Miracle-dz/UniFAR-FTUs huggingface dataset:
Mapping mantle flow during retreating subduction: Laboratory models analyzed by feature tracking

[1] Three-dimensional dynamically consistent laboratory models are carried out to model the large-scale mantle circulation induced by subduction of a laterally migrating slab. A laboratory analogue of a slab–upper mantle system is set up with two linearly viscous layers of silicone putty and glucose syrup in a tank. The circulation pattern is continuously monitored and quantitatively estimated using a feature tracking image analysis technique. The effects of plate width and mantle viscosity/density on mantle circulation are systematically considered. The experiments show that rollback subduction generates a complex three-dimensional time-dependent mantle circulation pattern characterized by the presence of two distinct components: the poloidal and the toroidal circulation. The poloidal component is the answer to the viscous coupling between the slab motion and the mantle, while the toroidal one is produced by lateral slab migration. Spatial and temporal features of mantle circulation are carefully analyzed. These models show that (1) poloidal and toroidal mantle circulation are both active since the beginning of the subduction process, (2) mantle circulation is intermittent, (3) plate width affects the velocity and the dimension of subduction induced mantle circulation area, and (4) mantle flow in subduction zones cannot be correctly described by models assuming a two-dimensional steady state process. We show that the intermittent toroidal component of mantle circulation, missed in those models, plays a crucial role in modifying the geometry and the efficiency of the poloidal component.
A study of blanketing sporadic E at middle latitudes

The average daytime behavior of midlatitude blanketing sporadic E is studied on a worldwide basis. The hourly values of ƒbEs obtained at over 80 stations in 1958 have been statistically analyzed to yield the latitudinal, seasonal, and diurnal variations of ƒbEs, and of the occurrence frequency of ƒbEs ≥ 2.0 Mc/s. The results show that ƒbEs varies on the average in step with ƒoE in all seasons at all latitudes, suggesting a strong dependence of ƒbEs on the local ƒoE value during daytime. The occurrence frequency of blanketing sporadic E shows two daytime maxima in local summer and a single afternoon maximum in local winter; further, it exhibits a rather complex latitudinal variation and considerable irregular fluctuations. It is shown that all the main characteristics of daytime blanketing sporadic E can be explained on the basis of the wind shear theory.
Estimating the potential role of commercial over‐harvesting in resource viability: a case study of five useful tree species in South Africa

There is a growing commercialization of non‐timber forest products (NTFPs) as a means of livelihood by rural communities throughout the developing world. This often occurs in the absence of any clear understanding of or guidelines regarding sustainable yields and ecological impacts, which may undermine the success of NTFP enterprises, especially from arid regions. This paper reports on the use of size class profiles and three quantitative indices to examine population profiles of five potentially useful tree species used as NTFPs in the semiarid lowveld of South Africa. We also contrast the population densities of the five tree species in 2003 with data from 1992. Low stem densities and population profiles indicated that three of the five species would preclude the establishment of NTFP enterprises based on their products. The other two species seem to have sufficient densities for some harvesting to take place, within an adaptive management framework. However, the longitudinal data indicated that the density of both these species had significantly declined over an eleven‐year period, highlighting the need for appropriate management institutions. Additionally, the proportion of mature stems cut, and the degree of cutting per stem, had increased for all five species over the eleven years. The three quantitative indices of population stability were not correlated with one another, and hence provided a useful suite of measures sensitive to different aspects of size class profiles and their interpretation. Copyright © 2005 John Wiley & Sons, Ltd.
Quantification of m(Lg) for Small Explosions

Abstract : This report focuses on a USGS data set from refraction surveys within the State of Maine. These data contain excellent recordings of short period Rayleigh waves (Rg) generated by the explosions. The initial intent was to use these data to characterize shear wave velocity and Q in the upper 1-2 km in this environment of folded paleozoic sediments. However the data set permitted other interesting studies. First, significant lateral changes in the moveout of the Rg, S and P wave were observed. Analysis techniques were developed to successfully invert for a laterally varying earth structure and to model the Rg waveforms, both in terms of absolute amplitude and phase. Second, the shear wave velocity model derived from the surface waves, was used in a blind test to predict the S-wave arrival times for two profiles having significant S waves. An excellent fit was obtained without having used the S-wave data in the inversion for the earth model, indicating the ability of the 1-4 Hz surface wave data to resolve shear wave velocity structure to depths of 2 km in this environment. Finally, since absolute instrument gains were known, forward modeling was used to compare the observed and estimated amplitude decay in different frequency bands. This permitted an estimation of the isotropic moment for these one ton explosions. By comparing estimates made in different portions of the 1-5 Hz frequency band, we conclude that a step source time function in moment is adequate to model the surface wave observations for these one ton shots. The estimated isotropic moments are similar to other chemical yield-moment observations. However, larger industrial chemical blasts, e.g., 100 ton or greater, would be expected to show a frequency dependence in the isotropic moment estimate because of the distributed source dimensions.
THE INFLUENCE OF MAGNESIUM AND OF EASILY WEATHERED MINERALS ON HYDRAULIC CONDUCTIVITY CHANGES IN A SODIC SOIL

Summary Exchangeable Mg appears to have no specific effect on soil hydraulic conductivity of A and C horizons of a sodic sandy loam soil (montmorillonite and kaolinite clay minerals) leached with solutions which cause clay swelling to be the dominant mechanism reducing conductivity (SAR < 20, electrolyte concentration 10 meq per litre). There is some evidence of a specific effect when these soils are subsequently leached with water which causes clay dispersion to become important. Fresh loess in the A horizon dissolves in percolating rainwater, causing difficulties in the replication of experiments. It seems to give a small degree of ‘self protection’ to soil structure, a property likely to be operating in other soils affected by recent loess deposits.
The planet Mars - From antiquity to the present

Telescopic observations of Mars, from those of Galileo in 1610 to the late 19th century, were summarized by Flammarion (1892, 1909). Major compilations of knowledge of Mars were produced by Antoniadi (1930) and de Vaucouleurs (1954). Polar cap composition was debated until the discovery by the Viking mission that the north and south perennial polar caps are composed of different materials. Spacecraft data indicate a rich and diverse geologic history as well as many unsolved puzzles. An annotated list of books about Mars is provided. Basic physical and chemical data on Mars are summarized in tabular form, and a guide to the Martian seasons is given.
Seasonal dependence of the long‐range transport and vertical distribution of free tropospheric aerosols over east Asia: On the basis of aircraft and lidar measurements and isentropic trajectory analysis

[1] Seasonal changes in the vertical structure of free tropospheric aerosols over east Asia, on the basis of aircraft-borne and lidar measurements, and on the pathway of the long-range transport of Asian dust particles inferred from isentropic trajectory analysis are discussed. Aircraft-borne measurements held in situ in the free troposphere over central Japan in 2000–2001 revealed a small in scale yet steady transport of dust in the lower-middle free troposphere (2–6 km altitude) during spring including days with no evident dust outbreak. Such dust, found as background, was observed even in summer in the regions higher than 4 km under the influence of remaining westerly winds but not in the lower regions. From a series of lidar observations over Nagoya (35°N, 137°E), Japan, noticeable changes in aerosol characteristics were obtained in the free troposphere from spring to summer. Taklimakan desert is suggested as possible important source of the background dust.
Mars atmospheric phenomena during major dust storms, as measured at surface

Meteorological instrumentation aboard the Viking Mars Landers measures wind, temperature, and pressure. Two global dust storms occurred during northern autumn and winter, observed both by the orbiters and by the landers. The meteorological data from the landers has been analyzed for the period just before first storm arrival to just after second storm arrival, with the objectives being definition of meteorological phenomena during the storm period, determination of those associated with storm and dust arrival, and evaluation of effects on synoptic conditions and the general circulation. Times of dust arrival over the sites could be defined fairly closely from optical and pressure (solar tide) data, and dust arrival was also accompanied by changes in diurnal temperature range, temperature maxima, and temperature minima. The arrivals of the storms at VL-1 were accompanied by significant increase in wind speed and pressure. No such changes were observed at VL-2. It is possible that surface material could have been raised locally at VL-1. Throughout the period except following the second dust storm the synoptic picture at VL-2 was one of eastward moving cyclonic and anticyclonic systems. These disappeared following the second storm, a phenomenon which may be related to the storm.
High‐resolution spectroscopy of the lunar sodium exosphere

We have applied high‐resolution Fabry‐Perot spectroscopy to the study of the lunar sodium exosphere for the study of exospheric effective temperature and velocity variations. Observing from the National Solar Observatory McMath‐Pierce Telescope, we used a dual‐etalon Fabry‐Perot spectrometer with a resolving power of 180,000 to measure line widths and Doppler shifts of the sodium D2 (5889.95 Å) emission line. Our field of view was 360 km, and measurements were made in equatorial and polar regions from 500 km to 3500 km off the limb. Data were obtained from full moon to 3 days following full moon (waning phase) in March 2009. Measured Doppler line widths within 1100 km of the sunlit east and south lunar limbs for observations between 5 and 40° lunar phase imply effective temperatures ranging between 3260 ± 190 and 1000 ± 135 K. Preliminary line center analysis indicates velocity displacements between different locations off the lunar limb ranging between 100 and 600 m/s from the lunar rest velocity with a precision of ±20 to ±50 m/s depending on brightness. Based on the success of these exploratory observations, an extensive program has been initiated that is expected to constrain lunar atmospheric and surface‐process modeling and help quantify source and escape mechanisms.
Socioeconomic and traditional importance of date palm.

The date palm fruit is a drupe exhibiting a high diversity in texture, shape, color and chemical composition depending on the genotype, environment, season and cultural practices. The fruit typically characterize the variety. The socio-economic value of dates is particularly known from oases, where date palms grow and fruits were historically the medium of exchange between populations. The geographical distribution of date palm cultivars is not yet well studied and the international demand on some of them will have disastrous impacts on the sustainability of this crop in the long term. This impoverishes germplasm and narrows the diversity grown among oases. In addition, despite the presence of several reports on the chemical composition and the nutritional value of dates, many other potentialities of the fruits remain to be explored. Many claims report on the antibacterial, antifungal, antitumor, antiulcer and immuno-modulatory properties of dates. Recently, the antioxidant activity of some cultivars was investigated and attributed to phenolic compounds. Dates are very rich in phenolics, in quality and quantity, which opens many fields of investigation in terms of new potential uses. This study summarizes the recent progress in date research, providing an up-to-date overview of the worldwide production/commercialization and the traditional and medicinal uses. Other current and future applications of dates also are highlighted.
Impacts of volumetric strain on CO2 sequestration in coals and enhanced CH4 recovery

Sequestration of CO2 into deep, unminable coal seams is an attractive option to reduce atmospheric emissions. However, coal seams commonly have low initial permeability, and CO2 adsorption causes the coal matrix to swell, which further reduces the permeability and may result in inefficient injection. We investigate numerically the impacts of coal swelling on coal permeability and, thus, CO2 injection efficiency with constraints determined by experimental adsorption-associated volumetric strain measurements on three western Canadian coals. Our results show that injecting pure CO2 markedly reduces permeability through time to the extent that it is not a feasible sequestration technology for almost all coals. However, injection of a gas mixture of N2 and CO2 (flue gas) markedly improved CO2 injection efficiency while mildly reducing CO2 sequestration capacity. The study also suggests that different geological settings and mechanical properties of specific coal seams strongly control coal seam permeability during gas injection and, thus, viability of CO2 sequestration.
Very low strengths of interplanetary meteoroids and small asteroids

Abstract– We have assembled data on 13 cases of meteorite falls with accurate tracking data on atmospheric passage. In all cases, we estimate the bulk strength of the object corresponding to its earliest observed or inferred fragmentation in the high atmosphere, and can compare these values with measured strengths of meteorites in the taxonomic class for that fall. In all 13 cases, the strength corresponding to earliest observed or inferred fragmentation is much less than the compressive or tensile strength reported for that class of stony meteorites. Bulk strengths upon atmospheric entry of these bodies are shown to be very low, 0.1 to approximately 1 MPa on first breakup, and maximal strength on breakup as 1–10 MPa corresponding to weak and “crumbly” objects, whereas measured average tensile strength of the similar meteorite classes is about 30 MPa. We find a more random relation between bulk sample strength and sample mass than is suggested by a commonly used empirical power law. We estimate bulk strengths on entry being characteristically of the order of 10−1–10−2 times the tensile strengths of recovered samples. We conclude that pre‐entry, meter‐scale interplanetary meteoroids are typically highly fractured or in some cases rubbly in texture, presumably as a result of their parent bodies’ collisional history, and can break up under stresses of a few megapascals. The weakness of some carbonaceous objects may result from very porous primordial accretional structures, more than fractures. These conclusions have implications for future asteroid missions, sample extraction, and asteroid hazard mitigation.
Porphyroblast–fabric relationships: an example from the Appin Group in the Glen Roy area

Synopsis The Neoproterozoic Grampian and Appin groups exposed in the Glen Roy area were deformed during an initial progressive tectono–thermal event of the Grampian orogeny. Prograde regional metamorphism to amphibolite facies accompanied deformation with the thermal peak coinciding with the second phase of folding (F2) and the imposition of an S2 crenulation to transposition fabric. In the pelitic to semipelitic schists of the Lochaber Subgroup (Appin Group), metamorphism resulted in the development of the assemblage: quartz + muscovite + biotite ± garnet, plagioclase (An 13 to 22%), staurolite and opaques. The complexity of porphyroblast–fabric relationships recorded from the schists varies systematically across the area and can be directly related to the intensity of S2. Six progressive stages of S2 crenulation cleavage development are recognized, preserved within multitextured, syn-kinematic garnet porphyroblasts. These stages show a progression from a planar S1 fabric to differentiated S2 crenulation cleavage, through to the development of a differentiated S2 transposition fabric. Porphyroblast–fabric relationships are further complicated by the localized reactivation of S1 in response to movement along the Grampian–Appin lithostratigraphic boundary during F2 folding. Biotite porphyroblasts developed early during the imposition of S2 and were subsequently deformed during D2 to form lenticular mica-fish. Staurolite (rare) nucleation and growth, representing peak metamorphism recorded by these schists, post–dated S2 development.
A Neoproterozoic glacially influenced basin margin succession and ‘atypical’ cap carbonate associated with bedrock palaeovalleys, Mirbat area, southern Oman

The Ayn Formation of the Neoproterozoic Mirbat Group comprises <400 m of little‐deformed, glacially influenced basin margin deposits. These deposits are preserved in several palaeovalleys eroded in crystalline basement and overlain by a discontinuous cap carbonate. The Ayn Formation and the cap carbonate, which are superbly exposed along a 20 km SW–NE‐striking escarpment in south Oman, provide important insights into the processes operating on a basin margin during a Neoproterozoic glaciation and its demise. The Ayn Formation comprises units of glacimarine rain‐out diamictite and sediment gravity flow deposits, alternated with units of fluvial and deltaic sandstones and conglomerates, which may have formed by proglacial outwash. The stratigraphic evolution of the Ayn Formation indicates a highly active hydrological cycle during a phase of overall (glacio‐eustatic? ) low stand when glaciers advanced into and receded upon bedrock valleys. The transgressive cap carbonate was deposited primarily in shallow marine or shallow lacustrine environments over palaeohighs during the deglaciation, and was partly reworked into deeper parts of the basin through sediment gravity flow processes. Locally, the cap carbonate transgresses over crystalline basement containing a network of fissures filled with carbonate originating from the cap. The δ13C isotopic composition of the cap carbonate varies systematically between −3.5 and +5.8‰ Pee Dee Belemnite standard, in common with other older Cryogenian examples.
Maintenance of the Arctic Ocean large-scale baroclinic structure by the M2 tide

A three-dimensional structure of the M2 tidal currents has been reproduced by mathematical modelling. The possibility of energy transfer from the tidal barotropic motion to large-scale baroclinic circulation of the Arctic Ocean has been estimated. It has been shown that the bottom relief plays an important role in the formation of the large-scale pattern of the baroclinic fields. The hypothesis has been proposed that the M2 tide may support the near-slope convection of the East-Siberian and Laptev seas. Polar Research13 (2), 219–232
Using Mean Flow Change as a Proxy to Infer Interdecadal Storm Track Variability.

Abstract Several recent studies, based mainly on analyses of reanalysis data, have suggested that the Northern Hemisphere storm tracks have intensified during the second half of the twentieth century. However, comparisons with rawinsonde observations over land areas suggest that eddy variance/covariance statistics may contain spurious jumps that had led to an exaggeration of the storm track secular trend. In this study, storm track variations are inferred from mean flow anomalies using canonical correlation analysis (CCA). A CCA model relating storm track anomalies to mean flow anomalies is derived using recent, more reliable data. The model is then applied to infer storm track anamalies using mean flow anomalies for earlier periods, when storm track analyses are deemed more suspect (or even nonexistent). Results of the CCA analyses suggest that the strong secular trend observed over the Atlantic basin and Europe is consistent with mean flow anomalies, while CCA predictions based on mean flow changes sugg.
Global upper-mantle tomography with the automated multimode inversion of surface and S-wave forms

SUMMARY We apply the Automated Multimode Inversion of surface and S-wave forms to a large global data set, verify the accuracy of the method and assumptions behind it, and compute an S vvelocity model of the upper mantle (crust‐660 km). The model is constrained with ∼51 000 seismograms recorded at 368 permanent and temporary broadband seismic stations. Structure of the mantle and crust is constrained by waveform information both from the fundamentalmode Rayleigh waves (periods from 20 to 400 s) and from S and multiple S waves (higher modes). In order to enhance the validity of the path-average approximation, we implement the automated inversion of surface- and S-wave forms with a three-dimensional (3-D) reference model. Linear equations obtained from the processing of all the seismograms of the data set are inverted for seismic velocity variations also relative to a 3-D reference, in this study composed of a 3-D model of the crust and a one-dimensional (1-D), global-average depth profile in the mantle below. Waveform information is related to shear- and compressional-velocity structure within approximate waveform sensitivity areas. We use two global triangular grids of knots with approximately equal interknot spacing within each: a finely spaced grid for integration over sensitivity areas and a rougher-spaced one for the model parametrization. For the tomographic inversion we use LSQR with horizontal and vertical smoothing and norm damping. We invert for isotropic variations in S- and P-wave velocities but also allow for S-wave azimuthal anisotropy—in order to minimize errors due to possible mapping of anisotropy into isotropic heterogeneity. The lateral resolution of the resulting isotropic upper-mantle images is a few hundred kilometres, varying with data sampling. We validate the imaging technique with a ‘spectral-element’ resolution test: inverting a published global synthetic data set computed with the spectral-element method using a laterally heterogeneous mantle model we are able to reconstruct the synthetic model accurately. This test confirms both the accuracy of the implementation of the method and the validity of the JWKB and path-average approximations as applied in it. Reviewing the tomographic model, we observe that low-S v-velocity anomalies beneath mid-ocean ridges and backarc basins extend down to ∼100 km depth only, shallower than according to some previous tomographic models; this presents a close match to published estimates of primary melt production depth ranges there. In the seismic lithosphere beneath cratons, unambiguous high velocity anomalies extend to ∼200 km. Pronounced low-velocity zones beneath cratonic lithosphere are rare; where present (South America; Tanzania) they are neighboured by volcanic areas near cratonic boundaries. The images of these low-velocity zones may indicate hot material—possibly of mantle-plume origin—trapped or spreading beneath the thick cratonic lithosphere.