|
Records |
Links |
|
Author |
Karl-Ludwig Klein, Sophie Musset, Nicole Vilmer, Carine Briand, Säm Krucker, Andrea Francesco Battaglia, Nina Dresing, Christian Palmroos, Dale E. Gary |
|
|
Title |
The relativistic solar particle event on 28 October 2021: Evidence of particle acceleration within and escape from the solar corona |
Type |
Journal |
|
Year |
2023 |
Publication |
Astronomy & Astrophysics |
Abbreviated Journal |
|
|
|
Volume |
663 |
Issue |
|
Pages |
A173 |
|
|
Keywords |
|
|
|
Abstract |
Aims. We analyse particle, radio, and X-ray observations during the first relativistic proton event of solar cycle 25 detected on Earth. The aim is to gain insight into the relationship between relativistic solar particles detected in space and the processes of acceleration and propagation in solar eruptive events.Methods. To this end, we used ground-based neutron monitor measurements of relativistic nucleons and space-borne measurements of electrons with similar speed to determine the arrival times of the first particles at 1 AU and to infer their solar release times. We compared the release times with the time histories of non-thermal electrons in the solar atmosphere and their escape to interplanetary space, as traced by radio spectra and X-ray light curves and images.Results. Non-thermal electrons in the corona are found to be accelerated in different regions. Some are confined in closed magnetic structures expanding during the course of the event. Three episodes of electron escape to the interplanetary space are revealed by groups of decametric-to-kilometric type III bursts. The first group appears on the low-frequency side of a type II burst produced by a coronal shock wave. The two latter groups are accompanied at higher frequencies by bursts with rapid drifts to both lower and higher frequencies (forward- or reverse-drifting bursts). They are produced by electron beams that propagate both sunward and anti-sunward. The first relativistic electrons and nucleons observed near Earth are released with the third group of type III bursts, more than ten minutes after the first signatures of non-thermal electrons and of the formation of the shock wave in the corona. Although the eruptive active region is near the central meridian, several tens of degrees east of the footpoint of the nominal Parker spiral to the Earth, the kilometric spectrum of the type III bursts and the in situ detection of Langmuir waves demonstrate a direct magnetic connection between the L1 Lagrange point and the field lines onto which the electron beams are released at the Sun.Conclusions. We interpret the forward- and reverse-drifting radio bursts as evidence of reconnection between the closed expanding magnetic structures of an erupting flux rope and ambient open magnetic field lines. We discuss the origin of relativistic particles near the Earth across two scenarios: (1) acceleration at the CME-driven shock as it intercepts interplanetary magnetic field lines rooted in the western solar hemisphere and (2) an alternative where the relativistic particles are initially confined in the erupting magnetic fields and get access to the open field lines to the Earth through these reconnection events. |
|
|
Programme |
227 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
0004-6361, 1432-0746 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8441 |
|
Permanent link to this record |
|
|
|
|
Author |
Florent Tencé, Julien Jumelet, Marie Bouillon, David Cugnet, Slimane Bekki, Sarah Safieddine, Philippe Keckhut, Alain Sarkissian |
|
|
Title |
14 years of lidar measurements of polar stratospheric clouds at the French Antarctic station Dumont d'Urville |
Type |
Journal |
|
Year |
2023 |
Publication |
Atmospheric chemistry and physics |
Abbreviated Journal |
|
|
|
Volume |
23 |
Issue |
1 |
Pages |
431-451 |
|
|
Keywords |
|
|
|
Abstract |
Polar stratospheric clouds (PSCs) play a critical role in the stratospheric ozone depletion processes. The last 30 years have seen significant improvements in our understanding of the PSC processes but PSC parametrization in global models still remains a challenge due to the necessary trade-off between the complexity of PSC microphysics and model parametrization constraints. The French Antarctic station Dumont d'Urville (DDU, 66.6∘ S, 140.0∘ E) has one of the few high latitude ground-based lidars in the Southern Hemisphere that has been monitoring PSCs for decades. This study focuses on the PSC data record during the 2007–2020 period. First, the DDU lidar record is analysed through three established classification schemes that prove to be mutually consistent: the PSC population observed above DDU is estimated to be of 30 % supercooled ternary solutions, more than 60 % nitric acid trihydrate mixtures and less than 10 % of water–ice dominated PSC. The Cloud–Aerosol Lidar with Orthogonal Polarization PSC detection around the station are compared to DDU PSC datasets and show a good agreement despite more water–ice PSC detection. Detailed 2015 lidar measurements are presented to highlight interesting features of PSC fields above DDU. Then, combining a temperature proxy to lidar measurements, we build a trend of PSC days per year at DDU from ERA5 (the fifth generation of European ReAnalysis) and NCEP (National Centers for Environment Protection reanalysis) reanalyses fitted on lidar measurements operated at the station. This significant 14-year trend of −4.6 PSC days per decade is consistent with recent temperature satellite measurements at high latitudes. Specific DDU lidar measurements are presented to highlight fine PSC features that are often sub-scale to global models and spaceborne measurements. |
|
|
Programme |
209 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1680-7316 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8491 |
|
Permanent link to this record |
|
|
|
|
Author |
Sarah Albertin, Joël Savarino, Slimane Bekki, Albane Barbero, Roberto Grilli, Quentin Fournier, Irène Ventrillard, Nicolas Caillon, Kathy Law |
|
|
Title |
Diurnal variations in oxygen and nitrogen isotopes of atmospheric nitrogen dioxide and nitrate: implications for tracing NOx oxidation pathways and emission sources |
Type |
Journal |
|
Year |
2023 |
Publication |
EGUsphere |
Abbreviated Journal |
|
|
|
Volume |
|
Issue |
|
Pages |
1-44 |
|
|
Keywords |
|
|
|
Abstract |
The oxygen (????17O) and nitrogen (????15N) isotopic compositions of atmospheric nitrate (NO3-) are widely used as tracers of its formation pathways, precursor (nitrogen oxides NOx = nitric oxide NO + nitrogen NO2) emission sources, and physico-chemical processing. However, the critical lack of observations on the multi-isotopic composition of NO2 maintains significant uncertainties regarding the links between the isotopic composition of NOx and NO3-, which may bias estimates of the NO3- formation processes and the distribution of sources. We report here on the first simultaneous atmospheric observations of ????17O and ????15N in NO2 and NO3-. The measurements were carried out at sub-daily (ca. 3 h) resolution over two non-consecutive days in an Alpine city in February 2021. Important diurnal variabilities are observed in both NO2 and NO3- multi-isotopic composition. ????17O of NO2 and NO3- range from 19.6 to 40.8 ‰ and 18.7 to 26 ‰, respectively. During both daytime and nighttime, the variability of ????17O(NO2) is mainly driven by the oxidation of NO by ozone, with a substantial contribution from peroxy radicals in the morning. NO3- local mass balance equations, constrained by observed ????17O(NO2), suggest that during the first day of sampling NO3- was formed locally from the oxidation of NO2 by hydroxyl radicals during the day, and via heterogeneous hydrolysis of dinitrogen pentoxide during the night. For the second day, calculated and observed ????17O(NO3-) do not match, particularly daytime values. The effects on ????17O(NO3-) of a Saharan dust event that occurred during the second day and winter boundary layer dynamics are discussed. ????15N of NO2 and NO3- ranged from -10.0 to 19.7 ‰ and -4.2 to 14.8 ‰, respectively. Consistent with theoretical predictions of N isotope fractionation, the important variability of ????15N(NO2) is explained by significant post-emission equilibrium N fractionation. After accounting for this effect, vehicle exhaust is found to be the primary source of NOx emissions at the sampling site. ????15N(NO3-) is closely linked to ????15N(NO2) variability, which bring further evidence of fast and local processing, but uncertainties on current N fractionation factors during NO2 to NO3- conversion are underscored. Overall, this detailed investigation highlights the potential and the necessity to use ????17O and ????15N in NO2 and NO3- to trace quantitatively the sources and formation chemistry of NO3-, particularly in urban environments in winter. |
|
|
Programme |
1215 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
|
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8022 |
|
Permanent link to this record |
|
|
|
|
Author |
Eleftherios Ioannidis, Kathy S. Law, Jean-Christophe Raut, Louis Marelle, Tatsuo Onishi, Rachel M. Kirpes, Lucia M. Upchurch, Thomas Tuch, Alfred Wiedensohler, Andreas Massling, Henrik Skov, Patricia K. Quinn, Kerri A. Pratt |
|
|
Title |
Modelling wintertime sea-spray aerosols under Arctic haze conditions |
Type |
Journal |
|
Year |
2023 |
Publication |
Atmospheric chemistry and physics |
Abbreviated Journal |
|
|
|
Volume |
23 |
Issue |
10 |
Pages |
5641-5678 |
|
|
Keywords |
|
|
|
Abstract |
Anthropogenic and natural emissions contribute to enhanced concentrations of aerosols in the Arctic winter and early spring, with most attention being paid to anthropogenic aerosols that contribute to so-called Arctic haze. Less-well-studied wintertime sea-spray aerosols (SSAs) under Arctic haze conditions are the focus of this study, since they can make an important contribution to wintertime Arctic aerosol abundances. Analysis of field campaign data shows evidence for enhanced local sources of SSAs, including marine organics at Utqiaġvik (formerly known as Barrow) in northern Alaska, United States, during winter 2014. Models tend to underestimate sub-micron SSAs and overestimate super-micron SSAs in the Arctic during winter, including the base version of the Weather Research Forecast coupled with Chemistry (WRF-Chem) model used here, which includes a widely used SSA source function based on Gong et al. (1997). Quasi-hemispheric simulations for winter 2014 including updated wind speed and sea-surface temperature (SST) SSA emission dependencies and sources of marine sea-salt organics and sea-salt sulfate lead to significantly improved model performance compared to observations at remote Arctic sites, notably for coarse-mode sodium and chloride, which are reduced. The improved model also simulates more realistic contributions of SSAs to inorganic aerosols at different sites, ranging from 20 %–93 % in the observations. Two-thirds of the improved model performance is from the inclusion of the dependence on SSTs. The simulation of nitrate aerosols is also improved due to less heterogeneous uptake of nitric acid on SSAs in the coarse mode and related increases in fine-mode nitrate. This highlights the importance of interactions between natural SSAs and inorganic anthropogenic aerosols that contribute to Arctic haze. Simulation of organic aerosols and the fraction of sea-salt sulfate are also improved compared to observations. However, the model underestimates episodes with elevated observed concentrations of SSA components and sub-micron non-sea-salt sulfate at some Arctic sites, notably at Utqiaġvik. Possible reasons are explored in higher-resolution runs over northern Alaska for periods corresponding to the Utqiaġvik field campaign in January and February 2014. The addition of a local source of sea-salt marine organics, based on the campaign data, increases modelled organic aerosols over northern Alaska. However, comparison with previous available data suggests that local natural sources from open leads, as well as local anthropogenic sources, are underestimated in the model. Missing local anthropogenic sources may also explain the low modelled (sub-micron) non-sea-salt sulfate at Utqiaġvik. The introduction of a higher wind speed dependence for sub-micron SSA emissions, also based on Arctic data, reduces biases in modelled sub-micron SSAs, while sea-ice fractions, including open leads, are shown to be an important factor controlling modelled super-micron, rather than sub-micron, SSAs over the north coast of Alaska. The regional results presented here show that modelled SSAs are more sensitive to wind speed dependence but that realistic modelling of sea-ice distributions is needed for the simulation of local SSAs, including marine organics. This study supports findings from the Utqiaġvik field campaign that open leads are the primary source of fresh and aged SSAs, including marine organic aerosols, during wintertime at Utqiaġvik; these findings do not suggest an influence from blowing snow and frost flowers. To improve model simulations of Arctic wintertime aerosols, new field data on processes that influence wintertime SSA production, in particular for fine-mode aerosols, are needed as is improved understanding about possible local anthropogenic sources. |
|
|
Programme |
1215 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1680-7316 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8504 |
|
Permanent link to this record |
|
|
|
|
Author |
Cynthia H. Whaley, Kathy S. Law, Jens Liengaard Hjorth, Henrik Skov, Stephen R. Arnold, Joakim Langner, Jakob Boyd Pernov, Garance Bergeron, Ilann Bourgeois, Jesper H. Christensen, Rong-You Chien, Makoto Deushi, Xinyi Dong, Peter Effertz, Gregory Faluvegi, Mark Flanner, Joshua S. Fu, Michael Gauss, Greg Huey, Ulas Im, Rigel Kivi, Louis Marelle, Tatsuo Onishi, Naga Oshima, Irina Petropavlovskikh, Jeff Peischl, David A. Plummer, Luca Pozzoli, Jean-Christophe Raut, Tom Ryerson, Ragnhild Skeie, Sverre Solberg, Manu A. Thomas, Chelsea Thompson, Kostas Tsigaridis, Svetlana Tsyro, Steven T. Turnock, Knut von Salzen, David W. Tarasick |
|
|
Title |
Arctic tropospheric ozone: assessment of current knowledge and model performance |
Type |
Journal |
|
Year |
2023 |
Publication |
Atmospheric Chemistry and Physics |
Abbreviated Journal |
|
|
|
Volume |
23 |
Issue |
1 |
Pages |
637-661 |
|
|
Keywords |
|
|
|
Abstract |
As the third most important greenhouse gas (GHG) after carbon dioxide (CO2) and methane (CH4), tropospheric ozone (O3) is also an air pollutant causing damage to human health and ecosystems. This study brings together recent research on observations and modeling of tropospheric O3 in the Arctic, a rapidly warming and sensitive environment. At different locations in the Arctic, the observed surface O3 seasonal cycles are quite different. Coastal Arctic locations, for example, have a minimum in the springtime due to O3 depletion events resulting from surface bromine chemistry. In contrast, other Arctic locations have a maximum in the spring. The 12 state-of-the-art models used in this study lack the surface halogen chemistry needed to simulate coastal Arctic surface O3 depletion in the springtime; however, the multi-model median (MMM) has accurate seasonal cycles at non-coastal Arctic locations. There is a large amount of variability among models, which has been previously reported, and we show that there continues to be no convergence among models or improved accuracy in simulating tropospheric O3 and its precursor species. The MMM underestimates Arctic surface O3 by 5 % to 15 % depending on the location. The vertical distribution of tropospheric O3 is studied from recent ozonesonde measurements and the models. The models are highly variable, simulating free-tropospheric O3 within a range of ±50 % depending on the model and the altitude. The MMM performs best, within ±8 % for most locations and seasons. However, nearly all models overestimate O3 near the tropopause (∼300 hPa or ∼8 km), likely due to ongoing issues with underestimating the altitude of the tropopause and excessive downward transport of stratospheric O3 at high latitudes. For example, the MMM is biased high by about 20 % at Eureka. Observed and simulated O3 precursors (CO, NOx, and reservoir PAN) are evaluated throughout the troposphere. Models underestimate wintertime CO everywhere, likely due to a combination of underestimating CO emissions and possibly overestimating OH. Throughout the vertical profile (compared to aircraft measurements), the MMM underestimates both CO and NOx but overestimates PAN. Perhaps as a result of competing deficiencies, the MMM O3 matches the observed O3 reasonably well. Our findings suggest that despite model updates over the last decade, model results are as highly variable as ever and have not increased in accuracy for representing Arctic tropospheric O3. |
|
|
Programme |
1215 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1680-7316 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8507 |
|
Permanent link to this record |
|
|
|
|
Author |
Federico Scoto, Gianluca Pappaccogli, Mauro Mazzola, Antonio Donateo, Roberto Salzano, Matteo Monzali, Fabrizio de Blasi, Catherine Larose, Jean-Charles Gallet, Stefano Decesari, Andrea Spolaor |
|
|
Title |
Automated observation of physical snowpack properties in Ny-Ålesund |
Type |
Journal |
|
Year |
2023 |
Publication |
Frontiers in Earth Science |
Abbreviated Journal |
|
|
|
Volume |
11 |
Issue |
|
Pages |
|
|
|
Keywords |
|
|
|
Abstract |
The snow season in the Svalbard archipelago generally lasts 6–10 months a year and significantly impacts the regional climate, glaciers mass balance, permafrost thermal regime and ecology. Due to the lack of long-term continuous snowpack physical data, it is still challenging for the numerical snow physics models to simulate multi-layer snowpack evolution, especially for remote Arctic areas. To fill this gap, in November 2020, an automated nivometric station (ANS) was installed ∼1 km Southwest from the settlement of Ny-Ålesund (Spitzbergen, Svalbard), in a flat area over the lowland tundra. It automatically provides continuous snow data, including NIR images of the fractional snow-cover area (fSCA), snow depth (SD), internal snow temperature and liquid water content (LWC) profiles at different depths with a 10 min time resolution. Here we present the first-year record of automatic snow preliminary measurements collected between November 2020 and July 2021 together with weekly manual observations for comparison. The snow season at the ANS site lasted for 225 days with an annual net accumulation of 117 cm (392 mm of water equivalent). The LWC in the snowpack was generally low (<4%) during wintertime, nevertheless, we observed three snow-melting events between November and February 2021 and one in June 2021, connected with positive temperature and rain on snow events (ROS). In view of the foreseen future developments, the ANS is the first automated, comprehensive snowpack monitoring system in Ny-Ålesund measuring key essential climate variables needed to understand the seasonal evolution of the snow cover on land. |
|
|
Programme |
1192 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2296-6463 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8530 |
|
Permanent link to this record |
|
|
|
|
Author |
C. Sauser, F. Angelier, P. Blévin, O. Chastel, G.W. Gabrielsen, W. Jouanneau, A. Kato, B. Moe, F. Ramírez, S. Tartu, S. Descamps |
|
|
Title |
Demographic responses of Arctic seabirds to spring sea-ice variations |
Type |
Journal |
|
Year |
2023 |
Publication |
Frontiers in Ecology and Evolution |
Abbreviated Journal |
|
|
|
Volume |
11 |
Issue |
|
Pages |
|
|
|
Keywords |
|
|
|
Abstract |
The Arctic experiences a rapid retreat of sea-ice, particularly in spring and summer, which may dramatically affect pagophilic species. In recent years, the decline of many Arctic seabird populations has raised concerns about the potential role of sea-ice habitats on their demography. Spring sea-ice drives the dynamics of phytoplankton blooms, the basis of Arctic food webs, and changes in spring sea-ice have the potential to affect the demographic parameters of seabirds through bottom-up processes. To better understand the effects of spring sea-ice on Arctic seabirds, we investigated the influence of spring sea-ice concentration on the survival and breeding success of three seabird species with contrasted foraging strategies in two Svalbard fjords in the high Arctic. We examined these relationships using long-term demographic data (2005–2021) from black-legged kittiwakes (Rissa tridactyla), Brünnich guillemots (Uria lomvia), and little auks (Alle alle). Spring sea-ice concentration was positively related to both the survival and breeding success of little auks, suggesting a higher sensitivity of this species to spring sea-ice. By contrast, the two other species were not particularly sensitive to changes in spring sea-ice, even though a potentially spurious negative effect on the breeding success of black-legged kittiwakes was observed. Overall, the study suggests that spring sea-ice may be involved in the demography of Arctic seabirds, but probably does not play a major role. |
|
|
Programme |
330 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2296-701X |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8533 |
|
Permanent link to this record |
|
|
|
|
Author |
Joris Laborie, Matthieu Authier, Adrien Chaigne, Karine Delord, Henri Weimerskirch, Christophe Guinet |
|
|
Title |
Estimation of total population size of southern elephant seals (Mirounga leonina) on Kerguelen and Crozet Archipelagos using very high-resolution satellite imagery |
Type |
Journal |
|
Year |
2023 |
Publication |
Frontiers in Marine Science |
Abbreviated Journal |
|
|
|
Volume |
10 |
Issue |
|
Pages |
|
|
|
Keywords |
|
|
|
Abstract |
Southern elephant seals (Mirounga leonina) play a pivotal role in the Southern Ocean as wide-ranging marine predators and major prey consumers within Southern Ocean marine ecosystems. Due to their circumpolar distribution and the remoteness of their habitat, large uncertainties remain about their total population sizes. This is especially true for elephant seal populations in the French Southern Territories in the southern Indian Ocean (i.e. Crozet and Kerguelen Archipelagos) as many breeding sites are inaccessible for ground censuses. Here, we present a simple and efficient approach for estimating the total elephant seal populations of the Kerguelen and Crozet Archipelagos by using very high-resolution satellite imagery (<1m resolution). Twenty-eight satellite images taken during the breeding season to count female elephant seals in inaccessible areas were used and complemented the traditional annual ground counts in accessible areas. For Kerguelen Island sectors likely to host colonies and where no satellite images were available for the breeding season, a statistical predictive model was built to estimate the most likely number of breeding females to be present on a given beach according to its physiographic characteristics. Our results show the reliability of using very high-resolution satellite images, a relatively low-cost platform, to count pinniped populations and provide the first estimation of the total southern elephant seal population for both the Kerguelen 347,995 (s e = 4,950) and Crozet 13,065 (s e = 169) Archipelagos. The combined total represents over 35% of the global elephant seal population with the Kerguelen stock being numerically equivalent to the South Georgia stock. In addition, we re-examined the population trends since the last mid-century for Kerguelen and over the last five decades for Crozet. The demographic trends of the southern Indian Ocean populations show marked growth over the last decade (5.1% and 1.6% annual growth rate for Crozet and Kerguelen respectively), particularly on Crozet where the elephant seal population has more than tripled. |
|
|
Programme |
109,1201 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
Bachelor's thesis |
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2296-7745 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8535 |
|
Permanent link to this record |
|
|
|
|
Author |
Concepcion Sanchez-Cid, Christoph Keuschnig, Timothy M Vogel, Catherine Larose |
|
|
Title |
Impact of in situ solar irradiation on snow bacterial communities and functional potential |
Type |
Journal |
|
Year |
2023 |
Publication |
FEMS Microbiology Ecology |
Abbreviated Journal |
|
|
|
Volume |
99 |
Issue |
6 |
Pages |
fiad042 |
|
|
Keywords |
|
|
|
Abstract |
Polar regions are increasingly exposed to ultraviolet light due to ozone depletion. Snowpacks contain photochemically active particles that, when irradiated, can lead to the production and accumulation of reactive species that can induce oxidative stress on snow microorganisms. This could generate a selective pressure on snowpack bacteria. In this study, snow microcosms were buried in a snowpack at Ny-Ålesund (Svalbard), either exposed to solar irradiation or incubated in the dark for 10 days, and the bacterial response to solar irradiation was evaluated in situ using a metagenomics approach. Solar irradiation induced a significant decrease in bacterial abundance and richness. Genes involved in glutathione synthesis, sulphur metabolism, and multidrug efflux were significantly enriched in the light, whereas genes related to cell wall assembly and nutrient uptake were more abundant in the dark. This is the first study demonstrating the response of snow bacterial communities to solar irradiation in situ and providing insights into the mechanisms involved. Our research shows that polar sun irradiation is sufficiently intense to impose a selective pressure on snow bacteria and supports the concern that increased ultraviolet exposure due to anthropogenic activities and climatic change could drive critical changes in the structure and functioning of snow bacterial communities. |
|
|
Programme |
1192 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
0168-6496 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8539 |
|
Permanent link to this record |
|
|
|
|
Author |
Loïc Le Ster, Hervé Claustre, Francesco d’Ovidio, David Nerini, Baptiste Picard, Christophe Guinet |
|
|
Title |
Improved accuracy and spatial resolution for bio-logging-derived chlorophyll a fluorescence measurements in the Southern Ocean |
Type |
Journal |
|
Year |
2023 |
Publication |
Frontiers in Marine Science |
Abbreviated Journal |
|
|
|
Volume |
10 |
Issue |
|
Pages |
|
|
|
Keywords |
|
|
|
Abstract |
The ocean’s meso- and submeso-scales (1-100 km, days to weeks) host features like filaments and eddies that have a key structuring effect on phytoplankton distribution, but that due to their ephemeral nature, are challenging to observe. This problem is exacerbated in regions with heavy cloud coverage and/or difficult access like the Southern Ocean, where observations of phytoplankton distribution by satellite are sparse, manned campaigns costly, and automated devices limited by power consumption. Here, we address this issue by considering high-resolution in-situ data from 18 bio-logging devices deployed on southern elephant seals (Mirounga leonina) in the Kerguelen Islands between 2018 and 2020. These devices have submesoscale-resolving capabilities of light profiles due to the high spatio-temporal frequency of the animals’ dives (on average 1.1 +-0.6 km between consecutive dives, up to 60 dives per day), but observations of fluorescence are much coarser due to power constraints. Furthermore, the chlorophyll a concentrations derived from the (uncalibrated) bio-logging devices’ fluorescence sensors lack a common benchmark to properly qualify the data and allow comparisons of observations. By proposing a method based on functional data analysis, we show that a reliable predictor of chlorophyll a concentration can be constructed from light profiles (14 686 in our study). The combined use of light profiles and matchups with satellite ocean-color data enable effective (1) homogenization then calibration of the bio-logging devices’ fluorescence data and (2) filling of the spatial gaps in coarse-grained fluorescence sampling. The developed method improves the spatial resolution of the chlorophyll a field description from ~30 km to ~12 km. These results open the way to empirical study of the coupling between physical forcing and biological response at submesoscale in the Southern Ocean, especially useful in the context of upcoming high-resolution ocean-circulation satellite missions. |
|
|
Programme |
109 |
|
|
Campaign |
|
|
|
Address |
|
|
|
Corporate Author |
|
Thesis |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Summary Language |
|
Original Title |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2296-7745 |
ISBN |
|
Medium |
|
|
|
Area |
|
Expedition |
|
Conference |
|
|
|
Notes |
|
Approved |
yes |
|
|
Call Number |
|
Serial |
8540 |
|
Permanent link to this record |