bluuebunny/crossref_metadata_2025 huggingface dataset:
An operational implementation of the GHER model for the Black Sea, with SST and CTD data assimilation
Authors: Vandenbulcke L. , Capet A. , Beckers J. M. , Grégoire M. , Besiktepe S.
Published: April 2010

Abstract. In this article, we describe the first operational implementation of the GHER hydrodynamic model. This happened onboard the research vessel "Alliance", in the context of the Turkish Straits System 2008 campaign, which aimed at the real-time characterization of the Marmara Sea and (south-western) Black Sea. The model performed badly at first, mainly because of poor initial conditions. Hence, as the model includes a reduced-rank extended Kalman filter assimilation scheme, after a hindcast where sea surface temperature and temperature and salinity profiles were assimilated, the model yielded realistic forecasts. Furthermore, the time required to run a one-day simulation (about 5 min of simulation, or 10 min with pre-processing and data transfers included) is very limited and thus operational use of the model is possible.
Adding nitrate and phosphate separately or together in the Central Indian Ocean: a nutrient enrichment experiment
Authors: Tang S. , Jiang L. , Wu Z. J.
Published: April 2010

Abstract. Nutrient enrichment experiments were carried out in the Central Indian Ocean during the Chinese First Around-the world Research Cruise, adding nitrate, phosphate, or a mixture of both of them to surface seawater. The concentration of nitrate, nitrite, ammonia, and phosphate were analyzed spectrophotometrically, the chlorophyll-a concentration with fluorescence analysis, and the temperature variation during the experiment recorded. Addition of nitrate resulted in rapid growth of phytoplankton concomitant with depletion of nitrate in the water samples. No apparent variation occurred in chlorophyll-a concentration when phosphate was added. Combining nitrate and phosphate proved to be best to promote phytoplankton bloom, and nitrate was depleted prior to phosphate. After nitrate was consumed, a substantial amount of phytoplankton survived on the supplied phosphate. No correlation was found between the nitrate to phosphate ratio and chlorophyll-a or phytoplankton growth rate. We also found no correlation between water temperature and chlorophyll-a or phytoplankton growth rate. We conclude that neither nitrate to phosphate ratio nor water temperature control the growth of phytoplankton.
Biofouling protection for marine environmental sensors
Authors: Delauney L. , Compère C. , Lehaitre M.
Published: April 2010

Abstract. These days, many marine autonomous environment monitoring networks are set up in the world. These systems take advantage of existing superstructures such as offshore platforms, lightships, piers, breakwaters or are placed on specially designed buoys or underwater oceanographic structures. These systems commonly use various sensors to measure parameters such as dissolved oxygen, turbidity, conductivity, pH or fluorescence. Emphasis has to be put on the long term quality of measurements, yet sensors may face very short-term biofouling effects. Biofouling can disrupt the quality of the measurements, sometimes in less than a week. Many techniques to prevent biofouling on instrumentation are listed and studied by researchers and manufacturers. Very few of them are implemented on instruments and of those very few have been tested in situ on oceanographic sensors for deployment of at least one or two months. This paper presents a review of techniques used to protect against biofouling of in situ sensors and will give a short list and description of promising techniques.
Super-ensemble techniques applied to wave forecast: performance and limitations
Authors: Lenartz F. , Beckers J.-M. , Chiggiato J. , Troupin C. , Vandenbulcke L. , Rixen M.
Published: April 2010

Abstract. Nowadays, several operational forecasts of surface gravity waves are available for a same region through different forecasting systems. However, their results may considerably diverge, and choosing one single forecasting system among them is not an easy task. A recently developed approach consists in merging different forecasts and past observations into a single multi-model prediction system, called the super-ensemble. First implemented in meteorology, the method has also already been tested with success in oceanography for determining temperature, acoustic properties or surface drift. During the DART06 campaigns organized by the NURC, four wave forecasting systems were simultaneously run in the Adriatic Sea, while significant wave height was measured at six stations and along the tracks of two remote sensors, hence offering an opportunity to evaluate the skills of the super-ensemble techniques. The improvement shown during both the learning and testing periods was essentially due to a bias reduction, though the correlation was also increased. The possibility of extrapolating locally obtained results in the whole domain of interest was assessed against satellite observations. Though definitive conclusions can not be drawn from these experiments, the results open the door for further investigations.
Rapid subduction in the deep North Western Mediterranean
Authors: Aguilar J. A. , Albert A. , Anghinolfi M. , Anton G. , Anvar S. , Ardid M. , Assis Jesus A. C. , Astraatmadja T. , Aubert J.-J. , Auer R. , Baret B. , Basa S. , Bazzotti M. , Bertin V. , Biagi S. , Bigongiari C. , Bou-Cabo M. , Bouwhuis M. C. , Brown A. , Brunner J. , Busto J. , Camarena F. , Capone A. , Carminati G. , Carr J. , Castel D. , Castorina E. , Cavasinni V. , Cecchini S. , Charvis Ph. , Chiarusi T. , Circella M. , Coniglione R. , Costantini H. , Cottini N. , Coyle P. , Curtil C. , De Bonis G. , Decowski M. P. , Dekeyser I. , Deschamps A. , Distefano C. , Donzaud C. , Dornic D. , Drouhin D. , Eberl T. , Emanuele U. , Ernenwein J.-P. , Escoffier S. , Fehr F. , Flaminio V. , Fratini K. , Fritsch U. , Fuda J.-L. , Giacomelli G. , Gómez-González J. P. , Graf K. , Guillard G. , Halladjian G. , Hallewell G. , van Haren H. , Heijboer A. J. , Hello Y. , Hernández-Rey J. J. , Hößl J. , de Jong M. , Kalantar-Nayestanaki N. , Kalekin O. , Kappes A. , Katz U. , Kooijman P. , Kopper C. , Kouchner A. , Kretschmer W. , Lahmann R. , Lamare P. , Lambard G. , Larosa G. , Laschinsky H. , Lefèvre D. , Lelaizant G. , Lim G. , Lo Presti D. , Loehner H. , Loucatos S. , Lucarelli F. , Lyons K. , Mangano S. , Marcelin M. , Margiotta A. , Martinez-Mora J. A. , Maurin G. , Mazure A. , Melissas M. , Montaruli T. , Morganti M. , Moscoso L. , Motz H. , Naumann C. , Neff M. , Ostasch R. , Palioselitis G. , Păvălaş G. E. , Payre P. , Petrovic J. , Piattelli P. , Picot-Clemente N. , Picq C. , Pillet R. , Popa V. , Pradier T. , Presani E. , Racca C. , Radu A. , Reed C. , Riccobene G. , Richardt C. , Rujoiu M. , Russo G. V. , Salesa F. , Schoeck F. , Schuller J.-P. , Shanidze R. , Simeone F. , Spurio M. , Steijger J. J. M. , Stolarczyk Th. , Tamburini C. , Tasca L. , Taupier-Letage I. , Toscano S. , Vallage B. , Van Elewyck V. , Vecchi M. , Vernin P. , Wijnker G. , de Wolf E. , Yepes H. , Zaborov D. , Zornoza J. D. , Zúñiga J.
Published: April 2010

Abstract. An Acoustic Doppler Current Profiler (ADCP) moored at the deep-sea ANTARES neutrino telescope site near Toulon, France, measured downward vertical currents of amplitudes up to 0.03 m s−1 in spring 2006. The currents were accompanied by enhanced levels of acoustic reflection by a factor of about 10 and by horizontal currents reaching 0.35 m s−1. These observations coincided with high levels of bioluminescence detected by the telescope. Although during winter 2006 deep dense-water formation occurred in this area, episodes of high levels of suspended particles and large vertical currents continuing into the summer are not direct evidence of this process. It is hypothesized that the main process allowing for particles to be moved across the entire water column (2500 m) within a few days, is local convection, triggered by small-mesoscale phenomena, such as meanders including a bipolar vortex, linked with boundary current instabilities.
The Gregoriev Ice Cap length changes derived by 2-D ice flow line model for harmonic climate histories
Authors: Konovalov Y. V. , Nagornov O. V.
Published: April 2010

Abstract. Different ice thickness distributions along the flow line and the flow line length changes of the Gregoriev Ice Cap, Terskey Ala-Tau, Central Asia, were obtained for some surface mass balance histories which can be considered as possible surface mass balances in the future. The ice cap modeling was performed by solving of steady state hydrodynamic equations in the case of low Reynolds number in the form of the mechanical equilibrium equation in terms of stress deviator components coupled with the continuity equation for incompressible fluid. The numerical solution was obtained by the finite difference method. A compound approximation of the ice surface boundary condition based on the extending of the mechanical equilibrium equation to ice surface points was applied. The approximation is considered as a way to overcome the problem of diagnostic equations numerical solution stability in the full model. The basal sliding can arise in the glacier tongue at certain climatic conditions and was introduced both through linear and through non-linear friction laws. A possible glacier length history, that corresponds to the regional climate changes derived from the tree-rings data, was obtained by the model. The correlations between the glacier length changes and annual air temperature histories were investigated within the simplified equation introduced by J. Oerlemans in the form of linear dependence of annual air temperature versus glacier length and time derivative of the length. The parameters of the dependence were derived from modeled glacier length histories that correspond to harmonic climate histories. The parameters variations were investigated for different periodicities of harmonic climate histories and appropriate dependences are presented in the paper. The results of the modeling are in a good agreement with the J. Oerlemans climatic model.
The mechanics of gravity-driven faulting
Authors: Barrows L. , Barrows V.
Published: April 2010

Abstract. Faulting can result from either of two different mechanisms. These involve fundamentally different energetics. In elastic rebound, locked-in elastic strain energy is transformed into the earthquake (seismic waves plus work done in the fault zone). In force-driven faulting, the forces that create the stress on the fault supply work or energy to the faulting process. Half of this energy is transformed into the earthquake and half goes into an increase in locked-in elastic strain. In elastic rebound the locked-in elastic strain drives slip on the fault. In force-driven faulting it stops slip on the fault. Tectonic stress is reasonably attributed to gravity acting on topography and the Earth's lateral density variations. This includes the thermal convection that ultimately drives plate tectonics. Mechanical analysis has shown the intensity of the gravitational tectonic stress that is associated with the regional topography and lateral density variations that actually exist is comparable with the stress drops that are commonly associated with tectonic earthquakes; both are in the range of tens of bar to several hundred bar. The gravity collapse seismic mechanism assumes the fault fails and slips in direct response to the gravitational tectonic stress. Gravity collapse is an example of force-driven faulting. In the simplest case, energy that is released from the gravitational potential of the stress-causing topography and lateral density variations is equally split between the earthquake and the increase in locked-in elastic strain. The release of gravitational potential energy requires a change in the Earth's density distribution. Gravitational body forces are solely dependent on density so a change in the density distribution requires a change in the body forces. This implies the existence of volumetric body-force displacements. The volumetric body-force displacements are in addition to displacements generated by slip on the fault. They must exist if gravity participates in the energetics of the faulting process. From the perspective of gravitational tectonics, the gravity collapse mechanism is direct and simple. The related mechanics are more subtle. If gravity is not deliberately and explicitly included in an earthquake model, then gravity is locked out of the energetics of the model. The earthquake model (but not necessarily the physical reality) is then elastic rebound.
Summary of Northeast Asia geodynamics and tectonics*
Authors: Parfenov L. M. , Badarch G. , Berzin N. A. , Khanchuk A. I. , Kuzmin M. I. , Nokleberg W. J. , Prokopiev A. V. , Ogasawara M. , Yan H.
Published: April 2010

Abstract. The compilation, synthesis, description, and interpretation of regional geology and tectonics of major regions, such as Northeast Asia (Eastern Russia, Mongolia, Northern China, South Korea, and Japan) and the Circum-North Pacific (the Russian Far East, Alaska, and Canadian Cordillera), requires a complex methodology that includes: (1) definitions of key terms; (2) compilation of a regional geodynamics map that can be constructed according to modern tectonic concepts and definitions; and (3) formulation of a comprehensive tectonic model. This article presents a summary of the regional dynamics and tectonics of Northeast Asia as developed for a new summary geodynamics map of the region. This article also describes how a high-quality summary geodynamics map and companion tectonic analysis substantially aids in the understanding of the origin of major rock units, major structures, and contained mineral and fuel resources, and provides important guidelines for new research. * Prepared in memory of Leonid M. Parfenov, the leader of the geodynamics map team for the International collaborative project on NE Asia tectonics and metallogenesis.
Tectonic reconstruction of Uda-Murgal arc and the Late Jurassic and Early Cretaceous convergent margin of Northeast Asia–Northwest Pacific
Authors: Sokolov S. D. , Bondarenko G. Ye. , Khudoley A. K. , Morozov O. L. , Luchitskaya M. V. , Tuchkova M. I. , Layer P. W.
Published: April 2010

Abstract. A long tectonic zone composed of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks is recognized along the Asian continent margin from the Mongol-Okhotsk fold and thrust belt on the south to the Chukotka Peninsula on the north. This belt represents the Uda-Murgal arc, which was developed along the convergent margin between Northeast Asia and Northwest Meso-Pacific. Several segments are identified in this arc based upon the volcanic and sedimentary rock assemblages, their respective compositions and basement structures. The southern and central parts of the Uda-Murgal arc were a continental margin belt with heterogeneous basement represented by metamorphic rocks of the Siberian craton, the Verkhoyansk terrigenous complex of Siberian passive margin and the Koni-Taigonos Late Paleozoic to Early Mesozoic island arc with accreted oceanic terranes. At the present day latitude of the Pekulney and Chukotka segments there was an ensimatic island arc with relicts of the South Anyui oceanic basin in a backarc basin. Accretionary prisms of the Uda-Murgal arc and accreted terranes contain fragments of Permian, Triassic to Jurassic and Jurassic to Cretaceous (Tithonian–Valanginian) oceanic crust and Jurassic ensimatic island arcs. Paleomagnetic and faunal data show significant displacement of these oceanic complexes and the terranes of the Taigonos Peninsula were originally parts of the Izanagi oceanic plate.
Paleomagnetism of the Cretaceous rocks from Cape Kronotskiy, East Kamchatka and reconstruction of terrane trajectories in the NE Pacific area
Authors: Harbert W. , Tsukanov N. V. , Alexeiev D. V. , Gaedicke C. , Freitag R. , Baranov B. V. , Skolotnev S. G. , Kramer W. , Seifert W.
Published: April 2010

Abstract. The Kamchatka Peninsula of northeastern Russia is located along the northwestern margin of the Bering Sea and consists of zones of complexly deformed accreted terranes. Paleomagnetic samples were collected for study from a Late Cretaceous aged locality at Cape Kronotskiy (λ=54°44.8´ N, φ=162°1.29´ E). Two components of magnetization were observed. During stepwise thermal demagnetization, the B-magnetic component was observed up to 600°C having a direction and associated uncertainty in stratigraphic coordinates of Ds=300.7°, Is=48.7°, α95=10.9°, k-value=11.8, n=17. The B component paleolatitude calculated from the Fisher mean in stratigraphic coordinates and associated statistics are λobs=30.4° N or S, λ95=8.9°, n=17 (sites), k-value=11. Our overall study paleolatitude result is similar to a previously reported paleomagnetic study completed within this unit. Terrane trajectories calculated using the finite rotation poles of Engebretson et al. (1985), which are corrected for either Pacific-hotspot drift or True Polar Wander hotspot-spin axis relative motion, show that the sampled unit represents a far traveled tectonostratigraphic terrane and support a model in which accretion (docking) events of this composite or superterrane with the North America plate occur at approximately 40 Ma.
Paleomagnetic determination of paleolatitude and rotation of Bering Island (Komandorsky Islands) Russia: comparison with rotations in the Aleutian Islands and Kamchatka
Authors: Minyuk P. S. , Stone D. B.
Published: April 2010

Abstract. A paleomagnetic study was carried out on Paleogene sedimentary rocks from Bering Island, Komandorsky islands, located at the far western end of the Aleutian Island Arc. The age of these sediments has been debated at length, but the combination of magnetostratigraphy with the fossil record indicates that the base of the section is of early Eocene (approximately 55 Ma) and the top latest Eocene age. Paleomagnetic data were obtained from 260 samples from 60 individual bedding units. The combined data show a clockwise rotation R=26.3°±8.5°, F=8.1°±2.5° with respect to the North American Plate and R=38°±8.8°, F=8.7°±2.7° with respect to the Eurasian Plate. They also show a shallowing of the inclination which yields a paleolatitude of 53°, 12° south of its expected latitude. The shallowing may have a component due to compaction, but the wide variation in sampled lithologies, combined with internal consistency of the data set, would argue against the shallowing being significant. To compare these data with other Aleutian Arc data we compiled a comprehensive survey of all available data sets. Out of these we selected four islands for which the data passed basic reliability criteria, namely Umnak, Amlia, Amchitka and Medny islands. All four showed significant clockwise rotation with respect to both North American and Eurasian polar wander paths. Several mechanisms can generate the observed rotation, ranging from block rotation driven by oblique relative motion of the Pacific plate, through lateral transport along the curve of the arc, to whole-arc rotation about its eastern end. The distribution and age spread of the rotation data are insufficient to discriminate between mechanisms, but it seems likely that different mechanism may have operated at different times and in different locations.
Geology of the Shelves surrounding the New Siberian Islands, Russian Arctic
Authors: Franke D. , Hinz K.
Published: April 2010

Abstract. A total of 11 700 km of multichannel seismic reflection data were acquired during recent reconnaissance surveys of the wide, shallow shelves of the Laptev and western East Siberian Seas around the New Siberian Islands. To the north of the Laptev Sea, the Gakkel Ridge, an active mid-ocean ridge which separates the North American and Eurasian Plates, meets abruptly the steep slope of the continental shelf. Extension has affected the Laptev Shelf since at least the Early Tertiary and has resulted in the formation of three major, generally north-south trending rift basins: the Ust' Lena Rift, the Anisin Basin, and the New Siberian Basin. Our data indicate that the rift basins on the Laptev Shelf are not continuous with those on the East Siberian Shelf. The latter shelf can best be described as an epicontinental platform which has undergone continuous subsidence since the Late Cretaceous. The greatest subsidence occurred in the NE, manifested by a major depocentre filled with inferred (?)Late Cretaceous to Tertiary sediments up to 5 s (twt) thick. On the basis of deep reflection data we revise and adjust Mesozoic domain boundaries around the New Siberian Islands.
Thresholds in the sliding resistance of simulated basal ice
Authors: Emerson L. F. , Rempel A. W.
Published: April 2010

Abstract. We report laboratory determinations of the shear resistance to sliding melting ice with entrained particles over a hard, impermeable surface. With higher particle concentrations and larger particle sizes, Coulomb friction at particle-bed contacts dominates and the shear stress increases linearly with normal load. We term this the sandy regime. When either particle concentration or particle size is reduced below a threshold, the dependence of shear resistance on normal load is no longer statistically significant. We term this regime slippery. We use force and mass balance considerations to examine the flow of melt water beneath the simulated basal ice. At high particle concentrations, the transition from sandy to slippery behavior occurs when the particle size is comparable to the thickness of the melt film that separates the sliding ice from its bed. For larger particle sizes, a transition from sandy to slippery behavior occurs when the particle concentration drops sufficiently that the normal load is no longer transferred completely to the particle-bed contacts. We estimate that the melt films separating the particles from the ice are approximately 0.1 µm thick at this transition. Our laboratory results suggest the potential for abrupt transitions in the shear resistance beneath hard-bedded glaciers with changes in either the thickness of melt layers or the particle loading.
Reconstructing the glacier contribution to sea-level rise back to 1850
Authors: Oerlemans J. , Dyurgerov M. , van de Wal R. S. W.
Published: April 2010

Abstract. We present a method to estimate the glacier contribution to sea-level rise from glacier length records. These records form the only direct evidence of glacier changes prior to 1946, when the first continuous mass-balance observations began. A globally representative length signal is calculated from 197 length records from all continents by normalisation and averaging of 14 different regions. Next, the resulting signal is calibrated with mass-balance observations for the period 1961–2000. We find that the glacier contribution to sea level rise was 5.5±1.0 cm during the period 1850–2000 and 4.5±0.7 cm during the period 1900–2000.
Transient thermal effects in Alpine permafrost
Authors: Noetzli J. , Gruber S.
Published: April 2010

Abstract. In high mountain areas, permafrost is important because it influences the occurrence of natural hazards, because it has to be considered in construction practices, and because it is sensitive to climate change. The assessment of its distribution and evolution is challenging because of highly variable conditions at and below the surface, steep topography and varying climatic conditions. This paper presents a systematic investigation of effects of topography and climate variability that are important for subsurface temperatures in Alpine bedrock permafrost. We studied the effects of both, past and projected future ground surface temperature variations on the basis of numerical experimentation with simplified mountain topography in order to demonstrate the principal effects. The modeling approach applied combines a distributed surface energy balance model and a three-dimensional subsurface heat conduction scheme. Results show that the past climate variations that essentially influence present-day permafrost temperatures at depth of the idealized mountains are the last glacial period and the major fluctuations in the past millennium. Transient effects from projected future warming, however, are likely larger than those from past climate conditions because larger temperature changes at the surface occur in shorter time periods. We further demonstrate the accelerating influence of multi-lateral warming in steep and complex topography for a temperature signal entering the subsurface as compared to the situation in flat areas. The effects of varying and uncertain material properties (i.e., thermal properties, porosity, and freezing characteristics) on the subsurface temperature field were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over time periods of decades to centuries. At the end, the model was applied to the topographic setting of the Matterhorn (Switzerland). Results from idealized geometries are compared to this first example of real topography, and possibilities as well as limitations of the model application are discussed.
The effect of the north-east ice stream on the Greenland ice sheet in changing climates
Authors: Greve R. , Otsu S.
Published: April 2010

Abstract. The north-east Greenland ice stream (NEGIS) was discovered as a large fast-flow feature of the Greenland ice sheet by synthetic aperture radar (SAR) imaginary of the ERS-1 satellite. In this study, the NEGIS is implemented in the dynamic/thermodynamic, large-scale ice-sheet model SICOPOLIS (Simulation Code for POLythermal Ice Sheets). In the first step, we simulate the evolution of the ice sheet on a 10-km grid for the period from 250 ka ago until today, driven by a climatology reconstructed from a combination of present-day observations and GCM results for the past. We assume that the NEGIS area is characterized by enhanced basal sliding compared to the "normal", slowly-flowing areas of the ice sheet, and find that the misfit between simulated and observed ice thicknesses and surface velocities is minimized for a sliding enhancement by the factor three. In the second step, the consequences of the NEGIS, and also of surface-meltwater-induced acceleration of basal sliding, for the possible decay of the Greenland ice sheet in future warming climates are investigated. It is demonstrated that the ice sheet is generally very susceptible to global warming on time-scales of centuries and that surface-meltwater-induced acceleration of basal sliding can speed up the decay significantly, whereas the NEGIS is not likely to dynamically destabilize the ice sheet as a whole.
Mountain glaciers of NE Asia in the near future: a projection based on climate-glacier systems' interaction
Authors: Ananicheva M. D. , Krenke A. N. , Hanna E.
Published: April 2010

Abstract. In this study we consider contrasting continental (Orulgan, Suntar-Khayata and Chersky ranges located in the Pole of Cold area at the contact of Atlantic and Pacific influences) and maritime (Kamchatka under the Pacific influence) Russian glacier systems. Our purpose is to present a simple method for the projection of change of the main parameters of these glacier systems with climate change. To achieve this aim, we constructed vertical profiles of mass balance (accumulation and ablation) based both on meteorological observations for the mid to late 20th century and an ECHAM4 GCM scenario for 2040–2069. The observations and scenario were used for defining the recent and future equilibrium line altitude (ELA) for each glacier system. The altitudinal distributions of the areas covered with glacier ice were determined for present and future states of the glacier systems, taking into account the correlation of the change of the ELA and glacier-termini levels. We also give estimates of the possible changes of the areas and morphological structure of North-eastern Asia glacier systems and their mass balance characteristics from the ECHAM4 scenario. Finally, we compare characteristics of the continental and maritime glacier systems stability under conditions of global warming.
Model resolution influence on simulated sea ice decline
Authors: Sewall J. O.
Published: April 2010

Abstract. Satellite observations and model predictions of recent and future Arctic sea ice decline have raised concerns over the timing and potential impacts of a seasonally ice-free Arctic Ocean. Model predictions of seasonally ice-free Arctic conditions are, however, highly variable. Here I present results from fourteen climate system models from the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset that indicate modeled Arctic sea ice sensitivity to increased atmospheric CO2 forcing is strongly correlated with ice/ocean model horizontal resolution. Based on coupled model analyses and ice only simulations with the Los Alamos National Lab sea ice model (CICE), the correlation between declining Arctic sea ice cover and ice/ocean model resolution appears to depend largely on ocean model resolution and its influence on ocean heat transport into the Arctic basin. The correlation between model resolution, northward ocean heat transport, and the degree of Arctic ice loss is independent of ice model physics and complexity. This not only illustrates one difficulty in using numerical models to accurately predict the timing and magnitude of Arctic sea ice decline under increasing atmospheric greenhouse gas forcing, but also highlights one area where improved simulation (of northward ocean heat transport) could greatly decrease the uncertainties associated with predictions of future Arctic sea ice cover.
Comparison of airborne radar altimeter and ground-based Ku-band radar measurements on the ice cap Austfonna, Svalbard
Authors: Brandt O. , Hawley R. L. , Kohler J. , Hagen J. O. , Morris E. M. , Dunse T. , Scott J. B. T. , Eiken T.
Published: April 2010

Abstract. We compare coincident data from the European Space Agency's Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) with ground-based Very High Bandwidth (VHB) stepped-frequency radar measurements in the Ku-band. The ASIRAS instrument obtained data from ~700 m above the surface, using a 13.5 GHz center frequency and a 1 GHz bandwidth. The ground-based VHB radar measurements were acquired using the same center frequency, but with a variable bandwidth of either 1 or 8 GHz. Four sites were visited with the VHB radar; two sites within the transition region from superimposed ice to firn, and two sites in the long-term firn area (wet-snow zone). The greater bandwidth VHB measurements show that the first peak in the airborne data is a composite of the return from the surface (i.e. air-snow interface) and returns of similar or stronger amplitude from reflectors in the upper ~30 cm of the subsurface. The peak position in the airborne data is thus not necessarily a good proxy for the surface since the maximum and width of the first return depend on the degree of interference between surface and subsurface reflectors. The major response from the winter snowpack was found to be caused by units of thin crust/ice layers (0.5–2 mm) surrounded by large crystals (>3 mm). In the airborne data, it is possible to track such layers for tens of kilometers. The winter snowpack lacked thicker ice layers. The last year's summer surface, characterized by a low density large crystal layer overlaying a harder denser layer, gives a strong radar response, frequently the strongest. The clear relationship observed between the VHB and ASIRAS waveforms, justifies the use of ground-based radar measurements in the validation of air- or spaceborne radars.
Surface melt magnitude retrieval over Ross Ice Shelf, Antarctica using coupled MODIS near-IR and thermal satellite measurements
Authors: Lampkin D. J. , Karmosky C. C.
Published: April 2010

Abstract. Surface melt has been increasing over recent years, especially over the Antarctic Peninsula, contributing to disintegration of shelves such as Larsen. Unfortunately, we are not realistically able to quantify surface snowmelt from ground-based methods because there is sparse coverage of automatic weather stations. Satellite based assessments of melt from passive microwave systems are limited in that they only provide an indication of melt occurrence and have coarse spatial resolution. An algorithm was developed to retrieve surface melt magnitude using coupled near-IR/thermal surface measurements from MODIS were calibrated by estimates of liquid water fraction (LWF) in the upper 1 cm of the firn derived from a one-dimensional physical snowmelt model (SNTHERM89). For the modeling phase of this study, SNTHERM89 was forced by hourly meteorological data from automatic weather station data at reference sites spanning a range of melt conditions across the Ross Ice Shelf during a relatively intense melt season (2002). Effective melt magnitude or LWF were derived for satellite composite periods covering the Antarctic summer months at a 4 km resolution over the entire Ross Ice Shelf, ranging from 0–0.5% LWF in early December to areas along the coast with as much as 1% LWF during the time of peak surface melt. Spatial and temporal variations in the magnitude of surface melt are related to both katabatic wind strength and advection during onshore flow.
Interaction between ice sheet dynamics and subglacial lake circulation: a coupled modelling approach
Authors: Thoma M. , Grosfeld K. , Mayer C. , Pattyn F.
Published: April 2010

Abstract. Subglacial lakes in Antarctica influence to a large extent the flow of the ice sheet. In this study we use an idealised lake geometry to study this impact. We employ a) an improved three-dimensional full Stokes ice flow model with a nonlinear rheology, b) a three-dimensional fluid dynamics model with eddy diffusion to simulate basal mass balance, and c) a newly developed coupler to exchange boundary conditions between individual models. Different boundary conditions are applied over grounded ice and floating ice. This results in significantly increased temperatures within the ice on top of the lake, compared to ice at the same depth outside the lake area. Basal melting of the ice sheet increases this lateral temperature gradient. Upstream the ice flow converges towards the lake and accelerates by about 10% whenever basal melting at the ice–lake boundary is present. Above and downstream of the lake, where the ice flow diverges, a velocity decrease of about 10% is simulated.
Geometric changes and mass balance of the Austfonna ice cap, Svalbard
Authors: Moholdt G. , Hagen J. O. , Eiken T. , Schuler T. V.
Published: April 2010

Abstract. The dynamics and mass balance regime of the Austfonna ice cap, the largest glacier on Svalbard, deviate significantly from most other glaciers in the region and is not fully understood. We have compared ICESat laser altimetry, airborne laser altimetry, GNSS surface profiles and radio echo-sounding data to estimate elevation change rates for the periods 1983–2007 and 2002–2008. The data sets indicate a pronounced interior thickening of up to 0.5 m y−1, at the same time as the margins are thinning at a rate of 1–3 m y−1. The southern basins are thickening at a higher rate than the northern basins due to a higher accumulation rate. The overall volume change in the 2002–2008 period is estimated to be −1.3±0.5 km3 w.e. y−1 (or −0.16±0.06 m w.e. y−1) where the entire net loss is due to a rapid retreat of the calving fronts. Since most of the marine ice loss occurs below sea level, Austfonna's current contribution to sea level change is close to zero. The geodetic results are compared to in-situ mass balance measurements which indicate that the 2004–2008 surface net mass balance has been slightly positive (0.05 m w.e. y−1) though with large annual variations. Similarities between local net mass balances and local elevation changes indicate that most of the ice cap is dormant and not in dynamic equilibrium with the current climate. More knowledge is needed about century-scale dynamic processes in order to predict the future evolution of Austfonna based on climate scenarios.
Degree-day modelling of the surface mass balance of Urumqi Glacier No. 1, Tian Shan, China
Authors: Huintjes E. , Li H. , Sauter T. , Li Z. , Schneider C.
Published: April 2010

Abstract. A distributed temperature-index melt model including potential shortwave radiation is used to calculate annual mean surface mass balance and the spatial distribution of melt rates on the east branch of Urumqi Glacier No. 1, north-western China. The lack of continuous datasets at higher temporal resolution for various climate variables suggests the application of a degree-day model with only few required input variables. The model is calibrated for a six day period in July 2007, for which daily mass balance measurements and meteorological data are available. Based on point measurements of mass balance, parameter values are optimised running a constrained multivariable function using the simplex search method. To evaluate the model performance, annual mass balances for the period 1987/88–2004/05 are calculated using NCEP/NCAR-Reanalysis data. The modelled values fit the observed mass balance with a correlation of 0.98 and an RMSE of 332 mm w.e. Furthermore, the calculated spatial distribution of melt rates shows an improvement in small-scale variations compared to the simple degree-day approach.
Microencapsulation
Authors: Lamprecht Alf , Bodmeier Roland
Published: April 2010

The article contains sections titled:1.Introduction2.Applications for Microencapsulation3.Materials4.Production4.1.Phase Separation4.2.Interfacial and in situ Polymerization4.3.Spray Drying, Spray Congealing4.4.Solvent Evaporation Processes4.5.Coating Processes4.6.Spinning Disk5.Other Forms of Microencapsulation6.Characterization of Microparticles7.Uses
Distillation, 1. Fundamentals
Authors: Stichlmair Johann
Published: April 2010

Distillation (or rectification) is the most important technique for separating fluid mixtures into pure substances. Distillation is extensively used in chemical, petrochemical, pharmaceutical, and food industries. This article presents a concise description of the state of the art and of novel developments. Distillation, 1. Fundamentals deals with the basic principles of distillation processes, e.g., vapor liquid equilibrium and separation mechanisms in counter current columns. In the focus are binary as well as multi‐component systems. → Distillation, 2. Equipmentdeals with the equipment of industrial distillation plants. The design principles of tray columns and packed columns are explained, and typical operational data are given. The objective of → Distillation, 3. Processesis the conceptual design of complex distillation processes such as: batch distillation, azeotropic distillation, extractive distillation, and reactive distillation. Some examples of important industrial distillation processes are also presented, i.e., sea water desalination, air separation, crude oil raffination, and production of absolute alcohol.

The article contains sections titled:1.Introduction2.Vapor–Liquid Equilibrium2.1.Ideal Systems2.2.Real Systems3.Distillation (Single‐Stage Distillation)3.1.Continuous Distillation3.2.Batch Distillation4.Rectification (Multi‐Stage Distillation)4.1.Binary Mixtures4.2.Ternary Mixtures4.3.Multi‐Component Mixtures4.4.Batch Distillation (Multi‐Stage)4.5.Reactive Distillation
Effect of ball milling on the hydrolysis of microcrystalline cellulose in hot‐compressed water
Authors: Yu Yun , Wu Hongwei
Published: April 2010

Ball milling leads to a considerable reduction in cellulose particle size and crystallinity, as well as a significant increase in the specific reactivity of cellulose during hydrolysis in hot‐compressed water (HCW). Cryogenic ball milling for 2 min also results in a significant size reduction but only little change in cellulose crystallinity and specific reactivity during hydrolysis. Therefore, crystallinity is the dominant factor in determining the hydrolysis reactivity of cellulose in HCW while particle size only plays a minor role. Ball milling also significantly influences the distribution of glucose oligomers in the primary liquid products of cellulose hydrolysis. It increases the selectivities of glucose oligomers at low conversions. At high conversions, the reduction in chain length plays an important role in glucose oligomer formation as cellulose samples become more crystalline. An extensive ball milling completely converts the crystalline cellulose into amorphous cellulose, substantially enhancing the formation of glucose oligomers with high degrees of polymerization. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Pilot assessment of a radiologic classification system for segmentation defects of the vertebrae
Authors: Offiah Amaka , Alman Benjamin , Cornier Alberto S. , Giampietro Philip F. , Tassy Olivier , Wade Angie , Turnpenny Peter D.
Published: April 2010

Existing nomenclature systems for describing and reporting congenital segmentation defects of the vertebrae (SDV) are confusing, inconsistently applied, and lack molecular genetic advances. Our aim was to develop and assess a new classification system for SDV. A multidisciplinary group of the International Consortium for Vertebral Anomalies and Scoliosis (ICVAS) developed a new classification system for SDV, and 5 members group (Group 1) independently classified 10 previously unseen cases using this system. Inter‐observer reliability was assessed using kappa, which compares observed agreement with that expected by chance. Seven independent general radiologists unaffiliated with the ICVAS (Group 2) classified the same 10 cases (total, 70 scores) before and after the ICVAS system was explained. We demonstrated the following: Inter‐observer reliability for Group 1 yielded a kappa value of 0.21 (95% confidence intervals (CI) 0.052, 0.366, P = 0.0046); A consensus diagnosis was established for the 10 cases. For Group 2, before the ICVAS system was explained, 1 of 70 scores (1.4%) agreed with the Group 1 consensus diagnoses; Group 2 offered 12 different diagnoses, but 38 of 70 (54.3%) responses were “Don't Know.” After the ICVAS system was explained, 47 of 70 responses (67.1%; 95% CI 55.5, 77.0) agreed with the Group 1 consensus, an improvement of 65.7% (95% CI 52.5, 75.6, P < 0.00005), with no “Don't Know” responses. Group 2 average reporting times, before and after explanation of the ICVAS system, were 148 and 48 min, respectively. We conclude that the ICVAS radiological classification system was found to be reliable and applicable for 10 SDV phenotypes. © 2010 Wiley‐Liss, Inc.
Diet and mobility in Early Medieval Bavaria: A study of carbon and nitrogen stable isotopes
Authors: Hakenbeck Susanne , McManus Ellen , Geisler Hans , Grupe Gisela , O'Connell Tamsin
Published: April 2010

This study investigates patterns of mobility in Early Medieval Bavaria through a combined study of diet and associated burial practice. Carbon and nitrogen isotope ratios were analyzed in human bone samples from the Late Roman cemetery of Klettham and from the Early Medieval cemeteries of Altenerding and Straubing‐Bajuwarenstrasse. For dietary comparison, samples of faunal bone from one Late Roman and three Early Medieval settlement sites were also analyzed. The results indicate that the average diet was in keeping with a landlocked environment and fairly limited availability of freshwater or marine resources. The diet appears not to have changed significantly from the Late Roman to the Early Medieval period. However, in the population of Altenerding, there were significant differences in the diet of men and women, supporting a hypothesis of greater mobility among women. Furthermore, the isotopic evidence from dietary outliers is supported by “foreign” grave goods and practices, such as artificial skull modification. These results reveal the potential of carbon and nitrogen isotope analysis for questions regarding migration and mobility. Am J Phys Anthropol 143:235–249, 2010. © 2010 Wiley‐Liss, Inc.
Brief communication: A probabilistic approach to age estimation from infracranial sequences of maturation
Authors: Coqueugniot Hélène , Weaver Timothy D. , Houët Francis
Published: April 2010

Infracranial sequences of maturation are commonly used to estimate the age at death of nonadult specimens found in archaeological, paleoanthropological, or forensic contexts. Typically, an age assessment is made by comparing the degree of long‐bone epiphyseal fusion in the target specimen to the age ranges for different stages of fusion in a reference skeletal collection. While useful as a first approximation, this approach has a number of shortcomings, including the potential for “age mimicry,” being highly dependent on the sample size of the reference sample and outliers, not using the entire fusion distribution, and lacking a straightforward quantitative way of combining age estimates from multiple sites of fusion. Here we present an alternative probabilistic approach based on data collected on 137 individuals, ranging in age from 7‐ to 29‐years old, from a documented skeletal collection from Coimbra, Portugal. We then use cross validation to evaluate the accuracy of age estimation from epiphyseal fusion. While point estimates of age can, at least in some circumstances, be both accurate and precise based on the entire skeleton, or many sites of fusion, there will often be substantial error in these estimates when they derive from one or only a few sites. Because a probabilistic approach to age estimation from epiphyseal fusion is computationally intensive, we make available a series of spreadsheets or computer programs that implement the approach presented here. Am J Phys Anthropol 142:655–664, 2010. © 2010 Wiley‐Liss, Inc.
Applying semantic networks to hypertext design: Effects on knowledge structure acquisition and problem solving
Authors: Khalifa Mohamed , Shen Kathy Ning
Published: April 2010

One of the key objectives of knowledge management is to transfer knowledge quickly and efficiently from experts to novices, who are different in terms of the structural properties of domain knowledge or knowledge structure. This study applies experts' semantic networks to hypertext navigation design and examines the potential of the resulting design, i.e., semantic hypertext, in facilitating knowledge structure acquisition and problem solving. Moreover, we argue that the level of sophistication of the knowledge structure acquired by learners is an important mediator influencing the learning outcomes (in this case, problem solving). The research model was empirically tested with a situated experiment involving 80 business professionals. The results of the empirical study provided strong support for the effectiveness of semantic hypertext in transferring knowledge structure and reported a significant full mediating effect of knowledge structure sophistication. Both theoretical and practical implications of this research are discussed.
Strategic investment decisions under fast mean‐reversion stochastic volatility
Authors: Souza Max O. , Zubelli Jorge P.
Published: April 2010

We are concerned with investment decisions when the spanning asset that correlates with the investment value undergoes a stochastic volatility dynamics. The project value in this case corresponds to the value of an American call with dividends, which can be priced by solving a generalized Black–Scholes free‐boundary value problem. Following ideas of Fouque et al. under the hypothesis of fast mean‐reversion, we obtain the formal asymptotic expansion of the project value and compute the adjustment of the price due to the stochastic volatility. We show that the presence of the stochastic volatility can alter the optimal time investment curve in a significative way, which in turn implies that caution should be taken with the assumption of constant volatility prevalent in many real option models. Additionally, we also present analytical results for the perpetual case. We also indicate how to calibrate to market data the model in the asymptotic regime. Copyright © 2010 John Wiley & Sons, Ltd.