bluuebunny/crossref_metadata_2025 huggingface dataset:
Intermittency in turbulence generated by traditional fractal square grid and spaced fractal square grid
Authors: Ben Mahjoub Otman , Ouadoud Aziz
Published: March 2022

The measurements of the longitudinal velocity were performed in an open-circuit suction wind tunnel installed at the laboratory of the Max-Planck Institute for Dynamics and Self-Organization in Gottingen, using hot wire anemometer at different positions in turbulent flow generated by a traditional fractal square grid (FSG) and by a spaced fractal square grid (SFSG) with similar physical properties have shown that the self-similarity is present. The statistical description of this complex turbulent system was performed using Extended Self Similarity (ESS). We propose a complementary methodology suitable for non-homogeneous turbulence based on the analysis of the energy transfer hierarchy. The signature of the non-homogeneous characteristics of a turbulent field, indicated by nonlocal dynamics, is separated from those usually assigned as being only due to the intermittency. We propose a physical interpretation of the observed scale independence of the relative scaling exponents in such non-homogeneous flows by means of the compensation effect of the energy transfer on the difference between the strong coherent turbulent events and the background less intense turbulence. This procedure is able to distinguish whether the intermittency arises from the small scales or is linked to coherent structures. The practical interest of this type of turbulent excitation concerns several fields of aeronautical and space application and energy or environmental problems of noise reduction of mixers in combustion or for the numerical models of prediction of the dispersion of pollutants in the atmosphere.
Investigating Roles of Baseflow on Water Level in Lake Urmia, Iran
Authors: Moghimi Nezhad Somayeh , Jun Changhyun , Narimani Roya , Byun Jongyun , Baik Jongjin , Lee Jinwook
Published: March 2022

Lake Urmia has experienced a decline in water level by about 40 cm per year in recent decades. Investigating the relationship between baseflow and water level in the lake is essential for better understanding of changes in water level. This study aims to estimate baseflow in the Urmia basin for analyzing the interaction between changes in baseflow and water level in the lake. The Eckhardt filter and mass balance filter (MBF) were considered for baseflow separation at nine stations in the Urmia basin with observation data from 2010 to 2018. It should be noted that each result for baseflow separation was compared in terms of catchment characteristics and climate parameters. Here, the constant filter α and BFImax (the maximum value of the baseflow index (BFI)) were estimated for the Eckhardt filter. Also, electrical conductivity (EC) was used to determine baseflow from the MBF. The relationship between groundwater, baseflow, and water level in the lake was determined by Kendall-Tau coefficients. The result shows that the value of 0.978 for α has the best performance in baseflow estimation from the Eckhardt filter and MBF. The relationship between groundwater, baseflow, and water level in the lake was statistically significant with respect to Kendall-Tau correlations (p ≤ 0.05). The BFI shows that 70% of the runoff at Lake Urmia comes from streamflow, and indicates potential risks of changes in groundwater levels.

 

Keywords: Baseflow Separation, Water Level, Eckhardt Filter, Mass Balance Filter, Baseflow Index, Lake Urmia
A Hydro-Mechanical Coupling Test System for Simulating Rock Masses in High Dam Reservoir Operations 
Authors: Ban Yuxin , Xie Qiang , Fu Xiang , Wu Aiqing
Published: March 2022

A meter-level direct shear test system and a true triaxial test system were designed by placing the traditional test apparatus into sealed cabins subjected to high water pressure. The influences of three-dimensional seepage water pressure on the shear and compression deformation of rock mass in Xiluodu Hydropower Station were studied. The test results showed that the changes in water pressure caused obvious shear deformation of the interlayer dislocation zone and tensile deformation and reduction in the triaxial compression strength of the fractured rock mass. The effect of water pressure on shear displacement and tensile displacement had a hysteresis effect. This was consistent with deformation data collected through field monitoring. The deformation mechanism in the reservoir valley was the coupling of the stress and seepage fields caused by reservoir impoundment. The effective stress was reduced, the mechanical parameters were weakened, and the change of the initial stress field led to the slightly overall shear slip and tensile deformation of the bank slope.
Gap filling in air temperature series by matrix completion methods
Authors: Loucheur Benoît
Published: March 2022

Quality control of meteorological data is an important part of atmospheric analysis and prediction, as missing or erroneous data can have a negative impact on the accuracy of these environmental products.

In Belgium, the Royal Meteorological Institute (RMI) is the national meteorological service that provide weather and climate services based on observations and scientific research. RMI collects and archives meteorological observations in Belgium since the 19th century. Currently, air temperature is monitored in Belgium in about 30 synoptic automatic weather stations (AWS) as well as in 110 manual climatological stations. In the latter stations, a volunteer observer records every morning at 8 o'clock the daily extreme air temperatures. All observations are routinely checked for errors, inconsistencies and missing values by the RMI staff. Misleading data are corrected and gaps are filled by estimations. This quality control tasks require a lot of human intervention. With the forthcoming deployment of low-cost weather stations and the subsequent increase in the volume of data to verify, the process of data quality control and completion should become as automated as much as possible.

In this work, the quality control process is fully automated by using mathematical tools. We present low-rank matrix completion methods (LRMC) that we used to solve the problem of completing missing data in daily minimum and maximum temperature series. We used a machine learning technique called Monte Carlo cross-validation to train our algorithms and then test them in a real case.

Among the matrix completion methods, some are regularised by graphs. In our case, it is then possible to represent the spatial and temporal component via graphs. By manipulating the construction of these graphs, we hope to improve the completion results. We were then able to compare our methods with what is done in the state of the art, such as the inverse distance weighting (IDW) method.

All our experiments were performed with a dataset provided by the RMI, including daily minimum and maximum temperature measurements from 100 stations over the period 2005-2019.
OBS noise reduction using music information retrieval algorithms
Authors: Zali Zahra , Rein Theresa , Krüger Frank , Ohrnberger Matthias , Scherbaum Frank
Published: March 2022

Since the ocean covers 71% of the Earth’s surface, records from ocean bottom seismometers (OBS) are essential for investigating the whole Earth’s structure. However, data from ocean bottom recordings are commonly difficult to analyze due to the high noise level especially on the horizontal components. In addition, signals of seismological interest such as earthquake recordings at teleseismic distances, are masked by the oceanic noises. Therefore, noise reduction of OBS data is an important task required for the analysis of OBS records. Different approaches have been suggested in previous studies to remove noise from vertical components successfully, however, noise reduction on records of horizontal components remained problematic. Here we introduce a method, which is based on harmonic-percussive separation (HPS) algorithms used in Zali et al., (2021) that is able to separate long-lasting narrowband signals from broadband transients in the OBS records. In the context of OBS noise reduction using HPS algorithms, percussive components correspond to earthquake signals and harmonic components correspond to noise signals. OBS noises with narrowband horizontal structures in the short time Fourier transform (STFT) are readily distinguishable from transient, short-duration seismic events with vertical exhibitions in the STFT spectrogram. Through HPS algorithms we try to separate horizontal structures from vertical structures in the STFT spectrograms. Using this method we can reduce OBS noises from both vertical and horizontal components, retrieve clearer broadband earthquake waveforms and increase the earthquake signal to noise ratio. The applicability of the method is checked through tests on synthetic and real data.
A Novel Framework for Simulating Flow and Transport Processes during Bedforms Movement
Authors: Arnon Shai , Teitelbaum Yoni , Shimony Tomer , Cifuentes Edwin , Dallmann Jonathan , Phillips Colin , Packman Aaron , Hansen Scott
Published: March 2022

Most current models for predicting flow and transport processes in bedforms do not consider that sandy streambeds occasionally move. In addition, models that consider bedform movement have used a moving reference frame, typically corresponding to an individual moving bedform. However, the latter approach cannot simulate the accumulation of fine particles at a given location over time as a modeling outcome or any other process influenced by the passage of multiple bedforms. We present a novel simulation framework that models periodic mobile bedforms within a stationary reference frame. This approach is combined with particle tracking to successfully reproduce clay deposition observations in sand beds and the resulting development of a low-conductivity layer near the scour zone. Passage of successive bedforms is represented by varying the shape of the top boundary of the domain. Simulation results successfully reproduce experimental observations of the development of the low-conductivity layer near the scour zone. We found that increased bedform celerity and filtration both lead to a shallower depth of clay deposition and a more compact deposition layer. While increased filtration causes more clay to deposit, increased celerity reduces deposition by flattening hyporheic exchange flow paths. Adopting this novel modeling approach creates opportunities to study realistic situations such as the influence of the passage of bedforms with changing sizes and shapes on flow and transport processes in sandy streams. 
Historical simulation of crop water and land footprints
Authors: Mialyk Oleksandr , Schyns Joep F. , Booij Martijn J.
Published: March 2022

Crop production puts substantial pressure on planetary water and land resources. One way to decrease it is to reduce crop water (WF, m3 t-1) and land footprints (LF, m2 t-1), i.e. have more crop per drop and hectare.  In this study, we simulate WFs and LFs of major crops with a process-based global gridded crop model ACEA during 1990-2019 at 5 x 5 arc minute resolution. Our results reveal regional differences and historical changes in both footprints. Most regions have successfully managed to reduce their WFs and LFs, which drives the global averages down for many crops since 1990. Despite this good news, the total water and land appropriation for crop production have increased worldwide due to the greater crop demand needed to sustain the growing human population. As this may endanger ecosystems and human livelihoods in some regions, it is vital to assess the potential ways of further WF and LF reductions in the future.
Variability of long-term denudation rates measured by 36Cl analyses on a karst levelled surface
Authors: Krklec Kristina , Braucher Regis , Perica Dražen , Domínguez-Villar David
Published: March 2022

Studies of karst denudation rates are great approach to provide an insight to karst landscape development. Traditionally, dissolution of carbonate rocks is considered to be the main process governing carbonate weathering, other processes should not be overlooked. Here we present research done in the North Dalmatian Plain, a carbonate erosive surface located in the Dinaric karst region. Although study site is composed of two different carbonate lithologies having different weathering style, there is no evident lithological impact on the topography of erosive surface. Analyses of 36Cl were performed in ten proximal samples from both lithologies resulted in denudation rates from 14.7 to 22.7 m/Ma. Since no statistical significance was found between samples from different lithologies (all samples belong to a single normal population) having same geomorphological context and climate features, variable denudation rates are attributed to local differences in denudation.  

In the study site there are no large outstanding rock residuals, or deep soil patches, thus in order to maintain the levelled erosive surface local differential denudation rates have to vary with time. We hypothesize that lichens and pedogenic carbonates have a significant role in modulating local differences in denudation rates. Our study shows that even at outcrop scale, differences in local denudation rate can be significant and study of large set of samples is preferred to properly characterize the overall denudation rates of carbonate surfaces. Thus, the long-term denudation rate of the North Dalmatian Plain, including local variability, is 18.55 ±0.79 m/Ma. Despite classical studies on karst terrains assume that dissolution is the main process responsible for denudation of these landscapes, our research highlights the importance of physical weathering in combination with dissolution of carbonates as main controls on the denudation of karst landscapes.

 

Acknowledgements: This research is a part of the research project “Inter-comparison of karst denudation measurement methods” (KADEME) (IP-2018-01-7080) financed by Croatian Science Foundation.
Quantifying the impact of climate processes on trans-Atlantic flight times in observed IAGOS data
Authors: Wright Corwin , Noble Phoebe
Published: March 2022

Commercial aviation is both a major economic sector and has significant effects on the climate system via emissions, and is forecast to continue to grow over coming decades. Significant modelling work over the past decade suggests strongly that climate-dynamical processes can affect flight times, but observational quantification of this is limited, particular in the important transatlantic sector.

Here, we examine flight record data from the In-service Aircraft for a Global Observing System (IAGOS) to quantify the magnitude of how climate processes affect transatlantic flight times between Europe and North America. Using >14 000 individual flight records covering the period 1994-2019, we specifically apply a combination of data-selection and multilinear regression techniques to quantify the effect of the North Atlantic oscillation (NAO), the quasi-biennial oscillation (QBO), the El Nino-Southern Oscillation (ENSO), the decadal solar cycle, and climate change on trans-Atlantic flight times over this period.

We see statistically-significant effects on flight times for all these indices for at least some part of the year, with the magnitude and direction of these effects varying seasonal and by flight direction. These range from the very large, such as changes in flight time of half an hour or more across the NAO cycle for winter flights - to the relatively small, such as changes of just a few minutes across the solar cycle. These results are broadly similar in form to previous modelling studies, but show important quantitative differences with implications for our understanding of how these processes do and will affect aviation in future.
Comparison of bacteriophage MS2, norovirus, rotavirus and adenovirus transport and attenuation in alluvial aquifer media
Authors: Pang Liping , Farkas Kata , Lin Susan , Hewitt Joanne , Premaratne Aruni , Close Murray
Published: March 2022

Contamination of potable groundwater by human enteric viruses pose serious health risks. Our knowledge about virus subsurface transport relies largely on using bacteriophages as surrogates. Relatively few studies have compared enteric viruses, especially norovirus, with phage surrogates regarding their transport behaviour.  Given that bacteriophages and enteric viruses have dissimilar physiochemical properties, differences in their behaviour and interactions in subsurface media and groundwater are possible.

Laboratory column studies were conducted to examine the attenuation and transport of norovirus and MS2 bacteriophage in alluvial sand (d10=0.25 mm), and rotavirus, adenovirus and MS2 in alluvial gravel (d10=2 mm) in 2 mM NaCl (pH 6.6–6.9) at pore velocities of 4.6–5.4 m/day. The experimental data were evaluated using colloid filtration theory and HYDRUS-1D two-site attachment-detachment modelling.

The log10 reduction values, mass recoveries, attachment efficiencies and irreversible deposition rate constants indicated that compared with MS2, norovirus removal was lower in the alluvial sand and the removal of rotavirus and adenovirus was markedly greater in the alluvial gravel. Modelling suggested virus attachment was reversible, and that the rates of virus detachment were faster than the rates of virus attachment, which favoured free virus transport. Hence, continual virus transport through subsurface media poses health risks if viruses are not inactivated, and virus remobilisation could cause contamination events. Thus, virus transport predictions in subsurface media should incorporate virus attachment reversibility.

Some of these observations align with other studies’ findings, but viruses behave very differently in different systems; hence, disparate relationships in other systems have been described, especially in the presence of multivalent cations and organic matter. Our understanding of enteric virus mobility and removal is limited, and data based on bacteriophages may not represent enteric virus behaviour accurately. Thus, further research is needed into enteric virus transport, especially that of norovirus, in different subsurface media under a variety of experimental conditions.
Wave-induced tracer dispersion by ocean surface waves
Authors: Voermans Joey , Babanin Alexander , Kirezci Cagil , Skvortsov Alex , Heil Petra , Pezzi Luciano , Santini Marcelo
Published: March 2022

Material tracers at the ocean surface disperse under the influence of the quasi-random forces that act on the ocean surface. These forces may include ocean turbulence, wind, and surface waves. Currently, wind and ocean turbulence are assumed to be the important drivers of dispersion of the floating tracer particles. Despite some theoretical results and laboratory experiments, the experimental proof of the significant contribution of wave induced dispersion in overall transport of large-scale geophysical systems remains elusive. This is mainly due to a lack of practical observations.

In this study we aim to estimate the contribution of wave-induced dispersion in comparison with conventional mechanisms of dispersion due to ocean turbulence. We do so through the analysis of in-situ observations of surface drifters deployed across the seas and oceans.  The experimental dataset include data from the Global Drifter Program and newly obtained data through cluster deployment of Spotter wave buoys. The results suggest that waves during marine storm conditions may be a critical driver of surface tracer dispersion during the first ten days after the storm and at horizontal length scales up to the order of 10 km. Our results imply that accurate information of wave conditions is required for accurate prediction of tracer dispersion at short to intermediate time and length scales.
An Update on the GGOS Bureau of Networks and Observations
Authors: Pearlman Michael , Behrend Dirk , Craddock Allison , Pavlis Erricos , Saunier Jérôme , Barzaghi Riccardo , Bradshaw Elizabeth , Carabajal Claudia , Thaller Daniela , Maennel Benjamin , Hippenstiel Ryan , Pail Roland , Shum Ck , Brown Nicholas , Blevins Sandra , Sanchez Laura
Published: March 2022

The GGOS Bureau of Networks and Observations works with the IAG Services (IVS, ILRS, IGS, IDS, IGFS, IERS, and PSMSL) to advocate for the expansion and modernization of space geodetic networks for the maintenance and improvement of the reference frame and other applications, as well as for the integration of the techniques.  Of particular interest is the integration of gravimetric and tide gauge networks in view of the forthcoming establishment of a new absolute gravity reference frame and of the International Height Reference System/Frame. New sites are being established following the GGOS concept of “core” and co-location sites, and new technologies are being implemented to enhance performance in data yield as well as accuracy. 

The IAG Committees and Joint Working Groups play an essential role in the Bureau activity. The Standing Committee on Performance Simulations and Architectural Trade-offs (PLATO) uses simulation and analysis techniques to project future network capability and to examine trade-off options. The Committee on Data and Information is working on a strategy for a GGOS metadata system for data products and a more comprehensive long-term plan for an all-inclusive system. The Committee on Satellite Missions is working to enhance communication with the space missions, to advocate for missions that support GGOS goals and to enhance ground systems support. The IERS Working Group on Site Survey and Co-location (also participating in the Bureau) is working to enhance standardization in procedures, outreach and to encourage new survey groups to participate and improve procedures to determine systems’ reference points, a crucial aid in the detection of technique-specific systematic errors.

We will give a brief update on the status and projection of the network infrastructure for the next several years, and the progress and plans of the Committees/Working Groups in their critical role in enhancing data product quality and accessibility to the users, scientists and the general community.   

 
: Collapses in the oceanic Ekman boundary layer
Authors: Shrira Victor , Oloo Joseph
Published: March 2022

Mixing in the uppermost part of the water column is crucial for modelling air-sea interaction, yet it remains poorly understood, especially the processes under strong wind conditions. The Ekman boundary layers are a salient feature of the air-sea interface. In the the Ekman boundary layers the current velocity vectors always rotates, making two components of the basic flow vorticity comparable and, thus, the boundary layer three dimensional. Linear instabilities of the homogeneous steady Ekman layers were examined and  found to occur for sufficiently large turbulent Reynolds numbers.  Here, we derive a model of  nonlinear instabilities of 3d Ekman layer  in deep ocean taking into account also a possible weak stratification of the boundary layer caused by air entrainment due to wave breaking or solar heating. The model exploits the observation that the corresponding linearized boundary value problem  always supports a “vorticity wave” mode which is often decaying. Employing an asymptotic procedure utilizing smallness of the boundary layer thickness to the characteristic wavelength of perturbations  scaled as  inverse Reynolds number squared we derive a novel nonlinear evolution equation with a pseudo-differential dispersion.  We take into  account viscosity and weak stratification  in the boundary layer. Within the framework of this equation a  wide class of initial conditions, which we a priori specify, leads to `collapses’ of localized perturbations, that is an initial perturbation becomes more and more localised and its amplitude becomes infinite in finite time forming a point singularity. We derived a self-similar solution describing these collapses. The mechanism of collapse is essentially nonlinear. A new insight into linear instabilities has been also  obtained.  The collapses are expected to result in intense mixing and even temporary destruction of the boundary layer.
Drivers and distribution of global ocean heat uptake over the last half century
Authors: Huguenin Maurice , Holmes Ryan , England Matthew
Published: March 2022

Since the 1970s, the ocean has absorbed almost all of the additional energy in the Earth system due to greenhouse warming. However, our knowledge of where ocean heat uptake (OHU) has occurred and where this heat is stored today is limited by sparse observations. Here, we use a global ocean-sea ice model forced by observationally constrained atmospheric fields to conduct hindcast simulations that are initialised from an equilibrated control simulation that improves on commonly used spin-up approaches. The hindcast with full interannual forcing captures the observed global ocean heat content evolution better than most previous ocean-sea ice model simulations. Applying trends in only surface winds or thermal properties reveals that each can explain ∼50% of the total ocean warming signal. These contributions, when restricted to the Southern Ocean, account for nearly all of the global OHU of 5.4 × 1021 J year-1. Integrated over the Southern Ocean, the sensible heat flux drives 75% more OHU than the longwave radiative flux in the simulation with only surface wind trends, while it is the opposite in the simulation with only trends in thermal properties. Almost 50% of the additional Southern Ocean-sourced heat signal is exported into the Atlantic Ocean where two-thirds of this added heat is then lost to the atmosphere.
Melting glaciers as a potential source of methylmercury in the first chains of Antarctic pelagic food web (Admiralty Bay)
Authors: Saniewska Dominika , Korejwo Ewa , Saniewski Michał , Bałazy Piotr
Published: March 2022

Recent studies have found that the Antarctic is a sink for mercury (Hg). The unique atmospheric mercury depletion events stimulate Hg deposition and its incorporation in the marine food web. This metal can also be sequestrate in the snowpack along all Antarctica. Therefore, this region should be considered as a giant cold trap of mercury. The ice sheet in West Antarctica is now in a state of dynamical imbalance and the rate of ice loss is five times greater than was thought. Therefore melting ice sheet and glaciers should be considered as an important secondary mercury source for the Antarctic, which can result in an increase of Hg concentration in marine biota. The aim of the research was to identify methylmercury (MeHg) sources in Antarctica and determine their potential for accumulation in the marine trophic chain. Sampling was conducted in the Admiralty Bay in December 2018. As part of the research marine samples (water, suspended particulate matter, phyto- and zooplankton) were collected. Total mercury, methylmercury and labile Hg concentration were determined in the samples.

Mean MeHg concentration in Admiralty Bay was 15 pg/dm3, and the highest values were measured in the vicinity of melting glaciers. MeHg in water occurred mainly in dissolved form (>70%), thus promoting the accumulation of Hg for plankton. Higher values of MeHg concentration were measured in phytoplankton (mean 204 pg/dm3) than in zooplankton (mean 143 pg/dm3). Different factors influence the accumulation of MeHg in both groups of plankton.

This study has been performed within the framework of a National Science Center projects No. 2019/33/B/ST10/00290 and  No. 2017/27/N/ST10/02230.
Laboratory simulation of gas hydrate formation at ice surfaces in Earth atmosphere
Authors: Durham Brian , Pfrang Christian , Hassanpouryouzband Aliakbar
Published: March 2022

For fourteen days in November the world’s attention turned to the rise in atmospheric GHG levels, on this occasion with a special focus on methane (Nature 25 August 2021).  Methane had previously been the subject of a study on gas hydrate formation and, while noting the relevance of this property to climate change modelling, the authors in that case wrote: `Curiously, gas hydrates seem to defy intuition about hydrophobic compounds, as the concentration of a nonpolar gas in the solid hydrate lattice is more than two orders of magnitude higher than the solubility of such a gas in liquid water’ (Walsh et al 2008 `Microsecond Simulations of Spontaneous Methane Hydrate Nucleation and Growth' ). 

The term `non-polar’ applies to the gases of Earth’s atmosphere - so does the same concentration paradox apply to the inclusion of each of these species in atmospheric ice? For CO2, curves published by the University of Lille quantify hydrate formation across a range of partial pressures, and are projected to a zero pressure origin, thereby embracing the partial pressure of the gas in Earth atmosphere (Chazallon and Pirim (2018) `Selectivity and CO2 capture efficiency in CO2-N2 clathrate hydrates investigated by in-situ Raman spectroscopy', Figs 4A and 4B).  Moreover, in the presence of ice phase at -12°C our own results have shown that, from a CO2+N2 mixture, more than 90% of CO2 goes into the ice/hydrate phase, which is three times higher that at 10°C (Hassanpouryouzband et al 2019 `Geological CO2 capture and storage with flue gas hydrate formation in frozen and unfrozen sediments').

We simulate hydrate formation in the Earth's atmosphere using laboratory apparatus designed to quantify the depletion of GHGs (including water vapour) from a chilled airstream at atmospheric pressure across a range of temperatures, followed by analysis of the condensate. 
Confronting the water potential information gap
Authors: Novick Kimberly , Ficklin Darren , Baldocchi Dennis , Davis Kenneth , Ghezzehei Teamrat , Konings Alexandra , MacBean Natasha , Raoult Nina , Scott Russell , Shi Yuning , Sulman Benjamin , Wood Jeffrey
Published: March 2022

Water potential directly controls the function of leaves, roots and microbes, and water potential gradients drive water flows throughout the soil-plant-atmosphere continuum. Notwithstanding its clear relevance for many ecosystem processes, soil water potential is rarely measured in-situ, and plant water potential observations are generally discrete, sparse, and not yet aggregated into accessible databases. These gaps limit our conceptual understanding of biophysical responses to moisture stress and inject large uncertainty into hydrologic and land surface models. Here, we outline the conceptual and predictive gains that could be made with more continuous and discoverable observations of water potential in soils and plants. We discuss improvements to sensor technologies that facilitate in situ characterization of water potential, as well as strategies for building new networks that aggregate water potential data across sites. We end by highlighting novel opportunities for linking more representative site-level observations of water potential to remotely-sensed proxies. Together, these considerations offer a roadmap for clearer links between ecohydrological processes and the water potential gradients that have the ‘potential’ to substantially reduce conceptual and modeling uncertainties.
Mechanism of Faster CH4 Bubble Growth Under Surface Waves in Muddy Aquatic Sediments: Effects of Wave Amplitude, Period and Water Depth
Authors: Painuly Abhishek , Katsman Regina
Published: March 2022

Methane (CH4) transport from organic-rich fine-grained shallow aquatic (muddy) sediments to water column is mediated dominantly by discrete bubbles, which is an important natural source of greenhouse CH4. Lifespan of CH4 bubbles within sediment constitutes two successive stages: growth from nucleation up to mature size and its buoyant ascent towards sediment - water interface. Bubbles often experience oscillating overburden load due to passage of winds/storm induced short period surface waves or long period tides, which can potentially affect both stages of bubble’s lifespan. However, little is known about the wave effects over bubble growth phase. In present work this subject is investigated using a numerical single-bubble mechanical/reaction–transport model and the effects of different parameters of the wave loading (amplitude and period) and of the water depth, over the bubble growth pattern and its specific characteristics in sediments, is quantified. It is found that bubbles induce early sediment fracturing in presence of waves, attributed to low overburden load appearing at wave troughs. Bubbles in shallow depth rapidly grow at wave troughs by inducing multiple intense fracturing events, however, this ability decrease with an increasing water depth (because of a slower solute influx). In presence of waves, bubbles mature in lesser time, whose contrast from the no wave case is controlled by the ratio of wave amplitude to equilibrium water depth. Due to higher frequency of occurrence of wave troughs for shorter-period waves, they accelerate the bubble growth more compared to the long-period waves. Overall, conducted modelling suggests that fastest bubble growth can be predicted under higher amplitude short period waves travelling in shallow water. We further infer that accelerated bubble growth, along with subsequent wave-induced ascent can sufficiently shorten the bubble’s total lifespan in sediment, which explains the observed episodic in-situ ebullitions correlated with wind-or storm-induced waves.
Using a tiny rainfall simulator to investigate the impact of soil internal forces on long-term location fertilization Loess soil loss
Authors: Du Wei , Hu Liang , Hu Feinan , Lv Jialong
Published: March 2022

Soil water erosion and the resulting nutrient loss (such as phosphorus loss) and other ecological and environmental issues are still important obstacles that challenge the quality and efficiency of agricultural production and sustainable development in the Loess Plateau of China. Soil water erosion is affected by external environmental factors such as rainfall intensity and slope. Measures such as increasing vegetation coverage and reducing slope can play an external role in preventing and controlling soil and nutrient loss. At present, based on the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE), Chinese scholars have established regional soil loss models such as the erosion prediction model for small watersheds in loess hilly and gully regions, which play a very important role in soil erosion prediction and prevention. However, all the above models are empirical and lack consideration of the mechanism of soil erosion. In this study, using a self-designed needle drop micro-rainfall model device combined with the basic principles of soil electrochemistry, the effect of the interaction between soil particles on the loss of soil and its nutrients during long-term fertilization was studied on a mesoscopic scale. We found that: (1) the total phosphorus content of loess soil under long-term phosphate fertilizer treatment was 2.46 times that of non-phosphorus treatment, but its surface potential, surface charge density, surface electric field intensity, specific surface area, and number of surface charges were all lower than those of non-phosphorus treatment; (2) loess soils with varying levels of phosphorus exhibit a trend in which the loss of soil particles and phosphorus increases as the surface potential of the soil particles, and there is a linear positive correlation between the cumulative loss of particulate phosphorus and the cumulative loss of soil particles; (3) the net force (the combined force of van der Waals force, hydration repulsion force, and electrostatic repulsion force) between soil particles with different phosphorus levels at a given electrolyte concentration is all expressed as repulsive force and changes with the decrease of electrolyte concentration; (4) due to the relatively high surface potential of low-phosphorus loess soil, the electrostatic repulsion between soil particles is greater, resulting in poor stability of soil aggregates and more cumulative loss of soil particles and attached phosphorus. This study clarified the relationship between soil surface properties, soil internal forces, soil particles and nutrient element loss characteristics under long-term fertilization treatment, and provided new ideas for soil loss prevention and control and environmental risk assessment during long-term fertilization.
The Deep Roots of Geology: Tectonic History of Australia as expressed by Mantle Anisotropy 
Authors: Eakin Caroline
Published: March 2022

Australia is an old stable continent with a rich geological history. Limitations in sub-surface seismic imaging below the Moho, however, mean that is unclear to what extent, and to what depth, this rich geological history is expressed in the mantle. Studies of seismic anisotropy, which reflect past/present mantle deformation, can offer potential insights. One commonly employed technique is shear wave splitting, in which the wave polarisation is measured. New such results from seismic arrays deployed across central Australia, reveal a pattern of anisotropy that is consistent with past deformation of the Australian lithosphere that has been preserved for over 300 million years. Another informative technique is to use scattered surface waves, called Quasi-Love waves, that can detect lateral gradients in seismic anisotropy. The first such study for the region finds that scatterers are preferentially located near (1) the passive continental margins, and (2) the boundaries of major geological provinces within Australia. Such lateral anisotropic gradients within the continental interior imply pervasive fossilized lithospheric anisotropy, on a scale that mirrors the crustal geology at the surface. Beneath the continental margins, lateral anisotropic gradients may indicate small-scale dynamic processes in the asthenosphere, such as edge-drive convection, that are tied to the margins.
Effect of surfactant concentration on the decomposition rate of alkaline activated persulfate
Authors: Abolhosseini Pejman , Robert Thomas , Martel Richard , Kaur Brar Satinder
Published: March 2022

Hydrocarbon contamination is among the most frequent sources of soil and water environmental impacts. Many remediation methods have been implemented to clean up the contaminated environment so far. In-Situ Chemical Oxidation has attracted attention as it has shown efficiency in contaminants removal and cost-effectivity. In addition, soil washing by surfactant foam has been recently proven as a promising method. The combination of these two methods can take the advantage of oxidation while eliminating the challenges regarding the poor distribution of treatment fluid in a heterogeneous porous media. The ultimate goal of this study is to use surfactant foam for delivering oxidant (persulfate) through diesel-contaminated soil in permafrost. However, the interaction between the surfactant and the oxidant needs to be studied first. A better understanding of the impact of surfactants and oxidants on each other can lead to an optimized process. At the first stage of this study, different concentrations of surfactant solutions (sodium dodecyl sulfate: cocamidopropyl betaine in a mass ratio of 1:1) were mixed with a constant persulfate concentration activated with alkali, in absence of hydrocarbon. The preliminary results showed that the initial concentration of the oxidant has no significant effect on its decomposition rate. Also, as the concentration of surfactant was increased above the Critical Micellar Concentration (CMC), the persulfate decomposition rate decreased, likely due to the formation of micelles. However, as the micelles started to be destroyed, the decomposition rate of the oxidant increased gradually and the highest rate was observed when the concentration of surfactant was close to the CMC. When no micelle was left in the solution, the decomposition rate of the oxidant waned to a low value. Thus, coupling the surfactant and the oxidant can be effective for the degradation of hydrocarbon contaminants. Micelles bring part of the hydrocarbon into the aqueous phase and then the micelles are destroyed by the oxidant that can also degrade the hydrocarbon effectively over time.
Multi-annual InSAR solution of vertical land motion in 2021 lethal building collapse site in Miami 
Authors: Yu Xiao , Hu Xie
Published: March 2022

NOAA reported that the sea level has risen by 203-228 mm since 1880 and the rates accelerated to 3.556 mm/year during 2006-2015. Coastal regions, home to about half of the world’s population (~3 billion), are subject to erosion from wind and waves and subsidence from natural compaction and artificial explication of subsurface resources, and are at high risks of floods from accidental storms and inundations from prolonged sea level rise. The vertical land motion (VLM) directly determines the relative sea level rise. To be specific, locally upward VLM can help alleviate the risks while locally downward VLM may hasten the arrival of inundation. Therefore, monitoring coastal VLM is fundamental in coastal resilience and hazard mitigation. 

One 12-floor building, Champlain Towers South, in the Miami suburb of Surfside collapsed catastrophically and claimed 98 lives on June 24th, 2021. No confident conclusion has been drawn on the cause of the collapse, but it might be related to multiple processes from the ground floor pool deck instability, concrete damage, and land subsidence.

Subsidence has been noted in populous Surfside since 1990s. However, we still lack a detailed mapping of the contemporary coastal subsidence. Here we focus on multi-source Synthetic Aperture Radar (SAR) datasets from C-band Sentinel-1 and X-band TerraSAR-X satellite imagery.

We use the time-series SAR interferometry of ascending Sentinel-1 path 48 to extract the VLM from 2015 to 2021. A comparatively stable GPS station ZMA1 obtained from the Nevada Geodetic Laboratory acts as the reference site to calibrate InSAR results. Long-wavelength atmospheric phase screen and orbit errors are approximated by the low-order polynomial fitting. The average subsidence rates derived from stacking can help reduce the temporarily high-frequency noise. A comparison with the GPS network solution can help verify InSAR measurements. Beyond that, we will also rely on high-resolution X-band TerraSAR-X data (Path 36, strip_014) to elaborate VLM details in the building clusters. Beyond that, NOAA reported that the relative sea level increase in Florida is 2.97 mm/year from 1931 to 2020, i.e., >0.3 m in one century. The 2019 Unified Sea Level Rise Projection in Southeast Florida predicted that the sea level in 2024 will rise by 254 to 432 mm in Florida compared to the level in 2000. We aim to extract the high-accuracy VLM to provide scientific evidence for more safe urban planning and effective adaptation strategies in coastal cities, for an ultimate goal of coastal resilience during global climate change.
Quantification of Predictive Uncertainty for Reversible Degradation of Diclofenac under Biotic, Denitrifying Redox Conditions
Authors: Ceresa Laura , Guadagnini Alberto , Porta Giovanni , Riva Monica , Sánchez-Vila Xavier , Rodriguez-Escales Paula
Published: March 2022

Drinking water resources and the associated delicate aquatic ecosystem are threatened by several contaminants. Diclofenac poses major concerns due to its persistent nature and frequent detection in groundwater. Despite some evidences of its biodegradability under reducing conditions, Diclofenac attenuation is often interpreted through geochemical models which are too simplified, thus potentially biasing the extent of its degradation. In this context, we suggest a modeling framework based on the conceptualization of the molecular mechanisms of Diclofenac biodegradation which we then embed in a stochastic context. The latter enables one to quantify predictive uncertainty. Biotic and denitrifying reference conditions are taken from a set of available batch experiments that evidence the occurrence of a reversible degradation pathway. Our model is subject to stochastic calibration through Acceptance-Rejection Sampling. The associated results fully embed uncertainty quantification and support the recalcitrance of Diclofenac in groundwater. Our results show that data scarcity and/or redundant model parametrization seem to deteriorate the quality of some parameter estimates, a feature that appears to be associated with the degree of information contained in the available dataset, which is addressed towards specific model processes. We then address the issue by reducing the complexity of the model and embed the resulting formulations within a multi-model context. The resulting models are calibrated through a Maximum Likelihood approach assisted by modern sensitivity analyses techniques, the performance of each candidate model being then assessed (in a relative sense) through classic model identification criteria. Our results suggest that an optimal trade-off in terms of model complexity (i.e., level of parametrization) given data availability can be assessed to satisfactorily interpret the system dynamics.
25 years of the IPCC Data Distribution Centre at the German Climate Computing Center (DKRZ)
Authors: Stockhause Martina , Lautenschlager Michael
Published: March 2022

The Data Distribution Centre (DDC) of the Intergovernmental Panel on Climate Change (IPCC) celebrates its 25th anniversary in 2022. DKRZ is the last remaining founding member among the DDC Partners. The contribution looks back on the past 25 years of the DDC at DKRZ from its establishment to the present. It shows which the milestones have been introduced in the areas of data management and data standardization, e.g. 

the NetCDF/CF data standard,

the DataCite data DOI assignment enabling data citation,  

the data preservation and stewardship standards of the World Data System (WDS), 

the Earth System Grid Federation (ESGF) as data infrastructure standard, or 

the IPCC FAIR Guidelines for the current 6th Assessment Report (AR6). 

In addition to the continuous effort to adopt new standards and curate the data holdings, current challenges - technical and organizational - and possible future directions are discussed. The most difficult of the challenges remains the long-term strategy for sustainable DDC services as a part of an increasingly interoperable data service environment, which is technically described in the FAIR digital object framework and which is contentwise guided by the UN Sustainable Development Goal 13 on climate action. 

(http://ipcc-data.org; http://ipcc.wdc-climate.de)