bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasi-Objective Coherent Structures from Single Lagrangian Trajectories
Authors: Aksamit Nikolas , Bartos Alex Encinas , Haller George
Published: March 2021

Lagrangian coherent structures (LCS) provide a means to understand persistent flow features in an objective manner. There has been great success identifying and harnessing hyperbolic, elliptic, and parabolic structures in both oceanic and atmospheric flows. These approaches (e.g. FTLE, PRA, LAVD) rely on well resolved velocity information for the computation of the gradient of the flow map or vorticity deviation. Thus, for sparse data, such as that available from ocean drifters or atmospheric balloons, the quality of these methods quickly deteriorates. On the other hand, all elementary features of individual particle paths, such as velocity, acceleration, looping number, curvature and trajectory length, are non-objective, i.e., depend on the observer. To bridge this gap between LCS and sparse data, we derive measures of local material stretching and rotation that are computable from individual trajectories without reliance on other trajectories or on an underlying velocity field. Both measures are quasi-objective: they approximate objective (i.e., observer-independent) coherence diagnostics in frames satisfying a certain condition. We illustrate with several examples how our quasi-objective coherence diagnostics highlight elliptic and hyperbolic LCS, even from very sparse unstructured trajectory data. This approach shows great potential for expanding the possibilities of LCS applications through its simplicity, performance with sparse data, and enhanced computational efficiency.
MEMO2: MEthane goes MObile – MEasurements and MOdelling
Authors: Walter Sylvia , Röckmann Thomas ,   the MEMO2 Team
Published: March 2021

MEMO2 was a 4-years European Training Network with more than 20 collaborators from 7 countries. The project contributed significantly to the targets of the EU with a focus on methane (CH4). CH4 emissions are a major contributor to Europe’s global warming impact, and the official inventories of emissions and estimates derived from direct atmospheric measurement show significant discrepancies. However, effective emission reduction can only be achieved if sources are properly quantified, and mitigation efforts are verified. MEMO2 contributed to advanced combinations of measurement and modelling which are needed to achieve such quantification.

With respect to the recently released EU methane strategy and the implementation of independent verification of emissions by atmospheric measurements, we will present some examples of relevant results from MEMO2 up to now:

Urban CH4 emissions: We can now detect and quantify CH4 leaks in cities at the street-level with mobile nigh precision analysers. Similar studies have been carried out in >10 EU cities and in collaboration with interested network operators those measurements are ready to be rolled out at larger scale.

Oil and gas production: We carried out a large study in the oil and gas production region in Romania (ROMEO), with aircraft, drones and vehicles. The final results are close to publication and help to improve the emission verification.

Coal mining: In collaboration with CoMet, another science project, we quantified the CH4 emissions from the Upper Silesian coal mining area. The collaboration and its results contribute to the development of an independent and objective emission monitoring system

Modelling: Micro-scale plume modelling is significantly improved. Those models e.g. help to simulate a measurement day as we had during our field campaign in Romania and improve sampling and measurement strategies.
Investigating the Global Monsoon by networks of extreme rainfall events
Authors: Strnad Felix , Goswami Bedartha
Published: March 2021

A defining feature of the Earth’s climate is the annual variation of heavy precipitation and convergent wind circulation in the tropics and subtropics. This dominant mode of hemispherically distributed rainfall is often termed the 'global monsoon', comprising of regional monsoon systems on every continent. Monsoon regions are defined using annual precipitation differences and average seasonality rather than by the dynamical similarities of rainfall dynamics; they thus fail to (i) consider global patterns of extreme rainfall events (EREs), and (ii) take into account spatio-temporal similarities in timing and intensity of monsoonal circulation.

In this work, we investigate the dynamics of the Global Monsoon using the framework of complex networks derived from extreme rainfall events. In particular, we use time-delayed event synchronization applied to the GPCP rainfall dataset to first extract a network of global ERE teleconnections. We then identify regions with similar ERE patterns by applying on the global ERE network a Bayesian hierarchical clustering approach based on the stochastic block model.

Our work presents evidence to place different monsoon regions in a global context and therefore to describe them as a unified system with common underlying dynamics: Besides known teleconnections, our method captures various differently resolved representations of the global weather system. These range from a description containing two clusters separated by the hemispheric equator to a precise representation of distinguishable but connected monsoon regions. We argue that the global monsoon can be regarded as a hierarchical complex system into which regional monsoons are embedded in intermediate levels of the clustering hierarchy.
Differences in the rupture process for very deep earthquakes at the Peru-Brazil and Peru-Bolivia borders 
Authors: Buforn Elisa , Pro Carmen , Tavera Hernando , Udias Agustin , Mattesini Maurizio
Published: March 2021

We analyze the differences in the rupture process for twelve very deep earthquakes (h>500 km) at the Peruvian-Brazilian subduction zone. These earthquakes are produced by the contact between the Nazca and the South America Plates. We have estimated the focal mechanism from teleseismic waveforms, using the slip inversion over the rupture plane, testing rupture velocities ranging from 2.5 km/s to 4.5 km/s, and analyzing the slip distribution for each  rupture velocity. The selected 12 earthquakes have occurred in the period 1994- 2016, with magnitudes between 5.9 and 8.2 and focal depth 500- 700 km. They can be separated in two groups attending to their epicentral location. The first group is formed by 9 events located, in the Peruvian-Brazil border, with epicenters following a NNW-SSE alignment, parallel to the trench. Their focal mechanisms present solutions of normal faulting with planes oriented in NS direction, dipping about 45 degrees and with vertical pressure axis. The second group is formed by three earthquakes located to the south of the first group in northern Bolivia. Their mechanisms show dip-slip motion with a near vertical plane, oriented in NW-SE direction and the pressure axis dipping 45º to the NE. The moment rate functions correspond to single ruptures with time durations from 6s to 12s, with the exception of the large 1994 Bolivian earthquake (Mw = 8.2) which presents a complex and longer STF. The different mechanisms for the two groups of earthquakes confirm the different dip of the subducting Nazca plate at the two areas, with the steeper part at the southern one.  
Interstellar Probe: A Mission to the Heliospheric Boundary and Interstellar Medium for the Next Decade
Authors: Brandt Pontus , McNutt Ralph , Provornikova Elena , Lisse Carey , Mandt Kathleen , Runyon Kirby , Rymer Abigail , Mostafavi Parisa , DeMajistre Robert , Roelof Edmond , Turner Drew , Hill Matthew , Kinnison James , Rogers Gabe , Smith Clayton , Fountain Glen , Copeland David , Kollmann Peter , Ashtari Reza , Stough Robert ,   The Interstellar Probe Study Team
Published: March 2021

An Interstellar Probe mission to the Very Local Interstellar Medium (VLISM) would bring new scientific discoveries of the mechanisms upholding our vast heliosphere and directly sample the unexplored Local Interstellar Clouds that our Sun is moving through in relatively short galactic timescales. As such, it would represent Humanity's first explicit step in to the galaxy and become perhaps NASA's boldest step in space exploration. Such a mission has been discussed and studied since 1960, but the stumbling block has often been propulsion. Now this hurdle has been overcome by the availability of new and larger launch vehicles. An international team of scientists and experts are now progressing towards the final year of a NASA-funded study led by The Johns Hopkins University Applied Physics Laboratory (APL) to develop pragmatic example mission concepts for an Interstellar Probe with a nominal design lifetime of 50 years. Together with the Space Launch System (SLS) Office at the NASA Marshall Space Flight Center, the team has analyzed dozens of launch configurations and demonstrate that asymptotic speeds in excess of 7.5 Astronomical Units (AU) per year can be achieved using existing or near-term propulsion stages with a powered or passive Jupiter Gravity Assist (JGA). These speeds are more than twice that of the fastest escaping man-made spacecraft to date, which is Voyager 1 currently at 3.59 AU/year. An Interstellar Probe would therefore reach the Termination Shock (TS) in less than 12 years and cross the Heliopause into the VLISM after about 16 years from launch.

In this presentation we provide an overview and update of the study, the science mission concept, discuss the compelling discoveries that await, and the associated example science payload, measurements and operations ensuring a historic data return that would push the boundaries of space exploration by going where no one has gone before.
Rodingitization of mafic rocks from Central Evia (Greece) associated with serpentinite exhumation: Evidence from Petrological, Geochemical and Isotopic data 
Authors: Karkalis Christos , Magganas Andreas , Koutsovitis Petros , Ntaflos Theodoros
Published: March 2021

In Central Evia island (Aegean-Greece) serpentinized ultramafic rocks appear as elongated thrust sheets or in the form of olistostromes incorporated within Maestrichtian-Paleocene flysch. These are crosscut by well-developed rodingite dykes that were derived from four main protoliths that include i) Boninites, ii) Island-arc Tholeiitic Basalts and Gabbros, iii) Alkaline basalts and iv) Calc-alkaline basalts. They mainly comprise of minerals that include (hydro)garnet + chlorite + clinopyroxene ± vesuvianite. Accessory minerals include spinel ± calcite ± prehnite ± amphibole ± orthopyroxene ± olivine ± quartz ± opaque Fe-Ti oxides. Rodingites that were formed at the expense of boninites and island-arc tholeiitic rocks were likely formed within a single rodingitization stage, since garnet is mainly grossular-rich and relict primary clinopyroxene has been preserved. The rodingitization of the alkaline and calc-alkaline basalts seems to have occurred as a multi-stage metasomatic process that occurred during the exhumation of the mafic-ultramafic mantle wedge complex. This resulted in the development of late-stage andradite, vesuvianite and in some cases of chlorite during derodingitization. In this case, successive reaction zones with variability in the participating mineral phases were developed.  Geochemical results reveal remarkable rare earth element (REE) enrichments, especially in the inner zones, likely being the result of successive diffusion and element transfer. Few rodingites are characterized as calcite-bearing, whose stable 13C-18O isotopic data points to the restricted involvement of late-stage mixed hydrothermal and seawater-related carbonation processes.
The impact of fault permeability on the nucleation of injection-induced earthquakes
Authors: Santillán Sanchez David , Mosquera Feijoo Juan Carlos , Cueto-Felgueroso Landeira Luis
Published: March 2021

Injection-induced seismicity has become a central issue in the development of subsurface energy technologies such as enhanced geothermal energy, unconventional hydrocarbon production, wastewater injection, geologic carbon sequestration, or underground gas storage. The effect of the hydraulic properties of faults on the nucleation of earthquakes is a key aspect poorly understood. Our research question is how these properties may alter the onset of slip, the nucleation pattern, the nucleation length, and the time to nucleation.

We simulate earthquakes by means of sophisticated 2-dimensional computational models where earthquakes are triggered by fluid injection. The fault frictional contact is described by the Dieterich–Ruina rate-and-state law. Rock is simulated as a poroelastic solid and we couple fluid flow and rock mechanics.

Our model allows us to explain the impact of longitudinal and transverse fault permeability on the mechanisms that control the evolution of fault strength and shear stress during the nucleation. We find that the nucleation is controlled by the pressure and shear stress profiles along the fault, which in turn are driven by the fault hydraulic properties. Therefore, fault permeability exerts a fundamental control on the scaling of the nucleation length, the nucleation pattern, and the time to nucleation.

 Acknowledgements: Project supported by a 2019 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. The BBVA Foundation accepts no responsibility for the opinions, statements and contents included in the project and/or the results thereof, which are entirely the responsibility of the authors.
Ground-based radar interferometry of sea ice dynamics
Authors: Dammann Dyre Oliver , Fedders Emily , Mahoney Andrew , Johnson Mark , Meyer Franz , Fahnestock Mark
Published: March 2021

Arctic sea ice has retreated significantly over recent years. This ongoing sea ice decline has major implications for Arctic warming which motivates efforts to improve modeling capabilities. Human activities are also affected as sea ice is becoming less stable making ice roads, on-ice operations, and subsistence activities challenging in certain regions. To enhance modelling capabilities, ice use, and safety near sea ice, it is crucial to understand how sea ice deforms and fractures on the km-scale. Satellite remote sensing provides important insight into the mechanisms of large-scale sea ice deformation. However, analysis is frequently hampered by suboptimal data availability and lacks the spatiotemporal resolution necessary to resolve key processes.

We examine ground-based radar interferometry as a tool to bridge the gap between spaceborne remote sensing and sea ice lab and in-situ measurements during two field campaigns. We deployed a Gamma portable radar interferometer (GPRI) during a drifting ice camp in the Beaufort Sea during spring 2020. Based on this data, we demonstrate the ability to derive km-scale 2-dimensional strain/stress fields through inverse modeling. This analysis also highlights the ability to resolve mm-scale variations in dynamic behavior between different ice regimes. We also deployed a GPRI at a fixed reference point on shore in Utqiaġvik, Alaska. This enabled the tracking of absolute motion over several hours revealing near uni-axial elastic divergence in response to offshore wind.

Our analysis included efforts to remove signals from continuous antenna tilt due to ice motion when stationed on ice. We also needed to take steps to remove atmospheric phase contributions from the data obtained in Utqiaġvik during late spring. Overall, ground-based radar interferometry shows promise as a tool to track mm-scale sea ice dynamics. This may enable new insight into rheological behavior of sea ice and potentially the monitoring of dynamic precursors to fracture, which may improve safety near ice operations.
Working towards a universal formation model for spheroidal iron (oxyhydr)oxide concretions
Authors: Baker Desiree , Potter-McIntyre Sally
Published: March 2021

Three principal models exist for iron (oxyhydr)oxide concretion formation in the Navajo Sandstone in southern Utah, USA and the most recent model by Yoshida et al. (2018) suggests that calcite concretions are precursors to iron (oxyhydr)oxide concretions. This model could account for the existence of a gradient of carbonate and iron concretions found in both red diagenetic facies (with primary hematite grains coatings retained) and white diagenetic facies (primary hematite grain coatings removed during diagenesis). However, evidence for calcite precursor minerals and an understanding of the fluid chemistries involved in these diagenetic reactions is lacking. This research focuses on spheroidal concretions in the Navajo Sandstone at Coyote Gulch—a site that is down gradient, but upsection from Spencer Flat (the focus of previous work) and tests the hypothesis that calcite concretions are precursors to iron (oxyhydr)oxide concretions. Bulk mineralogy, bulk geochemistry, and petrography provide elemental and mineralogical composition of the concretions and show that the concretions are calcite cemented (~40 wt.%) and the host rock is predominately iron (oxyhydr)oxide cemented (~3 wt.%). The host rock surrounding embedded concretions shows secondary iron (oxyhydr)oxide precipitation and decreases in calcite in transects away from the concretion. These relationships suggest that the calcite concretions formed prior to the precipitation of secondary iron (oxyhydr)oxides and may have provided a localized buffering environment for the precipitation of iron (oxyhydr)oxides. This study also represents an opportunity to determine a universal model for carbonate and iron (oxyhydr)oxide spheroidal concretion formation, and to understand the influence of fluid interactions in the search for subsurface redox reactions to power metabolisms on Earth and Mars.
Internal water storage capacity of terrestrial planets and the effect of hydration on the M-R relation
Authors: Shah Oliver , Helled Ravit , Alibert Yann , Mezger Klaus
Published: March 2021

The discovery of low density exoplanets in the super-Earth mass regime suggests that ocean planets could be abundant in the galaxy. Understanding the chemical interactions between water and Mg-silicates or iron is essential for constraining the interiors of water-rich planets. Hydration effects have, however, been mostly neglected by the astrophysics community so far. As such effects are unlikely to have major impacts on theoretical mass-radius relations, this is justified as long as the measurement uncertainties are large. However, upcoming missions, such as the PLATO mission (scheduled launch 2026), are envisaged to reach a precision of up to ≈ 3% and ≈ 10% for radii and masses, respectively. As a result, we may soon enter an area in exoplanetary research where various physical and chemical effects such as hydration can no longer be ignored. We have constructed interior models for planets that include reliable prescriptions for hydration of the cores and mantles. These models can be used to refine previous results for which hydration has been neglected and to guide future characterization of observed exoplanets. We have developed numerical tools to solve for the structure of multi-layered planets with variable boundary conditions and compositions. Here we have considered three types of planets: dry interiors, hydrated interiors, and dry interiors plus surface ocean, where the ocean mass fraction corresponds to the mass fraction of the H2O equivalent in the hydrated case. We find H and OH storage capacities in the hydrated planets equivalent to 0 - 6 wt% H2O corresponding to up to ≈800 km deep ocean layers. In the mass range 0.1 ≤ M/M⊕ ≤ 3, the effect of hydration on the total radius is found to be ≤ 2.5%, whereas the effect of separation into an isolated surface ocean is ≤ 5 %. Furthermore, we find that our results are very sensitive to the bulk composition.
The HydroEcoSedimentary Tool: an integrated approach to characterise interstitial processes in freshwater systems
Authors: Casas-Mulet Roser , Pander Joachim , Prietzel Maximilian , Geist Juergen
Published: March 2021

Increased deposition of fine sediments in streams affects a range of key ecosystem processes across the sediment-water interface, and it is a critical aspect of river habitat degradation and restoration. Understanding the mechanisms leading to fine sediment accumulation along and across streambeds, and their affectation to ecological processes is therefore essential for comprehending human impacts on river ecosystems and inform river restoration. Here, we introduce the HydroEcoSedimentary Tool (HEST) as an integrated approach to assess hydro-sedimentary and ecologically relevant processes together. The HEST integrates the estimation of a range of processes occurring in the interstitial zone, including sedimentary (fine sediment accumulation and fine sediment loss upon retrieval), hydraulic (hydraulic conductivity), geochemical (water quality and temperature) and ecological (with a focus on brown trout early life stages).

We tested the HEST application in two rivers with different degrees of morphological degradation in Germany. The HEST was successful in recording the set of key hydrosedimentary and ecologically relevant factors, and in providing a mechanistic linkage between and biological effect in a site-specific context. The HEST data confirmed that salmonid embryo mortality could be linked to high fine deposition in gravel beds. In addition, the HEST illustrated that such mortality could be linked explicitly to interstitial depths and to different infiltration pathways for fines (e.g. vertical vs. horizontal). Although interstitial water quality and temperature were within ecological thresholds and did not show significant differences with surface water, it was still useful to monitor such variables and to rule out any effect on mortality. Water temperature, for example, could be extremely important to detect local groundwater inputs, which has been demonstrated to have a significant effect on embryo salmonids elsewhere. The HEST also allowed accounting for the loss of fines during retrieval failure and estimating hydrological factors with the HEST illustrates its additional usefulness and reliability.

Compared to other methods, the HEST expands the possibilities to monitor and quantify fine sediment deposition in streambeds by differentiating between vertical, lateral and longitudinal infiltration pathways, and distinguishing between the depth (upper vs. lower layers) at which interstitial processes occur along the streambed column.
Water loss and the origin of thick ultramylonites
Authors: Finch Melanie , Weinberg Roberto , Hunter Nicholas
Published: March 2021

Hydrolytic weakening has been suggested as a major process facilitating strain localisation, consistent with many studies that have found a positive correlation between water content and intensity of deformation. We examine the role of water in an unusually thick shear zone: the 1 km-thick ultramylonitic layer of the El Pichao shear zone, NW Argentina. We used Fourier Transform Infrared Spectroscopy to measure water content in quartz and feldspar, comparing ultramylonitic rocks to mylonites and weakly-deformed rocks. We found that quartz and feldspar in ultramylonites contained half the amount of water of weakly-deformed rocks, contrary to findings in previous studies. We propose that the kilometre-thick ultramylonite formed in three stages: (1) localised deformation and recrystallisation caused release of intracrystalline water to grain boundaries, which promoted grain-boundary sliding, forming the ultramylonite, (2) high pressure in the shear zone continuously expelled intercrystalline water to the surroundings, drying the boundaries and leading to strain hardening, (3) water migrated to neighbouring, less-deformed rocks causing hydrolytic weakening, repeating the cycle, and widening the ultramylonite.
Earth's supecontinental climate control
Authors: Jellinek A. Mark , Lenardic Adrian , Pierrehumbert Raymond
Published: March 2021

Supercontinent assembly and breakup can influence the rate and global extent to which insulated and relatively warm subcontinental mantle is mixed globally, potentially introducing lateral oceanic-continental mantle temperature variations that regulate volcanic and weathering controls on Earth's long-term carbon cycle for a few hundred million years. In this talk we explore some remarkable consequences of this class of mantle climate control consistent with varied observational constraints. Whereas the relatively unchanging and ice sheet-free climate of the Nuna supercontinental epoch (1.8–1.3 Ga) is an expected consequence of thorough mantle thermal mixing, the extreme cooling-warming climate variability of the Neoproterozoic Rodinia episode (1–0.63 Ga), marked by discontinuous periods of global glaciation (snowball Earth), is a predicted effect of protracted subcontinental mantle thermal isolation.
Closing a scale-gap in Earth observation using regional-scale airborne geophysics in the lower Mississippi Valley
Authors: Minsley Burke , Rigby James , James Stephanie , Burton Bethany , Knierim Katherine , Pace Michael , Bedrosian Paul , Kress Wade
Published: March 2021

Critical groundwater resources and hidden seismic hazards underly much of the Mississippi Alluvial Plain. Spanning nearly 100,000 square kilometers across seven states, this region hosts one of the most prolific shallow aquifer systems in the United States that supports a $12 billion agricultural economy amidst chronic groundwater decline. Further, underlying fault structures of the Reelfoot Rift and New Madrid Seismic Zone represent an important and poorly understood hazard with a complex pattern of historical impacts. Despite its societal and economic importance, mapping of shallow subsurface architecture with spatial resolution needed for effective management is insufficient. Here, we report the results of 40,000 flight-line-kilometers of electromagnetic, magnetic, and radiometric data collectively providing a system-scale snapshot of an entire aquifer system, the first such effort in the United States. This survey enables new understanding of the regional hydrogeology while also revealing previously unseen large vertical displacements (exceeding 50 m) in the uppermost Tertiary units within the New Madrid Seismic Zone.
Impact of Boreal Autumn Antarctic Oscillation on Winter Wet and Cold Weather in East Asia
Authors: Yuan Zhengxuan , Qin Jun , Li Shuanglin , Huang Sijing , Mbululo Yassin , Rehman Akhtar
Published: March 2021

The Antarctic Oscillation (AAO) is the dominant mode of the southern extratropical atmospheric mass variability which has potential influences on the Northern Hemisphere (NH). This study reveals a significantly negative correlation between the September-October (SO) AAO index and the occurrence rate of following January-February (JF) wet and cold weather in the Middle and Lower Reaches of Yangtze River Basin (MLRY) in China. The latter is quantified by a Precipitation-Temperature (PT) Index. JF PT is modulated by both northerly air flow in the lower troposphere and southerly air flow in the lower-middle troposphere. The SO AAO stimulates Southern Ocean Dipole (SOD) pattern-like SST anomalies, which induces a North Atlantic Oscillation (NAO)-like atmospheric response in the following JF through ocean-air interaction. As for the northerly flow, the JF NAO-like pattern triggers an eastward propagating wave train, influencing the intensity of East Asian Winter Monsoon (EAWM) and subsequently the northerly cold flow to MLRY. As for southerly flow, the variation of JF SOD regulates the local meridional cell, in turn modulating the Middle East Jet Stream (MEJS) along with the NAO-like pattern, influencing the intensity of precipitation and the wet and warm flow over Southern China and the adjacent regions. In addition to the tropospheric processes, the stratospheric Quasi Biennial Oscillation (QBO) serves as the ‘bridge’ for linking SOD to NH climate, inducing the JF PT response to SOD SST. To summarize, SO AAO affects the JF PT in MLRY by modulating both cold-dry northerly air flow and warm-wet southerly air flow through ocean-atmosphere interactions and stratospheric pathway.
Geodynamic constraints deciphered from the petrology and geochemistry of the Late Cretaceous granitoids from Anafi island (Cyclades - Greece)
Authors: Koutsovitis Petros , Soukis Konstantinos , Voudouris Panagiotis , Lozios Stylianos , Ntaﬂos Theodoros , Stouraiti Christina , Koukouzas Nikolaos
Published: March 2021

In the Aegean region (Cyclades - Greece), the island of Anafi island comprises Late Cretaceous intermediate and felsic granitoids that intruded within exhumed HT/LP metamorphic sequences that include amphibolites, serpentinites and metasediments. The granitoids correspond to I-type arc-related rocks with calc-alkaline geochemical affinities. Variations in their petrography mineral chemistry and geochemical features are attributed to magma differentiation with removal of plagioclase and/or K-feldspar, but also amphibole and biotite. Differentiation processes of the upwelling granitoid magma included fractional crystallization accompanied with crustal assimilation, pointing to interaction with the overriding continental crust. Mineral chemistry and geochemical results display that the Anafi granitoids are highly comparable with the Late Cretaceous granitoids of East Crete and Donousa island suggesting that this magmatic activity was not a local event. Geothermometric results show relatively moderate temperature crystallization conditions (~790 °C) for the compositionally intermediate granitoids, which are and lower for the felsic granitoids (~630 °C). Geobarometric calculations suggest shallow intrusion conditions (~2.0-6.5 kbar), which corresponds to a depth of crystallization of ~12 ± 4 km.

The thrust sheets that overly the flysch constitute a subducted and metamorphosed oceanic sequence, that after the intrusion of the granitoids was exhumed from the Late Cretaceous to the Late Oligocene. These metamorphic units likely represent a part of the Pindos - CBU domain that was subducted at an earlier pre-Campanian stage. In the hydrated mantle wedge, incorporation of shallow level granitoids within metamorphic units was likely facilitated via corner flow intrusion mechanisms. Ongoing underplating of subducted material gradually brought the granitoids along with the host units to shallow structural levels and on top of the parautochtonous flysch.
A scaling law for similar ice sheet flow
Authors: Feldmann Johannes , Levermann Anders
Published: March 2021

The time scales of the flow and retreat of the outlet glaciers draining Greenland and Antarctica and their potential instabilities are arguably the largest uncertainty in future sea-level projections. The associated stress and velocity fields are highly complex. Here we derive an exact scaling law from first principles that shows that the time scale of outlet-glacier flow is related to the inverse of 1) the fourth power of the width-to-length ratio of its topographic confinement, 2) the third power of the confinement depth and 3) the temperature-dependent ice softness. We show that idealized numerical simulations of marine ice-sheet instabilities (MISI) as found in Antarctica follow this theoretical prediction. In a further step we apply the scaling law to observations of different MISI-prone Antarctic outlets to compare their potential instability time scales. The simple scaling relation incorporates the full complexity of the ice stress field of a fast outlet glacier similar to the predictive power of the thermodynamic equations of an ideal gas. In quantifying the non-linear influence of glacier geometry and temperature on the ice dynamicsscaling law allows to investigate similar ice flow under future global warming.
The roles of global cooling and early Tibetan Plateau uplift on the enhanced aridity in Eocene Asian inland
Authors: Li Xiangyu , Zhang Zhongshi , Zhang Ran , Yan Qing
Published: March 2021

Geological evidence shows that the Asian inland environment experienced enhanced aridity from the Early to the Late Eocene. The underlying mechanism for this enhanced Eocene aridity in the Asian inland is still not well illustrated and varies between global cooling and early Tibetan Plateau uplift. In this report, we evaluate the climate impact of three factors, global cooling, topographic uplift and land–sea reorganization, on the enhanced Eocene aridity in Asian inland, in the perspective view from paleoclimate modeling. Paleoclimate modeling supports the Eocene aridification in Asian inland explored by paleoclimate reconstruction. Both the early uplift of Tibetan Plateau and global cooling induced by atmospheric CO2 reduction contributed to the enhanced aridity in Asian inland in the late Eocene. The Eocene land sea redistribution caused the precipitation increase in Asian inland and hence didn’t contribute to the enhanced aridity there. The uplift of the central Tibetan Plateau during the early stage of the India–Asia collision is emphasized more to be responsible for the long-term Asian inland aridification during the Eocene, playing at least an equally important role as the global cooling induced by decrease in atmospheric CO2. The variation of atmospheric CO2 is likely more important in modulating the regional aridity, leading to the short-term fluctuations in this Eocene Asian inland aridification.
Quasi-solitary multiscale cross-diffusion waves as a precursor to Earth instabilities
Authors: Regenauer-Lieb Klaus , Hu Manman , Sun Qinpei , Schrank Christoph
Published: March 2021

We propose a mesoscopic thermodynamics approach for coupling multiphysics processes across scales in porous or multiphase media. In this multiscale reaction-diffusion formalism interactions of discrete phenomena at the local scale are seen as being subject to a larger scale Thermo-Hydro-Mechano-Chemical (THMC) thermodynamic force. When local interactions are incompatible with the large-scale thermodynamic stress field incompatibilities can arise which trigger accelerations resulting in meso-scale generalized thermodynamic fluxes of another (THMC) kind. The classical acoustic tensor localization criterion in plasticity theory is here understood as a standing wave solution of such acceleration waves. These classical zero-speed acceleration wave solutions are solitary waves, also known as solitons, and are interpreted in the reaction-diffusion formalism as self-diffusion dominated by harvesting all available energy from the cross-diffusional tails.

The more general case of non-zero traveling wave speed solutions is related to the cross-diffusion coefficients between different macro- and meso-scale thermodynamic THMC forces and fluxes. These cross-diffusion terms in the 4 x 4 THMC diffusion matrix are shown to lead to multiple diffusional P- and S-wave equations as THMC coupled, time-resolved dynamic solutions of the equation of motion. We show that the off-diagonal cross-diffusivities can give rise to a new class of waves also known as cross-diffusion waves or quasi-solitons. Their unique property is that for critical conditions cross-diffusion waves can funnel wave energy into a soliton wave focus.

Mathematically these solutions can be compared to events in ocean waves and optical fibers known as 'rogue waves' or 'high energy pulses of light' in lasers. In the context of hydromechanical coupling, a rogue wave would appear as a sudden fluid pressure spike on the future fault plane. This hydromechanically coupled fluid pressure P-wave instability is here interpreted as a trigger for the S-wave seismic moment release of a double couple dominated earthquake event. The proposed multiscale cascade of wave energy may apply to many other material instabilities.

 

 
The Lorenz Energy Cycle: Trends and the Impact of Modes of Climate Variability
Authors: Ma Qiyun , Lembo Valerio , Franzke Christian
Published: March 2021

The atmospheric circulation is driven by heat transport from the tropics to the polar regions, implying energy conversions between available potential and kinetic energy through various mechanisms. The processes of energy transformations can be quantitatively investigated in the global climate system through the Lorenz energy cycle formalism. In this study, we examine these variations and the impacts of modes of climate variability on the Lorenz energy cycle by using reanalysis data from the Japanese Meteorological Agency (JRA-55). We show that the atmospheric circulation is overall becoming more energetic and efficient. For instance, we find a statistically significant trend in the eddy available potential energy, especially in the transient eddy available potential energy in the Southern Hemisphere. We find significant trends in the conversion rates between zonal available potential and kinetic energy, consistent with an expansion of the Hadley cell, and in the conversion rates between eddy available potential and kinetic energy, suggesting an increase in mid-latitudinal baroclinic instability. We also show that planetary-scale waves dominate the stationary eddy energy, while synoptic-scale waves dominate the transient eddy energy with a significant increasing trend. Our results suggest that interannual variability of the Lorenz energy cycle is determined by modes of climate variability. We find that significant global and hemispheric energy fluctuations are caused by the El Nino-Southern Oscillation, the Arctic Oscillation, the Southern Annular Mode, and the meridional temperature gradient over the Southern Hemisphere.
Non-diffusive pitch-angle scattering of a distribution of energetic particles by coherent whistler waves
Authors: Yoon Young Dae , Bellan Paul
Published: March 2021

A recent study and a companion talk [1] showed that an exact rearrangement of the relativistic particle equation of motion under a coherent circularly-polarized electromagnetic wave leads to an equation describing the motion of the “frequency mismatch” parameter ξ under a pseudo-potential ψ(ξ). When the particle undergoes a so-called “two-valley motion” in ξ-space, it experiences large changes in ξ and thus its pitch-angle because ξ is a function of the particle’s velocity parallel to the background magnetic field. This single-particle analysis is extended [2] to a distribution of relativistic particles. First, the condition for two-valley motion is derived with parameters relevant to magnetospheric contexts. Single-particle simulations verify that particles which satisfy this condition indeed undergo large pitch-angle fluctuations. Second, assuming a relativistic Maxwellian particle distribution, the fraction of particles that undergo two-valley motion is analytically derived and is numerically verified by Monte-Carlo simulations. A significant fraction (1% - 5%) of the distribution undergoes two-valley motion for typical magnetospheric parameters. For sufficiently fast interactions where a uniform background magnetic field and a constant wave frequency can be assumed, the widely-used second-order trapping theory [3] is shown to be an erroneous approximation of the present theory.

 

[1] P. M. Bellan, Phys. Plasmas, 20 (4), Art. No. 042117 (2013)

[2] Y. D. Yoon and P. M. Bellan, JGR Space Physics, 125 (6), Art. No. e2020JA027796 (2020)

[3] D. Nunn, Planet. and Space Sci., 22 (3), 349-378 (1974)

 
Assessment and Comparison of Subseasonal Bias and Forecast Skill in the Unified Forecast System (UFS) Benchmarks 3 and 5
Authors: Kodama Keri , Straus David , Kinter James
Published: March 2021

A series of reforecasts have been generated with prototype versions of the coupled Unified Forecast System (UFS) to evaluate progress in the model development. The forecast skill and biases of the UFS Prototypes 3 and 5 reforecast sets—called Benchmark 3 and Benchmark 5, respectively—are analyzed and compared with the NCEP Climate Forecast System version 2 (CFSv2) reforecasts from the Subseasonal Prediction Experiment (SubX). The evaluation focuses on surface variables typically provided in the subseasonal outlooks at weekly-averaged timescales, namely 2-meter air temperature, precipitation rate, and sea surface temperature. Additional assessment of the structure of the systematic error in total diabatic heating over three broad layers of the atmosphere (850-650 hPa, 650-450 hPa and 450-50 hPa) has been performed as a function of season and forecast lead. In terms of forecast skill, all models still experience a skill drop-off of varying degree by week 3. In general, however, the UFS prototypes considerably reduce the marked diminution of variability with lead time displayed in their predecessor, CFSv2. Moreover, the prototypes have reduced systematic error compared to CFSv2, particularly for 2-meter temperature and precipitation. A systematic overestimate of diabatic cooling is noted in the upper atmosphere (diabatic heating too negative compare to ERA-5 estimates) during boreal winter. 
Direct Observation of A Large-scale CME Flux Rope Event Arising from an Unwinding Coronal Jet 
Authors: Chen Hechao , Yang Jiayan , Hong Junchao , Li Haidong , Duan Yadan
Published: March 2021

Increasing observations show that coronal jets may result in bubble-shaped coronal mass ejections (CMEs), but the genesis of jet-driven CMEs and their nature are not fully understood. Here, we report a direct stereoscopic observation on the magnetic coupling from a coronal blowout jet to a stellar-sized CME.  Observations in the EUV passbands of SDO/AIA show that this whole event starts with a small-scale active-region filament whose eruption occurs at a coronal geyser site due to flux emergence and cancellation. By interacting with an overlying null-point configuration, this erupting filament first breaks one of its legs and triggers an unwinding blowout jet. The release of magnetic twist in its jet spire is estimated at around 1.5−2.0 turns. This prominent twist transport in jet spire rapidly creates a newborn large-scale flux rope from the jet base to a remote site. As a result, the newborn large-scale flux rope erupts into the outer coronae causing an Earth-directed bubble-shaped CME. In particular, two sets of distinct flare post-flare loops form in its source region in sequence, indicating this eruptive event couples with twice flare reconnection. This observation highlights a real pathway for jet-CME magnetic coupling and provides a new hint for the buildup of large-scale CME flux ropes. 
Heavy metal translocation in soil-plant system in conditions of urban anthropogenic pollution (Tyumen, Russian Federation)
Authors: Petukhov Alexander , Kremleva Tatyana , Petukhova Galina
Published: March 2021

Soil contamination by heavy metals causes metal accumulation by plants, which leads to the degradation of plants communities and migration of toxicants with food chains to man. Therefore, the investigation of heavy metal concentration in soils of urban areas is an urgent scientific task. This study aims to examine the translocation of heavy metals from urban soils to herbs in Tyumen (Russian Federation).  Soil surface layer was collected at control site, near the highway as well as from areas with metallurgical, motor building, oil refinery and battery manufactory plants in Tyumen. Meadow grass, red clover, wild vetch, chamomile and coltsfoot were collected at all examined sites.  The mobile and acid-soluble heavy metal fractions in soils, as well as the heavy metal contents in plants, were determined by atomic absorption spectrophotometry. The bioconcentration factor was estimated as the ratio of the amount of heavy metals in soils to that in plants. The study was performed during three-year period from 2017 to 2019. Heavy metal concentrations in urban soils were higher than those at the control site by 20% and by up to 10 times. The greatest heavy metal accumulation in both soils and plants was found at the battery manufacturing and metallurgical plants, exceeding the control levels of Pb and Fe by 2-17 times. The Cu, Fe and Mn contents in soil were positively correlated with those in plants. Heavy metal translocation by the plants was species-specific. The percentages of the mobile heavy metal fractions decreased in the following order: Mn>Zn>Cu>Fe. Heavy metal accumulation in plants in the urban sites compared to that at the control site decreased in the following order: Fe>Zn>Cu>Mn>Pb>Cd. Coltsfoot exhibited the highest Fe, Mn, and Zn accumulation, which exceeded the control levels by 17, 5, and 3.5 times, respectively. The heavy metal bioconcentration factors, indicators of translocation, decreased in the following order: Cu>Zn>Cd>Pb>Mn>Fe. The heavy metal translocation suggests the need to relocate industrial facilities to outside the city. Future monitoring of the study area is needed to ensure its long-term ecological safety.
A method for predicting hydrogen and oxygen isotope distributions across a region’s river network using reach-scale environmental attributes
Authors: Dudley Bruce , Yang Jing , Shankar Ude , Graham Scott
Published: March 2021

Long-term isotope values of river water provide information on hydrological flow pathways and atmospheric exchange and can be used to determine the origins of hydrogen and oxygen stored in animal and plant tissues. However, development of isotope maps for rivers is currently limited by methods to spatially interpolate point measurements to values for entire river networks. Catchment environmental characteristics and structures that affect river water isotope values also affect downstream reaches via flow, but many (such as man-made dams) are no more likely to affect nearby unconnected catchments than distant ones. Hence, distance-based geospatial and statistical interpolation methods used to develop isoscapes for precipitation and terrestrial systems may be less appropriate for river networks. We developed a modified ‘water balance’ river isotope mapping method to consider the effects of reach-scale catchment environmental characteristics and applied it across the entire stream network of New Zealand. This network comprises over 600,000 reaches and over 400,000 kilometres of rivers. The method uses national rainfall precipitation isoscapes, a digital elevation layer, a national river water isotope monitoring dataset (currently over 3 years of monthly sampling at 58 sites) and reach scale environmental attribute databases that cover New Zealand’s river network. δ2H and δ18O isoscapes produced showed an improved fit to validation data, compared to a model for which residuals between observed and simulated isotope values were applied as a correction factor across the river network using the ordinary kriging method. Hence, we show how a water balance modelling approach can provide an improved representation of long-term river water δ2H and δ18O values when combined with a correction for catchment environmental attributes.