摘要:

For the third consecutive year, AGU has published Geophysics News, a collection of short articles about new research findings from the past year. The purpose of Geophysics News is to bring a sampling of the most significant research stories to light each year in a form that is readily accessible to journalists. It is hoped that Geophysics News will encourage journalists to develop these stories for circulation to the general public. As an integral part of AGU's public information program, Geophysics News ultimately seeks to better inform the public about the year's most significant research results in the Earth and space sciences.

ISSN:0002-8606    

DOI:10.1029/EO074i002p00017-01

年代:1993

数据来源: WILEY

摘要:

Several incorrect e‐mail address were printed in theAGU Handbook(Eos, December 8, 1992

ISSN:0002-8606    

DOI:10.1029/EO074i002p00018-02

年代:1993

数据来源: WILEY

摘要:

The Joint Workshop on New Technologies for Lunar Resource Assessment, sponsored by NASA, the Department of Energy, and the Lunar and Planetary Institute, was held in Santa Fe, N.Mex., from April 6 to 7. The workshop grew out of discussions between Los Alamos National Laboratory and the NASA Johnson Space Center in which it was realized that new technologies useful in assessing lunar resources might exist, and that these technologies could extend beyond the usual NASA circle of experimenters and investigators. We also realized that non‐NASA people could probably use some information on NASA needs and requirements as well as some general background technical information about the Moon.The purpose of the workshop was to bring together a number of experts from NASA, DOE national laboratories, industry, and the university community to address topics related to the exploration for and assessment of lunar resource

ISSN:0002-8606    

DOI:10.1029/93EO00082

年代:1993

数据来源: WILEY

摘要:

The isotopic and elemental compositions of groundwater are influenced by climatic conditions at the time of recharge and are therefore indicators of climate change. The potential of aquifers as archives of paleoclimate was discussed at a 3‐day conference held at Lamont‐Doherty Geological Observatory, Palisades, N.Y., from May 18 to 20. About forty scientists from nine countries attended the meeting, which was sponsored by the Northeast Regional Center of the National Institute for Global Environmental Change (NIGEC) and the National Science Foundation. Fifteen invited papers were presented, which formed the background of extensive discussions on applying isotopic methods to deriving information on climate change during the last 30,000 years from the groundwater arch

ISSN:0002-8606    

DOI:10.1029/93EO00212

年代:1993

数据来源: WILEY

摘要:

The beginnings of fractals can be traced to hydrologic studies, dating back to the late 1960s with Mandelbrot's description of river flow as a self‐similar process. Early applications of fractal concepts included the description of the length of coastlines and fracture patterns in the spatial domain, and river discharge in the temporal domain. Recent efforts to apply fractal concepts to hydrologic phenomena have produced new organizing principles for understanding the life cycle of water on Earth as it affects the terrestrial landscape and subterranean geologic deposits.Fractal mathematics offers a natural way to describe irregular patterns if they contain fine structure that is encountered repeatedly over a range of spatial or temporal scales [Meakin,1991]. Like the objects of classical geometry—circles and spheres—the objects of fractal geometry are idealizations that are only approximated in natural systems, but are nonetheless useful for mathematical description [Guyon and Stanley,

ISSN:0002-8606    

DOI:10.1029/93EO00226

年代:1993

数据来源: WILEY

摘要:

Most specialists now agree that the average temperature at the Earth's surface has increased by about half a degree Celsius since the beginning of the 20th century. The cause of this global warming, however, is a matter for intense debate and controversy, ranging from one extreme attributing it all to the increasing greenhouse effect brought about by human activities, to the opposite position attributing the warming to natural climate variability. Some model calculations have shown that the greenhouse effect can account for the size of the observed temperature increase, but the models are still relatively crude and cannot account for the shape of the increase. As a result, most researchers now think that some combination of natural and anthropogenic causes is at work.

ISSN:0002-8606    

DOI:10.1029/93EO00218

年代:1993

数据来源: WILEY

摘要:

Changes in the distribution of solar radiation received on Earth, as a result of the planet's orbital variations, are well‐established as the pacemaker of Pleistocene climate change [Hays et al,1976]. However, several hypotheses suggest that these radiation changes cannot account by themselves for the manner in which the ice ages wax and wane. New evidence clearly defines the role of deep ocean circulation during the last deglaciation and supports a stronger connection between deep ocean circulation changes and warming trends.Considering only the effect of solar radiation, climate change such as the transition from the last ice age to the present should occur gradually over several thousand years and should be out of phase in the Northern and Southern hemispheres. However, the last deglaciation was composed of two distinct steps, each of which lasted less than 1 kyr [Fairbanks,1989] and, apparently, was “felt” synchronously between the hemispheres. Hypotheses proposed to explain this most recent climate change focus either on changes in the level of greenhouse gases, such as CO2, methane, and water vapor, or on large‐scale ocean circulation, which delivers heat to high la

ISSN:0002-8606    

DOI:10.1029/93EO00216

年代:1993

数据来源: WILEY

摘要:

Until recently, virtually all studies of changes and projected changes of near‐surface temperature focused on the mean temperature. This value is often derived from the average of temperatures selected at various times of the day or from the daily maximum and minimum. Information on mean temperatures has been exchanged throughout the world and, in many areas, it extends back for well over a century. Unfortunately, even elementary observations such as the daily maximum and minimum temperatures have not been routinely available, despite their fundamental importance to understanding the impact of climate change in such spheres as agriculture, water resources, and the atmospher

ISSN:0002-8606    

DOI:10.1029/93EO00221

年代:1993

数据来源: WILEY