Showing papers in "Eos, Transactions American Geophysical Union in 1998"

New, improved version of generic mapping tools released

Abstract: Version 31 of the Generic Mapping Tools (GMT) has been released More than 6000 scientists worldwide are currently using this free, public domain collection of UNIX tools that contains programs serving a variety of research functions GMT allows users to manipulate (x,y) and (x,y,z) data, and generate PostScript illustrations, including simple x-y diagrams, contour maps, color images, and artificially illuminated, perspective, and/or shaded-relief plots using a variety of map projections (see Wessel and Smith [1991] and Wessel and Smith [1995], for details) GMT has been installed under UNIX on most types of workstations and both IBM-compatible and Macintosh personal computers

Biogeochemistry, An Analysis of Global Change

Abstract: Compared to the well-established disciplines, the field of Earth system science/global change has relatively few books from which to choose. Of the small subset of books dealing specifically with biogeochemical aspects of global change, the first edition of Schlesinger's Biogeochemistry in 1991 was an early entry. It has since gained sufficient popularity and demand to merit a second, extensively revised edition. The first part of the book provides a general introduction to biogeochemistry and cycles, and to the origin of elements, our planet, and life on Earth. It then describes the functioning and biogeochemistry of the atmosphere, lithosphere, biosphere, and hydrosphere, including marine and freshwater systems. Although system function and features are stressed, the author begins to introduce global change topics, such as soil organic matter and global change in Chapter 5, and landscape and mass balance in Chapter 6.

The Antarctic Region: Geological Evolution and Processes

Abstract: The Scientific Committee on Antarctic Research (SCAR) supports discipline- and issue-based meetings in Antarctic research, and these are forums for announcing developments in Antarctic science. Refereed symposia proceedings normally follow and generate a number of volumes that almost constitute serial publication. Meetings in the Earth sciences occur at roughly 4-year intervals. The resulting volumes cover Antarctic Earth science generally and provide convenient access to periodic bibliographic updates. The Antarctic Region: Geological Evolution and Processes is a collection of the Proceedings of the VII International Symposium on Antarctic Earth Sciences, held in Siena, Italy, in 1995 and sponsored by SCAR. It was by far the largest such meeting held to date—the next will be in New Zealand in 1999—but the book, even as large as it is, contains only a portion of the papers presented.

Identifying Marine Phytoplankton

Abstract: Until recently, anyone who needed to accurately identify marine phytoplankton had one of four choices: use the outdated Englishlanguage volumes by E. E. Cupp and N. I. Hendey plus the more recent book by J. Dodge, acquire a working knowledge of German and use the old volumes by Schiller and Hustedt, spend huge amounts of time in an exceedingly well-equipped marine science library trying in vain to keep up with the rapidly evolving field of phytoplankton systematics and taxonomy, or track down one of the rarest of endangered species—a phytoplankton taxonomist—and beg for help. To these unfortunate choices is added one considerably more hopeful: Identifying Marine Phytoplankton. This volume, which has seven contributing authors, contains most of the taxonomic groups that make up the planktonic autotrophs and some heterotrophs of the seas, coasts, and estuaries of the world (missing are cyanobacteria and some of the picoplankton groups).

Rock Magnetism: Fundamentals and Frontiers

Abstract: Most observers of the geophysical scene, those involved with plate tectonics and continental drift in particular, are aware of the seminal contributions of rock magnetism and its sister discipline, paleomagnetism, which some have called “applied rock magnetism.” That was in the heady days of the 1960s. As a discipline, however esoteric, rock magnetism goes further back to the 19th century when the Swedish prospectors for iron ores and Italian and German paleomagnetists in search of the history of the geomagnetic field were using rock magnetism as an exciting new tool. The first book on rock magnetism, Der Gesteinsmagnetismus by H. Haalck, was published in 1942, more than a decade before T. Nagata's Rock Magnetism, cited by Dunlop and Ozdemir as the earliest work on the subject. There have been more recent volumes on the subject, including one that I coauthored with Frank Stacey. However, I am not exaggerating when I say that Rock Magnetism: Fundamentals and Frontiers leaves the others in the dust.

Gravity Currents in the Environment and the Laboratory

Abstract: A large variety of geophysical phenomena can be considered examples of gravity currents, normally thought of as the horizontal or quasihorizontal penetration of a light fluid by a plume of denser fluid. In Gravity Currents in the Environment and the Laboratory, Simpson discusses both the basic physics and real-world applications of gravity currents and related phenomena such as hydraulic jumps, undular bores, and the spread of buoyant plumes. This book is a considerable expansion of an earlier edition published a decade ago and represents the accumulated wisdom of a career devoted to observation and laboratory simulation of small-scale environmental fluid mechanical phenomena. The result can be recommended enthusiastically both to experts in the field and readers who have more general interests in meteorology, oceanography, or other areas of fluid mechanics.

Antarctic Meteorology and Climatology

Abstract: Antarctica is the coldest of the continents and the most remote. Both of these facts pose problems for meteorologists. The lack of easy access to most of the continent presents significant obstacles to effective data collection, and the often hostile conditions make accurate, believable measurements difficult to obtain. Nonetheless, as the authors point out in the preface of Antarctic Meteorology and Climatology, the last decade has seen a great increase in both the quantity and quality of data available in the Antarctic region, making this book a timely review of the state of knowledge of the Antarctic climate system. The reader will not find extensive discussion of the “ozone hole” or of paleoclimate records here. Rather, what the reader does find is a comprehensive and smoothly written account of the present and recent past climate of the Antarctic troposphere in its many aspects.

Plate Tectonics and Crustal Evolution

Abstract: Ever since plate tectonics revolutionized Earth science, university courses presenting Earth processes in the framework of plate tectonics have become as plentiful as earthquakes. Consequently, this segment of the textbook market, which includes popular classroom classics such as Keary and Vine's Global Tectonics, is heavily contested. Condie's book attempts to secure a portion of the pie by targeting advanced undergraduates, graduate students, and specialists “who want to keep abreast of scientific advances in this field,” as stated in the preface.

Disturbed space environment may have been related to pager satellite failure

Abstract: A very intense flux of electrons, evident in the magnetosphere earlier this year, may have caused a satellite failure (or at least exacerbated the situation) leading to the loss of pager service to 45 million customers, research has shown. The electrons, known as highly relativistic electrons (HREs), were especially numerous in the weeks preceding the failure. Researchers say HREs have triggered spacecraft anomalies in the past through a process of deep dielectric charging when fluxes are elevated. They therefore believe this energetic electron environment could have been behind the failure in the attitude control system of the Galaxy 4 spacecraft at 2200 UT on May 19,1998. A backup system also failed, either at the same time or earlier, so operators were unable to maintain a stable Earth link [Silverstein, 1998].

Introduction to Geostatistics: Applications in Hydrogeology

Abstract: Our efforts to understand the physical, chemical, and biological processes involved in groundwater flow, contaminant transport, and site remediation are made challenging by the limited access we have to the subsurface environment in which they occur. While some recent research projects have collected data that are relatively high in temporal and spatial resolution, at the sites of many environmental investigations the resolution of the data is limited. For this reason, geostatistics has been integrated with hydrogeology to provide methods for quantifying uncertainty where estimation, interpolation, and extrapolation of hydrogeologic attributes are required between and beyond data locations. Hydrogeologic attributes generally do not vary in a maximally disordered fashion but have both random and structured qualities, both of which can be represented by geostatistical models.

Martian soil simulant available for scientific, educational study

Abstract: Just as the world is entering an intensive and exciting phase in the exploration of Mars, a Martian soil simulant has been developed for use in scientific research, engineering studies, and education. Called JSC Mars-1, it is a natural material obtained from volcanic ash. It approximates, within the limits of current understanding, the reflectance spectrum, mineralogy, chemical composition, grain size, density, porosity, and magnetic properties of the oxidized soil of Mars. This material is offered in limited quantities to qualified investigators and educators, without charge except for shipping.

Beach Processes and Sedimentation, Second Edition

Abstract: Anyone who has ever ventured to a beach has without a doubt watched in wonder, if not awe, what waves, tides, and currents may produce—or destroy—over timescales ranging from minutes to millennia. The second edition of Beach Processes and Sedimentation clearly and succinctly explains the physical processes responsible for shaping our coastlines. The material is presented at a level suitable for advanced undergraduates with backgrounds in physical science and beginning graduate students in any marine science discipline, including those interested in coastal management or policy. It will also serve as a valuable reference for those who have left their student years behind and for whatever reason find themselves in need of a reintroduction to beach dynamics.

Yellow River's water and sediment discharge decreasing steadily

Abstract: The amount of water and sediment discharged by the Yellow River in northern China has been decreasing steadily over the past 20–25 years, such that in recent years it has contributed relatively little sediment to the Gulf of Bohai. This is quite at odds with the well-known story in which the Yellow River has been regarded as a primary contributor of fluvial sediment to the global ocean. If the trend of decreasing discharge continues, the environmental and economic impacts to the Yellow River delta and adjacent coastal waters could be dramatic. Already shrimp harvest from the brackish waters of the western Gulf of Bohai has decreased markedly, and there has been considerable coastal retreat along parts of the delta.

Influence of Mediterranean Outflow on climate

Abstract: A cover article in Eos last year [Johnson, 1997] called for a dam across the Strait of Gibraltar to prevent a new Ice Age. In this article, R. G. Johnson argued that reduced Nile River flow after building the Aswan Dam increases Mediterranean Sea salinity, leading to enhanced outflow of salty water into the Atlantic Ocean. This, in turn, would alter the thermohaline (that is, temperature and salinity driven) circulation of the Atlantic, heat up the Labrador Sea and enhance evaporation there, and increase snowfall in Canada until a new ice sheet builds up. Ocean circulation model experiments, however, suggest that this fear is unfounded. While Mediterranean saltwater outflow (Figure 1a) does appear to have some effect on North Atlantic circulation and surface climate, the change in Mediterranean salt budget resulting from the Aswan Dam is far too small to have any noticeable impact.

Aquifer Hydraulics: A Comprehensive Guide to Hydrogeologic Data Analysis

Abstract: The past several decades have produced a surge in numerical methods of aquifer analysis, including more complex and sophisticated analytical approaches. For example, many consulting firms and universities have released graphic-intensive software packages for aquifer test data analysis, including automated optimization, data filtering, and preprocessing. It is not uncommon to find users of these products who are not versed in basic theory of aquifer hydraulics. Vedat Batu's Aquifer Hydraulics: A Comprehensive Guide to Hydrogeologic Data Analysis provides a valuable service—it teaches readers the most fundamental theory with a comprehensive overview of basic methods.

Advisor, Teacher, Role Model, Friend: On Bring a Mentor to Students in Science and Engineering

Abstract: Mentorship is one of the fundamental keys to growth and learning in any field, not just science. But our profession is unusual to the degree in which mentoring is used to guide and develop scientists, especially during the years of graduate school. While the Ph.D. advisor is rarely the sole mentor in a student's life, the success or failure of this relationship can literally make or break a young scientist. Most advisors I talk to believe they do an effective job of mentoring their students. Most students I talk to disagree.

Geomagnetic field excursions occurred often during the last million years

Abstract: Scientists studying western North Atlantic Ocean deep-sea sediments have discovered that the Earth's magnetic field underwent 14 local excursions since the last global magnetic-field polarity reversal 780,000 years ago These excursions coincide with similar excursions identified elsewhere on the planet—leading to the conclusion that excursions are global in nature, occur a significant portion of the time, and are an integral part of geomagnetic field secular variation between reversals Excursions are defined [Verosub and Banerjee, 1977] as anomalous magnetic field directions whose equivalent virtual geomagnetic poles (VGPs) are more than 45° away from the North Geographic Pole, while VGPs within 45° of the North Geographic Pole are considered to be typical secular variation (VGPs are calculated from local magnetic field directions which locate the magneticfield North Pole by assuming that the directions are caused by a simple dipole or bar magnet situated at the center of the Earth)

Detailed look at final stage of plate break‐off is target of study in Romania

Abstract: Geophysical experiments next year in Romania may provide insight into a common but short-lived seismic process that can be observed and understood at only one spot on Earth at present. About 150 stations will be set up in the Vrancea area in the southeast Carpathian Mountains to, in effect, record the terminal phase of the detachment of a subducting slab of oceanic lithosphere. This is a major regional tomographic study using a large number of broadband seismometers, which will operate for 6 months. Images will be used for hazard assessment as well as for a delineation of detachment history. Active subduction of oceanic lithosphere at convergent plate boundaries involves earthquakes, magmatism, metamorphism, and deformation—some of the most vivid manifestations of any plate tectonic process. The initiation and termination of subduction, however, remains relatively poorly understood. When convergence of lithospheric plates ceases and the suction force of the subducting plate becomes negligible, the subducting slab moves into an almost vertical position. If subduction occurs in an arcuate geometry, the slab is likely to be segmented.

Monsoons boost biological productivity in Arabian Sea

Abstract: Monsoons over the Arabian Sea—the oceanic basin that separates the Arabian peninsula from the Indian subcontinent—follow seasonal cycles, reversing directions twice a year, in summer and winter. Rather than spreading across the expanse of the sea, the southwest (summer) monsoon is often concentrated into a jet over the central Arabian Sea. Evidence suggests that variations in wind stress force substantial upwelling in the ocean to the west of the jet, and weaker upwelling or even downwelling to the east. This upwelling provides nutrients to the euphotic zone and enhances biological productivity.

Airborne Salinity Mapper Makes Debut in Coastal Zone

Abstract: New technology has been developed through a joint public-private partnership that could greatly improve the ocean sciences community's ability to study coastal oceanography in the same way that satellitebased infrared imaging revolutionized basinscale oceanography. Recent advances in passive microwave technologies and novel means of integrating those advances haveled to the development of the Scanning Low-Frequency Microwave Radiometer (SLFMR) for remote sensing of sea-surface salinity. Designed and built for the National Oceanic and Atmospheric Administration (NOAA), the SLFMR—also known as the salinity mapper—was recently used by a team of scientists from government and industry to generate the first remotely sensed image of sea-surface salinity (Figure 1). This image of salinity was obtained near the mouth of Chesapeake Bay, Virginia, during the Naval Research Laboratory's (NRL) Chesapeake Outflow Plume Experiment (COPE), elements of which were conducted in collaboration with NOAA.

Satellite monitoring of remote volcanoes improves study efforts in Alaska

Abstract: Satellite monitoring of remote volcanoes is greatly benefitting the Alaska Volcano Observatory (AVO), and last year's eruption of the Okmok Volcano in the Aleutian Islands is a good case in point. The facility was able to issue and refine warnings of the eruption and related activity quickly, something that could not have been done using conventional seismic surveillance techniques, since seismometers have not been installed at these locations. AVO monitors about 100 active volcanoes in the North Pacific (NOPAC) region, but only a handful are observed by costly and logistically complex conventional means. The region is remote and vast, about 5000 × 2500 km, extending from Alaska west to the Kamchatka Peninsula in Russia (Figure 1). Warnings are transmitted to local communities and airlines that might be endangered by eruptions. More than 70,000 passenger and cargo flights fly over the region annually, and airborne volcanic ash is a threat to them. Many remote eruptions have been detected shortly after the initial magmatic activity using satellite data, and eruption clouds have been tracked across air traffic routes. Within minutes after eruptions are detected, information is relayed to government agencies, private companies, and the general public using telephone, fax, and e-mail. Monitoring of volcanoes using satellite image data involves direct reception, real-time monitoring, and data analysis. Two satellite data receiving stations, located at the Geophysical Institute, University of Alaska Fairbanks (UAF), are capable of receiving data from the advanced very high resolution radiometer (AVHRR) on National Oceanic and Atmospheric Administration (NOAA) polar orbiting satellites and from synthetic aperture radar (SAR) equipped satellites.

Glaciers receive a surge of attention in the Karakoram Himalaya

Abstract: Between 1994 and 1996 catastrophic movement of the 15.5-km-long Chiring Glacier transferred 1-1.5 km3 of ice from its upper two thirds to its lower third, and into the main Panmah Glacier of which it is a tributary. By October 1996, a lobe of Chiring ice some 3.2 km2 in area had entered and compressed the main glacier, which was severely disturbed for 3 km above and 5 km below the junction of the glaciers (Figure 1). Ice streams and medial moraines were pushed into a series of looped or “tear-drop” forms, well-known in the surging glaciers. Despite an observational record back to 1856, it was not previously realized that changes in the glacier involve surging.

Why the United States is becoming more vulnerable to natural disasters

Abstract: The United States is becoming more vulnerable to natural hazards mostly because of changes in population and national wealth density—more people and more societal infrastructure have become concentrated in disaster-prone areas For most of the 20th century, the United States has been largely spared the expense of a catastrophic natural disaster A great earthquake (magnitude 8 or larger) has not struck a major metropolitan area since the 1906 San Francisco earthquake An extreme or catastrophic hurricane (Class 4 or 5) has not struck directly a major urban area since the one that hit Miami, Florida, in 1926 Yet even without such disasters, which might create losses well over $100 billion, the overall costs of natural hazards, such as extreme weather, drought, and wildfires, are estimated at $54 billion per year for the past 5 years, or approximately $1 billion per week [National Science and Technology Council, 1997]

Fractals and Chaos in Geology and Geophysics, Second Edition

Abstract: Fractals and Chaos in Geology and Geophysics, Second Edition, is the best technical introduction to chaos known to me. It is suitable not only for geologists, but for anyone who is seriously interested in the subject. The title of the book is misleadingly narrow; its content would be better described by the unwieldy title “Concepts and Application of Chaos Theory,” with an even longer subtitle “Examples Taken Predominantly from the Earth Sciences.” The mathematics are simple; a second-year college student should be fully capable of handling the book.

Preconceptions abound among students in an introductory earth science course

Abstract: Although the Third International Mathematics and Science Study found that most 8th-grade students like science and feel that they are doing well in it [Geary, 1997], fewer than one-quarter of U.S. adults can define the term DNA and only one in 11 knows what a molecule is [Augustine, 1998]. Hence the motivated, bright young people described by the study somehow become scientific illiterates despite the best efforts of elementary, secondary, and college-level instructors. This phenomenon has prompted various investigations into reasons why students have difficulty learning science. One possibility is illustrated by the famed video [Shapiro etal, 1988] showing that most of the graduating Harvard seniors surveyed confidently attributed the cause of the seasons to changes in the distance between the Earth and Sun rather than to the Earth's tilt. They had a clear conception of the answer, but it was wrong.

Isotopic fingerprinting may provide insights into evolution of magmatic systems

Abstract: A simple method may provide greater insights into the sort of pathways and time-scales in which magmatic systems evolve. The method, employing isotopic fingerprinting of the mineral components that characterize most magmatic rocks, may lead to a more comprehensive understanding of these types of rocks. Such an understanding is critical to resolving fundamental problems in geoscience, ranging from the origin and differentiation of the crust and mantle to the prediction of volcanic hazards. Much progress has been made in the past 30 to 40 years, first with the widespread application of experimental studies on natural and synthetic systems, and more recently with the application of chemical and isotopic constraints on the origin of igneous rocks. Despite this progress, however, many questions remain, and that is where isotopic fingerprinting may help.

Study provides data on active plate tectonics in southeast Asia region

Abstract: A major geodynamic study has provided significant new information about the location of active plate boundaries in and around Southeast Asia, as well as deformation processes in the Sulawesi region of Indonesia and tectonic activity in the Philippine archipelago. Results also have confirmed the existence of the so-called Sunda Block, which appears to be rotating with respect to adjacent plates. The study, known as the Geodynamics of South and South-East Asia (GEODYSSEA) project, has been a joint venture of the European Commission and the Association of South- East Asian Nations. It began in 1991 and involved a large team of European and Asian scientists and technicians studying the complex geodynamic processes and natural hazards of the region from the Southeast Asia mainland to the Philippines to northern Australia. Earthquakes, volcanic eruptions, tsunamis, and tectonically induced landslides endanger the lives of millions of people in the region, and the tectonic activity behind these natural hazards results from the convergence and collision of the Eurasian, Philippine, and Indo-Australian Plates at relative velocities of up to 10 cm per year.

Paleointensity database updated

Abstract: The updated version of the paleointensity database will be included in the new package that should be released by Mike McElhinny in May 1998. The new version comprises 1692 data records from 115 references. The database tables are also available as ASCII and Excel files via an anonymous ftp site (ftp.dstu. univ-montp2.fr, in the following directory: /pub/paleointdb).