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161.
Richard A. Frazin Alberto M. Vásquez William T. Thompson Russell J. Hewett Philippe Lamy Antoine Llebaria Angelos Vourlidas Joan Burkepile 《Solar physics》2012,280(1):273-293
In order to assess the reliability and consistency of white-light coronagraph measurements, we report on quantitative comparisons between polarized brightness [pB] and total brightness [B] images taken by the following white-light coronagraphs: LASCO-C2 on SOHO, SECCHI-COR1 and -COR2 on STEREO, and the ground-based MLSO-Mk4. The data for this comparison were taken on 16?April 2007, when both STEREO spacecraft were within 3.1° of Earth??s heliographic longitude, affording essentially the same view of the Sun for all of the instruments. Due to the difficulties of estimating stray-light backgrounds in COR1 and COR2, only Mk4 and C2 produce reliable coronal-hole values (but not at overlapping heights), and these cannot be validated without rocket flights or ground-based eclipse measurements. Generally, the agreement between all of the instruments?? pB values is within the uncertainties in bright streamer structures, implying that measurements of bright CMEs also should be trustworthy. Dominant sources of uncertainty and stray light are discussed, as is the design of future coronagraphs from the perspective of the experiences with these instruments. 相似文献
162.
Josep M. Trigo-Rodriguez José M. Madiedo Peter S. Gural Alberto J. Castro-Tirado Jordi Llorca Juan Fabregat Standa Vítek Pep Pujols 《Earth, Moon, and Planets》2008,102(1-4):231-240
By using high-resolution, low-scan-rate, all-sky CCD cameras, the SPanish Meteor Network (SPMN) is currently monitoring meteor
and fireball activity on a year round basis. Here are presented just a sampling of the accurate trajectory, radiant and orbital
data obtained for meteors imaged simultaneously from two SPMN stations during the continuous 2006–2007 coverage of meteor
and fireball monitoring. Typical astrometric uncertainty is 1–2 arc min, while velocity determination errors are of the order
of 0.1–0.5 km/s, which is dependent on the distance of each event to the station and its particular viewing geometry. The
cameras have demonstrated excellent performance for detecting meteor outbursts. The recent development of automatic detection
software is also providing real-time information on the global meteor activity. Finally, some examples of the all-sky CCD
cameras applications for detecting unexpected meteor activity are given. 相似文献
163.
Jorge Ramón Alicia Correa Edison Timbe Giovanny M. Mosquera Enma Mora Patricio Crespo 《水文研究》2021,35(6):e14209
Hydrogeochemical based mixing models have been successfully used to investigate the composition and source identification of streamflow. The applicability of these models is limited due to the high costs associated with data collection and the hydrogeochemical analysis of water samples. Fortunately, a variety of mixing models exist, requiting different amount of data as input, and in data scarce regions it is likely that preference will be given to models with the lowest requirement of input data. An unanswered question is if models with high or low input requirement are equally accurate. To this end, the performance of two mixing models with different input requirement, the mixing model analysis (MMA) and the end-member mixing analysis (EMMA), were verified on a tropical montane headwater catchment (21.7 km2) in the Ecuadorian Andes. Nineteen hydrogeochemical tracers were measured on water samples collected weekly during 3 years in streamflow and eight potential water sources or end-members (precipitation, lake water, soil water from different horizons and springs). Results based on 6 conservative tracers, revealed that EMMA (using all tracers) and MMA (using pair-combinations out of the 6 conservative ones), identified the same end-members: rainfall, soil water and spring water., as well as, similar contribution fractions to streamflow from rainfall 21.9% and 21.4%, soil water 52.7% and 52.3%, and spring water 26.1% and 28.7%, respectively. Our findings show that a hydrogeochemical mixing model requiring a few tracers can provide similar outcomes than models demanding more tracers as input data. This underlines the value of a preliminary detailed hydrogeochemical characterization as basis to derive the most cost-efficient monitoring strategy. 相似文献
164.
Alberto Longo Manuel Pastor Lorenzo Sanavia Diego Manzanal Miguel Martin Stickle Chuan Lin Angel Yague Saeid Moussavi Tayyebi 《国际地质力学数值与分析法杂志》2019,43(5):833-857
Classical depth-integrated smoothed particle hydrodynamics (SPH) models for avalanches are extended in the present work to include a μ(I)− rheological model enriched with a fragmentation law. With this improvement, the basal friction becomes grain distribution dependent. Rock avalanches, where grain distribution tends to change with time while propagating, are the appropriate type of landslide to apply the new numerical proposal. The μ(I)− rheological models considered in the present work are those of Hatano and Gray, combined with two different fragmentation laws, a hyperbolic and a fractal-based law. As an application, Frank avalanche, which took place in Canada in 1903, is analyzed under the scope of the present approach, focusing in the influence of the rheological and fragmentation laws in the evolution of the avalanche. 相似文献
165.
da Silva Richarde Marques Santos Celso Augusto Guimarães Silva Jorge Flávio Casé Braga da Costa Silva Alexandro Medeiros Brasil Neto Reginaldo Moura 《Natural Hazards》2020,104(2):1953-1954
Natural Hazards - The article “Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment, Paraíba, Brazil”, written by da... 相似文献
166.
David L. Vasconcelos Fernando O. Marques Francisco C. C. Nogueira Yoe A. R. Perez Francisco H. R. Bezerra Rmulo C. Stohler Jorge A. B. Souza 《Basin Research》2021,33(1):705-728
Common basin models assume that the post‐rift tectonic evolution of most basins is usually associated with tectonic quiescence. However, tectonic inversion during the post‐rift phase has been proposed for several sedimentary basins worldwide, but how and why it happens is still a matter of debate, especially in intracontinental settings where the lithosphere is old and thick. Here, we use geological and geophysical data from the Rio do Peixe Basin in NE Brazil to show evidence that intracontinental sedimentary basins can be tectonically inverted by far‐field compressive stresses acting on pre‐existing weakness zones of lithospheric‐scale where stresses can concentrate and inversion can occur. Geomorphological and field data combined with seismic reflection, gravimetric and borehole data show that: (a) inversion occurred along two main Precambrian lithospheric‐scale shear zones, the Patos (E‐W trending) and Portalegre (NE‐SW trending), which had already been reactivated as basin‐bounding faults during the earlier rift stage; (b) post‐rift reactivation affected (mostly) the original master normal faults with the largest rift displacements, and locally produced new reverse faults; (c) during contraction, deformation was partitioned between fault reactivation and buckling of the incompetent sediment pushed against the hard basement; (d) all these signs of inversion have been observed in the field and can be demonstrated on seismic reflection profiles; and (e) combined gravimetric and seismic data show that the main structures of the basin were followed by an inversion. These data are consistent with the operation of WSW‐ENE horizontal maximum compressive stress as a result of combined pushes of the Mid‐Atlantic Ridge (towards the W) and the Andes (towards the E), responsible for the post‐rift oblique inversion of normal faults inherited from the rift phase and formed with vertical maximum compressive stress. 相似文献
167.
Antonio Luis Montealegre-Gracia María Teresa Lamelas-Gracia Alberto García-Martín Juan de la Riva-Fernández Francisco Escribano-Bernal 《地理信息系统科学与遥感》2017,54(5):721-740
The aim of study is to map the carbon dioxide (CO2) emission of the aboveground tree biomass (AGB) in case of a fire event. The suitability of low point density, discrete, multiple-return, Airborne Laser Scanning (ALS) data and the influence of several characteristics of these data and the study area on the results obtained have been evaluated. A sample of 45 circular plots representative of Pinus halepensis Miller stands were used to fit and validate the model of AGB. The ALS point clouds were processed to obtain the independent variables and a multivariate linear regression analysis between field data and ALS-derived variables allowed estimation of AGB. Then, the influence of several characteristics on the residuals of the model was analyzed. Finally, conversion factors were applied to obtain the CO2 values. The AGB model presented a R2 value of 0.84 with a relative root-mean-square error of 27.35%. This model included ALS variables related to vegetation height variability and to canopy density. Terrain slope, aspect, canopy cover, scan angle and the number of laser returns did not influence AGB estimations at plot level. 相似文献
168.
Prof. Dr. Alberto Defant 《Pure and Applied Geophysics》1940,2(1):93-112
Riassunto L'A. sottopone ad una dettagliata analisi idrodinamica i fenomeni relativi alle maree ed alle correnti di marea dello Stretto di Messina, appoggiandosi sui dati mareografici dei due mari adiacenti nonchè sulle misure ed osservazioni di F. Vercelli e G. Mazzarelli. I risultati mostrano come il fenomeno delle maree nello Stretto di Messina consista nell'accoppiamento delle maree proprie delle masse d'acque dello Stretto con gli impulsi che le stesse masse ricevono dai due mari Jonio e Tirreno. In tale processo i fenomeni d'attrito (attrito esterno e turbolenza) rivelano un'importanza fondamentale. La sovrapposizione di una corrente generale più forte con la corrente di marea dà luogo nell'imbocco Nord dello Stretto a quelle convergenze di corrente alle quali si connettono i «tagli» e le «scale di mare», nonchè i vortici di Capo Peloro (Cariddi), Scilla e San Raineri. Seguono considerazioni sulla possibilità di alterazioni morfologiche dello Stretto di Messina da epoche preistoriche con abbassamento del fondo o con allargamento delle sponde in guisa da spiegare l'indebolimento dei medesimi fenomeni.
Zusammenfassung Die Gezeiten und Gezeitenströmungen in der Strasse von Messina, an die sich die bekannten Schilderungen der alten Sagen der Scylla und Charybdis knüpfen, werden hier einer eingehenden hydrodynamischen Analyse unterzogen. Die Grundlagen für diese bilden einerseits die bekannten Grundwerte der vertikalen Gezeit in den angrenzenden Meeren im Norden und Süden der Strasse, andererseits die neueren Messungen der Gezeitenströme im engsten Querschnitt der Strasse durch Prof. Vercelli und die Beobachtungen von Prof. G. Mazzarelli. Die Ergebnisse dieser Analyse zeigen, dass das Phänomen der Gezeiten in der Meeresstrasse nichts anderes ist, als die Mitschwingungsgezeiten der Wassermassen der Strasse mit den Impulsen, die sie vom Jonischen und Thyrrhenischen Meer her empfagen. Dabei spielen die Reibungseinflüsse (äussere Reibung und Turbulenz) im engsten Teil der Strasse für die Intensität und Phase der Ströme eine ausschlaggebende Rolle. Die Superposition einer stärkeren allgemeinen Strömung und des Gezeitenstromes gibt am Nordausgang der Meeresstrasse an der Meeresoberfläche zweimal in jeder Mondperiode jene Stromkonvergenzen, an die die bekannten Sprungwellen (tagli o scale di mare) gebunden sind. Mit ihnen in Zusammenhang stehen such die Wirbel vor Cap Peloro (Charybdis), vor Scilla und vor San Raineri. Dieser Zusammenhang wird in der Arbeit näher erörtert, sowie Betrachtungen darüber angestellt, ob nicht möglicherweise morphologische Aenderungen in der Strasse von Messina seit vorhistorischer Zeit durch Vertiefung und vielleicht auch Verbreiterung der Meeresstrasse eine Schwächung der Phänomens bewirkt haben könnten. So könnte man verstehen, dass «Scylla und Charybdis» das sind die von Homer so eindrucksvoll geschilderten Gefahren für die Schiffahrt allmählich verloren gegangen sind.相似文献
169.
Moises?E.?AngelesEmail authorView authors OrcID profile Jorge?E.?González Nazario?Ramírez 《Theoretical and Applied Climatology》2018,133(1-2):59-72
It was recently reported a regional warming in the intra-Americas region where sea surface temperature exhibited increases exceeding 0.15 °C/decade and an accelerated air temperature rise that could impact building energy demands per capita (EDC). Reanalysis data is used herein to quantify the impacts of these warming trends on EDC. Results of the analysis depict a Southern Greater Antilles and inland South America with a positive annual EDC rate of 1–5 kWh per year. The Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (RCP) 2.6 and 4.5 scenarios were selected to analyze energy demand changes in the twenty-first century. A multi-model ensemble forecasts an EDC increase of 9.6 and 23 kWh/month in the RCP2.6 and RCP4.5 at the end of the twenty-first century, which may increase average building cooling loads in the region by 7.57 GW (RCP2.6) and 8.15 GW (RCP4.5), respectively. Furthermore, 4 of 9 (RCP2.6) and 7 of 9 (RCP4.5) of the major countries in this region have EDCs ranging between 1887 and 2252 kWh/year at the end of this century. Therefore, increased energy production and improved energy infrastructure will be required to maintain ideal indoor building conditions at the end of the twenty-first century in these tropical coastal regions as consequence of a warmer climate. 相似文献
170.
Mariano Garcia Sassan Saatchi Antonio Ferraz Carlos Alberto Silva Susan Ustin Alexander Koltunov Heiko Balzter 《Carbon balance and management》2017,12(1):4