The Campanian Ignimbrite and Codola tephra layers: Two temporal/stratigraphic markers for the Early Upper Palaeolithic in southern Italy and eastern Europe

Tephra layers from archaeological sites in southern Italy and eastern Europe stratigraphically associated with cultural levels containing Early Upper Palaeolithic industry were analysed. The results confirm the occurrence of the Campanian Ignimbrite tephra (CI; ca. 40 cal ka BP) at Castelcivita Cave (southern Italy), Temnata Cave (Bulgaria) and in the Kostenki–Borshchevo area of the Russian Plain. This tephra, originated from the largest eruption of the Phlegrean Field caldera, represents the widest volcanic deposit and one of the most important temporal/stratigraphic markers of western Eurasia. At Paglicci Cave and lesser sites in the Apulia region we recognise a chemically and texturally different tephra, which lithologically, chronologically and chemically matches the physical and chemical characteristics of the Plinian eruption of Codola; a poorly known Late Pleistocene explosive event from the Neapolitan volcanoes, likely Somma–Vesuvius. For this latter, we propose a preliminary age estimate of ca. 33 cal ka BP and a correlation to the widespread C-10 marine tephra of the central Mediterranean. The stratigraphic position of both CI and Codola tephra layers at Castelcivita and Paglicci help date the first and the last documented appearance of Early Upper Palaeolithic industries of southern Italy to ca. 41–40 and 33 cal ka BP, respectively, or between two interstadial oscillations of the Monticchio pollen record – to which the CI and Codola tephras are physically correlated – corresponding to the Greenland interstadials 10–9 and 5. In eastern Europe, the stratigraphic and chronometric data seem to indicate an earlier appearance of the Early Upper Palaeolithic industries, which would predate of two millennia at least the overlying CI tephra. The tephrostratigraphic correlation indicates that in both regions the innovations connected with the so-called Early Upper Palaeolithic – encompassing subsistence strategy and stone tool technology – appeared and evolved during one of the most unstable climatic phases of the Last Glacial period. On this basis, the marked environmental unpredictability characterising this time-span is seen as a potential ecological factor involved in the cultural changes observed.     

Time Evolution of Deformation Using Time Series of Differential Interferograms: Application to La Palma Island (Canary Islands)

Differential interferometry is a very powerful tool for detecting changes in the Earth’s crust where coherence conditions are good, but is difficult to employ in some volcanic areas due to dense vegetation. We apply two differential InSAR methods using the time series associated with the interferograms to perform a phase analysis on a data set for La Palma island (Canary Islands) from the ERS-1 and ERS-2 European Space Agency (ESA) satellites for the time period 1992 to 2000. Both methods involve choosing a master image from the database and creating a series of interferograms with respect to this image. The “Coherent Pixel Time Series” (CPTS) technique chooses pixels with good average coherence, aligns the unwrapped interferograms with a stable area and then performs an inversion to calculate the linear velocity to quantify the deformation. The Coherent Target Modeling (CTM) method calculates the temporal coherence of each pixel to identify stable targets and then determines the best velocity for each pixel by using a linear fit that maximizes the temporal coherence. Using these two methods we have been able to detect deformation on La Palma Island that has been previously undetectable by conventional InSAR methods. There is a roughly circular region on the Southern part of the island that is actively deforming at ~ −4 to −8 mm/yr. This region is located near the Teneguia valcano, the host of the last known eruption on La Palma in 1971. A thorough investigation of the possible sources for this deformation revealed that it was most likely created by a subsurface thermal source.     

Sedimentation patterns in the Selenga River delta under changing hydroclimatic conditions

The Selenga River delta (Russia) is a large (>600 km²) fluvially dominated fresh water system that transfers water and sediment from an undammed drainage basin into Lake Baikal, a United Nations Educational, Scientific, and Cultural Organization World Heritage Site. Through sedimentation processes, the delta and its wetlands provide important environmental services, such as storage of sediment‐bound pollutants (e.g., metals), thereby reducing their input to Lake Baikal. However, in the Selenga River delta and many other deltas of the world, there is a lack of knowledge regarding impacts of potential shifts in the flow regime (e.g., due to climate change and other anthropogenic impacts) on sedimentation processes, including sediment exchanges between deltaic channels and adjacent wetlands. This study uses field measurements of water velocities and sediment characteristics in the Selenga River delta, investigating conditions of moderate discharge, which have become more frequent over the past decades (at the expense of peak flows, Q > 1,350 m³ s^?1). The aims are to determine if the river system under moderate flow conditions is capable of supporting sediment export from the main distributary channels of the delta to the adjacent wetlands. The results show that most of the deposited sediment outside of the deltaic channels is characterized by a large proportion of silt and clay material (i.e., <63 μm). For example, floodplain lakes function as sinks of very fine sediment (e.g., 97% of sediment by weight < 63 μm). Additionally, bed material sediment is found to be transported outside of the channel margins during conditions of moderate and high water discharge conditions (Q ≥ 1,000 m³ s^?1). Submerged banks and marshlands located in the backwater zone of the delta accumulate sediment during such discharges, supporting wetland development. Thus, these regions likely sequester various metals bound to Selenga River sediment.     

Numerical analysis of the Black Sea currents and mesoscale eddies in 2006 and 2011

Two prognostic experiments taking into account real atmospheric forcing for 2006 and 2011 were carried out based on the eddy-resolving numerical model with a horizontal resolution of 1.6 km for the Black Sea. The main dynamic features such as the Rim Current, the Sevastopol, and Batumi anticyclones are reproduced in both experiments. The model results are confirmed via observation data. We accomplished the analysis of simulated circulation and energetics. The results demonstrate that both the vertical viscosity and vertical diffusion along with the energy inflow from the wind have been the main contributors to the annual and seasonal budgets of kinetic and potential energies of the Black Sea circulation. It is shown that two regimes of the Black Sea general circulation are implemented depending on a magnitude of wind contribution to the kinetic energy in winter. Intensive mesoscale eddy formation was observed along the Anatolian, Caucasian, and Crimean coasts. The analysis of the Black Sea circulation and eddy energetics allowed us to conclude that the generation and development of the mesoscale coastal eddies is associated with the barotropic instability in case of intensive coastal currents and is associated with both the barotropic and baroclinic instability in case of weak coastal currents.     

Increasing resolution of reverse‐time migration using time‐shift gathers

Reverse‐time migration has become an industry standard for imaging in complex geological areas. We present an approach for increasing its imaging resolution by employing time‐shift gathers. The method consists of two steps: (i) migrating seismic data with the extended imaging condition to get time‐shift gathers and (ii) accumulating the information from time‐shift gathers after they are transformed to zero‐lag time‐shift by a post‐stack depth migration on a finer grid. The final image is generated on a grid, which is denser than that of the original image, thus improving the resolution of the migrated images. Our method is based on the observation that non‐zero‐lag time‐shift images recorded on the regular computing grid contain the information of zero‐lag time‐shift image on a denser grid, and such information can be continued to zero‐lag time‐shift and refocused at the correct locations on the denser grid. The extra computational cost of the proposed method amounts to the computational cost of zero‐offset migration and is almost negligible compared with the cost of pre‐stack shot‐record reverse‐time migration. Numerical tests on synthetic models demonstrate that the method can effectively improve reverse‐time migration resolution. It can also be regarded as an approach to improve the efficiency of reverse‐time migration by performing wavefield extrapolation on a coarse grid and by generating the final image on the desired fine grid.     

Comparison of several high-order advection schemes for vertex-based triangular discretization

Ocean Dynamics - Possible extensions of the standard 3rd (upwind) and 4th (centered) order vertex-centered finite-volume advection schemes on unstructured triangular meshes are explored. A...     

Probing the Sunspot Atmosphere with Three-Minute Oscillations

We present a seismological method for probing the solar atmosphere above sunspot umbrae with three-minute oscillations. Our technique allows us to estimate both the vertical distance between atmospheric layers and the wave-propagation speed, without specifying any additional parameters, in particular, the phase speed of the wave or the emission formation heights. Our method uses the projected wave paths of slow magnetohydrodynamic waves that propagate through the atmospheric layers of different heights and are guided by the magnetic field. The length of the projected wave path depends upon the distance between the layers and the inclination angle of the magnetic field with respect to the line of sight, allowing us to estimate the distance between the layers from measured projected wave paths and the local magnetic-field vector. In turn, the wave-propagation delay registered at different heights allows for the calculation of the phase speed. We estimated the vertical distance between the emission layers at the temperature minimum (1600 Å) and transition region (304 Å), as well as the average phase speed above the sunspot umbrae, for three active regions. We found that the distance between the 1600 Å emission layer and the transition region above the sunspot umbrae lies in the range of 500?–?800 km. The average phase speed between these layers was found to be about 30 km?s^?1, giving a sound speed of 6 km?s^?1. The temperature between the layers has been roughly estimated as 3000 K and corresponds to the region of the temperature minimum. The results obtained are consistent with the semiempirical model of the sunspot-umbrae atmosphere by Fontenla et al. (Astrophys. J.707, 482, 2009).     

The evolution of superbubbles and the detection of Lyα in star-forming galaxies

The detection of Ly α emission in star-forming galaxies in different shapes and intensities (always smaller than predicted for case B recombination) has puzzled the astronomical community for more than a decade. Here we use two-dimensional calculations to follow the evolution of superbubbles and of the H  ii regions generated by the output of UV photons from massive stars. We show the impact caused by massive star formation in the ISM of different galaxies and we look at the conditions required to detect Ly α emission from a nuclear H  ii region, and the variety of profiles that may be expected as a function of time.     

Solar energetic particle events at the rise phase of the 23rd solar activity cycle registered aboard the spacecraft &;#x201C;INTERBALL-2&;#x201D;

The experiment with 10K-80 aboard the INTER-BALL-2 (which detects protons with energies &amp;gt; 7, 27&amp;#x2013;41, 41&amp;#x2013;58, 58&amp;#x2013;88, 88&amp;#x2013;180 and 180&amp;#x2013;300 MeV) registered six events of the solar energetic particle (SEP) increase. These events are during the initial rise phase of the 23rd solar activity cycle. Solar flares with the SEP generation are accompanied by coronal mass ejection (CME). Here we analyze the dynamics of the differential energy spectrum at different phases of the SEP increase.