Miracle-dz/UniFAR-FTUs huggingface dataset:
Drakensberg basalts: their alteration, breakdown and durability

Abstract The basalts of the Drakensberg Formation consist of a succession of lava flows which total some 1400m in thickness. Many of the lava flows are characterized by amygdaloidal zones. Many of the primary minerals within the basalts have been subjected to varying degrees of deuteric alteration which has led to the formation of clay, and chlorite and zeolite to a lesser extent. Some interstitial glass has also broken down to form clay. These secondary minerals, together with zeolites which occur notably as amygdaloidal fillings, mean that many of the basalts break down rapidly on exposure. The breakdown results principally from the expansion which occurs when the clay minerals swell on absorption of water. This gives rise to crazing. The mineral content of the basalts was determined by modal analysis and X-ray diffraction. In addition, methylene blue adsorption was used to estimate the clay content. The secondary mineral rating was determined primarily from the modal analyses. Soak tests and free swell tests using ethylene glycol and water; water absorption, wet and dry, and freeze- thaw tests were carded out to assess the durability of these basalts. The olivine basalts and those types which contained disseminated clay spots were the least durable, some breaking down rapidly on testing. This was caused mainly by the expansion of clay minerals. Water absorption was also influenced by the presence of zeolites, notably laumontite. Another factor which has to be taken into account in relation to break down and durability is texture since this can restrict access of water to swelling minerals.
Small-scale features in the Earth's magnetic field observed by Magsat.

A spherical harmonic expansion to degree and order 29 is derived using a selected magnetically quiet sample of Magsat data. Global maps representing the contribution due to terms of the expansion above n = 13 at 400 km altitude are compared with previously published residual anomaly maps and shown to be similar, even in polar regions. An expansion with such a high degree and order displays all but the sharpest features seen by the satellite and gives a more consistent picture of the high-order field structure at a constant altitude than do component maps derived independently. The appendix is available with the entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W. , Washington, DC 20009. Document B83-008; $2.50. Payment must accompany order.
New heterodontosaurid specimens from the Lower Jurassic of southern Africa and the early ornithischian dinosaur radiation

ABSTRACT Heterodontosaurids are poorly understood early ornithischian dinosaurs with extensive geographic and stratigraphic ranges. The group is best known from the Lower Jurassic upper ‘Stormberg Group’ (upper Elliot and Clarens formations) of southern Africa, previously represented by at least three distinct species and ten described specimens. This paper describes four additional heterodontosaurid specimens from southern Africa. A partial skull of a large individual of Heterodontosaurus tucki (NM QR 1788) is approximately 70 longer than that of the type specimen of Heterodontosaurus, and provides new information on allometric changes in mandibular morphology during growth in this taxon. It is the largest known heterodontosaurid cranial specimen, representing an individual approximately 1·75 metres in length, and perhaps 10 kg in body mass. NHMUK R14161 is a partial skull that appears to differ from all other heterodontosaurids on the basis of the proportions of the dentaries, and may represent an unnamed new taxon. Two additional partial skulls (NHMUK RU C68, NHMUK RU69) are referred to cf. Lycorhinus. At least four, and possibly five or more, heterodontosaurid species are present in the upper ‘Stormberg’. This high diversity may have been achieved by dietary niche partitioning, and suggests an adaptive radiation of small-bodied ornithischians following the end Triassic extinctions.
Application of high‐performance anion‐exchange chromatography–pulsed amperometric detection for measuring carbohydrates in routine daily filter samples collected by a national network: 2. Examination of sugar alcohols/polyols, sugars, and anhydrosugars in the upper Midwest

[1] Carbohydrate measurements of ambient samples can provide insights into the biogenic fraction of the organic carbon (OC) aerosol. However, lack of measurement on a routine basis limits data analysis. In a companion paper, 1 year of archived 1-in-6 day FRM (Federal Reference Monitor) filter samples from the PM2.5 NAAQS compliance monitoring network collected at 10 sites in the upper Midwest were analyzed using high-performance anion-exchange chromatography with pulsed amperometric detection to determine the regional impact of biomass burning. Along with levoglucosan, 13 other carbohydrates were simultaneously measured, including two more anhydrosugars (mannosan and galactosan), five sugars (arabinose, galactose, glucose, mannose, xylose), and six sugar alcohols/polyols (glycerol, methyltetrols, threitol/erythritol, xylitol, sorbitol, mannitol). This paper focuses on the results from these carbohydrates in order to investigate their sources and trends both spatially and temporally. Mannosan, galactosan, arabinose, xylose, and threitol/erythritol all correlated with levoglucosan (R2 from 0.43 to 0.97), suggesting biomass burning as their main source. Glucose and mannitol exhibited higher concentrations in summer and at more southern sites, likely due to vegetation differences at the sites. Using mannitol, the contribution of spores to OC was found to be <1%. Methyltetrols were highly correlated with water-soluble OC (R2 from 0.63 to 0.95) and in higher concentrations at more eastern sites. This spatial pattern is possibly due to these sites being downwind of the high isoprene emission zones that occur in the western part of the Midwest from oak forests in the Ozarks and spruce forests in the northern lake states.
Oceanic consumption of CH3CCl3: Implications for tropospheric OH

Strong and extensive negative saturation anomalies for CH3CCl3 were observed in the mid-Pacific Ocean during the spring of 1990. Anomalies were largest at the equator, where upwelling and biological activity were greatest, but present virtually everywhere in our sampling range of 15°S to 20°N. The mean saturation anomaly for all of our data, corrected for physical effects, was −11.0%, implying that the ocean is a significant sink for CH3CCl3. The loss rate to maintain this anomaly is supported roughly by known hydrolysis rates, but contributions from other processes cannot be ruled out at this time. If hydrolysis and mixing are the only processes removing CH3CCl3 from seawater, then about 6% of atmospheric CH3CCl3 is removed by consumption in the oceans. Our data show that losses to the ocean most probably would range from 5 to 11% of the CH3CCl3 removed from the atmosphere. This range translates to a partial residence time of 59–128 years for atmospheric CH3CCl3 relative to oceanic consumption. Although these data indicate that the ocean is not an overwhelmingly large sink, its neglect does represent a systematic error in the calculation of tropospheric OH concentration from CH3CCl3 production, growth, and distribution in the atmosphere.
Synoptic storms and the development of the 1997 warming and freshening event in the Beaufort Sea

The climatic state in the Beaufort Sea in 1997 was characterized by warmer atmosphere, smaller areal coverage of sea ice in summer than average, and an oceanic mixed layer with a relatively low salinity that persisted into fall and and early winter. The most remarkable change occurred near the end of 1997 when both salinity and temperature in the upper layer varied dramatically in a short‐time period. The evolution of the air‐sea‐ice condition was observed by an autonomous buoy. The buoy observation revealed that deep mixing that penetrated through the Arctic halocline occurred in response to enhanced wind‐stress forcing associated with an intense storm and was mainly responsible for the abrupt change of temperature and salinity in the mixed layer near the end of 1997. Similar events were inferred from storms in the Eurasian basin in 1994. We postulate that synoptic storms plays a very important role in the variations of the heat and salt budgets in the upper Arctic Ocean.
Laboratory Velocity Measurements Used for Recovering Soil Distributions from Field Seismic Data

Recent advances in field methods make it possible to obtain high quality compressional (P) and shear (S) velocity data for the shallow subsurface. Environmental and engineering problems require new methods for interpreting the velocity data in terms of sub-surface soil distribution. Recent advances in laboratory measurement techniques have provided high quality velocity data for soils at low pressures that can be used to improve interpretation of field data. We show how laboratory data can be used to infer lithology from field data. We use laboratory ultrasonic velocity measurements from artificial soils made by combining various amounts of sand and peat moss.
Experimental investigation of drag coefficients of gobi surfaces

The response of gobi surfaces to the near-surface air flow can be characterized quantitatively by drag coefficients. By using wind tunnel tests, an attempt is made to define the relationship between the drag coefficients of gobi surfaces and gravel size and coverage. It is concluded that the drag coefficients of gobi surfaces tend to be constants when gravel coverage is over 40%-50%. Consequently, we think that the gobi deflation planes expanding vastly in the arid Northwestern China are aerodynamically stable, at least not the supplying sources of current dust storms, and therefore the emphasis on dust storm control should be paid on the so-called “earth gobi” that has low gravel coverage. The prediction model for drag coefficients of gobi surfaces has been developed by regressing drag coefficients on gravel size and coverage, the predicted results are in reasonably good agreement with wind tunnel results (R2= 0.94). The change of drag coefficients with gravel friction Reynolds number implies that the development extent of drag effect increases with gravel size and coverage.
SPECTRAL STUDIES OF MARINE GEOPHYSICAL PROFILES

Gravity, magnetic, and echo‐sounding data profiles from widely separated single‐track surveys in the Atlantic and Indian Oceans were subjected to spectral studies. A two‐dimensional sea floor with a recurring structural pattern seemed a model able to explain the computed results. In testing the model, the most important quantity to be determined from the spectra was the “ripple frequency” or interpeak interval. During the course of this work, a number of practical problems connected with the computation of spectra were considered. In addition, the spectral methods were also shown to be tools capable of investigating more complex geophysical theories. The experience and techniques of this investigation can be of value in treating analogous problems which arise in geophysical exploration.
Hydrochemistry of shallow groundwater and surface water in the Ndop plain, North West Cameroon

This study was conducted on the hydrochemistry of shallow groundwater and surface water in the Ndop plain, North West Cameroon. The objectives were to determine the physico-chemical characteristics of water, controls on water chemistry and suitability for drinking and irrigation. Forty-six shallow groundwater and 26 surface water samples were investigated. Field measurements of physical parameters were preceded by chemical analyses of the samples for major ions and F-. About 69% of the water sources had pH values below 6.5, classifying the water as barely acidic. Electrical conductivity ( Ca 2+ >Mg 2+ >K + for cations and HCO 3 - >>NO 3 -≥ Cl - >SO 4 2- for anions. Major ion concentrations were low, and within the WHO guidelines for drinking water, but F- concentrations were much lower (<0.39 mg/l) and below guideline value. Main water types and proportions were Na-HCO 3 (53 %), Ca-HCO 3 (35 %) and a mixed Na-Ca-HCO 3 (11%). Predominant processes influencing water chemistry were incongruent dissolution of silicate minerals and cation-exchange of Na+ in rocks for Ca 2+ in water. The low major ion concentrations indicated low water-rock interactions and short residence time. The analysed water was suitable for irrigation. Key words : Water chemistry, hydrochemical controls, drinking-irrigation quality, Ndop plain, Cameroon.
Impact of Incorrect Model Error Assumptions on the Sequential Assimilation of Remotely Sensed Surface Soil Moisture

Data assimilation approaches require some type of state forecast error covariance information in order to optimally merge model predictions with observations. The ensemble Kalman filter (EnKF) dynamically derives such information through a Monte Carlo approach and the introduction of random noise in model states, fluxes, and/or forcing data. However, in land data assimilation, relatively little guidance exists concerning strategies for selecting the appropriate magnitude and/or type of introduced model noise. In addition, little is known about the sensitivity of filter prediction accuracy to (potentially) inappropriate assumptions concerning the source and magnitude of modeling error. Using a series of synthetic identical twin experiments, this analysis explores the consequences of making incorrect assumptions concerning the source and magnitude of model error on the efficiency of assimilating surface soil moisture observations to constrain deeper root-zone soil moisture predictions made by a land surface model. Results suggest that inappropriate model error assumptions can lead to circumstances in which the assimilation of surface soil moisture observations actually degrades the performance of a land surface model (relative to open-loop assimilations that lack a data assimilation component). Prospects for diagnosing such circumstances and adaptively correcting the culpable model error assumptions using filter innovations are discussed. The dual assimilation of both runoff (from streamflow) and surface soil moisture observations appears to offer a more robust assimilation framework where incorrect model error assumptions are more readily diagnosed via filter innovations.
Influence of the Atlantic zonal mode on monsoon depressions in the Bay of Bengal during boreal summer

The influence of the Atlantic Zonal Mode (AZM) or the Atlantic Niño on monsoon depressions in the Bay of Bengal during the boreal summer (June–August) is studied. Our analysis shows that there is a statistically significant difference in the number of monsoon depressions in the Bay of Bengal between the warm and cold phases of the AZM; more (fewer) monsoon depressions form during the cold (warm) phase of AZM. It also shows that there are differences in spatial pattern of trajectories of monsoon depressions; during the cold phase of AZM, the tracks are relatively long and seem to cluster along the axis of core monsoon region compared to the warm phase of AZM. The analysis indicates an increase (a reduction) in low‐level cyclonic vorticity and midtropospheric humidity but a reduction (an increase) in vertical wind shear due to anomalous circulation pattern. All of these changes are favorable for the enhancement (suppression) of monsoon depressions during the cold (warm) phase of the AZM. Our analysis further shows a teleconnection pathway by which the AZM can influence the remote Indian Ocean. This could have implications for enhancing monsoon prediction skill, especially during non‐El Niño–Southern Oscillation years.
Apports des méthodes statistiques et hydrochimiques à la caractérisation des eaux des aquifères fissurés de la région du N’zi-Comoé (Centre-Est de la Côte d’Ivoire)

La region du N’zi-Comoe est situee au Centre-Est de la Cote d’Ivoire et appartient du point de vue geologique au socle cristallin. La vegetation est constituee de lambeaux de foret mesophile, de savanes separees par des forets-galeries et de jacheres, resultat de la deforestation. L’appauvrissement des sols, issu de cette deforestation a eu pour consequence l’utilisation d’engrais. La deforestation et l’usage des engrais suscitent des interrogations sur la qualite des eaux souterraines du N’zi-Comoe et leur aptitude a la consommation humaine. C’est pour repondre a cette problematique que ce present travail a ete initie. Ainsi, l’objectif de cette etude est la caracterisation hydrogeochimique des eaux et l’analyse de leur aptitude a la consommation humaine. Ce travail a ete mene a partir des resultats d’analyses de parametres physicochimiques des eaux et s’est appuye sur un echantillon de 193 forages. La methodologie appliquee est basee sur une approche pluridisciplinaire integrant l’hydrochimie (diagramme triangulaire de piper, indicateur de temps de sejour) et des analyses statistiques univariees, bivariees et multivariees (ACPN). Du point de vue hydrofacies, la majorite des eaux des aquiferes fissures du N’zi-Comoe est du facies bicarbonate calcique et magnesien. La region du N’zi-Comoe est dominee par deux phenomenes hydrochimiques majeurs : la mineralisation couplee au temps de sejour et l’oxydo-reduction qui sont a l’origine de l’acquisition de la mineralisation des eaux souterraines du N’zi-Comoe. L’etude de la potabilite revele que les eaux souterraines sont physico-chimiquement conformes dans l’ensemble aux normes recommandees par l’OMS et ne presentent pas de danger majeur pour la consommation humaine.
A hydromechanical relation governing internal stability of cohesionless soil

Results are presented from permeameter tests involving unidirectional seepage flow through reconstituted speci- mens of four widely graded cohesionless soils. The onset of instability is defined by a significant decrease in local hy- draulic gradient over a relatively short period of time. The novel concept of a hydromechanical path in stress (s 0 )- gradient (ijk) space is proposed, which describes the response to seepage flow during testing and terminates at the value of critical hydraulic gradient. The path terminus establishes a hydromechanical boundary governing the onset of seepage- induced internal instability in one-dimensional flow. The boundary represents a failure envelope, which is different for each of the four soils tested. A ranking of seepage-induced instability for each soil, from most unstable to least unstable, is found similar, but not identical to, the susceptibility to internal instability determined from empirical analysis of the gra- dation shape. Resume´ : Des resultats d'essais en permeametre impliquant un ecoulement unidirectionnel a travers des echantillons re- constitues de quatre sols sans cohesion agranulometrie etalee sont presentes. Le debut de l'instabiliteest defini par une di- minution significative du gradient hydraulique local sur une periode de temps relativement courte. Le nouveau concept d'un cheminement hydromecanique dans l'espace contrainte (s 0) - gradient (ijk) est propose ´, qui decrit le comportement en ecoulement durant l'essai et qui se termine ala valeur du gradient hydraulique critique. Le point final du cheminement etablit une frontiere hydromecanique qui gere le debut de l'instabiliteinterne causee par l'infiltration en ecoulement uni- dimensionnel. La frontiere represente une enveloppe de rupture, qui est differente pour chacun des quatre sols testes. Un classement de l'instabilitecausee par l'infiltration pour chaque sol, du plus instable au moins instable, est semblable mais pas identique a la susceptibilitea l'instabiliteinterne determineeapartir d'analyses empiriques de la forme de la grada- tion. Mots-cles: infiltration, gradient hydraulique, contrainte effective, instabiliteinterne. (Traduit par la Redaction)
Postseismic fluid flow after the large subduction earthquake of Antofagasta, Chile

We interpret the time evolution of high P-wave to S-wave velocity ( V p/ V s) ratios after the large Antofagasta subduction earthquake (M w = 8.0) as due to postseismic fluid flow into the overriding plate. We suggest that accumulation of high stress forms a permeability barrier along the plate interface, capturing the fluids in the subducting plate. This seal is broken only by large subduction earthquakes that allow the fluids to rapidly migrate into the overlying plate. Postseismic fluid flow implies a relatively high permeability of the overlying lower continental crust, which we estimate to be 10 −16 to 10 −17 m 2 .
An assessment of real‐time extended range forecast of 2013 Indian summer monsoon

Several aspects of real‐time forecast of Indian summer monsoon (ISM) in 3–4 pentad lead time (extended range) are discussed in this study to explore the operational capability of the Climate Forecast System model version 2 (CFSv2) developed by National Centre for Environmental Prediction (NCEP). 2013 summer monsoon was a near excess monsoon year in terms of seasonal mean and was a result of rich diversity of phenomena including strong intraseasonal variations and intense northward propagations over the Indian region. Eleven‐member forecasts were made at every 5‐day interval during the June–September monsoon season which included monsoon onset and withdrawal phases. The ensemble members were created by perturbing the initial conditions at each start time. In addition to the CFSv2 forecasts, we also carried out forecasts using the atmospheric‐only component (GFSv2) forced with CFSv2‐derived sea surface temperature (SST) subjected to a bias correction based on historical observations (GFSbc runs).
Nitrous oxide fluxes in the central and eastern South Pacific

N2O air‐sea fluxes were continuously measured on a transect crossing the Subtropical South Pacific Gyre (SPG) from its central part toward its coastal boundary (associated with coastal upwelling off central Chile) during the BIOSOPE cruise (austral spring, 2004). Continuous N2O air‐sea fluxes in the central part of the SPG (132° to 114°W) were slightly negative (−0.48 ± 0.44 μmol m−2 day−1), whereas in its eastern part (114°W to 81°W), they were slightly positive (0.41 ± 0.34 μmol m−2 day−1), reaching up to 18 μmol m−2 day−1 in the coastal area (130 km from the coast). The transition between oceanic and coastal conditions was characterized by an abrupt increase in N2O emissions from 80°W eastward and was associated with an increase of surface Chl‐a contents. This trend corresponded to the change in trophic status from very oligotrophic to eutrophic. The outward (through the air‐sea interface) and inward (through the pycnocline) N2O fluxes of the surface layer (SL) were also determined at three representative stations, taking into account turbulent diffusion and vertical advection. The N2O released into the atmosphere from the eastern part of the SPG came largely (70–80%) from the N2O produced in the SL (2.0 × 10−3μmol m−3 day−1). In the coastal area, N2O production in the SL reached up to 1.16 μmol m−3 day−1, and 28% of the N2O released into the atmosphere was upwelled though the pycnocline by Ekman transport. The annual N2O emissions estimated for the eastern South Pacific reach 50 Gg of N2O, confirming the importance of this region for global emissions and reaffirming coastal upwelling centers as areas of strong production and outgassing.
Atmospheric CO2 and O3 observed on Rishiri Island from December 2006 to March 2007

2006年12月から2007年3月まで北海道利尻島(45°07′N, 141°12′E)において大気中CO2とO3の濃度測定を実施した。 観測されたCO2とO3濃度は数分から数ヶ月の時間スケールで変動しており、12月から2月中旬までの期間CO2濃度はO3濃度の変動と逆相関を示した。 この逆相関はユーラシア大陸の高緯度地域及び利尻島での土壌呼吸によるCO2排出と地表でのO3分解消失によって引き起こされるものと考えられた。 12月から2月中旬までの逆相関とは対照的に、2月中旬以降大気中CO2濃度とO3濃度は、時折正相関を示した。 これら高濃度のCO2とO3は日本及び朝鮮半島の人為起源による排出・輸送の影響を受けていることが示唆された。