Estimation and prediction of the spatial occurrence of fish species using Bayesian latent Gaussian models

A methodological approach for modelling the occurrence patterns of species for the purpose of fisheries management is proposed here. The presence/absence of the species is modelled with a hierarchical Bayesian spatial model using the geographical and environmental characteristics of each fishing location. Maps of predicted probabilities of presence are generated using Bayesian kriging. Bayesian inference on the parameters and prediction of presence/absence in new locations (Bayesian kriging) are made by considering the model as a latent Gaussian model, which allows the use of the integrated nested Laplace approximation ( INLA ) software (which has been seen to be quite a bit faster than the well-known MCMC methods). In particular, the spatial effect has been implemented with the stochastic partial differential equation (SPDE) approach. The methodology is evaluated on Mediterranean horse mackerel (Trachurus mediterraneus) in the Western Mediterranean. The analysis shows that environmental and geographical factors can play an important role in directing local distribution and variability in the occurrence of species. Although this approach is used to recognize the habitat of mackerel, it could also be for other different species and life stages in order to improve knowledge of fish populations and communities.     

Structural-stratigraphic control on the Umitaka Spur gas hydrates of Joetsu Basin in the eastern margin of Japan Sea

Integrated geological, geochemical, and geophysical exploration since 2004 has identified massive accumulation of gas hydrate associated with active methane seeps on the Umitaka Spur, located in the Joetsu Basin on the eastern margin of Japan Sea. Umitaka Spur is an asymmetric anticline formed along an incipient subduction zone that extends throughout the western side of the Japanese island-arc system. Seismic surveys recognized chimney structures that seem strongly controlled by a complex anticlinal axial fault system, and exhibit high seismic amplitudes with apparent pull-up structures, probably due to massive and dense accumulation of gas hydrate. Bottom simulating reflectors are widely developed, in particular within gas chimneys and in the gently dipping eastern flank of the anticline, where debris can store gas hydrates that may represent a potential natural gas resource. The axial fault system, the shape of the anticline, and the carrier beds induce thermogenic gas migration to the top of the structure, and supply gas to the gas hydrate stability zone. Gas reaching the seafloor produces strong seepages and giant plumes in the sea water column.     

Evaluation of MIVIS Hyperspectral Data for Mapping Soil Degradation in an Upland Ecosystem of Southern Italy

Abstract

This paper describes the first stage of an experiment aiming to evaluate the potential and limitations of MIVIS data for mapping the degradational state of soils in a sub‐scene of a southern Apennines study area (Italy). After radiometric rectification of the image data and the collection of a field/laboratory spectral library, linear spectral mixture modelling (SMA) was used to decompose image spectra into fractions of spectrally distinct mixing components. Spectral endmember selection was based upon a principal component analysis (PCA) applied to a set of soil spectra, collected from the spectral library. The resulting abundance estimates (fractions) trough SMA were then analysed to identify soil conditions and to obtain an improved measure of dry and green vegetation cover. A map of soil conditions and dry‐green vegetation abundance, based upon MIVIS data was then derived from normalised fractions of soil‐vegetation endmembers obtained from SMA.     

Collaborative Web‐GIS Design: A Case Study for Road Risk Analysis and Monitoring

This article presents a methodology for designing a WebGIS framework intended for automatically analyzing spatial data and updating statistics of interest with new information inserted daily by multiple users via a Web portal. A practical example is used on vehicle accident data for assessing risk in specific road segments. Two main blocks integrated together will be described: the collaborative block and the data‐analysis block. The former gives end‐users computer‐aided tools to view, insert, modify and manage data related to accidents and traffic monitoring sensors, whereas the latter is developed to automatically analyze the accident data coming from user's collaboration. Because different agencies can survey accident sites, a collaborative environment is necessary – and a Web‐based solution is ideal – for permitting multi‐user access and data insertion. A centralized approach to process the data in real time is described in all its components. Server‐side Structured Query Language functions optimize performance by using dedicated libraries for spatial processing and re‐structuring the attributes associated with elements which are consequently re‐classified for correct color‐scaling. The end‐product is a system that provides a seamless integration of front‐end tools for user collaboration and back‐end tools to update accident risk statistics in real time and provide them to stakeholders.     

Jurassic‐to‐present thermal history of the central High Atlas (Morocco) assessed by low‐temperature thermochronology

Apatite fission track (AFT) and (U–Th)/He data from the High Atlas have been obtained for the first time to constrain the tectono‐thermal evolution of the central part of the chain. Results from Palaeozoic basement massifs indicate long residence at low temperatures, consistently with their original location out of the deepest Mesozoic rift troughs and indicating minor exhumation. The best rocks for extracting the Alpine history of the Atlas Mountains are Jurassic intrusives, which yield AFT ages centred on c. 80 Ma; thermal models based on AFT data and constrained by (U–Th)/He suggest that these ages are included in a slow cooling trend from intrusion age to c. 50 Ma ago that we attribute to post‐rift thermal relaxation. This is followed by a stability period of c. 30 Ma and then by a final exhumational cooling until present exposure. Eocene intrusives yield AFT ages similar to those of Rb–Sr and K–Ar suggesting rapid emplacement in the uppermost crust.     

Observations of shocked [FeII] and H2 line profiles in orion bullet wakes

Recent near-IR imaging of the Orion molecular cloud has revealed a complex of dense bullets, visible as [FeII] emitting HH-objects at the tips of H₂ wakes, ejected explosively from the cloud core. Having resolved individual bow-shock structures for the first time in this bright source, we have observed [FeII] 1.644µm velocity profiles of selected bullets and H₂ 1-0 S(1), 2.122µm velocity profiles for a series of positions along and across the corresponding bow-shock wakes. We present observed profiles for the bullet M42 HH1 and its associated wake and compare with theoretical bow-shock models.     

Ondes de surface

Résumé Le but de ce mémoire est de démontrer quelques nouvelles propriétés générales d'une classe de fonctions (les ondes de surface) très importante par son rôle en physique et en géophysique.On commence par la démontration d'un théoréme fondamental qui établit l'identité de l'ensemble des ondes de surface et de l'ensemble des fonctions pour lesquelles, à tout instantt ₀ et en tout pointA ₀ de leur domaine d'existence, on peut écrire une proportionnalité entre intervalles de temps (situés, en général asymétriquement, de part et d'autre det ₀) et rayons des domaines circulaires centrés enA ₀, telle que les moyennes temporelles et spatiales correspondantes soient égales. Ce théorème permet d'écrire, en termes finis, la solution des équations aux dérivées partielles de toute onde de surface.On applique ensuite les résultats généraux: 1° à la variation diurne de la pression lce qui permet de voir que ce phénomène peut être considéré comme une onde de surface et donne la loi fondamentale en cos³ ( latitude) pour l'amplitude de l'onde semidiurne progressive]; 2° aux ondes de variation de la pression synoptique. Pour ces ondes de variation on établit les relations qui existent entre leurs paramètres caractéristiques et on détermine finalement leur configuration théorique.

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Summary The aim of this paper is to give the proof of some new general properties of a class of functions (the surface waves) which is very important in physics and geophysics.We first give the proof of a fundamental theorem establishing the identity of the set of all surface waves and the set of functions for which, at any momentt ₀ and at any pointA ₀ of their domain, there exists a proportionality between time intervals comprisingt ₀ (asymmetrically, in the general case) and the radius of the circular domains centered onA ₀, such that the corresponding temporal and spatial means are equal. This theorem allows to write in finite terms the solution of the partial differential equations of any surface wave.The general results are then applied: 1° to the diurnal pressure variation, showing that this phenomenon can be considered as a surface wave and giving the fundamental law cos³ ( latitude) for the amplitude of the progressive or travelling 12-hourly wave; 2° to the waves of the synoptic pressure variations. For these waves the relations between their characteristic parameters is first established and finally their theoretical spatial configuration or pattern is deduced.

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Communication faite le 23 Avril 1957 à la Cinquième Assemblée de la «Società Italiana di Geofisica e Meteorologia» (Genova, 23–25 Avril 1957).