bluuebunny/crossref_metadata_2025 huggingface dataset:
Reductions in photosynthetic nitrogen demand due to elevated CO2 increases simulated future ecosystem carbon storage
Authors: Smith Nicholas , Zhu Qing , Keenan Trevor , Riley William
Published: March 2022

Photosynthesis is the largest flux of carbon between the atmosphere and Earth’s surface and is driven by proteins that require nitrogen. Thus, photosynthesis is a key linkage between the terrestrial carbon and nitrogen cycles, and the representation of this linkage is  critical for coupled carbon-nitrogen land surface models. Most models use a scheme that assumes that photosynthetic nitrogen is driven by soil nitrogen availability. This contributes to projected future reductions in the CO2 fertilization of photosynthesis, as this fertilization becomes limited by nitrogen availability. However, recent results suggest that photosynthetic nitrogen is determined by leaf nitrogen demand, which is set by aboveground conditions, and that future increases in temperature and atmospheric CO2 should reduce photosynthetic nitrogen demand. Here, we used recently developed photosynthetic optimality theory to incorporate the effect of reduced photosynthetic demand for nitrogen into the land surface component of the Energy Exascale Earth System Model (ELM). We simulated land surface processes under future elevated CO2 conditions to 2100 using the RCP 8.5 scenario. Our simulations showed that photosynthesis increases under future conditions, but leaf nitrogen declines. This nitrogen savings led to an increase in simulated leaf area, which increased GPP and ecosystem carbon in 2100. These results suggest that land surface models may overestimate future nitrogen limitation of photosynthesis if they do not incorporate future reductions in photosynthetic nitrogen demand.
Application of Remote Sensing and GIS to Assess Snow Cover and its Dynamics: A Case Study of Uttarakhand Himalaya, India
Authors: Pandey Arvind , Parashar Deepanshu , Palni Sarita , Singh Ajit Partap
Published: March 2022

The cryosphere plays a vital role in the climate system by changing the energy and mass transfer between the atmosphere and the surface, and it is the most important land cover type in the Himalayan and Polar Regions, which act as an important source of freshwater for rivers. This study examines Snow-Covered Area (SCA) and Snowline variations in the Uttarakhand Himalaya using the Normalized Difference Snow Index (NDSI). Three Landsat series imagery for 1990, 2000, 2010, and Sentinel Data from 2015 to 2021 were processed and analyzed through open-source software. In order to estimate the average elevation of the snowline, a digital elevation model was used and an area estimation study using multispectral imagery. The research focuses on the snowline and snow cover variations over the Uttarakhand Himalaya from 1990 to 2021 and the average snow line-height, respectively. This study shows that in the years 1990, 2000, 2010, and 2015 to 2021, snow line variations and area estimation differences in Uttarakhand, Central Himalaya, and snow line at above sea level (a.s.l.) in the western and eastern part of the study area. This study deals with the analysis of snow line shifting and cover. It suggests that the snow cover area in the Uttarakhand, Central Himalaya, is depleting steadily, which will have adverse impacts, especially upon water resources causing various economic and social disruptions in the near future.
Evaluating long range middle atmospheric variability for global infrasound monitoring
Authors: Le Pichon Alexis , Ceranna Lars , Listowski Constantino
Published: March 2022

Global scale infrasound observations confirm that the detection capability of the International Monitoring System (IMS) deployed to monitor compliance with the Comprehensive Nuclear-Test ban Treaty (CTBT) is highly variable in space and time. Previous studies estimated the radiated source energy from remote observations using empirical yield-scaling relations accounting for the along-path stratospheric winds. However, these relations simplified the complexities of infrasound propagation as the wind correction applied does not account for an accurate description of the middle atmosphere along the propagation path. In order to reduce the variance in the calculated transmission loss, massive frequency and range-dependent full-wave propagation simulations are carried out, exploring a wide range of realistic atmospheric scenarios. Model predictions are further enhanced by incorporating fine-scale atmospheric structures derived from a two-dimensional horizontal wave number spectrum model. A cost-effective approach is proposed to estimate the transmission losses at distances up to 8,000 km along with uncertainties derived from multiple gravity wave realizations. In the context of the future verification of the CTBT, this approach helps advance the development of network performance simulations in higher resolution and the evaluation of middle atmospheric models at a global scale with limited computational resources.
Exploring Algorithmic Justice and Planetary Science with Families from Diverse Migration Backgrounds
Authors: Brown Autumn
Published: March 2022

Tech Scéal, an Irish initiative, exploring algorithmic justice, robotics, and the future of planetary science with migrant and refugee families. The topics and approaches were directly informed by the learners themselves through informal discussions held during the plenary period of the project. From these conversations, a series emerged which focused on creative coding and robotics as cultural tools and ways to imagine, create, and claim a more just and joyful technological future. Grounded in story work and a based on a role playing tabletop gaming format, learners set out to remake relationships with with technology in a way that leveraged and contributed to the cultural practices of their communities. This research project also supported playful intergenerational learning opportunities during the pandemic, where families could gather online to share stories and create new knowledge around subjects of personal interest. Results including the impacts on the identity, attitudes, and learnings of participants will be shared as well as key takeaways of working with participants from diverse migration backgrounds.
Possible geomorphic indicators of methane emission in three Martian impact craters
Authors: Mariani Elettra , Allemand Pascal
Published: March 2022

Methane has been detected these last years in the Martian atmosphere both from orbit (TGO-ExoMars mission - still active) and from ground (Curiosity rover – Mars Science laboratory mission). The sources of methane remain undetected. As the life time of methane in the Martian atmosphere should be less than few months, these sources are currently active at the Martian surface. The localization and the geometry of these sources remain an open question. Emission centers could be localized in peculiar zones on which it is possible to detect methane. Methane could also be emitted in wide areas and be locally concentrated by atmospheric processes. The aim of this study is to compare the geology and geomorphology three impact craters (Gale, Gusev and Vernal) in which methane has been detected from orbit and/or from ground. Satellite and in situ hyperspectral data (for Gusev, hyperspectral data from Spirit - for Gale, data from Curiosity), as well as high-resolution Context Camera (CTX) and HiRISE images (MRO mission) were also considered. Digital Elevation Models (DEM) were calculated from the highest resolution images that are available. Geomorphological maps were drawn for each crater through GIS projects. For each crater, the possible areas of emission are defined from criteria defined on terrestrial analogs located in Chile and Antarctica. Differences and similarities between the three selected craters are discussed.
Application of biochar to irrigated technosoils: Effects on germination and agronomic properties
Authors: De la Rosa José María , Campos Paloma , Santa-Olalla Arturo , Sanchez-Martín Águeda , Miller Ana , Fernández-Boy Elena
Published: March 2022

Today's agriculture faces the challenge of safely feeding a growing population. This situation generates additional pressures on the environment such as increased organic waste generation, irrigated cropland and the consumption of mineral fertilizers. Moreover, in the present context of global warming, it is necessary to transform the linear economy into a circular economy, in which organic waste should be valorized and greenhouse gas emissions reduced. During the last decade the transformation of organic waste into biochar, the carbon-rich material produced during pyrolysis of biomass to be applied as soil ameliorant [1], to increase the amount of pyrogenic C at soils have been developed [2]. Here, green compost and biochar were produced from contrasting agricultural wastes and applied at greenhouse under limited irrigation conditions.

Results showed that raw material, together with the pyrolysis conditions, determined physical properties of biochars, and thus its performance as soil amendment. In all cases, an increase in the pyrogenic carbon content and a general improvement in the physical properties of agronomic interest of the technosoils were observed. However, the use of high doses of olive-pomace biochar negatively affected the germination due to its high salinity.

Biochar, although beneficial, is therefore not a universal solution and must be characterized, have the appropriate properties and be applied in a specific way to correct specific soil deficiencies.

Acknowledgements: The BBVA foundation is gratefully acknowledged for funding the scholarship Leonardo to “Investigadores y Creadores Culturales 2020” (Proyecto realizado con la Beca Leonardo a Investigadores y Creadores Culturales 2020 de la Fundación BBVA).

References:

[1] Campos, P., Miller, A., Knicker, H., Costa-Pereira, M., Merino, A., De la Rosa, J.M., 2020. Waste Manag., 105, 256-267.

[2] De la Rosa, J.M., Rosado, M., Paneque, M., Miller, A.Z., Knicker, H., 2018. Sci. Tot. Environ., 613-614, 969-976.
Mineral fibers in restoration work. Looking for avoiding health problems.
Authors: Pereira Lola , López Ana Jesús , Ramil Alberto
Published: March 2022

The World Health Organization defines asbestos as fibers with a length (L) ≥ 5 μm, a diameter (D) < 3 μm and L/D ratio > 3. When talking about hazards related to mineral fibers and asbestos, the general concern focuses on workers at quarries, extracting the material. However, there are historic buildings and monuments built on rocks containing these fibers (e.g. serpentinite, soapstone) that due to their artistic interest or links to the architectonic heritage may need to be cleaned at some point for restoration reasons. In this sense, laser cleaning is being more and more widely used in restoration. Although, in general, it is a very selective and controllable technique that allows the removal of fine layers of material (different types of crusts or patinas) with hardly any effect on the rock substrate, laser cleaning activities on this kind of fibrous materials can generate a potentially hazardous dust that, if not protective actions are taken, may affect the heath of workers, that can be from technicians to artists to scientists developing cleaning tools. Regarding the latter, we have arranged an experiment to test how much of this powder can be retained in a “homemade” filter, coupled to a laser equipment. The idea is to work with a laser in the same way a worker on restoration would do to clean a building made of, for example, serpentinite, and observe the fibers that are retained by the filter. Combination with other tools like petrographic and electronic microscopy can be used for the sake of human health.
Atmospheric energy spectra in global kilometre-scale models
Authors: Stephan Claudia , Duras Julia , Harris Lucas , Klocke Daniel , Putman William M. , Taylor Mark , Wedi Nils P. , Žagar Nedjeljka , Ziemen Florian
Published: March 2022

Eleven 40-day long integrations of five different global models with horizontal resolutions of less than 9 km are compared in terms of their global energy spectra. The method of normal-mode function decomposition is used to distinguish between balanced (Rossby wave; RW) and unbalanced (inertia-gravity wave; IGW) circulation. The simulations produce the expected canonical shape of the spectra, but their spectral slopes at mesoscales, and the zonal scale at which RW and IGW spectra intersect differ significantly. The partitioning of total wave energies into RWs an IGWs is most sensitive to the turbulence closure scheme and this partitioning is what determines the spectral crossing scale in the simulations, which differs by a factor of up to two. It implies that care must be taken when using simple spatial filtering to compare gravity wave phenomena in storm-resolving simulations, even when the model horizontal resolutions are similar. In contrast to the energy partitioning between the RWs and IGWs, changes in turbulence closure schemes do not seem to strongly affect spectral slopes, which only exhibit major differences at mesoscales. Despite their minor contribution to the global (horizontal kinetic plus potential available) energy, small scales are important for driving the global mean circulation. Our results support the conclusions of previous studies that the strength of convection is a relevant factor for explaining discrepancies in the energies at small scales. The models studied here produce the major large-scale features of tropical precipitation patterns. However, particularly at large horizontal wavenumbers, the spectra of upper tropospheric vertical velocity, which is a good indicator for the strength of deep convection, differ by factors of three or more in energy. High vertical kinetic energies at small scales are mostly found in those models that do not use any convective parameterisation.
Different strategies in attempting nuclear waste disposal – A comparative study based on four countries
Authors: Basumallik Jayjayanti , Rühaak Wolfram , Schreurs Miranda
Published: March 2022

Across the world, about thirty countries are generating power from nuclear energy, but adopting different strategies to deal with high-level radioactive waste (HLW) produced during the process. A brief comparative analysis of four countries, namely, Finland, Germany, China, and India, is conducted in order to understand the key geopolitical, technical, and social factors that drive these different strategies. There are significant differences in their preparedness related to planning and implementing a final disposal facility for the HLW in deep geological repositories. The research explores the extent of public awareness and acceptance of the nuclear waste management strategies in these four countries. Of special interest is the scope of public participation in the decision-making process related to repository site-selection, and the safety assurances of the proposed HLW disposal techniques. The analysis finally delves into the subject of protracted timelines of the ongoing HLW management projects and the associated challenges.
Geological imaging of a crustal-scale seismogenic source in the continental crust (Bolfin Fault Zone, Atacama Fault System, Chile)
Authors: Masoch Simone , Fondriest Michele , Gomila Rodrigo , Jensen Erik , Magnarini Giulia , Espinosa Javier , Hofer Karin , Mitchell Tom , Cembrano José , Pennacchioni Giorgio , Di Toro Giulio
Published: March 2022

Fault zone architecture controls, for instance, the nucleation, propagation and arrest of individual seismic ruptures, the moment magnitude of the mainshocks and the evolution in space and time of foreshock and aftershock seismic sequences. Nevertheless, the architecture of crustal-scale seismogenic sources is still poorly known. Here, we examine the architecture of the >40-km-long, Mesozoic seismogenic Bolfin Fault Zone (BFZ) of the Atacama Fault System (Northern Chile). The exceptionally well-exposed BFZ cuts through plutonic rocks of the Coastal Cordillera and was seismically active at 5-7 km depth and ≤ 300 °C in a fluid-rich environment. The BFZ includes multiple fault core strands consisting of chlorite-rich cataclasites-ultracataclasites and pseudotachylytes, surrounded by chlorite-rich protobreccias to protocataclasites over a zone as wide as 75 m. These cataclastic units are associated with a damage zone, up to 150-m-thick, which comprises strongly altered and brecciated rock volumes, and with clusters of epidote-rich fault-vein networks located at the linkage of the BFZ with other faults. The architecture of the BFZ is the result of fault core widening by cyclic co-seismic frictional melting and post-to-inter-seismic fault healing due to hydrothermal (chlorite + epidote ± K-feldspar) mineral precipitation plus pervasive, possibly associated with mainshocks and aftershocks, damaging of the surrounding rocks. Additionally, we interpret the epidote-rich fault-vein networks as an exhumed seismic source of fluid-driven earthquake swarm-type sequences in agreement with seismological observations of presently active magmatic and hydrothermal regions. 
Hemispheric asymmetries in recent changes of the stratospheric circulation
Authors: Ploeger Felix , Garny Hella
Published: March 2022

Despite the expected opposite effects of ozone recovery, the stratospheric Brewer-Dobson circulation (BDC) has been found to weaken in the Northern hemisphere (NH) relative to the Southern hemisphere (SH) in recent decades, inducing substantial effects on chemical composition. We investigate hemispheric asymmetries in BDC changes since about 2000 in simulations with the transport model CLaMS driven with different reanalyses (ERA5, ERA-Interim, JRA-55, MERRA-2) and contrast those to a suite of free-running climate model simulations. We find that age of air increases robustly in the NH stratosphere relative to the SH in all reanalyses considered. Related nitrous oxide changes agree well between reanalysis-driven simulations and satellite measurements, providing observational evidence for the hemispheric asymmetry in BDC changes. Residual circulation metrics further show that the composition changes are caused by structural BDC changes related to an upward shift and strengthening of the deep BDC branch, resulting in longer transit times, and a downward shift and weakening shallow branch in the NH relative to the SH. All reanalyses agree on this mechanism. Although climate model simulations show that ozone recovery will lead to overall reduced circulation and age of air trends, the hemispherically asymmetric signal in circulation trends is small compared to internal variability. Therefore, the observed circulation trends over the recent past are not in contradiction to expectations from climate models. Furthermore, the hemispheric asymmetry in BDC trends imprints on the composition of the lower stratosphere and the signal might propagate into the troposphere, potentially affecting composition down to the surface.
In situ low-degree melts in peridotite xenolith from Majuagaa kimberlite, West Greenland
Authors: Kiseeva Ekaterina S. , Kamenetsky Vadim S. , Nielsen Troels F. D.
Published: March 2022

Mantle xenoliths provide a clear evidence of interaction with low-degree mantle melts, however, this evidence is mostly geochemical, manifested by incompatible element enrichment, or mineralogical, manifested by already crystallised phases (e.g. amphibole, phlogopite) as a result of this interaction.

Despite decades of research, the composition of low-degree melts generated in lithospheric mantle are still not very well-known. In situ characterisation of such melts is hampered due to their modification during the ascent as well as rapid alteration and weathering at the surface, while experiments are hampered by difficulties to produce and analyse very low-degrees (<2-3%) melts.

In this study we report a rare sample of well-preserved low-degree melts within a peridotite xenolith GGU473178 from Majuagaa kimberlite in West Greenland. We report alkali-carbonatitic-chloride melt pools and veins that may represent primary low-degree partial melts and products of their in situ crystallisation.

Melt pools are largely composed of carbonate (predominantly dolomite) and contain spinel, apatite, phlogopite as well as minor amounts of Fe-Ni sulphides, barite and halite.

Euhedral crystals of spinel present in these melt pools contain large usually round aggregates of mineral inclusions, which we explain as former melt pools captures by spinel. Mineral assemblage found in these spinel inclusions is consistently composed of ferropericlase, dolomite, alkali-rich carbonate and apatite, which is indicative of a strongly silicate-undersaturated alkali-carbonatitic melt that contains chlorine and phosphorous. Due to the almost complete absence of SiO2, ferropericlase (instead of olivine) crystallises in equilibrium with dolomite and alkali-rich carbonate, implying incredibly low degrees of melting, when essentially only carbonated component is melted, or carbonate-silicate liquid immiscibility, previously reported for spinel lherzolite and garnet wehrlite xenoliths (Frezzotti et al., 2002; Soltys et al., 2016).

References

Frezzotti, M. L., Touret, J. L. R., and Neumann, E. R., 2002, Ephemeral carbonate melts in the upper mantle: carbonate-silicate immiscibility in microveins and inclusions within spinel peridotite xenoliths, La Gomera, Canary Islands: European Journal of Mineralogy, v. 14, no. 5, p. 891-904.

Soltys, A., Giuliani, A., Phillips, D., Kamenetsky, V. S., Maas, R., Woodhead, J., and Rodemann, T., 2016, In-situ assimilation of mantle minerals by kimberlitic magmas — Direct evidence from a garnet wehrlite xenolith entrained in the Bultfontein kimberlite (Kimberley, South Africa): Lithos, v. 256-257, p. 182-196.
Predicting the risk of groundwater nitrate contamination using machine learning tools
Authors: Huang Xin , Jin Menggui , Liang Xing , Su Jingwen , Ma Bin
Published: March 2022

Nitrate contamination in groundwater is affected by both anthropogenic activities and natural conditions, becoming one of the most prevalent problems worldwide. In this study, several machine learning methods including decision tree (DT), k nearest neighbors (KNN), logistic regression (LR), support vector machine (SVM), and extreme-gradient-boosted trees (Xgboost) were applied to predict the risk of groundwater nitrate contamination (NO3- > 50 mg L-1) in the riverside areas of lower reaches of Yangtze River, east China. The developed model included 13 hydrochemical parameters (K+, Na+, Ca2+, Mg2+, Cl-, SO42-, NH4+, NO2-, Fe, Mn, As, Sr, pH) and well depth as explanatory variables, and a total of 1089 groundwater samples. The results showed the hydrochemical dataset could effectively predict the risk of nitrate contamination, with a minimum accuracy of 82.7% in LR and maximal accuracy of 91.7% in SVM and Xgboost. However, only the Xgboost model under a cutoff probability of 0.3 had the best performance with the highest sensitivity of 80.3% and AUC 0.95, whereas other models had sensitivity lower than 60% with insufficient capability of identifying contaminated groundwater samples. The results showed that the ensemble learning method had a strong, robust prediction capability. In addition, the relative importance of K+, SO42-, and Cl- exceeded 0.65, indicating the dominant influence of domestic or industrial sewage in the study area due to widespread urbanization. Finally, we examined the relationship among nitrate contamination risk, land use type, the intensity of anthropogenic activities, and redox conditions and obtained the risk map of nitrate contamination in the study area. This study successfully proved the validity of predicting the risk of groundwater nitrate contamination using machine learning tools, which favors regional groundwater management and protection.

Keywords: groundwater; nitrate contamination; risk prediction; machine learning
Influence of topography on Tibetan Plateau snow cover simulations in land surface modeling
Authors: Miao Xin , Guo Weidong , Xue Yongkang , Sun Shufen
Published: March 2022

The Tibetan Plateau (TP) is the highest plateau in the world and has complex topography. On the TP, seasonal snow cover is widespread in different topographic areas, but the influence of topography on snow cover simulations is often ignored in most land surface models. In this study, the relationships among the snow cover fraction (SCF) and complex topography are investigated over the TP based on satellite observations. The standard deviation of topography is used as an index to describe the topographic complexity. We conduct 12 numerical experiments using the Simplified Simple Biosphere Model version 3 (SSiB3) to investigate the influence of topography on the snow cover simulations. Our results show that ignoring topography leads to significant SCF simulation biases. By adding a topographic factor to the original scheme, the SCF simulations are greatly improved. Compared with the simulation results of the default SCF scheme, the annual mean SCF bias at location at CMA stations is reduced from 3.833% to -0.097% by adding a topographic factor. The improved SCF simulations further lead to reduced biases in winter surface albedo and land surface temperature simulations. Compared with in situ observations, the winter surface albedo bias over the TP is reduced from 0.02 to 0.007 compared with GLASS albedo data, and the winter land surface temperature bias is reduced from -3.43 K to -3.04 K. This study highlights the importance of the topographic effect in simulating snow and energy exchanges between the land and atmosphere over the TP, and it can contribute to reducing the “cold bias” in winter climate simulations over the TP.
Spatio-temporal variation of transparent exopolymer particles (TEP) and their sinking flux in a temperate bay: Jiaozhou Bay, China
Authors: Guo Shujin , Zhao Yongfang , Zhu Mingliang , Liang Junhua , Du Juan , Sun Xiaoxia
Published: March 2022

This study investigates transparent exopolymer particles (TEP) distribution, seasonal variability and its sinking flux in a shallow coastal sea, Jiaozhou Bay, China. The TEP concentrations in the bay ranged from 75 to 553 μg xanthum gum equivalents per liter (Xeq. L-1), which was within the range of values reported in other coastal seas. Spatially, high levels of TEP were always observed in the northern bay during all four seasons. In the southern and outer bay, TEP levels were relatively low. Significant positive correlations were observed between TEP and chlorophyll a during spring, summer and fall, suggesting that phytoplankton was the primary source of TEP during these three seasons. Seasonally, TEP concentrations were highest in summer (mean = 275 ± 142 μg Xeq. L-1), followed by winter (mean = 209 ± 53 μg Xeq. L-1), and lowest in spring (mean = 142 ± 43 μg Xeq. L-1) and fall (mean = 180 ± 49 μg Xeq. L-1). High phytoplankton biomass and temperature contributed to the high TEP levels in summer, while the relatively high amount of TEP in winter was most probably derived from re-suspension of sedimentary particles. For the whole year, TEP carbon (TEP-C) contributed to a mean of ~26% of POC in the bay, representing the second most important contributor to POC pool after phytoplankton (mean: 38%). Sinking flux of TEP was measured with sediment trap, and the results revealed that sinking TEP contributed to a mean of 20% of total POC flux for the four seasons in the bay. This study highlights the fact that TEP-C could represent a significant fraction of the POC pool in the coastal sea, and their sedimentation could play an important role in the carbon sedimentation in these areas.
Modeling the translocation and transformation of chemicals in the soil-plant continuum: a dynamic plant uptake module for the HYDRUS model
Authors: Brunetti Giuseppe , Šimůnek Jirka , Kodešová Radka
Published: March 2022

Soil pollution from neutral and ionizable compounds poses a significant threat to water resources management and food production. The development of numerical models to describe their reactive transport in the soil-plant domain is of paramount importance to elaborate mitigation strategies. However, most existing models simplify the description of physicochemical processes in soil and plants, mass transfer processes between soil and plants and in plants, and transformation in plants. To fill this scientific gap, we first coupled the widely used hydrological model, HYDRUS, with a multi-compartment dynamic plant uptake model, which accounts for differentiated multiple metabolization pathways in plant’s tissues. The model, which is able to simulate the reactive transport of neutral compounds, has been successfully validated against experimental data, and integrated in the Graphical User Interface of the HYDRUS software suite. To further extend its domain of applicability, we have recently adapted its theoretical framework to simulate the translocation of ionizable compounds. The new modeling framework connects a biophysical multi-organelles model to describe processes at the cell level with a semi-mechanistic soil-plant model, and accounts for dissociation processes and electrical interactions with cell biomembranes. Validation against experimental data showed encouraging results and opens new perspectives for its use for predictive and explanatory purposes.

 

References

Šimůnek, J., G. Brunetti, and R. Kodešová, Modeling the translocation and transformation of chemicals in the soil-plant continuum: A dynamic plant uptake module for the HYDRUS model, AGU Annual Meeting, ID 810092, New Orleans, Louisiana, December 13-17, 2021.
Temporal and spatial variation of soil erosion rate in the Loess Plateau and its main controlling factors in the past 40 years
Authors: Huang Chenlu , Yang Qinke
Published: March 2022

Soil erosion is a very complex physical and geographical phenomenon, which is affected by both natural and human activities. Based on theoretical and technical methods such as CSLE model, Classification and Regression Tree (CART) and Google Earth Engine (GEE), on the basis of obtaining medium and high resolution soil erosion factors, this study systematically analyzed the temporal and spatial variation of soil erosion rate on the Loess Plateau in the past 40 years and the changes of the main controlling factors of soil erosion before and after “returning farmland to forest (grass)”. The main conclusions are as follows: (1) The soil erosion rates of the Loess Plateau in 1980, 1990, 2000, 2010, and 2017 were 2207.57, 1725.13, 981.18, 727.79, and 640.00 t/(km2∙a), showing a decreasing trend overall. As the most serious soil erosion area on the Loess Plateau, the Loess Hilly and Gully region has a significant weakening trend in its soil erosion rate, but its five-phase average soil erosion rate is still more than twice the average of the whole region, 4414.77, 3485.19, 1884.37, 1296.21, 1135.04 t/(km2∙a). (2) Before returning farmland to forest (grass) (before 1999), rainfall erosivity (R) was the main controlling factor for soil erosion. After the large-scale implementation of various soil and water conservation measures, the influence of biological measures (B) on soil erosion rate increased; in the sandy region of the Loess Plateau dominated by low-coverage grasslands, soil erosion was significantly affected by rainfall erosivity (R). The main controlling factors of soil erosion in the loess hilly and gully area changed significantly around 2000, from the combined effect of terrain (LS) and vegetation (B) to the combined effect of rainfall erosivity (R), gully erosion factor (g) and vegetation (B). (3) The average soil erosion rate under different land use types on the Loess Plateau is characterized by cultivated land>grassland>forest land. From 1980 to 2017, the soil erosion rate from cultivated land to forest land decreased the most, and the change slope was -74.84 (t/(km2∙a))/a, followed by cultivated land to grassland and grassland to forest land, both of which changed the slope of soil erosion. They are -51.88 (t/(km2∙a))/a and -49.05 (t/(km2∙a))/a, respectively. This research can provide a scientific basis for the needs of future comprehensive management planning and soil and water conservation construction in the basin.
Do we need to consider electrons’ kinetic effects to properly model a planetary magnetosphere? The case of Mercury
Authors: Lapenta Giovanni , Schriver David , Walker Raymond J. , Berchem Jean , Echterling Nicole F. , El Alaoui Mostafa , Travnicek Pavel
Published: March 2022

While a global full particle-in-cell (PIC) model of Earth’s magnetosphere cannot yet achieve enough resolution to be quantitatively accurate, the full model of smaller planets is becoming possible and can be used to learn what extra effects the full electron kinetic physics brings. From smaller planets we can learn much relevant also for the Earth. 

In this presentation, we investigate the global magnetosphere of Mercury using an implicit full particle in cell simulation (PIC). We use a hybrid simulation where ions are full particles and electrons are considered as a fluid to start a full PIC simulation where electrons are also particles (1836 mion/me) and follow their distribution function.

This approach allows us to estimate the changes introduced by the electron kinetic physics. We find that the overall macroscopic state of the magnetosphere of Mercury is little effected but several physical processes are significantly modified in the full PIC simulation: the foreshock region is more active with more intense shock reformation, the Kelvin-Helmholtz rippling effects on the nightside magnetopause are sharper, and the magnetotail current sheet becomes thinner than those predicted by the hybrid simulation.  The greatest effect of the electron physics comes from the processes of particle energization. Both species, not just the electrons, are found to gain more energy when kinetic electron processes are included. The region with the most energetic plasma is on the dusk side of the tail where magnetic flux ropes are formed due to reconnection. We find that the ion and electron energization is associated with the regions of reconnection and the development of kinetic instabilities caused by counter-streaming electron populations. The resulting electron distributions are highly non-Maxwellian, a process that neither MHD nor hybrid models can describe.

Reference: Lapenta, G., Schriver, D. Walker, R.J.,  Berchem, J., Echterling, N.F.,  El Alaoui, M., Travnicek, P., (2022) Do we need to consider electron kinetic effects to properly model a planetary magnetosphere: the case of Mercury, arXiv:2201.01653, submitted.

 
Fault growth and rift propagation during rotational continental rifting: Insights from an analogue modelling study
Authors: Schmid Timothy , Schreurs Guido , Adam Jürgen
Published: March 2022

Continental rifts typically result from regional horizontal stretching of the lithosphere and in modelling studies, such rifts are typically assumed to be the result of orthogonal or oblique extension. However, in nature often V-shape rift geometries occur indicating an underlying rotational component that results in a divergence velocity gradient along plate boundaries. Consequently, the geometric, kinematic, and dynamic rift evolution in such rotational settings may significantly differ from those of orthogonal or oblique rifts. Here, we present new findings from an analogue modelling study using a crustal-scale model series with a rotational opening component to investigate the effect of such a rift-axis parallel divergence velocity gradient on fault growth and rift propagation towards the rotation axis.

We use a simplified two-layer system simulating an upper brittle and a lower ductile crust with an imposed initial mechanically weak zone on top of the viscous layer to ensure localized rifting. The experimental monitoring by means of a stereoscopic camera setup and X-Ray computed tomography (XRCT) enables a detailed and quantitative investigation of near-surface rift evolution and internal deformation, respectively. With the combination of 3D surface topography, 3D displacement fields, and XRCT, we gain a comprehensive understanding of deformation evolution in analogue models of rotational rifting. Our modelling results depict a novel characterization of normal fault growth under rotational extension and a rift evolution which is described by (1) rift propagation in two consecutive stages: A first stage showing bidirectional fault growth due to segment linkage with high rift propagation rates, and a second stage during which rift propagation occurs by unidirectional fault growth towards the rotation axis with linearly decreasing growth rates at decreasing distance to the rotation axis, (2) strain partitioning between competing conjugate normal faults with fault activity switching repeatedly from one segment of a normal fault to a segment on the oppositely dipping normal fault, and (3) active faulting migrating from the rift boundary faults inwards to intra-rift normal faults.

Our quantitative, spatiotemporal fault growth analysis reveals a characteristic segmentation of all deformation features listed above. The conclusion that the gradual decrease of the divergence velocity towards the rotation axis causes segmented deformation propagation is key and can help to understand natural examples of rotational rift settings such as the Taupo Rift Zone in New Zealand.
​Studying the active tectonic in the northern flank of the Bozqush Mountains, NW Iran
Authors: Nasiri Ali , Aflaki Mahtab
Published: March 2022

The NW-striking North Tabriz Fault is one of the most important basement faults in the northwest of the Iranian ‎plateau. This fault defines the boundary between the two tectonic ‎blocks with different stress regimes in its northern and southern parts as characterized with NW-SE and NE-SW direction of maximum horizontal compression, respectively. In the southern ‎termination of the North Tabriz fault, part of deformation is concentrated along its EW-striking splay faults extending along northern and southern boundaries of the Bozqush Mountains. The occurrence of medium-magnitude earthquakes, as ‎well as morphotectonic evidence reveal that modern deformation is dominantly concentrated along ~EW-striking dextral/reverse dextral and NNE-striking sinistral faults in the southern flank of the Bozqush Mountains. It is still not known to what extent the deformation is also accomodated in the northern flank of the Bozqush Mountain. The approach of this research is to ‎answer the question by studying the state of stress along the northern border of the Bozqush Mountains by applying the inversion method on the fault slip data measured during the field studies, studying their related ‎morphotectonic evidence, and comparing the results with ‎the state of stress and the morphotectonic evidence reported throughout the southern flank of the Bozqush Mountains. Fault kinematic data were collected at 35 sites ‎along the northern boundary of the Bozqush Mountains. Evidence of the modern NW-SE stress regime is found at five sites measured within the Quaternary detrital deposits in the western part of the study area. At the other ‎sites, evidence of the older stress regime, with NE-SW direction of maximum horizontal ‎compression is obtained. Also, the systematic deflection of the stream channels, especially in the eastern part of the region, ‎indicates the sinistral displacement along the EW-striking faults, consistent with the old ‎stress regime in the region. Evidence of dextral deflection was observed along few EW-striking faults cutting the Quaternary deposits only in the western parts of the region. Therefore, ‎by comparing these kinematic data and morphotectonic evidences with those reported from the southern flank of the Bozqush Mountains, it can be concluded that the modern deformation is dominantly absorbed along the splay faults in the southern flank of the Bozqush.‎

 

​Key Words: North Tabriz fault, Modern stress state, NW Iran, Northern flank of Bozqush Mountains, Stress inversion
Tuning an improved irrigation scheme inside ORCHIDEE land surface model and assessing its sensitivity over land surface hydrology and energy budget 
Authors: Arboleda Pedro , Ducharne Agnès , Yin Zun , Ciais Philippe
Published: March 2022

Water used to irrigate accounts for 70% of total water withdrawal and 90% of water consumption worldwide. As a result, irrigation has a strong impact on water and energy budgets, on the associated biogeochemical cycles, and on local and regional climate. Furthermore, water volume for irrigation is projected to increase, due to population growth and climate change. This has encouraged the inclusion of irrigation in an increasing number of land surface models (LSM), which represent the continental branch of the water cycle in Earth System Models. To this end, three key aspects of irrigation must be described: when to irrigate (timing), how to irrigate (irrigation method), and how much to irrigate (water amount).

We present a new irrigation scheme for the ORCHIDEE land surface model, developed to account for flood and drip irrigation techniques. In grid cells with irrigated areas, the water demand is deduced from the soil moisture deficit in the crop and grass soil column, i.e. is partially controlled by soil parameters. The soil column contains both irrigated and rainfed crops, but the fraction equipped for irrigation limits the water demand. The deficit is the difference between the actual soil moisture in the root zone and a soil moisture target. Both the root zone depth and the soil moisture target are user-defined. The volume of water utilized for irrigation is constrained by water availability from rivers and the unconfined groundwater reservoirs, while guaranteeing an environmental flow (i.e. irrigation cannot deplete completely the reservoirs). Additionally, priority in abstraction source (surface vs groundwater) is imposed based on the maps of Siebert et al., (2010). This means that a grid cell without infrastructure for groundwater irrigation, for example, will take all the water from the river, and vice versa. This adds an additional constraint to water availability. The water volume is put in the surface of the crop and grass soil column for infiltration, regardless of water source.

Using offline simulations at global scale, we will evaluate the sensitivity of four key factors:  definition of the root zone, setting of the soil moisture target, water availability and the decay of soil hydraulic conductivity with depth. We will then tune the irrigation scheme to match the irrigation volumes reported at country level by the AQUASTAT dataset, and evaluate the effect of irrigation on soil surface hydrology and energy balance. The perspective of this work is to explore the effects of irrigation over present and future climates, using coupled land surface – atmosphere simulations with the IPSL-CM6 climate model. 

S. Siebert et al., “Groundwater use for irrigation - A global inventory,” Hydrol. Earth Syst. Sci., vol. 14, no. 10, pp. 1863–1880, 2010.
Resolving land use conflicts between renewable energy, nature protection and food production
Authors: Delafield Gemma , Day Brett , Smith Greg , Holland Robert
Published: March 2022

As countries transition to net zero emissions, the number of land use conflicts between energy generation, nature conservation and food production are expected to rise. Models typically restrict energy deployment from land deemed as providing high societal value (e.g. National Parks, peatland) when exploring future energy pathways to resolve these conflicts. This study applies the spatially explicit ADVENT-NEV model to Great Britain to determine the lower-bound of the implied value being placed on the land excluded. It compares the ‘optimal’ locations for new renewable energy when strict restrictions are applied against those identified when a natural capital approach is used.

When energy development is restricted from Areas of Outstanding Natural Beauty, National Parks and high-grade agricultural land the cost of the energy system is shown to increase by approximately 10%. Even limited bioenergy crop expansion is unfeasible if strict restrictions are applied. In particular, results indicate that such restrictions would not be compatible with net zero emissions targets. These restrictions also result in an increase in the spatial footprint of solar farms, wind farms and bioenergy power stations by up to 13.4%, 79.6% and 15.8% respectively.

Incorporating the valuation of ecosystem services into renewable energy modelling provides a more nuanced approach than a binary exclusion, highlighting how strict restrictions may not always be best for society. The natural capital approach makes trade-offs between energy, nature conservation and food production more explicit for decision-makers allowing them to take a more holistic approach.
The open-ended, high-cadence, Kp-like and fully operational geomagnetic Hpo indices for the ESA Space Weather G-ESC service network
Authors: Kervalishvili Guram , Matzka Jürgen , Rauberg Jan
Published: March 2022

Global geomagnetic indices are widely used not only to characterize the geomagnetic disturbance level but also for the parameterization of physical and empirical models of the near-Earth space environment and in data (re)analysis. One of the most utilized index families is the three-hourly Kp and the ap, Ap, Cp, C9 indices derived and disseminated by the GFZ German Research Centre for Geosciences.

The new global geomagnetic open-ended, high-cadence, Kp-like Hpo index family (consisting of the half-hourly Hp30, ap30 and hourly Hp60, ap60) was developed within the Space Weather Atmosphere Models and Indices (SWAMI) project of the H2020 EU research activity. These open-ended Hpo indices are based on the data of the same 13 geomagnetic observatory and similar algorithms as the three-hourly Kp index. The open-ended indices are designed such that 15 Hp60 and 32 Hp60 values exceeding 9 (maximum amplitude for the Kp index) have been assigned since 1995.

Near real-time indices and archive indices back to 1995 are available for download under the CC BY 4.0 license and include the linear versions of the Hp30 and Hp60 indices, the ap30 and ap60 indices. Near real-time plots of the Hp30 and Hp60 indices for the current day and the previous six days are also provided. Here, the operational capabilities and examples of these indices will be presented.
Reduced rainfall in future heavy precipitation events tied to decreased rain area and takes place despite increased rain rate
Authors: Armon Moshe , Marra Francesco , Garfinkel Chaim , Rostkier-Edelstein Dorita , Adam Ori , Dayan Uri , Enzel Yehouda , Morin Efrat
Published: March 2022

Heavy precipitation events (HPEs) can lead to deadly and costly natural disasters and, especially in regions where rainfall variability is high, such as the eastern Mediterranean, they are critical to the hydrological budget. Reliable projections of future HPEs are needed, but global climate models are too coarse to explicitly represent rainfall processes during HPEs. In this study we used pseudo global warming high-resolution (1 km2) weather research and forecasting (WRF) model simulations to provide rainfall patterns projections based on simulations of 41 pairs of historic and “future” (end of 21st century) HPEs under global warming conditions (RCP8.5 scenario). Changes in rainfall patterns were analyzed through different properties: storm mean conditional rain rate, storm duration, and rain area. A major decrease in rainfall accumulation occurs in future HPEs (−30% averaged across events). This decrease results from a substantial reduction of the storms rain area (−40%) and duration (−9%), and occurs despite an increase in the mean conditional rain intensity (+15%). The consistency of results across events, driven by varying synoptic conditions, suggests that these changes have low sensitivity to the specific synoptic evolution during the events. Future HPEs in the eastern Mediterranean will therefore likely be drier and more spatiotemporally concentrated, with substantial implications on hydrological outcomes of storms. (For hydrological results see: abstract #EGU22-4777)

Armon, M., Marra, F., Enzel, Y., Rostkier‐Edelstein, D., Garfinkel, C. I., Adam, O., et al. (2022). Reduced Rainfall in Future Heavy Precipitation Events Related to Contracted Rain Area Despite Increased Rain Rate. Earth’s Future, 10(1), 1–19. https://doi.org/10.1029/2021ef002397