Select All    Deselect All
 |   | 
Details
   print
  Records Links
Author E. Aristidi, A. Agabi, L. Abe, E. Fossat, A. Ziad, D. Mékarnia doi  isbn
openurl 
  Title Dome C coherence time statistics from DIMM data Type Journal
  Year 2020 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal  
  Volume 496 Issue 4 Pages 4822-4826  
  Keywords Astrophysics – Instrumentation and Methods for Astrophysics  
  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.  
  Programme 1066  
  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 0035-8711, 1365-2966 ISBN (down) 0035-8711, 1365-2966 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7825  
Permanent link to this record
 

 
Author D. Mékarnia, T. Guillot, J.-P. Rivet, F.-X. Schmider, L. Abe, I. Gonçalves, A. Agabi, N. Crouzet, T. Fruth, M. Barbieri, D. D. R. Bayliss, G. Zhou, E. Aristidi, J. Szulagyi, J.-B. Daban, Y. Fanteï-Caujolle, C. Gouvret, A. Erikson, H. Rauer, F. Bouchy, J. Gerakis, G. Bouchez doi  isbn
openurl 
  Title Transiting planet candidates with ASTEP 400 at Dome C, Antarctica Type Journal
  Year 2016 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal  
  Volume 463 Issue 1 Pages 45-62  
  Keywords  
  Abstract ASTEP 400, the main instrument of the ASTEP (Antarctica Search for Transiting ExoPlanets) programme, is a 40 cm telescope, designed to withstand the harsh conditions in Antarctica, achieving a photometric accuracy of a fraction of millimagnitude on hourly time-scales for planet-hosting southern bright (R ∼ 12 mag) stars. We review the performances of this instrument, describe its operating conditions, and present results from the analysis of observations obtained during its first three years (2010–2012) of operation, before its repatriation in 2014. During this time, we observed a total of 22 stellar fields (1° × 1° field of view). Each field, in which we measured stars up to magnitude R = 18 mag, was observed continuously during ∼7 to ∼30 d. More than 200 000 frames were recorded and 310 000 stars processed, using an implementation of the optimal image subtraction photometry algorithm. We found 43 planetary transit candidates. 20 of these candidates were observed using spectroscopic follow-ups including four targets classified as good planet candidates. Our results demonstrate that accurate near-continuous photometric observations are achievable from the Concordia station at Dome C in Antarctica, even if we were not able to reach the nominal photometric precision of the instrument. We conducted a correlation analysis between the rms noise and a large number of external parameters and found that source of the ∼1 mmag correlated noise is not obvious and does not depend on a single parameter. However, our analysis provided some hints and guidance to increase the photometric accuracy of the instrument. These improvements should equip any future telescope operating in Antarctica.  
  Programme 1066  
  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 0035-8711 ISBN (down) 0035-8711 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8070  
Permanent link to this record
 

 
Author Christine Bingen, Charles E. Robert, Kerstin Stebel, Christoph Brühl, Jennifer Schallock, Filip Vanhellemont, Nina Mateshvili, Michael Höpfner, Thomas Trickl, John E. Barnes, Julien Jumelet, Jean-Paul Vernier, Thomas Popp, Gerrit de Leeuw, Simon Pinnock doi  isbn
openurl 
  Title Stratospheric aerosol data records for the climate change initiative: Development, validation and application to chemistry-climate modelling Type Journal
  Year 2017 Publication Remote Sensing of Environment Abbreviated Journal  
  Volume 203 Issue Pages 296-321  
  Keywords Aerosol burden Aerosol remote sensing Climate data record Climate modelling ENVISAT GOMOS Lidar Stratospheric aerosol extinction Volcanic eruptions  
  Abstract This paper presents stratospheric aerosol climate records developed in the framework of the Aerosol_cci project, one of the 14 parallel projects from the ESA Climate Change Initiative. These data records were processed from a stratospheric aerosol dataset derived from the GOMOS experiment, using an inversion algorithm optimized for aerosol retrieval, called AerGOM. They provide a suite of aerosol parameters, such as the aerosol extinction coefficient at different wavelengths in the UV–visible range. The extinction record includes the total extinction as well as separate fields for liquid sulfate aerosols and polar stratospheric clouds (PSCs). Several additional fields (PSC flag, etc.) are also provided. The resulting stratospheric aerosol dataset, which spans the whole duration of the GOMOS mission (2002−2012), was validated using different reference datasets (lidar and balloon profiles). In the present paper, the emphasis is put on the extinction records. After a thorough analysis of the original AerGOM dataset, we describe the methodology used to construct the gridded CCI-GOMOS dataset and the resulting improvements on both the AerGOM algorithm and the binning procedure, in terms of spatio-temporal resolution, coverage and data quality. The extinction datasets were validated using lidar profiles from three ground-based stations (Mauna Loa, Garmisch-Partenkirchen, Dumont d'Urville). The median difference of the CCI-GOMOS (Level 3) extinction and ground-based lidar profiles is between ~15% and ~45% in the 16–21km altitude range, depending on the considered site and aerosol type. The CCI-GOMOS dataset was subsequently used, together with a MIPAS SO2 time series, to update a volcanic eruption inventory published previously, thus providing a more comprehensive list of eruptions for the ENVISAT period (2002–2012). The number of quantified eruptions increases from 102 to 230 in the updated inventory. This new inventory was used to simulate the evolution of the global radiative forcing by application of the EMAC chemistry-climate model. Results of this simulation improve the agreement between modelled global radiative forcing of stratospheric aerosols at about 100hPa compared to values estimated from observations. Medium eruptions like the ones of Soufriere Hills/Rabaul (2006), Sarychev (2009) and Nabro (2011) cause a forcing change from about −0.1W/m2 to −0.2W/m2.  
  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 0034-4257 ISBN (down) 0034-4257 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6753  
Permanent link to this record
 

 
Author M. Leduc-Leballeur, G. Picard, G. Macelloni, L. Arnaud, M. Brogioni, A. Mialon, Y. H. Kerr doi  isbn
openurl 
  Title Influence of snow surface properties on L-band brightness temperature at Dome C, Antarctica Type Journal
  Year 2017 Publication Remote Sensing of Environment Abbreviated Journal  
  Volume 199 Issue Pages 427-436  
  Keywords Cryosphere Microwave SMOS Snow emission modeling  
  Abstract L-band radiometer measurements collected over the Dome~C area from 2010 to 2015 indicated that the brightness temperature (TB) was relatively stable at vertical (V) polarization (standard deviation lower than 1K at annual scale), while it was slightly more variable at horizontal (H) polarization. During the 2014–2015 austral summer, an exceptional situation was recorded by both the DOMEX ground radiometer and the European Space Agency (ESA)’s Soil Moisture and Ocean Salinity (SMOS) satellite. From November 2014 to March 2015, TB H showed a progressive and significant increase until 20 March 2015 when it sharply decreased by about 5K (at 52.5° incidence angle) within a few days. In parallel to the increase in TB H, glaciological and meteorological in situ measurements showed a wind speed that was lower than usual and a low-density snow layer being progressively set up on the surface. This was consistent with the exceptional hoar event observed, as well as with snow accumulation on the surface. On the other hand, the decrease in TB H was related to the passing over Dome C of a storm that removed or compacted the layer of light snow on the surface. The WALOMIS (Wave Approach for LOw-frequency MIcrowave emission in Snow) snow-emission model was used with in situ measurements of the snowpack as inputs for evaluating the effect of changes observed on the snow surface in TB H. The simulations indicated that the surface snow density variations were sufficient for predicting the increasing and decreasing trends of the TB H. However, the thickness variations of the superficial layer were essential so as to obtain a better agreement with the SMOS observations. This result confirmed that the L-band TB H was affected by the snow properties of the top centimeters of the snowpack, in spite of the large penetration depth (hundreds of meters). Both the surface snow density and the thickness of the superficial layer were relevant, due to coherent interference effects.  
  Programme 1110  
  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 0034-4257 ISBN (down) 0034-4257 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6774  
Permanent link to this record
 

 
Author Giovanni Macelloni, Marion Leduc-Leballeur, Francesco Montomoli, Marco Brogioni, Catherine Ritz, Ghislain Picard doi  isbn
openurl 
  Title On the retrieval of internal temperature of Antarctica Ice Sheet by using SMOS observations Type Journal
  Year 2019 Publication Remote Sensing of Environment Abbreviated Journal  
  Volume 233 Issue Pages 111405  
  Keywords Cryosphere L band Snow/ice microwave emission model  
  Abstract Internal temperature is an essential parameter for understanding ice sheet dynamics. Glaciological models provide estimations of temperature profiles over Antarctica and few boreholes are also available, but, at present, no measurement exists at the scale of the whole continent. The analysis of passive L-band observations from the Soil Moisture and Ocean Salinity (SMOS) satellite shows that, thanks to the high penetration depth (i.e. up to 1500 m), it is possible to infer information on in depth glaciological properties of the ice sheet including temperature. In this study, the temperature profile is retrieved from SMOS observations using jointly glaciological and emission models. The developed methodology is valid in the inner part of Antarctica where the ice sheet is almost stable (i.e. its velocity is limited to 10 m yr−1). This analysis points out that in several cases, differences are observed between retrieved temperature profiles and those predicted by glaciological models. In particular, some geophysical parameters, namely the geothermal heat flux and the mean annual accumulation, need to be modified with respect to their prior values in order to simulate SMOS brightness temperatures. Results also clearly show that the reliability of the retrieved profile in depth decreases with increasing ice thickness due to the limited penetration of microwaves in the ice. The obtained results prove the capability of L band (1.4 GHz) passive microwave sensors for investigating the internal temperature of the ice-sheet.  
  Programme 1110  
  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 0034-4257 ISBN (down) 0034-4257 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6977  
Permanent link to this record
 

 
Author Guillaume Hubert, Sébastien Aubry doi  isbn
openurl 
  Title Analysis of Exposure to Solar and Galactic Cosmic Radiations of Flights Representative of the European International Air Traffic Type Journal
  Year 2018 Publication Radiation Research Abbreviated Journal  
  Volume 190 Issue 3 Pages 271-281  
  Keywords  
  Abstract This study analyzed the impact of galactic and solar cosmic rays on ambient dose equivalent during airline travel. A high statistic of flights are considered, which is representative of European international air traffic. Flight paths are based on the Eurocontrol Demand Data Repository and consider realistic flight plans with and without regulations or updated with radar data from the Central Flow Management Unit. Ambient dose equivalent during flights was investigated during quiet solar periods and extreme solar flare events. Thus, the statistical analyses presented here take into account route characteristics (departure, arrival, continent, etc.) and space weather conditions. The findings of this work show the important influence of flight path, particularly the latitude, which drives the cutoff rigidity variations. Moreover, dose values vary drastically during ground level enhancement events, with the route path (latitude, longitude and altitude) and the phasing of the solar event. This study highlights the importance of monitoring these solar events and developing a physical approach to obtain reliable assessment of ambient dose equivalents.  
  Programme 1112  
  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 0033-7587, 1938-5404 ISBN (down) 0033-7587, 1938-5404 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7040  
Permanent link to this record
 

 
Author Guillaume Hubert, Sébastien Aubry doi  isbn
openurl 
  Title Atmospheric Cosmic-Ray Variation and Ambient Dose Equivalent Assessments Considering Ground Level Enhancement Thanks to Coupled Anisotropic Solar Cosmic Ray and Extensive Air Shower Modeling Type Journal
  Year 2017 Publication Radiation Research Abbreviated Journal  
  Volume 188 Issue 5 Pages 597-611  
  Keywords  
  Abstract This work investigates the impact of Forbush decrease (FD) and ground-level enhancement (GLE) in the atmosphere, based on solar and galactic cosmic-ray models and the extensive air shower simulations. This approach gives the possibility to investigate both the dynamic behavior of neutron monitors (NM) (using response function) and the flight dose. The ambient dose equivalent during quiet solar activity and solar events (i.e., FDs and GLEs) were investigated for realistic flight plans issued from the Eurocontrol Demand Data Repository. The calculated ambient dose equivalents were compared with flight measurements in quiet solar conditions; comparisons are relevant and demonstrate the ability to estimate the dose level. The GLE model was validated for the GLEs 5 and 69 using the cosmic-ray variation recorded by NMs. The GLE model was applied to flight dose calculations. All of these results show that dose values vary drastically with the route path (latitude, longitude and altitude) and with the delay between the flight departure and the solar event occurrence. Doses induced by extreme GLE events were investigated specifically for London to New York flights, and resulting additional doses are a few hundred or 1,000 μSv, impacting significantly the annual effective dose. This highlights the importance of monitoring extreme solar events and using realistic semi-empirical and particle transport methods for reliable calculation of dose levels.  
  Programme 1112  
  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 0033-7587 ISBN (down) 0033-7587 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6725  
Permanent link to this record
 

 
Author Dmitry Krasnoshchekov, Petr Kaazik, Elena Kozlovskaya, Vladimir Ovtchinnikov doi  isbn
openurl 
  Title Seismic Structures in the Earth’s Inner Core Below Southeastern Asia Type Journal
  Year 2016 Publication Pure and Applied Geophysics Abbreviated Journal  
  Volume 173 Issue 5 Pages 1575-1591  
  Keywords  
  Abstract Documenting seismic heterogeneities in the Earth’s inner core (IC) is important in terms of getting an insight into its history and dynamics. A valuable means for studying properties and spatial structure of such heterogeneities is provided by measurements of body waves refracted in the vicinity of the inner core boundary (ICB). Here, we investigate eastern hemisphere of the solid core by means of PKPBC–PKPDF differential travel times that sample depths from 140 to 360 km below its boundary. We study 292 polar and 133 equatorial residuals measured over the traces that probe roughly the same volume of the IC in both planes. Equatorial residuals show slight spatial variations in the sampled IC volume mostly below the level of 0.5 %, whereas polar residuals are up to three times as big, direction dependent and can exhibit higher local variations. The measurements reveal fast changes in seismic velocity within a restricted volume of the IC. We interpret the observations in terms of anisotropy and check against several anisotropy models few of which have been found capable of fitting the residuals scatter. We particularly quantify the model where a dipping discontinuity separates fully isotropic roof of the IC from its anisotropic body, whereas the depth of isotropy–anisotropy transition increases in southeast direction from 190 km below Southeastern Asia (off the coast of China) to 350 km beneath Australia. Another acceptable model cast in terms of localized anisotropic heterogeneities is valid if 33 largest polar measurements over the rays sampling a small volume below Southeastern Asia and the rest of polar data are treated separately. This model envisages almost isotropic eastern hemisphere of the IC at least down to the depth of 360 km below the ICB and constrains the anisotropic volume only to the ranges of North latitudes from 18° to 23°, East longitudes from 125° to 135° and depths exceeding 170 km. The anisotropy strength in either model is about 2 %. Further effective pursuit of the models presents challenges in terms of resolution and coverage and basically requires a significant dataset extension.  
  Programme 133  
  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 0033-4553, 1420-9136 ISBN (down) 0033-4553, 1420-9136 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6772  
Permanent link to this record
 

 
Author Alexandre Corbeau, Charles-André Bost doi  isbn
openurl 
  Title A healthy, premoult adult king penguin (Aptenodytes patagonicus) with a markedly twisted beak Type Journal
  Year 2017 Publication Polar Record Abbreviated Journal  
  Volume 53 Issue 6 Pages 631-632  
  Keywords  
  Abstract In seabirds, diet and feeding methods are related to the species morphology (Croxall, Evans, & Schreiber, 1984). Species that feed on living, mobile resources rely on a fully operational beak to efficiently seize, kill and swallow their prey. This is particularly important to diving species, such as penguins, that are highly time constrained when searching for prey at depth—as air-breathing predators, penguins must maximise their feeding efficiency during their deep foraging dives (Wilson & Wilson, 1990). This is why the observation of free-ranging penguins with physical abnormalities in good body condition is so rare. Here we report a highly unusual observation of a premoult adult king penguin (Aptenodytes patagonicus Miller) in good body condition with a highly anomalous beak.  
  Programme 394  
  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 0032-2474, 1475-3057 ISBN (down) 0032-2474, 1475-3057 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6853  
Permanent link to this record
 

 
Author Alexandra Lavrillier doi  isbn
openurl 
  Title Climate change among nomadic and settled Tungus of Siberia: continuity and changes in economic and ritual relationships with the natural environment Type Journal
  Year 2013 Publication Polar Record Abbreviated Journal  
  Volume 49 Issue 3 Pages 260-271  
  Keywords  
  Abstract Living in close relationship with the Siberian environment, for several decades the Tungus (Evenk and Even peoples) have been noticing numerous changes in climate, flora and fauna. Based on fieldwork among reindeer herders, hunters and fishermen in Yakutia, the Amur region and Kamchatka, this paper explores how climate change is perceived, and how it causes economic, social and ritual changes. It questions the modifications of the economic and religious human-environment relationships through various aspects. It analyses the indigenous perception of a link between the environment and identity and the indigenous notion of adaptation and vulnerability. It also compares their adaptive strategies that either use old techniques, or trigger mutations. In this context, the notion of reciprocity seems to be disappearing and a new notion of time-space in managing the environment is appearing. This paper analyses the religious changes, such as the creation of new rituals and millenarian narratives or the rebirth of shamanistic legends.  
  Programme 1127  
  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 0032-2474, 1475-3057 ISBN (down) 0032-2474, 1475-3057 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6976  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print