1997 Spring Meeting Session Highlights

Listed below are brief descriptions of some of the sessions that will be presented at this meeting.


Carl Sagan: His Pioneering Science and Current Studies of Life in Extreme Environments (U21A)

On December 20, 1996, Carl Sagan astronomer, planetary researcher, environmentalist, and popularizer of science died unexpectedly. For thirty years, Sagan and his students have contributed to the fundamental development of planetary and Earth sciences. Sagan was responsible for establishing the basis to carry out radiative and climate studies of the planets. He proposed the super greenhouse effect on Venus, defined the climatic effects of dust storms on Mars, discovered that complex organic compounds are formed in primitive planetary atmospheres, and engineered the first searches for evidence of extraterrestrial life. Sagan also studied the climate of Earth and was instrumental in bringing to light the potential global devastation that might occur through a "nuclear winter." His exceptional books and unique television production, Cosmos, have educated more individuals on the basic concepts and facts of geophysical sciences than perhaps all the works of his colleagues combined. This Union memorial session is a tribute to Carl Sagan's enormous contributions, in both his individual research accomplishments and his highly interdisciplinary approach toward problem solving. Included within this session are presentations on the existence of life in extreme environments: below the ground, in high-temperature regimes, in polar conditions, and the possibility of life on Mars. Much of Carl Sagan's research was dedicated to exploring the potential for life within and beyond our solar system, a field which has acquired great prominence with the recent analyses of Martian meteorites.

Building on the Legacies of the International Geophysical Year (IGY) for the 21st Century (U31A, U31B, U31C, U32A, U32B)

The IGY of 40 years ago created a new mode of international scientific cooperation in the pursuit of knowledge about the habitat of humanity. It stimulated public interest in science and education. The IGY opened the Space Age and was the catalyst for international treaties on Space, Antarctica, and the Test Ban on Nuclear Weapons. The scientific community now has an opportunity to develop an initiative for the 21st century that will leave legacies for science and for society as rich as those left by the IGY. Critical issues in creating a Global Knowledge Strategy to make knowledge the organizing principle for the society in the 21st century are being identified through a March/April E-mail roundtable of interested individuals. These issues will be addressed by two panels on Science: An Endless Frontier and one panel each on Knowledge: An Enabler at the Frontier and Synthesis and Prognosis.

Sea Level Variations: Measurements, Interpretation and Societal Impact (Joint with EGS) (U32C, U41A)

Sea-level variations have always raised the interest and the concern of those living close to the coasts. However, attention from the global community is growing with the detection of a global sea-level rise of the order of 1.0-to-2.5 mm/yr measured over the last century; the linkage of sea-level rise to increasing global temperature and anthropogenic changes to the Earth system are areas of high activity and priority. Climate models suggest that global warming will continue with many impacts to society. The sources of global sea-level rise are not well understood and probably arise from a combination of steric ocean effects and mass redistribution from the

continents to the ocean. Monitoring of sea level may prove to be an important indicator of global warming, especially if an acceleration of the sea-level rise can be detected. This session will be interdisciplinary in nature and should be of interest to oceanographers, geodesists, glaciologists, geophysicists, geologists and those involved in natural hazard research. Papers cover a broad range of areas: measurements of sea-level rise, post-glacial rebound, the effect of tectonics and subsistence on sea-level rise, mass balance studies (e.g., continental glaciers, Greenland and Antarctica) and emerging technologies. Global as well as regional aspects are included with both invited and contributed presentations.

Impact of Natural Hazards on Coastal Zones (U41B, U42B, U51B)

Populations in the U.S. and abroad are becoming increasingly concentrated in coastal areas. These coastal zones are frequently subject to a wide range of natural hazards making populations and infrastructures vulnerable to disaster. Topics covered include: 1) review the several types of natural hazards affecting coastal zones (e.g., severe weather events, tsunamis, earthquakes, volcanic eruptions, and harmful algal blooms); 2) discuss their physical, economical, and societal impact; 3) examine some of the new tools used to study these phenomena; and 4) assess the effectiveness of management and mitigation measures. In the panel discussion associated with this session, the role of research in reducing disasters associated with natural hazards will be addressed.

Shaping the Future of Undergraduate Earth and Planetary Sciences Education (U42A, U51A)

In November, 1996, AGU hosted a workshop sponsored by five National Science Foundation (NSF) Divisions, that challenged workshop participants to develop a set of recommendations using Earth Systems Sciences as a focus. These recommendations area suggested plan for the Earth sciences education community's mission in the 21st century. This session highlights the main issues the workshop participants felt were facing Earth sciences education and presents some of their recommendations and plans for action. Invited papers from the NSF Divisions of Undergraduate Education and Geosciences highlight NSF's plans for the future. Additional contributed papers discuss an Earth systems science approach to earth and planetary sciences instruction as currently in practice.

The Role of Research in Reducing Natural Hazards (U42C)

Research is an integral part of natural disaster reduction. In particular, research is needed in areas where our understanding of the hazard itself is incomplete and/or mitigation tools are not fully developed. Disaster reduction effectiveness differs dramatically from hazard to hazard, as illustrated by differences in our forecasting and mitigating capabilities. These differences serve to shape our research priorities. Representatives from government agencies, academia, and the private sector will describe their present research efforts and future plans. After brief introductory remarks from each panelist, the floor will be open for questions.

Contribution of Satellites to Global Climate Monitoring (U51C, U52A)

By virtue of their global coverage, increasing record lengths, and sophisticated instrumentation, environmental satellites are playing an expanding role in monitoring variations in the Earth's climate. This session focuses on the contributions of satellites to measuring climate variations on time scales ranging from seasonal-interannual to decadal. Invited papers review the radiative forcing of the Earth's climate by the Sun and measurements of all components of the Earth's climate system atmosphere, oceans, land surface, and cryosphere. Contributed papers report latest results on these topics.

The Digital Earth in 1997: Models and Computations in the Solid, Fluid, and Magnetic Earth (U52B)

Advances in inversion, tomography and computing have resulted in construction of detailed and complex models of the atmosphere, the oceans, the crust and the mantle, and the inner and outer core of the earth, as well as models of fields around, on and within the Earth, and of dynamic physical and chemical processes. Topics include geomagnetic and geopotential field models and fractal models of the crust and of crustal magnetism. The modeling of dynamic processes are presented on the atomistic simulation of the melting of iron at high pressures; on the avalanche effect in phase transition modulated mantle mixing; and on the geodynamo.

Atmospheric Sciences

Integration of Ecosystem Simulation Modeling in Large-Scale Field Experiments of Biosphere-Atmosphere Exchange (Joint with H) (A21A)

This session will bring together terrestrial field scientists, simulation modelers, and atmospheric scientists to provide analysis and overview of biogeochemical cycling, hydrology, and remote sensing results from previous large-scale field experiments of biosphere-atmosphere exchange (BOREAS, HAPEX-Sahel, ABRACOS). We will address the general question: "What can intercomparison(s) of ecosystem modeling algorithms and results contribute to observational studies of regional-scale biosphere processes?" Speakers will analyze requirements for more complete and productive integration of ecosystem modeling studies with experimental and monitoring components of field campaigns.

Solar Radiation Interactions with Aerosols and Clouds (Joint with OS) (A21B, A22D, A51B)

The presence of aerosols and clouds has a significant impact on the flux of solar energy through the atmosphere. Analysis of ARESE (ARM Enhanced Shortwave Experiment) broadband and spectral measurements indicate higher visible and near infrared radiation absorption by clouds than predicted by theory. Analysis of the solar radiative flux data acquired during ARESE has lead to improved estimates of cloud solar absorptance values, remote sensing of cloud properties, and treatment of clouds in climate models. Spectrally-resolved measurements of total-horizontal, diffuse-horizontal, and direct-normal solar irradiance from 350 nm to 1050 nm has been acquired at the Southern Great Plains facility of the ARM program. These data sets are available to test radiative models and to infer column properties. Black carbon, a radiatively important substance, has been studied in air and in cloud droplets during NARE (North Atlantic Regional Experiment) and RACE (Radiation, Aerosol and Climate Experiment). A new technique has been developed to map UV-absorbing aerosols over land, water and snow using TOMS data. This technique is capable of providing both the optical depth and single-scattering albedo of the aerosols; it has great promise for improving satellite estimates of surface radiation.

Smoke, Clouds, and Radiation-Brazil (SCAR-B) (A22A, A31B, A32D)

Papers in these sessions highlight the recently conducted SCAR-B field experiment in the southern Amazon basin. Papers include the comparison of remote satellite, airborne, and ground-based observations with detailed in situ airborne measurements of the properties and characteristics of aerosols, clouds, radiation, and chemistry. Other papers will deal with the meteorology, mass transport, climatology, and radiative impacts. Based on the SCAR-B observations, one paper will document the direct radiative forcing due to aerosols on the global climate.

Scientific Application of NASA Scatterometer (Joint with OS) (A22C, A31A, A32C)

The NASA Scatterometer (NSCAT) was successfully launched into a near-polar, sun-synchronous orbit aboard the Japanese Advanced Earth Observing Satellite (ADEOS), on 17 August 1997, to provide surface wind vectors (speed and direction), under both clear and cloudy conditions, over nearly 80% and 100% of the ice-free ocean in one and two days, respectively. In this special session, 36 papers will be presented, covering a broad spectrum of scientific application of NSCAT data. The global synoptic observation makes possible investigations in large-scale changes of sea-ice, atmospheric circulation, and wind-forced oceanic circulation. The high spatial resolution of data has been utilized in the studies of storms, typhoons, orographic effects on atmospheric circulation, wind-driven coastal circulation and related biological processes. Significant improvement in numerical weather forecast by assimilating NSCAT winds will also be reported.

Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) (A41C, A42D)

Aerosol effects on atmospheric radiation are a leading source of uncertainty in predicting future climate. TARFOX was designed to reduce this uncertainty by measuring the radiative effects, and the chemical and physical properties, of aerosols in the plume carried from North America over the Atlantic Ocean. The campaign, endorsed by the International Global Atmospheric Chemistry Program's Focus on Atmospheric Aerosols (IGAC/FAA), used satellite, aircraft, land, and ship measurements to enable a variety of radiative "column closure" studies, including validation of satellite remote sensing measurements. Initial results from the July 1996 Intensive Field Period are presented.

Atmospheric Sources and Sinks of Nitrous Oxide and Their Implications (A41D, A42A)

This session concerns the greenhouse gas nitrous oxide whose concentration has been rising due to currently quite uncertain causes, and which is also the progenitor of a powerful ozone destroyer. It highlights the very serious possibility that the nitrous oxide chemistry in contemporary atmospheric models, which are used in regulatory policy decisions, is incomplete. A concerted effort by laboratory kineticists, computational chemists, soil scientists, hydrologists, atmospheric observers and modelers will be needed to correct this situation.

Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) (A42B, A51C, A52A)

The SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) was a field mission carried out in April and May of 1996 to better understand the radiative properties of aircraft contrails and cirrus clouds. Three instrumented NASA aircraft were used to sample clouds and contrails (DC-8), to act as a surrogate satellite for remote sensing (ER-2), and to sample aircraft exhaust and contrails (T-39). The mission objectives were to determine how cirrus clouds form, whether emissions from the current subsonic fleet affect cirrus cloud formation, and, if so, whether such changes are of climatological significance. A wide variety of sampling measurements of gaseous species and aerosols in conjunction with radiometric measurements have been accumulated which represents a uniquely comprehensive database for contrail and cirrus properties in the upper troposphere. The Special Session will represent a collection of initial reports of the analysis of the results of this important field mission.

Air-Sea Gas Exchange (Joint with OS) (A42E)

This session reports on investigations of air-sea fluxes of gases that play important roles in the earth's climate and biogeochemical cycles (carbon dioxide, oxygen, methyl bromide and carbonyl sulfide). The session also reports on studies of the mechanisms of air-sea gas transfer. Processes that occur in small spatial domains (such as estuaries) and during short-lived events (such as hurricanes) may play a disproportionately large role in global air-sea gas fluxes. The diversity of processes--bubble formation, whitecapping, surfactant production and rain--that contribute to air-sea gas transfer is apparent.


Antarctic Geodynamics (Joint with T) (G21A, G31A)

Satellite missions, such as ERS-1 and ERS-2, have provided valuable new data for analyzing a range of geodynamic phenomena in Antarctica. This session provides a forum for recent results using highly accurate altimetric, SAR, GPS, and absolute gravity observations for studying the ice sheets and their dynamical behavior. In particular, new results of Antarctic studies of ice sheet topography, ice sheet dynamics, glacier motion, deformational responses of the ice sheet, kinematic modeling, and tide modeling are among the highlights for papers to be presented in these sessions.

Oceanographic and Geophysical Applications of Satellite Altimeter Data and Complementary Data Sources (Joint with OS) (G22A, G31B)

Continuous sea surface height measurements have been made over the past four years by the TOPEX/POSEIDON altimeter. In addition, measurements from other satellite missions such as ERS-1/-2, the Navy's GFO-1, the NOAA operational satellites and the DMSP satellite mission, and in situ measurements from the WOCE and TOGA field experiments have led to and will provide an unprecedented amount of data available for oceanographic study.

Papers which address the complementary use of altimeter data with other satellite and in situ data to increase each other's usability for oceanographic studies will be presented in this session. In particular, papers on efforts to produce high-level sea level measurements from multiple altimetry, basin-scale heat flux change inferred from satellite altimetry and from in situ data, gravity field, geoid, orbit determination and ocean tide improvement, and altimetric corrections such as media delay and inverted barometric response are among the highlights of the sessions.

Research Applications of Dense GPS Networks (Joint with T) (G32A, G32B)

The number of permanently-located, continuously-tracking GPS receivers has grown

tremendously during the past few years and there is every indication that this growth will continue. Papers which explore the application of data from these networks to primarily crustal deformation, plate motion, volcano and earthquake monitoring will be presented. In particular, papers on the applications of existing dense networks currently in Japan and Southern California are among the highlights of the sessions.

Combinations of GPS with Other Geophysical Data (G32C)

GPS has received much attention for its ability to provide three-dimensional position and deformation data. Considerably more can be learned about the Earth by combining GPS

with other types of geophysical data. For example, the combination of GPS and differential microgravity measurements permits the separation of the effects of elevation changes and mass changes below a station. This session includes papers on applications using both GPS, absolute gravity and other measurements to study crustal motions, ice sheet dynamics, and Earth rotation signals.

Space Geodesy Posters (G41A)

Papers in this session provides a variety of topics ranging from Earth rotation to reference frame studies using SLR, VLBI, and GPS.

Contribution of Satellite Gravity Measurements to Earth Science,

Global Change, and Natural Hazards Research (Joint with H, OS, T) (G41B, G42A) With advances in instrument technology, mission design, and gravity models, the geopotential missions proposed today have the capability to collect data with sufficient accuracy

to address a wide variety of Earth science problems. This session reviews the results of a National Research Council study on the application of satellite gravity measurements (both static and time-varying aspects with particular emphasis on the latter) for addressing research problems related to Earth science, global change, and natural hazards. Papers will address the application of time-varying gravity measurements to oceanography, solid Earth science, hydrology, glaciology and sea level rise studies, and will address error budgets for advanced gravity mapping mission, including GRACE, which has been selected as one of NASA's ESSP missions.

Earth Rotation: Measurements and Models (G42B, G42C)

The Earth's rotation varies in response to a wide range of geophysical and astronomical forces acting either within the body of the solid Earth or at its bounding surfaces. Modeling the Earth's variable rotation not only requires models of the applied forces but also requires knowledge of the Earth's deformational response to these forces. Discrepancies allow insight into the forcing mechanisms and response of the solid Earth. Papers in this session provide a forum for discussions on the measurement and modeling of the Earth's variable rotation. In particular, the use of VLBI and GPS measurements along with the associated comparisons with atmospheric angular momentum signals and influence on sea level and tides are among the highlights of the sessions.

Edge Mechanics and Internal Deformation of the Tibetan Plateau (Joint with S, T) (G42D)

The past several years has seen a wealth of new field data emerge concerning the

processes that formed, and sustained the Tibetan Plateau, and which are being used to address its future development. The session provides a forum for papers with new results from geodetic studies, kinematic models, seismic tomography, geologic and morphologic analyses, that provide us with new insights concerning the partitioning of deformation at its edges, underlying mantle motions, and its internal structure.

Geomagnetism and Paleomagnetism

Space Age Geomagnetism: A Tribute to Dr. Robert A. Langel (GP22A, GP31A)

This session honors Dr. Robert A. Langel, Project Scientist for NASA's enormously successful MAGSAT mission and the leading authority on the analysis of near-Earth satellite magnetic data. Topics range from satellite magnetic anomalies, geomagnetic field modeling, comparison of global magnetic and gravity fields, and core-field modeling to paleosecular variation and dynamo simulations. Dr. Langel will be sharing, "Thoughts on the History of and Recent Developments in Modeling of the Geomagnetic Field at Goddard Space Flight Center."

Cox (GP22B)

This lecture is given by a senior member of the Geomagnetism and Paleomagnetism community who has made significant contributions during his career to the field. Rob Van der Voo will talk about his work on pre- Mesozoic paleogeographic reconstructions using paleomagnetic datasets.

Tectonic Relations Between the Caribbean and Adjacent Plates (Joint with G, T) (GP41A)

This session focuses on GPS, paleomagnetic, and other data bearing on the tectonics of the Caribbean and adjacent areas. New data are presented as well as summaries of prior results, including for GPS the results of surveys spanning several years and for paleomagnetism the results of studies spanning several decades.

Rock Magnetism, Paleomagnetism, Tectonics, Climate Change, Petrology, and the Earth's Field Posters (GP51A)

This poster session presents the results of the diverse interests of paleomagnetists, rock magnetists, and those studying the behavior of the Earth's magnetic field. Studies of Precambrian climate and more recent climate change, MORB magnetic mineralogy, pre-Mesozoic paleogeography, remagnetization processes, and inclination shallowing are some of the topics covered.

A Tribute to Prof. William J. Hinze on His Retirement From Purdue University (Joint with G, T) (GP52A)

This session honors Bill Hinze at his retirement from Purdue. Topics reflect the wide range of Bill's interests and cover results from aeromagnetic and gravity surveys, shallow geophysics to the deep structure of crustals rifts and volcanoes.


Natural Attenuation and Groundwater Remediation (H21A, H22C)

Natural Attenuation (NA) for remediation of groundwater contamination uses natural (non-engineered) degradation and dilution processes to reduce contaminant concentration. NA is rapidly becoming a commonly used remediation technology with tens of thousands of sites permitted annually. Mechanisms and rates of the physical, chemical and microbial processes which control fate and transport of contaminants must be well understood if environmental

managers and regulatory agencies are to evaluate NA as a remedial method. This session explores the science underlying natural attenuation. Lab, field and modeling studies of NA and the biogeochemistry involved are examined.

Large-Scale Field Experimentation and Remote Sensing: Results and Opportunities (Joint with A) (H21C, H22D)

In the past decade a number of carefully planned campaigns involving ground-based measurements, in concert with remotely sensed observations from satellites and aircraft and various types of modeling activities, have gradually started to unravel several issues in landsurface-atmosphere interaction and the related hydrology. These experiments have

covered a wide spectrum of spatial and temporal scales, ranging from the micro to the mesobeta and from the quasi-instantaneous to the monthly, respectively. The objective of this session is to take stock of recent results, with successes and failures, and to consider prospects for clarifying unresolved issues.

Chesapeake Bay Ecosystem: Human and Climate Impacts (Joint with OS) (H22A, H32E)

Chesapeake Bay, the nation's largest estuary, has historically experienced ecological stress from elevated nutrient and sediment influx commonly linked to land use changes such as agricultural practices, deforestation, urbanization, and pollution throughout its 64,000 km2. Despite restoration efforts, large gaps exist in our understanding of the relationship between the Bay's health and both human-induced and climatological influences. It is clear that hydrology and climate strongly influence nutrient influx, the development and maintenance of spring and summer hypoxia, and sedimentation. This session examines Chesapeake Bay, its watershed and potential impacts of population growth and climate variability over interannual, interdecadal and long-term time scales.

Scaling in Hydrology (H22B, H31D)

Scaling efforts are underway in most all areas of hydrology from groundwater to hydrometeorology. Yet, the term "scaling" means many different things: such as averaging fine resolution data to coarse model meshes, or perhaps the use of a theoretical framework that links variability at one scale to variability at yet another scale. Designed to clarify the issues and approaches, this session will consists of two parts: (I) a workshop of invited full-length seminars addressing fundamental aspects of scaling in both a general sense and in each of the major sub-disciplines in hydrology, and (ii) a poster session highlighting theoretical developments and applications of scaling in hydrology.

Laboratory, Field, and Numerical Investigations of Reactive Transport in Subsurface Environment (H31B, H41E)

Systems Solutes may undergo a variety of reactions within saturated and unsaturated systems: aqueous phase reactions; partitioning between solid, vapor, or non-aqueous phases; and biological transformations. Interactions between the flow regime and the chemical or biological behavior of these solutes determines solute fate. This session focuses on studies

that aim to describe, measure, or model reactive transport phenomena.

Sources, Transport and Delivery of Sediment and Associated Contaminants in River and Estuarine Systems (H31C)

Sediment initially removed from disturbed lands by agriculture, logging, mining, urbanization and other activities often remains within the river system for decades or centuries, and creates a variety of problems. Phosphate, metals, and other contaminants move with the sediment and can be remobilized in estuaries or wetlands under different redox or pH conditions. Papers cover a wide variety of topics, including field and modeling studies of sediment sources, transport, and delivery in both river and estuarine systems.

Diffusion of Solutes in Groundwater Systems (H31E)

Diffusion in groundwater is recognized as one of the main mechanisms of solute transport; however, it is one of the most difficult mechanisms to measure independently and is often ignored or lumped with dispersion. Diffusion in dual porosity media is effective in both retarding solute transport and limiting the rate of groundwater remediation. In contrast, diffusion in granular porous media is often minimized. The purpose of this session is to bring together research on diffusion in groundwater at both small- (contaminant) and large- (isotopes, mineralization) time scales in both dual porosity and granular porous media.

Measurement and Modeling of Land-Surface Processes (H32A, H41C)

The land-surface processes (LSP) that link the terrestrial biosphere and atmosphere co-exist over a wide range of space and time scales. Understanding LSP and their hydrologic controls are necessary to assess how short-and-long term climate perturbations modify the hydrologic cycle, and in return, how these modifications impact local and regional

climate. This session deals specifically with measurements and modeling of LSP across a wide range of time and space scales with emphasis on examining physical and biophysical parameters that control LSP over different terrain types.

Soil Moisture Measurement: Integration From Point to Field Scale (H42A, H51D)

Measurement of the spatial and temporal variability of soil moisture represents a critical component in our understanding of the transfer of water between the atmosphere and the subsurface. The goal of this session is to highlight 1) recent advances in soil moisture determination 2) the relationship of local scale measurements with field scale and remotely

sensed data and 3) the integration of soil moisture monitoring in watershed-scale studies.

Hydrologic Restoration (H42E)

Human activities have had profound effects on the landscape, and hence on the hydrology of streams, lakes, wetlands, and other aquatic systems. Primary effects include increases in flood peaks, flood volumes, and sediment loads; decreases in baseflow discharges; degradation of water quality and aquatic habitat; and channel erosion. Attempts to mitigate these effects in agricultural, forest, range, and urban settings have included implementation of land and water management practices, restoration of wetlands and other natural landscape features, and stream rehabilitation. This session explores technical issues associated with hydrologic restoration, including establishment of restoration goals and criteria; hydrologic characterization under past, present, and future conditions; and evaluation of restoration strategies.

Remote Sensing of Precipitation Posters (H51B)

This poster session covers a broad range of topics related to the remote sensing of precipitation and highlights research and applications involving remotely-sensed precipitation.. Papers cover the estimation, validation, and error analysis of precipitation measured by ground-based remote sensors, such as radar (e.g., NEXRAD WSR-88D), and satellite sensors (e.g., VIS, IR, SSM/I).

Groundwater Management in the Atlantic Coastal Plain (H51C)

The Atlantic Coastal Plain aquifer system extending from New York to Georgia is one of the major aquifer systems of the country with ground-water withdrawals of about 2 billion gallons per day. The purpose of this session is to share experiences among scientists and resource managers of studies relevant to management of ground water in this major hydrogeologic setting.

Ocean Sciences

Geobiology of Critical Intervals (Joint with A, GS) (OS21A, OS22A)

Interdisciplinary research sheds light on key intervals of the geologic past during which important changes took place in the coupled earth-life system. The proposed initiative "Geobiology of Critical Intervals" focuses on this integrative field of research. Topics included in this session include the possible interplay between climate and life, the usefulness of iterative data analyses and climate modeling studies which focus on questions of global change in Earth history, and the possible influences of tectonics upon climatic and biologic evolution.

Carbonate Marine System During Oxygen Isotope Stage 11 (OS21B)

The geologic record indicates an extreme response in the operation of the marine carbonate system, and possibly the climate system, during interglacial Stage 11 (362 to 423 ka). The first two speakers will provide a general overview of this time interval and a broad discussion of the carbonate system. Subsequent speakers will compare and contrast this unusual time in Earth history from the vantage points of the tropical neritic environment (geological records from the Great Barrier Reef, Bermuda, and the Bahamas) and the low and high latitude open ocean (deep-sea sedimentary records from the equatorial Pacific and the Southern Ocean). A highlight of this session will be a presentation that concludes that the Great Barrier Reef is significantly younger than previously thought, initially forming less than 500,000 years ago, possibly during Stage 11.

High Latitude Holocene Climate Change (OS22B)

High latitude records from both hemispheres reveal distinctive climate changes throughout the Holocene. Ice cores, marine, and terrestrial records provide glaciochemical, isotopic, ice sheet, temperature, treeline, sea level, and carbon storage information for the last 10,000 years. These records are compared to understand regional Holocene climate complexity.

Paleoceanography of the Atlantic Basin: ODP Results (OS31A)

This session focuses on recent Ocean Drilling Program results from the Atlantic Ocean, primarily on Neogene deep-sea sedimentary records from the North Atlantic (Legs 151, 154, and 162), and on Cretaceous-Cenozoic sequences from the New Jersey coastal plain (Leg 174AX). The North Atlantic presentations will highlight: (1) millennial-scale and sub-Milankovitch climate variability; (2) ground-truthing of multi-sensor-track data and applications to glaciomarine sedimentation; (3) environmental magnetism; (4) initiation of Northern Hemisphere glaciation; and (5) thermohaline circulation. The presentations of New Jersey data will concentrate on sequence stratigraphy and sea level as well as on a high-quality, spherule-containing K/T interval.

Paleoclimatology and Paleoceanography: Observations and Models (OS32A, OS41B, OS42A)

These sessions (two oral and one poster) include several topics, including coral isotopic records of interannual tropical climate variability, climate model investigations of effects of variable atmospheric CO2 concentrations on Cenozoic climate, sedimentary indices of paleoceanographic processes during the late Neogene, paleoclimate signatures of the K/T extinction event, and late Cenozoic geochemical studies of ocean productivity, carbon budget variations, and hydrothermal activity, and the development of new geochemical tracers of ocean productivity.

High-Latitude Gas Venting, Hydrates, and Mass Wasting Posters (Joint with T) (OS41A)

This session focuses on high latitude seafloor sedimentary processes. High latitude gas venting and methane hydrates, thermal gradients, pore water chemistry associated with venting, and the microbiology/biochemistry surrounding these vents will be examined. In addition, continental slope mass-wasting phenomena, including mudflow microfabric, acoustic, physical and rheologic characteristics, and the relation of mass wasting events to hydrate dissociation will be examined along the Northern European Arctic and Alaskan Arctic margins.

Nearshore Processes and Modeling (OS51A, OS52B)

These sessions (one oral and one poster) focus on coastal processes and modeling studies of physical processes in such environments. Regions examined in these studies include Galveston and Tampa Bays, the East, Japan, and Sargasso Seas, as well as general estuarine environments.

Marine Processes and Geochemistry Posters (OS51B)

This session features a range of poster presentations which examine marine processes such as productivity and dissolution. Biogeochemical aspects of the marine system are also focused upon, including Germanium/Silicon measurements, 224Ra distributions, and wind-driven 210Po.

Biogeochemistry of Trapped Gases in Ice Cores (OS51C)

This session will present new data concerning the history of atmospheric greenhouse gases and will also honor Hans Oeschger, the 1997 Revelle Medal recipient. Highlights include presentation of a new 400,000 year record of atmospheric gas measurements from the Vostok ice core, a discussion of climate mechanisms during the last deglaciation, and discussions of tropical climate instability from ice core records.

Ocean Surface Wave Generation Processes (OS52A)

Papers presented in this session will discuss recent results that aid in the interpretation and understanding of remotely sensed ocean surface data and the basic physics of the air-sea interaction mechanisms between wind, ocean waves, and ocean currents leading to the observable ocean surface.


A Session in Honor of John A. O'Keefe (Joint with G) (P22A)

This session highlights John A. O'Keefe's remarkably wide-ranging career, from

discovering the "pear-shaped" Earth to his participation in the Apollo Lunar Laser Ranging Experiment. The session also includes discussions on the paradoxes associated with tektites.

Galileo Investigations of the Icy Galilean Satellites (P31A, P32A)

It has been almost a year since the first Galileo encounter with the icy Galilean satellites and during that time several encounters have taken place with Europa, Ganymede and Callisto,

providing exciting new discoveries and startling new views of these bodies. In this session, Galileo investigators report on the latest data on icy satellite interiors, magnetic fields, and surface composition, morphology and geologic history.

Also see the Union Session on

Carl Sagan: His Pioneering Science and Current Studies of Life in Extreme Environments (U21A)


Earthquake Precursors and Other Transients in Plate Boundary Deformation (Joint with G, H, T, V) (S21A, S22A, S31C)

Earthquake prediction can rightly be called the Holy Grail of Seismology. Nonetheless, the goal of identifying precursory phenomena that can be reliably used to predict earthquakes has proven elusive. This session provides a critical review of recent observations on precursory phenomenon, along with a number of papers on physical processes involved in the earthquake process that may or may not (depending on individual author's viewpoints) render earthquake prediction feasible. The session closes with a panel discussion on Wednesday morning which promises to yield a lively debate on this subject.

Seismology and Education (S32B)

The infrastructure developed by IRIS and others for the collection, management, and distribution of seismic data is not only serving the research community, but is beginning to see use in education at the K-12 and undergraduate level. This session contains papers describing data acquisition, web-based software tools, and video productions that have emerged from this effort.

Recent Observations at Parkfield (Joint with G, T) (S42A)

Since 1993 data from several types of instruments at Parkfield show evidence for a change in behavior. An apparent increase in the deformation rate has been identified both in two-color laser and borehole strainmeter measurements. This same time period has seen earthquakes that triggered the two highest alert levels for an impending earthquake and a brief period of anomalous magnetic field activity in December, 1994. This session will review these observations and their possible implications for the earthquake process and the future of the Parkfield monitoring effort.


Meteors and Their Effects Upon the Space Environment (SA21B, SA22A)

Scientific research and public awareness share a renewed interest in the influx of celestial material upon the terrestrial environment. This Special Session will focus on how meteors, in general, and the predicted Leonid "Meteor Storms" of 1998 and 1999, in particular, can be used to enhance our understanding of a broad range of topics known to be affected by meteor impact. These include the creation of unusual layers in the Earth's atmosphere and ionosphere, potentially induced effects in the magnetosphere, and the short term generation of a transient lunar atmosphere. Presenters will describe recent measurements, models and observing plans for the 1998/1999 events.

Optical and Density Measurements From the MSX Satellite (SA41B, SA42B, SA51A)

The MSX Satellite is the first technology demonstration in space that has simultaneously satisfied its BMDO/DoD mission requirements and provided a rich hyperspectral data base on the earth's atmosphere and phenomena of interest ( Density, Aurora, Global Change Gases, Polar Mesospheric Clouds, Space Weather, Surface features, etc.), to the general scientific community.

SPA-Heliospheric Physics

Cometary X Rays and New Cometary Physics (Joint with P, SM) (SH21D, SH22B)

The discovery of soft xrays emitted by a region surrounding Comet Hyakutake was unexpected and exciting. This seems to be a common phenomenon for all comets as they approach the sun. This session examines a variety of emission mechanisms. These emissions will surely become useful for remote monitoring of the interactions of the solar wind with comets.

Small-Scale Energy Releases on the Sun (SH22C, SH31D, SH32A)

This session has a number of papers dealing with the observations and theory of

flare-like brightenings from active regions and quiet Sun; these tiny flares are weaker than typical flares by one or more orders of magnitude. Oral and poster presentations also deal with the structure and dynamics of other small scale phenomena such as bright points, coronal plumes, small-scale filaments. Data from many space missions such as SOHO, YOHKOH and CGRO will be presented. Since these phenomena are observationally less complex as compared to major flares and eruptions, it may be easier to understand them. The special session has four groups of presentations (I-iii oral, iv poster). (I) Small-scale phenomena on the quiet Sun, (ii) Small-scale phenomena from active regions, (iii) Small-scale structure and dynamics, (iv) The poster session has eight papers related to various topics in the previous three groups.

Whole Sun Month Campaign Posters (SH31A)

The Whole Sun Month campaign is an on-going effort to understand the

large-scale, stable solar minimum corona and its connections to interplanetary space. The observational phase of the campaign ran from August 10 to September 8, 1996. This campaign included observations from a variety of spacecraft and ground-based observatories. By getting a large number of people to work on the same set of data, we hope to be able to contrast and compare results. The work presented in this session is just the very beginning of the analysis and modeling. As this is an on-going effort, we invite interested participants to become involved in the campaign, which will include future workshops. More details of the campaign and the observations are available at the Whole Sun Month Web Site: http://serts.gsfc.nasa.gov/whole_sun/

Relativistic Electrons and Positrons in the Heliosphere (SH31B, SH31C)

Electrons and positrons constitute the frontier of cosmic-ray science, as their measurement is difficult and our understanding is correspondingly poor. This session

puts together papers summarizing our present understanding of this important component.

Coronal Heating and Solar Wind Acceleration (SH32B, SH41C, SH42A, SH51A)

The physical processes responsible for the heating of the solar corona and acceleration of the solar wind remains a great mystery. Stunning new SOHO observations of long-lasting

"plumes" extending to large distances over the solar poles and two different types of coronal transients from helmet streamers in the ecliptic will be presented in the session. These observations place new constraints on the possible physical mechanisms. New theoretical ideas concerning coronal heating and solar wind acceleration including: dissipation of collionless quasiparallel Alfvenic shocklets, Alfven resonances in the presence of shear flow, acceleration by solitary or Alfven waves, effects of parallel heat conduction and cyclotron damping will be discussed.

Sun-Earth Connections: New Directions (Joint with SA, SM) (SH42B)

The status of the long-term strategic plan, called a "road map," presently

under development by the scientific community of NASA's Sun-Earth Connections theme, will be presented in this special session. Details of spacecraft missions supported by this community will be described. These missions include the community's choices for the next Solar Terrestrial Probe (STP) to follow TIMED, now under development by NASA and a "Frontier" mission to be the flagship mission for this theme.

SPA-Magnetospheric Physics

ISTP Correlative Results (Joint with SA, SH) (SM21A, SM22C, SM31A, SM32C, SM41A, SM41C, SM42C, SM51A, SM52C)

A tremendous international effort has provided a rich source of correlative data from diverse space and ground-based measurements. The international solar-terrestrial science community is deeply involved in the extensive analysis of these coordinated observations through specific events or campaigns. These events all involve multi-point observations which are elucidating the structure of the magnetopause and bowshock, plasma entry at high latitudes, structure and origin of the solar wind, and plasmasheet- ionosphere coupling in substorm phenomenology just to name a few. This session comprises papers advancing an end-to-end understanding of the sun and geospace as a system. An "interactive poster" session allows direct access to the correlative data.

FAST Results and Related Auroral Physics (SM21B, SM22D, SM32A)

Understanding acceleration processes in the aurora and related plasma

physics and "microphysics" phenomena has traditionally been led by advances in in-situ and ground-based experimental techniques. For example, instruments with higher spatial and temporal resolution have been essential in revealing the fundamental interactions between energetic particles and electrostatic potential structures and related wave phenomena. NASA's Fast Auroral SnapshoT (FAST) Small Explorer Satellite, launched in August, 1996, includes DC and AC electric and magnetic field detectors, as well as high time resolution energetic electron, ion, and ion composition instruments. The instruments on this satellite have already returned an unprecedented collection of observations that promise to yield new discoveries and physical insights towards our understanding of auroral acceleration phenomena. Furthermore, in the past few years, related in-situ observations have been gathered by the Swedish Freja Satellite and more recently by NASA's Polar satellite (particularly for data collected near perigee), as well as by numerous sounding rockets launched from Poker Flat, Alaska and Scandinavia. In concert with the new experimental data, many new ideas have been advanced by theoretical studies, including simulations and modeling. This session serves as a forum to present new findings of auroral microphysics and to discuss their theoretical interpretations.

Innovative Techniques and Tools for Magnetospheric Research (SM21C, SM22A)

Magnetospheric research is confronted with the complex behavior of the vast magnetosphere, and equipped with only a small handful of widely scattered observing platforms. One possible remedy is to launch numerous satellites into strategically- optimized orbits, leading to severe cost and technical challenges. Another avenue is to devise major new techniques and tools beyond the traditional means to maximize the scientific returns from the existing observing platforms as well as for implementation in future missions. This session is devoted to exploring innovative approaches to solving the frontier problems in magnetospheric research.

Heavy Ions in the Magnetosphere (SM32D, SM41B)

At times high abundances of heavy ions are observed in the magnetosphere. If singly charged, these are usually regarded as being of ionospheric origin. Observation of heavy ions now cover the whole magnetosphere, including the distant tail on its open magnetic field lines. This session includes diverse observational results, as well as the models developed.

Space Physics and Aeronomy From Galileo (Joint with P, SA) (SM41D, SM42D, SM51B, SM52A)

Galileo is well into its survey of the Jovian system. Close encounters with all four Galilean satellites have been completed, revealing a host of new phenomena, including the possibility of satellite magnetospheres. The first half of a survey of the Jovian magnetosphere has been completed, providing unprecedented coverage of the Jovian magnetosphere and an invaluable data base for determining the major plasma physics processes operating in the Jovian magnetosphere. Combined Earth-based observational studies of auroral emissions at X-ray, UV, and IR wavelengths have been carried out in conjunction with Galileo in situ and remote measurements and provide a unique data set for the study of atmosphere-ionosphere-magnetosphere coupling processes. These exciting and scientifically-diverse studies are the primary focus of this session.

Interrelationship Between Space Plasma Physics and Laboratory Experiments (Joint with SH) (SM42A, SM51C, SM52D)

This session addresses key areas of the interrelationship between the space plasma physics and laboratory plasma experiments. Recent satellites and souding rockets have measured various kinds of waves and fluctuations in magnetosphere and in polar area: Alfven

waves, Whistler waves, ion cyclotron waves, and lower hybrid waves. The interaction of plasma with magnetic field is receiving much attention due to the recent very successful satellite programs such as YOHKOH, SOHO and GEOTAIL. New laboratory experiments have been generating novel and interesting data on magnetic reconnection. By comparing these results, we will make an effort to deduce a key mechanism of interaction of plasma with magnetic fields in real geometry, from both local and global points of view. The following three topics will be emphasized in this session; (1) Magnetic Reconnection, (2) Electrostatic waves and wave-particle interaction, and (3) Alfven waves/Whistler waves.


High Pressure Minerals: Elasticity, Equation of State and Phase Equilibrium (Joint with M, V) (T21A, T22A)

These sessions focus on experimental and theoretical constraints on the state and thermodynamic properties of the upper and lower mantle. Highlights include new observations on the stability of hydrous phases in the lower mantle, and the role of phase changes for modeling mantle compositions, interpreting seismic discontinuities in the Earth's transition zone, and understanding the influence of phase transformations on convection.

Criteria for Differentiating Tectonic from Nontectonic Faults (Joint with S) (T22B)

Identifying tectonic faults is a key element in seismic hazard assessment. Surface faults that result from a variety on nontectonic mechanisms commonly exhibit characteristics similar to and may be confused with tectonic faults. An understanding of the tectonic and nontectonic processes that result in surface deformation is essential for developing criteria to identify and evaluate the seismogenic and ground rupture potential of faults. In this session, criteria to differentiate tectonic faults from surface faulting that results from karst-related subsidence, large-scale gravitational spreading, landsliding, soft-sediment deformation, and other nontectonic mechanisms will be presented.

Dynamic Topography (Joint with G, P, S, V) (T31A)

In the past decade, there have been a number of successful attempts to fit Earth's long-wavelength geoid by assuming that tomographically-imaged seismic velocity anomalies represent thermally-induced density anomalies driving convection in a viscous mantle. There has been less success, however, in producing the correct dynamic topography in that most solution predict undulations of the surface that greatly exceed what is reasonable. This session focusses on theoretical and observational studies on the origin of dynamic topography that provide constraints on the depth distribution of viscosity in the mantle and convection models.

Birch Lecture (Joint with S, V) (T41B)

In this distinguished lecture, Don Forsyth presents seismological results from the Mantle ELectromagnetic and Tomography (MELT) Experiment, and discusses the implications of the results for melting and mantle flow beneath mid-ocean ridges.

Volcanology, Geochemistry and Petrology

Monitoring and Predicting Volcanoes (V22A)

Volcanic eruptions can cause significant damage to populations and aircraft flying in the vicinity of the eruption. Consequently, monitoring volcanoes in an effort to predict their future behavior is important for economic, social and scientific reasons. This session focuses on the behavior of volcanoes in various parts of the world in an effort to predict future eruptions.

Daly Lecture (V22B)

This lecture focuses on the tectonic implications of the discovery of diamonds and high pressure rocks in some ancient orogens. The talk will integrate mineralogic and petrologic constraints with tectonic models of the deep crust and the possible models that allow the introduction of continental crust to very deep levels of the Earth and how these deep sections get exhumed rapidly.

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