A web of secondary resonances for large <Emphasis Type="Italic">A</Emphasis>/<Emphasis Type="Italic">m</Emphasis> geostationary debris     

A. Lemaître  N. Delsate  S. Valk 《Celestial Mechanics and Dynamical Astronomy》2009,104(4):383-402

The dynamics of space debris with very high A/m near the geostationary orbit is dominated by the gravitational coefficient C ₂₂ and the solar radiation pressure. An analysis of the stability of the orbits by the chaos indicator MEGNO and frequency analysis map FAM shows chaotic layers around the separatrix and reveals a web of sub-structures associated to resonances with the annual period of the Sun. This succession of stable thin islands and chaotic layers can be reproduced and explained by a quite simple toy model, based on a pendulum approach, perturbed, through the eccentricity, by the external (Sun) frequency. The use of suitable action-angle variables in the circulation and libration regions of the pendulum allows to point out new resonances between the geostationary libration angle and the Sun’s longitude. They correspond very well (positions, shape, width) to the structures visible on the FAM representations.  相似文献   

Modeling the obliquity of Mercury     

Benoît Noyelles  Sandrine D'Hoedt 《Planetary and Space Science》2012,60(1):274-286

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GETEMME—a mission to explore the Martian satellites and the fundamentals of solar system physics     

Jürgen Oberst  Valéry Lainey  Christophe Le Poncin-Lafitte  Veronique Dehant  Pascal Rosenblatt  Stephan Ulamec  Jens Biele  J?rn Spurmann  Ralph Kahle  Volker Klein  Ulrich Schreiber  Anja Schlicht  Nicolas Rambaux  Philippe Laurent  Beno?t Noyelles  Bernard Foulon  Alexander Zakharov  Leonid Gurvits  Denis Uchaev  Scott Murchie  Cheryl Reed  Slava G. Turyshev  Jesus Gil  Mariella Graziano  Konrad Willner  Kai Wickhusen  Andreas Pasewaldt  Marita W?hlisch  Harald Hoffmann 《Experimental Astronomy》2012,34(2):243-271

GETEMME (Gravity, Einstein??s Theory, and Exploration of the Martian Moons?? Environment), a mission which is being proposed in ESA??s Cosmic Vision program, shall be launched for Mars on a Soyuz Fregat in 2020. The spacecraft will initially rendezvous with Phobos and Deimos in order to carry out a comprehensive mapping and characterization of the two satellites and to deploy passive Laser retro-reflectors on their surfaces. In the second stage of the mission, the spacecraft will be transferred into a lower 1500-km Mars orbit, to carry out routine Laser range measurements to the reflectors on Phobos and Deimos. Also, asynchronous two-way Laser ranging measurements between the spacecraft and stations of the ILRS (International Laser Ranging Service) on Earth are foreseen. An onboard accelerometer will ensure a high accuracy for the spacecraft orbit determination. The inversion of all range and accelerometer data will allow us to determine or improve dramatically on a host of dynamic parameters of the Martian satellite system. From the complex motion and rotation of Phobos and Deimos we will obtain clues on internal structures and the origins of the satellites. Also, crucial data on the time-varying gravity field of Mars related to climate variation and internal structure will be obtained. Ranging measurements will also be essential to improve on several parameters in fundamental physics, such as the Post-Newtonian parameter ?? as well as time-rate changes of the gravitational constant and the Lense-Thirring effect. Measurements by GETEMME will firmly embed Mars and its satellites into the Solar System reference frame.  相似文献   

Planetary perturbations on Mercury’s libration in longitude     

Julien Dufey  Anne Lemaître  Nicolas Rambaux 《Celestial Mechanics and Dynamical Astronomy》2008,101(1-2):141-157

Two space missions dedicated to Mercury (MESSENGER and BepiColombo) aim at understanding its rotation and confirming the existence of a liquid core. This double challenge requires much more accurate models for the spin-orbit resonant rotation of Mercury. The purpose of this paper is to introduce planetary perturbations on Mercury’s rotation using an analytical method and to analyse the influence of the perturbations on the libration in longitude. Applying a perturbation theory based on the Lie triangle, we were able to re-introduce short periodic terms into the averaged Hamiltonian and to compute the evolution of the rotational variables. The perturbations on Mercury’s forced libration in longitude mainly come from the orbital motion of Mercury (with an amplitude around 41 arcsec that depends on the momenta of inertia). It is completed by various effects from Jupiter (11.86 and 5.93 year-periods), Venus (with a 5.66 year-period), Saturn (14.73 year-period), and the Earth (6.58 year-period). The amplitudes of the oscillations due to Jupiter and Venus are approximately 33% and 10% of those from the orbital motion of Mercury and the amplitudes of the oscillations due to Saturn and the Earth are approximately 3% and 2%. We compare the analytical results with the solution obtained from the spin-orbit numerical model SONYR.  相似文献   

The information system of the French Peatland Observation Service: Service National d'Observation Tourbières – A valuable tool to assess the impact of global changes on the hydrology and biogeochemistry of temperate peatlands through long term monitoring     

Sébastien Gogo  Jean-Baptiste Paroissien  Fatima Laggoun-Défarge  Jean-Marc Antoine  Léonard Bernard-Jannin  Guillaume Bertrand  Philippe Binet  Stéphane Binet  Guillaume Bouger  Yohann Brossard  Thierry Camboulive  Jean-Pierre Caudal  Stéphane Chevrier  Geneviève Chiapiuso  Benoît D'Angelo  Pilar Durantez  Chris Flechard  André-Jean Francez  Didier Galop  Laure Gandois  Daniel Gilbert  Christophe Guimbaud  Louis Hinault  Adrien Jacotot  Franck Le Moing  Emilie Lerigoleur  Gaël Le Roux  Fabien Leroy  Alexandre Lhosmot  Qian Li  Elodie Machado Da Silva  Jean-Sébastien Moquet  Juanita Mora-Gomez  Laurent Perdereau  Thomas Rosset  Marie-Laure Toussaint 《水文研究》2021,35(6):e14244

Mitigating and adapting to global changes requires a better understanding of the response of the Biosphere to these environmental variations. Human disturbances and their effects act in the long term (decades to centuries) and consequently, a similar time frame is needed to fully understand the hydrological and biogeochemical functioning of a natural system. To this end, the ‘Centre National de la Recherche Scientifique’ (CNRS) promotes and certifies long-term monitoring tools called national observation services or ‘Service National d'Observation’ (SNO) in a large range of hydrological and biogeochemical systems (e.g., cryosphere, catchments, aquifers). The SNO investigating peatlands, the SNO ‘Tourbières’, was certified in 2011 ( https://www.sno-tourbieres.cnrs.fr/ ). Peatlands are mostly found in the high latitudes of the northern hemisphere and French peatlands are located in the southern part of this area. Thus, they are located in environmental conditions that will occur in northern peatlands in coming decades or centuries and can be considered as sentinels. The SNO Tourbières is composed of four peatlands: La Guette (lowland central France), Landemarais (lowland oceanic western France), Frasne (upland continental eastern France) and Bernadouze (upland southern France). Thirty target variables are monitored to study the hydrological and biogeochemical functioning of the sites. They are grouped into four datasets: hydrology, fluvial export of organic matter, greenhouse gas fluxes and meteorology/soil physics. The data from all sites follow a common processing chain from the sensors to the public repository. The raw data are stored on an FTP server. After operator or automatic processing, data are stored in a database, from which a web application extracts the data to make them available ( https://data-snot.cnrs.fr/data-access/ ). Each year at least, an archive of each dataset is stored in Zenodo, with a digital object identifier (DOI) attribution ( https://zenodo.org/communities/sno_tourbieres_data/ ).  相似文献   

Local traditions as a means for commercial production of historical beers: The case of Vossaøl,Norway     

Hans Olav Bråtå 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(5):301-312

The aim of the article is to analyse challenges facing the commercial production of historical beers, which are ‘extinct’ beers. The concept of ‘fictive terroir’ is introduced to emphasize these challenges. The author addresses the following questions: What kind of knowledge is needed to produce historical beers? How can this knowledge be acquired? How can it be used commercially in craft breweries? The studied case is Vossaøl, a craft beer imitation of a beer produced in the early 19th century. The data were obtained from written sources and interviews with local home brewers and brewers at Voss Brewery in Norway. The study revealed the need to reconstruct the terroir in the early 19th century. Additionally, Voss Brewery had to acquire knowledge about how to process and combine the ingredients, which included the traditional yeast (kveik). Involving traditional home brewers was crucial to determine how ingredients could be combined to produce Vossaøl. The author concludes that a synthetic knowledge base was a useful point of departure in this respect. Participation in the traditional culture of brewing proved an important means when working with this knowledge base. The results are interesting in the broader context of the reconstruction of beverages and food.  相似文献   

Méthode de comparaison des régimes pluviaux en météorologie synoptique     

M. Bouët 《Meteorology and Atmospheric Physics》1948,1(1):100-107

Résumé On développe une méthode basée sur le dénombrement des jours de pluite communs à deux stations données et sur l'écart avec leur probabilité. Une formule simple définit l'indice de similitude de deux régimes pluviaux, indice qui peut varier de –1 à +1 et qui caractérise la plus ou moins grande similitude des distributions chronologiques de la pluie en deux endroits quelconques. L'application de la méthode conduit à établir une loi de décroissance de l'indice avec la distance séparant les stations comparées. Dans la région alpine cette loi présente une anomalie résultant de l'effet orographique.

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Summary A method of obtaining a synoptic view of the distribution of precipitation (rain- and snowfall) is developed. It is based on the number of days on which precipitation occurs at both of two places more or less distant from each other. A mathematical definition is given of an index of similarity, which latter varies between –1 and +1. These, limiting, figures signify in the case of –1 that precipitation is least likely to occur on any one day at both of two different places, in the case of +1 that it is most likely to occur, and that when the index of similarity is 0 no relation at all can be established for the likelihood of precipitation at both places on the same day. The index shows a sharp decline as the distance between places increases. In general it shows less relationship in regard to the simultaneous occurrence of rain-and snowfall between places lying on opposite sides of the Alps than between places on the same side, showing once more how the Alps act as a weather partition. The results, based on observations at 9 places in Switzerland and 8 in other European countries, are valid for the Temperate Zone; for other climatic regions they may be different.

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Zusammenfassung Von der Anzahl der gleichzeitigen Niederschlagstage an zwei Beobachtungsstationen und von der Abweichung ihrer Wahrscheinlichkeit ausgehend, wird eine Methode zum Vergleiche der Niederschlagstypen im synoptischen Sinne entwickelt. Der sogenannte Ähnlichkeitsindex, der zwischen –1 und +1 variieren kann, wird mathematisch definiert. Je nach dem Wert desselben ist die zeitliche Verteilung der Niederschlagstage an zwei Orten gleich (+1), indifferent (0) oder entgegengesetzt (–1). Bei der Anwendung der Methode tritt eine gesetzmäßige Abnahme des Index mit der Entfernung auf. Ein entgegengesetztes Verhalten des Ähnlichkeitsindex beiderseits der Alpen veranschaulicht die Rolle, welche die Alpen bekanntlich als Wetterscheide spielen.

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Human mortality impacts of the 2015 summer heat spells in Slovakia     

Dalibor?Vyber?iEmail author  Lívia?Labudová  Milada?E?tóková  Pavol?Fa?ko  Milan?Trizna 《Theoretical and Applied Climatology》2018,133(3-4):925-936

In 2015, Central Europe experienced an unusually warm summer season. For a great majority of climatic stations around Slovakia, it had been the warmest summer ever recorded over their entire instrumental observation period. In this study, we investigate the mortality effects of hot days’ sequences during that particular summer on the Slovak population. In consideration of the range of available mortality data, the position of 2015 is analysed within the years 1996–2015. Over the given 20-year period, the summer heat spells of 2015 were by far the most severe from a meteorological point of view, and clearly the deadliest with the total of almost 540 excess deaths. In terms of impacts, an extraordinary 10-day August heat spell was especially remarkable. The massive lethal effects of heat would have likely been even more serious under normal circumstances, since the number of premature deaths appeared to be partially reduced due to a non-standard mortality pattern in the first quarter of the year. The heat spells of the extremely warm summer of 2015 in Slovakia are notable not just for their short-term response in mortality. It appears that in a combination with the preceding strong influenza season, they subsequently affected mortality conditions in the country in the following months up until the end of the year. The impacts described above were rather different for selected population subgroups (men and women, the elderly). Both separately and as a part of the annual mortality cycle, the 2015 summer heat spells may represent a particularly valuable source of information for public health.  相似文献   

Edge-to-Stem Variability in Wet-Canopy Evaporation From an Urban Tree Row     

John T. Van StanII  Zachary Norman  Adrian Meghoo  Jan Friesen  Anke Hildebrandt  Jean-François Côté  S. Jeffrey Underwood  Gustavo Maldonado 《Boundary-Layer Meteorology》2017,165(2):295-310

Evaporation from wet-canopy (\(E_\mathrm{C}\)) and stem (\(E_\mathrm{S}\)) surfaces during rainfall represents a significant portion of municipal-to-global scale hydrologic cycles. For urban ecosystems, \(E_\mathrm{C}\) and \(E_\mathrm{S}\) dynamics play valuable roles in stormwater management. Despite this, canopy-interception loss studies typically ignore crown-scale variability in \(E_\mathrm{C}\) and assume (with few indirect data) that \(E_\mathrm{S}\) is generally \({<}2\%\) of total wet-canopy evaporation. We test these common assumptions for the first time with a spatially-distributed network of in-canopy meteorological monitoring and 45 surface temperature sensors in an urban Pinus elliottii tree row to estimate \(E_\mathrm{C}\) and \(E_\mathrm{S}\) under the assumption that crown surfaces behave as “wet bulbs”. From December 2015 through July 2016, 33 saturated crown periods (195 h of 5-min observations) were isolated from storms for determination of 5-min evaporation rates ranging from negligible to 0.67 \(\hbox {mm h}^{-1}\). Mean \(E_\mathrm{S}\) (0.10 \(\hbox {mm h}^{-1}\)) was significantly lower (\(p < 0.01\)) than mean \(E_\mathrm{C}\) (0.16 \(\hbox {mm h}^{-1}\)). But, \(E_\mathrm{S}\) values often equalled \(E_\mathrm{C}\) and, when scaled to trunk area using terrestrial lidar, accounted for 8–13% (inter-quartile range) of total wet-crown evaporation (\(E_\mathrm{S}+E_\mathrm{C}\) scaled to surface area). \(E_\mathrm{S}\) contributions to total wet-crown evaporation maximized at 33%, showing a general underestimate (by 2–17 times) of this quantity in the literature. Moreover, results suggest wet-crown evaporation from urban tree rows can be adequately estimated by simply assuming saturated tree surfaces behave as wet bulbs, avoiding problematic assumptions associated with other physically-based methods.  相似文献   

Rapid cooling and geospeedometry of granitic rocks exhumation within a volcanic arc: A case study from the Central Slovakian Neovolcanic Field (Western Carpathians)          下载免费PDF全文

Milan Kohút  Martin Danišík 《Island Arc》2017,26(5)

U–Pb Sensitive High‐Resolution Ion MicroProbe (SHRIMP) dating of zircon in combination with (U–Th)/He dating of zircon and apatite is applied to constrain the emplacement and exhumation history of the youngest granitic rocks in the Western Carpathians collected in the Central Slovakian Neovolcanic Field. Two samples of diorite from the locality Banky, and granodiorite from Banská Hodru?a yield the U–Pb zircon concordia ages of 15.21 ±0.19 Ma and 12.92 ±0.27 Ma, respectively, recording the time of zircon crystallization and the intrusions’ emplacement. Zircon (U–Th)/He ages of 14.70 ±0.94 (Banky) and 12.65 ±0.61 Ma (Banská Hodru?a), and apatite (U–Th)/He ages of 14.45 ±0.70 Ma (diorite) and 12.26 ±0.77 Ma (granodiorite) are less than 1 Myr younger than the corresponding zircon U–Pb ages. For both diorite and granodiorite rocks their chronological data thus document a simple cooling process from magmatic crystallization/solidification temperatures to near‐surface temperatures in the Middle Miocene, without subsequent reheating. Geospeedometry data suggest for rapid cooling at an average rate of 678 ±158 °C/Myr, and the exhumation rate of 5 mm/year corresponding to active tectonic‐forced exhumation. The quick cooling is interpreted to record the exhumation of the studied granitic rocks complex that closely followed its emplacement, and was likely accompanied by a drop in the paleo‐geothermal gradient due to cessation of volcanic activity in the area.  相似文献