Miracle-dz/UniFAR-FTUs huggingface dataset:
Passive seismic imaging with directive ambient noise: application to surface waves and the San Andreas Fault in Parkfield, CA

SUMMARY This study deals with surface waves extracted from microseismic noise in the (0.1–0.2 Hz) frequency band with passive seismic-correlation techniques. For directive noise, we explore the concept of passive seismic-noise tomography performed on three-component sensors from a dense seismic network. From the nine-component correlation tensor, a rotation algorithm is introduced that forces each station pair to re-align in the noise direction, a necessary condition to extract unbiased traveltime from passive seismic processing. After rotation is performed, the new correlation tensor exhibits a surface wave tensor from which Rayleigh and Love waves can be separately extracted for tomography inversion. Methodological aspects are presented and illustrated with group-speed maps for Rayleigh and Love waves and ellipticity measurements made on the San Andreas Fault in the Parkfield area, California, USA.
Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean

We present a new method for assimilating observations of sea surface height (SSH) into a high-resolution primitive equation model. The method is based on the concept of reinitialization. First, the surface velocity increments necessary to adjust the model forecast to the observed geostrophic surface currents are projected onto deep velocity increments by a linear regression method. Second, changes in the density field required to balance the changes in the velocity field geostrophically are obtained from an inversion of the thermal wind equation. A unique partition of the density increments into corresponding temperature and salinity changes is realized by conserving the local θ-S relation of the model forecast. In contrast to pure statistical methods that infer temperature and salinity changes from correlations with SSH anomalies, our approach explicitly conserves water mass properties on isopycnals. For the assimilation experiment we use optimally interpolated maps of Geosat SSH anomalies (the mean topography is taken from the model), which are assimilated into the World Ocean Circulation Experiment (WOCE) Community Modeling Effort (CME) model of the North Atlantic Ocean at 5-day intervals covering the year 1987. It is shown that the assimilation significantly improves the model's representation of eddy activity, with the hydrographic structure of individual eddies agreeing well with independent hydrographic observations. The importance of a careful treatment of water mass properties in the assimilation process is discussed and further illustrated by comparing different assimilation schemes.
Cycles and Events in Stratigraphy

This book reviews and discusses the most up-to-date knowledge in the fields of cyclostratigraphy and event stratigraphy. The book contains 48 papers contributed by the most knowledgeable geologists and paleontologists in the fields of cycle and event stratigraphy. It is divided into two parts. Part one is concerned with the structure of individual beds and larger cycles and sequences and discusses; rhythmic stratification, event stratification, diagenetic overprint, cherts and phosphorites, and preservation and biologic destruction of laminated sediments. Part two, on larger cycles and sequences, looks at sequences, hierarchies, causes and environmental expression, and timing and correlation, i.e. the cycles of frequencies from millions of years to thousands of years (Milankovich band). Summaries on spectral analysis are also presented. There are 80 pages of references and a comprehensive index. It is extensively illustrated with line drawings and graphs. Practicing sedimentary geologists without access to a good library or find it hard to keep up with the plethora of journal articles and want a refresher in this area of stratigraphy will find the book particularly useful.
The role of plant-soil interactions in peatland carbon cycling at a Scottish wind farm

Northern peatlands play an important role in the cycling of carbon (C) globally, and contain up to one third of the world’s soil C despite only covering a small percentage of its land surface (Gorham, 1991). Changes in climate and land use are increasing the vulnerability of these vast C stocks, by altering the conditions favourable for peat accumulation and therefore C sequestration. The establishment of wind farms on peatlands is increasing in the UK, as a result of the growing need for sustainable energy and the suitably high wind speeds that are typical to these upland ecosystems (Smith et al., 2014). There is limited understanding of the impacts of operational wind farms on their host ecosystems, but evidence to suggest that wind farms create microclimate conditions by altering ground-level temperature is increasing (Armstrong et al., 2014a; Baidya Roy and Traiteur, 2010; L. Zhou et al., 2012). The sensitivity of peatland C cycling processes to wind farm-induced microclimatic changes represents a considerable gap in knowledge. Further, the role that aboveground and belowground peatland communities have in mediating the effects of wind farm microclimates on C cycling processes remains unknown. By examining plant-soil interactions across a peatland at Black Law Wind Farm and under a range of microclimate conditions in the laboratory, this thesis aimed to investigate the influence of plant functional type (PFT) and microclimatic conditions on physical, chemical and biological peatland properties, greenhouse gas (GHG) emissions and litter decomposition. Results show that a PFT legacy in peat plays a mediatory role in the response of CO2 and CH4 emissions to microclimatic differences in temperature and water table. Mass loss of litter is primarily driven by PFT differences in litter quality, with interactions between litter types controlling decomposition of litter mixtures via non-additive effects, and interactions between litter types and PFT legacies in peat affecting the likelihood of home-field advantage and disadvantage (HFA and HFD) litter mass loss. This thesis demonstrates that the direct effects of microclimatic changes in temperature and water table are important drivers of peatland C cycling processes; however the indirect effects of microclimate change on plant community composition e.g. the relative proportion of PFTs could influence these processes to a greater extent. Examining the importance of PFTs in C cycling processes at wind farm peatlands is important in improving predictions of peatland C sequestration under future climate change scenarios, and in calculating the C savings achieved by land-based renewable technologies.
The structure and dynamics of geographic ranges

structure and dynamics of geographic ranges. Book lovers, when you need a new book to read, find the book here. Never worry not to find what you need. Is the structure and dynamics of geographic ranges your needed book now? That's true; you are really a good reader. This is a perfect book that comes from great author to share with you. The book offers the best experience and lesson to take, not only take, but also learn.
Acquisition, orthorectification, and object-based classification of unmanned aerial vehicle (UAV) imagery for rangeland monitoring.

The use of unmanned aerial vehicles (UAVs) for natural resource applications has increased considerably in recent years due to their greater availability, the miniaturization of sensors, and the ability to deploy a UAV relatively quickly and repeatedly at low altitudes. We examine in this paper the potential of using a small UAV for rangeland inventory, assessment and monitoring. Imagery with a ground resolved distance of 8 cm was acquired over a 290 ha site in southwestern Idaho. We developed a semiautomated orthorectification procedure suitable for handling large numbers of small-footprint UAV images. The geometric accuracy of the orthorectified image mosaics ranged from 1.5 m to 2 m. We used object-based hierarchical image analysis to classify imagery of plots measured concurrently on the ground using standard rangeland monitoring procedures. Correlations between imageand ground-based estimates of percent cover resulted in r-squared values ranging from 0.86 to 0.98. Time estimates indicated a greater efficiency for the image-based method compared to ground measurements. The overall classification accuracies for the two image mosaics were 83 percent and 88 percent. Even under the current limitations of operating a UAV in the National Airspace, the results of this study show that UAVs can be used successfully to obtain imagery for rangeland monitoring, and that the remote sensing approach can either complement or replace some ground-based measurements. We discuss details of the UAV mission, image processing and analysis, and accuracy assessment.
Field Tests on Laterally Loaded Rigid Piles in Cement Treated Soils

AbstractA series of laterally loaded pile tests carried out both in natural ground and in cemented treated soil is presented in this paper. The length to diameter ratio L/D of the piles was selected as 5, representing the behavior of a free-headed, short pile that will move as a rigid body in the direction of the applied load without structural damage. The extent of the treated soil layer around the pile ranged from 2–4 times the pile diameter and 0.1–0.3 times the pile length. The treated layer was a mixture of Osorio sand and early strength portland cement. Experimental results show a significant increase in lateral load resistance of short piles when the soil is treated with cement.
Some observations on Assarsson's Z-phase and its structural relations to gyrolite, truscottite, and reyerite

Summary Z-phase was obtained hydrothermally at 120 °C by decomposition of Al-substituted tobermorite and by reaction of lime and colloidal silica. X-ray and electron diffraction show that the structural element is hexagonal, with a 9·65, c 15·3 Å, and good {0001} cleavage. Reversible water loss and lattice shrinkage occur on heating, the layer thickness (c) decreasing to 12.1 Å at 400 °C. For material in equilibrium with air of normal humidity, the composition is probably between CaO. 2SiO2. 1·7H2O and CaO. 2SiO2. 2H2O; Z = 8 for the structural element. New t.g. and infrared absorption data are presented; the infra-red spectrum closely resembles that of gyrolite, but OH ions attached only to Ca appear to be absent. Conditions of formation are discussed; if Z-phase has any stability field, it is below 120 °C. Crystal structures for Z-phase, gyrolite, and truscottite are suggested, based on the known structure of reyerite.
On the radiation budget in regional climate simulations for West Africa

[1] This paper discusses the simulated monthly radiation budget of West Africa by eight regional climate models and the impact of three uncertainty sources in the simulations: cloud fraction, surface albedo, and surface temperature. The models were driven by the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis data within the European Union project ENSEMBLES. The simulated budgets were compared to the satellite-based Global Energy and Water Cycle Experiment Surface Radiation Budget and ERA-Interim data sets. The simulations tended to underestimate the net solar radiation and the outgoing long-wave radiation, and they showed a regionally varying over- or underestimation in all budget components (up to 75%). The evaluation showed that uncertainty in the cloud fraction is the most important of the uncertainty sources over the ocean (with explained error variances between 25% and 60% depending on the budget component averaged over all models). Over land, the surface albedo and surface temperature were, on average, of similar importance as the cloud fraction. The latter result differed from that in a recent study for Europe, indicating that the importance of land surface on the radiation budget is regionally dependent. The relatively simple factor of surface albedo still explains a substantial part of the solar budget error variance in this study: more than 10% over ocean and more than 20% over land, peaking to more than 60% over the Sahelian and Saharan areas. It is worth improving on that in the models, in view of the complexity of other factors like cloud inhomogeneity and direct and indirect aerosol effects.
He and Ne in individual chromite grains from the regolith breccia Ghubara (L5): Exploring the history of the L chondrite parent body regolith

We analyzed He and Ne in chromite grains from the regolith breccia Ghubara (L5), to compare it with He and Ne in sediment‐dispersed extraterrestrial chromite (SEC) grains from mid‐Ordovician sediments. These SEC grains arrived on Earth as micrometeorites in the aftermath of the L chondrite parent body (LCPB) breakup event, 470 Ma ago. A significant fraction of them show prolonged exposure to galactic cosmic rays for up to several 10 Ma. The majority of the cosmogenic noble gases in these grains were probably acquired in the regolith of the LCPB (Meier et al. ). Ghubara, an L chondritic regolith breccia with an Ar‐Ar shock age of 470 Ma, is a sample of that regolith. We find cosmic‐ray exposure ages of up to several 10 Ma in some Ghubara chromite grains, confirming for the first time that individual chromite grains with such high exposure ages indeed existed in the LCPB regolith, and that the >10 Ma cosmic‐ray exposure ages found in recent micrometeorites are thus not necessarily indicative of an origin in the Kuiper Belt. Some Ghubara chromite grains show much lower concentrations of cosmogenic He and Ne, indicating that the 4π (last‐stage) exposure age of the Ghubara meteoroid lasted only 4–6 Ma. This exposure age is considerably shorter than the 15–20 Ma suggested before from bulk analyses, indicating that bulk samples have seen regolith pre‐exposure as well. The shorter last‐stage exposure age probably links Ghubara to a small peak of 40Ar‐poor L5 chondrites of the same exposure age. Furthermore, and quite unexpectedly, we find a Ne component similar to presolar Ne‐HL in the chromite grains, perhaps indicating that some presolar Ne can be preserved even in meteorites of petrologic type 5.
Prediction of hydrological drought durations based on Markov chains: case of the Canadian prairies

Abstract Hydrological drought durations (lengths) in the Canadian prairies were modelled using the standardized hydrological index (SHI) sequences derived from the streamflow series at annual, monthly and weekly time scales. The rivers chosen for the study present high levels of persistence (as indicated by values exceeding 0.95 for lag-1 autocorrelation in weekly SHI sequences), because they encompass large catchment areas (2210–119 000 km2) and traverse, or originate in, lakes. For such rivers, Markov chain models were found to be simple and efficient tools for predicting the drought duration (year, month, or week) based on annual, monthly and weekly SHI sequences. The prediction of drought durations was accomplished at threshold levels corresponding to median flow (Q50) (drought probability, q = 0.5) to Q95 (drought probability, q = 0.05) exceedence levels in the SHI sequences. The first-order Markov chain or the random model was found to be acceptable for the prediction of annual drought lengths, based on the Hazen plotting position formula for exceedence probability, because of the small sample size of annual streamflows. On monthly and weekly time scales, the second-order Markov chain model was found to be satisfactory using the Weibull plotting position formula for exceedence probability. The crucial element in modelling drought lengths is the reliable estimation of parameters (conditional probabilities) of the first- and second-order persistence, which were estimated using the notions implicit in the discrete autoregressive moving average class of models. The variance of drought durations is of particular significance, because it plays a crucial role in the accurate estimation of persistence parameters. Although, the counting method of the estimation of persistence parameters was found to be unsatisfactory, it proved useful in setting the initial values and also in subsequent adjustment of the variance-based estimates of persistence parameters. At low threshold levels corresponding to q < 0.20, even the first-order Markov chain can be construed as a satisfactory model for predicting drought durations based on monthly and weekly SHI sequences. Editor D. Koutsoyiannis; Associate editor C. Onof Citation Sharma, T.C. and Panu, U.S., 2012. Prediction of hydrological drought durations based on Markov chains in the Canadian prairies. Hydrological Sciences Journal, 57 (4), 705–722.
Present and future variations in Antarctic firn air content

A firn densification model (FDM) is used to assess spatial and temporal (1979–2200) variations in the depth, density and temperature of the firn layer covering the Antarctic ice sheet (AIS). A time-dependent version of the FDM is compared to more commonly used steady-state FDM results. Although the average AIS firn air content (FAC) of both models is similar (22.5 m), large spatial differences are found: in the ice-sheet interior, the steady-state model underestimates the FAC by up to 2 m, while the FAC is overestimated by 5–15 m along the ice-sheet margins, due to significant surface melt. Applying the steady-state FAC values to convert surface elevation to ice thickness (i.e., assuming flotation at the grounding line) potentially results in an underestimation of ice discharge at the grounding line, and hence an underestimation of current AIS mass loss by 23.5% (or 16.7 Gt yr −1 ) with regard to the reconciled estimate over the period 1992–2011. The timing of the measurement is also important, as temporal FAC variations of 1–2 m are simulated within the 33 yr period (1979–2012). Until 2200, the Antarctic FAC is projected to change due to a combination of increasing accumulation, temperature, and surface melt. The latter two result in a decrease of FAC, due to (i) more refrozen meltwater, (ii) a higher densification rate, and (iii) a faster firn-to-ice transition at the bottom of the firn layer. These effects are, however, more than compensated for by increasing snowfall, leading to a 4–14% increase in FAC. Only in melt-affected regions, future FAC is simulated to decrease, with the largest changes (−50 to −80%) on the ice shelves in the Antarctic Peninsula and Dronning Maud Land. Integrated over the AIS, the increase in precipitation results in a similar volume increase due to ice and air (both ~150 km 3 yr −1 until 2100). Combined, this volume increase is equivalent to a surface elevation change of +2.1 cm yr −1 , which shows that variations in firn depth remain important to consider in future mass balance studies using satellite altimetry.
Macheridians from the upper Wenlock (Silurian) of Gotland

Machaeridians, enigmatic animals widespread in Palaeozoic strata, have been known for approximately 130 years but nevertheless remain a little studied and problematical group. Two species of machaeridians (Lepidocoleus sp. A and Turrilepas sp. A) from the
GOTIC2: A Program for Computation of Oceanic Tidal Loading Effect

Oceanic tidal loading signals are in general smaller than solid Earth tide signals, but they can be measured by geodetic technique and need to be accurately corrected for because they are in general a source of noise. In order to meet this requirement we have developed a program to compute the loading tide most accurately in Japanese region by using a combination of global and regional ocean tide models and fine-scale land-sea grids. The program computes six kinds of loading (radial and horizontal displacements, gravity, tilt, strain, and deflection of the vertical) for 21 constituents including long-period tide.
Micropaleontology across the Precambrian—Cambrian boundary in Spitsbergen

Paleobiological studies of early metazoan evolution are critically dependent on the accurate stratigraphic subdivision and correlation of uppermost Proterozoic and Lower Cambrian sequences. Planktonic microfossils evolved rapidly during this period and are widely distributed and abundant in Vendian and Lower Cambrian rocks; therefore, they provide what is potentially one of the best means of correlating successions of this age. In Ny Friesland, Spitsbergen, tillite-bearing detrital rocks of the uppermost Proterozoic Polarisbreen Group are overlain without apparent unconformity by the Tokammane Formation, a tripartite lithologic sequence consisting of quartzarenites (Blårevbreen Member) overlain by dark shales with subordinate sandstone (Topiggane Member) and dolomites (Ditlovtoppen Member). Salterella, hyoliths, and other invertebrate remains occur in the upper part of the Tokammane succession; trace fossils are found in the Tokammane quartzarenites and shales, as well as in the uppermost few meters of the Polarisbreen sequence. Planktonic microfossils occur throughout the succession. They indicate that the Polarisbreen Group is Vendian in age and that a hiatus corresponding in time to the latest Vendian and (perhaps) earliest Cambrian coincides with the Polarisbreen/Tokammane boundary. Lower Topiggane shale samples contain acritarchs comparable to those found in the sub-Holmia Lontova Beds of Eastern Europe. Upper Topiggane samples contain diverse acritarch assemblages that indicate a late Holmia or Protolenus age, suggesting the presence of a second hiatus within the Tokammane Formation. Planktonic microfossils allow biostratigraphic correlation with other sequences both within (East Greenland) and between (East European Platform) paleocontinents. Like those from other areas, diversity trends exhibited by late Proterozoic and Early Cambrian acritarchs from Spitsbergen indicate a major Vendian episode of extinction followed by Early Cambrian rediversification of planktonic microfossils.
An introduction to marine biogeochemistry

Partial table of contents:. THE PHYSICAL CHEMISTRY OF SEAWATER. The Crustal-Ocean Factory. The Waters of the Sea. Salinity as a Conservative Tracer. Gas Solubility and Exchange Across the Air-Sea Interface. THE REDOX CHEMISTRY OF SEAWATER. The Importance of Oxygen. Vertical Segregation of the Biolimiting Elements. Horizontal Segregation of the Biolimiting Elements. Trace Metals in Seawater. THE CHEMISTRY OF MARINE SEDIMENTS. Classification of Sediments. Calcite, Alkalinity, and the pH of Seawater. Biogenic Silica. Iron-Manganese Nodules and Other Hydrogenous Minerals. ORGANIC BIOGEOCHEMISTRY. The Production and Destruction of Organic Compounds in the Sea. The Marine Nitrogen Cycle. The Marine Carbon Cycle and the Carbon Dioxide Problem. The Origin of Petroleum in the Marine Environment. ISOTOPE GEOCHEMISTRY. Measuring Rates and Dates: The Use of Radioisotopes in the Study of Marine Processes. Reading the Sedimentary Record: The Use of Stable Isotopes in the Study of Paleoceanography. MARINE POLLUTION. The Fate of Pollutants in the Coastal Ocean. Appendices. Glossary. Index.
Lithospheric stress near a ridge‐transform intersection

Oceanic lithosphere at a ridge-transform intersection has distinct structural characteristics. The spreading axis and normal fault scarps, which parallel the ridge axis away from the intersection, locally curve towards the transform fault. This implies that the least compressive stress direction becomes oblique to the spreading direction near a ridge-transform intersection. This stress field may be the result of a tensile ridge axis stress resisting plate separation and a transform shear stress resisting relative plate motion. A plane stress plate model with prescribed plate boundary stresses is formulated to explore this hypothesis. The orientation of the least compressive horizontal stress near an intersection depends strongly on the ratio of the applied boundary stresses. Thus ridge axis curvature may place an important constraint on plate boundary forces.