摘要:

Particle beams released from space vehicles provide a unique way to study many problems in basic plasma physics in the ionosphere and magnetosphere. Electron beams, for example, may act as probes or tracers in the large‐scale magnetosphere but also generate waves, plasma heating, and current systems in the local ionosphere. Such experiments are a natural extension of laboratory plasma physics to a regime where there are no walls, but where a high degree of control may still be achieved.The first electron beam experiment in space was the Hess Artificial Aurora Experiment [Hess et al., 1971], which was launched in 1969 from the NASA Wallops Island Range, Wallops Island, Va., not only to generate auroral streaks but to map magnetic field lines between conjugate regions above the Earth's surface. This was followed in 1970 by ECHO 1, also from Wallops. Since that time, a multitude of electron beam experiments have been carried out on sounding rockets, and some at orbiting altitudes on the Space Shuttle. In the ECHO program, six additional experiments have been flown, culminating in ECHO 7, which is the subject of this paper and the last of the series. The history of the subject up to 1980 has been covered in a review paper [Winckler, 1980]. Particle beams in space plasmas were the subject of an extensive symposium in 1981 [Grandal, 1982]. This symposium includes a review of ECHO results [Winckler, 1982].Abe et al.,[1988] have analyzed ELF wave generation observed during the previous flight, ECHO 6, and referenced recent papers under the ECHO progra

ISSN:0002-8606    

DOI:10.1029/89EO00194

年代:1989

数据来源: WILEY

摘要:

Citation analysis has become an important tool for assessing the impact of scientific publications, and one of its applications is the evaluation of different journals. The Institute for Scientific Information publishes annual reviews of the journals it covers in terms of different scientometric indices. One of them is the impact factor, defined as the number of citations in the given year of the articles published in a particular journal in the preceding 2 years. Thus the impact factor can be defined as the average number of citations of an article in the second year after its publication.

ISSN:0002-8606    

DOI:10.1029/89EO00195

年代:1989

数据来源: WILEY

摘要:

Much progress has been made in our understanding of the Cretaceous/Tertiary (K/T) and other extinction events throughout Phanerozoic time. Scenarios for the K/T extinctions have been outlined. Suggested exogenic causes include a large asteroid impact or a number of smaller impacts over a year or soon both continental and oceanic terranes, or a comet shower of six to ten impacts over a 1‐ to 3‐m.y. period. Suggested endogenic causes include the environmental effects of a major sea level regression and intense global volcan

ISSN:0002-8606    

DOI:10.1029/89EO00405

年代:1989

数据来源: WILEY

摘要:

Chemistry of the Natural Atmospherefills an important gap in the literature of atmospheric chemistry. While local and regional air pollutions have been o f concern for a long time and many books discuss the chemistry, physics and engineering of urban air pollution, there are few texts that treat atmospheric chemistry in broad interdisciplinary terms. The available literature typically deals with localized problems and is usually written for a limited scientific audience, mainly chemists or meteorologists. The natural global background atmosphere has been neglected, despite the fact that without such knowledge it is impossible to assess the impact of human activity on the atmosphere.

ISSN:0002-8606    

DOI:10.1029/89EO00197

年代:1989

数据来源: WILEY

摘要:

The Hess Medal of the American Geophysical Union is conferred on A. G. W. Cameron for his extraordinary pioneering contributions to the theory of nuclear synthesis in the development of the solar nebula from the interstellar medium, and the formation of the Sun, the planets, the Moon, and the comets. The concepts which he has developed have served as a principal intellectual guide to the exploration of the Solar System and the isotopic and chemical studies of meteorites. His stimulating ideas and extensive theoretical works are tied together in a syncretic approach that has and does receive the attention and respect o f scholars of all sections of the Union. In particular, this award of the Hess Medal places emphasis on an outward view of the Solar System to consider its full cosmic significance.

ISSN:0002-8606    

DOI:10.1029/89EO00199

年代:1989

数据来源: WILEY

摘要:

To maximize our ability to obtain recognition of Ocean Sciences Section members as Fellows of AGU while minimizing the associated workload, I have, in consultation with our executive committee, established an Ocean Sciences Fellows Committee chaired by the President‐Elect to oversee and assist in the nomination process.The committee asks that anyone wanting to sponsor a nomination send a one‐page proposal telling why an individual should be made a Fellow. Proposals will be reviewed by the commitee, and a number equal to 1 ½ to 2 times our nomination quota will be chosen for full presentation. Committee members will then work with nominators to select and contact seconders, while the nominator provides the required curriculum vitae and publication list. The committee will assist in any manner possible to insure that the files that go forward are both timely and well docume

ISSN:0002-8606    

DOI:10.1029/89EO00201

年代:1989

数据来源: WILEY