A mechanism for the multidecadal modulation of ENSO teleconnection with Europe   总被引：1，自引：1，他引：0  

Jorge López-Parages  Belén Rodríguez-Fonseca  Laurent Terray 《Climate Dynamics》2015,45(3-4):867-880

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Caribbean hurricanes: interannual variability and prediction     

Mark R. Jury  Ernesto Rodr��guez 《Theoretical and Applied Climatology》2011,106(1-2):105-115

Climatic conditions that affect the interannual variability of Caribbean hurricanes are studied. Composite meteorological and oceanographic reanalysis fields are constructed for active and inactive seasons since 1979, and differences are calculated for spring and summer periods to provide guidance in statistical analysis. Predictors are extracted for areas exhibiting high contrast between active and inactive seasons, and intercomparisons are made. Zonal winds north of Venezuela exhibit westerly anomalies prior to active years, so coastal upwelling and the north Brazil current are diminished. Rainfall increases in the Orinoco River basin, creating a fresh warm plume north of Trinidad. The predictor time series are regressed onto an index of Caribbean hurricanes, and multivariate algorithms are formulated. It is found that atmospheric kinematic and convective predictors explain only ??20% of hurricane variance at 3?C5-month lead time. Subsurface ocean predictors offer higher levels of explained hurricane variance (42%) at 3?C5-month lead time, using 1?C200-m-depth-averaged temperatures in the east Pacific and southern Caribbean. We place the statistical results in a conceptual framework to better understand climatic processes anticipating Caribbean hurricanes.  相似文献   

Implementation of the European Marine Strategy Framework Directive: a methodological approach for the assessment of environmental status, from the Basque Country (Bay of Biscay)     

Borja A  Galparsoro I  Irigoien X  Iriondo A  Menchaca I  Muxika I  Pascual M  Quincoces I  Revilla M  Germán Rodríguez J  Santurtún M  Solaun O  Uriarte A  Valencia V  Zorita I 《Marine pollution bulletin》2011,62(5):889-904

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Transgressive dunefield landforms and vegetation associations,Doña Juana,Veracruz, Mexico     

Patrick Hesp  Marisa Martinez  Graziela Miot da Silva  Natalia Rodríguez‐Revelo  Erika Gutierrez  Adriana Humanes  Daniela Laínez  Irene Montaño  Verónica Palacios  Agustín Quesada  Lorena Storero  Gabriela González Trilla  Carolina Trochine 《地球表面变化过程与地形》2011,36(3):285-295

Transgressive dune fields often comprise a multiplicity of landforms where vegetation processes largely affect landform dynamics, which in turn, also affect vegetation processes. These associations have seldom been studied in detail. This paper examines four separate landform types in a complex coastal transgressive dunefield located in the central Gulf of Mexico, in order to assess the relationships between dunefield habitat, local environmental factors, vegetation associations and landform evolution. Topographic surveys using tape and clinometer were conducted in conjunction with vegetation survey transects at four locations across the Doña Juana dunefield. Vegetation surveys allowed the estimation of relative plant cover of each plant species found along the transects. A large variety of landforms were found at the Doña Juana Dunefield: deflation plains, gegenwalle (counter) ridges, transverse dune trailing ridges, blowouts and parabolic dunes, aklé (fish‐scale shaped) dunefields and precipitation ridges, with plant species associations developing on these different landforms equally variable. Flood tolerant species were located in the lower parts (deflation plain and gegenwalle ridges) whereas the older and dryer parts were covered by coastal matorral shrubs. Burial‐tolerant species were dominant in the most mobile areas (blowouts and aklé dunefield and margin). The dune trailing ridge, with relatively milder conditions, showed the highest richness, with no dominant species. A dual interaction was found such that colonizing species both create and affect topography, and in turn, topography determines vegetation association and succession patterns. In coastal dunes, the vegetation and abiotic environment (namely the different landforms and the inherent micronevironmental variability) interact tightly and generate a complex and highly dynamic biogeomorphic system where substrate mobility and colonization processes reinforce one another in positive feedback. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Insights into cation exchange selectivity of a natural clinoptilolite by means of dielectric relaxation spectroscopy     

Gerardo Rodríguez-Fuentes  Sabine Devautour-Vinot  Sekou Diaby  François Henn 《Physics and Chemistry of Minerals》2011,38(8):613-621

Purified natural clinoptilolite from the Tasajeras deposit, Cuba, and some of its metal exchanged forms are studied, at the dehydrated state, by means of dielectric relaxation spectroscopy (DRS) using two different modus operandi: complex impedance spectroscopy and dielectric dynamic thermal analysis. Data analysis yields the determination of the extra-framework cation (EFC) population into the various possible crystallographic sites of the zeolitic framework as well as of the activation energy characterizing the localized hopping mechanism of EFC. First, it is shown that the DRS responses obtained here match well with the previous reported data, which were previously localized EFCs in positions close to M1 and M2 sites when the clinoptilolite is modified to almost homoionic form. From this outcome, it can be concluded that all EFCs are in the same crystallographic situation regarding solvation or, in other terms, that no steric effect can be taken into account to explain cationic selectivity. Second, based on the assumption that the activation energy for EFC hopping is directly connected to the EFC/framework interaction and on simple thermodynamics consideration, we show this interaction does not govern the EFC exchange reaction. So, it is emphasized that EFC/H₂O interaction is the key factor for cation exchange selectivity.  相似文献   

Comparison of Two Sample Preparation Methods for X‐Ray Fluorescence Spectrometry in the Determination of Ni and Cr     

Surendra P. Verma  Rosalinda González‐Ramírez  Rodolfo Rodríguez‐Ríos 《Geostandards and Geoanalytical Research》2011,35(2):183-192

Pressed powder pellets and fused beads or glass disks are routinely used in X‐ray fluorescence spectrometry for the determination of major and trace elements, respectively, in geological materials. In order to evaluate the performance of these two sample preparation methods, we determined Ni and Cr concentrations of fourteen RMs from Japan, France and South Africa, and eighty‐five igneous and three sedimentary rock samples from Mexico in both powder pellets and glass beads. We also computed new values of statistical parameters for RMs from an outlier‐based multiple‐test method and compared them with the literature mean and confidence limit values. The results showed that the multiple‐test method provided more reliable central tendency and dispersion parameters for RMs than those obtained previously from the two or three standard deviation method, or from robust methods. The powder pellet and fused bead sample preparation methods provided consistent results for Ni and Cr at concentration levels > 50 μg g^?1 in this application; for lower concentration levels, however, these methods showed somewhat greater differences. For quantitative comparisons, both ordinary and weighted least‐squares linear regression models were used to show that the two sample preparation methods provided generally unbiased results.  相似文献   

Furrows in the southern Scan Basin, Antarctica: interplay between tectonic and oceanographic influences     

Francisco Jos�� Lobo  Francisco Javier Hern��ndez-Molina  Fernando Bohoyo  Jes��s Galindo-Zald��var  Andr��s Maldonado  Yasmina Martos  Jos�� Rodr��guez-Fern��ndez  Luis Somoza  Juan Tom��s V��zquez 《Geo-Marine Letters》2011,31(5-6):451-464

Multibeam echosounder data and TOPAS seismic reflection profiles collected during the AntPac 1997, Scan 2004, and Scan 2008 cruises aboard the RV Hespérides reveal a host of surficial geomorphological features as yet poorly investigated in the Scan Basin, south-central Scotia Sea. This area represents one of the deep gateways between the Weddell Sea and the Scotia Sea, since it enables the northward flow of a branch of the Weddell Sea Deep Water (WSDW). Analysis of the data identifies numerous elongated depressions interpreted as furrows in the southernmost sector of the basin. These furrows show two main trends, i.e., either N?CNNW parallel to, or NE oblique to regional bathymetric contours. These trends plausibly reflect a tectonic influence on the bottom-flow distribution, conditioned by a set of recent, conjugate strike-slip faults that developed on the seafloor under dominant NNE?CSSW compression and orthogonal extension. The furrows exhibit distinct geomorphological patterns at either side of the basin, which can be related to west?Ceast asymmetry in the WSDW flow direction. Consistent with existing knowledge of regional WSDW dynamics, northward WSDW overflows would be channeled along the western part of the basin at higher bottom-current velocities, thereby generating more erosional-type furrows that are straighter, more elongated, and have more abrupt sidewalls than their eastern counterparts. In contrast, weaker southward WSDW would flow along the eastern part of the basin, resulting in more depositional-type furrows that are more curved, less elongated, and have gentler sidewalls.  相似文献   

Variation of Proton Flux Profiles with the Observer’s Latitude in Simulated Gradual SEP Events     

R. Rodríguez-Gasén  A. Aran  B. Sanahuja  C. Jacobs  S. Poedts 《Solar physics》2014,289(5):1745-1762

We studied the variation of the shape of the proton intensity–time profiles in simulated gradual Solar Energetic Particle (SEP) events with the relative observer’s position in space with respect to the main direction of propagation of an interplanetary (IP) shock. Using a three-dimensional (3D) magnetohydrodynamic (MHD) code to simulate such a shock, we determined the evolution of the downstream-to-upstream ratios of the plasma variables at its front. Under the assumption of an existing relation between the normalized ratio in speed across the shock front and the injection rate of shock-accelerated particles, we modelled the transport of the particles and obtained the proton flux profiles to be measured by a grid of 18 virtual observers located at 0.4 and 1.0 AU, with different latitudes and longitudes with respect to the shock nose. The differences among flux profiles are the result of the way each observer establishes a magnetic connection with the shock front, and we found that changes in the observer’s latitude may result in intensity changes of up to one order of magnitude at the two radial distances considered here. The peak intensity variation with the radial distance for the pair of observers located at the same angular position was also derived. This is the first time that the latitudinal dependence of the peak intensity with the observer’s heliocentric radial distance has been quantified within the framework of gradual SEP event simulations.  相似文献   

Ionospheric Disturbances and Their Impact on IPS Using MEXART Observations     

M. Rodríguez-Martínez  H. R. Pérez-Enríquez  A. Carrillo-Vargas  R. López-Montes  E. A. Araujo-Pradere  G. A. Casillas-Pérez  J. A. L. Cruz-Abeyro 《Solar physics》2014,289(7):2677-2695

We study the impact of ionospheric disturbances on the Earth’s environment caused by the solar events that occurred from 20 April to 31 May 2010, using observations from the Mexican Array Radio Telescope (MEXART). During this period of time, several astronomical sources presented fluctuations in their radio signals. Wavelet analysis, together with complementary information such as the vertical total electron content (vTEC) and the Dst index, were used to identify and understand when the interplanetary scintillation (IPS) could be contaminated by ionospheric disturbances (IOND). We find that radio signal perturbations were sometimes associated with IOND and/or IPS fluctuations; however, in some cases, it was not possible to clearly identify their origin. Our Fourier and wavelet analyses showed that these fluctuations had frequencies in the range ≈?0.01 Hz?–?≈?1.0 Hz (periodicities of 100 s to 1 s).  相似文献   

Cme Phenomenology in Different Solar Magnetic Scenarios     

R. Rodríguez Taboada  G. Gil Moreno  A. Méndez Berhondo  R. Pérez-Enriquez 《Astrophysics and Space Science》1997,256(1-2):373-376

The existence of three magnetic scenarios with magnetic field intensities one order apart was considered. CMEs were associated to different solar activity phenomena and solar features showing different characteristics. Those associated to intense magnetic fields were more complex, having either more components or multiple emissions and a greater magnetic energy to particle acceleration conversion rate. On the other hand, simple CMEs were found to associate to weak magnetic fields. No evidence was found that the process that leads to CME starts before their detection at 1.6 solar radii. This indicates that the whole volume moves upward simultaneously, no matter how deep it reaches into the solar atmosphere.  相似文献