Miracle-dz/UniFAR-FTUs huggingface dataset:
Critical factors in the exploration of an Atlas intramontane basin; the Western Hodna Basin of northern Algeria

Abstract The acquisition and evaluation of a substantial integrated surface outcrop and well database over the western Hodna Basin allows the identification of three critical factors (reservoir quality, source maturity and timing and hydrodynamic regime) to which well failures to date can largely be attributed. Reservoir quality is variable in Cretaceous sandstones, because of a high degree of quartz cementation, but improves to the south. Reservoir quality in Eocene limestones is related to the development of vuggy porosity and can now be mapped out from well control. Potential Cretaceous source rocks lie at moderate to high degrees of maturity, with explusion probably preceding the Miocene phases of structure development. Tertiary palaeostress reconstructions from field studies indicate four main structural phases: (1) Late Cretaceous N-S to NW-SE oriented compression; (2) Oligo-Miocene distension; (3) N-S oriented Miocene (pre-Langhian) pull-apart; (4) Langhian compression related to the emplacement of the Tellian nappes. Seismic analysis illustrates some classic late-stage inversion structures. Organic matter seen in outcrops and cores within the Thanetian-Ypresian and lower Lutetian sections is composed mainly of type II kerogen and varies from undermature to marginally mature, leading to the development of shows in many wells that helped in the past to stimulate continued exploration. Study of the hydrology of the formation waters in drilled wells allows large areas of likely reservoir flushing to be delineated. Study of the three critical factors allows a high grading in terms of remaining exploration potential. Based on the interpretations derived from structural, palaeogeography, diagenetic and hydrodynamic studies, the basin can be divided into three areas, which are ranked on the basis of their prospectivity. Each of the factors also needs to be critically assessed in analogous regions of the Atlas, in which such good geological control may not exist.
Separated two‐phase flow and basaltic eruptions

Fluid dynamical models of volcanic eruptions are usually made in the homogeneous approximation where gas and liquid are constrained to move at the same velocity. Basaltic eruptions exhibit the characteristics of separated flows, including transitions in their flow regime, from bubbly to slug flow in Strombolian eruptions and from bubbly to annular flow in Hawaiian ones. These regimes can be characterized by a parameter called the melt superficial velocity, or volume flux per unit cross section, which takes values between 10−3 and 10−2 m/s for bubbly and slug flow, and about 1 m/s for annular flow. We use two-phase flow equations to determine under which conditions the homogeneous approximation is not valid. In the bubbly regime, in which many bubbles rise through the moving liquid, there are large differences between the two-phase and homogeneous models, especially in the predictions of gas content and pressure. The homogeneous model is valid for viscous lavas such as dacites because viscosity impedes bubble motion. It is not valid for basaltic lavas if bubble sizes are greater than 1 cm, which is the case. Accordingly, basaltic eruptions should be characterized by lower gas contents and lower values of the exit pressure, and they rarely erupt in the mist and froth regimes, which are a feature of more viscous lavas. The two-phase flow framework allows for the treatment of different bubble populations, including vesicles due to exsolution by pressure release in the volcanic conduit and bubbles from the magma chamber. This yields information on poorly constrained parameters including the effective friction coefficient for the conduit, gas content, and bubble size in the chamber. We suggest that the observed flow transitions record changes in the amount and size of gas bubbles in the magma chamber at the conduit entry.
Evaluation of empirical and semi-empirical backscattering models for surface soil moisture estimation

Several empirical and semi-empirical backscattering models have been proposed to offer alternative expressions for the inversion of surface parameters from radar data, but the applicability and adequacy of the models for different surface conditions and sensor configurations have not been clearly assessed. A number of empirical and semi-empirical models are studied in this paper to assess the applicability of the models for different conditions that are often found over agricultural areas. The performance of the models is evaluated first analytically by comparing their simulations with those obtained using the theoretical integral equation model (IEM) and geometrical optics model (GOM). The model estimations are then compared with RADARSAT-1 observations acquired over an experimental catchment. The results show very different model behaviour depending on the surfaces roughness conditions and incidence angle. This study highlights the importance of carefully selecting the backscattering model to be used in radar applications.
The Puglia uplift (SE Italy): An anomaly in the foreland of the Apenninic subduction due to buckling of a thick continental lithosphere

The Apenninic foreland shows two distinct structural signatures comparing the central Adriatic Sea and the Puglia region. During the Pliocene-Pleistocene the central Adriatic underwent high subsidence rates due to the eastward rollback of the hinge of the west dipping Apenninic subduction. The Puglia region and the Bradanic foredeep are located southward along strike in the same foreland, but, in contrast with the central Adriatic, after Pliocene-early Pleistocene subsidence they underwent uplift since the middle Pleistocene. The geometry and the kinematics of the frontal accretionary wedge and related foreland changed from that moment on between the two areas. At the front of the central northern Apennines, off scraping and subsidence continued, whereas the foredeep and foreland of the southern Apennines were buckled. Those differences are interpreted as being due to the larger subduction hinge rollback rate since middle Pleistocene of the central Adriatic lithosphere (70 km thick) with respect to the thicker Puglia (110 km). The different thicknesses of the continental crust and lithosphere were inherited from the Mesozoic rifting that disrupted the Adriatic plate. The different thicknesses appear to have controlled the variable degree of flexure of the lithosphere and its asthenospheric penetration rate. The Tremiti E–W alignment is the right-lateral lithospheric transfer zone of those different tectonic regimes. The consequent different dip of the subduction in the two sections (steeper west of Puglia) could also explain the lower elevation of the southern Apennines, compared to their central-northern sector.
Effects of dynamic crop growth on the simulated precipitation response to irrigation

AbstractThe rapid expansion of irrigation since the 1950s has significantly depleted the Ogallala Aquifer. This study examines the warm-season climate impacts of irrigation over the Ogallala using high-resolution (6.33 km) simulations of a version of the Weather Research and Forecasting (WRF) Model that has been coupled to the Community Land Model with dynamic crop growth (WRF-CLM4crop). To examine how dynamic crops influence the simulated impact of irrigation, the authors compare simulations with dynamic crops to simulations with a fixed annual cycle of crop leaf area index (static crops). For each crop scheme, simulations were completed with and without irrigation for 9 years that represent the range of observed precipitation. Reduced temperature and precipitation biases occur with dynamic versus static crops. Fundamental differences in the precipitation response to irrigation occur with dynamic crops, as enhanced surface roughness weakens low-level winds, enabling more water from irrigation to remain o.
Orogen‐scale decollements

The continental lithosphere responds to stress by deforming as a generally layered medium. Deep seismic reflection data, coupled with a variety of ancillary geological and geophysical data, are interpreted to provide images of fault zones that tend to form moderately dipping ramp structures in mechanically rigid layers, and flat detachments in mechanically weak layers. This geometry is similar to ramp and flat structures observed at smaller scales in thrust and fold belts and leads to the interpretation that most orogens are underlain by orogen-scale decollements in a manner that is analogous to so-called “thin skin” deformation in sedimentary rocks. Decollements may occur within the crust (for example, near the base of a sedimentary section or in the middle crust), near the Moho, in the subcrustal lithosphere, or in the asthenosphere. Even intracratonic basement-cored (“thick skin”) uplifts that occasionally occur in foreland regions such as the Wyoming province are probably large (crustal) scale versions of ramp/flat features observed in supracrustal rocks and are thus likely caused by the same fundamental tectonic processes.
PRODUCTIVITY AND ABUNDANCE OF SCLEROCARYA BIRREA SUBSP. CAFFRA IN AND AROUND RURAL SETTLEMENTS AND PROTECTED AREAS OF THE BUSHBUCKRIDGE LOWVELD, SOUTH AFRICA

ABSTRACT Sclerocarya birrea (A. Rich.) Hochst, subsp. caffra (Sond.) Kokwaro is a common species throughout the semi-arid savannas of southern Africa, and is sought after by rural communities. It is frequently maintained in homesteads and fields in an agroforestry situation. It has also been identified by a number of international and national institutes as a key species for domestication and commercialisation. Yet, the sustainability of the resource and local user knowledge and practices have not been considered. This study reports on the abundance and productivity of S. birrea in four rural villages and neighbouring protected areas in the Bushbuckridge lowveld of the Limpopo Province, South Africa, where its common name is marula. The density of marula stems was measured in homestead plots, arable fields and the surrounding communal rangelands of each village. Fruit production was assessed by regular counting of fruit fall from marked trees of known size. Within the villages, fruit production was monitored via local community groups. Additional monitoring of fruiting was conducted on marked trees within local protected areas. The proportion of households planting or nurturing marula trees was determined through interviews with a stratified random sample of households. The density of marula trees was significantly higher in protected areas than the neighbouring communal lands, fields or homesteads. However, the majority of trees in protected areas were small, while those in homesteads were large and mature. Density of adult fruit-bearing female trees, was similar between the protected areas and homesteads, but less in fields and communal lands. S. birrea trees were maintained in 79 % of homesteads and 58 % of fields. Mean fruit yield per tree was significantly higher from village trees (> 17 000 fruits) than protected area trees (< 3 500 fruits), even after accounting for differences in tree size. The fresh mass of individual fruits was also greater on village trees than on trees in protected areas. Both these characteristics suggest some degree of historical selection of the trees in the homesteads and fields. There was a positive relationship between tree size and number of fruits produced.
Measured and modeled equilibrium sizes of NaCl and (NH4)2SO4 particles at relative humidities up to 99.1

[1] The Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to measure equilibrium sizes of particles at relative humidities (RHs) up to 99.1%. Particles of substances with well-known hygroscopic behavior (NaCl and (NH4)2SO4) were used for the measurements. The intention was to check the proper functionality of LACIS for this measurement mode. Equilibrium sizes were also simulated on the basis of Kohler theory, by (1) assuming ideal solutions and (2) accounting for the nonideality of the droplets by using osmotic coefficients from the open literature. Measured and simulated equilibrium diameters were compared to measured values published in the open literature. For sodium chloride, model approaches 1 and 2 and all measured values were in good agreement. For ammonium sulfate, the results of model approach 2 (nonideal solution) were in good agreement with the measured diameters, whereas assuming an ideal solution yields equilibrium diameters that are too large by up to 20%. Measured hygroscopic growth factors were used to derive scattering coefficients and visibilities for two exemplary atmospheric dry number size distributions at different RHs. For both salts, at 90% RH the scattering coefficient increased by about a factor of 5 compared to that of the dry aerosol; at 99% RH the increase was about 21-fold. If instead the hygroscopic growth was assumed to follow the growth factors that were simulated for an ideal ammonium sulfate solution, the increase of the scattering coefficient is overestimated by ∼40%. This highlights the need to account for the nonideal solution behavior of droplets when calculating equilibrium diameters, even at high RHs.
Dynamics of crustal compensation and its influences on crustal isostasy

Deviation from isostasy is commonly believed to be caused by the strength of the Earth's lithosphere. An analysis of crustal compensation dynamics suggests that the deviation may have a dynamic origin. The analysis is based on analytic models that assume that (1) the medium is incompressible and has a layered and linear viscoelastic rheology and (2) the amplitude of topography is small compared with its wavelength. The models can describe topographic relaxation of different density interfaces at both small (e.g., postglacial rebound) and large time-scales. The models show that for a simple crust-mantle system with topography at the Earth's surface and Moho representing the only mass anomalies, while the crust always approaches the isostatic state at long wavelengths (>800 km), crustal isostasy may not be an asymptotic limit at short wavelengths, depending on crustal and lithospheric rheology. For a crust with viscosity smaller than lithospheric viscosity, at wavelengths comparable with widths of orogenic belts (i.e., <300 km), the crust tends to approach a state with significant overcompensation (i.e., excess topography at the Moho) within a timescale of about 107 years, and this characteristic time depends on wavelengths and crustal viscosity. This overcompensation is greater for weaker crust and stronger lithosphere. A thicker crust or lithosphere also enhances this overcompensation. If crustal and lithospheric viscosities are both large and comparable, the asymptotic state for the crust displays a slight undercompensation. For an elastic and rigid upper crust, the crust eventually becomes undercompensated after a characteristic decay time of topography at the Moho. The characteristic time is dependent on viscosity and thickness of the lower crust. The deviation from isostasy arises because these viscosity structures result in a ratio of vertical velocity at the surface to vertical velocity at the Moho which in the asymptotic state for short wavelengths differs from the ratio of density contrast at the Moho to that at the surface.
Changes in daily precipitation frequency and distribution in Italy over the last 120 years

[1] A new data set of 45 daily precipitation series, covering quite uniformly Italian territory for the period 1880–2002, was recovered. The series have been homogenized on daily basis, completed by means of statistical methods and grouped into five regions by a Principal Component Analysis. Seasonal and yearly total precipitation, number of wet days, and precipitation intensity were analyzed for each station record and averaged into five regional series for a synthetic description of the results. Proportion and frequency of daily rainfall amounts, belonging to six precipitation class-intervals, defined on the basis of some percentiles of the precipitation distribution, were also analyzed. The results show a negative significant trend in the number of wet days all over Italy, and a positive trend in precipitation intensity, which is significant only in the northern regions. The negative trend in wet days has persisted since the end of 19th century and is due to the marked decrease in the number of low intensity precipitation events. An increase in the number of events belonging to the highest intensity class interval was observed too, but only in northern regions.
The global ocean flux of particulate organic carbon: Areal distribution and magnitude

The magnitude and distribution of the particulate organic carbon (POC) rain rate to the seafloor in the Atlantic, Pacific and Indian Ocean basins between 61°N and 61°S has been estimated from benthic oxygen flux estimates (for water depths ≥ 1000 m only). The calculation utilizes the extensive data sets of sedimentary organic carbon, CaCO3, and accumulation rate to extrapolate between individual benthic flux measurement sites using an empirically-derived correlation between the seafloor oxygen flux and these parameters. The POC flux through the 1000 m depth horizon was then estimated from published correlations between sediment trap-determined fluxes and water depth. Total oxygen utilization in the deep ocean is estimated to be 1.2×1014 mol O2 yr−1, a value that agrees well with previous estimates which were based on surface water primary productivity, sediment trap, and depth relationships and with deep water respiration rates estimated from apparant oxygen utilization (AOU)-14C relationships. On the basis of the derived global ocean flux distribution, it is concluded that (1) dissolved organic carbon (DOC) inputs are not required to account for estimated deep water respiration rates; (2) the majority of the POC input to the deep ocean occurs within 30° of the equator; (3) the proportion of primary production that reaches the deep sea does not vary greatly with latitude; (4) gyre and continental margin regions contribute roughly equally to the deep POC flux with a relatively minor contribution from the equatorial divergence region; (5) of the estimated 7.2×1013 mol C yr−1 of POC that sinks below the 1000 m depth horizon, 45% (3.3×1013 mol C yr−1) reaches the seafloor where it is oxidized; (6) when normalized to basin area, average deep flux rates in the Atlantic and Pacific are similar while highest rates are observed in the Indian Ocean; and (7) the results can be fully reconciled only if the benthic flux of DOC is significantly less than the benthic O2 flux.
Soil respiration in four different land-use systems in north central Alberta, Canada

agriculture and 2 year old hybrid poplar plantation, respectively. We found that � 75% of soil respiration in the native aspen stand originated from the top 7.5–10 cm litter-fibrichumus layer. Seasonal heterotrophic and autotrophic respiration among the land uses ranged from 97 to 272 and 333 to 560 g C m � 2 , respectively, contributing up to 35% and 83% of total soil respiration, respectively. The variability in soil respiration across different land uses was explained mainly by site differences in soil temperature (88– 94%). Soil respiration followed a pronounced seasonal trend: increasing during the growing season and converging to a minimum in the fall. Soil respiration under different land uses was influenced by (1) ecosystem C stock, (2) temperature sensitivity (Q10 )o f organic matter present, and (3) organic matter decomposability as indicated by the natural abundance of d 13 C. Heterotrophic respiration was influenced by soil temperature, while autotrophic respiration was influenced by fine root biomass and nutrient (NO3 and P) availability. These results are useful in estimating potential responses of soil respiration and its components to future land management and climate change.
THE MIDDLE ORDOVICIAN PROVENTOCITUM PROCERULUM RADIOLARIAN ASSEMBLAGE OF SPITSBERGEN AND ITS BIOSTRATIGRAPHIC CORRELATION

Abstract: The Proventocitum procerulum radiolarian assemblage from the Valhallfonna Formation of Spitsbergen is described for the first time in some detail from material investigated in transmitted light. A number of species are recognized in the well‐preserved material, showing unexpected diversity. The age of the fauna is restricted to the early Darriwilian (Da1‐2), based on comparison with precisely dated radiolarian assemblages from the Cow Head and Table Head Groups of western Newfoundland. Most species, however, are left in open nomenclature until additional material is available for SEM investigation. Inanigutta magnifica n. sp. is described as new.
Observations of the diurnal tide during seven intensive radiosonde campaigns in Australia and Indonesia

[1] Seven intensive radiosonde campaigns of between five days and one month duration were conducted in northern Australia and the Indonesian region between 2001 and 2006. These data were used to study the diurnal tide below 30 km altitude. Inter-campaign comparisons were made at Darwin (12°S, 131°E) and Koto Tabang (0°S, 100°E). The amplitudes of the diurnal tide did not depend upon the strength of tropospheric convection at Koto Tabang or whether there were monsoon conditions at Darwin. However, the amplitude of the zonal wind component at Koto Tabang during the different campaigns was influenced by the background QBO zonal wind structure. Stratospheric amplitudes exceeded 2.0 m s−1 at 16–17 km and 24–26 km, where the zonal wind shear was greater than 15 m s−1 km−1 during November–December 2005, but were 0.3 m s−1 when the wind shear was close to zero above 25 km during April–May 2004. The local time phase structures at Darwin and Koto Tabang were similar between campaigns and also similar to previous observations in the region, suggesting a uniform regional scale heating source. Vertical wavelengths of the stratospheric diurnal tide were generally 5–20 km. This, together with the tidal interaction with the background wind shear, suggests the presence of non-migrating components.
Determination of the striking distance of lightning to earthed structures

A theoretical determination based upon a critical charge criterion and ionization processes is presented of the striking distance rs at which the upward leader is initiated from a struck object. The striking distance is shown to be leader-current dependent in the form rs ∝ i2/3. Comparisons are made with earlier, more numerically based models, which used an alternative equivalent-radius approach. The altitude dependence of the striking distance is also investigated. Since pressure, absolute humidity and temperature decrease with increasing altitude, the variation of streamer properties with altitude can be inferred from laboratory experiments. Calculations on this basis show that the striking distance increases significantly with increasing altitude, causing a corresponding increase in the risk of lightning strikes for given structures in mountain or aviation environments.