bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing Last Interglacial Greenland and Antarctic Ice Sheet melting through forward stratigraphic derived synthetic outcrops: test case from Southwestern Madagascar
Authors: Boyden Patrick , Stocchi Paolo , Rovere Alessio
Published: March 2022

The last interglacial (LIG), ca. 128-116 ka, is widely considered a process analogue in understanding Earth’s systems in a future warmer climate. In particular, significant effort has been made to better constrain ice sheet contributions to sea level rise through direct field observation of relative sea level (RSL) indicators. In order to extract the RSL, a series of corrections for formational parameters and post-depositional processes need to be applied. Along tropical coastal margins, LIG RSL observations are predominately based on exposed shallow coral reef sequences due to their relatively narrow indicative range and reliable U-series chronological constraints. However, the often-limited sub-stadial temporal preservation of many Pleistocene reef sequences on stable coastlines restrict many reported RSLs to a series of distinct points in within the LIG. This in turn, limits ability to elucidate different commonly reported meter-scale sub-stadial sea level peak patterns and their associated uncertainties. In order to address this shortcoming, lithostratigraphic and geomorphologic traces are often used to place RSLs into a broader context. Unfortunately, this is often subjective, with significant reliance on field observations where missing facies and incomplete sequences can distort interpretations. Stepping back from a conventional approach, in this study we generate a spectrum of synthetic Quaternary subtropical fringing reefs in southwestern Madagascar within the DIONISOS forward stratigraphic model environment. Each reef sequence has been subjected to distinct Greenland and Antarctica melt scenarios produced by a coupled ANICE-SELEN global isostatic adjustment model, matching previously hypothesized LIG sea level curves in the Indo-Pacific Basin. The resulting suite of synthetic reef sequences provides the ability to probabilistically test any number of melt scenarios against the sensitivity of the stratigraphic record. We propose this accessible additional quantitative quality control during the final interpretation phase of establishing emergent reef sequence based LIG RSL indicators can assist in narrowing down the wide uncertainty surrounding inter-stadial ice sheet behaviors.   
Modeling of capillary and thermal nonequilibrium flows in porous media
Authors: Izvekov Oleg , Konyukhov Andrey , Cheprasov Ivan
Published: March 2022

Complex structure of a skeleton of saturated porous medium can have a great influence on the processes of heat and mass transfer. 

There are various approaches to the description of  two-phase flow: direct numerical calculation of fluid flow in the pore space, multicontinuous models with the laws of mass exchange between continua, single-continuum models of non-equilibrium flow. In the family of isothermal non-equilibrium filtration models, the relative phase permeabilities and capillary pressure are functions not of current saturation but of their change history.

In this work we generalize the relaxation model of capillary nonequilibrium to the non-isothermal case. We introduce two internal thermodynamic parameters (capillary and thermal nonequilibrium) which depend on change history of saturation and temperature. In the model relative phase permeabilities and capillary pressure are functions of saturation, temperature, and current values of these internal parameters. Based on the analysis of the dissipation inequality, thermodynamically consistent kinetic equations for the evolution of these parameters are proposed. The parameters of the single-continuum model are clarified with double-porosity model of porous media with special structure. Structure of the penetration front of fluid hot (or cold) compared to the skeleton was investigated.

This work was supported by the Russian Foundation for Basic Research: grant N19-01-00592. 

 
Performance of MOST for the latent heat flux over irrigated and rainfed terrains in a semi-arid environment
Authors: Martí Belén , Martínez-Villagrasa Daniel , Cuxart Joan , Wrenger Burkhard , Price Jeremy , Groh Jannis , Miró Josep R.
Published: March 2022

Nearby locations can sustain different values of latent heat flux, an important factor for these differences is the spatial variability in soil water content. The Land surface Interactions with the Atmosphere over the Iberian Semi-arid Environment (LIAISE) campaign took place in 2021 over an area including an irrigated-rainfed discontinuity. The instrumental display included a spatially-distributed extensive assortment of measurements, including surface energy-budget stations and sensors in masts up to 50m above the surface. As models usually have large errors in semi-arid conditions, the campaign is expected to provide good quality data for developing better ways to explore evapotranspiration in such conditions.

Estimations in semi-arid regions are scarce and different methods such as Penman-Monteith or Prisley-Taylor generate overestimations of the flux as much as with Monin Obukhov Similarity Theory (MOST). In this work the performance of MOST for the water vapour fluxes is analysed for two contrasting sites, one over irrigated grass and the other one over rainfed terrain. The study uses two instrumented levels of air temperature and moisture at 2m and 0.4 m above the surface to produce the MOST estimates of the latent flux, using eddy-covariance and lysimeter data (when available) as reference data. While daytime evapotranspiration from the surface is the main interest for applications, evaluation of nocturnal evaporation and condensation is a challenge, especially for arid terrains.
Enhancing resilience of vulnerable rural communities against hydrometeorological hazards in tropical mountains. A case study from the Sierra de las Minas, Guatemala. 
Authors: Jiménez Donato Yenny Alejandra , Restrepo Carla , Avila Mora Miguel Antonio , Catalán Armas Sara Michelle , Muñoz-Torrero Manchado Alberto , Stoffel Markus , Ballesteros Cánovas Juan Antonio
Published: March 2022

Tropical regions are particularly vulnerable to natural hazards and cascading disasters. The geography and geology of these regions, along with intense rainfall, high rates of weathering, environmental degradation and global warming, contribute to the increasing impact of hydro-meteorological hazards. More frequent and intense events introduce new risk factors that can exacerbate existing vulnerabilities. The analysis of natural hazards in tropical regions faces several challenges, such as the lack of baseline data, which prevents the implementation of effective disaster risk reduction measures. Therefore, the integration of geomorphological, ecological and dendrological studies plays an important role in understanding the impacts of future events and building community resilience. Here we combine multiple sources of data and approaches, such as, remote sensing, field data acquisition, machine learning and physical modelling to develop an integrated coupled landslide-flood risk model for the Sierra de las Minas, Guatemala. This risk analysis will strengthen the development and implementation of appropriate disaster risk reduction in rural communities.

Sierra de las Minas is a very complex region due to coalescing events such as hurricanes, earthquakes, land mass movements and floods. The impact of Hurricane Mitch in 1998 is used as a reference to understand the frequency and magnitude of these types of hydro-meteorological hazards, the triggering factors and the multi-hazard dynamics. The results are subsequently used to determine the potential socioeconomic impacts of a similar event under current conditions of vulnerability and exposure. The potential socioeconomic losses are then compared to the impacts of hurricanes Eta and Iota in 2020. This information will be used to propose adaptation strategies, such as community-based early warning systems, pedestrian evacuation models and storytelling projects, that will help reduce the underlying vulnerabilities of the community to better respond to potential events to which it is exposed.
Imaging high-enthalpy geothermal reservoirs using seismic noise interferometry
Authors: Sánchez-Pastor Pilar , Obermann Anne , Reinsch Thomas , Ágústsdóttir Þorbjörg , Gunnarsson Gunnar , Tómasdóttir Sigrún , Hjörleifsdóttir Vala , Hersir Gylfi Páll , Ágústsson Kristján , Wiemer Stefan
Published: March 2022

High-enthalpy geothermal reservoirs have been exploited for electrical power generation worldwide during the last century.  Despite the different definitions of high-enthalpy reservoirs in the literature, one can consider fluid enthalpies of around 800 kJ/kg as high. In terms of temperature, geothermal systems with more than 200°C at 1 km depth can yield high fluid enthalpies. Igneous-related geothermal reservoirs are an abundant though unexploited energy resource on Earth. The thermal energy stored in those reservoirs is much higher but the risk of drilling into a molten magma pocket is very high too.

While there are numerous geophysical exploration techniques developed for the oil and gas industry, few are directed to the geothermal sector, where profitability is much smaller. In this talk, we are going to show the potential of ambient seismic noise interferometry to image high-enthalpy geothermal reservoirs. This approach has been broadly used in many different scenarios but barely in geothermal settings. In particular, we study the Hengill area, which is located in Iceland and hosts three volcanic systems, several geothermal sub-fields and two large power plants, being one of them Hellisheiði (303 MWe, 200 MWt), one of the largest power plants in the world.

We compute a 3D shear-wave tomography from seismic noise records in the Hengill area and compare the results with several geophysical observables derived from borehole measurements in the region, such as steam ratio and formation temperature. Furthermore, we compare the results with a resistivity model obtaining an excellent correlation between both observables overall. We find some discrepancies in small areas that we interpret as a lack of thermal equilibrium. We also identify a promising site for future drilling projects.
A consistently derived set of empirical models for high-latitude electrodynamics
Authors: Hatch Spencer , Laundal Karl M , Reistad Jone P , Ohma Anders
Published: March 2022

The ionosphere-thermosphere research community has clearly expressed a need for improved, observation-based estimates of key ionosphere-thermosphere parameters such as Joule dissipation, Poynting flux, and ionospheric conductances. While global estimates of these key parameters can be obtained by combining existing empirical models, one often encounters some frustrating sources of uncertainty: the models to be combined often use different input parameters, different assumptions about hemispheric symmetry, and/or different coordinate systems. We eliminate these sources of uncertainty by deriving a new model of high-latitude ionospheric potential that can be combined with the Average Magnetic Field and Polar Current System (AMPS) model to obtain empirical estimates of Joule dissipation, Poynting flux, and ionospheric conductances. These models treat the two hemispheres independently, are derived in a mutually consistent fashion, and are based entirely on electric and magnetic field measurements made by the Swarm satellites.
Extreme waves on vertically sheared flows: Statistical analysis of weakly nonlinear waves
Authors: Zheng Zibo , Li Yan , Ellingsen Simen
Published: March 2022

A depth-dependent shear current can play a significant role in modifying the statistics of wave surface elevation, including the probability of rogue waves. This work develops a second-order theory in wave steepness for the prediction of a train of weakly nonlinear irregular waves, which extends Dalzell (1999) to allow for the influence of a depth-dependent background flow and does not rely on the assumption of irrotational flows.

The theory was implemented numerically and we focus on the analysis of statistical proprieties of random waves. The linear dispersion relation of the coupled wave-current system is solved implicitly by a direct integration method (Li & Ellingsen 2019).

Both a JONSWAP spectrum and a directionally spread distribution are used to generate random linear waves, to which second-order modifications are obtained in the presence and absence of a depth-dependent shear current. The resulting probability distributions of wave crest are found to be greatly different from the Tayfun distribution (Tayfun 1980). The shear current with positive or negative vorticity leads to an increase or decrease in the probability of rogue waves, respectively. We also analyse the effects of different shear current profiles on the wave group averaged from a number of largest waves, the spectral change, and skewness and kurtosis of wave elevation.

Key words: waves/free-surface flow, ocean surface waves, wave-current interaction

 

References

Dalzell, J. F. (1999) "A note on finite depth second-order wave–wave interactions." Applied Ocean Research 21 105-111.

Li, Y. and Ellingsen, S. Å. (2019) "A framework for modeling linear surface waves on shear currents in slowly varying waters." Journal of Geophysical Research: Oceans 124 2527-2545.  

Tayfun, M. (1980) "Narrow-band nonlinear sea waves. " Journal of Geophysical Research 85 1548-1552..
Real-Time Magnitude Determination and Ground Motion Prediction using Optical Fiber Distributed Acoustic Sensing for Earthquake Early Warning
Authors: Lior Itzhak , Rivet Diane , Sladen Anthony , Mercerat Diego , Ampuero Jean-Paul
Published: March 2022

Distributed Acoustic Sensing (DAS) is ideally suited for the challenges of Earthquake Early Warning (EEW). These distributed measurements allow for robust discrimination between earthquakes and noise, and remote recordings at hard to reach places, such as offshore, close to the hypocenters of most of the largest earthquakes on Earth. In this study, we propose the first application of DAS for EEW. We present a framework for real-time strain-rate to ground accelerations conversion, magnitude estimation and ground shaking prediction. The conversion is applied using the local slant-stack transform, adapted for real-time applications. Since currently, DAS earthquake datasets are limited to low-to-medium magnitudes, an empirical magnitude estimation approach is not feasible. To estimate the magnitude, we derive an Omega-squared-model based theoretical description for acceleration root-mean-squares (rms), a measure that can be calculated in the time-domain. Finally, peak ground motions are predicted via ground motion prediction equation that are derived using the same theoretical model, thus constituting a self-consistent EEW scheme. The method is validated using a composite dataset of earthquakes from different tectonic settings up to a magnitude of 5.7. Being theoretical, the presented approach is readily applicable to any DAS array in any seismic region and allows for continuous updating of magnitude and ground shaking predictions with time. Applying this method to optical fibers deployed near on-land and underwater faults could be decisive in the performance of EEW systems, significantly improving earthquake warning times and allowing for better preparedness for intense shaking.
Satellite imagery band ratio for mapping the open pit mines: A preliminary study 
Authors: Punia Anita , Bharti Rishikesh , Joshi Pawan Kumar
Published: March 2022

Indices are designed to differentiate land use and land cover classes to avoid misinterpretation of landscape features. The resemblances of spectral reflectance of mines with urban built-up and barren land cause difficulties in identification of objects. Open pit mines of Rampura-Agucha for Zn and Pb were selected for this study. The freely available data of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was selected from the year of 2001 and 2003. It is observed that b1-b5/b1+b5 equation of ASTER imagery significantly differentiate Zn-Pb mine from urban settlement and other features. The reflected range (µm) for b1 and b5 is 0.52-0.60 (Visible and Near-Infrared) and 2.145-2.185 (Shortwave Infrared) respectively. The pixel values indicate higher reflectance of open pit suggesting feasibility of equation for differentiating it from barren and built-up area. The mine is rich in sphalerite followed by galena, pyrite and pyrrhotite in different proportions of abundance. Spectral reflectance depends on type of minerals hence need further studies to develop the index according to specific minerals and mines. In the mining regions, the role of temperature, moisture content, vegetation covers and high concentration of pollutants in variation of spectral reflectance are highly important. The developed index would be beneficial for tracing the extent of overburden dumps, tailings and mines at faster rate.
Velocity influence on deformation partitioning along evolving restraining bends
Authors: Elston Hanna , Cooke Michele
Published: March 2022

The evolution of strike-slip restraining bends depends on early fault geometry (e.g., bend angle & stepover distance) and material properties, yet the influence of loading rate on fault system evolution is unknown. Within viscoelastic materials, such as the crust, the relaxation of stresses depends on loading rate. Under faster strain, faults will have shorter recurrence intervals, which reduces the time for stress relaxation during the interseismic period. Because slow strain rates yield greater stress relaxation, the growth of new faults near restraining bends may depend on loading rate. While crustal restraining bends evolve under a range of strain rates, the field expressions of faulting have overprints of early and late deformation, which makes discerning the impact of early strain rate on fault growth difficult. Here, we use scaled physical experiments to directly investigate the impact of strain rate on the evolution of restraining bends. We use wet kaolin as an analog for the crust because it creates sharp faults that remain active even when the loading orientation deviates slightly from the ideal for fault slip. In addition, off-fault stresses within the wet kaolin dissipate over time just as stresses within the crust do via inelastic processes and are tracked with tests on Anton Paar MCR102 rheometer. We directly observe and record the horizontal surface deformation for three experiments with the same initial restraining bend geometry. Computer-controlled stepper motors drive a basal plate at a prescribed velocity to induce faulting within the overlying layer of wet kaolin. The three experimental loading rates of 0.25, 0.5, and 1.0 mm/min scale to crustal loading rates of 2-4, 4-8, and 11-22 mm/yr respectively. We use digital image correlation to calculate incremental displacement and strain field data from overhead photos. Restraining bend experiments with different loading rates produce different deformation histories; slower applied loading produces greater  off-fault deformation and more secondary faults. Furthermore, new oblique-slip faults that grow within the slower loading rate experiments accommodate greater slip than the new faults that grow within the faster loading rate experiments. This suggests that strike-slip fault systems in slow strain rate regions may have slip distributed among several faults whereas slip may localize along a few faults within high strain rate regions. Additionally, the restraining bend geometry becomes more open in the slower loading rate experiments due to greater off-fault deformation. The differences in fault evolution owe to the sensitivity of both the wet kaolin strength and the degree of stress relaxation to strain rate, supported by rheometer tests. The experimental data suggest that loading rate can impact strain partitioning and fault geometry in crustal faults.
The potential impact of predicted climatic change on future slope stability in Ireland
Authors: Cullen Niamh , Bourke Mary
Published: March 2022

Globally landslides are triggered by a myriad of singular and complex causes however the response of the Irish landscape to predicted climate changes are unknown. Some limited data suggest that there may be an increasing trend observed in the frequency of landslides in Ireland, clustered around specific high magnitude rainfall events. Whether this trend is associated with a changing climate trend is unclear. None of the several peer reviewed compendiums that include regional landslide studies and climate have a dedicated contribution on Irelands landscape. We provide a summary of the climate of Ireland from Holocene to future modelled predictions. We present a qualitative assessment of the role of Irish climate and climate change on landslides by identifying specific climate aspects which are important for slope instabilities including precipitation receipts, intensity and variability; the tracks of storms and other rain bearing weather systems and temperature changes. We examine published case studies and an inventory of known landscape response to past weather to consider, qualitatively, the likely response of landslides to predicted future climate trends. We also present rainfall data for three recent landslides events in Ireland and identify areas that require further landslide research. Our review finds that climatic factors which are predicted for Ireland, are cited in the published literature as contributors to slope failures in the Irish landscape. Analysis of rainfall data for the three recent slope failures further support this. Our review suggests that Ireland may see an increase in the frequency of landslide occurrence in the future. Although the data suggests that the majority of failures occur in peat, we highlight a paucity of data for coastal slope failures.  
Using seismograms to investigate earthquake determinism
Authors: Colquhoun Rebecca L. , Hawthorne Jessica C.
Published: March 2022

It is relatively simple to calculate the magnitude of an earthquake after it has happened.  However, it is unclear if an earthquake 'knows' its final magnitude before rupture ends.  We are interested in whether earthquakes are deterministic: whether features of the initial stages of an earthquake make accurate predictions about the earthquakes' final size.

A major piece in the puzzle of determinism was proposed around 15 years ago by Olson and Allen (2005), who found a relationship between the predominant period of the early stages of an earthquake and its final magnitude. However, the results remain controversial, partly because Olsen and Allen (2005) analysed only 71 events. Here we aim to test their prediction in a statistically robust way using many more earthquakes, from a variety of settings. 

We calculate the predominant and average periods for several thousand earthquakes from around the world. Our preliminary results find a deterministic relationship, where both parameters increase with earthquake magnitude, but with a large scatter. They highlight the importance of filtering, and the parameters used to filter, as these have a significant effect on your final result. We are therefore now analysing the spectra of these earthquakes to look for patterns amongst them, and to better understand the physical basis of the predominant and average period calculations.
Pyrogenic carbon in temperate forests - long-lasting impact of historical charcoal production on soils and ecosystems
Authors: Bonhage Alexander , Raab Thomas , Schneider Anna , Raab Alexandra , Ramezany Shaghayegh , Ouimet William
Published: March 2022

Pre- and early industrial charcoal production has left a striking legacy effect on today’s soil landscapes in many forests of Central Europe and the North Eastern USA. Charcoaling in upright standing hearths (also called kilns) resulted in distinct circular micro relief structures, easily identifiable today in the field and on high resolution LiDAR-based digital elevation maps. Soils on these sites are characterized by one or multiple layers of decimetre thick charcoal rich substrate, which makes them Spolic Technosols according to the WRB soil classification. The focus of research on these sites increasingly deals with the difference of their soil physical and chemical properties in relation to unaffected forest soils and the potential implications for changes in vegetation and faunal growth. The controlling factor thereby is the soils large content of charcoal in various particle sizes, ranging from fine dust to large chunks. Studies have repeatedly shown the soils significant increase in total organic- and pyrogenic carbon content. The increase in total carbon stocks is thereby not only caused by pyrogenic carbon, but also by an apparently increased accumulation of non-pyrogenic organic matter. Here we present the latest findings regarding the carbon contents of centennially old charcoal rich technogenic substrates, sampled as part of multiple research projects in Brandenburg, Germany and the Litchfield hills in North-western Connecticut, USA. A focus will be the determination of highly aromatic carbon by the molecular marker Benzene-polycarboxylic acid (BPCA) and its prediction by FTIR-MIR chemometric methods. We discuss the results on forest soil carbon stocks on a site specific to a landscape and regional scale. Furthermore, the potential to use these sites to study the long term effects of charcoal admixture to soils by wildfires or biochar application will be discussed.  
Modeling pesticides in surface runoff: a review of the current status, progress achieved and desirable improvements.
Authors: Centanni Marco , Ricci Giovanni Francesco , De Girolamo Anna Maria , Gentile Francesco
Published: March 2022

The excessive use of pesticides in agriculture poses a threat to water and environmental quality. Under Horizon Europe, considering the priorities of the European Green Deal (EGD), research activities, technological innovation, and investments are needed to contribute to reducing the use of pesticides, fertilizers, and antimicrobials. In this scenario, there is a need to carry out studies on the short and long-term effects of the use of pesticides in the agro-environment and on the effect of mitigation measures. For this purpose, hydrological models are useful tools for the simulation of the fate and transport of pesticides.

Through a critical review, this study aims to: (i) update the status of the use of the hydrological models to simulate pesticides coming from diffuse pollution, (ii) Analyze the spatial and temporal scale of the model applications, (iii) Investigate possible relationships between models and specific pesticides. The ISI papers were selected based on six keywords were used on Scopus: “pesticides, model, watershed, hydrology, water quality, diffuse pollutant”. After removing articles, not in English and articles not related to modeling applications, 37 papers were found and analyzed by constituting a database containing information about the study areas, the pesticides, the model, and the methodology adopted (I.e. warm-up, calibration, and/or validation). Pesticides were classified into three categories: herbicides, fungicides, and insecticides.

Results showed that most of the study areas were localized in Europe (55.5%) followed by North America (22.3%), Asia (13.9%), and South America (8.3%). Soil and Water Assessment Tool was the most commonly used model with a percentage of 45.95%. Regarding the substances investigated, herbicides were the most modeled (71.4%) followed by insecticides (18.2%) and fungicides (10.4%). In particular, among the most commonly modeled herbicides were atrazine, metolachlor, isoproturon, glyphosate, and acetochlor. Among the insecticides, chlorpyrifos and metaldehyde were the substances most frequently modeled. Finally, chlorothalonil and tebuconazole were the most investigated fungicides.

This work will be useful to create an updated guideline to facilitate the water and the landscape managers in selecting a specific hydrological model to assess the transport and fates of pesticides and to simulate the effect of potential mitigation practices.
Verification of sub-seasonal sea surface temperature forecasts for fish farms along the Norwegian coast
Authors: Auestad Henrik , Sørland Silje Lund , Wulff Ole , Kolstad Erik , Sobolowski Stefan
Published: March 2022

Climate variations have the potential to strongly affect aquaculture production. By having access to reliable predictions at extended and long-range lead times, aquaculture can take preventative measures. For instance, variability in water temperature influences the growth and mortality rates of farmed fish. Fish farmers can, if they have reliable forecasts, take action against unfavorable changes in water temperature by moving the sea cages and alter feeding schemes and slaughter times accordingly. In this way, one can minimize production loss, and production can become more sustainable. We present how sub-seasonal forecasts  from ECMWF can be used to provide skilful forecasts at lead times of two to four weeks at various fish farm locations in Norway by including post-processing methods that use on-sight observations as a predictor. Sub-seasonal forecasts are expected to capture grid scale variations and larger-scale phenomena in sea temperature. However, fish farms often lie in complex coastal areas and are therefore prone to local effects like river runoff and smaller scale currents, which are not adequately represented in the sub-seasonal forecast models.  First, we assess the forecast skill for all seasons for the fish farms along the Norwegian coast. The Norwegian fish farms are located in various regions, from off-shore to practically closed-off fjord environments. It is clear that forecast skill is reduced the further in the fjords  the fish farms are located. Post-processing the forecasts by including information on the persistence of water temperatures improves the skill in the fjords, compared to using the ECMWF sub-seasonal forecasts alone. The post-processing model is simple to implement and may enhance water temperature forecast skill in regions that are influenced by local processes. Moreover, this overview of forecast skill may guide forecasters and fish farmers on when, and where, to trust the sub-seasonal forecasts, which is crucial for decision making and can be beneficial for the economy and the industry’s  environmental sustainability.
Impact of tidal activity on the fate of PCB153 in the North Sea
Authors: Mikheeva Elena , Bieser Johannes , Schrum Corinna
Published: March 2022

Over the last century, anthropogenic emissions led to increasing pollution levels in the environment, including coastal areas. Along with hundreds of other persistent organic pollutants (POPs), polychlorinated biphenyls (PCBs) have been introduced into the environment. Due to their long residence time, these pollutants can not only affect the local ecosystem, but they are also able to go on a steady journey to remote areas, such as the polar regions.

In the presented study, we investigate the role of the North Sea for long range transport of PCBs. For northern Europe, the North Sea is the major transit area between land-based emissions and the open ocean (North Atlantic). Here, local hydrodynamic and biogeochemical features determine whether PCBs are deposited or transported into the open ocean. The interplay and seasonality of sedimentation and resuspension processes determine the overall fate of PCBs in the coastal seas. On the one hand, the biological pump transports PCBs to the sediments. On the other hand, turbulence and mixing can lead to the resuspension of previously deposited PCBs. In the North Sea tidal activity strongly impacts not only the local turbulence regime, but consequently also biological production through the resuspension of nutrients.

Here, we investigate the influence of tides on regions with seasonal stratification and permanently mixed areas. For that we used our newly developed PCB model based on the hydrodynamic biogeochemical modelling system GOTM-ECOSMO. The model has been run for 2 different regimes including model runs with and without tidal activity. Simulations are presented exemplarily for one PCB congener – PCB153.

Model results indicate that the seasonality of sedimentation and resuspension has a profound impact on the speciation of PCB in the water column. Removal of PCB from surface waters in summer leads to increased air-sea exchange. Meanwhile, the timing of seasonal resuspension from sediments can lead to peaks of bioavailable PCB species coinciding with primary production peaks leading to increased bio-accumulation.
Information theory solution approach for air-pollution sensors' location-allocation problem
Authors: Fishbain Barak , Mano Ziv , Kendler Shai
Published: March 2022

Urbanization and industrialization processes are accompanied by adverse environmental effects, such as air pollution. The first action in reducing air pollution is the detection of its source(s). This is achievable through monitoring. When deploying a sensor array, one must balance between the array's cost and performance. This optimization problem is known as the location-allocation problem. Here, a new solution approach, which draws its foundation from information theory is presented. The core of the method is air-pollution levels computed by a dispersion model in various meteorological conditions. The sensors are then placed in the locations which information theory identifies as the most uncertain. The method is compared with two other heuristics typically applied for solving the location-allocation problem. In the first, sensors are randomly deployed, in the second, the sensors are placed according to the maximal cumulative pollution levels (i.e., hot spot). For the comparison two simulated scenes were evaluated, one contains point sources and buildings, and the other also contains line sources (i.e., roads). It shows that the Entropy method resulted in a superior sensors' deployment compared to the other two approaches in terms of source apportionment and dense pollution field reconstruction from the sensors' network measurements.
Icebergs slow glacier retreat in a Greenland fjord
Authors: Kajanto Karita , Nisancioglu Kerim
Published: March 2022

The interface between ice and ocean in Greenlandic fjords is the main source of uncertainty in the sea level contribution estimates from the Greenland ice sheet in the coming century. So far, research has shown tight coupling between the glacier and the water column in the fjord, but several main processes remain unclear. The role of icebergs in narrow fjords is poorly understood, and until recently research has focused mostly on the buttressing effect iceberg melange can have on the calving front. However, icebergs provide a substantial fresh water flux in the fjord that can exceed subglacial discharge annually. Iceberg melt is distributed at depth and produced throughout the year, and contributes to the stratification of the fjord, impacting the glacier terminus.

We model the high-silled Ilulissat Icefjord in Western Greenland with the MITgcm ocean model, using IceBerg package to study the effect different iceberg distributions have on this fjord. We compare our results to available XCTD profiles from the fjord. Our results demonstrate that including icebergs is essential to correctly understand the stratification of the fjord. We show that larger icebergs with drafts close to, or deeper than sill depth cool the fjord basin at depth. More specifically, we show that — while the inflowing water looses heat as it passes icebergs — a significant part of this iceberg-induced cooling at depth is due to entrainment of iceberg-cooled intermediate waters into the basin. Furthermore, we demonstrate that icebergs affect glacier melt rate by modifying the melt rate distribution along the glacier face both in shape and magnitude.
Changes in the solubility and potential toxicity of metal(loid)s in soils treated with Technosols
Authors: Aguilar-Garrido Antonio , Romero-Freire Ana , Paniagua-López Mario , Martínez Garzón Francisco Javier , Martín-Peinado Francisco José
Published: March 2022

The influence of six different Technosols on solubility and potential toxicity of metal(loid)s from polluted soils was studied. Technosols were made with a soil affected by residual pollution coming from the Guadiamar Green Corridor and different combinations of three organic wastes [solid olive-mill (T1 and T4), sewage sludge (T2 and T5), and gardening vermicompost (T3 and T6)]. In addition, carbonate-rich material from a peatbog was applied to T1, T2, and T3; while marble sludge was added to T4, T5, and T6; iron-rich sludge (2%) was also applied to all Technosols. The comparison with a non-polluted soil from the study area is also included. Main soil properties (pH, EC, and OC) and solubility of potentially harmful elements (PHEs) in a soil:water extract (1:10) was measured both in Technosols as in soils after two months of incubation period. Potential toxicity was estimated by a germination bioassay with Trifolium pratense L.

The different Technosols showed changes in the solubility of PHEs with significant differences between elements. Cu and Zn strongly reduced the solubility in T3 and T6 in relation to the polluted soil; Cd was reduced in all cases without significant differences between Technosols; and Pb increased in Technosols treated with solid olive-mill (T1 and T4) and sewage sludge (T2 and T5). A significant increase in the solubility of As and Sb was detected in all cases. Likewise, soil treated with Technosols showed differences in solubility of PHEs. Cu and Zn were strongly reduced in the soil treated with T6, and Cd and Pb was reduced in all cases. Arsenic was reduced in all treated soils, although the soluble concentration remained slightly above the values of non-polluted soil. While Sb solubility increased in soils treated with Technosols made with carbonate-rich material from a peatbog (T1, T2, and T3), and maintained at the same level as in polluted soils for soils treated with Technosols made with marble sludge (T4, T5, and T6). These behaviours are mainly related to the increase in calcium carbonate content and the rise in pH in Technosols compared to the polluted soil. The germination bioassay with T. pratense showed very high toxicity (no germination) in soils treated with sewage sludge (T2 and T5), high toxicity (>75% reduction in germination in relation to non-polluted soil) in soils treated with solid olive-mill (T1 and T4), and low toxicity (15% reduction in germination in relation to non-polluted soil) in soils treated with gardening vermicompost (T3 and T6).

Our results indicate that the Technosol composed of gardening vermicompost were the most effective in the reduction of PHEs solubility and toxicity; however, additional studies should be made to assess the increase of mobility in As and Sb after Technosol treatment.
Feedbacks emerging from variable floe size in the Arctic sea ice cover
Authors: Bateson Adam , Feltham Daniel , Schröder David , Ridley Jeff , Frew Rebecca
Published: March 2022

Sea ice is not homogenous and is instead made up of individual pieces of ice that are called floes. Observations show that these floes range in size from just metres to tens of kilometres. Sea ice and climate models have historically assumed a fixed floe size, if there is an explicit representation of floe size at all. There have been several recent efforts to include a treatment of variable floe size within sea ice models. These models have included several processes thought to be important in floe size evolution including break-up of sea ice by waves, lateral melt and growth, welding together of floes, and brittle fracture processes. Floe size can have a direct impact on sea ice evolution via several mechanisms including lateral melt rate, momentum exchange between the sea ice, ocean, and atmosphere, and the ice rheology. Floe size distribution (FSD) models have so far been used within sea ice models to primarily explore the direct impact of floe size on the sea ice cover, and there has been little exploration of the possible resulting feedback processes.

In this study we consider a prognostic approach to modelling the FSD within the CICE sea ice model where the shape of the FSD is an emergent characteristic. We consider results from both standalone sea ice simulations and fully coupled climate simulations. These results are used to explore whether an improved representation of sea ice-ocean and sea ice-atmosphere feedbacks modifies the impact of floe size on the sea ice concentration and thickness over both pan-Arctic and localised scales. We will focus on feedbacks that result from changes to the lateral melt rate, considering in particular whether there is a significant impact from the ice-ocean albedo feedback mechanism. Finally, we will discuss the necessary conditions for there to be significant feedbacks resulting from the inclusion of floe size distribution models in sea ice and climate models. 
Fault friction during simulated seismic slip pulses
Authors: Harbord Christopher , Brantut Nicolas , Spagnuolo Elena , Di Toro Giulio
Published: March 2022

Theoretical studies predict that during earthquake rupture faults slide at non-constant slip velocity, however it is not clear which source time functions are compatible with the high velocity rheology of earthquake faults. Here we present results from high velocity friction experiments with non-constant velocity history, employing a well-known seismic source solution compatible with earthquake source kinematics. The evolution of friction in experiments shows a strong dependence on the applied slip history, and parameters relevant to the energetics of faulting scale with the impulsiveness of the applied slip function. When comparing constitutive models of strength against our experimental results we demonstrate that the evolution of fault strength is directly controlled by the temperature evolution on and off the fault. Flash heating predicts weakening behaviour at short timescales, but at larger timescales strength is better predicted by a viscous creep rheology. We use a steady-state slip pulse to test the compatibility of our strength measurements at imposed slip rate history with the stress predicted from elastodynamic equilibrium. Whilst some compatibility is observed, the strength evolution indicates that slip acceleration and deceleration might be more rapid than that imposed in our experiments. 
Evaluation of albedo schemes in WRF coupled with Noah-MP on the Parlung No. 4 Glacier against in-situ observations
Authors: Liu Lian , Ma Yaoming
Published: March 2022

Meteorological variables (e.g. air temperature (T2), radiation flux and precipitation) determine the evolution of glacier mass and characteristics. Observations of these variables are not available at adequate spatial coverage and temporal / spatial resolution over the Tibetan Plateau. This study focuses on evaluating the performance of albedo parameterization scheme in WRF coupled with Noah-MP in terms of glacio-meteorological variables, by conducting sensitivity experiments on Parlung No. 4 Glacier in ablation season in 2016. The control experiment (CTL) uses the model’s default albedo scheme and unrealistic surface type, while sensitivity experiments apply the default albedo scheme (Sens1) and the modified scheme (Sens2) in ice surface. The key results are as follows. First, all experiments yield similar T2 diurnal patterns to the observations and realistic land-use type considerably reduces model warm bias on the glacier. The RMSE of T2 decreases by 1 °C with an improvement of 37 % by sensitivity experiment estimates. Second, Sens1 keeps rather high albedo value of 0.68 causing net shortwave radiation and net radiation apparent underestimation, while Sens2 holds mean albedo value of 0.35 close to observations contributing to relieve net shortwave radiation and net radiation underestimation. Thirdly, compared with Sens1 estimates, more energy from Sens2 is used to heat ice surface resulting in high ground heat flux (182 W m-2), ice melt and liquid water content increase more quickly and preferentially. Our study confirms the ability of WRF model in reproducing glacio-meteorological variables as long as a reasonable albedo parameterization scheme is applied, and provides a theoretical reference for researchers committed to further improving the surface albedo scheme.
Tidal sea level oscillations in the Sea of Azov
Authors: Korzhenovskaia Arina , Medvedev Igor , Arkhipkin Viktor
Published: March 2022

The Sea of Azov is the most isolated and shallow sea of the World Ocean. Longterm hourly data from 14 coastal tide gauges were used to study the features of tides in the Sea of Azov. Spectral analysis showed well-defined spectral peaks at tidal diurnal and semidiurnal frequencies. Harmonic analysis of tides for individual annual sea level series with consecutive vector averaging over the entire observation period was applied to estimate mean amplitudes and phases of 11 tidal constituents. The amplitude of the major diurnal harmonics is generally greater than the semidiurnal ones. The amplitude of the diurnal radiational constituent S1 changes from 6 cm at the head of the Taganrog Bay to 0.5 cm in the Kerch Strait, while the amplitude of the main semidiurnal gravitational harmonic M2 inside the sea varies from 1.0 cm in the southeastern part of the Sea of Azov, to 0.38 cm at Mysovoye. The tidal form factor within the Sea of Azov changes significantly from the diurnal form in the north to the mixed, mainly semidiurnal near the Kerch Strait. The maximum theoretical tidal range of 19.5 cm were found at the head of the Taganrog Bay, and the lowest was noted in the Kerch Strait, 4.9 cm. The assumption about the predominantly radiational genesis of diurnal tides is confirmed by the seasonal variations of their spectrum. Radiational tides in the Sea of Azov may be initiated by sea breeze winds, which is best expressed in summer.
Statistical approaches to assimilate soil moisture information: Methodology, first assessment and future plans
Authors: Aires Filipe , Weston Peter , De Rosnay Patricia , Fairbairn David
Published: March 2022

Land surfaces are characterized by strong heterogeneities of soil texture, orography, land cover, soil moisture, snow and other variables. These are very challenging to represent accurately in radiative transfer models which have currently a still limited reliability over land. In this study, we compare two statistical modeling approaches: the traditional CDF-matching used routinely in NWP centers (used here as a normalization and as an inversion technique), and the Neural Network (NN) methods. NNs and CDF-matching are compared and combined. Two cases are considered: (1) the more traditional inversion scheme, and (2) the forward modelling that could be attractive for assimilation purposes. It is shown that in the context of ASCAT, the inversion approach seems better suited than the forward modelling but this could be different for another type of observations. It is also shown that it is possible to combine the global model obtained using the NN and the localized information of the LSM offered by the CDF-matching. A first assessment is performed over the USA using in situ soil measurements. Localization strategies for the NN models are introduced. Another necessity for the use of NN in an assimilation framework are estimations of NN uncertainties: this is unfortunately not available so far and we propose several schemes in order to obtain them. Finally, we will present future plans to develop a forward operator for low-frequency microwave channels (SMOS, AMSR-E, SMAP, CIMR) based on a statistical modeling of surface emissivities over continental, snow-ice and sea ice surfaces.