bluuebunny/crossref_metadata_2025 huggingface dataset:
Drag-Based Ensemble Model (DBEMv4) with variable solar wind speed input
Authors: Čalogović Jaša , Dumbović Mateja , Vršnak Bojan , Temmer Manuela , Veronig Astrid
Published: March 2022

Drag-Based Ensemble Model (DBEM) is a probabilistic model for heliospheric propagation of Coronal Mass Ejections (CMEs) that predicts the CME hit chance, most probable arrival times and speeds, quantify the prediction uncertainties and calculate the confidence intervals. DBEM is based on the 2D analytical Drag-based Model (DBM) with very short computational time. By using CME cone geometry with flattening DBM calculates the CME arrival time and speed at Earth or any other given target in the solar system. DBEM considers the variability of model input parameters by making an ensemble of n different input parameters to obtain the distribution and significance of the DBM results. As an important tool for space weather forecasters, DBM/DBEM web application is integrated as one of the ESA Space Situational Awareness portal services (https://swe.ssa.esa.int/current-space-weather). Important requirement to perform DBM calculations is to assume that two input parameters namely background solar wind speed and the drag parameter γ are constant in order to have the analytical solution and fast computational times. However, this assumption is not always valid in more complex heliospheric conditions. Thus, to further increase the accuracy of CME propagation forecast we developed the new DBEMv4 version that calculates CME propagation in more steps with variable solar wind speeds. This allows also to employ as DBEMv4 input the dynamic solar wind data in real-time taken from simple persistence model under consideration of the CME propagation direction.
Jullienella foetida Schlumberger, the largest shallow-water agglutinated foraminifer in modern oceans
Authors: Langer Martin R. , Weinmann Anna E. , Makled Walid , Koenen Janine , Gooday Andrew J.
Published: March 2022

Jullienella foetida is probably the largest agglutinated foraminifer in modern oceans and can reach a length of up to ~14 cm. Because of its large size, the species was initially considered to be a bryozoan, but later correctly described as a single-chambered (monothalamous) foraminifer with a large, flat or slightly undulating plate-like test, leaf-like, or fan-like in overall shape and with the chamber interior subdivided by longitudinal partitions. It occupies a restricted geographical range around part of the NW African margin where it is found in eutrophic settings with a preference for energetic environments.

We have applied a suite of non-destructive methods, namely light microscopy, SEM, X-ray and high-resolution micro-computed tomography (micro-CT) to 1) explore its external and internal test characteristics and 2) to provide a first-order estimate of its possible contribution to sea floor biomass. High-resolution SEM images show the test wall to comprises a smooth, outer veneer of small mineral grains that overlies the much thicker inner layer, which has a porous structure and is composed of grains measuring several hundreds of microns in size.  X-ray images of the test reveal an elaborate system of radial partitions that subdivides the test interior into channels that may serve to direct the flow of the cytoplasm, and perhaps increase its surface to volume ratio.  Micro-CT scans suggest that much of the test interior is filled with cytoplasm with a biomass comparable to that of slightly larger xenophyophores. This remarkable species appears to play an important, perhaps keystone, role in benthic ecosystems where it is abundant, providing the only common hard substrate on which sessile organisms can settle.
Establishing a zero-pollution circular economy: an overview of the Horizon2020-Green Deal project PROMISCES 
Authors: Lions Julie , Miehe Ulf , Zhiteneva Veronika , Togola Anne , Groot Hans , Bakker Martine , van Hullebusch Eric D. , Dulio Valeria , Zjip Michiel , Heine Nicole , Track Thomas , Sperlich Alexander , Zessner Matthias , Bosch Carme , Fatone Francesco , Colombano Stefan , Fernandez-Rojo Lidia , Negrel Philippe
Published: March 2022

The PROMISCES project aims to understand the origins, routes and fates of industrial persistent, mobile and potentially toxic pollutants (iPM(T)s), including per- and polyfluoroalkyl substances (PFAS). These substances, also called “forever chemicals”, can be harmful to the environment, human health and circular economy resources.

PROMISCES will develop, test and demonstrate, new technologies and innovations to prevent, monitor and remediate iPM(T)s in the soil-sediment-water system under real-life conditions in the field. In this way, PROMISCES will establish more cost-effective, sustainable and ecological technologies for remediating PFAS and iPM(T)s.

The project will support the European Green Deal goals and sustainability roadmap of urbanised areas by reducing the environmental impacts on waters (surface and groundwater, urban runoff, drinking waters, wastewater, landfill leachate), soils (contaminated sites, brownfields) and dredged sediments (river, seaports) and of nutrient and material recovery (from sewage sludge to recovered fertilisers, dredged sediments to valorised materials, reclaimed water to crops).

To pursue this objective, PROMISCES is centered around seven representative case studies in different European regions linked with challenging chemical pollution, including locations in Spain, Italy, Bulgaria, France, Germany and the Danube river basin between Vienna and Budapest.

This Horizon2020-Green Deal project will address key technological challenges while also developing recommendations for implementing relevant EU plans - such as the Zero Pollution Action Plan, the Circular Economy Action Plan and the EU chemicals strategy for sustainability - and EU policy directives, such as the Sewage Sludge Directive and the Water Framework Directive.
Mobility of Fluopyram in soils under saturated flow conditions
Authors: Vasconcelos Barroca Mariana , Arye Gilboa
Published: March 2022

A new generation of non-fumigant nematicides has recently been introduced and is essential to enable efficient and sustainable agricultural production. Fluopyram (FL) is a new compound with a novel mode of action and an improved safety profile. The aim of this study was to quantify the adsorption and transport of FL in 3 soils with different texture under increasing water flows. Initially, equilibrium adsorption isotherms were measured by batch method. Then, FL transport characteristics were analyzed by flowthrough experiments under saturated flow conditions in soil columns. A pulse input of FL was given together with Bromide (Br), used as a conservative tracer. The flowthrough experiments were performed with 3 different soil types, loamy sand, loam and clay under 3 water flow rates, 0.3, 1 and 4 ml min-1, then analyzed and simulated with the convection–dispersion equation (CDE). Equilibrium and kinetic reaction terms were employed to consider sorption of FL. The adsorption isotherms of FL exhibited linear behavior for all soils, with distribution coefficient (Kd) varying from 0.72 to 1.87 L Kg-1 for loam and clay respectively. The established breakthrough curves (BTCs) obtained for bromide exhibited a symmetrical pattern, regardless of soil texture and flow rates, with an average of 100% of Br recovered, suggesting that physical equilibrium is prevailing in all columns. The FL BTCs exhibited sharp increase in concentration after pulse input and long tailing during leaching phase, not fully completed after leaching for 17 pore volumes (PV). The experimental mass balance demonstrated a maximum of 90% recovery on sandy soil and a minimum of 79% in clayey texture. This might indicate that FL has fast adsorption on soil and slow desorption kinetics or even some irreversible adsorption. To understand better the processes affecting FL transport in soils, two models of solute transport were used, a Two-sites sorption model (TSM) and Two-kinetic sites model. When irreversibility was assumed, both models underestimated the tailing of BTCs, trending the curve to zero; showing that instead of irreversible desorption, the long-term leaching behavior is due to a very slow desorption rate. All the models could describe well the adsorption process and confirmed that part of FL has quick adsorption in soil which is in agreement with the low mobility observed. Further evaluation on FL transport characteristics and the adequacy of the different numerical model will be discussed. 
Double single-force model to characterize the detachment and impact of a landslide: application to the 07-02-2021 Uttarakhand, India landslide
Authors: Carrillo Ponce Angela , Cesca Simone , Dahm Torsten , Tilmann Frederik , Babeyko Andrey , Rekapalli Rajesh , Rao N. Purnachandra
Published: March 2022

Landslides begin with the detachment of a mass and end with its impact at lower altitude. To simultaneously model seismic signals produced by these processes, we consider a double single-force model. We applied this source model to the seismic signals generated by the landslide in Uttarakhand, India, on February 7th, 2021. We model the seismic recordings at 12 seismic stations located at less than 100 km epicentral distance. We perform the source inversion by fitting low-frequency (0.08-0.15 Hz) three component (vertical, radial, transversal) waveforms in the time and simultaneously their amplitude spectra in the frequency domain. We compare our results with those obtained for a single-force model applied to each pulse separately. Our results identify two energetic pulses separated by a time delay of ~1 minute. The amplitude of the second pulse, interpreted as the impact, is ~3 times larger than the first one, and of opposite sign. Together with visual observations of the landslide itself, our results confirm that the first pulse was produced by the detachment of the rock mass and the second one by the impact of the mass in the valley. The orientations of the single forces are consistent with the slope geometry and the direction of the debris flow. We discuss statistical measures of fit of the two different inversion approaches and the possible strengths and weaknesses of the new double single-force model.
Cascading tipping in a coupled cryosphere-ocean model
Authors: Sinet Sacha , von der Heydt Anna S. , Dijkstra Henk A.
Published: March 2022

In the climate system, many different large-scale components have been identified as tipping elements, i.e., components that may pass a tipping point, with a substantial and definitive impact on earth and societies. These climate components do not stand on their own, but are dynamically coupled, which leads to the issue of cascading tipping. One important example of cascading involves the Greenland Ice Sheet (GIS), the West Antarctica Ice Sheet (WAIS) and the Atlantic Meridional Overturning Circulation (AMOC). While the destabilizing effect of a GIS decline on the AMOC is well established, the effect of a tipping WAIS is still unclear.

 

In this project, we aim at getting a better understanding of the global behaviour of this connected system, at a conceptual level. Accounting for the different nature of both ice sheets, we use two models including their most important feedbacks, namely, the marine ice sheet instability for the WAIS and the height-accumulation feedback for the GIS. The AMOC, depicted by the Rooth model, is coupled to both ice sheets through meltwater fluxes. Finally, we consider the Southern Ocean temperature as the main driver of the marine ice sheet instability.

With this conceptual interhemispheric model, we study the role of the AMOC as mediator of this potential cascading in hosing and/or climate change experiments, as well as the involved time scales. As a new result we find that, in this model, the stability of the AMOC depends on the ratio between the GIS and WAIS tipping rates, as well as their delay in time.
Errors in Mass Balance estimates of Antarctica from ice mask and input-output inconsistencies, pinpointed by GRACE
Authors: Hansen Nicolaj , Simonsen Sebastian B. , Boberg Fredrik , Forsberg Rene , Mottram Ruth
Published: March 2022

Surface mass balance (SMB) is computed from regional climate models (RCM) using reanalysis data. Estimates of the SMB vary between RCMs due to differences such as the model set-up, physical parameterizations, and topography as well as ice mask. The ice mask in a model defines the surface covered by glacier ice. The differences in ice masks appear small, however it is here shown that it leads to important differences in SMB when integrated over the continent. To circumvent this area-dependent bias, intercomparison studies of modelled SMB use a common ice mask (Mottram et al., 2021). The SMB in areas outside the common ice mask is discarded. By comparing the native ice masks with the common ice mask used in Mottram et al. 2021 we find differences in integrated SMB of between 20.1 and 102.4 Gt per year over the grounded ice sheet when compared to the ensemble mean from Mottram et al. 2021. These differences are nearly equivalent to the entire Antarctic ice sheet mass imbalance identified in the IMBIE study.
SMB is particularly essential when estimating the total mass balance of an ice sheet via the input-output method, by subtracting ice discharge from the SMB to derive the mass change. We use the RCM HIRHAM5 to simulate the Antarctic climate and force a newly develop offline subsurface firn model, to simulate the Antarctic SMB from 1980 to 2017. We use discharge estimates from two previously published studies to calculate the regional scale mass budget. To validate the results from the input-output method, we compared the results to the gravimetry-derived mass balance from the GRACE/GRACE-FO mass loss time series, computed for the period 2002–2020. We find good agreement between the two input-output results and GRACE in West Antarctica, however, there are large disagreements between the two input-output methods in East Antarctica and over the Antarctic Peninsula. Over the entire grounded ice sheet, GRACE detects a mass loss of 900 Gt for the period 2002-2017, whereas the two input-output results show a mass gain of 500 Gt and a mass loss of 4000 Gt, depending on which discharge dataset is used. These results are integrated over the native HIRHAM5 ice mask. If we instead integrate over the common ice mask from Mottram et al. 2021, the results change from a mass gain of 500 Gt to a mass loss of 500 Gt, and a mass loss of 4000 Gt to a mass loss of 5000 Gt, over the grounded ice sheet for the period 2002-2017. While the differences in ice discharge remain the largest sources of uncertainty in the Antarctic ice sheet mass budget, our analysis shows that even a small area bias in ice mask can have a huge impact in high precipitation areas and therefore SMB estimates. We conclude there is a pressing need for a common ice mask protocol, to create an accurate harmonized updated ice mask.
Snow height monitoring in coastal Greenland – datasets, scales and climatic drivers
Authors: Abermann Jakob , Rasmussen Kerstin , Langley Kirsty , van der Schot Jorrit , Silva Tiago , Winkler Michael , Schellander Harald , Schöner Wolfgang
Published: March 2022

In this contribution we compile hitherto little or unused snow height data for Greenland. We present time-series of autonomously measured snow heights at around 10 locations in different parts of Greenland dating back to 1997. This data was largely measured and archived by Asiaq, Greenland Survey, for varying applications. We show the wide variability of snow heights and determine snow water equivalent using a recently developed model approach. The performance of the model to reproduce manually measured snow water equivalent is striking given the simplicity of input (solely snow depth) and the complexity of the different snow climates. We assess the hydrological significance of seasonal snow cover for very varying climatological conditions in Greenland and evaluate that the hysteresis between snow depth and snow water equivalent formation and depletion differs in shape and strength depending on the general climatological conditions.

In a further step we analyze the drivers of the observed variability relating snow height anomalies to climate oscillation indices (such as NAO, GBI). We hypothesize that the impact of climate oscillations on snow height anomalies is spatially variable in coastal Greenland. Furthermore, we assess to which extent the timing of spring onset determines snow depletion rates.

Finally, given the spatial heterogeneity of snow measurements, we assess the capability of a regional climate model to reproduce snow height and snow water equivalent and relate its performance to topography.
Evaluation of Assimilation in the MASNUM Wave Model Based on Jason-3 and CFOSAT 
Authors: Sun Meng , Du Jianting , Yang Yongzeng , Yin Xunqiang
Published: March 2022

Accurate numerical simulation of ocean waves is one of the most important measures to ensure shipping safety, offshore engineering construction, etc. The use of wave observations from satellite is an efficient way to correct model results. The goal of this paper is to assess the performance of assimilation in the MASNUM wave model for the Indian Ocean. The assimilation technique is based on Ensemble Adjusted Kalman Filter, with a variable ensemble constructed by the dynamic sampling method rather than ensemble members of wave model. Observations of significant wave height from satellites Jason-3 and CFOSAT are regarded as assimilation data and independent validation data, respectively. The results indicate good performance in terms of absolute mean error for significant wave height. Model error decreases by roughly 20–40% in high-sea conditions.
Sedimentary evidence for a Quaternary mega-tsunami in NW Australia
Authors: Larcombe Piers , Wilson Moyra , Whitley Thomas , Ward Ingrid , Pirrie Duncan , Li Tanghua , Hill Jon , Florec Veronique , Bateman Mark
Published: March 2022

Tsunamis can cause catastrophic impacts at the coastline. Australia’s NW continental margin displays abundant massive slope-failure deposits, but there is little evidence of associated coastal tsunami deposits. Here we report on investigations of an exposed field of cemented dunes and associated conglomero-breccias, located on Barrow Island. Preliminary OSL dating indicates that these deposits formed when relative sea level was around 30 to 50 m below present. If the deposits can be interpreted as having been formed by a mega-tsunami, then it was a very significant event that ran inland several km and achieved a maximum run-up of several tens of metres. A similar event today would directly impact thousands of people, multiple ports, and industrial facilities worth many billions of dollars, as well as impacting many unique ecological and cultural resources.
Joint Geophysical and Petrological Inversion to Image the Lithosphere and Asthenosphere Beneath Ireland and Britain
Authors: Chambers Emma , Bonadio Raffaele , Lebedev Sergei , Fullea Javier , Kiyan Duygu , Bean Christopher , O'Reilly Brian , Meere Patrick , Rezaeifar Meysam , Tomar Gaurav , Ye Tao ,   DIG Team
Published: March 2022

DIG (De-risking Ireland’s Geothermal Potential) integrates inter-disciplinary and multi-scale datasets in order to investigate Ireland’s low-enthalpy geothermal energy potential. Recent deployments of broadband seismic stations and the output surface-wave measurements yield dense data sampling of the crust and mantle beneath Ireland and neighbouring Great Britain, which can be used to determine the lithospheric and asthenospheric structure at a regional scale. In addition, we integrate magnetotelluric measurements, forming the foundations for a region-scale, multi-parameter modelling of the thermal and compositional structure of the lithosphere.

In this study, we utilise the large seismic dataset and extract Rayleigh and Love-wave phase velocity dispersion curves, measured for pairs of stations across Ireland and Great Britain. The measurements were performed using two methods with complementary period ranges; the teleseismic cross-correlation method and the waveform inversion method, yielding a 4-500 s period range for the dispersion curves. The joint analysis of Rayleigh and Love measurements constrains the isotropic-average shear-wave velocity, relatable to temperature and composition, providing essential constraints on the thermal structure of the region’s lithosphere. We demonstrate this by inverting the data using an integrated joint geophysical-petrological thermodynamically self-consistent approach (Fullea et al., GJI 2021), where seismic velocities, electrical conductivity, and density are dependent on mineralogy, temperature, composition, water content, and the presence of melt. The multi-parameter models produced by the integrated inversions fit the surface-wave and other data, revealing the temperatures and geothermal gradients within the crust and mantle, which will be used for future geothermal exploration and utilisation.

The project is funded by the Sustainable Energy Authority of Ireland under the SEAI Research, Development & Demonstration Funding Programme 2019 (grant number 19/RDD/522) and by the Geological Survey of Ireland.
Investigation of custom-made metakaolin-based geopolymers for stone conservation: preliminary results on activation
Authors: van Roosmale Sophie , De Kock Tim , Blom Johan
Published: March 2022

Geopolymers are an interesting material because they are inorganic and non-toxic, they are inexpensive because the raw materials are easy to obtain, and they also have high strength and are able to process and adjust. These properties make them an innovative alternative to restoration mortars, which carry out current restoration treatments of stone heritage, but which often cause more damage because they are not fully compatible with the original.

Geopolymers are stone-like materials placed between binders, such as cements and ceramics. Different types of geopolymers exist, depending on the raw materials and the system through which they are activated. In this research we focus on geopolymers with a base of metakaolin. Metakaolin based geopolymers improve the properties of the end product compared to geopolymers based on fly-ash and ground granulated blast furnace slag. For curing the geopolymer, certain requirements have been set that take into account the application of the geopolymer in the restoration sector in the future, like curing by room temperature and ambient relative humidity in less than 48 hours. A set of reactivity tests have been performed to determine the appropriate activator and to optimize their ideal molarity. These tests shows that calcium hydroxide give the best results in forming a matrix of geopolymer.

In the next phase of the research, the compatibility between the geopolymer and porous sedimentary building stones will be investigated. The properties that are important for technical compatibility include: porosity, pore size distribution, capillary water absorption, frost resistance, structure, texture, compressive and bending strength. Samples are made with standardized aggregates of marl flour (porous calcium carbonate flour), limestone flour (non-porous calcium carbonate flour) and relatively pure sand with various grain size distribution to evaluate the compatibility and to investigate the effects on reactivity. It is critical this test phase is carried out with pure products, so that any contamination cannot affect the results. In the following stage it is then possible to experiment with the effect of degraded and contaminated original material as aggregate.
Subglacial export of coarse sediment from temperate Alpine glaciers by meltwater
Authors: Jenkin Matthew , Mancini Davide , Miesen Floreana , Hofmann Margaux , Hubbard Bryn , Herman Frédéric , Lane Stuart N.
Published: March 2022

Proglacial measurements of subglacial sediment export by meltwater are commonly used to estimate glacial erosion rates. Such estimates generally assume that subglacial meltwater flow is the dominant agent driving export and that eroded sediment is rapidly conveyed through subglacial drainage networks to the glacier outlet in efficient channels with large and generally-unsatisfied transport capacities. However, understanding of sediment transport processes under glaciers is limited, especially in the thin, snout-marginal zones of retreating temperate Alpine glaciers.

A growing body of field and model-based research from such systems challenges the theory that eroded sediment is rapidly evacuated. Conversely, Alpine glaciers develop intense diurnal and seasonal discharge variation leading to highly variable sediment transport competence and the moderation of sediment export by associated cycles of alluviation. This has important consequences for the timescales over which sediment export can be used as a reliable proxy for glacial erosion, though the problem remains that very little is known about when and under what conditions a glacier margin is capable of evacuating the sediment supplied to it.

This study attempts to elucidate sediment transport mechanisms and timescales in the main snout-marginal subglacial channel of glacier d’Otemma, Switzerland, by tracking 324 cobble-sized particles tagged with 433 MHz active radio transponders over the mid-to-late 2021 melt season. Tagged particles were injected into the channel via a 48 m deep borehole and were then tracked over a 350 m subglacial reach and a 150 m proglacial reach with a mobile antenna and stationary antenna arrays.

Only 86 particles (27%) were exported in 2021. Preliminary analyses indicate that cobble-sized particles generally have extended residence times in snout marginal zones (weeks to months), with no clear effect of particle size, shape or density on overall transport velocities. Ongoing work involves the daily localisation of particles using a signal strength-based algorithm, providing a unique record of the down-glacier transport of coarse particles in a subglacial channel. Repeat measurements will follow in 2022.
Polarization of Langmuir waves observed by RPW-TDS instrument on Solar Orbiter during Type III radio bursts
Authors: Soucek Jan , Bandara Sampath , Pisa David , Santolik Ondrej , Maksimovic Milan , Chust Thomas , Khotyaintsev Yuri , Vecchio Antonio , Kretzschmar Matthieu , Wimmer-Schweingruber Robert , Berger Lars , Rodriquez-Pacheco Javier , Gomez-Herrero Raul
Published: March 2022

We investigate the polarization of Langmuir waves observed by the Time Domain Sampler (TDS) module of the Radio and Plasma Waves instrument on Solar Orbiter during several extensive Type III burst events. During its two-year-long cruise phase, Solar orbiter often crossed the source region of the Type III radio emission and observed the Langmuir waves generated by solar energetic electrons. The waves are known to exhibit complex modulation and often non-trivial elliptical polarization which sometimes rapidly changes on the timescales of tens of milliseconds. We show that the observed waveforms are typically composed of multiple sub-packets with a relatively short coherence length. We investigate the correlation between the polarization of the waves, simultaneously observed energetic electrons beams and other plasma properties.
Recent Hadley circulation strengthening: a trend or multidecadal variability?
Authors: Zaplotnik Žiga , Pikovnik Matic , Boljka Lina
Published: March 2022

This study explores the possible drivers of the recent Hadley circulation strengthening in the modern reanalyses. Predominantly, two recent generations of reanalyses provided by the European Centre for Medium-Range Weather Forecasts are used: the fifth-generation atmospheric reanalysis (ERA5) and the interim reanalysis (ERA-Interim). Some results are also evaluated against other long-term reanalyses. To assess the origins of the Hadley cell (HC) strength variability we employ the Kuo-Eliassen (KE) equation. ERA5 shows that both HCs were strengthening prior to 2000s, but they have been weakening or remained steady afterwards. Most of the long-term variability in the strength of the HCs is explained by the meridional gradient of diabatic (latent) heating, which is related to precipitation gradients. However, the strengthening of both HCs in ERA5 is larger than the strengthening expected from the observed zonal-mean precipitation gradient (via Global Precipitation Climatology Project, GPCP). This suggests that the HC strength trends in the recent decades in ERA5 can be explained partly as an artifact of the misrepresentation of latent heating and partly through (physical) long-term variability. To show that the latter is true, we analyze ERA5 preliminary data for the 1950-1978 period, other long-term (e.g. 20th century) reanalyses, and sea surface temperature observational data. This reveals that the changes in the HC strength can be a consequence of the Atlantic multidecadal variability (AMV) and related diabatic and frictional processes, which in turn drive the global HC variability. This work has implications for further understanding of the long-term variability of the Hadley circulation.
The evaluation of crustal field influence to geomagnetic cutt-off rigidities
Authors: Jakab Patrik , Bobík Pavol
Published: March 2022

The cut-off rigidities of cosmic rays usually do not reflect the influence of the crustal geomagnetic field. Due to the weakness of the crustal field effect to the cosmic rays trajectories are very minor. However, two regions of the world have a crustal field with significantly higher values. The effect of the crustal field in those regions is evaluated. The consequences for the approach of cosmic rays to Earth's surface (top of the Earth atmosphere) in the last decades are analyzed and discussed. Presented are suggestions for possible modification of models for evaluation of Earth's magnetosphere transparency for cosmic rays.
Unprecedented Expansion of the Azores High due to Anthropogenic Climate Change
Authors: Ummenhofer Caroline , Cresswell-Clay Nathaniel , Thatcher Diana , Wanamaker Alan , Denniston Rhawn , Asmerom Yemane , Polyak Victor
Published: March 2022

The Azores High is a subtropical high-pressure ridge in the North Atlantic surrounded by anticyclonic winds that steer rain-bearing weather systems. The size and intensity of the Azores High modulate the oceanic moisture transport to Europe thereby affecting hydroclimate across western Europe, especially during wintertime. While changes in the North Atlantic storm track have been linked to the variability of the North Atlantic Oscillation (NAO), we focus on North Atlantic variability with a subtropical perspective by focusing on the Azores High independently of the Icelandic Low. The subtropical perspective provides a direct understanding of regional climate variability in the western Mediterranean and reveals dramatic changes to North Atlantic climate throughout the past century and can provide insight into the impact of future warming on the dynamics of the Azores High and associated hydroclimate. Here we show that winters with an extremely large Azores High are significantly more common in the industrial era (since 1850 CE) than in preindustrial times, resulting in anomalously dry conditions across the western Mediterranean, including the Iberian Peninsula. Climate model simulations of the past millennium indicate that the industrial-era expansion of the Azores High is unprecedented throughout the last millennium (since 850 CE), consistent with proxy evidence from Portugal. Azores High expansion emerges after the end of the Little Ice Age and strengthens into the 20th century consistent with anthropogenically-driven warming.
Drought legacy effects in radial tree growth are rarely significant under heightened statistical scrutiny
Authors: Klesse Stefan , Babst Flurin , Evans Margaret E.K. , Hurley Alexander , Pappas Christoforos , Peters Richard L.
Published: March 2022

Drought legacy effects in radial tree growth have been extensively studied over the last decade and are found to critically influence carbon sequestration in woody biomass. Typically quantified as a deviation from “normal” growth, drought legacy magnitude and statistical significance depend on the definition of expected vs. unexpected growth variability under average conditions – a definition that has received insufficient theoretical validation.

Here, we revisit popular legacy effect analyses using the International Tree-Ring Data Bank (ITRDB) and employ a synthetic data simulation to disentangle four key variables influencing the magnitude of legacy effects. We show that legacy effects i) are mainly influenced by the overall auto-correlation of radial growth time series, ii) depend on climate-growth cross-correlation, iii) are directly proportional to the year-to-year variability of the growth time series, and iv) scale with the chosen extreme event threshold. Our analysis revealed that legacy effects are a direct outcome of the omnipresent biological memory.

We further found that the interpretation of legacy effects following individual drought events at specific sites is challenged by high stochasticity, and show that the commonly perceived stronger legacy effects for conifers are the result of higher auto-correlation compared to deciduous broadleaves. Given that the existing literature has not sufficiently addressed biological memory, we present two pathways to improve future assessment and interpretation of legacy effects. First, we provide a simulation algorithm to a posteriori account for auto-correlated residuals of the initial regression model between growth and climate, i.e. a corrected Null model to determine statistical significance, thereby retrospectively adjusting expectations for “normal” growth variability. The second pathway is to a priori include lagged climate parameters in the regression model. This substantially reduces the magnitude of observed legacy effects and thus challenges us to revisit estimates of drought-induced growth deviations by considering the full spectrum of expected growth behavior. 
High-resolution InSAR reveals deformation inside the crater of Agung, Indonesia, prior to the 2017 eruption.
Authors: Bemelmans Mark , Biggs Juliet , Wookey James , Poland Mike , Ebmeier Susanna , Syahbana Devy
Published: March 2022

In September 2017, volcanic unrest in the vicinity of Mount Agung, Bali, Indonesia, increased drastically as a dike intruded between Agung and Batur volcanoes. This intrusion was followed by 5 weeks of declining activity before the eventual explosive eruption from Agung’s summit starting on November 21, 2017. We use high-resolution satellite SAR imagery to detect pre-eruptive intra-crater uplift at Agung volcano. We show that deformation of the crater floor occurred together with the dike intrusion to the northwest of the volcano. We attribute the deformation to a hydrothermal system less than 300 m below the surface that was activated by the injection of magmatic gasses. This finding indicates that Agung’s shallow magmatic system was active from the start of the increased unrest. Additionally, we observe a pulse of intra-crater uplift within 3-0.5 days prior to the onset of the eruption. The second pulse of uplift was one of the only precursors to the eruption and was probably caused by interaction between the hydrothermal system and the ascending magma. The detection of localized deformation during a volcanic crisis has important implications for eruption and unrest forecasting at Mount Agung and similar volcanoes and argues for monitoring with high-resolution SAR, which is capable of achieving both outstanding spatial resolution and, if sufficient satellites are used, excellent temporal coverage.
Drought legacy effects on ecosystem productivity across eddy-covariance FLUXNET sites
Authors: Yu Xin , Orth René , Reichstein Markus , Bahn Michael , Bastos Ana
Published: March 2022

The frequency and severity of droughts are expected to increase in the wake of climate change in many regions. Droughts not only cause concurrent impacts on the ecosystem carbon balance, but also result in legacy effects during the following seasons and years. These legacies result from, for example, drought-driven hydraulic damage or adjustments in carbon allocation. To understand how droughts might affect the carbon cycle, it is important to consider both concurrent and legacy effects. Such effects likely affect the interannual variability in carbon fluxes, but are challenging to detect in observations, and poorly represented in land surface models. Therefore, the understanding of patterns and mechanisms inducing legacy effects of drought on ecosystem carbon balance need to be improved.

In this study, we analyze the seasonal dynamic of gross primary productivity (GPP) from the FLUXNET dataset and detect legacy effects from past droughts. We predict the potential GPP in legacy periods based on a trained data-driven model using data in non-legacy periods and infer legacy effects from the difference between actual and potential GPP in legacy periods. We find that the drought-induced lagged GPP reductions are overall of similar magnitude to the concurrent GPP reductions in many sites. We further explore how drought legacy effects depend on drought intensity, vegetation type, and climate zone. These results have the potential to improve our understanding of the mechanisms of recovery and resilience of GPP to drought, thereby drought impacts on the ecosystem carbon cycle.
Responsiveness of maize to soil drying is related to a decrease in belowground hydraulic conductivity
Authors: Köhler Tina , Tung Shu-Yin , Steiner Franziska , Tyborski Nicolas , Wild Andreas , Akale Asegidew , Pausch Johanna , Lüders Tillmann , Wolfrum Sebastian , Müller Carsten , Vidal Alix , Vahl Wouter , Groth Jennifer , Eder Barbara , Ahmed Mutez , Carminati Andrea
Published: March 2022

Limited water supply is one of the largest impediments to food production worldwide in the light of climate change and increasing food demand. Stomatal regulation allows plants to promptly react to water stress and regulate water use. Although the coordination between stomatal closure and aboveground hydraulics has extensively been studied, our understanding of the impact of belowground hydraulics on stomatal regulation remains, as yet, incomplete. The overall objective of this study was to investigate the impact of belowground hydraulic conductivity as affected by differences in expressions of root and rhizosphere traits on the water use regulation of different maize genotypes.

We have utilized a novel phenotyping facility to investigate the response of a selection of 48 maize (Zea mays L.) genotypes exhibiting different root and rhizosphere traits to soil drying. We measured the relation between leaf water potential, soil water potential, soil water content and transpiration rate, as well as root and rhizosphere traits (e.g. root length, rhizosheath mass) between genotypes. Our hypothesis is that stomatal response to soil drying is related to a loss in soil hydraulic conductivity and that key root and rhizosphere hydraulic traits affect such relation.

We found that the genotypes differed in their responsiveness to drought and that such differences were related to belowground hydraulic traits. The critical soil water content at which plants started to decrease transpiration was related to a combination of plant- and rhizosphere traits (namely plant hydraulic conductance, maximum transpiration rate, root length and rhizosheath mass). Genotypes with a higher maximum transpiration rate and a higher plant hydraulic conductance and a smaller root system closed stomata in wetter soil conditions, meaning earlier in the drying process. This finding is explained by a soil-plant hydraulic model that assumes that stomata start to close when the soil hydraulic conductance of the soil-plant continuum starts to decline. Those findings stress the importance of belowground hydraulic properties on stomatal regulation and thereby drought responsiveness.
 Transport and Retention of Free-Living Amoeba Spores in PorousMedia 
Authors: Jin Chao
Published: March 2022

 Amoebas are protists that are widespread in water and soil environments. Some species are pathogenic, inducing potentially lethal effects on humans, making them a major threat to public health. Nonpathogenic amoebas are also of concern because they have the potential to carry a mini-microbiome of bacteria, either transiently or via more long-term stable transport. Due to their resistance to disinfection processes, the physical removal of amoeba by filtration is necessary to prevent their propagation throughout drinking water distribution networks and occurrence in tap water. In this study, a model amoeba species Dictyostelium discoideum was used to study the transport and retention behavior of amoeba spores in porous media. The key factors affecting the transport behavior of amoeba spores in fully saturated media were comprehensively evaluated, with experiments performed using a quartz crystal microbalance with dissipation monitoring (QCM-D) and parallel plate chamber system. The effects of ionic strength (IS) on the deposition of spores were found to be in contrast to the predicted Derjaguin-Landau-Verwey-Overbeek (DLVO) theory that more deposition is observed under lower-IS conditions. The presence of extracellular polymeric substances (EPS) was found to be the main contributor to deposition behavior. Overall, these results provide plausible evidence for the presence of amoeba in tap water. Furthermore, this is one of the first studies to examine the mechanisms affecting the fate of amoeba spores in porous media, providing a significant baseline for future research to minimize the safety risk presented by amoeba in porous media.
A comparative study of snowmelt runoff modelling at Rheraya watershed in the Moroccan High Atlas Mountains 
Authors: Bouamri Hafsa , Boudhar Abdelghani , Kinnard Christophe
Published: March 2022

In the Atlas Mountains range, streamflow is largely generated from meltwater supplied by the snowpack during spring and early summer. In this manner, snow is considered an important factor which determining water availability in semi-arid and arid mountains. This substantial part of freshwater stored in the form of snow contributes significantly to mountainous runoff. However, the contribution of snow and rain to the annual and multi-annual water balance remain largely unknown. Hydrological modeling is needed to support water resource assessment and management in the Atlas range. As meteorological data is often scarce, the models must be able to simulate the spatiotemporal heterogeneity of forcing variables while maintaining a low data input requirement.

In this study, the performance of the snowmelt runoff model (SRM) is assessed to simulate and forecast daily runoff essentially from snowmelt and rainfall at the Rheraya watershed in the Moroccan High Atlas range over the 2010 - 2016 period. The SRM runoff simulation is tested under two forcing inputs: (i) four snowmelt rates previously estimated by a classical temperature-index model (TI) and three enhanced temperature index models that respectively include the potential clear-sky direct radiation (HTI), the incoming solar radiation (ETI-A), and net solar radiation (ETI-B); (ii) calculated snowmelt from the snow cover area (SCA) products of Moderate-Resolution Imaging Spectroradiometer (MODIS).

All SRM simulated runoff were subjected to calibration and validation through the measured runoff in the Tahanaout weather station. The sensibility of recession coefficients was also evaluated. The SRM simulations results over the validation period show an acceptable performance.

Keywords: Runoff, SRM, snowmelt, SCA, temperature index model; enhanced degree-day models, MODIS, semi-arid climate, Rheraya, High Atlas, Morocco.

 
Spatial and temporal variability of near-surface flow pathways in a Swiss pre-alpine headwater catchment
Authors: Leuteritz Anna , Gauthier Victor , van Meerveld Ilja
Published: March 2022

In catchments with poorly drained soils, a significant part of the lateral flow on hillslopes takes place at or near the soil surface. However, there is still little knowledge about these shallow flow pathways and the factors that affect their temporal and spatial variability. Therefore, a better understanding of overland flow and shallow subsurface flow is required to enhance our understanding of runoff generation and solute transport at the catchment scale.

We installed 14 plots on vegetated hillslopes in the Studibach catchment in the Swiss pre-Alpine area that is underlain by poorly drained gleysols. We measured the overland flow and shallow subsurface flow rates at small (3 m wide) trenches, as well as the groundwater level near each plot. We, furthermore, sampled precipitation, overland flow and subsurface flow, soil water, groundwater, and stream water over a two-month period to obtain information about the stable water isotope and geochemical composition. Isotope hydrograph separation and end-member mixing analysis were used to determine the event water fractions and to quantify the fractions of precipitation, soil water, and groundwater in overland flow and lateral subsurface flow. In this presentation, we will present the first results on the temporal and spatial variability in the occurrence, amount and chemical composition of overland flow and shallow subsurface flow and describe how these are related to rainfall event characteristics and topographic position.
Lagrangian connectivity of marine plankton under thermal constraints
Authors: Manral Darshika , Amaral-Zettler Linda , van Sebille Erik
Published: March 2022

The biogeographic distribution of marine planktonic communities in the global ocean and its drivers has been a topic of great interest in the scientific community. Some of these drivers can be abiotic: ocean currents, temperature, salinity, nutrients, and others biotic: presence of predators and competitive species. In our study, we focus on the distribution mediated by ocean currents and temperature. Combining Lagrangian modeling and network theory approaches, we estimate the pathways and timescales that establish the surface connectivity for passive i.e., freely floating plankton between stations in the Atlantic Ocean where plankton have been sampled during Tara Oceans & Tara Oceans Polar Circle (2009-2013) and Tara Pacific (2016-2018) expeditions.

We obtain these estimates using a transition matrix approach derived from surface ocean simulations. Given the high rates of reproduction of many planktonic species and that only a few organisms are needed to establish connectivity, we make use of the minimum time path between different stations. To obtain plankton connectivity, two types of constraints are applied on the passive connectivity model: thermal niche and thermal adaptation rate, based on data for a given planktonic species from the literature. From the preliminary analysis, we find that, using minimum time paths, passive particles representative of foraminifera can connect all the stations in less than 3 years. Application of thermal niche constraints increases the minimum connectivity time between stations by approximately 10%, suggesting that plankton can keep to within their favorable thermal conditions by advecting via slightly longer paths. Main pathways of connectivity between these stations are also highlighted in this study. The developed approach can be applied for other plankton species, for any location in the Atlantic and can also be further expanded to derive seasonal connectivity.