Evaluation of spatial, radiometric and spectral Thematic Mapper performance for coastal studies

On 31 March 1983, the University of Delaware's Center for Remote Sensing initiated a study to evaluate the spatial, radiometric and spectral performance of the LANDSAT Thematic Mapper for coastal and estuarine studies. The investigation was supported by Contract NAS5-27580 from the NASA Goddard Space Flight Center. The research was divided into three major subprojects: (1) a comparison of LANDSAT TM to MSS imagery for detecting submerged aquatic vegetation in Chesapeake Bay; (2) remote sensing of submerged aquatic vegetation - a radiative transfer approach; and (3) remote sensing of coastal wetland biomass using Thematic Mapper wavebands

Remote sensing of optically shallow, vertically inhomogeneous waters: A mathematical model

A multiple-layer radiative transfer model of a vertically inhomogeneous, optically shallow water mass is briefly described. This model is directed toward use in remote sensing properties. Some preliminary results and qualitative predictions are presented

Three-dimensional flushing times of the Persian Gulf

2000 FLORIDA AVE NW, WASHINGTON, USA, DC, 2000

South Park: A Public Service Announcement

Each South Park episode leads viewers through a series of outrageous circumstances that culminate in an interesting and oftentimes profound conclusion. Whether Parker and Stone simply give Al Gore a little shove off of his high horse or make a bold statement about an important social issue such as whether or not we as humans should play God, they inevitably have something of consequence to say regarding a current social issue, and millions of viewers tune in every week to find out what it is. William Ackleson is currently an Engineering major from McLean, Virginia in his Freshman year at JMU. In his free time, he enjoys playing Xbox, going to the Urec, and working with his engineering team. In the future, he intends to apply his skills in engineering to the veterinary sciences. He also has no idea how he got on e-Vision as an Engineering major. Liam chose to write about South Park because it was an opportunity to apply one of his interests in an evaluative way. He also appreciates South Park\u27s message of skepticism and willingness to make your own decisions instead of being told what to think

Identidades, fronteras, órdenes: Navegando por el laberinto posterior al 11 de Septiembre

En abril de 2004, siete terroristas islamistas decidieron inmolarse a sí mismos en un edificio residencial de la localidad madrileña de Leganés, al percatarse de que estaban siendo vigilados por unidades especiales de la policía española. Pusieron fin a sus vidas haciendo estallar una gran cantidad de explosivos, que tenían acumulados en el inmueble con el fin de llevar a cabo diversos atentados por las proximidades. Gracias a que los vecinos fueron evacuados a tiempo, el incidente no ocasionó una masacre, como deseaban los propios terroristas. Sin embargo, como resultado de la detonación falleció un miembro de las agencias estatales de seguridad que se disponían a asaltar el inmueble y detenerlos. Unos días antes, concretamente el once de marzo, esa misma partida de fundamentalistas islámicos había ocasionado la muerte a cerca de doscientas personas, mediante una serie concatenada de atentados perpetrados en trenes de cercanías a horas de máxima concurrencia. El más grave incidente terrorista conocido en España y la primera vez que la actual red global del terrorismo islamista conseguía atentar en Europa. Entonces no se suicidaron sencillamente porque su prevista campaña de violencia indiscriminada no terminaba ahí

Narrating identity and territoriality: The cases of the U.S.-Mexico and U.S.-Canada borderlands.

Analysing the processes and relationships of political territoriality and collective identity in the American borderlands, this thesis examines the narrative and material dimensions of policies increasingly favouring securitised border 'control'. This 'reterritorialisation' contrasts markedly with concurrent moves to increase economic integration under the North American Free Trade Agreement and with long patterns of transnational socio-cultural interaction, emblematic of larger relational, transnational 'mobilities' fostered by globalisation. Through a historical and transdisciplinary survey, borders are examined as representations and socio-political constructs: a unique, contingent, political cartography connected to a precise, early modern notion of space and identity. Borders are in a continual process of being reproduced through both material means and supportive state-produced 'texts' or narratives. The analysis is part of a larger project in International Relations: the development of the 'identities/borders/orders' heuristic triad, designed to narrow and produce new theoretical and empirical insights by coupling three key concepts and exploring the co-constitutive relationships. Focussing on the identity-border link within the triad, the first case study analyses 'Operation Hold the Line' and related events in the securitisation of the southern borderlands against undocumented migration. The second case study provides an account of major official documentation and public debate framing current developments on the northern border, including a reading of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996. Border policy is understood as an example of reflexive territoriality, suggesting continual, ever speedier revision, monitoring, and reproduction of a state's constructed strategy responding to control defined 'risks', such as migration. These regulations are fed and actualised by new information flows and technologies, as the state's attempt to 'control' its borders by making them political realities of difference with particular material and normative outcomes. Here, the politics of representation involves an image of border 'security' which effects the socio-spatialisation of collective identity, specifically the reinforcement of difference and a secure nationalism narrative. The securitisation also reflects a modern understanding of knowledge as regulation and order

An Overview of Approaches and Challenges for Retrieving Marine Inherent Optical Properties from Ocean Color Remote Sensing

Ocean color measured from satellites provides daily global, synoptic views of spectral water-leaving reflectances that can be used to generate estimates of marine inherent optical properties (IOPs). These reflectances, namely the ratio of spectral upwelled radiances to spectral downwelled irradiances, describe the light exiting a water mass that defines its color. IOPs are the spectral absorption and scattering characteristics of ocean water and its dissolved and particulate constituents. Because of their dependence on the concentration and composition of marine constituents, IOPs can be used to describe the contents of the upper ocean mixed layer. This information is critical to further our scientific understanding of biogeochemical oceanic processes, such as organic carbon production and export, phytoplankton dynamics, and responses to climatic disturbances. Given their importance, the international ocean color community has invested significant effort in improving the quality of satellite-derived IOP products, both regionally and globally. Recognizing the current influx of data products into the community and the need to improve current algorithms in anticipation of new satellite instruments (e.g., the global, hyperspectral spectroradiometer of the NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission), we present a synopsis of the current state of the art in the retrieval of these core optical properties. Contemporary approaches for obtaining IOPs from satellite ocean color are reviewed and, for clarity, separated based their inversion methodology or the type of IOPs sought. Summaries of known uncertainties associated with each approach are provided, as well as common performance metrics used to evaluate them. We discuss current knowledge gaps and make recommendations for future investment for upcoming missions whose instrument characteristics diverge sufficiently from heritage and existing sensors to warrant reassessing current approaches

Satellite sensor requirements for monitoring essential biodiversity variables of coastal ecosystems.

The biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a small fraction of these areas. Satellite-based sensors can repeatedly record the visible and near-infrared reflectance spectra that contain the absorption, scattering, and fluorescence signatures of functional phytoplankton groups, colored dissolved matter, and particulate matter near the surface ocean, and of biologically structured habitats (floating and emergent vegetation, benthic habitats like coral, seagrass, and algae). These measures can be incorporated into Essential Biodiversity Variables (EBVs), including the distribution, abundance, and traits of groups of species populations, and used to evaluate habitat fragmentation. However, current and planned satellites are not designed to observe the EBVs that change rapidly with extreme tides, salinity, temperatures, storms, pollution, or physical habitat destruction over scales relevant to human activity. Making these observations requires a new generation of satellite sensors able to sample with these combined characteristics: (1) spatial resolution on the order of 30 to 100-m pixels or smaller; (2) spectral resolution on the order of 5 nm in the visible and 10 nm in the short-wave infrared spectrum (or at least two or more bands at 1,030, 1,240, 1,630, 2,125, and/or 2,260 nm) for atmospheric correction and aquatic and vegetation assessments; (3) radiometric quality with signal to noise ratios (SNR) above 800 (relative to signal levels typical of the open ocean), 14-bit digitization, absolute radiometric calibration <2%, relative calibration of 0.2%, polarization sensitivity <1%, high radiometric stability and linearity, and operations designed to minimize sunglint; and (4) temporal resolution of hours to days. We refer to these combined specifications as H4 imaging. Enabling H4 imaging is vital for the conservation and management of global biodiversity and ecosystem services, including food provisioning and water security. An agile satellite in a 3-d repeat low-Earth orbit could sample 30-km swath images of several hundred coastal habitats daily. Nine H4 satellites would provide weekly coverage of global coastal zones. Such satellite constellations are now feasible and are used in various applications

Reflectancias de imágenes multiespectrales de SPOT asociadas a la turbidez en el Alto Golfo de California

[EN] The use of satellite images for the observation and measurement of marine turbidity has been developed mainly with ocean colour sensors, such as MODIS. These images have a maximum spatial resolution of 250 m in their visible and infrared bands. In this research, images of the SPOT sensors were chosen as an alternative to overcome this limited spatial resolution. The objective was to prove the suitability of SPOT to measure turbidity in areas with great spatial variability. As a first step, all the images were standardized and the SPOT wavelength that had the largest association in the Principal Component Analysis was chosen (PCA). The results show that the bands of a SPOT multispectral image are highly redundant. The wavelength of the 610-680 nm (S2610-680) obtained the best association in 89% of the 73 images analysed. The SPOT reflectance (Rrs) (S2610-680) was compared with MODIS 620-670 nm (M1620-670), which has already been tested in other research and has proved to be adequate for measuring turbidity. Both sensors performance was similar for low and moderate reflectance but for high reflectance, SPOT (S2610-680) had a better performance than MODIS (M1620-670). Additionally, the SPOT Rrs (S2610-680) was associated with standardized Secchi disk depth data, which were measured in situ, to check SPOT suitability. SPOT Rrs (S2610-680)images were classified into: 1) cold or warm season, 2) spring tide or neap tide and 3) water flux or reflux. These constructed scenarios allowed to see the result of the Standardized Space Anomalies, which showed the continuous presence of low and medium values in the most oceanic region of the Upper Gulf of California (UGC) and very high values in all the scenarios in the intertidal zone. This research has shown that SPOT Rrs (S2610-680) is useful for observing, differentiating and measuring turbidity patterns in areas with very high spatial variability.[ES] El uso de imágenes de satélite para la observación y medida de la turbidez marina se ha desarrollado principalmente con sensores de color del océano como MODIS. Estas imágenes tienen una resolución espacial máxima de 250 m en las bandas visible e infrarroja. En esta investigación, se eligieron imágenes del sensor SPOT como alternativa para superar esta limitada resolución espacial. El objetivo es probar la validez de SPOT para medir turbidez en áreas con gran variabilidad espacial. Como primer paso se normalizaron todas las imágenes y se eligió la longitud de onda de SPOT que mejor ajuste obtuvo a partir del Análisis de Componentes Principales (ACP). Los resultados mostraron que las bandas de una imagen multiespectral SPOT tienen una alta redundancia (buena correlación) entre sí. La longitud de onda de los 610-680 nm (S2610-680) fue la que obtuvo el mejor ajuste en 89% de las 73 imágenes analizadas. Esta reflectancia (Rrs) (S2610-680) de SPOT fue comparada con MODIS (M1620-670). El comportamiento de ambos sensores fue similar para reflectancias bajas y medias, pero para altas reflectancias SPOT Rrs (S2610-680) tuvo un mejor rendimiento que MODIS. Además, la Rrs (S2610-680) de SPOT fue asociada con datos in situ normalizados de profundidad del disco de Secchi para comprobar la idoneidad del sensor SPOT. Las imágenes Rrs (S2610-680) de SPOT fueron clasificadas en: 1) época fría o cálida, 2) marea viva o muerta, y 3) flujo o reflujo de las aguas. Estos escenarios seleccionados permitieron ver el resultado de las Anomalías Espaciales Normalizadas, que dejaron ver la continua presencia de valores bajos y medios en la región más oceánica del Alto Golfo de California (AGC) y valores muy altos en todos los escenarios en la zona intermareal del AGC. El trabajo realizado permite concluir que la reflectancia Rrs (S2610-680) de SPOT es válida para observar, diferenciar y medir patrones de turbidez en áreas con una elevada variabilidad espacial.Aguilar-Maldonado, JA.; Santamaría-Del-Ángel, E.; Sebastiá-Frasquet, MT. (2017). Reflectances of SPOT multispectral images associated with the turbidity of the Upper Gulf of California. Revista de Teledetección. (50):1-16. doi:10.4995/raet.2017.7795SWORD1165

Living up to the hype of hyperspectral aquatic remote sensing: science, resources and outlook

Intensifying pressure on global aquatic resources and services due to population growth and climate change is inspiring new surveying technologies to provide science-based information in support of management and policy strategies. One area of rapid development is hyperspectral remote sensing: imaging across the full spectrum of visible and infrared light. Hyperspectral imagery contains more environmentally meaningful information than panchromatic or multispectral imagery and is poised to provide new applications relevant to society, including assessments of aquatic biodiversity, habitats, water quality, and natural and anthropogenic hazards. To aid in these advances, we provide resources relevant to hyperspectral remote sensing in terms of providing the latest reviews, databases, and software available for practitioners in the field. We highlight recent advances in sensor design, modes of deployment, and image analysis techniques that are becoming more widely available to environmental researchers and resource managers alike. Systems recently deployed on space- and airborne platforms are presented, as well as future missions and advances in unoccupied aerial systems (UAS) and autonomous in-water survey methods. These systems will greatly enhance the ability to collect interdisciplinary observations on-demand and in previously inaccessible environments. Looking forward, advances in sensor miniaturization are discussed alongside the incorporation of citizen science, moving toward open and FAIR (findable, accessible, interoperable, and reusable) data. Advances in machine learning and cloud computing allow for exploitation of the full electromagnetic spectrum, and better bridging across the larger scientific community that also includes biogeochemical modelers and climate scientists. These advances will place sophisticated remote sensing capabilities into the hands of individual users and provide on-demand imagery tailored to research and management requirements, as well as provide critical input to marine and climate forecasting systems. The next decade of hyperspectral aquatic remote sensing is on the cusp of revolutionizing the way we assess and monitor aquatic environments and detect changes relevant to global communities