Antarctic Station Research Articles

Verification of the regional atmospheric model CCLM v5.0 with conventional data and lidar measurements in Antarctica

Abstract. The nonhydrostatic regional climate model CCLM was used for a long-term hindcast run (2002–2016) for the Weddell Sea region with resolutions of 15 and 5 km and two different turbulence parametrizations. CCLM was nested in ERA-Interim data and used in forecast mode (suite of consecutive 30 h long simulations with 6 h spin-up). We prescribed the sea ice concentration from satellite data and used a thermodynamic sea ice model. The performance of the model was evaluated in terms of temperature and wind using data from Antarctic stations, automatic weather stations (AWSs), an operational forecast model and reanalyses data, and lidar wind profiles. For the reference run we found a warm bias for the near-surface temperature over the Antarctic Plateau. This bias was removed in the second run by adjusting the turbulence parametrization, which results in a more realistic representation of the surface inversion over the plateau but resulted in a negative bias for some coastal regions. A comparison with measurements over the sea ice of the Weddell Sea by three AWS buoys for 1 year showed small biases for temperature around ±1 K and for wind speed of 1 m s−1. Comparisons of radio soundings showed a model bias around 0 and a RMSE of 1–2 K for temperature and 3–4 m s−1 for wind speed. The comparison of CCLM simulations at resolutions down to 1 km with wind data from Doppler lidar measurements during December 2015 and January 2016 yielded almost no bias in wind speed and a RMSE of ca. 2 m s−1. Overall CCLM shows a good representation of temperature and wind for the Weddell Sea region. Based on these encouraging results, CCLM at high resolution will be used for the investigation of the regional climate in the Antarctic and atmosphere–ice–ocean interactions processes in a forthcoming study.

Variations of methane in the Antarctic atmosphere in 2009–2017 by ground-based and satellite data

The article presents the results of systematic measurements (2009−2017) of the total column abundances of methane (TC_CH4 ) and the column-averaged concentration (X_CH4 ) at the Antarctic station Novolazarevskaya. Solar radiation is recorded in the range 2990 – 3006 cm–1 using a diffraction spectrometer with 0.2 cm–1 resolution. The inverse task CH4 total column determining is achieved using the SFIT4 v0.9.4.4 code. The analysis shows that during the measurement period the average TC_CH4 was (3.4±0.8).1019 molecules/cm2 during the measurement period, and the average X_CH4 is (1663±34) ppbv. TC_CH4 trend is (4.5±2.2).1015 molecules/cm2 /month, and X_CH4 trend is (0.28 ± 0.11) ppbv/month. The average TC_CH4 values and trend at Novolazarevskaya are in good agreement with the measurements by the Brucker120HR instrument at the Arrival Heights station. Seasonal variations of atmospheric methane have the maximum in October–November and the minimum in May–July. The trends of surface methane concentrations at Sywa, the Halley station and the Amundsen-Scott South Pole station are 0.59 – 0.61 ppbv/month and exceed the trend of the column-averaged concentration at Novolazarevskaya and AIRS trends for the troposphere (0.24 – 0.32) ppbv/month, due to a decrease in the maximal values of TC_CH4 in the period after 2014. The closest agreement of X_CH4 variations at Novolazarevskaya with AIRS data is observed at the levels of 150–200 hPa. Significant semiannual harmonics varied with height are characteristic of CH4 variations according to the AIRS data. The interference of annual and semiannual harmonics leads to the appearance of two maxima in the seasonal variations of methane with relative position to each other varies with height. The statistical model is developed for all the series considered. It approximates the trend, annual and semi-annual components of CH4 oscillations.The authors have no competing interests.

Characterization of gravity waves in the lower ionosphere using very low frequency observations at Comandante Ferraz Brazilian Antarctic Station

Abstract. The goal of this work is to investigate the gravity wave (GW) characteristics in the low ionosphere using very low frequency (VLF) radio signals. The spatial modulations produced by the GWs affect the conditions of the electron density at reflection height of the VLF signals, which produce fluctuations of the electrical conductivity in the D region that can be detected as variations in the amplitude and phase of VLF narrowband signals. The analysis considered the VLF signal transmitted from the US Cutler, Maine (NAA) station that was received at Comandante Ferraz Brazilian Antarctic Station (EACF, 62.1∘ S, 58.4∘ W), with its great circle path crossing the Drake Passage longitudinally. The wave periods of the GWs detected in the low ionosphere are obtained using the wavelet analysis applied to the VLF amplitude. Here the VLF technique was used as a new aspect for monitoring GW activity. It was validated comparing the wave period and duration properties of one GW event observed simultaneously with a co-located airglow all-sky imager both operating at EACF. The statistical analysis of the seasonal variation of the wave periods detected using VLF technique for 2007 showed that the GW events occurred all observed days, with the waves with a period between 5 and 10 min dominating during night hours from May to September, while during daytime hours the waves with a period between 0 and 5 min are predominant the whole year and dominate all days from November to April. These results show that VLF technique is a powerful tool to obtain the wave period and duration of GW events in the low ionosphere, with the advantage of being independent of sky conditions, and it can be used during the whole day and year-round.

Occurrence characteristics of electromagnetic ion cyclotron waves at sub-auroral Antarctic station Maitri during solar cycle 24

We present a statistical study of electromagnetic ion cyclotron (EMIC) waves observed at Antarctic station (geographic 70.7{^circ },hbox {S}, 11.8{^circ },hbox {E}, L=5) on quiet and disturbed days during 2011–2017. The data span a fairly good period of both ascending and descending phases of the solar cycle 24, which has witnessed extremely low activity. We noted EMIC wave occurrence by examining wave power in different frequency ranges in the spectrogram. EMIC wave occurrence during ascending and descending phases of solar cycle 24, its local time, seasonal dependence and durations have been examined. There are total 2367 days for which data are available. Overall, EMIC waves are observed for 3166.5 h (approx 5.57% of total duration) which has contributions from 1263 days. We find a significantly higher EMIC wave occurrence during the descending phase (approx 6.83%) as compared to the ascending phase (approx 4.08%) of the solar cycle, which implies nearly a twofold increase in EMIC wave occurrence. This feature is attributed to the higher solar wind dynamic pressure during descending phase of solar activity. There is no evident difference in the percentage occurrence of EMIC waves on magnetically disturbed and quiet days. On ground, EMIC waves show marginally higher occurrence during winter as compared to summer. This seasonal tendency is attributed to lower electron densities and conductivities in the ionosphere, which can affect the propagation of EMIC waves through ionospheric ducts. In local time, the probability distribution function of EMIC wave occurrence shows enhancement during 11.7–20.7 LT (i.e., afternoon–dusk sector). Daily durations of EMIC waves are in the range of 5–1015 min and it is noted that the longer duration (240–1015 min) events are prevalent on quiet days and are mostly seen during the descending phase of solar cycle.

Variations of global thunderstorm activity derived from the long-term Schumann resonance monitoring in the Antarctic and in the Arctic

The paper analyzes the records of the magnetic components of the Schumann resonance signals obtained at the Ukrainian Antarctic station “Akademik Vernadsky” (coordinates: 65.25° S, 64.25° W) from March 2002 to March 2019 and at Svalbard in the Arctic (coordinates: 78.15° N and 16.05° E) from October 2013 to June 2019. The time-course is studied of the monthly average intensities and peak frequencies of the first Schumann resonance maximum, as well as the background noise intensity at the first minimum. Both observed parameters demonstrate periodic seasonal variations. The intensities are in-phase in different hemispheres while the peak frequencies are in anti-phase. Another feature of the resonance signals is interannual trend of the resonance intensity and peak frequency observed in both hemispheres being synchronous with 11-year solar cycle. The background noise intensities demonstrate the absence of appreciable interannual variations. We propose the following interpretation of these results. Seasonal changes in peak frequencies are determined by the regular meridian drift of the world thunderstorm centers up to ±(18°–26°) in latitude from the equator. Seasonal variations of the intensity are controlled by changes of thunderstorm activity that increase of about 1.5 times during the boreal summer compared with the winter. World thunderstorm activity is practically independent on the phase of the solar cycle. The observed interannual trends in the parameters of the first Schumann mode are determined by the global changes in the lower ionosphere. They can be explained by increasing of the upper (magnetic) characteristic height by 2–3 km due to additional ionization during the years of maximum solar activity. Another explanation might be an increase of the lower (electric) characteristic height by 1–1.5 km during the years of the quiet Sun due to variation of the flux of galactic cosmic rays. Moreover, we showed that involvement of ionosphere conductivity profiles in the point source model accounting their seasonal drift provides reliable estimating the global thunderstorms’ centers activities. To explain a behavior of the intensity changes recorded in the Antarctic observatory a mechanism of additional modulation of the local resonant cavity parameters within the solar cycle is required.

Subjective time estimation in Antarctica: The impact of extreme environments and isolation on a time production task

Interval timing measures time estimation in the seconds-to-minutes range. Antarctica provides a real-world context to study the effect of extreme photoperiods and isolation on time perception. The aim of this study was to explore interval timing as a cognitive measure in the crew of Belgrano II Argentine Antarctic Station. A total of 13 subjects were assessed for interval timing in short (3 s), intermediate (6 s) and long (12 s) duration stimuli. Measures were taken during the morning and evening, five times along the year. Significant variations were found for 3 s and 6 s during the morning and 6 s during the evening. Results suggest an impact of isolation on morning performances and an effect of the polar night on evening measures. These findings shed some light on the use of interval timing as a cognitive test to assess performance in extreme environments.

Results of Long-term Observations of Total Ozone in Antarctica and over the Atlantic and Southern Oceans

The study presents the results of analysis of observational data on total ozone (TO) at the Russian Antarctic stations Mirny, Novolazarevskaya, and Vostok for 1975–2019 and on the research vessels for 2005–2019. A steady trend towards the TO decrease in Antarctic spring was observed till the early 2000s. Currently, there is a tendency of returning TO values to those typical of the period preceding the manifestation of the ozone hole effect.

Establishment of Chart Datum and Vertical Datum Transformation for Hydrography in the Chinese Great Wall Bay, Antarctic Peninsula

AbstractThe Great Wall bay has become an important investigation area due to the establishment of the Chinese Antarctic Great Wall scientific research station. Establishing a seamless chart datum a...

Impacts of the Cryosphere and Atmosphere on Observed Microseisms Generated in the Southern Ocean

The Southern Ocean (in the region 60–180° E) south of the Indian Ocean, Australia, and the West Pacific is noted for the frequent occurrence and severity of its storms. These storms give rise to high‐amplitude secondary microseisms from sources, including the deep ocean regions, and primary microseisms where the swells impinge on submarine topographic features. A better understanding of the varying microseism wavefield enables improvements to seismic imaging and development of proxy observables to complement sparse in situ wave observations and hindcast models of the global ocean wave climate. We analyze 12–26 years of seismic data from 11 seismic stations either on the East Antarctic coast or sited in the Indian Ocean, Australia, and New Zealand. The power spectral density of the seismic wavefield is calculated to explore how the time‐changing microseism intensity varies with (i) sea ice coverage surrounding Antarctica and (ii) the Southern Annular Mode (SAM) climate index. Variations in sea ice extent are found to be the dominant control on the microseism intensity at Antarctic stations, which exhibit a seasonal pattern phase‐shifted by 4–5 months compared to stations in other continents. Peaks in extremal intensity at East Antarctic stations occur in March–April, with the highest peaks for secondary microseisms occurring during negative SAM events. This relationship between microseism intensity and the SAM index is opposite to that observed on the Antarctic Peninsula. This work informs the complexity of microseism amplitudes in the Southern Hemisphere and assists ongoing interdisciplinary investigations of interannual variability and long‐term trends.

Thermohaline Structure of Water in Antarctic Coastal Areas in March–April 2019 Derived from the 64th Russian Antarctic Expedition Measurements

The thermohaline structure of water in the Antarctic coastal areas adjoining Molodezhnaya, Novolazarevskaya, and Bellingshausen stations is analyzed using many-hour soundings carried out in March–April 2019 during the 64th Russian Antarctic Expedition on the Akademik Fedorov research vessel. Water masses typical of the Antarctic zone (Antarctic surface, Antarctic shelf, Antarctic winter, upper circumpolar deep water, Bransfield Strait surface water) are identified, and the features of their temporal variability are described. It is shown that intradaily and interdaily variations in water temperature and salinity were observed during the measurement period. The changes in the water structure in the area of Molodezhnaya, Novolazarevskaya, and Bellingshausen stations occurred under changes in synoptic atmospheric conditions, and their frequency was close to that of tidal processes.

Organic Compounds in the Antarctic Coastal Ecosystem

The paper presents the results of studying the granulometric composition of aerosol in the suspended matter of the surface water layer, and organic compounds (hydrocarbons, lipids, suspended organic carbon, chlorophyll a) in surface water at the sublatitudinal section near the Antarctica coast obtained in 2019 (the 64th Russian Antarctic Expedition). Snow, soil, and moss in the region of Antarctic stations Molodezhnaya, Novolazarevskaya, and Bellingshausen were also investigated. The results were compared with earlier data.

Glycerols and fatty acids isolated from Micractinium sp. KSF0031

From the collected extract from King Sejong Antarctic Station, strain Micractinium sp. KSF0031, led to the isolation of one new monoacyldigalactosyl glycerol (1) and seven known compounds (2–8). Their chemical structures were established using extensive spectroscopic techniques, including 1D, 2D-NMR, and MS, and compared with the published data. To the best of our knowledge, this is the first report to investigate the secondary metabolites from genus Micractinium. The monoacyldigalactosyl glycerol in Micractinium could serve as its chemotaxonomic markers.

Design strategies for the Brazilian Antarctic Station Comandante Ferraz

Design strategies for the Brazilian Antarctic Station Comandante Ferraz

ГЕОЛОГІЧНА БУДОВА ТА ПЕТРОГРАФІЯ ОСТРОВІВ ВЕДЕЛЬ (АРХІПЕЛАГ ВІЛЬГЕЛЬМА, ЗАХІДНА АНТАРКТИКА)

The Vedel Islands are a small island group that is part of the Wilhelm archipelago in the West Antarctica. They are located near the Graham Coast of the Antarctic Peninsula at a distance of 12 km from Akademik Vernadsky Ukrainian Antarctic Station. Until recently, the Vedel Islands were a "white spot" on all existing geological maps. In 2019, during the seasonal work of the 24th Ukrainian Antarctic expedition, the authors first carried out field geological researches on the Vedel Islands. The main goal of the geological survey was reconnaissance and large-scale geological mapping. The general ideas about the geological structure of the study area were developed by further processing of the collected materials. The preliminary data about the mode of occurrence, the geological ages, the petrographic peculiarities and the ore potential of the local rocks were also obtained. It was first established that multiple-aged intrusive-magmatic formations take part in the geological structure of the Vedel Islands. The intermediate compositions of the plutonic rocks namely the diorites and quartz diorites are the most common among them. The gabbroids and the tonalites are less common. The least common ones are hypabyssal and subvolcanic dike rocks namely microdiorites and diabases. The plutonic rocks were formed in at least three intrusive phases with a homodromous order of their intrusions. The most ancient among them are gabbroids. The Early Cretaceous age for their formation is assumed by analogy with the petrographically similar rocks of the Tuxen-Rasmussen layered gabbroid intrusion (TRGI). The tonilites are the youngest plutonic rocks on the Vedel Islands. It is assumed that their formation at a deep level took place in the Late Cretaceous, although their tectonic exhumation and the final erosion outcropping occurred in the Paleogene and ended in the Neogene. In the process of the exhumation, the plutonic rocks were intruded by hypabyssal dikes of microdiorites. The youngest subvolcanic diabase dykes intruded the tonalites supposedly after their complete erosion outcropping i. e. in Neogene or even Quaternary. Like TRGI and other layered gabbroid intrusions of the Wilhelm archipelago, the Vedel island gabbroids contain iron-titanium oxide-ore and copper-silicate mineralization, which requires further study. The additional researches are also needed to clarify the age, origin, petrography and mineralogy of the numerous veins of aplite-pegmatoid granite which intrude gabbroids and diorites on the Vedel Islands.

The Petrology of Gabbroids of the Anagram Islands (Wilhelm Archipelago, West Antarctica)

The Anagram Islands are located near the Graham Coast of West Antarctica not far from the Ukrainian Antarctic Station "Akademik Vernadsky". Gabbroids that are probably Cretaceous in age predominate in the geological structure of the Anagram Islands. New data on the mode of occurrence of the Anagram gabbroids and their layering were obtained during the seasonal field works of the Ukrainian Antarctic Expeditions in 2017, 2019-2020 years. Samples of the gabbroids were examined by optical microscopy, electron microscopy and microprobe analysis as well as by measuring of anisotropy of magnetic susceptibility of rocks. The goal of the research was to clarify the geological position and petrographic features of the Anagram gabbroids, to determine the typomorphic features of rock-forming minerals, and to clarify the origin of the layering in gabbroids. It was determined that the bottom part of a large layered gabbroid intrusion is fragmentarily exposed on the Anagram Islands. The continuation of the intrusion is expected in the northeastern and southeastern directions. It was established that primary magmatic textures and mineral composition are preserved in the gabbroids despite the development of metamorphic amphibolization. The gabbroids show typical cumulative textures of magmatic origin. The main cumulative phases are plagioclase (An70-95), clinopyroxene (Wo41-49En34-47), orthopyroxene (Wo2-4En49-71), olivine (Fo67-69), Ti-magnetite and ilmenite. It is proved that the fine rhythmic-gradational layering in the gabbroids was formed by gravitational precipitation of the cumulative minerals on the bottom of the magma chamber and their further sorting by specific gravity due to convection currents. Cryptic layering is firstly discovered in the Anagram gabbroids and is explained by the processes of crystallization differentiation. The latter caused the accumulation of the most calcium plagioclases and the most magnesian mafic minerals in the layered gabbroids forming the bottom part of the intrusion. The present subvertical position of layering is explained by tectonic deformation that resulted in the tilting of the investigated section of the Anagram gabbroid intrusion. This confirmed by the studying of magnetic texture of the gabbroids (by the anisotropy of magnetic susceptibility data).

Management of safe behavior to maintain life at the Brazilian Antarctic Station

Management of safe behavior to maintain life at the Brazilian Antarctic Station

Hydrochemical composition of glacial lakes on inshore Russian Antarctic stations

This paper reviews the chemical composition of 12 Antarctic lakes at offshore Russian stations in the period of seasonal work 55 and 58 RAE (Russian Antarctic Expedition) in December-January 2009–2010 and 2013–2014. Results of hydrochemical analyses of lake water, as well as their classification by ion composition, organic matter content, and mineralization, are presented in this paper. Low-level content of microelements in lake waters are also presented. Enrichment factors of lake waters in relation to ocean water were calculated and direct stratification of water from the surface to the bottom of Lake Progress was identified.

Стратиграфія району Української антарктичної станції «Академік Вернадський»

In 2019 and 2017, the authors performed field geological research on the Graham Coast of the Antarctic Peninsula. The studied area covered the western coast of the Kiev Peninsula and most of the adjacent islands of the Wilhelm Archipelago. The main objective of the study was to specify the stratigraphic column for the Ukrainian Antarctic Station (UAS) area, to determine the petrographic composition and lithological features of strata, to find out the features of their occurrence and the succession of accumulation. Research methods included: large-scale geological surveying and geological mapping. The main result was the development of a new stratigraphic scheme for the UAS area. The authors found that the studied stratigraphic column was composed of volcanic and subordinate terrigenous deposits. Their accumulation lasted in the time interval from late Palaeozoic to Cenozoic inclusive. The conclusions have been made about to the origin of studied strata, their ages and possible analogues in neighbouring territories. Lahille Island Formation (LIF) was recognized as the oldest lithostratigraphic unit of the studied area. Deep-sea turbid origin is assumed for the LIF terrigenous rocks. The TTL sedimentation age is limited by the time interval between the Late Permian and Early Triassic periods. On the basis of lithological features and geological age, TTL correlates with the Paradise Harbour formation belonging to the Trinity Peninsula Group. The most widespread lithostratigraphic unit of the study area is the volcanic strata of the Kiev Peninsula, which is a product island-arc volcanism associated with the Andean orogeny. The age of KPF volcanism is defined as Jurassic. It is found that the volcanic stratum of the Argentine Islands Formation (AIF) differs from the KPF by the petrographic composition, occurrence and features of stratification. It gave grounds to separate AIF into an independent lithostratigraphic unite. The age of AIF volcanism is limited by the time interval between the Jurassic and Cretaceous periods. According to lithological features and geological age, KPF and AIF were identified as the members of Antarctic Peninsula Volcanic Group. An assumption about the possible presence of the latest volcanogenic rocks of Neogene or even Quaternary age on the Argentinean Islands is made.

Dynamics of Numbers and Occurrence of Colonial Species of Birds in the Area of Ukrainian Antarctic Station Akademik Vernadsky

Abstract The research covers water area, island archipelagos and coastal line of the Antarctic Peninsula from 65°31ʹ S, 64°25ʹ W in the South to 65°03ʹ S, 63°53ʹ W in the North. There was time gap of 7 years between the researches (2011 and 2018), which allows to define tendencies in development of individual colonies and to make conclusion about success of existence of a given species. The work itself was carried out during the first half of January, that is in the time when the stage of brooding ends and the period of hatching starts. As of 2011, 12 nesting points of gentoo penguin (Pygoscelis papua) with total number of 8,342 pairs were found in the region under investigation. Till 2018, quantity of the colony grew to 14, with total number of 14,105 pairs. For seven years, quantity of nesting points of aelie penguin (Pygoscelis adeliae) almost did not change (4 colonies). Instead, total number of the species decreased somewhat: from 3559 pairsin 2011 to 3295 onesin 2018. Number of chinstrap penguin (Pygoscelis antarctica) in united stable locality for nesting also decreased from 26 pairsin 2011 to19 onesin 2018. Booth Island (65°04ʹ S, 64°02ʹ W) for chinstrap penguins and Green Island (65°19ʹ S, 64°09ʹ W) for gentoo penguins are the southern most points of nesting range of the species. Also, 7 colonies of antarctic shag (Phalacrocorax bransfieldensis) were revealed in the region under investigation. For seven years from 2011 to 2018 total number of the species in the region under investigation grew from 190 pairs to 299, and in most cases the antarctics shag forms settlements jointly with penguins.

One year of aerosol refractive index measurement from a coastal Antarctic site

Abstract. Though the environmental conditions of the Weddell Sea region and Dronning Maud Land are still relatively stable compared to the fast-changing Antarctic Peninsula, we may suspect pronounced effects of global climate change for the near future (Thompson et al., 2011). Reducing the uncertainties in climate change modeling requires a better understanding of the aerosol optical properties, and for this we need accurate data on the aerosol refractive index (RI). Due to the remoteness of Antarctica only very few RI data are available from this region (Hogan et al., 1979; Virkkula et al., 2006; Shepherd et al., 2018). We calculate the real refractive index of natural atmospheric aerosols from number size distribution measurements at the German coastal Antarctic station Neumayer III. Given the high average scattering albedo of 0.992 (Weller et al., 2013), we assumed that the imaginary part of the RI is zero. Our method uses the overlapping size range (particle diameter D between 120 and 340 nm) of a scanning mobility particle sizer (SMPS), which sizes the particles by their electrical mobility, and a laser aerosol spectrometer (LAS), which sizes the particles by their optical scattering signal at the 633 nm wavelength. Based on almost a complete year of measurement, the average effective refractive index (RIeff, as we call our retrieved RI because of the used assumptions) for the dry aerosol particles turned out to be 1.44 with a standard deviation of 0.08, in a good agreement with the RI value of 1.47, which we derived from the chemical composition of bulk aerosol sampling measurements. At Neumayer the aerosol shows a pronounced seasonal pattern in both number concentration and chemical composition. Despite this, the variability of the monthly averaged RIeff values remained between 1.40 and 1.50. Compared to the annual mean, two austral winter months (July and September) showed slightly but significantly increased values (1.50 and 1.47, respectively). The size dependency of the RIeff could be determined from time-averaged LAS and SMPS number size distributions measured between December 2017 and January 2018. Here we calculated RIeff for four different particle size ranges and observed a slight decrease from 1.47 (D range 116–168 nm) to 1.37 (D range 346–478 nm). We find no significant dependence of the derived RIeff values on the wind direction. Thus we conclude that RIeff is largely independent of the general weather situation, roughly classified as (i) advection of marine boundary layer air masses during easterly winds caused by passing cyclones in contrast to (ii) air mass transport from continental Antarctica under southern katabatic winds. Neumayer, the only relevant contamination source, is located 1.5 km north of the air chemistry observatory, where the measurements were performed. Given that northerly winds are almost absent, the potential impact of local contamination is minimized in general. Indeed our data show no impact of local contamination on RIeff. Just in one case a temporary high-contamination episode with diesel engines operating right next to the measurement site resulted in an unusual high RIeff of 1.59, probably caused by the high black carbon content of the exhaust fumes. To conclude, our study revealed largely constant RIeff values throughout the year without any sign of seasonality. Therefore, it seems reasonable to use a single, constant RIeff value of 1.44 for modeling optical properties of natural, coastal Antarctic sub-micrometer aerosol.