bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphometric analysis of channel networks suggests the Jezero system is a fluvial fan rather than a delta
Authors: Gezovich Luke , Plink-Bjorklund Piret , Henry Jack
Published: March 2022

Fluvial fans and river deltas are both fan-shaped landforms that contain complex channel networks. A critical difference between these landforms is that deltas form only along a standing body of water, whereas fluvial fans may form hundreds of kilometers from oceans or lakes. Accurately distinguishing between deltas and fluvial fans is thus critical for identifying paleo-shorelines on planetary bodies. Here we test an ensemble of quantitative methods to differentiate fluvial fans and deltas on Earth, and apply the methodology to Mars. We quantify differences in channel divergence angles, and in downstream changes of channel reach lengths and channel width between the divergence nodes. These differences in channel networks occur because fluvial fans build by channel avulsions, whereas delta build by avulsions as well as mouth bar growth and consequent bifurcations. Bifurcations in deltas form channel divergence angles of approximately 77° and cause a distinct downstream decrease in channel reach length and in channel width at bifurcation nodes. In contrast, avulsions in fluvial fans form considerably smaller channel divergence angles. Down-fan channel narrowing is also not linked to divergence nodes. This initial dataset shows that the methodology is applicable both on Earth and Mars, and that the Jezero system is likely a fluvial fan rather than a delta. These results indicate that channel networks need to be carefully assessed if used for the estimation of the location of paleo-shorelines on planetary bodies, as only deltas systematically occur at shorelines. Alternatively, additional evidence is needed for the presence of shorelines as fluvial fans may also occur at shorelines. On Earth, fluvial fans are less sensitive to sea-level rise and coastal hazards than deltas, due to upstream morphodynamic controls.
Validation of a 1-D lake model for modeling evaporation from an elongated and deep boreal reservoir
Authors: Kallel Habiba , Mackay Murray , Thiboult Antoine , Nadeau Daniel , Anctil François
Published: March 2022

Freshwater reservoirs modify the regional climate through mass, energy, and momentum exchanges with the atmosphere. Recent studies have shown that hydropower reservoirs tend to evaporate more than the land they have flooded, hence reducing water availability for other uses, at a level that should with local climate conditions, however. Knowing that evaporation is a key component of the water balance and that very few studies have focused on evaporation from northern reservoirs, which are ice covered several months per year, there is a real need for models that can provide reliable estimates of this water vapor flux. This project focuses on the modeling of evaporation from an 85-km2 hydropower reservoir located in the boreal biome of eastern Canada (50.7°N, 63.2°W), with a mean depth of 60 m and an elongated shape. To support this modeling effort, two flux towers (one on the shore and one on a raft) and a vertical chain of thermistors were deployed. Exchanges between the water surface and the atmosphere are simulated with the Canadian Small Lake Model (CSLM), a 1-D physical-based surface scheme designed to be coupled with a numerical weather prediction model. The model also simulates the thermal regime of the water body, including ice formation. Considering the irregular shape of the reservoir as well as its depth, a new model parameterization was adopted that improved simulations (albedo parameterization, leakage parameter, mixed layer maximum depth...). Turbulent fluxes were successfully predicted during the open water period. Comparison between observed and modeled time series showed a good agreement specifically for sensible heat fluxes.  Deviations mostly occur before freeze-up (October to November) and around ice off (April to May) with a tendency of overestimating latent heat fluxes when its observed magnitude is small (ice period). Thermal mixing as well as mixed layer deepening were well estimated. Thermal mixing, as well as mixed layer deepening, were well estimated. Near-surface water temperature confirmed the ability of the CSLM to simulate the near-surface seasonal cycle. However, in early fall, an overestimation of the water temperature induced an overestimation of the heat fluxes leading to early depletion of the energy storage that led to an early modeled freeze-up.
Morphometric analysis of volcanic structures using digital elevation models and models developed from radar images in the Apan volcanic field, México.
Authors: Ruiz Sánchez Jesús Octavio , Méndez Serrano Jesús Eduardo , Jácome Páz Mariana Patricia , Ramírez Serrato Nelly , López Váldes Nestor
Published: March 2022

The present project aims to make a preliminary assessment of the volcanic risk represented by the Apan Volcanic Field (CVA). The methodology was divided into two parts. In the first, Digital Elevation Models (DEM) published by official sources were used to identify unreported structures and perform morphometric analysis of previously dated structures. In the second stage, a new DEM was developed from interferometric methodologies to compare the results with those obtained from official sources. Two SAR satellite images from the SENTINEL-1 satellite of ESA's Copernicus program were used. Being the first of October 14, 2021, leader image, and the second of October 26, 2021, slave image. These images were processed in ESA's SNAP software. For the morphometric analysis, volcanic structures have been classified into three major categories: Young cones (0.18 Ma - 0.5 Ma), Intermediate cones (0.5 Ma-1 Ma), and Old cones (1 Ma-3 Ma). From the official DEM analysis, 243 volcanic structures were reported within the study area with a preliminary predominance of structures that fall in the range of old cones, 4 areas with a higher concentration of volcanic structures were detected in which some highly populated localities are found. In addition, demographic parameters were used for a better preliminary risk assessment in the study area. Official and Radar images DEMs were used for the morphometric analysis and the results were compared with the previously published models. Finally, it was concluded the importance of the CVA by comparison with other two Mexican volcanic fields CVA represents a moderate volcanic risk, for which a greater number of studies and monitoring in the area is recommended.  This project provides a new understanding of the volcanic hazard and risk associated with the CVA and the development of the surrounding social environment.
PM10 fluctuation modeling in the Caribbean area using the universal multifractals framework
Authors: Plocoste Thomas , Calif Rudy , Euphrasie-Clotilde Lovely
Published: March 2022

Every year, the Caribbean basin is strongly impacted by sand mists from African deserts. The health impact is significant for the population living there. This is the reason why a better understanding of the behavior of particulate matter that have an aerodynamic diameter less than 10 µm diameter (PM10) is crucial to predict their fluctuations. The aim of this study is to characterize the PM10 fluctuations in the fully developed turbulence framework. For that, this analysis is carried out using PM10 datasets sampled at daily basis during six years period for three Caribbean islands (Martinique–Guadeloupe-Puerto Rico). After a multifractal analysis, the results obtained show that the log-Lévy model is suitable, in comparison to the log normal model, to fit the scaling exponent function ζ(q) and the multifractal spectrum f(α). Under this basis, a PM10 fluctuations characterization for each island is proposed using the three universal multifractal parameters [1,2]. Hence, stochastic simulations can be envisaged to mimic the stochastic behavior of PM10 data.

References

[1] Schertzer, D., Lovejoy, S., 1987. Physical modeling and analysis of rain and clouds by anistropic multiplicative processes. J. Geophys. Res. 92 (D8), 9693-9714.

[2] Schertzer, D., Lovejoy, S., Schmitt, F., Chigirinskaya, Y., Marsan, D., 1997. Multifractal cascade dynamics and turbulent intermittency. Fractals 5 (3), 427-471.
Optimising agri-environmental measures at catchment scale through specific allocation with the SWAT model – A case study in southern Andes of Ecuador
Authors: Rivas-Tabares David , Tarquis Alfonso Ana María , Célleri Rolando
Published: March 2022

Agricultural catchments are prone to high crop yield variability because of extreme weather events, and their impact destabilises agricultural income at different territorial scales. This study aims to use optimisation algorithms coupled with the Soil Water and Assessment Tool – SWAT to allocate specific agri-environmental measures to mitigate the impact of climate change in water fluxes availability at subbasin scale.

The SWAT tool as a semi-distributed model uses the hydrological response unit – HRU concept to split catchments into several territorial management units with similar soil properties, slopes, and land use. The HRUs were used as optimisation unit to change land use and crop management. The work was performed in a catchment located in the southern part of Cuenca city in Ecuador; the area delineates the Tarqui river. The primary land use of the area is grassland-livestock systems and seasonal cropping. Two steps were performed: first, a model run with calibration and validation was set as baseline model. A second step include an optimisation set of modeled scenarios derived from future stakeholder alternatives defined in a previous study as sustainable practices in the area.

Several SWAT model alternatives were optimised, changing crop sequences, fertilisation rates, and crop scheduling dates. As a result, stakeholders' perception majorly matches with scenarios results in optimising water availability during low flow periods increasing streamflow and soil water availability. However, several unexpected alternatives, coming from optimisation, hint at farmers and ranchers. These new options explore other uses and crop sequences that increase income and reduce fertilisation costs.

Acknowledgements

The authors acknowledge support from European Union NextGenerationEU and RD 289/2021 and the support of Project No. PGC2018-093854-B-I00 of the Ministerio de Ciencia, Innovación y Universidades of Spain

References

David Rivas-Tabares, Ana M. Tarquis, Ángel de Miguel, Anne Gobin, Bárbara Willaarts. Enhancing LULC scenarios impact assessment in hydrological dynamics using participatory mapping protocols in semiarid regions. Sci. Total Environ., 803, 149906, 2022. https://doi.org/10.1016/j.scitotenv.2021.149906

Rivas-Tabares, A. de Miguel, B. Willarts and A.M. Tarquis. Self-organising map of soil properties in the context of hydrological modeling. Applied Mathematical Modelling, 88,175-189, 2020. https://doi.org/10.1016/j.apm.2020.06.044
Changjiang sediment discharge to the East China Sea at the time scale of months to years
Authors: Wang Jinlong
Published: March 2022

The riverine derived particles play significant roles in sedimentological and geomorphological processes as well as biogeochemical cycles in estuaries. We collected a suite of water and sediment samples from the Changjiang (Yangtze) Estuary and adjacent East China Sea during to observe variations in the particulate 234Th, 7Be, 210Pb, and 137Cs activities as well as in particle transport, deposition, and resuspension. In the Changjiang Estuary, sedimentary particles in the North Passage experienced net deposition during neap tides whereas those in more seaward areas of the North Passage exhibited net resuspension during spring tides. based on a two-dimensional model of 7Be, 234Th, and 210Pb. Using 7Be/210Pbex and 137Cs/210Pbex activity ratios as tracers, we deduced that most of particles in the North Passage were not derived from the direct deposition of Changjiang input particles but were transported there from sediment deposited offshore. These riverine particles would undergo 3-6 years multiple cycles of deposition-resuspension-transport-deposition-resuspension before eventually buried in the shelf or export from inner shelf. The 7Be/210Pbex ratio indicates a southward transport pathway in spring and northeastward transport pathway in summer. Besides, 210Pb budget in the inner shelf of the ECS show that a small fraction (at most 14% of annual Changjiang sediment discharge in 2011) of particles could be transported offshore. The ratio of the mobile mud inventory of 234Thex/production in the overlying water column of > 2.5 in south inshore indicates that the sediment focusing resulted in the increased mass flux.
The pre-industrial digital elevation model of the Greenland Ice Sheet from the 17th and 18th Centuries  
Authors: Oien Rachel , Nowicki Sophie , Csatho Beata
Published: March 2022

A large uncertainty surrounding the current state of the Greenland Ice Sheet (GIS) and the predictions for future sea-level change stem from a lack of knowledge in the historical boundary and shape of the ice sheet. Prior to the 1970s, the ice sheet is reliant on aerial imagery and digital photographs. To help improve ice sheet model projections, in particular for the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) group, the focus is to provide a historical perspective of the boundaries and thickness. The digital elevation model is built using trim lines, geomorphic mapping, known points of boundary conditions, early explorer records, through a combination of biogeographical, archaeological and geologic records to amalgamate into a historical DEM. As more numerical simulations are based on the same DEM input yet the response time of the ice sheet is slow enough where a pre-industrial DEM would provide insight into the climate-ice sheet interactions of the recent past. Furthermore, this work will provide an observation-based estimate of change to the GIS and has the potential to lead to a calculation of the spatial ice mass loss from previous centuries. This DEM will increase understanding of the spatial extent of the GIS prior to the 20th century which remains crucial for evaluating the reliability of numerical simulations to predict global sea-level rise.
4-D regional ionosphere imaging and SED reconstruction with a new TEC-based ionospheric data assimilation system (TIDAS)
Authors: Aa Ercha , Zhang Shun-Rong , Wang Wenbin , Erickson Philip , Rideout Bill , Coster Anthea
Published: March 2022

Accurately imaging and modeling the 4-D spatial-temporal variation of the Earth's ionosphere has always been a challenging task in the space weather community, since the ionosphere is a highly variable nonlinear system that exhibits not only remarkable climatological variations but also significant weather disturbances. In the past decades, with the ever-increasing availability of GNSS measurements from ground-based receivers and space-borne radio occultation data such as COSMIC, remarkable progress has been made in the data assimilation technique to improve the overall accuracy of ionospheric nowcast and forecast. However, there still exists a strong need to provide a retrospective specification of the storm-time sophisticated four-dimensional electron density gradient with high spatial-temporal resolution so that detailed localized ionospheric variability and weather disturbances could be better reproduced and understood. Recently, we have developed a new TEC-based ionospheric data assimilation system (TIDAS) to issue high-resolution (1o× 1o× 20 km × 5 min) electron density products over the continental U.S., which is built upon the massive GNSS line-of-sight TEC data processed at MIT Haystack Observatory, radio occultation data from COSMIC measurements, Millstone Hill incoherent scatter radar measurements, and JASON TEC data. This new data assimilation product is able to successfully reconstruct the mid-latitude ionosphere density gradients, such as the 3-D morphology and dynamic evolution of storm-enhanced density (SED) plume. This presentation will describe the data assimilation method and some preliminary SED analysis results.
Causality in long-term predictions, past-value problems and a stochastic-deterministic hybrid
Authors: Del Rio Amador Lenin , Lovejoy Shaun
Published: March 2022

Over time scales between 10 days and 10-20 years – the macroweather regime – atmospheric fields, including the temperature, respect statistical scale symmetries, such as power-law correlations, that imply the existence of a huge memory in the system that can be exploited for long-term forecasts. The Stochastic Seasonal to Interannual Prediction System (StocSIPS) is a stochastic model that exploits these symmetries to perform long-term forecasts. It models the temperature as the high-frequency limit of the fractional energy balance equation (fractional Gaussian noise) which governs radiative equilibrium processes when the relevant equilibrium relaxation processes are power law, rather than exponential.

The multivariate version of the model (m-StocSIPS), exploits the space-time statistics of the temperature field to produce realistic global simulations, including realistic teleconnection networks and El Niño events and indices. One of the implications of this model is the lack of Granger-causality: the optimal predictor at gridpoint i is obtained from the past of the timeseries i and cannot be improved using past temperatures from any other location j. This allows to treat predictions for long-memory processes as “past value” problems rather than the conventional initial value approach that uses the current state of the atmosphere to produce ensemble forecasts.

To improve the stochastic predictions, a zero-lag independent (non-stochastic) predictor is needed. Here we use the Canadian Seasonal to Interannual prediction System (CanSIPS), as a deterministic co-predictor. CanSIPS is a long-term multi-model ensemble (MME) system using two climate models developed by the Canadian Centre for Climate Modelling and Analysis (CCCma). The optimal linear combination of CanSIPS and StocSIPS (CanStoc) was based on minimizing the square error of the final predictor in the common hindcast period 1981-2010 using different out-of-sample validations. Global time series and regional maps at 2.5ºx2.5º resolution show that the skill of CanStoc is better than that of each individual model for most of the regions when non-overlapping training and verification periods are used.
Toward a framework for the assessment of the socio-economic impacts of irrigation under variable surface water-groundwater interactions
Authors: Igiraneza Sinyigenga Laetitia , Zarco Armando , Munoz Arriola Francisco
Published: March 2022

A better understanding of surface water (SW) and groundwater (GW) interactions have become indispensable for efficient water management. This study aims to analyze the impact of irrigation on SW-GW interactions. Irrigation in areas where groundwater interacts with surface water is more prone to externalities like water depletion. This paper evaluates the resulting externalities and the associated changes in economic efficiency and irrigation allocation efficiency because of SW-GW interactions. The economic efficiency analysis composes the evaluation of changes in water value and the effectiveness of water rights due to irrigating using water where SW-GW interactions occur. To test the hypothesis that irrigation in hydrologically connected water resources leads to shifts in the water-use value for irrigation, we collected and evaluated evapotranspiration, precipitation, streamflow, and groundwater well-level data in irrigated landscapes in the High Plains US. The objectives are: (1) examine water available for irrigation and the associated changes in discharge (as a proxy to SW-GW interactions); (2) examine the role of water rights, especially on US Winters doctrine, in the presence of variable SW-GW interactions; and (3) carry an economic analysis for the optimal use of water under the occurrence of SW-GW interactions through cost-benefit analysis. This study indicates that by promoting effective water policies and water rights transfers through water markets, the impacts of SW-GW interactions can be lessened. This study provides a deep understanding of the existing policy gaps and gaps in the efficient allocation of water for irrigation due to SW-GW interactions.
Delineating the coastal saline water intrusion zones using Electrical resistivity tomography (ERT) 
Authors: Tiwari Prarabdh , rupesh Rupesh , Sharma Shashi Prakash
Published: March 2022

Seawater intrusion is a major worldwide environmental issue for coastal groundwater resources. Due to natural & human activities, freshwater aquifers are contaminated with saltwater. In the present study, the Electrical Resistivity survey was carried out in Mandarmani, West Bengal, India, to delineate such saltwater intruded zones. It was observed that in the nearby area, many shallow aquifers (around 30m depth) was affected mainly by the salinity problem. ERT results show the signature of saline clay based on significantly less resistivity value. The probable cause of the high salinity problem in this area is excessive use of groundwater resources, Fish farming, Salt industry & recently, a cyclonic effect was observed. 

Keywords: Electrical Resistivity Tomography (ERT), aquifers, saline water intrusion.

 

 

 

 

 
Representing microbial activity in a soil decomposition model
Authors: Ristorp Aas Elin , Koren Berntsen Terje , Eiler Alexander , de Wit Heleen
Published: March 2022

Complex biogeochemical processes involving vegetation, microbial communities, symbiotic relationships and nutrient cycling determines the rates at which carbon is transferred between the atmosphere and the soils, and eventually the terrestrial carbon storage. Because of these complexities, there are still large uncertainties connected to the representation of the terrestrial carbon cycling in Earth System Models.

An emerging approach to deal with these problems is to explicitly represent microbial pools as well as physically and chemically protected soil organic matter in the model. Based on this, we have developed a soil decomposition process model designed to capture and quantify relationships between soil microorganisms and their environment, focusing on high latitude systems. Our aim with this approach is dual: 1) Testing hypotheses in the model before designing field experiments will help to set up experiments that benefits both understanding of the ecology and improving the model and, 2) Incorporating such a model into an ESM will make it possible to validate the model with observations, and to identify possible climate feedbacks related to the soil dynamics.

The model includes the decomposer activity of saprotrophic fungal and bacterial communities and the symbiotic relationship between mycorrhizal fungi and vegetation. We include separate carbon and nitrogen reservoirs for these microbes, as well as for plant litter and soil organic matter. The transfer of C and N between the reservoirs is based on rate equations using various parameterizations found in literature, and is also transported vertically following a diffusion equation.

The model is forced with litter input and climatic variables from the Community Land Model (CLM5). For calibration and validation we use subsets from a large dataset containing soil profile data for ~1000 forested sites in Norway (Strand et al. 2016). Since the sites are distributed over a large area, they cover climatic gradients in both temperature and precipitation.

Comparisons of C and N content between simulations from the new decomposition model, the standard CLM5 and the observations will be presented, as well as sensitivity tests of different parameter choices and impacts of changes in climate forcing.
Local Changes in Rainfall and Streamflow via Quantile Regression Methods and their relationship with the PDO, MJO and ENSO: Application to French Polynesia
Authors: Sichoix Lydie , Tanguy Garance , Benoit Lionel
Published: March 2022

Flooding in the tropical high islands of French Polynesia located in the South Pacific represents a major threat for tens of thousands of people, in particular in coastal urban areas. In this context,  this study aims to assess rainfall and streamflow changes at local scale and daily interval (hourly when data are available) over the Islands of Tahiti and Moorea during the period 1977-2020, and to provide new indicators for integrated water resource management under high anthropogenic pressure, as well as flood risk anticipation, especially over the northwestern urban part of Tahiti.

Our analysis is based on quantile regression combining linear and annual cycle components applied on 18 rain gauge and 2 river discharge time series. Results show a moderate to high decrease of extreme precipitation (percentiles > 0.90) on the western leeward side. This finding is in line with recent studies on trends in precipitation in the Pacific. More surprisingly, we also observe a moderate increase in rainfall for the windward (North-East) and southern areas, as well as an overall decline in streamflow over two watersheds encompassing the urban zone of North-West Tahiti. This last finding is correlated with the precipitation decline in leeward slopes.

The differences in observed rainfall and streamflow trends may be related to differences in forcings involved. To better understand the influence of the regional climate on our hydrometeorological observations, we investigate the modulating effect of the El Niño Southern Oscillation (ENSO), the Madden-Julian Oscillation (MJO) and Pacific Decadal Oscillation (PDO) on rainfall and runoff by testing a fast inference for time-varying quantiles via a flexible dynamic quantile linear approach. Increase and decline in precipitation are tied to respective positive and negative PDO phases.  However, further validation is required to disentangle the short-term influence of different modes of variability contained in distinct time scales.
Quantitative analysis of systemic risk: from traditional collective risk assessment to resilience concept
Authors: Arosio Marcello , Cesarini Luigi , Martina Mario
Published: March 2022

We live in a complex world: today’s societies are interconnected in complex and dynamic socio-technological networks and have become more dependent on the services provided by critical facilities. In coming years, climate change is expected to exacerbate these trends. In this context, systemic risk assessment is a worldwide challenge that institutions and private individuals must face at both global and local scales. The aim of this work is to adapt the traditional risk assessment methodology to the concept of resilience in order to quantify disaster resilience of a complex system by means of the graph (i.e., the mathematical representation of the system element and connections). We showed that is necessary to adapt the traditional risk assessment to resilience concept considering that the consolidaded definition, provided by the United Nations General Assembly in 2017, includes two fundamental features of systemic risk: (1) resilience is a property of a system and not of single entities and (2) resilience is a property of the system dynamic response.

The methodology proposed represents the elements of the system and their connections (i.e., the services they exchange) with a weighted and redundant graph exposed to extreme weather events and societal systems: river and pluvial floods in urban area. The quantitative analysis of systemic risk is characterized by three activities: 1) assess the systemic properties in order to highlight the centrality of some elements; 2) show how each element can dynamically adapt to an external perturbation, taking advantage of the redundancy of the connections and the capacity of each element to supply lost services; 3) quantify the resilience as the actual reduction of the impacts of events at different return periods.

To illustrate step by step the proposed methodology and show its practical feasibility, we applied it to a pilot study: the city of Monza, a densely populated urban environment.
Experimental measurement of kinematic behavior of particle collisions in ambient liquid
Authors: Jiao Jiajun , Zhou Yiyang , An Yi , Liu Qing-quan
Published: March 2022

The collisions of a particle against other particles or walls in the ambient fluid are one of the key processes in debris flow. Understanding the kinematics of this process, especially the role of particle rotation, is of great significance. We conducted a series of experiments studying the kinematics of a free-falling sphere colliding with a flat wall in the ambient fluids. Seven water-glycerol mixtures of different viscosities and densities are used. The kinematic behavior of the sphere is measured using both MEMS and optical techniques. The relationships between the coefficient of restitution (CR), contact time, and the Stokes number (St) are obtained. We found that when the St is greater than the upper critical value (448), the coefficient of restitution is stable at around 0.63. With the decrease of St, the CR drops rapidly before it approaches 0 when St is less than the lower critical value. The rotation process leads to wider distribution of CR. These results implicit the particle-particle collision might be significantly different when the viscosity of the liquid phase in debris flow varies and the particle scale kinematics of the particle phase is not trivial.
A method for 3D mapping of sub-resolution porosity from X-ray tomography images
Authors: Larsbo Mats , Fukumasu Jumpei , Koestel Johannes
Published: March 2022

Sub-resolution pore space is increasingly being accounted for in Lattice-Boltzmann models of water flow and solute transport. However, robust methods to estimate the permeability and porosity of sub-resolution voxels in 3D X-ray images, which are needed for model parameterization are lacking. The grey-value of a voxel in a 3D X-ray tomography image is approximately proportional to the density. Since the density in a voxel depends on the volume fractions of solids, air and water, and the densities of these phases, a grey-value cannot be directly translated to a porosity value. The objective of this study was to develop a reliable method for 3D estimation of sub-resolution porosity in undisturbed soil samples using data obtained from standard industrial X-ray tomography images. To achieve this we used the differences in X-ray attenuation between samples saturated with water and saturated with a potassium iodide (KI) solution.

We collected ten intact soil cores (5.5 cm high, 6.5 cm diameter) in aluminium cylinders from the topsoil of an arable field in south-west Sweden. The samples had a large variations both in soil texture and organic carbon content. The samples were scanned using X-ray tomography after being slowly saturated with water from the bottom. The water was then replaced by a KI solution (30 g I L-1) with a larger X-ray attenuation than water, and the samples were scanned a second time. The grey-values of the resulting 3D images were scaled by the known densities of air, water and aluminium and the images were registered (i.e. spatially aligned). Macropores, sand grains and gravel were then removed from the images. The difference in attenuation between the two final images was then used to calculate the sub-resolution porosity (i.e. the degree of saturation) in all voxels in the remaining image of the soil matrix. Average porosities for individual samples, which were in the range 0,34­–0.45, were significantly correlated to matrix porosities estimated from soil water retention measurements.
Assessment of Extreme Precipitation Indices over India by CMIP6 Models
Authors: Bhuyan Debi Prasad , Salunke Popat , Mishra Saroj Kanta
Published: March 2022

To simulate the extreme precipitation events through GCMs has become a challenge due to discrepancies in spatio-temporal resolution, physics, and parameterization schemes of the models along with deficiencies in the observed datasets. In this study, the performance of 27 CMIP6 models and their Multi model mean (MMM) in simulating extreme precipitation indices has been compared to the observed precipitation datasets (APHRODITE and IMD) over India during JJAS for 1975-2014. Meanwhile, the MMM shows a close agreement in simulating the indices derived from APHRODITE with PCC >0.6 for all indices with higher skill score (0.54), lower NRMSE than IMD. However, the MMM over- (under)-estimate the number of consecutive wet days (total precipitation) with a median relative error of 64% and 160% (5% and 20%) respectively, as compared to APHRODITE and IMD. Which inferred that similar biases still persist in the newly released CMIP6 GCMs with inter-observation dissimilarity in reproducing the indices. In general, the MMM is unable to replicate the very heavy precipitation (R20mm), with negative median relative errors. However, for all three aforementioned precipitation indices the extent of over- and under-estimation is less while comparing against the APHRODITE than IMD. For consecutive dry days (CDD), the MMM over- (under)-estimate over the North west (northern tip and peninsular as well as lee side of Western Ghat) parts of India, where the biases relative to APHRODITE (IMD) is large (less). The MMM simulates precipitation indices well, instead of using individual model. Whereas, the variation of NRMSE values of individual models are less with the exception of CDD and CWD, where the disagreement between the models with observation is large with larger interquartile model range. Comparing the relative errors between the different homogenous regions of India, all the regions are marginally performing good in simulating the different indices except the NW region, which is appended with larger relative error. It was worth noting that the models having higher spatial resolutions simulate the indices realistically with high (low) PCC (NRMSE), whereas the reversal is not valid for the worst performing models.

 

Key Words: Extreme Precipitation, CMIP6, MMM, IMD, APHRODITE
Plagioclase megacrysts from the shallow crystalline mush of the Deccan Traps
Authors: Marzoli Andrea , Tholt Andy , Renne Paul R , Andreasen Rasmus , Spiess Richard , Chiaradia Massimo , Ruth Dawn C , Pande Kanchan
Published: March 2022

We analyzed the mineral composition of Giant Plagioclase Basalt flows from the Deccan large igneous province. In these flows typically occurring at the transition between geochemically distinct volcanic formations, plagioclase occurs as mm-to cm-seized crystals and crystal clots, which sometimes show evidence of high-temperature deformation, as constrained by EBSD analyses. Plagioclase have anorthite contents generally in the range An65-An60, sometimes showing relatively high-An cores (ca. An75). Clinopyroxene has mainly augitic and rarely pigeonitic composition and generally crystallized at shallow depth. Minor and trace element compositions of plagioclase crystals are correlative to those of their host-rocks. Most core-rim profiles of rapidly diffusing elements (e.g., Mg) are flat, suggesting diffusive re-equilibration. On the contrary, slower diffusing elements like K and Fe are zoned in some samples. In particular, Fe shows a marked increase at the crystal rims. Sr isotopic compositions of plagioclase cores are slightly but significantly different from those of the crystal rims and of the surrounding matrix in several samples.

These geochemical and textural characteristics of the analyzed plagioclase suggest that they derived from a crystalline mush crystallized and stored for variably long periods (years to centuries) in the shallow magmatic plumbing system, which was repeatedly flushed and partially deformed by magma rising from deeper levels. Finally, plagioclase-rich magmas became cargos of Fe-rich, dense magmas possibly mobilized by increased CO2 contents heralding the arrival of e mantle-derived magmas.
Use of composite fingerprinting technique to identify sources of fine-sediment deposited in a reservoir
Authors: Xu Mingyang , Zhang Yunqi , Wu Tong , Li Zhaoran , Wang Yong
Published: March 2022

Abstract: Geochemical fingerprinting was used to identify the sources of fine sediments derived from three types of contrasting lithological zones and deposited in a reservoir in a medium-sized catchment over the past 60 years. The impact of grain-size sorting on the source of fine sediments in the reservoir was investigated. Overall, the fine sediment sources identified in the sediment cores indicated changing trends in sediment contribution from the three types of lithological zones during the past 60 years. Although the granite zone covers half of the catchment, has thicker soils, is more prone to soil erosion, and has been subjected to more human disturbance than the limestone and shale zones, it only provided 25% of the fine sediment in the cores. The limestone and shale zones, on the other hand, account for 23% and 15% of the catchment, respectively, but produce 42% and 33% of the fine sediment in the cores. This is due to grain-size sorting in the reservoir system during downstream sediment transit and deposition. These data show that grain-size sorting has had a significant impact on the sediment source. This study provides new insight into the source of sediments deposited in a reservoir system from different lithological zones at the scale of a medium-sized catchment across multi-decadal periods.

 

Keywords: Sediment source; Composite fingerprinting techniques; Reservoir Contrasting lithologies
Optimizing cropping patterns under the influence of climate change
Authors: Pasula Sindhuja Reddy , Gudem Swethu Sree , Gaddam Sai Jagadeesh , Sampath Prasanna Venkatesh
Published: March 2022

The world needs 70% more food by 2050, increasing the pressure on the available water resources. With the climate change threat approaching, the water stress will further be exacerbated that would adversely affect food security. In countries like India, with extensive cultivation of staple crops like paddy, there has been a rapid increase in the total water consumption. At the same time, cultivation of crops such as pulses and millets has not been sufficient to satisfy the nutritional requirements of India’s population. With the increased likelihood of droughts and floods due to the advent of climate change, it becomes imperative to achieve water, food, and nutritional security into the future. This study attempts to optimise cropping patterns to minimise future water requirement, while satisfying the nutritional and caloric requirements of future generations. We perform the analysis for the southern Indian state of Andhra Pradesh, where agriculture depends predominantly on irrigation. To achieve this objective of optimization, we collected bias-corrected climate datasets from three General Circulation Models (BCC-CSM2-MR, INM-CM5-0, MPI-ESM1-2 HR) that include future rainfall and temperature information from 2021 to 2050. Further, we collected crop-wise farm-level data of five major crops in the state - paddy, sugarcane, groundnut, sorghum, and red gram. The irrigation water requirement (IWR) of the selected crops was estimated using FAO’s CROPWAT model under two different scenarios - SSP 245, SSP 585. Further, we developed an optimization model to obtain the optimal cropping pattern that minimises water consumption. Future food requirements in terms of protein and calorie demands and arable land available for cultivation were used as constraints to perform this optimization. Preliminary results indicate that shifting from water-intensive crops like sugarcane to relatively more nutritious crops like red gram and sorghum has the potential to significantly reduce water consumption, while also enhancing the nutritional security of the region. Interestingly, the optimization results indicated that the southern part of the study region required more interventions in terms of crop diversification as compared to the northern part. Such insights could help decision makers to devise holistic policies, enhancing the water-food security under different climate change scenarios. Further, this research could be extended to domains such as economics, ecology, and energy to achieve overall sustainability in the agricultural sector.
Towards fully automated root phenotyping in the field: from Minirhizotron image acquisition to data analysis 
Authors: Zhou Kaining , Soffer Adam , Ephrath Jhonathan E. , Hadar Ofer , Lazarovitch Naftali
Published: March 2022

Root phenotyping in the field remains challenging from root imaging to data analysis since each part of this process is time-consuming and labor-intensive. Extensive efforts have been taken to explore the possibility to automate parts of this process. However, few studies have provided an integrated solution to make the whole process in a manner of low cost, automated, and customizable for different tasks.  In this study, we have worked towards this goal. A newly designed root imaging system called RootCam addresses the above-mentioned limitations. RootCam moves a small camera with fully automated operations for long-term in-situ monitoring. It captures high-resolution root images (2592 x 1944 pixels). These images are saved to a “Raspberry Pi” device which is accessible by a network cable allowing users to control the system remotely. Users can also control time intervals between runs and set image capturing either overlapped or non-overlapped. This camera was tested in a net house by imaging bell pepper roots which shows superior performance over commercial minirhizotron systems. A deep convolutional neural networks (CNN) model was developed to detect plant roots and calculate root length. This model was trained and calibrated with a dataset of ~18,000 tomato root images and has been used for calculating bell pepper root length on 832 images. The high correlation coefficient (R2 = 0.854) between the measurements from the automated and manual methods proved that our model is able to generalize well over different crop roots. However, the model underestimates root length when there are many roots in an individual image. In summary, the platform we developed to automatize minirhizotron image acquisition and analysis has the promising potential to benefit both the root research community via accelerating high throughput root phenotyping in the field for root studies and farmers via making real-time root development information available for decision making.
Rapid Permafrost Thaw Removes Nitrogen Limitation Rising the Potential of N2O Emissions 
Authors: Wegner Rica , Fiencke Claudia , Knoblauch Christian , Sauerland Lewis , Beer Christian
Published: March 2022

Previous research was addressed to carbon emissions after permafrost thaw, but less attention was paid to changes in nitrogen availability and N2O emissions and in particular data from the Russian Arctic are scarce. Rise in water temperature and sea-level contribute to coastal erosion accelerating thaw rates and the release of dissolved nitrogen. Already 78% of the coastal regions of the Laptev Sea are affected by rapid permafrost thaw. This study estimates whether eroded Arctic coasts are hotspots for N availability and N2O emissions and to further understand the impact of NO3- leaching. Therefore, we estimated N-transformation rates and greenhouse gas (GHG) production (CO2, CH4, N2O) by incubating non-vegetated and revegetated soil samples from a retrogressive thaw slump in the Lena River Delta, Siberia. Within the thaw slump we found at exposed thaw mounds a domination of DIN over DON and an accumulation of NO3- with up 110 µg N (g DW)-1 within the growing season and in the presence of vegetation. Those results are contracting to what is normally reported in Arctic regions. Our incubations indicate that thaw mounds are hotspots for N-mineralization and N2O release (up to 390 ng N2O-N (g DW)-1) via denitrification while at the slump floor denitrification was substrate limited. Substrate limitation is rather caused by soil moisture and pH value than by functional limitation, since in our incubation N-mineralization could proceed in all samples. Simulated NO3- leaching removed the substrate limitation of the denitrification and converted the slump floor to a significant N2O hotspot (410 ng N2O-N (g DW)-1).

Our results emphasise that it is necessary to consider geomorphology and landscape processes to identify hotspots of gaseous and dissolved N loss. A higher availability of inorganic nitrogen in coastal zones will have effects on marine ecosystems and more in depth-studies are needed to characterise seasonality of nitrogen leaching by melt water and eroded sediments.
Lightweight embedded DSLs for geoscientific models.
Authors: Piotrowski Zbigniew , Caviedes Voullieme Daniel , Hokkanen Jaro , Kollet Stefan , Stein Olaf
Published: March 2022

On the map of the ESM research and operational software efforts, a notable area is occupied by the mid-size codes that benefit from established code design and user base and are developed by the domain scientists. Contrary to the major operational frameworks and newly established software projects, however, developers of such codes cannot easily benefit from novel solutions providing performance portability, nor have access to software engineering teams capable to perform full code rewrite, aiming at novel hardware architectures. While evolving accelerator programming paradigms like CUDA or OpenACC enable reasonably fast progress towards execution on heterogenous architectures, they do not offer universal portability and immediately impair code readability and maintainability. In this contribution we report on a lightweight embedded Domain Specific Language (eDSL) approach that enables legacy CPU codes to execute on GPU. In addition, it is minimally invasive  and maximizes code readability and developer productivity.  In the implementation, the eDSL serves as a front end for hardware dependent programming models, such as CUDA. In addition, performance portability can be achieved efficiently by implementing parallel execution and memory abstraction programming models, such as Kokkos as a backend. We evaluate the adaptation process and computational performance of the two established geophysical codes: the ParFlow hydrologic model written in C, and the Fortran-based dwarf encapsulating  MPDATA transport algorithm. Performance portability is demonstrated in the case of ParFlow. We present scalability results on state-of-the-art AMD CPUs and NVIDIA GPUs of JUWELS booster supercomputer. We discuss the advantages and limitations of the proposed approach in the context of other direct and DSL-based strategies allowing for exploitation of the modern accelerator-based computing platforms.