Search results for "Planetary Science"
showing 10 items of 4367 documents
Large-scale distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory
2012
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 1018 eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 1018 eV from stationary Galactic …
The Piancaldoli meteorite: A forgotten primitive LL3.10 ordinary chondrite
2020
International audience; The Piancaldoli ordinary chondrite fell in northern Italy on August 10, 1968. Preliminary studies led to its classification as an LL3.4 unequilibrated ordinary chondrite. However, recent developments in classification procedures have prompted us to re‐examine its mineralogical, petrographic, spectroscopic, chemical, and isotopic features in a multi‐technique study. Raman spectra and magnetic properties indicate that Piancaldoli experienced minimal thermal metamorphism, consistent with its high bulk hydrogen content and the Cr contents of ferroan olivines in its type II chondrules. In combination with findings of previous studies, our data thus confirm the variability…
Global equatorial variability of 850 and 200 hPa zonal winds from rawinsondes between 1963 and 1989
1995
The longitude-height-time variability of 3-month averaged zonal wind anomalies at 850 and 200 hPa over the equatorial area (5{degrees}N-5{degrees}S) is analyzed using a three-dimensional dataset constructed from rawinsonde data (1963-1989). The first mode, closely related to the Southern Oscillation Index, suggests a strong vertical coupling associated with a horizontal out-of-phase pattern between the central/western Pacific and the remainder of the equatorial belt. The vertical coupling appears to be phase-locked to the annual cycle with strongest intensities found over South America and near the maritime continent early in the calendar year and over the Pacific basin and Africa during th…
Sahel droughts and Enso dynamics
1996
Correlations between summer Sahel rainfall and Southern Oscillation Index has increased during the last thirty years. At high frequency time scale (periods lower than 8 years), an intertropical Atlantic zonal divergent circulation anomaly is forced by the difference of sea surface temperature (SST) anomalies between the eastern equatorial parts of Pacific and Atlantic. This zonal connection worked well during most of the E1 Nino/Southern Oscillation (ENSO) events occurring after 1970; positive/negative SST anomalies in the eastern Pacific/Atlantic led to rainfall deficits over the whole West Africa. At low frequency time scale (periods greater than 8 years), positive SST anomalies in the In…
Changing European storm loss potentials under modified climate conditions according to ensemble simulations of the ECHAM5/MPI-OM1 GCM
2007
Abstract. A simple storm loss model is applied to an ensemble of ECHAM5/MPI-OM1 GCM simulations in order to estimate changes of insured loss potentials over Europe in the 21st century. Losses are computed based on the daily maximum wind speed for each grid point. The calibration of the loss model is performed using wind data from the ERA40-Reanalysis and German loss data. The obtained annual losses for the present climate conditions (20C, three realisations) reproduce the statistical features of the historical insurance loss data for Germany. The climate change experiments correspond to the SRES-Scenarios A1B and A2, and for each of them three realisations are considered. On average, insure…
Isotope geochemistry of Pantelleria volcanic fluids, Sicily Channel rift: a mantle volatile end-member for volcanism in southern Europe
2000
Chemical and isotopic ratio (He, C, H and O) analysis of hydrothermal manifestations on Pantelleria island, the southernmost active volcano in Italy, provides us with the first data upon mantle degassing through the Sicily Channel rift zone, south of the African–European collision plate boundary. We find that Pantelleria fluids contain a CO2–He-rich gas component of mantle magmatic derivation which, at shallow depth, variably interacts with a main thermal (∼100°C) aquifer of mixed marine–meteoric water. The measured 3He/4He ratios and δ13C of both the free gases (4.5–7.3 Ra and −5.8 to −4.2‰, respectively) and dissolved helium and carbon in waters (1.0–6.3 Ra and −7.1 to −0.9‰), together wi…
Lower Crustal Rheology Controls the Development of Large Offset Strike‐Slip Faults During the Himalayan‐Tibetan Orogeny
2020
International audience
Assessing environmental noise exposure: does the size of the neighbourhood matter?
2013
International audience; In environmental epidemiology, studies rely on the quantification of subject'sexposures in a surface defined as the subject exposure area. For outdoor exposure, this area is often considered as the subject's neighbourhood. But, depending on the authors, the size and the nature of this neighbourhood differs, making difficult to compare results. In order to study the impact of the sampling surface on the noise exposure values affected to a subject, a high definition environmental noise model has been builton a middle-sized French city. Outdoor neighbourhood noise indices were computed at 10,394 residential buildings, using eight different sizes of buffers defined by di…
The Mistigri Thermal Infrared Project: Scientific Objectives And Mission Specifications
2013
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Protection de la ressource en eau du bassin de l’Auxerrois et transformation des pratiques agricoles
2022
Avec des taux de nitrates dépassant les seuils définis par la Directive européenne « nitrates », puis la présence de résidus de pesticides utilisés par les activités agricoles du secteur, l’eau des bassins d’alimentation de captages de l’Auxerrois fait l’objet de préoccupations depuis une trentaine d’année. C’est ainsi qu’à la fin des années 1990, les représentants des pouvoirs publics ont choisi de mettre en place une démarche préventive passant par un travail de transformation des pratiques agricoles. Notre article analyse comment la prise en charge collective de cette situation participe à la configuration des relations entre représentants des pouvoirs publics, agriculteurs et défenseurs…