bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatio-temporal dynamics of root system architecture of maize in a field trial during a growing season
Authors: Vetterlein Doris , Schreiter Susanne , Lippold Eva , Phalempin Maxime , Blaser Sebastian , Schlüter Steffen
Published: March 2020

A better understanding of how roots explore soil is crucial for plant breeding, yield increase and sustainable agriculture. This requires detailed knowledge about the temporal dynamics of root system architecture under field conditions, which is hard to achieve as sampling of roots with unconstrained growth (no root windows) is very laborious. 
Here we present the results of a major undertaking to sample maize roots in a field experiments at four growth stages in various depths (0-20, 20-40, 40-60 cm) with two different methods: a) destructive sampling with a root corer and root washing vs. b) undisturbed sampling combined with root detection in X-ray CT images. The first method results in root length data with a higher number of technical replicates per depth and plot, whereas the second provides more details of small-scale rooting patterns and plant-soil interactions in intact soil for a smaller number of samples.
The aim of the study was to explore differences in spatio-temporal root growth patterns between two different maize genotypes (wild type vs. root hairless mutant) growing in two different homogenized substrates (sand vs. loam). For disturbed sampling we found that for both genotypes root growth was more vigorous in sand during the entire growing season. This was remarkable since shoot biomass was larger on the loam plot. As drought developed during the growing season, root length density profiles reversed in loam, but not on sandy substrate. For intact cores we find the same trends so that they can now be analyzed towards inter-root distances at shorter scales.
In loam the absence of root hairs and the associated reduction of available surface for water and nutrient uptake resulted in a 50% reduction in shoot biomass, whereas root length profiles did not differ in the root corer data. In sand differences in shoot biomass between genotypes were comparable, but here root length densities were lower for the root hairless mutant in the root corer data. Unexpectedly there was no compensation of lacking root hairs by enhanced root growth. The root length data in intact samples showed higher variation due to smaller sampled volumes which disguised possible trends between genotypes.
In summary, the different hydraulic properties of the substrates had a strong effect on root growth and root distribution with depth, whereas the genotype governed shoot biomass supposedly through differences in nutrient and/or water uptake efficiency mediated by the presence or absence of root hairs. As the next steps, these observations will be underpinned by transpiration and soil moisture monitoring data as well as plant nutrient uptake data.
The Climate Benefit of Carbon Sequestration
Authors: Sierra Carlos , Crow Susan , Heimann Martin , Metzler Holger , Schulze Ernst-Detlef
Published: March 2020

Ecosystems play a fundamental role in climate change mitigation by taking up carbon from the atmosphere and storing it for a period of time in organic matter. Although climate impacts of carbon emissions can be quantified by global warming potentials, there is not a formal metric to assess climate benefits of carbon removals by sinks. We introduce here the Climate Benefit of Sequestration (CBS), a metric that quantifies the radiative effect of taking up carbon dioxide from the atmosphere and retaining it for a period of time in an ecosystem before releasing it back to the atmosphere.  To quantify CBS, we also propose a formal definition of carbon sequestration (CS) as the integral of a sequestered amount of carbon over the time horizon it remains stored in an ecosystem. Both metrics incorporate the separate effects of i) inputs (amount of atmospheric carbon removal), and ii) transit time (time of carbon retention) in carbon sinks, which can vary largely for different ecosystems or management types. In three separate examples, we show how to compare different carbon management practices in forestry and soils using CS and CBS. We believe these metrics can be useful in resolving current controversies about the management of ecosystems for climate change mitigation. 
Geoelectrical monitoring of dissolution and precipitation reactions in a saturated calcareous porous medium
Authors: Rembert Flore , Jougnot Damien , Luquot Linda , Zuddas Pierpaolo , Guérin Roger
Published: March 2020

Precipitation and dissolution are prime processes in carbonate rocks and being able to monitor them is a major deal of reservoir exploitation for geo-resources (water, gas) or geological storage (CO2, H2, waste). Geophysics can be used to monitor these processes non-intrusively and at low cost. Among the existing techniques, we used two electrical methods to monitor the reactivity of a synthetic calcareous porous medium: self-potential (SP) and spectral induced polarization (SIP). SP is a passive technique that consists in measuring the electrical field as it is affected by water fluxes and concentration gradients through electrokinetic and electrochemical couplings. SIP is an active method that provides the electrical conductivity and the chargeability of a porous medium in a low frequency range (mHz to kHz). We carried out a two months laboratory experiment to monitor the geoelectrical signals generated by chemical variations in a synthetic medium composed of pure calcite grains. Three different solutions were injected to alternatively dissolve or precipitate calcite in the sample. The sample is equipped with four aligned non-polarizable Ag/AgCl electrodes in order to geoelectrically monitor the fluid percolation and the ionic concentration gradients changes through the medium. Moreover, we conducted chemical analyses of the downstream fluid to monitor its ionic composition. We made a 1D reactive-transport simulation with the software CrunchFlow to get the concentration gradients of all dissolved ions along the column. Following a theoretical framework, we used a physically based analytical model to relate our electrical signals to ionic concentrations of a multicomponent electrolyte. We find that dissolution and precipitation generate measurable geoelectrical signals because of chemical reactions and ions substitutions. These findings open the possibility to better understand geoelectrical signals in natural media and possibly use them to monitor in situ reactivity.
Sea level in Thule measured with tide gauge, GNSS-IR and Satellite Altimetry
Authors: Dahl-Jensen Trine S. , Khan Shfaqat Abbas , Williams Simon D.P. , Andersen Ole B. , Ludwigsen Carsten A.
Published: March 2020

Recent studies show that under the right conditions relative sea level can be measured using GNSS interferometric reflectometry (GNSS-IR). We test the possibility of using an existing GNET GPS station in Thule, Greenland, to measure inter annual changes in sea level by comparing sea level measurements from GNSS-IR with tide gauge observations and satellite altimetry data. GNET is a network of 56 permanent GPS stations positioned on the bedrock around the edge fo the Greenland ice sheet with the main purpose of monitoring ice mass changes. Currently, Thule is the only location in Greenland where we have both a tide gauge and a GPS station that is suitable for sea level measurement covering the same time period for more than a couple of years. If successful a number of other GPS stations are also expected to be suitable for GNSS-IR measurements of sea level. However, they lack the tide gauge station for testing.
We compare the measured sea level with uplift measured using the GPS and modeled from height changes of the Greenland ice sheet as well as sea surface temperatures and modeled sea level changes from gravimetry, in order to investigate the origin of sea level changes in the region.  
 
An asymptotic approximation of the maximum runup produced by a Tsunami wave train entering an inclined bay with parabolic cross section
Authors: Postacioglu Nazmi , Özeren M. Sinan , Çelik Ebubekir
Published: March 2020

Investigation of the behavior of various types of Tsunami wave trains entering bays is of practical importance for coastal hazard assessments. The linear shallow water equations admit two types of solutions inside an inclined bay with parabolic cross section: Energy transmitting modes and decaying modes. In low frequency limit there is only one mode susceptible of transmitting energy to the inland tip of the bay. The decay rates of decaying modes are controlled by the boundary conditions at the sides of the bay. Therefore a complicated eigenvalue problem needs to be solved in order to compute these decay rates. To determine the amplitude of the energy transmitting mode one should solve an integral equation, involving not just the energy transmitting mode but also decaying modes, the scattered field into the open sea, the incident wave and the reflected wave in the open sea. However, in the long wave limit, all these complications can be avoided if one applies the Dirichlet boundary conditions at the open boundary. That is to take the displacement of the free surface at the open boundary being equal to the twice of the disturbance associated with the incident wave in the open sea, just like a wall boundary condition. The runup produced by the solution obtained from this Dirichlet boundary condition, can be easily calculated using a series of images. In this model no energy is allowed to escape from the bay therefore the error arising from the simplification of the boundary conditions at the open boundary grows with time. Nevertheless the maximum runup occurs before this error becomes significant. If the characteristic wavelength of the incident wave train is equal to 5 times the width of the bay then this simple solution overestimates the first maximum of the runup only by %15 compared to the “exact” solution derived from the integral equation. This overestimation is partly due to the fact that Dirichlet boundary conditions violates the continuity of depth integrated velocities. The solution associated with Dirichlet boundary condition is perturbed in order to match fluxes inside and outside of the bay. This perturbation does not use the decaying modes inside the bay. The height of the first maximum of the runup coming from the perturbation theory is in excellent agreement with that obtained using the integral equation. This perturbation theory can also be applied to narrow bays with arbitrary cross section as long as their depth does not not change in the longitudinal direction.
On the impact of gravitational deformation on VLBI-derived parameters
Authors: Shoushtari Sahar , Glaser Susanne , Balidakis Kyriakos , Heinkelmann Robert , Anderson James , Schuh Harald
Published: March 2020

On the impact of gravitational deformation on VLBI-derived parameters

Sahar Shoushtari1,2, Susanne Glaser1, Kyriakos Balidakis1, Robert Heinkelmann1,2, James M. Anderson1,2, Harald Schuh1,2

(1) GFZ German Research Centre for Geosciences, Section 1.1 Space Geodetic Techniques, Telegrafenberg, 14473 Potsdam, Germany

(2) Technische Universität Berlin, Chair of Satellite Geodesy, Strasse des 17. Juni 135, 10623 Berlin, Germany

Very Long Baseline Interferometry (VLBI) is a highly accurate space geodetic technique that observes extragalactic radio sources to measure the time delay between arrival times of a plane wavefront at two distant radio telescopes. The gravitational deformation of the VLBI telescopes as a function of pointing direction, caused by gravitational forces acting on the massive telescope structures, mainly impacts the estimated station heights and can reach centimeter-level for large antennas. Thus far, this effect has not been considered in operational VLBI data analysis. In the next realization ITRF2020, it is envisaged to model this effect in an effort to reduce the persistent scale discrepancy in ITRF2014 between VLBI and Satellite Laser Ranging. Currently, there are models for only a minority of antennas available, six in total: Effelsberg, Gilcreek, Medicina, Noto, Onsala, and Yebes, which are provided by the International VLBI Service for Geodesy and Astrometry (IVS). In this study, the impact of the gravitational models on station positions, Earth orientation parameters and the network scale is assessed within VLBI data analysis. The standard 24-hours IVS-R1 and -R4 sessions are analyzed using the PORT (Potsdam Open-source Radio Interferometry Tool) software package. First results show that the gravitational models of the six antennas change the station heights by a few mm and the horizontal components by less than 1 mm (in case of Medicina).
End-to-end PGA estimation for earthquake early warning using transformer networks
Authors: Münchmeyer Jannes , Bindi Dino , Leser Ulf , Tilmann Frederik
Published: March 2020

The key task of earthquake early warning is to provide timely and accurate estimates of the ground shaking at target sites. Current approaches use either source or propagation based methods. Source based methods calculate fast estimates of the earthquake source parameters and apply ground motion prediction equations to estimate shaking. They suffer from saturation effects for large events, simplified assumptions and the need for a well known hypocentral location, which usually requires arrivals at multiple stations. Propagation based methods estimate levels of shaking from the shaking at neighboring stations and therefore have short warning times and possibly large blind zones. Both methods only use specific features from the waveform. In contrast, we present a multi-station neural network method to estimate horizontal peak ground acceleration (PGA) anywhere in the target region directly from raw accelerometer waveforms in real time.

The three main components of our model are a convolutional neural network (CNN) for extracting features from the single-station three-component accelerograms, a transformer network for combining features from multiple stations and for transferring them to the target site features and a mixture density network to generate probabilistic PGA estimates. By using a transformer network, our model is able to handle a varying set and number of stations as well as target sites. We train our model end-to-end using recorded waveforms and PGAs. We use data augmentation to enable the model to provide estimations at targets without waveform recordings. Starting with the arrival of a P wave at any station of the network, our model issues real-time predictions at each new sample. The predictions are Gaussian mixtures, giving estimates of both expected value and uncertainties. The model can be used to predict PGA at specific target sites, as well as to generate ground motion maps.

We analyze the model on two strong motion data sets from Japan and Italy in terms of standard deviation and lead times. Through the probabilistic predictions we are able to give lead times for different levels of uncertainty and ground shaking. This allows to control the ratio of missed detections to false alerts. Preliminary analysis suggest that for levels between 1%g and 10%g our model achieves multi-second lead times even for the closest stations at a false-positive rate below 25%. For an example event at 50 km depth, lead times at the closest stations with epicentral distances below 20 km are 6 s and 7.5 s. This suggests that our model is able to effectively use the difference between P and S travel time and accurately assess the future level of ground shaking from the first parts of the P wave. It additionally makes effective use of the information contained in the absence of signal at other stations.
A quantitative comparison of ENSO prediction methods
Authors: Hu Xinjia , Kantz Holger , Faust Eberhard
Published: March 2020

The El Niño Southern Oscillation (ENSO) is one of the most important inter-annual climate phenomena with worldwide impacts. It can influence daily temperature and rainfall, as well as cause extreme weather events and natural disasters. Therefore, early and reliable prediction of the onset and magnitude of ENSO is crucial for different stakeholders. In order to overcome the “spring predictability barrier” in ENSO prediction, recent studies have developed some analysis tools and put forward some forecasting indices based on climate network, claiming they have achieved the long-lead-time (over 6 months) forecasts. However, there are few kinds of research to quantitatively compare the predictive power of these methods. Thus developing a method to measure the quality of these forecasts and compare their predictive power is necessary and meaningful for the improvement of ENSO prediction skills. In these existing researches, in order to set the threshold or estimate the accuracy of the prediction, the standard El Niño indices such as Oceanic Index (ONI), Niño 3.4 Index and etc., are often used to be compared with the invented indices series. In this research, we look into these comparisons and results, and use the receiver operating characteristic curve (ROC) to quantitatively compare these recent analysis tools. Additionally, for demonstrating that the results are not accidental, randomized series obtained by reshuffling the temperature records are analyzed. In this paper, we use the method of surrogate data instead of using shuffle data in the evaluation procedure of the prediction to further improve the evaluation method of the El Nino prediction.

 

(This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 813844.)
Towards global stochastic flood modelling
Authors: Wing Oliver , Quinn Niall , Bates Paul , Neal Jeff , Sampson Chris , Smith Andy
Published: March 2020

Hydraulic modelling at large spatial scales is a field of enquiry approaching a state of maturity, with the flood maps produced beginning to inform wide-area planning decisions, insurance pricing and emergency response. These maps, however, are typically ‘static’; that is, are a spatially homogeneous representation of a given probability flood. Actual floods vary in their extremity across space: if a given location is extreme, you may expect proximal locations to be similarly extreme and distal locations to be decreasingly extreme. Methods to account for this stochastically can, broadly speaking, be split into: (i) continuous simulation via a meteorological-hydrological-hydraulic model cascade and (ii) fitting statistical dependence models to samples of river gauges, generating a synthetic event set of streamflows and simulating the hydraulics from these. The former has the benefit of total spatial coverage, but the drawbacks of high computational cost and the low skill of large-scale hydrological models in simulating absolute river discharge. The latter enables higher-fidelity hydraulics in simulating the extremes only and with more accurately defined boundary conditions, yet it is only possible to execute (ii) in gauge-rich regions – excluding most of the planet.

In this work, we demonstrate that a hybrid approach of (i) & (ii) offers a promising path forward for stochastic flood modelling in gauge-poor areas. Inputting simulated streamflows from large-scale hydrological models to a conditional exceedance model which characterises the spatial dependence of discharge extremes produces a very different set of plausible flood events than when observed flows are used as boundary conditions. Yet, if the relative exceedance probability of simulated flows – internal to the hydrological model – are used in place of their absolute values (i.e. a return period instead of a value in m3s-1), the observation- and model-based dependence models produce similar events in terms of the spatial distribution of return periods. In the context of flood losses, when using Fathom-US CAT (a state-of-the-art large-scale stochastic flood loss model), the risk of an example portfolio is indistinguishable between the gauge- and model-driven framework given the uncertainty in vulnerability alone. This is providing the model-based event return period is matched up with a hydraulic model of the same return period, yet where the latter is characterised via a gauge-based approach.
P-wave velocity anisotropy in an active methane venting pockmark: The Scanner Pockmark, northern North Sea
Authors: Bayrakci Gaye , Minshull Timothy A. , Bull Jonathan M. , Henstock Timothy J. , Provenzano Giuseppe , Birinci Hamza , Macdonald Calum , Dunn Robert
Published: March 2020

Scanner pockmark is an active and continuous methane venting seafloor depression of ~ 900 x 450 m wide and 22 m deep. It is located in the northern North Sea, within the Witch Ground basin where the seafloor and shallow sediments are heavily affected by pockmarks and paleo-pockmarks of various sizes. A seismic chimney structure is present below the Scanner pockmark. It is expressed as a near-vertical column of acoustic blanking below a bright zone of gas-bearing sediments. Seismic chimneys are thought to host connected vertical fractures which may be concentric within the chimney and align parallel to maximum compression outside it. The crack geometry modifies the seismic velocities, and hence, the anisotropy measured inside and outside of the chimney is expected to be different.

 

We carried out anisotropic P-wave tomography with a GI-gun wide-angle dataset recorded by the 25 Ocean Bottom Seismometers (OBSs) of the CHIMNEY experiment (2017). Travel times of more than 60,000 refracted phases propagating within a volume of 4 x 4 x 2 km were inverted for P-wave velocity and the direction and degree of P-wave anisotropy. The grid is centred on the Scanner Pockmark and has a y-axis parallel to -34o N. The horizontal node interval is denser in the zone covered by the OBSs and the vertical node interval is denser near the seabed. A 3 iteration inversion leads to a chi2 misfit value of 1 and a root-mean-square misfit of <10 ms. The results show a maximum P-wave anisotropy of 5%, and higher degrees of anisotropy correlates well with higher velocities. The fast P-wave velocity orientation, a proxy for fracture orientations, is 46o N. The top of the chimney possibly links a bright spot mapped at 270 ms in two way travel time using RMS amplitudes of MCS data, to the surface gas emission. The bright spot corresponds to low tomographic P-wave velocity and anisotropy, suggesting that gas is located in a zone with unaligned fractures or porosity. This observation is in good agreement with early multi-channel seismic data interpretations which suggested that the gas is trapped within a sandy clay layer, the Ling Bank Formation, capped by an upper clay layer, the Coal Pit Formation. In the next step, we will invert the travel-times of reflected phases in order to increase the image resolution.  
Glacier monitoring, capacity building and related cryospheric research in Central Asia
Authors: Hoelzle Martin , Barandun Martina , Saks Tomas , Azisov Erlan , Gafurov Abror , Ghirlanda Alyssa , Kayumov Abdulhamid , Kenzhebaev Ruslan , Kronenberg Marlene , Machguth Horst , Mamirov Halim , Moldobekov Bolot , Petrov Maxim , Salzmann Nadine , Usubaliev Ryskul , Yakovlev Andrey , Zemp Michael
Published: March 2020

Climate change is a major challenge for humanity and the related global implications will influence and threaten future economies and livelihood of coming generations, especially in developing countries. Central Asia is one of the regions mostly vulnerable to climate change considering its hydrological constraints. Tien Shan and Pamir, are among the largest mountain systems of the world, and play a significant role in serving water to the arid and continental region. Future water resources in Central Asia depend strongly on the cryosphere, particularly on snow, glaciers and permafrost. These cryospheric components store enormous amounts of fresh water and under the ongoing climate warming, expected changes will play an important role for future water availability in the region. Recent research clearly points out that a) for current climate conditions, water release by the cryosphere, particularly glaciers, is fundamental to keep runoff sufficient during the dry summer months and b) at the end of this century the water contribution of glaciers will be drastically reduced. Certain catchments are expected to completely dry-out. This setting creates a complex set of future challenges in the domains of water management, energy production, irrigation, agriculture, environment, disaster risk reduction, security and public health and potential political tension and conflicts between the countries cannot be excluded.

Notably, climate change also poses challenges in the field of climate services, as the lack of reliable data and commitment of the governments to fully integrate their observatory systems inhibits the sustainable adaptation and development of the region. At this point, the project CICADA (Cryospheric Climate Services for improved Adaptations) is currently contributing to the improvement of the Cryospheric Climate Services in the Central Asian countries by installing modern monitoring infrastructure, by training local students and researchers and by using the collected in situ measurements in combination with remote sensing and modelling to provide climate scenarios and services for water runoff and natural hazards. This is a prerequisite to allow early planning and adaptation measures within the water resource management and disaster risk reduction sectors.
Introducing the VESBO Project - Impact assessment of vascular plant encroachment on water and carbon cycling in a Sphagnum dominated bog
Authors: Welpelo Carla , Dubbert Maren , Tiemeyer Bärbel , Dettmann Ullrich , Beuster Thomas , Launiainen Samuli , Kieloaho Antti-Jussi , Haahti Kersti , Piayda Arndt
Published: March 2020

Boreal and temperate peatlands cover less than 3% of the earth's surface but store nearly 30% of the terrestrial carbon. Natural raised bogs are characterized by a Sphagnum-moss dominated vegetation cover. The majority of bogs has been used for peat extraction or agriculture for centuries, but in the last decades the focus on restoration to protect climate and biodiversity was increasing. This includes the re-establishment of quasi-natural hydrological conditions as well as of ecosystem-typical vegetation.

Recently, a change in species composition of restored bogs from Sphagnum-dominated bryophyte communities to multi-layered tree and graminoid vegetation was observed. Current investigations report contradictory effects for the impact on throughfall, evapotranspiration (ET), gross primary productivity, respiration, net CO2 balance (NEE) as well as soil carbon sink strength. A final conclusion with respect to altered ecosystem functioning through changing conditions for vegetation development in the light of climate change is missing.

The VESBO project aims at the mechanistic analysis of ET, NEE and soil carbon sink strength of a restored, atlantic-temperate raised bog during vascular plant encroachment. The two study areas are former peat extraction sites, with one being Sphagnum-dominated while the other one has been populated by Betula pubescens during the last years. Focus will be placed on the partitioning of total ecosystem ET and NEE fluxes by Eddy Covariance and chamber measurements in situ into bryophyte, graminoid and tree contributions. Results are used to parameterize a modern soil-vegetation-atmosphere-transport model able to simulate bryophyte and vascular plant layers on peat soil. The model, jointly with the empirical data, is used to quantify seasonal changes in plant functional group flux contributions depending on altered environmental conditions. The holistic process understanding is of high relevance for the NEE estimation of restored bog ecosystems under changing climatic conditions and vegetation compositions. The knowledge about different interactions of plant functional groups with mass and energy fluxes of the bog ecosystem will be valorised by the assessment of restoration and emission mitigation measures throughout Europe.
On seismic clusters, swarms and repeating earthquakes in Central Chile.
Authors: Valenzuela Malebrán Carla , Cesca Simone , Ruiz Sergio , Passarelli Luigi , Leyton Felipe , Dahm Torsten
Published: March 2020

 Along the Chilean subduction segment, the seismicity tends to display characteristics of mainshock-aftershocks sequences. However, besides large and destructive earthquakes, central Chile has been also characterized by the occurrence of localized seismicity clusters with weak to moderate magnitudes, appearing either in form of repeated short-duration swarms or in form of sustained long-lasting activity. Seismic swarms were observed prior to large earthquakes and were hypothesized as possible precursors, although they did not always develop into major earthquakes. The origin and driving processes of this localized seismic activity have not yet been identified. Here, we characterize the seismicity at two seismic clusters in Central Chile, by analyzing hypocentral locations, spatio-temporal migration, magnitude, and inter-event time distributions and moment tensors. Both clusters are characterized by weak to moderate seismicity and manifest as clear seismicity rate and Benioff strain anomalies. We discuss these seismic clusters over a period of 18 years (2000-2017) and investigate their interactions with the Maule earthquake. We find repeating thrust earthquakes on the slab interface at one cluster beneath Vichuquén slipping at a rate comparable to the tectonically accumulated one. At the offshore Navidad cluster, the seismicity occurs in forms of swarms, with the largest episodes in 2001, 2002, 2004, 2012, 2014, 2016 and 2017 showing some rough temporal recurrence. Moment tensor indicates the occurrence of similar thrust mechanisms along a west-dipping structure across the subducting plate. Clusters persist before and after the Maule earthquake. However, at the Vichuquén cluster, the increased seismicity rate following the Maule earthquake remains to date higher than the background rate and the system is still far from recovery.
Structure and function of coupled human—natural systems: from fitting to sustainability
Authors: Wang Shuai
Published: March 2020

Under the intense disturbances of human activities, the global resources and environment are facing unprecedented stresses. Now, because the earth has entered a new era of “anthropocence”, coupling natural and social systems, analyzing the structure and function of the human-land system has become the key to ensuring the sustainability of the earth system. Human-land coupled systems, whose structures are the relationships between internal components and functions are their properties to meet a certain demand, are composed of a natural ecological subsystem and a human social subsystem with their interactions. A human-land coupled system has structural and functional characteristics that are different from social or natural systems’ respectively. While structure determines function, functional feedback structure. “Fit” is a sustainable system structure configuration. Here, we summarized the four main types of “fit” within coupled human-land system. (1) Fit of totality: to the allocation of the total amount of key indicators does not exceed the threshold; (2) Fit of structure: the interaction relationships configuration to sustain good performance of the system; (3) Fit of dynamic: adjusting and optimizing the configuration when new changes or disturbances occurred; (4) Fit of scale: the rational configuration of the structure-function effect relationship between different scales. Coupled human-land systems researches are aiming at the aspects of quantity, order, time, and space to propose ways to regulate and control the structure of the system to achieve sustainable functions, so as to keep fit. In the future, priority can be given to the following three aspects: (1) Developing theories and methods of coupled human-land systems’ structure; (2) Analyzing the changes in the structure of the coupled system and their functional effects; (3) Further identifying and clarifying the approaches to keep fit.
Long term brownification process at the Lammi LTER area in Finland
Authors: Rankinen Katri , Holmberg Maria , Hellsten Seppo , Arvola Lauri , Liukko Ninni , Riihimäki Juha
Published: March 2020

Browning of surface waters due to increased terrestrial loading of organic carbon is observed in boreal regions. It is explained by large scale changes in ecosystems, including decrease in sulphur deposition that affects soil organic matter solubility, increase in temperature that stimulates export of dissolved organic carbon (DOC) from organic soils, and increase in precipitation and thus runoff. Land use changes and forestry measures are also observed to be one reason for increased transport of DOC. The effects of brownification extend to ecosystem services like water purification, but also freshwater productivity through limiting light penetration and creating more stable thermal stratification. The research question at the Lammi LTER area (Southern Boreal Aquatic and Terrestrial Long-Term Ecological Research Area) was brownification of the lake Pääjärvi. We studied both past trends of organic carbon loading from catchments and water colour in the lake based on observations since early 1990’s. We also made simulations of loading for future climate by the physical Persist and INCA models. DOC concentration in the lake was simulated by the physical MyLake model. Simulated DOC concentration was transformed to water colour and light climate of the lake by empirical equations to study the influence on macrophytes (as an indicator of the ecosystem state). In future growing depths might decrease from 2 m to 1.2 m corresponding to observed shift from reference lakes to impacted lakes. Brownification was driven mainly by the change in climate and decay of organic matter in soil, with smaller impact of land use change on organic soil types. Decrease in sulphur deposition had only minor effect on brownification.
Application of a Coupled Atmospheric and Hydrological Modelling System (AHMS) to the Yellow River Basin, China
Authors: Jiang Cong , J. R. Parteli Eric , Shao Yaping
Published: March 2020

The Yellow River Basin (795,000 km2) in Northern China has been greatly affected by intensive human activity and climate change over the past decades. In this study, a coupled atmospheric and hydrological modelling system is applied to investigating the long-term hydrological cycle and short-term forecasting of hydrological events in the Yellow River Basin. This modelling system (AHMS) combines a hydrological model (HMS) with the Weather Research and Forecast model (WRF) and the Noah land surface scheme (NoahMP-LSM), which has been recently improved to account for topographic influences in the infiltration scheme and to allow for interactions between the unsaturated and saturated zones by applying the Darcy-flux boundary condition. Here, simulations are performed using the offline AHMS mode over the Yellow River Basin by considering a time span of 25 years (1979-2003) and a spatial resolution of 20 km. The NCEP reanalysis dataset and observed precipitation data for the referred period are used as meteorological forcing data. The most important parameters affecting the hydrological process are identified by means of a parametric sensitivity analysis. Specifically, these main parameters are the Manning's roughness coefficient of channel, the soil infiltration capacity and the hydraulic conductivity of riverbed. To calibrate the values of these parameters for the Yellow River Basin, model predictions for daily streamflow are compared with the corresponding observational data at four hydrological gauging stations including Tangnaihe (TNH), Lanzhou (LZ), Toudaoguai (TDG) and Huanyuankou (HYK) on the mainstream of the Yellow River. Quantitative agreement is found between these observations and the simulation results for all stations. The progress achieved in the present work paves the way for a sediment flux model over the Yellow River Basin and demonstrates the good performance of AHMS for long-term hydrological simulations. 
Modelling the marine ecosystem of IBI European waters for CMEMS operational applications
Authors: Gutknecht Elodie , Reffray Guillaume , Mignot Alexandre , Dabrowski Tomasz , Sotillo Marcos
Published: March 2020

As part of the Copernicus Marine Environment Monitoring Service (CMEMS), a physical-biogeochemical coupled model system has been developed to monitor and forecast the ocean dynamics and marine ecosystem of the European waters. The model domain, called Iberia-Biscay-Ireland (IBI), covers the North-East Atlantic Ocean from the Canary Islands to Iceland, including the North Sea and the Western Mediterranean. Based on NEMO-PISCES with a horizontal resolution of 1/36°, the CMEMS IBI coupled model has provided 7-day weekly ocean forecasts for CMEMS since April 2018. But prior to its operational launch, a pre-operational qualification simulation (2010-2016) has allowed assessing the model's capacity to reproduce the main biogeochemical and ecosystem features of the IBI area. 
The objective is to evaluate the capacity of the coupled model to reproduce the spatial distribution and seasonal dynamics of the main biogeochemical variables, using this 7-year qualification simulation. The model results are compared with available satellite estimates as well as in situ observations, with a focus on BGC-Argo floats. 
The evaluation confirms that this model system can be a useful tool to better understand the current state and changes in the marine biogeochemistry of European waters and can also provide key variables for developing indicators to monitor the health of marine ecosystems. 
PROSPECT-PRO: a leaf radiative transfer model for estimation of leaf protein content and carbon-based constituents
Authors: Féret Jean-Baptiste , Berger Katja , de Boissieu Florian , Malenovský Zbyněk
Published: March 2020

Leaf nitrogen content is key information for ecological and agronomic processes. A number of studies aiming at estimation of leaf nitrogen content used chlorophyll content as a proxy due to a moderate to strong correlation between chlorophyll and nitrogen content during vegetative growth stages. Since leaf nitrogen content is directly linked to leaf protein content, the capacity to accurately estimate leaf protein content may improve robustness of an operational nitrogen monitoring. In the past, the introduction of proteins - as an absorbing input constituent of the PROSPECT leaf model - has been attempted numerous times. Yet, the attempts suffered from a certain number of shortcomings, including limited applicability to both fresh and dry vegetation, inaccurate definition of the specific absorption coefficients, or incomplete accounting for different constituents of leaf dry matter.

Here, we introduce PROSPECT-PRO, a new version of the PROSPECT model simulating leaf optical properties based on their biochemical properties and including protein and carbon-based constituents (CBC) as new input variables. These two additional chemical constituents correspond to two complementary constituents of LMA. Specific absorption coefficients for proteins and CBC were produced splitting LOPEX dataset into 50% for calibration and 50%for validation. Both data sets included fresh and dry samples. Our objective is to keep compatibility between PROSPECT-PRO and PROSPECT-D, the previous version of the model, and to ensure the same performances for the estimation of LMA even through its decomposition into two constituents. Therefore, the full validation consisted of two steps:

1) PROSPECT-PRO inversion using an iterative optimization approach to retrieve proteins and CBC from LOPEX data

2) Testing the compatibility with PROSPECT-D by estimating LMA as the sum of protein and CBC content from independent datasets

The capacity of PROSPECT-PRO for the accurate estimation of leaf proteins and CBC on LOPEX could be evidenced, with slightly higher performances for the estimation of fresh leaf proteins (NRMSE = 17.3%, R2 = 0.75) than of dry leaf proteins (NRMSE =24.0%, R2 = 0.62). Good overall performances were obtained for the estimation of CBC (NRMSE<15%, R2>0.90). Based on these results, the carbon/nitrogen ratio of leaves could be modelled accurately.

The indirect estimation of LMA through PROSPECT-PRO inversion led to similar or slightly improved results when compared to the estimation of LMA with PROSPECT-D. Hence, PROSPECT-PRO might be of particular interest for precision agriculture applications in the context of nitrogen sensing using observations of current and forthcoming satellite imaging spectroscopy missions.
Crustal and Upper Mantle Deformation Beneath Northwestern part of North Anatolian Fault Zone from Harmonic Decomposition of Receiver Functions
Authors: Keleş Derya , Eken Tuna , Licciardi Andrea , Taymaz Tuncay
Published: March 2020

A proper understanding of crustal seismic anisotropy beneath the tectonically complex northwestern part of the North Anatolian Fault Zone (NAFZ) will shed light into the depth extent of deformation zones. To investigate the seismic anisotropy in the crustal part of the NAFZ, we applied the harmonic decomposition technique on receiver functions from teleseismic earthquakes (with epicentral distances between 30° and 90°) recorded at the Dense Array for North Anatolia (DANA) seismic network. Harmonic coefficients, k=0, k=1, and k=2 were obtained by applying the harmonic decomposition method to the depth migrated receiver functions. Results from k=0 harmonics suggest south to north (e.g. from Sakarya Zone to Istanbul Zone) increase in crustal thickness. The depth variations of energy associated with k=1 and k=2 harmonic components imply significant lateral variation. For instance, the energy calculated for k=1 harmonics in the north (Istanbul Zone) indicates that seismic anisotropy is likely concentrated in the upper crust (within the first 15 km). However, further south, the signature of anisotropy in Armutlu-Almacik and Sakarya Zones becomes more significant in close proximity to the fault zone and dominates at greater (15-30 km and 30-60 km). Furthermore, k=2 harmonic energy maps exhibit relatively high intensities nearby the fault for all depth ranges.
The fate of volcanic ash aggregates: premature or delayed sedimentation?
Authors: Rossi Eduardo , Beckett Frances , Bonadonna Costanza , Bagheri Gholamhossein
Published: March 2020

Most volcanic ash produced during explosive volcanic eruptions sediments as aggregates of various types that typically have a greater fall velocity than the particles of which they are composed. As a result, aggregation processes are commonly known to affect the sedimentation of fine ash by considerably reducing its residence time in the atmosphere. Nonetheless, speculations also exist in the literature that aggregation does not always result in a premature sedimentation of their constitute particles but that it can also result in a delayed sedimentation (i.e. the so-called rafting effect). However, previous studies have considered rafting as a highly improbable phenomenon due to a biased representation of aggregate shapes.

Here we provide the first theoretical evidence that rafting may not only occur, but it is probably more common than previously thought, helping to elucidate often unexplained field observations. Starting from field evidence of rafted aggregates at Sakurajima Volcano (Japan), we clarify the conditions for which aggregation of volcanic ash results either in a premature or a delayed sedimentation.

Moreover, using the Lagrangian dispersion model NAME, we show the practical consequences of rafting on the final sedimentation distance of aggregates with different morphological features. As an application we chose the case study of the 2010 eruption of Eyjafjallajökull volcano (Iceland), for which rafting can increase the travel distances of ash <500 m up 3.7 times with respect to sedimentation of individual particles.

These findings have fundamental implications both for real-time forecasting and long-term hazard assessment of volcanic ash dispersal and sedimentation and for weather modelling. The constraints on rafting presented and discussed in this work will help the scientific community to clarify the often unexpected role of aggregation in creating a delayed sedimentation of coarse ash.
New insights into the kinematics and timing of superimposed rifting events through integration of offshore data, onshore fieldwork and U-Pb geochronology: Inner Moray Firth Basin, Scotland
Authors: Tamas Alexandra , Holdsworth Robert , Underhill John , McCaffrey Kenneth , Dempsey Eddie , Selby David , McCarthy Dave
Published: March 2020

Keywords: inherited structures, fault reactivation, U-Pb geochronology

The E-W striking Inner Moray Firth Basin (IMFB) lies in the western part of the North Sea trilete rift system formed mainly in the Upper Jurassic. The IMFB has experienced a long history of superimposed rifting with plenty of uplift and fault reactivation during Cenozoic. The basin is overlying the Caledonian basement, the pre-existing Devonian-Carboniferous (Orcadian Basin) and a regionally developed Permo-Triassic basin. The potential influence of older structures related to the Orcadian Basin on the kinematics of later basin opening has received little attention, partly due to the poor resolution of seismic reflection data at depth or sparse well data.

By integrating onshore fieldwork with the interpretation of 2D and 3D seismic data and U-Pb geochronology of syndeformationally grown calcite we provide new insights into the kinematic opening of the basin as well as the role of pre-existing Devonian-Carboniferous (Orcadian) basin structures.

The Jurassic opening of the rift basin is known to be associated with major NE-SW trending faults. New detailed mapping of offshore 3D seismic data revealed that at a smaller scale en-echelon E-W to NE-SW trending faults, en-echelon N-S to NNE-SSW and NW-SE fault arrays coexist. This suggests an oblique-sinistral component associated with the major NE-SW rift basin trends. This correlates with onshore findings, which suggest that the inherited Orcadian fault systems (mainly N-S to NE-SW) have been dextrally reactivated. Sinistral WNW-SSE to NW-SE striking faults and associated transtensional folds are also present in the Devonian rocks. This later deformation is consistently associated with calcite mineralization (e.g. slickenfibers, calcite tensile veins or Riedel shear fractures). New U-Pb dating of the calcite mineralization, related to the reactivated faults, shows that the age of fault reactivation is 153 ± 0.68 Ma (Upper Jurassic).

The integration of fieldwork with subsurface interpretations and absolute dating techniques has provided better constraints on superimposed basin development, as well as explaining complexities that have hitherto been ignored. This can reduce subsurface uncertainties regarding the structural evolution of the basin and unlock the full potential of the area and significantly enhance future exploration programs.