Comparison of lacustrine successions and their palaeohydrological implications in two sub‐basins of the Triassic Cuyana rift,Argentina          下载免费PDF全文

Cecilia Benavente  Adriana Mancuso  Nora Cabaleri  Elizabeth Gierlowski‐Kordesch 《Sedimentology》2015,62(7):1771-1813

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POlarization Emission of Millimeter Activity at the Sun (POEMAS): New Circular Polarization Solar Telescopes at Two Millimeter Wavelength Ranges     

Adriana Valio  P. Kaufmann  C. G. Giménez de Castro  J.-P. Raulin  L. O. T. Fernandes  A. Marun 《Solar physics》2013,283(2):651-665

We present a new system of two circular polarization solar radio telescopes, POEMAS, for observations of the Sun at 45 and 90 GHz. The novel characteristic of these instruments is the capability to measure circular right- and left-hand polarizations at these high frequencies. The two frequencies were chosen so as to bridge the gap at radio frequencies between 20 and 200 GHz of solar flare spectra. The telescopes, installed at CASLEO Observatory (Argentina), observe the full disk of the Sun with a half power beam width of 1.4^°, a time resolution of 10 ms at both frequencies, a sensitivity of 2?–?4 K that corresponds to 4 and 20 solar flux unit (=10⁴ Jy), considering aperture efficiencies of 50±5 % and 75±8 % at 45 and 90 GHz, respectively. The telescope system saw first light in November 2011 and is satisfactorily operating daily since then. A few flares were observed and are presented here. The millimeter spectra of some flares are seen to rise toward higher frequencies, indicating the presence of a new spectral component distinct from the microwave one.  相似文献   

Assessment of vulnerability for rockfalls in Cozia Gorge (Southern Carpathians,Romania)     

Ovreiu  Adriana Bianca  Bărsoianu  Iulian Andrei  Nistor  Constantin  Nedelea  Alexandru  Comănescu  Laura 《Natural Hazards》2019,99(1):117-140

Natural Hazards - Rockfalls represents a sudden, extremely important geomorphological hazard and may become a threat for people’s life, as well as goods and transport. The present study aims...  相似文献   

Evaluation of community leaders’ perception regarding Alerta Rio,the warning system for landslides caused by heavy rains in Rio de Janeiro     

Patricia de Oliveira Melo  Renata Marques de Britto  Tharcisio Cotta Fontainha  Adriana Leiras  Renata Albergaria de Mello Bandeira 《Natural Hazards》2017,89(3):1343-1368

Warning systems help reduce damage and save lives in disasters; however, there is a lack of research analyzing the population perception of these systems. In Rio de Janeiro (Brazil), because the city slums face the risk of landslides caused by heavy rains, a siren early warning system named “Alerta Rio” was installed in 102 areas. The purpose of this paper was to understand the perception of community leaders regarding this alert system. To this end, a survey was conducted with community leaders to collect data on whether and why the public do or do not attend to the alert. Results indicated that (1) public adherence to Alerta Rio is low despite the generally positive view of the system, (2) local violence was reported as the reason for staying at home to protect one’s property, and (3) problems with temporary shelters and the routes to them result in lack of people’s involvement in the system. Whereas these factors are similar to population perception regarding other warning systems, the community leaders also raised the public’s lack of trust in the city hall’s adopted concept of risk and in the politicians as a relevant factor in the population perception of Alerta Rio. These factors, together with the lack of prevention policies complementary with the alert system, led to perception of reduced importance of the system. For potential solutions to enhance alarm compliance, this study recommends improvement in communication, educational programs, and public engagement strategies tailored for each target group.  相似文献   

Directional interpolation of multicomponent data          下载免费PDF全文

Fredrik Andersson  Adriana Citlali Ramírez  Torgeir Wiik  Viktor V. Nikitin 《Geophysical Prospecting》2017,65(5):1246-1263

A method for interpolation of multicomponent streamer data based on using the local directionality structure is presented. The derivative components are used to estimate a vector field that locally describes the direction with the least variability. Given this vector field, the interpolation can be phrased in terms of the solution of a partial differential equation that describes how energy is transported between regions of missing data. The approach can be efficiently implemented using readily available routines for computer graphics. The method is robust to noise in the measurements and particularly towards high levels of low‐frequent noise that is present in the derivative components of the multicomponent streamer data.  相似文献   

HAND contour: a new proxy predictor of inundation extent          下载免费PDF全文

Antonio Donato Nobre  Luz Adriana Cuartas  Marcos Rodrigo Momo  Dirceu Luís Severo  Adilson Pinheiro  Carlos Afonso Nobre 《水文研究》2016,30(2):320-333

Tools for accurately predicting environmental risks, such as the location and spatial extent of potential inundation, are not widely available. A dependence on calibration and a lack of available flood data have prevented the widespread application of existing hydrodynamic methods for predicting the extent of inundation. We use the height above the nearest drainage (HAND) terrain model to develop a simple static approach for mapping the potential extent of inundation that does not depend on flood observations and extends beyond methods for mapping low‐lying areas. While relying on the contour concept, the method utilizes drainage‐normalized topography and flowpaths to delineate the relative vertical distances (drop) to the nearest river. The HAND‐delineated relative drop is an effective distributed predictor of flood potential, which is directly related to the river stage height. We validated the new HAND contour approach using a flood event in Southern Brazil for which high‐resolution maps were available. The results indicated that the flood hazard‐mapping method accurately predicted the inundation extent of the channel carrying the flood wave and the channels influenced by flooding. For channels positioned outside of the flood‐wave area, the method overestimated the actual flood extent. As an original static assessment of floodwaters across the landscape, the HAND contour method could be used to map flood hazards in areas with poor information and could promote the development of new methods for predicting hydrological hazards. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Solar Radius at Subterahertz Frequencies and Its Relation to Solar Activity     

Fabian Menezes  Adriana Valio 《Solar physics》2017,292(12):195

The Sun emits radiation at several wavelengths of the electromagnetic spectrum. In the optical band, the solar radius is 695?700 km, and this defines the photosphere, which is the visible surface of the Sun. However, as the altitude increases, the electromagnetic radiation is produced at other frequencies, causing the solar radius to change as a function of wavelength. These measurements enable a better understanding of the solar atmosphere, and the radius dependence on the solar cycle is a good indicator of the changes that occur in the atmospheric structure. We measure the solar radius at the subterahertz frequencies of 0.212 and 0.405 THz, which is the altitude at which these emissions are primarily generated, and also analyze the radius variation over the 11-year solar activity cycle. For this, we used radio maps of the solar disk for the period between 1999 and 2017, reconstructed from daily scans made by the Solar Submillimeter-wave Telescope (SST), installed at El Leoncito Astronomical Complex (CASLEO) in the Argentinean Andes. Our measurements yield radii of \(966.5'' \pm2.8''\) for 0.2 THz and \(966.5'' \pm2.7''\) for 0.4 THz. This implies a height of \(5.0 \pm2.0 \times10^{6}\) m above the photosphere. Furthermore, we also observed a strong anticorrelation between the radius variation and the solar activity at both frequencies.  相似文献   

Multi‐kilometre long pathway of geofluids migration: Clues concerning an ophiolite serpentinization setting possibly responsible for the inferred abiotic provenance of methane in thermal water outflows of the South‐West Carpathians (Romania)     

Horia Mitrofan  Constantin Marin  Florina Chitea  Nicoleta Cadicheanu  Ioan Povar&#x;  Alin Tudorache  Daniela Elena Ioni&#x;&#x;  Mirela‐Adriana Anghelache 《地学学报》2021,33(1):56-73

Methane occurrences displaying signatures of a possible abiotic origin had previously been reported in the South‐West Carpathians (Romania). Such an accumulation, at Tisovi?a, was intercepted by a well drilled in an ophiolitic rocks massif, whereas in two other localities—situated tens of kilometres faraway—the concerned methane is released via thermal groundwater outflows that are apparently not associated with any ultramafic products. By using groundwater ionic compositions, corroborated with previously published isotopic (¹³C‐CH₄, ²H‐CH₄, ³He/⁴He) and molecular gas analyses, we assessed in more detail the conjectured abiotic provenance of methane, and quantitatively investigated the hypothesis of a progressive mixing between two, abiotic and thermogenic, methane end‐members. The corresponding geofluids behaviour was modelled by hypothesizing a “concealed” ophiolite serpentinization setting (largely similar to that at Tisovi?a), whose abiotic methane production was “diverted” towards remote discharges at ground surface, via a ~20‐km‐long flowpath supposedly generated by recently operating extensional tectonics.  相似文献   

A multidisciplinary study of the Cape Peloro brackish area (Messina, Italy): characterisation of trophic conditions, microbial abundances and activities     

Marcella Leonardi  Filippo Azzaro  Maurizio Azzaro  Gabriella Caruso  Monique Mancuso  Luis Salvador Monticelli  Giovana Maimone  Rosabruna La Ferla  Francesco Raffa  & Renata Zaccone 《Marine Ecology》2009,30(S1):33-42

In the framework of the VECTOR DIVCOST Project, a 2-year investigation was started in 2006, with the aim of testing the sensibility of microbial parameters to environmental changes and of assessing whether they can provide information about functional changes in the carbon cycle. The investigation was performed in the surface waters of two small brackish ponds (Ganzirri and Faro), located in the Cape Peloro transitional area (Sicily, Italy). The seasonal changes in both the microbial compartment [bacterioplankton, vibrios, exoenzymatic hydrolysis of proteins and polysaccharides, bacterial secondary production (HBP) and community respiration] and the trophic state of suspended matter [total suspended matter (TSM), particulate organic carbon (POC), particulate organic nitrogen (PON), C/N] were analysed in relation to the hydrological characteristics [temperature, salinity, oxygen, fluorescence, NH₄, NO₂, NO₃, PO₄]. Despite marked differences in the nutritional input and the diversification in both carbon budget and trophic level, the two ponds show similar trends in many of the investigated factors, hardly influenced by seasonal variations. Temporally coupled trends were observed for some parameters (enzyme activities, vibrios abundances, respiratory activity), whereas others (POC, PON, heterotrophic bacterial production, bacterioplankton) showed a seasonal shift between the two lakes. The different behaviour found for the some biotic parameters suggests that their response to environmental conditions may be modulated differently between the two lakes, which, despite their spatial proximity and reciprocal connection, do not always show contemporaneous functional processes.  相似文献   

Multiscale Variability of Twenty-Two Coastal Phytoplankton Time Series: a Global Scale Comparison     

Adriana Zingone  Edward J. Phlips  Paul J. Harrison 《Estuaries and Coasts》2010,33(2):224-229

We provide an introduction and a foreword to the Special Issue “Phytoplankton Time Series in Estuaries and Coastal Ecosystems”. This issue includes long-term investigations (10–40 years) of 22 coastal ecosystems and a comparative analysis of chlorophyll a from 84 time series. The results and conclusions provided by these studies help to illuminate the disparities and similarities in long-term phytoplankton dynamics among a wide range of coastal systems and provide insight into the major driving factors responsible for short- and long-term trends in phytoplankton communities.  相似文献