60 research outputs found

    An update on remote measurement of soil moisture over vegetation using infrared temperature measurements: A FIFE perspective

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    Using model development, image analysis and micrometeorological measurements, the object is to push beyond the present limitations of using the infrared temperature method for remotely determining surface energy fluxes and soil moisture over vegetation. Model development consists of three aspects: (1) a more complex vegetation formulation which is more flexible and realistic; (2) a method for modeling the fluxes over patchy vegetation cover; and (3) a method for inferring a two-layer soil vertical moisture gradient from analyses of horizontal variations in surface temperatures. HAPEX and FIFE satellite data will be used along with aircraft thermal infrared and solar images as input for the models. To test the models, moisture availability and bulk canopy resistances will be calculated from data collected locally at the Rock Springs experimental field site and, eventually, from the FIFE project

    Remotely Sensed Index of Deforestation/Urbanization for use in Climate Models

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    The purpose of this investigation is to use a new method for deriving land surface parameters from a combination of thermal infrared and vegetation index measurements from satellites (Landsat-TM, and NOAA-AVHRR) and to integrate these parameters with more conventional data bases. We have completed an investigation of urbanization in the State College, PA area and have begun work in Chester County, PA, and Costa Rica. Our basic hypothesis is that changes in land use, including deforestation, exert a profound influence on local microclimates whose effects may greatly exceed in importance those occurring on larger scales

    Remote measurement of soil moisture over vegetation using infrared temperature measurements

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    Better methods for remote sensing of surface evapotranspiration, soil moisture, and fractional vegetation cover were developed. The objectives were to: (1) further develop a model of water movement through the soil/plant/atmosphere system; (2) use this model, in conjunction with measurements of infrared surface temperature and vegetation fraction; (3) determine the magnitude of radiometric temperature response to water stress in vegetation; (4) show at what point one can detect that sensitivity to water stress; and (5) determine the practical limits of the methods. A hydrological model that can be used to calculate soil water content versus depth given conventional meteorological records and observations of vegetation cover was developed. An outline of the results of these initiatives is presented

    A remotely sensed index of deforestation/urbanization for use in climate models

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    The object of this research is to use indirect measurements, notably thermal infrared, to describe urbanization and deforestation with parameters that can be used to assess, as well as predict, the effects of land use changes on local microclimate. More specifically, we use a new approach for the treatment of remotely sensed data; this is referred to as the 'triangle' method. The name triangle is given because the envelope of data points, when plotted as a function of surface radiant temperature versus vegetation index or fractional vegetation cover, exhibits the shape of a triangle. From the information contained on these 'scatter plots', land use changes can be related to two intrinsic surface variables, the surface moisture availability (M(sub 0))(sup 1) and fractional vegetation cover. Recent work by Carlson et al. indicate that the triangle shape on the scatter plots may be scale similar, suggesting that these two parameters are subject to the same interpretation on differing scales. A second objective in this research is to determine if historical data for Advanced Very High Resolution Radiometer (AVHRR) (NOAA satellite; 1.1 km resolution at nadir) can be used to assess changes in regional land use over time. To this end, two target areas were chosen for the investigation of urbanization and two for deforestation. The former comprise tow areas in Pennsylvania, one a small but rapidly growing population center (State College) and the other a medium-sized urban area which continues to undergo development (Chester County). The two deforestation sites consist of rain forest areas in western and central Costa Rica and a region in the Brazilian Amazon

    An Overview of the Use of the SimSphere Soil Vegetation Atmosphere Transfer (SVAT) Model for the Study of Land-Atmosphere Interactions

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    Soil Vegetation Atmosphere Transfer (SVAT) models consist of deterministic mathematical representations of the physical processes involved between the land surface and the atmosphere and of their interactions, at time-steps acceptable for the study of land surface processes. The present article provides a comprehensive and systematic review of one such SVAT model suitable for use in mesoscale or boundary layer studies, originally developed by [1]. This model, which has evolved significantly both architecturally and functionally since its foundation, has been widely applied in over thirty interdisciplinary science investigations, and it is currently used as a learning resource for students in a number of educational institutes globally. The present review is also regarded as very timely, since a variation of a method using this specific SVAT model along with satellite observations is currently being considered in a scheme being developed for the operational retrieval of soil surface moisture by the US National Polar-orbiting Operational Environmental Satellite System (NPOESS), in a series of satellites that are due to be launched from 2016 onwards

    Graphical surface-vegetation-atmosphere transfer (SVAT) model as a pedagogical and research tool

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    This paper considers, by example, the use of a Surface-Atmosphere-Vegetation-Transfer (SVAT), Atmospheric Boundary Layer (ABL) model designed as a pedagogical tool. The goal of the computer software and the approach is to improve the efficiency and effectiveness of communicating often complex and mathematical based disciplines (e.g., micrometeorology, land surface processes) to the non-specialist interested in studying problems involving interactions between vegetation and the atmosphere and, in the nature of interactions rather than a description of the components. Topics are addressed within a Socratic framework using a scenario system based approach: As an example of this, the interactions between a vegetation canopy and a carbon dioxide rich (2 times ambient CO2) atmosphere, are presented. This will illustrate obvious to the student or, would be to complicated to be insightful. This type of approach is another careful, critical way of thinking fostered by interactions with a computer model. The student instead of taking things apart, is looking at them as wholes and is encouraged to make new and important distinctions

    Acerca de la estimación de la disponibilidad de humedad en el suelo a partir de mediciones remotas

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    Se presenta la extensión de un método para obtener la disponibilidad de humedad en el suelo. El mismo consiste en combinar el producto de un modelo unidimensional de capa límite con la información contenida en imágenes infrarrojas digitalizadas provenientes del satélite GOES-Este. La región elegida tiene un gradiente este-oeste del campo de la precipitación media anual similar al de la franja este-oeste del centro de nuestro país. Dicha región se encuentra localizada en parte da los astados de Texas y Oklahoma (EEUU) y abarca unos 300.000 kilómetros cuadrados. Se obtuvieron los campos de la disponibilidad de humedad para tres días distintos y para dos subregiones que cubran la y totalidad del orea seleccionada. Hatos campos se compararon con los correspondientes al Indice de Precipitación Acumulada a fin de evaluar la representanvidad de los resultados obtenidos. Esa comparación arroba valores del coeficiente de correlación superiores al 0,65 en algunos casos. Al combinarse los valores de los parametros mencionados para distintos pares de días se obtuvieron coeficientes de correlación mayores de 0,70 lo que sugiere la posibilidad de utilizar el presante Método pera obtener índices de humedad del suelo.The extensión ot a nethod to obtain soil moisture availability ís presentad. It consista in the combination of a one dimensional boundary layar nodal and infrered digital satellite magas fros GOES East. The región selected presents an east-west average rainl'all gradient similar to that of Argentina's east-west central stripe. It is located ín parta of the Oklahoma and Texas States (USA) and comprises about 300.000 square kilometers. Moisture ovailability fields for three different days and two subregions were obtained. These fields were compared with the ones of the Antecedent Fracipitation Index ín order to evalúate them. The correlation coefficient was above 0.65 for soné cases. The parameters difference was compared for different days and correlation coefficient valúes above 0,70 were obtained. These resulte euggest that this method can be used ín order to compute soil moisture indexes.Asociación Argentina de Geofísicos y Geodesta

    Stripes, Vibrations and Superconductivity

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    We propose a model of a spatially modulated collective charge state of superconducting cuprates. The regions of higher carrier density (stripes) are described in terms of Luttinger liquids and the regions of lower density as a two-dimensional interacting bosonic gas of d_{x^2-y^2} hole pairs. The interactions among the elementary excitations are repulsive and the transition to the superconducting state is driven by decay processes. Vibrations of the CCS and the lattice, although not participating directly in the binding mechanism, are fundamental for superconductivity. The superfluid density and the lattice have a strong tendency to modulation implying a still unobserved dimerized stripe phase in cuprates. The phase diagram of the model has a crossover from 1D to 2D behavior and a pseudogap region where the amplitude of the order parameters are finite but phase coherence is not established. We discuss the nature of the spin fluctuations and the unusual isotope effect within the model.Comment: 51 pages, 20 figures. Post-March Meeting version: New references are added, some of the typos are corrected, and a few new discussions are include

    Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis

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    Background: Patellofemoral pain is considered one of the most common forms of knee pain, affecting adults, adolescents, and physically active populations. Inconsistencies in reported incidence and prevalence exist and in relation to the allocation of healthcare and research funding, there is a clear need to accurately understand the epidemiology of patellofemoral pain. Methods: An electronic database search was conducted, as well as grey literature databases, from inception to June 2017. Two authors independently selected studies, extracted data and appraised methodological quality. If heterogeneous, data were analysed descriptively. Where studies were homogeneous, data were pooled through a meta-analysis. Results: 23 studies were included. Annual prevalence for patellofemoral pain in the general population was reported as 22.7%, and adolescents as 28.9%. Incidence rates in military recruits ranged from 9.7 – 571.4/1,000 person-years, amateur runners in the general population at 1080.5/1,000 person-years and adolescents amateur athletes 5.1% - 14.9% over 1 season. One study reported point prevalence within military populations as 13.5%. The pooled estimate for point prevalence in adolescents was 7.2% (95% Confidence Interval: 6.3% - 8.3%), and in female only adolescent athletes was 22.7% (95% Confidence Interval 17.4% - 28.0%). Conclusion: This review demonstrates high incidence and prevalence levels for patellofemoral pain. Within the context of this, and poor long term prognosis and high disability levels, PFP should be an urgent research priority
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