Ocean Remote Sensing with Synthetic Aperture Radar

The ocean covers approximately 71% of the Earth’s surface, 90% of the biosphere and contains 97% of Earth’s water. The Synthetic Aperture Radar (SAR) can image the ocean surface in all weather conditions and day or night. SAR remote sensing on ocean and coastal monitoring has become a research hotspot in geoscience and remote sensing. This book—Progress in SAR Oceanography—provides an update of the current state of the science on ocean remote sensing with SAR. Overall, the book presents a variety of marine applications, such as, oceanic surface and internal waves, wind, bathymetry, oil spill, coastline and intertidal zone classification, ship and other man-made objects’ detection, as well as remotely sensed data assimilation. The book is aimed at a wide audience, ranging from graduate students, university teachers and working scientists to policy makers and managers. Efforts have been made to highlight general principles as well as the state-of-the-art technologies in the field of SAR Oceanography

Developing a remote sensing system based on X-band radar technology for coastal morphodynamics study

New data processing techniques are proposed for the assessment of scopes and limitations from radar-derived sea state parameters, coastline evolution and water depth estimates. Most of the raised research is focused on Colombian Caribbean coast and the Western Mediterranean Sea. First, a novel procedure to mitigate shadowing in radar images is proposed. The method compensates distortions introduced by the radar acquisition process and the power decay of the radar signal along range applying image enhancement techniques through a couple of pre-processing steps based on filtering and interpolation. Results reveal that the proposed methodology reproduces with high accuracy the sea state parameters in nearshore areas. The improvement resulting from the proposed method is assessed in a coral reef barrier, introducing a completely novel use for X-Band radar in coastal environments. So far, wave energy dissipation on a coral reef barrier has been studied by a few in-situ sensors placed in a straight line, perpendicular to the coastline, but never been described using marine radars. In this context, marine radar images are used to describe prominent features of coral reefs, including the delineation of reef morphological structure, wave energy dissipation and wave transformation processes in the lagoon of San Andres Island barrier-reef system. Results show that reef attenuates incident waves by approximately 75% due to both frictional and wave breaking dissipation, with an equivalent bottom roughness of 0.20 m and a wave friction factor of 0.18. These parameters are comparable with estimates reported in other shallow coral reef lagoons as well as at meadow canopies, obtained using in-situ measurements of wave parameters.DoctoradoDoctor en Ingeniería Eléctrica y Electrónic

Propagation modeling for the analysis of radar systems.

It is well understood in the defence procurement industry that there is a shortfall in the understanding of military mobile radar system performance in complex meteorological environments. To meet this challenge, the work presented in this thesis has combined advanced radar propagation methods with a novel clutter modelling algorithm to describe system performance at the level needed to meet modern naval requirements. The need for these new methods is demonstrated by sets of data gathered in anomalous propagation (anaprop) environments by the author. A new flexible radar model created during this project has allowed the author to analyse the radar data taken and to explore the benefits of performance modelling of radar systems in complex littoral and anaprop environments. A prototype system that exploits the model to try to estimate the local conditions has also been developed. Tests on this technology demonstrator have indicated that more advanced applications of these techniques could allow future radar systems to sense their local environment to improve tactical awareness and enhance sensor optimisation

THE USE OF MARINE RADAR FOR INTERTIDAL AREA SURVEY AND MONITORING COASTAL MORPHOLOGICAL CHANGE

Surveying and monitoring the dynamic morphology of intertidal areas is a logistically challenging and expensive task, due to their large area and complications associated with access. This thesis describes a contribution to the nearshore survey industry; an innovative methodology is developed and subsequently applied to marine radar image data in order to map topography within the intertidal area. This new method of intertidal topographical mapping has a reasonable spatial resolution (5 m) and operates over a large radial range (~4 km) with the required temporal resolution to observe both event-based and long-term morphological change (currently bi-weekly surveys). This study uses nearly three years of radar image data collected during 2006-2009 from an installation on Hilbre Island at the mouth of the Dee estuary, northwest UK. The development of the novel 'radar waterline method' builds on previous waterline techniques and improves upon them by moving the analysis from the spatial to the temporal domain, making the analysis extremely robust and more resilient to poor quality image data. Results from radar topographical surveys are compared to those of a LiDAR survey during October 2006. The differences compare favourably across large areas of the intertidal zone, within the first kilometre 97% of radar-derived elevations lie within 1 m of LiDAR estimations. Concentrations of poor estimations are seen in areas that are shown to be shadowed from the radar antenna or suffering from pooling water during the ebb tide. The full three-year dataset is used to analyse changing intertidal morphology over that time period using radar-derived surveys generated every two weeks. These surveys are used to perform an analysis of changing sediment volume and mean elevation, giving an indication of beach 'health' and revealing a seasonal trend of erosion and accretion at several sites across the Dee estuary. The ability of the developed technique to resolve morphological changes resulting from storm events is demonstrated and a quantification of that impact is provided. The application of the technique to long-range (7.5 km) marine radar data is demonstrated in an attempt to test the spatial and operational limitations of this new method. The development of a mobile radar survey platform, the Rapidar allows remote areas to be surveyed and provides a platform for potential integration with other survey instruments. A description of the potential application to coastal management and monitoring is presented. Areas of further work intended to improve vertical elevation accuracy and robustness are proposed. This contribution provides a useful tool for coastal scientists, engineers and decision-makers interested in the management of coastal areas that will form part of integrated coastal management and monitoring operations. This method presents several key advantages over traditional survey techniques including; the large area of operation and temporal resolution of repeat surveys, it is limited primarily by topographical shadowing and low wind conditions limiting data collection

Technical approaches, chapter 3, part E

Radar altimeters, scatterometers, and imaging radar are described in terms of their functions, future developments, constraints, and applications

Earth Resources: A continuing bibliography with indexes, issue 33

This bibliography list 436 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution sytems, instrumentation and sensors, and economic analysis

Itämeren planktivorien pedonvälttämiskäyttäytyminen

Predation is an important source of mortality for most aquatic animals. Thus, the ability to avoid being eaten brings substantial fitness benefits to individuals. Predator detection abilities and antipredator behaviour were examined in various planktivores, i.e. the littoral mysids Neomysis integer and Praunus flexuosus, three-spined stickleback Gasterosteus aculeatus larvae, pelagic mysids Mysis mixta and M. relicta, and the predatory cladoceran Cercopagis pengoi, with cues from their respective predators European perch Perca fluviatilis and Baltic herring Clupea harengus membras. The use of different aquatic macrophytes as predation refuges by the littoral planktivores was also examined. All pelagic planktivores and stickleback larvae were able to detect the presence of their predator by chemical cues alone. The littoral mysids N. integer and P. flexuosus responded only when chemical and visual predator cues were combined. The responses of stickleback larvae were stronger to the combined cues than the chemical cue alone. A common antipredator behaviour in all of the planktivores studied was decreased ingestion rate in response to predator cues. N. integer and stickleback larvae also decreased their swimming activity. Pelagic mysids and C. pengoi altered their prey selectivity patterns in response to predator cues. The effects of predator cues on the swarming behaviour of N. integer were examined. Swarming brings clear antipredator advantages to N. integer, since when they feed in a swarm, they do not significantly decrease their feeding rate. However, the swarming behaviour of N. integer was not affected by predation risk, but was instead a fixed strategy. Despite the presence or absence of predator cues, N. integer individuals attempted to associate with a swarm and preferred larger to smaller swarms. In studies with aquatic macrophytes, stickleback larvae and P. flexuosus utilized vegetation as a predation refuge, spending more time within vegetation when under predation threat. The two macroalgal species studied, bladderwrack Fucus vesiculosus and stonewort Chara tomentosa, were preferred by P. flexuosus, whereas Eurasian watermilfoil Myriophyllum spicatum was strongly avoided by N. integer and stickleback larvae. In fact, when in dense patches in aquaria, M. spicatum caused acute and high mortality (> 70%) in littoral mysids, but not in sticklebacks, whereas C. tomentosa and northern watermilfoil M. sibiricum did not. In contrast, only 2-4% mortality in N. integer was observed with intact and broken stems of M. spicatum in field experiments. The distribution of littoral mysids in different vegetations, however, suggests that N. integer avoids areas vegetated by M. spicatum.Eveliina Lindén väittelee tohtoriksi 4.8. 2006 Dynamicumin (Erik Palménin aukio 1) luentosali Aurassa. Hänen väitöskirjassaan tarkastellaan sekä ulapan että rantavyöhykkeen planktonia syöviä eläimiä: mysidiäyriäisiä, kalanpoikasia sekä petovesikirppua (Cercopagis pengoi), ja miten ne käyttäytyvät niitä saalistavien kalojen, ahvenen ja silakan, läsnä ollessa. Planktivorit (mm. mysidiäyriäiset, kalanpoikaset, petovesikirppu) kykenevät havaitsemaan niihin kohdistuvan saalistusuhan ja muuttamaan käytöstään vähentääkseen syödyksi joutumisen riskiä. Kaikilla edellä mainituille lajeilla on samanlainen käyttäytymisvaste pedon läsnä ollessa, ne vähentävät omaa syöntiaktiivisuuttaan. Tällöin todennäköisyys kohdata saalistaja ja myös tulla havaituksi vähenee. Lisäksi ne pystyvät olemaan valppaampia saalistajien varalta. Rantavyöhykkeen mysidiäyriäinen Neomysis integer sekä kolmipiikin poikaset vähentävät myös uintiaktiivisuuttaan havaitessaan saalistajan läsnäolon. N. integer myös muodostaa parvia, mikä tuo monenlaisia etuja välttää saalistusta. Syöntiaktiivisuuden vähentämisen lisäksi ulapan mysidiäyriäiset Mysis mixta ja M. relicta sekä petovesikirppu valikoivat ravintokohteensa eri tavalla saalistusuhan alla. Kolmipiikin poikaset sekä toinen rantavyöhykkeen mysidiäyriäinen Praunus flexuosus puolestaan piilottelevat vesikasvillisuudessa, jolloin saalistajan on vaikeampi havaita ja tavoittaa niitä. Vesikasvilajien välillä on kuitenkin suuria eroja niiden soveltuvuudessa piilopaikaksi. Tähkä-ärviä (Myriophyllum spicatum) on laboratorio-oloissa jopa tappavan myrkyllinen rantavyöhykkeen mysidiäyriäisille ja ne välttävät sitä luonnossakin. Tähkä-ärviä hyötyy rehevöitymisestä ja on leviämässä yhä laajemmille alueille saaristossa. Sen sijaan piilopaikkoina suositut makrolevälajit, kuten rakkolevä (Fucus vesiculosus) ja punanäkinpartainen (Chara tomentosa), ovat taas monin paikoin vähenemässä tai jopa kokonaan hävinneet. Kullakin planktivorilajilla on oma tapansa välttää saaliiksi joutumista. Itämeren ympäristömuutoksilla saattaa olla vaikutusta myös planktivorien ja petokalojen välisiin saalistussuhteisiin

Statistical Analysis of Coherent Monostatic and Bistatic Radar Sea Clutter

Radar sea clutter analysis has been an important area of radar research for many years. Very limited research has been carried out on coherent monostatic sea clutter analysis and even less on bistatic sea clutter. This has left a significant gap in the global scientific knowledge within this area. This thesis describes research carried out to analyse, quantify and model coherent sea clutter statistics from multiple radar sources. The ultimate goal of the research is to improve maritime radars' ability to compensate for clutter and achieve effective detection of targets on or over the sea surface. The first analyses used monostatic data gathered during the fight trials of the Thales Searchwater 2000 AEW radar. A further sea clutter trials database from CSIR was then used to investigate the variation of clutter statistics with look angle and grazing angle. Finally simultaneous monostatic and bistatic sea clutter data recorded in South Africa using the S-band UCL radar system NetRAD were analysed. No simultaneous monostatic and bistatic coherent analysis has ever been reported before in the open literature. The datasets recorded included multiple bistatic angles at both horizontal and vertical polarisations. Throughout the analysis real data have been compared to accepted theoretic models of sea clutter. An additional metric of comparison was investigated relating to the area of information theoretic techniques. Information theory is a significant subject area, and some concepts from it have been applied in this research. In summary this research has produced quantifiable and novel results on the characteristics of sea clutter statistics as a function of Doppler. Analysis has been carried out on a wide range of monostatic and bistatic data. The results of this research will be extremely valuable in developing sea clutter suppression algorithms and thus improving detection performance in future maritime radar designs

Predicting and auralizing acoustics in classrooms

Although classrooms have fairly simple geometries, this type of room is known to cause problems when trying to predict their acoustics using room acoustics computer modeling. Some typical features from a room acoustics point of view are: Parallel walls, low ceilings (the rooms are flat), uneven distribution of absorption, and most of the floor being covered with furniture which at long distances act as scattering elements, and at short distance provide strong specular components. The importance of diffraction and scattering is illustrated in numbers and by means of auralization, using ODEON 8 Beta

COMBAT SYSTEMS Volume 1. Sensor Elements Part I. Sensor Functional Characteristics

This document includes: CHAPTER 1. SIGNATURES, OBSERVABLES, & PROPAGATORS. CHAPTER 2. PROPAGATION OF ELECTROMAGNETIC RADIATION. I. – FUNDAMENTAL EFFECTS. CHAPTER 3. PROPAGATION OF ELECTROMAGNETIC RADIATION. II. – WEATHER EFFECTS. CHAPTER 4. PROPAGATION OF ELECTROMAGNETIC RADIATION. III. – REFRACTIVE EFFECTS. CHAPTER 5. PROPAGATION OF ELECTROMAGNETIC RADIATION IV. – OTHER ATMOSPHERIC AND UNDERWATER EFFECTS. CHAPTER 6. PROPAGATION OF ACOUSTIC RADIATION. CHAPTER 7. NUCLEAR RADIATION: ITS ORIGIN AND PROPAGATION. CHAPTER 8. RADIOMETRY, PHOTOMETRY, & RADIOMETRIC ANALYSIS. CHAPTER 9. SENSOR FUNCTIONS. CHAPTER 10. SEARCH. CHAPTER 11. DETECTION. CHAPTER 12. ESTIMATION. CHAPTER 13. MODULATION AND DEMODULATION. CHAPTER 14. IMAGING AND IMAGE-BASED PERCEPTION. CHAPTER 15. TRACKING. APPENDIX A. UNITS, PHYSICAL CONSTANTS, AND USEFUL CONVERSION FACTORS. APPENDIX B. FINITE DIFFERENCE AND FINITE ELEMENT TECHNIQUES. APPENDIX C. PROBABILITY AND STATISTICS. INDEX TO VOLUME 1. Note by author: Note: Boldface entries in the table of contents are not yet completed