摘要:

The magnetospheric substorm is a collective response of the magnetosphere and ionosphere to a set of conditions in the solar wind. The concept of magnetospheric substorm was first proposed a quarter century ago in a classic paper byAkasofu[1964]. The magnetospheric substorm is unquestionably a global phenomenon produced by the solar wind‐magnetosphere‐ionosphere interaction. It is not a phenomenon of the plasma dynamics in the plasma sheet alone, nor is it exclusively a phenomenon of aurora (“northern lights”) in the upper atm

ISSN:0002-8606    

DOI:10.1029/EO071i038p01083-01

年代:1990

数据来源: WILEY

摘要:

Current research to understand the fate and transport of particulate contaminants in subsurface environments is being conducted from a variety of perspectives. The physical and chemical factors that control microbial movement, the transport of particulate organic material in aquifers, and the mobilization of radionuclides, trace metals, and hydrophobic organic contaminants by colloidal transport are among the many topics being investigated. The transport processes influencing particulates are not limited to physical hydrology; the geochemistry and microbiology of these systems fundamentally influence the transport properties. Because of the recent intense activity in these topics, the special session, “Particle Transport in the Subsurface and its Geochemical Impact,” was convened at the 1990 AGU Spring Meeting held in Baltimore, Md., May 29–J

ISSN:0002-8606    

DOI:10.1029/EO071i038p01084-02

年代:1990

数据来源: WILEY

摘要:

How can we sustain a public sense of the common danger of global change while remaining honest in view of the realities of scientific uncertainty? How can we nurture this sense of common danger without making statements based on half‐baked ideas, statistically unreliable results, or oversimplified models? How can we strike a balance between the need to overstate a case to attract the attention of the media and the obligation to adhere strictly to the ethos of science?The task of achieving a scientific understanding of the inner workings of the terrestrial environment is one of the most difficult and ambitious endeavors of humankind. It is full of traps, temptations and deceptions for the participating scientists. We are dealing with a horrendously complex, strongly interactive, highly non‐linear system. Lessons learned from disciplines such as plasma physics and solid state physics which have been dealing with complex non‐linear systems for decades, are not very encouraging. The first thing one learns is that there are intrinsic, physical limits to the quantitative predictability of a complex system that have nothing to do with the particular techniques employed to mod

ISSN:0002-8606    

DOI:10.1029/90EO00298

年代:1990

数据来源: WILEY

摘要:

The Bergen Avenue Groin in Harvey Cedars, N.J., a storm protection structure that confines alongshore‐moving sediment to create wider beaches, has been found to act as a barrier to longshore sediment transport according to Michael S. Bruno, Stevens Institute of Technology, Hoboken, N.J. Using a wave transformation‐shoreline evolution model, Bruno examined the effectiveness of an existing stone groin on a commercially and historically valuable beach. His findings were summarized at the 21st Union of Panamerican Engineers meeting hosted by the American Association of Engineering Societies held in Washington, D.C., August 19–24.Groins are low, narrow jetties made of timber, stone, concrete, or steel that extend roughly perpendicular to the shoreline. They are designed to protect the shore from erosion by currents, tides or waves, or to trap sand and littoral drift to build up or make a beach. The advantage of a groin is that it is a permanent solution to beach erosion, as opposed to the continuing process of beach replenishment required in nonstructural processes such as beachfills. This same permanence, however, is often the downfall of structural solutions because of the long‐term deleterious consequences associated with such

ISSN:0002-8606    

DOI:10.1029/EO071i038p01090-01

年代:1990

数据来源: WILEY