Energetic Charged Particles Above Thunderclouds     

Martin Füllekrug  Declan Diver  Jean-Louis Pinçon  Alan D. R. Phelps  Anne Bourdon  Christiane Helling  Elisabeth Blanc  Farideh Honary  R. Giles Harrison  Jean-André Sauvaud  Jean-Baptiste Renard  Mark Lester  Michael Rycroft  Mike Kosch  Richard B. Horne  Serge Soula  Stéphane Gaffet 《Surveys in Geophysics》2013,34(1):1-41

The French government has committed to launch the satellite TARANIS to study transient coupling processes between the Earth’s atmosphere and near-Earth space. The prime objective of TARANIS is to detect energetic charged particles and hard radiation emanating from thunderclouds. The British Nobel prize winner C.T.R. Wilson predicted lightning discharges from the top of thunderclouds into space almost a century ago. However, new experiments have only recently confirmed energetic discharge processes which transfer energy from the top of thunderclouds into the upper atmosphere and near-Earth space; they are now denoted as transient luminous events, terrestrial gamma-ray flashes and relativistic electron beams. This meeting report builds on the current state of scientific knowledge on the physics of plasmas in the laboratory and naturally occurring plasmas in the Earth’s atmosphere to propose areas of future research. The report specifically reflects presentations delivered by the members of a novel Franco-British collaboration during a meeting at the French Embassy in London held in November 2011. The scientific subjects of the report tackle ionization processes leading to electrical discharge processes, observations of transient luminous events, electromagnetic emissions, energetic charged particles and their impact on the Earth’s atmosphere. The importance of future research in this area for science and society, and towards spacecraft protection, is emphasized.  相似文献   

Impact of fire on long-term vegetation dynamics of ombrotrophic peatlands in northwestern Québec,Canada     

Gabriel Magnan  Martin Lavoie  Serge Payette 《Quaternary Research》2012,77(1):110-121

A 7000-year record of local fire history was reconstructed from three ombrotrophic peatlands in the James Bay lowlands (northwestern Québec, Canada) using a high-resolution analysis of macroscopic charcoal (long axis ≥ 0.5 mm). The impact of fire on vegetation changes was evaluated using detailed analysis of plant macrofossils. Compared to upland boreal forest, fire incidence in these Sphagnum-dominated bogs is rather low. Past fire occurrence seems to have been controlled primarily by internal processes associated with local hydroseral succession. Size of the peatland basin and distance from the well-drained forest soils also appear to be factors controlling fire occurrence. The impact of peatland fires on long-term vegetation succession appears negligible except in a forested bog, where it initiated the replacement of Sphagnum by mosses. In some circumstances, fire caused marked changes in the bryophyte assemblages over many decades. However, ombrotrophic peatland vegetation is generally resilient to surface fire.  相似文献   

On the origin of the prolate solar chromosphere     

Filippov  Boris  Koutchmy  Serge 《Solar physics》2000,196(2):311-320

A simple geometric model is proposed to explain the recently reported effect of the prolateness of the solar chromosphere. We assume that a specific dynamical part of the solar atmosphere above the 2 Mm level, being a mixture of moving up and down jets of chromospheric matter with the coronal plasma between them, is responsible for the solar prolateness. Due to the dynamic nature of this layer, the magnetic field is considered to play a very important role in the density distribution with the height, guiding the mass flows along the field lines. The difference of the magnetic field topology in the polar and the equatorial regions leads to different heights of the chromospheric limb. Calculations show a satisfactory coincidence with observations when the mean separation between opposite polarity concentrations is about 9 Mm. The possible observational signature of this network in low photospheric and chromospheric layers is discussed.  相似文献   

Why Is the Climate Forcing of Sulfate Aerosols So Uncertain?   总被引：2，自引：0，他引：2  

Hu Rongming  Serge Planton  Michel Déque  Pascal Marquet  Alain Braun 《大气科学进展》2001,18(6):1103-1120

l. IntroductionAlthough the aerosol has been recognized as an important factor which has innuence onthe past, present and future climate for a long time, it still has much uncertainty in assessingits climate forcing. The direct radiative forcing of sulfate aerosols has been estimated rangingfrom --0.3 W/ m2 to --0.9 W/ m2 in recent publications (Charlson et al., l992, Kiehl andBriegleb l993; Taylor and Penner 1994, Boucher and Anderson l995, Kieh1 and Rodhe l995;Chuang et al., l997, Penne…  相似文献   

The late Quaternary sedimentary infill of Lake Annecy (northwestern Alps): an overview from two seismic-reflection surveys     

Christian Beck  Pieter Van Rensbergen  Marc De Batist  Fernand Berthier  Serge Lallier  Frédéric Manalt 《Journal of Paleolimnology》2001,25(2):149-161

The sedimentary fill of Lake Annecy (northwestern Alps) - related to the last glacial/post-glacial episode - was investigated through high resolution (sparker) and very high resolution (2.5 kHz) seismic-reflection surveys. A seismostratigraphic approach led to subdivision of a 150 m-thick pile (maximum thickness in axial part) into five units. Basal units (1 and 2) represent an imbrication of subglacial and glacio-lacustrine deposits, close to the grounding line of the glaciers' fronts (respectively at the northern and southern terminations of the lake). The first acoustically well-stratified unit (3) developed during a fast retreat of the glaciers fronts far from the lake basin, and a progradational alluvial regime, with abundant underflows, in a lake larger than the present one. Unit 4 represents the progressive decrease of this clastic input mixed with the progressive development of in situ bio-induced production. As in many other alpine lakes, a topmost unit (5), relatively thin (about 8-10 m) and with a conspicuous drape configuration, is the signature of the Holocene interglacial climatic conditions with a sedimentation rate of about 1 mm/yr. On the lacustrine basin slopes, slumps and debris flow occurred mainly within Unit 3; they may be due to, either climate-induced high rate terrigenous sedimentation, or/and to a period of increased seismo-tectonic activity.  相似文献   

Two dynamical models for solar spicules     

Paul Lorrain  Serge Koutchmy 《Solar physics》1996,165(1):115-137

Solar spicules are luminous jets that erupt up to 10 000 km from the surface of the Sun and have diameters, all along their length, of only about 150–200 km. We first review some recent observations made at the H wavelength. According to our models, a solar spicule is a self-channelled proton beam emitted by a magnetic element and surrounded by a cold sheath. The beam originates in a self-excited dynamo that exploits a v × B field and that could be situated either below or above the element, where v is the local plasma velocity and B is the local magnetic flux density. In falling back, the sheath provides a return current of protons that cancels the outgoing current. We discuss the channelling of charged-particle beams of very large cross-section and propose velocity channelling, which is apparently a new concept. We assume a steady state and a hydrogen plasma.  相似文献   

Seasonal influence of the sea surface temperature on the low atmospheric circulation and precipitation in the eastern equatorial Atlantic     

Rémi Meynadier  Gaëlle de Coëtlogon  Marion Leduc-Leballeur  Laurence Eymard  Serge Janicot 《Climate Dynamics》2016,47(3-4):1127-1142

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Predictive Geological Mapping Using Closed-Form Non-stationary Covariance Functions with Locally Varying Anisotropy: Case Study at El Teniente Mine (Chile)   总被引：1，自引：0，他引：1  

Francky?FouedjioEmail author  Serge?Séguret 《Natural Resources Research》2016,25(4):431-443

This paper is concerned with the problem of predicting the surface elevation of the Braden breccia pipe at the El Teniente mine in Chile. This mine is one of the world’s largest and most complex porphyry-copper ore systems. As the pipe surface constitutes the limit of the deposit and the mining operation, predicting it accurately is important. The problem is tackled by applying a geostatistical approach based on closed-form non-stationary covariance functions with locally varying anisotropy. This approach relies on the mild assumption of local stationarity and involves a kernel-based experimental local variogram a weighted local least-squares method for the inference of local covariance parameters and a kernel smoothing technique for knitting the local covariance parameters together for kriging purpose. According to the results, this non-stationary geostatistical method outperforms the traditional stationary geostatistical method in terms of prediction and prediction uncertainty accuracies.  相似文献   

Requiem     

Serge von Bubnoff 《International Journal of Earth Sciences》1953,41(1):1-6

Ohne Zusammenfassung  相似文献   

The role of inorganic and organic nutrients on the development of phytoplankton along a transect from the Daugava River mouth to the Open Baltic, in spring and summer 1999     

Poder  Tonis; Maestrini  Serge Y; Balode  Maija; Lips  Urmas; Bechemin  Christian; Andrushaitis  Andris; Purina  Ingrida 《ICES Journal of Marine Science》2003,60(4):827-835

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