bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro-Composition
Authors: Mellor D. H.
Published: November 2010

Entities of many kinds, not just material things, have been credited with parts. Armstrong (1978: 36), for example, has taken propositions and properties to be parts of their conjunctions, sets to be parts of sets that include them, and geographical regions and events to be parts of regions and events that contain them. The justification for bringing all these diverse relations under a single ‘part–whole’ concept is that they share all or most of the formal features articulated in mereology (Simons 1987). But the concept has also prompted an ontological thesis that has been expressed in various ways: that wholes are ‘no ontological addition’ to their parts (meaning their proper parts, i.e. not counting a whole as a part of itself); that to list both a whole and its parts is ‘double counting’; and that there is ‘no more’ to a whole than its parts: for example, that there is no more to a conjunction (i.e. to its truth conditions) than the conjuncts that are its parts, and whose truth or falsity determines whether it is true or false. For brevity, I shall express the thesis in the last of these ways, as the claim that entities with parts are ‘nothing but’ those parts.
Working Parts: Reply to Mellor
Authors: Williams J. Robert G.
Published: November 2010

Whenever a material thing has parts, those parts are located where that thing is. This is a necessary truth, and needs explaining.
Truthmakers, Realism and Ontology
Authors: Cameron Ross P.
Published: November 2010

Together, these entail that for every true proposition p, there exists some thing which could not exist and p be false.
Monism and Statespace Structure
Authors: Sider Theodore
Published: November 2010

Exotic ontologies are all the rage. Distant from common sense and often science as well, views like mereological essentialism, nihilism, and four-dimensionalism appeal to our desire to avoid arbitrariness, anthropocentrism, and metaphysical conundrums.
Coincidence and Identity
Authors: Mackie Penelope
Published: November 2010

This paper is about a puzzle concerning the metaphysics of material objects: a puzzle generated by cases where material objects appear to coincide, sharing all their matter. As is well known, it can be illustrated by the example of a statue. In front of me now, sitting on my desk, is a (small) statue – a statue of a lion. The statue is made of clay. So in front of me now is a piece of clay. But what is the relation between the statue and the piece of clay? Are they identical, or are they distinct?
Nihilism without Self-Contradiction
Authors: Liggins David
Published: November 2010

Last weekend, I made a bookcase. To begin with, I went and bought various pieces of wood and several screws. Then I screwed the pieces of wood together. In doing so, I created something new: my bookcase. And this bookcase is made up of the pieces of wood and the screws. In other words, they're parts of it.
Persistence and Determination
Authors: Hawley Katherine
Published: November 2010

Roughly speaking, perdurantism is the view that ordinary objects persist through time by having temporal parts, whilst endurantism is the view that they persist by being wholly present at different times. (Speaking less roughly will be important later.) It is often thought that perdurantists have an advantage over endurantists when dealing with objects which appear to coincide temporarily: lumps, statues, cats, tail-complements, bisected brains, repaired ships, and the like. Some cases – personal fission, for example – seem to involve temporary coincidence between objects of the same kind. Other cases – a cat and its flesh, a statue and its lump – seem to involve objects of different kinds.
New indicators of 30 OECD countries' pension systems
Authors: WHITEHOUSE EDWARD
Published: November 2010

Pension systems are complex and diverse, so comparing them is consequently difficult. Yet there are valuable lessons to be learned from the pension experiences of other nations. International comparisons of pension systems have focused almost wholly on the fiscal aspects of ageing populations. This paper provides consistent data on pension entitlements for the 30 member countries of the OECD, allowing cross-country analysis of the adequacy and distribution of pension promises.

The following section provides a brief description of the 30 retirement-income regimes and compares key parameters, such as pension eligibility ages, ceilings on pensionable earnings, contribution rates to defined-contribution schemes and accrual rates for defined-benefit plans. Section 2 sets out the methodology for and assumptions used in modelling pension entitlements. Section 3 presents replacement rates, the most commonly used indicator in pension analysis. Section 4 calculates pension wealth, the present value of the flow of pension entitlements, which captures the effects of cross-country differences in life expectancy, pension eligibility ages, and indexation of pensions in payment. The concept of weighted averages is introduced in Section 5: a way of summarizing the main indicators across the range of individual earnings. The structure of the pension package, that is the role that different components of the retirement-income system play, is explored in Section 6. Section 7 presents a measure of the progressivity of the pension benefit formula, while Section 8 concludes.
Consequences for welfare and pension buffers of alternative methods of discounting future pensions
Authors: BUCCIOL ALESSANDRO , BEETSMA ROEL M. W. J.
Published: November 2010

We explore the implications of alternative methods of discounting future pension outlays for the valuation of funded pension liabilities. Measured liabilities affect the asset–liability ratio of pension funds and, thereby, their policies. Our framework for analysis is an applied many-generation OLG model describing a small open economy with heterogeneous agents and a two-pillar pension system (with pay-as-you-go and funded tiers) calibrated to that in the Netherlands. We compare mark-to-market discounting against various alternatives, such as discounting against a moving average of past market curves or a curve that is constant over time. The pension buffer is stabilized by adjusting indexation and contribution rates in response to demographic, economic and financial shocks in the economy. Mark-to-market valuation of liabilities produces substantially higher volatility in the pension buffers, but it also generates slightly higher aggregate welfare.
Slip distribution of the 2003 Tokachi‐oki Mw 8.1 earthquake from joint inversion of tsunami waveforms and geodetic data
Authors: Romano F. , Piatanesi A. , Lorito S. , Hirata K.
Published: November 2010

We study the 2003 Mw 8.1 Tokachi‐oki earthquake, a great interplate event that occurred along the southwestern Kuril Trench and generated a significant tsunami. To determine the earthquake slip distribution, we perform the first joint inversion of tsunami waveforms measured by tide gauges and of coseismic displacement measured both by GPS stations and three ocean bottom pressure gauges (PG) for this event. The resolution of the different data sets on the slip distribution is assessed by means of several checkerboard tests. Results show that tsunami data constrain the slip distribution offshore, whereas GPS data constrain the slip distribution in the onshore zone. The three PG data only coarsely constrain the offshore slip, indicating that denser networks should be installed close to subduction zones. Combining the three data sets significantly improves the inversion results. Joint inversion of the 2003 Tokachi‐oki earthquake data leads to maximum slip values (∼6 m) confined at depths greater than ∼25 km, between 30 and 80 km northwest of the hypocenter, with a patch of slip (3 m) in the deepest part of the source (∼50 km depth). Slip values are very low (≤1 m) updip from the hypocenter. Furthermore, the rupture does not extend on the plate interface off Akkeshi. As a significant back slip amount (∼4 m) has accumulated there since the last 1952 earthquake, this segment could rupture during the next large interplate event along the Kuril Trench.
Role of seepage forces on seismicity triggering
Authors: Rozhko Alexander Y.
Published: November 2010

Borehole fluid injection is commonly used for geological sequestration of carbon dioxide, underground storage of natural gas, waste injections, and during stimulations and development of geothermal and hydrocarbon reservoirs. Typically, the injection process induces significant seismicity, with some earthquakes as large as magnitude four. Induced seismicity has also been observed around producing hydrocarbon boreholes. Recently, it has been argued that some induced seismicity data can be explained by a highly nonlinear fluid diffusion mechanism or by the propagation of fluid pressure pulses. The nature of the nonlinearity and the mechanisms by which a pressure pulse can trigger seismicity are still uncertain. In this paper I show that the same spatiotemporal variation of seismicity can be explained and predicted by linear diffusion coupled to deformation of a linear poroelastic medium. By calculating the propagation of Coulomb Yielding Stress (CYS) perturbation with time, it is demonstrated that seismicity can be triggered by this perturbation. The change of CYS along the diffusion front is caused by seepage forces, which are body forces generated by fluid pressure gradients, and can explain induced seismicity during borehole fluid injection and extraction. Using published experimental data, I demonstrate how the spatiotemporal distribution of fluid‐induced seismic events can be used for reservoir modeling and characterization.
Calcium carbonate saturation states in the waters of the Canadian Arctic Archipelago and the Labrador Sea
Authors: Azetsu‐Scott Kumiko , Clarke Allyn , Falkner Kelly , Hamilton James , Jones E. Peter , Lee Craig , Petrie Brian , Prinsenberg Simon , Starr Michel , Yeats Philip
Published: November 2010

Ocean acidification is predicted to occur first in polar oceans. We investigated the saturation state of waters with respect to calcite (Ωcal) and aragonite (Ωarg) in six sections along an Arctic outflow pathway through the Canadian Arctic Archipelago (CAA) and into the northwestern Atlantic using dissolved inorganic carbon and total alkalinity measurements from 2003 to 2005. The study area, a key region connecting the Arctic and the North Atlantic, includes Smith Sound, Barrow Strait, Baffin Bay, Davis Strait, Hudson Strait, and the Labrador Sea. The average Ωarg in the Arctic outflow was 1.18 ± 0.17 in Barrow Strait and 1.31 ± 0.14 in Smith Sound, with areas where Ωarg < 1. The Arctic outflow through the CAA has a high content of Pacific waters, which have a low saturation state. These waters can be traced along the western Baffin Bay to Davis Strait. South of Davis Strait, this outflow is modified by mixing with slope and offshore waters of Atlantic origin and with the outflow from Hudson Strait. Despite the mixing, low saturation state water can still be identified on the southern Labrador Shelf. The aragonite saturation horizon is found at ∼150 m in Barrow Strait; at 200 m in Baffin Bay, Davis Strait, and Hudson Strait; and at 2300 m in the Labrador Sea. This study provides baseline data of the saturation states for the waters of the CAA and the northwest Atlantic. It also illustrates the downstream evolution of low saturation state Arctic outflow in the northwest Atlantic.
Identification, distribution and possible origins of sulfates in Capri Chasma (Mars), inferred from CRISM data
Authors: Flahaut Jessica , Quantin Cathy , Allemand Pascal , Thomas Pierre , Le Deit Laetitia
Published: November 2010

CRISM is a hyperspectral imager onboard the Mars Reconnaissance Orbiter (MRO; NASA, 2005) which has been acquiring data since November 2006 and has targeted hydrated minerals previously detected by OMEGA (Mars Express; ESA, 2003). The present study focuses on hydrated minerals detected with CRISM at high spatial resolution in the vicinity of Capri Chasma, a canyon of the Valles Marineris system. CRISM data were processed and coupled with MRO and other spacecraft data, in particular HiRiSE (High Resolution Science Experiment, MRO) images. Detections revealed sulfates in abundance in Capri, especially linked to the interior layered deposits (ILD) that lie in the central part of the chasma. Both monohydrated and polyhydrated sulfates are found at different elevations and are associated with different layers. Monohydrated sulfates are widely detected over the massive light‐toned cliffs of the ILD, whereas polyhydrated sulfates seem to form a basal and a top layer associated with lower‐albedo deposits in flatter areas. Hydrated silicates (phyllosilicates or opaline silica) have also been detected very locally on two mounds about a few hundred meters in diameter at the bottom of the ILD cliffs. We suggest some formation models of these minerals that are consistent with our observations.
A hydrologically coupled higher‐order flow‐band model of ice dynamics with a Coulomb friction sliding law
Authors: Pimentel S. , Flowers G. E. , Schoof C. G.
Published: November 2010

The influence of hydrologic transience and heterogeneity on basal motion is an often‐neglected aspect of numerical ice‐flow models. We present a flow‐band model of glacier dynamics with a Coulomb friction sliding law that is coupled to a model of the basal drainage system by means of subglacial water pressure. The ice‐flow model contains “higher‐order” stress gradients from the Stokes flow approximation originally conceived by Blatter (1995). The resulting system of nonlinear equations is solved using a modified Picard iteration that is shown to improve the rate of convergence. A parameterization of lateral shearing is included to account for the effects of three‐dimensional geometry. We find that lateral drag has a discernible effect on glacier speed even when glacier width exceeds glacier length. Variations in flow‐band width are shown to have a greater influence on flow line speed than either different valley cross‐sectional shapes or the presence or absence of glacier sliding along valley walls. Modeled profiles of subglacial water pressure depart significantly from pressures prescribed as a uniform fraction of overburden, thus producing profiles of glacier sliding that are distinctly different from those that would be described by a sliding law controlled by overburden pressures. Simulations of hydraulically driven glacier acceleration highlight the value of including a representation of basal hydrology in models aiming for improved predictive capability of glacier dynamics.
Climate signal propagation in southern California aquifers
Authors: Barco Janet , Hogue Terri S. , Girotto Manuela , Kendall Donald R. , Putti Mario
Published: November 2010

The western United States is marked by limited water resources and a fast‐growing population. Increasing climate variability as well as a growing demand on water resources highlights the need for improved understanding of connections between regional climate, surface water dynamics, and groundwater recharge. The current study focuses on the linkages between climate variability and groundwater levels in Calleguas Creek watershed located in southern California. The Calleguas Creek groundwater system serves as a critical source of water supply for agricultural and industrial use. Precipitation time series and groundwater levels were analyzed throughout the Calleguas Creek watershed for the period 1975–2004. Water level variability was analyzed for over 311 individual wells with a subset of 20 wells selected for further analysis. A correlation matrix was computed to establish well locations (or groups) with similar hydrologic behavior. Prewhitening methods were used to evaluate the effect of time series autocorrelation on the test statistics for trend detection using the Mann‐Kendall test. Both climate and selected groundwater level (well) data were subjected to frequency analysis using fast Fourier transform. The time series of precipitation, the El Niño–Southern Oscillation (ENSO) index, and well levels were analyzed. A strong persistence was observed in the groundwater level time series, ranging from 66% to 99%. Results suggest the existence of significant periodicities between 2.0 and 7.0 years in both the precipitation and the well level data that are partially coincident with ENSO modes. A decadal oscillation was also observed in the well level data, which partially corresponds with the Pacific Decadal Oscillation. Assessment of the complex interactions between climate variability and groundwater levels will facilitate improved water resources planning and management in water‐stressed regions where marginal changes in hydrologic budgets have significant implications.
Self‐regulated fluctuations in the ablation of a snow patch over four decades
Authors: Fujita Koji , Hiyama Kuniharu , Iida Hajime , Ageta Yutaka
Published: November 2010

We describe four decades of temporal fluctuations in the ablation of the Hamaguri‐yuki snow patch in the northern Japan Alps. Annual ablation depth through the melting season shows a significant correlation with the initial depth (at the beginning of the melting season), whereas a less significant correlation is found with a temperature index that is generally believed to correlate well with ablation. The scale effect of the snow patch, which appears to modify the wind speed over the patch, has a more significant effect on snow ablation than does the radiation shadowing effect of surrounding mountains. In the case of a thinner and therefore smaller initial springtime snow patch, the speed of the local wind may be reduced over the snow surface, thereby suppressing ablation, whereas wind speed is not reduced (and ablation is not suppressed) in the case of a thicker snow patch. This self‐regulating feedback means that over the past four decades, the thickness of the snow patch has fluctuated in a manner that is largely independent of summertime temperature. Our findings also suggest that the self‐regulating feedback, which influences ablation, allows some small wind‐drifted glaciers to survive, whereas previous studies reported enhanced accumulation at such glaciers via a similar topographic effect on wind speed and suppressed ablation via the shading effect of surrounding mountains on solar radiation.
In lieu of the paired catchment approach: Hydrologic model change detection at the catchment scale
Authors: Zégre Nicolas , Skaugset Arne E. , Som Nicholas A. , McDonnell Jeffrey J. , Ganio Lisa M.
Published: November 2010

The paired catchment approach has been the predominant method for detecting the effects of disturbance on catchment‐scale hydrology. Notwithstanding, the utility of this approach is limited by regression model sample size, variability between paired catchments, type II error, and the inability of locating a long‐term suitable control. An increasingly common practice is to use rainfall‐runoff models to discern the effect of disturbance on hydrology, but few hydrologic model studies (1) consider problems associated with model identification, (2) use formal statistical methods to evaluate the significance of hydrologic change relative to variations in rainfall and streamflow, and (3) apply change detection models to undisturbed catchments to test the approach. We present an alternative method to the paired catchment approach and improve on stand‐alone hydrologic modeling to discern the effects of forest harvesting at the catchment scale. Our method combines rainfall‐runoff modeling to account for natural fluctuations in daily streamflow, uncertainty analyses using the generalized likelihood uncertainty estimation method to identify and separate hydrologic model uncertainty from unexplained variation, and GLS regression change detection models to provide a formal experimental framework for detecting changes in daily streamflow relative to variations in daily hydrologic and climatic data. We include statistical analyses of climate variation and a two‐part evaluation to explore model performance and account for unexplained variation. Evaluations consisted of applying our method to a control catchment and to a period prior to harvesting in a treated catchment to demonstrate that our method was capable of capturing the absence of land use change in an undisturbed catchment and capturing the absence of land use change during a period of no disturbance in the harvested catchment. In addition, we explore the sensitivity of our method to model identification, number of simulations, and likelihood thresholds for model identification. We show that an increase in the number of model simulations does not necessarily result in increased change detection performance. Our method is a potentially useful alternative to the paired catchment approach where reference catchments are not possible and to stand‐alone hydrologic modeling for detecting the effects of land use change on hydrology.
Stochastic estimation of aquifer geometry using seismic refraction data with borehole depth constraints
Authors: Chen Jinsong , Hubbard Susan S. , Gaines David , Korneev Valeri , Baker Gregory , Watson David
Published: November 2010

We develop a Bayesian model to invert surface seismic refraction data with depth constraints from boreholes for characterization of aquifer geometry and apply it to seismic and borehole data sets collected at the contaminated Oak Ridge National Laboratory site in Tennessee. Rather than the traditional approach of first inverting the seismic arrival times for seismic velocity and then using that information to aid in the spatial interpolation of wellbore data, we jointly invert seismic first arrival time data and wellbore‐based information, such as depths of key lithological boundaries. We use a staggered‐grid finite difference algorithm with second‐order accuracy in time and fourth‐order accuracy in space to model seismic full waveforms and use an automated method to pick the first arrival times. We use Markov Chain Monte Carlo methods to draw many samples from the joint posterior probability distribution, on which we can estimate the key interfaces and their associated uncertainty as a function of horizontal location and depth. We test the developed method on both synthetic and field case studies. The synthetic studies show that the developed method is effective at rigorous incorporation of multiscale data and the Bayesian inversion reduces uncertainty in estimates of aquifer zonation. Applications of the approach to field data, including two surface seismic profiles located 620 m apart from each other, reveal the presence of a low‐velocity subsurface zone that is laterally persistent. This geophysically defined feature is aligned with the plume axis, suggesting it may serve as an important regional preferential flow pathway.
Environmental, political, and economic determinants of water quality monitoring in Europe
Authors: Beck Lucas , Bernauer Thomas , Kalbhenn Anna
Published: November 2010

Effective monitoring is essential for effective pollution control in national and international water systems. To what extent are countries' monitoring choices driven by environmental criteria, as they should be? And to what extent are they also influenced by other factors, such as political and economic conditions? To address these questions, we describe and explain the evolution of one of the most important international environmental monitoring networks in Europe, the one for water quality, in the time period 1965–2004. We develop a geographic information system that contains information on the location of several thousand active monitoring stations in Europe. Using multivariate statistics, we then examine whether and to what extent the spatial and temporal clustering of monitoring intensity is driven by environmental, political, and economic factors. The results show that monitoring intensity is higher in river basins exposed to greater environmental pressure. However, political and economic factors also play a strong role in monitoring decisions: democracy, income, and peer pressure are conducive to monitoring intensity, and monitoring intensity generally increases over time. Moreover, even though monitoring is more intense in international upstream‐downstream settings, we observe only a weak bias toward more monitoring downstream of international borders. In contrast, negative effects of European Union (EU) membership and runup to the EU's Water Framework Directive are potential reasons for concern. Our results strongly suggest that international coordination and standardization of water quality monitoring should be intensified. It will be interesting to apply our analytical approach also to other national and international monitoring networks, for instance, the U.S. National Water‐Quality Assessment Program or the European Monitoring and Evaluation Program for air pollution.
Low‐productivity Hawaiian volcanism between Kaua‘i and O‘ahu
Authors: Greene Andrew R. , Garcia Michael O. , Weis Dominique , Ito Garrett , Kuga Maia , Robinson Joel , Yamasaki Seiko
Published: November 2010

The longest distance between subaerial shield volcanoes in the Hawaiian Islands is between the islands of Kaua‘i and O‘ahu, where a field of submarine volcanic cones formed astride the axis of the Hawaiian chain during a period of low magma productivity. The submarine volcanoes lie ∼25–30 km west of Ka‘ena Ridge that extends ∼80 km from western O‘ahu. These volcanoes were sampled by three Jason2 dives. The cones are flat topped, <400 m high and 0.4–2 km in diameter at water depths between ∼2700 and 4300 m, and consist predominantly of pillowed flows. Ar‐Ar and K‐Ar ages of 11 tholeiitic lavas are between 4.9 and 3.6 Ma. These ages overlap with shield volcanism on Kaua‘i (5.1–4.0 Ma) and Wai‘anae shield basalts (3.9–3.1 Ma) on O‘ahu. Young alkalic lavas (circa 0.37 Ma) sampled southwest of Ka‘ena Ridge are a form of offshore secondary volcanism. Half of the volcanic cones contain high‐SiO2 basalts (51.0–53.5 wt % SiO2). The trends of isotopic compositions of West Ka‘ena tholeiitic lavas diverge from the main Ko‘olau‐Kea shield binary mixing trend in isotope diagrams and extend to lower 208Pb/204Pb and 206Pb/204Pb than any Hawaiian tholeiitic lava. West Ka‘ena tholeiitic lavas have geochemical and isotopic characteristics similar to volcanoes of the Loa trend. Hence, our results show that the Loa‐type volcanism has persisted for at least 4.9 Myr, beginning prior to the development of the dual, subparallel chain of volcanoes. Several West Ka‘ena samples are similar to higher SiO2, Loa trend lavas of Ko‘olau Makapu‘u stage, Lāna‘i, and Kaho‘olawe; these lavas may have been derived from a pyroxenite source in the mantle. The high Ni contents of olivines in West Ka‘ena lavas also indicate contribution from pyroxenite‐derived melting. Average compositions of Hawaiian shield volcanoes show a clear relation between 206Pb/204Pb and SiO2 within Loa trend volcanoes, which supports a prominent but variable influence of pyroxenite in the Hawaiian plume source. In addition, both Pb isotopes and volcano volume show a steady increase with time starting from a minimum west of Ka‘ena Ridge. The entrained mafic component in the Hawaiian plume is probably not controlling the increasing magma productivity in the Hawaiian Islands.
Slab stress and strain rate as constraints on global mantle flow
Authors: Alisic Laura , Gurnis Michael , Stadler Georg , Burstedde Carsten , Wilcox Lucas C. , Ghattas Omar
Published: November 2010

Dynamically consistent global models of mantle convection with plates are developed that are consistent with detailed constraints on the state of stress and strain rate from deep focus earthquakes. Models that best fit plateness criteria and plate motion data have strong slabs that have high stresses. The regions containing the MW 8.3 Bolivia and MW 7.6 Tonga 1994 events are considered in detail. Modeled stress orientations match stress patterns from earthquake focal mechanisms. A yield stress of at least 100 MPa is required to fit plate motions and matches the minimum stress requirement obtained from the stress drop for the Bolivia 1994 deep focus event. The minimum strain rate determined from seismic moment release in the Tonga slab provides an upper limit of ∼200 MPa on the strength in the slab.
A strong high altitude narrow jet detected at Saturn's equator
Authors: García‐Melendo E. , Sánchez‐Lavega A. , Legarreta J. , Perez‐Hoyos S. , Hueso R.
Published: November 2010

Here we report the discovery at the upper cloud level of an extremely narrow and strong prograde jet, centered in the middle of the broad equatorial jet. Measurements from images obtained by the Cassini Imaging Science Subsystem (ISS) show that the jet reaches 430 ms−1 ± 16 m s−1 with a peak speed difference of 180 ms−1 relative to nearby latitudes at 60 mbar and 390 ms−1 ± 23 m s−1 at depths > 500 mbar spanning ∼6° about the equator . Contrarily to what is observed in other latitudes, its velocity increases with altitude. This jet is the first of its kind to be discovered on any of the giant planets, and adds to our three‐dimensional understanding of Saturn's stratospheric wind field.
Observations of very‐low‐energy (<10 eV) ion outflows dominated by O+ ions in the region of enhanced electron density in the polar cap magnetosphere during geomagnetic storms
Authors: Kitamura N. , Nishimura Y. , Ono T. , Ebihara Y. , Terada N. , Shinbori A. , Kumamoto A. , Abe T. , Yamada M. , Watanabe S. , Matsuoka A. , Yau A. W.
Published: November 2010

Velocity distributions of upflowing ions in the polar ionosphere are crucial to understand their destinations. Natural plasma wave observations by the plasma wave and sounder experiments and thermal ion observations by the suprathermal ion mass spectrometer onboard the Akebono satellite at ∼9000 km altitude in the polar magnetosphere during the geomagnetic storms showed that ions in the region of enhanced electron density in the polar cap were dominated by very‐low‐energy O+ ions (∼85%) with upward velocities of 4–10 km s−1, corresponding to streaming energies of 1.3–8.4 eV. The fluxes of very‐low‐energy upflowing O+ ions exceeded 1 × 109 cm−2 s−1 (mapped to 1000 km altitude) across wide regions. These signatures are consistent with high‐density plasma supplied by the cleft ion fountain mechanism. Trajectory calculations of O+ ions based on the Akebono observations as the initial condition showed the transport paths and accelerations of the O+ ions and indicated that the velocities of the very‐low‐energy upflowing O+ ions through the dayside polar cap are enough to reach the magnetosphere under strong convection. The calculations suggest the importance of the very‐low‐energy upflowing O+ ions with large fluxes in the total O+ ion supply toward the magnetosphere, especially the near‐Earth tail region and inner magnetosphere. The initially very‐low‐energy O+ ions can contribute significantly to the ring current formation during geomagnetic storms since some of the O+ ions were transported into the ring current region with typical energies of ring current ions (several tens of keV) in the trajectory calculations.
On slowly evolving Grad‐Shafranov equilibria
Authors: Sonnerup Bengt U. Ö. , Hasegawa Hiroshi
Published: November 2010

A method is developed for analyzing the slow, purely kinematic evolution of magnetohydrostatic Grad‐Shafranov equilibria, recovered by reconstruction from data taken by a single spacecraft as it traverses a quasi‐static, two‐dimensional, magnetic field/plasma structure in space, such as a flux transfer event at the magnetopause. The evolution is caused by the presence of small plasma velocities in the reconstruction plane, in which a velocity component perpendicular to the field moves and deforms the field lines. The method is developed in a general form that allows for plasma compressibility but is then specialized to a simpler version, in which the velocity field is assumed to be divergence free, at least in the vicinity of the spacecraft path through the structure. Benchmarking and application of the simpler version to Cluster data are presented in a companion paper by Hasegawa et al. (2010). Potential applications include, not only flux transfer events, but also other slowly evolving elongated structures in which dissipation can be neglected, including flux ropes and magnetic clouds in the solar wind.
Characterization of global ocean turbidity from Moderate Resolution Imaging Spectroradiometer ocean color observations
Authors: Shi Wei , Wang Menghua
Published: November 2010

Seasonal global ocean turbidity is studied and quantified using the diffuse attenuation coefficient at the wavelength of 490 nm, Kd(490), derived from measurements of the Moderate Resolution Imaging Spectroradiometer onboard the Aqua satellite. The shortwave infrared‐based atmospheric correction algorithm and a newly developed Kd(490) algorithm have been used to derive Kd(490) data for both the global open ocean and coastal turbid waters. The spatial pattern of global open ocean turbidity shows significant seasonal Kd(490) variations with highs in the boreal (or austral) spring and summer and lows in the winter for the Northern Hemisphere (or Southern Hemisphere). The clear water with Kd(490) ≤ 0.1 m−1 covers an average of ∼95.67% of the global ocean. The modestly turbid waters with Kd(490) values ranging from ∼0.1 to 0.3 m−1 has about 5.12% and 3.07% of the global ocean region in the summer and winter, respectively, with average coverage of ∼3.59%. Turbid waters with Kd(490) over 0.3 m−1 are all located in the coastal regions, river estuaries, and inland lakes with an average global coverage of ∼0.74%, accounting for ∼8% to 12% of the total global continental shelf area. The world's major turbid water regions are identified and evaluated in this study. Amazon River Estuary ranks as the world's most turbid region with the mean Kd(490) value of ∼5 m−1. In addition, different mechanisms for the water turbidity in the open oceans and coastal turbid waters are investigated. In the open ocean, variability in the seasonal turbidity is related to the seasonal variation of chlorophyll a concentration, i.e., the seasonal phytoplankton bloom dominates the global geographic perspective of the water turbidity (for waters with Kd(490) ≤ 0.3 m−1). In the coastal region, on the other hand, high turbidity (Kd(490) > 0.3 m−1) is attributed to the high loading of sediment concentration due to various physical processes, such as sediment resuspension, river runoff, etc.
Aviation response to a widely dispersed volcanic ash and gas cloud from the August 2008 eruption of Kasatochi, Alaska, USA
Authors: Guffanti Marianne , Schneider David J. , Wallace Kristi L. , Hall Tony , Bensimon Dov R. , Salinas Leonard J.
Published: November 2010

The extensive volcanic cloud from Kasatochi's 2008 eruption caused widespread disruptions to aviation operations along Pacific oceanic, Canadian, and U.S. air routes. Based on aviation hazard warnings issued by the National Oceanic and Atmospheric Administration, U.S. Geological Survey, the Federal Aviation Administration, and Meteorological Service of Canada, air carriers largely avoided the volcanic cloud over a 5 day period by route modifications and flight cancellations. Comparison of time coincident GOES thermal infrared (TIR) data for ash detection with Ozone Monitoring Instrument (OMI) ultraviolet data for SO2 detection shows congruent areas of ash and gas in the volcanic cloud in the 2 days following onset of ash production. After about 2.5 days, the area of SO2 detected by OMI was more extensive than the area of ash indicated by TIR data, indicating significant ash depletion by fall out had occurred. Pilot reports of visible haze at cruise altitudes over Canada and the northern United States suggested that SO2 gas had converted to sulfate aerosols. Uncertain about the hazard potential of the aging cloud, airlines coped by flying over, under, or around the observed haze layer. Samples from a nondamaging aircraft encounter with Kasatochi's nearly 3 day old cloud contained volcanic silicate particles, confirming that some fine ash is present in predominantly gas clouds. The aircraft's exposure to ash was insufficient to cause engine damage; however, slightly damaging encounters with volcanic clouds from eruptions of Reventador in 2002 and Hekla in 2000 indicate the possibility of lingering hazards associated with old and/or diffuse volcanic clouds.
Spatial and temporal variations of aerosols around Beijing in summer 2006: 2. Local and column aerosol optical properties
Authors: Matsui H. , Koike M. , Kondo Y. , Takegawa N. , Fast J. D. , Pöschl U. , Garland R. M. , Andreae M. O. , Wiedensohler A. , Sugimoto N. , Zhu T.
Published: November 2010

Model calculations were conducted using the Weather Research and Forecasting model coupled with chemistry (WRF‐chem) for the region around Beijing, China, in the summer of 2006, when the CAREBeijing‐2006 intensive campaign was conducted. In this paper, we interpret aerosol optical properties in terms of aerosol mass concentrations and their chemical compositions by linking model calculations with measurements. The model calculations generally captured the observed variability of various surface and column aerosol optical parameters in and around Beijing. At the surface, the spatial and temporal variations of aerosol absorption and scattering coefficients corresponded well to those of elemental carbon and sulfate mass concentrations, respectively, and were controlled by local‐scale (<100 km and <24 hours) and regional‐scale (<500 km and <3 days) emissions, respectively. The contribution of secondary aerosols and their water uptake increased with altitude within the planetary boundary layer. This variation led to a considerable increase in column aerosol optical depth and was responsible for the differences in regional and temporal variations between surface and column aerosol optical properties around Beijing. These processes are expected to be common in other megacity regions as well. Model calculations, however, underestimated or overestimated the absolute levels of aerosol optical properties in and around Beijing by up to 60%. Sensitivity studies showed that these discrepancies were mostly due to the uncertainties in aerosol mixing state and aerosol density (affecting mass extinction efficiency) in the model calculations. Good agreement with measurements is achieved when these aerosol properties are accurately predicted or assumed; however, significant bias can result when these properties are inadequately treated, even if total aerosol mass concentrations are reproduced well in the model calculations.
Airborne observations of ammonia and ammonium nitrate formation over Houston, Texas
Authors: Nowak J. B. , Neuman J. A. , Bahreini R. , Brock C. A. , Middlebrook A. M. , Wollny A. G. , Holloway J. S. , Peischl J. , Ryerson T. B. , Fehsenfeld F. C.
Published: November 2010

Anthropogenic emissions of NOx (nitric oxide (NO) + nitrogen dioxide (NO2)), which in sunlight can be oxidized to form nitric acid (HNO3), can react with ammonia (NH3) to form ammonium nitrate particles. Ammonium nitrate formation was observed from the NOAA WP‐3D aircraft over Houston during the 2006 Texas Air Quality Study with fast‐response measurements of NH3, HNO3, particle composition, and particle size distribution. Typically, NH3 mixing ratios over the urban area ranged from 0.2 to 3 ppbv and were predominantly from area sources. No NH3 enhancements were observed in emission plumes from power plants. The few plumes with high NH3 levels from point source emissions that were sampled are analyzed in detail. While the paucity of NH3 data in emission inventories made point source identification difficult, one plume was traced to NH3 release from an industrial accident. NH3 mixing ratios in these plumes ranged from 5 to 80 ppbv. In these plumes, the NH3 enhancement correlated with a decrease in HNO3 mixing ratio and an increase in particulate NO3− concentration indicating ammonium nitrate formation. The ammonium nitrate aerosol mass budget in the plumes was analyzed to assess the quantitative agreement between the gas and aerosol phase measurements. The thermodynamic equilibrium between the gas and aerosol phase was examined for one flight by comparing the modeled dissociation constant for ammonium nitrate with NH3 and HNO3 measurements. The high levels of NH3 in these plumes shifted the equilibrium toward favorable thermodynamic conditions for the condensation of ammonium nitrate onto particles.
Study of Schumann resonances based on magnetotelluric records from the western Mediterranean and Antarctica
Authors: Toledo‐Redondo S. , Salinas A. , Portí J. , Morente J. A. , Fornieles J. , Méndez A. , Galindo‐Zaldívar J. , Pedrera A. , Ruiz‐Constán A. , Anahnah F.
Published: November 2010

Eight independent magnetotelluric (MT) campaigns, carried out in the western Mediterranean area and Antarctica, have been analyzed with the aim of extracting information from Schumann resonances (SR). The advantages and drawbacks of MT data with respect to single‐purpose fixed stations for SR research are evaluated. Two different methods of signal processing have been employed: spectral analysis through the fast Fourier transform (FFT) and Rescaled Range analysis (R/S), calculating the Hurst exponents. The first permitted a study of the source contributions, the effects caused by local changes in the observation area, interseasonal behavior, and the relations between electric and magnetic horizontal fields. The average central frequencies obtained for the first three resonances are 7.8, 14, and 20.5 Hz respectively, but there are fluctuations in them. These variations seem to respond to the characteristics of the principal active storms that generate the resonances. These frequency shifts are stronger for the second and third resonances. Owing to the broadband registering of MT, the second method of signal processing could be applied to the low noise signals from Antarctica with high resolution, revealing the persistent nature of SR. A numerical simulation indicates a way for inferring lightning rates from R/S analysis.
Optimal management of a Hawaiian Coastal aquifer with nearshore marine ecological interactions
Authors: Duarte Thomas Kaeo , Pongkijvorasin Sittidaj , Roumasset James , Amato Daniel , Burnett Kimberly
Published: November 2010

We optimize groundwater management in the presence of marine consequences of submarine groundwater discharge (SGD). Concern for marine biota increases the optimal steady‐state head level of the aquifer. The model is discussed in general terms for any coastal groundwater resource where SGD has a positive impact on valuable nearshore resources. Our application focuses on the Kona Coast of Hawai‘i, where SGD is being actively studied and where both nearshore ecology and groundwater resources are serious sociopolitical issues. To incorporate the consequences of water extraction on nearshore resources, we impose a safe minimum standard for the quantity of SGD. Efficient pumping rates fluctuate according to various growth requirements on the keystone marine algae and different assumptions regarding recharge rates. Desalination is required under average recharge conditions and a strict minimum standard and under low recharge conditions regardless of minimum standards of growth.
Daily streamflow analysis based on a two‐scaled gamma pulse model
Authors: Muneepeerakul Rachata , Azaele Sandro , Botter Gianluca , Rinaldo Andrea , Rodriguez‐Iturbe Ignacio
Published: November 2010

In this paper, we develop a simple analysis method to infer some properties of the watershed processes from daily streamflow data. The method is built on a simple streamflow model with a link to rainfall stochasticity, which characterizes the streamflow as a series of overlapping gamma distribution‐shaped pulses. The key premise of the method is that the complex streamflow processes can be effectively captured by simply dividing streamflow into two regimes. Specifically in this method, the gamma pulse model is applied separately to low‐ and high‐flow regimes. We demonstrate the application of the method to five watersheds and show that it is capable of capturing at least two important statistical properties of streamflow, namely the probability density function and the autocorrelation function for wide ranges of values (i.e., from low to large flows and time lags, respectively).
A note on the visualization of wetting film structures and a nonwetting immiscible fluid in a pore network micromodel using a solvatochromic dye
Authors: Grate Jay W. , Zhang Changyong , Wietsma Thomas W. , Warner Marvin G. , Anheier Norman C. , Bernacki Bruce E. , Orr Galya , Oostrom Mart
Published: November 2010

Micromodel technologies are a useful and important method to study pore‐scale fluidic processes, using two‐dimensional formats that enable direct visualization of processes within patterned microstructures. In this technical note, Nile red, 9‐diethylamino‐5H‐benzo[alpha]phenoxazine‐5‐one, is demonstrated as a single dye whose solvatochromism enables selective visualization of two immiscible liquid fluids in a pore network micromodel containing a homogeneous array of pillars. Nile red dissolves in, and partitions between, hexadecane as a nonwetting fluid and polyethylene glycol 200 (PEG200) as a hydrophilic wetting fluid in a micromodel with silicon oxide surfaces. Both the absorption spectra and fluorescence emission spectra are sensitive to the solvent environment, such that the two phases can be distinguished by the observed color or the fluorescence emission band. Bright field, epifluorescence, confocal fluorescence, and hyperspectral microscopy methods were used to image the micromodel after displacing PEG200 in the model with hexadecane. Using a single solvatochromic dye facilitates direct visualization and identification of both phases anywhere in the micromodel on the basis of color and also enables collection of complementary fluorescent images for each phase. The use of Nile red with these imaging methods facilitates selective visualization of phase identity at specific locations; the interfaces between the two immiscible liquid phases; wetting behavior of the wetting phase within the pore network; and retention of the wetting phase as thin films around pillars and as bridges across the pore throats. The pillars and wetting phase bridges create a network of obstacles defining a tortuous flow path for the displacing nonwetting phase.
Changes in wood and foliar δ13C in sugar maple at Gatineau Park, Quebec, Canada
Authors: Watmough Shaun A. , Mcneely Roger , Lafleur Peter M.
Published: November 2010

Leaf samples and tree rings formed between the mid‐1960s and mid‐1990s from sugar maple (Acer saccharum Marsh.) at Gatineau Park (45°30′ N, 75°54′ W), Quebec were analysed for δ13C. Leaf samples were collected at ground level (1–2 m above ground) at monthly intervals during the summer, whereas tree cores were extracted from the largest trees (d.b.h. > 30 cm) in the young deciduous forest in August 1998. Significant linear decreases in δ13C over time were found in foliage and tree rings, but the decrease in δ13C was significantly greater in foliage than in the wood. The apparent isotopic discrimination (Δ) of tree rings varied insignificantly around a mean of 18‰, whereas foliar Δ increased significantly from 19‰ in the 1960s to around 23‰ by the mid 1990s, likely as a result of an increasing canopy effect as the forest matured. Using models of carbon discrimination and Δ‐values of the tree rings, we calculate that the intrinsic water use efficiency of mature sugar maple has increased by approximately 4% over the study period.
INITIATION AND GROWTH OF SMALL CRACKS IN DIRECTIONALLY SOLIDIFIED MAR‐M247 UNDER CREEP‐FATIGUE. PART I: EFFECT OF MICROSTRUCTURE
Authors: Okada M , Tsutsumi M , Kitamura T , Ohtani R
Published: November 2010

This paper deals with the initiation and growth of small cracks in a directionally solidified superalloy, Mar‐M247.