Very high-frequency radar mapping of surface currents

An ocean surface current radar (OSCR) in the very high frequency (VHF) mode was deployed in South Florida Ocean Measurement Center (SFOMC) during the summer of 1999. During this period, a 29-d continuous time series of vector surface currents was acquired starting on 9 July 1999 and ending 7 August 1999. Over a 20-min sample interval, the VHF radar mapped coastal ocean currents over a 7.5 km × 8 km domain with a horizontal resolution of 250 m at 700 grid points. A total of 2078 snapshots of the two-dimensional current vectors were acquired during this time series and of these samples, only 69 samples (3.3%) were missing from the time series. During this period, complex surface circulation patterns were observed that included coherent, submesoscale vortices with diameters of 2 to 3 km inshore of the Florida Current. Comparisons to subsurface measurements from moored and ship-board acoustic Doppler current profiles revealed regression slopes of close to unity with biases ranging from 4 to 8 cm s^-1 between surface and subsurface measurements at 3 to 4 m beneath the surface. Correlation coefficients were 0.8 or above with phases of - 10 to - 20° suggestive of an anticyclonic veering of current with depth relative to the surface current. The radar-derived surface current field provided spatial context for an observational network using mooring-, ship- and autonomous underwater vehicle-sensor packages that were deployed at the SFOMC     

Rock Glaciers in the Patagonian Andes: An Inventory for the Monte San Lorenzo (Cerro Cochrane) Massif, 47° S

Although rock glaciers in the Central and Desert Andes of Argentina and Chile have been previously studied in detail, much less attention has been paid to the occurrence of these permafrost forms in Patagonia. Recently, however, the establishment of the Argentinean Glacier Inventory program, which intends to inventory and monitor all ice masses along the Argentinean Andes, has started a large amount of new geocryological research. The project is designed to provide reliable and worldwide comparable results, supported by well established technical procedures and background information. Presented here is the first rock glacier inventory of the Monte San Lorenzo (Cerro Cochrane) region in the southern Patagonian Andes. A total of 130 intact (9.86 km²) and 47 fossil (1.45 km²) landforms were inventoried using two 2.5 m resolution ALOS Panchromatic Remote‐sensing Instruments for Stereo Mapping images. Since the Argentinean federal initiative described above legally protects all rock glaciers in the country as water reserves, and due to the little scientific knowledge concerning rock glaciers in the vast majority of the Patagonian Andes, this inventory provides an important basis for political decision‐making and opens further geocryological research avenues for the Patagonian region in general.     

Late Holocene palaeoenvironments of the Nutria Mansa 1 archaeological site,Argentina

This paper presents results of interdisciplinary palaeoenvironmental research carried out on a sediment sequence from the Nutria Mansa 1 archaeological site. This late Holocene site is located in the Pampean plains, Argentina. Siliceous microfossils were recorded (i.e. phytoliths, diatoms, chrysophytes, sponges) and micro-charcoal was analyzed. In addition, fauna identified at the site were correlated with regional palaeoclimatic evidence. Based on the microfossil associations, we concluded that the human occupations occurred beside a fluvial and brackish-freshwater lacustrine setting. Grass communities were located on its margins that developed under a warm temperate climate with evidence for dryness and marked seasonality in part of the record. Although some stratigraphic and faunal evidence indicates a possible temperature increase, these fluctuations were not sufficient to extirpate mammals of arid and cold environments.     

A unified framework for earthquake risk assessment of transportation networks and gross regional product

Natural threats like earthquakes, hurricanes or tsunamis have had serious impacts on communities. In the past, major earthquakes in the United States like Loma Prieta 1989, Northridge 1994, or recent events in Italy like L’Aquila 2009 or Emilia 2012 emphasized the importance of preparedness and awareness to reduce social impacts. In addition to that, earthquake damaged businesses dramatically reduced the gross regional product. Generating scenario earthquakes in a proper way is important to suitably assess the risk in bridge networks and social losses in terms of gross regional product reduction. Seismic hazard is traditionally assessed by means of probabilistic seismic hazard analysis (PSHA). Although PSHA well represents the hazard at a specific location it is not suitable for spatially distributed systems. Scenario earthquakes can overcome this problem; they represent the actual distribution of ground shaking for a spatially distributed system while being hazard consistent. In this work a methodology to generate scenario earthquakes has been proposed using a novel approach with the aim of being the basic step for investigating possible earthquake consequences in seismic areas and contributing to reduce losses.     

Rangeland hydrology and erosion model (RHEM) enhancements for applications on disturbed rangelands

The rangeland hydrology and erosion model (RHEM) is a new process‐based model developed by the USDA Agricultural Research Service. RHEM was initially developed for functionally intact rangelands where concentrated flow erosion is minimal and most soil loss occurs by rain splash and sheet flow erosion processes. Disturbance such as fire or woody plant encroachment can amplify overland flow erosion by increasing the likelihood of concentrated flow formation. In this study, we enhanced RHEM applications on disturbed rangelands by using a new approach for the prediction and parameterization of concentrated flow erosion. The new approach was conceptualized based on observations and results of experimental studies on rangelands disturbed by fire and/or by tree encroachment. The sediment detachment rate for concentrated flow was calculated using soil erodibility and hydraulic (flow width and stream power) parameters. Concentrated flow width was calculated based on flow discharge and slope using an equation developed specifically for disturbed rangelands. Soil detachment was assumed to begin with concentrated flow initiation. A dynamic erodibility concept was applied where concentrated flow erodibility was set to decrease exponentially during a run‐off event because of declining sediment availability. Erodibility was estimated using an empirical parameterization equation as a function of vegetation cover and surface soil texture. A dynamic partial differential sediment continuity equation was used to model the total detachment rate of concentrated flow and rain splash and sheet flow. The enhanced version of the model was evaluated against rainfall simulation data for three different sites that exhibit some degree of disturbance by fire and/or by tree encroachment. The coefficient of determination (R²) and Nash–Sutcliffe efficiency were 0.78 and 0.71, respectively, which indicates the capability of the model using the new approach for predicting soil loss on disturbed rangeland. By using the new concentrated flow modelling approach, the model was enhanced to be a practical tool that utilizes readily available vegetation and soil data for quantifying erosion and assessing erosion risk following rangeland disturbance. Copyright © 2014 John Wiley & Sons, Ltd.     

Predation on the southwestern Atlantic fiddler crab (Uca uruguayensis) by migratory shorebirds (pluvialis dominica, P. squatarola, arenaria interpres, and numenius phaeopus)

In Bahia Samborombon (SW Atlantic; 35°30′–36°22′S; 56°45′–57°23′W) migratory American golden plover (Pluvialis dominica), black-billed plover (P. squatarola), ruddy turnstone (Arenaria interpres), and whimbrel (Numenius phaeopus) forage on fiddler crabs (Uca uruguayensis). These shorebirds have distinct patterns of feeding behavior and capture different proportions of each sex and size. P. dominica made short runs, capturing mostly juvenile crabs, which are eaten whole. P. squatarola use a similar feeding strategy but capture females primarily. A. interpres walks continuously, capturing almost exclusively large male crabs (71%). N. phaeopus walk in the Uca patch and probe burrows by inserting the bill; they primarily capture females. The feeding rate of A. interpres is higher than that of P. dominica, P. squatarola, and N. phaeopus. Handling time shown by P. dominica and A. interpres was greater than the other two species for all categories of crabs. In all cases, handling time of male crabs was greater than those of either females or juveniles. All the evidences suggest that U. uruguayensis is an important food source for all these species and should be accounted in any conservation endeavor. *** DIRECT SUPPORT *** A01BY085 00006     

Pre‐Variscan metagabbro from NW Sardinia,Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts

Small metagabbro bodies are enclosed in the metasedimentary sequence of NW Sardinia. The metagabbros represent the last magmatic episode before the continent–continent collision that built up the Variscan chain of north Sardinia. The metagabbros are composed of variable proportions of plagioclase and pyroxene igneous relics and metamorphic minerals. Major and trace element data, specifically high TiO₂ and P₂O₅ and low K and Rb contents, as well as light rare‐earth elements, Nb and Ta enrichment, suggest an alkaline affinity for the gabbro and emplacement in a within‐plate tectonic setting. The gabbro was derived from an ocean island alkali basalt‐like asthenospheric mantle source enriched with incompatible elements and uncontaminated by crustal or subducted materials. Non‐modal modelling indicates a 5–7% partial melting of the asthenospheric mantle. Copyright © 2003 John Wiley & Sons, Ltd.