Automated proximal sensing for estimation of the bidirectional reflectance distribution function in a Mediterranean tree-grass ecosystem

Premio Extraordinario de Doctorado de la UAH en el año académico 2015-2016Los sistemas automáticos de proximal sensing permiten adquirir información espectral de las cubiertas terrestres elevada frecuencia temporal, que puede relacionarse con observaciones remotas o de otros tipos de sensores como los sistemas de eddy covariance. Si bien inicialmente los sistemas automáticos empleaban sensores multi-banda, en los últimos años se ha incrementado el uso de sensores hiperespectrales. Si bien estos sensores ofrecen información redundante y de alta resolución espectral, las mediciones están sujetas a múltiples fuentes de incertidumbre; tanto instrumentales (dependencias de la temperatura o el nivel de señal) como direccionales (dependencia de la geometría de observación e iluminación). Las dependencias instrumentales pueden ser minimizadas, por ejemplo, controlando la temperatura del instrumento o el nivel de señal registrado. En otros casos, es necesario parametrizar y emplear modelos para corregir los datos. En la presente tesis doctoral los capítulos 1 al 3 presentan la caracterización completa de un espectrómetro de campo instalado en un sistema automático. Los capítulos 1 y 2 analizan las fuentes de no linealidad en este instrumento, una de las cuales no había sido anteriormente descrita en este tipo de instrumentos. El tercer capítulo muestra el conjunto completo de modelos de corrección de los efectos instrumentales y la cadena de procesado correspondiente. Por otro lado, los sistemas automáticos se enfrentan a efectos direccionales ya que adquieren mediciones continuamente durante el ciclo solar diario y bajo cualquier condición de iluminación. Esto maximiza los rangos de los ángulos de iluminación y también de la fracción difusa de la irradiancia. Esta variabilidad de condiciones de iluminación, combinada con una variación de los ángulos de observación permite obtener la información necesaria para caracterizar las respuestas direccionales de la cubierta observada. Algunos sistemas automáticos multi-angulares ya han sido empleados para realizar esta caracterización mediante la estimación de la Función de Distribución de Reflectividad Bidireccional (BRDF) en ecosistemas homogéneos. Sin embargo, esto no se ha conseguido aún en áreas heterogéneas, como es el caso de los ecosistemas tree-grass o de sabana. Así mismo, los trabajos previos no han considerado los efectos de la radiación difusa en el estudio del BRDF. En el capítulo 4 proponemos una metodología que permite desmezclar y caracterizar simultáneamente la función de distribución de reflectividad hemisférica-direccional de las dos cubiertas de vegetación presentes en el ecosistema, pasto y arbolado. También se analizan los efectos de las diferentes características del método. Finalmente, los resultados se escalan y se comparan con productos globales de satélite como el producto BRDF de MODIS. La conclusión obtenida es que se requieren más esfuerzos en el desarrollo y caracterización de sensores hiperespectrales instalados en sistemas automáticos de campo. Estos sistemas deberían adoptar configuraciones multi-angulares de modo que puedan caracterizarse las respuestas direccionales. Para ello, será necesario considerar los efectos de la radiación difusa; y en algunos casos también la heterogeneidad de la escena

Automated proximal sensing for estimation of the bidirectional reflectance distribution function in a Mediterranean tree-grass ecosystem

Premio Extraordinario de Doctorado de la UAH en el año académico 2015-2016Los sistemas automáticos de proximal sensing permiten adquirir información espectral de las cubiertas terrestres elevada frecuencia temporal, que puede relacionarse con observaciones remotas o de otros tipos de sensores como los sistemas de eddy covariance. Si bien inicialmente los sistemas automáticos empleaban sensores multi-banda, en los últimos años se ha incrementado el uso de sensores hiperespectrales. Si bien estos sensores ofrecen información redundante y de alta resolución espectral, las mediciones están sujetas a múltiples fuentes de incertidumbre; tanto instrumentales (dependencias de la temperatura o el nivel de señal) como direccionales (dependencia de la geometría de observación e iluminación). Las dependencias instrumentales pueden ser minimizadas, por ejemplo, controlando la temperatura del instrumento o el nivel de señal registrado. En otros casos, es necesario parametrizar y emplear modelos para corregir los datos. En la presente tesis doctoral los capítulos 1 al 3 presentan la caracterización completa de un espectrómetro de campo instalado en un sistema automático. Los capítulos 1 y 2 analizan las fuentes de no linealidad en este instrumento, una de las cuales no había sido anteriormente descrita en este tipo de instrumentos. El tercer capítulo muestra el conjunto completo de modelos de corrección de los efectos instrumentales y la cadena de procesado correspondiente. Por otro lado, los sistemas automáticos se enfrentan a efectos direccionales ya que adquieren mediciones continuamente durante el ciclo solar diario y bajo cualquier condición de iluminación. Esto maximiza los rangos de los ángulos de iluminación y también de la fracción difusa de la irradiancia. Esta variabilidad de condiciones de iluminación, combinada con una variación de los ángulos de observación permite obtener la información necesaria para caracterizar las respuestas direccionales de la cubierta observada. Algunos sistemas automáticos multi-angulares ya han sido empleados para realizar esta caracterización mediante la estimación de la Función de Distribución de Reflectividad Bidireccional (BRDF) en ecosistemas homogéneos. Sin embargo, esto no se ha conseguido aún en áreas heterogéneas, como es el caso de los ecosistemas tree-grass o de sabana. Así mismo, los trabajos previos no han considerado los efectos de la radiación difusa en el estudio del BRDF. En el capítulo 4 proponemos una metodología que permite desmezclar y caracterizar simultáneamente la función de distribución de reflectividad hemisférica-direccional de las dos cubiertas de vegetación presentes en el ecosistema, pasto y arbolado. También se analizan los efectos de las diferentes características del método. Finalmente, los resultados se escalan y se comparan con productos globales de satélite como el producto BRDF de MODIS. La conclusión obtenida es que se requieren más esfuerzos en el desarrollo y caracterización de sensores hiperespectrales instalados en sistemas automáticos de campo. Estos sistemas deberían adoptar configuraciones multi-angulares de modo que puedan caracterizarse las respuestas direccionales. Para ello, será necesario considerar los efectos de la radiación difusa; y en algunos casos también la heterogeneidad de la escena

Mid-infrared photothermal hyperspectral imaging of biomolecular systems

Thesis (Ph.D.)--Boston UniversityThe development of novel techniques in spectroscopy and microscopy that are label-free, contactless and accessible is useful among many scientific disciplines, ranging from Materials Science to Biomedical Engineering. Hyperspectral photothermal imaging using vibrational spectroscopy promises to be a new tool in the arsenal for analysis and characterization of materials. This technique can be used for understanding structural composition of a material that is advantageous to the materials scientist. A combination of microscopy and spectroscopy is also beneficial to the biologist or pathologist that analyzes a complex sample with rich morphology. Photothermal hyperspectral microscopy is a label-free nondestructive method that utilizes specific vibrational bands of a molecule giving spectral information to an image. The method is based on changes in the thermal state, and the associated change in the refractive index of the sample as it is irradiated with mid-infrared light. Photothermal microscopy has rapidly emerged as one of the most sensitive label-free optical spectroscopic methods, rivaling current well-established methods based on fluorescence. The method has been used to image single non-fluorescent molecules in room temperature and to directly characterize biological features such as mitochondria and red blood cells. Despite great breakthroughs in the visible regime, the method has not been explored in the mid-infrared regime where most of the biological molecules have characteristic vibrational modes that constitute an intrinsic molecular "fingerprint" . This thesis presents the development of a new technique to measure the linear and nonlinear mid-infrared photothermal response induced by tunable high power lasers such as Quantum Cascade Lasers (QCLs). Photothermal response can be measured in pump-probe heterodyne detection, using short wavelength visible lasers and compact fiber lasers as a probe. This allows for direct detection of the fingerprint mid-infrared vibrational modes through ultrasensitive photodetectors. Integrated into a mid-infrared microscope, the system facilitates the acquisition of spectra and images on condensed phase samples. Photothermal heterodyne mid-infrared hyperspectral vibrational technique is used to image biological samples such as bird brain and other biomolecules First photothermal images on specially designed plasmonic metamaterials, designed to either enhance or suppress a selected mid-infrared vibrational normal mode, are demonstrated. Plasmonic metamaterials can be engineered using electron beam lithography for functional studies on biomolecules enhancing selected vibrational infrared resonances. This study takes advantage of the strong interaction between light and matter and investigates properties of the material that are difficult to detect through conventional spectroscopic methods. The new technique has the ability to advance studies in many fields, as it is applicable to different types of materials, non-destructive, accessible and inexpensive

Journal of South Carolina Water Resources Volume 4, Issue 1

For the better part of 2017, South Carolina saw an improvement in drought status for many of the state’s 55 counties, with the SC Drought Response Committee reporting 28 of those in ‘incipient’ (first stage of drought) status and the remaining 17 in ‘normal’ status on November 27. With regard to major rain events, Tropical Storm Irma brought noteworthy levels of rainfall to much of the state in mid-September, as well as coastal flooding. Because of the ongoing significant weather events that continue to threaten water resources and related infrastructure, Clemson’s SC Water Resources Center held its first Summit Series event entitled “Back to the Future of Drought” in April to begin bringing statewide water professionals together for issue specific forums during the ‘off ’ years of the biennial SC Water Resources Conference (SCWRC). The presentations and discussions during the summit fostered new collaborations and shortly after, the SC State Climatology Office took the lead in coordinating a Drought and Water Shortage Tabletop Exercise in September at the SC Emergency Operations Center, drawing 80 participants from across the state. Included in this issue of the journal is a short communication paper about the exercise. Continuing to build on the benefits of statewide networking and collaboration, the SC State Climatology Office has also developed a 2017-18 Climate Connection Workshop series in collaboration with the Carolinas Integrated Sciences and Assessments (CISA) and the Clemson SC Water Resources Center. The first workshop was held in Greenville in December, and workshops are to be scheduled in Columbia and Charleston in early 2018. In addition, SCDNR in partnership with SCDHEC, USGS, Clemson SC Water Resources Center and USACE, held stakeholder meetings during the fall focused on the state’s groundwater assessment. Events such as these, are filling the growing need to initiate collaborative efforts to positively impact water resources management, which in turn continue to grow the network of outreach

Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers

Growing interest in the proximal sensing of sun‐induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 “Innovative optical tools for proximal sensing of ecophysiological processes” (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiometers. We developed a sensor simulator capable of reproducing biases and noises usually found in field spectroradiometers. First the sensor simulator was calibrated and characterized using synthetic datasets of known uncertainties defined from laboratory measurements and literature. Secondly, we used the sensor simulator and the characterized sensor models to simulate the acquisition of atmospheric and vegetation radiances from a synthetic dataset. Each of the sensor models predicted biases with propagated uncertainties that modified the simulated measurements as a function of different factors. Finally, the impact of each sensor model on SIF retrieval was analyzed. Results show that SIF retrieval can be significantly affected in situations where reflectance factors are barely modified. SIF errors were found to correlate with drivers of instrumental-induced biases which are as also drivers of plant physiology. This jeopardizes not only the retrieval of SIF, but also the understanding of its relationship with vegetation function, the study of diel and seasonal cycles and the validation of remote sensing SIF products. Further work is needed to determine the optimal requirements in terms of sensor design, characterization and signal correction for SIF retrieval by proximal sensing. In addition, evaluation/validation methods to characterize and correct instrumental responses should be developed and used to test sensors performance in operational conditions

Exploring the Possibilities: Earth and Space Science Missions in the Context of Exploration

According to Dr. Edward J. Weiler, Director of the Goddard Space Flight Center, "Exploration without science is tourism". At the American Astronautical Society's 43rd Annual Robert H. Goddard Memorial Symposium it was quite apparent to all that NASA's current Exploration Initiative is tightly coupled to multiple scientific initiatives: exploration will enable new science and science will enable exploration. NASA's Science Mission Directorate plans to develop priority science missions that deliver science that is vital, compelling and urgent. This paper will discuss the theme of the Goddard Memorial Symposium that science plays a key role in exploration. It will summarize the key scientific questions and some of the space and Earth science missions proposed to answer them, including the Mars and Lunar Exploration Programs, the Beyond Einstein and Navigator Programs, and the Earth-Sun System missions. It will also discuss some of the key technologies that will enable these missions, including the latest in instruments and sensors, large space optical system technologies and optical communications, and briefly discuss developments and achievements since the Symposium. Throughout history, humans have made the biggest scientific discoveries by visiting unknown territories; by going to the Moon and other planets and by seeking out habitable words, NASA is continuing humanity's quest for scientific knowledge

Remote Sensing

This dual conception of remote sensing brought us to the idea of preparing two different books; in addition to the first book which displays recent advances in remote sensing applications, this book is devoted to new techniques for data processing, sensors and platforms. We do not intend this book to cover all aspects of remote sensing techniques and platforms, since it would be an impossible task for a single volume. Instead, we have collected a number of high-quality, original and representative contributions in those areas

Sun-induced chlorophyll fluorescence I:Instrumental considerations for proximal spectroradiometers

Growing interest in the proximal sensing of sun-induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 “Innovative optical tools for proximal sensing of ecophysiological processes„ (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiometers. We developed a sensor simulator capable of reproducing biases and noises usually found in field spectroradiometers. First the sensor simulator was calibrated and characterized using synthetic datasets of known uncertainties defined from laboratory measurements and literature. Secondly, we used the sensor simulator and the characterized sensor models to simulate the acquisition of atmospheric and vegetation radiances from a synthetic dataset. Each of the sensor models predicted biases with propagated uncertainties that modified the simulated measurements as a function of different factors. Finally, the impact of each sensor model on SIF retrieval was analyzed. Results show that SIF retrieval can be significantly affected in situations where reflectance factors are barely modified. SIF errors were found to correlate with drivers of instrumental-induced biases which are as also drivers of plant physiology. This jeopardizes not only the retrieval of SIF, but also the understanding of its relationship with vegetation function, the study of diel and seasonal cycles and the validation of remote sensing SIF products. Further work is needed to determine the optimal requirements in terms of sensor design, characterization and signal correction for SIF retrieval by proximal sensing. In addition, evaluation/validation methods to characterize and correct instrumental responses should be developed and used to test sensors performance in operational conditions

Solar System Remote Sensing : September 20-21, 2002, Pittsburgh, Pennsylvania

This international meeting presents the current state of research over a wide range of topics including:; Photometric theory; Spectroscopic modeling; Laboratory exploration of scattering phenomena; Space weathering processes throughout the inner solar system; Photometric and spectroscopic studies of the Moon, Mars, Mercury, and asteroids; Photometric and spectroscopic studies of cold, icy places such as comets and outer planet satellites.This international meeting presents the current state of research over a wide range of topics including:; Photometric theory; Spectroscopic modeling; Laboratory exploration of scattering phenomena; Space weathering processes throughout the inner solar system; Photometric and spectroscopic studies of the Moon, Mars, Mercury, and asteroids; Photometric and spectroscopic studies of cold, icy places such as comets and outer planet satellites.sponsors, University of Pittsburgh ... [and others]conveners, William Cassidy, Deborah Domingue, Robert M. Nelson ; scientific organizing committee William Cassidy ... [and others].PARTIAL CONTENTS: Interpreting Photometry of Planetary Regoliths: Progress and Problems as Seen from Kharkov / Yu.G. Shkuratov--Toward an Improved Single-Particle Model for Large, Irregular Grains / W.M. Grundy, B. Schmitt, S. Doute--A New Method for Estimating the Single Scattering Phase Functions of Regolith Grains / P. Helfenstein--The Opposition Effect: A Very Unusual Case / R.M. Nelson--Coherent Backscattering by Random Particulate Media in the Solar System / K. Muinonen--The Diverse Surface Compositions of the Galilean Satellites / R.W. Carlso