Imaging the recent sediment dynamics of the Galicia Bank region (Atlantic,NW Iberian Peninsula)

Multibeam bathymetry, high resolution multi-channel, and very high resolution single-channel (3.5 kHz) seismic records were used to depict the complex geomorphology that defines the Galicia Bank region (Atlantic, NW Iberian Peninsula). This region (≈620–5,000 m water depth) is characterized by a great variety of features: structural features (scarps, highs, valleys, fold bulges), fluid dynamics-related features (structural undulations and collapse craters), mass-movement features (gullies, channels, mass-flow deposits, slope-lobe complexes, and mass-transport deposits), bottom-current features (moats, furrows, abraded surface, sediment waves, and drifts), (hemi)pelagic features, mixed features (abraded surfaces associated to mixed sediments) and bioconstructions. These features represent architectural elements of four sedimentary systems: slope apron, contouritic, current-controlled (hemi)pelagic, and (hemi)pelagic. These systems are a reflection of different sedimentary processes: downslope (mass transport, mass flows, turbidity flows), alongslope (bottom currents of Mediterranean Outflow Water, Labrador Sea Water, North Atlantic Deep Water, and Lower Deep Water), vertical settling, and the interplay between them. The architectural and sediment dynamic complexities, for their part, are conditioned by the morphostructural complexity of the region, whose structures (exposed scarps and highs) favor multiple submarine sediment sources, affect the type and evolution of the mass-movement processes, and interact with different water masses. This region and similar sedimentary environments far from the continental sediment sources, as seamounts, are ideal zones for carrying out submarine source-to-sink studies, and can represent areas subject to hazards, both geologic and oceanographic in origin.     

Downscaling projections of climate change in Sao Tome and Principe Islands,Africa

Sao Tome and Principe is a small insular African country extremely vulnerable to rising sea levels and impacts such as inundation, shore line change, and salt water intrusion into underground aquifers. Projections of climate change have considered coarse model resolutions. The objective of this work is to dynamically downscale the global model projections to 4-km resolution and to assess the climate change in the Sao Tome and Principe islands. The global climate projections are provided by the Canadian Earth System Model under two Representative Concentration Pathways greenhouse gas scenarios, RCP4.5 and RCP8.5. The downscaling is produced by the Eta regional climate model. The baseline period is taken between 1971 and 2000, and the future climate period is taken between 2041 and 2070. The 2-m temperature simulations show good agreement with station data. The model simulates temperature more accurately than precipitation. The precipitation simulations systematically show underestimation and delay of the rainy and the dry seasons by about 1 month, a feature inherited from the global climate model. In the middle of the 21st century, projections show the strongest warming in the elevated parts of the Sao Tome Island, especially in February under RCP8.5. Warmer nights and warmer days become more frequent in the islands when compared with those in the present. While under RCP4.5, precipitation increases in the islands; under RCP8.5, it decreases everywhere in both islands. Heavy precipitation rates should increase, especially in the south-southwestern parts of the Sao Tome islands. Detailed spatial variability of the temperature and precipitation changes in the islands can only be revealed at very high spatial model resolution. Implications for the potential energy production from two major river basins are assessed in this work.     

Surface atmospheric circulation patterns and associated minimum temperatures in the Maipo and Casablanca valleys, central Chile

This paper analyzes the influence of circulation anomalies on the magnitude of minimum air temperature (T _min) at a daily scale in two important agricultural valleys of Chile (Maipo and Casablanca) during the period 2001–2007. A statistical classification of synoptic fields was performed, resulting in eight circulation patterns (CPs, 84 % of explained variance). The corresponding anomalies of T _min (AT_min) of each CP were analyzed in order to understand their synoptic-scale forcing mechanisms. Results showed a direct association between AT_min and the synoptic structure. The average weakening in sea level pressure (SLP) yields positive AT_min, while negative AT_min is associated with a strengthening in SLP. In the latter case, it was also found that a synoptic structure (10.2 % of frequency) corresponding to a migratory high-pressure system passing eastward across the Andes led to the lowest AT_min and a higher probability of frost in both valleys (22 % on average) in winter and springtime.     

The Iguaraçu H5 chondrite: a fall from Paraná State,Brazil

Abstract— The Iguaraçu meteorite, a single stone of 1200 g, fell in Paraná State, Brazil in October 1977. It is classified as an H5 ordinary chondrite with olivine of composition Fa 18.7.     

Mineralogical characterization of some basaltic asteroids in the neighborhood of (4) Vesta: first results

We present reflectance spectra of 19 V-type asteroids obtained at the 3.6 m Telescopio Nazionale Galileo covering 0.8 to 2.5 μm. For 8 of these asteroids we obtained also visible spectra in the same observational run. The range from 0.8 to 2.5 μm, encompassing the 1 and 2 μm pyroxene features, allows a precise mineralogical characterization of these asteroids. The obtained data suggests the possible coexistence of distinct mineralogical groups among the V-type asteroids, either probing different layers of (4) Vesta or coming from different bodies. No clear correlation was found between mineralogies and the objects being, or not, member of the Vesta dynamical family.     

Stochastic Modeling of the Residual Acceleration Field in a Microgravity Environment

We discuss fluid flows induced by thehigh-frequency components of the residual acceleration field onboard spacecraft (g-jitter) on representative experimental configurations.We study the statistics of g-jitter time series data from theNASA SL-J mission (SAMS-258), and discuss a recently introducedstochastic model of g-jitter. The examples studied are chosen to highlightintrinsically stochastic effects of g-jitter. They include free surfaceresonances, cavity flow, and inertial Brownian motion in suspensions. Thelatter is relevant for coarsening experiments in solid-liquid mixtures.     

Site evaluation and RFI spectrum measurements in Portugal at the frequency range 0.408–10 GHz for a GEM polarized galactic radio emission experiment

We probed for radio frequency interference (RFI) at three potential galactic emission mapping experiment (GEM) sites in Portugal using custom made omnidirectional disconic antennas and directional pyramidal horn antennas. For the installation of a 10-m dish dedicated to the mapping of polarized galactic emission foreground planned for 2005–2007 in the 5–10 GHz band, the three sites chosen as suitable to host the antenna were surveyed for local radio pollution in the frequency range 0.01–10 GHz. Tests were done to look for radio broadcasting and mobile phone emission lines in the radio spectrum. The results show one of the sites to be almost entirely RFI clean and showing good conditions to host the experiment.     

High-performance computing strategies for seismic-imaging software on the cluster and cloud-computing environments

Modern subsurface imaging techniques allow obtaining high-quality images but with high computational costs. Nonetheless, depending on the amount of data, their execution is limited by memory in the current generation's hardware. However, with the advancement of new hardware and cloud-based solutions, these problems are mitigated but still with the risk of work loss and instability. To mitigate the execution problems in memory-limited and fail-prone environments, we propose two high-performance computing techniques. The first is based on independent checkpointing alongside a fault-tolerant framework to store an execution state and recover from that state in case of failures. Besides, for memory-limited graphics processing units, we present a technique to reduce the amount of memory requirement that we call the hybrid strategy. The experiments showed that the independent checkpointing alongside the fault-tolerant framework is able to mitigate the performance penalty of node failures, with the independent checkpointing technique being more relevant when multiple nodes are terminated. Furthermore, the hybrid strategy technique has shown the possibility of execution of larger models that could make the graphics processing unit run out of memory otherwise. Finally, our implementation is scalable, allowing a significant improvement in performance when adding new nodes. In conclusion, our techniques can be used to deliver fast, high-fidelity subsurface imaging in unstable and memory-limited environments, such as the cloud.