Miracle-dz/UniFAR-FTUs huggingface dataset:
Glacial erosion beneath ice streams and ice‐stream tributaries: constraints on temporal and spatial distribution of erosion from numerical simulations of a West Antarctic ice stream

Geologic evidence such as subglacial troughs and grounding zone wedges indicate that soft‐bedded, West Antarctic ice streams are capable of eroding, transporting and depositing large volumes of debris at high rates (˜100 m3 yr‐1 per meter width). In order to understand the dynamics of ice streams and the geologic effects of their activity, it is important to understand the physical mechanisms that control these high rates of sub‐ice‐stream sediment generation and transport. Here, we use a numerical model of Ice Stream C run over c. 8500 model years to quantify the effects of a recently proposed, till‐ploughing mechanism of till formation and redistribution beneath ice streams (Tulaczyk et al. 2001; Clark et al. in press). Our results show that this ‘transport‐limited’ mechanism, in which till transport rates scale with ice velocity and erosion rates with spatial gradients of velocity, is consistent with existing constraints. For instance, our model results predict significantly higher (˜0.6 mm yr‐1) average erosion rates beneath ice‐stream tributaries, which are underlain by deep subglacial troughs, than beneath ice‐stream trunks (˜0.2mm yr‐1), whose subglacial troughs have a significantly smaller relief. We would not obtain this satisfactory result if subglacial erosion was parametrized in the model using the more traditional approach of scaling erosion rates with ice velocity (what we call the ‘production‐limited’ parametrization). Because of the requirement of ice continuity, the magnitude of ice velocity generally increases downstream in polar ice streams, and so do the production‐limited erosion rates. Pending further investigations, we propose that geologic and geomorphic effects of soft‐bedded ice streams should be quantified using some form of a ‘transport‐limited’ parametrization of subglacial erosion rates, e.g. the till‐ploughing mechanism.
Atmospheric chemistry of small organic peroxy radicals

Global atmospheric models play a key role in international assessments of the human impact on global climate and air pollution. To increase the accuracy and facilitate comparison of results from such models, it is essential they contain up-to-date chemical mechanisms. To this end, we present an evaluation of the atmospheric chemistry of the four most abundant organic peroxy radicals: CH3O2, C2H5O2, CH3C(O)O2, and CH3C(O)CH2O2. The literature data for the atmospheric reactions of these radicals are evaluated. In addition, the ultraviolet absorption cross sections for the above radicals and for HO2 have been evaluated. The absorption spectra were fitted to an analytical formula, which enabled published spectra to be screened objectively. Published kinetic and product data were reinterpreted, or in some case reanalyzed, using the new cross sections, leading to a self-consistent set of kinetic, mechanistic, and spectroscopic data. Product studies were also evaluated. A set of peroxy radical reaction rate coefficients and products are recommended for use in atmospheric modeling. A three-dimensional global chemical transport model (the Intermediate Model for the Global Evolution of Species, IMAGES) was run using both previously recommended rate coefficients and the current set to highlight the sensitivity of key atmospheric trace species to the peroxy radical chemistry used in the model.
Determination of sea ice parameters with the NIMBUS 7 SMMR

A method of determining sea ice parameters using dual-polarized multispectral radiance data obtained with the NIMBUS 7 Scanning Multichannel Microwave Radiometer (SMMR) is presented. Sea ice concentration is determined both at a 60-km resolution from the polarization at the 1.7-cm wavelength and at a 30-km resolution using the polarization at the 0.81-cm wavelength. Multiyear sea ice fraction is obtained from the spectral gradient ratio, which is the difference of the 0.81 cm and the 1.7 cm vertically polarized radiances divided by their sum. In addition, an ice temperature is calculated from the 4.6-cm vertical channel radiances. The use of radiance ratios greatly reduces uncertainties in the derived parameters resulting from temporal and horizontal spatial variations of ice temperature. Observed SMMR radiances from selected areas in the Arctic region for the period February 3–7, 1979, are used in computing algorithm coefficients. Polar maps of sea ice concentration, multiyear fraction, and ice temperature are illustrated for this period. The variation of the mean and standard deviation of ice concentration and multiyear ice fraction for a region of perennial ice cover over the first 11 months of SMMR operation is also presented. The standard deviation about the mean for the computed concentration varies from 2 to 5% over the 11-month period, while that of the multiyear fraction is about 8% for all but the summer months. Discrimination between first-year and multiyear sea ice during the summer period is indeterminate largely because the general surface melt conditions mask the distinguishing properties of the two ice types. Based on the time variation of ice concentration and multiyear fraction for the central Arctic region and on an analysis of histograms of these parameters, the precision of the calculated ice concentration is estimated to be in the range of 5–9% and that of the multiyear fraction in the range of 13–25%. Comparisons are made between the calculated sea ice parameters and information obtained from previous studies using aircraft, submarine, and surface observations. From these comparisons it is concluded that the absolute accuracy of the SMMR parameters remains uncertain. The precision of the sea ice concentration is sufficient to provide useful data on the large-scale polar ice cover, but further study is required to increase the confidence in the multiyear ice fraction which at present contains significant uncertainties.
Enigmatic Structures in an Upper Pennsylvanian (Kasimovian) Marine Limestone

Abstract Enigmatic structures in the shape of inverted rounded cones are very common in a discrete horizon of the upper Stoner Limestone Member (Stanton Limestone Formation, Lansing Group, Upper Pennsylvanian) in southeastern Nebraska. These structures are 100–300 mm in diameter, but rare, very large examples attain 1300 mm in diameter. On bedding planes, individual structures are conspicuously expressed as groups of concentric rings, some of which appear as low ridges (rugae). At least some of these rings correspond to concentric cone sheets (hollow cones) extending downward into the rock mass; these cone sheets are sometimes separated clearly from each other by discontinuous mud linings or drapes. The largest structures usually have smaller ones nested within them. The Stoner Limestone structures differ from described types of nonbiological and biological conelike structures, yet they must have formed in soft sediment prior to burial. Although they have a superficial similarity to such plug-shaped trace fossils as Conichnus and Conostichus, the purported dwelling traces left by cnidarians, several salient points with respect to shape, structure, and occurrence distinguish the Stoner Limestone structures from such traces. A trace-fossil hypothesis for the origin of the structures remains plausible—possible feeding structures—albeit problematic. Study of the Stoner Limestone concentric-conelike structures indicates that careful reexamination of trace fossils and sedimentary structures in Midconinent Pennsylvanian limestones is in order, as well as a reconsideration of how unique physical and diagenetic properties of carbonate sediments in general might affect the preservation of such features.
Surface variability effects on the remote sensing of thin cirrus optical and microphysical properties

We have developed a methodology for the retrieval of the optical and microphysical properties of thin cirrus clouds with optical depths less than 0.5 using Moderate Imaging Spectroradiometer (MODIS) Airborne Simulator (MAS) measurements conducted during the Subsonic Aircraft Cloud and Contrail Special Study (SUCCESS). This methodology involves the use of correlated reflectance at three channels (0.65, 1.6, and 2.2 μm). We demonstrate the necessity of employing accurate values of the upwelling cloud base reflectance fields and present a method for the computation of these fields based on the atmospheric correction approach. For ocean surfaces the anisotropic reflectance is atmospherically corrected using appropriate radiative transfer calculations, along with the retrieved aerosol optical depths based on a simple aerosol microphysical model. For land surfaces a mosaic of ecosystems is used to compute the anisotropic reflectance associated with the surface terrain variability. We show that using these explicit computations of the emerging cloud base reflectance, thin cirrus optical depths and ice crystal size over ocean surfaces can be retrieved accurately. Uncertainties in the retrieved optical depth and ice crystal size are further reduced by 20 and 45%, respectively, over complex land surfaces.
Anisotropic processing of 4‐C sea‐bed seismic data: A case example from West Africa

Anisotropic processing is performed on a 4C dataset to determine whether it can improve the original converted wave stack. This is achieved by firstly processing the P-P wave for estimates of Vnmo and an additional parameter η which indicates the presence of anisotropy. The converted wave processing is then achieved by adapting the isotropic double-square-root (DSR) equation for P-S move-out. The ratio of the RMS velocities for P and S wave is estimated as the semblance parameter. The final P-S section has a better quality than the one provided by the contractor, although the technique remains limited by the extent to which a correlation can be defined between the P-S section and P-P section. The anisotropic DSR equation is also applied to the data. By using the relation ε=2δ followed by a double scanning over σ and γn, γ0 can be estimated. This analysis reveals the presence of a TIV anisotropy of up to 25%. Finally, the analytically derived γ0 serves as a guide to determine a correlation between the P-P and P-S section.
SIMMAX : a modern analog technique to deduce Atlantic Sea Surface Temperatures from planktonic foraminifera in deep sea sediments

We present a data set of 738 planktonic foraminiferal species counts from sediment surface samples of the eastern North Atlantic and the South Atlantic between 87°N and 40°S, 35°E and 60°W including published Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) data. These species counts are linked to Levitus's [1982] modern water temperature data for the four caloric seasons, four depth ranges (0, 30, 50, and 75 m), and the combined means of those depth ranges. The relation between planktonic foraminiferal assemblages and sea surface temperature (SST) data is estimated using the newly developed SIMMAX technique, which is an acronym for a modern analog technique (MAT) with a similarity index, based on (1) the scalar product of the normalized faunal percentages and (2) a weighting procedure of the modern analog's SSTs according to the inverse geographical distances of the most similar samples. Compared to the classical CLIMAP transfer technique and conventional MAT techniques, SIMMAX provides a more confident reconstruction of paleo-SSTs (correlation coefficient is 0.994 for the caloric winter and 0.993 for caloric summer). The standard deviation of the residuals is 0.90°C for caloric winter and 0.96°C for caloric summer at 0-m water depth. The SST estimates reach optimum stability (standard deviation of the residuals is 0.88°C) at the average 0– to 75-m water depth. Our extensive database provides SST estimates over a range of −1.4 to 27.2°C for caloric winter and 0.4 to 28.6°C for caloric summer, allowing SST estimates which are especially valuable for the high-latitude Atlantic during glacial times. An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU. ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username and GUESTas the password. Go to the right directory by typing CD APPEND. TypeLS to see what files are available. Type GET and the name of the file toget it. Finally type EXIT to leave the system.) (Paper 95PA01743,SIMMAX: A modern analog technique to deduce Atlantic sea surfacetemperatures from planktonic foraminifera in deep-sea sediments, UwePflaumann, Josette Duprat, Claude Pujol, and Laurent D. Labeyrie). Diskette may be ordered from American Geophysical Union, 2000Florida Avenue, N.W. , Washington, DC 20009; Payment mustaccompany order.
Soil organic carbon after long-term fertiliser N and P applications

Soil organic carbon (SOC) was measured at two depths where fertiliser nitrogen (N) and phosphorus (P) combinations had been applied to a long-term experiment after 16 years in north-eastern Australia. An opportunity cropping regime of grain sorghum and wheat or barley following a range of fallow lengths was used. With N fertiliser application, SOC in 0.0-0.1m was 0.84 Mg/ha higher than in nil N plots, whilst fertiliser P treated soil was 0.40 Mg/ha higher compared to no P application. From 0.1-0.3 m, neither fertiliser N or P was statistically significant. For the sum of SOC to 0.3 m depth, N treatment only was significant. Cumulative estimates of stover and below-ground carbon input were estimated from harvested grain yields. Fertiliser N increased estimated C input in 8 of 14 years; the largest responses in grain sorghum sown on short fallows ( � 6 months). There was little or no N fertiliser effect on sorghum yield or C input following long-fallow ( � 14 months). For winter cereal crops, P fertiliser increased estimated C input over all fallow lengths, whilst responses to N fertiliser were influenced by fallow-length. Cumulatively, the interaction between fertiliser N and P significantly increased estimated stover and below-ground C input.
Holocene chemical weathering and climatic oscillations in north China: evidence from lacustrine sediments

Holocene lacustrine sediments from two isolated lakes in north China are investigated. Based on palaeoclimatic significance of independent proxies in lake sediments, Holocene chemical weathering, and hence climate change, has been reconstructed for dated sediment cores from Daihai Lake and Aibi Lake. During early to mid‐Holocene, higher weathering intensity occurred in the Daihai catchment under warm and humid climate conditions, and this reached a maximum at ˜5 kyr BP. However, synchronous proxy shifts from the two widely separated, isolated lake sediments indicate that there was a cool climate event during the early to mid‐Holocene transition. This is characterized by reduced weathering in each catchment, low δ13 C and δ18O of authigenic carbonate, and by lake level fluctuations. These might correspond to a global cooling signal identified in lakes, oceans, mollusc sequences, and polar ice cores, typically centred between ˜8.0 and 8.5 kyr BP. Dry conditions were experienced in Greenland, the North Atlantic and surrounding regions, and in broad monsoonal regions including Daihai at this time. However, recent extensive evidences as well as our data from the Aibi Lake sediments show that cool but wet conditions occurred in the central Eurasian continent at this time. After ˜2.5 kyr BP, a significant shift of independent sediment proxies indicates the beginning of the Neoglaciation with a higher frequency of fluctuations, including both the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Our continental records provide new evidence of the Holocene climate variability with global significance and highlight the different spatial nature of the response to oscillations associated with different climate patterns.
Exposure to HAP and the Regional Pattern of Air-Related Morbidity in India: A Multivariate Analysis

This paper attempts to analyse the nature of relationship between the levels of Household Air Pollution (HAP) and incidence of morbidity in urban India along with the pattern of its regional variations. It also explores the causal connection between the incidence of air-related diseases and HAP, giving control for outdoor pollution. Whether these effects are sensitive to the overall level of economic development is an issue of our interest. Therefore, the States/UTs of India are grouped, in terms of different developmental parameters, using Multidimensional Scaling and Clustering technique, and the relation between HAP and morbidity has been analysed for each group of states by applying stepwise regression techniques. The study of this heterogeneity helped us provide more focused policy prescriptions. Different policy prescriptions in terms of education as well as exposure to HAP and fuel choices have been suggested for different clusters.
Cultural heritage and tourism in the developing world: a regional perspective

Tourism development in the developing world has been a focus of study by tourism scholars for some time. While considerations of cultural heritage and tourism in this area of the world have been touched upon (e.g. Brohman, 1996; Kirshenblatt-Gimblett, 1998; McKercher & Du Cros, 2002; Teo & Huang, 1995; Tuan & Navrud, 2007), this book is one of the first to look comprehensively at cultural heritage tourism development in the developing world. The purpose of this book, according to the editors, is to ‘provide conceptual overviews of critical issues, challenges, and opportunities in the heritage tourism context in developing regions’ (p. xiv). To achieve this goal, the editors divide the book into two sections. Section 1, entitled ‘Heritage Issues and Challenges in Developing Regions’, is written by the editors and encompasses four chapters. In Chapter 1, the reader is introduced to heritage and tourism in the developing world, with the editors focusing on the types of heritage tourism supply and products available in less-developed nations, as well as other heritage tourism-related trends such as the role of UNESCO in preserving heritage sites in the developing world. In Chapter 2, the focus is on the challenges and threats in preserving heritage tourism in the developing world. Chapter 3 examines the politics of heritage preservation in this area of the world and particularly focuses on the role that heritage plays in maintaining the instable political status quo. Chapter 4 looks at the physical, social and environmental impacts of heritage tourism on destinations in the developed world. Section II, entitled ‘Heritage Issues and Challenges: Regional Perspectives’, contains nine chapters by the editors and other scholars, who look at challenges to heritage tourism development in different regions of the developing world. In Chapter 5, Joan Henderson reviews the different types of, and issues related to, heritage tourism in Southeast Asia. In Chapter 6, Dallen Timothy, Bihu Wu and Oyunchimeg Luvsandavaajav look at heritage tourism in East Asia, focusing particularly on North Korea and Mongolia. Chapter 7, written by Michael Hall, examines heritage tourism in the Pacific and discusses the issues of how the Pacific is represented or ‘exoticized’. Gyan Nyaupane and Megha Budruk turn to South Asia in their discussion of issues and opportunities related to heritage tourism development in Chapter 8. In Chapter 9, Dallen Timothy and Rami Daher look at heritage tourism in Southwest Asia and North Africa and highlight the challenges that arise when factoring in religion, war and conflict, and sedimented layers of history and heritage in the region. Victor Teye follows this chapter with a discussion of heritage tourism in Africa, and juxtaposes indigenous and colonial heritage beside issues relating to the African diaspora and heritage. Leslie-Ann Jordan and David Duval next turn the reader’s attention to heritage management and tourism in the Caribbean and, after typologizing
The poleward leap of the auroral electrojet as seen in auroral images

This paper discusses a recently published series of 12 successive images of the northern auroral oval obtained by the University of Iowa's auroral imager on DE 1 during a substorm on November 8, 1981. The images showed a sudden (within <12 min) thickening and poleward expansion of the midnight sector of the oval that occurred at the “maximum epoch” of the substorm, i.e., as auroral zone bays reached their peaks and began to subside about 90 min after the expansive phase onset. We propose that this was the auroral manifestation of the poleward leap of the auroral electrojet that has been reported on many occasions to coincide with thickening of the plasma sheet in the outer magnetotail (beyond ∼15 RE) late in a substorm. The plasma sheet thickening is thought to be associated with a tailward retreat of the substorm magnetic neutral line. We note evidence that the neutral line's tailward retreat influences auroral currents and particle precipitation even at low auroral latitudes. Modifications of the present auroral substorm model are suggested.
Different kinds of mangrove forests provide different goods and services

The goods and services that mangrove forests provide to society are widely understood but may be too generally stated to serve as useful guidelines in decision-making. Understanding the differences between fringe, riverine, and basin forests may help to focus these guidelines and to determine the best use of a particular forest. Fringe mangroves are important primarily for shoreline protection. Riverine forests, which are likely to be the most productive of the three types of forests, are particularly important to animal and plant productivity, perhaps because of high nutrient concentrations associated with sediment trapping. Basin forests serve as nutrient sinks for both natural and anthropogenically enhanced ecosystem processes and are often important sources of wood products. Exploitation of a forest for one particular reason may make it incapable of providing other goods and services.
North Siberian Lakes: A Methane Source Fueled by Pleistocene Carbon

The sizes of major sources and sinks of atmospheric methane (CH4), an important greenhouse gas, are poorly known. CH4 from north Siberian lakes contributes ∼1.5 teragrams CH4 year−1 to observed winter increases in atmospheric CH4 concentration at high northern latitudes. CH4 emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon.
An extended riparian buffer strip concept for soil conservation and stream protection in an agricultural riverine area of the La Chevrotière River watershed, Québec, Canada, using remote sensing and GIS techniques

The implementation of riparian buffer strips in agricultural areas is regarded as a means to protect watercourses against runoff water carrying sediments and contaminants. In the field, riparian buffers are usually dimensioned to meet the minimum width required by policies and regulations. In the case of the province of Québec, Canada, regulation stipulates a width of 1–3 m in agricultural watersheds. However, such small riparian strips offer little protection, especially during the spring-snowmelt period when the soil is saturated, infiltration is low, vegetative cover is poor and soil erosion and runoff are the dominant hydrological processes. In this study, high-resolution, remote sensing, raster-based information is used to evaluate an extended riparian buffer strip concept with variable widths of 5–120 m to assess soil erosion and to convert agricultural riverine areas into soil and water conservation areas. For a studied watershed of 108 km2 in Québec, this would enable reducing soil erosion in riverine areas from 361 to 1.0 t year−1 (1.9 to 0.005 t ha−1 year−1), and thereby reducing soil erosion at the watershed scale by 40% (calculated with the Revised Universal Soil Loss Equation, RUSLE). The extended riparian buffer strip concept would require the conversion of 7% of the 29 km2 of agricultural land.