Miracle-dz/UniFAR-FTUs huggingface dataset:
BENTHIC FORAMINIFERAL EXTINCTION AND REPOPULATION IN RESPONSE TO LATEST PALEOCENE TETHYAN ANOXIA

The latest Paleocene benthic foraminiferal extinction event has been studied in two marlstone successions in the Tethys: at Wadi Nukhl (Egypt) and Torangly (Turkmenistan). Both sections yield a sapropelic layer at the level of the extinction event. At Nukhl, this layer underlies a thin calcareous bed that has also been found in other Middle East upper Paleocene sections. With the onset of anoxia at the Tethyan sea floor, the aerobic and oligotrophic Gavelinella beccariiformis deep-sea community collapsed. Eutrophic-to-mesotrophic and low-oxygen conditions, most likely resulting from enhanced organic carbon fluxes to the sea floor, triggered an ~100‐200 k.y. repopulation sequence, marked by downslope migration of several neritic communities that were dominated by opportunistic and tolerant taxa. The initial ecosystem restoration was completed when an aerobic and oligotrophic Nuttallides truempyi deep-sea community became established. We suggest that this repopulation mode could be typical for the central Tethys.
Size truncation effect, threshold behavior, and a new type of autoconversion parameterization

A function defined as the size truncation function is introduced to quantify the effect of truncating the cloud droplet size distribution on the autoconversion rate. It is shown that the size truncation function can be used as a threshold function to represent the threshold behavior associated with the autoconversion process, providing a physical basis for the threshold function. Comparisons of the new threshold function with those ad hoc threshold functions associated with existing Kessler‐type and Sundqvist‐type parameterizations reveals the degree of approximations of the two empirical parameterizations. Application of the new threshold function leads to a new type of autoconversion parameterization that is fully analytical, physics‐based, and removes the ad hoc nature of threshold representation in existing autoconversion parameterizations.
Round Buoyant Jet Entering Shallow Water in Motion

This paper focuses on the mixing processes that develop when a buoyant jet from a round outfall pipe enters a shallow moving body of water. Results from a detailed experimental study quantify the effects on jet mixing produced when a current is imposed on shallow receiving water. Findings show that the dilutions of buoyant jets entering these environments are significantly different from those discharging into unconfined (deep‐water) conditions. Mixing features discussed include the application of scaling relationships in collapsing integral parameter data and the role played by the Coanda effect in influencing the mixing of jets. Patterns of jet path, centerline dilution, total dilution, horizontal and vertical half widths, and a novel width parameter are described and compared with shallow stationary and current affected deep‐water results.
Robust spring drying in the southwestern U.S. and seasonal migration of wet/dry patterns in a warmer climate

This study compares climate simulations over North America produced by a regional climate model with the driving global climate simulations as well as a multimodel ensemble of global climate simulations to investigate robust changes in water availability (precipitation (P)‐evapotranspiration (E)). A robust spring‐drying signal across multiple models is identified in the Southwest that results from a decrease in P and an increase in E in the future. In the boreal winter and summer, the prominent changes in P‐E are associated with a north‐south dipole pattern, while in spring, the prominent changes in P‐E appear as an east‐west dipole pattern. The progression of the north‐south and east‐west dipole patterns through the seasons manifests clearly as a seasonal “clockwise” migration of wet/dry patterns, which is a robust feature of water availability changes in North America consistent across regional and global climate simulations.
Contact metamorphism, halocarbons, and environmental crises of the past

What triggered the largest know mass extinction at the Permian-Triassic boundary 252 million years ago, when 95% of the species in the oceans disappeared? New geological data suggest that eruptions of carbon (CH4 ,C O 2) and halocarbon (CH3Cl and CH3Br) gases from the vast sedimentary basins of east Siberia could have triggered a period with global warming (5 ◦ -10 ◦ C) and terrestrial mass extinction. The gases were generated during contact metamorphism of sedimentary rocks around 1200 ◦ C hot igneous intrusions. One of the suggested end-Permian extinction mechanisms is the extreme ultraviolet radiation (UV-B) caused by a prolonged destruction of stratospheric ozone induced by the emitted halocarbons. This hypothesis is supported by a new set of experiments, where natural rock salt samples from Siberia were heated to 275 ◦ C. Among the gases generated during heating are methyl chloride (CH3Cl) and methyl bromide (CH3Br).
Magnetopause erosion: A global view from MHD simulation

[1] In this paper we use a global magnetohydrodynamic simulation of the magnetosphere to examine the behavior of the magnetopause position when the interplanetary magnetic field suddenly changes from northward to southward. The inward motion of the magnetopause under the influence of a southward IMF is generally referred to as magnetopause “erosion. ” Physical models to explain erosion have been proposed, notably the “onion” peeling model, a model based on the effects of fringe fields from the Region 1 Birkeland currents and the nightside cross-tail current. The simulation shows behavior consistent with aspects of these models, but it also shows behavior that is most consistent with the major driver of erosion being the growth of the nightside cross-tail current. In particular, the simulation exhibits a marked delay between the arrival of the southward IMF at the magnetopause and the inward motion of the magnetopause. We attribute this delay to the delay in the growth of the nightside current system in response to the southward turning of the IMF.
Rhéologie et microstructure des suspensions concentrées non-browniennes

De part leur ubiquite et les nombreux parametres physiques les caracterisant, les suspensions concentrees (i.e. la dispersion de grains solides dans une matrice fluide) presentent des proprietes rheologiques vastes et complexes. Cette etude se limite a des suspensions modeles de spheres rigides non colloidales immergees dans un fluide newtonien, et a des ecoulements ou l'inertie et le mouvement brownien peuvent etre negliges. Ce manuscrit presente une etude experimentale de la microstructure des suspensions non-browniennes en ecoulement et de son lien avec leur reponse rheologique. Il explore le role important joue par les contacts dans la reponse mecanique de ces materiaux. Deux dispositifs experimentaux ont pour cela ete mis au point. Le premier, dit de rheometrie locale, accede aux champs de vitesse de l'ecoulement et aux quantites rheologiques du materiau par le biais d'une technique de velocimetrie par imagerie de particules. Le second permet, grâce au suivi individuel des spheres solides, de realiser une mesure directe de la microstructure de la suspension. Une etude en rheometrie locale du regime transitoire mesure apres une inversion de cisaillement montre que la viscosite d'une suspension chute avant de revenir a la valeur du regime permanent. Alors que la viscosite a l'etat stationnaire diverge avec une loi de puissance d'exposant -2 lorsque la concentration s'approche de la concentration de blocage, la viscosite minimale diverge avec un exposant -1. Ce resultat, mis en parallele avec d'autres etudes de la litterature, montre le role important des contacts et de la microstructure sur la rheologie des suspensions. La microstructure est etudiee a travers la fonction de distribution de paires. Pour des suspensions diluees l'asymetrie amont-aval et l'inclinaison de la zone de depletion est tres bien reproduite par un modele a deux particules et apportent une preuve d'un contact entre les spheres via les rugosites. A forte concentration, en plus d'une inclinaison de la zone de depletion vers l'axe de dilatation, il apparait une zone d'accumulation dans la direction de la vitesse.
The vertical distribution of Mars water vapor

Analysis of observations made from the Viking 1 Orbiter indicates that the water vapor over the Viking 1 landing site is uniformly mixed with the atmosphere and not concentrated near the surface. The analysis incorporates the effects of atmospheric scattering and explains why previous earth-based observations showed a strong diurnal variation in water content. It also explains the lack of an early morning fog and removes the necessity of daily exchange of large amounts of water between the surface and the atmosphere. A water vapor volume mixing ratio of 1.5×10−4 is inferred for the Viking 1 site in late summer.
Sulphur release from flood lava eruptions in the Veidivötn, Grímsvötn and Katla volcanic systems, Iceland

Abstract Emissions of SO2 by volcanic eruptions have been shown to be important for short-term environmental and climate changes. Stratospheric sulphur mass-loading by explosive silicic eruption is commonly considered to be the principal forcing factor for these changes. The SO2 emissions from basaltic flood lava eruptions have not featured strongly in the discussions on volcano-climate interactions, notwithstanding the fact that basaltic magma is typically richer in sulphur (by a factor of two to four), than silicic magmas, as well as the evidence of widespread atmospheric impact associated with historical flood lava eruption. Fourteen Holocene flood lava eruptions are known from the Veidivötn, Grímsvötn, and Katla volcanic systems of the Eastern Volcanic Zone in South Iceland, which include the three largest of its kind in Iceland; the 1783–1784 Laki, 934–40 Eldgjá, and c. 8600 years BP Thjórsá events. We present new data on the sulphur content in melt inclusions from the Veidivötn system and use this information, along with existing inclusion data from the Grímsvötn and Katla volcanic systems, to establish an empirical method for estimating the sulphur mass release from these basaltic flood lava eruptions. The results show that these eruptions released a total of c. 700 Mt SO2 into the atmosphere in four 600- to 850-year-long eruption periods. During each period, between 98 and 328 Mt SO2 were emitted into the atmosphere, and the mass loadings from individual eruptions ranged from 5 to 210 Mt SO2. These flood lava eruptions are likely to have resulted in widespread atmospheric perturbations and, by analogy with the 1783–1784 Laki eruption, the effects of the largest eruptions may have been felt on a hemispheric scale.
A mechanistic model for the spectral induced polarization of clay materials

Water-saturated clay-rich media exhibit low-frequency (1 Hz to 1 MHz) effective conductivity and effective permittivity dispersions that are the consequence of both the polarization of the mineral/water interface coating the surface of the grains and the Maxwell-Wagner polarization. These low-frequency properties are modeled by combining (1) a complexation model of the surface properties of clay minerals (kaolinite, illite, and smectite), (2) a polarization model of the Stern layer (the inner portion of the electrical double layer coating the surface of the minerals), and (3) a macroscopic model comprising the electrochemical polarization of the grains and the contribution of the Maxwell-Wagner effect. The macroscopic model is based on the differential effective medium theory. It includes a convolution product with the grain size distribution. For kaolinite, the diffuse layer occupies a small fraction of the pore space and is considered as part of the surface of the grains. This is due to the low specific surface area of kaolinite. In the case of illite and smectite, the situation is different. Because of the high specific surface areas of these minerals, the diffuse layer occupies a large fraction of the pore space and is considered as part of the pore space and is described using a Donnan equilibrium model. We obtain excellent comparisons between various experimental data reported in the literature and our model. Then, we considered low-porosity (compacted or cemented) clay rocks and shales. Here too, we obtained a good agreement between the data and the predictions of a model based on a volume-averaging approach. We also note that at very low frequencies (<1 Hz), another polarization mechanism exists that is not reproduced by our model. We believe that this polarization corresponds to a nonlinear membrane polarization contribution.
LOWER PERMIAN PALAEOAPLYSINID BIOHERMS AND ASSOCIATED SEDIMENTS FROM CENTRAL SPITSBERGEN

Bioherms found in the Lower Permian Tyrrellfjellet Member of Central Spitsbergen contain bindstones produced by the ? hydrozoan taxon Palaeoaplysina. We briefly describe the bioherms’stratigraphical and environmental setting and note their development on hardground surfaces. The association of these structures with bituminous limestones is interesting in view of the petroleum resources of similar buildups in the USSR.
Re-examination of the BMN Model for Estimating Evapotranspiration

This study re-examined the BM N model making use of the Sig ma Plot software (based on the Levenberg - Marquardt algorithm) to generate modified versions of the BMN model that are specific for Ibadan, Kano and Onne and one version which applicable across the country, correcting some perceived shortcomings of the BMN. Records of climat ic variables (So lar radiat ion, Maximu m and Min imu m Temperature, Maximu m and M inimu m Relat ive Hu mid ity and Wind speed) were collected fro m three International Institute of Tropical Agriculture (IITA) Stations in Ibadan, Kano and Onne. For Ibadan, a 36-year (1973 - 2008) record was obtained, for Kano, a 29-year (1980 - 2008) record was obtained and for Onne, a 31-year (1977 - 2006) record was obtained. Evapotranspiration rates for each of the stations were then estimated using the FAO56-PM model. ETo estimates fro m the FAO56-PM model were thereafter used to recalibrate the BM N model, generating new model constants for Ibadan, Kano, Onne and a model co mb ining the climatic characteristics of the three stations. The re-calibrated BM N model had h igher correlat ion values of 0.74, 0.79 and 0.75 for Ibadan, Onne and Kano respectively when compared with the FAO-56 model than the Original BM N model when compared with the FAO56-PM model with values of 0.7, 0.77 and 0.75 respectively for Ibadan, Onne and Kano.
The origin of the montmorillonite of the European Chalk with special reference to the Lower Chalk of England

Abstract The evidence is reviewed for the various hypotheses put forward to explain the origin of the Chalk montmorillonite. Recent X-ray investigation of the mineralogy of the acid-insoluble clay fractions (buffered 2 N acetic acid at pH 3; <2 µ e.s.d.) of the Lower Chalk of England sheds light on the origin of the montmorillonite. The relations between the qualitative and semi-quantitative mineralogy of the clay fractions and the facies and stratigraphy in this formation have been studied in detail. Montmorillonite, illite, kaolinite, chlorite, vermiculite, pyrophyllite, mixed-layer minerals, quartz, low-temperature cristobalite and apatite have been identified; their semi-quantitative distribution reveals that two main antipathetic assemblages are present, between which all gradations occur. The first is characterized by montmorillonite, illite, quartz and by montmorillonite/illite (M/I) values of 0·7 and above; and the second by illite, kaolinite, chlorite, vermiculite and by M/I values of below 0·2. The distribution of these assemblages or of any particular mineral does not show obvious relations to the facies or stratigraphy. There is strong evidence that the second of these assemblages is of detrital origin, introduced into the Lower Chalk seas by currents flowing mainly from areas to the east and south-east of England. There is no evidence to suggest that the montmorillonite and the illite of the first assemblage are of detrital or volcanic origin, and their distribution in the Lower Chalk is best explained by their neoformation in the sediment on the sea floor by precipitation from the porewaters. By extrapolation it is thought that most of the Chalk montmorillonite of clay-grade is of neoformational origin. Some from the Campanian and younger Chalks may be detrital. Locally in N.W. Germany and possibly Poland minor amounts may have been derived from the decomposition of volcanic glass in the Chalk seas.
Thermal constraints on the formation of mississippi valley-type lead-zinc deposits and their implications for episodic basin dewatering and deposit genesis

Two simple constraints: that the deposits formed within 1 km of the surface, and that the temperature of the ore fluids at the time of mineral deposition was 100 degrees to 150 degrees C. For base metal deposits to form as the result of the compactive expulsion of basin brines, brine expulsion must be episodic. Episodic pulses of geopressured brines moving through the near-surface sites of ore deposition, followed by much longer periods of exposure to cool surface waters, could produce the color banding of sphalerite, the cycles of sulfide precipitation and dissolution, and the distinctive local tectonic features associated with mississippi valley-type deposits. Basin features favoring the right kind of episodic dewatering are identified. --Modified journal abstract.
Retrieval of the spectral diffuse attenuation coefficient Kd(λ) in open and coastal ocean waters using a neural network inversion

[1] The diffuse attenuation coefficient, Kd(λ) is a fundamental radiometric parameter that is used to assess the light availability in the water column. A neural network approach is developed to assess Kd(λ) at any visible wavelengths from the remote sensing reflectances as measured by the SeaWiFS satellite sensor. The neural network (NN) inversion is trained using a combination of simulated and in-situ data sets covering a broad range ofKd(λ), between 0.0073 m−1 at 412 nm and 12.41 m−1at 510 nm. The performance of the retrieval is evaluated against two data sets, one consisting of mainly synthetic data while the other one contains in-situ data only and is compared to those obtained with previous published empirical (NASA, Morel and Maritorena (2001) and Zhang and Fell (2007)) and semi-analytical (Lee et al., 2005b) algorithms. On the in-situ data set from the COASTLOOC campaign, the retrieval accuracy of the present algorithm is quite similar to published algorithms for oligotrophic and mesotrophic ocean waters. But for Kd(490) > 0.25 m−1, the NN approach allows to retrieve Kd(490) with a much better accuracy than the four other methods. The results are consistent when compared with other SeaWiFS wavelengths. This new inversion is as suitable in the open ocean waters as in the turbid waters. The work here is straightforwardly applicable to the MERIS sensor and with few changes to the MODIS-AQUA sensor. The algorithm in matlab and C code is provided as auxiliary material.
Systematic errors in the simulation of european climate (1961–2000) with RegCM3 driven by NCEP/NCAR reanalysis

Systematic errors of a European climate simulation (1961–2000) with RegCM3 were analyzed. Model results were compared to Climate Research Unit (CRU) observations. Average (AveB) and annual cycle biases (CycB) were evaluated for three surface variables: air temperature (TMP), water vapor pressure (VAP), and precipitation (PRE). The model shows a cold AveB over Europe with the exception of the northern part. It also shows a prevailing wet AveB. Annual PRE is underestimated only in regions with high average values, while VAP is overestimated over the entire European continent. The AveB is between − 1.2 °C and + 1.0 °C for TMP, 0.4 mb and 1.4 mb for VAP and − 15% and + 33% for PRC on annual/subcontinental scale. Most of the TMP and VAP CycB is related to the amplitude of annual cycle (CycA). The CycA of the TMP is underestimated over most of Europe. The CycA of the VAP is underestimated in some coastal regions and overestimated over the continental regions. The distinction between coastal and inland regions can also be seen in the CycB of the PRE. In coastal regions, with a PRE maximum in late autumn/early winter and minimum in summer, the CycA is underestimated. In some continental regions, with a precipitation maximum in summer and minimum in late autumn/early winter, the CycA is overestimated. The annual cycle pattern is not captured well by RegCM3 over the Alps and European Russia. Most of systematic errors in the RegCM3 simulation can be related to boundary conditions. Although the bias in NCEP/NCAR reanalysis is reflected in RegCM3 simulation, the RegCM3 enriches large‐scale information with regional details and with the more realistic description of annual cycles, especially for PRE. Because of these advantages and the overall relatively good performance of RegCM3, the model is seen as a valuable tool in regional projections of future climate change. Copyright © 2006 Royal Meteorological Society
Dominating Controls for Wetter South Asian Summer Monsoon in the Twenty-First Century

AbstractThis paper analyzes a suite of global climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) archives to understand the mechanisms behind a net increase in the South Asian summer monsoon precipitation in response to enhanced radiative forcing during the twenty-first century. An increase in radiative forcing fuels an increase in the atmospheric moisture content through warmer temperatures, which overwhelms the weakening of monsoon circulation and results in an increase of moisture convergence and therefore summer monsoon precipitation over South Asia. Moisture source analysis suggests that both regional (local recycling, the Arabian Sea, the Bay of Bengal) and remote (including the south Indian Ocean) sources contribute to the moisture supply for precipitation over South Asia during the summer season that is facilitated by the monsoon dynamics. For regional moisture sources, the effect of excessive atmospheric moisture is offset by weaker monsoon circulation and uncertaint.
Factors controlling sediment yield in China's Loess Plateau

The Loess Plateau in China, an area with some of the highest sediment yield in the world, contributes predominant proportion of the sediments found in the Yellow River. We examined sediment yield and its control variables in the plateau based on a multi‐year dataset from 180 gauging stations in areas varying in size from 102 to 104 km2. Various morphometric, hydrologic, climatic and land cover variables were estimated in order to understand and predict the variations in sediment yield. The results show a spatial pattern of sediment yield exhibiting an obvious zonal distribution and a coupling between precipitation and vegetation cover that fits the Langbein–Schumm law. A critical threshold of precipitation and vegetation cover was observed among the relationships of sediment yield and precipitation/vegetation cover. A multiple regression equation with three control variables, i.e. vegetation cover, percentage of cultivated loess and annual runoff, explains 65% of the total variation in sediment yield. For the loess dominated basins, where the cultivated loess accounts for more than 60% of the total area, annual runoff was the dominant variable, explaining 76% of the observed variation in sediment yield. The established equation could be a valuable tool for predicting total sediment yield in the Loess Plateau. Copyright © 2010 John Wiley & Sons, Ltd.