Stepwise selection of functional covariates in forecasting peak levels of olive pollen     

Manuel Escabias  Mariano J. Valderrama  Ana M. Aguilera  M. Elena Santofimia  M. Carmen Aguilera-Morillo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(2):367-376

High levels of airborne olive pollen represent a problem for a large proportion of the population because of the many allergies it causes. Many attempts have been made to forecast the concentration of airborne olive pollen, using methods such as time series, linear regression, neural networks, a combination of fuzzy systems and neural networks, and functional models. This paper presents a functional logistic regression model used to study the relationship between olive pollen concentration and different climatic factors, and on this basis to predict the probability of high (and possibly extreme) levels of airborne pollen, selecting the best subset of functional climatic variables by means of a stepwise method based on the conditional likelihood ratio test.  相似文献   

Coastal dynamics off Northwest Iberia during a stormy winter period     

Pablo Otero  Manuel Ruiz-Villarreal  Luz García-García  Gonzalo González-Nuevo  Jose Manuel Cabanas 《Ocean Dynamics》2013,63(1):115-129

The consequences of a stormy winter period (2009/2010) on the shelf and coastal dynamics off Northwest Iberia are analysed by using model results in combination with the set of available observations in the frame of the Iberian Margin Ocean Observatory (RAIA), a cross-border infrastructure among North Portugal and Galicia (Spain). During the study winter, the frequent arrival of weather fronts forced river plumes to flow along the inner shelf in a fast (>1 m?s^?1) jet-like structure. The buoyant current strongly influenced the outer rías, the name of the estuaries in the region, where a strong decay of surface salinity (<10.5) has been observed. Once the weather front has passed, the wind reversal forced the offshore expansion of river plumes and also the development of a winter upwelling event. Thermohaline patterns in both model and observations revealed an intrusion of warm (>15 °C) and salty (>35.9) waters into the rías associated with the Iberian Poleward Current. Finally, some Lagrangian modelling experiments were performed to analyse the transport ability of the plume and the effect that could have had in the biological material trapped on it. The experiments reveal that an overall northward displacement of surface particles will be expected after several alternate wind events.  相似文献   

Cumulative impacts on seabed habitats: An indicator for assessments of good environmental status     

Samuli Korpinen  Manuel MeidingerMaria Laamanen 《Marine pollution bulletin》2013

The European seas are under anthropogenic pressures impacting the state of water quality, benthic habitats and species. The EU Marine Strategy Framework Directive (MSFD) requires the Member States to assess the impacts of pressures and make a programme of measures leading to good environmental status (GES) by 2020. This study presents a method for assessing the quantity and distribution of anthropogenic impacts on benthic habitats in the Baltic Sea by using spatial data of human pressures and benthic habitats. The southern sub-basins were more extensively impacted than the northern sub-basins. Over the entire sea area, deep sea habitats were more impacted than shallower infralittoral and circalittoral habitats. Sand and coarse sediments were the seabed types relatively most impacted in the Baltic Sea scale. A comparison against tentative thresholds for GES showed that in the sub-basin scale only one third of the habitat types was in GES.  相似文献   

Range imaging: a new method for high‐resolution topographic measurements in small‐ and medium‐scale field sites     

Manuel Nitsche  Jens M. Turowski  Alexandre Badoux  Dieter Rickenmann  Tobias K. Kohoutek  Michael Pauli  James W. Kirchner 《地球表面变化过程与地形》2013,38(8):810-825

Topographic measurements are essential for the study of earth surface processes. Three‐dimensional data have been conventionally obtained through terrestrial laser scanning or photogrammetric methods. However, particularly in steep and rough terrain, high‐resolution field measurements remain challenging and often require new creative approaches. In this paper, range imaging is evaluated as an alternative method for obtaining surface data in such complex environments. Range imaging is an emerging time‐of‐flight technology, using phase shift measurements on a multi‐pixel sensor to generate a distance image of a surface. Its suitability for field measurements has yet not been tested. We found ambient light and surface reflectivity to be the main factors affecting error in distance measurements. Low‐reflectivity surfaces and strong illumination contrasts under direct exposure to sunlight lead to noisy distance measurements. However, regardless of lighting conditions, the accuracy of range imaging was markedly improved by averaging multiple images of the same scene. For medium ambient lighting (shade) and a light‐coloured surface the measurement uncertainty was approximately 9 mm. To further test the suitability of range imaging for field applications we measured a reach of a steep mountain stream with a horizontal resolution of approximately 1 cm (in the focal plane of the camera), allowing for the interpolation of a digital elevation model on a 2 cm grid. Comparison with an elevation model obtained from terrestrial laser scanning for the same site revealed that both models show similar degrees of topographic detail. Despite limitations in measurement range and accuracy, particularly at bright ambient lighting, range imaging offers three‐dimensional data in real time and video mode without the need of post‐processing. Therefore, range imaging is a useful complement or alternative to existing methods for high‐resolution measurements in small‐ to medium‐scale field sites. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Effect of galvanic distortions on the series and parallel magnetotelluric impedances and comparison with other responses     

Enrique Gómez-Treviño  Francisco Javier Esparza Hernández  José Manuel Romo Jones 《Geofísica Internacional》2013,52(2):135-152

The series and parallel impedances of the magnetotelluric tensor are appraised in relation to their relative immunity to galvanic electric distortions. The distorted responses are modeled using the Groom-Bailey decomposition of the tensor in terms of twist, shear, statics and strike direction. These four parameters and the undistorted responses are normally considered as unknowns, and are obtained from field data through the solution of an inverse problem. In the present work we use the decomposition as a forward model to simulate distorted sounding curves. Starting with undistorted 2-d te and tm responses, the tensor is distorted by assuming arbitrary values of twist, shear, static and strike direction. By default, both series and parallel responses are immune to the strike direction because they are invariants under rotation. In addition, series responses are immune to twist and shear and parallel responses only to twist. The dependence of the latter on shear is in the form of a real factor that shifts downwards the amplitude curves. On the other hand, the effect of statics on both series and parallel responses is more complicated than that on the impedance tensor because it cannot be accounted for by a simple shift of the curves. On the whole, there is a positive balance on the part of the series and parallel impedances over the te and tm responses because some of the distortions are filtered out by the invariants. It is shown that invariance is not sufficient to be immune to any of the distortions. The example chosen is Eggers’ eigenvalues, which are immune only to the by-the-fault strike direction. Invariance is not necessary either, as evidenced by the phase tensor, whose elements depend on strike but are immune to all distortions. The derivations are illustrated using soundings from the synthetic coprod2s1 and field-recorded coprod2 and bc87 data sets.  相似文献   

The evolution of the hydrothermal IOCG system in the Mantoverde district,northern Chile: new evidence from microthermometry and stable isotope geochemistry     

Ana?A.?RiegerEmail author  Robert?Marschik  Manuel?Díaz 《Mineralium Deposita》2012,47(4):359-369

New microthermometric data combined with stable isotope geochemistry and paragenetic relationships support a previously suggested cooling–mixing model for the iron oxide–copper–gold mineralization in the Mantoverde district. Fluid inclusions show characteristics of a CO₂-bearing aqueous NaCl ± CaCl₂ salt system. The evolution of the Mantoverde hydrothermal system is characterized by (1) an early hypersaline, high to moderate temperature fluid; (2) a moderate saline, moderate temperature fluid; and (3) a low saline, moderate to low temperature fluid. Early magnetite formation took place at median temperatures of 435.0°C, whereas hematite formed at median temperatures of 334.4°C. The main sulfide mineralization texturally post-dates the iron oxides and occurred before late-stage calcite, which developed at a median temperature of 244.8°C. Boiling occurs only locally and is of no relevance for the ore formation. The microthermometric and stable isotope data are supportive for a fluid cooling and mixing model, and suggestive for a predominantly magmatic–hydrothermal fluid component during the iron oxide and main sulfide mineralization. Thereafter, the incursion of a nonmagmatic fluid of ultimately meteoric or seawater gains more importance.  相似文献   

Espacio,Ambiente y los Inicios de la Agricultura Indígena en el Noroeste Argentino: Un Enfoque Arqueológico. María Marta Sampietro Vattuone. 2010. JAS Arqueología Editorial S.L.U., Madrid. 188 pp., ISBN978‐84‐938146‐4‐9, 19€ (paperback).     

Manuel R. Palacios‐Fest 《Geoarchaeology》2012,27(2):183-184

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Uranium-series isotopes transport in surface,vadose and ground waters at San Marcos uranium bearing basin,Chihuahua, Mexico     

Juan Carlos Burillo Montúfar  Manuel Reyes Cortés  Ignacio Alfonso Reyes Cortés  Ma. Socorro Espino Valdez  Octavio Raúl Hinojosa de la Garza  Diana Pamela Nevárez Ronquillo  Eduardo Herrera Peraza  Marusia Rentería Villalobos  María Elena Montero Cabrera 《Applied Geochemistry》2012

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EVA: GPS-based extended velocity and acceleration determination   总被引：1，自引：0，他引：1  

Dagoberto Salazar  Manuel Hernandez-Pajares  Jose Miguel Juan-Zornoza  Jaume Sanz-Subirana  Angela Aragon-Angel 《Journal of Geodesy》2011,85(6):329-340

In this work, a new GPS carrier phase-based velocity and acceleration determination method is presented that extends the effective range of previous techniques. The method is named ‘EVA’, and may find applications in fields such as airborne gravimetry when rough terrain or water bodies make difficult or impractical to set up nearby GPS reference receivers. The EVA method is similar to methods such as Kennedy (Precise acceleration determination from carrier phase measurements. In: Proceedings of the 15th international technical meeting of the satellite division of the Institute of Navigation. ION GPS 2002, Portland pp 962–972, 2002b) since it uses L1 carrier phase observables for velocity and acceleration determination. However, it introduces a wide network of stations and it is independent of precise clock information because it estimates satellite clock drifts and drift rates ‘on-the-fly’, requiring only orbit data of sufficient quality. Moreover, with EVA the solution rate is only limited by data rate, and not by the available precise satellite clocks data rate. The results obtained are more robust for long baselines than the results obtained with the reference Kennedy method. An advantage of being independent of precise clock information is that, beside IGS Final products, also the Rapid, Ultra-Rapid (observed) and Ultra-Rapid (predicted) products may be used. Moreover, the EVA technique may also use the undifferenced ionosphere-free carrier phase combination (LC), overcoming baseline limitations in cases where ionosphere gradients may be an issue and very low biases are required. During the development of this work, some problems were found in the velocity estimation process of the Kennedy method. The sources of the problems were identified, and an improved version of the Kennedy method was used for this research work. An experiment was performed using a light aircraft flying over the Pyrenees, showing that both EVA and the improved Kennedy methods are able to cope with the dynamics of mountainous flight. A RTK-derived solution was also generated, and when comparing the three methods to a known zero-velocity reference the results yielded similar performance. The EVA and the improved-Kennedy methods outperformed the RTK solutions, and the EVA method provided the best results in this experiment. Finally, both the improved version of the Kennedy method and the EVA method were applied to a network in equatorial South America with baselines of more than 1,770 km, and during local noon. Under this tough scenario, the EVA method showed a clear advantage for all components of velocity and acceleration, yielding better and more robust results.  相似文献   

The ionosphere: effects,GPS modeling and the benefits for space geodetic techniques   总被引：12，自引：8，他引：4  

Manuel Hernández-Pajares  J. Miguel Juan  Jaume Sanz  Àngela Aragón-Àngel  Alberto García-Rigo  Dagoberto Salazar  Miquel Escudero 《Journal of Geodesy》2011,85(12):887-907

The main goal of this paper is to provide a summary of our current knowledge of the ionosphere as it relates to space geodetic techniques, especially the most informative technology, global navigation satellite systems (GNSS), specifically the fully deployed and operational global positioning system (GPS). As such, the main relevant modeling points are discussed, and the corresponding results of ionospheric monitoring are related, which were mostly computed using GPS data and based on the direct experience of the authors. We address various phenomena such as horizontal and vertical ionospheric morphology in quiet conditions, traveling ionospheric disturbances, solar flares, ionospheric storms and scintillation. Finally, we also tackle the question of how improved knowledge of ionospheric conditions, especially in terms of an accurate understanding of the distribution of free electrons, can improve space geodetic techniques at different levels, such as higher-order ionospheric effects, precise GNSS navigation, single-antenna GNSS orientation and real-time GNSS meteorology.  相似文献