bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation strategy for nutrient-dependent carbon and nitrogen stoichiometric homeostasis in freshwater phytoplankton
Authors: Li Wanzhu , Yang Meiling , Wang Baoli , Liu Cong-Qiang
Published: February 2023

Redfield first reported a carbon: nitrogen (C:N) ratio of approximately 6.6 in marine phytoplankton. However, recent studies show that phytoplankton C:N ratio has a large range (marine: 6.5-9.9; freshwater: 7.8-10.5) and is species-specific.These studies pose a great challenge to phytoplankton stoichiometric homeostasis, which traditionally refers to their ability to maintain relatively stable elemental composition with the variation in external nutrient availability. The underlying mechanisms of the interaction between phytoplankton stoichiometric homeostasis and nutrient availability need further clarification. Therefore, in the field seven reservoirs in Tianjin, North China, were investigated to understand their phytoplankton C:N ratios and the influencing factors, and in the laboratory, Chlamydomonas reinhardtii, as a model organism, was used to investigate its C and N metabolism and relevant physiological parameters under different C and N availability. Transcriptome sequencing, nano-scale secondary ion mass spectrometry, and C stable isotope analysis were used to understand cellular C-N metabolism at the molecular level, cellular C-N compartmentation, and C utilization strategy, respectively, in the culture experiment. The main aim of this study was to understand how C-N availability affects the C:N ratio of freshwater phytoplankton at the molecular level.The results indicated that CO2 limitation had no significant effect on the phytoplankton C:N ratio in either scene, whereas limitation of dissolved inorganic N induced the ratio to be a 35% higher in the field and a 138% higher in the laboratory, respectively. Under CO2 limitation, algal CO2-concentrating mechanisms were operated to ensure a C supply, and coupled C-N molecular regulation remained the cellular C:N ratio stable. Under nitrate limitation, differentially expressed gene-regulated intensities increase enormously, and their increasing proportion was comparable to that of the algal C:N ratio; cellular metabolism was reorganized to form a “subhealthy” C-N stoichiometric state with high C:N ratios. In addition, the N transport system had a specific role under CO2 and nitrate limitations. This study implies that algal stoichiometric homeostasis depends on the involved limitation element and will help to deepen the understanding of C-N stoichiometric homeostasis in freshwater phytoplankton.
Effects of extreme precipitation on sediment connectivity in a farmland watershed of the gully region, the Loess Plateau of China
Authors: Feng Juanlong , Yu Yang
Published: February 2023

Connectivity has emerged as a useful concept for exploring the movement of water and sediments between landscape locations and across spatial scales. Studies on the influences of extreme precipitation events on sediment connectivity of slope-gully systems in a small watershed can provide a theoretical basis for comprehensive watershed management. Taking the farmland watershed in Caijiachuan watershed in Ji County of the Loess plateau as the research area, UAV and remote sensing images were used to carry out field investigations on a slope and gully system before and after the extreme precipitation event occurred in October 2021. The landscape patterns before and after extreme rainstorm were analyzed, the sediment connectivity of the slope-gully system was quantified, and the spatial distribution and topographic features of landslide points were identified, the responses of typical engineering measures to extreme precipitation was evaluated. The results showed that: (1) the rainfall event lasts 84 hours, with a cumulative rainfall of 160.4 mm, a rainfall intensity of 1.9 mm/h and a rainfall frequency of 0.16%. It was an extreme rainstorm that comes once in a hundred years. (2) After the rainstorm, the number of patches increased, the landscape shape index increased, the Contag index decreased, and the Shannon diversity index decreased. (3) Sediment connectivity was unevenly distributed in the watershed before the rainstorm, but it increased after the rainstorm. (4) After the rainstorm, the sediment connectivity of the landslide site decreased, and the landslide mainly occurred at 0-10°and 40-50°, accounting for 29.11% and 17.74%, respectively. After the occurrence of extreme rainfall, landscape pattern fragmentation and richness of the slope-gully system decreased. Landslides induced by extreme rainfall events affect sediment connectivity, and the sediment connectivity index could be used to identify landslide sites and assess the response of typical soil and water conservation engineering measures to extreme rainfall. The results of the study could provide support for integrated watershed management and ecological restoration after extreme precipitation events.Keywords: Extreme precipitation; Check dam; Sediment connectivity; Integrated watershed management
Evaluation of tropospheric NO2 columns observed from the Geostationary Environment Monitoring Spectrometer (GEMS)
Authors: Park Junsung , Lee Hanlim , Hong Hyunkee , Roozendael Michel Van , Kim Jhoon , Kim Siwan , Lee Dong-won , Lee Won-Jin , Krotkov Nickolay A. , Wagner Thomas , Richter Andreas , Lamsal Lok N.
Published: February 2023

Nitrogen dioxide (NO2) and nitrogen oxide (NO), usually referred to as nitrogen oxides (NOx), are emitted into the atmosphere by anthropogenic and natural sources. The detection and monitoring of NO2 plays a key role in air quality managements because of its effects on health and of its contribution to the increase of tropospheric ozone and nitrate aerosols. Unfortunately, up to now, observations were possible only once a day based on satellites in low-earth orbit (GOME, GOME-2, OMI and TROPOMI). However, from now on, it is possible to observe the diurnal variations over the Asia based on Geostationary Environment Monitoring Spectrometer (GEMS) in geostationary earth orbit. Here, we present results of tropospheric nitrogen dioxide column observations with high temporal (hourly) and spatial resolutions over major cities in Asia. In addition, we evaluate the GEMS NO2 operational algorithm by comparing GEMS total and tropospheric NO2 columns with independent observations from ground-based Pandora (total column) and MAX-DOAS (tropospheric column). Additionally, we retrieved the GEMS tropospheric NO2 columns by subtracting the stratospheric NO2 columns, which are assumed based on SLIMCAT model data and then scalded with the real GEMS observations, from the total NO2 columns. Then we also compared the tropospheric NO2 columns that are retrieved based on GEMS NO2 operational algorithm and SLIMCAT model, respectively. Lastly, we compared the GEMS NO2 with other low-earth orbit satellite instruments that include OMI and TROPOMI.
Apply a positivity-preserving limiter of spectral element method to KIM
Authors: Nam Hyun , Choi Suk-Jin
Published: February 2023

 As for a tracer transport scheme, the spectral element method (SEM) has a good accuracy in the  L2-norm error analysis since it uses relatively high-order continuous polynomials. However, the fact  that the basis functions for SEM are globally continuous makes it difficult to preserve important property such as positivity of tracer advection, which results in oscillations in numerical solutions. Moreover, this may cause difficulties in maintaining conservation of mass in long-term integration. Therefore, in many studies, many efforts have been made to reduce or eliminate these oscillations. Among them, this study attempts to apply a positivity-preserving limiter used in finite volume and discontinuous finite element method to SEM. It was proposed by Zhang and Shu (2010) in the highorder positivity-preserving discontinuous Galerkin schemes without losing local conservation or high-order accuracy.  The Korean Integrated Model (KIM) is employing SEM for a tracer transport scheme and has a kind of sign-preserving limiter to reduce oscillations currently (Guba et al.). The limiter prevents all undershoots up to machine precision in a highly deformational advection test case. As a primary result, this study aims to analyze the numerical results in terms of accuracy, mass conservation, oscillation magnitude, comparing to two types of limiters (positivity-preserving limiter & sign-preserving limiter) with original one of KIM. 
A Study on Earthquake Detection Performance of MEMS Sensors According to Seismic Observation Network Density
Authors: Park Euna , Ahn Jae-Kwang , Hwang Eui-Hong , Lee Hye-Won , Park Sun-Cheon
Published: February 2023

Earthquake early warning (EEW) is a technology that aims to reduce damage by notifying an alarm message before a large shaking due to an earthquake. The EEW currently adopted by most national or local governments is a network-based method. Network-based EEW produces seismic source information based on seismic wave detection from at least three observation stations, so the density of the observation network is a very important factor in shortening the warning time. However, a huge budget and space are required to construct a dense seismic observation network. In order to compensate for such limitations, all sensors capable of detecting vibration are being expanded and applied to seismometers. The Korea Meteorological Administration (KMA) signed an MOU with a private telecommunication service provider and installed about 6,700 MEMS sensors across the country. This is about 22 times more sensors than the existing KMA seismic observation network. In this study, the seismic detection performance of MEMS sensors and the KMA seismometers installed across the country was analyzed from the perspective of time. Since it is difficult to apply the existing seismic wave detection technology to the MEMS sensor as it is, an artificial intelligence-based seismic detection technology was applied. We compared the analysis results of the KMA observation network and the MEMS observation network in real-time for earthquakes of M 3.5 or greater. As a result of real-time detection, it was found that the high-density of observation network was more effective in detecting earthquakes than the performance of the sensor.
Velocity and displacement of Korean Peninsula after The 2011 Tohoku earthquake
Authors: Kim Hee-Un , Lee Haseong , Bang So-Young , Lee Jimin , Park Sun-Cheon
Published: February 2023

On March 11, 2011, a magnitude 9.0 earthquake occurred in the Pacific Ocean off the Tohoku region, which greatly affected the crust of the Korean Peninsula. At the time of the Tohoku earthquake, the crust deformation of the Korean Peninsula moved about 30 mm in the eastward direction. This is the size corresponding to the annual average on the Korean Peninsula, and this displacement occurred in one day due to the earthquake. Therefore, in this study, the degree of impact of crustal movement on the Korean Peninsula before and after the Tohoku earthquake was analyzed using domestic and global GNSS observation data. The analysis was performed in two ways. The first was a time series analysis of the crustal movement on the Korean Peninsula based on the IGS observation station in order to globally observe the change in the crustal movement on the Korean Peninsula before and after the earthquake. Secondly, the movement of the inner crust of the Korean Peninsula was confirmed by analyzing the correlation of movement according to the distance from the epicenter. The analysis period is from January 1, 2005 to December 31, 2021. As a result, stations that moved in the southeast direction before the earthquake on the Korean Peninsula moved eastward after the earthquake. However, over time, it gradually moves in a southeasterly direction. The velocity was higher in the western region before the earthquake. At the time of the earthquake, the stations in the eastern area where closer to the epicenter moved more, but have since returned to a similar velocity to that before the earthquake. It seems to be recovering over time after the earthquake, but to be incompleted which means continuous monitoring is needed.
Prototyping Convection-Permitting Global Weather Forecast and the Representation of Aerosol-Cloud-Radiation Interaction in the NOAA Unified Forecast System
Authors: Yang Fanglin , Chen Anning , Moorthi Shrinivas
Published: February 2023

NOAA is collaborating with the US weather and climate science community to develop the next generation fully coupled earth system modeling capability for both research and operational forecast applications across different temporal and spatial scales.    In this presentation we explore the possibility of running the UFS at convection-permitting resolution for global medium-range weather forecasting.  A few sensitivity experiments were performed at a global uniform 3-km resolution with and without parameterized convection.  Results were compared with the 13-km control experiments to investigate the impact of model resolution and convection parameterization on precipitation and cloud-radiation interaction.   Aerosol indirect effect on clouds is also tested and evaluated within this framework to understand its sensitivity to model resolution and parameterized convection.  Aerosol indirect effect occurs when aerosols act as cloud condensation nuclei and ice nuclei within clouds and consequently alter cloud radiative properties and cloud lifetime.   Using the Thompson double-momentum microphysics scheme, the number concentrations of water friendly aerosol and ice friendly aerosol are either diagnosed from the MERRA2 aerosol climatology or predicted and advected with source and sink terms derived from the climatology. The relations between clouds, radiation and precipitation with and without the presence of aerosol indirect effects are analyzed for simulations made at both the control 13-km and experimental 3-km UFS model resolutions.  
Application of Fuzzy Algorithm for Assessing Seismically Induced Landslide Hazard for an Important Road Corridor in the Lower Indian Himalayas
Authors: Tyagi Arun , Nath Ritu Raj , Chaurasia Saurabh
Published: February 2023

A critical part of planning and managing road infrastructures in mountainous regions is thepragmatic assessment of the prevailing and credible landslides hazard. Such assessments assumegreater significance for the Himalayan region, where seismically induced landslides present agreater threat than commonly recognized, and require a robust comprehension of two hazards:earthquake and the landslides induced by the former. However, the traditional practice oflandslide hazard assessment often neglects seismic factor due to paucity of pertinent data, whichmay further be ascribed to the rarity of an extreme event. In this context, an endeavor has beenmade in this study to evaluate the seismically induced landslide hazard for a scenario earthquakeof 10% exceedance probability in 50 years for an important road corridor in the lower IndianHimalayas using Fuzzy algorithms. Probabilistic Seismic Hazard Assessment (PSHA) has beencarried out for the study area to calculate the Peak Ground Acceleration (PGA) of the scenarioearthquake, which is then used as a landslide triggering factor. PGA is integrated with eightdifferent landslide controlling factors viz. lithology, slope angle, aspect, elevation profile,distance form fault, distance from drainage, distance from road, and land-use-land-cover patternsin a Geographical Information System (GIS). 232 numbers of landslides are mapped for thestudy area using high resolution Google earth imagery platform. The Fuzzy Cosine Amplitudemethod is used to define the degree of similarity (strength of correlation) between the observedlandslides (dependent variable) and the landslide causative factors (independent variable(s)).Expectedly, the probability of landslide occurrence correlates (degree of similarity) to the PGAin a linear pattern (goodness of fit = 0.9954). The result of the study is discussed in terms of aseismically induced Landslide Hazard Zonation (LHZ) map for the study, which is generatedusing three Fuzzy operators (AND, OR and GAMMA). The prepared LHZ map demarcates morethan 40% of the study area as the zones of high to very high landslide hazard under the scenarioearthquake, with a prediction accuracy of 80%. The study shows that probabilistically generatedPGA can be included as seismic parameter for a more comprehensive assessment of the landslidehazard in seismically active regions.Keywords: Fuzzy Cosine Amplitude, Probabilistic Seismic Hazard Assessment (PSHA), PeakGround Acceleration (PGA), Landslide Hazard Zonation (LHZ), the Himalayas
Analysis of the Factor Affecting in the recent Air Quality changes in South Korea and China in winter
Authors: Cha Yesol , Song Chang-Keun , Jeon Kwon-ho , Lim Jae-Hyun , Lim Cheol-Soo
Published: February 2023

 The factors affecting the change in air quality must be objectively analyzed, and this study used chemical transport model and observational data to investigate the contributions of each factor. The data analysis focuses on air quality changes in China and South Korea from 2016 to 2020, and existing emission data were adjusted based on observational data to reflect the trend of emission reduction into chemical transport model. The observational data revealed that in China and South Korea, respectively, the PM2.5 concentration in winter in 2020 reduced by -23.7% (-11.58 µg/m3) and -19.2% (-4.97 µg/m3) compared to 2016. Meteorological condition, emission control policy, and unexpected events are major factors which may affect the change in air quality, and each of these factors has a different effect on the concentration of PM2.5. The impact of meteorological conditions in China and South Korea in 2020, resulted in increases in PM2.5 concentration of +7.6% and +9.7%, respectively, compared to 2016. However, due to the long-term emission control polices implemented in both countries, PM2.5 concentration decreased in China (-26%) and South Korea (-5%). In addition, the newly imposed policy during the study period (winter) and the unexpected coronavirus outbreak had an impact on the PM2.5 concentration in 2020. It was discovered to have decreased by -5% and -19.5%, respectively, in China and South Korea, which was not a negligible amount. Considering the impact of each quantified factors can provide a reliable scientific foundation for upcoming policymaking or air quality assessments.This work was supported by Korea Environment Industry &Technology Institute(KEITI) through "Climate Change R&D Project for New Climate Regime." , funded by Korea Ministry of Environment(MOE) [Grant Number : 1485018907].
Spatial and temporal variation of typhoon-induced coarse-grained sediments in the muddy inner continental shelf, SE Korea
Authors: Chun Jong-Hwa , Um In-Kwon
Published: February 2023

To document the spatial and temporal variation of typhoon-induced coarse-grained sediments on the muddy inner continental shelf of the southeast Korea, we analyzed the sedimentary facies, ichnofacies, and 14C dating of 8-m-long six cores obtained from the continental shelf at water depths of 35–55 m. The mud deposits on the inner continental shelf represent the Nakdong subaqueous delta accumulation during the Holocene sea-level highstand. Typhoon-induced deposits consist of coarse-grained sandy and shelly sediments with a sharp lower contact. The upper contact is slightly deformed. Sedimentary records of the typhoon-induced coarse-grained sediments are well preserved on the shallower depocenter with high sedimentation rate in the Nakdong subaqueous delta. Grain size and thickness of the typhoon-induced deposits are increased from mid to late Holocene due to the different typhoon intensity and pathway based on the 14C dating and grain size analysis results. In addition, the Skolithos ichnofacies are dominated by high turbidity settings related to the typhoon-generated high turbulent conditions and differ from Planolites ichnofaices under fair-weather conditions. Historical records of typhoon-driven energetic conditions provide to analyze essential information of wind speeds, wave heights, coastal currents, and atmospheric pressure for predicting for future energetic conditions in the continental shelf.
Assessment of rainfall-induced shallow landslide susceptibility using a probabilistic approach and the bootstrap method
Authors: Hwang In-Tak , Park Hyuck-Jin , Lee Jung-Hyun , Ahn Sang-A , Park Hyeon-Hui , Choi Ji-Hee
Published: February 2023

Physically based landslide susceptibility analysis method, which can consider landslide occurrence mechanisms, has been widely used since it has high predictive capability. This method considers the geometric characteristics of slope and the geotechnical characteristics of slope material as input data in the analysis. However, since the uncertainties were involved in input parameters due to limited information and spatial variability of slope materials, the probabilistic analysis has been adopted to deal properly with uncertainties in input parameters. In the probabilistic analysis, the accurate statistical parameters (mean, standard deviation and probability density function) of input parameters were required. However, it is difficult to obtain sufficient information for the statistical parameters in the landslide susceptibility analysis for regional area, which means that the reliability of probabilistic analysis would be adversely affected. Therefore, in this study, the bootstrap method that could effectively deal with uncertainties caused by limited data was proposed for regional landslide susceptibility analysis. Especially, the bootstrap approach was combined with the point estimation method (PEM) because the previous bootstrap method did not provide a single value of the probability of failure as a result, which means that the results could not be presented in the form of the susceptibility map. The proposed bootstrap-PEM method was applied to the practical case to evaluate landslide susceptibility, and the analysis results were compared with the probabilistic approach using Monte Carlo (MC) simulation. The bootstrap–PEM method showed better performance than the MC simulation. In addition, the proposed approach has the advantage of readily handling the cross-correlation between variables that significantly affects the analysis results from insufficient data.
Comparison of PM2.5 Concentration Changes in Northeast Asia by pcSOA option in CMAQv5.2
Authors: Choi Jaeho , Song Chang-Keun , Kim Hyeon-Kook , Lee Kyung-Mi , Jeon Kwon-ho
Published: February 2023

The atmospheric chemical transport model, CMAQ, has been used to study the behavioral characteristics of air pollutants in Northeast Asia. To improve the performance of the simulated particulate matter, we used the CMAQ version 5.2 which newly considers pcSOA (Potential Secondary Organic Aerosol from Combustion Emissions) of fossil fuel combustion origin based on studies in North America. This study examines whether pcSOA is also effective in CMAQ modeling in Northeast Asia. Model experiments were simulated in January (Winter), April (Spring), July (Summer), and October (Autumn), representing the season in 2019, and China, South Korea, BTH (Beijing-Tianjin-Hebei), and SMA (Seoul Metropolitan Area) were selected as the target areas. To increase the reliability of the model experiment, a modeling emission inventory (e.g., UNIMIXv2) reflecting the latest air pollution emission information was used for anthropogenic emission sources in China and South Korea. According to the results of the CMAQ model experiment in January 2019, the difference between the pcSOA applied-unapplied model based on PM2.5 (particulate matter less than 2.5μm in size) concentration was about 17.23μg/m3 (-23.6%) and about 5μg/m3 (-16.5%) in China and South Korea, respectively. As a result of analyzing the chemical composition of PM2.5 simulated by the CMAQ model, ‘OC’ and ‘Unspec1’ were identified as the most affected variables by the change in the pcSOA option, and characteristics were found in the diurnal variation graph for these two substances. Therefore, when operating the CMAQv5.2 model in Northeast Asia, it is expected to help improve the model's performance in the future and understand the behavioral characteristics of air pollutants through regional and seasonal interrelated mechanisms understanding of substances caused by differences in the pcSOA option. This work was supported by Korea Environment Industry &Technology Institute(KEITI) through "Climate Change R&D Project for New Climate Regime." , funded by Korea Ministry of Environment(MOE) (1485018907)
A statistical study of superfast atmospheric precipitation of radiation belt electrons observed by POES satellites
Authors: Guo Deyu , Xiang Zheng , Ni Binbin
Published: February 2023

Atmospheric precipitation of radiation belt electrons plays an important role in the magnetosphere-ionosphere-atmosphere coupling system, which can trigger chemical and electric effects in the upper atmosphere and meanwhile generate aurorae of various types. In the regime of the quasi-linear theory, it is commonly accepted that the population of trapped electrons is no smaller than the precipitated population. However, such a concept has been proved to break down due to the nonlinear wave-particle interactions, which can drive the superfast electron precipitation. Therefore, on basis of the long-term MEPED datasets of POES satellites, we perform a comprehensive analysis of the spatiotemporal characteristics and geomagnetic dependence of superfast radiation belt electron precipitation. Our results demonstrate that superfast atmospheric precipitation of energetic electrons occurs with a non-negligible percentage with respect to the overall electron precipitation observations, and has the geomagnetic dependence similar to that of whistler-mode chorus waves.
A Study on analysis of fine particle Distribution in Busan Port Area Using Scanning LiDAR
Authors: Kim Jaewon , Shin Juseon , Joo Shohee , Noh Youngmin
Published: February 2023

Busan is Korea's largest port city. Considering the large size of the port, measurement through a single monitoring station has limitations in expressing the spatial distribution of fine particles. In this study, a Scanning LiDAR system was used to overcome the limitations of existing observations. Scanning LiDAR is a remote sensing device that uses a laser as a light source to calculate distance information. It can calculate fine particle mass concentration and distance information through signal analysis of collected light from laser light scattered backward by fine particles. It is possible to observe the fine particle concentration in real-time and continuously for 24 hours at a resolution of 30 m within a radius of 5 km and to check the spatial distribution of particulate matter using this. Scanning LiDAR is located on the rooftop of the 9th Engineering Building, Yongdang Campus, Pukyong National University, Korea (latitude: 35.11, longitude: 129.09, about 10m above ground), and was observed from March 2nd to April 28th, 2022. Residential areas, ports, industrial facilities, etc., are included in the observation range, and the average fine particle concentration by area was obtained by dividing it into six areas. ( (A) residential area, (B) steel mill, (C) Gamman Port, (D) redevelopment area, (E) shipyard, (F) berth ). Areas A, B, and C are located to the northeast of the port area, while Areas D, E, and F are located to the west and southwest. As a result of observation, the average concentration of PM2.5 and PM10 in the A, B, and C areas tended to be higher than those in D, E, and F. In the case of Area A, despite being residential, it has a high average concentration. This is because the fine particle is emitted from Area C, where ships and loading equipment are located, and Area B, where steel mills are located. This can be attributed to the diffusion and movement of fine particles discharged from the port area to the downwind side due to the influence of the south wind series, which is the main wind during the observation period.
Acknowledgement
This work was supported by the "Graduate school of Particulate matter specialization"of Korea Environment Industry & Technology Institute grant funded by the Ministry of Environment, Republic of Korea.
Numerical modeling of flow in a phosphogypsum stack. Case of salt-marshes, Huelva, SW Spain.
Authors: Coscia Franco , Vázquez-Suñè Enric , Pujades Estanislao
Published: February 2023

Phosphogypsum is a waste that results when fertilizer is obtained from phosphate through a wet chemical process. Phosphogypsum waste can entail negative consequences for the environment and human health since it is enriched in radionuclides from U-decay series and metal impurities. Phosphogypsum wastes are commonly accumulated in large stockpiles that are exposed to weathering processes. These stockpiles are located near the plants where phosphate is processed, which are usually located in coastal areas. This is the case of a phosphogypsum stack on the western side of the Tinto River estuary (Huelva, SW Spain), where the piles were directly settled on the marshland without using any isolation from 1968 to 2010. Here, in addition to the potential environmental impacts, the effect of the phosphogypsum wastes on human health are a source of concern since the piles are located near the city of Huelva (Spain). In this context, it is of paramount importance to assess the phosphogypsum leachate percolation into underlaid aquifer systems and the release of pollutants to the Tinto River.This investigation aims at building a complex coupled hydro-chemical numerical model accounting with variable density to quantify how the pollutants are released to the environment. The first step has consisted in developing the flow numerical model that has been calibrated by fitting the piezometric head oscillations as a result of recharge processes and sea tide oscillations. The good fitting obtained during the calibration process (normalized RMS when comparing simulated and observed piezometric heads is less than the 10%) allows affirming that the estimated hydraulic parameters are accurate, and are consistent with the literature reviewed. Furthermore, the numerically calculated mass balance is consistent with the conceptually estimated one, the differences were as expected. Thus, the model allows simulating the flow processes and modelling predictive scenarios. The next steps will consist in implementing variable density and hydro-chemical, and possibly, hydromechanical processes.This study, which uses numerical modelling, is intended to be useful for future work related to restoration measures and provides new insights into the water balance along with the complex processes occurring at the site.
Paleomagnetic data from recent volcanics of Piton de La Fournaise, Réunion Island: constraints on the evolution of the South Atlantic Anomaly.
Authors: Meyer Romy , van Grinsven Liz , de Groot Lennart
Published: February 2023

The South Atlantic Anomaly (SAA) is an ongoing regional minimum of the Earth’s magnetic field, located beneath South America. The field intensity there is substantially weaker than is expected from the current geocentric axial dipole moment. Currently, the SAA is observed to be expanding and gradually moving westwards. Some geomagnetic field models suggest that the SAA developed underneath the Indian Ocean and has been moving westwards since, while others propose that the anomaly originated under Southern Africa. The current field models that track the onset and evolution of the anomaly, however, are hampered by a lack of paleomagnetic data from the Southern Hemisphere.Here we present new paleomagnetic directions and paleointensity estimates from Piton de la Fournaise, an active shield volcano on Réunion Island. Réunion Island is located in the Western Indian Ocean (21°S, 55°E) and therefore ideally located to assess whether the SAA once moved from the Indian Ocean westwards, or whether it originated underneath the African continent. A recent study reporting data from Réunion Island revealed a low field intensity of around 30µT for a lava flow dated at ~1600CE. This suggests that the SAA has had an influence in the region at that time. Unfortunately, there are very few datapoints between 1400-1600CE. In our study, we sampled an additional 18 lava flows with ages between 573 and 2019CE, of which seven were deposited between 1400-1600CE. Samples are subjected to rock-magnetic analyses, thermal demagnetization and AF demagnetization methods. Obtained paleointensities with the IZZI-Thellier technique illustrate a high geomagnetic field around 1400CE, after which the field rapidly decreased until 1600CE. This behavior deviates significantly from current geomagnetic models. We discuss the implications these preliminary results have for the evolution of the SAA in the South African region.
Modeling random isotropic vector fields on the sphere
Authors: Rebischung Paul , Gobron Kevin
Published: February 2023

Thousands of permanent GNSS stations sample nowadays the 3D deformation of the Earth’s surface. The temporal covariance structure of the field of GNSS station displacements is well characterized and modelled. On the other hand, there lacks a general agreed-upon model of its spatial covariance structure, in part because the theory of random vector fields on the sphere remains hardly developed.In this contribution, we show how the well-established theory of random isotropic scalar fields on the sphere generalizes to the case of vector fields. We derive in particular a spectral representation of random isotropic vector fields on the sphere in the domain of vector spherical harmonics, from which several properties of their covariance functions follow. We then present several parametric families of covariance functions which could be used to describe and model the covariance structure of vector fields on the sphere, such as GNSS station displacements.Although this presentation focuses on theoretical aspects, it is given with future practical applications in mind. A realistic spatio-temporal covariance model of GNSS station displacements could indeed benefit different problems such as the estimation of long-term GNSS station velocities, the identification and mitigation of offsets in GNSS station position time series, the filtering of spatial “common modes” to isolate local deformation, or the spatial interpolation of GNSS station displacements into global maps. Applications may also be found in other domains involving vector quantities distributed on a sphere, e.g., winds, ocean currents, magnetic anomalies, etc.
Granular dilatancy of deforming, partially molten rock
Authors: Katz Richard F. , Rudge John F. , Kohlstedt David , Hansen Lars N.
Published: February 2023

When a confined packing of sand grains is sheared, the shear strain generates a compressive normal stress [1].  If the sand is unconfined, the shear leads to a volume expansion of the pore space between grains, low fluid pressure, and imbibition of fluid [1]. This physics is known as dilatancy [2].   We hypothesise that dilatancy occurs within a deforming, basalt-saturated aggregate of olivine grains. We extend a theory for the dynamics of partially molten rock [3,4] to describe this.  We analyse the theory in the geometry of laboratory experiments and show that the dilatancy hypothesis can explain a variety of robust, non-trivial features of experiments. These include the angle of melt bands and the inward melt segregation in torsional and Poiseuille flows [5,6].One mechanism by which partially molten rock can deform is grain-boundary sliding with geometric incompatibility between grains accommodated by mass diffusion. Dilatancy would also accommodate granular incompatibility.  The balance of diffusive and dilatant accommodation of compatibility might depend on the ratio of shear stress to confining stress.  Rock sheared by a larger stress would strain faster and potentially undergo more dilatant accommodation.  Moreover, shear strain could be associated with an anisotropy in the generated normal stress.  At smaller melt fractions, partially molten rock might create greater dilatancy stress, but would also have a smaller resistance to (de)compaction.  Our theory addresses these issues.A theory of anisotropic viscosity [7,8] has previously been proposed to explain the features of deformation experiments on olivine aggregates. We compare and contrast its physical basis and predictions with those of dilatancy.[1] Guazzelli, and Pouliquen, Rheology of dense granular suspensions, J Fluid Mech, 2018.[2] Reynolds, LVII. On the dilatancy of media composed of rigid particles in contact. With experimental illustrations. The London, Edinburgh, and Dublin Phil Mag and J Sci, 1885.[3] McKenzie, The generation and compaction of partially molten rock, J Pet, 1984.[4] Katz, The Dynamics of Partially Molten Rock, Princeton University Press, 2022.[5] King, Zimmerman, & Kohlstedt. Stress-driven melt segregation in partially molten olivine-rich rocks deformed in torsion. J Petrology, 2010.[6] Quintanilla-Terminel, Dillman, Pec, Diedrich, & Kohlstedt. Radial melt segregation during extrusion of partially molten rocks. Geochem. Geophys. Geosys., 2019.[7] Takei & Holtzman.  Viscous constitutive relations of solid–liquid composites in terms of grain boundary contiguity: 1. Grain boundary diffusion control model. JGR: Solid Earth, 2009.[8] Takei & Katz. Consequences of viscous anisotropy in a deforming, two-phase aggregate. Part 1. Governing equations and linearized analysis. J Fluid Mech, 2013.
Triggering Mechanisms of Post-Injection Induced Seismicity Using The Enhanced Geothermal System of Basel (Switzerland)
Authors: Boyet Auregan , De Simone Silvia , Ge Shemin , Vilarrasa Victor
Published: February 2023

Induced seismicity is a limiting factor in the widespread deployment of Enhanced Geothermal Systems (EGS). Induced seismicity occurs not only during injection, but also after the stop of injection, with the largest magnitude earthquakes usually occurring after the stop of injection at different scales of time (hours to months). The post-injection large magnitude seismicity is counterintuitive and is still not well understood. Multiple mechanisms have been identified as triggering induced seismicity in EGS systems. Pore pressure increase due to fluid injection is the most commonly accepted triggering mechanism to explain induced seismicity. Yet, coupled poromechanical effects and static stress transfer are also important mechanisms in the process of fault reactivation. We study the combination of these different mechanisms by simulating coupled hydromechanical processes of the Deep Heat Mining Project at Basel, Switzerland (2006), a well-known case of short-term post-injection large-magnitude seismicity. We apply the material characteristics and stress conditions of the site to a simplified 2-dimensional fault network that is based on the monitored seismic events. In our model, pore pressure has a dominant effect on the triggering of the seismicity in the vicinity of the injection well, but its effect decreases away from the well as static stress transfer and poroelastic stressing gain importance. Poroelastic stress can have a stabilizing effect when its direction is opposite to the fault slipping orientation; but an abrupt shut-in, and consequently a quick poroelastic relaxation, reactivates the fault soon after the shut-in. Later post-injection induced seismicity is partially due to the post-injection diffusion of the pore pressure, but is mainly induced by constant static stress redistribution from reactivations of the different faults of the domain. Understanding the processes inducing seismicity, and especially the post-injection large-magnitude seismicity, should enable developing better strategies of shut-in to mitigate the risks of post-injection large-magnitude seismic events.
Development of ultrahigh resolution mass spectrometry techniques to extend the molecular view of soil organic matter in solution and on mineral particles
Authors: Simon Carsten , Pietsch Paul , Stumpf Konstantin , Kaiser Klaus , Lechtenfeld Oliver
Published: February 2023

Soil organic matter plays important roles in soil reactivity and fertility as well as soil physics. Nevertheless, we know relatively little about the individual molecules that make up soil organic matter but ultimately determine its properties. Ultrahigh-resolution mass spectrometry like FT-ICR-MS has revealed an enormous molecular diversity yet it often remains limited to the water-soluble fractions (i.e., dissolved organic matter) analyzed with electrospray ionization (ESI) that represent only a small fraction of the total organic matter contained in soils. To extend the analytical window and leverage the value of non-targeted mass spectrometry, parallel analyses of soluble (via ESI) and particle-associated organic matter (PAOM) via laser-desorption ionization (LDI) and FT-ICR-MS detection is a promising approach, that has yet to prove its full potential. Here, we studied the sensitivity and robustness of the LDI technique based on a combination of dried arable soils, their aqueous DOM extracts, reference DOM samples (Suwannee River Fulvic Acid, SRFA), model compounds (syringic acid, sinapic acid, syringaldehyde, vanillic acid and tannic acid) and model mineral phases (goethite, illite). DOM samples were used to study the effects of a mineral matrix and dilution, while model compounds and SRFA were used to test the effects of laser strength and presence of an organic matrix on intact ionization of analytes. Lastly, non-extracted and extracted soil samples were used to assess if DOM composition trends observed in solution are reproduced in PAOM composition. In general, ESI ionized a very different fraction of the DOM mixture, being more polar and more saturated, while LDI ionized rather small, low-to-mid polar, and less saturated ions. Besides clear differences in PAOM and DOM analytical windows, molecular trends such as aromaticity or nominal oxidation state were well-aligned. Although most insight was gained by combining both types of analyses, our results therefore suggest that direct analysis of soil particles is a fast, reproducible, sensitive and less invasive alternative to routine protocols employing FT-ICR-MS detection, and avoids additional extraction or purification steps.
Jet streaks from a PV gradient perspective: A Lagrangian analysis of diabatic-adiabatic interaction in km-scale simulations
Authors: Bukenberger Mona , Rüdisühli Stefan , Schemm Sebastian
Published: February 2023

The jet stream is a circumpolar global band of high wind speeds in the upper troposphere. Meridional meanders of the jet lead to high-impact weather events and may synchronize them over thousands of kilometres. As a Rossby waveguide, the jet influences paths of synoptic-scale eddies, which in turn alter jet dynamics. Coherent regions of enhanced wind speed, so-called jet streaks, typify the jet locally and anomalously strong jet streaks often coincide with extreme precipitation and wind events.Despite their relevance, process understanding remains limited regarding the formation of jet streaks in interaction with lower-level weather systems. The same is true for the influence of jet streaks on Rossby wave evolution. One way to further the understanding of jet streak dynamics is to study the interaction between adiabatic and diabatic processes during jet streak evolution. However, the relative importance of those processes is difficult to disentangle. This study utilises a Lagrangian-based PV gradient perspective by applying it to a jet streak relative coordinate system to obtain composites throughout the lifecycles of multiple jet streak events. The theoretical foundation of this approach is the link between the horizontal isentropic PV gradient and wind speed. Local maxima of the normalised isentropic PV gradient are collocated with centers of jet streaks. As PV is conserved under adiabatic and frictionless flow, the PV gradient perspective allows for an investigation of diabatic-adiabatic interaction.We analyse a convection-resolving 1.1 km COSMO simulation in the eastern North Atlantic in autumn 2016, using PV gradient analysis and online air parcel trajectories to separate diabatic and adiabatic contributions to jet streak development. Cloud processes play an important role in the establishment and maintenance of a strong event, while the dynamics of a weaker jet streak is dominated by effects of adiabatic deformation.After demonstrating the approach in two case studies, we present results from a composite analysis of multiple jet streak events to achieve a more systematic understanding of diabatic-adiabatic interaction during their evolution.
The "reflexive" public administration
Authors: Barone Antonio
Published: February 2023

A peculiar aspect of the precautionary principle lays right in the reassessment and renewal of authorization provisions. Precautionary measures are provisional and subject to review upon acquisition of “new scientific information” or development of “best available technologies”. In the European administrative integration process, the re-examination of public decisions adopted in situations of scientific uncertainty reflects the idea of a permanent correspondence between the administrative function and the public interest (in cases of human and environmental safety). Because of such on-going correspondence, the administrative function cannot be fossilized in one single administrative provision (e.g., the authorization), but rather must adapt to the (ever changing) need of the public interest. Such idea also shows the need to reconsider the principle of administrative continuity: from an organization-based moment to a functional one. The authorization of an industrial activity potentially harmful to human and animal health or the environment initiates an administrative relationship that is “unstable” ab origine. Such relationship with the Administration has a “procedural” character (maintained even after the authorization’s grant), which is characterized by a permanent modification of the administrative function. Therefore in a risk-based logic, all procedures of authorization, renewal and re-examination cannot be strictly separated one from each other and take the shape of an administrative function that gradually and permanently creates the features of the very administrative relationship itself. This happens along a continuum that seems not to distinguish between procedures of “first” or “second” degree. Similarly, also risk management cannot be exhausted in the single authorization procedure. Risk management sets itself aside from the single administrative procedure and performs its many potentialities before, during and after the authorization’s renewal and re-examination. Precaution, as a principle of administrative action, calls for the duty to evaluate thereby enhancing or (arguably) exacerbating the duty to pursue the public interest. In “risk law”, the action of public authorities cannot exhaust itself in one single administrative provision. The global relevance of the administrative function finds its expression in the continuous re-examination of the decisions taken in light of the evolution of the scientific and technological datum. It is right in the duty to evaluate and re-assess the scientific datum that the sociological concept of “reflexive” Administration becomes legally relevant.