bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overview: The stratospheric photochemistry aerosols and dynamics expedition (SPADE) and Airborne Arctic Stratospheric Expedition II (AASE‐II)
Authors: Wofsy S. C. , Cohen R. C. , Schmeltekopf A. L. 
Published: February 2004

The Stratospheric Photochemistry, Aerosols, and Dynamics Expedition (SPADE) made in situ observations of the composition of the lower stratosphere from the NASA ER‐2 aircraft at latitudes from 15°N to 60°N, during November 1992 and April, May and October 1993. SPADE followed the Airborne Arctic Stratospheric Expedition II (AASE‐II, September 1991 to March 1992) by 8 months. Together the two missions provide a record of stratospheric trace species and aerosols at middle and high latitudes spanning the input and decay of debris from the eruption of Mt. Pinatubo. New instruments deployed for SPADE include sensors to measure OH, HO2, H2O, CO2, NO2 and the UV/visible radiation field, complementing sensors previously deployed on the ER‐2 (ClO, BrO, NO, NOy, N2O, O3, H2O, HCl, CH4, CFC‐11, CFC‐113, and aerosol number and size distribution). The data provide the first simultaneous in situ measurements of radicals and reservoir species to include representatives from all the important families of stratospheric reactants, observed as functions of time of day (at ∼18 km), latitude and altitude (15–20 km). The results place strong new constraints on models of stratospheric photochemistry. For example, measurements of the radicals HO2, NO2, ClO and BrO allow for a nearly completely empirical evaluation of local rates for photochemical removal of ozone (by known catalytic cycles).Highly precise observations of the seasonal cycle and interannual changes in CO2, combined with data for N2O and other tracer species, provide new insights into rates for transport in the lower stratosphere. High resolution data obtained during SPADE by the ER‐2 (in its own wake) and in AASE‐II by the DC‐8 (in wakes from commercial aircraft) provide support for engineering models of NOx emissions from subsonic jet aircraft at cruise conditions. Observations from the DC‐8 during AASE‐II, defining global distributions of NOx and NOy near the tropopause, and of HF, HCl, ClNO3, and HNO3 column abundances, provide new information on the processes influencing polar ozone loss.
Sediment transport in oscillatory boundary layers in cases of rippled beds and sheet flow
Authors: Ribberink Jan S. , Al‐Salem Abdullah A. 
Published: February 2004

An experimental study was focused on the process of sediment transport in unsteady flow conditions due to wave action. Wave‐induced oscillatory flow conditions near the seabed were simulated at full scale (1:1) in a new large oscillating water tunnel. Two sets of experiments (series A and B) were carried out. During series A, bed forms and wave‐cycle averaged suspended sediment concentrations were measured under sinusoidal waves. Series B focused on measurement of the wave‐cycle averaged sediment transport rates under regular and random asymmetric oscillatory flows (upper shoreface conditions) and was aimed at the verification of quasi‐steady formulas for the description of cross‐shore sediment transport.Bedform dimensions appeared to decrease considerably under the influence of wave asymmetry and wave randomness. Only the measured ripple dimensions under asymmetric waves (series B) showed good agreement with Nielsen's (1979) relations. For most of the series B experiments the bed was plane (sheet flow), the net sediment transport was directed “onshore” and the measured transport rates showed a strong correlation with the velocity moment < U3 >. An empirical quasi‐steady transport model is proposed which is based on the new tunnel data and other existing data sets. The limitations of the quasi‐steady model approach became clear in the rippled‐bed regime and through the presence of a consistent influence of the wave period in plane‐bed conditions. In rippled‐bed conditions the suspended concentration profiles followed a negative exponential distribution. For most of the experiments the measured concentration decay length showed a linear relation with the ripple height. In plane‐bed/sheet flow conditions the measured suspended concentration profiles followed a negative power function. The power or concentration decay parameter was constant (α ≃ 2.1) for a wide range of velocity conditions. It is suggested that the mobile bed (sheet flow layer) has a strong damping effect on the mixing of suspended sediments (turbulence damping).
Data and analysis note: A new type of article for Water Resources Research
Authors: Hornberger George M. 
Published: February 2004

Water Resources Research (WRR) is pleased to announce a new type of article, the data and analysis note, which will fill a gap in current AGU publications. The purpose of this new type of manuscript is to describe data sets, analysis procedures, and algorithms that are of interest and significance to a segment of the profession but are too specialized and extensive to publish in toto in WRR.The casual network that historically has permitted data to be shared on an informal basis among investigators in a particular subdiscipline of water resources is no longer a sufficient method of distributing data. The many investigators spread around the world, the large quantity of scientific data, the costs of maintaining and increasing the quality of the data, and the increasing use of a variety of data by nonspecialists have made it increasingly difficult to share data adequately on an informal basis. A wide variety of international, national, and program‐oriented data centers have been organized over the past quarter century to archive data. Nonetheless, important data sets are often unknown or inaccessible to many potential users. Furthermore, many scientists expend considerable effort and resources to obtain and reduce data to usable form, but for a variety of reasons do not bring these data to a stage where the scientific results merit journal publication. Thus the scientist receives little or no recognition for producing a widely used data set. Similarly, geoscientists who develop well‐documented algorithms, analysis procedures, and instrumentation often receive limited recognition for their efforts. The products resulting from the diligent efforts of these scientists may not be widely known and disseminated. To alleviate the problems outlined above, WRR is instituting a new type of manuscript called the “data and analysis note.”
Galileo infrared observations of the Shoemaker‐Levy 9 G Impact Fireball: A Preliminary report
Authors: Carlson R. W. , Weissman P. R. , Segura M. , Hui J. , Smythe W. D. , Johnson T. V. , Baines K. H. , Drossart P. , Encrenaz Th. , Leader F. E. 
Published: February 2004

The Galileo spacecraft was fortuitously situated for a direct view of the impacts of the fragments of comet Shoemaker‐Levy 9 in Jupiter's atmosphere. The Galileo Near Infrared Mapping Spectrometer (NIMS) instrument observed several of the impact events in several discrete bands and with a temporal resolution of roughly five seconds. Data have been received for the G impact showing two phases of strong infrared emission. The first phase is approximately one minute in duration and corresponds to the initial fireball and early plume development. This is followed six minutes later by the onset of heating by plume ejecta falling back on the upper atmosphere. This report provides a preliminary description of the fireball phase. The first detection of the G fireball occurred at 07:33:37 UT on July 18, 1994, approximately five seconds after the initial signal recorded by the Galileo Photopolarimeter‐Radiometer (PPR) instrument. The preceding NIMS measurement, occurring approximately one second before the initial PPR signal, showed no evidence of fireball emission. The detected duration of the fireball at 4.38 µm was 70 seconds. Spectra in the first half of this period show blackbody‐like emission, with absorption features from overlying methane and molecular hydrogen. The strengths of these features place the fireball in the upper troposphere and lower stratosphere, above the ammonia cloud layer. The emitting surface rises and accelerates, achieving a velocity of 2–3 km/sec after 25 seconds, in qualitative agreement with that expected for an explosion in an inhomogeneous atmosphere.The Galileo spacecraft, en route to Jupiter, was in a position to obtain a direct view of the impacts of Comet Shoemaker‐Levy 9 fragments on the nightside of Jupiter, providing an opportunity to investigate the early temporal evolution of the impact events. It was predicted that the comet fragments would produce high temperature bolides as they entered the atmosphere and then explode, producing hot fireballs which would rise, expand, and cool (Sekanina, 1993; Zahnle and Mac Low, 1994; Chevalier and Sarazin, 1994; Ahrens et al., 1994; Boslough et al., 1994). Much of the predicted radiation occurs in the infrared region, and time‐resolved infrared spectral observations, obtained over a broad wavelength range, are ideal for studying these phenomena.
4He/³He dispersion and mantle convection
Authors: Allègre Claude J. , Moreira Manuel , Staudacher Thomas 
Published: February 2004

Histograms of the 4He/³He ratios analysed in MORB glasses from individual ridge segments show a linar correlation between the ridge spreading rate and the standard deviation of the corresponding averaged 4He/³He ratio. We interpret the form of these histograms in terms of stirring time (τstir) of the upper mantle. This stirring time corresponds to the time that perturbations brought in from outside into the upper mantle, in the form of oceanic island source material or slabs, were attenuated by a factor of 1/e through the effect of convection.Using 4He/³He ratios of oceanic basalts, we calculate a stirring time close to 250 Ma, distinct from the residence time of ∼1 Ga. This may indicate the existence of two scale upper mantle convection, rapid convection being responsible for the homogeneisation of helium in the upper mantle, and the consequent uniformity of the 4He/³He ratio, and slower convection being responsible for mantle outgassing and plate tectonic motion.
Theoretical and experimental studies of magnetic domains
Authors: Merrill Ronald T. , Halgedahl Susan L. 
Published: February 2004

The primary purpose of this paper is to review recent contributions from North American scientists to theory and observations of magnetic domain structures in magnetic minerals common to rocks.Although rock magnetism deals with all the magnetic properties of rocks, a major goal of rock magnetists has been to understand the origins and properties of remanent magnetization (RM). A remanent magnetization is defined as the magnetization that exists in the absence of an external magnetic field. The analyses of RMs (of which there are more than 20 kinds) have led to the numerous, and well‐known, successes of paleomagnetism.
Terrestrial and planetary gravity fields
Authors: Nerem R. S. 
Published: February 2004

The determination of the gravity field, together with knowledge of the surface topography, provides one of the primary means of inferring the density structure and dynamics of planetary interiors [Phillips and Lambeck, 1980;Hager, 1985]. After removing the topographic gravity signal, the distribution of internal density anomalies caused by thermal or compositional differences can be studied. Gravity field models can also be used to study the compensation of surface topography, which can provide information on the mechanical properties and state of stress of the lithosphere.The determination of these models has been accomplished using a wide variety of different measurement types and solution techniques. The near‐Earth measurement types can be divided into satellite tracking measurements, surface gravity measurements, and satellite altimeter measurements. In both near‐Earth and interplanetary contexts, tracking data are used to measure gravitational perturbations affecting satellites, with the accuracy and spatial/temporal distribution of the data being the most important factors in the resulting field accuracy and resolution. Surface gravity data provide a more direct measurement of the gravity field, but acquiring data uniformly over the Earth has always been difficult. Satellite altimetry provides precise measurements of the marine gravity field, provided that satellite orbit errors and non‐geoidal sea surface height variations can be adequately modeled. Comprehensive gravity field solutions must incorporate these disparate data types in order to estimate mathematical parameters describing the gravity field, such as spherical harmonic coefficients. The proper combination of these data, along with the desire to acquire an accurate representation of the model errors, require that complex procedures be developed for computing these solutions.
Mineral physics of iron and of the core
Authors: Anderson Orson L. 
Published: February 2004

Mineral physics is a field of materials physics and materials chemistry confined to the study of materials pertinent to the Earth and planetary interiors. In the last two decades, emphasis has been given to research on the values of physical properties in materials appropriate to the Earth's mantle and core.Braginsky and Roberts[1995] listed the physical properties that play a key role in their analysis of convection of the Earth's core and the dynamo. These connect mineral physics to geomagnetism of the core. This review will be concerned primarily with progress made in the last four years in refining values of these properties.
Element partitioning between metallic liquid, magnesiowustite, and silicate liquid at 20 GPa and 2500°C: A secondary ion mass spectrometric study
Authors: Ohtani Eiji , Yurimoto Hisayoshi 
Published: February 2004

We determined the partition coefficients of 20 elements between metallic liquid, magnesiowustite, and silicate liquid at 20 GPa and 2500°C. The partition coefficients of V, Cr, Mn, Co, Ni, and Cu between metallic liquid and magnesiowustite are similar to those between metallic liquid and silicate liquid. The partitioning behavior of Si, P, W and Pb between metallic liquid and magnesiowustite show remarkable differences to that between metallic liquid and silicate liquid, reflecting incompatibility of these elements in magnesiowustite.Comparison of the present data with the previous ones implies that the metallic liquid‐siicate liquid partition coefficients of Co, Ni, W, and Mo decrease whereas those of Cr, and Mn increase due to the combined effect of pressure and temperature, although some other factors such as the liquid composition might play some roles on a large difference in D for Mo and W.The core and mantle concentrations for Co and Ni estimated by Allegre et al. [1995] are consistent with the metal‐silicate equilibrium at lower mantle conditions, although other models such as inhomogeneous accretion are also able to explain the core‐mantle concentrations.
Strange attractor characteristics of earthquakes in Shillong Plateau and adjoining regions
Authors: Srivastava H. N. , Bhattacharya S. N. , Sinha Ray K. C. 
Published: February 2004

Strange attractor dimensions were determined for two concentric areas of about 220 km (2°) and 440 km (4°) radii around WWSSN station at Shillong based on earthquake data during the period 1964 to 1992. Existence of deterministic chaos for both the areas was supported by the same fractal dimension of 6.1 and positive value of the largest Lyapunov exponent. The results have provided justification for delineating precursory seismicity patterns based on earthquakes up to epicentral distance of 440 km on different fault systems.Conspicuous higher value of the strange attractor dimension in Hindukush, Himalaya and northeast India than that in Koyna region in the peninsular India suggests a new criteria for distinction between interplate and intraplate earthquakes. Differences with subduction zone in Pacific vis‐à‐vis stress drop in great earthquakes (M≥8) and implications of the chaotic approach in earthquake hazard analysis have also been brought out.
The Southern Tropical Atlantic Region Experiment (STARE): Transport and Atmospheric Chemistry near the Equator‐Atlantic (TRACE A) and Southern African Fire‐Atmosphere Research Initiative (SAFARI): An introduction
Authors: Andreae Meinrat O. , Fishman Jack , Lindesay Janette 
Published: February 2004

In November 1988 some 50 atmospheric scientists met at Dookie College, a small campus in the agricultural lands of Victoria, Australia, to map out the scientific goals of the International Global Atmospheric Chemistry (IGAC) Program, which was to become one of the first operational Core Projects of the International Geosphere‐Biosphere Program (IGBP). They identified the tropical regions as one of the priority areas for future international, coordinated research in atmospheric chemistry because of the vast biological activity in the tropics, with a correspondingly large potential for biogenic emissions, and the rapidly growing human populations and resulting land use change in these regions. In view of the prominent role that biomass burning plays in the tropics as a source of atmospheric pollutants and of the important ecological functions of vegetation fires in the tropics, the scientists at Dookie created the Biomass Burning Experiment (BIBEX) with the goals of characterizing the fluxes of gases and aerosols from biomass burning to the global atmosphere and assessing the consequences of pyrogenic emissions on chemical and physical climate.The southern tropical Atlantic region, defined here as the region containing the Amazon basin, the tropical South Atlantic, and southern Africa, was the obvious first focus of research for this project. Large tropical forest and savanna fires had been known to occur here every year. In addition, observations from satellites and from the space shuttle had shown high levels of tropospheric ozone and carbon monoxide to be present over this region every year in the August‐to‐October period. Results from previous campaigns (ABLE 2A, CITE 3, DECAFE 88) also suggested a widespread impact of vegetation fires on both continents on the trace gas and aerosol content of the troposphere in this region.
Aptian‐Albian sea level history from Guyots in the western Pacific
Authors: Röhl Ursula , Ogg James G. 
Published: February 2004

Relative sea level fluctuations are an important control on patterns of sedimentation on continental margins and provide a valuable tool for regional correlations. One of the main objectives of combined Ocean Drilling Program Legs 143 and 144 was drilling the thick carbonate caps of a suite of seamounts, called guyots, scattered over the northwestern Pacific. The array of drowned Cretaceous banks includes four carbonate banks of Aptian‐Albian age. These particular carbonate banks display emergent surfaces if regional sea level falls faster than the rate of guyot subsidence, or intervals of condensed parasequences and well‐cemented peritidal crypto‐algal flats if the rate of sea level fall is slightly less than guyot subsidence. Rapid rises of sea level following these sequence boundaries are recorded as drowning of the emergent horizons or as pronounced deepening of facies. The cored lithologies and downhole geophysical and geochemical logs were used to identify depositional sequences and surfaces of exceptional shallowing or deepening. A combination of biostratigraphic datums, carbon and strontium isotope curves, relative magnitude of surfaces of emergence, relative thicknesses of depositional sequences, sea level events, and counts of upward shallowing cycles or parasequences were used to correlate sequences among the four sites. After compensating for thermal subsidence rates at each guyot, an identical pattern of major Aptian‐Albian eustatic sea level events is evident throughout this large portion of the Pacific Ocean. There are approximately 12 Aptian and 12 Albian significant sequence boundaries, of which a third were associated with major episodes of emergence. When these events are compared with Aptian‐Albian relative sea level changes observed in European shelf successions, the major sequence boundaries and transgressive surges can be easily correlated, and it appears that both regions also display the same number of minor events. Therefore we can apply the relative timing of these events from the thermal subsidence rates and parasequence counts of the Pacific banks to construct an improved scaling of the associated ammonite zones and biostratigraphic datums in the Aptian‐Albian interval.An electronic supplement of this material may be obtained on adiskette or via Anonymous FTP from KOSMOS.AGU.ORG (LOGINto AGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing APEND.Diskette may be ordered from American Geophysical Union, 2000Florida Ave., N.W., Washington, D.C. 20009, $15.00. Payment mustaccompany order.
The Soufriere Hills Eruption, Montserrat, British West Indies: Introduction to Special Section, Part 2
Authors: Young S. R. , Voight B. , Sparks R. S. J. , Rowley K. , Robertson R. E. A. , Lynch L. L. , Aspinall W. P. 
Published: February 2004

The special section on the eruption of Soufriere Hills volcano is a collection of 24 papers that summarises the early scientific work of the Montserrat Volcano Observatory. Part 1 of the special section, published in a previous issue of GRL, provided a sampling of the multidisciplinary investigations undertaken at Montserrat. The papers published in Part 1 included an overview of the eruption, investigations on seismicity, ground deformation studies, and petrology.The papers of this issue comprise Part 2 of the special section. These papers also cover a broad spectrum of topics, including various topics in seismology, petrology, pyroclastic flow models, gas chemistry, hydrothermal systems, and tsunami models. In general, papers in Part 1 may be said to be more observational‐ or data‐orientated, and those of Part 2 more model‐orientated, but indeed there is much overlap of descriptive material, data, and modelling within the individual contributions. Considered in total the collection presents a representative summary of the scientific effort carried out in Montserrat through much of 1997.
Systemic anti‐inflammatory fibrosis suppression in threatened trabeculectomy failure
Authors: Vote Brendan , Fuller J Robert , Bevin Tui H , Molteno Anthony CB 
Published: February 2004

Abstract Purpose: To provide a rationale for the use of systemic anti‐inflammatory fibrosis suppression in the postoperative management of threatened early trabeculectomy bleb failure. Methods: A review of the literature and of the authors’ own experiences was conducted. Results: The most important cause of persistent elevation of intraocular pressure after trabeculectomy is unduly marked or persistent inflammation with deposition of fibrous tissue, which prevents the formation of an adequately draining bleb. It was found that a clinically useful degree of suppression of bleb inflammation and fibrosis can be obtained with a 4−6 week course of the combined systemic administration of prednisone (10 mg t.i.d.), a non‐steroidal anti‐inflammatory agent (e.g. diclofenac 100 mg SR daily) and colchicine (0.25 mg or 0.3 mg t.i.d.), which was termed anti‐inflammatory fibrosis suppression. Topical atropine 1% t.i.d. and adrenaline 1% t.i.d. eye drops can also be considered in addition to routine postoperative topical steroids. Conclusions: Despite advances in surgical techniques and methods to control fibrosis, anti‐inflammatory fibrosis suppression is a valuable tool to have available in the post­operative period for management of trabeculectomies that threaten failure. This regime produces a diffuse bleb, which has a very low risk of late infection or bleb perforation. It is recommend that this regime be added to the list of therapies that are considered when clinical features suggestive of a failing bleb are confronted early in the post­operative course.