Miracle-dz/UniFAR-FTUs huggingface dataset:
Beryllium 10/beryllium 7 as a tracer of stratospheric transport

We use the ratio between cosmogenic radionuclides beryllium 10 (t1/2 = 1.5×106 years) and beryllium 7 (t1/2 =53 days) to study stratospheric transport, particularly the exchange between the tropics and the high latitudes and as an indicator of stratosphere-troposphere exchange. Both tracers are generated steadily, with maximum production occurring at midlatitudes of the stratosphere. During transport away from their source the ratio 10Be/7Be increases and thus acts as a clock for air mass age. According to model (GISS GCM) calculations, the tropics is a reservoir of high-ratio air with the high magnitude of 10Be/7Be partly a consequence of air mixed in from higher latitudes. The observations of Dibb et al. [1994] show a vertical maximum in 10Be/7Be in the lower arctic stratosphere during the spring of 1989; model results qualitatively reproduce this maximum and suggest that it may result from transport of tropical air to high latitudes during winter. The model ratio values are not so large as in these observations, possibly due to either excessive leakage into the troposphere near the pole or to insufficient transport from the tropical stratosphere to the pole. Beryllium 10 and 7Be observations, combined with model analysis, can be a useful indicator of transport processes in the troposphere/stratosphere system.
Barrier Layers in the Tropical South Atlantic: Mean Dynamics and Submesoscale Effects*

AbstractBarrier layers are generated when the surface mixed layer is shallower than the layer where temperature is well mixed, in geographical regions where salinity plays a key role in setting up upper-ocean density stratification. In the tropical oceans, thick barrier layers are also found in a latitude range where spiraling trajectories from surface in situ drifters suggest the presence of predominantly cyclonic submesoscale-like vortices. The authors explore these dynamical processes and their interplay in the present paper, focusing on the tropical South Atlantic Ocean and using a high-resolution modeling approach. The objective is threefold: to investigate the mean dynamics contributing to barrier-layer formation in this region, to study the distribution and seasonality of submesoscale features, and to verify whether and how the submesoscale impacts barrier-layer thickness. The model used is the Regional Ocean Modeling System (ROMS) in its Adaptive Grid Refinement in Fortran (AGRIF) online-nested co.
Flow of variably fluidized granular masses across three‐dimensional terrain: 1. Coulomb mixture theory

Rock avalanches, debris flows, and related phenomena consist of grain-fluid mixtures that move across three-dimensional terrain. In all these phenomena the same basic forces govern motion, but differing mixture compositions, initial conditions, and boundary conditions yield varied dynamics and deposits. To predict motion of diverse grain-fluid masses from initiation to deposition, we develop a depth-averaged, three-dimensional mathematical model that accounts explicitly for solid- and fluid-phase forces and interactions. Model input consists of initial conditions, path topography, basal and internal friction angles of solid grains, viscosity of pore fluid, mixture density, and a mixture diffusivity that controls pore pressure dissipation. Because these properties are constrained by independent measurements, the model requires little or no calibration and yields readily testable predictions. In the limit of vanishing Coulomb friction due to persistent high fluid pressure the model equations describe motion of viscous floods, and in the limit of vanishing fluid stress they describe one-phase granular avalanches. Analysis of intermediate phenomena such as debris flows and pyroclastic flows requires use of the full mixture equations, which can simulate interaction of high-friction surge fronts with more-fluid debris that follows. Special numerical methods (described in the companion paper) are necessary to solve the full equations, but exact analytical solutions of simplified equations provide critical insight. An analytical solution for translational motion of a Coulomb mixture accelerating from rest and descending a uniform slope demonstrates that steady flow can occur only asymptotically. A solution for the asymptotic limit of steady flow in a rectangular channel explains why shear may be concentrated in narrow marginal bands that border a plug of translating debris. Solutions for static equilibrium of source areas describe conditions of incipient slope instability, and other static solutions show that nonuniform distributions of pore fluid pressure produce bluntly tapered vertical profiles at the margins of deposits. Simplified equations and solutions may apply in additional situations identified by a scaling analysis. Assessment of dimensionless scaling parameters also reveals that miniature laboratory experiments poorly simulate the dynamics of full-scale flows in which fluid effects are significant. Therefore large geophysical flows can exhibit dynamics not evident at laboratory scales.
Dating of a muskox (Ovibos moschatus) skull fragment from Jämtland, Sweden: Middle Weichselian age

A radiocarbon age determination of a tundra muskox (Ovibos moschatus) skull fragment from Jämtland, central Sweden gave an age of 44 000 ± 1500 14C years BP or c. 46–49 cal. ka, indicating that the species was a member of the Middle Weichselian fauna of Sweden. The age confirms that central Sweden was ice-free during parts of the Middle Weichselian, prior to the last glacial maximum, as shown by previous studies. The region was probably characterised by treeless arctic to subarctic tundra environments.
Expansion of LISS III swath using AWiFS wider swath data and contourlet coefficients learning

Spaceborne sensors have limited capability to acquire images with wider swath at high spatial and high temporal resolutions simultaneously. This study reports a ground processing technique that combines images from two sensors onboard Resourcesat-2 (RS2) Linear Imaging and Self-Scanning Sensor (LISS III) and an Advanced Wide-Field Sensor (AWiFS) to overcome this limitation. The spatial resolution of LISS III is 23.5 × 23.5m and that of AWiFS is 56 × 56m. The temporal resolution of LISS III is 24 days and that of AWiFS is 5 days. The 140-km swath of the LISS III overlaps at center portion of 740-km swath of AWiFS in simultaneous acquisition. Assume that the nonoverlapping region of the AWiFS contains similar Earth’s surface features of the LISS III overlapping region; then, it is possible to enhance the spatial resolution of AWiFS to the spatial resolution of LISS III in the nonoverlapping region. With this assumption, we propose a novel technique to enhance the spatial resolution of the nonoverlapping region through a single-image super-resolution technique using nonsubsampled contourlet transform (NSCT) and evaluated it on RS2 data-sets. The proposed method can create a synthetic image with 740-km swath at 23.5 × 23.5m spatial and 5-day temporal resolutions. Experimental results demonstrated that it outperforms the support vector regression (SVR)-based methods in prediction accuracy and computational time.
Flow splitting modifies the helical motion in submarine channels

Intricately meandering channels of various scales constitute a major morphological feature of the submarine slope and fan systems. These channels act as conduits of density‐driven gravity underflows and in turn are shaped by these underflows. The relationship between channel curvature and the dynamics of sediment‐laden underflows commonly known as turbidity current has been an enigma, and recently, a subject of controversy. This contribution unravels the flow field of turbidity current at submarine channel bends captured from large scale laboratory experiments. The experimental results show that a mildly sloping channel bank greatly enhances the tilt of the turbidity current‐ambient water interface, so much so that the current completely separates from the convex or the inside bank. We also show that irrespective of the shape of the channel cross section, two cells of helical flow appear in confined submarine bend flow. The near‐bed cell has a circulation pattern similar to that observed in fluvial channels; the other cell has an opposite sense of rotation. If, on the other hand, a portion of the flow detaches from the body of the current and spills to the concave or outside overbank area, the upper circulation cell becomes suppressed by the resulting lateral convection.
Simulation of Ground Motion and Synthetic Seismograms. The 1908 Messina Earthquake.

We design a numerical algorithm for wave simulation in anelastic media in the presence of free surface, which can be used to model seismic waves at the Earth's surface. The modeling simulates 3-D waves by using the Fourier and Chebyshev methods to compute the spatial derivatives along the horizontal and vertical directions, respectively. The stress-strain relation is based on the Kelvin-Voigt mechanical model, which has the advantage of not requiring additional field variables. The model is based on two anelastic parameters and twice the spatial derivatives of the lossless case. The methodology is illustrated by simulating the Messina 1908 earthquake.
Analysis of DNA methylation in young people reveals limited evidence for an association between victimization stress and epigenetic variation in blood

words) Objective: To test if victimization stress is associated with genome-wide DNA methylation. DNA methylation has been proposed as an epigenetic mechanism by which early-life experiences become “embedded” in the genome and alter transcriptional processes to compromise health. Method: We tested the hypothesis that victimization is associated with DNA methylation in the Environmental Risk (E-Risk) Longitudinal Study, a nationally representative 1994-1995 birth cohort of 2232 twins born in England and Wales and assessed at ages 5,7,10,12, and 18 years. Multiple forms of victimization were ascertained in childhood and adolescence (including physical, sexual and emotional abuse, neglect, exposure to intimate-partner violence, bullying, cyber- and crime victimization). Results: Epigenome-wide analyses of polyvictimization across childhood and adolescence revealed few significant associations with DNA methylation in peripheral blood at age 18 years, but these were confounded by tobacco smoking and/or did not survive co-twin control tests. Secondary analyses of specific forms of victimization revealed sparse associations with DNA methylation that did not replicate across different operationalizations of the same putative victimization experience. Hypothesis-driven analyses of six candidate genes in the stress response ( NR3C1, FKBP5 , BDNF, AVP, CRHR1, SLC6A4) did not reveal predicted associations with DNA methylation in probes annotated to these genes. Conclusion: Findings from this epidemiological analysis of the epigenetic effects of early-life stress do not support the hypothesis of robust changes in DNA methylation in victimized young people. We need to come to terms with the possibility that epigenetic epidemiology is not yet well matched to experimental, non-human models in uncovering the biological embedding of stress.
Early summer temperatures reconstructed from black pine (Pinus nigra Arnold) tree-ring widths from Albania

The first regional chronology of black pine (Pinus nigra Arnold) from Albania, its response to climate and a 428-year long reconstruction of June–July temperatures for the 1583–2010 period are presented. Samples were collected at five locations from the north to the south of Albania. We constructed a 552-year long Pinus nigra chronology with sufficient sample depth for potential climate reconstruction from 1583 to 2010 (428 years). Response to precipitation was significant only for July of the current year (0.23), while a clear temperature response to the May–August period was identified, with July having by far the highest correlation (−0.47). When combined, June–July temperatures had the highest correlation of all tested combinations (r = −0.63), explaining almost 40% of the tree-ring width variability. The test of the climate signal temporal stability using a 31-year running correlation highlighted the very stable relationship between tree-ring indices and June–July temperatures. The spatial extent of the regional Pinus nigra chronology tested, using a field correlation function, showed very high spatial correlation over a large part of the Balkan Peninsula and even southern Italy. Based on high explained variance between tree-ring indices and June–July temperatures and significant values of reduction of error (RE) and coefficient of efficiency statistics (CE; 0.62 and 0.25 in the calibration period), a linear model was developed, with June–July temperatures reconstructed for the 1583–2010 period. Our reconstruction and identified extreme years were compared with various temperature, drought and precipitation reconstructions from nearby regions, as well as data from documentary archives. We confirmed a high degree of similarity of our reconstruction with other reconstructions and documentary data.
Detecting and attributing nonlinear anthropogenic regional warming in southeastern Australia

[1] Nonlinear anthropogenic warming is detected and attributed as a series of step changes in observed and simulated climate for southeastern Australia (SEA). A stationary period of 1910–1967 and non-stationary period of 1968–2010 was established using statistically significant step-changes (pH0 < 0.01) in the relationship between observed minimum (Tmin) and maximum (Tmax) temperature (0.6°C in 1968) and Tmax and rainfall (P; 0.7°C in 1997). Regressions between these pairings during stationary conditions were used to determine how Tmin and Tmax would have evolved under non-stationary conditions. Assuming these relationships remain constant, the resulting residuals were attributed to anthropogenic regional warming. This warming was initiated as step changes in 1968 forTmin (0.7°C) and 1973 for Tmax (0.5°C), coinciding with step changes in zonal (24–44°S) and southern hemisphere mean air temperatures (Tav). A step change in 1997 in Tmax (0.8°C) coincided with a statistically significant step change in global mean air temperature of 0.3°C. This analysis was repeated using regionally averaged output from eleven climate model simulations. Regional warming in all models commenced with step changes in Tmin ranging from 0.4 to 0.7°C between 1964 and 2003. Tmax underwent step changes ranging from 0.7 to 1.1°C simultaneously or within several decades. Further step changes, combined with rising trends, were simulated under increasing radiative forcing to 2100. This highlights limitations in the current use of the signal-to-noise model that considers anthropogenic climate change as a monotonic curve. The identification of multiple step changes in a changing climate provides important information for planning adaptation.
Reduction of magnetic and gravity data on an arbitrary surface acquired in a region of high topographic relief; discussion

In their paper, Bhattacharryya and Chan address the problem of reduction of magnetic and gravity data on an arbitrary surface acquired in a region of high topographic relief. In their work, the authors are kind enough to mention our contribution to the solution of the problem of finding the sources responsible for an observed magnetic or gravity anomaly, using the general formalism of inverse problems (Courtillot et al, 1974). Unfortunately, however, the authors seem to be unaware of our other publications which are far more relevant to their subject. Courtillot et al (1973) solved the problem of continuation of a potential field measured on an uneven profile, using the Backus and Gilbert approach. Another reference relevant to this problem (solved by Bhattacharryya and Chan on p. 1424) is Parker and Klitgord (1972), who used the Schwartz‐Christoffel transformation. The work was extended to the case of three‐dimensional potential fields measured on an uneven surface by Ducruix et al (1974). Indeed, the de.
Determination of critical shear stress of non‐cohesive soils using submerged jet test and turbulent kinetic energy

Laboratory tests using Jet Erosion Testing (JET) apparatus, impinging normally on a horizontal boundary, were conducted to determine the critical shear stress (τc) of non‐cohesive soil samples. A three‐dimensional (3D) SonTek/YSI 16 MHz Micro‐Acoustic Doppler Velocimeter (MicroADV) was used to measure turbulent kinetic energy (TKE) at a radial limit of entrainment in the wall jet zone and the measurements were used to calculate τc of the samples. The results showed that TKE increases exponentially with increasing particle size. The τc from this study were comparable (R2 = 0.8) to the theoretical τc from Shields diagram after bed roughness scale ratio (D/ks), due to the non‐uniform bed conditions, was accounted for. This study demonstrated that JET and TKE can be used to determine τc of non‐cohesive soils. The use of JET and TKE was found to be faster and easier when compared to the conventional approach of using flumes. A relationship of TKE at the onset of incipient motion (TKEc) and samples’ D50 developed in this study can be used to predict τc of non‐cohesive soils under similar non‐uniform conditions. Copyright © 2015 John Wiley & Sons, Ltd.
Titan's stratospheric composition driven by condensation and dynamics

[1] Atmospheric transport of chemical compounds and organic haze in the stratosphere of Titan is investigated with an axisymmetric general circulation model. It has been shown previously that the meridional circulation, dominated by global Hadley cells, is responsible both for the creation of an intense stratospheric zonal flow and for the accumulation of chemical compounds and haze in high latitudes. The modified composition in turn intensifies the meridional circulation and equator-to-pole thermal contrasts. This paper analyzes in detail the transport processes responsible for the observed vertical and latitudinal variations of atmospheric composition. It is shown that the competition between rapid sinking of air from the upper stratosphere in the winter polar vortex and latitudinal mixing by barotropic planetary waves (parameterized in the model) controls the vertical gradient of chemical compounds. The magnitude of polar enrichment (of a factor 1.4 to 20 depending on the particular species) with respect to low latitudes is mostly controlled by the way the meridional advection increases the concentrations of chemical compounds in the clean air which is rising from the troposphere, where most of the chemical compounds are removed by condensation (the temperature at the tropopause being close to 70 K). The agreement between the observed and simulated contrasts provides an indirect but strong validation of the simulated dynamics, thus confirming the explanation put forward for atmospheric superrotation. It is shown also that by measuring the atmospheric composition, the Cassini-Huygens mission will provide a strong constraint about Titan's atmospheric circulation.
MJO and its relationship to ENSO

[1] In this study, we detected the spatial and temporal characteristics of Madden-Julian Oscillation (MJO) using zonal winds at the surface and outgoing long-wave radiation (OLR) from the NCEP-NCAR (U.S. National Center of Environmental Prediction-National Center for Atmospheric Research) reanalysis product from 1981–2003. The results show that MJO activity, represented by these two variables, has large variances around 10° off the equator and over the near-equatorial western Pacific. One central issue addressed in this study is MJO-ENSO (El Nino and Southern Oscillation) relationship. It has been found that there exists a statistically significant relationship between MJO in spring-summer and ENSO in autumn-winter. The relationship of MJO-ENSO is nonlinear in nature and has a decadal variation. A much stronger statistical relationship of MJO-ENSO was found in the 1990s as compared to that in the 1980s. These findings were further verified using ECMWF (European Center for Medium-Range Weather Forecasts) reanalysis product. The potential mechanisms responsible for MJO-ENSO relationship are also discussed.
Variation of solar cyclicity during the Spoerer Minimum

[1] We investigate the 11-year solar cycle during the Spoerer Minimum (1415–1534 A.D.) by measuring the carbon 14 content in the annual tree rings for the period 1413–1554 A.D. The period of the Spoerer Minimum is assumed to be a prolonged sunspot minimum like the Maunder Minimum (1645–1715 A.D.). However, the 11-year solar cycle, which appears in recent solar variations, was also prominently detected in the carbon 14 record during this period. The amplitude of the 11-year cycle seems to have been modulated only around 1455–1510 A.D.
Using CloudSat Cloud Retrievals to Differentiate Satellite-Derived Rainfall Products over West Africa

AbstractDaily precipitation retrievals from three algorithms [the Tropical Rainfall Measuring Mission 3B42 rain product (TRMM-3B42), the Climate Prediction Center morphing technique (CMORPH), and the second version (RFEv2) of the Famine Early Warning System (FEWS)] and CloudSat retrievals of cloud liquid water, ice amount, and cloud fraction are used to document the cloud structures associated with rainfall location and intensity in the West African monsoon. The different rainfall retrieval approaches lead to contrasting cloud sensitivities between all three algorithms most apparent in the onset period of June and July. During the monsoon preonset phase, CMORPH produces a precipitation peak at around 12°N associated with upper-level cirrus clouds, while FEWS and TRMM both produce rainfall maxima collocated with the tropospheric–deep convective cloud structures at 4°–6°N. In July similar relative displacements of the rainfall maxima are observed. Conditional sampling of several hundred convection systems p.
System Dynamics Approach for Hydropower Generation Assessment in Developing Watersheds: Case Study of Karkheh River Basin, Iran

AbstractIn many watersheds around the world where the importance of assessing a watershed as a whole is overlooked, new water resources projects are designed solely based on historic flow data. Such projects might fail to operate satisfactorily when designed without considering the uncertainties associated with future hydrologic changes. In this study, a system dynamics model (SDM) is developed to quantify the potential hydrologic impacts of future developments in parts of the Karkheh River basin, Iran, and assess their effects on hydroelectricity generation of existing and projected hydropower plants. Results indicate that upstream development could reduce future annual energy production by 254 GWh. Interbasin water transfer from the nearby Sirvan River basin to the Karkheh River basin was also investigated as a viable option to increase future energy production. Simulation results revealed that an average 88 GWh/year increase in electricity production can be achieved per 100×106 m3 of annual environme.