Showing papers in "Eos, Transactions American Geophysical Union in 1996"
TL;DR: A Macintosh computer program that can perform many time-series analysis procedures is now available on the Internet free of charge, originally designed for paleoclimatic time series.
Abstract: A Macintosh computer program that can perform many time-series analysis procedures is now available on the Internet free of charge. Although AnalySeries was originally designed for paleoclimatic time series, it can be useful for most fields of Earth sciences. The program's graphical user interface allows easy access even for people unfamiliar with computer calculations. Previous versions of the program are already used by hundreds of scientists worldwide.
2,015 citations
TL;DR: Baines as discussed by the authors makes significant progress in describing the flow of homogeneous and especially stratified real fluid flows over uneven topography, whether it be ridges on a laboratory model or a real mountain.
Abstract: Everyone talks about the weather, but no one does anything about it, an adage says. Similarly, many fluid mechanicians this century have sought to describe accurately the flow phenomena occurring when fluid moves past an object or irregular terrain, but usually the fluid model and/or the body shape had to be substantially simplified to make the problem tractable. In this new monograph, Peter Baines has really “done something about it.” He makes significant progress in describing the flow of homogeneous and especially stratified real fluid flows over uneven topography, whether it be ridges on a laboratory model or a real mountain.
259 citations
TL;DR: In this article, it is shown that for steep hillslopes with thin soils, the fundamental control on hillslope flow paths is the bedrock surface, which is not always determined by surface topography.
Abstract: Hillslope hydrologists have long assumed that the downslope movement of water and solutes can best be described by surface topography since gravitational potential largely dominates hydraulic gradients in steep terrain. Hence with the increased availability of Digital Terrain Maps (DTMs), surface topography is driving many popular hydrological models and is being used to estimate flow pathways in hydrological and geochemical models. This method may suffice at the catchment scale, but at the hillslope scale, flow pathways are not always determined by surface topography.
It is at this critical scale (100–10,000 m2) that water flux and the chemical composition of soil water and groundwater can be measured as they move downslope. The complex interactions between water and solutes along hillslope subsurface flow paths have not been well documented. New evidence suggests that for steep hillslopes with thin soils, the fundamental control on hillslope flow paths is the bedrock surface.
111 citations
TL;DR: A research project in Tanzania, East Africa, is being conducted to examine seismic velocities within the crust and upper mantle in an area where cratonic lithosphere is experiencing extensional tectonism as mentioned in this paper.
Abstract: A research project in Tanzania, East Africa, is being conducted to examine seismic velocities within the crust and upper mantle in an area where cratonic lithosphere is experiencing extensional tectonism. The results will be used to evaluate models of cratonic structure. Waveforms from several hundred teleseismic earthquakes and over 10,000 regional and local earthquakes recorded in 1994 and 1995 by the Tanzania Broadband Seismic Experiment are not only yielding new insights into deep continental structure, but are also helping to determine the tectonic stability of cratons by identifying the locus of rifting within northeastern Tanzania.
107 citations
TL;DR: Analytic Element Modeling of Groundwater Flow as discussed by the authors is an excellent tutorial on the subjects of groundwater flow and modeling groundwater with the analytic element method, and it is recommended to any student of groundwater hydrology, as well as to researchers and professionals concerned with modeling regional groundwater flow in productive aquifers.
Abstract: Analytic Element Modeling of Groundwater Flow offers much more than one might anticipate from its title. It is an excellent tutorial on the subjects of groundwater flow and modeling groundwater with the analytic element method. I greatly enjoyed reading it, and I recommend it to any student of groundwater hydrology, as well as to researchers and professionals concerned with modeling regional groundwater flow in productive aquifers. Chapters 3 and 6 are particularly interesting.
93 citations
TL;DR: The discovery of the Earth's radiation belts by the first U.S. satellites in the late 1950s was an astonishing surprise as discussed by the authors, and the exploration of the outer solar system by the Pioneer and Voyager spacecraft showed that rather than being a peculiar characteristic of Earth's environment, intense andenergetic radiation belts are common to the space environments of all magnetized planets.
Abstract: The discovery of the Earth's radiation belts by the first U.S. satellites in the late 1950s was an astonishing surprise. Composed of magnetically trapped populations of charged particles with energies up to hundreds of MeV, these belts are intense enough to kill satellites and astronauts alike if appropriate measures are not taken. More recently, the exploration of the outer solar system by the Pioneer and Voyager spacecraft showed that rather than being a peculiar characteristic of the Earth's environment, intense andenergetic radiation belts are common to the space environments of all magnetized planets. Jupiter, for example, a planet that could hardly be more different than Earth, has a radiation environment several orders of magnitude more severe than the Earth's. We can presume from this evidence that hyperacceleration, trapping, and redistribution of intense and energetic charged particles are omnipresent within magnetized astrophysical environments throughout the universe.
92 citations
TL;DR: In this article, the authors considered that the normal faults related to graben structures in the Lower Rhine embayment could produce large earthquakes, and this moderate earthquake is considered to be one of the major historical seismic events in this region, and it is stimulating concern among seismologists and geologists.
Abstract: Northern Europe would typically be classified as a relatively stable continental region where seismic hazard is low. Indeed, in comparison to active zones in the Mediterranean, seismic activity is low in northern Europe and the Lower Rhine graben region. Until recently, no one would have suspected that the normal faults related to graben structures in the Lower Rhine embayment could produce large earthquakes. Yet, on April 13, 1992, an Ms = 5.3 earthquake struck the city of Roermond in the Netherlands. This moderate earthquake is considered to be one of the major historical seismic events in this region, and it is stimulating concern among seismologists and geologists. Fundamental questions are being asked about fault behavior in the region and the earthquake distribution in time and space.
85 citations
TL;DR: A multidisciplinary research program is studying the structure, composition, and tectonic evolution of the mantle and crust of one of the best preserved early Archean eratons: the Kaapvaal craton in southern Africa.
Abstract: A multidisciplinary research program is studying the structure, composition, and tectonic evolution of the mantle and crust of one of the best preserved early Archean eratons: the Kaapvaal craton in southern Africa. Cratons, which have survived over 2.5 Ga of tectonic activity on the Earth's surface, are more than just old crustal features. They form the stable nuclei of the present-day continents, comprising regions of thickened lithosphere extending deeper than 200 km.
84 citations
TL;DR: In this article, the authors observed the initiation, development, and decay of a recurrent coastal plume in southern Lake Michigan (Figure 1) and collected water samples from helicopter and a small boat.
Abstract: NOAA CoastWatch satellite imagery from early 1996 captured the initiation, development, and decay of a recurrent coastal plume in southern Lake Michigan (Figure 1). For the past 4 years intermittent satellite coverage has revealed a late winter-early spring plume in the lake, a feature also observed by Mortimer [1988]. In 1996, clear weather conditions allowed researchers to observe the plume's development for the first time and they also collected water samples from helicopter and a small boat.
77 citations
TL;DR: A third summer of coastal upwelling observations was recently completed by researchers at LEO-15, the Long-term Ecosystem Observatory established in 15 m of water offshore of Tuckerton, New Jersey.
Abstract: A third summer of coastal upwelling observations was recently completed by researchers at LEO-15, the Long-term Ecosystem Observatory established in 15 m of water offshore of Tuckerton, New Jersey. Each year, real-time satellite images of wind-driven upwelling events trigger fast-response shipboard surveys to study the subsurface structure of the upwelled features and their relationship to bottom dissolved oxygen (DO) concentrations (Figure 1). The LEO-15 observations indicate that recurrent up-welling centers develop on the downslope sides of topographic highs and coincide with the historically observed regions of recurrent low DO. Recent modeling suggests that because of the along-shore topographic variations, a cyclonic eddy in the upwelling center forms that may concentrate nutrients, leading to phytoplankton blooms and subsequent reductions in DO as the resulting organic material decays below the thermocline.
69 citations
TL;DR: In this paper, an anomalous northward penetration of waters from the Brazil/Malvinas confluence region into the South Brazil Bight was observed (Figure 1) in the austral winter of 1993.
Abstract: Observations in the Brazil Current region between 20° and 30°S are revealing many interesting oceanographic features. In the austral winter of 1993, what appears to be an anomalous northward penetration of waters from the Brazil/Malvinas confluence region into the South Brazil Bight was observed (Figure 1).
TL;DR: A core of ice recently recovered from a rock glacier in the Absaroka Mountains of northwestern Wyoming demonstrates several important aspects about rock glaciers as mentioned in this paper... and the core of some rock glaciers is composed of layered ice that can be drilled and recovered, and some of this ice is exceptionally old.
Abstract: Anyone who spends much time above the treeline has probably seen rock glaciers and paused to wonder about them. Their curious and occasionally spectacular forms (Figure 1) occur in alpine and polar regions throughout the world, yet much remains uncertain about how they develop. A core of ice recently recovered from a rock glacier in the Absaroka Mountains of northwestern Wyoming vividly illustrates several important aspects about rock glaciers. At least some rock glaciers are a form of debris-covered glacier, and original isotopic stratigraphy may be preserved within their ice. Perhaps most interesting of all, the core of some rock glaciers is composed of layered ice that can be drilled and recovered, and some of this ice is exceptionally old.
TL;DR: The Arctic Ocean Section (AOS) experiment as discussed by the authors was conducted by two Canadian and U.S. ice breakers to investigate the biological, chemical, and physical systems that define the role of the Arctic in global change.
Abstract: During July–September 1994, two Canadian and U.S. ice breakers crossed the Arctic Ocean (Figure 1) to investigate the biological, chemical, and physical systems that define the role of the Arctic in global change. The results are changing our perceptions of the Arctic Ocean as a static environment with low biological productivity to a dynamic and productive system. The experiment was called the Arctic Ocean Section (AOS) and the ships were the Canadian Coast Guard ship Louis S. St.-Laurent and the U.S. Coast Guard cutter Polar Sea.
TL;DR: An Eemian cold event observed in both high-resolution marine and terrestrial climate records offers an opportunity to study a climate event during an interglacial on a human timescale, thus providing an analog for future climate change as mentioned in this paper.
Abstract: An Eemian cold event observed in both high-resolution marine and terrestrial climate records offers an opportunity to study a climate event during an interglacial on a human timescale, thus providing an analog for future climate change. This event, however, would not have been discovered had it not been for the “Eemian controversy” stirred by the Greenland ice core records.
TL;DR: In this paper, a pulse-like temperature signal, produced when water generated by convection drains into a deep boundary current, has apparently been detected in the Mediterranean, which provides clues to the mechanisms by which the dense water escapes the convection region and makes its journey.
Abstract: Deep convection is important in forming the dense water masses that lie below the ocean's surface and feed the global thermohaline circulation system. But the exact role that deep convection plays in these processes is a subject of much debate. Now, for the first time, a pulse-like temperature signal, produced when water generated by convection drains into a deep boundary current, has apparently been detected in the Mediterranean. This observation provides clues to the mechanisms by which the dense water escapes the convection region and makes its journey. While up to 50% of the newly formed water could incorporated into the deep boundary current this way, no increase in its transport was observed.
TL;DR: In the last decade, the oceanography community has focused much attention on the Mediterranean Sea as mentioned in this paper, and the growing interest is that the Mediterranean's impact on the Northern Atlantic Ocean is more significant than previously realized.
Abstract: During the last decade the oceanography community has focused much attention on the Mediterranean Sea. One reason for the growing interest is that the Mediterranean's impact on the Northern Atlantic Ocean is more significant than previously realized. The warm, salty Mediterranean water tongue exits the Gibraltar Straits and spreads throughout the North Atlantic at all depths between 1000 and 2500 m. The second reason for the surge in interest is the well-recognized role of the Mediterranean Sea as a laboratory for studying ocean processes that are important in global climate dynamics [Malanotte-Rizzoli and Robinson, 1991; Malanotte-Rizzoli and Robinson, 1994].
TL;DR: Most water scientists and environmental engineers will recognize this classic environmental chemistry text as "Stumm and Morgan" rather than Aquatic Chemistry as mentioned in this paper, and will recognize it as a classic text.
Abstract: Most water scientists and environmental engineers will recognize this classic environmental chemistry text as “Stumm and Morgan” rather than Aquatic Chemistry. Publication of the first edition in 1970 established a standard for books dealing with environmental chemistry in terms of depth and breadth of coverage. Scientists and engineers concerned with issues of water quality are well advised to have Aquatic Chemistry as part of their personal libraries, or at least in their office libraries.
TL;DR: A 1995 revision of the IGS was adopted by the International Association of Geomagnetism and Aeronomy (IAGA) during the XXI General Assembly of the International Union of Geodesy and Geophysics held in Boulder, Colo., in July 1995 as discussed by the authors.
Abstract: A 1995 revision of the International Geomagnetic Reference Field (IGRF) was adopted by the International Association of Geomagnetism and Aeronomy (IAGA) during the XXI General Assembly of the International Union of Geodesy and Geophysics held in Boulder, Colo., in July 1995.
TL;DR: The Whittier Narrows earthquake of 1987 and the Northridge earthquake of 1991 highlighted the earthquake hazards associated with buried faults in the Los Angeles region as mentioned in this paper, and a more thorough knowledge of the subsurface structure of southern California is needed to reveal these and other buried faults and to aid us in understanding how the earthquake-producing machinery works in this region.
Abstract: The Whittier Narrows earthquake of 1987 and the Northridge earthquake of 1991 highlighted the earthquake hazards associated with buried faults in the Los Angeles region. A more thorough knowledge of the subsurface structure of southern California is needed to reveal these and other buried faults and to aid us in understanding how the earthquake-producing machinery works in this region.
TL;DR: This book is one of the few books that addresses the scaling problem in hydrology: that is, how to transfer information from one scale to another and how to handle spatial heterogeneity.
Abstract: Scale Issues in Hydrological Modeling is a collection of 27 papers presented at a workshop in Australia in 1993 and later published in two special issues of Hydrological Processes. It is one of the few books that addresses the scaling problem in hydrology: that is, how to transfer information from one scale to another and how to handle spatial heterogeneity. It gives us a flavor of the nature and extent of the scaling problems in hydrology, although no general answers are provided.
TL;DR: The International Atomic Energy Agency (IAEA) held an Advisory Group Meeting on stable isotope reference and intercomparison materials for light elements in Vienna from December 11 to 14, 1995 as discussed by the authors.
Abstract: Stable isotope-ratio measurements of the light elements have been used in increasingly important ways to understand processes in geochemistry, hydrology, oceanography, atmospheric sciences, environmental studies, and many other fields. Progress in these fields requires better precision and reproducibility of stable isotope-ratio measurements. Some laboratories are claiming accuracies of 0.02‰; or better for δ13C and δ180. However, δ13C and δ180 analyses of the same sample by different laboratories can differ by more than 0.3‰. Recognizing that isotopic analyses of the same homogeneous material reported from different credible laboratories should yield the same isotopic composition within the uncertainty of the measurements, the International Atomic Energy Agency (IAEA) held an Advisory Group Meeting on stable isotope reference and intercomparison materials for light elements in Vienna from December 11 to 14, 1995.
TL;DR: An experiment to identify changes in water mass properties as a result of sea ice growth and deformation was conducted in a 110×110 km region of the Antarctic pack ice near 64°S, 140°E in August 1995 as mentioned in this paper.
Abstract: An experiment to identify changes in water mass properties as a result of sea ice growth and deformation was conducted in a 110×110 km region of the Antarctic pack ice near 64°S, 140°E in August 1995. This was the first intensive winter-time study in this region, which is thought to be high in ice production and active in bottom water formation [Foster, 1995; Gordon and Tchernia, 1972]. The information gathered is important in understanding the role sea ice plays in the climate system and for developing and validating combined ocean-ice-atmosphere models.
TL;DR: For example, this article reported that of the more than 80 jet aircraft that encountered volcanic ash clouds during the past 15 years, seven lost engine power as a result and repair costs from encounters with volcanic clouds through mid-1994 are estimated at more than $200 million.
Abstract: When airplanes meet clouds of volcanic ash thousands of feet above Earth's surface, the combination can be potentially deadly. Of the more than 80 jet aircraft that encountered volcanic ash clouds during the past 15 years, seven lost engine power as a result. The problem is also expensive. Repair costs from encounters with volcanic clouds through mid-1994 are estimated at more than $200 million [Casadevall, 1994]. Many pilots never know they are flying through volcanic ash because the radar onboard their planes cannot detect the small (1–15 μm in radius) particles that cause the hazard. With onboard radar systems unable to detect volcanic clouds, mitigating the hazard is a challenge.
TL;DR: Biogenic silica, better known as opal, is one of the three biogenic components of pelagic sediments, along with carbonate and organic matter, and it is a powerful tool for understanding the carbon cycle of the present and past.
Abstract: Biogenic silica, better known as opal, is one of the three biogenic components of pelagic sediments, along with carbonate and organic matter, and it is a powerful tool for understanding the carbon cycle of the present and past Opal is formed in surface waters during the photosynthesis of siliceous phytoplankton such as diatoms After cells die, they sink through the water column; the fraction that is not dissolved ultimately is buried in the underlying sediments In the modern ocean, siliceous phytoplankton generates more than 50% of the biological pump of CO2
TL;DR: The Mediterranean ridge's extreme environments have led to several surprising findings as discussed by the authors, including evidence of a molluscan community possibly sustained by chemosynthesis, and five brine lakes have been discovered in the deep Eastern Mediterranean.
Abstract: Exploration of the Mediterranean ridge's extreme environments has led to several surprising findings. Over the last 10 years five brine lakes have been discovered in the deep Eastern Mediterranean. For the first time in the sea's deep waters, a temperature of over 45°C was recorded in 1994 and evidence of a molluscan community possibly sustained by chemosynthesis was found in 1993.
TL;DR: The results from the Faeroe-Iceland Ridge Experiment (FIRE) conducted in the summer of 1994 suggest that it is thicker and cooler than previously assumed as discussed by the authors, with a high-level crustal magma chamber beneath Krafla.
Abstract: Since the 1970s there has been an ongoing debate about whether the crust beneath Iceland is relatively thin ( 20 km) and cooler. New results from the Faeroe-Iceland Ridge Experiment (FIRE) conducted in the summer of 1994 suggest that it is thicker and cooler.
This major land-sea study investigated the crust generated where the North Atlantic spreading center intersects the Iceland mantle plume and mapped the transition from thickened oceanic crust to the continental fragment on which the Faeroe Islands sit. Seismic techniques were used to obtain a 600-km profile of the area (Figure 1). Preliminary results suggest that a 20-km-thick crust is being generated beneath the northern Neovolcanic Zone of Iceland, with a high-level crustal magma chamber beneath Krafla. In northeast Iceland, the igneous crust is considerably thicker, reaching 35 km, while along the Faeroe-Iceland Ridge it varies between 25–30 km.
TL;DR: For each kilogram of water on Earth, only 1 mg is stored as soil moisture as discussed by the authors. Yet this miniscule amount of water exerts significant control over various hydrological, ecological, and meteorological processes ranging from boundary layer dynamics to the global water cycle.
Abstract: For each kilogram of water on Earth, only 1 mg is stored as soil moisture. Yet this miniscule amount of water exerts significant control over various hydrological, ecological, and meteorological processes ranging from boundary layer dynamics to the global water cycle. The 1993 Mississippi River flood illustrated the power of 0.0001% of Earth's water to dictate the fate and evolution of regional weather and climate.
The space-time distribution of soil moisture is a key component in describing transfer and distribution of mass and energy between the land and the atmosphere. It is a fundamental variable in biosphere-atmosphere transfer, biogeochemistry, ecosystem process, and rainfall-runoff models. There is a growing consensus that a unified approach is necessary to monitor, characterize, and model soil moisture over a range of scales, but such an approach has yet to be defined.
TL;DR: A joint Japanese-French program (New STARMER) sampled active hydrothermal sites near the New Britain active subduction zone in the South Pacific from October 16 to November 13, 1995 as mentioned in this paper.
Abstract: A joint Japanese-French program (New STARMER) sampled active hydrothermal sites near the New Britain active subduction zone in the South Pacific from October 16 to November 13, 1995. Using the R/V Yokosuka and the submersible Shinkai 6500, researchers made a number of surprising findings about magmatic, tectonic, and hydrothermal activity at the central and northeastern ridges of the Manus Basin spreading system. Fifteen dives by the submersible revealed a spectrum of hydrothermal processes, ranging from shimmering waters to black smokers. For the first time, highly acidic fluids rich in H2S and low in temperature (87–118°C) were sampled in the eastern part of the Manus Basin.
TL;DR: Stober et al. as discussed by the authors investigated the conductivity of the Black Forest crystalline rock and the chemical properties of the water within [Stober, 1995] and found that the crystalline basement is more permeable than once thought.
Abstract: The crystalline basement of the Black Forest is under consideration as a possible repository for radioactive waste. Crystalline rock has traditionally been considered impermeable, even though very deep wells such as the Kola well in the former Soviet Union have been found to contain open, water-filled fissures at more than 12,000 m depth. In 1995, researchers investigated the conductivity of the Black Forest crystalline rock and the chemical properties of the water within [Stober, 1995] and found that the crystalline basement is more permeable than once thought. Hydrogeologic evidence revealed the presence of several thermal and mineral water springs in the crystalline rocks, suggesting that the region may be especially poorly suited for the radioactive waste repository.