bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modelling of ice stream fabrics: Implications for recrystallization processes and basal slip conditions
Authors: Richards Daniel , Pegler Sam , Piazolo Sandra
Published: March 2022

Accurately predicting ice crystal fabrics is key to understanding the processes and deformation in ice-sheets. Here we use SpecCAF, a continuum fabric evolution model validated against laboratory experiments, to predict the fabric evolution with an active ice stream. This is done by predicting the fabrics at the East Greenland Ice core Project (EGRIP) site. We do this using satellite data and inferred particle paths, combined with the shallow ice approximation (with basal slip) to infer a leading order approximation for the deformation through the ice sheet. We find that SpecCAF is able to predict the patterns observed at EGRIP - a girdle/horizontal maxima fabric perpendicular to the flow direction. By reducing the rate of rotational recrystallization in the model we are also able to predict the fabric strength at EGRIP. This suggests the effect of rotational recrystallization on the fabric may be primarily strain-rate/stress dependent. These results show SpecCAF can be applied to real-world conditions and provide insights into the deformation and basal-conditions of the ice sheet. As the model only considers deformation and recrystallization through dislocation creep, the results imply that - for the ice stream modelled - no other process is significantly influencing both the produced ice fabric and the deformation. We find that the model gives best results for full slip at the base of the ice sheet, implying that the level of sliding at the base of the ice sheet in the North Greenland Ice stream may be very high. The methodology used here can be extended to other ice core locations in Greenland and Antarctica.
Astronomical Climate Pacing in a Model Framework for Late Triassic Lake Level Cycles
Authors: Landwehrs Jan , Wagreich Michael , Feulner Georg , Willeit Matteo , Whiteside Jessica H. , Olsen Paul E.
Published: March 2022

Combining both detailed geological records and climate modeling provides exciting opportunities to understand orbital effects on the early Mesozoic greenhouse climate across the supercontinent Pangaea. Lake sediments from the Newark-Hartford Basins (NHB) of the eastern US record cyclic climate changes in the tropics of Pangaea during the Late Triassic and earliest Jurassic (~233–199 Ma). We explore how the combined climatic effect of orbital forcing, paleogeographic changes and atmospheric pCO2 variations could have contributed to major features of this record.

For this, we assess results from an ensemble of transient, orbitally driven climate simulations for nine geologic timeslices, three atmospheric pCO2 values and two paleogeographic reconstructions. Each simulation is run with an idealized orbital forcing, with precession, modulated by eccentricity, and obliquity oscillating over a 250 kyr interval. The long duration and large number of simulations is achieved by utilizing the fast CLIMBER-X Earth System Model.

A transition from tropical humid to more seasonal and ultimately semi-arid climates is associated with the tectonic drift of the NHB region from the equator to ~20°N. The orbital modulation of the precipitation-evaporation balance that could be recorded in the lake sediments is most pronounced during 220 to 200 Ma, while it is limited by weak seasonality and increasing aridity before and afterwards, respectively. Lower pCO2 values around 205 Ma contribute to drier climates and could have led to the damping of sediment cyclicity observed at this time. Eccentricity-modulated precession dominates the orbital climate response in the NHB area, with maximum humidity associated to high spring-summer insolation and enhanced moisture import from the Tethys sea. High obliquity further amplifies summer precipitation through the seasonally shifting tropical rainfall belt.

We furthermore show how contemporaneous proxy localities, e.g. in the Germanic Basin, Junggar Basin or Colorado Plateau, can also be evaluated in this model framework. Studying the varying climate response in these different areas provides directions towards an integrated picture of global astronomical climate pacing in the Late Triassic. Furthermore, the presented approach is readily applicable to other periods in Earth history.
Sustainability of a multi-stage free water surface constructed wetland in terms of water quality under changing conditions
Authors: Jiang Long , Chui Ting Fong May
Published: March 2022

Multi-stage constructed wetlands (CWs) are widely used for water quality improvement, especially in the treatment of wastewater. Many studies focus on their treatment efficiency under steady loading, but fewer studies consider their stability and sustainability under variable conditions. This study monitors the hydrology and water quality at the multi-stage CWs in the Hong Kong Wetland Park. Five wetland units along the flow path are examined for their long-term performance and sustainability in terms of water quality under seasonal changes, storm events, and shock loadings of pollutants. Time-series statistical analysis indicates that the multistage design well achieves stable performance. Each wetland unit has certain roles and they work together to achieve good performance. The reliability analysis shows that the CW system can largely buffer the fluctuations from most disturbances. While the resiliency analysis also shows that most water quality indicators could recover in a few days after the fluctuations. The water levels recover quickly but it was difficult to return to original water levels in multi-stage CWs. Besides, a numerical model is developed, calibrated, and utilized to predict future water quality changes. This will help evaluate measures to improve the sustainability of multi-stage CWs by simulating water quality changes under different influent concentrations and rainfall conditions. This study could provide appropriate recommendations and early warnings for wetland management and improvement.
Active versus arrested silica diagenetic front: Implications on the Palaeoceanographic evolution across the Falkland Plateau
Authors: Najjarifarizhendi Banafsheh , Uenzelmann-Neben Gabriele
Published: March 2022

3300 km of newly collected 2D seismic reflection data across the Falkland Plateau, acquired during cruise MSM81 (2019) allowed for mapping of two distinct bottom-simulating-reflection (BSR) features, which are mostly pronounced within the western and southern sectors of the Falkland Plateau Basin (FPB-BSR) and the eastern sector of the Falkland Trough (FT-BSR). The nature of these BSRs is investigated by means of their reflection characteristics and seismic expressions and is concluded to be associated with silica diagenetic fronts. In absence of a proximal borehole, age information is derived through correlation with the Deep Sea Drilling Project Leg 36 Sites 327 and 330 and Leg 71 Site 511, on the easternmost proximity of the FPB, along the seismic profiles. It is argued in this study, that despite their similar origin, presumably in connection to an Opal A/CT diagenetic front, FPB- and FT-BSR display dissimilar geometrical characters. While the FPB-BSR is by definition a true BSR, which mimics the present seafloor, the geometrical extent of the FT-BSR, which shows parallelism with a shallower buried (Early/Middle Miocene?) reflector, favors a fossilized diagenetic front parallel to a paleo-isotherm. Palaeoceanic and palaeomorphologic implications are brought based on observed depth properties of the BSRs by considering different scenarios for the geothermal gradients. The observations suggest the absence of up to a few hundred meters of sedimentary deposits which presumably have been eroded due to the erosive action of the bottom currents.
Utilising Cryosat-2 observations of the Arctic sea ice cover to produce a new Arctic sea ice reanalysis
Authors: Williams Nicholas , Byrne Nicholas , Feltham Daniel , Van Leeuwen Peter Jan , Schroeder David , Bannister Ross , Shepherd Andrew
Published: March 2022

In this work we present results from a new sea ice reanalysis over the satellite era. We use a newly created sea ice data assimilation system CICE-PDAF, combining the Los Alamos Sea Ice Model (CICE) and the Parallelized Data Assimilation Framework (PDAF), to take advantage of the new observations of the sea ice cover produced in the last decade by Cryosat-2. Sea ice thickness and sea ice thickness distribution observations from Cryosat-2, alongside sea ice concentration observations, are assimilated to explore their effects on our current estimates of the Arctic sea ice cover. In particular we look at its effects on the sea ice thickness distribution. The true state of the Arctic sub-grid scale thickness distribution system is not well known, and yet it plays a key role in the dynamic and thermodynamic processes present in the model to produce a good estimate of the Arctic sea ice state. Thus by combining knowledge from state-of-the-art sea ice models with knowledge from newly developed observations we hope to produce a clearer picture of the Arctic sea ice and its thickness distribution.
Automatic detection of pit-mound topography from LiDAR based DEMs
Authors: Godziek Janusz , Pawlik Łukasz
Published: March 2022

Pit-and-mound (treethrow, windthrow) topography is a result of tree uprooting caused by the impact of hurricane-speed wind events. Analyzing its location and morphometric features can improve our knowledge about the influence of winds on forest ecosystem dynamics and on changes in the forest floor microrelief. This is important in terms of hillslope denudation and soil evolution.

The occurrence and evolution of pit-mound topography can be studied with the use of high-resolution elevation data. Such data can be obtained from LiDAR (Light Detection and Ranging) surveys. Polish Institute of Geodesy and Cartography carried the LiDAR survey in the years 2010-2015. Point cloud data for the entire area of Poland with the minimal density of 4 points per m2 is currently available on the Internet.

Under the present project, we have analyzed Digital Elevation Models (DEMs) produced from the above-mentioned LiDAR data in order to develop and test a new method for automatic detection of pit-mound topography. As far as we know, no such method exists at the moment. We generated DEMs with 0.5 m spatial resolution for three study sites with the confirmed occurrence of pit-mound topography, located in Southern Poland. A script with the method was written in the R programming language.

The proposed method is based on contour lines. We found that the detection of pit and mound topography formed on gentle hillslopes is possible when closed contours are delineated. Detected forms can be classified into “pits” and “mounds” by investigating point positions with the highest and the lowest elevation within the closed contour. On the other hand, for steep surfaces pit-mound topography can be detected by calculating distances between contours and selecting slope segments with between-contours distances above a certain threshold value. This leads to the identification of gently-sloped areas within the study site. With a high probability, such areas indicate places, where pit-mound topography was formed. To validate our methods, we performed the on-screen assessment of DEMs for the presence of forms that could be interpreted as pit-mound topography.

The study has been supported by the Polish National Science Centre (project no 2019/35/O/ST10/00032).
Uncertainty assessment and data-worth evaluation for estimating soil hydraulic parameters and recharge fluxes from lysimeter data
Authors: Schübl Marleen , Stumpp Christine , Brunetti Giuseppe
Published: March 2022

Transient measurements from lysimeters are frequently coupled with Richards-based solvers to inversely estimate soil hydraulic parameters (SHPs) and numerically describe vadose zone water fluxes, such as recharge. To reduce model predictive uncertainty, the lysimeter experiment should be designed to maximize the information content of observations. However, in practice, this is generally done by relying on the a priori expertise of the scientist/user, without exploiting the advantages of model-based experimental design. Thus, the main aim of this study is to demonstrate how model-based experimental design can be used to maximize the information content of observations in multiple scenarios encompassing different soil textural compositions and climatic conditions. The hydrological model HYDRUS is coupled with a Nested Sampling estimator to calculate the parameters’ posterior distributions and the Kullback-Leibler divergences. Results indicate that the combination of seepage flow, soil water content, and soil matric potential measurements generally leads to highly informative designs, especially for fine textured soils, while results from coarse soils are generally affected by higher uncertainty. Furthermore, soil matric potential proves to be more informative than soil water content measurements. Additionally, the propagation of parameter uncertainties in a contrasting (dry) climate scenario strongly increased prediction uncertainties for sandy soil, not only in terms of the cumulative amount and magnitude of the peak, but also in the temporal variability of the seepage flow. 
Climate indicators for high-impact weather events as droughts and temperature extremes over the Iberian Peninsula with convection permitting scale simulations
Authors: Adinolfi Marianna , Raffa Mario , Mercogliano Paola
Published: March 2022

The dynamical downscaling of global circulation models (GCMs) with regional climate models (RCMs) is a computationally expensive process, even more so running at the convection permitting scale (CP). The high-resolution product of these simulations is an important factor for consideration and is relevant to provide a  proper characterization of climate extremes, to address hazard assessment and manage associated risk. Moreover, an increasing number of studies shows improvements in regional climate model performances at CP scale if compared to their driving RCMs. The assessment of extreme events indicators, as defined by the joint CCl/WCRP/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI), is here proposed over the Iberian peninsula using CP simulations at around 3km of resolution for evaluation experiment as well as for future spans. The same indicators are also assessed for the available observations and for the driving RCM simulation at around 12km of resolution. Such approach allows, from one side to evaluate the results of CP simulation by comparison against observations and, on the other one, to quantify if there are any improvement by comparison against RCM simulation at a coarser resolution. Then, indicators are calculated in a near future 10 years-long period from both CP and RCM simulations, in order to highlight the differences in the climate projections. The selected indicators as consecutive dry days and maximum value of daily maximum temperature are strictly connected to high-impact events as droughts and temperature extremes. Their exploiting provide useful information about the expected changes in next decades due to the climate warming.
Modelling the long-term impact of catchment and coastal management on estuarine morphology
Authors: Yoshizaki Miyo , Schuerch Mark , Mao Luca , Macklin Mark
Published: March 2022

Climate change puts estuaries at higher risk of flooding from the land, river, and coast by increasing sea levels and extreme weather events such as heavy rainfall. Meanwhile, sediment delivery from catchments and the seas is expected to play a crucial role in estuarine to keep up with sea-level rise (SLR), which will consequently affect estuarine hydrodynamics and flood risks in the future. Nevertheless, the actual impact of fluvial inputs, and specifically, the role of catchment management for the long-term estuarine development, is less known due to a lack of integrated catchment and coastal modelling works. Therefore, this study built a modelling framework that combined catchment hydrological and estuary hydro-morphological processes to understand the impact of catchment management, particularly natural flood management, on long-term estuarine evolution. A cellular automata model (Bentley, 2016) and HEC-HMS were applied for estuary and catchment modelling, respectively. The reforestation scenario with and without SLR (3 mm/year) for 100 years on a hypothetical catchment and estuary were tested. The reforestation effect was captured as the proportionally reduced catchment discharge and sediment delivery at the rainfall events compared to the baseline (non-reforestation) scenario. Preliminary results, however, showed the estuarine morphology is less sensitive to reforestation cases. In both management scenarios, SLR cases resulted in a 50 % increase in sedimentation in the estuary compared to non-SLR. Though due to rapid SLR, that sedimentation was not sufficient to keep tidal prism constant, and it was increased by 13% in 100 years as a result. The above results/sensitivities are based on simulation runs, with no tidal pumping, incorporating this may change these results. Further work such as introducing tidal asymmetry to the estuary model will provide a more comprehensive view of the fluvial impact on estuaries' long-term evolution. 

Bentley, I. (2016) A novel cellular automata based estuarine morphodynamic model. PhD. University of Glasgow. Available at: http://theses.gla.ac.uk/6821/.
Ice Nucleating Particles in the Antarctic region
Authors: Wex Heike , Henning Silvia , Mangold Alexander , Van Overmeiren Preben , Zeppenfeld Sebastian , van Pinxteren Manuela , Herrmann Hartmut , Dallosto Manuel , Stratmann Frank
Published: March 2022

Ice nucleating particles (INPs) are rare but important atmospheric particles as they induce the formation of primary ice in mixed phase clouds and also in some cirrus clouds. A plethora of substances which can be found in atmospheric particles can induce ice nucleation. The most important ice active particle types in the atmosphere are assumed to be mineral dust and biological particles, which can originate from a large number of sources. It is hence not surprising that INP concentrations vary over several orders of magnitude at any ice nucleation temperature, with concentrations being typically larger in continental than in marine environments. Although research concerning INP and their global occurrence has seen a steep rise in the past years, global INP concentrations are still not well known, and not all important INP sources are clear, neither are there good parameterizations for describing INP concentrations in models.

To increase the knowledge of typical global INP concentrations and to draw conclusions about INP sources, we examined INP concentrations in the Antarctic region, namely at the German research Station Neumayer III, located at shelf ice in close proximity (only some 10 km) to the ice edge, at the Belgian research Station Princess Elisabeth, located roughly 200 km inland and at an altitude of 1390 m, and during a campaign including ship- and land-based data at the Antarctic peninsula. We used our well-established methods of filter collection and off-line analysis with cold-stages to derive INP concentrations in these locations.

For Neumayer, two years of data are available. INP concentrations there were generally lower than values derived, e.g., for northern mid latitudes, and they were similar to values published for the Southern Ocean in literature. No pronounced annual cycle was observed. Around and on the Antarctic peninsula, INP concentrations were roughly similar to those observed at Neumayer. However, the Princess Elisabeth station, for which only data obtained during two austral summers are available, showed the lowest values detected in this study. Our results suggest that sources of INP in the Antarctic region are rare, and particularly so on Antarctica itself. 
Can glendonites be used as palaeothermometers?
Authors: Vickers Madeleine L. , Bernasconi Stefano M. , Schultz Bo Pagh , Rogov Mikhail , Ershova Victoria , Ullmann Clemens V. , Chivas Allan R. , Dux Florian W. , Jones Morgan
Published: March 2022

 

Glendonites are pseudomorphs after the mineral ikaite found throughout the geological record since the Palaeoproterozoic, often during cooling or glaciation episodes. This, and the apparent temperature dependency of ikaite on low temperatures to nucleate and grow, led to glendonites being considered low-temperature proxies. However, subsequent laboratory work has shown that ikaites, and therefore fossil glendonites, may not require near-freezing temperatures to nucleate and grow. The occurrence of glendonites in sediments deposited during Greenhouse times, and the lack of glendonites during some icehouse periods of Earth’s climate history appears to support a theory that glendonites are more dependent on local chemical conditions than temperature. We present a database of clumped isotope paleothermometry temperatures from glendonites aged Permian to Recent, and discuss the implications of these reconstructed temperatures in the context of glendonites as a palaeothermometer, and the complication of diagenetic overprinting in ancient glendonites.
Water Towers of the Pamirs: I. Precipitation and temperature trends
Authors: Khojazoda Zulfiqor , Sidle Roy , Caiserman Arnaud
Published: March 2022

Precipitation and temperature changes across the Vakhsh and Panj basins are of great importance for Tajikistan, Afghanistan, Turkmenistan, and Uzbekistan for consumption, agricultural, and energy purposes. While studies of precipitation and temperature trends have been conducted in these basins, attention to their heterogenous topography and nature have not been considered and analyzed together with glacial and permafrost melt. Here, we assessed the trends of precipitation and temperature over the last 20 years using remote sensing products. For precipitation, we used research grade daily GPM IMERG V06 Final Run from 2001 to 2020. Similarly, temperature MODIS Land Surface Temperature & Emissivity (LST&E) (MOD11A1) was used to assess temperature trends and separate liquid from solid precipitation. Annual precipitation and temperature trends were also assessed in three elevation bands: low (317-2225m), middle (2225-4500m) and high (4500-7543m).

Positive significant trends for solid precipitation mainly arise in the northern parts of the basins, while slightly positive with more negative trends occurred over the central and southern parts of the Panj basin. A significant solid precipitation trend of +1.30mm y-1 below 2225 m a.s.l. occurred in late spring. Many of the pixels (1 x 1 km) across the study region that exhibited significant trends were increases in temperature, especially in the high elevations in the eastern portion of the basins. There was a significant annual increase of liquid precipitation coupled with a decrease in solid precipitation and an increase in temperature trend in the central Pamirs, implying a shift from solid to liquid precipitation. An increase in rainfall below 4500 m a.s.l. was observed, where the largest increases occurred in the western portions of these basins with nearly no significant temperature trends; thus, potentially having a positive influence on agricultural and community water supplies. However, long-term water supplies in the dry regions of the central and eastern parts of the basins may create supply vulnerabilities.
Daily precipitation with stretched-exponential tails could explain the statistics of observed annual maxima
Authors: Marra Francesco , Papalexiou Simon M.
Published: March 2022

The parent distribution of daily precipitation is usually not known, and the exceedance probability of extremes is described using a Generalized Extreme Value distribution (GEV) fitting the annual maxima. However, knowing the parent distribution would allow us to use ordinary statistics to describe extremes, with two advantages: (i) a decreased parameter estimation uncertainty; (ii) the possibility to establish direct relations between ordinary and extreme events. Recent studies suggest that daily precipitation could have Weibull tails, meaning that the probability of exceeding large values decrease as a stretched exponential. Here, we exploit a global dataset of long and quality-controlled continuous rain gauge records (~8,000 stations, ≥50 complete years) to investigate this question.

We find that the observed annual maxima are likely samples from Weibull tails in ~88% of the stations worldwide. On average, ~36% of the wet days belong to these tails. We find a strong climatic dependence in their definition, with smaller portions of data in the Weibull tails in central Europe, US east coast and southern Australia. We then generate synthetic records with the same characteristics (yearly number of wet days, Weibull tails with the same shape parameter) and increasing lengths (10-110 years); we estimate the corresponding GEV shape parameters and contrast them with the ones obtained from very long annual maxima records (~15,000 stations, 40-163 years; Papalexiou and Koutsoyiannis, 2013, https://doi.org/10.1029/2012WR012557). We show that parent distributions with Weibull tails well explain the properties of the observed GEV shape parameters. These GEV tails (type-III, Frechet) are heavier than the limiting GEV for Weibull parent distributions (type-I, Gumbel); this implies a pre-asymptotic behavior: the average yearly number of wet days (globally, n=100±50) is not large enough to fulfill the asymptotic assumption (n~∞) of extreme value theory. Contrasting our results with generalized Pareto tails, as predicted by extreme value theory for high threshold exceedances, we find that the two models are equivalent within the observational uncertainties; the Weibull model, however, describes a portion of data which is, on average, 7 times larger.
Plantenna Demonstrator: novel sensors for monitoring plant health
Authors: ten Veldhuis Marie-Claire , Steeneken Peter , Verbiest Gerard , Dutta Satadal , Kaiser Elias , Vialet-Chabrand Silvere , Fan Qinwen , Bronckers Sander , Vdiojkovic Vojkan , Van den Berg Tom , Vilfan Nastassia
Published: March 2022

Measuring plant-balance and -water dynamics is essential to gain better insight into plant health. In the Plantena research program (https://www.4tu.nl/plantenna/en/), new techniques have been developed for direct monitoring of plant traits. These include water status monitoring based on Ultrasound, magnetic resonance imaging (MRI) or radiofrequency (RF), volatile compound emission (“e-Nose”) and continuous stomatal aperture sensing (SAS). The SAS sensor enables real-time autonomous imaging of stomatal apertures inside the growth environment to asses dynamic behavior of individual stomata within the ensemble. For e-Nose, a new approach is being explored to utilize an electronic nose to smell insects for early detection of pests, thus safeguarding crop harvests while minimizing pesticide usage. RF sensing , Ultrasound and MRI are non-invasive techniques for real-time monitoring of internal plant parameters. RF is being investigated for monitoring of water and mineral content, Ultrasound technology enables the determination of internal plant parameters in a fast, non-contact, and non-destructive matter, thereby providing new ways for water monitoring, pest detection, and selective breeding. MRI enables monitoring of water content and flow in plants and offers the potential for non-invasive metabolite detection.

Additionally, low-cost, autonomous sensor nodes are being developed for integration of novel and existing plant-sensors into a high density network (“internet of plants”). To this end, a smart and efficient power management scheme is being developed to adapt the sensor nodes to a wide range of environmental scenarios. A first demonstration of sensor innovations will be set up in spring 2022 in a commercial greenhouse environment. In this contribution we will present preliminary results of novel plant-sensors as well as the set-up of the Plantenna Demonstrator facility.

Outlook: Results of the Plantenna Demonstrator will validate performance of the plant-sensor innovations in a real-life environment and by combining these with existing sensors will provide valuable datasets for assessing plant response to climate variability and stress conditions.
Spatial patterns in seasonal coupling between ice sheet hydrology and motion in west Greenland
Authors: Sole Andrew , Davison Benjamin , Livingstone Stephen
Published: March 2022

Ice motion within the land-terminating ablation zone of west Greenland typically follows a seasonal pattern with fastest flow in the spring as surface meltwater first accesses the hydraulically inefficient subglacial drainage system, followed by a gradual reduction in ice motion over the summer as efficient subglacial channels evacuate water stored over wide swathes of the subglacial environment. Minimum speeds occur in autumn, when surface meltwater delivery to the bed ceases, then, over winter, ice flow gradually recovers before the cycle repeats once again. This understanding is principally derived from high temporal resolution field observations with limited spatial coverage. It is now, however, possible to measure these seasonal patterns in detail over large spatial scales, enabling basin-scale comparisons between meltwater supply, subglacial hydrology and ice motion.

We present near continuous time-series of ice motion for a ~60,000 km2 portion of predominantly the land-terminating western margin of the Greenland Ice Sheet (with coverage extending up to 150 km from the margin in winter and 25 km in summer) between 2016 and 2022 at up to 12-day temporal resolution derived from Sentinel-1, Sentinel-2 and Landsat 8 imagery. We compare ice motion with surface melt magnitude and timing (derived from meteorological observations and a positive degree day model), theoretical subglacial water routing, and glaciological context (e.g. ice thickness).

Our results reveal clear spatial patterns in seasonal coupling between ice sheet hydrology and motion. Overall, the amplitude of the seasonal cycle of ice motion is generally greater closer to the ice margin as has been shown previously by field observations. There is, however, distinct variability between subglacial hydraulic catchments. Subglacial catchments whose principal drainage pathway has a high hydraulic potential gradient typically experience smaller peaks in summer ice motion, but more prominent autumn ice flow minima. Subglacial water flow in such catchments has more potential to create hydraulically efficient channels, which can both accommodate spikes in meltwater delivery with muted ice flow acceleration, and also reduce basal water pressure across a wider area of the ice bed as surface meltwater delivery declines.

As ice sheet surface mass balance becomes more negative and marginal ice thins fastest (where the ice is land-terminating), subglacial hydraulic gradients and subglacial discharge will both increase. Based on our findings, these changes may lead to smaller summer ice flow accelerations and bigger winter slow-downs, driving an overall decrease in mean annual ice motion. Our results also highlight the importance of careful selection of field sites for measuring ice motion and caution against scaling up from spatially limited observations.
Coda-Based Estimation of Source Parameters of Laboratory Acoustic-Emission Events
Authors: Kartseva Tatiana , Shapiro Nikolai , Patonin Andrey , Smirnov Vladimir , Ponomarev Alexander
Published: March 2022

We propose a coda-based estimation of source parameters of acoustic events recorded in laboratory experiments on rock deformation. Coda-waves are considered as the reverberation of the acoustic field in the tested sample. After multiple reverberations, the resulting wavefield can be approximated as nearly homogeneously distributed over the sample and with signal amplitudes decaying exponentially in time (linearly in a logarithmic scale). Within the framework of this model, the frequency-dependent coda amplitude at any moment of time is described as combination of a source spectra, of a decay rate combining internal attenuation with reverberation losses, and of a sensor response. One of the main difficulties with the laboratory experiments is that acoustic sensors are very difficult to calibrate and their absolute response function in most of cases remains unknown. With the simple reverberation model, the logarithms of coda amplitudes at different times and sensors and for multiple events are described by a system of linear equations that we solve in a least-square sense to find frequency-dependent decay rates and relative source spectra and sensor responses. In a next step, we compute spectral ratios between different events to eliminate the sensor responses and to estimate main source parameters such as corner frequencies and relative seismic moments. Additionally, we propose a new method for computing relative magnitudes (energy classes) of acoustic emission events from the coda envelopes and argue that it might be more robust comparing with estimations based on first arrivals.

We provide details of our data analyses tehnique and present first results of our new coda-based method applied to 30-600 kHz signals recorded during experiments carried out in the Research Equipment Sharing Center of IPE RAS “Petrophysics, Geomechanics and Paleomagnetism” on a controlled hydraulic press INOVA-1000 of the Geophysical Observatory ”Borok”, IPE RAS with granites of the Voronezh massif and Berea sandstones.
GIS-Based Mapping of Groundwater Potential Zones Using AHP for Ujjain District, Madhya Pradesh, India
Authors: Patidar Nilesh , Mohseni Usman , Pathan Azazkhan , Raaj Saran , Agnihotri Dr. P.G , Jariwala Khushboo , Chandarana Nidhi , Patel Dr. Dhruvesh , Prieto Dr. Cristina , Đurin Dr. Bojan
Published: March 2022

Groundwater is one of the most important natural resources, with quality and quantity fluctuating across space. One of the key sources that contributes to the overall yearly supply is groundwater. Groundwater resources are under significant threat as a result of various factors, including rising population, urbanization, and industrialization. In rural regions, groundwater supplies 80–90% of household water. The fall in groundwater levels is caused by unreliable monsoons and poor-quality surface water supplies. As a result, identifying and delineating the GWPZ that can be used to supplement the groundwater supply is important. The goal of this research is to combine geospatial techniques such as geographic information systems (GIS) and remote sensing (RS) to analyse the groundwater potential in the Ujjain district of Madhya Pradesh, India. To create the GWPZ map, the thematic layers of the primary elements that govern the occurrence and movement of groundwater in hard rock regions were prioritized, weighted, and aggregated in a linear combination equation in the ArcGIS Raster Calculator. In this study area for evaluating groundwater potential zones, a total of nine thematic maps were prepared, such as geology, drainage density, geomorphology, lithology, soil, land use/land cover, elevation, and slope. The weights for the different thematic layers were calculated using a multi-criteria decision-making (MCDM) technique, i.e., the analytical hierarchy process (AHP), that permits pairwise evaluation of criteria influencing the prospective zone. The groundwater potential (GWP) map has also been reclassified into five distinct classes, i.e., excellent, very good, good, moderate, and poor. According to the findings, the excellent potential zone accounts for 1.15% of the total area, with the remaining areas classified as very good (23.21%), good (45.76%), moderate (21.54%), and low (8.35%). A total of 53 well sites are available for the validation of the GWPZ map in the research region. According to our findings, 38 existing wells are in the good and very good potential zones. This suggests that the study's groundwater potential zone map is quite consistent and dependable when it comes to estimating groundwater potential. On the basis of the groundwater potential zone map, a spatial rearrangement of cropping patterns might be recommended. This study is even more essential in an era of drinking water shortages, as the GWPZ map would have been beneficial in water resource planning and management. Future management plans, including natural and artificial recharge practices, may be established successfully in these locations since the approach used yielded reliable analysis.
Comparison of methods for assessing drought risk in beech ecosystem in central Slovakia
Authors: Oravcová Zuzana , Vido Jaroslav
Published: March 2022

Drought, as a consequence of climate change, impacts beech ecosystems on their lower altitudinal limit of occurrence in Slovakia. During the growing season, precipitation deficit and its uneven distribution and rising evapotranspiration demands of ecosystems are significant. In this paper, we evaluate drought risk in the beech ecosystem in Kremnica Mountains (Central Slovakia) firstly from a climatological point of view (Climatic Index of Irrigation, CII) and secondly based on water availability in the soil (Relative Extractable Water, REW), while in the latter case we used drought severity classification for drought episodes. The study aimed to describe drought evolution during vegetation seasons 2017 and 2018 and compare its evaluation methods. Results revealed that CII is sufficient to determinate drought onset in the ecosystem. On the other hand, REW is suitable for accurately describing drought evolution in particular soil horizons and severity of drought determination. Furthermore, since CII is based on climatological data, positive values immediately after precipitation recovery might be inaccurate since soil profile require a certain volume of water over a more extended period for full saturation. Therefore, REW is more precise and suitable for drought evaluation because it considers the amount of water in the soil, closely related to plants' water balance.
Deep learning for recognizing fine detailed crop types using time series satellite radar images
Authors: Shu Qingying , Zhang Ce
Published: March 2022

Crop identification and mapping using satellite remote sensing techniques is critical for agricultural monitoring and management. Distinguishing crops from satellite sensor image can be challenging given the irregular shape of fields, the complex mixture within smallholder farms, the variety of crops, and the frequent land use changes. The advances in satellite sensor techniques and classification algorithms allow us to acquire timely information on crop types at fine spatial scales. State-of-the-art research of crop classification involves the joint use of both optical and microwave satellite imagery.

Our current research aims to develop a recurrent neural network (RNN) for crop classification using Sentinel-1A time series backscatter images. The objectives of our study are to discriminate a wide variety of crops at fine spatial details and to increase the classification accuracy using time series images. A pilot study was performed on an area of the North-western Germany, for which we obtained the Land use registry across the growing seasons in 2018 as the ground reference data.  The area has a maritime influenced climate which is featured by warm summers and mild cloudy winters and flat terrain. The major crops identified include barley, rapeseed, rye, wheat, potatoes. We expect to observe five stages, which are planting, vegetative, reproductive, mature, and harvested stages, in the time-series pixel values of the crop types. The satellite images have been batch processed based on the ESA recommended procedures.  An initial time series analysis was performed on individual pixel values to detect and characterize the changes in different crop types. The next step was to explore the spatial distribution of the crops, i.e., the shape of the parcels. Image segmentation approaches were considered for dividing the image into small parcels for object-based image analysis rather than pixel-based classification. Because of the imbalance number of parcels, we resample pixel within parcels to avoid the problem of underfitting or overfitting.

Our modelling approaches are developed based on the Long Short-Term Memory (LSTM) deep learning models, which transform the temporal and dual-polarization input features into sequential hidden states, generate the output with scores, and then predict the crop types. This study can be extended to lands under similar climate and terrain conditions, and, with contribution to the understanding of the global agricultural system.
A distributed time-lapse camera network on high-arctic Svalbard to track vegetation phenology with high temporal detail and at varying scales 
Authors: Parmentier Frans-Jan W. , Nilsen Lennart , Tømmervik Hans , Cooper Elisabeth J.
Published: March 2022

Near-surface remote sensing techniques are essential monitoring tools to provide spatial and temporal resolutions beyond the capabilities of orbital methods. This high level of detail is especially helpful to monitor specific plant communities and to accurately time the phenological stages of vegetation – which satellites can miss by days or weeks in frequently clouded areas such as the Arctic. Therefore, we established a measurement network that is distributed across varying plant communities in the high arctic valley of Adventdalen on the Svalbard archipelago, with the aim to monitor vegetation phenology. The network consists of ten racks equipped with sensors that measure NDVI (Normalized Difference Vegetation Index), soil temperature and moisture, as well as time-lapse RGB cameras. Three additional time-lapse cameras are placed on nearby mountain tops to provide an overview of the valley. From these RGB photos we derived the vegetation index GCC (Green Chromatic Channel), which has similar applications as NDVI but at a fraction of the cost of NDVI imaging sensors. To create a robust timeseries for GCC, each set of photos was adjusted for unwanted movement of the camera with a stabilizing algorithm that enhances the spatial precision of these measurements. We show how this data can be used to monitor different vegetation communities in the landscape and that this can form the basis for a direct comparison to space-borne observations and further upscaling.
Is it possible to describe the behaviour of per- and polyfluoroalkyl substances (PFAS) and biodegradable precursors using the MACRO model? – Approach and preliminary results.
Authors: Weidemann Eva , Lämmer René , Stahl Thorsten , Göckener Bernd , Bücking Mark , Breuer Jörn , Kowalczyk Janine , Just Hildegard , Boeddinghaus Runa S. , Gassmann Matthias
Published: March 2022

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic substances, which moved to the scientific focus due to their ubiquity in the environment. Several thousands of individual PFAS are known, which differ in chemical structure as well as in their chemical and physical properties. Due to the huge number of substances, the assessment of their environmental behaviour is challenging. Still, more information about these substances, which are partly already declared PBT (persistent, bioaccumulative and toxic), is needed for risk assessments and remediation.

The overall aim of this study was to describe the environmental behaviour in soil during leaching of ten different PFAAs (perfluoroalkyl acids), a group of persistent PFAS, and two diPAPs (polyfluoroalkyl phosphate diesters) with physical equations and parameters to gain knowledge about substance-related characteristics. For this purpose, we simulated the leaching of all surveyed PFAAs and of the biodegradable precursors 6:2 diPAP and 8:2 diPAP, which can transform into PFAAs. Soil and percolation data received from two experimental studies, a laboratory soil column study and a field lysimeter study, were used to evaluate the leaching and transformation behaviour using the MACRO model. In both studies the behaviour of diPAPs were simulated, which enables a comparison between natural and unnatural conditions. Modelling results from the laboratory study, in which climate impacts are limited, were used as input for the field study with natural climatic conditions. Parameters used for calibration were substance-related such as the adsorption distribution coefficient (KD). The amount of non-recovered PFAS, which is potentially related to the formation of non-extractable residues (NERs), was described using a first-order degradation equation. The evaluation of simulations was done using the goodness-of-fit function KGE (Kling-Gupta Efficiency) and a fitting score comparing simulated and observed soil and percolation data. Optimisation was done using the caRamel evolutionary algorithm with multi-objectives within the GNU R environment and up to 15,000 runs per substance, which resulted in a pareto front. Results of parameter values were then used to describe their leaching behaviour as transformation products (PFAAs) of diPAPs in two steps: (1) optimisation of leaching and transformation of diPAPs with soil data, (2) simulation of leaching of transformation products using results of PFAA simulations. The preliminary modeling results are promising for simulating the behavior of PFAAs as well as their precursors with MACRO.
Self-induced incipient `eclogitization' of metagranitoids at closed-system conditions
Authors: Schorn Simon
Published: March 2022

The incipient development of diagnostic high-pressure assemblages –the `eclogitization'– of granitoids, such as plagioclase-breakdown and small-scale formation of garnet and phengite does not require exogenous hydration because unlike dry protoliths like basalt/gabbro or granulite, granitoids s.l. contain crystallographically-bound H2O in biotite. During high-pressure overprint, partial biotite dehydration-breakdown causes a localized increase in the chemical potential of H2O (µH2O). Diffusion of H2O into nearby plagioclase induces the formation of diagnostic eclogite-facies assemblages of jadeite–zoisite–K-feldspar–quartz ± kyanite ± phengite that pervasively replace former cm-sized plagioclase without requiring the participation of free H2O. Depending on P–T evolution, similar textures may involve albite instead of jadeite. Plagioclase-breakdown may also occur due to simple burial because compression leads to an increase of µH2O, without requiring additional influx of H2O at the texture scale. However, diffusion of biotite-derived H2O into plagioclase sites likely favors reaction due to its catalytic effect. In parallel, ~100 µm-thick complementary coronae involving garnet phengite–quartz develop at former biotite–plagioclase/K-feldspar interfaces due to the coupled diffusion of FeO–MgO–H2O from biotite towards feldspars, and minor CaO in the opposite direction. The reaction textures likely create structural weaknesses and preferential fluid pathways, thereby promoting further hydration, deformation and equilibration along the prograde path. If exogenous H2O is introduced, it is accommodated in phengite growing at the expense of igneous K-feldspar and possibly in epidote-group minerals. Upon decompression, such hydrated rocks would dehydrate, thereby favoring fluid-assisted retrogression and loss of diagnostic eclogite-facies assemblages at lower pressure. Whereas the prograde reaction textures are only preserved at closed-system conditions and in the absence of deformation, they are suggested to commonly form during orogenic metamorphism of granitoids and quartzofeldspathic gneisses that dominate the continental crust in high-pressure terranes such as the Western Italian Alps or the Western Gneiss Region (Norway).