bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating rainfall and catchment attributes promoting heavy-tailed distributions of river flows
Authors: Wang Hsing-Jui , Yang Soohyun , Merz Ralf , Basso Stefano
Published: March 2021

Heavy-tailed probability distributions of streamflow are frequently observed in river basins. They indicate sizable odds of extreme events in these catchments and thus signal the existence of enhanced hydrological perils. Notwithstanding their relevance for characterizing the hydrological hazard of river basins, identifying specific mechanisms which promote the emergence of heavy-tailed flow distributions has proved challenging due to the complex hydrological response of such dynamical systems exposed to highly variable rainfall inputs.

In this study we combine a continuous hydrological model grounded on the geomorphological theory of the hydrologic response with archetypical descriptions of the spatial and temporal distributions of rainfall inputs and catchment attributes to investigate physical mechanisms and stochastic features leading to the emergence of heavy tails.

In the model, soil moisture dynamics driven by the water balance in the root zone trigger superficial and subsurface runoff contributions, which are routed to the catchment outlet by means of a representation of transport by travel time distributions. The framework enables a parsimonious distributed description of hydrological processes, suitably considered with their stochastic character, and is thus fit for the goal of investigating manifold mechanisms promoting heavy-tailed streamflow distributions.

A set of archetypical spatial and temporal variabilities of rainfall inputs and catchment attributes (e.g., localized versus uniform rainfall in the catchment, lumped versus distributed catchment attributes, mainly upstream versus downstream source areas, high versus low rainfall frequency) are finally imposed in the model and their capability (or not) to affect the tail of the streamflow distribution is investigated.

The proposed framework provides a way to disentangle physical attributes of river catchments and stochastic properties of hydroclimatic variables which control the emergence of heavy-tailed streamflow distributions and thus identify the key drivers of the inherent hydrological hazard of river basins.
Timing and magnitude of runoff in Austrian mountain catchments in a warming climate
Authors: Hanus Sarah , Zekollari Harry , Schoups Gerrit , Kaitna Roland , Hrachowitz Markus
Published: March 2021

Hydrological regimes of alpine catchments are expected to be strongly influenced by climate change due to their dependence on snow dynamics. While seasonal changes have been studied extensively, studies on changes in the timing and magnitude of annual extremes remain rare. This study investigates the effects of climate change on runoff patterns in six alpine catchments in Austria by using a topography-driven semi-distributed hydrological model and 14 climate projections for RCP 4.5 and RCP 8.5. The study catchments represent a range of alpine catchments, from pluvial-nival to nivo-glacial, as the study focuses on providing a comprehensive picture of future runoff changes on catchments at different altitudes. Simulations of 1981-2010 are compared to projections of 2071-2100 by examining changes in timing and magnitude of annual maximum and minimum flows as well as monthly discharges.

Our results indicate a substantial shift to earlier occurrences in annual maximum flows by 9 to 31 days on average and an extension of the potential flood season by 1 to 3 months for high elevation catchments. For lower elevation catchments, changes in timing of annual maximum flows are less pronounced. Magnitudes of annual maximum flows are likely to increase, with four catchments exhibiting larger increases under RCP 4.5 compared to RCP 8.5. The timing of minimum annual discharges shifts to earlier in the winter months for high elevation catchments, whereas for lower elevation catchments a shift from winter to autumn is observed. While all catchments show an increase in mean magnitude of minimum flows under RCP 4.5, this is not the case for two low elevation catchments under RCP 8.5.

Our results suggest a relationship between the altitude of catchments and changes in timing of annual maximum and minimum flows and magnitude of low flows, whereas no relationship between altitude and magnitude of annual maximum flows could be distinguished.
Drivers and future changes in simultaneous extremes and their implications for global food security
Authors: Kornhuber Kai , Lesk Corey , Pfleiderer Peter , Jägermeyer Jonas , Schleussner Carl-Friedrich , Horton Radley
Published: March 2021

In a strongly interconnected world, simultaneous extreme weather events in far-away regions could potentially impose high-end risks for societies. In the mid-latitudes, amplified Rossby waves are associated with a strongly meandering jet-stream causing simultaneous heatwaves and floods across multiple major crop producing regions simultaneously with detrimental effects on harvests and potential implications for global food security.

While no scientific consensus on future changes in these wave events has been established so far, impacts of associated extremes are expected to become more severe due to thermodynamic factors alone, possibly enhancing crop production co-variability across major breadbasket regions and amplifying future risks of multiple harvest failures.

Quantifying future changes in crop co-variability linked to amplified Rossby waves faces a key challenge: Models need to exhibit sufficient skill along a chain of complex and non-linear features, namely i. Rossby Wave characteristics, ii. location and magnitude of associated surface extremes and iii. respective yield response. Here we investigate those relationships in the latest CMIP6 and GGCMI model simulations, providing preliminary results on future changes in crop production co-variability, linked to amplified Rossby waves.
Using convolutional neural networks to detect giant landslides in the Patagonian Andean foreland
Authors: Schönfeldt Elisabeth , Tomáš Pánek , Diego Winocur , Oliver Korup
Published: March 2021

The Andean foreland of Patagonia features dozens of basaltic plateaus that are spread out from the Argentinean province of Neuquén south to Tierra del Fuego. The plateau margins are undermined by numerous giant slope failures that mostly involved a combination of lateral spreading and rotational sliding, running out up to several kilometres along the plateau margins. However, the overall extent of plateau margins affected by landsliding is still unknown, because manual mapping of such a large area (~500.000 km²) is time-consuming. Therefore, our goal is to test methods that support manual mapping by an automatic and objective detection of giant landslides. All of these landslides share very similar topographic features such as subparallel compression ridges and elongate depressions, distinguishing them in terms of their topographic and optical appearance from surrounding areas (e.g. plains or plateau tops). Using a catalogue of these features, we tested an image classification scheme using convolutional neural networks (CNNs). Our input data consist of Sentinel-2 optical data (20-m resolution) and topographic factors (surface roughness and curvature) acquired from TanDEM-X data (12-m resolution). We applied transfer learning, modifying the pre-existing CNN alexnet to test how well it is able to distinguish different geomorphic features such as unstable terrain from plateau tops or plains. Over 4000 training images were extracted from the Meseta Somuncurá, while the trained algorithm was tested at the Sierra Cuadrada. Both plateaus are part of the Northern Patagonia Massif. Preliminary results show that the modified algorithms performs reasonable and is able to distinguish between giant landslides and other geomorphic features. However, performance strongly depends on the training options of the stochastic gradient descent within the CNN and image quality of the training images, especially the quantity of images and their extracted location with respect to the plateau margin.
Investigating current structures in 3D-3V hybrid Vlasov simulations of turbulence
Authors: Faganello Matteo , Sisti Manuela , Fadanelli Sid , Cerri Silvio Sergio , Califano Francesco , Agullo Olivier
Published: March 2021

In space and astrophysical plasmas magnetized coherent structures continuously emerge as an outcome of the nonlinear dynamics. These structures are characterized  by the presence of localized strong current density peaks. Here we present a statistical study of the development of such structures resulting in different hybrid-Vlasov 3D-3V simulations of plasma turbulence. In particular, we make use of different methods to characterize the global shape of the 3D structures. Furthermore, we study the local magnetic configuration inside and outside current peak regions, comparing the statistics in the two cases. Finally, we discuss correlations between characteristic dimensions of the current structures and current density, marking the difference between magnetic structures in 2D and 3D simulations.
Tropospheric response to stratospheric momentum torques
Authors: White Ian , Garfinkel Chaim
Published: March 2021

An idealised model is used to examine the tropospheric response to stratospheric momentum torques with an emphasis on the response to high-latitude sudden stratospheric warmings (SSWs). Previous related studies have generally imposed such torques in models that lack a key element of realism; for instance, models that do not have a realistic stratosphere, models without stationary planetary waves (i.e., without topography), and models that do not have a troposphere and so precludes any investigation of a downward impact. The idealised moist model of an atmosphere (MiMA) used here overcomes these three shortcomings and is hence well-suited to study the downward impact of extreme events in the stratosphere in a more realistic setup. In particular, we impose transient zonally-symmetric momentum forcing to various latitude bands in the stratosphere, spun-off from a free-running control run (CTRL). In addition to varying the latitudinal location of the forcing, we vary the depth, duration and magnitude to examine the sensitivity of the tropospheric response. Preliminary results show that in contrast to thermally-forced SSWs for which the initial 'Eliassen adjustment' (i.e., the meridional circulation response during the forcing period) is opposite to that found during free-running SSWs, the momentum-forced events here, produce a meridional circulation that mimics that found in the free-running events. This meridional circulation immediately transfers the imposed momentum forcing to the surface, projecting onto the tropospheric Northern Annular Mode (NAM) and initiating a synoptic-wave feedback, a process that takes much longer to develop in the thermally-forced SSWs. Hence, a sudden and strong enough wave forcing (approximated here by an imposed momentum torque) can induce a meridional circulation that penetrates deep into the troposphere and immediately initiate a tropospheric NAM response. The applicability of these experiments to the real atmosphere will be discussed via comparing the evolution of the forced events to free-running SSWs identified in CTRL.
Nordic EPOS - A FAIR Nordic EPOS Data Hub
Authors: Korja Annakaisa , Atakan Kuvvet , Voss Peter H. , Roth Michael , Vogfjord Kristin , Kozlovskaya Elena , Tanskanen Eija I. , Junno Niina , Working Group Nordic Epos
Published: March 2021

Nordic EPOS - A FAIR Nordic EPOS Data Hub – is a consortium of the Nordic geophysical observatories financed by NordForsk. It is delivering on-line data to European Plate Observing System’s Thematic Core Services (EPOS’s TCSs). Nordic EPOS consortium comprises of the Universities of Helsinki, Bergen, Uppsala, Oulu and GEUS and Icelandic Meteorological Office. Nordic EPOS enhances and stimulates the ongoing active Nordic interactions related to Solid Earth Research Infrastructures (RIs) in general and EPOS in particular. Nordic EPOS develops expertise and tools designed to integrate Nordic RI data and to enhance their accessibility and usefulness to the Nordic research community. Together we can address global challenges in Norden and with Nordic data.

The Nordic EPOS’s main tasks are to advance the usage of multi-disciplinary Solid Earth data sets on scientific and societal problem solving, increase the amount of open, shared homogenized data sets, and increase the scientific expertise in creating sustainable societies in Nordic countries and especially in the Arctic region. In addition to developing services better suited for Nordic interest for EPOS, Nordic EPOS will also try to bring forward Nordic research interest, such as research of Arctic areas in TCSs and EPOS-ERIC governance and scientific boards.

The Nordic EPOS is organized into Tasks and Activities. The project has six main infrastructure TASKs: I - Training in usage of EPOS-RI data and services; II - Nordic data integration and FAIRness; III - Nordic station management of seismological networks, IV - Induced seismicity, safe society; V - Ash and gas monitoring; and VI- Geomagnetic hazards. In addition, the project has one transversal TASK VII on Communication and dissemination. The activities within the TASKs are workshops, tutorials, demos and training sessions (virtual and on-site), and communication and dissemination of EPOS data and metadata information at local, national and international workshops, meetings, and conferences.
Time-window into the transcrustal plumbing system dynamics of Dominica (Lesser Antilles)
Authors: Ostorero Léa , Boudon Georges , Balcone-Boissard Hélène , Morgan Daniel J. , d'Augustin Thiebaut , Solaro Clara
Published: March 2021

A transcrustal mush system has been recognized beneath Dominica (Lesser Antilles) with different magma ponding zones that generated a series of pumiceous eruptions from Morne Trois Pitons–Micotrin volcano. Here, the latest, large, pumiceous eruption (Grand Fond - 24 kyrs cal BP) and four, smaller, Plinian eruptions (18-9 kyrs cal BP) are investigated. Pre-eruptive magma dynamics within the mush are unraveled through orthopyroxene phenocrysts by combining a Crystal System Analysis approach (on unzoned and zoned orthopyroxenes) and timescale estimates derived by intracrystalline Fe-Mg interdiffusion modeling. Two magmatic environments are recognized in the mush and have mixed, more or less vigorously, before the successive eruptions. Few interactions between the two magmas began 15-34 years prior to the small Plinian eruptions, but the sustained mixing occurred in the last 2 years. This contrasts with longer timescales (2-80 years) obtained for the larger eruption of Grand Fond with magmas stored deeper. These magma mixing timescales have significant implications for volcanic risk mitigation, with a growing reactivation signal that could be registered at the surface few years prior to the eruptions.
Modulators of soil organic carbon (SOC) stocks and dynamics in an intensively used hummocky landscape in North-East Germany
Authors: Öttl Lena Katharina , Wilken Florian , Sommer Michael , Fiener Peter
Published: March 2021

The young moraine landscape of North-East Germany is highly prone to tillage-dominated soil erosion processes due to highly mechanised farming in a rolling topography. The corresponding soil redistribution pattern highly influences crop biomass production and soil organic carbon (SOC) dynamics. The aims of the study are to understand the effect of soil redistribution processes on SOC dynamics like dynamic replacement and efficient SOC burial. Therefore, an updated version of the spatially explicit soil redistribution and carbon turnover model SPEROS-C was applied for a large-scale (200 km²) simulation of lateral soil and SOC redistribution and vertical SOC turnover (spatial and vertical resolution 5 m x 5 m and 1 m soil depth, respectively). A sensitivity analysis was applied to identify the dominant modulators of SOC in the modelling approach (carbon input by roots, manure, and residues, decomposition of SOC, etc.). Uncertainties in model structure, process parameterisation, and input data are analysed with the GLUE approach (Generalized Likelihood Uncertainty Estimation). This approach is also used to estimate regional model parameters (e.g. SOC turnover rates, crop-specific root length density distribution, C input by aboveground biomass, manure, residues, etc.) to allow landscape-scale estimations of soil redistribution and accompanied C balance and hence, if this leads to a sink or source of CO2.
Variations of VLF Wave Intensity Analyzed via Principal Component Analysis
Authors: Bezděková Barbora , Němec František , Parrot Michel , Manninen Jyrki , Krupařová Oksana , Krupař Vratislav
Published: March 2021

Wave intensity measured in the very low frequency (VLF) range (up to 20 kHz) is typically represented using frequency-time spectrograms. Since the characterization of spectrogram main features and/or their direct comparison is a challenging task, we transform the measurements of the low-altitude DEMETER spacecraft using the principal component analysis (PCA). The present study is focused on both the physical interpretation of the first two principal components and their application to real physical problems. To understand the physical meaning of the first principal components, their scatter plot is constructed and discussed. Moreover, the dependence of the first principal component (PC1) coefficients on the geomagnetic activity and their seasonal/longitudinal variations are analyzed. The obtained distributions are well comparable with those obtained by previous studies for average wave intensities, indicating that the PC1 coefficients are directly related to the overall wave intensity. Furthermore, the variations of PC1 coefficients around interplanetary (IP) shock arrivals are analyzed, suggesting that the fast forward shock occurrence has the most significant effect. It is shown that the wave intensity variations depend on the wave intensity detected before the shock arrival. The shock strength and interplanetary magnetic field orientation are also important. To further demonstrate the adaptability of PCA, we use a similar method to analyze also ground-based VLF measurements performed by the Kannuslehto station located in northern Finland.
An atmospheric forcing extending ENSO forecast horizon using statistical models
Authors: Feigin Alexander , Mukhin Dmitry , Gavrilov Andrey , Seleznev Aleksei , Buyanova Maria
Published: March 2021

Interseasonal forecasting of El Niño Southern Oscillation (ENSO), which is traditionally based on data of tropical sea surface temperatures (SST), is in high demand due to the impacts of ENSO on regional climatic conditions around the world as well as the global climate. Improvements in the quality of data in recent decades have led to the active use of statistical ENSO models, which compete with physical models in predictive power. The main disadvantage of statistical forecasts is the pronounced seasonal growth of uncertainty when predicting the upcoming summer-fall ENSO conditions from winter-spring months (so called the spring predictability barrier (SPB)). Recent studies show that Pacific atmospheric circulation anomalies in winter-spring may have a long-term impact on the summer tropical climate via the SST footprint. Here, we infer an index based on sea level pressure (SLP) data from February-March in a single area surrounding Hawaii, and show that this area is the most informative part of the large SLP pattern initiating the SST footprinting mechanism. We define the Hawaiian index (HI) as the mean SLP anomalies in the region (130N-190N, 1500W-1600W) averaged over February-March and demonstrate that the statistical AR model of the Niño 3.4 index taking the HI as a forcing is better in the Bayesian sense and delivers significantly better multimonth predictions. In fact, the HI forcing in the model substantially lowers the SPB and hence increases the predictability of the whole June-May ENSO cycle for forecasts starting in spring. Thus, we can recommend that modelers test the HI as an additional predictor in statistical ENSO models.

This research was supported by the Russian Science Foundation (Contract 19-42-04121)
Root system monitoring using a mise-à-la-masse (MALM) extension to time-domain IP
Authors: Mary Benjamin , Iván Veronika , Cassiani Giorgio
Published: March 2021

The development, architecture, and activity of the plant root system has a key role in plant-soil-water interactions, and thus, in plant ecology both in agricultural and natural systems. The characterization of the flow of electric current in the root-soil system may provide non-invasive methodologies to observe the state and dynamics of this critical zone hidden in the shallow subsurface.

Inversion of Current source density (CSD) from Mise-a-la-masse (MALM) surveys provides a straightforward way to describe the shape of a conductive body that charges up. While numerous studies show a correlation between root mass density and electrical capacitance (Ehosioke et al., 2020), physical proofs of the underlying assumptions of such concepts are still missing. In particular, some authors questioned the hypothesis that the xylem behaves as a continuous conductive body with regard to its physiological state. Application of the MALM in conjunction with CSD helps distinguish the current pathway through the root system (Mary et al., 2019; Peruzzo et al., 2020).

As roots are electrically polarisable, their responses depend on the frequency of the current injection. Extending the CSD inversion to secondary voltages produced by secondary currents (after shutting down the primary current) may provide insights into transient phenomena associated with the polarization of the roots.

Based on a Self-Potential (SP) processing algorithm (Shao et al., 2018), we build and test a new inversion scheme of secondary voltages using synthetic models. Small-scale laboratory experiments are in progress on grapevine cuttings placed in water-filled rhizotrons. Root growth will be monitored using MALM in TDIP domain.  
Preliminary results of numerical simulation of submarine landslide-generated waves
Authors: Sabeti Ramtin , Heidarzadeh Mohammad
Published: March 2021

Landslide-generated waves have been major threats to coastal areas and have led to destruction and casualties. Their importance is undisputed, most recently demonstrated by the 2018 Anak Krakatau tsunami, causing several hundred fatalities. The accurate prediction of the maximum initial amplitude of landslide waves (ηmax) around the source region is a vital hazard indicator for coastal impact assessment. Laboratory experiments, analytical solutions and numerical modelling are three major methods to investigate the (ηmax). However, the numerical modelling approach provides a more flexible and cost- and time-efficient tool. This research presents a numerical simulation of tsunamis due to rigid landslides with consideration of submerged conditions. In particular, this simulation focuses on studying the effect of landslide parameters on ηmax. Results of simulations are compared with our conducted physical experiments at the Brunel University London (UK) to validate the numerical model.

We employ the fully three-dimensional computational fluid dynamics package, FLOW-3D Hydro for modelling the landslide-generated waves. This software benefit from the Volume of Fluid Method (VOF) as the numerical technique for tracking and locating the free surface. The geometry of the simulation is set up according to the wave tank of physical experiments (i.e. 0.26 m wide, 0.50 m deep and 4.0 m). In order to calibrate the simulation model based on the laboratory measurements, the friction coefficient between solid block and incline is changed to 0.41; likewise, the terminal velocity of the landslide is set to 0.87 m/s. Good agreement between the numerical solutions and the experimental results is found. Sensitivity analyses of landslide parameters (e.g. slide volume, water depth, etc.) on ηmax are performed. Dimensionless parameters are employed to study the sensitivity of the initial landslide waves to various landslide parameters.
Characterization of the Outer Coast Tuff Formation- A way to unravelling the magmatic processes preceding and triggering Deception Island’s caldera - forming eruption (Antarctica)
Authors: Vilanova Oriol , Aulinas Meritxell , Geyer Adelina , Marti Joan , Álvarez-Valero Antonio , Albert Helena , Gisbert Guillem
Published: March 2021

Deception Island (South Shetland Islands), discovered in 1820, is one of the most active volcanoes in Antarctica with more than 20 eruptions (including the historic eruptions of 1967, 1969 and 1970) and three documented volcanic unrest events (1992, 1999 and 2014-15) over the past two centuries. Deception Island currently hosts two scientific bases, which operate every year during the Austral summer, and is also one of the most popular tourist destinations in Antarctica. The island is a composite volcano with a centrally located caldera of 8.5 x 10 km dated at 3,980 ± 125 yr. BP. During the caldera-forming event, between 30 and 60 km3 (Dense Rock Equivalent-DRE) of magma, erupted in the form of dense basaltic-andesitic pyroclastic density current deposits. During the last decades, Deception Island has been intensively investigated but some aspects regarding the magmatic processes associated with the formation of its caldera collapse are still under research and debate. For instance, characterizing the magmatic conditions and processes that triggered the huge explosive event is crucial to understand the past (and in turn the future) magmatic and volcanic evolution of the island.

This study is performing an exhaustive petrological and geochemical characterization (mineral and juvenile glass geochemistry) of the Outer Coast Tuff Formation (OCTF), the main syn-caldera depositional unit. The preliminary results confirm the existence of two different magmas coexisting, and interacting, prior to (and during) the caldera-forming event. Mineral analyses also allow shedding further light on the magmatic processes occurring in the magma system before the eruption (e.g. fractional crystallization, magma mixing). The presence of alteration minerals such as palagonite and zeolites indicate different magma-water interaction mechanisms occurred during the syn- and post-eruptive episodes in the island.

This research is part of POLARCSIC and PTIVolcan research initiatives. This research was partially funded by the MINECO grants POSVOLDEC(CTM2016-79617-P)(AEI/FEDER-UE) and VOLGASDEC (PGC2018-095693-B-I00)(AEI/FEDER, UE). This research is also supported by the PREDOCS-UB grant.
Hillslope-scale mapping and numerical representation of the subsurface heterogeneity towards an improved process-based hydrological modelling
Authors: Martini Edoardo , Wollschläger Ute , Bittelli Marco , Tomei Fausto , Werban Ulrike , Zacharias Steffen , Roth Kurt
Published: March 2021

One of the major challenges in soil hydrological modelling is due to the fact that soils are heterogeneous at all spatial scales. The identification and accurate representation of such heterogeneity can be crucial for quantifying the subsurface hydrological states and water fluxes.

This work presents the results of an integrated approach for process-based soil hydrological modelling for a highly instrumented hillslope site. The approach builds on the integration of classical soil mapping, on accurate monitoring of soil water dynamics as well as on geophysical measurements for characterising subsurface heterogeneity. It finally integrates the gathered information into a physical model for simulating the soil water dynamics with high spatial and temporal resolution.

At the Schäfertal Hillslope site (Central Germany), the soil monitoring network STH-net provides high-quality data about the soil water dynamics and soil properties at 8 instrumented soil profiles and depths within the unsaturated zone. The soil spatial variability, known from local soil description and sampling, was mapped using time-lapse electromagnetic induction measurements. The geophysical inversion of the data provided depth-resolved information about the subsurface structures in terms of soil-bedrock interface, soil horizons and their spatial continuity along the hillslope transect. Based on this, different versions of the subsurface geometry model were produced and associated to soil hydraulic parameterizations derived from different approaches.

We show the performance of the physical model CRITERIA-3D in reproducing the soil water dynamics for different subsurface models with increasing complexity. Specifically, we highlight and discuss the key challenges that need to be addressed when continuous information about the subsurface heterogeneity is to be mapped in the field with high resolution and represented in a numerical model with fine discretization in three-dimensions.

We conclude that linking state-of-the-art experimental methods to advanced numerical tools, and bridging the gap between different disciplines such as pedology, hydrology and geophysics can be the key for improving our ability to measure, predict and better understand the vadose-zone processes. This will provide important knowledge needed for transferring this approach to larger scales where the accurate quantification of the soil water fluxes is required for a more efficient water management in the context of sustainable food production and climate change.
Hydrological effects of combining Italian alder and blackberry in an agroforestry system in South Africa
Authors: Hoffmeister Svenja , Bohn Reckziegel Rafael , Kestel Florian , Maier Rebekka , Sheppard Jonathan P. , Hassler Sibylle K.
Published: March 2021

Water limitation provides the potential to hinder the productivity of agricultural systems especially in arid and semi-arid regions. In agroforestry systems interactions between trees and crops range from mutually beneficial to critically competing, shaping the demand for resources, such as water. In this study, we investigated the hydrological effects of an Italian Alder (Alnus cordata) windbreak on an irrigated blackberry plantation near Stellenbosch, South Africa. We determine the key components of the water budget in the system and compare them at two positions: alongside the windbreak, and amongst the crop away from the windbreak’s influence.

We measured soil water content depth profiles in the summer months, from October 2019 to March 2020, in both locations with four consecutive time domain reflectometry (TDR) tube sensors, each integrating over 20 cm depth. Potential evapotranspiration (ET) was estimated from site based meteorological observations. We surveyed and classified the local soil, and defined soil chemical and physical properties (e.g. texture, matrix potential). The windbreak structure was measured on a single tree basis (e.g. tree height, volume and biomass) using manual and terrestrial laser scanning methodologies.

The data indicate that high potential ET, caused by high summer temperatures and strong winds, dominates the water budget at the study site, exceeding the water input of the drip irrigation. We found differences in the water dynamics between the two sites, e.g. greater soil water content at greater distances from the windbreak. Possible reasons are: (1) the water demand of trees increases underground competition for water, and/or; (2) microclimatic conditions closer to the windbreak increase ET. Modelling of the windbreak influence on the ET and further analysis of water fluxes will be conducted as next steps to combine the results from the sensors and the joint field campaign.
Un-mixing the effect of post-depositional tillage turbation on OSL age-depth data through measurements and numerical simulations
Authors: van der Meij Marijn , Temme Arnaud , Verhoeven Mark , Reimann Tony
Published: March 2021

Agricultural systems are subject to severe land degradation, because anthropogenic erosion processes, such as tillage erosion, substantially increase erosion rates compared to natural settings. Optically Stimulated Luminescence (OSL) dating is often used to measure the age of depositional layers to quantify rates of landscape change. OSL dating in agricultural systems is however challenging, because the deposits are reworked in the tillage layer even long after their moment of deposition. This post-depositional mixing resets the built-up luminescence signal, which causes an offset between the apparent OSL ages and the actual deposition ages.

In this study we illustrate the effect of post-depositional mixing on geochronological OSL age-depth data from northeastern Germany and we developed tools to un-mix depositional and post-depositional ages. We analyzed 32 OSL samples from five locations in a kettle hole to reconstruct spatial and temporal deposition patterns. We were able to correct our chronologies for post-depositional mixing by tillage by accounting for (pre-)historical plough regimes. Next to these empirical data, we also modified a Soil-Landscape Evolution Model called Lorica to numerically simulate the effect of post-depositional mixing on depositional ages. This combination of measurements and simulations enabled us to constrain the spatial and temporal effects of post-depositional mixing on OSL age-depth data more accurately. This is an important step towards getting a better grip on the dynamics of agricultural landscapes including the associated dates and rates.
MetaDamage Tool: Examining post-mortem damage in sedaDNA on a metagenomic scale
Authors: Everett Rosie , Cribdon Becky , Kistler Logan , Ware Roselyn , Allaby Robin
Published: March 2021

Authentication of ancient sedimentary DNA (sedaDNA) remains central to the interpretation of the proxy for wider understanding of palaeoecological archives. Distinguishing between in-situ, endogenous sedaDNA from that of contamination or modern material also allows for a wider understanding of taphonomy in the deposition and post-depositional process in the formation of the sedaDNA archive. At current, tools for authentication are reliant on single-taxon input and require a significant number of input sequences to identify an established cytosine deamination rate consistent with ancient DNA. We present the MetaDamage tool: a tool that examines cytosine deamination on a metagenomic scale. In this paper we outline the process of and testing of the MetaDamage tool using both authentic sedaDNA sequences and simulated data in order to demonstrate the resolution in which MetaDamage can observe deamination levels consistent with the presence of ancient DNA. The MetaDamage tool offers a method for initial assessment of the presence of ancient sedaDNA and provides a method for a wider understanding of key questions of preservation for palaeoecological reconstruction.
Multi-Frequency and Multi-Temporal InSAR Analysis for Monitoring Land Subsidence, Aswan City, Egypt
Authors: Medhat Noha , Yamamoto Masa-yuki , El-Qady Gad
Published: March 2021

Land deformation due to natural and anthropogenic impacts considered to be one of the challenging environmental problems in the Aswan area located in the southern part of Egypt. Specifically, we applied multi-sensor analysis in order to record the slow rate of subsidence with a high spatial resolution of COSMO-SkyMed (X-band) and Sentinel-1 TOPSAR (C-band) scenes. We proposed multi-temporal DInSAR data analysis by means of ascending and descending orbit tracks during the recent time period of 2012-2017. The stacked DInSAR results reported the occurrence of land subsidence of active urban areas. A strong correlation between the ground truth data, ground leveling, and the estimated Line of Sight (LOS) displacement time series values are reached, assuming the ground deformation controlled by seasonal surface water loading, lithological units, and subsurface water activity. The detection of short-term displacement highlights the priority of groundwater management plans in the affected urban areas.
High-Resolution Carbonate Variability in Red Earth Deposits: Implications for Water Cycling Dynamics during the Late Miocene
Authors: He Tong
Published: March 2021

The late Miocene provides the chance to assess the changing boundary conditions on a warmer world than present. While the climate variability is well understood for the oceanographic records, the water availability and dynamics in terrestrial environment in the densely populated East Asian remains enigmatic. Little is known about the precipitation response to the Antarctic ice-sheets during this time interval. To understand this critical relationship between low- and high-latitude climates, we use a new indicator based on the carbonate variability in Red Earth on the northern Chinese Loess Plateau to reconstruct water availability throughout the interval (7.5–6.9 Ma). Our high-resolution reconstructions show that the carbonate leaching/reprecipitation cycle is dominantly forced by the astronomical parameter obliquity (40-kyr) that is in accord with the Antarctic ice-volume controlled oceanography records at ~7 Ma. Supported by goethite and hematite records in the same site, soil temperatures and precipitations are fully coupled, interpreted as marking the climate pattern of Asian monsoon during the late Miocene. Cyclic correlation between the carbonate variability and the goethite, hematite data, reveal that the obliquity controlled precipitation oscillations were superimposed on a long-term increase of the Asian monsoon, which was synchronous with intensifification of climate cooling, the declining of partial pressure of carbon dioxide, and the growing of Antarctic ice-volume. Combined with the atmospheric- and oceanic-adjustments, we suggest that the cross-equatorial pressure gradient has led to the rise of Asian monsoon.
Interdisciplinary data-constrained 3-D potential field modelling with IGMAS+
Authors: Anikiev Denis , Götze Hans-Jürgen , Bott Judith , Gómez-García Angela Maria , Gomez Dacal Maria Laura , Meeßen Christian , Spooner Cameron , Rodriguez Piceda Constanza , Plonka Christian , Schmidt Sabine , Scheck-Wenderoth Magdalena
Published: March 2021

We introduce a modelling concept for the construction of 3-D data-constrained subsurface structural density models at different spatial scales: from large-scale models (thousands of square km) to regional (hundreds of square km) and small-scale (tens of square km) models used in applied geophysics. These models are important for understanding the drivers of geohazards, for efficient and sustainable extraction of resources from sedimentary basins such as groundwater, hydrocarbons or deep geothermal energy, as well as for investigation of capabilities of long-term underground storage of gas and radioactive materials.

The modelling concept involves interactive fitting of potential fields (gravity and magnetics) and their derivatives within IGMAS+ (Interactive Gravity and Magnetic Application System), a well-known software tool with almost 40 years of development behind it. The core of IGMAS+ is the analytical solution of the volume integral for gravity and magnetic effects of homogeneous bodies, bounded by polyhedrons of triangulated model interfaces. The backbone model is constrained by interdisciplinary data, e.g. geological maps, seismic reflection and refraction profiles, structural signatures obtained from seismic receiver functions, local surveys etc. The software supports spherical geometries to resolve the first-order effects related to the curvature of the Earth, which is especially important for large-scale models.

Currently being developed and maintained at the Helmholtz Centre Potsdam – GFZ German Research Centre, IGMAS+ has a cross-platform implementation with parallelization of computations and optimized storage. The powerful graphical interface makes the interactive modelling and geometry modification process user-friendly and robust. Historically IGMAS+ is free for research and education purposes and has a long-term plan to remain so.

IGMAS+ has been used in various tectonic settings and we demonstrate its flexibility and usability on several lithospheric-scale case studies in South America and Europe.

Both science and industry are close to the goal of treating all available geoscientific data and geophysical methods inside a single subsurface model that aims to integrate most of the interdisciplinary measurement-based constraints and essential structural trends coming from geology. This approach presents challenges for both its implementation within the modelling software and the usability and plausibility of generated results, requiring a modelling concept that integrates the data methods in a feasible way together with recent advances in data science methods. As such, we present the future outlook of our modelling concept in regards to these challenges.
Parent material and organic matter control soil microbial processes in African tropical rainforests 
Authors: Kidinda Kidinda Laurent , Kemi Ologoke Folasade , Vogel Cordula , Kalbitz Karsten , Doetterl Sebastian
Published: March 2021

Microbial processes are one of the key factors driving carbon (C) and nutrient cycling in terrestrial ecosystems, and are strongly controlled by the equilibrium between resource availability and demand. In deeply weathered tropical rainforest soils of Africa, it remains unclear whether patterns of microbial processes differ between soils developed from geochemically contrasting parent material. Here, we investigate patterns of soil microbial processes and their controls in tropical rainforests of Africa. We used soil developed from three geochemically distinct parent material (mafic, felsic, mixed sedimentary rocks) and three soil depths (0−70 cm). We measured microbial biomass C and enzyme activity at the beginning and end of a 120-day incubation experiment. We also conducted a vector analysis based on ecoenzymatic stoichiometry to assess microbial C and nutrient limitations. We found that microbial C limitation was highest in the mixed sedimentary region and lowest in the felsic region, which we propose was related to the strength of contrasting C stabilization mechanisms and varying C quality. None of the investigated regions and soil depths showed signs of nitrogen (N) limitation for microbial processes. Microbial phosphorus (P) limitation increased with soil depth, indicating that subsoils in the investigated soils were depleted in rock-derived nutrients and are therefore dependent on efficient nutrient recycling. Microbial C limitation was lowest in subsoils, indicating that subsoil microbes cannot significantly participate in C cycling and limit C storage if oxygen is not available, but can do so in our laboratory incubation experiment under well aerated conditions. Using multivariable regressions, we demonstrate that microbial biomass C normalized to soil organic C content (MBCSOC) is controlled by soil geochemistry and substrate quality, while microbial biomass C normalized to soil weight (MBCSoil) is predominantly driven by resource distribution (i.e., depth distribution of organic C). We conclude that due to differences in resource availability, microbial processes in deeply weathered tropical rainforest soils greatly vary across geochemical regions.
Global hydro-meteorological anomalies associated with vegetation productivity extremes
Authors: Kroll Josephin , Denissen Jasper , Li Wantong , Orth René
Published: March 2021

Vegetation productivity is generally governed by water and energy availability. In arid regions, it is usually water-controlled (i.e. soil moisture), whereas in humid regions it is mainly influenced by energy variables (i.e. incoming radiation). Shifts within or even between these regimes might result from hydro-meteorological extremes. For example, during droughts vegetation might become water-limited even in typically energy-controlled regions. In this context, the aim of our analysis is to detect the difference between the controls of average and extreme vegetation productivity.

For this purpose, we use global satellite-based Sun-Induced Chlorophyll Fluorescence (SIF) data as a proxy for vegetation productivity alongside several hydro-meteorological variables. We select the three largest positive and negative monthly SIF anomalies from 2007 – 2015 and determine the hydro-meteorological variable with the largest corresponding standardized anomaly, which is considered to represent the main driver of the respective vegetation extreme.

We aggregate the results across grid cells of similar climate conditions. By contrasting main controls and their importance on vegetation productivity during extreme and general conditions, we find that water control in arid regions and energy control in humid regions are overall consistent in both conditions, while the importance of deep root-zone soil moisture is significantly increased in arid regions. Then, we identify regions where transitions between water and energy-control occur and further assess to which extent such regime transitions amplify vegetation productivity anomalies and/or impact their recovery.

This study contributes to a better understanding of vegetation productivity extremes, which may change with changing future patterns of temperature and precipitation, with subsequent feedbacks on the climate system and implications on food security.
Woody plant encroachment in southwestern US: Drivers, feedbacks, and conceptual models
Authors: Li Junran (Jimmy) , Ravi Sujith , Wang Guan , Van Pelt Scott , Gill Thomas , Sankey Joel
Published: March 2021

Many grass-dominated ecosystems in dryland regions have experienced increasing woody plant density and abundance during the past century. An example is the Chihuahuan Desert in the southwestern US, which experienced different stages of shrub encroachment in the past 150 years. We synthesize recent developments in the roles and feedbacks of abiotic and biotic drivers of shrub encroachment in the Chihuahuan Desert using an ecosystem dynamics context through intercomparison of Long Term Ecological Research (LTER) sites. Experimental and modeling studies support a conceptual framework which underscores the roles of erosion and fire in woody plant encroachment. Collectively, research at the Jornada LTER provided complementary, quantitative support to the well-known fertile-islands framework. Studies at the Sevilleta LTER expanded the framework, adding fire as a major disturbance to woody plants. Conceptual models derived from the synthesis may guide management interventions aimed at reducing or mitigating undesirable ecosystem state change elsewhere in the world.