Numerical modeling of space-time wave extremes using WAVEWATCH III     

Francesco Barbariol  Jose-Henrique G. M. Alves  Alvise Benetazzo  Filippo Bergamasco  Luciana Bertotti  Sandro Carniel  Luigi Cavaleri  Yung Y. Chao  Arun Chawla  Antonio Ricchi  Mauro Sclavo  Hendrik Tolman 《Ocean Dynamics》2017,67(3-4):535-549

A novel implementation of parameters estimating the space-time wave extremes within the spectral wave model WAVEWATCH III (WW3) is presented. The new output parameters, available in WW3 version 5.16, rely on the theoretical model of Fedele (J Phys Oceanogr 42(9):1601-1615, 2012) extended by Benetazzo et al. (J Phys Oceanogr 45(9):2261–2275, 2015) to estimate the maximum second-order nonlinear crest height over a given space-time region. In order to assess the wave height associated to the maximum crest height and the maximum wave height (generally different in a broad-band stormy sea state), the linear quasi-determinism theory of Boccotti (2000) is considered. The new WW3 implementation is tested by simulating sea states and space-time extremes over the Mediterranean Sea (forced by the wind fields produced by the COSMO-ME atmospheric model). Model simulations are compared to space-time wave maxima observed on March 10th, 2014, in the northern Adriatic Sea (Italy), by a stereo camera system installed on-board the “Acqua Alta” oceanographic tower. Results show that modeled space-time extremes are in general agreement with observations. Differences are mostly ascribed to the accuracy of the wind forcing and, to a lesser extent, to the approximations introduced in the space-time extremes parameterizations. Model estimates are expected to be even more accurate over areas larger than the mean wavelength (for instance, the model grid size).  相似文献   

Influence of volcanic glass on the magnetic signal of different paleosols in Córdoba,Argentina     

Sabrina Rouzaut  María Julia Orgeira 《Studia Geophysica et Geodaetica》2017,61(2):361-384

This contribution comprises geological and magnetic results obtained in loess and paleosols profiles outcropped in the Pampean plain (Argentina). The sedimentary sequence exposed in Córdoba province is represented by four profiles Corralito I, Corralito II, Monte Ral815o and Lozada, 32°S 64°14'W (Argentina). These profiles were mineralogically described and magnetically analyzed. The sediments that compound the profiles contain volcanic glass between 20 and 90%. The results of two paleosols with different percentage of volcanic glass in the parent material (correlated to Marine Isotope Stage 5, MIS 5) exposed at Corralito I and Lozada, were compared; an important relationship between environmental magnetism signal and volcanic glass content was observed. All the results suggest that there are variations between different paleosols of the same area and age; such variations are attributed to content of volcanic glass in parent material; time of exposure of the parent material to pedogenic processes; and geomorphological place of each profile. At present, it is not possible to quantify certainly the paleo-precipitation index. Only qualitative interpretation can be done taking into account many variables of the geological system.  相似文献   

Genetic diversity in old populations of sessile oak from Calabria assessed by nuclear and chloroplast SSR     

Antonio LUPINI  Meriem Miyassa ACI  Antonio MAUCERI  Giuseppe LUZZI  Silvio BAGNATO  Giuliano MENGUZZATO  Francesco MERCATI  Francesco SUNSERI 《山地科学学报》2019,(5)

In the framework of forest resources conservation, this study aims to understand the dynamic and the genetic structure of sessile oak forests in Calabria, Italy. Two old populations of sessile oak(Quercus petraea(Mattuschka) Liebl.) from two areas of Sila and Aspromonte massifs in Calabria were analyzed for genetic diversity and population structure based on 6 nuclear simple sequence repeat(nSSR) and 4 chloroplastic SSR(cpSSR) loci. The populations displayed high amount of genetic diversity, which was toughly structured according to their geographical origins. Number of alleles at SSR loci ranged from 11 to 20 with an average of 13.5 per locus. Gene diversity(expected heterozygosity, He) estimates ranged from 0.575 to 0.834 with a mean of 0.749. The observed heterozygosity(Ho) was on average 0.458 ranging from 0.150 to 0.682. Polymorphism information content(PIC) values ranged from 0.625 to 0.865 with an average of 0.787. The analysis of molecular variance(AMOVA) highlighted a significant higher estimated variance within populations compared to among populations. Finally, the analysis of haplotypes by using cpSSR suggested a higher diversification in the population from Sila. Hierarchical clustering analysis grouped the genotypes into two major clusters, which agreed with the geographic origin of populations, and was confirmed by the Discriminant Analysis of Principal Components(DAPC). The first cluster included plants/population from Sila massif, while the second encompassed mostly plants/population sampled in Aspromonte massif. Finally, model-based clustering by STRUCTURE analysis also supported the presence of clear genetic structuring in the collection with two major populations(K=2) supported to PCoA analysis as well. Finally, our data indicated the Aspromonte population as a marginal forest with fragmented distribution suggesting different strategies of preservation than in Sila massif.  相似文献   

Drought and Spatiotemporal Variability of Forest Fires Across Mexico     

Pompa-García MARíN  Camarero J.JULIO  Rodríguez-Trejo DANTE ARTURO  Vega-Nieva DANIEL JOSE 《中国地理科学(英文版)》2018,28(1):25-37

Understanding the spatiotemporal links between drought and forest fire occurrence is crucial for improving decision-making in fire management under current and future climatic conditions. We quantified forest fire activity in Mexico using georeferenced fire records for the period of 2005–2015 and examined its spatial and temporal relationships with a multiscalar drought index, the Standardized Precipitation-Evapotranspiration Index(SPEI). A total of 47975 fire counts were recorded in the 11-year long study period, with the peak in fire frequency occurring in 2011. We identified four fire clusters, i.e., regions where there is a high density of fire records in Mexico using the Getis-Ord G spatial statistic. Then, we examined fire frequency data in the clustered regions and assessed how fire activity related to the SPEI for the entire study period and also for the year 2011. Associations between the SPEI and fire frequency varied across Mexico and fire-SPEI relationships also varied across the months of major fire occurrence and related SPEI temporal scales. In particular, in the two fire clusters located in northern Mexico(Chihuahua, northern Baja California), drier conditions over the previous 5 months triggered fire occurrence. In contrast, we did not observe a significant relationship between drought severity and fire frequency in the central Mexico cluster, which exhibited the highest fire frequency. We also found moderate fire-drought associations in the cluster situated in the tropical southern Chiapas where agriculture activities are the main causes of forest fire occurrence. These results are useful for improving our understanding of the spatiotemporal patterns of fire occurrence as related to drought severity in megadiverse countries hosting many forest types as Mexico.  相似文献   

Analysis of impulsive maneuvers to keep orbits around the asteroid 2001SN<Subscript>263</Subscript>     

Willer G. Santos  Antonio F. B. A. Prado  Geraldo M. C. Oliveira  Leonardo B. T. Santos 《Astrophysics and Space Science》2018,363(1):14

The strongly perturbed environment of a small body, such as an asteroid, can complicate the prediction of orbits used for close proximity operations. Inaccurate predictions may make the spacecraft collide with the asteroid or escape to the deep space. The main forces acting in the dynamics come from the solar radiation pressure and from the body’s weak gravity field. This paper investigates the feasibility of using bi-impulsive maneuvers to avoid the aforementioned non-desired phenomena (collisions and escapes) by connecting orbits around the triple system asteroid 2001SN₂₆₃, which is the target of a proposed Brazilian space mission. In terms of a mathematical formulation, a recently presented rotating dipole model is considered with oblateness in both primaries. In addition, a “two-point boundary value problem” is solved to find a proper transfer trajectory. The results presented here give support to identifying the best strategy to find orbits for close proximity operations, in terms of long orbital lifetimes and low delta-\(V\) consumptions. Numerical results have also demonstrated the significant influence of the spacecraft orbital elements (semi-major axis and eccentricity), angular position of the Sun and spacecraft area-to-mass ratio, in the performance of the bi-impulsive maneuver.  相似文献   

Perihelion precession in binary systems: higher order corrections     

Carlos Marín  Jorge Poveda 《Astrophysics and Space Science》2018,363(12):245

Higher order corrections (up to n-th order) are obtained for the perihelion precession in binary systems like OJ287 using the Schwarzschild metric and complex integration. The corrections are performed considering the third root of the motion equation and developing the expansion in terms of \(r_{s}/ (a(1-e^{2}) )\).The results are compared with other expansions that appear in the literature giving corrections to second and third order. Finally, we simulate the shape of relativistic orbits for binary systems with different masses.  相似文献   

Thermodynamic exchanges between the external boundary layer and the indoor microclimate at the Basilica of Santa Maria Maggiore, Rome, Italy: the problem of conservation of ancient works of art     

Dario Camuffo  Giovanni Sturaro  Antonio Valentino 《Boundary-Layer Meteorology》1999,92(2):243-262

The Basilica of Santa Maria Maggiore, Rome, is an example of how ancient buildings with thick walls lessen the impact of the external temperature and humidity variations. The external influence on the internal microclimate is studied in order to gather information on how the building exchanges heat and moisture. Correlations between outdoor and indoor values are found. The results are applied to the calculation of the condensation-evaporation cycles inside micropores due to the Kelvin effect, to assess their impact on works of arts placed inside and outside the Basilica. It was found that the building attenuation is not sufficient to avoid damage due to condensation-evaporation cycles on stones and plasters. Some suggestions are made in order to mitigate the temperature variations during the liturgical offices.  相似文献   

Periodic Orbits Around a Massive Straight Segment   总被引：1，自引：0，他引：1  

Andrés Riaguas  Antonio Elipe  Martín Lara 《Celestial Mechanics and Dynamical Astronomy》1999,73(1-4):169-178

In this paper, we consider the motion of a particle under the gravitational field of a massive straight segment. This model is used as an approximation to the gravitational field of irregular shaped bodies, such as asteroids, comet nuclei and planets's moons. For this potential, we find several families of periodic orbits and bifurcations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Natural metastable reactions involving garnet, staurolite and cordierite: implications for petrogenetic grids and the extensional collapse of the Betic-Rif Belt     

Antonio García-Casco  Rafael Luis Torres-Roldán 《Contributions to Mineralogy and Petrology》1999,136(1-2):131-153

Medium grade metapelites of the Torrox unit (Betic-Rif Belt, S Spain) contain mineral assemblages consisting of garnet (Grt), staurolite (St), cordierite (Crd), biotite, kyanite, sillimanite, andalusite, muscovite (Ms) and quartz (Qtz) and record complex reaction processes of cordierite growth through garnet and staurolite decomposition. The reaction textures, the chemical composition of the reactant and product phases, including Fe-Mg-Mn partitioning, and the results of equilibrium thermodynamic calculations indicate that these cordierite-bearing assemblages are largely deviated from equilibrium. Furthermore, the actual cordierite-forming reactions, as estimated from the assemblage and associated textures, conflict with the predictions of thermodynamically based petrogenetic grids for the model pelite system KFMASH, either those that predict the stable coexistence of cordierite + muscovite plus garnet or staurolite or those that do not foresee a field of stability for these types of assemblages. This conflict is explained in terms of cordierite growth (at ca. 575 °C and 2.5 kbar) through metastable reactions whose operation was conditioned by the relict persistence of higher pressure phases (garnet and staurolite) and phase compositions (e.g. muscovite and biotite) after fast decompression. This interpretation militates against the existence of a wide P-T range of stable coexistence at low P of Crd + Ms + Qtz ± Grt ± St in medium grade metapelites of normal composition (i.e. poor in Zn and/or Mn). The triggering of metastable cordierite-forming reactions and the preservation of even subtle disequilibrium features associated to them indicate that the rocks underwent fast near-isothermal decompression from ca. 12 kbar down to 2–3 kbar, then rapid cooling. These inferences agree with independent evidence indicating that termination of alpine metamorphism in the western Betic-Rif Belt was related to the extensional collapse of thickened crust and that the latter had consisted of a single, continuous event. Received: 6 August 1998 / Accepted: 9 February 1999  相似文献   

A global analysis of the 1991 geomagnetic jerk     

Paola De Michelis  Lili Cafarella  Antonio Meloni 《Geophysical Journal International》2000,143(3):545-556

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