bluuebunny/crossref_metadata_2025 huggingface dataset:
Projecting Three-dimensional Ocean Thermohaline Structure in the North Indian Ocean from the Satellite Sea Surface Data Based on a Variational Method
Authors: He Zikang , Wang Xidong , Wu Xinrong , Chen Jian
Published: March 2022

This study uses a variational method combined with satellite observations to reconstruct three-dimensional temperature and salinity profiles for the Northern Indian Ocean (NIO). Sensitivity experiments show that sea surface temperature (SST) dominantly improve the temperature reconstruction of upper 100 m; sea surface salinity (SSS) determines salinity estimation in the upper 100 m; sea surface height anomaly (SSHA) dominates the reconstruction of thermocline. The reconstructed temperature fields can be greatly improved in the thermocline by removing barotropic signal from the altimeter SSH data through a linear regression method. Ocean reanalysis and in situ temperature and salinity data are used to evaluate the results of reconstruction. Comparing with Simple Ocean Data Assimilation (SODA) in 2016, the spectral correlation between the reconstruction and the SODA density anomalies show that the reconstruction fields can retrieve mesoscale and large-scale signals better. Moreover, the reconstruction salinity is much more accurate than SODA salinity in the upper ocean over the Bay of Bengal (BoB). Compared with CTD section observations, the reconstruction fields can capture the mesoscale eddy structure in the Arabian Sea (AS) and BoB well, respectively. The long time series of reconstruction along Argo trajectory shows that the reconstruction fields can better reproduce the observed intraseasonal oscillations of thermocline/halocline in the BoB. Compared with the World Ocean Atlas 2013 (WOA13) climatology, the reconstruction fields can better characterize upper ocean water mass variability.
Statistical distribution of ion cyclotron waves in Saturn’s inner magnetosphere: A survey of Cassini measurements between 2004 and 2016
Authors: Long Minyi , Cao Xing , Ni Binbin , Gu Xudong , Ye Shengyi , Yao Zhonghua , Wu Siyuan , Xu Yan
Published: March 2022

Based on Cassini observations from 2004 to 2016, we perform a comprehensive analysis of the statistical distribution of the occurrence rate, averaged amplitude, wave normal angle (WNA), ellipticity and power spectral intensity of ion cyclotron waves in Saturn’s inner magnetosphere. Our results show that ion cyclotron waves mainly occur between the orbits of Enceladus and Dione near the equatorial region (λ<20°), with higher occurrence rates in the northern hemisphere than the southern hemisphere. The averaged wave amplitudes vary between 0.1–2 nT with a strong day-night asymmetry and a pronounced minimum at the equator. Saturnian ion cyclotron waves are predominantly left-handed polarized with small WNAs near the equator, and become linearly polarized with larger WNAs at higher latitudes. The major wave power occurs frequently at frequencies of 0.5-1.2 fw+, where fw+ is the equatorial gyrofrequency of H2O+ ions, with the strongest intensity (>~10 nT2/Hz) at L~6.5 statistically present in the midnight sector.
Characteristics of 7 Northerly Cold Surge Events During Years of the Maritime Continent Campaign 2021
Authors: Makmur Erwin , Moteki Qoosaku , Fitria Welly , Nurrahmat Mohamad Husein , Riama Nelly , Sasmito Achmad , Suharmanto Eko , Soebroto Eko , Kurniawan Roni , Swarinoto Yunus , Rahayu Sri , Harsa Hastuadi , Hanggoro Wido , Fatkhuroyan Fatkhuroyan , Habibie Najib , Praja Alfan , Hutapea Daniel , Sapta Rahayu , Noviati Sri , Paski Jaka
Published: March 2022

To explore the characteristics of Northerly Cold Surge during Years of the Maritime Continent Campaign 2021, intensive observation was used to detect the modification processes of the air mass at the head of cold surge, convection development, and severe weather including torrential rainfall using several methods such as the intensive upper-air observation at Jakarta and Pangkal Pinang, vapor variation observation with GNSS network, and precipitation radar network. During this campaign, 7 CENS (Cross-Equatorial Northerly Surge) events were observed according to Hattori’s criteria. The results of the intensive observation show that all of 7 CENS events occurred in association with the negative SST anomaly over the Java Sea with CENS6 (18 – 21 February 2021) induced extreme rainfall (over 150 mm/day) in the southern part of Jakarta. The significant negative SST anomaly was continued over the inland & marginal seas of Indonesia under the strong northerly surge condition during this campaign.
The structure of the upper crust under the Kambalny volcano (Southern Kamchatka) according to the results of seismic tomography
Authors: Komzeleva Viktoria , Koulakov Ivan , Rychagov Sergey , Gordeev Evgeny , Abkadyrov Ilyas , Stupina Tatiana , Novgorodova Angelika
Published: March 2022

In this study we present the results of tomography studies for seismic velocity in the area of Kambalny volcano (Southern Kamchatka). After a long repose stage, on March 24, 2017, it produced a strong phreatic eruption, which ejected an ash cloud to the distance of up to 1000 km. We have obtained the first 3D model of seismic velocities beneath the area of Kambalny based on the data recorded by a temporal network of ten seismic stations installed for one year in 2018-2019. The distributions of velocities of the P and S seismic waves, and especially the Vp/Vs ratio, provide the information on the geometry of the plumbing system beneath the volcano in the upper crust down to ~10 km, which makes it possible to build a scenario of preparation and occurrence of the explosive eruption in 2017. We clearly identify an anomaly of high Vp/Vs ratio in the depth interval of 7-10 km, which is interpreted as a magma reservoir responsible for Holocene activity of Kambalny. This reservoir appears to be connected with the volcano edifice by a linear zone of high Vp/Vs ratio, which may represent a system of fractures originated during the eruption in March 2017 and served as a pathway for magma ascent. We propose that the interaction of hot magma with meteoric fluids in shallow layers caused active boiling and steam formation in a closed reservoir below the volcano. After exceeding a critical pressure, the steam escaped to the surface causing an explosive eruption. We also found evidence that geothermal fields located to the north and northwest of Kambalny might be fed from separate deep sources. The area of Kambalny is characterized by strong geothermal activity, most of which is located to the north and to the west of the volcano. The northern geothermal manifestations mostly occur on the northern part of the Kambalny Ridge and in the Pauzhetka depression. We found that the geothermal activity in these areas is likely associated with a deep source, which appears to be isolated from the magma reservoir below Kambalny volcano. A similar isolated anomaly is observed below geothermal fields in the area of the Koshelev volcano to the west, which may indicate that the geothermal activity appears to be independent of the magmatic system of Kambalny volcano, at least for its upper-crustal part.

This study was partially supported by the Russian Science Foundation project # 20-17-00075.
Two Cretaceous forebulge successions in the Oman Mountains, triggered by the obducted Semail Ophiolite, identified by the facies analysis of limestones, ferruginous crusts and ferruginous oolites
Authors: Mattern Frank , Pracejus Bernhard , Scharf Andreas , Frijia Gianluca , Al-Salmani Moath
Published: March 2022

The Tethys-derived Semail Ophiolite had formed during the Cenomanien-Turonian. Along with deep-sea sediments, it was obducted onto the Arabian Plate as it was still young, hot and buoyant. Thrusting and loading triggered the formation of the Aruma Foreland system consisting of a foredeep, a forebulge and a backbulge basin.

The studied succession represents the uppermost part of the Permo-Mesozoic shallow marine shelf sequence of the Arabian Platform, which is blanketed at an angular unconformity by shales of the Late Cretaceous Muti Formation of the Aruma (foreland) Group. The structural position of the succession is on the forebulge which is characterized by eroded Cretaceous and Jurassic shelf formations of the Arabian Platform (Wasia-Aruma Break).    

We identified two forebulge successions. Both display repetitive lithofacies, beginning with (1) shallow subtidal massive/poorly bedded bioclastic wackestones to floatstones, followed by (2) peloidal grainstones, (3) ferruginous crusts and (4) shallow marine ferruginous oolites. From base to top, both successions record an overall shallowing-up trend. At the same time, the relative sedimentation rate decreases in the same direction. The coarse-grained massive facies may have been deposited on a regular slope which was well-supplied with bioclasts. The finer grained grainstone facies and their peloids indicate a lower sedimentation rate, reflecting the transition form a regular slope to a forebulge on which in the next step sediment condensation occurred (crusts) and chemical precipitation of ferruginous material (crusts and oolites). Each forebulge succession is capped by clayey material.

The similar facies development of the two successions suggests repetitively similar depositional and tectonic conditions. As both sequences occur at the same site, two vertical forebulge developments are concluded.

The ferruginous crusts formed under at least slightly reducing conditions, associated with minor water-deepening events. Both oolites contain chlorite, hematite, quartz, calcite and apatite. The nuclei of the ooids are often chlorite or hematite fragments, having most-likely derived from preexisting ferruginous crusts. Iron oxyhydroxides and clinochlore of the oolites reflect bathymetric changes to more oxidizing aqueous conditions, associated minor water-shallowing events.

Fe-rich anoxic to sub-oxic sea water of the marine foredeep was the Fe source for the crusts and oolites, coinciding with (1) a high rate of global Cretaceous oceanic crust production, (2) related hydrothermalism and (3) the regional proximity of an active spreading axis. Fe was likely stabilized in ocean water as Fe colloids and organic Fe complexes.
3D Analysis of Stability for Rainfall Induced Landslides in Unsaturated Soils 
Authors: Oh Seboong , Kim Seong Jin , Son Kwang Ik
Published: March 2022

In the stability analysis of landslides, it is required to consider the rainfall intensity, geographical features and hydromechanical behavior in unsaturated layers. The actual landslide can be simulated rigorously by 3D analysis. The unsaturated shear strength can be evaluated from soil water retention curves based on the suction stress which has generalized Bishop’s effective stress. The unsaturated soils become unstable as the saturation ratio increases and subsequently the effective stress decreases. The assessment of landslide stability is based on the effective stress theory in unsaturated soils.

By the GIS based analysis system, the slope stability is estimated for wide mountain area in Korea. From digital map data, the contour map and elevation are extracted and the mesh is created as a preprocess. In each cell, the infiltration and stability analysis are performed step by step. In the area of actual landslides, the infiltration analysis on transient flow has been performed one dimensionally for the actual rainfall record. The stability analysis is subsequently performed three dimensionally based on the unsaturated effective stress principle. It is verified that the 3D stability analysis can simulate the actual landslide rigorously.

 

 Acknowledgements This research is supported by grant from Korean NRF (2019R1A2C1003604), which are greatly appreciated.
Climate Predictions in a Forecast based Action (FbA) pilot within the Greater Horn of Africa; Experiences from ForPAc and Down2Earth Projects
Authors: Otieno Dr. George , MacLeod Dave , Todd Martin C , Visman Emma , Graham Richard , Waruru Shamton , Tadege Abebe , Hassaballah Khalid
Published: March 2022

Skillful weather and climate forecasts, if utilized effectively, have the potential to improve preparedness and disaster risk reduction. Forecast-based Action (FbA) is a framework for aiding decisions on preparedness in advance of weather/climate hazards, through use of forecasts. Here, we present a summary of research results and pilot project work within the Arid and Semi-Arid Land (ASAL) areas of Kenya conducted under the Towards Forecast-based Preparedness and Action (ForPAc) project. We also present opportunities for scaling up FbA  across the Greater Horn of Africa region through leveraging on connected projects and initiatives like Down2Earth.  Skill assessment of a pool of weather/climate models has established the most skilful multi-model combinations for monthly-seasonal timescale.  Co-production initiatives between forecast users and producers established the forecast variables best aligned with Kenya’s existing Drought Early Warning Systems (DEWS); Standardized Precipitation Index (SPI), Vegetation Condition Index (VCI) and soil moisture, as well as optimum forecast delivery time required by the DEWS processes. Our analysis shows that rainfall forecasts have skill across ‘seamless’ sub-seasonal to seasonal lead times, offering the potential to improve the anticipatory actions within the DEWS of Kitui county of Kenya. Working with multiple stake-holders from across local and national government, humanitarian agencies, forecasting services and climate researchers, we have explored the potential for a more anticipatory, proactive DEWS using forecast information. The Down2Earth project, which aims at translating climate information for adaptation and climate-resilience across decision-making levels is leveraging on gains of ForPAc by advancing FbA approaches within the rural communities of Kenya, Somalia and Ethiopia. To facilitate the institutionalization of FbA, we have developed a regional roadmap to guide implementation within National, regional and international humanitarian actors.   
Reconstruction of the Cenozoic deformation of the Bohai Bay Basin, North China
Authors: Zhu Yinbing , Liu Shaofeng , Zhang Bo , Gurnis Michael , Ma Pengfei
Published: March 2022

A well-constrained plate deformation model may lead to an improved understanding of sedimentary basin formation and the connection between subduction history and over-riding plate deformation. Building quantitative models of basin kinematics and deformation remains challenging often due to the lack of comprehensive constraints. The Bohai Bay Basin (BBB) is an important manifestation of the destruction of the North China Craton, and records the plate kinematic history of East Asia during the Cenozoic. Although a number of interpretations of the formation of the BBB have been proposed, few quantitative basin reconstruction models have been built to test and refine previous ideas. Here, we developed a quantitative deformation reconstruction of the BBB constrained with balanced cross-sections and structural, stratigraphic, and depositional age data. Our reconstruction suggests that the basin formation process was composed of three main stages: Paleocene-early Eocene (65-42 Ma) extension initiation, middle Eocene-early Oligocene (42-32.8 Ma) extension climax, and post-Oligocene (32.8-0 Ma) post-extensional subsidence. The deformation of the BBB is spatially heterogeneous, and its velocity directions rotated clockwise during the basin formation process. The reconstruction supports the interpretation that the BBB formed via strike-slip faulting and orthogonal extension and that the basin is classified as a composite extensional-transtensional basin. We argue that the clockwise rotation of the basin velocity field was driven by the counter-clockwise rotation in the direction of Pacific Plate subduction. The kinematics of the BBB imply that the Pacific Plate may have been sufficiently coupled to the over-riding East Asian Plate during the critical period of Pacific Plate reorganization. The new reconstruction provides a quantitative basis for studies of deformation processes not only in the vicinity of the BBB but more broadly throughout East Asia.
Application on the Micro-hydropower generation Benefits of Agricultural Channels and the Water- Energy-Food nexus
Authors: Shih Jen-Chieh , Lin Fu-Yuan , Hong Ming-Der , Lin Hong-Ru , Wen Jet-Chau
Published: March 2022

Micro-hydropower is necessary renewable energy to provide baseload, and it has the advantages of sustainable development and reduction of greenhouse gas emissions. There is an interrelationship between irrigation water and energy from micro-hydropower with micro-hydropower development in agricultural irrigation systems. Li et al. (2019) mentioned that the agricultural system estimated the water supply-demand, energy supply-demand, land demand, and food production and was quantitatively analyzed under different scenarios. However, the study of water for electricity generation was neglected in the agricultural system. Zhou et al. (2019) apply small-hydropower into water supply systems to lift renewable power output and uplift the synergistic benefits of the Water-Food-Energy (WFE) Nexus steered by the optimal water allocation and small-hydropower installation. Still, the adjustment of the water source by the reservoir makes the flow of the water supply system unstable, which leads to inconsistent electricity generation of small hydropower. Gaudard et al. (2018) research that hydropower plants' relationship between water and energy is set-upstream. The results show that seasonality slightly affects hydroelectric power generation.

Therefore, the study set up a micro-hydropower generation system in the Linnei channel of the Zhuoshuixi river watershed in the middle of Taiwan. Collected channel background information and used Doppel (Teledyne StreamPro ADCP) to measure the water level, velocity, and discharge of the study site, analyze potential power generation, and evaluate the profit and payback period micro-hydropower generation and the impact of micro- hydropower systems in agriculture. Furthermore, to investigate the relationship nexus of WFE and assess micro-hydropower's effectiveness in reducing carbon dioxide emissions. According to the results of this study, it can be used as a reference basis for setting up other micro-hydropower systems in the future.
Assessing the groundwater sustainability of Bengaluru megacity, India, through the lens of socio-hydrogeology 
Authors: Kulkarni Tejas , Gassmann Matthias , Kulkarni Chandrakanth , Khed Vijayalaxmi , Buerkert Andreas
Published: March 2022

Water extraction in Bengaluru, India's fastest expanding metropolis, entirely depends on its ~500000 wells in a crystalline rock aquifer, of which an unknown number has been abandoned and the level of others has sunk to depths of 450 meters below surface. Recent research has highlighted the spatial heterogeneity and questioned the reliability of water level data in these settings. To fill existing knowledge gaps on the likely over-extraction of groundwater as a vital resource we used a socio-hydrogeological approach of front-lining local hydrogeologists to collect primary data on the spatio-temporal evolution of well depths across the city. Our data show that over the past 60 years borewell depth has increased significantly while water yields have remained unchanged, indicating that digging deeper wells is unsustainable. Using camera inspections of 56 wells in a 2.1km2 catchment of industrial land use in Electronic City of Bengaluru, we noted that water levels in the wells are largely determined by rock fractures, not by well depth. Our data show that increased borewell depths is a good signal of declining water levels in Bengaluru’s aquifers. Analysis of δ18O and δ2H signatures of groundwater samples across all depths followed the local meteoric water line indicating recent recharge, implying that drilling deeper only increased the borehole volume and did not tap into newer water sources.
The Critical Need to Foster Reproducibility in Computational Geoscience
Authors: Reinecke Robert , Trautmann Tim , Wagener Thorsten
Published: March 2022

Chains of computer models translate emissions into climate signals and subsequent into impacts regarding floods, droughts, heatwaves, and other perils. While the need for computational geoscience is significant, recent publications across the geo- and environmental sciences suggest that reproducibility of computational geoscience might be limited. So far, the focus of reproducibility largely remained on discussions of this problem in the social sciencesor medicine; in this talk, we take a peek behind the curtain of everyday geoscientific research and unveil how we need to foster reproducibility in computational geoscience and what is required to do that. A poll among more than 300 geoscientists reveals that geoscientific research is currently not reproducible enough. 61% say that a lack of reproducible research is putting trust in our results at stake, and only 3% strongly agree that computational geoscientific research is reproducible. Leading causes, contrasting previous polls, are not only a lack of resources and willingness to share code and data but also a lack of knowledge about state-of-the-art software development methods and licenses among the geoscientific community. To lay a path for a future where Open Science is the norm, we let the voices of the community speak on what they think is necessary and paint a picture of a future that fosters reproducible geoscience and thus trust.
Long-term changes in dissolved inorganic carbon (DIC) across boreal streams caused by altered hydrology
Authors: Wallin Marcus , Rehn Lukas , Laudon Hjalmar , Sponseller Ryan
Published: March 2022

A major challenge for predicting future landscape carbon (C) balances is to understand how environmental changes affect the transfer of C from soils to surface waters. Here we evaluated 14 years (2006-2019) of data on stream dissolved inorganic carbon (DIC) concentrations and export rates for 14 nested boreal catchments that are subject to climatic changes, and compared long-term patterns in DIC with patterns in dissolved organic carbon (DOC). Few streams displayed significant concentration or export trends at annual time scales. However, a clear majority of streams showed decreasing DIC concentrations during spring flood, and about half showing declines during summer. Although annual runoff has generally not changed during the studied period, intra-annual redistribution in runoff explained much of the seasonal changes in stream DIC concentration. We observed negative DIC-discharge relationships in most streams, suggesting supply limitation of DIC with increasing discharge. This was in contrast to DOC, which mostly showed a chemostatic behaviour. The distinct trend patterns observed for DIC and DOC underpin intra-annual changes in the total C pool (DIC/DOC ratio) in most streams and reflect differences in how these C forms are produced and stored, are mobilized by hydrological events, and are responding to long-term environmental changes. Collectively, our results indicate that future changes in hydro-meteorological conditions will affect the transfer of DIC from soils to water, and that these changes contrast to those of DOC. Such information is critical for future projections on how total C transfer from boreal system will respond on a changing climate.
Contribution of the Winter Salinity Barrier Layer to Summer Ocean–Atmosphere Variability in the Bay of Bengal
Authors: Pang Shanshan , Wang Xidong , Foltz Gregory R. , Fan Kaigui
Published: March 2022

This study finds that the winter (December–February) barrier layer (BL) in the Bay of Bengal (BoB) acts as a dynamical thermostat, modulating the subsequent summer BoB SST variability and potentially affecting the Indian summer monsoon (ISM) onset and associated rainfall variability. In the years when the prior winter BL is anomalously thick, anomalous sea surface cooling caused by intensified latent heat flux loss appears in the BoB starting in October and persists into the following year by positive cloud–SST feedback. During January–March, the vertical entrainment of warmer subsurface water induced by the anomalously thick BL acts to damp excessive cooling of the sea surface caused by atmospheric forcing and favors development of deep atmospheric convection over the BoB. During March–May, the thinner mixed layer linked to the anomalously thick BL allows more shortwave radiation to penetrate below the mixed layer. This tends to maintain existing cold SST anomalies, advancing the onset of ISM and enhancing June ISM precipitation through an increase in the land–sea tropospheric thermal contrast. We also find that most CMIP5 models fail to reproduce the observed relationship between June ISM rainfall and the prior winter BL thickness. This may be attributable to their difficulties in realistically simulating the winter BL in the BoB and ISM precipitation. The present results indicate that it is important to realistically capture the winter BL of the BoB in air–sea coupled models for improving the simulation and prediction of ISM.
Classification reveals varying drivers of severe and moderate hydrological droughts in Europe
Authors: Brunner Manuela Irene , Van Loon Anne , Stahl Kerstin
Published: March 2022

Streamflow droughts are generated by a variety of processes including rainfall deficits and anomalous snow availability or evapotranspiration. The importance of different driver sequences may vary with event severity, however, it is yet unclear how. To study the variation of driver importance with event severity, we propose a formal classification scheme for streamflow droughts and apply it to a large sample of catchments in Europe. The scheme assigns events to one of eight drought types – each characterized by a set of compounding drivers - using information about seasonality, precipitation deficits, and snow availability. Our findings show that drought driver importance varies regionally, seasonally, and by event severity. More specifically, we show that rainfall deficit droughts are the dominant drought type in western Europe while northern Europe is most often affected by cold snow season droughts. Second, we show that rainfall deficit and cold snow season droughts are important from autumn to spring, while snowmelt and wet to dry season droughts are important in summer. Last, we demonstrate that moderate droughts are mainly driven by rainfall deficits while severe events are mainly driven by snowmelt deficits in colder climates and by streamflow deficits transitioning from the wet to the dry season in warmer climates. This high importance of snow-influenced and evapotranspiration-influenced droughts for severe events suggests that these potentially high-impact events might undergo the strongest changes in a warming climate because of their close relationship to temperature. The proposed classification scheme provides a template that can be expanded to include other climatic regions and human influences.
Nutrient enrichment reduces soil multidiversity and multifunctionality in an alpine meadow
Authors: Hu Zhengkun , Chen Xiaoyun , Hu Feng , Liu Manqiang
Published: March 2022

Anthropogenic activities have profoundly increased the nutrient inputs into soil through inorganic nitrogen (N) and phosphorus (P) fertilization and atmospheric deposition over recent decades. In grasslands, nutrient enrichment is one of the most important global change factors affecting a range of ecosystem functions and services. Nutrient enrichment promotes some functions such as plant production, but at the cost of other ecosystem functions, which may obscure the net effects on multiple ecosystem functions (i.e., ecosystem multifunctionality). In particular, nutrient enrichment can strongly reduce above- and below-ground biodiversity, which might threaten ecosystem services that delivered by biodiversity. However, our understanding of the importance of soil biota as a component of nutrient-enrichment effects on ecosystem multifunctionality is still limited.

Taking advantages of a long-term field study and a controlled microcosm experiment, we explored whether and how nutrient enrichment affects ecosystem multifunctionality in a Tibetan alpine meadow. The diversity of soil biota across multiple trophic, including bacteria, fungi, protists and nematodes for two consecutive years were investigated from a 13-year field experiment under a gradient of N and P enrichment. A total of 14 ecosystem functions that are influenced by soil biota were measured and were grouped into five categories: (1) nutrient cycling, (2) SOM decomposition, (3) carbon and nutrient cycling drivers, (4) soil structure, and (5) pest control. To generate a comprehensive understanding of the biodiversity-ecosystem-function relationship under nutrient enrichment, a microcosm inoculation experiment using the dilution-to-extinction approach was conducted with soil samples with or without nutrient enrichment.

Our results showed that nutrient enrichment weakened multifunctionality by reducing the multidiversity across soil food webs. Specially, soil biodiversity at higher trophic levels (e.g., microbivorous nematode) supported a greater number of ecosystem functions at high levels of functioning than those of lower trophic levels, such as bacteria and fungi. Microcosm experiment further demonstrated that nutrient enrichment weakened the relationships between soil biodiversity and ecosystem multifunctionality. Together, our results provide insight into the importance of soil biodiversity for maintaining soil multifunctionality under nutrient enrichment, as well as providing strong support for inclusion of multiple aspects of soil biodiversity in conservation and management policies under global change scenarios.
Identification of The Processes Triggering Induced Seismicity at the Enhanced Geothermal System of Basel (Switzerland)
Authors: Boyet Auregan , De Simone Silvia , Vilarrasa Vìctor
Published: March 2022

Felt induced seismicity compromises the public perception on the deployment of geothermal power-plants in urban areas. Large induced earthquakes have led to the shutdown of Enhanced Geothermal Systems (EGS), such as Basel (Switzerland) and Pohang (Republic of Korea). In the majority of induced seismicity cases in EGS, the largest events occur after shut-in. Different mechanisms can trigger induced seismicity. Pore pressure diffusion is established as the most common triggering mechanism. It reduces the effective normal stress acting across pre-existing fault surfaces, weakening the shear resistance and allowing slip of faults. However, this is not the only triggering mechanisms and it cannot explain the large magnitude of post-injection induces seismicity. Additional influencing processes are poromechanical elastic stressing, shear stress transfer and local tectonic settings. Considering theses mechanisms simultaneously can provide a better understanding of the causes of post-injection seismicity and could allow to develop strategies to mitigate the occurrence of earthquakes with high magnitude. To explain these processes, we investigate the induced seismicity that led to the closure of the Basel EGS project. We set-up a hydro-mechanical finite element numerical model which contains faults corresponding with the clusters of induced events at Basel. We study the reactivation of these pre-existing fractures using a viscoplastic model. We are able to identify the process combinations bringing faults to failure. During injection, faults fail due to pore pressure diffusion in the vicinity of the well, and due to poroelastic stressing further in the reservoir. After the injection shut in, poroelastic stressing and shear stress transfer trigger seismicity, being the most relevant triggering mechanisms of post-injection induced seismicity.
The relevance of environmental DNA as a targeted sediment fingerprinting method sensitive to vegetation
Authors: Frankl Amaury , Evrard Olivier , Levard Fabien , Dupin Brice , Tytgat Bjorn , Cammeraat Erik , Verleyen Elie , Stokes Alexia
Published: March 2022

Environmental DNA (eDNA) has recently been considered as a marker that could be used for fingerprinting sediments. Identify sediment sources originating from zones covered with specific plant communities would enhance the sediment fingerprinting method significantly and enable the detailed identification of soil erosion hotspots relative to land use and cover. Here, we explore the relevance of environmental DNA (eDNA) that originates from plant litter and fixes onto fine soil particles as a targeted sediment fingerprinting method. Although research on plant eDNA signatures in soils and sediments is limited, initial results are promising and indicate that eDNA could yield more accurate results than other sediment fingerprints that are sensitive to vegetation. Plant eDNA signatures tend to produce a highly localized signal of sediment sources, mainly reflecting the current vegetation cover of soils. As eDNA is rapidly adsorbed onto fine mineral soil particles such as clay, it is protected against rapid degradation in fluvial environments. Supported by the increasing availability and quality of vegetation maps and eDNA reference libraries, we argue that sediment source fingerprinting using eDNA from plant litter will evolve into a valuable method to identify hotspots of soil erosion and allow stakeholders to prioritize areas where ecological restoration is necessary. We tested our assumptions from a case study in a high mountain environment (catchment of approximately 600 km² in the Central Pyrenees, France) which was recently affected by a severe hydro-climatic event and for which ecological restoration is pertinent.

Keywords:

Pyrenees, river catchments, sedDNA, sediment source fingerprinting, vegetation
Intrinsic low-frequency variability of the Mediterranean Sea circulation studied using a multilayer ocean model
Authors: Rubino Angelo , Pierini Stefano , Rubinetti Sara , Zanchettin Davide
Published: March 2022

Intrinsic chaotic variability in the oceans is an active field of research in modern oceanography, with important implications concerning the understanding and predictability of the ocean system. The focus is mainly on open ocean basins while very little attention is devoted to enclosed or semi-enclosed seas. The intrinsic variability of the Mediterranean Sea, in particular, has not yet been investigated. Here, results obtained with an eddy-resolving nonlinear multilayer ocean model are presented shedding light on relevant aspects of the intrinsic low-frequency variability of the Mediterranean Sea circulation.

An ensemble of multi-centennial ocean runs is performed to allow for a significant statistical analysis. The statistically stationary state obtained after long simulations shows a robust meridional structure consistent with the observed Mediterranean mean state. Among the various features emerging in the decadal and multidecadal temporal ranges are abrupt shifts in the water mass stratification structure. Differences and similarities with observed patterns are finally discussed. 
Theoretical Research on the Pendulum-type Wave in Nonlinear Block-rock Mass Based on Hyperbolic Elastic Model
Authors: Jiang Kuan , Qi Cheng-zhi , Wang Ze-fan
Published: March 2022

Pendulum-type wave is a kind of sign-alternating wave with discontinuous and nonlinear characteristics found in deep rock mass, which is different from the traditional continuum elastic waves. The dynamic engineering disasters such as rockbrusts and anomalously low friction phenomenon occur frequently in surrounding deep level tunnels rock mass, and the study of pendulum-type wave is of great significance for explaining the mechanism and prevention of these engineering disasters. The presence of multiple fractures makes geomaterials nonlinear. Therefore, it is unreasonable to use linear model to study pendulum-type wave in block-rock mass. With the consideration of the nonlinear deformation characteristics of deep rock mass, a nonlinear dynamic model of pendulum-type wave in block-rock mass is established by introducing hyperbolic elastic model of interlayers of geoblocks, and the time-domain characteristics, frequency-domain characteristics and the law of energy transfer are studied. Furthermore, the influence of initial geostress on pendulum-type wave propagation in nonlinear block-rock mass is studied. The research shows that the improved nonlinear model can not only shows the nonlinear deformation of block-rock mass, but also limits the maximum compression deformation of cracks between rock blocks. Under the action of strong impact loading, the acceleration amplitude of blocks far away from the impact point increases significantly, and is the largest, which is not conducive to the structure safety of rock mass. With the increase of impact loading, the frequency response of blocks tends to move to high-frequency domain, and the frequency center increases continuously. Kinetic energy and potential energy are constantly transformed to each other in block-rock mass, and in the free vibration stage, they are in inverse phase, i.e. when the kinetic energy reaches the maximum, the elastic potential energy is the minimum, and vice versa. Relative to the initial geostress, the hyperbolic elastic model can be grouped into three categories: low stress state, high stress state and ultra-high stress state. Under different initial geostress states, the dynamic response of the block-rock mass is very different. With the increase of initial geostress, the displacement amplitude decrease approximately exponentially. In ultra-high stress state, the displacement amplitude of rock blocks decreases by more than 95% compared with that without initial geostress. Therefore, we conclude that in the ultra-high stress state, the pendulum-type wave phenomenon will not occur in block-rock mass, and the wave propagation is close to the longitudinal wave. This paper provides a reference for further study on nonlinear pendulum-type wave in block-rock mass under the conditions of strong impact and high initial geostress.
Flood responses to increases in rainfall extremes vary depending on event severity
Authors: Brunner Manuela Irene , Swain Daniel , Wood Raul , Willkofer Florian , Done James , Gilleland Eric , Ludwig Ralf
Published: March 2022

There is clear evidence that precipitation extremes will increase in a warming climate. However, the hydrologic response to this increase in heavy precipitation is more uncertain - and there is little historical evidence for systematic increases in flood magnitude despite observed increases in precipitation extremes. These dual realities yield a paradox with considerable practical relevance: will the divergence between extreme precipitation increases and flood severity persist, or are land-surface processes at work?  Here, we investigate how flood magnitudes in hydrological Bavaria change in response to warming using a single model initial condition large climate ensemble coupled to a hydrological model (hydro-SMILE). We find that there exists a severity threshold above which precipitation increases clearly yield increased flood magnitudes, and below which flood magnitude is modulated by land surface processes. Our findings highlight the importance of large ensembles and help reconcile climatological and hydrological perspectives on changing flood risk in a warming climate.
Numerical prediction of the effects of solar energetic particle precipitation on the Martian atmospheric chemical composition
Authors: Nakamura Yuki , Terada Naoki , Leblanc Francois , Nakagawa Hiromu , Sakai Shotaro , Hiruba Sayano , Kataoka Ryuho , Murase Kiyoka
Published: March 2022

Solar energetic particles (SEPs) are high-energetic particles that consist mainly of electrons and protons with energies from a few tens of keV to GeV ejected  associated with solar flares and coronal mass ejections. SEPs can precipitate into planetary atmospheres cause ionization, excitation and dissociation of atmospheric molecules, leading to changes in atmospheric chemical composition via chemical network [e.g. Solomon et al., 1981; Adams et al., 2021].

The effect of SEPs on ozone concentration in the Earth’s polar region has been intensively studied for the past decades. For instance, during the enormous solar flare that occurred in late October 2003, NOx and HOx concentrations were enhanced and ozone concentration was depleted by 40% at the polar lower mesosphere [e.g. Jackman et al., 2005]. Increased ionization and dissociation of atmospheric N2 and O2molecules led to the production of NOx and HOx, which catalytically destroyed ozone at the polar mesosphere.

Recently, the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has discovered global diffuse aurora on the nightside of Mars down to few tens km in altitude during SEP events, indicating that a significant amount of energy could be deposited in the atmosphere deeper than previously thought  [Schneider et al., 2015; Nakamura et al., 2022]. However, the effects of SEPs on the atmospheric chemistry of present-day Mars have not yet been investigated by observations and/or models.

By coupling a Monte Carlo model PTRIP (Nakamura et al., 2022) and a newly developed photochemical model to investigate the effects of SEPs on the atmospheric compositions at Mars, we performed a simulation to track the effects of a large SEP event on the Martian atmospheric composition. We found that HOx increased by a factor of 10 and ozone decreased by a factor of 10 in the altitude range from 20 km to 60 km. This is the very first estimation of the effects of SEPs on the atmospheric neutral compositions at Mars, indicating that similar effects on HOx and ozone could be expected on Mars than on Earth.
Locating Nearby Explosions in Fürstenfeldbruck, Germany, Combining 8 Rotational Sensors 
Authors: Izgi Gizem , Eibl Eva P.S. , Krüger Frank , Bernauer Felix
Published: March 2022

The seismic wavefield can only be completely described by the combination of translation, rotation and strain. Direct measurement of rotational motions in combination with the translational motions allow observing the complete seismic ground motion. Portable blueSeis-3A (iXblue) sensors allow to measure 3 components of rotational motions. We co-located Nanometrics Horizon seismometers with blueSeis-3A sensors and measured the full wavefield.

An active source experiment was performed in Fürstenfeldbruck, Germany in November 2019, in order to further investigate the performance of multiple rotational instruments in combination with seismometers. Within the scope of the experiment 5 explosions took place. For the first two explosions, all 8 rotational sensors were located inside of a bunker while for the rest of explosions, 4 sensors each were located at 2 different sites of the field. One group was co-located with translational seismometers. This is the first time the recordings of 8 rotational sensors are combined for event analysis and location. We calculate and intersect the back azimuths and derive phase velocities of the five explosions.

We discuss the reliability of the data recorded by the rotational sensors for further investigations in other environments.
Kinematic orbits and their usage in determining space weather storms induced orbit decays
Authors: Suesser- Rechberger Barbara , Krauss Sandro , Temmer Manuela , Kroisz Sofia , Drescher Lukas , Behzadpour Saniya , Mayer-Gürr Torsten
Published: March 2022

Low earth orbiting (LEO) satellites can be affected by space weather events like coronal mass ejections (CMEs) in such a way that the drag force acting on the spacecraft is enhanced due to increasing atmospheric neutral density. As a consequence, this leads to an additional storm induced orbit decay. LEO satellites equipped with accelerometers offer the possibility to deduce information on the current state of the atmospheric neutral mass density based on the measurements of non-gravitational forces acting on the spacecraft. However, satellites with suitable onboard accelerometers are extremely rare. An alternative method to derive atmospheric densities along a satellite trajectory can be realized through the usage of global navigation satellite system (GNSS) based kinematic orbit information. This approach offers the advantage that that theoretically almost every LEO satellite mission which is tracked by GNSS can be used for the evaluation. In addition, through the increasing number of analysable satellites the explorable altitude range can be expanded to 300 km - 800 km. Thus, a tomography of the upper Earth’s atmosphere is feasible and the impact of a solar event on a satellite can be estimated as a function of its orbital altitude. In this study, we present density estimates based on kinematic orbits during quiet and active solar periods. The results are compared to state-of-the-art thermosphere models like the NRLMSIS 2.0, JB2008 and HASDM. In the case of extreme solar events the investigations are extended by estimating the storm induced orbit decay for different altitudes and satellites.
Nonlinear subcritical and supercritical thermal convection in a sphere
Authors: Sternberg Tobias , Jackson Andrew
Published: March 2022

Fluids that are subject to temperature gradients (or internal heating) and a gravity force will begin convecting when the thermal forcing, conventionally measured by the nondimensional Rayleigh number Ra exceeds a critical value. The critical value RL for the transition from a static, purely conductive state to an advective state can be determined by linearising the equations of motion and formulating an associated characteristic value problem. We discuss two aspects of fluid behaviour away from this point:

(i) Highly supercritical behaviour, and the asymptotic behaviour of heat transport in the highly nonlinear regime. (ii) Subcritical behaviour for Ra<RL, which may be possible for finite amplitude fluid motions. We work in both full sphere and shell geometries, with various forms of heating and gravitational profiles. We report on both theoretical developments and direct numerical simulations using highly accurate fully spectral methods for solving the relevant equations of motion and of heat transfer.
Low-level cloud base height in the eastern Mediterranean basin: comparison between ECMWF IFS forecasts, ceilometers observations, satellite observations and aviation-weather reports 
Authors: Shiloah Nir , Yunker Amit , Kunin Pavel , Rostkier-Edelstein Dorita
Published: March 2022

Clouds are a severe disturbance in a very wide range of applications, such as aviation, and solar energy, and in ground based, airborne, and satellite observations. The ability to accurately predict cloud-base heights (CBH) using the weather models is of crucial importance

In recent years, information on CBH has been added as an integral part of the output of the European Operational Model, the Integrated Forecasting System (IFS) of the European Center for Medium-Range Weather Forecasts (ECMWF).

In order to examine the quality of the IFS forecasts, a CBH comparison was made in this work for low-level clouds at the eastern basin of the Mediterranean, between the IFS model predictions, observations from different meteorological satellites - VIIRS and CALIPSO, ceilometer observations at two sites in Israel - Beit Dagan (Coastal Plain) and Jerusalem (Mountainous area), and aviation weather report data from airports.

The comparison shows that there is a very good agreement between CBH IFS predictions, and ground observations from ceilometers (in most months the difference is less than 25% of the CBH), and a good agreement in cloud cover between IFS forecast and observations of aviation weather reports.

The comparison also shows that there is a good agreement between CBH IFS predictions, and CALIPSO satellite measurements (the difference is on average less than 35% of the CBH, and an excellent 95% fit if CBH measurements are paired compared. Similar comparison of VIIRS satellite observations with CBH IFS predictions, shows good agreement too (the difference is less than 20% of the CBH).