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Title |
Ionization processes in the atmosphere of Titan
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Journal Article |
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Year |
2009 |
Publication |
A&A |
Abbreviated Journal |
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Volume |
506 |
Issue |
2 |
Pages |
955 -964 |
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Keywords  |
planets and satellites: individual: Titan -- atmospheric effects -- Sun: UV radiation -- space vehicles: instruments -- methods: numerical |
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Abstract |
Context. The Cassini probe regularly passes in the vicinity of Titan, revealing new insights into particle precipitation thanks to the electron and proton spectrometer. Moreover, the Huygens probe has revealed an ionized layer at 65 km induced by cosmic rays. The impact of these different particles on the chemistry of Titan is probably very strong.
Aims. In this article, we compute the whole ionization in the atmosphere of Titan: from the cosmic rays near the ground to the EUV in the upper atmosphere. The meteoritic layer is not taken into account.
Methods. We used the transTitan model to compute the electron and EUV impact, and the planetocosmics code to compute the influence of protons and oxygen ions. We coupled the two models to study the influence of the secondary electrons obtained by planetocosmics through the transTitan code. The resulting model improves the accuracy of the calculation through the transport of electrons in the atmosphere.
Results. The whole ionization is computed and studied in details. During the day, the cosmic ray ionization peak is as strong as the UV-EUV one. Electrons and protons are very important depending the precipitation conditions. Protons can create a layer at 500 km, while electrons tend to ionize near 800 km. The oxygen ion impact is near 900 km. The results shows few differences to precedent models for the nightside T5 fly-by of Cassini, and can highlight the sources of the different ion layers detected by radio measurements.
Conclusions. The new model successfully computes the ion production in the atmosphere of Titan. For the first time, a full electron and ion profile has been computed from 0 to 1600 km, which compares qualitatively with measurements. This result can be used by chemical models. |
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1026 |
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0004-6361 |
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yes |
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1973 |
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Title |
QUBIC: the Q&U Bolometric Interferometer for Cosmology
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Type |
Conference - International - Article with Reading Comitee |
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Year |
2011 |
Publication |
Journal of Low Temperature Physics |
Abbreviated Journal |
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Pages |
1-7 |
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Keywords |
Physics and Astronomy, |
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Abstract |
The primordial B-mode polarisation of the Cosmic Microwave Background is the imprints of the gravitational wave background generated by inflation. Observing the B-mode is up to now the most direct way to constrain the physics of the primordial Universe, especially inflation. To detect these B-modes, high sensitivity is required as well as an exquisite control of systematics effects. To comply with these requirements, we propose a new instrument called QUBIC (Q and U Bolometric Interferometer for Cosmology) based on bolometric interferometry. The control of systematics is obtained with a close-packed interferometer while bolometers cooled to very low temperature allow for high sensitivity. We present the architecture of this new instrument, the status of the project and the self-calibration technique which allows accurate measurement of the instrumental systematic effects. |
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915 |
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Springer Netherlands |
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0022-2291 |
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yes |
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3482 |
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Author |
Klein K-L, Trottet G, Samwel S, Malandraki O, |
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Title |
Particle Acceleration and Propagation in Strong Flares without Major Solar Energetic Particle Events
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Journal Article |
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Year |
2011 |
Publication |
Solar Physics |
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Volume |
269 |
Issue |
2 |
Pages |
309-333 |
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Keywords |
Physics and Astronomy, |
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Abstract |
Solar energetic particles (SEPs) detected in space are statistically associated with flares and coronal mass ejections (CMEs). But it is not clear how these processes actually contribute to the acceleration and transport of the particles. The present work addresses the question why flares accompanied by intense soft X-ray bursts may not produce SEPs detected by observations with the GOES spacecraft. We consider all X-class X-ray bursts between 1996 and 2006 from the western solar hemisphere. 21 out of 69 have no signature in GOES proton intensities above 10 MeV, despite being significant accelerators of electrons, as shown by their radio emission at cm wavelengths. The majority (11/20) has no type III radio bursts from electron beams escaping towards interplanetary space during the impulsive flare phase. Together with other radio properties, this indicates that the electrons accelerated during the impulsive flare phase remain confined in the low corona. This occurs in flares with and without a CME. Although GOES saw no protons above 10 MeV at geosynchronous orbit, energetic particles were detected in some (4/11) confined events at Lagrangian point L1 aboard ACE or SoHO. These events have, besides the confined microwave emission, dm-m wave type II and type IV bursts indicating an independent accelerator in the corona. Three of them are accompanied by CMEs. We conclude that the principal reason why major solar flares in the western hemisphere are not associated with SEPs is the confinement of particles accelerated in the impulsive phase. A coronal shock wave or the restructuring of the magnetically stressed corona, indicated by the type II and IV bursts, can explain the detection of SEPs when flare-accelerated particles do not reach open magnetic field lines. But the mere presence of these radio signatures, especially of a metric type II burst, is not a sufficient condition for a major SEP event. |
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227 |
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Thesis |
Bachelor's thesis |
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Publisher |
Springer Netherlands |
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ISSN |
0038-0938 |
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yes |
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Serial |
3577 |
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Author |
Saintenoy Albane, Friedt J-M, Booth Adam D, Tolle F, Bernard E, Laffly Dominique, Marlin C, Griselin M, |
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Journal Article |
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Year |
2013 |
Publication |
NEAR SURFACE GEOPHYSICS |
Abbreviated Journal |
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Volume |
11 |
Issue |
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Pages |
253-261 |
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Keywords |
Physics – Geophysics, |
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Abstract |
The Austre Lov\'enbreen is a 4.6 km2 glacier on the Archipelago of Svalbard (79 degrees N) that has been surveyed over the last 47 years in order of monitoring in particular the glacier evolution and associated hydrological phenomena in the context of nowadays global warming. A three-week field survey over April 2010 allowed for the acquisition of a dense mesh of Ground-penetrating Radar (GPR) data with an average of 14683 points per km2 (67542 points total) on the glacier surface. The profiles were acquired using a Mala equipment with 100 MHz antennas, towed slowly enough to record on average every 0.3 m, a trace long enough to sound down to 189 m of ice. One profile was repeated with 50 MHz antenna to improve electromagnetic wave propagation depth in scattering media observed in the cirques closest to the slopes. The GPR was coupled to a GPS system to position traces. Each profile has been manually edited using standard GPR data processing including migration, to pick the reflection arrival time from the ice-bedrock interface. Snow cover was evaluated through 42 snow drilling measurements regularly spaced to cover all the glacier. These data were acquired at the time of the GPR survey and subsequently spatially interpolated using ordinary kriging. Using a snow velocity of 0.22 m/ns, the snow thickness was converted to electromagnetic wave travel-times and subtracted from the picked travel-times to the ice-bedrock interface. The resulting travel-times were converted to ice thickness using a velocity of 0.17 m/ns. The velocity uncertainty is discussed from a common mid-point profile analysis. A total of 67542 georeferenced data points with GPR-derived ice thicknesses, in addition to a glacier boundary line derived from satellite images taken during summer, were interpolated over the entire glacier surface using kriging with a 10 m grid size. Some uncertainty analysis were carried on and we calculated an averaged ice thickness of 76 m and a maximum depth of 164 m with a relative error of 11.9%. The volume of the glacier is derived as 0.3487$\pm$0.041 km3. Finally a 10-m grid map of the bedrock topography was derived by subtracting the ice thicknesses from a dual-frequency GPS-derived digital elevation model of the surface. These two datasets are the first step for modelling thermal evolution of the glacier and its bedrock, as well as the main hydrological network. |
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Programme |
1111 |
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ISSN |
1569-4445 |
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yes |
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Call Number |
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Serial |
4429 |
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Title |
Enhanced upward heat transport at deep submesoscale ocean fronts |
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Journal |
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Year |
2020 |
Publication |
Nature Geoscience |
Abbreviated Journal |
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Volume |
13 |
Issue |
1 |
Pages |
50-55 |
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Keywords |
Physical oceanography |
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Abstract |
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Programme |
109,1201 |
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Bachelor's thesis |
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ISSN |
1752-0908 |
ISBN |
1752-0908 |
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yes |
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Call Number |
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8264 |
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Journal |
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2021 |
Publication |
Communications Earth & Environment |
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Volume |
2 |
Issue |
1 |
Pages |
1-8 |
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Keywords |
Physical oceanography |
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688 |
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2662-4435 |
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yes |
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Serial |
8387 |
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Author |
Houser C, Masters G, Flanagan M, Shearer P, |
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Title |
Determination and analysis of long-wavelength transition zone structure using SS precursors
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Type |
Journal Article |
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Year |
2008 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
0956-540X |
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Volume |
174 |
Issue |
1 |
Pages |
178-194 |
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Keywords |
Phase transitions, Body waves, |
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133 |
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Blackwell Publishing Ltd |
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ISSN |
1365-246X |
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yes |
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2784 |
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Title |
Energetic constraints may limit the capacity of visually guided predators to respond to Arctic warming
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Journal Article |
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2013 |
Publication |
Journal of Zoology |
Abbreviated Journal |
J. Zool. (Lond.) |
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289 |
Issue |
2 |
Pages |
119-126 |
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Keywords |
Phalacrocorax carbo, great cormorant, climate change, temperature, illumination, diving, |
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Abstract |
For many polar species, climate change is likely to result in range contractions and negative population trends. For those species whose distribution is limited by sea ice and cold water, however, polar warming could result in population increases and range expansion. Population increases of great cormorants Phalacrocorax carbo in Greenland are associated with warmer sea surface temperatures, but the actual impact of environmental change on cormorant spatial ecology remains unclear. In the present study, we investigate how Arctic warming is likely to influence the distribution of cormorants in Greenland. Using geolocation data, we show that many individuals that breed above the Arctic Circle migrate south and winter at lower latitude. We then couple estimates of migratory flight costs with a model that predicts daily energy expenditure during winter on the basis of water temperature, ambient illumination during diving, dive depth and day length. This model shows that the most energy efficient strategy predicted for any breeding location is to migrate as far south as possible, and that, for a given wintering location, it is more energetically expensive to breed at high latitude. We argue that cormorants currently undertake a winter migration to escape the polar night and reduce winter energy costs and that their wintering grounds in Greenland will remain largely unchanged under Arctic warming. This is because low levels of ambient illumination during the polar night will continue to restrict foraging opportunities at high latitude during winter. Northward expansion of the breeding range will result in increased energy expenditure associated with long migratory flights, and the cost of such flights may ultimately limit the breeding range of cormorants. Such limitations are likely to represent a general constraint on the capacity of visually guided predators to respond to climate warming, and may limit the predicted poleward range shifts of these species.
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1469-7998 |
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yes |
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3940 |
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Author |
Moine B. |
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2000 |
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Pages |
290 |
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Keywords |
petrogenesis ; rock inclusions ; ultramafics ; volatile elements ; Kerguelen Islands ; metasomatism ; mantle ; mass transfer ; intraplate magmatism ; petrology ; chemical analysis ; mass spectroscopy ; inductively coupled plasma ; stable isotopes ; C-13/C-12 ; O-18/O-16 ; D/H ; trace-element analyses ; xenoliths ; hot spots ; crystal chemistry ; mineral data ; percolation ; fluid phase ; lava ; peridotites ; alkali basalts ; plutonic rocks ; igneous rocks ; Indian Ocean ; basalts ; volcanic rocks |
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251 |
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yes |
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1486 |
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Title |
The stress of being contaminated? Adrenocortical function and reproduction in relation to persistent organic pollutants in female black legged kittiwakes
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Journal Article |
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Year |
2014 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Pages |
553-560 |
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Keywords |
Persistent organic pollutants, Corticosterone, Stress response, Reproduction, Arctic seabirds, |
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330 |
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ISSN |
0048-9697 |
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yes |
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5655 |
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