bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of Hyporheic Nitrate Removal at the Reach Scale: Exposure Times versus Residence Times
Authors: Frei Sven , Gilfedder Benjamin , Durejka Stefan , Thomas Zahra , Le Lay Hugo
Published: March 2020

The rate of biogeochemical processing associated with natural degradation and transformation processes in the hyporheic zone (HZ) is one of the largest uncertainties in predicting nutrient fluxes. We present a lumped parameter (LPM) model that can be used to quantify the mass loss for nitrate in the HZ operating at the scale of river reaches to entire catchments. The model is based on using exposure times (ET) to account for the effective timescales of reactive transport in the HZ. Reach scale ET distributions are derived by removing the portion of hyporheic residence times (RT) associated with flow through the oxic zone. The model was used to quantify nitrate removal for two scenarios: 1) a 100 m generic river reach and 2) a small agricultural catchment in Brittany (France). For the field site hyporheic RT are derived from measured in-stream 222Rn activities and mass balance modelling. Simulations were carried out using different types of RT distributions (exponential, power-law and gamma-type) for which ET were derived. Mass loss of nitrate in the HZ for the field site ranged from 0-0.45 kg d-1 depending on the RT distribution and the availability of oxygen in the streambed sediments. Simulations with power law ET distribution models only show very little removal of nitrate due to the heavy weighting towards shorter flow paths that are confined to the oxic sediments.  Based on the simulation results, we suggest that ET likely lead to more realistic estimates for nutrient removal.
Magnetic properties of synthetic taenite at high pressure
Authors: McCammon Catherine , Wei Qingguo , Gilder Stuart
Published: March 2020

Taenite, an iron-nickel alloy with 20-40 at% nickel, is a major constituent of iron meteorites that have been used to infer planetary core compositions. Many aspects of its magnetic properties are controversial, particularly near the Invar (“invariable”) composition around 36 at% nickel. Open questions include the conditions under which magnetism is lost, so to address this particular controversy, we undertook a combined magnetic remanence and Mössbauer study of synthetic taenite at high pressure. We synthesised polycrystalline iron-nickel alloy with 38 at% nickel, loaded the sample into a diamond anvil cell and collected Mössbauer spectra during decompression from 20 GPa. Our results show a clear loss of magnetism, but at pressures that differ considerably depending on the fitting model. The pressure obtained using the traditional approach involving a magnetic field distribution conflicts with results obtained from other methods, while a simple model based on magnetic field fluctuations gives results that are consistent with other data. Comparison of data from all methods provides insight that can be applied to planetary magnetism.
Atmospheric Rivers over the Arctic with the ICON model
Authors: Bresson Hélène , Rinke Annette , Schemann Vera , Crewell Susanne , Viceto Carolina , Gorodetskaya Irina
Published: March 2020

The Arctic climate changes faster than the ones of other regions, but the relative role of the individual feedback mechanisms contributing to Arctic amplification is still unclear. Atmospheric Rivers (ARs) are narrow and transient river-style moisture flows arriving from the sub-polar regions. The
integrated water vapour transport associated with ARs can explain up to 70% of the precipitation variance north of 70°N. However, there are still un-

certainties regarding the specific role and the impact of ARs on the Arctic climate variability.

For the first time, the high-resolution ICON modelling framework is used over the Arctic region (from 13 km down to ca. 6 and 3 km) to investigate processes related with anomalous moisture transport into the Arctic. Based on a case study for Svalbard, the representation of the atmospheric circulation and the spatio-temporal structure of water vapour, temperature, and precipitation and snowfall within the limited-area mode (LAM) of the ICON model is assessed. Preliminary results show that the moisture intrusion is relatively well represented in the ICON-LAM simulations. The impact on the surface energy budget will also be calculated.
Pomeranian Bolide
Authors: Ciechowska Helena , Fronczak Aleksandra , Karasewicz Maciej , Mocek Klaudia , Zawadzki Mikołaj , Grad Marek
Published: March 2020

October 31st of 2015 the bolide lightened up the sky above Northern Poland. The main purpose of the project  was to define the place and time of its explosion in Earth’s atmosphere. To calculate these values and define the velocity of acoustic wave in the air, MATLAB model has been created. The model was based on seismic records of the event from GKP permanent seismological station and few stations of temporary array 13 BB star, arrival time of the wave to each station was read from seismograms. Using this data it was possible to indicate the narrowed area on plane where the explosion could take place. Next step was to model elevated point of explosion, time of the explosion, and the velocity of sonic wave in Earth’s atmosphere for spherical Earth 3D model, needed for the wave to travel from the point of explosion to seismological station.
Mixing induced by ISWs breaking over a sloping boundary: an analytical heuristic model
Authors: Cavaliere Davide , la Forgia Giovanni , Falcini Federico
Published: March 2020

We propose an analytical approach to estimate mixing efficiency in Internal Solitary Waves (ISWs) breaking processes. We make use of the theoretical framework of Winters et al. [1995] to describe the energetics of a stratified fluid flow, calculating the Available Potential Energy (APE) of an ISW of depression in a two-layer system, assuming that the symmetric density structure on both sides of the feature is exactly the same. Starting from the definition of mixing efficiency given by Michallet and Ivey [1999], through the Ozmidov and Thorpe length-scales we derive an expression for the mixing efficiency avoiding the use of any wave model (as KdV-type models or strongly nonlinear models) to estimate the wave energy. The model is successfully verified through laboratory experiments performed in a wave tank and is meant to be applied by using real field CTD casts.

 

References:

Winters, K., Lombard, P., Riley, J., and D’Asaro, E. (1995). Available potential

energy and mixing in density-stratified fluids. J. Fluid Mech., 289, 115-128.

Michallet, H. and Ivey, G. (1999). Experiments on mixing due to internal solitary

waves breaking on uniform slopes. Journal of Geophysical Research: Oceans,

104(C6), 13467-13477
Effects of strain weakening in self-consistent models of mantle convection with plate-like behavior and continental drift
Authors: Rolf Tobias , Arnould Maëlis
Published: March 2020

It is now well-established that the Earth’s mantle and lithosphere form an integrated, dynamically self-regulating system. Numerical convection models that self-consistently generate plate-like behavior are a powerful tool to investigate this system, but have only recently reached a level at which they can be linked to the geodynamics of the Earth. Strongly temperature-dependent and viscoplastic rheology is known to be a key ingredient for these models to be successful. Such rheologies, however, are typically time-independent and lack a memory on the previous history of deformation. Yet, it is known that the Earth’s geodynamic evolution is somewhat guided by structures of pre-existing weakness, which was initiated a potentially long time before.

As a step forward we implement a simple form of rheological memory in the mantle convection code StagYY: strain weakening [Fuchs & Becker, 2019, Role of strain-dependent weakening memory on the style of mantle convection and plate boundary stability, Geophys. J. Int., 218, 601-618]. We present calculations in 2D cases with and without continents, and also selected 3D cases. By varying the governing parameters for plate-like behavior as well as the rates of rheological damage and healing, we examine how strain weakening modifies the generation of plate-like behavior and its time dependence as well as the drift of continents.

First results indicate the importance of the balance of weakening (via the critical strain) and thermal healing. The averaged cumulative strain (effectively the degree of lithospheric weakening) is lower when healing is more effective, so that plastic failure of the lithospheric and the formation of new plate boundaries is complicated, as expected. In initial models with strong, long-living continents, accumulated strain is very small within the continents and seems insufficient to induce substantial weakening, even if the memory on previous deformation is infinite (i.e. no healing with continents). Further models with weaker continents and different rheological parameters will be presented.
Seismic wide-angle constrains on the structure of the northern Sicily margin and Vavilov Basin: implications for the opening of the Tyrrhenian back-arc basin
Authors: Grevemeyer Ingo , Ranero Cesar , Zitellini Nevio , Sallares Valenit , Prada Manel
Published: March 2020

The Tyrrhenian Sea in the central Mediterranean Sea was form by Neogene slab roll-back of the retreating Ionian slab about 6 to 2 Myr ago. Yet, little is known about the structure of its southern margin off Sicily as well as back-arc extension and spreading in the southern Tyrrhenian Sea to the north of Sicily. The Sicilian margin is generally classified as a passive margin bounding a young back-arc basin. However, focal mechanisms from regional earthquakes suggest that the margins suffers presently from compressional tectonics. New seismic refraction and wide-angle data were collected along seismic profile WAS4 during the CHIANTI survey of the Spanish research vessel Sarmiento de Gamboa in 2015. The profile runs from the centre of the Tyrrhenian Sea – the Vavilov Basin – across the margin of Sicily, approaching the Gulf of Castellammare to the northwest of Sicily. Reanalyzed multi-channel seismic data supports compressional tectonics across a small basin paralleling the coastline of Sicily, revealing recent inversion of the Tyrrhenian Basin. Offshore of Sicily WAS4 indicates a roughly 120-140 km wide domain showing seismic P-wave velocities characteristic for continental crust (Vp ~4-6.7 km/s) and a base of crust defined by a wide-angle Moho reflection. Continental crust reaches a maximum thickness of 22 km to the north of the Gulf of Castellammare and is thinning to ~9 km to the north of the Ustica Ridge. The compressional belt occurs in continental crust to the south of Ustica Ridge. In the Vavilov Basin, a lithosphere was sample where seismic P-wave velocity increases from approx. 3-4 km/s to 7.5 km/s. This velocity depth-distribution clearly shows profound similarities to serpentinized mantle and hence un-roofed mantle. Thus, seismic constrains support results from Ocean Drilling Program (ODP) hole 651A, which sample serpentinized peridotites in the Vavilov Basin. The transition between serpentinized mantle and continental crust is rather abrupt. Thus, within a ~10 km wide transitional domain, continental crust with a thickness of~ 9 km is juxtaposed against un-roofed mantle. All available data from the Tyrrhenian Sea support wide-spread mantle exhumation in the Vavilov Basin. Therefore, the Tyrrhenian Sea provides a rather different structure when compared to marginal basins in the Western Pacific and hence may not have supported a mid-ocean ridge-type spreading system opening the basin.
Global assimilation of ocean-color data of phytoplankton functional types: Impact of different datasets
Authors: Nerger Lars , Pradhan Himansu , Völker Christoph , Losa Svetlana , Bracher Astrid
Published: March 2020

Satellite phytoplankton functional type (PFT) data is assimilated into the global coupled ocean-ecosystem model MITgcm-REcoM2 for two years using a local ensemble Kalman filter. The ecosystem model has two PFTs: small phytoplankton (SP) and diatoms. Three different sets of satellite PFT data are assimilated: OC-PFT, PhytoDOAS, and SynSenPFT, which is a synergistic product combining the independent PFT products OC-PFT and PhytoDOAS. The effect of assimilating PFT data is compared with the assimilation of total chlorophyll data (TChla). This constrains both PFTs through multivariate assimilation using ensemble-estimate cross-covariances. While the assimilation of TChla already improves both PFTs individually, the assimilation of PFT data further improves the representation of the phytoplankton community. The effect is particularly large for diatoms where, compared to the assimilation of TChla, the SynSenPFT assimilation results in 57% and 67% reduction of root-mean square error (RMSE) and bias, respectively, while the correlation is increased from 0.45 to 0.54. For SP the assimilation of SynSenPFT data reduces the RMSE and bias by 14% each and increases the correlation by 30%. This shows that satellite data products beyond total chlorophyll are relevant for biogeochemical data assimilation. The separate assimilation of the PFT data products OC-PFT, SynSenPFT, and joint assimilation of OC-PFT and PhytoDOAS data lead to similar results while the assimilation of PhytoDOAS data alone leads to deteriorated SP but improved diatoms. When both OC-PFT and PhytoDOAS data are jointly assimilated, the representation of diatoms is improved compared to the assimilation of only OC-PFT. The results show slightly lower errors than when the synergistic SynSenPFT data is assimilated, which shows that the assimilation successfully combines the separate data sources.
Identification of marine litter accumulation areas in estuaries
Authors: Núñez Paula , García Andrés , Abascal Ana J. , Mazarrasa Inés , Bárcena Javier F. , Chiri Helios , Rodriguez-Castillo Tamara , Juanes José A. , Medina Raúl
Published: March 2020

Marine litter is one of the main threats for the marine environment, causing significant damage at ecological, economic and social levels. Approximately, 80% of the marine litter comes from land-based sources, mainly from rivers. A significant percentage of this litter reaches the open oceans and the rest are retained inside the estuaries. The mechanisms that favor the marine litter accumulation inside the estuaries are determined by the interactions between the tide, the river flow, the waves, and the wind, as well as by the physical features of the estuary. In addition, tides and waves can contribute to the introduction of litter from marine sources. Therefore, estuaries frequently act as sinks for marine litter. In this study, a methodology to identify the most probable areas of marine litter accumulation inside estuaries is developed. The methodology is based on numerical modeling and statistical analysis and consists of 4 fundamental steps. First, a series of metocean scenarios (tidal conditions, river flow, waves, and wind), statistically representative of the studied estuary, are identified using the clustering algorithm K-means. Second, these conditions are used as forcing and boundary conditions of a hydrodynamic model to obtain the high spatial resolution currents and waves that determine the transport of litter. Third, with these high-resolution drivers, a Lagrangian transport model is fed to generate a database of potential marine litter trajectories from different litter-sources, where each litter-source is carefully selected according to the activity developed in the area. Finally, the statistical analysis of these trajectories allows identifying the most probable areas of marine litter accumulation. The efficacy of this methodology is demonstrated by its application to the Pas estuary (northern coast of Spain) by comparing the numerical results with field data. Results show that the greatest accumulations of marine litter take place in the curves that imply important changes in the direction of the flow, where the probabilities range between 20 and 30%, and that the distance to the litter-sources also plays a fundamental role.
Neoarchean tectonics: insight from the deformation of the Archean basement of North China Craton
Authors: Liu Yongjiang , Li Jing , Li Weimin , Li Sanzhong , Dai Liming
Published: March 2020

The controversy over the Archean tectonic regimes has lasted several decades focusing around horizontal and vertical tectonics, the two classical tectonic models for Archean times. Thus, more studies of the early crustal growth and tectonic evolution are requisite for better understanding geodynamic regimes in the early Precambrian. The North China Craton is one of the major Archean to Paleoproterozoic cratons in the world and oldest craton in China, which preserves a large amount of ancient basement and abundant structures showing the early earth tectonics.

In this study, we have carried out detailed structural analysis of two down-slip ductile shear zones which developed in eastern Anshan area and provided an example for revealing of Neoarchean vertical tectonics in the study area. There were also develop many structures of dome and keel style in the North China Craton, such as Qian ’an, Qingyuan areas.

Based on abundant structural evidence and previous studies, we infer that the vertical tectonics is still the dominant model for Neoarchean crust growth and tectonic evolution in Anshan area. The formation of dome and keel structure, and the deformation of the down-slip ductile shear zones may have resulted from the sagduction of the banded iron formations and synchronous Archean granite dome emplacement, supporting a vertical tectonic regime in Archean times.
Large eddy simulation of bed formation in subaqueous bedload
Authors: Zhao Chenwei
Published: March 2020

Large eddy simulation of incompressible turbulent flow over a loose bed of spherical particles are investigated in an open channel. Eulerian and Lagrangian point-particle methods is applied to solve the Navier-Stokes equations and particle motion respectively and the particle-flow interaction is also considered. A new method solving particle-particle collisions is utilized for the first time to reduce the computational time spending on calculating the pairwise distances between particles. A turbulent fluid condition from the experiment of Robert and Uhlman (2001) are chosen of which the corresponding sediment patterns are ‘ripple’. Flow over the formed bed is considered and it is found that double-averaged Reynolds stresses including shear stress and three normal stresses reach their peak values near the bed. However, affected by the movable bed, they decay quickly as the height increases. The flow direction slightly rises over the stoss-side of ripples and falls after the crest and the velocity magnitude of time-averaged flow accelerate and decelerate before and after the crest of ripples as well. Hence, recirculation zones and clockwise vorticity appear at the trough of the bed where kolk boil vortices like hairpins and elongated streamwise vortices is also evident. Coherent structures, in the form of high- and low-speed streaks near the bed are also affected by the bed formation. The near-bed low-speed streaks entrain into the main flow domain over the stoss-side of ripples and the high-speed fluid streaks from the main flow rush toward the bed over the leeside of ripples. The bedload transport rate is well represented by previous empirical formulas. The bed surface elevation changes from upstream to downstream with time and there is a difference in the direction of sediment transport which is obvious three-dimensionality. In addition, it is also found that the bed surface elevation shows a positive correlation with particle streamwise velocity and entrainment rate which means higher bed elevation leads to larger bedload transport rate.
Analysis of a typical heavy dust pollution weather in Semi-arid region- A Case Study in Eastern Qinghai
Authors: guo xiaoning , ma yuancang
Published: March 2020

 Based on conventional meteorological observation data and particulate matter monitoring data, combined with traceability of pollution sources, the main causes of sand-dust heavy pollution and the characteristics of dust transmission in eastern Qinghai in May 2019 were analyzed by using the principles of meteorology and trajectory analysis.The results show as following：The heavy dusty weather is mainly affected by the development of the enhanced low-slot eastward of Lake Baikal. The low-slots carry strong cold air moving eastward ,leading to heavy pollution in the eastern part of Qinghai. During the dusty weather, the cold air from the Hexi Corridor was poured into the eastern part of Qinghai from the valley . The dust from Gansu Province entered and then transported from east to west to easdtern Qinghai,causing pollution. The presence of the inversion layer stabilizes the atmospheric stratification in the eastern boundary layer of Qinghai, which is not conducive to the outward spread of pollutants caused by surface turbulence activities. The long-term maintenance of dust that cannot be diffused in time is the main cause of heavy pollution. In the early stage of sand and dust weather, the humidity conditions in the eastern part of Qinghai gradually deteriorated. Before the sand-dust occurred, the sensible heat on the ground increased significantly. The water vapor in the atmosphere weakened, the air was dry, and the water vapor condition, which is an important condition for the formation of sand and dust,was poor. The dust storm transmission route affecting the eastern part of Qinghai is transmitted from southeast to northwest. The mixed layer height and static weather index of the EC numerical forecasts have a good predictive indication during the process. The results of the trajectory analysis also indicate that the dusty weather in the eastern part of Qinghai (Xining, Haidong, etc.) was caused by backward irrigation of sandfrom the Hexi Corridor, and affected Haidong and Xining areas under the influence of the terrain.
SOLSTICE: Space Weather Modeling Meets Machine Learning
Authors: Gombosi Tamas ,   SOLSTICE Team
Published: March 2020

The last decade has truly witnessed the rise of the machine age. The enormous expansion of technology that can generate and manipulate massive amounts of information has transformed all aspects of society. Missions such as SDO and MMS, and numerical models such as the Space Weather Modeling Framework (SWMF) are now routinely generating terabytes of science data, far beyond what can be analyzed directly by humans. Fortunately, concurrent with this explosion in information has come the development of powerful capabilities, such as machine learning (ML) and artificial intelligence (AI), that can retrieve revolutionary new understanding and utility from the massive data sets. 

SOLSTICE (Solar Storms and Terrestrial Impacts Center) is a recently selected NASA/NSF DRIVE Center. It will serve as the vanguard for developing and applying ML methods, which will then raise the capabilities of the entire community. We will combine next generation ML technology with our world-leading numerical models and the exquisite data from the space missions to make breakthrough advances in Heliophysics understanding and space weather capabilities, and then transition our technology to the CCMC for the benefit of all.

We use ML to attack Grand Challenge Problems that cover the major aspects of space weather science: (i) use interpretable deep learning models, archived solar observations and high-performance physics-based simulations to identify the onset mechanism of solar flares and coronal mass ejections; and (ii) use high-cadence observations and physics-based feature learning to predict solar storms many hours before eruption, training time-to-event models to predict event times and flare magnitudes using innovative machine learning techniques.
Landslides and Geophysics: a review of the advantages and limitations on the basis of the last twelve years open access international literature
Authors: Morelli Stefano , Pazzi Veronica , Fanti Riccardo
Published: March 2020

Given a landslide, which are the constituent materials? How are the material inhomogeneities distributed? Which are their properties? What are the deformation processes? How large are the boundaries or how depth is/are the slip surface/s? Answering these questions is not a simple goal. Therefore, since the ‘70s, the international community (mainly geophysicists and lower geologists and geological engineers) has begun to employ, together with other techniques, active and passive geophysical methods to characterize and monitor landslides. Both the associated advantages and limitations have been highlighted over the years, but some drawbacks are still open.

On the basis of the more recent landslides classification by Hungr et al. dated 2014, an analysis of about 120 open access papers published in international journals between the 2007 and the 2018 has been carried out. The aim of this review work was to evaluate the geophysical community efforts in overcoming the geophysical technique limitations highlighted in the conclusion section of the review of 2007 by Jongmans and Garambois. These drawback can be summarized ad follow: 1) geophysicists have to make an effort in the presentation of their results; 2) the resolution and the penetration depth of each method are not systematically discussed in an understandable way; 3) the geological interpretation of geophysical data should be more clearly and critically explained; 4) the challenge for geophysicists is to convince geologists and engineers that 3D and 4D geophysical imaging techniques can be valuable tools for investigating and monitoring landslides; and 5) efforts should also be made towards obtaining quantitative information from geophysics in terms of geotechnical parameters and hydrological properties

Moreover, the review work highlighted that the most studied landslides are those of the flow type and fall type for the “soil” and “rock” category, respectively. From the “employed method” point of view, active and passive seismic methods are the most employed in landslide characterization and monitoring. The latest method is also able to remotely detect events that might otherwise go unnoticed for weeks or months, and therefore, it is widely employed. The three more frequently applied techniques to characterize and monitor the slope deformation are electrical resistivity tomography, seismic noise, and seismic refraction. Finally, the main conclusion is that independently of the applied technique/s or the landslide type, a very accurate and high-resolution survey could be performed only on a small landslide portion, as it is costly and time-consuming, even though geophysical techniques are defined as cost and time effective compared to traditional field methods.
Large-Scale Migration Patterns of Wastewater-Induced Earthquakes in the Central U.S.
Authors: Johann Lisa , Shapiro Serge A.
Published: March 2020

It is understood that the recent acceleration of seismic event occurrences in Kansas and Oklahoma, U.S., can be connected to the large-volume disposal of wastewater. These highly saline fluids are co-produced with oil and gas and are re-injected under gravity into the highly porous Arbuckle aquifer. Since 2015, injection rates have been decreasing. However, the seismic hazard in that region remains elevated. Furthermore, it has been noticed that some events in Kansas occur far from disposal wells.

To analyse spatio-temporal patterns between the fluid injection and earthquake locations, we applied a time-dependent 2D cross-correlation technique. This reveals a vectorial migration pattern of the seismic events. Whereas early events occur towards the east-sourtheast, later events are located preferably in northeastern direction of large volume injectors. With time, event locations migrate further in that direction. We explain this observation as well as measured Arbuckle pore pressures by a directional pore-fluid pressure diffusion and poroelastic stress propagation. This also follows from our principal two-dimension poroelastic finite element model which is of predictive power and identifies controlling parameters of the observations. These are mainly the permeability of the target injection formation and the seismogenic basement as well as the anisotropic permeability and the critical fault strength distribution. Our results lead to the conclusion that remote locations are destabilised also when injection rates are declining.

Thus, volume reductions may only provide a direct effect to lower earthquake rates locally. However, a state-wide decrease of the seismicity may require longer times such that the seismic hazard due to wastewater disposal induced seismicity may remain for decades. 
The upper Messinian-lowermost Pliocene out-of-sequence event in the southern Apennines (Italy): a study about the kinematics of the major thrust faults
Authors: Ciarcia Sabatino , Prinzi Ernesto Paolo , Tramparulo Francesco D’Assisi , Vitale Stefano
Published: March 2020

The southern Apennines are a fold-and-thrust belt formed since the lower Miocene until the middle Pleistocene (e.g., Vitale and Ciarcia, 2013). Although a wide literature exists about the geology of this orogenic chain, few are the studies about the kinematics of the major thrusts. With this in mind, this work is aimed to investigate the out-of-sequence regional thrust system exposed in the Campania region. This system is characterized by a frontal ramp exposed along the N-NE side of the platform carbonate ridge forming the regional mountain backbone. The main structure is also exposed as a flat thrust in the Campagna and Giffoni tectonic windows located in the internal sector of the chain. We analyzed several outcrops; in some of them, we observed the Mesozoic carbonates superposed onto the upper Miocene wedge-top basin deposits of the Castelvetere Group. The kinematic analysis of major and minor structures suggests the occurrence of two thrust fault sets: (i) the oldest indicates an eastward tectonic vergence, whereas (ii) the youngest, and more developed, toward the north. In the external zones, the N-S shortening was synchronous with the deposition of the upper Messinian-lowermost Pliocene Altavilla Fm. The origin of this out-of-sequence regional deformation is still matter of debate (e.g., Vitale et al., 2017). In our opinion it was the shallow expression of a deep-seated thrusting episode within the buried Apulian slab. It was dominated by thrust ramps (thick-skinned tectonics) mainly verging to East, and by the N-verging structures associated to lateral ramps.

References

Vitale Stefano and Ciarcia Sabatino (2013) - Tectono-stratigraphic and kinematic evolution of the southern Apennines/Calabria-Peloritani Terrane system (Italy). Tectonophysics, 583, 164–182.

Vitale Stefano, Tramparulo Francesco d'Assisi, Ciarcia Sabatino, Amore F. Ornella, Prinzi Ernesto Paolo and Laiena Fabio (2017) - The northward tectonic transport in the southern Apennines: examples from the Capri Island and western Sorrento Peninsula (Italy). International Journal of Earth Sciences (Geologische Rundschau), 106, 97–113.
Evaluation of CMIP6 simulations of temperature extremes using proper evaluation methods, observations and reanalyses
Authors: Thorarinsdottir Thordis , Sillmann Jana , Haugen Marion
Published: March 2020

Climate models aim to project future changes in important drivers of climate including atmosphere, oceans and ice, and their interactions. A comprehensive evaluation of climate models thus requires evaluation methods, or performance measures, that are flexible, specific and can address also extreme events. Climate models have traditionally been assessed by comparing summary statistics or point estimates that derive from the simulated model output to corresponding observed quantities using e.g. RMSE. However, it has been argued persuasively that probability distributions of model output need to be compared to the corresponding empirical distributions of observations or observation-based data products. Observation-based gridded datasets for climate extremes, despite having limitations, are particularly useful and necessary to assess model performance with respect to extremes.  We discuss proper performance measures for comparing distributions of model output against corresponding distributions from data products that are flexible and robust enough to handle the particular aspects of extremes such as limited data availability. The new measures are applied to evaluate CMIP5 and CMIP6 projections of extreme temperature indices over Europe and North-America against the HadEX2 data set as well as the ERA5 and ERA-Interim reanalyses. Several models perform well to the extent that when compared to the HadEX2 data product, these models' performance is competitive with the performance of the reanalysis. While the model rankings vary with region, season and index, the model evaluation is robust against changes in the grid resolution considered in the analysis. 
From the field-scale Aquacrop model to a regional gridded crop model: initial evaluation over Europe
Authors: de Roos Shannon , de Lannoy Gabriëlle , Raes Dirk
Published: March 2020

The pressure on soil and water resources to support the demand for crop production calls for effective water management at the regional scale and a need for regional crop models.

In our study, the field-based Aquacrop v.6.1 is modified to a gridded crop model that is run spatially over the main part of Europe at 1-km resolution.

The gridded model simulates spatially distributed soil moisture, crop biomass and yield, given spatial input of meteorological forcings extracted from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) and 1-km soil texture information from the Harmonized World Soil Database v1.2 (HWSD v1.2). For the first model evaluation, a hypothetical and uniform crop is implemented, and field management and irrigation practices are not included. We will present preliminary results over Europe by comparing the spatial soil moisture and biomass simulations with remote sensing data.

This work is part of the SHui project, a H2020 project that aims at improving stakeholder decision-making for water scarcity management in European and Chinese cropping systems.
Uptake and surface chemistry of SO2 on natural Icelandic volcanic dusts under simulated atmospheric conditions
Authors: Urupina Darya , Romanias Manolis , Thevenet Frederic , Lasne Jerome
Published: March 2020

Volcanic dust (v-dust) is a highly variable source of natural particles in the atmosphere, and during the period of high volcanic activity it can provide a large surface for heterogeneous interactions with other atmospheric compounds. With an area of 103,000 km2, Iceland is the biggest volcanic desert on earth. It was chosen as a case study due to frequency of volcanic eruptions and high aeolian activity in the area. This is a comprehensive study of the heterogeneous reactivity of Icelandic volcanic dust with sulfur dioxide (SO2) gas. First, we focused on the kinetics of the reaction of SO2 with natural v-dust samples under atmospheric conditions using coated wall flow tube reactor. Steady-state uptake coefficients were measured to represent the long-term phenomena of the processing of aerosols in the atmosphere and the values obtained can be directly incorporated in chemical transport modeling. Second, the mechanism of the reaction of SO2 with natural v-dust samples was studied using infrared Fourier transform spectroscopy (DRIFTS). Both sulfites and sulfates were observed on the surface of v-dust, with sulfates being the final oxidation product, attesting to SO2 heterogeneous reactivity. Surface hydroxyl groups were found to play a crucial role in the conversion of SO2 to sulfates as evidenced from both flow tube and DRIFTS experiments. Based on these experimental results, a mechanism for SO2 interaction with different surface sites of v-dust was proposed and discussed. Third, in order to monitor the amount of sulfites and sulfates formed on the surface of mineral dusts of different origins a simple, accurate and precise reversed-phase liquid chromatography method was developed and validated to stabilize and analyze sulfites and sulfates in the extract of dusts exposed to SO2. Besides SO2 gas, v-dust reacts with other atmospheric pollutants, such as NO2 and O3, proving that heterogeneous processes play an important role in the atmospheric chemistry. One must keep in mind that as a result of such transformations, such properties as ice nucleation and optical properties might change as well soliciting further investigation of heterogeneous reactivity of Icelandic v-dusts.
The topographic pattern of the Sudetes and the tectonic message it conveys
Authors: Migon Piotr , Jancewicz Kacper , Różycka Milena , Szymanowski Mariusz
Published: March 2020

The Sudetes in Central Europe are part of an intraplate belt of highlands and mountains that extends north of the Alps, being also the highest (1602 m a.s.l.) and one of topographically most complex geomorphic units within this belt. The Sudetes consist of numerous semi-isolated mountain massifs, dissected uplands, intramontane troughs and basins, forming a seemingly disordered patchwork of high and low relief. This topographic pattern has developed upon lithologically diverse bedrock, suggesting at least some degree of superposition of different controls. Although specific areas within the Sudetes were subject to analysis focused on the recognition of tectonic imprint in the present-day topography, attempts to disentangle this landscape complexity across the entire Sudetes range were rare and largely inconclusive. Here we approach the problem from the perspective of multidimensional analysis of regional topography, using high-resolution digital elevation data as the primary background material. The building blocks used in the exercise are spatial distribution of altitude and relief, spatial pattern of erosional (dissection) hot spots, position of the main water divide and second-order divides, geometry of main mountain fronts, spatial distribution of surfaces of low relief, considered as inherited planation surfaces, selected features of the regional drainage pattern such as the position of gorges, dominant directions, geometric anomalies etc., and spatial pattern of intramontane basins. Topography is compared with lithology, following an assumption that high strength of a rock unit may also result in considerable elevation and relief, without the necessity to have active tectonics involved. An overlay of these various topographic features allows us to propose intra-regional differentiation of the Sudetes into units typified by different topographic signatures and to separate relief features, both linear and areal, primarily controlled by uplift and subsidence from those reflecting other controls. As an end-result, tectonic interpretation of the contemporary topography is offered.
The nutations of a rigid Mars
Authors: Baland Rose-Marie , Yseboodt Marie , Le Maistre Sébastien , Rivoldini Attilio , Van Hoolst Tim , Dehant Véronique
Published: March 2020

The nutations of Mars are about to be estimated with unprecedented accuracy (a few milliarcseconds) with the radioscience experiments RISE (Rotation and Interior Structure Experiment, Folkner et al. 2018) and LaRa (Lander Radioscience, Dehant et al. 2020) of the InSight and ExoMars 2020 missions, allowing to detect the contributions due to the liquid core and tidal deformations and to constrain the interior of Mars.

To properly identify the non-rigid contribution, an accurate precession and nutation model for a rigidly behaving Mars is needed. We develop such a model, based on the Torque approach, and include the forcings by the Sun, Phobos, Deimos, and the other planets of the Solar System, as well as geodetic precession and nutations. Both semi-analytical developments (for the Solar and planetary torques) and analytical solutions (for Phobos and Deimos torques and the geodetic precession and nutations) are considered.

We identify 43 nutation terms with an amplitude above the chosen truncation criterion of 0.025 milliarcseconds in prograde and/or retrograde nutations. Uncertainties related to modelling choices are negligible in comparison to the uncertainty coming from the observational uncertainty on the current determination of the precession rate of Mars (7608.3+/-pm2.1 mas/yr, Konopliv et al. 2016). Our model predicts a dynamical flattening HD=(C-A)/C=0.00538017+/-0.00000148 and a normalized polar moment of inertia C/MR2=0.36367+/-0.00010 for Mars.

References:
Folkner et al., 2018. doi: 10.1007/s11214-018-0530-5.
Dehant et al., 2020. doi: 10.1016/j.pss.2019.104776.
Konopliv et al., 2016. doi: 10.1016/j.icarus.2016.02.052.
Factors driving the Mediterranean water cycle from a cold and wet glacial past to a warm and dry future
Authors: Lionello Piero , D'Agostino Roberta
Published: March 2020

Model simulations of the last glacial maximum (LGM) and RCP8.5 projections suggest that factors responsible for past and future changes in the Mediterranean region are different.  The wet LGM conditions were determined mainly by low evaporation, with some increase of precipitation in the western areas, while dry rcp8.5 conditions will be driven by a reduction of precipitation over the whole region. These changes were caused by atmospheric dynamics (changes of mean atmospheric circulation ) in LGM and it will be caused by the atmospheric thermodynamics (reduction of mean moisture content ) in the future rcp8.5. In both cases, the Mediterranean region appears to be more sensitive to climate change than the rest of areas within the same latitudinal range, particularly considering the hydrological cycle, whose characteristics in winter exhibit large changes between these two different climates. These conclusions emerge from the substantial consensus among six PMIP3 and CMIP5 models, simulating LGM, pre-Industrial and rcp8.5 climate conditions.
Quantify the regional methane emissions based on a new SCIAMACHY data set
Authors: Liu Mengyao , Van der A Ronald , Tan Haiyue , Frankenberg Christian , Aben Ilse , Kong Hao , Sun Jiyunting , Ding Jieying , Zhang Lin
Published: March 2020

Methane (CH4) is the most important anthropogenic greenhouse gas after carbon dioxide, and it keeps increasing globally since 2007 after a period of relative stability, which is well-documented by surface measurements and satellites. Although satellites provide long-term global observations of CH4, the interpretation of column-averaged mixing ratios (xCH4) is difficult due to the influence of elevated terrains (i.e. mountain areas) and less abundant methane in the stratosphere. The lack of data over the ocean further limits global insights. Here we build a long-term global CH4 data set at a resolution of 0.25° × 0.25°  from SCIAMACHY, including the areas over the ocean, with the help of FRESCO cloud data. We dynamically consider the influence of elevations and contributions from the stratosphere through converting xCH4 to tropospheric xCH4 (trop_xCH4) by applying the daily ratios of tropospheric to stratospheric xCH4 in GEOS-Chem model.

The large increases occur in Trop_xCH4 over the source regions and mountain areas. The trend of SCIAMACHY Trop_xCH4 over the global ocean is comparable to the trend of NOAA globally averaged marine monthly mean data, showing the capability of SCIAMACHY in monitoring the ocean. After removing the latitudinally independent background concentration based on SCIAMACHY data over the ocean, we quantify the regional sources. A significant trend in Trop_ xCH4 relating to the background in Eastern China, India, tropical Africa, and tropical South America is further found from 2003 to 2011. 
Assessing the impacts of climate variability - a study of institutional archival data spanning 1700-1947 (British Colonial Period) pertaining to semi-arid tracts of peninsular India
Authors: Ray Ranjini , Bhattacharya Atreyee
Published: March 2020

Climate disasters such as droughts and floods are becoming very important in 21st century India especially in the semi-arid tracts of rain-shadow regions of peninsular India – stretching from Maharashtra in the west to Tamil Nadu in the south. The role of climate variability in these climate disasters and the climate forcings working behind these needs a special attention. Here we present new data, pertaining to climate disasters, impacts and adaptive strategies, from a review of 60 volumes of archival institutional documents from the British Colonial Period pertaining to administration of districts of peninsular India. The documents span ~ 220 years (1729-1947 AD) and encompass the two phases of the British colonial period, the Company period (before 1858) and the Crown period (1858-1947) respectively. We found archival institutional documents to be excellent archives for reconstructing a chronology of climate disasters, studying the effects of these disasters and assessing the efficacy of adaptive strategies and policies at local scales, often at the level of districts (<30 kms). Vivid accounts describe impacts of climate disasters e.g crop failure, price hike, farmer migration, riot, starvation, epidemic diseases, death during droughts, and colossal destruction, migration and death due to heavy rainfall (and associated floods). Farmers being the most affected group. In 19th century famines due to droughts continued to occur every 5-10 years if the rainfall fell below 14% of the average annual rainfall, consistent with decadal and sub-decadal modes of rainfall variability. This data is comparable with the tree ring data found in this area. Climate variability is to some extent at par with ENSO events but land atmosphere interaction especially due to anthropogenic activities such as deforestation can be a major climate forcing that acted in this area. During the Crown period protective measures were very similar even though governance changed. But British government had to change their policies when sudden huge fall in rainfall occurred in 1876 and 1899 causing major famines (Great Famine 1876-1877, Indian Famine1899-1900). Formation of Famine Codes and Famine Commissions (1880-1901) after these two major famines made situation better, changes were done in grass root level. We see no major famine caused by droughts in peninsular India after that.