摘要:

Satellite altimetry continues to have an extraordinary impact on the Earth sciences. It is sure to be considered the most important new observing tool for marine geophysics and geology to emerge in recent times. Spacecraft that have used and are currently using radar altimeters to map sea‐surface topography, and thereby marine gravity, include Geos‐3, Seasat, Geosat, ERS‐1, and Topex/Poseidon. To date, however, only Geosat altimeter data have possessed both the accuracy and density of coverage necessary to clearly resolve tectonic details in the marine gravity field on a global

ISSN:0002-8606    

DOI:10.1029/93EO00249

年代:1993

数据来源: WILEY

摘要:

Richard S. Greenfield has been appointed director of the Division of Atmospheric Sciences at the National Science Foundation. The February 4 announcement was made by Robert W. Correll, assistant director for geosciences.Greenfield began his career at NSF in 1974 as program director for the Global Atmospheric Research Program (GARP), where he coordinated NSF support of academic participation in the GARP Atlantic Tropical Experiment (GATE) in association with the National Oceanic and Atmospheric Administration. Subsequently, he directed participation in the Monsoon Experiment (MONEX) and Alpine Experiment (ALPEX) as the U.S. focal point for each of those projects.

ISSN:0002-8606    

DOI:10.1029/93EO00343

年代:1993

数据来源: WILEY

摘要:

James R. Stahmann, 70, died on October 3. He had been a member of AGU (Atmospheric Sciences) since 1970.David George Dorandied recently at age 49. He joined AGU (Hydrology) in 1975.

ISSN:0002-8606    

DOI:10.1029/EO074i008p00083-01

年代:1993

数据来源: WILEY

摘要:

The National Science Foundation has made funds available to support U.S. scientists' travel to the International Workshop on Intraplate Volcanism, to be held in Tahiti, French Polynesia, in August. Travel grants in the amount of $1,000 can be obtained by writing to the U.S. members of the organizing committee, c/o Marcia McNutt, 54‐826 MIT, Cambridge, MA 02139. Include a copy of your abstrac

ISSN:0002-8606    

DOI:10.1029/93EO00347

年代:1993

数据来源: WILEY

摘要:

The new FG5 absolute gravimeter has a design goal accuracy of 1 μGal and represents the most recent of a series of gravimeters inspired by advances in gravimeter design by J. Faller at the Joint Institute for Laboratory Astrophysics (JILA) in Boulder, Colo. A 2‐day workshop will be held in Boulder from March 22 to 23 to discuss current and future applications of absolute gravity (g). Details of the workshop appear at the end of this article. The instrument is based on the principle of interferometrically measuring the time and position of a weight falling in a vacuum, using a stabilized laser and an atomic clock [cf.Cook, 1967;Faller, 1963;Hammond, 1970;Zumberge, 1981;Niebauer, 198

ISSN:0002-8606    

DOI:10.1029/93EO00349

年代:1993

数据来源: WILEY

摘要:

As part of a European multinational collaboration, 1104 km of deep seismic reflection data were collected in the Mediterranean Sea during February and March 1992 under the technical supervision of the British Institutions Reflection Profiling Syndicate (BIRPS), based at the University of Cambridge. The surveys were centered over the southern Ionian Sea between Italy and Greece and over the Valencia trough and Balearic ridge offshore Spain (Figure 1).Principal funding for data acquisition was provided by the European Economic Community under the auspices of Project STREAMERS and by the Consejo Superior de Investigaciones Cientificas (CSIC) in Barcelona, respectively. The STREAMERS Project, coordinated by Alfred Hirn at the Institut de Physique du Globe de Paris, is based on a collaboration between the Institut Physique du Globe de Paris, Istituto di Miniere e Geofisica Applicata Universita' Degli Studi Trieste, Public Petroleum Corporation of Greece, the University of Athens, the University of Lisbon, the CSIC, and the BIRPS team (Universities of Cambridge, College Wales, East Anglia, Leicester, and London).

ISSN:0002-8606    

DOI:10.1029/93EO00243

年代:1993

数据来源: WILEY

摘要:

Stephen J. Gould [1987] argued that one of the greatest scientific realizations was the concept of “deep time,” a phrase coined by John McPhee to encompass the breadth of geological time. We rely on measurements of geological time to provide rates of geological and geophysical processes and a chronology for the evolution of the Earth. Geological measurements of deep time rely on a limited number of radiometric ages that provide the only true clocks. Our chronometer is the geological time scale, and it is based on these ages and interpolations between them. The most precise ruler for these interpolations is provided by minor variations in the Earth's orbit, which control solar insolation and global climate changes; this “astronomical pacemaker” has provided a precise chronology (one with 5,000‐year resolution) for the past few million years. It has proven difficult to extend this astronomical time scale to the geological record older than about 5 m.y. However, for the Late Cretaceous to Pleistocene (approximately the last 150 m.y.), another ruler is available: reversals of the Earth's magnetic field provide a Geomagnetic Polarity Time Scale (GPTS) that serves as a framework for a limited number of radiome

ISSN:0002-8606    

DOI:10.1029/93EO00231

年代:1993

数据来源: WILEY

摘要:

With the spread of nuclear weapons technology, more regions of the world need to be monitored in order to verify nuclear nonproliferation and limited test‐ban treaties. Seismic monitoring is the primary means to remotely sense contained underground explosions “Bolt, 1976;Dahlman and Israelson, 1977”. Both underground explosions and earthquakes generate seismic energy, which propagates through the Earth as elastic waves. The crux of the verification problem is to differentiate between the seismic signatures of explosions and earthquakes. Such identification is most difficult in countries with seismically active areas, where bombs might be detonated to blend in with the region's natural seism

ISSN:0002-8606    

DOI:10.1029/93EO00229

年代:1993

数据来源: WILEY

摘要:

The release of trace gases such as carbon dioxide and methane through human activity is generally accepted to have the potential to alter the Earth's climate. Various projections indicate that present concentrations of these “greenhouse” gases will double by the end of the 21st century. Studies of the atmospheric effect of these gases suggest that the globally averaged temperature of the troposphere (0–10 km altitude) will increase by about 1‐5°K because of an increase in trapped infrared radiation. In the stratosphere (10–50 km), however, the increased concentration of these gases will give rise to a greater infrared cooling to space, and the globally averaged temperature is predicted to cool by 10–20°K, compared with present‐day temperatures [Brasseur and Hitchman, 1988]. It should be stressed that this latter prediction applies to the upper atmosphere, and does not address greenhouse warming in the lower atmosphere, which has been treated by other c

ISSN:0002-8606    

DOI:10.1029/93EO00233

年代:1993

数据来源: WILEY