bluuebunny/crossref_metadata_2025 huggingface dataset:
Cancer control in women. Update 2003
Authors: Boyle P. , Leon M.E. , Maisonneuve P. , Autier P.
Published: April 2004

The global cancer burden in women appeared to be increasing quickly at the end of the twentieth century with notable increases in the absolute numbers of cases of breast, cervix, lung and colorectal cancer of concern. However, prospects for cancer control in women appear to be good within our current knowledge and deserve close attention. Rates of lung cancer in women are increasing substantially in many countries and seem set to overtake breast cancer as the commonest form of cancer death in women in many parts of the world. These changes are due to the effects of cigarette smoking, a habit which women widely embraced during the second half of the last century. The high levels of smoking current in young women, which have yet to have their full impact on death rates, constitute an important hazard not only for future cancer risks but for several other important causes of death.

Although the breast is the commonest form of cancer in women in most western countries, the etiology of this disease remains elusive and preventable causes remain to be identified. Endogenous hormones also appear to have a role in cancer risk in women: oral contraceptives seem to increase slightly the risk of breast cancer in users in the use, and in the immediate post‐use, period, but ten years after cessation the risk returns to that of never users. Oral contraceptive usage also appears to be protective against ovarian and endometrial cancer. The use of Hormonal Replacement Therapy (HRT) appears to increase the risk of endometrial cancer and a positive association with breast cancer risk appears to exist.

Within our current knowledge of the epidemiology of cancer in women, the most important Cancer Control strategy is the prevention of cigarette smoking and the increase in the prevalence of adult women quitting smoking. Screening has also shown to be effective in reducing incidence and mortality of cervix cancer and mortality from breast and colorectal cancer. Although more work is needed, it is becoming clear that there could be an important role of HPV testing to further enhance cervix cancer screening.
Promising directions for the diagnosis and management of gynecological cancers
Authors: Kohn E.C. , Mills G.B. , Liotta L.
Published: April 2004

Diagnosis and management of cancer requires tools with both high sensitivity and specificity. The minimally invasive cervical smear has demonstrated how a test, even one with low specificity, can change the public health profile of a cancer from a late stage deadly disease to early diagnosis with rare tumor‐related deaths. The benefit of such a test is best demonstrated by the low frequency of cervix cancer and its good outcome in countries where this test is readily available and used with appropriate secondary follow up. Early and specific symptoms, and identification and prevention for high risk groups has had similar impact for endometrial cancer. Neither a robust test, nor reliable or specific early symptoms are available for ovarian cancer, making clinical and scientific advances in this area a critical world‐wide need. Current approaches testing one protein or gene marker at a time will not address this crisis expeditiously. New sensitive, specific, accurate, and reliable technologies that can be implemented using high throughput mechanisms are needed at as low a cost as possible. Ideally, these technologies should be focused on readily available patient resources, such as blood or urine, or as in the case of cervix cancer, minimally invasive informative approaches such as cervical smears. Techniques that allow data mining from a large input database overcome the slow advances of one protein‐one gene investigation, and further address the multi‐faceted carcinogenesis process occurring even in germ line mutation‐associated malignancy. Proteomics, the study of the cellular proteins and their activation states, has led the progress in biomarker development for ovarian and other cancers and is being applied to management assessment. Amenable to high throughput, internet interface, and representative of the proteome spectrum, proteomic technology is the newest and most promising direction for translational developments in gynecologic cancers.
Interactions between pool geometry and hydraulics
Authors: Thompson Douglas M. , Nelson Jonathan M. , Wohl Ellen E.
Published: April 2004

An experimental and computational research approach was used to determine interactions between pool geometry and hydraulics. A 20‐m‐long, 1.8‐m‐wide flume was used to investigate the effect of four different geometric aspects of pool shape on flow velocity. Plywood sections were used to systematically alter constriction width, pool depth, pool length, and pool exit‐slope gradient, each at two separate levels. Using the resulting 16 unique geometries with measured pool velocities in four‐way factorial analyses produced an empirical assessment of the role of the four geometric aspects on the pool flow patterns and hence the stability of the pool. To complement the conclusions of these analyses, a two‐dimensional computational flow model was used to investigate the relationships between pool geometry and flow patterns over a wider range of conditions. Both experimental and computational results show that constriction and depth effects dominate in the jet section of the pool and that pool length exhibits an increasing effect within the recirculating‐eddy system. The pool exit slope appears to force flow reattachment. Pool length controls recirculating‐eddy length and vena contracta strength. In turn, the vena contracta and recirculating eddy control velocities throughout the pool.
DOAS moonlight observation of atmospheric NO3 in the Arctic winter
Authors: Wagner Thomas , Otten Cornelius , Pfeilsticker Klaus , Pundt Irene , Platt Ulrich
Published: April 2004

The diurnal variation of the vertical column density (VCD) of NO3 was measured during 16 nights in the winter 1993/94 (mid January–early March) at Kiruna (68°N, 21°E) using the moon as light source. The lunar zenith angle (LZA) dependence of the NO3 absorption indicates that the majority (≥75%) of the atmospheric column was located in the stratosphere. After a rapid increase within the first two hours after sunset the measured NO3 VCDs only slowly increase during the rest of the night. The NO3 VCDs (≤ 3.2 · 1013 molec/cm²) are significantly larger compared to previous NO3 measurements in the Arctic. These differences can be most probably attributed to different atmospheric temperatures and differences in the correction of the H2O absorption structure in the NO3 analysis.
Radiation transport simulation by means of a fully equivalent operational model
Authors: Shorter Jeffrey , Ip Percila , Rabitz Herschel
Published: April 2004

The radiation transport component of atmospheric modelling codes is typically a major contributor to the overall execution time. This paper introduces a fully equivalent operational model (FEOM) as a high speed replacement for traditional transport modules. The input information to the FEOM is the atmospheric trace gases and temperature profiles as a function of altitude as well as the surface temperature and albedo. The FEOM operates by identifying how these latter variables impact the heating rate as a function of altitude. This relationship is compactly represented by the FEOM in terms of a hierarchy of cooperativity relations amongst the input variables thereby producing an accurate equivalent module. In the present test of the concept, water vapor and temperature are treated as altitude dependent inputs, and the FEOM is shown to be better than 97% accurate over a broad input variable range, while simultaneously being approximately 10³ times faster than the traditional radiation transport module it replaced.
Is magnetospheric line radiation man‐made?
Authors: Rodger Craig J. , Clilverd Mark A. , Yearby Keith H. , Smith Andy J.
Published: April 2004

Magnetospheric line radiation (MLR) events are relatively narrowband VLF signals (∼30 Hz) that sometimes drift in frequency and that have been observed in both ground‐based and satellite data sets. We present the result of a survey undertaken on the basis of measurements made of MLR events observed at Halley station, Antarctica (75°35'S, 26°33'W, L≈4.3) during June, July, September, and December 1995, specifically to examine whether there is a link between MLR and power line harmonic radiation (PLHR). We find that (1) the diurnal variation of MLR occurrence at Halley does not resemble the expected load pattern in the industrialized conjugate hemisphere; (2) MLR does not show the pronounced east‐west asymmetry in the distribution of arrival directions which would be the case if it was linked to North American electrical load; (3) MLR does not show an immediate association with geomagnetic activity, as would be expected from increases in PLHR levels produced by geomagnetically‐induced currents saturating transformers; and (4) there is no evidence of a Sunday, weekend, or other 7‐day cycle in the occurrence of MLR. Taken together these results strongly suggest that MLR is a natural VLF emission and is not primarily caused by PLHR. In addition, Halley data have been examined to determine whether the intensity of all types of VLF emissions are influenced by PLHR. We find that (1) there is no significant difference between weekdays and weekends over the frequency range 0.5–9.3 kHz and (2) there is no consistent change in wave intensity that is observed around any of the major North American holiday periods. It is concluded that PLHR is not a significant influence on geospace as viewed from Halley.
Study of weak substorms observed during December 8, 1990, Geospace Environment Modeling campaign: Timing of different types of substorm onsets
Authors: Mishin V. M. , Russell C. T. , Saifudinova T. I. , Bazarzhapov A. D.
Published: April 2004

We define an expansion onset (synonymous with the main breakup) to be one with sufficient signatures of open tail reconnection. Earlier onsets, which we term initial onsets, occur before the expansion onset, without the signatures of open tail reconnection but with other signs of a clear substorm onset. These two types of substorm onsets and their timing are discussed herein in a study of selected substorm‐like events. During the 10‐hour interval studied, five impulses of the Perreault‐Akasofu index ε were observed with comparable peak values. However, the observed magnetospheric responses were very different in terms of equatorward motion and poleward expansion of the auroral oval. We conclude that the occurrence either of an initial onset or of a full onset (under similar boundary conditions) depends on the amount of stored free energy, proportional to the tail length, which is controlled by the input power. The earlier or initial onset marks a sudden change in the convection pattern in the nightside. This onset could mark the initiation of reconnection on closed field lines while the expansion onset could mark the initiation of reconnection on open field lines.
Autumn sea ice thickness, ridging and heat flux variability in and adjacent to Terra Nova Bay, Ross Sea, Antarctica
Authors: Jeffries Martin O. , Morris Kim , Maksym Ted , Kozlenko Nickolai , Tin Tina
Published: April 2004

The variability of sea ice thickness and snow depth observed from the R/V Nathaniel B. Palmer in late May 1998 in and adjacent to Terra Nova Bay (TNB), Ross Sea, Antarctica, is described. Conductive heat fluxes are estimated on the basis of the observed snow and ice thicknesses. There was only 6% areal coverage of open water in TNB and 87% of the areal coverage of unridged ice was ≤0.3 m thick. Between the western and eastern margins of TNB there were increases in the area‐weighted unridged ice thickness (0.05–0.25 m) and the areal extent of ridging (2.5–18.5%). Ridged ice accounted for 44–66% of the total ice mass in TNB and was as vital to thickening the ice cover as it was outside the bay, where 30–60% of the total ice mass was contained within the 5–35% of ice that was ridged. Satellite passive microwave (Special Sensor Microwave Imager SSM/I) data show that the extensive ice cover in TNB was normal for this time of year probably because of the blocking effect of thick, ridged, 100% concentration pack ice outside the bay. Despite the extensive ice cover in TNB, there was an order of magnitude difference in area‐weighted mean heat flux between the bay and the pack ice. For example, depending on the choice of bulk snow thermal conductivity value ks (0.14 or 0.31 W m−1 K−1), the heat flux values for unridged ice were 199 or 216 W m−2 in TNB versus 35 or 49 W m−2 on the inbound pack ice leg and 20 or 39 W m−2 on the outbound pack ice leg. Factoring in the contribution of ridges to the ice thickness distribution decreased the heat flux in the bay and the pack ice by 25 or 36%, depending on ks. The greatest proportion of the heat flux in TNB occurred through the ice; no more than 30% of the heat loss was from open water. Since the ice conditions observed in TNB were apparently normal for the time of year, the heat fluxes also must have been quite normal.
Contribution of equatorial Pacific winds to southern tropical Indian Ocean Rossby waves
Authors: Potemra James T.
Published: April 2004

Westward propagating features, identified as Rossby waves, have been observed and modeled in the southern tropical Indian Ocean (STIO) between 10° and 30°S. These STIO Rossby waves, which have broad zonal and meridional extents, could interact with the westward flowing South Equatorial Current (SEC) as well as coastal currents on the south shore of Java (the South Java Current) and along the western shore of Australia (the Leeuwin Current). Previous work has attributed these waves to variations in wind stress along the west coast of Australia, Ekman pumping in the STIO interior, and a combination of both. This study investigates the importance of a third factor: remotely forced coastal Kelvin waves. Observations show that changes in wind stress curl in the eastern equatorial Pacific create annual upwelling and downwelling Rossby waves. Numerical model results confirm previous studies that demonstrate these waves, upon reaching the western boundary of the Pacific, create poleward propagating coastal Kelvin waves along the western shore of the Irian Jaya/Australia land mass. Direct observations of annual sea level variations along the northwest coast of Australia show a phase lag from the northernmost station to the southernmost that is not explained by direct wind forcing, suggesting that this signal is propagating from the Indonesian seas. It is shown in this work that when these waves reach the Indian Ocean, they are in phase with the local Ekman forcing and enhance the STIO Rossby waves. In the model the signal from the equatorial Pacific accounts for almost 80% of the energy of the STIO Rossby wave near the coast of Australia and 10% of the energy offshore.
A photosynthetic‐irradiance model for the upwelling region northeast of Taiwan and its application to the East China Sea
Authors: Gong Gwo‐Ching , Chang Jeng , Liang Ming‐Hsing
Published: April 2004

The
curves of upwelled Kuroshio waters in the sea northeast of Taiwan were constructed on a bimonthly basis from 1994 to 1995. The euphotic zone averaged light saturated specific primary productivity
and the initial slope seu of the
curves ranged from 3.655 to 10.583 g C [g Chl a]−1 hr−1 and from 0.012 to 0.028 g C [g Chl a]−1 hr−1 [μEinstein m−2 s−1]−1, respectively. The values of
between September and November were ∼2 times higher than those in other months. Here it is shown that the
curve parameters can be used to accurately estimate euphotic zone integrated primary production with deviations of <6% from the in situ measured values. It was also found that the
curve developed for the May 1995 cruise can also be applied to estimate primary production in the entire shelf region of the East China Sea south of Changjiang in spring, except at one station occupied by mainland China coastal waters.
A simple model of complex cusp ion dispersions during intervals of northward interplanetary magnetic field
Authors: Topliss S. M. , Owen C. J. , Peterson W. K.
Published: April 2004

During northward IMF intervals, cusp ion energy‐latitude dispersions observed by POLAR's TIMAS instrument often have two components. One dispersion decreases in energy with decreasing latitude. The second appears to split from the first and increases in energy as the equatorward edge of the cusp is approached. We present a simple model representing particle entry resulting from reconnection poleward of the cusp. We qualitatively show that split dispersions may arise on reconnected field lines which accelerate as they contract sunward into regions of lower magnetosheath flow velocity. The velocity filter effect produces the first dispersion by spreading particles entering near the reconnection site across a range of latitudes. The second, increasing energy dispersion, results from particles crossing the magnetopause at later times and lower latitudes. These particles are accelerated to higher energies due to the increased contraction speed of reconnected field lines at these latitudes.
Positive and negative ionospheric disturbances at middle latitudes during geomagnetic storms
Authors: Tsagouri I. , Belehaki A. , Moraitis G. , Mavromichalaki H.
Published: April 2004

The morphology of middle latitude ionospheric disturbances in response to geomagnetic storms has been investigated to determine the phenomenological differences between positive and negative ionospheric storm effects, using foF2 observations from azimuthal chain of stations. To better organize the disturbance signatures, two ionospheric indices were introduced to describe the maximum positive (Dfu‐index) and negative (Dfl‐index) deviation observed during an ionospheric storm. A systematic appearance of nighttime positive effects was determined with a 24‐hour recurrence. The thermospheric‐ionospheric view associated with positive and negative storm effects proposed by Prolss (1993) was extended to encompass our observations. This test clearly demonstrates that such a model can capture most of the basic aspects of ionospheric storms, nevertheless the prominent feature of large nighttime enhancements in the ionization density have yet to be explained.
Proton precipitation related to Pcl pulsations
Authors: Yahnina T. A. , Yahnin A. G. , Kangas J. , Manninen J.
Published: April 2004

By the analysis of one‐year data from the low‐altitude NOAA satellite and on the basis of comparison with observations of Pcl pulsations at Sodankylä Geophysical Observatory, Finland, we have for the first time found and described a type of proton precipitation closely related to Pcl. It is characterised by a localised (∼1° of latitude) burst of both precipitating and locally trapped energetic (>30 keV) protons situated within the anisotropic precipitation zone. We found that intense Pcl on the ground can be observed at any distance (in MLT) from the footprint of satellite detecting the precipitation burst, but the probability of the Pcl observations strongly decreases with the distance. The frequency of the ground Pcl pulsations decreases with the increase of the proton burst latitude. These findings strongly confirm the idea that Pcl pulsations are the result of ion‐cyclotron instability of energetic ring current protons.
Generation of traveling convection vortices and field‐aligned currents in the magnetosphere by response to an interplanetary tangential discontinuity
Authors: Chen G. X. , Lin Y. , Cable S.
Published: April 2004

Three‐dimensional global magnetohydrodynamic simulations are conducted to study the response of the magnetosheath and the magnetosphere to an interplanetary tangential discontinuity (TD), across which the plasma density increases. A fast mode wave and a transmitted TD are generated in the magnetosheath by the interaction between the interplanetary TD and the bow shock. These waves further propagate and disturb the dayside magnetosphere. The fast mode compressional wave propagates downstream out of the dayside region in about 1 minute. The pressure enhancement associated with the transmitted TD later compresses the magnetopause significantly for several minutes. The generation of traveling convection vortices, shear Alfvén waves, and the associated field‐aligned currents (FACs) in the dayside magnetosphere by these pressure pulses is identified in the simulation.
Fast tailward stream observed in the distant tail associated with substorm: A multi‐instrument study
Authors: Rouquette S. , Jacquey C. , Le Contel O. , Lui A. T. Y. , Williams D. J. , McEntire R. W. , Mukai T. , Angelopoulos V. , Mozer F. S. , Nagai T. , Christon S. P. , Tsuruda K. , Reeves G. D.
Published: April 2004

We report a fast tailward flow event on July 19, 1994, observed in the deep tail by the GEOTAIL spacecraft then located at 133 RE from the Earth. This event was associated with an isolated substorm and GEOTAIL continuously remained inside the plasma sheet during the 2.5 hours period following the substorm onset. Thus, this event provides the opportunity to analyze the substorm dynamics in deep‐tail plasma sheet. Using magnetic field (MGF), electric field (EFD), plasma (LEP) and energetic particle (EPIC) data, we show that the fast tailward flow associated with the substorm expansion exhibited clear features: (i) the flow was quasi‐stationary during its 2.5 hours long duration; (ii) its structure across the plasma sheet thickness showed two layers associated with two clearly distinct flow regimes. In the central plasma sheet, the plasma speed was roughly constant and uniform. Its value was close to the lobe Alfven velocity. The separation between the two layers precisely took place where the plasma parameter beta was close to one.
Lidar and SAGE II observations of Shishaldin Volcano aerosols and lower stratospheric transport
Authors: Rizi Vincenzo , Masci Fabrizio , Redaelli Gianluca , Di Carlo Piero , Iarlori Marco , Visconti Guido , Thomason Larry W.
Published: April 2004

During May 1999, data collected with two of University of L'Aquila lidar systems, Italy show an increase in the stratospheric aerosol content at altitudes between 15 and 18 km. Our initial hypothesis is that these aerosols originated from the Shishaldin (Alaska) volcanic eruption of 19 April 1999. SAGE II observations, taken between Julian day 100 and 180, at latitudes above 40°N, show several sightings that are good candidates for volcanic aerosols. A trajectory analysis shows that a few SAGE II measurements are in space and time compatible with the Shishaldin eruption, and the aerosol enhancements observed by L'Aquila lidars have been also sampled by SAGE II, later and in different locations.
The clear‐sky index to separate clear‐sky from cloudy‐sky situations in climate research
Authors: Marty Christoph , Philipona Rolf
Published: April 2004

Accurate surface radiation fluxes are required to quantify atmosphere‐surface energy exchanges. In climate research, detailed investigations of the influence of diverse atmospheric conditions on radiative fluxes ask for a well‐defined distinction between clear‐sky and cloudy‐sky situations. Effects of clouds, the so called “cloud forcing”, can only be determined by explicitly separating clear‐sky from all‐sky radiation measurements. A Clear‐Sky Index (CSI) to separate clear‐sky from cloudy‐sky situations has therefore been introduced, using accurate atmospheric longwave radiation in conjunction with air temperature and humidity measurements at the station. This clear‐sky index, which has the important advantage to be applicable 24 hours a day, was tested and first used on measurements of the Alpine Surface Radiation Budget (ASRB) network, and was of prime importance for the determination of the altitude dependence of cloud forcing and greenhouse effect over the Alps.
Secular variations of atomic oxygen in the mesopause region induced by transient gravity wave packets
Authors: Hickey Michael P. , Walterscheid Richard L. , Richards Philip G.
Published: April 2004

We employ a 2‐dimensional, time‐dependent, fully nonlinear model of minor species in the mesopause region and our Spectral Full‐Wave Model to simulate the response of atomic oxygen (O) to a gravity wave packet in the mesopause region. We demonstrate that gravity waves affect the time‐averaged distribution of O in the mesosphere and lower thermosphere (MLT) region through the constituent fluxes the waves induce. Our conclusions are based on simulations of two wave packets that violate the non‐acceleration conditions through transience and dissipation. The net cycle‐averaged effect of the waves is to significantly increase (by as much as 50%) the O density through downward transport of O at low altitudes (≤90 km), and to deplete (by as much as 20%) the O density above ∼100 km altitude. Comparison with results obtained including only chemistry and diffusion suggests that the effects of gravity wave transport on the distribution of O in this region can be greater than the effects of eddy transport.
The increase in stratospheric water vapor from balloonborne, frostpoint hygrometer measurements at Washington, D.C., and Boulder, Colorado
Authors: Oltmans Samuel J. , Vömel Holger , Hofmann David J. , Rosenlof Karen H. , Kley Dieter
Published: April 2004

Stratospheric water vapor concentrations measured at two midlatitude locations in the northern hemisphere show water vapor amounts have increased at a rate of 1–1.5% yr−1 (0.05–0.07 ppmv yr−1) for the past 35 years. At Washington, D.C., measurements were made from 1964–1976, and at Boulder, Colorado, observations began in 1980 and continue to the present. While these two data sets do not comprise a single time series, they individually show increases over their respective measurement periods. At Boulder the trends do not show strong seasonal differences; significant increases are found throughout the year in the altitude range 16–28 km. In winter these trends are significant down to about 13 km.
Hydroxyl radical and ozone measurements in England during the solar eclipse of 11 August 1999
Authors: Abram Joanne P. , Creasey David J. , Heard Dwayne E. , Lee James D. , Pilling Michael J.
Published: April 2004

The solar eclipse on 11 August 1999 provided a rare opportunity to observe the remarkably dynamic character of atmospheric photochemistry. OH formation is driven by sunlight, and the rapid changes in light intensity associated with a solar eclipse provide a unique, yet natural perturbation experiment to study the response of OH and the ensuing chemistry. Highly time‐resolved measurements of OH and its rate of primary production were made at ground level during a 97% solar eclipse at Silwood Park, Ascot (51°25′N, 0°41′W) on 11 August 1999. The solar ultraviolet flux fell almost to nighttime levels, and the OH concentration decreased dramatically to below the detection limit of the instrument (2.1×105 molecule cm−3), before increasing again. The OH concentration is well correlated (r=0.88) to its rate of primary production from ozone photolysis. Shortly after maximum eclipse the concentration of ozone fell to 60% of its value at first contact. The study provides a striking demonstration of the dynamics of photochemical processes in the planetary boundary layer.
Energetic proton and electron dispersion signatures in the nightside magnetosheath supporting their leakage out of the magnetopause
Authors: Sarafopoulos D. V. , Athanasiu M. A. , Sibeck D. G. , McEntire R. W. , Sarris E. T. , Kokubun S.
Published: April 2004

Energetic proton and electron dispersion structures are detected at both the dawn and dusk nightside magnetosheath near the equatorial plane using the Geotail Energetic Particles and Ion Composition instrument data. A common feature of all the exhibited examples is that the vector magnetic field progressively scans from northward to southward through all the latitude angles while remaining almost within a plane intersecting the nightside magnetopause. For such geometries, at the duskside magnetosheath, peaks in the energetic electron flux precede those in the proton, whereas the opposite occurs at the dawnside magnetosheath. The peak fluxes of energetic protons (electrons) are measured at the duskside (dawnside) magnetosheath whenever the vector magnetic field points toward the central dusk (dawn) low‐latitude boundary layer (LLBL) region of the magnetosphere. Therefore we infer that the energetic electron (proton) source is essentially spatially limited to the central dawn (dusk) LLBL. We interpret the observed dispersion structures as spatial phenomena: Energetic electrons (protons) leak out from the equatorial dawn (dusk) LLBL and then are channeled along the draped magnetic field lines over the magnetopause toward spacecraft on the duskside (dawnside). The energetic electrons (protons) are detected in the duskside (dawnside) magnetosheath for a larger range of magnetic field latitude angles. In conclusion, the leakage of energetic particles through the magnetopause seems to be a process of great importance, in parallel with the merging one.
Permeability of a decollement zone: Results from a two‐well experiment in the Barbados accretionary complex
Authors: Screaton Elizabeth , Carson Bobb , Davis Earl , Becker Keir
Published: April 2004

Fault zones are hypothesized to play a major role in focusing fluid expulsion from accretionary complexes. A small number of previous investigations have examined the hydrogeologic properties of these fault zones using borehole packer or submersible‐based slug and constant rate flow tests. While these single‐well experiments yielded the first data on the permeability of active fault zones, they could only investigate a small area around the borehole and could not ensure reliable determination of formation storage properties. Recent data from an unplanned experiment in the décollement zone of the Barbados accretionary prism demonstrate the potential for multiple‐well hydrogeologic tests. Pressure data from a sealed borehole show a clear signal of drilling activity ∼45 m away. Analysis of the pressure response suggests that decollement zone permeability lies between 1.0 and 1.2×10−14m2. This permeability is ∼2–4 orders of magnitude greater than overlying and underlying sediment and thus appears sufficient to focus fluid flow along the decollement zone. This inadvertent test evaluated fault zone hydrogeologic parameters over a larger radius and longer timescale and at pressures closer to in situ than previous single‐well tests.
ScP constraints on ultralow‐velocity zone density and gradient thickness beneath the Pacific
Authors: Reasoner Colin , Revenaugh Justin
Published: April 2004

Short‐period teleseismic recordings of ScP from events in the Tonga‐Fiji (TF) and Marianas (MAR) subduction complexes made by the U.S. Geological Survey Hawaiian Volcano Observatory seismograph network are examined for evidence of pre‐ and post‐ScP phases. Such arrivals would be caused by interaction of ScP with ultralow‐velocity zone (ULVZ) structures at the base of the mantle and can therefore be used to constrain the properties and occurrence of ULVZs. The relative timings and amplitudes of ScP, two pre‐ScP phases, and one post‐ScP phase potentially provide very good constraints on ULVZ compressional and shear velocities, density, and thickness. For example, the amplitude of the topside S to P conversion, SdP, is very strongly density contrast dependent, while the amplitude of the last arriving ScsP, a core reflection that converts to P upon emergence from the ULVZ, is very strongly dependent on the shear velocity contrast. Previous data, largely consisting of diffracted SPdiffKS arrivals and reflected PcP precursors, have been unable to provide good constraints on these two properties. In our data set, though, we find very little evidence for pre‐ and post‐ScP arrivals, even for TF paths where abundant evidence for the presence of ULVZ exists. For the TF data distance range (43°–48°), precursor amplitudes are at or below the data noise level if the density contrast, δlnρ, is <10%, even for compressional velocity decreases of 10%. The one definitive ScsP observation for the TF data is best modeled by a layer 20 km thick with 9 and 27% υP and υS decreases, respectively, and a density increase ≤5%. The absence of ScsP in the remainder of the TF data may be caused either by patchy ULVZ occurrence or by vertical transition zones between mantle and ULVZ > 10 km thick which lower ScsP amplitudes below detectable levels. Taken together, these properties favor ULVZ material composed dominantly of partial melt, but a contribution from core‐mantle reaction products cannot be ruled out. For the MAR distance range (55°–58°), pre‐ and post‐ScP arrival amplitudes are predicted to be higher, although such arrivals are absent from the MAR recordings. However, the quality of our data is not sufficiently good to rule out the presence of thinner and/or more subdued ULVZ in that region.
Iodine speciation and deposition fluxes from the marine atmosphere
Authors: Baker A. R. , Tunnicliffe C. , Jickells T. D.
Published: April 2004

The concentration and speciation of iodine have been determined in wet and dry deposition at a coastal site over a 15‐month period. Deposition fluxes in rain (2.7 μmol m−2 yr−1) and aerosol (3.6–6.5 μmol m−2 yr−1) are the major routes for removal of iodine from the marine atmosphere onto the Earth's surface, with only a minor contribution from direct deposition of methyl iodide (0.003–0.17 μmol m−2 yr−1). Iodate (IO3−) is often considered to be the only species of iodine that is permanently removed to the aerosol phase, and IO3− may therefore be expected to be the dominant form of iodine in precipitation. However, iodide (I−) was found to constitute a significant fraction (5–100%) of iodine in both rain and aerosol. This implies that the rates of iodate formation and iodide volatilization (through reaction with hypohalous acids) are relatively slow. A third pool of aerosol iodine (nonvolatile organic compounds) may also contribute to removal of iodine from the atmosphere in dry or wet deposition.
Quantitative analysis of NOx emissions from Global Ozone Monitoring Experiment satellite image sequences
Authors: Leue C. , Wenig M. , Wagner T. , Klimm Oliver , Platt U. , Jähne B.
Published: April 2004

Nitric oxides (NOx) play a very important role among the anthropogenic trace gases. They affect human health and have an impact on ozone chemistry and climatic change. Here we describe a new method for the quantification of the global NOx budget from image sequences of the Global Ozone Monitoring Experiment (GOME) spectrometer on board the ERS 2 satellite. In contrast to measurements using ground‐based or balloon‐ or aircraft‐borne sensors, this instrument provides, for the first time, the possibility of observing global maps of NO2 column densities. As part of this work, algorithms were developed to analyze GOME spectra numerically and to extract physically relevant parameters from the resulting maps using image‐processing techniques. Column densities of NOx were determined using differential optical absorption spectroscopy (DOAS) [Platt, 1994]. By the combined use of an efficient B‐spline interpolation and an inversion algorithm based on Householder transformations, the numerical algorithms accelerate the retrievals by a factor of 26 with respect to previous methods. Moreover, techniques are presented for separating tropospheric and stratospheric NO2 colums and estimating the lifetime of NO2 in the troposphere. This allows determination of regional NOx source strengths. Independent of traditional methods, a global source strength of (43±20) Tg N yr−1 is estimated. The accuracy of this method is comparable to that of established statistical approaches.
Peroxy radical and related trace gas measurements in the boundary layer above the Atlantic Ocean
Authors: Burkert Jörn , Andrés‐Hernández Maria‐Dolores , Stöbener Dirk , Burrows John Philip , Weissenmayer Michael , Kraus Alexander
Published: April 2004

Measurements of peroxy radicals (RO2* = HO2 + ∑RO2, where HO2 is the hydroperoxyl radical and R is an organic group) were made using the chemical amplifier technique (PERCA) during the Air chemistry and Lidar studies of tropospheric and stratospheric species on the Atlantic Ocean (ALBATROSS) campaign on board the German research vessel Polarstern (cruise ANT XIV/1, 1996). The data obtained are compared to previous results from an earlier cruise in 1991 (ANT X/1). Reasonable agreement between the two data sets was observed, indicating the reliability of these measurements. Both data sets take into account the sensitivity of the radical amplifier to the presence of ambient water vapor. Maximum RO2* mixing ratios around noon between 40 and 80 pptv were measured. Nighttime signals were observed on many days. Air masses in different latitude regions in the North and South Atlantic could be characterized using back trajectories. In spite of the fact that the RO2* is relatively short lived, its mixing ratio appears to be influenced by the path traveled by the air mass somewhat higher levels being associated with sources of pollution. A box model based on CH4 and CO oxidation chemistry describes RO2* reasonably well but could not explain the persistent nighttime signals and the HCHO observed. An additional source of HCHO is required, indicating the importance of nonmethane hydrocarbon (NMHC) chemistry in the remote Atlantic boundary layer. Both back trajectories and variations of trace gas concentrations indicate that biomass burning, ship, and natural emissions are likely responsible for the observed deviations from the assumed chemistry.
Introduction to the Special Section: Geology and Geophysics of Io
Authors: McEwen Alfred S.
Published: April 2004

Io is about the size and density of Earth's Moon, but it has a dramatically different thermal state and geologic history. Tidal heating leads to intense volcanic and tectonic activity, so Io is an accelerated experiment in planetary geology and geophysics. Here we can witness volcanic activity on very large scales and at very high temperatures, perhaps providing insights into the early histories of the terrestrial planets.

Io has always been a high‐priority objective of Galileo, but her proximity to Jupiter's intense radiation belt has meant saving the best for last. An Io flyby occurred during Jupiter orbit insertion in December 1995, but a tape recorder anomaly led to cancellation of remote‐sensing observations. No further close flybys of Io were planned until the final two orbits (I24 and I25) of the Galileo Europa Mission (GEM) late in 1999 in order to minimize radiation damage to spacecraft and instrument electronics. I24 was an exciting encounter, with a spacecraft safing event and recovery just hours before Io closest approach. Most of the Io data were acquired, but not without problems. The majority of images from the Solid State Imager (SSI) were acquired in a mode that failed due to the cumulative radiation damage, producing garbled images, although reconstruction has produced some useful pictures [Keszthelyi et al., this issue]. Also, the grating of the Near‐Infrared Mapping Spectrometer (NIMS) became stuck leading to loss of spectral sampling [Lopes et al., this issue]. These instrument problems were mitigated by the use of different observation modes or strategies in subsequent orbits. The 125 polar pass included another safing event, this time eliminating the recording of the highest‐resolution observations. However, the medium‐resolution observations were of excellent quality and provided a surprise look at a new fissure eruption at Tvashtar Catena. GEM was followed by the Galileo Millennium Mission (GMM) including another close Io flyby in orbit I27, a fully successful encounter. Three additional Io flybys are anticipated in August 2001 (I31), October 2001 (I32), and January 2002 (I33). The groundtracks for all six Io encounters are shown in Plate 1.
Study of seismic site effects using H/V spectral ratios at Arenal Volcano, Costa Rica
Authors: Mora Mauricio M. , Lesage Philippe , Dorel Jacques , Bard Pierre‐Yves , Métaxian Jean‐Philippe , Alvarado Guillermo E. , Leandro Carlos
Published: April 2004

By using data obtained with a linear array at Arenal volcano, we show that the H/V spectral ratio method can be profitably applied to detect site effects on volcanoes. Similar results are obtained when calculating spectral ratios with different types of seismo‐volcanic signals (tremor, ambient noise, explosion quakes, LP events). We compare the H/V ratios with theoretical S‐wave transfer functions calculated using velocity models obtained from seismic refraction studies. There is a good agreement when the H/V ratios display sharp peaks, indicating a close relationship between the ratios and the transfer function of the shallow structure. Furthermore, the main peaks of the spectral ratios are consistent with local amplification of seismic waves observed at the corresponding frequencies.
The Okhotsk‐Pacific seawater exchange in the viewpoint of vertical profiles of radiocarbon around the Bussol' Strait
Authors: Aramaki Takafumi , Watanabe Shuichi , Kuji Tomoyuki , Wakatsuchi Masaaki
Published: April 2004

Vertical profiles for Δ14C values were described around the Bussol' Strait for the first time. The abnormality of Δ14C values at 0–400 m depth in the Bussol' Strait was observed, and expected that diapycnal mixing occurs between the sub‐surface water around the Bussol' Strait and the surface water in the Bussol' Strait. The Okhotsk‐Pacific cross‐sections through the Bussol' Strait of Δ14C and σϑ suggested the intermediate water in the Sea of Okhotsk (26.8–27.3 σϑ) has the role of the Okhotsk‐Pacific water exchange, and the deep water (>27.3 σϑ) between the Sea of Okhotsk and the Pacific Ocean is mixed well rapidly through the Bussol' Strait. Using estimation of bomb produced 14C inventories in each water column, it was suggested the quantities of the Okhotsk‐Pacific water exchange may be essentially small.
Four years of continuous surface aerosol measurements from the Department of Energy's Atmospheric Radiation Measurement Program Southern Great Plains Cloud and Radiation Testbed site
Authors: Sheridan P. J. , Delene D. J. , Ogren J. A.
Published: April 2004

Continuous measurements of the optical and microphysical properties of aerosol particles have been made at the Department of Energy's Atmospheric Radiation Measurement Program Southern Great Plains Cloud and Radiation Testbed (CART) site covering the 4‐year period from July 1996 through June 2000. Hourly, daily, and monthly statistics have been calculated that illustrate aerosol variability over a range of timescales. A pronounced peak in total particle number, centered on the midafternoon hours (local time), is evident in the hourly statistics. A broad early morning peak in the concentration of particles >0.1‐μm aerodynamic diameter corresponds with a similar peak in aerosol light‐scattering coefficient, σsp. No strong cycles were observed in the daily statistics, suggesting that day of the week has only a minor influence on the observed aerosol variability. The σsp at a wavelength of 550 nm for the 4‐year period showed a median value of 33 Mm−1 and was highest in February and August. The median fraction of aerosol light scattering at 550 nm due to particles <1‐μm aerodynamic diameter was 0.85 over the entire record. The median aerosol light absorption coefficient, σap, for the 4‐year period was ∼1.5 Mm−1 and was observed to be highest in late summer and autumn. The σap showed an increasing trend of nearly 0.5 Mm−1 yr, possibly due to increased agricultural field burning in the area. The occurrence of an autumn decrease in single‐scattering albedo, ω0, was observed and may be caused by regional‐scale agricultural or transportation activities or seasonal changes in atmospheric flow patterns. The median value for ω0 over the 4‐year period was 0.95, but this value has decreased ∼1–2% yr−1 presumably due to increased agricultural burning. Numerous field fires during the second half of 1999 influenced the surface aerosol at the CART site causing substantial variability of aerosol optical properties. The aerosol hygroscopic growth factor (f(RH)), corresponding to a relative humidity increase of 40–85%, showed a median value of 1.83 for 1999, although much lower values were observed during periods that were probably influenced by locally generated smoke and dust aerosols (median f(RH) = 1.55 and 1.59, respectively).
Reflection of a long‐period gravity wave observed in the nightglow over Arecibo on May 8–9, 1989?
Authors: Hickey Michael P.
Published: April 2004

During the Arecibo Initiative for Dynamics of the Atmosphere (AIDA) campaign in 1989 a characteristic of gravity wave perturbations observed in mesopause region airglow emissions was that airglow brightness fluctuations and airglow‐derived temperature fluctuations often occurred either in phase or in antiphase. This stimulated the development of a theory suggesting that such in‐phase fluctuations were most probably the result of strong reflections occurring in the mesosphere and lower thermosphere region. Recent examination of a particular wave event and application of simple WKB‐type theory has appeared to support this hypothesis. Here we use a full‐wave model and a WKB‐type model, each coupled with a chemical‐airglow fluctuation model describing O2 atmospheric and OH Meinel airglow fluctuations, to assess the strength of wave reflection and also to explicitly calculate the phase difference between the airglow brightness and the temperature fluctuations. Our results suggest that reflection is not strong for the particular wave event, and the model produces fairly large phase differences between the airglow brightness and the temperature fluctuations (∼35° and ∼134°–165° for the O2 atmospheric and OH airglow emissions, respectively). These results are not particularly sensitive to the nominal mean winds used in the simulations. There is an instance when a region of minimum refractive index occurs directly above a region in which reflection is strongest, suggesting that the two are related. However, the reflection does not appear to be strong. Our results suggest that chemical effects can account for the inferred phases of the observed airglow fluctuations and that effects associated with wave reflection appear to play a relatively minor role in the airglow fluctuations.
Strain localization in the Sea of Marmara: Propagation of the North Anatolian Fault in a now inactive pull‐apart
Authors: Rangin C. , Le Pichon X. , Demirbag E. , Imren C.
Published: April 2004

The Sea of Marmara is presently the site of pure dextral strike‐slip faulting that connects the Izmit Fault in the east to the Ganos Fault in the west along a linear strike‐slip fault that is part of the northwestern branch of the North Anatolian Fault. This active Main Marmara Fault (MMF) cuts across a succession of depocenters and highs. Analysis of a large data set that includes multichannel seismic lines, sparker and deep towed high definition seismics, shows that most of the N120°E trending normal faults framing these depocenters are now inactive as they are sealed by an average thickness of 300 m of sediments. The highs correspond to a series of NE‐SW trending anticlines and reverse faults blanketed by a thin cover of undeformed sediments. We interpret these structures as inverted former transfer faults of the now inactive Sea of Marmara pull‐apart system. Depocenters and highs are the relicts of a former pull‐apart basins and transfer faults system that accommodated the North Anatolian Fault motion within the Sea of Marmara prior to the formation of the MMF. We propose that a relatively short (a few hundreds of thousands of years) period of basin inversion accompanied the localization of strain along the present Main Marmara Fault, until it was fully formed, 200 ± 100 Kyr ago. The preexisting pull‐apart basin system accounts for about 30 km of motion along this fault system and thus probably appeared sometime in late Pliocene or early Pleistocene as a reactivated portion of the old Thrace basin. During the Plio‐Quaternary the Sea of Marmara has been the site of progressive localization of strain.