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At least 19 recordsLinked to original sources
USGS1976

Measurements of exclusive photoproduction processes at large values of t and u from 4 to 7.5 GeV

Exclusive photoproduction cross sections have been measured for the processes γ p → π + n , γ p → π 0 p , γ p → π − Δ + + , γ p → ρ 0 p , γ p → K + Λ , and γ p → K + Σ 0 at large t and u values at several energies for each process between 4 and 7.5 GeV. These measurements taken together with past data taken at small values of t and u provide complete angular distributions. The data show the usual small t and u peaks and a central region in which the cross section decreases approximately as s − 7 . The results are discussed within the context of parton or constituent models.

Physical Review D↗
USGS2010

Physical oceanography of continental shelves

Knowledge of the physical oceanography of continental shelves has increased tremendously in recent years, primarily as a result of new current and hydrographic measurements made in locations where no comparable measurements existed previously. In general, observations from geographically distinct continental shelves have shown that the nature of the flow may vary considerably from region to region. Although some characteristics, such as the response of currents to wind forcing, are common to many shelves, the relative importance of various physical processes in influencing the shelf flow field frequently is different. In the last several years, the scientific literature on shelf studies has expanded rapidly, with that for separate regions, to some extent, developing independently because of the variable role played by different physical effects.

Reviews of Geophysics and Space Physics↗
USGS2010

Lunar basin formation and highland stratigraphy

Multiring impact basins, formed after solidification of the lunar crust, account for most or all premare regional deposits and structures expressed in the lunar landscape and for major topographic and gravity variations. A fresh basin has two or more concentric mountain rings, a lineated ejecta blanket, and secondary impact craters. Crackled material on the floor may be impact melt. The ejecta blanket was emplaced at least partly as a ground‐hugging flow and was probably hot. A suggested model of basin formation is that the center lifts up and the rings form by inward collapse during evisceration. The resulting basin is shallow and has a central uplift of the mantle. This results in a central gravity high and a ring low. Later flooding by mare basalt has since modified most near side basins. Highland deposits of plains, furrowed and pitted terrain, and various hills, domes, and craters that were interpreted before the Apollo missions as being volcanic can now be interpreted as being basin related. A province map of the whole moon shows that the relatively young Orientale and Imbrium basins imprinted and rejuvenated much of the moon's surface; older basins must have also. The most primitive cratered surface remaining is mostly on the far side, distant from Imbrium and Orientale and other large relatively young basins. All five lunar landings in the highlands sampled stratigraphic units probably related to basins. Several nearly obliterated basins have been discovered recently, including a deep one on the far side that is as wide as the moon's radius. The presence of these ancient basins suggests that the surface is effectively saturated by basins and that many others were completely destroyed by later impacts. Basin impacts may have churned the lunar crust to large depths.

Reviews of Geophysics and Space Physics↗
USGS2022

Identifying key stressors driving biological impairment in freshwater streams in the Chesapeake Bay watershed, USA

Biological communities in freshwater streams are often impaired by multiple stressors (e.g., flow or water quality) originating from anthropogenic activities such as urbanization, agriculture, or energy extraction. Restoration efforts in the Chesapeake Bay watershed, USA seek to improve biological conditions in 10% of freshwater tributaries and to protect the biological integrity of existing healthy watersheds. To achieve these goals, resource managers need to better understand which stressors are most likely driving biological impairment. Our study addressed this knowledge gap through two approaches: 1) reviewing and synthesizing published multi-stressor studies, and 2) examining 303(d) listed impairments linked to biological impairment as identified by jurisdiction regulatory agencies (the states within the watershed and the District of Columbia). Results identified geomorphology (i.e., physical habitat), salinity, and toxic contaminants as important for explaining variability in benthic community metrics in the literature review. Geomorphology (i.e., physical habitat and sediment), salinity, and nutrients were the most reported stressors in the jurisdictional impairment analysis. Salinity is likely a major stressor in urban and mining settings, whereas geomorphology was commonly reported in agricultural settings. Toxic contaminants, such as pesticides, were rarely measured; more research is needed to quantify the extent of their effects in the region. Flow alteration was also highlighted as an important urban stressor in the literature review but was rarely measured in the literature or reported by jurisdictions as a cause of impairment. These results can be used to prioritize stressor monitoring by managers, and to improve stressor identification methods for identifying causes of biological impairment.

Chesapeake Bay Watershed↗
USGS2022

A review of the exploration, discovery, and characterization of highly concentrated gas hydrate accumulations in coarse-grained reservoir systems along the Eastern Continental Margin of India

The analysis of 3-D seismic data has become one of the most powerful ways to identify sand-rich gas hydrate reservoir systems and to directly identify highly concentrated gas hydrate prospects. Scientific drilling programs have shown that the occurrence of highly concentrated gas hydrate accumulations in coarse-grained, sand-rich, reservoir systems has a significant impact on the physical properties of sediments, allowing gas hydrates to be “directly detected” by conventional seismic analysis techniques. One of the most diagnostic responses of a gas hydrate-bearing sand reservoir is that of a high-velocity sedimentary section and an associated high-amplitude seismic response with a reflection polarity matching that of the seafloor. Knowledge of this physical relationship guided the Indian National Gas Hydrate Program Expedition 02 (NGHP-02) in their pre-drill site review and selection effort along the eastern continental margin of India in 2016. Within the planning, operational and post-operational data analysis phases of the NGHP-02 Expedition, scientists relied heavily on the analyses of the (1) pre-expedition acquired 3-D seismic data from offshore India, (2) downhole logging data acquired during NGHP-02 and (3) core samples and data obtained from NGHP-02 conventional- and pressure-cores to identify gas hydrates and assess the geologic controls on the formation and stability of these accumulations. Data analysis has confirmed the presence of extensive sand-rich depositional systems throughout the deepwater portions of the Krishna-Godavari and Mahanadi Basins in the Bay of Bengal. Two areas of the Krishna-Godavari Basin contain substantial gas hydrate accumulations in sand-rich systems, representing candidate sites for future potential energy exploitation.

Bay of Bengal, Krishna-Godavari Basin, Mahanadi Ba↗
USGS1987

Coincident seismic reflection/refraction studies of the continental lithosphere: A global review

Vertical-incidence reflection profiling has identified several characteristic features of the continental lithosphere including a generally transparent upper crust, a reflective lower crust, reflections from the crust-mantle boundary, and a commonly transparent upper mantle. The underlying physical causes of these characteristic features remain poorly understood. This review summarizes additional information brought to bear on the physical properties of these characteristic crustal structures through the use of coincident wide-angle refraction profiling.

Geophysical Journal International↗
USGS2000

Laboratory performance in the Sediment Laboratory Quality-Assurance Project, 1996-98

This report describes the results of the first 3 years of an ongoing study of sediment laboratories used by the U.S. Geological Survey (USGS). The sediment laboratories currently in operation constitute the entire USGS national laboratory system for sediment analyses. As with all environmental data, physical sediment data can be expected to contain a certain amount of difference, whether the difference resulted from the collecting, transporting, or analyzing of the sample. Because it is important to know how each laboratory is performing, the USGS initiated the Sediment Laboratory Quality-Assurance (SLQA) project in August 1996. From August 1996 through June 1998, five studies were made, the results of which are the basis of this report. The focus of the project is on quantitative analyses done on water-sediment mixtures to derive suspended-sediment concentrations, sediment-mass determinations, and sand/fine separations. For the purpose of this report, all mass determinations are net values—the tare weight of the container is excluded. The fine-size material is defined as particles sieved to a size of less than 62 micrometers (µm) and sand-size material is defined as particles sieved to a size of between 63 and 125 µm. Also, in this report, class 1 samples are defined as samples containing 50 to 100 milligrams (mg) of fine-size material, class 2 samples are defined as samples containing 101 to 300 mg of fine-size material, and class 3 samples are defined as samples containing 2,200 to 3,200 mg of fine-size material. In studies 96-1 through 98-1, the amount of sand added to each sample ranged from 9 to 28 percent of the mass of fine-size material in each sample class. Analytical results from all sediment quality-control samples are compiled and statistically summarized by the USGS, Branch of Quality Systems, both on an intra- and interlaboratory basis. When evaluating these data, the reader needs to keep in mind that every measurement has an error component associated with it. It is premature to use the data from the first five SLQA studies to judge any of the laboratories as performing in an unacceptable manner. There were, however, some notable differences in the results for the 12 laboratories that participated in the five SLQA studies. For example, the overall median percent difference for suspended-sediment concentration on an individual laboratory basis ranged from –18.04 to –0.33 percent. Five of the 12 laboratories had an overall median percent difference for suspended-sediment concentration of –2.02 to –0.33 percent. There was less variability in the median difference for the measured fine-size material mass. The overall median percent difference for fine-size material mass ranged from –10.11 to –4.27 percent. Except for one laboratory, the median difference for fine-size material mass was within a fairly narrow range of –6.76 to –4.27 percent. The median percent difference for sand-size material mass differed among laboratories more than any other physical sediment property measured in the study. The overall median percent difference for the sand-size material mass ranged from –1.49 percent to 26.39 percent. Five of the nine laboratories that do sand/fine separations had overall median percent differences that ranged from –1.49 to 2.98 percent for sand-size material mass. Careful review of the data reveals that certain laboratories consistently produced data within statistical control limits for some or all of the physical sediment properties measured in this study, whereas other laboratories occasionally produced data that exceeded the control limits.

Water-Resources Investigations Report↗
USGS2008

Diagnosis of an intense atmospheric river impacting the pacific northwest: Storm summary and offshore vertical structure observed with COSMIC satellite retrievals

This study uses the new satellite-based Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission to retrieve tropospheric profiles of temperature and moisture over the data-sparse eastern Pacific Ocean. The COSMIC retrievals, which employ a global positioning system radio occultation technique combined with "first-guess" information from numerical weather prediction model analyses, are evaluated through the diagnosis of an intense atmospheric river (AR; i.e., a narrow plume of strong water vapor flux) that devastated the Pacific Northwest with flooding rains in early November 2006. A detailed analysis of this AR is presented first using conventional datasets and highlights the fact that ARs are critical contributors to West Coast extreme precipitation and flooding events. Then, the COSMIC evaluation is provided. Offshore composite COSMIC soundings north of, within, and south of this AR exhibited vertical structures that are meteorologically consistent with satellite imagery and global reanalysis fields of this case and with earlier composite dropsonde results from other landfalling ARs. Also, a curtain of 12 offshore COSMIC soundings through the AR yielded cross-sectional thermodynamic and moisture structures that were similarly consistent, including details comparable to earlier aircraft-based dropsonde analyses. The results show that the new COSMIC retrievals, which are global (currently yielding ???2000 soundings per day), provide high-resolution vertical-profile information beyond that found in the numerical model first-guess fields and can help monitor key lower-tropospheric mesoscale phenomena in data-sparse regions. Hence, COSMIC will likely support a wide array of applications, from physical process studies to data assimilation, numerical weather prediction, and climate research. ?? 2008 American Meteorological Society.

Monthly Weather Review↗
USGS1977

Voyager imaging experiment

The overall objective of this experiment is exploratory reconnaissance of Jupiter, Saturn, their satellites, and Saturn's rings. Such reconnaissance, at resolutions and phase angles unobtainable from Earth, can be expected to provide much new data relevant to the atmospheric and/or surface properties of these bodies. The experiment also has the following specific objectives: Observe and characterize the global circulation of the atmospheres of Jupiter and Saturn; Determine the horizontal and vertical structure of the visible clouds and establish their relationship to the belted appearance and dynamical properties of the planetary atmospheres; Determine the vertical structure of high, optically-thin, scattering layers on Jupiter and Saturn; Determine the nature of anomalous features such as the Great Red Spot, South Equatorial Belt disturbances, etc.; Characterize the nature of the colored material in the clouds of Jupiter and Saturn, and identify the nature and sources of chromophores on Io and Titan; Perform comparative geologic studies of many satellites at less than 15-km resolution; Map and characterize the geologic structure of several satellites at high resolution (???1 km); Investigate the existence and nature of atmospheres on the satellites; Determine the mass, size, and shape of many of the satellites by direct measurement; Determine the direction of the spin axes and periods of rotation of several satellites, and establish coordinate systems for the larger satellites; Map the radial distribution of material in Saturn's rings at high resolution; Determine the optical scattering properties of the primaries, rings, and satellites at several wavelengths and phase angles; Search for novel physical phenomena, e.g., phenomena associated with the Io flux tube, meteors, aurorae, lightning, or satellite shadows. ?? 1977 D. Reidel Publishing Company.

Space Science Reviews↗
USGS2025

Relative abundance, seasonal occurrence, and distribution of marine birds in the northern Gulf of Mexico

Marine birds in the U.S. Gulf of Mexico have long been poorly studied. Given statutory obligations to protect migratory birds and endangered species, three broad-scale vessel and aerial programs initiated since 2010 have now surveyed the entire northern Gulf. Vessel coverage alone exceeds 700 d and 74,000 km of observer effort using 300-m strip transects. We supplemented these survey data with earlier, smaller-scale studies, eBird checklists, literature reviews, and other less accessible sources to create snapshot summaries of relative abundance, seasonal occurrence, and regional distribution for 117 taxa of marine and water birds reported from the northern Gulf (113 of which were substantiated with physical evidence). Using taxonomic and functional criteria, we identified 56 taxa characteristic of open shelf, slope, and pelagic waters (federal jurisdiction), 41 taxa with primarily coastal affinities (state and federal jurisdiction), and 20 taxa of sea and diving ducks. High species richness of marine birds in the northern Gulf is attributed to (1) a temperate-to-tropical gradient facilitating diverse marine environments year-round; (2) varied geographic origins of marine bird species using the Gulf; and (3) a mostly enclosed sea basin acting as a vagrant trap for wide-ranging species. Our taxonomic list and status updates seek to bridge information gaps for marine birds now subject to accelerated commercial uses of this region's continental shelf, including newly proposed offshore wind energy development. Other applications include guiding risk and vulnerability assessments of Gulf marine birds, providing core content for seabird observer training, and prioritizing environmental impact reviews and monitoring programs in offshore energy construction and operations plans.

Marine Ornithology: Journal of Seabird Research an↗
USGS2021

Evaluating coexistence of fish species with coastal cutthroat trout in low order streams of western Oregon and Washington, USA

When multiple species of fish coexist there are a host of potential ways through which they may interact, yet there is often a strong focus on studies of single species without considering these interactions. For example, many studies of forestry–stream interactions in the Pacific Northwest have focused solely on the most prevalent species: Coastal cutthroat trout. To examine the potential for interactions of other fishes with coastal cutthroat trout, we conducted an analysis of 281 sites in low order streams located on Washington’s Olympic Peninsula and along the central Oregon coast. Coastal cutthroat trout and juvenile coho salmon were the most commonly found salmonid species within these streams and exhibited positive associations with each other for both presence and density. Steelhead were negatively associated with the presence of coastal cutthroat trout as well as with coho salmon and sculpins (Cottidae). Coastal cutthroat trout most frequently shared streams with juvenile coho salmon. For densities of these co-occurring species, associations between these two species were relatively weak compared to the strong influences of physical stream conditions (size and gradient), suggesting that physical conditions may have more of an influence on density than species interactions. Collectively, our analysis, along with a review of findings from prior field and laboratory studies, suggests that the net effect of interactions between coastal cutthroat trout and coho salmon do not appear to inhibit their presence or densities in small streams along the Pacific Northwest.

Washington↗
USGS2007

Crust and lithospheric structure – Global crustal structure

The Earth’s crust has played an important role in all aspects of this planet’s evolution. This chapter presents a review of our current understanding of the physical properties of the crust on a global basis. This understanding comes from extensive seismic measurements using many techniques, as well as nonseismic geophysics, including gravity, magnetic, geoelectric, and heat flow measurements. Seismic measurements include those that employ active (man-made) sources and those that use passive (naturally occurring) sources. Deep seismic reflection profiles provide a seismic image of the crust in twodimensions with a high (50–100m) resolution. Local earthquake tomography can provide three-dimensional (3-D) seismic images at moderate (500–1000m) resolution and higher, depending on the number and spacing of seismographs. Nonseismic methods provide estimates of crustal density, magnetic properties, conductivity and geotherms (temperature vs depth). The crust in deep ocean basins is 6–7km thick and has a relatively uniform seismic velocity structure, but there are numerous oceanic regions with anomalous crustal structure, including mid-ocean ridges, trenches, volcanic islands, and oceanic plateaux. Ocean–continent passive margins are also highly variable in structure, and may be classified as volcanic versus nonvolcanic margins. Continental crust ranges in thickness from 16 to 80km, and has a highly variable seismic velocity and density structure. The proportions of continental crust, by area, are 69% shield and platform (cratons), 15% old and young orogens, 9% extended (stretched) crust, 6 % magmatic arc, and 1% rifts. The weighted mean continental crustal thickness and average crustal velocity are 41km (SD 6.2km) and 6.45kms−1 (SD 0.21kms−1), respectively. A global geographic distribution of seismic data has made it possible to create global crustal models with cell sizes as small as 2°×2°. These models provide a complete description of seismic velocities and density within the crust and uppermost mantle, including, where present, ice, water, and sedimentary layers and the crystalline crust (parameterized in three layers, upper, middle and lower crust), and sub-Moho properties. The crust is the most intensely studied region of the Earth’s interior and consequently is the best understood in terms of its structure, composition, and evolution. © 2007 Elsevier B.V. All rights reserved.

Book chapter↗
USGS2020

Storm impacts on phytoplankton community dynamics in lakes

In many regions across the globe, extreme weather events such as storms have increased in frequency, intensity, and duration due to climate change. Ecological theory predicts that such extreme events should have large impacts on ecosystem structure and function. High winds and precipitation associated with storms can affect lakes via short‐term runoff events from watersheds and physical mixing of the water column. In addition, lakes connected to rivers and streams will also experience flushing due to high flow rates. Although we have a well‐developed understanding of how wind and precipitation events can alter lake physical processes and some aspects of biogeochemical cycling, our mechanistic understanding of the emergent responses of phytoplankton communities is poor. Here we provide a comprehensive synthesis that identifies how storms interact with lake and watershed attributes and their antecedent conditions to generate changes in lake physical and chemical environments. Such changes can restructure phytoplankton communities and their dynamics, as well as result in altered ecological function (e.g., carbon, nutrient and energy cycling) in the short‐ and long‐term. We summarize the current understanding of storm‐induced phytoplankton dynamics, identify knowledge gaps with a systematic review of the literature, and suggest future research directions across a gradient of lake types and environmental conditions.

Global Change Biology↗
USGS2019

Global virtual water trade and the hydrological cycle: Patterns, drivers, and socio-environmental impacts

The increasing global demand for farmland products is placing unprecedented pressure on the global agricultural system and its water resources. Many regions of the world, that are affected by a chronic water scarcity relative to their population, strongly depend on the import of agricultural commodities and associated embodied (or virtual) water. The globalization of water through virtual water trade is leading to a displacement of water use and a disconnection between human populations and the water resources they rely on. Despite the recognized importance of these phenomena in reshaping the patterns of water dependence through teleconnections between consumers and producers, their effect on global and regional water resources has just started to be quantified. This review investigates the global spatiotemporal dynamics, drivers, and impacts of virtual water trade through an integrated analysis of surface water, groundwater, and root-zone soil moisture consumption for agricultural production; it evaluates how virtual water flows compare to the major “physical water fluxes” in the Earth System; and provides a new reconceptualization of the hydrologic cycle to account also for the role of water redistribution by the hidden ‘virtual water cycle’.

Environmental Research Letters↗
USGS2017

Can ozone be used to control the spread of freshwater Aquatic Invasive Species?

The introduction of aquatic invasive species to non-native habitats can cause negative ecological effects and also billions of dollars in economic damage to governments and private industries. Once aquatic invasive species are introduced, eradication may be difficult without adversely affecting native species and habitats, urging resource managers to find preventative methods to protect non-invaded areas. The use of ozone (O 3 ) as a non-physical barrier has shown promise as it is lethal to a wide range of aquatic taxa, requires a short contact time, and is relatively environmentally safe in aquatic systems when compared to other chemicals. However, before O 3 can be considered as an approach to prevent the spread of aquatic invasive species, its effects on non-target organisms and already established aquatic invasive species must be fully evaluated. A review of the current literature was conducted to summarize data regarding the effects of O 3 on aquatic taxa including fish, macroinvertebrates, zooplankton, phytoplankton, microbes, and pathogens. In addition, we assessed the practicality of ozone applications to control the movement of aquatic invasive species, and identified data gaps concerning the use of O 3 as a non-physical barrier in field applications.

Management of Biological Invasions↗
USGS2023

Modeling post-wildfire hydrologic response: Review and future directions for applications of physically based distributed simulation

Wildfire is a growing concern as climate shifts. The hydrologic effects of wildfire, which include elevated hazards and changes in water quantity and quality, are increasingly assessed using numerical models. Post-wildfire application of physically based distributed models provides unique insight into the underlying processes that affect water resources after wildfire. This work reviews and synthesizes post-wildfire applications of physically based distributed models by examining the scales and geographic/ecohydrologic distribution of model applications, hydrologic response process representation, model parameterization, and model performance metrics. Highlighted gaps and opportunities for advancing physically based distributed hydrologic response modeling after wildfire include the following: (a) applying models in under-represented geographic (S. America, Africa, Asia) and ecohydrologic regions (arid or dry subhumid climates), (b) incorporating all four major streamflow generation mechanisms (infiltration excess, saturation excess, subsurface storm flow, and groundwater flow), (c) representing integrated vadose zone and saturated zone processes to better capture subsurface streamflow generation, (d) building new remotely sensed model parameterization methods for precipitation interception, infiltration, and overland flow that account for burn severity and recovery, (e) incorporating distributed state variables (e.g., soil moisture, groundwater levels) in model performance assessment, (f) designing model intercomparison studies, including field datasets specifically for post-wildfire model development and validation, (g) linking mechanistic vegetation regrowth models with hydrologic models to improve simulation of process shifts as ecosystems recover, and (h) creating a new community modeling framework to integrate modeling advances across the wildfire science community.

Earth's Future↗
USGS2019

A brief introduction to integrated pest management for aquatic systems

Aquatic invasive plants and animals are increasingly becoming a problem, causing severe economic and ecological damage to critical freshwater systems. The best strategy for controlling an invasive pest employs an integrated pest management (IPM) approach using a combination of biological, physical, chemical, and social/cultural control methods. Here, we examine the history and development of IPM and provide a discussion of the components of an IPM program involving development, evaluation, and management. Control approaches will be reviewed and the application of this technique to aquatic systems will be discussed. A discussion of the Great Lakes Fishery Commission's (GLFC) Integrated Management of Sea Lamprey Petromyzon marinus Control Program will be provided to illustrate the application of IPM to an aquatic system.

North American Journal of Fisheries Management↗
USGS1981

Proceedings of a workshop on clathrates (gas hydrates) in the National Petroleum Reserve in Alaska, July 16-17, 1979, Menlo Park, California

Purpose : The purpose of this report is to make available the results of the "Workshop on clathrates (gas hydrates) in the National Petroleum Reserve in Alaska," July 16-17, 1979, Menlo Park, California. Scope : Written reports presented by participants of the workshop, relevant letters generated by this workshop and some "forms" created within ONPRA to aid in collecting information are an unusual assemblage but are presented in the proceedings because I feel they can be of use to others. The articles are arranged alphabetically because of the diverse aspects in style and subject matter. A comprehensive list of references was forwarded to Gas Research Institute to avoid duplication of bibliographic effort and because I have been unable to unscramble Russian references to the satisfaction of our editors. The workshop on Clathrates in NPRA : The workshop was convened in Menlo Park on July 16-17, 1979, to review our "knowledge of clathrates and to help develop background for ONPRA 1 s program on clathrates. Speakers were invited to discuss clathrates or some aspect of the physical or chemical relations of clathrates. The letters of invitation, schedule of talks, list of attendees, and a list of workers interested in clathrates are inserted, although the procedure is unusual because these define the scope and objectives of the meetings. Conclusions from the meeting : Conclusions of the discussions are: (a) very little is known about in situ clathrates, (b) our ability to identify in situ clathrates while drilling is poor, (c) the engineering of ONPRA wells is not conductive to the study of clathrates because of the large holes drilled, and (d) ONPRA could justify only limited investigations of clathrates. The attendees unanimously agreed that the next step to be taken by ONPRA should be to examine the wire-line logs and drilling records of NPRA wells to identify probable zones of natural occurring gas hydrates (clathrates). The atttendees stressed the need for more accurate data on natural thermoclines and additional compositional analyses of gases encountered in NPRA wells in order to more accurately define the P/T fields of natural clathrates of NPRA. Article 2 is an overview of results of the meeting.

Alaska↗