bluuebunny/crossref_metadata_2025 huggingface dataset:
The fate of urease inhibitors in two agricultural soils
Authors: Schmalhorst Sophia , Kühn Sandra , Kaupenjohann Martin , Klitzke Sondra
Published: February 2023

Urease inhibitors (UI) are organic trace substances, which are applied along with urea fertilizers to reduce NH3 emissions from agricultural fields. Due to the recent amendment to the German fertilizer act (DüngG) which now dictates the use of UI, increasing amounts of these substances will be applied to arable soils.  So far, little is known about the fate of UI in soils and there is only few data on the leaching of UI from soil to groundwater, especially with respect to field data. However, first studies have proven traces of UI in surface and ground waters, raising concern among drinking water suppliers. Therefore, the aim of this study was to investigate the fate of two different UI, i.e. N-(2-Nitrophenyl) phosphoric acid triamide (2-NPT) and N-(n-Butyl)thio-phosphoric triamide (NBPT) in two agricultural soils, addressing the following questions:How long do UI remain in the topsoil following application?
Which portion will be translocated to deeper soil layers?
 On two agriculturally used fields in the state of Brandenburg (Germany) with sandy soils, which differ in their topsoil total carbon concentration (Berge 0.96 %, Ribbeck 1.39 %) and pH (Berge 5.9, Ribbeck 7.6), 2-NPT (as urea prills) and NBPT (as a mixture with urea solution) were applied along with urea. Soil samples were taken from the topsoil at 0-5 cm depth (using a soil sampling ring with a volume of 100 cm³) and from 5-15 cm and 15-30 cm depth (using a Pürckhauer sampler) of 4 different plots each prior to the application of the substances. Afterwards, samples from the topsoil were taken 1, 3, 6, 8, 10, 12, 14 and 21 days following the application. On the last day of the sampling period, samples from 5-15 cm and 15-30 cm depth were taken in addition. Samples were stored at -18°C until analysis.Based on recovery tests by spiking the study soils with UI, the field-moist samples (sieved to 2 mm) were extracted according to the following procedure: 20 ml extraction solution (50 Vol.-% Acetonitrile/50 Vol.-% H20 for 2-NPT and 0.1 M KCl for NBPT) were added to 10 g soil, then shaken on a horizontal shaker (30 min, 120 rpm). After centrifugation (30 min, 3830 g), the supernatant was filtered through cellulose acetate filters (0.45 µm) and transferred to vials. The extracts were adjusted to neutral pH using dilute NaOH solution and stored in the refrigerator until measurement by HPLC-MS.The concentration on 1 day of 2-NPT in the Berge topsoil amounted to 353 ± 151 µg/kg and in the Ribbeck topsoil 302 ± 148 µg/kg. NBPT was not found in any of the two soils. Whilst 2-NPT was no longer detectable in the Ribbeck topsoil after 10 days, 2-NPT decreased much slower in the Berge topsoil, reaching concentrations of 15.4 ± 15.7 µg/kg after 21 days. None of the inhibitors could be detected in deeper soil layers. Results will be discussed in the context of the site-specific soil parameters and the local precipitation data.
Seismic monitoring of laboratory fault reactivation by pore fluid injection
Authors: Veltmeijer Aukje , Naderloo Milad , Barnhoorn Auke
Published: February 2023

Rising demand for energy and green energy has led to increasing subsurface activities, such as geothermal energy sites. These increasing human activities in the subsurface have caused substantial induced earthquakes in more densely populated areas, increasing the risks of operating safely. Well-known examples of induced seismicity, due to geothermal sites, are the M5.4 earthquake in Pohang (South Korea) or the M3.4 earthquake in Basel (Switzerland).  Monitoring and forecasting earthquakes have been a topic of interest for years. Predictions are often made by production scenarios, probabilistic models, or average earthquake size distribution (b-value). Only a few studies focus on predicting fluid-induced seismicity by using seismic monitoring methods. Pore fluid changes play an important role in the reactivation of the fault strength and stability. Variations in pore pressure can cause a drop in the stresses along the fault plane and cause fault instability and movement resulting in induced seismicity.  Monitoring and predicting the stress changes along the fault planes can therefore be essential in forecasting induced seismicity and mitigation, potentially reducing the risks of operating (in denser populated areas). However, monitoring the degree of these changes remains challenging. Most studies using seismic methods to monitor induced seismicity on a field scale or laboratory scale focus on either passive monitoring or active monitoring. This study combines the two methods and shows how they complement each other in monitoring and mitigation of fault reactivation in the laboratory. We have performed pore fluid injection experiments on faulted sandstones to reactivate the faults while monitoring both actively (active seismic) and passively (acoustic emission).These results show that both acoustic monitoring techniques can be used to detect the different fault reactivation stages: linear strain build-up, early creep (pre-slip), stress drop (main slip), and continuous sliding phase. However, using active monitoring the early creep phase is detected slightly earlier than using passive monitoring. Combining the methods shows that the stress changes along the fault can be detected with more detail in more accuracy. As a result, the combination of passive and active techniques may be useful for monitoring faulted or critically stressed reservoirs that experience pore pressure changes.
How to make a sustainable development approach successful across all scales of a research institute? Crossed views at INRAE
Authors: Gauthier Leslie , Vidal Jean-Philippe , Carnet Armelle
Published: February 2023

This communication aims at presenting how transitions are being made at different organizational scales at INRAE (French National Research Institute for Agriculture, Food and Environment): (1) at the scale of a research lab through the perspective of a sustainable development contact person, (2) at the scale of a regional research centre through the perspective of the sustainable development regional manager, and (3) at the national and institutional level with the view of the sustainable development director of INRAE. The overall institutional context is first introduced to further develop viewpoints of the three persons involved on the on-going transitions, the strengths of the implemented approach, but also the points of attention. This communication aims at triggering exchanges on how to make sustainable development reach all organizational levels while ensuring a global coherence, and notably across all professions including administration staff, scientists, engineers, etc.
Reducing environmental impact at NERSC (Bergen, Norway).
Authors: Brajard Julien , Sivertsen Christine Due
Published: February 2023

NERSC is a non-profit research foundation established in Bergen (Norway) in 1986. Besides cutting-edge research in climate science, the NERSC has for a long time been very attentive to the working conditions, diversity, inclusion, and environmental impact of its activities.In this poster, we will present the different efforts taken at the NERSC initiative to take the path of reducing its environmental impact, especially the GHG footprint, of its activities. We have divided the analysis into big compartments including the travels, the numerical computations, the field campaigns, and the premises. For each compartment, we are in the process to assess the GHG emissions, and some actions have already been taken to already minimize the impacts, for example, a travel policy, and opportunity campaigns.In addition to the details of the work done by NERSC for reducing GHG emissions, we will reflect on challenges and problems encountered while taking those actions, some being general to the scientific or geoscience field (e.g., travel injunction), others being specific to NERSC (fundings, geographic location, low-carbon electricity).Finally, we will draw perspective to the experience, and try to bring recommendations into the debate, such as a better inclusion of climate impact in the European research calls.
Drainage Divide Migration in Steady-State Landscapes Experiencing Horizontal Tectonic Advection
Authors: Hoskins Anthony , Attal Mikael , Mudd Simon , Castillo Miguel
Published: February 2023

Any tectonic forcing acting on a mountain range consists of vertical uplift motion and horizontal advection motion. In landscapes with a high advective component, such as those affected by low angle normal faults, advection can form a substantial portion of the total tectonic forcing. Questions therefore remain relating to the role of advection in shaping mountain range topography, surface drainage patterns and erosion rate distributions. We ask, how does advection influence mountain range topography and drainage? How do drainage basins and divides respond to advection? And how does advection influence the spatial distribution of erosion rates? Through numerical modelling with the Channel-Hillslope Integrated Landscape Development (CHILD) model and comparison to a natural landscape, the Sierra de la Laguna (Mexico), we test the extent to which advection affects mountain range evolution. Advection is shown to alter surface drainage patterns by promoting catchment elongation and reducing outlet spacing at the mountain front. The mountain range’s Main Drainage Divide (MDD) exhibits faster erosion on the distal flank’s headwaters; relative to the proximal flank’s headwaters, leading to a migration of the MDD towards the fault. Steady-state is achieved when the MDD migrates towards the fault at a rate equal to the rate at which the footwall is advected away from the fault. This pattern of erosion rates is found across all spatially fixed geomorphic features. Cosmogenic radionuclide analysis for catchment-averaged erosion rates in the Sierra de la Laguna demonstrates a difference in erosion rates across the MDD that is also indicative of a migration of the MDD towards the fault. Topographic, drainage and erosion rate observations for the Sierra de la Laguna are consistent with the numerical modelling when advection is included, suggesting that advection induces continual drainage migration whilst maintaining mountain range flank widths. We suggest that highly elongate catchments are indicative of substantial advection, and we also identify a mechanism through which divide migration can occur without altering the size of adjacent drainage basins.   
Oroclinal arcs of the Variscan Belt: features and mechanisms
Authors: Martínez Catalán José R. , Schulmann Karel , Ayarza Puy , Edel Jean-Bernard
Published: February 2023

Arcuate trace of large structures characterizes many mountain chains. The Variscan Belt is not an exception, and depicts one of the tightest oroclines in the world, the Ibero-Armorican Arc. In addition, the belt features a few more open arcs in the Eastern Moroccan Meseta, Central Iberia, the French Massif Central and the Bohemian Massif. All Variscan arcs are considered oroclines or secondary oroclines according to definitions by Weil and Sussman (2004) and Johnston et al. (2013) respectively. They are also essentially late orogenic features, but their timing and deformation mechanisms differ. Models explaining their origin have been proposed for some individual arcs, and are generally controversial.This contribution aims at interpreting the ensemble of Variscan arcs paying attention to their age relative to previous orogenic features as well as to those associated with arc development. Such features include first order structures, metamorphism and plutonism, as well as magnetic and gravimetric anomalies. Development of the arcs is viewed as somehow related with late Variscan dextral transpression provoked by the relative displacement of Laurussia to the East relatively to Gondwana during the Pennsylvanian and early Permian (325-290 Ma; Arthaud and Matte, 1977; Shelley and Bossière, 2000; Martínez Catalán et al., 2021). But several mechanisms operated to form the arcs, the most important of them being ductile transcurrent shearing, indentation and shortening perpendicular and parallel to the orogenic trend. These mechanisms acted at different time intervals and their participation or relative importance varies for each arc, as well as their involvement in the development of the structural, metamorphic and igneous features and in the geophysical characteristics.REFERENCES:Arthaud, F. and Matte, P. 1977. Late Paleozoic strike-slip faulting in southern Europe and northern Africa: result of a right-lateral shear zone between the Appalachians and the Urals. Geological Society of America Bulletin, 88, 1305-1320.Johnston, S.T., Weil, A.B. and Gutiérrez-Alonso, G. 2013. Oroclines: Thick and thin. Geological Society of America Bulletin, 125 (5-6), 643-663.Martínez Catalán, J.R., Schulmann, K. and Ghienne, J.F. 2021. The Mid-Variscan Allochthon: Keys from correlation, partial retrodeformation and plate-tectonic reconstruction to unlock the geometry of a non-cylindrical belt. Earth-Science Reviews, 220, 103700, 1-65.Shelley, D. and Bossière, G. 2000. A new model for the Hercynian Orogen of Gondwanan France and Iberia. Journal of Structural Geology, 22 (6), 757-776.Acknowledgement: Spanish Ministry of Science and Innovation, project PID2020-117332GB-C21.
Testing the CO2M NO2 Retrieval Algorithm using TROPOMI Spatial Zoom Data
Authors: Leune Benjamin , Veefkind Pepijn , Trees Victor , van Geffen Jos , Lang Ruediger
Published: February 2023

The future Copernicus Anthropogenic CO2 Monitoring Mission (CO2M) will provide CO2 data at a high resolution of 2x2 km2 with unprecedented accuracy and precision. In addition to bands in the near-infrared and shortwave infrared, the CO2I spectrometer on board of CO2M also contains a visible band for the retrieval of NO2 tropospheric columns. NO2 observations will be performed to aid the detection and identification of CO2 emission plumes, as NO2 is co-emitted during combustion processes and acts as a tracer of CO2. Due to its relatively low tropospheric background value and biospheric influence, local enhancements of tropospheric NO2 are better detectable than those of CO2 and allow for more accurate CO2 emission estimates. Furthermore, this NO2 product will be very valuable for air quality applications, especially emission source quantification.To fully exploit the high resolution of the NO2 measurements, five times higher than the operational resolution of the TROPOMI instrument onboard Sentinel 5P, improvements on multiple aspects of the air-mass correction in the tropospheric NO2 retrieval algorithm are considered: (1) anisotropic surface treatment at high spatial resolution using MODIS-like products, (2) effective cloud/aerosol parameter retrieval as a scattering layer using co-registered cloud information provided by the on-board cloud imager instrument (CLIM) and the measured O2-O2 and O2-A absorption bands and (3) high resolution NO2 a-priori profiles from the CAMS global/regional model forecasts.The TROPOMI instrument produced a limited data set during the commissioning phase, where measurements were performed with increased spatial sampling of 2.4x1.8 km2. This data set captures typical scenes showing NO2 emission plumes at a similar spatial resolution as the planned CO2M measurements, allowing for the CO2M NO2 retrieval algorithm to be tested on real data. These TROPOMI zoom data are processed with the new prototype algorithm for CO2M and impacts of the improvements are quantified.
Integrating expert knowledge in Digital Soil mapping
Authors: Poggio Laura , Rossiter David , Kempen Bas , Genova Giulio , Batjes Niels , Heuvelink Gerard
Published: February 2023

The commonly-used scorpan approach to Digital Soil Mapping is purely correlative, between observations at points and the values of  covariates at those points.  An-often-used approach is of maximum complexity: different quality observations are thrown together with the largest possible number of covariates, along with the most complex model (e.g., ensembles of many models). The resulting products are almost always evaluated with point-wise metrics with sometimes not large differences or improvement between models. Spatial patterns are rarely compared with soil geography. Further work should be done to include more the local and spatial structure component, the ‘n = neighbourhood’ of scorpan. This work addresses how pedological knowledge could be included and the potential advantages and disadvantages of doing so.  
High resolution Large Eddy Simulations of the convective boundary layer over idealized land surface heterogeneities
Authors: Koerner Benjamin
Published: February 2023

Absorption, transformation and release of incoming solar radiation as turbulent heat into the atmosphere is critical for earth's energy balance. However, there is a lack of knowledge of the governing factors of the associated turbulent fluxes. Especially the influence of land surface heterogeneities is uncertain, as often only one-dimensional measurements are available. Finding an interrelation of the surrounding terrain to the turbulent fluxes is therefore not possible. This might be the explanation for why measured fluxes often cannot be reproduced with common calculation methods.Thus, the objective of our study is to investigate the impact of surface heterogeneities on turbulent surface fluxes by performing idealized Large Eddy Simulations of a convective boundary layer over heterogeneous land surfaces under varying conditions. The simulations are run with the Parallelized Large-Eddy Simulation Model (PALM), covering a 10 km x 10 km domain with cyclic boundary conditions. The horizontal resolution is 5 m, the vertical resolution is 2 m near the surface and is increasing with height. The simulation period is one day. The scenarios differ in initial wind profiles, radiation, soil moisture and the type of surface heterogeneities. Output variables are averaged over 5 minutes.By means of these highly resolved simulations, an encompassing three-dimensional analysis of the turbulent surface fluxes and their governing factors could be carried out, enabling the development of improved methods for calculating turbulent fluxes.
Did Earth surface processes promote stabilization of the central Indian Bundelkhand craton?
Authors: Colleps Cody , McKenzie N. Ryan , Chen Wei , Sharma Mukund
Published: February 2023

The impact that ancient Earth surface processes had on long-term thermal regimes remain uncertain despite their potentially important role in fostering craton stabilization and preservation. The distribution and redistribution of heat producing elements (HPEs) during craton development plays a major role in lithospheric cooling and strengthening. Whereas the redistribution of HPEs via erosion has theoretically been suggested to alter the long-term geotherm and contribute to Moho cooling, direct temporal constraints from the field are lacking to adequately assess the role that ancient Earth surface processes may have had on long-term thermal regimes. Here, we used apatite U-Pb thermochronology to assess the thermal evolution of the Archean Bundelkhand craton of central India immediately following its amalgamation and final phase of silicic magmatism at ~2.5 Ga. Apatite from both ~3.4 Ga granitic gneisses and ~2.5 Ga granitoids collected across the ~250 km-wide craton yielded near-uniform apatite U-Pb dates between ~2.4–2.3 Ga, indicating that the craton was broadly exhumed through mid-crustal depths shortly following shallow granitoid emplacement. Unroofing of the craton at this time is further corroborated by the presence of a distinct ~2.5 Ga detrital zircon U-Pb age peak obtained from ~2.2–2.3 Ga sandstones in direct non-conformable contact with Bundelkhand granitoids. We speculate that a two-step redistribution of HPEs largely contributed to the stabilization of the Bundelkhand craton. First, the concentration of HPEs within shallowly emplaced granitoids at ~2.5 Ga reduced the heat production of the lower-most crust. Second, post-emplacement exhumation of HPE-enriched Bundelkhand granitoids further modified the heat source distribution to a thermal regime that promoted cooling of the lower-crust. Although the mechanism driving exhumation through mid-crustal depths remains uncertain, temporal relationships from the Bundelkhand craton suggest that erosional processes may have had a significant role in promoting the craton’s stability and longevity.
A climatology of trapped lee waves over Britain and Ireland, derived using machine learning
Authors: Coney Jonathan , Ross Andrew , Denby Leif , Wang He , Vosper Simon , van Niekerk Annelize , Dunstan Tom
Published: February 2023

Trapped lee waves and turbulent rotor activity are a hazard for aviation, so forecasters must take into account the likelihood of lee wave activity when advising aviation personnel. The UK Met Office’s operational high resolution Numerical Weather Prediction model, UKV, resolves lee wave activity but there is currently no automated operational way to recognise such regions directly from the high resolution UKV data, short of a forecaster looking at the data themselves. If lee waves can be detected from the UKV data, we can use this output to gain a better understanding of lee waves and their impact over Britain and Ireland. For example, over which regions are lee waves likely to form? Which atmospheric conditions are the most conducive to lee wave propagation? 

A machine learning (ML) model, a U-Net, was trained to identify and segment lee waves, and then retrained to derive characteristics about the waves (orientation, wavelength) from the model data. The wave amplitudes are also extracted using the wave mask from the segmentation model. These ML models were then applied to a 30 year dataset (1982 – 2012) of high resolution NWP output, driven by ERA-Interim data. From this, the location and characteristics of lee waves over Britain and Ireland from within this time period were extracted. In this presentation, we explore the climatology of lee waves in the data over this period, including the relationship between waves and the orography; frequency of waves; seasonal effects; the effects of weather patterns on waves; and diurnal effects. 
Enhancing coastal wave forecasts by improving forcings with deep learning – The Copernicus Marine Service Evolution KAILANI project
Authors: García-León Manuel , Aouf Lotfi , García-Valdecasas Javier , Toledano Lozano Cristina , Dalphinet Alice , García-Valdecasas José María , Terrés Nícoli José María , Aznar Roland , López Collantes José Manuel , G. Sotillo Marcos
Published: February 2023

Ocean wave forecasting is highly demanded by end-users. There is a pressing need for reliable forecasts, to be applied in emergency services, harbour logistics, search-and-rescue operations, renewable energy or pollutant transport. In addition to this wide variety of uses, the coastal zone represents a modelling challenge due to the joint superposition of physical processes that make it a highly dynamic environment (including wind, waves, circulation and air-sea-land interactions).In the observational side, remote sensing products such as those derived from Satellite Synthetic Aperture Radar (SAR, e.g. from the Sentinel missions) and High Frequency Radar (HFR, e.g. available at the Copernicus Marine Service - In Situ TAC) offers vast quantities of high-resolution spatio-temporal fields. However, their applicability within the operational ocean forecasts services is not straightforward.The Copernicus Marine Service Evolution KAILANI project (2022 - 2024) aims to enhance the Copernicus Marine regional wave forecasts by improving the forcings required by spectral wave models: i.e. wind forcings and surface current fields. This enhancement comes from blending remote sensing observations with wind and surface currents forecasts. Artificial Intelligence Neural Networks (ANNs) has been proposed as the basis for this blending, as they allow to extract complex spatio-temporal features from remote-sensing data.The impact on bias and error reduction would be assessed by testing these blended fields under a preoperational environment. The Iberia-Biscay-Ireland (IBI) area has been selected for this Proof of Concept, due to the good coverage of HFR along its coastline. Selection of pilot study sites in areas at the Cantabrian Sea (macrotidal), the Canary Islands (mesotidal), the NW Mediterranean (microtidal), and in the hot spot that is the Gibraltar Strait will ensure that KAILANI applicability ranges different environments.This methodology focuses on the post-processing of the forcings. Then, it could be a complement for Data Assimilation algorithms. If successful, the proposed KAILANI methodology could be exportable to different Copernicus Marine Monitoring and Forecasting Centers (MFCs); without significant changes in their numerical codes and operation chain. Finally, the expected enhancement of the delivered coastal wave spectra and their integrated parameters (i.e. wave height, period and direction) will be key to foster downstream nearshore applications.
Identification of fog Particle Size Distributions by inverting the radiative transfer equation
Authors: Krayem Ali , Bernardin Fréderic , Munch Arnaud
Published: February 2023

            Degraded meteorological conditions, including fog, limit the performance of optical sensors used in various fields of application (avionics, intelligent road vehicles, etc.). Cerema, the French research and expertise center under the supervision of the Ecological Transition Ministry, conducts evaluations of these sensors under artificial and controlled fog conditions in the dedicated PAVIN Fog&Rain platform.  In order to perform a digital twin of the platform, it is necessary to develop robust modeling of the propagation of electromagnetic waves in fog. Propagation is governed by the phenomena of scattering and absorption of photons in contact with fog droplets. The fog Droplet Size Distribution (DSD) is a key parameter of the propagation models.In the present work, we investigate the DSD identification from spectral radiation measurements by inverting the stationary radiative transfer equation (RTE). This distribution together with Lorenz-Mie scattering theory allow to compute the optical properties (scattering coefficient, absorption coefficient, and phase function). First, we prove the well-posedness of the underlying inverse problem, then we perform some numerical experiments using synthetic data. The numerical results suggest that the method allows to identify the DSD.We present some numerical results obtained by using various models describingthe particle size distribution (e.g. Shettle and Fenn models) and some experimental distribution measured in the Cerema platform. Afterwards, the identification of the DSDs is carried out using the radiative transfer equation with the collision term (multiple scattering) and by performing direct scattering and backscattering measurements. The robustness of the reconstruction was studied numerically by introducing several noise levels to the measurements.  
The Effects of Soil Texture on Transpiration Losses During Droughts: A Field Study of Three Oak Forests in an Inner Alpine Valley of Switzerland
Authors: Schoch Julian , Walthert Lorenz , Lehmann Peter , Unverricht Pascal , Carminati Andrea
Published: February 2023

As safety mechanism during droughts, plants close their stomata to reduce transpiration losses and prevent excessively negative water potentials. Although the coordination between stomatal closure, xylem vulnerability and leaf traits has been extensively investigated, the role of soil hydraulic limitation remains elusive. Here, we test the hypothesis that stomatal closure is triggered by the loss of soil hydraulic conductivity in the root zone. As the soil hydraulic conductivity is a function of soil texture, we further hypothesize that stomatal closure, and more precisely the relation between stomatal conductance and leaf water potential, are soil texture dependent. An alternative hypothesis is that the shoot to root ratio adapts to the specific soil conditions, and it is lower in soils with low hydraulic conductivity. We compared three field sites in an inner alpine valley in Switzerland (yearly rainfall of 600 mm) with the same oak tree species (Quercus pubescens) and varying soil textures. We used the model of Carminati and Javaux (2020), which predicts that the decline in transpiration rate is controlled by the soil hydraulic conductivity, and, consequently, it is more abrupt in 1) coarse textured soils compared to fine textured soils and 2) in plants with high shoot to root ratio.To test these working hypotheses, stem water status and soil matric potential were measured at various depths of three oak sites. The soil matric potentials were then linked to the hydraulic conductivity and soil water content using a new pedotransfer function (PTF) for forest soils, which overcomes the limits of existing PTFs that were trained for arable soils. A simple water balance model based on changes in water content (deduced from PTF and measured potentials) was used to calculate transpiration rates and was compared with sap flow measurements conducted on two trees per site. Leaf water potentials were estimated from dendrometers after calibration with pressure chamber measurements of leaves. The sap flow measurements correlate well with estimated transpiration rates (R2=0.7).Comparisons between sites show a similar decrease in stomatal conductance at all three sites during drought, regardless of soil texture. Rather, our data suggest the trees hydraulically adapt to the local soil texture by adjusting their leaf area index and root length density to the local water demand and supply. In coarse-textured soils, oak had a low leaf area index, reducing their water demand, and high fine root length density, increasing their supply. In conclusion, our study suggests a hydraulic adaptation of trees to their local soil texture by adapting their “shoot to root ratio” as quantified here by leaf area index and root density.
Inferring deep soil moisture variations in Central Europe using seismic method
Authors: Lu Yang , Wang Qing-Yu , Bokelmann Götz
Published: February 2023

Soil moisture is a key metric to assess soil health. Water held in the shallow subsurface between soil particles enables various biogeochemical and hydrological processes indispensable to soil functions. Potential soil moisture deficit may raise the irrigation demands, which further exacerbates the stress on the water supply. The changes in soil moisture can impact climate, further amplifying the climatic anomalies and intensifying extreme weather events. Thus, understanding soil moisture and its dynamics over time are of broad scientifical interest and practical implications.
Despite the vital importance of soil moisture, it still lacks sufficient means to properly assess the parameter at a regional scale, which is an essential research dimension for addressing practical issues in the agricultural and environmental sectors.
Ambient noise seismology provides new possibilities to infer subsurface changes in a real-time, non-intrusive, and costless manner. In this study, we map the temporal variations in soil moisture for the great Alpine region and the Italy peninsular with ambient seismic noise. It is the first time that the seismic method has been applied to map water resources at a regional scale using an ordinary seismic network setup. The seismic method helps in bridging the resolution gap between current pointwise (e.g., tensio-, electrical- and neutron-meter) and global (e.g., satellite-based remote sensing) investigations, providing complementary information for both scientific research and public decision-making.
The Role of Moisture and Heat Transport for Extreme Droughts in the Amazon Basin - a Lagrangian Perspective
Authors: Baier Katharina , Stohl Andreas
Published: February 2023

In the last decade, tropical rainforests, e.g. the Amazon basin, have experienced events of extreme droughts. Such events have huge impacts on the forest, as trees are damaged. Therefore, it is relevant to gain deeper understanding on the main mechanisms causing such events, and further clarify the role of moisture recycling over the continent vs. moisture transport from oceanic regions.We study the role of moisture- and heat transport for the Amazon basin, with special focus on drought events. We show how these extreme events differ from normal conditions, with special focus on the changes in atmospheric transport. We analyse the atmospheric transport with the particle dispersion model FLEXPART using meteorological input data from the ERA5 reanalysis. In this Lagrangian model, the atmosphere was filled homogeneously with particles, which were traced forward in time and represent the global atmospheric mass transport. From this Lagrangian reanalysis dataset, covering the years 1979-2021, air masses over the Amazon basin are selected and traced backward in time. Based on that, we investigate the role of continental and oceanic moisture source areas, incorporating also information on soil moisture and burned areas. Thereby, we highlight the relevance of moisture recycling over continental - vs.  moisture transport from oceanic areas. For example, we found that for the northern parts of the Amazon basin the most important moisture source is the Atlantic Ocean, thus this area is less affected by deforestation in the southern areas.
Response of vegetation indices to drought in western Spain
Authors: Quirós Elia , Fragoso-Campón Laura
Published: February 2023

Drought is a transitory anomaly, prolonged, characterised by a period with precipitation values lower than normal in a specific area. The initial cause of any drought is a shortage of precipitation (meteorological drought) which leads to a shortage of water resources (hydrological drought) necessary to supply the existing demand. Flash drought is a critical sub-seasonal phenomenon that can be devasted for the ecosystems and, consequently, for general economy and health. There are areas where droughts are more devastating, and Spain is in a medium risk zone. In addition to water supplies, one of the first elements where the effects of droughts are first felt is on vegetation. Recent studies have addressed the relationship between NDVI and drought events. They concluded that, although vegetation activity over large parts of Spain is closely related to the interannual variability of drought, there are clear seasonal differences in the response of the NDVI to drought.The World Meteorological Organization (WMO) categorises various drought indices into different groups such as (a) meteorology, (b) soil moisture, (c) hydrology, (d) remote sensing and (e) composite or modelled. Within the group of indices that can be defined by remote sensing, it points out some indices as possible predictors or evaluators of drought periods such us the Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI). However, WMO leaves open the use of other possible VIs for drought prediction or assessment. In the current scenario, where there are multiple vegetation indices that can be used from satellite imagery, the initial objective of the study is to establish, from a set of VIs proposed or not by the WMO, which ones have the highest correlation with drought events in the study area. This correlation will be analysed according to vegetation type  (using the categorisation of the recently published ESA World cover map), in order to attempt to determine the behaviour of the vegetation index under meteorology according to each type. The study area is located in the Extremadura region of western Spain. The mean annual precipitation of the zone ranges from 446 to 1323 mm. The precipitations occur mainly from October to April while June, July and August suffer a significant drought with none or close to zero precipitation amount. The land cover types are mainly forests, agricultural and impervious cover. Regarding the temporal extent, two episodes of severe drought (2005-2006 and 2021-2022) will be studied.Firstly, the vegetation indices available in open collections like OpenEO or Copernicus Global Land Service will be used. All available indices will be used to create time series to be compared with meteorological time series. Once the correlation is established, it will be analysed according to the type of coverage of the World cover map, in order to establish which index correlates better with drought episodes and thus try to establish the best predictor/evaluator.
Development of supraglacial meltwater streams and their influence on the morphology of debris-covered glacier surfaces.
Authors: Ouvry Boris , Kneib Marin , Purves Ross S. , Vieli Andreas
Published: February 2023

Debris-covered glacier tongues are widespread in high-relief mountains and are characterised by highly undulated surfaces with supraglacial ponds and circular cliffs in hummocky topography. These features are known to strongly enhance mass loss on debris-covered surfaces and have been widely mapped, but their formation mechanisms and underlying controls have not been studied in detail.Here we aim to investigate the role of supraglacial streams on the morphological development of debris-covered glacier surfaces and related supraglacial features such as ice cliffs based on high-resolution DEMs and orthophotos (Pleiades and UAV) from two debris-covered glaciers of contrasting spatial scales: the Satopanth Glacier located in the Indian Himalaya and the Zmuttgletscher in the European Alps. We systematically analyse the morphological development of the debris-covered surface along the glacier from the onset zone of debris cover and supraglacial channels down to the hummocky and sunken tongue surfaces. We perform this using a semi-automated approach that includes meltwater flow routing, the extraction of surface roughness, profiles and extents of supraglacial channel-influenced valleys, as well as the mapping of ice cliffs.Based on this analysis, we find a clear and coherent succession of morphological developments along both glaciers that seems initiated through erosion from supraglacial streams. On the initially smooth debris-covered surface, locally incised and meandering channels initiate ice cliffs that progressively backwaste, creating a downstream-widening supraglacial valley with an undulated surface. This ‘mobility area’ is advected downstream even beyond the moulins where the supraglacial channels drain to the bed. Further downstream, neighbouring ‘mobility area’ valleys laterally merge and create the quasi-chaotic highly undulated surfaces typically observed on tongues of debris-covered glaciers. We integrate these interpretations into a conceptual model that links the downstream morphological development of debris-covered surfaces and explains the genesis of related features such as ice cliffs.
Experimental and simulation study of quasistatic capillary rise resulting in pressure-saturation (p-s) hysteresis
Authors: Nepal Animesh , Dentz Marco , Hidalgo Juan J , Ortin Jordi , Lunati Ivan
Published: February 2023

During imbibition, fluid-fluid interface at the inlet of a constriction experiences an increase in capillary force that results in rapid fluid invasion known as Haines jump. During drainage, the interface gets pinned at the end of the constriction, which causes p-s trajectories to follow different paths during imbibition and drainage resulting in p-s hysteresis. In this work, we performed quasistatic two-phase flow experiments and simulations of cyclic imbibition and drainage to have a quantitative understanding of pore-scale processes resulting in pressure-saturation (p-s) hysteresis. We considered two different 2D Hele-Shaw cell setups: a capillary tube with a horizontal constriction (ink-bottle) and a heterogeneous porous media randomly populated by cylindrical obstacles. In both setups, drainage and imbibition were driven by quasitatically changing the pressure gradient between the inlet and the outlet of the domain. The experimental results were compared with the results from numerical model in OpenFOAM, which solves the Navier-Stokes equations employing volume of fluid method to calculate the position of the interface and the continuum surface force model to describe surface tension. For the ink-bottle setup, we observed that multiphase flow through a single constriction displayed the signature trait of p-s hysteresis, which depends innately on the cross-section gradient. The steeper the cross-section gradient, the more pronounced the p-s hysteresis, moreover, p-s hysteresis did not occur below a critical gradient. We derived an analytical solution to calculate the critical gradient and compared it with the critical gradient obtained from experiments and simulations. In heterogeneous porous media setup, we observed rapid fluid invasion and retention patterns in small pores during imbibition-drainage cycles, which give rise to hysteretic p-s trajectories. This comparative study will allow us to quantitatively link the pore-scale capillary physics to large-scale p-s hysteresis.
Controls on global submarine canyon occurrence and formation processe s– Insights from Spatial Point Pattern Analysis –
Authors: Bernhardt Anne , Schwanghart Wolfgang
Published: February 2023

Submarine canyons are the main conduits that transport material such as sediment, organic carbon, and litter from the continent to the deep sea. This transport of material is more efficient when the canyon heads incise into the shelf, as opposed to canyons that are confined to the continental slope. The specific controls on the distribution of these two canyon types along the world’s continental margins remain unquantified and we still lack knowledge about these seascape shaping processes.Spatial statistics on a global scale help to reveal these processes.  In this study, we successfully predict the global patterns of submarine canyon occurrence along major continental margins based on terrestrial and marine environmental variables using point patterns on linear networks. We show that submarine canyon density of both types increases as a function of gradient of the continental slope which is the most important predictor. Subsequently, the locations of slope-confined canyons are best predicted by age of the adjacent ocean lithosphere with old ages corresponding to high canyon densities. Shelf-incised canyons are best predicted by the shelf gradient which correlates positively with shelf-incised canyon densities and, to a lesser extent, by high water discharge from the adjacent catchments.Our results show that marine variables – primarily the continental slope gradient - are most crucial for spatially predicting submarine canyons while terrestrial variables are of lesser importance. The influence of terrestrial conditions and shelf morphology on slope-confined canyons is minimal. However, incision of canyons into the shelf is facilitated when shelves are steep and river discharge is high, highlighting the secondary role of canyon head erosion by terrestrially derived sediment. Our results underscore that the formation of submarine canyons worldwide is mainly governed by backward erosion along steep continental slopes by mass failure and/ or erosive sediment density currents.  Erosion by sediment flows carrying sediment directly from terrestrial sources is likely less important for the formation of submarine canyons. 
Aggregates vs pores? A survey among soil scientists about perspectives on soil structure
Authors: Roosch Svenja
Published: February 2023

Two perspectives on soil structure have often been juxtaposed in the past: the “solid phase” or “aggregate” perspective and the “pore” perspective. The debate intensified recently with several opinion papers, letters to the editor, and editorials being published on that matter. The discussion centred around the usefulness of the aggregate concept. Main disputed aspects were whether aggregates (a) are suitable experimental units for measuring and upscaling soil functions and (b) exist in situ or are mere artefacts of the separation method. Some researchers view the pore perspective as superior regarding the explanation and measurement of soil functions and predict that it will largely replace the aggregate perspective. This would mean a major change in the mental models that, up to now, many soil scientists have of the soils they study. Yet the topic remains highly controversial. Despite disagreements between researchers following one or the other perspective, some researchers view these perspectives as complementary, not exclusive. Do we not even agree to disagree? Moreover, people taking the same broad perspective may not agree on all aspects on how to use the concept, as the discussion about aggregates as “biogeochemical reactors” for greenhouse gas production showed.In order to have a constructive and efficient debate, it seems necessary that we better understand the different perspectives, arguments, and use of terms. Moreover, the discussion in written publications only reflects the views of a part of the scientific community. Thus, in order to gain a broader overview of the views currently present in soil science, other – additional – ways of communication are necessary.An online survey is a low-inhibition tool to get insight into peoples’ thoughts. A short English-language survey will be spread via email and social media with the aim to answer the following questions:1. How is the approval of pore or aggregate perspective distributed among soil scientists?2. How do soil scientists judge the compatibility of the two approaches?3. (How) do perspectives on soil structure differ between soil scientists at different career stages?Preliminary results of single or multiple choice questions will be presented to sketch the status quo of how the soil science community conceptually relates to soil structure. Data grouped by career stage might give hints for a future development of this debate.