Study of Coherent Structures and Estimation of the Pressure Transport Terms for the Nocturnal Stable Boundary Layer

During the CASES-99 field experiment, three quartz-based microbarographs were installed on the 58-m main tower at the Central Site. These devices measuredabsolute pressure with temperature compensated output at a resolution better than 0.2 Pa and a sampling frequency of 2 s^-1 during the whole campaign. This sampling rate is not adequate to compute turbulent pressure fluxes with the classic averaging method, but the wavelet transform allows flux estimations at a wide range of scales. The resolution of the devices is suitable to study pressure perturbations such as internal gravity waves. The night period of the Intensive Operational Period number 6 (IOP6), where wave-like structures were present, is chosen to illustrate the method. A complete wavelet analysis of pressure recordsand data from sonic anemometers located at the same heights in the tower is performed. Wavelet methods make it possible to identify the relevant scales in the flowand to study the vertical structure of pressure perturbations, including coherent structures and small-scale motions.A study of a simplified turbulence kinetic energy budget equation is made and the contribution of the pressure terms is discussed.     

Characterisation of a Pleistocene debris-avalanche deposit in the Tenteniguada Basin,Gran Canaria Island,Spain

We studied a large debris-avalanche deposit of Pleistocene age in the Tenteniguada Basin, Gran Canaria Island, Spain. This deposit, which is well preserved because it is mostly covered by basanite lava flows, has distinctive matrix and block facies, hummocky topography and internal structures typical of debris avalanches. However, neither syneruptive lavas nor some characteristic features of volcanic debris-avalanche deposits, such as a stratovolcano edifice or a horseshoe-shaped crater, are present. The occurrence of internal features characteristic of volcanic avalanche deposits could be attributed to the volcanic materials involved in the movement rather than to the triggering of the avalanche during a volcanic eruption. The conditioning factors are shown to be associated with specific structural and hydrological conditions, such as the presence of old volcanic domes, strength reduction of the rocks, effective stress decrease, active gully erosion and water table rise during Pleistocene humid episodes. We finally suggest that the possible triggering factor of the avalanche was a neighbouring volcanic or tectonic earthquake.     

The ARIEL Instrument Control Unit design

In this paper we present the electromagnetic modeling and beam pattern measurements of a 16-elements ultra wideband sparse random test array for the low frequency instrument of the Square Kilometer Array telescope. We discuss the importance of a small array test platform for the development of technologies and techniques towards the final telescope, highlighting the most relevant aspects of its design. We also describe the electromagnetic simulations and modeling work as well as the embedded-element and array pattern measurements using an Unmanned Aerial Vehicle system. The latter are helpful both for the validation of the models and the design as well as for the future instrumental calibration of the telescope thanks to the stable, accurate and strong radio frequency signal transmitted by the UAV. At this stage of the design, these measurements have shown a general agreement between experimental results and numerical data and have revealed the localized effect of un-calibrated cable lengths in the inner side-lobes of the array pattern.     

Seismotectonics of south-west Dominican Republic using recent data

The Dominican Republic has a high level of seismic activity, and a new seismic network has been installed to improve the detection of earthquakes. The network has been operated by Instituto Politécnico Loyola since 2012. It uses six new stations of its own, as well as 17 other stations publically available. In this study, we investigate in particular the south-west of the country where no seismic stations have been operating before. We find an area, SE of the Enriquillo Plantain Garden fault (responsible for the 2010 Haiti M7.0 earthquake), with a high seismic activity (M?=?2–4) compared to the surrounding area. This shallow seismicity (except two events around 40 km depth) is not seen in any global catalogs, and it does not seem to be associated with any known faults. However, the region has been under rapid recent uplift since margins between hills and valleys are filled with massive alluvial fans. We made 24 new fault plane solutions using P-polarities and S/P amplitude ratios. The solutions show mainly reverse mechanisms and the P-axis directions are mainly NNE oriented, which is in agreement with a published strain direction from GPS measurements. We conclude that the main cause of the seismicity in our study area is the push of the Beata Ridge against Enriquillo basin and the rest of the Gonave microplate, reflected in the mainly reverse focal mechanisms.     

Paleomagnetic and paleoclimatic investigation at Laguna Melincue (Pampean Plains,Argentina): preliminary results

Laguna Melincué is a shallow lake located in Santa Fe Province, Argentina (33°41′27.8″S, 61°31′36.5″W). The catchment area is around 1495 km² and it is located in the Pampean Plains. It was reduced to 678 km² by the construction of the San Urbano channel in 1941 and reconditioned in 1977, which was built to avoid floods. The floods are related to some El Niño episodes, with high precipitation events. The lake has been previously studied from different approaches, mainly to understand hydrological and climatic variations, but more multidisciplinary studies are needed to understand its complex hydrological situation. Here we present the first paleomagnetic and rock magnetic studies made on a short sediment core collected from the lake in order to contribute to identifying paleoclimatic proxies and to present the first paleomagnetic results for the site. Rock magnetic analyses suggest that the well-preserved magnetic mineralogy is dominated by pseudo single-domain (titano)magnetite and/or maghemite. The results also indicate that a stable characteristic remanent magnetisation can be isolated and thus the directions of the geomagnetic field may be obtained, providing evidence for the use of this lake for paleomagnetic and paleoenvironmental studies. Changes in magnetic grain size and concentration of magnetic minerals suggest environmental variations and changes in the lake level, which are consistent with historical reports. The paleomagnetic results agree well with Cals3k.3 model for inclination and declination of the geomagnetic field except for the dry period probably due to the fact that the core was extracted near the shore.     

Simulation of the 2004 tsunami of Les Saintes in Guadeloupe (Lesser Antilles) using new source constraints

Natural Hazards - The arc of the Lesser Antilles is associated with a significant tectonic activity due to the subduction of the Atlantic oceanic plate under the Caribbean plate. Earthquakes in...     

Optimum selection of design parameters for transportation of offshore structures

A probabilistic framework is presented to select the design significant wave height and design transverse rotation for typical barges used in the Gulf of Mexico for marine transportation of structural elements and/or systems. The selection of design transverse rotation is based on optimization procedure that trade-off between the performance of the barge subjected to a meteorological-oceanographic (metocean) hazard along the route and losses by structural damage. For this purpose probabilistic models to estimate the metocean hazard for marine transportation are shown. Afterwards, the design rotation is linked to the design of significant wave height and to the return period associated with such wave conditions. The formulation is applied to an offshore transportation route in the Gulf of Mexico.     

Eco‐physiological repercussions of dietary arachidonic acid in cell membranes of active tissues of the Gray whale

The radiation of the mammalian land species that became the baleen whales happened about 27–34 Mya. Mammals require omega 6 fatty acids for reproduction. With this long exposure to the omega 3‐rich marine food chain, the Gray whale (Eschrichtius robustus) might be expected to have lost its requirement for omega 6 fatty acids. We report an unexpectedly high content of omega 6 arachidonic acid (ArA) in the Gray whale liver and muscle lipids. This whale migrates 10,000 km from the cold polar, omega 3 oil‐rich food chain to that of the breeding lagoons of the tropical waters. The food web of tropical waters is a source of omega 6 fatty acids, which are hardly present in the cold polar food web. We suggest the reason for this longest of migrations from cold to warm waters is to meet the requirement for omega 6 fatty acids for mammalian reproduction and brain growth. This extreme conservation of omega 6 fatty acids in Gray whale biology has critical implications for mammalian biology and especially for whale conservation.     

Freezing-resistant liquid water in porous media, a possible mechanism to account for the fluidized transport of sediments on Mars: an example from East Gorgonum crater

ABSTRACT A mudflow-like deposit resting on the bottom of the East Gorgonum Crater (Mars; 37.4°S, 168.0°W) may provide new insight regarding the debate on the existence of water over the Martian surface. Because water in a mudflow is confined to a porous medium, we analyse this case from the perspective of non-equilibrium systems. Fluids confined to porous media behave in a special way, the system being ruled by kinetic restrictions, which alter the expected thermodynamic equilibrium. These non-equilibrium conditions allow the existence of pure liquid water to temperatures as low as − 40 °C, and even less if the system includes brines. Thus, application of the triple point diagram of water on the Martian surface may constitute a simplistic approach if we are dealing with confined, and yet moving, water in the form of a mudflow. We further suggest that the V-shaped channels excavated alongside the mudflow may have been caused by water rejected by syneresis from the moving sediment. We finally indicate that the series of deeply entrenched channels and debris aprons that occur only in the northern half of the crater might be related to the regional slope, which decreases in altitude to the south.