which showed an especially high mortality during a period of repeated snow storms. To conclude, investigator disturbance seems to have little effect on Snow Petrel chicks after thermal emancipation, but to remain cautious, we recommend to avoid capture and handling of Snow Petrel chicks during or soon after inclement weather.

Abstract: We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time $\tau0$. Statistics and seasonal behaviour of $\tau0$ are given at two heights above the ground, 3m and 8m, for the wavelength $\lambda=500$nm. We found an annual median value of $2.9$ms at the height of 8m. A few measurements could also be obtained at the height of 20m and give a median value of 6ms during the period June--September. For the first time, we provide measurements of $\tau0$ in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5pm local time. Exceptional values of $\tau0$ above 10ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system.

Abstract:

Abstract. Drifting snow is a widespread feature over the Antarctic ice sheet, whose climatological and hydrological significance at the continental scale have been consequently investigated through modelling and satellite approaches. While field measurements are needed to evaluate and interpret model and satellite products, most drifting-snow observation campaigns in Antarctica involved data collected at a single location and over short time periods. With the aim of acquiring new data relevant to the observation and modelling of drifting snow in Antarctic conditions, two remote locations in coastal Adélie Land (East Antarctica) that are 100 km apart were instrumented in January 2010 with meteorological and second-generation IAV Engineering acoustic FlowCapt™ sensors. The data, provided nearly continuously so far, constitute the longest dataset of autonomous near-surface (i.e. within 2 m) measurements of drifting snow currently available over the Antarctic continent. This paper presents an assessment of drifting-snow occurrences and snow mass transport from up to 9 years (2010–2018) of half-hourly observational records collected in one of the Antarctic regions most prone to snow transport by wind. The dataset is freely available to the scientific community and can be used to complement satellite products and evaluate snow-transport models close to the surface and at high temporal frequency.