bluuebunny/crossref_metadata_2025 huggingface dataset:
Power-law frequency scaling of surface temperature spatial degrees of freedom – estimated from instrumental data, reanalysis and climate model simulations
Authors: Kunz Torben , Laepple Thomas
Published: March 2021

What is the spatial scale of climate fluctuations, and how does this scale depend on the timescale under consideration? To answer this question, the spatio-temporal correlation structure of global surface temperature fields is characterized, for the period 1850-present, by estimating frequency spectra of the effective spatial degrees of freedom (ESDOF). These ESDOF spectra serve as a simple summarizing metric of the frequency-dependent spatial auto-correlation function. ESDOF spectra are estimated from: (a) the HadCRUT global gridded temperature anomaly dataset, based exclusively on instrumental measurements, and including detailed error variance estimates; (b) the NOAA 20th Century Reanalysis; and (c) a large ensemble of CMIP historical climate model simulations. When comparing (i) error corrected ESDOF spectra from the instrumental data to (ii) those obtained from the reanalysis and the model simulations, with HadCRUT data gaps imposed, results are found to be highly consistent among the three data sources. When the analysis is applied to the entire globe, the ESDOF spectra exhibit an almost uniform power-law frequency scaling with about 100 ESDOFs at monthly timescales and only about 2 ESDOFs at multidecadal timescales. Second-order differences in this scaling behaviour are found when the analysis is restricted to various spatial subdomains of the globe, namely, the tropics, extra-tropics, land areas, and ocean areas. A few implications of the diagnosed ESDOF reduction towards the longer timescales are briefly discussed.
The Fate of Rare Earth Elements in Post-Fire Soils in the Pocono Mountains, Pennsylvania (USA)
Authors: Pope Gregory , Callanan Jennifer , Darley Jason , Flood Michael , Wear Jeffrey , Calderon Bernadette , Gorring Matthew , Li Xiaona
Published: March 2021

The wood ash contribution to soils represents a unique and important part of soil organic carbon following fires.  Wood ash imparts chemical and physical changes to the soil, evident in elements other than carbon.  Our case studies are from recent wildfires and experimental burns in mixed hardwood forests in the Pocono Mountains of Pennsylvania, USA.  In these studies, we identified increases in most of the major elements and some minor elements in soils following forest fires, analyzed with ICP-MS. Elements such as Mn, Mg, Na, Ca, Na, K, Cu, and Ba, derive from an infusion of biomass ash, with variable contribution depending on, for instance, tree species. In the case of Ba and Cu, their presence is distinctly different from any mineral parent material contribution to the soil, and therefore unique signatures of fire contribution. Signature post-fire elements persist in some cases over one year following the fire, and are found in both topsoil horizons and into illuvial soil horizons.

In the course of these investigations, we also found a curious depletion of all rare earth elements (REEs) and certain trace elements from the soil following forest fires, and in adjacent stream and wetland sediments. The post-fire difference in REE concentration was statistically significant (p < 0.10, N=51) in all but Eu and U, with light REEs La, Ce and Pr showing the most significant decreases. Among other trace elements, Sc (which behaves similarly to REEs), V, Cr, Ga, and Rb also exhibited statistically significant decreases (though other elements Cu and Sr increase along with the ash input). The reasons for the depletions are unclear. Other authors report that REE dynamics in soils are poorly understood, but may be associated with phosphates, carbonates, and silicates in the soil. These are relatively enriched via post-fire biomass ash, yet the associated REEs are missing. It is unlikely that the elements would have preferentially translocated through and below the soil profile. Erosion is ruled out, otherwise the ash-associated major and trace elements would also be depleted. Two possible causes for post-fire REE loss are 1) volatilization from the soil during the fire, and 2) rapid uptake by post-fire succession plants, notably ferns, which are known to bioaccumulate REEs. Further research is warranted, following the ongoing post-fire vegetation recovery, and the dynamics of REEs within the soil profile.       
On the Low Energy (< keV) O+ Ion Outflow directly into the Inner Magnetosphere
Authors: Gkioulidou Matina , Ohtani Shin , Mitchell Don , Spence Harlan
Published: March 2021

The development of low energy (< keV) O+ ions in the inner magnetosphere is a crucial issue for various aspects of magnetospheric dynamics: i) Recent studies have suggested that low energy O+ can be locally accelerated to few keV energies inside geosynchronous orbit, and thus can constitute a significant source of the storm-time ring current O+ that could dominate the energy density during storms, ii) Mass loaded densities are important for accurate location of the plasmapause, which, in turn, is necessary for meaningful calculation of the field line resonance radial frequency profiles of ULF hydromagnetic waves in plasmasphere, iii) since O+ is only of ionospheric origin, its outflow from ionosphere into the magnetosphere is a manifestation of fundamental processes concerning energy and mass flow within the coupled Magnetosphere – Ionosphere system. Although a lot of progress has been made on O+ outflow at high latitudes and its subsequent transport and acceleration within the magnetotail and plasma sheet, the source of low-energy O+ within the inner magnetosphere remains a compelling open question. The Helium Oxygen Proton and Electron (HOPE) mass spectrometer instrument aboard Van Allen Probes, which move in highly elliptical, low inclination orbits with apogee of 5.8 RE, has repeatedly detected field aligned flux enhancements of eV to hundreds of eV O+ ions, which indicate O+ outflow directly into the inner magnetosphere. We systematically investigate, throughout the duration of the Van Allen Probes mission (2012 – 2019), the occurrence of such events with respect to L and MLT, the dependence of their directionality (bi-directional or unidirectional) and the lowest and highest energies involved on L, MLT and MLAT. We categorize the outflow events with respect to plasmapause location (when its determination is possible) and identify whether there is enhancement of O+ density. This categorization is important because if the outflows occur close to the plasmapause location, and depending on the density enhancement they cause, they could be responsible for the formation of O+ torus, whose source has been under debate for years. Finally, in order to identify the physical processes that lead to the ionospheric outflow, we also examine whether there are dipolarizations and/or enhancements of the field-aligned poynting flux associated with these outflow events.
Fusing Damage Proxy Maps with Geospatial Models for Bayesian Updating of Seismic Ground Failure Estimations: A Case Study in Central Italy
Authors: Xu Susu , Dimasaka Joshua , Wald David J. , Noh Hae Young
Published: March 2021

On August 24, 2016, a magnitude-6.2 earthquake in Central Italy resulted in at least 290 deaths, significant ground failure (including landslides and liquefaction), and building damage. After the event, the NASA Advanced Rapid Imaging and Analysis team produced Damage Proxy Maps (DPM) that reflect earthquake-induced surficial changes using synthetic aperture data from the COSMO-SkyMed satellite. However, exact causes of these surface changes, e.g., ground failure, building damage, or other environmental changes, are difficult to directly differentiate from the satellite images alone. For example, changes could reflect building damage, landslides, the co-occurrence of both, or numerous other processes that are not related to the earthquake. Alternatively, existing ground failures models are useful in locating areas of higher likelihoods but suffer from high false alarm rates due to inaccurate or incomplete geospatial proxies and complex physical interdependencies between shaking and specific sites of ground failure. In this work, we present a joint Bayesian updating framework using a causal graph strategy. The Bayesian causal graph models physical interdependencies among ground shaking, ground failures, building damage, and remote sensing observations. Based on the graph, a variational inference approach is designed to jointly update the estimates of ground failure and building damage through fusing traditional geospatial models and the remotely sensed data. As a case study, the DPMs in Central Italy are input to the model for jointly calibrating and updating the probability of ground failure estimations as well as for estimating building damage probabilities. The results showed that by incorporating high-resolution imagery, our model significantly reduces the false alarm rate of ground failure estimates and improves the spatial accuracy and resolution of ground failure and building damage inferences.
Estimation of sediment capacity of Aswan High Dam Lake utilizing remotely sensed bathymetric data: Case Study Active Sedimentation portion of Lake Nubia
Authors: Negm Abdelazim , Hossen Hickmat , Elsahabi Mohamed , Makboul Omar , Scozzari Andrea
Published: March 2021

This study deals with the quantitative estimation of the accumulated sediment capacity within the period from the initiation of the storage process of Lake Nubia in 1964 until 2012, by using field measurements and remote sensing data.. The bed levels of the study area related to year 1964 were extracted from a tri-dimensional model of the lake derived from a topographic map, based on observations anterior to lake filling. This map was compared with the bed levels estimated for the year 2012, which were extracted from remote sensing data, with the aim to estimate the sediment capacity. The utilized technique for estimating the bathymetric data (depths) from satellite images relies on establishing a Multiple Linear Regression (MLR) model between in situ measurements and reflectance data from multi-spectral optical satellite observations. The Multiple Linear Regression (MLR) model showed good results in the correlation between field measurements and remote sensing data. The current approach provides flexibility as well as effective time and cost management in calculating depths from remote sensing data when compared to the traditional method applied by Aswan High Dam Authority (AHDA). This study is in the framework of a bilateral project between ASRT of Egypt and CNR of Italy, which is still running.

 
Tectonic deformation and mantle-driven uplift of the Middle Atlas mountain belt (Morocco) during the late Cenozoic
Authors: Yaaqoub Ahmed , Essaifi Abderrahim , Clementucci Romano , Ballato Paolo , Faccenna Claudio
Published: March 2021

The Middle Atlas mountain range represents the northeastern branch of the Atlas system, which spans approximately 2000 km from the Atlantic coast of Morocco to Tunisia. The Atlas system is a prominent example of active intracontinental mountain belts that developed in the African plate of the Cenozoic Alpine belt.

The Middle Atlas is an inverted Mesozoic rift that began to rise during the late Cretaceous with limited crustal thickening. It can be divided into two geomorphological provinces: 1) an elevated, low-relief area called Tabular Middle Atlas (TMA), which is located in the north-western orogenic sectors and consists of weakly deformed Mesozoic sediments in stratigraphic contact with the Paleozoic basement of the western Meseta, and 2) a deeply dissected, high-relief area known as Folded Middle Atlas to the southeast, where crustal deformation is dominated by transpressive tectonics induced by a NNW-SSE maximum shortening direction. Seismicity and geomorphic landforms suggest that tectonic deformation is still active, at least in some sectors of the orogen.

In order to investigate the tectonic evolution of the Middle Atlas, we combined structural and geomorphic analysis. Although the age control of the continental syn-orogenic deposits is limited, the eastern boundary of the orogen shows evidence of recent tectonic deformation and flexural subsidence with the development of a foreland basin. Conversely, the western boundary of the orogen does not include syn-orogenic foreland basins suggesting the lack of flexural subsidence. This boundary is also characterized by alkaline late Miocene-Quaternary lava flows over a wide surface of ca. 960 km2. These lava flows cover part of the TMA where they fill valleys crossing the Meseta and draining towards the Atlantic Ocean. The degree of subsequent fluvial incision of the lavas is lower in the TMA than in the Meseta. While incision does not go beyond the stratigraphic contact lava-substratum in the TMA, it goes further down in the Meseta indicating a higher magnitude of uplift. The lack of contractional deformation, however, suggests that such an uplift is not controlled by tectonics.

Overall, our preliminary observations suggest the occurrence of an asymmetry between the two orogenic flanks. Uplift along the eastern orogenic boundary has been triggered by late Cenozoic contractional deformation, whereas deep-seated, most likely mantle-driven processes essentially control uplift of the western boundary.
Optical and Radio emissions of a possible blue starter observed by ASIM and the West Texas LMA
Authors: Boggs Levi , Neubert Torsten , Chanrion Oliver , Reglero Victor , Østgaard Nikolai , Heumesser Matthias , Nag Amitabh , Bruning Eric
Published: March 2021

This study reports on simultaneous optical and radio observations of a possible blue starter that took place in north-west Texas in the United States in 2018.  The optical observations come from the Atmospheric-Space Interactions Monitor (ASIM) onboard the International Space Station [Neubert et al., 2019, doi: https://doi.org/10.1007/s11214-019-0592-z] and the radio observations were from the National Lightning Detection Network (NLDN) [Cummins and Murphy, 2009, doi: 10.1109/TEMC.2009.2023450] and the West Texas Lightning Mapping Array (WTLMA) [Chmielewski and Bruning, 2016, doi: https://doi.org/10.1002/2016JD025159]. It was identified by the ASIM CHU1 337 nm imager and shows a diffuse, conical emission shape reaching approximately 7 km above cloud top, characteristic of blue starters.  The ASIM CHU2 777.4 nm imager shows a simple point-source of emissions, highly contrasting the 337 nm imager observations.  The 337 and 777.4 nm photometers show four distinct pulses, the first two of which were dominated by the 337 nm emissions and also showed clear UV (180-230 nm) photometer peaks.  From the WTLMA data, which clearly mapped the negative and positive leaders (or negative recoil events) even at low altitudes, the parent storm cell exhibited what appears to be a classic tri-polar charge structure, with upper and lower positive and middle negative charge.  The blue starter occurs during what appears to be an initial ascending negative leader into the upper positive charge region, which continues to develop into a positive intracloud (IC) flash between the upper positive and middle negative charge region.  During this time, there are several small NLDN positive cloud pulses (+IC), consistent with a traditional IC flash, but these are followed by two moderately high peak current (40-50 kA) negative cloud-to-ground strokes, which appear to be misclassified by the NLDN as there were no WTLMA VHF source points at low altitudes during this time. The misclassified negative strokes are concurrent with the first blue peak from the ASIM 337 nm photometer.  We conjecture that these misclassified negative CG strokes were actually electromagnetic pulses from in-cloud (or near-cloud-top) sources, which were perhaps directly associated with the blue starter. 
Implications of pericline geometries on 3D fold shape analysis, stress distribution and fracture analysis
Authors: Eckert Andreas , Liu Xiaolong , Welker Avery , Connolly Peter , Hogan John , Tindall Sarah
Published: March 2021

The characterization of folds is often limited to two-dimensional cross-sectional views where folds are approximated as cylindrical. This enables simplification of fold shape analysis (using principles such as dip isogons, stereographs, tangent diagrams, and Bezier curve analysis), allows for a simplified analysis of the distribution of stress and strain, and enables and the analysis and visualization of folding associated fractures. However, in a heterogenous medium folds have to terminate somewhere, resulting in more complex three-dimensional geometries. In this study, a 3D finite element modeling approach using a Maxwell visco-elastic rheology is utilized to simulate 3D periclinal folds resulting from single layer buckle folding. With respect to fold shape analysis, we use the forward modeled pericline geometries to demonstrate that geometrical attitude data collected for various cross sections and plotted using traditional 2D methods such as stereographs and tangent diagrams may lead to the misinterpretation of the fold shape as conical. In contrast 3D geometric data such as Gaussian curvature can describe and quantify the 3D fold geometry in its entirety. With respect to folding associated fracture analysis, the 3D modeling results show that shear fractures of various orientations in the fold limb, which cannot be intuitively explained by the strain/stress regimes during 2D buckling and require unrealistic boundary conditions, are feasible to occur during a single deformation event during the development of a pericline. In summary, accounting for the true 3D geometry of buckle fold structures will lead to a better classification of folds, a better understanding of the processes and parameters affecting their development, and enable post-folding failure analysis.
Weather-condition-regulated, heated 3-D sonic anemometers (CSAT3AH and CSAT3BH): Working rationale, operation algorithm, and performance assessment
Authors: Mahan Hayden , Gao Tian , Li Xiufen , Forbush Troy , Payne Kris , Yang Quan , Li Yanlei , Zhou Haitao , Wu Shangming , Zheng Ning , Zhou Xinhua
Published: March 2021

Three-dimensional (3D) sonic anemometers are commonly used to measure 3-D wind in eddy-covariance systems for the fluxes of momentum, sonic temperature, and when integrated with fast-response gas analyzers, the fluxes of CO2/H2O. A 3-D sonic anemometer has three pairs of sonic transducers spatially positioned with optimized geometry for 3-D wind measurements. The three pairs form three individual sonic paths, each of which is between paired transducers mutually emitting and receiving ultrasonic signals. The transmitting time of the signals in reference to the sonic path length is used to calculate air flow speed and sonic temperature at high frequencies, which can be used for flux computations. However, under unfavorable weather conditions the dew, frost, snow, and/or ice often deposit on the transducer signal transmitting surface. The deposition interferes with the transducer emitting and receiving signals, bringing significant uncertainties to the wind and sonic temperature measurements. These uncertainties degrade the quality of flux data and even interrupt the data continuity, especially in climates where this deposition is most frequent. To minimize the uncertainties, and to optimize the data quality and continuity as much as possible, Campbell Scientific developed the weather-condition-regulated, heated 3-D sonic anemometers: CSAT3AH and CSAT3BH. The former is a heated CSAT3A used for Campbell Scientific open-path and closed-path eddy-covariance systems. The latter is a heated CSAT3B, universally configured with any other gas analyzer for eddy-covariance measurements or used as a stand-alone sensor for wind aerodynamic measurements. Both models use the same heating technology equipping a sonic anemometer with an electronic heating controller (CSAT3H) programmatically regulating the power to heat sonic transducers, arms, and the strut. Based on weather conditions (air temperature, relative humidity, wind speed, and atmospheric pressure) and sonic anemometer operation status (diagnosis codes), the controller regulates heat to prevent frozen and liquid deposition from interfering with the sonic signal. The two new models of sonic anemometers were tested and assessed at several locations, including inside an environment-controlled laboratory chamber, over a forest canopy in a cold region, and at a snow-covered field station at a high plateau. This poster addresses working rationale, operating heating algorithm, and sensor performances.
Global and monthly glacier mass balance from radar altimetry from 2010 to 2020
Authors: Jakob Livia , Gourmelen Noel , Kauffert Johanna
Published: March 2021

Glaciers are currently experiencing the largest land-ice imbalance and are the largest contributor to sea level rise after ocean thermal expansion, contributing ~30% to sea level budget. Global monitoring of these regions remains a challenging task since global estimates rely on a variety of observations and models to achieve the required spatial and temporal coverage, and significant differences remain between current estimates. Here we report, for the first time, the application of radar altimetry to retrieve spatially and temporally resolved elevation and mass changes of glaciers on a global scale. We apply interferometric swath altimetry to CryoSat-2 data acquired between 2010 and 2020 over all large mountain glacier regions and provide monthly and annual time series of glacier mass loss for each region, together with linear mass losses. We report ubiquitous and sustained ice loss ranging from 82.3 ± 6.3 Gt yr−1 in Alaska, to 3.4 ± 2.5 Gt yr−1 for the Antarctica Periphery. While there is a considerable spatial and temporal variability in imbalance, reflecting the complexity of regional atmospheric and oceanic forcing and of glacier forcing, the global glacier trend is remarkably sustained over this period. Globally, glaciers have lost a combined mean of 275 ± 15 Gt yr−1 between 2010 and 2020 contributing 0.76 ± 0.5 mm yr−1 to global Sea Level Rise.
Exploring the potential of buried paleosols and paleodunes sequences for unraveling Late-Pleistocene climate change in subtropical Coastal Chile
Authors: García Juan Luis , Luethgens Christopher , Cabello Misael A. , Quilamán Estefanía A. , Latorre Claudio , Maldonado Antonio , Pfeiffer Marco
Published: March 2021

We have started a program of detailed mapping and sampling buried paleosols and paleodunes sequences that occur along the semiarid coast of central Chile (32-34ºS). Previous work has postulated these stratigraphic records afford evidence for past climate change linked to the latitudinal oscillations/intensification of the southern westerly winds (SWW): Bt horizons resembling humid conditions associated with north shifted SWW, and paleodunes with arid conditions and south shifted SWW. Nonetheless, multiple factors can affect long-term (e.g., orbital to suborbital time-frames) eolian dune variability (stabilization-reactivation, expansion-contraction, pedogenesis-morphogenesis), including sea level, sediment supply, wind intensity, and tectonics. It is therefore a pending work to expand our research in these eolian archives and understand their causes and environmental implications. Here, we present preliminary research results from the Ritoque paleodune, Comuna de Quintero, Chile (32ºS). The study site is a 15 m deep gully incision that allowed us to built a very complete sediment stratigraphic sequence postdating the Miocene-Pliocene marine Horcón Formation. Previous luminescence geochronologic control in nearby paleodune deposits indicate eolian morphogenetic and pedogenetic activity during the last glacial period. We interpret the geomorphic context together with standard sediment field and laboratory data to discriminate between stratigraphic units and their origin. A total of 13 sediment units were mapped, which include mostly couplets of buried paleosols (Bt horizons) and underlying paleodunes. Other units resembling rather paleowetlands and possibly sea side sand beaches were also found. We discuss our results in light of available evidence to unravel the environmental meaning of this extraordinary well-preserved terrestrial record in the SE subtropical Pacific.
Semi-Lagrangian advection models for quasi-uniform nodes on the sphere
Authors: Enomoto Takeshi , Ogasawara Koji
Published: March 2021

Radial basis functions enable the use of unstructured quasi-uniform nodes on the sphere. Iteratively generated nodes such as the minimum energy nodes may not converge due to exponentially increasing local minima as the number of nodes grows. By contrast, deterministic nodes, such as those made with a spherical helix, are fast to generate and have no arbitrariness. It is noteworthy that the spherical helix nodes are more uniform on the sphere than the minimum energy nodes. Semi-Lagrangian and Eulerian models are constructed using radial basis functions and validated in a standard advection test of a cosine bell by the solid body rotation. With Gaussian radial basis functions, the semi-Lagrangian model found produces significantly smaller error than the Eulerian counterpart in addition to approximately three times longer time step for the same error. Moreover, the ripple-like noise away from the cosine bell found in the Eulerian model is significantly reduced in the semi-Lagrangian model. It is straightforward to parallelize the matrix–vector multiplication in the time integration. In addition, an iterative solver can be applied to calculate the inverse of the interpolation matrix, which can be made sparse.
Fuzzy mathematical model for estimating wind erosion based on wind tunnel data, comparison of results with laboratory measured and SWEEP model results
Authors: Tatárvári Károly , Piros Attila
Published: March 2021

Fuzzy logic is often used for calculation and simulation of real environmental situations. Wind erosion can often be complex, and from various erosion situations it is one of the hardest to be calculated and exactly described. In our research, we based the structure of the fuzzy system on the soil loss of six soils with different mechanical compositions measured in wind channels. Measurement of soil loss in four wind speed ranges during soil channel testing of soils. During the wind tunnel analysis of the soils, the topsoil loss was measured in four wind speed ranges (I. 11,2-11,6 m/s; II. 12.5-13.3 m/s, III. 14.4-14.7 m/s, IV. 15.5-15.7 m/s) on six soils with different mechanical compositions (four sand and two clayey sand soil). The mathematical model programmed and built up in MATLAB, this mamdani type fuzzy evaluation system uses two input parameters wind speed and ErosionFactor. The mathematical model requests the soils mechanical composition and identifies it based on the USDA triangle diagram. Many mathematical methods applicable to fine tune a fuzzy system. We have chosen the method of exhaustive design to cover the whole parameter space. The mathematical model calculated the soil loss. Model runs were also performed with the SWEEP model according to the soils examined in the wind tunnel. Based on our results, we found that using our fuzzy mathematical model, we obtained estimated soil loss values similar to the SWEEP model compared to the soil loss measured in the wind tunnel. However, it should be noted that the USDA SWEEP model requires a much larger amount of data to estimate the extent of soil loss caused by a wind erosion damage event.
Socio-economic conditions for satisfying human needs at low energy use: an international analysis of provisioning factors
Authors: Vogel Jefim , Steinberger Julia K. , O'Neill Daniel W. , Lamb William F. , Krishnakumar Jaya
Published: March 2021

Meeting human needs at low levels of energy use is fundamental for avoiding catastrophic climate change and securing the well-being of all people. In the current international political-economic regime, no country does so.

Here, we assess which socio-economic conditions might enable societies to satisfy human needs at sustainable levels of energy use, and thus reconcile human well-being with ambitious climate mitigation. Applying a novel analytical framework and a novel regression-based moderation approach to data from 106 countries, we analyse how the relationship between energy use and six dimensions of human need satisfaction varies with a wide range of socio-economic factors relevant to the provisioning of goods and services (‘provisioning factors’).

We find that higher achievements in provisioning factors such as income equality, public service quality, democracy and electricity access are associated with greater need satisfaction and lower energy dependence of need satisfaction. Conversely, higher levels of economic growth and extractivism are associated with lower need satisfaction and greater energy dependence of need satisfaction. Our analysis suggests that countries with beneficial configurations of key provisioning factors are much more likely to reach high levels of need satisfaction at low(er) levels of energy use. Based on our statistical models, countries with highly beneficial configurations of several key provisioning factors could likely achieve sufficient need satisfaction within levels of energy use found compatible with limiting global warming to 1.5 °C without negative emissions technologies. Achieving this would be very unlikely for countries with detrimental provisioning configurations.

Improvements in relevant provisioning factors may thus be crucial for ending human deprivation in currently underproviding countries without exacerbating climate and ecological crises, and for tackling the ecological overshoot of currently needs-satisfying countries without compromising sufficient need satisfaction. However, as key pillars of the suggested changes in provisioning run contrary to the dominant political-economic regime, a broader political-economic transformation may be required to organise provisioning for the satisfaction of human needs within sustainable levels of energy use.

Our findings have important implications for climate mitigation, poverty eradication, development discourses, and efforts towards Sustainable Development Goals and socio-ecological transformation.
Modelling hydraulic fracturing with the J-integral
Authors: Pezzulli Edoardo , Nejati Morteza , Salimzadeh Saeed , Matthai Stephan , Driesner Thomas
Published: March 2021

Hydraulic fracturing plays a central role in engineering fractured reservoirs. To simulate the propagation of “dry” fractures, the J-integral has been a standard technique. Its superior accuracy at coarser resolutions make it particularly attractive, especially for reservoir-scale simulations. However, the extension of the J-integral to hydro-mechanical simulations of fluid-driven fracturing has not received the same attention or success. In particular, while several studies have highlighted the capacity of the method in simulating viscosity-dominated propagation, detailed investigations into the performance of the method are still missing. In this work, we find that the extent of hydraulic fracturing is typically overestimated by the J-integral in the viscosity-dominated propagation regime.  A finite element analysis is conducted which sheds light on the source of the error. The case is put forward that the inaccurate numerical solution for fluid pressure is exclusively responsible for the loss in accuracy of the J-integral. With this new understanding, the J-integral is reformulated to minimise its dependence on inaccurate fluid pressures, bypassing the aforementioned sources of error. The reformulation, termed the JV-integral, is both simple to implement, and general to the numerical method. Within the framework of finite elements, a propagation algorithm using the novel JV-integral is subsequently constructed with two distinct abilities compared to the original J-integral. The first is an increased ability to capture the viscosity-dominated regime of propagation at significantly coarser resolutions. Finite element simulations conducted at various levels of refinement detail the promising results relevant to hydro-mechanical simulations at reservoir scale.  The ability of the method in simulating the toughness regime remains as performant as the original J-integral.  The second, is the ability of the JV-integral in extracting the propagation velocity of the fracture; a feature particular to methods arising from hydraulic fracture mechanics. Consequently, the method demonstrates an inherent advantage when converging on the fracture length, requiring significantly fewer iterations compared to the original formulation. Fundamentally, the velocity obtained via the JV-integral has the potential to be used in combination with front-tracking schemes like the implicit level set method. As a result, the JV-integral appears to be a promising method when simulating hydraulic fracturing in geoenergy applications and beyond. 
Large Precipitation Gradients along the South Coast of Alaska Revealed by Spaceborne Radars
Authors: Aoki Shunsuke , Shige Shoichi
Published: March 2021

This study focuses on the considerable spatial variability of precipitation along the western coast of a continent at mid–high latitude and investigates the precipitation climatology and mechanism along the south coast of Alaska, using datasets of spaceborne radars onboard two satellites, namely, the Dual-frequency Precipitation Radar (DPR) KuPR onboard the Global Precipitation Measurement (GPM) core satellite and the Cloud Profiling Radar (CPR) onboard CloudSat. At higher latitudes, differentiating the phase of precipitation particles falling on the ground is crucial in evaluating precipitation. Classification of satellite precipitation products according to the distance from the coastline shows that precipitation characteristics differ greatly on opposite sides of the coastline. Above coastal waters, relatively heavy precipitation with CPR reflectivity larger than 7 dBZ from orographically enhanced nimbostratus clouds, which can be detected by KuPR, is frequently captured. Meanwhile, along coastal mountains, light-to-moderate snowfall events with CPR reflectivity lower than 11 dBZ, which are well detected by the CPR but rarely detected by KuPR, frequently occur, and they are mainly brought by nimbostratus clouds advected from the coast and orographically enhanced shallow cumuliform clouds. There is no clear diurnal variation of precipitation except in summer, and the amplitude of the variation during summer is still low compared with total precipitation especially over the ocean, suggesting that the transport of synoptic-scale water vapor brings much precipitation throughout the year. Case studies and seasonal analysis indicate that frontal systems and moisture flows associated with extratropical cyclones that arrive from the Gulf of Alaska are blocked by terrain and stagnate along the coast to yield long-lasting precipitation along the coastline. The results of this study illustrate the importance of using complementary information provided by these radars to evaluate the precipitation climatology in a region in which both rainfall and snowfall occur.
Investagation of the sediment connectivity under freeze-thaw meltwater compound erosion condition on loessal slope
Authors: Wang Tian , Li Peng , Hou Jingming , Li Zhanbin , Cheng Shengdong , Wang Feng
Published: March 2021

The connectivity of rill erosion and overland flow are significantly affected by freeze-thaw cycles. Meltwater concentrated flow laboratory experiments were carried out to assess the soil erosion connectivity of different frozen conditions based on simplified hydrological curve and relative surface connection function. The experiments were performed over frozen, shallow-thawed, and unfrozen soil-filled flumes under 1, 2, and 4 L/min flow rates with the temperature around 5 °C. The results imply that according to the spatial distribution of the high connected areas on the slope, the connectivity of the sediment structure on the slope is obviously enhanced with the increase of the flow rate. The order of the structural connectivity of the sediment on the slope with different freeze-thaw states under the same flow rate is: frozen slope > shallow-thawed slope > unfrozen slope. Under different flows and soil frozen conditions, the laws of the vertical and horizontal connectivity rates of the slope are relatively similar which increase first and then stabilize, while the horizontal connectivity rate first decreases and then stabilizes. From the perspective of horizontal connectivity, the erosion form at the beginning of the experiment was mainly surface erosion; as the experiment progressed, the erosion form gradually changed from surface erosion to rill erosion. The results of this research would provide specific implications about meltwater erosion connectivity for improving the erosion process understand.
ICEComb − A New Software Tool for Satellite Laser Altimetry Data Processing and Visualisation
Authors: Silva Bruno , Guerreiro Lopes Luiz , Campos Pedro
Published: March 2021

Processing, handling and visualising the large data volume produced by satellite altimetry missions is a challenging task. A reference tool for the visualisation of satellite laser altimetry data is the OpenAltimetry platform, a tool that provides altimetry-specific data from the Ice, Cloud, and land Elevation Satellite (ICESat) and ICESat-2 satellite missions through a web-based interactive interface. However, by focusing only on altimetry data, that tool leaves out access to many other equally important information existing in the data products from both missions.

The main objective of the work reported here was the development of a new web-based tool, called ICEComb, that offers end users the ability to access all the available data from both satellite missions, visualise and interact with them on a geographic map, store the data records locally, and process and explore data in an efficient, detailed and meaningful way, thus providing an easy-to-use software environment for satellite laser altimetry data analysis and interpretation.

The proposed tool is intended to be mainly used by researchers and scientists to aid their work using ICESat and ICESat-2 data, offering users a ready-to-use system to rapidly access the raw collected data in a visually engaging way, without the need to have prior understanding of the format, structure and parameters of the data products. In addition, the architecture of the ICEComb tool was developed with possible future expansion in mind, for which well-documented and standard languages were used in its implementation. This allows, e.g., to extend its applicability to data from other satellite laser altimetry missions and integrate models that can be coupled with ICESat and ICESat-2 data, thus expanding and enriching the context of studies carried out with such data.

The use of the ICEComb tool is illustrated and demonstrated by its application to ICESat/GLAS measurements over Lake Mai-Ndombe, a large and shallow freshwater lake located within the Ngiri-Tumba-Maindombe area, one of the largest Ramsar wetlands of international importance, situated in the Cuvette Centrale region of the Congo Basin.

Keywords: Laser altimetry, ICESat/GLAS, software tool design, data visualization, Congo Basin.

Acknowledgement. This work was partially supported by the Portuguese Foundation for Science and Technology (FCT) through LARSyS − FCT Pluriannual funding 2020−2023.
Differential uplift of three Pliocene sea level indicator sites in southern Argentina driven by upwelling asthenosphere through the Patagonian slab window 
Authors: Hollyday Andrew , Austermann Jacqueline , Lloyd Andrew , Hoggard Mark , Richards Fred , Rovere Alessio
Published: March 2021

Bivalve and gastropod shell beds deposited during the Early Pliocene (4.69-5.23 Ma) occur in uplifted outcrops (36 – 180 m above sea level) along the east coast of Patagonian Argentina. These rock units provide a record of sea level during a geologic period when atmospheric CO2 and temperatures were higher than today. As such, reconstructing the elevation of global mean sea level (GMSL) during this time allows us to better understand how sensitive ice sheets are to increased past and future warming. However, reconstructing GMSL from local sea level indicators is hindered by effects such as mantle dynamic topography and glacial isostatic adjustment (GIA) that cause local sea level to deviate from the global mean. Here we use geodynamic modeling to better understand this complex dynamic setting and quantify the amount of uplift along this coastline.

Despite being located on a relatively stable passive margin, significant variations in the elevation of the paleo shoreline indicators imply that the underlying convecting mantle is deforming the coastline. In particular, the subduction of the Chile Rise beginning ~18 Ma beneath Patagonia has generated a slab window underneath this region through which hot asthenosphere ascends. However, the former slab is still present deeper in the mantle, which causes a complex interplay between the downwelling slab and the upwelling asthenosphere. To quantify the effects of dynamic topography change since the Pliocene, we run 3D mantle convection simulations using the code ASPECT. We initialize our global model with a composite temperature structure derived from recent tomographic studies and a calibrated parameterization of upper mantle anelasticity. Independent estimates of pressure and temperature from thermobarometric calculations of proximal Pali-Aike xenoliths agree with the thermal structure of the tomography-based Earth model. We back-advect temperature perturbations and extract the resulting change in dynamic topography. Pairing GIA models and a suite of convection simulations in which we vary the viscosity and buoyancy structure with the observed differential paleo shoreline elevations allows us to forward model the most likely scenario for uplift along this coast.
Closing the Neotethys Ocean in western Anatolia: Insights from forearc and foreland sedimentary basin records
Authors: Mueller Megan , Licht Alexis , Campbell Clay , Ocakoğlu Faruk , Akşit Gui , Métais Grégoire , Coster Pauline , Beard K. Christopher , Taylor Michael
Published: March 2021

Across the Tethyan realm, subduction zones are characterized by phases of forearc and backarc extension, and subsequent collisions are protracted and polygenetic, often resulting in significant discrepancies among proxies of collision age. The closure of the northern branch of the Neotethys Ocean along the İzmir-Ankara-Erzincan suture in Anatolia has been variously estimated from the Late Cretaceous to Eocene. It remains unclear whether this age range results from a protracted, multi-phase collision or disparities between proxies and geographic location. Near-continuous Jurassic through Eocene deposition in the forearc-to-foreland Central Sakarya Basin system in western Anatolia makes it an ideal location to integrate pre-collisional extension and multi-stage collision into a holistic reconstruction of subduction through collision. The Central Sakarya Basin system is located north of the Izmir-Ankara-Erzincan suture, where the Gondwanan-derived Anatolide and Tauride terranes to the south collided with the Laurasian-derived Pontide terrane in the north. By integrating new sandstone petrography and detrital zircon U-Pb and Hf isotopes with other geologic proxies, we demonstrate four phases of evolution of subduction and collision. (1) Magmatism began on the Pontides at 110 Ma, potentially the signal of subduction (re-)initiation, and is coincident with extension in the forearc. (2) Forearc obduction began around 94 Ma with initial subduction of lower plate continental lithosphere. Extension migrated to the backarc and opened the Black Sea. (3) The onset of intercontinental collision at 76 Ma is marked by gradual arc shutdown, basement exhumation, and uplift of the suture zone. (4) This first contractional phase is followed by thick-skinned deformation and basin partitioning starting around 54 Ma, coeval with regional syn-collisional magmatism. The 20-Myr protracted collision in western Anatolia could be explained by three non-exclusive mechanisms that produced a change in plate coupling: relict basin closure, progressive underthrusting of thicker lithosphere, and slab breakoff.
Effect of ecological construction on sediment connectivity in a typical small watershed on Loess Plateau
Authors: Ma Yongyong , Li Zhanbin , Hou Jingming , Li Peng , Ren Zongping , Lu Kexin
Published: March 2021

In recent years, the significantly decrease of water and sediment in the Yellow River has attracted wide attention from domestic and foreign scholars. The Loess Plateau is the main source of sediment in the Yellow River, which ecological environment changes caused by large-scale ecological construction measures is considered as one of the main factors affecting the water and sediment changes in the Yellow River. In this study, the Wangmaogou small watershed in Loess Plateau was taken as the study area. On the basis of summing up the process of ecological construction in Wangmaogou watershed, and restoring the topography before ecological construction by topographic map, we set up four scenarios of ecological construction to analyzed the characteristics of sediment connectivity under different ecological construction scenarios and the effects of ecological construction on sediment connectivity, which are before ecological construction, only slope measures are built, only channel measures are constructed, and at the same time slope measures and channel measures are constructed. Under the same ecological construction scenario, the index of sediment connectivity (IC) of the basin shows a decreasing trend from ridge to gully, which mean the connectivity of the sediment at the ridge is less than that at the gully, and the gully are more prone to occur soil erosion than ridge. The distributed of large amount of construction land in the middle and lower reaches at the main gully of Wangmaogou small watershed reduces the connectivity of their surrounding sediment, and the region is prone to occur sediment deposition. Eco-construction measures have decreased significantly the sediment connectivity index (p<0.01) of Wangmaogou small watershed, and reduced the occurrence of soil erosion. Laying ecological measures lessened the possibility of local soil erosion, and increased the resistance of sediment in the transport process. Compared with the situation without ecological control, the mean of Dup index decreased by 75.27% by laying slope and gully measures, while the mean of Dup index decreased by only 6.45% by laying gully measures.