bluuebunny/crossref_metadata_2025 huggingface dataset:
Using online N2O isotopic measurements to understand grassland N2O emission processes in a changing climate 
Authors: Stoll Elena , Harris Eliza , Diaz-Pines Eugenio , Reinthaler David , Radolinski Jesse , Glatzel Stephan , Zechmeister-Boltenstern Sophie , Pötsch Erich , Bahn Michael
Published: March 2021

Biogeochemical processes in soils largely control the atmospheric mixing ratio of nitrous oxide (N2O). The growing use of nitrogen (N) fertilizer in agriculture drives anthropogenic N2O emissions, which currently surpass projections with some of the highest emissions. In order to adapt mitigation strategies and to model the future N cycle it is crucial to fully understand N2O emission pathways in a changing climate. The underlying processes, attributed to microbial transformation of N, primarily occur via the oxic nitrification and anoxic denitrification pathways. These processes depend greatly on soil, plant and ecosystem properties, which in turn rely on meteorological drivers (e.g. air temperature and precipitation). This means that the many environmental factors that drive microbial activity and N2O emissions in soils are vulnerable to climate change, including extreme events such as droughts. Consequently, the rates of nitrification and denitrification are expected to be strongly impacted by changing climatic conditions, which could also alter the N2O production and consumption dynamics across the soil profile.

This study aims to understand how N2O production and consumption pathways respond to the individual and combined effects of warming, elevated atmospheric CO2 concentration, and drought-rewetting events in managed mountain grassland. For the first time, we use online, in-situ stable isotopic measurements of both surface N2O emissions and of N2O across the soil profile to distinguish pathways for N2O production and consumption. Different modeling approaches will be used to reconstruct production and consumption dynamics from soil gas isotopic measurements, and to upscale results to examine global relevance.
Simulations of gravitoelastic correlations for the Sardinian candidate site of the Einstein Telescope
Authors: Andric Tomislav , Harms Jan
Published: March 2021

Gravity fluctuations produced by ambient seismic fields are predicted to limit the sensitivity of the next-generation, gravitational-wave detector Einstein Telescope at frequencies below 20 Hz. The detector will be hosted in an underground infrastructure to reduce seismic disturbances and associated gravity fluctuations. Additional mitigation might be required by monitoring the seismic field and using the data to estimate the associated gravity fluctuations and to subtract the estimate from the detector data, a technique called coherent noise cancellation. In this paper, we present a calculation of correlations between surface displacement of a seismic field and the associated gravitational fluctuations using the spectral-element SPECFEM3D Cartesian software. The model takes into account the local topography at a candidate site of the Einstein Telescope at Sardinia. This paper is a first demonstration of SPECFEM3D’s capabilities to provide estimates of gravitoelastic correlations, which are required for an optimized deployment of seismometers for gravity-noise cancellation.
Application of the "genRE" approach to spatial interpolation of precipitation gauge data for the Suir River Basin
Authors: Boumis Georgios , van Osnabrugge Bart , Verkade Jan
Published: March 2021

Operational near real-time flood forecasting relies heavily on adequate spatial interpolation of precipitation forcing which bears a huge impact on the accuracy of hydrologic forecasts. In this study, the generalized REGNIE (genRE) interpolation technique is examined. The genRE approach was shown to enhance the traditional Inverse Distance Weighting (IDW) method with information from existing observed climatological precipitation data sets (Van Osnabrugge, 2017). The successful application of the genRE method with a re-analysis precipitation data set, expands the applicability of the method as detailed re-analysis data sets become more prevalent while high density observation networks remain scarce.

Here, the approach is extended to use climatological precipitation data from the Met Éireann’s Re-Analysis (MÉRA). Investigations are carried out using hourly precipitation accumulations for two major flood events induced by Atlantic storms in the Suir River Basin, Ireland. Alongside genRE, the following techniques are comparatively explored: Inverse Distance Weighting (IDW), Ordinary Kriging (OK) and Regression Kriging (RK). Cross-validation is applied in order to compare the different interpolation methods, while spatial maps and correlation coefficients are utilized for assessing the skill of the interpolators to emulate the climatology of MÉRA. In the process, a preliminary intercomparison between the observed precipitation and MÉRA precipitation for the two events is also made.

In a statistical sense, cross-validation results verify that genRE performs slightly better than all three interpolation techniques for both events studied. Overall, OK is found to be the most inadequate approach, specifically in terms of preserving the original variance in observed precipitation. MÉRA manages to reproduce the temporal variations of observations in a good manner for both events, whereas it displays less skill when considering spatial variations especially where topography has a major influence. Finally, genRE outperforms all other interpolators in mimicking the climatological conditions of MÉRA for both events.

 

Van Osnabrugge, B., Weerts, A.H. and Uijlenhoet, R., 2017. genRE: A method to extend gridded precipitation climatology data sets in near real-time for hydrological forecasting purposes. Water Resources Research, 53(11), pp.9284-9303.
The Quadratic Magnetic Gradient and Complete Geometry of Magnetic Field Lines Deduced from Multiple Spacecraft Measurements
Authors: Shen Chao , Zhang Chi , Rong Zhaojin , Pu Zuyin , Dunlop M.alcolm , Escoubet Chris , Russell Chris , Zeng Gang , Ren Nian , Burch James , Zhou Yufei
Published: March 2021

Topological configurations of the magnetic field play key roles in the evolution of space plasmas. This paper presents a novel algorithm that can estimate the quadratic magnetic gradient as well as the complete geometrical features of magnetic field lines, based on magnetic field and current density measurements by a multiple spacecraft constellation at 4 or more points. The explicit estimators for the linear and quadratic gradients, the apparent velocity of the magnetic structure and the curvature and torsion of the magnetic field lines can be obtained with well predicted accuracies. The feasibility and accuracy of the method have been verified with thorough tests. The algorithm has been successfully applied to exhibit the geometrical structure of a flux rope. This algorithm has wide applications for uncovering a variety of magnetic configurations in space plasmas.
Different approaches of finding European climate analogue regions for the Steigerwald forest (Germany) in the future
Authors: Ziegler Katrin , Pohl Felix , Pollinger Felix , Paeth Heiko
Published: March 2021

Adapting the impacts of climate change is a great challenge. To facilitate forest adaptation long-term and forward-looking decisions must be made today since they have to be valid for several decades. Therefore, fundamental knowledge of the future climate and of tree species which are more resilient to the future climate than trees growing in the forests today is necessary.

To give local foresters a basis for their decisions, we use the so-called analogue region method. With this method we aim to find regions in Europe which currently have the same climate as it is projected in a specific reference region for different future scenarios. For the projections, the model runs of the regional climate model REMO are used. As an example of finding analogue regions, we selected the forest region Steigerwald in North Bavaria. We use different climatic and forest specific indices and data preparation methods to test the influence of varying indices and methods on the resulting regions. After identifying the respective analogue regions, we analyze which tree species are growing currently in these regions by using the EU-Forest data set.
A record of plume-induced plate rotation triggering seafloor spreading and subduction initiation
Authors: van Hinsbergen Douwe J. J. , Steinberger Bernhard , Guilmette Carl , Maffione Marco , Gürer Derya , Peters Kalijn , Plunder Alexis , McPhee Peter , Gaina Carmen , Advokaat Eldert , Vissers Reinoud , Spakman Wim
Published: March 2021

The formation of a global network of plate boundaries surrounding a mosaic of lithospheric fragments was a key step in the emergence of Earth’s plate tectonics. So far, propositions for plate boundary formation are regional in nature but how plate boundaries are being created over 1000s of km in short periods of geological time remains elusive. Here, we show from geological observations that a >12,000 km long plate boundary formed between the Indian and African plates around 105 Ma with subduction segments from the eastern Mediterranean region to a newly established India-Africa rotation pole in the west-Indian ocean where it transitioned into a ridge between India and Madagascar. We find no plate tectonics-related potential triggers of this plate rotation and identify coeval mantle plume rise below Madagascar-India as the only viable driver. For this, we provide a proof of concept by torque balance modeling revealing that the Indian and African cratonic keels were important in determining plate rotation and subduction initiation in response to the spreading plume head. Our results show that plumes may provide a non-plate-tectonic mechanism for large plate rotation initiating divergent and convergent plate boundaries far away from the plume head that may even be an underlying cause of the emergence of modern plate tectonics.
Impact assessment of climate change and human activities on GHG emissions and agricultural water use
Authors: Sun Shikun , Tang Yihe
Published: March 2021

The agriculture sector is one of the largest users of water and a significant source of greenhouse gas (GHG) emissions. The development of low-GHG-emission and water-conserving agriculture will inevitably be the trend in the future. Because of the physiological differences among crops and their response efficiency to external changes, changes in planting structure, climate and input of production factors will have an impact on regional agricultural water use and GHG emissions. This paper systematically analyzed the spatial-temporal evolution characteristics of crop planting structure, climate, and production factor inputs in Heilongjiang Province, the main grain-producing region of China, from 2000 to 2015, and quantified the regional agricultural water use and GHG emissions characteristics under different scenarios by using the Penman-Monteith formula and the Denitrification-Decomposition (DNDC) model. The results showed that the global warming potential (GWP) increased by 15% due to the change in planting structure. A large increase in the proportion of rice and corn sown was the main reason. During the study period, regional climate change had a positive impact on the water- saving and emission reduction of the agricultural industry. The annual water demand per unit area decreased by 19%, and the GWP decreased by 12% compared with that in 2000. The input of fertilizer and other means of production will have a significant impact on GHG emissions from farmlands. The increase in N fertilizer input significantly increased N2O emissions, with a 5% increase in GWP. Agricultural water consumption and carbon emissions are affected by changes in climate, input of means of production, and planting structure. Therefore, multiple regulatory measures should be taken in combination with regional characteristics to realize a new layout of planting structure with low emissions, water conservation, and sustainability.
Insights from big data into the fossilization potential of marine communities
Authors: Shaw Jack , Briggs Derek , Hull Pincelli
Published: March 2021

Only a small percentage of all life that ever existed is preserved in the rock record. Some animals and environments are particularly unlikely to fossilize—e.g., soft-bodied organisms and high-energy habitats—biasing fossil deposit faunal composition and resultant inferences about macroevolution and macroecology. To estimate the extent of information loss caused by non-preservation we compared diversity data in over 20,000 modern marine assemblages (Ocean Biogeographic Information System; OBIS) with fossil occurrence data (Paleobiology Database; PBDB) to yield a global assessment of assemblage-level fossilization potential as it varies across depth, habitats, and environments. We used two different metrics, taxon fossilization potential and within-environment fossilization potential, to assess the proportion of taxa in a modern community with PBDB occurrences or with PBDB occurrences in the same environment, respectively. Averaged across all 20,000+ marine assemblages, mean taxon fossilization potential is 38% and mean values vary between environments: from 34% in shallow and deep water, 44% in coral reefs, 51% on seamounts, to 15% in pelagic assemblages. Mean within-environment fossilization potential, in contrast, does not exceed 32% (in shallow water), a lower value than that obtained in other studies, and may approach zero (on seamounts and pelagic environments). Differences between these two metrics indicate the large control of environment on fossilization potential. Our results provide a means to include and compare palaeoecological dynamics across a broader range of settings in the fossil record, while accounting for differences in fossilization potential among environments.
Enhancing the detection of buried anthropogenic features thought a cloud-computing Python procedure
Authors: Brandolini Filippo , Domingo-Ribas Guillem , Zerboni Andrea , Turner Sam
Published: March 2021

The necessity of sustainable development for landscapes has emerged as an important theme in recent decades. Moreover, past landscape reconstruction enables a better understanding of human resilience to climatic and environmental changes in different periods and locations, and illustrates examples of sustainable development in the past. Free and open-source (FOSS) datasets of satellite imagery offer considerable opportunities for landscape heritage stakeholders both for recording and monitoring activities. In this research, a completely FOSS-cloud procedure to enhance the detection of palaeo-landscape features is presented. Sentinel - 2 satellite imagery has been retrieved in the Google Earth Engine dataset collection and analysed through a Python script code realized in Google Colaboratory. A multi-temporal approach has been adopted to investigate the potential of satellite imagery to detect buried features along with Spectral Index (i.e., RGB, False Short Wave Infrared Colour and Bare Soil Index) and Spectral Decomposition analysis (i.e., Hue, Saturation and Value, Tasselled Cap Transformation and Principal Component Analysis). This procedure has been tested in the Po Plain (Northern Italy), chosen because it is characterized by human-landscape interaction since the Mid-Holocene. Thanks to its complex settlement and land-management history, the Po Plain represents an ideal laboratory to assess the potentiality of satellite imagery to enhance riverscapes’ palaeo-features.  The outputs obtained can be visualized directly in the Google Colaboratory browser or downloaded via Google Drive for further graphical applications or spatial analysis. The buried features detected have been checked through the available geomorphological and archaeological literature; published case studies interpreting the occurrence of buried features served as a benchmark to validate the script code developed. This research represents one of the first applications of the GEE Python API in landscape studies. The main advantages of this procedure consist of: i) being FOSS, all the software used here are open-licensed; ii) working in cloud, no powerful hardware is necessary to run the script code; iii) high adaptability, changing the ROI is possible to calculate SI and SD outputs for any area of the world; iv) very basic coding skills are required to adapt the code to a ROI with different environmental characteristics. The development of FOSS-cloud procedures could support the identification, conservation and management of cultural and natural heritage anywhere around the world. In remote areas or where local heritage is threatened as a result of political instability, climate change or other factors, FOSS-cloud protocols can facilitate the application of new scientific methods and enable the dissemination of and access to scientific information.
Knowledge transfer from simulation to reality via Long Short-Term Memory networks:  Estimating groundwater table depth anomalies over Europe
Authors: Ma Yueling , Montzka Carsten , Bayat Bagher , Kollet Stefan
Published: March 2021

Near real-time groundwater table depth measurements are scarce over Europe, leading to challenges in monitoring groundwater resources at the continental scale. In this study, we leveraged knowledge learned from simulation results by Long Short-Term Memory (LSTM) networks to estimate monthly groundwater table depth anomaly (wtda) data over Europe. The LSTM networks were trained, validated, and tested at individual pixels on anomaly data derived from daily integrated hydrologic simulation results over Europe from 1996 to 2016, with a spatial resolution of 0.11° (Furusho-Percot et al., 2019), to predict monthly wtda based on monthly precipitation anomalies (pra) and soil moisture anomalies (θa). Without additional training, we directly fed the networks with averaged monthly pra and θa data from 1996 to 2016 obtained from commonly available observational datasets and reanalysis products, and compared the network outputs with available borehole in situ measured wtda. The LSTM network estimates show good agreement with the in situ observations, resulting in Pearson correlation coefficients of regional averaged wtda data in seven PRUDENCE regions ranging from 42% to 76%, which are ~ 10% higher than the original simulation results except for the Iberian Peninsula. Our study demonstrates the potential of LSTM networks to transfer knowledge from simulation to reality for the estimation of wtda over Europe. The proposed method can be used to provide spatiotemporally continuous information at large spatial scales in case of sparse ground-based observations, which is common for groundwater table depth measurements. Moreover, the results highlight the advantage of combining physically-based models with machine learning techniques in data processing.

 

Reference:

Furusho-Percot, C., Goergen, K., Hartick, C., Kulkarni, K., Keune, J. and Kollet, S. (2019). Pan-European groundwater to atmosphere terrestrial systems climatology from a physically consistent simulation. Scientific Data, 6(1).
Mapping tectonic strain in the central Alpine-Himalayan Belt with Sentinel-1 InSAR and GNSS observations
Authors: Rollins Chris , Wright Tim , Weiss Jonathan , Hooper Andrew , Walters Richard , Lazecky Milan , Maghsoudi Yasser
Published: March 2021

Geodetic measurements of crustal deformation provide crucial constraints on a region’s tectonics, geodynamics and seismic hazard. However, such geodetic constraints have traditionally been hampered by poor spatial and/or temporal sampling, which can result in ambiguities about how the lithosphere accommodates strain in space and time, and therefore where and how often earthquakes might occur. High-resolution surface deformation maps address this limitation by imaging (rather than presuming or modelling) where and how deformation takes place. These maps are now within reach for the Alpine-Himalayan Belt thanks to the COMET-LiCSAR InSAR processing system, which performs large-scale automated processing and time-series analysis of Sentinel-1 InSAR data. Expanding from our work focused on Anatolia, we are combining LiCSAR products with GNSS data to generate high-resolution maps of tectonic strain rates across the central Alpine-Himalayan Belt. Then, assuming that the buildup rate of seismic moment (deficit) from this geodetically-derived strain is balanced over the long term by the rate of moment release in earthquakes, we pair these strain rate maps with seismic catalogs to estimate the recurrence intervals of large, moderate and small earthquakes throughout the region. We also use arguments from dislocation modeling to identify two key signatures of a locked fault in a strain rate field, allowing us to convert the strain maps to “effective fault maps” and assess the contribution of individual fault systems to crustal deformation and seismic hazard. Finally, we address how to expand these approaches to the Alpine-Himalaya Belt as a whole.
Transient cusp ionospheric disturbances caused by a solar wind dynamic pressure enhancement
Authors: Liu Jianjun
Published: March 2021

Interplanetary (IP) shock driven sudden compression produces disturbances in the polar ionosphere. Various studies have investigated the effects of IP shock using imagers and radars. However, very few studies have reported the plasma flow reversal and a sudden vertical plasma drift motion following a CME driven IP shock. We report on the cusp ionospheric features following an IP shock impingement on 16 June 2012, using SuperDARN radar and digisonde from the Antarctic Zhongshan Station (ZHO). SuperDARN ZHO radar observed instant strong plasma flow reversal during the IP shock driven sudden impulse (SI) with a suppression in the number of backscatter echoes. Besides, we also report on a “Doppler Impulse” phenomenon, an instant and brief downward plasma motion, were observed by the digisonde in response to the SI and discuss the possible physical causes. Geomagnetic disturbance and convection patterns indicate the flow reversal was generated by the downward field-aligned current (FAC). We speculate that sudden enhancement in ionization associated with SI is responsible for generating the Doppler Impulse phenomenon.
Numerical modelling of deformation and fracturing of thermo-poroelastic media
Authors: Stefansson Ivar , Keilegavlen Eirik , Berre Inga
Published: March 2021

In addition to significantly impacting flow properties, fractures may deform and propagate due to changes in the stress state. Such stress changes may e.g. be caused by changes in fluid pressure or rock temperature. Accounting for all interacting processes and structures leads to a tightly coupled and highly complex system.

We apply a mixed-dimensional model explicitly accounting for both rock matrix and fractures, the latter as two-dimensional objects. This framework enables tailored modeling in the different parts of the domain. We impose conservation of mass and energy in both fractures and matrix and conservation of momentum in the matrix. At the fractures, we impose contact mechanics relations and propagation criteria based on the local stress state. Coupling between fractures and matrix is formulated as interdimensional fluid and heat fluxes and displacement at the two fracture surfaces.

We demonstrate the model through three-dimensional transient simulations focusing on process-structure interaction. That is, we investigate the interplay between thermo-hydraulic processes and fracture deformation, including propagation of pre-existing fractures.
Validity domains and parametrizations for white-noise and multiscale models in turbulence and wave-turbulence interactions
Authors: resseguier valentin , Hascoet Erwan , Chapron Bertrand , Fox-Kemper Baylor
Published: March 2021

Geophysical fluid dynamics systems generally involve a wide range of spatio-temporal scales. Numerical representation can only simulate some of the scales. The others, at the unresolved scales of motion, must be parameterized for each type of phenomenon (wave, eddy, current), in terms of expected effects on the resolved scales. Most developments then assume that the fluid transport velocity has a time-uncorrelated noisy component with zero mean and stationary statistics. These approximations generally simplify theoretical descriptions, numerical simulations, data comparisons or more recently model error quantifications for data assimilation.

In the present work, we will discuss the applicability of such approximations through two examples: a surface oceanic current dynamics and swell refractions by surface currents.

When the time-decorrelation assumption is valid, we propose simple and tuning-free parametric models to represent the spatial correlations of the white-in-time small-scale velocity to help simulate the geophysical system of interest. These parametric models relies on turbulence space self-similarity and their statistical properties (e.g. spectral slope) can be easily estimated from observations of larger scale fluid velocities.

When the white-in-time approximation is not valid, we extend the previous parametric models to follow self-similarity properties in both time and space.

Numerical simulations will illustrate these theoretical developments along the presentation.
Analysis of floodplain forest sensitivity to drought
Authors: Kowalska Natalia , Šigut Ladislav , Stojanović Marko , Fischer Milan , Kyselova Ina , Pavelka Marian
Published: March 2021

Floodplain forests are very complex, productive ecosystems, capable of storing huge amounts of soil carbon. With the increasing occurrence of extreme events, they are today among the most threatened ecosystems. Our study’s main goal was to assess the productivity of a floodplain forest located at Lanžhot in the Czech Republic from two perspectives: carbon uptake (using an eddy covariance method) and stem radius variations (using dendrometers). We aimed to determine which conditions allow for high ecosystem production and what role drought plays in reducing such production potential. Additionally, we were interested to determine the relative soil water content threshold indicating the onset and duration of this event. We hypothesized that summer drought in 2018 had the most significant negative effects on the overall annual carbon and water budgets. In contrast with our original hypothesis, we found that an exceptionally warm spring in 2018 caused a positive gross primary production (GPP) and evapotranspiration (ET) anomaly that consequently led in 2018 to the highest seasonal total GPP and ET from all of the investigated years (2015–2018). The results showed ring-porous species to be the most drought resistant. Relative soil water content threshold of approximately 0.45 was determined as indicating the onset of drought stress.
Using artificial neural networks with joint muon-gravity datasets for shallow subsurface density prediction at volcanoes
Authors: Cosburn Katherine , Roy Mousumi
Published: March 2021

The ability to accurately and reliably obtain images of shallow subsurface anomalies within the Earth is important for hazard monitoring at many geologic structures, such as volcanic edifices. In recent years, the use of machine learning as a novel, data-driven approach to addressing complex inverse problems in the geosciences has gained increasing attention, particularly in the field of seismology. Here we present a physics-based, machine learning method to integrate disparate geophysical datasets for shallow subsurface imaging. We develop a methodology for imaging static density variations at a volcano with well-characterized topography by pairing synthetic cosmic-ray muon and gravity datasets. We use an artificial neural network (ANN) to interpret noisy synthetic datasets generated using theoretical knowledge of the forward kernels that relate these datasets to density. The deep learning model is trained with synthetic data from a suite of possible anomalous density structures and its accuracy is determined by comparing against the known forward calculation. 

In essence, we have converted a traditional inversion problem into a pattern recognition tool, where the ANN learns to predict discrete anomalous patterns within a target structure. Given a comprehensive suite of possible patterns and an appropriate amount of added noise to the synthetic data, the ANN can then interpolate the best-fit anomalous pattern given data it has never seen before, such as those obtained from field measurements. The power of this approach is its generality, and our methodology may be applied to a range of observables, such as seismic travel times and electrical conductivity. Our method relies on physics-based forward kernels that connect observations to physical parameters, such as density, temperature, composition, porosity, and saturation. The key benefit in using a physics-based approach as opposed to a data-driven one is the ability to get accurate predictions in cases where the amount of data may be too sparse or difficult to obtain to reliably train a neural network. We compare our approach to a traditional inversion, where appropriate, and highlight the (dis)advantages of the deep learning model.
Investigating cave responses to regional climate change: an approach to calibrate speleothem proxies in Madagascar
Authors: Voarintsoa Ny Riavo G. , Ratovonanahary Antsa Lal’Aina J. , Rakotovao Avotriniaina Z. M. , Bouillon Steven
Published: March 2021

Caves are an excellent natural laboratory for understanding the transfer processes of the region’s environmental signals to speleothems. At least eight speleothems have produced high resolution paleoclimate and paleoenvironment records from Anjohibe Cave, NW Madagascar. However, due to the remote and difficult access to many caves in Madagascar, no studies have yet been done to understand the transfer of climate and environmental changes of the region to the cave. This is the first monitoring study to understand the linkage between regional climatology and various responses in Anjohibe Cave. We monitored (1) the drip water pH, TDS, EC, temperature, δ13CDIC, δ18Ow, δ2Hw, and elemental (Ca, Mg, Sr) composition, and (2) the cave atmosphere pCO2, relative humidity and temperature. Results show that air-to-air transfer is fast, and the internal parameters closely vary with the regional climatology. In contrast, rainfall to drip signal transfer is not immediate, and it can take few months to one season for the signals to be detected in the drip water due to the “epikarst storage effect”. The deposition of CaCO3 is inferred to occur late in the dry austral winter season, during which prior carbonate precipitation was also detected. Since the growth of speleothems is influenced by numerous cave-specific factors, this study, although preliminary, indicates that Anjohibe Cave drip waters are capable of registering changes in its surrounding environment. A longer monitoring study is expected in the future to constrain the timing and the mode of transfer.
Northern Hemisphere Glaciation, African Climate and Evolution
Authors: Trauth Martin H. , Asrat Asfawossen , Berner Nadine , Bibi Faysal , Foerster Verena , Grove Matt , Kaboth-Bahr Stefanie , Maslin Mark A. , Mudelsee Manfred , Schaebitz Frank
Published: March 2021

The hypothesis of a connection between the onset (or intensification) of Northern Hemisphere Glaciation (NHG), the stepwise increase in African aridity (and climate variability) and an important mammalian (including hominin) species turnover is a textbook example of the initiation of a scientific idea and its propagation in science. It is, however, also an example of the persistent popularity of a hypothesis despite mounting evidence against it. The first part of our work analyzes of the history of the scientific idea by seeking its roots, including coincidental meetings and exchanges between of scientists, at project meetings, conferences and workshops. The consequences of this idea are examined and its influence on subsequent scientific investigations both before and after it has been falsified. In the second part of our investigation, we examine why the idea that the high latitudes have a major control on the climate of the low latitudes and thus early human evolution persists. For this purpose, an attempt is made to understand the original interpretation of the data, with special consideration of the composition of the scientific team and their scientific backgrounds and persuasions. Some of the key records in support of the hypothesis of a step-wise transition will be statistically re-analyzed by fitting change-point models to the time series to determine the midpoint and duration of the transition – in case such a transition is found in the data. A critical review of key publications in support of such a connection and a statistical re-analysis of key data sets leads to three conclusions: (1) Northern Hemisphere Glaciation is a gradual process between ~3.5–2.5 Ma, not an abrupt onset, either at ~2.5 Ma, nor at ~2.8 Ma, or any other time in the Late Cenozoic Era, (2) the trend towards greater aridity in Africa during this period was also gradual, not stepwise in the sense of a consistent transition of a duration of ≤0.2 Ma, and (3) accordingly, a step-wise change in environmental conditions cannot be used to explain an important mammalian (including hominin) species turnover.
Damage-cost assessment of vernacular buildings against coastal flooding
Authors: Narendr Aishwarya , Das Sutapa , H.  Aithal Bharath
Published: March 2021

Coastlines across the globe have been experiencing threats due to rising sea-level. The global average rise in the annual sea level is projected to be 2 -3 mm putting the coastlines across the globe into a threat. South-East Asian countries would experience sea-level variation from 1.5 mm to 4.4 mm per year, exacerbating inundation risk due to tidal anomalies. Many of these countries bear relatively higher population density and fall under developing economy – hence under-equipped to follow proactive strategies for adaptation.

Recurring flood hazard incapacitates regional sustainability. Rapidly changing climate scenarios further add to the climate-hazard sensitivity by increasing the frequency of extremes. The coastal communities experience multiple threats of such climate sensitivity due to rising sea-level and high tide anomalies In the form of loss of life and livelihood, overbearing losses from disaster-related damages to the infrastructure damages. Particularly those associated with residential building impose significant liability on marginal groups, presenting ‘disaster recovery’ nearly an impossible target to achieve. Therefore, damage reduction becomes an inevitable parameter for disaster risk reduction (DRR).

This research presents a methodology for the assessment of vernacular building typology in coastal areas of Sundarbans in eastern India. The area adjoining the Bay of Bengal is the part of largest Mangrove delta in the world The case area, Sagar Island has 75 percent of its population residing within traditional housing system that is now under potential economic stress due to reoccurring floods. The process begins with probing insight on the damage and failure pattern induced by floodwater to the housing and helps in the development of a systematic framework for ‘damage preventing intervention’ for primary building typology. The study categorizes damage stages associated with the high tide flooding levels using the synthetic method of data collection. This is followed by damage cost calculation for the flood levels considering the available remedies. Therefore, suggesting a proactive approach for disaster resilient design depending on robustness and cost-effectiveness of the chosen remedies. As the vernacular buildings are still a popular habitat choice in various parts of developing/ urbanizing South Asia, the research finds a generic application for upgrading vernacular housing design standards for regional sustainability.

Keywords: flood hazard, high tide flooding, climate change, vernacular housing, damage assessment
The effect of ocean model tidal-forcing and spatial resolution on virtual particle dispersion and accumulation at the ocean surface
Authors: Gomez-Navarro Laura , van Sebille Erik , Albert Aurelie , Molines Jean-Marc , Brodeau Laurent , Le Sommer Julien , Ubelmann Clement
Published: March 2021

Understanding the pathways of floating material (e.g. larvae, plastics, oil) at the surface ocean is important to improve our knowledge on the surface circulation and for its ecological and environmental impacts.  For example, knowing where floating plastic and oil spills accumulate in the surface ocean can help ocean clean-up strategies.  One of the main methods of research is virtual particle simulations, which simulate the dispersion of floating material in the Ocean.  

 

Previous studies have tried to understand the surface dispersion and accumulation via these numerical simulations. To define the circulation, the velocity outputs of ocean general circulation models are needed. Oceanic models have improved in the past years, but many still do not fully represent the ocean dynamics at the fine-scales (below 100 km).  The spatial resolution of ocean models and whether they include a tidal-forcing are two important model parameterizations that can determine how well the ocean dynamics are represented at the fine-scales. In this study we try to answer: How do these model characteristics affect the dispersion and accumulation of virtual particles at the ocean surface?

 

To answer this, we use the ocean surface velocity outputs of different NEMO simulations to simulate the trajectories of virtual particles, and we evaluate the impact of different NEMO simulations’ spatial resolution and the presence or not of a tidal-forcing. As tidal-forcing has a big impact on the ocean model’s representation of internal tides and waves, we focus on a region where there is a high internal-tide signal: the Azores Islands.  We evaluate these impacts by looking at whether there is a difference in particles’ accumulation and dispersion in the different model scenarios.
Identifying key determinants of ecosystem health in the middle reaches of Yangtze River Urban Agglomerations, China
Authors: Ge Fengjian , Li Jiangfeng , Chen Wanxu , Ouyang Shubing , Han Peng , Ye Shipeng
Published: March 2021

With the rapid development of urbanization in China, urban circles and urban agglomerations are gradually formed among different cities, which in turn has brought large pressure to the ecological environment. As an important monitoring index for evaluating the sustainable development of cities, quantified evaluation on the eosystem health is lacked for urban agglomerations. In this study, ecosystem health was assessed based on the framework of ecosystem vigor, organization, resilience, and services (VORS) in the Middle Reaches of the Yangtze River Urban Agglomerations (MRYRUA) in 2000, 2005, 2010, and 2015 with county as research units. Using GeoDetector to quantitatively analyze the impact of seven factors (including the proportion of construction land, forest land, and water, land use degree, population, average annual precipitation, and digital elevation model (DEM)) on ecosystem health in different periods. The results showed that: (1) There were significant differences in the spatial distribution of ecosystem health. The ecosystem health in the central area of Wuhan Metropolis, Changsha-Zhuzhou-Xiangtan City Group, and Poyang Lake City Group were significantly lower than the surrounding areas; (2) From the time scale, the research units of ordinary well level gradually develop to relatively well and well levels. The research units of relatively weak and weak level remain relatively stable. (3) Land use degree was the main factor affecting on ecosystem health. Moreover, there were interactions between different factors affecting. The impact of factors on ecosystem health were bi-enhanced or nonlinear enhanced. (4) The impacts of the proportion of construction land on ecosystem health had become greater over the time, and risen from fourth in 2000 to second in 2015. Therefore, a reasonable layout of urban land use planning has an important impact on the ecosystem health.
Crustal structures of southern Mongolia from seismic anisotropy and gravity analysis
Authors: Guy Alexandra , Tiberi Christel , Mijiddorj Saandar
Published: March 2021

This study integrates gravity modelling and analysis with seismic constraints through the prism of seismic anisotropy to characterize the structures of southern Mongolia, in particular at the lower crustal but also the upper mantle levels. Recently, gravity signal analysis and forward modelling combined with magmatic geochemistry and thermodynamic modelling demonstrate that relamination of allochtonous felsic to intermediate lower crust played a major role in southern Mongolia structure. Relamination of material induces a homogeneous layer in the lower crust, which contrasts with the highly heterogeneous upper crustal part composed of different lithotectonic domains. The seismic signals of the seven southernmost stations of the MOBAL2003 experiment were analyzed to get the receiver functions. The data treatment was performed following a new protocol, which reduces the noise on the different components. This treatment reveals the variation of the crustal thickness of cca. 10 km along the first 450 km of the profile. In addition, some seismic stations display significant signals related to the occurrence of a low velocity zone (LVZ) at lower crustal and upper mantle levels. The depth of the Moho discontinuity and the dips of the seismic interfaces obtained from the seismic inversions as well as the boundaries of the different tectonic zones constitute the starting points from the 2D forward gravity modelling along the southern part of the MOBAL 2003 profile. Moreover, the density values applied to the different blocks were determined according to the global lithological composition of the different units and the vergences of the tectonic contacts were constrained by the geodynamic studies. The gravity modelling reveals the occurrence of a low density zone in the lower crust beneath the four southernmost seismic stations, which corresponds to the LVZ observed with the receiver function analysis. The combination of the independent methods enhances the occurrence of a low velocity and a low density zone (LVLDZ) at lower crustal level beneath the southernmost part of the MOBAL 2003 seismic profile. These LVLDZ may demonstrate the existence of the relamination of a hydrous material in southern Mongolia.
Addressing challenges in biodiversity conservation with fish otolith death assemblages: the state-of-the-art
Authors: Agiadi Konstantina , Albano Paolo G.
Published: March 2021

Fish otoliths are incrementally growing aragonitic elements found in the inner ear of most fishes. They have species-specific morphology that enable species level identification and they are excellent high-resolution recorders of ambient water conditions, enabling the reconstruction of past fish faunas and their environment. Although they have been studied as fossils for almost 150 years, and they are very useful tools for tracking lifestyle and population changes in modern fishes, otolith death assemblages recovered from sea bottom sediments have been studied only much more recently. Still, these fish remains can provide valuable insight into past fish faunas before most anthropogenic impacts, such as climate warming, habitat modification and biological invasions. Here, we present an overview of research done until now on otolith death assemblages highlighting their applications for marine conservation.
Plant trait analysis to determine effective annual cover crops for Spanish orchards
Authors: Ripley Helena , Stevens Carly , Quinton John
Published: March 2021

This paper investigates the use of plant trait analysis on cover crop species, and the impact selected species had on soil chemistry in a Spanish olive orchard. Farmers with hillside orchards in Spain frequently remove vegetation between tree rows due to concerns about water competition in the semi-arid environment. However, this increases the vulnerability of the soil to water erosion. Despite research showing that annual cover crops control soil loss, there has been little uptake of this form of management by farmers.

Ten species, native to southern Spain which had previously been used in cover crop experiments, and for which the seed was low cost, were assessed with plant trait analysis. Above and below ground traits, including specific leaf area, total biomass, root diameter and root volume, were examined to indicate the potential of the plants to reduce splash erosion, runoff and soil detachment. Four of the species were then selected and used in monocultures and mixes in an olive orchard set up in collaboration with CSIC in Cordoba. Soil moisture, rainfall, temperature and soil cover data was collected. Chemical analysis of plant and soil samples is to take place in January 2021.

Brachypodium distachyon, Calendula arvensis, Medicago sativa and Medicago truncatula had the most potential as cover crop species. In the field, the treatment with the greatest number of species (two grasses, one legume and one forb) had the highest mean soil cover at 78 ± 16%. It is hypothesised that the plots in which the greatest cover was established would show the greatest change in soil chemistry and that, where the legume was planted there will be higher nitrogen in the soil.

This presentation will outline the plant traits analysed, the outcomes of this analysis and the impact selected plants had on plant and soil chemistry in the field.
Multiple pulses in lacustrine turbidites reveal earthquake doublets
Authors: Wils Katleen , Deprez Maxim , Kissel Catherine , Vervoort Morgan , Van Daele Maarten , Daryono Mudrik R. , Cnudde Veerle , Natawidjaja Danny H. , De Batist Marc
Published: March 2021

Earthquake doublets form a particular challenge for seismic hazard assessment and can provide insights into potentially characteristic fault behaviour. However, knowledge on this type of earthquake sequences is limited to information provided by historical archives as their identification in paleoseismic records is ambiguous. The continuous sedimentation records provided by lacustrine settings might be able to resolve closely-timed earthquakes, but confident identification of earthquake doublets has, up to now, not been made. To reveal the potential of these high-resolution records, we perform a detailed analysis of a multi-pulsed turbidite that has been identified in the sedimentary infill of Lake Singkarak and that was generated by the March 2007 West Sumatra earthquake doublet (i.e. two Mw>6 shocks on adjacent fault segments at 2 hours apart). In order to distinguish non-synchronously generated pulses in this turbidite (different earthquake, same turbidite source area) from those that are potentially synchronously-generated (same earthquake, different turbidite source areas), we develop a new methodology that allows analysing paleoflow directions by using grain-size analysis, natural remanent magnetization measurements and high-resolution X-ray computed tomography. Combining these techniques allows us to reveal the absolute geographical orientation of elongated grains, which are considered to be deposited aligned to the dominant paleoflow direction. Application to the 2007 turbidite in Lake Singkarak allows identifying the presence of non-synchronously generated pulses, thus confirming that each earthquake in the 2007 West Sumatra doublet triggered separate turbidity currents in the lake. Our study thus underscores the invaluable sensitivity of lacustrine paleoseismic records and outlines a promising methodology to analyse previously-described multi-pulsed lacustrine turbidites to reveal the occurrence of, up to now, unknown earthquake doublets.