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31.
Sandrine Roy Riccardo Vassallo Joseph Martinod Matías C. Ghiglione Christian Sue Pascal Allemand 《地学学报》2020,32(1):1-10
Across the extreme south of Patagonia, the Magallanes‐Fagnano Fault (MFF) accommodates the left‐lateral relative motion between South America and Scotia plates. In this paper, we present an updated view of the geometry of the eastern portion of the MFF outcropping in Tierra del Fuego. We subdivide the MFF in eight segments on the basis of their deformation styles, using field mapping and interpretation of high‐resolution imagery. We quantify coseismic ruptures of the strongest recorded 1949, Mw7.5 earthquake, and determine its eastern termination. We recognize several co‐seismic offsets in man‐made features showing a sinistral shift up to 6.5 m, greater than previously estimated. Using 10Be cosmogenic nuclides depth profiles, we date a cumulated offset in post‐glacial morphologies and estimate the long‐term slip rate of the eastern MFF. We quantify a 6.4 ± 0.9 mm/a left‐lateral fault slip rate, which overlaps geodetic velocity and suggests stable fault behaviour since Pleistocene. 相似文献
32.
The averaged spin-orbit resonant motion of Mercury is considered, with e the orbital eccentricity, and i o the orbital inclination introduced as very slow functions of time, given by any secular planetary theory. The basis is our Hamiltonian approach (D’Hoedt, S., Lemaître, A.: Celest. Mech. Dyn. Astron. 89:267–283, 2004) in which Mercury is considered as a rigid body. The model is based on two degrees of freedom; the first one is linked to the 3:2 resonant spin-orbit motion, and the second one to the commensurability of the rotational and orbital nodes. Mercury is assumed to be very close to the Cassini equilibrium of the model. To follow the motion of rotation close to this equilibrium, which varies with respect to time through e and i o , we use the adiabatic invariant theory, extended to two degrees of freedom. We calculate the corrections (remaining functions) introduced by the time dependence of e and i o in the three steps necessary to characterize the frequencies at the equilibrium. The conclusion is that Mercury follows the Cassini equilibrium (stays in the Cassini forced state), in an adiabatic behavior: the area around the equilibrium does not change by more than ${\varepsilon}$ for times smaller than ${\frac{1}{\varepsilon}}$ . The role of the inclination and the eccentricity can be dissociated and measured in each step of the canonical transformation. 相似文献
33.
Sandrine Vinatier Bruno Bézard Andrei Mamoutkine Ronald C. Carlson Donald E. Jennings Nick A. Teanby F. Michael Flasar 《Icarus》2010,205(2):559-570
Observations of the Composite InfraRed Spectrometer (CIRS) during the entire nominal Cassini mission (2004-2008) provide us with an accurate global view of composition and temperature in the middle atmosphere of Titan (between 100 and 500 km). We investigated limb spectra acquired at resolution at nine different latitudes between 56°S and 80°N, with a better sampling in the northern hemisphere where molecular abundances and temperature present strong latitudinal variations. From this limb data acquired between February 2005 and May 2008, we retrieved the vertical mixing ratio profiles of C2H2, C2H4, C2H6, C3H8, CH3C2H, C4H2, C6H6, HCN, HC3N and CO2. We present here for the first time, the latitudinal variations of the C2H6, C3H8, CO2, C2H4 and C6H6 vertical mixing ratios profiles. Some molecules, such as C2H6 or C3H8 present little variations above their condensation level. The other molecules (except CO2) show a significant enhancement of their mixing ratios poleward of 50°N. C2H4 is the only molecule whose mixing ratio decreases with height at latitudes below 46°N. Regions depleted in C2H2, HCN and C4H2 are observed around 400 km (0.01 mbar) and 55°N. We also inferred a region enriched in CO2 located between 30 and 40°N in the 2-0.7 mbar pressure range. At 80°N, almost all molecules studied here present a local minimum of their mixing ratio profiles near 300 km (∼0.07 mbar), which is in contradiction with Global Circulation Models that predict constant-with-height vertical profiles due to subsidence at the north pole. 相似文献
34.
The paper develops a hamiltonian formulation describing the coupled orbital and spin motions of a rigid Mercury rotation about
its axis of maximum moment of inertia in the frame of a 3:2 spin orbit resonance; the (ecliptic) obliquity is not constant,
the gravitational potential of mercury is developed up to the second degree terms (the only ones for which an approximate
numerical value can be given) and is reduced to a two degree of freedom model in the absence of planetary perturbations. Four
equilibria can be calculated, corresponding to four different values of the (ecliptic) obliquity. The present situation of
Mercury corresponds to one of them, which is proved to be stable. We introduce action-angle variables in the neighborhood
of this stable equilibrium, by several successive canonical transformations, so to get two constant frequencies, the first
one for the free spin-orbit libration, the other one for the 1:1 resonant precession of both nodes (orbital and rotational)
on the ecliptic plane. The numerical values obtained by this simplified model are in perfect agreement with those obtained
by Rambaux and Bois [Astron. Astrophys. 413, 381–393].
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
35.
D. Dubreuil J. L. Sauvageot C. Blondel G. Dhenain P. Mestreau P. Mulet 《Experimental Astronomy》1995,6(3):257-273
In this paper we present a new spectrophotometer ESOP (Expérience Spectroscopique d'Observation des Plasmas). We describe its general features and characteristics. We report the first spectrophotometric results on the Puppis A supernova remnant on the coronal iron line emission. These [FeXIV] observations were in the vicinity of the Eastern X-ray knot. We have observed at 30 scale. In appendices we describe in more details some specific technical points.Based on observations obtained at ESO-La Silla Observatory. 相似文献
36.
The distribution and speciation of mercury (Hg) in the water column, the inputs (wet deposition and tributaries) and the outputs (atmospheric evasion and outlet) of an artificial partially anoxic tropical lake (Petit-Saut reservoir, French Guiana) were investigated on a seasonal basis in order to appraise the cycling and transformations of this metal. The total mercury (HgT) concentrations in the oxygenated epilimnetic waters averaged 5 ± 3 pmol L−1 in the unfiltered samples (HgTUNF) and 4 ± 2 pmol L−1 in the dissolved (HgTD) phase (<0.45 μm). On average, the monomethylmercury (MMHg) constituted 8%, 40% and 18% of the HgT in the dissolved phase, the particulate suspended matter and in the unfiltered samples, respectively. Covariant elevated concentrations of particulate MMHg and chlorophyll a in the epilimnion suggest that phytoplankton is an active component for the MMHg transfer in the lake. In the anoxic hypolimnion the HgTUNF averages 13 ± 6 pmol L−1 and the HgTD 8 ± 4 pmol L−1. The averages of MMHgP and MMHgD in hypolimnetic waters were two and three times the corresponding values of the epilimnion, 170 ± 90 pmol g−1 and 0.9 ± 0.5 pmol L−1, respectively. In the long dry and wet seasons, at the flooded forest and upstream dam sampling stations, the vertical profiles of MMHgD concentrations accounted for two distinct maxima: one just below the oxycline and the other near the benthic interface. Direct wet atmospheric deposition accounted for 14 moles yr−1 HgTUNF, with 0.7 moles yr−1 as MMHgUNF, while circa 76 moles yr−1 of HgTUNF, with 4.7 moles yr−1 as MMHgUNF, coming from tributaries. Circa 78 moles (∼17% as MMHg) are annually exported through the dam, while 23 moles yr−1 of Hg0 evolve in the atmosphere. A mass balance calculation suggests that the endogenic production of MMHgUNF attained 8.1 moles yr−1, corresponding to a methylation rate of 0.06% d−1. As a result, the Petit-Saut reservoir is a large man-made reactor that has extensively altered mercury speciation in favor of methylated species. 相似文献
37.
38.
Sandrine Mathy Patrick Criqui Katharina Knoop Manfred Fischedick Sascha Samadi 《Climate Policy》2016,16(4):S47-S62
Contrary to ‘static’ pathways that are defined once for all, this article deals with the need for policy makers to adopt a dynamic adaptive policy pathway for managing decarbonization over the period of implementation. When choosing a pathway as the most desirable option, it is important to keep in mind that each decarbonization option relies on the implementation of specific policies and instruments. Given structural, effectiveness, and timing uncertainties specific to each policy option, they may fail in delivering the expected outcomes in time. The possibility of diverging from an initial decarbonization trajectory to another one without incurring excessive costs should therefore be a strategic element in the design of an appropriate decarbonization strategy. The article relies on initial experiences in France and Germany on decarbonization planning and implementation to define elements for managing dynamic adjustment issues. Such an adaptive pathway strategy should combine long-lived incentives, like a pre-announced escalating carbon price, to form consistent expectations, as well as adaptive policies to improve overall robustness and resilience. We sketch key elements of a monitoring process based on an ex ante definition of leading indicators that should be assessed regularly and combined with signposts and trigger values at the subsector level.Policy relevanceThese research questions are of special interest and urgency following the Paris Agreement in 2015. It calls on all countries to monitor the implementation of their national contributions and review their ambition regularly. The regular revision of decarbonization pathways constitute a great research opportunity to gather experiences on decarbonization pathway implementation and on dynamic management issues to progress towards an operational dynamic adaptive policy pathway mechanism. 相似文献
39.
Shallow cumulus clouds in the trade-wind regions are at the heart of the long standing uncertainty in climate sensitivity estimates. In current climate models, cloud feedbacks are strongly influenced by cloud-base cloud amount in the trades. Therefore, understanding the key factors controlling cloudiness near cloud-base in shallow convective regimes has emerged as an important topic of investigation. We review physical understanding of these key controlling factors and discuss the value of the different approaches that have been developed so far, based on global and high-resolution model experimentations and process-oriented analyses across a range of models and for observations. The trade-wind cloud feedbacks appear to depend on two important aspects: (1) how cloudiness near cloud-base is controlled by the local interplay between turbulent, convective and radiative processes; (2) how these processes interact with their surrounding environment and are influenced by mesoscale organization. Our synthesis of studies that have explored these aspects suggests that the large diversity of model responses is related to fundamental differences in how the processes controlling trade cumulus operate in models, notably, whether they are parameterized or resolved. In models with parameterized convection, cloudiness near cloud-base is very sensitive to the vigor of convective mixing in response to changes in environmental conditions. This is in contrast with results from high-resolution models, which suggest that cloudiness near cloud-base is nearly invariant with warming and independent of large-scale environmental changes. Uncertainties are difficult to narrow using current observations, as the trade cumulus variability and its relation to large-scale environmental factors strongly depend on the time and/or spatial scales at which the mechanisms are evaluated. New opportunities for testing physical understanding of the factors controlling shallow cumulus cloud responses using observations and high-resolution modeling on large domains are discussed. 相似文献
40.
Sandrine D’Hoedt Benoît Noyelles Julien Dufey Anne Lemaître 《Celestial Mechanics and Dynamical Astronomy》2010,107(1-2):93-100
The resonant rotation of Mercury can be modelised by a kernel model on which we can add perturbations. Our kernel model is a two-degree of freedom one written in Hamiltonian formalism. For this kernel, we consider that Mercury is solid and rotates on a Keplerian orbit. By introducing the perturbations due to the other planets of the Solar System, it appears that, in a particular case, our slow degree of freedom may enter into a 1:1 resonance with the Great Inequality of Jupiter and Saturn. Actually, as the moments of inertia of Mercury are still poorly known, this phenomenon cannot be excluded. 相似文献