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At least 307 records · Page 17Linked to original sources
USGS2013

Traces in the dark: sedimentary processes and facies gradients in the upper shale member of the Upper Devonian-Lower Mississippian Bakken Formation, Williston Basin, North Dakota, U.S.A.

Black, organic-rich rocks of the upper shale member of the Upper Devonian–Lower Mississippian Bakken Formation, a world-class petroleum source rock in the Williston Basin of the United States and Canada, contain a diverse suite of mudstone lithofacies that were deposited in distinct facies belts. The succession consists of three discrete facies associations (FAs). These comprise: 1) siliceous mudstones; 2) quartz- and carbonate-bearing, laminated mudstones; and 3) macrofossil-debris-bearing massive mudstones. These FAs were deposited in three facies belts that reflect proximal to distal relationships in this mudstone system. The macrofossil-debris-bearing massive mudstones (FA 3) occur in the proximal facies belt and contain erosion surfaces, some with overlying conodont and phosphate–lithoclast lag deposits, mudstones with abundant millimeter-scale siltstone laminae showing irregular lateral thickness changes, and shell debris. In the medial facies belt, quartz- and carbonate-bearing, laminated mudstones dominate, exhibiting sub-millimeter-thick siltstone layers with variable lateral thicknesses and localized mudstone ripples. In the distal siliceous mudstone facies belt, radiolarites, radiolarian-bearing mudstones, and quartz- and carbonate-bearing, laminated mudstones dominate. Overall, total organic carbon (TOC) contents range between about 3 and 10 wt %, with a general proximal to distal decrease in TOC content. Abundant evidence of bioturbation exists in all FAs, and the lithological and TOC variations are paralleled by changes in burrowing style and trace-fossil abundance. While two horizontal traces and two types of fecal strings are recognized in the proximal facies belt, only a single horizontal trace fossil and one type of fecal string characterize mudstones in the distal facies belt. Radiolarites intercalated into the most distal mudstones are devoid of traces and fecal strings. Bedload transport processes, likely caused by storm-induced turbidity currents, were active across all facies belts. Suspended sediment settling from near the ocean surface, however, most likely played a role in the deposition of some of the mudstones, and was probably responsible for deposition of the radiolarites. The distribution pattern of high-TOC sediments in proximal and lower-TOC deposits in some distal facies is interpreted as a function of higher accumulation rates during radiolarian depositional events leading to a decrease in suspension-derived organic carbon in radiolarite laminae. The presence of burrows in all FAs and nearly all facies in the upper Bakken shale member indicates that dysoxic conditions prevailed during its deposition. This study shows that in intracratonic high-TOC mudstone successions such as the upper Bakken shale member bed-load processes most likely dominated sedimentation, and conditions promoted a thriving infaunal benthic community. As such, deposition of the upper Bakken shale member through dynamic processes in an overall dysoxic environment represents an alternative to conventional anoxic depositional models for world-class source rocks.

North Dakota↗
USGS2026

An integrated mudstone facies classification scheme and revised interpretation of the sedimentologic processes driving carbon burial in the Cenomanian–Turonian Greenhorn Formation, Colorado, U.S.A.

Standardizing facies descriptions has proven key to integrating interpretations of depositional processes and environments from sedimentologic observations with geochemistry data for mudstone lithologies. Because of their fine-grained nature, high degree of compaction, and heterogeneous composition, standardizing methods for mudstone descriptions has proven difficult, but it is critical to formulating meaningful interpretations of the processes that govern the accumulation of organic-rich lithologies and their role in both petroleum systems and the global carbon cycle. In this study, we have developed a modified facies classification scheme for mudstone lithologies that incorporates sedimentologic and compositional observation at the hand-sample and thin-section scales with geochemical measurements, including bulk organic and inorganic geochemistry, to characterize these rocks and their variability more completely for improved interpretations of depositional environments during a low-order sea-level transgression. The facies described in this study are of the Cenomanian–Turonian Greenhorn Formation in the USGS #1 Portland Core drilled in Fremont County, Colorado. Strata of the Greenhorn Formation span Oceanic Anoxic Event 2 (OAE-2) and the preceding interval. Lithologies range from organic-rich argillaceous mudstones with varied sedimentary structures to organic-lean, highly bioturbated limestones. Six facies were identified, each differentiated by varied sedimentary structures and geochemical composition. These facies occur in a predictable stratigraphic stacking pattern that represents a low-order sea-level transgression with interpreted depositional environments ranging from terrigenous-dominated pro-delta and muddy continental shelf at the base of the interval to pelagic offshore marine at the top of the Greenhorn Formation. Though the facies are consistent with previous interpretations of depositional environments at this locale in the Cretaceous Western Interior Seaway during the Greenhorn cyclothem, the sedimentary processes governing the accumulation of organic-rich strata that have defined this interval are significantly revised. Variability in the proximity and intensity of bottom currents driven by storms and geostrophic flows were key to the accumulation of each facies, with significant sediment transport occurring even through deposition in the most oxygen-depleted bottom waters. The methodology and interpretations provided here are now being employed to basin-scale predictions of organic enrichment utilizing calibrated petrophysical methods. The approach and results from this study improve understanding of how organic and inorganic carbon was sequestered during perturbations to the global carbon cycle associated with events such as OAE-2.

Colorado↗
USGS2008

Utility of shallow-water ATRIS images in defining biogeologic processes and self-similarity in skeletal scleractinia, Florida reefs

A recently developed remote-sensing instrument acquires high-quality digital photographs in shallow-marine settings within water depths of 15 m. The technology, known as the Along-Track Reef-Imaging System, provides remarkably clear, georeferenced imagery that allows visual interpretation of benthic class (substrates, organisms) for mapping coral reef habitats, as intended. Unforeseen, however, are functions new to the initial technologic purpose: interpr??table evidence for real-time biogeologic processes and for perception of scaled-up skeletal self-similarity of scleractinian microstructure. Florida reef sea trials lacked the grid structure required to map contiguous habitat and submarine topography. Thus, only general observations could be made relative to times and sites of imagery. Degradation of corals was nearly universal; absence of reef fish was profound. However, ???1% of more than 23,600 sea-trial images examined provided visual evidence for local environs and processes. Clarity in many images was so exceptional that small tracks left by organisms traversing fine-grained carbonate sand were visible. Other images revealed a compelling sense, not yet fully understood, of the microscopic wall structure characteristic of scleractinian corals. Conclusions drawn from classifiable images are that demersal marine animals, where imaged, are oblivious to the equipment and that the technology has strong capabilities beyond mapping habitat. Imagery acquired along predetermined transects that cross a variety of geomorphic features within depth limits will ( 1) facilitate construction of accurate contour maps of habitat and bathymetry without need for ground-truthing, (2) contain a strong geologic component of interpreted real-time processes as they relate to imaged topography and regional geomorphology, and (3) allow cost-effective monitoring of regional- and local-scale changes in an ecosystem by use of existing-image global-positioning system coordinates to re-image areas. Details revealed in the modern setting have taphonomic implications for what is often found in the geologic record.

Conference Paper↗
USGS1946

Sedimentary and volcanic processes in the formation of high alumina clay

In the West, where volcanic materials are abundantly distributed among the rocks of the geologic column, the importance of sedimentary processes in the formation of high-alumina clays has not been fully appreciated. At Ione, Calif., Castle Rock, Wash., Whiteware, Mont., Hobart Butte and Mollala, Oreg., where the Geological Survey has been investigating clays jointly with the Bureau of Mines, U. S. Department of the Interior, high-alumina clays formed by sedimentary processes are more important than those formed by all phases of volcanic activity. Clays derived directly from volcanic materials are composed dominantly of montmorillonite; but these clays, with the exception of the beidellite-nontronite varieties, have relatively low percentages of available alumina. In contrast, clays derived by thorough leaching of various aluminous rocks under conditions favoring thorough drainage are composed dominantly of kaolinite and when sorted by sedimentary processes form high-grade deposits; furthermore, the depositional structures of these sedimentary clays have favored the derivation of gibbsite through weathering, resulting in an increase in the alumina content of the clays. Kaolinite, gibbsite, and dickite all have relatively high percentages of available alumina.

Economic Geology↗
USGS2018

UZIG research: Measurement and characterization of unsaturated zone processes under wide-ranging climates and changing conditions

Unsaturated zone properties and processes are central to understanding the interacting effects of land-use change, contamination, and hydroclimate on our ability to grow food, sustain clean water supplies, and minimize loss of life and property. Advances in unsaturated zone science are being achieved through collaborations across traditional boundaries where information from biological, physical, and chemical disciplines is combined for new insights. The Unsaturated Zone Interest Group (UZIG) is an organization that exists principally to promote multidisciplinary collaborations and the sharing of ideas, expertise, and technical assets. Here we summarize key findings from 14 papers, several of which originated from a meeting convened by UZIG in 2017 at the University of Florida in Gainesville titled “Land-Use Change, Climate Change, and Hydrologic Extremes: Unsaturated Zone Responses and Feedbacks.” This special section of Vadose Zone Journal contains multidisciplinary research in three general categories relevant to measuring and understanding unsaturated zone responses to changing land uses and climate: (i) unsaturated zone properties and processes; (ii) soil–plant–atmosphere interactions; and (iii) novel field sampling devices. A strong cross-cutting theme in these papers is the value of continuous monitoring data and ways of utilizing them to discover novel hydrologic, biologic, and pedologic information. As climatic and land-use conditions change and demands for resources and stresses on ecosystems continue to intensify, it is vital to improve our fundamental understanding of the processes at work in the unsaturated zone. Toward that goal, we discuss the need for improved ground-based unsaturated zone monitoring networks.

Vadose Zone Journal↗
USGS2006

Identifying the effects of petrologic processes in a closed basaltic system using trace element concentrations in olivines and glasses: Implications for comparative planetology

We use trace-element concentrations in olivines and glasses from a closed basaltic system to identify the effects of petrologic processes on the trace-element record of that system. The closed basaltic system in question is the Makaopuhi Lava Lake (MLL), which is closed with respect to magma mixing. Detailed studies of this lava lake have provided important information about system variables and petrologic processes that have been measured and observed at the lake. These previous studies show that olivine crystallized from the lava lake at all stages of the lake’s evolution, which means that olivine and residual glasses contain a record of the lake’s petrologic history. We use this information, in conjunction with variations in trace-element concentrations in olivines and glasses, to show that mineral crystallization, gravitational settling, convective flow, filter pressing, and mineral-melt interface kinetics have characteristic effects on the trace element record of a closed basaltic system. These results are pertinent to the field of comparative planetology because they can be used to evaluate petrologic information in small samples from other planetary bodies, where information about system variables and/or petrologic processes is limited.

Hawaii↗
USGS2000

Pattern and process of land loss in the Mississippi Delta: A spatial and temporal analysis of wetland habitat change

An earlier investigation (Turner 1997) concluded that most of the coastal wetland loss in Louisiana was caused by the effects of canal dredging, that loss was near zero in the absence of canals, and that land loss had decreased to near zero by the late 1990s. This analysis was based on a 15-min quadrangle (approximately 68,000 ha) scale that is too large to isolate processes responsible for small-scale wetland loss and too small to capture those responsible for large-scale loss. We conducted a further evaluation of the relationship between direct loss due to canal dredging and all other loss from 1933–1990 using a spatial scale of 4,100 ha that accurately captures local land-loss processes. Regressions of other wetland loss on canal area (i.e., direct loss) for the Birdfoot, Terrebonne, and Calcasieu basins were not significant. Positive relationships were found for the Breton (r 2 =0.675), Barataria (r 2 =0.47), and Mermentau (r 2 =0.35) basins, indicating that the extent of canals is significantly related to wetland loss in these basins. A significant negative relationship (r 2 =0.36) was found for the Atchafalaya coastal basin which had statistically lower loss rates than the other basins as a whole. The Atchafalaya area receives direct inflow of about one third of the Mississippi discharge. When the data were combined for all basins, 9.2% of the variation in other wetland loss was attributable to canals. All significant regressions intercepted the y-axis at positive loss values indicating that some loss occurred in the absence of canals. Wetland loss did not differ significantly from the coast inland or between marsh type. We agree with Turner that canals are an important agent in causing wetland loss in coastal Louisiana, but strongly disagree that they are responsible for the vast majority of this loss. We conclude that wetland loss in the Mississippi delta is an ongoing complex process involving several interacting factors and that efforts to create and restore Louisiana’s coastal wetlands must emphasize riverine inputs of freshwater and sediments.

Louisiana↗
USGS2001

Patterns and processes of wetland loss in coastal Louisiana are complex: A reply to Turner 2001. Estimating the indirect effects of hydrologic change on wetland loss: If the Earth is curved, then how would we know it?

The coastal wetlands of Louisiana comprise a vast expanse of marine to freshwater wetland plant communities interspersed w-ith shallow bays and bayous. These wetlands were built by processes associated with the present-day Mississippi and Atchatfalaya River deltas and older distributaries occupied by the river over the past 7,000 }rears. The high rates of wetland loss identified in this system during the 20th century have serious consequences for living resources (Boesch et al. 1994) and coastal residents, and they affect our ability to maintain navigation and flood control. The restoration and management response to this problem must be grounded in a sound understanding of the causative factors. The system has been highly altered by river levees, roads and railway embankments, impoundments, and canals of many dimensions dredged for a variety of purposes. These changes have been imposed on a landscape that is essentially the result of a delicate natural balance between wetland building processes and compaction, subsidence, and sea-level rise. Many now recognize that coastal wetlands can cope with relatively high rates of subsidence and sea-level rise, as long as the processes that ensure wetland sustainability through vertical accumulation of substrate remain unimpaired (Boesch et al. 2000). The challenge facing both the scientific community and coastal resource managers in Louisiana is to look to the future. We must use our understanding of the problem and how it evolved to develop a multi-use ecosystem management plan, and some efforts have been made by state and federal agencies towards this goal (LCWCRTF & WCRA 1998). The present discussions (Turner 1997, 2001; Day et al. 2000; Gosselink 2001) demonstrate the complexity of the issues faced in Louisiana. While such discourse is common in the scientific community where varied approaches and interpretations are a sign of vitality, it is helpful to be clear about the state of knowledge and what levels of uncertainty exist. We seek to clarify some of the issues that have been raised in the discussion, recognizing that our best-available science cannot yet resolve many of them as completely as all would like.

Louisiana↗
USGS1972

Ground control requirements for precision processing of ERTS images

When the first Earth Resources Technology Satellite (ERTS-A) flies in 1972, NASA expects to receive and bulk-process 9,000 images a week. From this deluge of images, a few will be selected for precision processing; that is, about 5 percent will be further treated to improve the geometry of the scene, both in the relative and absolute sense. Control points are required for this processing. This paper describes the control requirements for relating ERTS images to a reference surface of the earth. Enough background on the ERTS-A satellite is included to make the requirements meaningful to the user.

Report↗
USGS1978

Manual on characteristics of Landsat computer-compatible tapes produced by the EROS Data Center digital image processing system

Landsat data are received by National Aeronautics and Space Administration (NASA) tracking stations and converted into digital form on high-density tapes (HDTs) by the Image Processing Facility (IPF) at the Goddard Space Flight Center (GSFC), Greenbelt, Maryland. The HDTs are shipped to the EROS Data Center (EDC) where they are converted into customer products by the EROS Data Center digital image processing system (EDIPS). This document describes in detail one of these products: the computer-compatible tape (CCT) produced from Landsat-1, -2, and -3 multispectral scanner (MSS) data and Landsat-3 only return-beam vidicon (RBV) data. Landsat-1 and -2 RBV data will not be processed by IPF/EDIPS to CCT format.

Report↗
USGS1980

A survey of image processing developments in support of remote sensing

New algorithm developments for image processing (IP) will occur throughout the 1980's, resulting from evolution in computer hardware and sensors as well as continuing research. This report will describe the areas of algorithm development that are occurring in applications, research, and operational environments. Included is an overview of image processing activities at institutions which are generally regarded as leaders in IP algorithm development and implementation. Finally, this report addresses directions in IP algorithm development that are being proposed for the EROS Data Center (EDC). The major applications of IP at EDC are developed for use in the processing, analysis, and extraction of remote sensing information from Landsat and aircraft data (platforms).

Report↗
USGS2000

Processing strategy for water-gun seismic data from the Gulf of Mexico

In order to study the regional distribution of gas hydrates and their potential relationship to a large-scale sea-fl oor failures, more than 1,300 km of near-vertical-incidence seismic profi les were acquired using a 15-in3 water gun across the upper- and middle-continental slope in the Garden Banks and Green Canyon regions of the Gulf of Mexico. Because of the highly mixed phase water-gun signature, caused mainly by a precursor of the source arriving about 18 ms ahead of the main pulse, a conventional processing scheme based on the minimum phase assumption is not suitable for this data set. A conventional processing scheme suppresses the reverberations and compresses the main pulse, but the failure to suppress precursors results in complex interference between the precursors and primary refl ections, thus obscuring true refl ections. To clearly image the subsurface without interference from the precursors, a wavelet deconvolution based on the mixedphase assumption using variable norm is attempted. This nonminimum- phase wavelet deconvolution compresses a longwave- train water-gun signature into a simple zero-phase wavelet. A second-zero-crossing predictive deconvolution followed by a wavelet deconvolution suppressed variable ghost arrivals attributed to the variable depths of receivers. The processing strategy of using wavelet deconvolution followed by a secondzero- crossing deconvolution resulted in a sharp and simple wavelet and a better defi nition of the polarity of refl ections. Also, the application of dip moveout correction enhanced lateral resolution of refl ections and substantially suppressed coherent noise.

Bulletin↗
USGS2016

The Land Processes Distributed Active Archive Center (LP DAAC)

The Land Processes Distributed Active Archive Center (LP DAAC) operates as a partnership with the U.S. Geological Survey and is 1 of 12 DAACs within the National Aeronautics and Space Administration (NASA) Earth Observing System Data and Information System (EOSDIS). The LP DAAC ingests, archives, processes, and distributes NASA Earth science remote sensing data. These data are provided to the public at no charge. Data distributed by the LP DAAC provide information about Earth’s surface from daily to yearly intervals and at 15 to 5,600 meter spatial resolution. Data provided by the LP DAAC can be used to study changes in agriculture, vegetation, ecosystems, elevation, and much more. The LP DAAC provides several ways to access, process, and interact with these data. In addition, the LP DAAC is actively archiving new datasets to provide users with a variety of data to study the Earth.

Fact Sheet↗
USGS2000

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Processing, taxonomy, and quality control of benthic macroinvertebrate samples

Qualitative and quantitative methods to process benthic macroinvertebrate (BMI) samples have been developed and tested by the U.S. Geological Survey?s National Water Quality Laboratory Biological Group. The qualitative processing method is based on visually sorting a sample for up to 2 hours. Sorting focuses on attaining organisms that are likely to result in taxonomic identifications to lower taxonomic levels (for example, Genus or Species). Immature and damaged organisms are also sorted when they are likely to result in unique determinations. The sorted sample remnant is scanned briefly by a second person to determine if obvious taxa were missed. The quantitative processing method is based on a fixed-count approach that targets some minimum count, such as 100 or 300 organisms. Organisms are sorted from randomly selected 5.1- by 5.1-centimeter parts of a gridded subsampling frame. The sorted remnant from each sample is resorted by a second individual for at least 10 percent of the original sort time. A large-rare organism search is performed on the unsorted remnant to sort BMI taxa that were not likely represented in the sorted grids. After either qualitatively or quantitatively sorting the sample, BMIs are identified by using one of three different types of taxonomic assessment. The Standard Taxonomic Assessment is comparable to the U.S. Environmental Protection Agency Rapid Bioassessment Protocol III and typically provides Genus- or Species-level taxonomic resolution. The Rapid Taxonomic Assessment is comparable to the U.S. Environmental Protection Agency Rapid Bioassessment Protocol II and provides Familylevel and higher taxonomic resolution. The Custom Taxonomic Assessment provides Species-level resolution whenever possible for groups identified to higher taxonomic levels by using the Standard Taxonomic Assessment. The consistent use of standardized designations and notes facilitates the interpretation of BMI data within and among water-quality studies. Taxonomic identifications are quality assured by verifying all referenced taxa and randomly reviewing 10 percent of the taxonomic identifications performed weekly by Biological Group taxonomists. Taxonomic errors discovered during this review are corrected. BMI data are reviewed for accuracy and completeness prior to release. BMI data are released phylogenetically in spreadsheet format and unprocessed abundances are corrected for laboratory and field subsampling when necessary.

Open-File Report↗
USGS2002

GPR data processing computer software for the PC

The computer software described in this report is designed for processing ground penetrating radar (GPR) data on Intel-compatible personal computers running the MS-DOS operating system or MS Windows 3.x/95/98/ME/2000. The earliest versions of these programs were written starting in 1990. At that time, commercially available GPR software did not meet the processing and display requirements of the USGS. Over the years, the programs were refined and new features and programs were added. The collection of computer programs presented here can perform all basic processing of GPR data, including velocity analysis and generation of CMP stacked sections and data volumes, as well as create publication quality data images.

Open-File Report↗
USGS2004

Desert Landforms and Surface Processes in the Mojave National Preserve and Vicinity

Landscape features in the Mojave National Preserve are a product of ongoing processes involving tectonic forces, weathering, and erosion. Long-term climatic cycles (wet and dry periods) have left a decipherable record preserved as landform features and sedimentary deposits. This website provides and introduction to climate-driven desert processes influencing landscape features including stream channels, alluvial fans, playas (dry lakebeds), dunes, and mountain landscapes. Bedrock characteristics, and the geometry of past and ongoing faulting, fracturing, volcanism, and landscape uplift and subsidence influence the character of processes happening at the surface.

Open-File Report↗
USGS2006

Users' manual for the Hydroecological Integrity Assessment Process software (including the New Jersey Assessment Tools)

This manual is a user’s guide to four computer software tools that have been developed for the Hydroecological Integrity Assessment Process. The Hydroecological Integrity Assessment Process recognizes that streamflow is strongly related to many critical physiochemical components of rivers, such as dissolved oxygen, channel geomorphology, and water temperature, and can be considered a “master variable” that limits the disturbance, abundance, and diversity of many aquatic plant and animal species. Applying the Hydroecological Integrity Assessment Process involves four steps: (1) a hydrologic classification of relatively unmodified streams in a geographic area using long-term gage records and 171 ecologically relevant indices; (2) the identification of statistically significant, nonredundant, hydroecologically relevant indices associated with the five major flow components for each stream class; and (3) the development of a stream-classification tool and a hydrologic assessment tool. Four computer software tools have been developed.

Open-File Report↗
USGS2009

Experimental Advanced Airborne Research Lidar (EAARL) Data Processing Manual

The Experimental Advanced Airborne Research Lidar (EAARL) is an example of a Light Detection and Ranging (Lidar) system that utilizes a blue-green wavelength (532 nanometers) to determine the distance to an object. The distance is determined by recording the travel time of a transmitted pulse at the speed of light (fig. 1). This system uses raster laser scanning with full-waveform (multi-peak) resolving capabilities to measure submerged topography and adjacent coastal land elevations simultaneously (Nayegandhi and others, 2009). This document reviews procedures for the post-processing of EAARL data using the custom-built Airborne Lidar Processing System (ALPS). ALPS software was developed in an open-source programming environment operated on a Linux platform. It has the ability to combine the laser return backscatter digitized at 1-nanosecond intervals with aircraft positioning information. This solution enables the exploration and processing of the EAARL data in an interactive or batch mode. ALPS also includes modules for the creation of bare earth, canopy-top, and submerged topography Digital Elevation Models (DEMs). The EAARL system uses an Earth-centered coordinate and reference system that removes the necessity to reference submerged topography data relative to water level or tide gages (Nayegandhi and others, 2006). The EAARL system can be mounted in an array of small twin-engine aircraft that operate at 300 meters above ground level (AGL) at a speed of 60 meters per second (117 knots). While other systems strive to maximize operational depth limits, EAARL has a narrow transmit beam and receiver field of view (1.5 to 2 milliradians), which improves the depth-measurement accuracy in shallow, clear water but limits the maximum depth to about 1.5 Secchi disk depth (~20 meters) in clear water. The laser transmitter [Continuum EPO-5000 yttrium aluminum garnet (YAG)] produces up to 5,000 short-duration (1.2 nanosecond), low-power (70 microjoules) pulses each second. Each pulse is focused into an illumination area that has a radius of about 20 centimeters on the ground. The pulse-repetition frequency of the EAARL transmitter varies along each across-track scan to produce equal cross-track sample spacing and near uniform density (Nayegandhi and others, 2006). Targets can have varying physical and optical characteristics that cause extreme fluctuations in laser backscatter complexity and signal strength. To accommodate this dynamic range, EAARL has the real-time ability to detect, capture, and automatically adapt to each laser return backscatter. The backscattered energy is collected by an array of four high-speed waveform digitizers connected to an array of four sub-nanosecond photodetectors. Each of the four photodetectors receives a finite range of the returning laser backscatter photons. The most sensitive channel receives 90% of the photons, the least sensitive receives 0.9%, and the middle channel receives 9% (Wright and Brock, 2002). The fourth channel is available for detection but is not currently being utilized. All four channels are digitized simultaneously into 65,536 samples for every laser pulse. Receiver optics consists of a 15-centimeter-diameter dielectric-coated Newtonian telescope, a computer-driven raster scanning mirror oscillating at 12.5 hertz (25 rasters per second), and an array of sub-nanosecond photodetectors. The signal emitted by the pulsed laser transmitter is amplified as backscatter by the optical telescope receiver. The photomultiplier tube (PMT) then converts the optical energy into electrical impulses (Nayegandhi and others, 2006). In addition to the full-waveform resolving laser, the EAARL sensor suite includes a down-looking 70-centimeter-resolution Red-Green-Blue (RGB) digital network camera, a high-resolution color infrared (CIR) multispectral camera (14-centimeter-resolution), two precision dual-frequency kinematic carrier-phase global positioning system (GPS) receivers, and an

Open-File Report↗