bluuebunny/crossref_metadata_2025 huggingface dataset:
Korteweg-de Vries equation family in the theory of nonlinear internal waves
Authors: Talipova Tatiana , Pelinovsky Efim
Published: March 2022

As it is known, the canonical Korteweg-de Vries equation is applied to describe nonlinear long internal waves in the first approximation on parameters of nonlinearity and dispersion. To compare with surface gravity waves, the coefficient of quadratic nonlinearity can have either sign and to be zero. In this case, the asymptotic procedure should take into account higher terms of nonlinearity. Generalized Korteweg-de Vries equation called the Gardner equation is now a popular model to analyze nonlinear internal waves in the ocean with complicated density and shear flow stratification. If the density stratification is almost linear, the number of nonlinear terms is increased. The family of the Korteweg-de Vries-like equations for internal waves in the form ut+ [F(u)]x + uxxx = 0 is discussed in this presentation. In leading order the nonlinear term is F(u) ~ qub  with b > 0. The steady-state travelling solitary waves is analyzed.

            For q > 0 and b > 1 the analysis re-confirmed that all travelling solitons have “light” exponentially decaying tails and propagate to the right. If q < 0 and b < 1, the travelling solitons (so called compactons) have a compact support (and thus vanishing tails) and propagate to the left. For more complicated F(u) and b > 1 (e.g., the Gardner equation and higher-order generalizations) standing algebraic solitons with “heavy” power-law tails may appear. If the leading term of F(u) is negative, the set of solutions may include wide or table-top solitons (similar to the solutions of the Gardner equation), including algebraic solitons and compactons with any of the three types of tails. The solutions usually have a single-hump structure but if F(u) represents a higher-order polynomial, the generalized KdV equation may support multi-humped pyramidal solitons.

Study is supported by RFBR Grant No 21-55-15008.
Developing an operational forecast system as byproduct of scientific research - an example for inland floods at the German North Sea coast
Authors: Lenz Jonas , Jackisch Conrad , Burkhard Kremena , Schibalski Anett , Schröder-Esselbach Boris
Published: March 2022

Within the research project RUINS we assess the risk of inland floods of the Krummhörn region at the German North Sea coast. One third of this area lies below mean sea level, which demands to drain inland water during low tides by sluicing or otherwise by pumping. If, at any point in time, the drainage demand exceeds the drainage capacity, the available storage in polders and canals will be filled. Once this storage capacity is exceeded inland floods will occur.

Previous risk assessment for such inland floods assumed a constant daily drainage capacity, which results from the installed pump capacity. We analysed process data provided by the operator of the drainage system (1. Entwässerungsverband Emden) at sub hourly resolution. The recorded water levels within the canal system showed that under current conditions the maximum areal drainage capacity is usually limited by the flow capacity within the canal network. The capacity of the pumps is dependend on the gradient from canal to North Sea water level.

Under increased tidal water levels in the North Sea (e.g. storm flood situations) the pumping capacity can drop below the canal flow capacity. In consequence the areal drainage capacity is variable and can become much smaller than the constant daily drainage capacity assumed in previous studies. Due to the predicted increase in mean sea level with climate change the area might face an increased risk of inland floods despite a situation of insignificant changes in predicted rainfall patterns.

Instead of costly infrastructural improvements, we propose a forecast system i) to optimise the drainage capacity in foresight of short term extreme situations and ii) to enable preparation for inland floodings. The proposed system includes the inherent uncertainty of the analysed processes and predicts the magnitude of upcoming inland floods. Currently, we use synthetic data as drivers, but these shall be exchanged by available weather and tide level predictions. The forecast system is realized as online accessible app, providing an easy usable and understandable access point for the operator and the interested public.
Cloud regulation of inter-hemispheric albedo symmetry
Authors: Bender Frida
Published: March 2022

Despite differences in land distribution, and aerosol amount, the Northern and Southern hemispheres have been found to reflect almost exactly the same amount of incoming shortwave radiation. This indicates that clouds compensate for the asymmetry in clear-sky reflection, and make the system maintain an inter-hemispheric albedo symmetry. 

In the mean state, retrievals from satellite-borne CERES measurements suggest that mid-latitude clouds are both in amount and reflectivity contributing to this compensation, together with sub-tropical cloud amount, that is also greater in the Northern hemisphere. Composites of instances with high asymmetry in either direction indicate that the variability in albedo symmetry is driven by variation in tropical and subtropical cloudiness, with patterns in agreement with non-neutral phases of ENSO. 

CMIP6 models are found to typically overestimate the variability in inter-hemispheric asymmetry, and underestimate the degree of symmetry, compared to observations. The bias in models is largely driven by biases in mid-latitude reflected shortwave radiation. Mid-latitude clouds are also found to play a significant role in model albedo symmetry response to strong forcing: models with large loss of mid- and high-latitude clouds in the Southern hemisphere restore the initial asymmetry, due to relative Northern hemisphere darkening, produced in the models in response to abrupt 4xCO2 forcing and subsequent warming.

Here we discuss albedo distribution and variability in satellite-derived products, and across model generations, pointing at inter-hemispheric symmetry as a useful model diagnostic, and as indicator of cloud feedback mechanisms.
Exploitation of SHARAD data from a passive sounding perspective: a preliminary analysis 
Authors: Gerekos Christopher , Steinbrügge Gregor , Donini Elena , Romero-Wolf Andrew
Published: March 2022

Passive radar sounding has been proposed as a low-cost, low-risk way to enrich the scientific return of planetary radar sounders, especially in the vicinity of bright radio sources such as Jupiter [Romero-Wolf et al. (2015), Icarus, 248:463-477], whose moons will be studied by radar sounders in the late 2020's and 2030's. To predict what passive radargrams may look like as a function of parameters such as the noise source spectrum and the surface/subsurface roughness, analytical and empirical models have been proposed in the literature [Schroeder et al. (2016), PSS, 134:52-60], and proof-of-concept hardware has been tested on Earth [Peters et al. (2018), TGRS, 56(12) 7338-7349]. To cement our understanding of passive sounding, we searched for traces of passively-acquired radar echoes in existing SHARAD radargrams. Such signals can be uncovered if the incoming noise was captured in one acquisition and its reflection by surface or subsurface features in the next one. Cross-correlating the two uncompressed rangelines could then reveal possible present Martian features using only the signals of opportunity. We started from the engineering parameters of SHARAD, such as its orbit, Rx window length, and PRF, to work out all the geometric configurations where Jovian emissions and their reflection from the surface could have been intercepted if such emissions were present. We made the assumption that waves must be specularly-reflected off the surface of Mars at a given angle, and looked for the angles at which the delay of the reflected noise matches the PRI of SHARAD. We have determined that, for the range of altitudes SHARAD operates at, the (Jupiter-Mars, Mars-SHARAD) angle must lie between 35° and 52°. Based on Friis-like arguments, we believe the SNR of such signals could reach 10 dB in the case of a smooth surface such as Elysium Planitia. We then cross-correlated this database of SHARAD radargrams with that of a model of Jovian noise occurrence at Mars using ExPRES [Hess et al. (2008), GRL, 35.13], and extracted a list of potential candidates. Preliminary analysis of these candidates shows that some of them may indeed contain passively-acquired signals that may be exploited scientifically. We have additionally conducted passive Stratton-Chu simulations [Gerekos et al. (2019), TGRS, 58(4) 2250-2265] of these cases to support interpretation.
Using Operational Earthquake Forecasting Tool for Decision Making: A Synthetic Case Study 
Authors: Huang Chen , Bolin Håkan , Refsum Vetle , Meslem Abdelghani
Published: March 2022

Operational earthquake forecasting (OEF) provides timely information about the time-dependent earthquake probabilities, which facilitates resilience-oriented decision-making. This study utilized the tools developed within the TURNkey (Towards more Earthquake-Resilient Urban Societies through a Multi-Sensor-Based Information System enabling Earthquake Forecasting, Early Warning and Rapid Response Actions) project funded by the European Union’s Horizon 2020 research and innovation programme to demonstrate the benefits of OEF to the decision support system.  The considered tools are developed based on the state-of-the-art knowledge about seismology and earthquake engineering, involving the Bayesian spatiotemporal epidemic-type aftershock sequence (ETAS) forecasting model, the time-dependent probabilistic seismic hazard assessment, the SELENA (SEimic Loss EstimatioN using a logic tree Approach) risk analysis, cost-benefit analysis and the multi-criteria decision-making methodology. Moreover, the tools are connected to the dense seismograph network developed also within the TURNkey project and, thus, it is capable of real-time updating the forecasting based on the latest earthquake information and observations (e.g., earthquake catalogue). Through a case study in a synthetic city, this study first shows that the changes in the earthquake probabilities can be used as an indicator to inform the authorities or property owners about the heightened seismicity, based on which the decision-maker can, for example, issue a warning of the potential seismic hazard. Moreover, this study illustrates that OEF together with the risk and loss analysis provides the decision-maker with a better picture of the potential seismic impact on the physical vulnerabilities (e.g., damage, economic loss, functionality) and social vulnerabilities (e.g., casualty and required shelters). Finally, given the decision-maker’s preference, this study shows how the hazard and risk results are used to help the decision-maker to identify the optimal action based on cost-beneficial class and the optimality value computed based on the multi-criteria decision-making methodology.
Instabilities and Turbulence in Two-Dimensional Magnetohydrodynamics
Authors: Tessier Jonathan , Poulin Francis J. , Hughes David W.
Published: March 2022

The solar tachocline is a dynamically important thin region in the Sun, located between the convective and radiative zones and characterised by strong shear in both the radial and latitudinal directions. Furthermore, it is believed to play a key role in the solar dynamo process through the shearing of a poloidal field into a stronger toroidal component. Motivated by the dynamics of the tachocline we have conducted a detailed numerical exploration of the dynamics of sheared MHD turbulence.

Specifically, we have implemented a parallelized numerical model using the "shenfun" Python library to solve the nonlinear two-dimensional Magnetohydrodynamic (MHD) equations to study the dynamics of unstable jets and turbulence in astrophysical plasmas. In particular, we study details of how the jet becomes unstable and the resulting cascade of energy in the case of MHD turbulence. In addition to studying the evolution of the physical quantities, we also investigate the evolution of the spectral slopes and spectral fluxes. As has been found in previous studies of MHD turbulence, a very weak large-scale magnetic field can play a key dynamical role through its amplification on small scales. For extremely weak fields, the behaviour is essentially hydrodynamic. However, once the field is dynamic, the nature of the resulting MHD solution is very different. We are able to classify the various flows and quantify the nature of the solutions in the two regimes.
Simulation study of water balance and solute transport in agricultural soil in Haouz region, Morocco
Authors: el moussaoui el houcine , Moumni Aicha , Lahrouni Abderrahman
Published: March 2022

The hydraulic basin of Tensift is a concrete example of diversification and increase of pollutants discharged without treatment into the natural environment. This issue strongly threatens the water resources of this basin and makes it extremely sensitive to pollution, including groundwater that is a strategic resource in this area. The purpose of this study is to simulate two phenomena, which are hydrodynamic operation and leaching of solute in the conditions of the Haouz region.

The study was conducted on the R3 perimeter. It is an irrigated agricultural sector in the region of Sidi Rahal, about 40 km east of Marrakech city, Morocco. To carry out this work, the VS2DI model was chosen for the following reasons: accessibility, reliability, and free of charge. This model popularly uses Cartesian or radial coordinates and allows solving the Richards equation to model the water transfer and the convection-dispersion equation to model the transport of solutes and heat in a porous and variably saturated medium. Our research team collects the data needed for the VS2DI model during the agricultural season of 2002/2003. The collected data is related to climatic conditions, soil, plant, and cultivation practice. 

The results obtained showed that for the scenarios studied the moisture of the upper layers increases and tends towards saturation depending on the value of the flux imposed on the surface. However, the deep layers remain unsaturated for a long time because of drainage. Thus, after one day and for a flux of 12 cm/d, the first 40cm of the soil is saturated. For the 4 cm/d flow, the saturation, during 24h, did not exceed the 30 cm depth. Knowing that these upper layers are subject to strong thermal gradients and root extractions. On the other hand, in the simulations of solute transport, we try to describe the evolution of the degree of contamination of a layer after a period of one day as a function of the imposed water flow and the concentration of solute on the surface.

The results obtained by these simulations show that at 20cm depth the solute concentration starts to change only after a period of 4h and that the rate of change of the concentration is almost linear with time for each given water flux. Beyond 4h, the rate of change of the solute at this depth decreases in a non-linear way with the increase of the water flux imposed on the surface. From these first tests, we can say that this model performs water balances in an acceptable way. It has also been proved that the saturation rate of the soil increases with the increase of the imposed flux and of the moisture of this layer. Finally, it was found that the rate of change of the solute at a given depth decreases non-linearly with the imposed water flux at the surface.
Evaluation of reanalysis soil moisture products using Cosmic Ray Neutron Sensor observations across the globe
Authors: Zheng Yanchen , Coxon Gemma , Woods Ross , Power Daniel , Rosolem Rafael
Published: March 2022

Soil moisture influences many physical processes in hydrology, meteorology, and agriculture, such as evapotranspiration, infiltration, runoff generation, drought development, crop growth, among others. Robust and accurate soil moisture estimates are needed for drought monitoring, climatology research and hydrological model initialization. Compared to in-situ soil moisture measurements and satellite products, reanalysis soil moisture products are becoming good alternatives for analysis at the global scale due to their long temporal coverage. However, there are a great variety of reanalysis products available and choosing a suitable product that is consistent with the observed soil moisture condition is of significant interest.

In this study, we evaluate the performance of seven reanalysis products including ERA5-Land, CFSRv2, MERRA2-Land, JRA-55, GLDAS-Noah v2.1, CRA40, and GLEAM against field measurements from 109 sites with Cosmic Ray Neutron Sensors (CRNS). CRNS provide estimates of root-zone soil moisture at the field scale (~250m radius from sensor). The sites used in this study are located in the United Kingdom (51 sites), United States (40 sites), and Australia (18 sites). Metrics describing the temporal correlation (Pearson correlation coefficient, R) for the daily time series, seasonal cycle and anomaly time series, bias (mean square error, MSE) as well as root mean square difference (unbiased root mean square error, ubRMSE) are employed to quantify agreement between reanalysis products and measurements.

As an example, for the UK sites, CFSRv2 and GLEAM soil moisture products have lower errors in terms of temporal correlation and bias, while MERRA2-Land and GLDAS datasets exhibit higher errors. Reanalysis soil moisture products tend to have poorer behaviour at wet sites, with low temporal correlation and high bias. Relatively low correlation coefficient values are also found at sites with organic soils and low bulk density. This study provides guidelines for researchers about choosing the reanalysis soil moisture products.
Rock slope dynamics in flysch formation under cold climate (part 2): rock deformations and rockfall triggering factors
Authors: Birien Tom , Gauthier Francis
Published: March 2022

Since 1987, more than 17 500 rockfalls reaching a 70 km stretch of road have been reported by the Québec Ministry of Transport (MTQ) in northern Gaspésie. This natural hazard represents a nearly permanent danger for users. Earthquake, rainfall and freeze-thaw cycles are considered to be the main rockfall triggering factors. Although these events are well correlated with rockfall occurrences, it is not clear how they affect the failure mechanism. The first step in managing the risk rockfalls pose is to better understand the pre-failure processes that contribute to their development. The second step is to improve our ability to predict and anticipate rockfalls. This study aims to better understand the influence of climate-dependent variables on (1) the mechanical deformations of stratified sedimentary rock and (2) the climatic conditions conducive to rockfalls. Meteorological instruments including a 550 cm thermistor strings have been installed directly on a vertical rockwall located in northern Gaspésie. Mechanical deformations of the flysch sequence composed of sandstone, siltstone and shale was monitored using crack-meters. In addition, rockwalls were scanned with a terrestrial laser scanner (TLS) during specific pre-targeted meteorological conditions. Over a period of 18 months, 17 LiDAR surveys have allowed to identify 1287 rockfalls with a magnitude above 0.005 m³ on a scanned surface of 12 056 m². Irreversible deformations are mainly induced by rainfall and snowmelt (shrink-swell process in porous and clayey rock and/or hydrostatic pressure variations in discontinuities), by freeze-thaw cycles and to a lesser extent, by large thermal variations. Gradual settling measured in the siltstone strata causes destabilization of sandstone strata and the eventual fall of sandstone blocks. In winter, rockfall frequency is 12 times higher during a superficial thaw than during a cold period in which temperature remains below 0°C. In summer, rockfall frequency is 22 times higher during a heavy rainfall event than during a period mainly dry. Superficial freeze-thaw cycle (< 50 cm) causes mostly a high frequency of small magnitude events while deeper spring thaw (> 100 cm) results in a high frequency of large magnitude events. Influence of meteorological conditions on mechanical deformations and on rockfall frequency and magnitude is crucial in order to improve risk management since large magnitude events represent higher potential hazards. This study provides a classification of meteorological conditions based on their ability to trigger rockfalls of different magnitudes which could be used to implement an adequate preventive risk management.
Quantifying the impact of soil moisture dynamics on UK flood hazard under climate change
Authors: Rong Youtong , Bates Paul , Neal Jeffrey
Published: March 2022

Extreme precipitation events are expected to intensify with global warming, and naturally a widespread assumption is that the intensity and frequency of flooding will grow with the heavier downpours under climate change. However, flood magnitude is not only dependent on the spatial distribution, time evolution and rarity of precipitation, antecedent soil moisture and snowmelt are also the potential controls on flood hazard. Few studies have jointly quantified the influence of soil moisture dynamics and spatiotemporal distribution of precipitation on flood amplitude, though many research attempted to explain the elusive relationship between rainfall and flood conceptually. Here, the connections of changes in extreme precipitation and direct surface water flooding intensities in the periods of 1981-2000, 2021-2040 and 2061-2080 are quantified in 6 study areas in the UK, with high-resolution spatial and temporal characteristics of hourly rainfall data from UKCP Local 2.2 km. Dynamic soil moisture is modeled empirically and continuously to capture the moisture variation and infiltration loss, and distributed rainfall-runoff is calculated on the uneven terrain with the sub-grid river channel model in LISFLOOD-FP. Results indicate a strong correlation of the extreme rainfall and flood magnitude changes with the capacity of the soil moisture. Extreme precipitation can be magnified in rainy seasons due to amplified moisture convergence, while in dry periods limited moisture availability may offset extreme precipitation increases.
A Sequentially Estimated Terrestrial Reference Frame: JTRF2020
Authors: Gross Richard , Abbondanza Claudio , Chin T. Mike , Heflin Mike , Parker Jay
Published: March 2022

JPL's newly developed software for determining terrestrial reference frames, known as SREF (Square-root REference Frame filter), has been used to produce JTRF2020, a combined terrestrial reference frame determined from the input SINEX files submitted by the IVS, IGS, ILRS, and IDS for ITRF2020. SREF, being based upon a square-root information filter and smoother, determines the reference frame sequentially from the input station position time series. Incorporating process noise in SREF, determined from geophysical fluid loading models, allows the observed station positions to be smoothed between discontinuities caused by earthquakes and equipment changes. Reference frames determined by SREF, like JTRF2020, are represented by this set of smoothed station position time series. SREF also fits a model (consisting of a piecewise linear trend, annual and semi-annual periodic terms, and a sum of exponential terms to represent postseismic motion) to the station's observations and uses the model to fill gaps in the station's observing history, to forecast the position of the station after it stopped observing, and to hindcast its position before it started observing. The result of using SREF to determine JTRF2020 will be presented.
Unraveling the role of ancient orogens in present-day rifting using tectonic geomorphology in Shanxi, North China
Authors: Froemchen Malte , McCaffrey Ken , Allen Mark , van Hunen Jeroen , Phillips Thomas
Published: March 2022

Many rifts are influenced by pre-existing structures and heterogeneities during their evolution, a process known as structural inheritance. During a rift’s evolution, these heterogeneities may aid the nucleation of the rift, growth and segmentation of faults, aid linkage of various segments or even inhibit the formation of faults in various places. Structural inheritance is well explored in offshore rift settings due to the availability of high-quality 3D seismic, which enables good constraint on the structural evolution. However, the degree of structural inheritance in onshore active rifts is more difficult to constrain due to a lack of subsurface datasets. Yet, understanding how structural inheritance influences early rift evolution is vital to better understand seismic risk in areas of active rifting. The Shanxi Graben in the North of China is a densely populated active rift system that is believed to have formed along the trend of the Precambrian Trans North China Orogen. However, the influence of these Precambrian structures on the present-day rifting is poorly constrained. Here we show how the impact of structural inheritance on a young active rift may be investigated using tectonic geomorphological techniques - e.g., hypsometric integral, channel steepness (KsN) and drainage network analysis (chi analysis). Using the geomorphic expression of active faults, we can quantify their geomorphic response and identify faults that show higher levels of activity. Our results show that large basin bounding faults broadly follow the trends of basement fabrics but show a lower geomorphic response, while smaller faults that link the main basins show higher levels of geomorphic response but seemingly crosscut the basement fabrics. We interpret that those large faults formed first in regions with basement fabrics that were preferably orientated to the principal stress direction. Faults in the linkage zones between major basins likely formed later due to local perturbations of the stress field by the major rift faults. This means that there is no need for a changing stress field during the evolution of the Shanxi Graben, as previously proposed, but that the graben evolved under a relatively uniform stress field. Using the hypsometric integral or drainage network analysis may prove useful when applied to other areas with active rifts influenced by structural inheritance such as East Africa. Due to the lack of data in these regions, geomorphic analysis might prove useful in the study of the temporal evolution of structural inheritance in young active rifts.
Emerging technology for daily, field-scale, global evapotranspiration from space
Authors: Fisher Joshua ,   Hydrosat Team
Published: March 2022

Science and applications communities have made clear the needs and requirements for daily, field-scale ET. However, we do not have the high spatiotemporal TIR data to meet these requirements. Exciting new technology is now emerging to finally achieve this long-standing goal. With an upcoming launch en route to 16+ smallsat satellites, the Hydrosat constellation will provide field-scale, global TIR and VNIR measurements for ET every day, multiple times per day. An Early Adopters product is available now with 20 m daily TIR data globally from the fusion of Landsat, ECOSTRESS, MODIS, VIIRS, and Sentinel-2. Hydrosat data will be a game-changer and will significantly advance our monitoring and management capabilities for ecosystems, agriculture, and other applications.
Bayesian merging of large scale and local scale hydrological forecasts
Authors: Boucher Marie-Amélie , Odry Jean , Fortin Vincent , Lachance-Cloutier Simon , Turcotte Richard , Roussel Dominic
Published: March 2022

Global or large-scale hydrological forecasting systems covering entire countries, continents and even the entire planet are growing in popularity. As more large-scale hydrological forecasting systems emerge, it is likely that they will co-exist with pre-existing local forecasting systems. It is the case for instance in Canada, where most provinces have their own streamflow forecasting system, while the new NSRPS will eventually cover the whole country using a 1km by 1km grid. Those province, for instance Quebec, built their own forecasting systems on hydrological models configured for river catchments rather than a regular grid. Using this situation as a starting point and a case study, we propose a Bayesian framework for merging the forecasts from two systems. Within this Bayesian framework, the large-scale prior information comes from the NSRPS. This prior information is then updated using forecasts from the government of Quebec and the associated likelihood. In order to account for forecast uncertainty, this work is carried out using a probabilistic approach for both the NSRPS and Quebec’s Système de Prévision Hydrologique (SPH). While SPH produces probabilistic forecasts by default, the preliminary version of the NSRPS that we had access to is deterministic. Consequently, forecasts from the NSRPS had to be dressed into an ensemble in order to use them as prior distribution within the Bayesian merging framework. Alternative prior distributions (climatology, Markov chain) are also considered instead of those obtained from the NSRPS. Since both forecasting systems include ungauged sites, a version of this Bayesian merging framework based on regional statistics was also developed and tested using cross-validation. Our results show that the merged forecasts perform at least as well as the best individual system, for both gauged and ungauged basins. For longer lead times, merged forecasts can even outperform individual systems. Considering that the NSRPS relies on a non-calibrated model with no data assimilation, those results show that there could be important practical gains in merging large scale hydrological forecasts with local scale forecasts.
Lossy compression in violent thunderstorm simulations: Lessons learned and future goals
Authors: Orf Leigh , Halbert Kelton
Published: March 2022

Here we discuss our experiences with of ZFP lossy floating point compression in eddy resolving cloud modeling simulations of violent thunderstorms executed on the Blue Waters and Frontera supercomputers. Lossy compression has reduced our simulation data load by a factor of 20-100 from uncompressed. This savings enables us to save data at extremely high temporal resolution, up to the model's time step, the smallest possible temporal discretization. Further data savings is realized by only saving a subdomain of the entire simulation, and this is has opened the door to new approaches to analysis.  We will discuss the Lack Of a File System (LOFS) compressed format that model data is saved in, as well as conversion routines to create individual ZFP compressed NetCDF4 files for shaing with collaborators and for archiving. Further, we will discuss the effect of lossy compression on offline Lagrangian parcel analysis from LOFS data. Preliminary results suggest that high compression does not alter parcel paths considerably in cloud model simulation data over several minutes of integration as compared to uncompressed.
In-situ nanoscale geochemical characterization of organic matter in shale by AFM-IR
Authors: Wang Ke , Ma Lin , Taylor Kevin G.
Published: March 2022

Due to the fine-grained nature of shale, organic matter particles are generally micro- and nano-scale in size. Functional groups differ between different organic matter types and as such provide unique chemical information for organic matter. Micro-FTIR can provide direct measurement to characterize sample features at the micrometer scale. However, optical diffraction limits its application at the nanometer scale. As a non-destructive high-resolution scanning probe technique, atomic force microscopy (AFM) is very powerful in nanoscale research and has been widely used in the fields of polymers, semiconductors, electrochemistry and biology. To provide a better combination of AFM’s unique advantages with nanoscale chemical analysis, the AFM-IR technique has been developed in recent years and also attracted the attention of geologists to explore the application in geological materials.

In this research, AFM-IR which is a quite new technique in geological research was used to investigate the in-situ geochemical characteristics of organic matter in shale. Nanoscale molecular composition of individual organic particles was captured nondestructively, and the distribution of typical functional groups was displayed via 2D IR mapping. In our samples, both alginite and inertinite display chemical homogeneity. The former is dominated by oxygenated and aliphatic contents which indicates a higher hydrocarbon generation potential, whereas the latter is dominated by aromatic carbon. In contrast, migrated solid bitumen particles show compositional heterogeneities at the nanometer scale as some are aromatic-rich and others are aliphatic-rich. Finally, linking this advanced nanochemical technique to potential applications in subsurface energy was explored. This research demonstrates that AFM-IR is a powerful tool to examine the in-situ nanoscale geochemical characteristics of different organic matter types, which can also provide implications for energy applications.
Origin of compositional variations of Taupo Volcanic Zone (TVZ) eruption products: crustal differentiation or subduction melange diapirism?
Authors: Corella Santa Cruz Carlos Rodolfo , Zellmer Georg F. , Stirling Claudine H. , Straub Susanne , Reid Malcolm , Nemeth Karoly , Brenna Marco
Published: March 2022

The Taupo Volcanic Zone (TVZ) is dominated by felsic volcanism with more than 95% of the total volume corresponding to rhyolitic magmas. To generate felsic and intermediate volcanism, assimilation and fractional crystallisation (AFC) of primary basalt has previously been invoked as a necessary means to generate the chemical and isotopic characteristics of these magmas; is it energetically possible that dominantly felsic volcanism is generated by AFC of a mafic magma in the TVZ? Here, we present a suite of samples representative of the entire TVZ with respect to geography, age, and compositional variation from mafic to felsic. Major oxides, trace elements and Sr isotopic ratios were modelled for AFC using the energy and mass constrained Magma Chamber Simulator (MCS) and the local Torlesse terrain as an assimilant. We find that regardless of the intensive parameters employed, an energy and mass constrained model cannot realistically reproduce the combined major oxide, trace element, and isotopic systematics of the sample set. At New Zealand’s active margin, subduction erosion has been previously reported based on geophysical data. However, no links of this process to TVZ magmatism has been established to date. New high precision lead isotopic ratios show a tight linear trend that cannot be reproduced by AFC with a Torlesse component but can be approximated through a binary mixture of Torlesse subterrains, representative of eroded forearc crust, with global subducting sediments (GLOSS-II) on one hand, and a primitive basalt, representative of the subarc mantle, on the other. We therefore propose that the compositional variations in TVZ volcanic products and the genesis of voluminous rhyolites are primarily linked to melting of subduction melange diapirs as the source of this magmatism, with differentiation processes within the overriding crust being subordinate.
Controlling dynamic splitting of Brazilian disc specimens using Adelaide University Snapback Indirect Tensile test (AUSBIT)
Authors: Nguyen Giang D. , Verma Rupesh , Karakus Murat
Published: March 2022

Specimens of quasi-brittle materials under Brazilian disc testing usually fracture abruptly, with load carrying capacities dropping almost instantly from peak to zero. This abrupt failure in a split second is known due to the excess storage of strain energy at peak load that is released through the creation of new fracture surfaces and in the form of kinetic energy. This kind of dynamics and bursting is hard or impossible to control in laboratory testing using direct vertical displacement. We present our innovative technology, registered as an innovation patent in Australia, to control the dynamic splitting of Brazilian disc specimens so that the failure process is not abrupt, indicated by the snapback load-vertical displacement responses. Thanks to the use of lateral strain to control the loading, the time to complete the whole fracturing process increases significantly from a split second to a few hours, sufficient to enable advanced instrumentation using image-based techniques.  Acoustic Emission (AE) is used to monitor the fracturing process to make sure that the snapback response observed is not unloading. The proposed technology has been applied with largely success to a wide range of quasi-brittle materials, including sandstone, granite, and even 3D-printed rock-like materials with inherent weak discontinuities. This presentation reports the obtained results and challenges in controlling the dynamic splitting of Brazilian disc specimens using the proposed technology.
Pre-breakup drawdown and ice cliff formation on two Larsen B tributaries, 1968-2008
Authors: Ochwat Naomi , Scambos Ted , Child Sarah , Willis Mike
Published: March 2022

The major tributary glaciers of the former Larsen B Ice Shelf have undergone significant changes in the time leading up to, and following, the collapse of the ice shelf in March 2002. Crane and Hektoria-Green-Evans Glaciers (hereafter, Crane; Hektoria) experienced multiple periods of rapid velocity increases and intervening decreases, and dramatic surface lowering and mass loss. Initial results of early (late 1960s) U.S. Navy Trimetrogon aerial image analysis for elevation indicates large elevation losses in the decades prior to the disintegration event. Following the ice shelf collapse, both glaciers developed significant ice cliff fronts, but with markedly different calving styles and ice front heights at different times after the event. Rapid collapse with indications of arcuate listric faulting began at Hektoria almost immediately after ice shelf loss, while Crane also experienced rapid retreat during this time. Maximum elevation of the cliff fronts in the Hektoria collapsed region ranged between 60 and 100 meters. Peak ice cliff height at Crane was approximately 105 m, occurring in late 2004. These cliff heights correspond with periods of very high flow speed, thinning, and rapid ice front retreat that is characteristic with modeled ice cliff failure events. Here we present our analysis of the characteristics that defined the retreat periods. We assess ice velocity changes from optical satellite imagery, hypsometry, and ice cliff front heights from stereo-image DEMs and altimetry data, and use bed topography and bathymetry data. Ice cliff failure that could lead to Marine Ice Cliff Instability (MICI) has never been observed either in situ or through remote sensing. Using the observed dynamics of Crane and Hektoria, we aim to improve our understanding of the parameters that modeling results show as the drivers of ice cliff failure. In doing so, impacts of ice cliff failure on outlet glacier stability in numerical modeling will be better constrained, which will increase predictive sea level rise accuracy.
Annual development of subalpine grassland observed with UAV: how NDVI evolution is controlled by snow melting
Authors: Revuelto Jesús , Sobrino Javier , Gómez Daniel , Rodriguez-López Guillermo , Alonso-González Esteban , Rojas-Heredia Francisco , Izagirre Eñaut , Montorio-Lloveria Raquel , Pérez-Cabello Fernando , López-Moreno Juan Ignacio
Published: March 2022

In the Pyrenees, as in other mid latitude mountain ranges, sub alpine areas have a long lasting snow cover that affect different mountain processes, including river discharge timing, soil erosion, primary production or animal and plant phenology. This work presents and analyzes a complete snow depth and Normalized Difference Vegetation Index (NDVI) spatial distribution dataset, generated by Unmanned Aerial Vehicles (UAV) over two years. This study aims to increase the knowledge and understanding of the relationship of the duration and timing of snowmelt and vegetation cover and its annual cycle.

The dataset was obtained in Izas Experimental Catchment, a 55 ha study area located in Central Spanish Pyrenees ranging between 2000 to 2300 m a.s.l., which is mostly covered by grasslands. A total of 18 UAV snow depth and 14 NDVI observations were obtained by a fixed wing UAV equipped with RGB and multispectral cameras during 2020 and 2021. The melt out date for the different areas of the catchment has been obtained from the snow depth distribution dataset, which in turn has been used to analyze the NDVI evolution. The NDVI values for each UAV flight have been correlated with the snow depth distribution observed in previous dates and with different topographic variables as elevation, solar radiation, curvature (through the Topographic Position Index) or slope.

The maximum seasonal NDVI happens throughout the study area simultaneously in the entire study area; however those zones with the latest snow disappearance do not reach NDVI values as high as those observed in areas with earlier snow disappearance. Oppositely areas with the soonest snow melting (in late February) have lower maximum NDVI values that those observed in areas with snow melting occurring later (around May).  NDVI correlations have shown that the snow depth distribution observed about one month prior to each NDVI acquisition has a very important control on pasture phenology. This correlation is particularly evident on the free-snow areas during first melting weeks, with a lower influence in those areas where snow melts at the end of the snow season. This field study exemplifies how intensive UAV acquisitions allow understanding snow processes over extended areas with an unprecedented spatial resolution.
Investigating the impact of urban heat islands on long-term climatic observations in Sweden
Authors: Suliman Mahmoud , Winterdahl Mattias
Published: March 2022

Urban land cover (ULC) has been steadily expanding in Sweden over the last century. This expansion could potentially include areas in the vicinity of meteorological stations, and may, in turn, lead to increased urban heat island effects in the areas surrounding them. As observations form the basis of many climate studies, it is then important to investigate the potential influence of urban heat island effects on long-term trends in climatic observations. For the purpose of quantifying the change in ULC around meteorological stations, we developed a semi-supervised methodology that classifies the land cover based on single-band orthophotos, and then calculates the change in ULC around the stations. Using this methodology, we estimated the change in land cover in a 100 m radius around 48 Swedish meteorological stations during the period 1960-2019. The seasonal Mann-Kendall test, together with the Theil-Sen estimator and linear regression were applied on the stations’ long-term temperature and precipitation data in order to determine systematic differences in climatic trends between stations with varying degrees of ULC increase, and to explore the possible influence of urban heat islands. Initial results associate large increases in ULC with higher positive Theil-Sen estimator values for temperature observations, and negative linear regression slopes in precipitation observations, respectively (p < 0.001). Thus, the temperature increase has been more pronounced at meteorological stations experiencing substantial ULC increase. Conversely, these stations showed decreasing trends in precipitation. Overall, our results show a correlation between the change in ULC around climatic stations and their long-term trends in climatic observations, and suggest possible influences of urban heat island effects on observed climate data in Sweden.
Dehydration-induced earthquakes and apparent slab pull in a subducted oceanic slab beneath Vrancea, Romania
Authors: Ferrand Thomas P. , Manea Elena , Craiu Andreea , Vrijmoed Johannes C. , Marmureanu Alexandru
Published: March 2022

Vrancea, Eastern Romania, presents a significant intermediate-depth seismicity, between 60 and 170 km depth, i.e. pressures from 2 to 6.5 GPa. A debate has been lasting for decades regarding the nature of the seismic volume, which could correspond to the remnant of a subducted slab of Tethyan lithosphere or a delamination of the Carpathians lithosphere. We present P-T diagrams showing to what extent these hypocentral conditions match the thermodynamic stability limits for minerals typical of the uppermost mantle, oceanic crust and lower continental crust.

Most triggering conditions match relatively well antigorite dehydration between 2 and 4.5 GPa; at higher pressures, the dehydration of the 10-Å phase provides the best fit. This demonstrates that the Vrancea intermediate-depth seismicity is evidence of the current dehydration of an oceanic slab beneath Romania. Our results are consistent with a recent rollback of a W-dipping oceanic slab, whose current location is explained by limited delamination of the continental Moesian lithosphere between the Tethyan suture zone and Vrancea.

In addition, we investigate the potential link between the triggering mechanisms and the retrieved focal mechanisms of 940 earthquakes, which allows interpreting the stress field distribution with depth. We observe a switch from collision to vertical extension between 100 and 130 km depth, where the Clapeyron slope of serpentine dehydration is negative. The negative volume change within dehydrating subhorizontal serpentinized faults (verticalized slab) likely explains the vertical extension recorded by the intermediate-depth seismicity. This apparent slab pull is accompanied with a rotation of the main compressive stress, which could favour slab detachments in actively subducting slabs.
Fold and thrust belts in an intraplate setting- An interplay between rheology and inherited deep structures. 
Authors: Santimano Tasca , Pysklywec Russell
Published: March 2022

Fold and thrust belts and prominent orogens are found primarily along continental plate boundaries. Our knowledge of how these orogens are formed is based on the deformation of the upper crust. However, continental interiors also exhibit fold and thrust belts that may not be related to plate boundary collision. In these intraplate settings, structural heterogeneities in the deep lithosphere have been identified as an important factor in the formation of these belts. Particularly, inherited deep zones of weakness may initiate orogenesis in continent interiors. Aside from structural heterogeneity, the rheological strength of the lithosphere also has a primary role affecting the kinematics of deformation in the lithosphere. To investigate the interplay of rheology and pre-existing structures, we designed a set of physical scaled analogue experiments in a convergent setting that tests (a) the presence and absence of a pre-existing weak zone in the lithospheric mantle and (b) the effects of the rheological strength of the lithospheric mantle. The tectonic evolution of the model is recorded to acquire a time series data set of the velocity field, strain in the model, and the development of structures in the upper crust. Results show that a weak zone in the lithospheric mantle allows deformation to be accommodated by displacement along this zone and is transferred into the overlying lower and upper crust, regardless of lithosphere strength. In contrast, a model absent of a weak zone accommodates deformation by folding and thickening of the viscous layers. The viscous lithosphere in models with a strong lithospheric mantle tends to buckle creating a sequence of brittle faults in the upper crust. Specifically, the rheology of the lithosphere dictates the distribution of strain. Our results are further used to interpret the genetic formation of an intracontinental fold and thrust belt found on Ellesmere Island in the Canadian Arctic Archipelago.