Orbital Elements of 2004 Perseid Meteoroids Perturbed by Jupiter

Jupiter and Saturn produce important gravitational impulses on meteoroids released by comet 109P/Swift-Tuttle. The meteoroids from this comet once released follow retrograde orbits that during their periodic approaches to these planets (within 1.6 and 0.9 A.U., respectively) are impulsed gaining orbital energy. This perturbation effect is translated into a net inward shift in the node of the perturbed meteoroids. Such geometry with Jupiter occurred in 2004 over a meteoroid trail ejected by this comet during the 1862 A.D. return of the comet to perihelion. In order to study the predicted outburst produced by one-revolution meteoroids, the Spanish Photographic Meteor Network (SPMN) performed an extensive campaign. As a part of this observational effort here are presented 10 accurate meteoroid orbits. We discuss their origin by comparing them with the theoretical orbital elements of the dust trails intercepting the Earth during the 2004 Perseid return.     

The 29 September 2009 Samoa Islands Tsunami: Simulations Based on the First Focal Mechanism Solutions and Implications on Tsunami Early Warning Strategies

The tsunamigenic earthquake (Mw?=?8.1) that occurred on 29 September 2009 at 17:48 UTC offshore of the Samoa archipelago east of the Tonga trench represents an example of the so-called ??outer-rise?? earthquakes. The areas most affected were the south coasts of Western and American Samoa, where almost 200 people were killed and run-up heights were measured in excess of 5?m at several locations along the coast. Moreover, tide gauge records showed a maximum peak-to-peak height of about 3.5?m near Pago Pago (American Samoa) and of 1.5?m offshore of Apia (Western Samoa). In this work, different fault models based on the focal mechanism solutions proposed by Global CMT and by USGS immediately after the 2009 Samoan earthquake are tested by comparing the near-field recorded signals (three offshore DART buoys and two coastal tide gauges) and the synthetic signals provided by the numerical simulations. The analysis points out that there are lights and shadows, in the sense that none of the computed tsunamis agrees satisfactorily with all the considered signals, although some of them reproduce some of the records quite well. This ??partial agreement?? and ??partial disagreement?? are analysed in the perspective of tsunami forecast and of Tsunami Early Warning System strategy.     

Kinetics of the reactions of Cl atoms with 2-buten-1-ol, 2-methyl-2-propen-1-ol, and 3-methyl-2-buten-1-ol as a function of temperature

The reactions of three structurally similar unsaturated alcohols, 2-buten-1-ol (crotyl alcohol), 2-methyl-2-propen-1-ol (MPO221) and 3-methyl-2-buten-1-ol (MBO321) with Cl atoms, have been investigated for the first time, using a 400 l Teflon reaction chamber coupled with gas chromatograph-coupled with flame-ionization detection (GC-FID). The experiments were performed at atmospheric pressure and at temperatures between 255 and 298 K, in air or nitrogen as the bath gas. The obtained kinetic data were used to derive the Arrhenius expressions , , (in units of cm³ molecule⁻¹ s⁻¹). Finally, atmospheric lifetimes of those unsaturated alcohols with respect to OH, NO₃, O₃ and Cl have been calculated.     

Community structure and dynamics of deep-water decapod assemblages from Le Danois Bank (Cantabrian Sea, NE Atlantic): Influence of environmental variables and food availability

The community structure of the decapod crustaceans inhabiting Le Danois Bank (Cantabrian Sea, NE Atlantic Ocean) was studied on two cruises performed in October 2003 and April 2004. Otter and beam-trawls were used to collect this fauna. At depths ranging between 455 and 1048 m, we found distinct decapod assemblages on the bank summit and deeper in the inner basin (between the bank and the continental shelf). The faunal discontinuity between these groups appeared at around 600 m (e.g. between 612 and 642 m in the basis of species replacement). The summit assemblage was characterized by low diversity (in terms of number and relative abundances of species) and by the dominance of hermit crabs (Pagurus alatus, Anapagurus laevis, Pagurus excavatus), the crangonid Pontophilus spinosus and the squat lobster Munida sarsi. Species characterizing the deeper assemblage, which was richer in terms of diversity, were Munida tenuimana, Parapagurus pilosimanus, Pontophilus norvegicus, the crab Geryon trispinosus and a number of bathypelagic shrimps (Sergia robusta, Acanthephyra pelagica and Pasiphaea tarda). Changes in decapod composition characterized by multidimensional scaling analyses were correlated with different variables, e.g. %mud and %organic matter (OM), temperature and salinity close to the bottom. Among those the %OM and %mud in sediments affected decapod distributions the most. The summit of the bank was covered by fine sediments with low proportion of mud (13.9–29.3%) and OM (2.55–3.50%). By contrast, sediment of the inner basin had a higher proportion of OM and mud (64.1–84.2%; 6.26–7.00%, respectively). The low proportion of mud at the summit of Le Danois Bank may explain the absence or scarcity of burrowing species (e.g. the lobster Nephrops norvegicus, the shrimps Calocaris macandreae and Alpheus glaber and the crab Goneplax rhomboides), that are dominant at similar depths (400–500 m) in the upper muddy assemblage on the mainland-continental slope in the Bay of Biscay (44–46°N). The dominance of certain species on the summit of submarine mounts can probably be related to their biology and feeding ecology. For example, pagurids are deposit feeders, even consuming marine snow (e.g. Chl-a identified in guts of Pagurus alatus), and they have low gut fullness (probably indicating a capacity to withstand long periods under starvation), that would favour their adaptability to a rather unpredictable habitat such as Le Danois Bank summit. Regarding prey availability, zooplankton/micronekton and infauna distributed around Le Danois Bank showed different depth-related patterns. Among zooplankton, mesopelagic decapods, mysids, and fishes were absent at the bank summit, while euphausiids exhibited high abundances over the summit. No significant trends with depth were found for infauna abundance, and for instance polychaete densities were similar both at the summit and the inner basin. Therefore, prey availability was lower for summit assemblages regarding zooplankton/micronekton. Patterns in mean size vs. depth were species specific for decapods, and the possible role of the bank summit as a recruitment area was not general for the whole decapod assemblage.     

Estimation of transit trip production using Factorial Kriging with External Drift: an aggregated data case study

Studies in transportation planning routinely use data in which location attributes are an important source of information. Thus, using spatial attributes in urban travel forecasting models seems reasonable. The main objective of this paper is to estimate transit trip production using Factorial Kriging with External Drift (FKED) through an aggregated data case study of Traffic Analysis Zones in São Paulo city, Brazil. The method consists of a sequential application of Principal Components Analysis (PCA) and Kriging with External Drift (KED). The traditional Linear Regression (LR) model was adopted with the aim of validating the proposed method. The results show that PCA summarizes and combines 23 socioeconomic variables using 4 components. The first component is introduced in KED, as secondary information, to estimate transit trip production by public transport in geographic coordinates where there is no prior knowledge of the values. Cross-validation for the FKED model presented high values of the correlation coefficient between estimated and observed values. Moreover, low error values were observed. The accuracy of the LR model was similar to FKED. However, the proposed method is able to map the transit trip production in several geographical coordinates of non-sampled values.     

Cotton Fiber/ZrO2, A New Material for Adsorption of Cr(VI) Ions in Water

The natural cotton fiber was used to synthesize an anion exchange, containing ZrO₂ film on its surface, NCFZC (natural cotton fiber/ZrO₂ composite). This anion exchanger was produced by the reaction of the zirconium oxychloride and hydroxyl groups on surface of the natural cotton fiber. The material was used for Cr(VI) ions adsorption studies. Adsorption equilibrium time and optimum pH for Cr(VI) adsorption were found to be 6 h and 4.0, respectively. The Langmuir and Temkin isotherms were used to models adsorption equilibrium data. The adsorption capacity of NCFZC was found to be 1.33 mmol/g. Kinetic studies showed that the rate of adsorption of Cr(VI) on NCFZC obeyed a pseudo‐second‐order kinetic model.     

Storm surge frequency reduction in Venice under climate change

Increased tidal levels and storm surges related to climate change are projected to result in extremely adverse effects on coastal regions. Predictions of such extreme and small-scale events, however, are exceedingly challenging, even for relatively short time horizons. Here we use data from observations, ERA-40 re-analysis, climate scenario simulations, and a simple feature model to find that the frequency of extreme storm surge events affecting Venice is projected to decrease by about 30% by the end of the twenty-first century. In addition, through a trend assessment based on tidal observations we found a reduction in extreme tidal levels. Extrapolating the current +17 cm/century sea level trend, our results suggest that the frequency of extreme tides in Venice might largely remain unaltered under the projected twenty-first century climate simulations.     

Corrections stemming from the non-osculating character of the Andoyer variables used in the description of rotation of the elastic Earth

We explore the evolution of the angular velocity of an elastic Earth model, within the Hamiltonian formalism. The evolution of the rotation state of the Earth is caused by the tidal deformation exerted by the Moon and the Sun. It can be demonstrated that the tidal perturbation to spin depends not only upon the instantaneous orientation of the Earth, but also upon its instantaneous angular velocity. Parameterizing the orientation of the Earth figure axis with the three Euler angles, and introducing the canonical momenta conjugated to these, one can then show that the tidal perturbation depends both upon the angles and the momenta. This circumstance complicates the integration of the rotational motion. Specifically, when the integration is carried out in terms of the canonical Andoyer variables (which are the rotational analogues to the orbital Delaunay variables), one should keep in mind the following subtlety: under the said kind of perturbations, the functional dependence of the angular velocity upon the Andoyer elements differs from the unperturbed dependence (Efroimsky in Proceedings of Journées 2004: Systèmes de référence spatio-temporels. l’Observatoire de Paris, pp 74–81, 2005; Efroimsky and Escapa in Celest. Mech. Dyn. Astron. 98:251–283, 2007). This happens because, under angular velocity dependent perturbations, the requirement for the Andoyer elements to be canonical comes into a contradiction with the requirement for these elements to be osculating, a situation that parallels a similar antinomy in orbital dynamics. Under the said perturbations, the expression for the angular velocity acquires an additional contribution, the so called convective term. Hence, the time variation induced on the angular velocity by the tidal deformation contains two parts. The first one comes from the direct terms, caused by the action of the elastic perturbation on the torque-free expressions of the angular velocity. The second one arises from the convective terms. We compute the variations of the angular velocity through the approach developed in Getino and Ferrándiz (Celest. Mech. Dyn. Astron. 61:117–180, 1995), but considering the contribution of the convective terms. Specifically, we derive analytical formulas that determine the elastic perturbations of the directional angles of the angular velocity with respect to a non-rotating reference system, and also of its Cartesian components relative to the Tisserand reference system of the Earth. The perturbation of the directional angles of the angular velocity turns out to be different from the evolution law found in Kubo (Celest. Mech. Dyn. Astron. 105:261–274, 2009), where it was stated that the evolution of the angular velocity vector mimics that of the figure axis. We investigate comprehensively the source of this discrepancy, concluding that the difference between our results and those obtained in Ibid. stems from an oversimplification made by Kubo when computing the direct terms. Namely, in his computations Kubo disregarded the motion of the tide raising bodies with respect to a non-rotating reference system when compared with the Earth rotational motion. We demonstrate that, from a numerical perspective, the convective part provides the principal contribution to the variation of the directional angles and of length of day. In the case of the x and y components in the Tisserand system, the convective contribution is of the same order of magnitude as the direct one. Finally, we show that the approximation employed in Kubo (Ibid.) leads to significant numerical differences at the level of a hundred micro-arcsecond.