Assessment of WRF numerical model forecasts using different lead time initializations during extreme precipitation events over Macaé city,Rio de Janeiro (Brazil)     

da Silva  Fabricio Polifke  da Silva  Alfredo Silveira  da Silva  Maria Gertrudes Alvarez Justi  Pires  Gisele Dornelles 《Natural Hazards》2022,110(1):695-718

Natural Hazards - The ability to forecast extreme precipitation events has become increasingly important over the last decades due to their significant impacts on society and properties. In this...  相似文献   

The Mineral Adsorption and The Application of a Metamorphic Felsic Rock as Aggregate in Asphalt Pavements     

Lago  Larissa Neves  Casagrande  Michéle Dal Toé  da Conceição Ribeiro  Roberto Carlos  de Albuquerque e Silva  Ben-Hur 《Geotechnical and Geological Engineering》2022,40(3):1585-1595

Geotechnical and Geological Engineering - The aggregates consist approximately 85% of the total volume in asphalts pavements, and their properties influence directly their behavior. Therefore, it...  相似文献   

Development of the Global Earthquake Model’s neotectonic fault database   总被引：2，自引：0，他引：2  

Annemarie Christophersen  Nicola Litchfield  Kelvin Berryman  Richard Thomas  Roberto Basili  Laura Wallace  William Ries  Gavin P. Hayes  Kathleen M. Haller  Toshikazu Yoshioka  Richard D. Koehler  Dan Clark  Monica Wolfson-Schwehr  Margaret S. Boettcher  Pilar Villamor  Nick Horspool  Teraphan Ornthammarath  Ramon Zuñiga  Robert M. Langridge  Mark W. Stirling  Tatiana Goded  Carlos Costa  Robert Yeats 《Natural Hazards》2015,79(1):111-135

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Evaluation of an ensemble of regional climate model simulations over South America driven by the ERA-Interim reanalysis: model performance and uncertainties   总被引：2，自引：1，他引：1  

Silvina A. Solman  E. Sanchez  P. Samuelsson  R. P. da Rocha  L. Li  J. Marengo  N. L. Pessacg  A. R. C. Remedio  S. C. Chou  H. Berbery  H. Le Treut  M. de Castro  D. Jacob 《Climate Dynamics》2013,41(5-6):1139-1157

The capability of a set of 7 coordinated regional climate model simulations performed in the framework of the CLARIS-LPB Project in reproducing the mean climate conditions over the South American continent has been evaluated. The model simulations were forced by the ERA-Interim reanalysis dataset for the period 1990–2008 on a grid resolution of 50 km, following the CORDEX protocol. The analysis was focused on evaluating the reliability of simulating mean precipitation and surface air temperature, which are the variables most commonly used for impact studies. Both the common features and the differences among individual models have been evaluated and compared against several observational datasets. In this study the ensemble bias and the degree of agreement among individual models have been quantified. The evaluation was focused on the seasonal means, the area-averaged annual cycles and the frequency distributions of monthly means over target sub-regions. Results show that the Regional Climate Model ensemble reproduces adequately well these features, with biases mostly within ±2 °C and ±20 % for temperature and precipitation, respectively. However, the multi-model ensemble depicts larger biases and larger uncertainty (as defined by the standard deviation of the models) over tropical regions compared with subtropical regions. Though some systematic biases were detected particularly over the La Plata Basin region, such as underestimation of rainfall during winter months and overestimation of temperature during summer months, every model shares a similar behavior and, consequently, the uncertainty in simulating current climate conditions is low. Every model is able to capture the variety in the shape of the frequency distribution for both temperature and precipitation along the South American continent. Differences among individual models and observations revealed the nature of individual model biases, showing either a shift in the distribution or an overestimation or underestimation of the range of variability.  相似文献   

Moisture source for the Amazon Basin: a study of contrasting years     

Prakki Satyamurty  Claudia Priscila Wanzeler da Costa  Antonio Ocimar Manzi 《Theoretical and Applied Climatology》2013,111(1-2):195-209

The regions where the divergence of vertically integrated water vapor flux, averaged over a season or a year, is positive (negative) are sources (sinks) of moisture for the atmosphere. An aerial river is defined as a stream of strong water vapor flux connecting a source and a sink. Moisture flux, its divergence, and sources and sinks over the tropics of South and Central America and the adjoining Atlantic Ocean are obtained for dry years and for wet years in the Amazon Basin. Results show that the Amazon Basin is a sink region for atmospheric moisture in all seasons and that there are two source regions for the moisture in the basin, one situated in the South Atlantic and the other in the North Atlantic, both located equator-ward of the respective subtropical high-pressure centers. The convergence of moisture increases over the Amazon Basin in austral summer, and at the same time it decreases in the Pacific and Atlantic ITCZs. Box model calculations reveal that the wet years, on the average, present about 55 % more moisture convergence than the dry years in the Amazon Basin. A reduction in the moisture inflow across the eastern and northern boundaries of the basin (at 45°W and at the Equator, respectively) and an increase in the outflow across the southern boundary (at 15°S) lead to dry conditions. The annual mean contribution of moisture convergence to the precipitation over the Amazon Basin is estimated to be 70 %. In the dry years, it lowers to around 50 %. The net convergence of water vapor flux over the basin is a good indicator of the wet or dry condition.  相似文献   

THz photometers for solar flare observations from space     

Pierre Kaufmann  Rogério Marcon  André Abrantes  Emilio C. Bortolucci  Luis Olavo T. Fernandes  Grigory I. Kropotov  Amauri S. Kudaka  Nelson Machado  Adolfo Marun  Valery Nikolaev  Alexandre Silva  Claudemir S. da Silva  Alexander Timofeevsky 《Experimental Astronomy》2014,37(3):579-598

The search for the still unrevealed spectral shape of the mysterious THz solar flare emissions is one of the current most challenging research issues. The concept, fabrication and performance of a double THz photometer system, named SOLAR-T, is presented. Its innovative optical setup allows observations of the full solar disk and the detection of small burst transients at the same time. The detecting system was constructed to observe solar flare THz emissions on board of stratospheric balloons. The system has been integrated to data acquisition and telemetry modules for this application. SOLAR-T uses two Golay cell detectors preceded by low-pass filters made of rough surface primary mirrors and membranes, 3 and 7 THz band-pass filters, and choppers. Its photometers can detect small solar bursts (tens of solar flux units) with sub second time resolution. Tests have been conducted to confirm the entire system performance, on ambient and low pressure and temperature conditions. An artificial Sun setup was developed to simulate performance on actual observations. The experiment is planned to be on board of two long-duration stratospheric balloon flights over Antarctica and Russia in 2014–2016.  相似文献   

Discovery of the 'missing' mode in HR 1217 by the Whole Earth Telescope     

D. W.Kurtz  S. D.Kawaler  R. L.Riddle  M. D.Reed †  M. S.Cunha  M.Wood  N.Silvestri  T. K.Watson  N.Dolez  P.Moskalik  S.Zola  E.Pallier  J. A.Guzik  T. S.Metcalfe  A. S.Mukadam  R. E.Nather  D. E.Winget  D. J.Sullivan  T.Sullivan  K.Sekiguchi  X.Jiang  R.Shobbrook  B. N.Ashoka  S.Seetha  S.Joshi  D.O'Donoghue  G.Handler  M.Mueller  J. M.Gonzalez Perez  J.-E.Solheim  F.Johannessen  A.Ulla  S. O.Kepler  A.Kanaan  A.da Costa  L.Fraga  O.Giovannini  J. M.Matthews 《Monthly notices of the Royal Astronomical Society》2002,330(3):57-61

HR 1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 and 34.6 μHz, with a sixth mode at a problematic spacing of 50.0 μHz (which equals  1.5×33.3 μHz)  to the high-frequency side. Asymptotic pulsation theory allowed for a frequency spacing of 34 μHz, but Hipparcos observations rule out such a spacing. Theoretical calculations of magnetoacoustic modes in Ap stars by Cunha predicted that there should be a previously undetected mode 34 μHz higher than the main group, with a smaller spacing between it and the highest one. In this Letter, we present preliminary results from a multisite photometric campaign on the rapidly oscillating Ap star HR 1217 using the 'Whole Earth Telescope'. While a complete analysis of the data will appear in a later paper, one outstanding result from this run is the discovery of a newly detected frequency in the pulsation spectrum of this star, at the frequency predicted by Cunha.  相似文献   

First Results from SWAN Lyman α solar wind mapper on SOHO     

J. L. Bertaux  E. Quémerais  R. Lallement  E. Kyrölä  W. Schmidt  T. Summanen  J. P. Goutail  M. Berthé  J. Costa  T. Holzer 《Solar physics》1997,175(2):737-770

After one year of almost flawless operation on board the SOHO spacecraft poised at L1 Lagrange point, we report the main features of SWAN observations. SWAN is mainly dedicated to the monitoring of the latitude distribution of the solar wind by the Lα method. Maps of sky Lα emissions were recorded througout the year. The region of maximum emission, located in the upwind hemisphere, deviates strongly from the pattern that could be expected from a solar wind constant with latitude. It is divided into two lobes by a depression aligned with the solar equatorial plane called the Lyα groove already noted in 1976 Prognoz data. The north lobe is much brighter than the south lobe. These two characteristics can be explained qualitatively by an enhanced ionization along the neutral sheet where the slow solar wind is concentrated, which results from the higher low-latitude solar wind mass flux as measured by Ulysses. The groove is the direct imprint on the sky of the enhanced carving by the slow solar wind, at this time of solar minimum, when the tilt angle of the neutral sheet is small. The question is still pending to predict what will happen with the ascending phase of the solar cycle. Observations of comets are briefly mentioned, with the ability of SWAN to monitor the H₂O production of many comets. Operations of the instrument are briefly described, including some instrumental problems which could be solved by software modifications sent to the instrument. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1004979605559  相似文献   

Groundwater behaviour in Madeira, volcanic island (Portugal)     

Susana Nascimento Prada  Manuel Oliveira da Silva  José Virgílio Cruz 《Hydrogeology Journal》2005,13(5-6):800-812

Madeira Island is a hot-spot originating from a mantle plume. K-Ar age determinations indicate that the emerged part of the island was generated during Post-Miocene times 6000–7000 years B.P. Groundwater occurs in perched-water bodies, spring discharge from them is high, about 3,650 l/s; in dike-impounded water and basal groundwater. Basal groundwater is exploited by tunnels (1,100 l/s) and wells (1,100 l/s). Hydraulic gradients range from 10^–4 to 10^–2 and transmissivity ranges from 1.16×10^–2 to 2.89×10^–1 m²/s, indicating the heterogeneity of the volcanic aquifers. Water mineralisation is variable, and electrical conductivity ranges from 50 to 3,300 S/cm. There is a difference between groundwater discharging from perched-water bodies (43–201 S/cm) and from basal groundwater (109–3,300 S/cm). Groundwater average pH is 7.37, with waters acid to slightly alkaline (6.13–8.4), and generally cold. Nevertheless, a few samples associated with fault zones can be classified as thermal waters.

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Resumen La Isla de Madeira tuvo origen en un punto caliente proveniente de una pluma del manto. Las dataciones K – Ar, indican que la parte emergida de la isla se formó durante en Post—Mioceno, hace unos 6000–7000 años. El agua subterránea se encuentra en acuíferos colgados, cuya descarga a través de manantiales es alta, alrededor de 3650 l/s; también como agua retenida en diques o bien como agua subterránea propiamente dicha. Esta última es explotada por túneles (1100 l/s) y pozos (1100 l/s). Los gradientes hidráulicos varían desde 10–4 hasta 10–2 y la transmisividad varía desde 1.16×10^–2 hasta 2.89×10^–1 m²/s, indicando la heterogeneidad de los acuíferos volcánicos. La mineralización de agua es variable y la conductividad eléctrica varía desde 50 mS/cm hasta 3300 mS/cm. Hay una diferencia entre el agua subterránea proveniente de acuíferos colgados (43–201 mS/cm) y aquella del acuífero principal (109–3300 mS/cm). El pH promedio para el agua subterránea es 7.37; con variación desde ácida hasta ligeramente alcalina (6.13–8.4), y es generalmente fría. Sin embargo unos pocos ejemplos asociados con zonas de falla, pueden ser clasificados como agua termal.

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Résumé Lîle de Madeira est un point chaud, provenant dun panache mantélique. Les datations par la méthode de K-Ar indiquent que la part émergée de lîle a été générée pendant le Post Miocène, il y a 6000–7000 ans. Les eaux souterraines sont cantonnées dans des aquifères perchées qui se déchargent par des sources à grands débits, avec des valeurs dapproximativement de 3500 l/s, ainsi que dans les dikes. Une importante quantité des eaux souterraine se trouve sur la forme deau de fonds, formant une nappe basale, qui est exploitée par des tunnels (1100 l/s) et par des puits (1100 l/s). Les gradients hydrauliques ont des valeurs dans lintervalle de 10^–2 à 10^–4, tandis que les transmissivités se rangent entre 1.16×10^–2 m²/s et 2.81×10^–1 m²/s, ce quindique la hétérogénéité de laquifère volcanique. La minéralisation des eaux est aussi variable avec des conductivités électriques qui se rangent ente 50 mS/cm et 3300 mS/cm. Il y a une différence entre la conductivité des eaux provenant des aquifères perchées (30–201 mS/cm) par rapport à la conductivité les eaux de la nappe basale (109–3300 mS/cm). Le pH moyen est de 7.37 avec des valeurs de 6.13 pour les eaux acides et de 8.4 pour les eaux à faible alcalinité. En général il sagit des eaux froides, mais quelques échantillons provenant des zones faillées peuvent être classifiés comme des eaux thermales.

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Seismic hazard analysis in zones of time and space interdependence: An application to S?o Miguel Island, Azores     

C. S. Oliveira  A. C. Costa  V. H. Forjaz  J. C. Nunes 《Natural Hazards》1984,3(1):15-29

The Azores Islands are located in the mid-Atlantic region near the triple junction where the Euro-Asiatic-African-American plates join together. Seismic activity in the area is very high, as can be observed either from historical events since the fifteenth century, from present day microseismicity, and from direct and indirect measurements of recent tectonic deformation. Volcanic activity is also present throughout the region.All available information, even data exhibiting low quality, was used to develop hazard models of São Miguel Island. Source zones were established based on both the global tectonic behaviour of the region and on the local active fault structures. Recurrence laws for São Miguel Island, for which historical information seemed quite incomplete, were obtained from the large events in the entire archipelago and from their remarkable pattern of time and space dependence, and complimented by information on long-term fault deformation (for the longer recurrence periods) and on high precision instrumental network (for the very short recurrence periods).Attenuation laws were derived from data on events felt and/or recorded in the Island.Hazard maps were obtained through a modified version of McGuire's algorithm for several geometries of source areas and results compared with the maximum observed intensity of historical events.Abstract presented at the 21st General Assembly of the European Seismological Commission held in Sofia, 1988.  相似文献