bluuebunny/crossref_metadata_2025 huggingface dataset:
Survey of “emerging contaminants” in U.S. streams indicates need for further research
Authors: Showstack Randy
Published: October 2006

The first nationwide reconnaissance of pharmaceuticals, hormones, and other organic wastewater contaminants (OWCs) in U.S. streams has found one or more targeted compounds in 80% of the streams sampled. The U.S. Geological Survey (USGS) study, released on 13 March, detected 82 of 95 specific compounds in the 139 streams sampled.

Herbert Buxton, coordinator of the USGS Toxic Substances Hydrology Program, which conducted the study, said, “This is the first hard environmental occurrence information on a large number of environmental compounds on which we did not have information before.” Buxton said the findings may aid research on potential human and ecological effects from these compounds and on understanding in what concentrations the compounds occur individually and in combinations.
Space Station allows remote sensing of Earth to within six meters
Authors: Robinson Julie A. , Evans Cynthia A.
Published: October 2006

Budgetary challenges and research limitations of the International Space Station, which is currently being constructed, are routinely discussed in the media [e.g., Lawler, 2001]. In spite of these challenges, an Earth remote sensing experiment being conducted from the International Space Station, called Crew Earth Observations [Robinson and Evans, 2001], is already yielding significant data returns by using the successful photographic methods employed in earlier Earth imaging programs from the Space Shuttle and Mir Space Station [Lulla and Dessinov, 2000]. Early results show great improvement in our ability to compensate for the relative motion of the Earth and achieve high remote sensing spatial resolution in handheld images. Images captured for Crew Earth Observations have spatial resolutions of less than 6 m, approaching the highest spatial resolution of color images now available from commercial remote sensing satellites.
Drilling program investigates permafrost gas hydrates
Authors: Dallimore Scott R. , Collett Timothy S. , Weber Michael , Uchida Takahashi
Published: October 2006

On 25 December 2001, fieldwork began on a new gas hydrate research well program at the northeastern edge of the Mackenzie Delta, Northwest Territories, Canada (Figure 1, top). The Mallik research well program of 2001–2002 will drill a 1200‐m deep main production research well, and, for the first time, two 1150‐m‐deep scientific observation wells offset 40 m from the main well (Figure 1, bottom) for geophysical monitoring of the main well. The science and engineering objectives are to assess the production properties of gas hydrates and determine the stability of continental gas hydrates both in terms of past climate warming events and in response to warming trends predicted by various climate change models.
Measuring water exchange between the Venetian Lagoon and the open sea
Authors: Gačić M. , Kovačević V. , Mazzoldi A. , Paduan J. , Arena F. , Mosquera I. Mancero , Gelsi G. , Arcari G.
Published: October 2006

Almost 15 centuries ago, people fleeing civil disorder and barbarian invasions after the collapse of the Roman Empire began building houses on low‐lying islands in the middle of a lagoon. These islands later on—in the 10th century—became the city of Venice, the center of the long‐lived Venetian Republic. Surrounded by water, the republic flourished for more than 7 centuries thanks to its strategic position. It fell into decline only at the end of the eighteenth century after being occupied by Napoleon. The early Venetians who built their city on the water to defend it from attacks would never have expected that the water would become the city's most dangerous enemy. In fact, this is what has been going on during the last century Venice risks being destroyed by the very waters that once served as its defense.
Optimizing Reservoir Resources: Including a New Model for Reservoir Reliability
Authors: Houck Mark H.
Published: October 2006

Optimizing Reservoir Resources: Including a New Model for Reservoir Reliability is a fascinating blend of text and monograph with an unusual range of material. The first part is clearly textual and the second half reports on some very interesting research done for the Institute of Water Resources of the U.S. Army Corps of Engineers.

The successive chapters are evolutionary; one leads to another and offers a base for the subjects covered subsequently Part I contains five chapters on relatively established topics in water resources systems. These are the “text” chapters in the text‐monograph combo referred to above.
Meta‐information system facilitates use of complex data related to Andes
Authors: Ott N. , Götze H.‐J. , Schmidt S. , Burger H. , Alten M.
Published: October 2006

Studies of the Collaborative Research Center 267, “Deformation Processes in the Andes,” focus on interdisciplinary geoscientific research in the central and Patagonian Andes involving all disciplines of geoscience. The combination of geophysical and geological field research, Global Positioning System monitoring, penological and geochemical analysis, age dating, and remote sensing provides new insight into the structure and tectonic evolution of the Andes.
Carbon sequestration studied in western U.S. mountains
Authors: Schimel David , Kittel Timothy G. F. , Running Steven , Monson Russell , Turnipseed Andrew , Anderson Dean
Published: October 2006

The U.S. carbon budget has been the focus of recent scientific debate [Fan et al., 1998; Pacala et al., 2001; Gurney et al., 2002] Even conservative estimates suggest that U.S. ecosystems take up a significant amount of carbon, largely as a result of historical land use practices [Houghton et al., 1999; Schimel et al.,2000; Pacala et al., 2001]. In the western United States, a key cause of carbon sequestration is fire suppression. Fire suppression, of course, also sets the stage for the catastrophic losses that are occurring during fire season 2002. Increases in fire due to the effects of fire suppression, increased prescribed burning and thinning, and climate change could significantly affect the national carbon budget. At the continental scale, a comprehensive research approach—the North American Carbon Program (NACP)—is planned to quantify carbon exchange and improve our understanding of the contributing processes [Wofsy and Harriss, 2002].
Blowin' in the wind: Research priorities for climate effects of volcanic eruptions
Authors: Robock Alan
Published: October 2006

Volcanic eruptions inject gases and ash into the atmosphere, with climatic impacts on time scales up to decades. At the AGU Chapman Conference on Volcanism and the Earth's Atmosphere, held in Greece last summer, 108 scientists gathered to assess our understanding of volcanic emissions and the atmosphere's response to them, and to outline topics for future interdisciplinary collaboration that will lead to better understanding and prediction of the effects of large explosive eruptions.
Ancient observations link changes in Sun's brightness and Earth's climate
Authors: Pang Kevin D. , Yau Kevin K.
Published: October 2006

From the frequencies of sunspot and aurora sightings, abundance of carbon‐14 in the rings of long‐lived trees, and beryllium‐10 in the annual ice layers of polar ice cores, we have reconstructed the history of a variable Sun. In the last 1,800 years, the Sun has gone through nine cycles of changes in brightness. While these long‐term variations account for less than 1%of the total irradiance, there is clear evidence that they affect the Earth's climate.
Trends and variations in Arctic Climate System
Authors: Polyakov Igor , Akasofu Syun‐Ichi , Bhatt Uma , Colony Roger , Ikeda Motoyoshi , Makshtas Alexander , Swingley Chris , Walsh David , Walsh John
Published: October 2006

Prominent changes of the Arctic atmosphere‐ice‐ocean system observed in recent years have sparked intense discussions as to whether these changes represent episodic events or long‐term shifts in the Arctic environment. In the past, the lack of long‐term observations in the Arctic made it difficult to explore this issue. Although the length of available instrumental records is often too short to give a quantitative, statistical description of processes at multi‐decadal time scales, these Arctic records, which are similar in length to the global records, provide insight into long‐term variations of the Arctic climate system and suggest that high‐latitude climate feedbacks merit further study.
Deep sea borehole observatories ready and capturing seismic waves in the western Pacific
Authors: Suyehiro Kiyoshi , Araki Eiichiro , Shinohara Masanao , Kanazawa Toshihiko
Published: October 2006

Digital broadband seismometer networks and GPS networks are the recent sources of rapid progress in solid Earth geophysics. But they do not exist beneath the oceans. The lack of observatories in deep oceans that cover 71% of the Earth's surface has been considered a major deficiency in the seismic network by the scientific community. About 80% of the present plate boundary is located in the oceans and about 90% of seismic energy release is earthquakes beneath the sea floor, mostly at plate subduction zones.

Ocean basins and continents that make up our environments are not mere superficial features. They are surface manifestations of plate tectonics, mantle mixing, and core‐mantle interactions invigorated by the recycling of the oceanic plates.
New insight on Mars: A network of ancient lakes and discontinuous river segments
Authors: Kramer Marc G. , Potter Christopher S. , Des Marais David , Peterson David
Published: October 2006

With an abundance of ice recently detected just below the surface of Mars [Boynton et al., 2002],the possibility that life has existed or still may exist on Mars may hinge on examining its past climate and the duration of surface water flows. Was Mars ever a warm and wet planet, or has it always been cold and dry? The study of surface depressions, in conjunction with river features, yields new insight into these questions. Together, these features provide a more complete picture of a surface water network that may have existed on what must have been a warmer early Mars.
A new deep‐sea towed digital camera and multi‐rock coring system
Authors: Fornari Daniel J. ,   WHOI TowCam Group
Published: October 2006

Photographs of the sea floor provided some of the first clues about the abundance of life in the deep ocean, lava flows on the mid‐ocean ridge crest, and evidence for hydrothermal venting [e.g., Hersey, 1967; Heezen and Hollister, 1971; Ballard and Moore, 1977; Lonsdale, 1977]. These direct observations of the ocean floor are critical to understanding the physical, chemical, and biological processes occurring there.

Last year, a team of engineers at the Woods Hole Oceanographic Institution (WHOI), in collaboration with engineers at DeepSea Power and Light (DSPL) of San Diego, California, designed and successfully built and tested a new, digital deep‐sea camera and multi‐rock coring system. The system has been used during three expeditions thus far: the East Pacific Rise at 9°50′N, the Galápagos Rift at 86°–89°W and most recently to the Hess Deep in the equatorial eastern Pacific. To date, it has acquired ˜20,000 digital sea floor images and 50 volcanic glass chip samples during 20 lowerings.
Investigating a 65‐Ma‐old smoking gun: Deep drilling of the Chickxulub Impact Structure
Authors: Dressler B. O. , Sharpton V. L. , Morgan J. , Buffler R. , Moran D. , Smit J. , Stöffler D. , Urrutia J.
Published: October 2006

The Phanerozoic paleontological record is marked by several biological extinction events. One of them, at the Cretaceous/Tertiary (K/T) boundary, was responsible for the demise of about 50% of genera and 75% of species, including the dinosaurs. These drastic and abrupt changes in the development of life on Earth puzzled paleontologists in the past. Many a cause was put forward to account for them, amongst them climate changes, disease, or overspecialization.

About 20 years ago, Alvarez et al. [1980] discovered a high iridium concentration in an Italian K/T boundary clay layer.They proposed that the iridium was derived from an extra‐terrestrial impact 65 Ma ago, and that the impact was the cause for the K/T boundary extinctions. The iridium layer was subsequently found at K/T boundary locations worldwide. Further evidence for a K/T impact came from the discovery of shocked quartz, nano‐diamonds, glass spherules, and nickel‐rich spinels in microkrystites in the iridium‐rich layer. There was evidence for an impact event, but no crater.
The seas of Titan
Authors: Lorenz Ralph D. , Kraal Erin , Asphaug Erik , Thomson Richard E.
Published: October 2006

Oceanography may no longer be only an Earth science. Evidence continues to mount that Saturn's giant moon, Titan, may have seas of liquid hydrocarbons that exhibit many phenomena familiar to terrestrial oceanographers, but with an other‐worldly flavor (Figure l ). In less than two years, the Cassini‐Huygens mission, a massive joint undertaking of NASA, the European Space Agency, and the Italian Space Agency will arrive at Saturn and begin exploring the strange world of Titan. Our goal here is to introduce Titan to the oceanographic community, to outline the data to come, and prompt new modeling efforts. We pay particular attention to phenomena observable from Cassini, although we note that many terrestrial phenomena—only now beginning to be surveyed on Earth via moored instrument networks, submersibles, remotely operated vehicles (ROVs), and autonomous underwater vehicles (AUVs), etc.—may have analogues on Titan. We anticipate that Earth will have much to tell us about oceans on Titan, and vice‐versa.
Remote sensing of sea surface temperatures during 2002 Barrier Reef coral bleaching
Authors: Liu Gang , Strong Alan E. , Skirving William
Published: October 2006

Early in 2002, satellites of the U.S. National Oceanic and Atmospheric Administration (NOAA) detected anomalously high sea surface temperatures (SST) developing in the western Coral Sea, midway along Australia's Great Barrier Reef (GBR). This was the beginning of what was to become the most significant GBR coral bleaching event on record [Wilkinson, 2002]. During this time, NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) provided satellite data as part of ongoing collaborative work on coral reef health with the Australian Institute of Marine Science (AIMS) and the Great Barrier Reef Marine Park Authority (GBRMPA). These data proved invaluable to AIMS and GBRMPA as they monitored and assessed the development and evolution of SSTs throughout the austral summer, enabling them to keep stakeholders, government, and the general public informed and up to date.
Experiment explores inter‐calibration of biogeochemical flux and nucleic acid measurements
Authors: Kerkhof Lee , Corredor Jorge , López José , Paul John , Bronk Deborah , Cherrier Jennifer
Published: October 2006

In the ocean, biologically active elements undergo continuous cycling between the biota, the water column, and the atmosphere. Biological processes and the resultant air/sea exchange of atmospherically active gases are closely modulated by the availability and distribution of key elements. Such processes have been traditionally measured by incubation of representative microbial communities and tracking of end‐product appearance or substrate disappearance. The recent advent of molecular techniques allows for the quantification of DNA and the RNA messenger responsible for the synthesis of the enzymes catalyzing specific biochemical processes. However, there is little information on how levels of gene expression for natural populations of micro‐organisms correlate with biogeochemical processes.
An Introduction to Seismology, Earthquakes, and Earth Structure
Authors: Thurber Clifford
Published: October 2006

S. Stein and M. Wysession's An Introduction to Seismology, Earthquakes, and Earth Structure is the textbook I've been waiting for. It combines the pedagogical strengths of Introduction to Seismology by P. Shearer (1999) and the breadth of coverage of Modern Global Seismology by T. Lay and T. Wallace (1995). The “price” of this combination is a rather lengthy text, but it is so well written that the length can be easily forgiven.

At first glance, An Introduction to Seismology Earthquakes, and Earth Structure appears to follow a very traditional path, beginning with a nice overview chapter on the relevance of seismology, followed by chapters on seismic waves that include stress and strain basics, Earth structure, earthquake sources, and seismology and plate tectonics. On closer inspection, though, the reader will find many chapter sections that are rather novel. Included among these are waves on a string, an excellent way to introduce students to the complexity of seismic waves; earthquake geodesy which establishes the important connection between seismology and deformation studies; and plate kinematics, a clearly presented “short‐course” on plate motion studies. These sections, and others like them, significantly enhance the text. The latter two in particular help give the book a broader perspective that is rare in standard seismology texts.
When Earth's freezer door is left ajar
Authors: Gildor Hezi
Published: October 2006

The expected response of the Earth's cryosphere to global warming is a critical open research area in which model certainty is still unsatisfactory On the other hand, past climate history can teach us quite a bit. If one had returned from a vacation to find that the freezer door was left partially open and ice had collected in it, one would have learned an important climate lesson: ice does not form when conditions are merely cold, but when there is a supply of warm, moist air to a sufficiently cold environment.

While it is good practice to close one's freezer door and not experience this climate lesson personally, numerous observations and model results demonstrate that the large ice sheets that developed during past ice ages grew when the climate was relatively warm, and therefore moist. One must conclude that statements such as “…glaciers grow when climate is cold, not warm and moist” [Rahmstorf, 2002] contradicts a large body of scientific evidence, observations, and dynamical arguments. We now understand that the ocean also plays an important role in this feedback due to the role of sea ice in glacial dynamics.
Are noctilucent clouds a “Miner's Canary” for global change?
Authors: von Zahn Ulf
Published: October 2006

Noctilucent clouds (NLC) occur close to 83 km altitude during summer at polar, high, and mid‐latitudes. They are frequently visible to Earth‐bound observers, provided the observers are on the night side of Earth and the clouds are still illuminated by the Sun. Under these conditions, NLC can become a quite impressive sight. NLC owe their existence to the extremely low temperatures (well below 150 K) which prevail during summer over a wide latitude band in the 82‐ to 90‐km altitude region. For a major review of NLC science, the reader is referred to Gadsden and Schröder [1989].
A long‐term circulation and water mass monitoring program for the Arctic Ocean
Authors: Polyakov Igor , Walsh David , Dmitrenko Igor , Colony Roger , Hutchings Jennifer , Timokhov Leonid , Johnson Mark , Carmack Eddy
Published: October 2006

Substantial changes have occurred in the Arctic over the last few decades. These changes are linked with the variability of external climate system in ways not yet fully understood. Unresolved issues concerning the driving processes and mechanisms behind these changes in the Arctic environment require further investigation.

A major constraint on our ability to understand linkages between the Arctic Ocean and the global climate system is the scarcity of observational data. We have thus initiated efforts to establish a long‐term, mooring‐based observational system in the Eurasian and Canadian basins of the Arctic Ocean. A number of regional monitoring programs have elucidated local details of the circulation, but none has provided the large‐scale coverage proposed here (Figure l). The widely spaced array of moorings discussed here will emphasize the largest‐scale modes of variability over relevant time scales.
Exploring the plate boundary structure of the North Island, New Zealand
Authors: Henrys Stuart , Reyners Martin , Bibby Hugh
Published: October 2006

New Zealand's North Island and the offshore region to the east are one of the few places on Earth where many features of an active convergent margin can be studied along a compact transect. All components normally identified with continent‐wide deformation are present. From east to west, these include oceanic plateau, trench, accretionary prism, axial range, active andesite volcanoes, back‐arc rift, fold and thrust belt, and foreland basin. The North Island, therefore, represents one of the best modern, active continental margins for assessing the role of subduction on compressional and extensional deformation of continental crust.
Righting the balance: Gender diversity in the geosciences
Authors: Bell Robin E. , Kastens Kim A. , Cane Mark , Muller Roberta B. , Mutter John C. , Pfirman Stephanie
Published: October 2006

The blatant barriers are down. Women are now routinely chief scientists on major cruises, lead field parties to all continents, and have risen to leadership positions in professional organizations, academic departments, and funding agencies. Nonetheless, barriers remain. Women continue to be under‐represented in the Earth, ocean, and atmospheric sciences. Let's do the numbers: As of 1997, women received 41% of all Ph.D.s in science and engineering, but only 29% of the doctorates in the Earth, atmospheric, and oceanographic sciences [NSF, 1999a]. Women were 23% of employed Ph.D.s across all fields of science, but only accounted for 13% in the geosciences. Women's salaries also lag: the median salary for all Ph.D. geoscientists was $60,000; for women, the figure is $47,000 [NSF, 1999b]. The growing number of women students is a step in the right direction, but only a step.
Amphibious seismic survey images plate interface at 1960 Chile Earthquake
Authors: Krawcyzk C. ,   The SPOC Team
Published: October 2006

The southern central Chilean margin at the site of the largest historically recorded earthquake in the Valdivia region, in 1960 (Mw = 9.5), is part of the 5000‐km‐long active subduction system whose geodynamic evolution is controversially debated and poorly understood. Covering the area between 36° and 40°S, the oceanic crust is segmented by prominent fracture zones. The offshore forearc and its onshore continuation show a complex image with segments of varying geophysical character, and several fault systems active during the past 24 m.y.

In autumn 2001, the project SPOC was organized to study the Subduction Processes Off Chile, with a focus on the seismogenic coupling zone and the forearc. The acquired seismic data crossing the Chilean subduction system were gathered in a combined offshore‐onshore survey and provide new insights into the lithospheric structure and evolution of active margins with insignificant frontal accretion.
The MOBB experiment: A prototype permanent off‐shore ocean bottom broadband station
Authors: Romanowicz Barbara , Stakes Debra , Uhrhammer Robert , McGill Paul , Neuhauser Doug , Ramirez Tony , Dolenc David
Published: October 2006

Technical accomplishments of the past 10 years in the design and deployment of sea floor broadband seismic systems are now making it possible to start addressing the issue of the limited coverage of the Earth that can be achieved through land‐based installations, at the regional or global scale. In particular, the September 2002 Ocean Mantle Dynamics (OMD) workshop in Snowbird, Utah [OMD Workshop Committee, 2003] proposed the development of two “leap‐frogging arrays” of about 30 broadband sea floor instruments to fill geophysically important target holes in ocean coverage for deployment periods of 1 to 2 years. The rationale for an off‐shore (“Webfoot”) component of the SArray/Earth‐scope “Bigfoot” array was also highlighted at this meeting, pointing out that the study of the North American continent should not stop at the ocean margin.

The ocean floor environment is challenging for broadband seismology for several reasons. Broadband seismometers cannot be simply “dropped off” a ship with the expectation that they will produce useable data, particularly on the horizontal components. Several pilot experiments, [e.g., Montagner et al., 1994; OSN1, 1998; Suyehiro et al., 2002] have addressed the issue of optimal installation of ocean bottom stations, and in particular, have carried out comparisons between borehole, sea floor, and buried sea floor installations.
Atmospheric Pollution: History, Science and Regulation
Authors: Fraser Matt
Published: October 2006

There is no shortage of textbooks available for introductory courses on air pollution. However, finding a text that is ideally suited for a specific course can be nearly impossible, since the focus of the text never quite matches what you want to teach in the course. Atmospheric Pollution: History, Science and Regulation, by Mark Z. Jacobson, provides a novel perspective on air pollution by examining the historical developments of air pollution science and regulation prior to presenting information on the major air pollution issues of today.

The first two chapters set the stage for studying the atmosphere from a historical context. In the first chapter, the basics of atmospheric gases and particles are defined, and the topic progresses to a historical accounting of the discoveries of the important atmospheric chemicals. The author discusses the experiments that determined the composition of the various trace gases present in the atmosphere, and how the misinterpretation of some experiments led to incorrect conclusions about the makeup of atmospheric trace gases. The second chapter focuses on the evolution of the Earth's atmosphere, beginning at the time of formation of the Sun and Earth, the evolution of a pre‐biotic atmosphere into an anoxic biotic atmosphere, and finally the evolution of oxygen through photosynthesis. This material provided new insight into how trace gases were first discovered and how the atmosphere evolved. While this might be fascinating to someone who has spent years studying the present‐day atmosphere, it may not necessarily be important in an introductory course.
Geophysical project in Ethiopia studies continental breakup
Authors: Maguire P. K. H. , Ebinger C. J. , Stuart G. W. , Mackenzie G. D. , Whaler K. A. , Kendall J.‐M. , Khan M. A. , Fowler C. M. R. , Klemperer S. L. , Keller G. R. , Harder S. , Furman T. , Mickus K. , Asfaw Laike , Ayele Atalay , Abebe Bekele
Published: October 2006

As continental rift zones evolve to sea floor spreading, they do so through progressive episodes of lithospheric stretching, heating, and magmatism, yet the actual process of continental breakup is poorly understood. The East African Rift system in northeastern Ethiopia is central to our understanding of this process, as it lies at the transition between continental and oceanic rifting [Ebinger and Casey, 2001].

We are exploring the kinematics and dynamics of continental breakup through the Ethiopia Afar Geoscientific Lithospheric Experiment (EAGLE), which aims to probe the crust and upper mantle structure between the Main Ethiopian (continental) and Afar (ocean spreading) rifts, a region providing an ideal laboratory to examine the process of breakup as it is occurring. EAGLE is a multidisciplinary study centered around the most advanced seismic project yet undertaken in Africa (Figure l). Our study follows the Kenya Rift International Seismic Project [e.g., KRISP Working Group, 1995],and capitalizes on the IRIS/PASSCAL broadband seismic array [Nyblade and Langston, 2002], providing a telescoping view of the East African Rift within this suspected plume province.
Investigating environmental tectonics in Northern Alpine Foreland of Europe
Authors: Cloetingh Sierd , Ziegler Peter , Cornu Tristan ,   ENTEC Working Group
Published: October 2006

Until now, research on neotectonics and related seismicity has mostly focused on active plate boundaries characterized by a generally high level of earthquake activity. Current seismic hazard estimates for intraplate areas are commonly based on probabilistic analyses of historical and instrumental earthquake data. The accuracy of these hazard estimates is limited by the nature of the data (e.g., ambiguous historical sources), and by the restriction of available earthquake catalogues to time scales of only a few hundred years. Both of these are geologically insignificant and unsuitable for describing tectonic processes causing earthquakes. This is especially relevant to intraplate regions, where faults show low slip rates resulting in long average recurrence times for large earthquakes (103 to 106 yrs), such as the devastating Basel earthquake of 1356, with an estimated magnitude of 6.5.
Ocean‐atmosphere‐sea ice‐snowpack interactions in the Arctic, and global change
Authors: Shepson Paul , Matrai Paty , Barrie Len , Bottenheim Jan
Published: October 2006

The discovery of the nature of Arctic haze in the late 1970s and early 1980s [Barrie, 1986] showed that the Arctic is not a pristine environment isolated from human activity, but rather, a region well connected to natural and anthropogenic sources of chemicals by winds, ice movement, and marine currents. Copious pollution is carried on the winds to the Arctic during winter and spring from Europe and northern Asia. The study of this phenomenon led serendipitously to the discovery of ozone depletion chemistry in the Arctic marine boundary layer (MBL) at polar sunrise [Oltmans, 1981; Bottenheim et al., 1986]. In turn, research to understand surface ozone depletion chemistry led to the discovery that it is perturbing the biogeochemical cycle of many elements such as mercury; and that ozone depletion chemistry is likely to have a significant impact on radiative transfer in the atmospheric layer near the surface, with important consequences on the air‐sea exchange of biologically‐mediated compounds.
Advancing remote sensing of volcanic clouds
Authors: Rose William I.
Published: October 2006

A second international workshop on the remote sensing of volcanic clouds was recently held to improve and expand the use of satellite‐based remote sensing data for hazard mitigation and other research purposes, such as volcano‐atmosphere interactions and chemical and meteorological effects on the troposphere and stratosphere. Forty‐six researchers attended, representing 11 countries, 10 universities, and several government meteorological and volcanological organizations. Also represented were the Volcanic Ash Aviation Centers in Washington, D.C.; Anchorage; Montreal; Darwin; London; and Tokyo, which monitor volcanic ash plumes and predict their displacement within their areas of responsibility The nine VAACs were established by the International Civil Aviation Organization (ICAO) to address various aviation concerns related to volcanic ash.
Seismic experiment searches for active magmatic source in deep lithosphere, central Europe
Authors: Babska Vladišlav , Plomerová Jaroslava ,   BOHEMA Working Group
Published: October 2006

The Bohemian Massif (BM) is the largest coherent surface exposure of basement rocks in central Europe. It is a geodynamically active part of the Hercynian orogenic belt representing a collage of magmatic arcs and micro‐continents caused by the collision of Laurasia (Laurentia‐Baltica) and Africa (Gondwana). The general northwest direction of accretion is typical of the northern part of the Hercynian belt. Irregularly‐shaped colliding blocks resulted in a very complicated structure of convergence, lithospheric subduction, and crustal shortening, followed by extensional processes and rifting.

The western part of the Bohemian Massif is the well‐known health and resort landscape of Bohemia, Saxonia, and Bavaria, with Karlovy Vary (Karlsbad) as the flagship of the famous spa towns of the region (Figure 1). Allegedly, the Emperor Charles IV founded the spa in the years 1347–1349 at the site, which was already well known for its hot springs. For centuries, 12 springs in Karlovy Vary ranging in temperatures between 42°C and 72°C have been exploited, especially for the treatment of digestive system disorders and metabolic diseases.
Satellite data help predict terrestrial carbon sinks
Authors: Potter Christopher , Klooster Steven , Genovese Vanessa , Myneni Ranga
Published: October 2006

Accurate estimates of how much CO2 ecosystems can absorb will be fundamental to successful systems of international carbon accounting. NASA's Terra satellite platform, with the moderate resolution imaging spectro‐radiometer (MODIS) instrument on board, provides a new era of observations for carbon cycle assessments. Direct input of satellite vegetation index “greenness” data from the MODIS sensor into ecosystem simulation models can be used to estimate spatial variability in monthly net primary production (NPP), biomass accumulation, and litter fall inputs to soil carbon pools. Global NPP of vegetation can be predicted using the relationship between leaf reflectance properties and the fraction of absorption of photosynthetically active radiation (FPAR) [Knyazikhin et al., 1999].
Deep electromagnetic soundings conducted in Trans‐European Suture Zone
Authors: Semenov Vladimir Yu. , Jozwiak Waldemar , Pek Josef
Published: October 2006

A consortium of nine geophysical institutions recently carried out a large‐scale geomagnetic experiment focused on revealing the deep electrical structure beneath central and eastern Europe around the Trans‐European Suture Zone (TESZ), the region's first‐order geological lineament. The TESZ is considered a broad zone of deformation that crosses all of Europe, from the British Isles in the northwest to the Black Sea area in the southeast, and it most likely continues in North America [Keller and Hatcher, 1999].

The geomagnetic experiment was called Central Europe Mantle Geoelectrical Structure (CEMES). Initiated by Polish scientists, geophysicists from eight other countries joined the project during a NATO Advanced Research Workshop held in the spring of 2001 in Belsk, Poland. The experimental phase of the project was held from 2001 through 2002; and altogether, 12 geomagnetic observatories, the international codes of which are shown among others in Figure 1, took part in acquiring the data. They will serve the objective of inferring information on the mantle conductivity structures beneath the region of TESZ, as well as beneath surrounding units, specifically the western part of the East European Craton (EEC), Variscides, including the Bohemian Massif, the Carpathians, and the Pannonian Basin.
The role of greenhouse gases in orbital‐scale climatic changes
Authors: Ruddiman William F.
Published: October 2006

A decade ago, the Spectral Analysis, Mapping and Prediction Project (SPECMAP) analyzed the relationship between changes in Earth's orbit produced by variations in obliquity precession, and eccentricity and all available long‐term responses observed within the climate system [Imbrie et al., 1992, 1993]. In the intervening decade, improvements to the gas time scale for the Vostok ice core from Antarctica have provided age constraints on greenhouse gas changes that are comparable to those for climatic responses based on marine δ18O signals; these prompted a new investigation of the orbital‐scale climatic changes.

Milutin Milankovitch proposed that variations in northern hemisphere summer radiation at the 22,000‐yr precession cycle and 41,000‐yr obliquity cycle drive northern ice sheets by summer ablation control of ice mass balance, and he inferred that ice sheet responses should lag 5000 years behind summer radiation forcing. In confirmation of Milankovitch's hypothesis, Hays et al. [1976] found that coherent changes in δ18O lag several thousand years behind the forcing at those two orbital cycles. Imbrie et al. [1984] determined that δ18O lags of 5000 years behind precession and 8000 years behind obliquity simultaneously satisfied a 17,000‐yr time constant of ice response (Figure 1a). These studies also detected a dominant δ18O response at 100,000 years that Milankovitch had not anticipated because direct solar forcing at that period is negligible. Because the 100,000‐yr δ18O signal is phased with orbital eccentricity, Hays et al. [1976] called it a “paced” response but left its origin unresolved.
Drilling probes past carbon cycle perturbations on the Demerara Rise
Authors: Erbacher Jochen , Mosher David , Malone Mitchell ,   ODP Leg 207 Scientific Party
Published: October 2006

Ocean Drilling Program (ODP) Leg 207 recently cored sediments on the Demerara Rise at ∼9°N in the tropical Atlantic and successfully recovered continuous records of the Paleocene/Eocene Thermal Maximum (PETM), the Cretaceous/Tertiary boundary (K/T), and Cretaceous Ocean Anoxic Events (OAEs). The Demerara Rise, north of Suriname and French Guyana, South America, is an ideal drilling target because expanded sections of Cretaceous‐ and Paleogene‐age deep‐sea sediments are shallowly buried and exist with good stratigraphic control in expanded sections. Furthermore, the northwestern escarpment of the Demerara Rise offered the possibility of recovering sediments along a paleo‐depth transect. The paleogeographic position of the Demerara Rise lies within the core of the tropics in a location near the Equatorial Atlantic Gateway between South America and Africa, which is believed to have played an important role in controlling changes in global climate during the Cretaceous.
Sea ice index monitors polar ice extent
Authors: Fetterer Florence , Knowles Kenneth
Published: October 2006

In September 2002, Arctic sea ice extent reached a minimum unprecedented in 24 years of satellite passive microwave observations, and almost certainly unmatched in 50 years of charting Arctic ice [Serreze et al., 2003]. Again, in September 2003, ice retreated to an unusually low extent, almost equaling the previous year's minimum (Figure l). The Sea Ice Index (http://nsidc.org/data/seaice_index/), an easy‐to‐use source of information on sea ice trends and anomalies, assists in observing these minima. The Sea Ice Index is intended for both researchers and the scientifically inclined general public.
Error made in reports of main field decay
Authors: Campbell Wallace H.
Published: October 2006

A special session, “Decay of the Main Field,” was held at the AGU Fall Meeting in San Francisco, California, 11 December 2003. Two of the presentation topics were the recent main dipole field decay indicated by the International Geomagnetic Field (IGRF) representation and the unique properties of the second and third field harmonics obtained from the IGRF. The Earth's dipole field is certainly decaying, but neither at the strength nor rate announced at the AGU meeting. And the higher harmonics of the IGRF are especially important for any calculation of the expected magnetic field at a location on the Earth's surface, but only for that purpose. The large second and third field harmonics mainly arise because of the offset of the Earth's main dipole field from the geographical center.
Argo profiling floats bring new era of in situ ocean observations
Authors: Gould John , Roemmich Dean , Wijffels Susan , Freeland Howard , Ignaszewsky Mark , Jianping Xu , Pouliquen Sylvie , Desaubies Yves , Send Uwe , Radhakrishnan Kopillil , Takeuchi Kensuke , Kim Kuh , Danchenkov Mikhail , Sutton Phil , King Brian , Owens Breck , Riser Steve
Published: October 2006

The Argo profiling float project will enable, for the first time, continuous global observations of the temperature, salinity, and velocity of the upper ocean in near‐real time.This new capability will improve our understanding of the ocean's role in climate, as well as spawn an enormous range of valuable ocean applications. Because over 90% of the observed increase in heat content of the air/land/sea climate system over the past 50 years occurred in the ocean [Leuitus et al., 2001], Argo will effectively monitor the pulse of the global heat balance.The end of 2003 was marked by two significant events for Argo. In mid‐November 2003, over 200 scientists from 22 countries met at Argo's first science workshop to discuss early results from the floats. Two weeks later, Argo had 1000 profiling floats—one‐third of the target total—delivering data. As of 7 May that total was 1171.
U.S. stream flow measurement and data dissemination improve
Authors: Hirsch Robert M. , Costa John E.
Published: October 2006

Stream flow information is essential for many important uses across a broad range of scales, including global water balances, engineering design, flood forecasting, reservoir operations, navigation, water supply, recreation, and environmental management. Growing populations and competing priorities for water, including preservation and restoration of aquatic habitat, are spurring demand for more accurate, timely, and accessible water data. To be most useful, stream flow information must be collected in a standardized manner, with a known accuracy and for a long and continuous time period.

The U.S. Geological Survey (USGS) operates over 7000 stream gauges nationwide, which constitute over 90% of the nation's stream gauges that provide daily stream flow records, and that are accessible to the public. Most stream flow records are not based on direct measurement of river discharge, but are derived from continuous measurements of river elevations or stage. These stage data, recorded to 3‐mm accuracy are then converted into discharge by use of a stage/discharge relation (rating) that is unique for each stream gauging location. Because stream beds and banks are not static, neither is the stage discharge rating. Much of the effort and cost associated with stream gauging lies in establishing and updating this relation. Ten years ago, USGS personnel would visit stream gauging stations 8 to 10 times a year to make direct measurements of river depth, width, and velocity using mechanical instruments: a sounding rod or cable, a tagline, and a current meter. From these data, flow rates were computed.The range of measured flow and concurrent river stages were then used to build the rating curve for each site and to track changes to the rating curve.
Central Arctic: Battleground of natural and man‐made climate forcing
Authors: Kukla George
Published: October 2006

Alarming observations have been reported on recent climate changes in the Arctic. Sea ice is thinning and shrinking, and its area was the lowest since 1979 when systematic microwave satellite observations began. Will the summertime ice completely disappear due to man‐made greenhouse gases as predicted by climate models?

Twenty‐three experts from the United States and abroad gathered in January to address this question. Additional scientists participated in the discussion sessions or contributed by mail.
U.S. constructed area approaches the size of Ohio
Authors: Elvidge Christopher D. , Milesi Cristina , Dietz John B. , Tuttle Benjamin T. , Sutton Paul C. , Nemani Ramakrishna , Vogelmann James E.
Published: October 2006

The construction and maintenance of impervious surfaces—buildings, roads, parking lots, roofs, etc.—constitute a major human alteration of the land surface, changing the local hydrology, climate, and carbon cycling. Three types of national coverage data were used to model the spatial distribution and density of the impervious surface area (ISA) for the conterminous United States. The results (Figure 1) indicate that total ISA of the 48 states and Washington, D.C. is 112,610 km2 (±12,725 km2), which is slightly smaller than the state of Ohio (116,534 km2) and slightly larger than the area of herbaceous wetlands (98,460 km2) of the conterminous United States [Vogelmann et al., 2001].
Space weather research elucidates risks to technological infrastructure
Authors: Jansen F. , Pirjola R.
Published: October 2006

“Space weather” refers to electromagnetic and particle conditions in space near the Earth that may produce problems for spaceborne and ground‐based technological systems, and which may even be dangerous to humans. Explosions on the Sun are the primary origin of space weather phenomena. The solar wind carries the effect to the Earth, and the interaction with the geomagnetic field affects the magnetosphere, which has a sharp boundary on the dayside and a long tail in the nightside. The plasmaphysical coupling between the magnetosphere and the ionosphere is also important. The entire chain, starting from the Sun and ending at geomagnetic storms observed at the Earth's surface, involves complicated processes whose better understanding will lead to possibilities of avoiding harmful impacts. In space weather research, galactic cosmic rays have to be considered as a secondary source.
Understanding continent‐ocean sediment transfer
Authors: Mulder T. , Cirac P. , Gaudin M. , Bourillet J.‐F. , Trainer J. , Normand A. , Weber O. , Griboulard R. , Jouanneau J.‐M. , Anschutz P. , Jorissen F. J.
Published: October 2006

Submarine canyons are narrow but deep submarine valleys that extend for hundreds of meters. They represent the most impressive structures that shape the present morphology of passive continental margins. They can occur off the mouth of rivers: the Tagus, Zaire, Amazon, and Orinoco in the Atlantic; the Indus in the Indian Ocean; and the Var, Rhone, and Ebro in the Mediterranean. Some are at times disconnected from any stream mouth such as the Nazare canyon, off Portugal, despite the fact that it is close to the coast. Some were connected to a river mouth during lowstands of sea level, such as the Wilmington canyon in the northwest Atlantic, or the Blackmud canyon in the northeast Atlantic.
Soliciting participation in climate model analyses leading to IPCC fourth assessment report
Authors: Meehl Gerald , Covey CurtCurt , Latif MojibMojib
Published: October 2006

Looking for a way to get involved in the IPCC Fourth Assessment Report (AR4)?

Here's an opportunity to do so. You can sign up now to analyze some aspect of the 20th century or future climate simulations being performed by about 14 modeling groups around the world. These analyses will begin when the model simulations currently running are completed and the model data is collected and archived in September of this year.
The western U.S. drought: How bad is it?
Authors: Piechota Thomas , Timilsena Janak , Tootle Glenn , Hidalgo Hugo
Published: October 2006

Historical stream flow records and the forecast for 2004 make the current (1999–2004) drought in the southwestern United States the worst one in the past 80 years for portions of the Upper Colorado River Basin (UCRB).

For the Colorado River (near Cisco, Utah), the cumulative stream flow deficit (departure from long‐term mean) for the current drought is almost 11 km8, or approximately 2 years of average stream flow Although the current drought is the most significant, based on historical stream flow records, is it the worst ever?
Is the climate of the Bering Sea warming and affecting the ecosystem?
Authors: Overland James E. , Stabeno Phyllis J.
Published: October 2006

Observations from the Bering Sea are good indicators of decadal shifts in climate, as the Bering is a transition region between the cold, dry Arctic air mass to the north, and the moist, relatively warm maritime air mass to the south. The Bering Sea is also a transition region between Arctic and sub‐Arctic ecosystems; this boundary can be loosely identified with the extent of winter sea‐ice cover.

Like a similar transition zone in the eastern North Atlantic [Beaugrand et al., 2002], the Bering Sea is experiencing a northward biogeographical shift in response to changing temperature and atmospheric forcing. If this shift continues over the next decade, it will have major impacts on commercial and subsistence harvests as Arctic species are displaced by sub‐Arctic species. The stakes are enormous, as this rich and diverse ecosystem currently provides 47% of the U.S. fishery production by weight, and is home to 80% of the U.S. sea bird population, 95% of northern fur seals, and major populations of Steller sea lions, walrus, and whales.