bluuebunny/crossref_metadata_2025 huggingface dataset:
Sediment connection modes of check dams and its effects for sediment interception efficiency in the loess hill and gully region
Authors: Jiao Juying , Bai Leichao , Wang Nan , Chen Yulan
Published: February 2023

The Loess Plateau is the area with the most serious soil erosion in China, and its control of soil erosion has always been a focus of attention and research. As an important engineering measure of soil and water conservation, the check dam plays an irreplaceable role. However, the effect of connection mode between check dam and downstream channel is not considered in the evaluation of sediment interception efficiency of check dam, which may lead to the high calculation result. In this study, in order to evaluate the sediment interception efficiency of check dam more accurately, the control areas of Caoping hydrological station in Wudinghe River Basin and Ganguyi hydrological station in Yanhe River Basin were taken as study areas, and 24 typical dam-controlled watersheds with different land use types, 4 typical small watersheds with different combinations of check dam were selected, the check dam types and their connection modes between check dam and downstream channel were investigated and analyzed, and the sediment interception efficiency of check dam was estimated. According to the difference of connectivity between check dams and downstream channels, there are 11 types of connection modes between check dam and downstream channel: disconnected, connected with spillway, connected with shaft or horizontal pipe, connected with spillway and shaft or spillway and horizontal pipe, connected with shaft, horizontal pipe and spillway, connected with dam body damaged gap, connected with discharge canal, connected with discharge canal and shaft, connected with discharge canal–spillway, connected with discharge canal–shaft and spillway, connected with discharge canal–dam body damaged gap. Based on the actual control area percentage of dam land, the structure connectivity of sediment between check dam and downstream channel was evaluated. The results show that the structure connectivity of sediment is mainly affected by the discharge canal and its length. The sediment interception efficiency of dam system is greater than the sum of single dams. If there is no drainage channel at the bottom of the key check dam, the sediment interception efficiency of the whole dam system will be greatly increased. The results show that the sediment interception efficiency would be 9.74–18.78% higher if the connection mode is not considered. And extreme rainfall increased the sediment connectivity between check dams and downstream channels, thus greatly reduced the sediment interception efficiency of check dams.
Impacts of tide and cavity geometry on ocean-driven melting beneath the Nansen Ice Shelf
Authors: Kim Taekyun , Hong Ji-Seok , Moon Jae-Hong , Jin Emilia Kyung
Published: February 2023

Mass loss from ice shelves occurs through ocean-driven melting regulated by dynamic and thermodynamic processes in sub-ice shelf cavities. However, the understanding of these oceanic processes is quite limited because of the scant observations under ice shelves. Here, a regional coupled sea-ice/ocean model that includes physical interactions between the ocean and the ice shelf is used as an alternative tool for exploring ocean-driven melting beneath the Nansen Ice Shelf (NIS), Terra Nova Bay (TNB), Antarctica.We will first show the spatiotemporal variability signatures for different modes of ocean-driven melting at the base of the NIS. Our model includes detailed bathymetry and ice shelf base topography based on in-situ observation and has been run with and without tides. We have also investigated how tide and model geometries (i.e., cavity geometry) affect the water mass transformations and ice shelf melting/freezing regimes at the base of the ice shelf which significantly affect the ice shelf stability.
Micropaleontological study of the Miocene Dam Formation, Eastern Province of Saudi Arabia
Authors: Chan Septriandi , Kaminski Michael , Humphrey John
Published: February 2023

There is relatively little information on the taxonomy of foraminifera found in Saudi Arabia's Cenozoic formations compared with those from the Mesozoic formations. Four outcrops in the Al Lidam area, eastern province of Saudi Arabia have been studied to document the Miocene foraminiferal assemblages. Acetic acid was used to extract foraminifera from lithified carbonate rocks from 80 samples representing seven lithofacies. Results of disaggregation using acetic acid are promising. In total, 46 species of benthic foraminifera have been identified. The foraminifera are dominated by calcareous porcelaneous Miliolina (Coscinospira, Sigmoilinita, Peneroplis, Quinqueloculina, Triloculina), followed by hyaline genera (Ammonia, Cibicides, Discorbinella, Elphidium), a few agglutinated forms (Textularina), but planktonic foraminifera are absent. Borelis melo melo indicates that the studied formation is dated to Burdigalian to Langhian age. Based on the identified species, the studied formation is interpreted as having been deposited in an arid subtropical environment in hypersaline waters that were present on a restricted and very shallow carbonate platform (inner ramp). The foraminiferal faunas of the present-day Arabian Gulf show similarity with the Miocene faunas. Thus, the present-day Arabian Gulf provides a highly suitable modern analog for earlier Cenozoic conditions in the region.
High-precision GNSS-R Altimetry based on Carrier Phase Measurement Combination
Authors: Xu Tianhe , He Yunqiao , Gao Fan , Meng Xinyue
Published: February 2023

Abstract: Global Navigation Satellite System-Reflectometry (GNSS-R) technique has been used to obtain sea surface height (SSH) since the 1990s. Due to the short wavelengths and low power of GNSS signals, the continuously tracked carrier phase measurements of reflected signals are usually unavailable for sea surfaces with big roughness, varying over space and time. Under high sea states, the phase difference cannot be well retrieved from carrier phase measurements, especially for the signals with high elevation angles. To overcome these shortcomings related to temporal incoherence, we propose an improved algorithm to extract the combined interferometric phase difference measurements between direct and reflected signals. We improve the configuration of GNSS-R altimetry software-defined receiver (SDR) by reconstructing ‘clean’ direct signals to compute phase differences between direct and reflected signals. The interferometric phase differences are combined in the complex domain and the resulting interferometric signal is refined through open-loop tracking with 60-s coherent integration before the phase difference measurements are extracted, without tracking their respective carrier phase measurements in advance.  In order to verify our method, a coastal experiment under different sea conditions was conducted. Raw intermediate frequency data of Quasi-Zenith Satellite System were collected and processed by SDR to compute the path delay measurements of L1 and L5. Under high sea states, the phase delay measurements of L1 and L5 were random over time, while phase delay can still be well recovered based on the proposed method even in the case of high elevation angles. The altimetry solutions were compared with the in situ observations from a radar altimeter instrument. The results show that centimeter-level altimetry accuracy can be achieved under high sea states using the proposed method The same SDR and method are applied in the shipborne altimetry experiment, the interferometric phase observations are successfully extracted on both ship motion and statics. Also, the integer ambiguity in the interferometric phase observations is well estimated. The differences in the SSH measurements between different satellites is at centimeter level. The coastal and shipborne experiments demonstrate that the dual-antenna GNSS-R phase altimetry technique can be used for low-cost tide gauges on different platforms to monitor sea levels.Acknowledgments: This work was supported by Natural Science Foundation of China (42192534) and Key Research and Development Program of Shandong Province (Major Technological Innovation Project, 2021ZDSYS01).
Application of machine learning in predicting flow and transport in porous media
Authors: Mostaghimi Peyman , Wang Ying da , Chung Traiwit , Armstrong Ryan
Published: February 2023

Micro-CT imaging and pore-scale modelling have developed rapidly over the last decade by bridging the disciplines of geology, reservoir engineering, image processing, and computational fluid dynamics. They have provided new pathways for understating complex transport phenomena in heterogeneous geological formations. However, direct simulation of flow in these complex three-dimensional geometries can be difficult and time-consuming. Machine learning and Convolutional Neural Networks (CNN), as a part of the broader field of Artificial Intelligence (AI), can be integrated into the framework of pore-scale modelling. We propose a neural network architecture that considers features of the rock geometry as well as the conservation of mass and predicts the velocity distribution on the images. The method can be applied to two or three-dimensional rock images. The reliability of the flow prediction is studied by comparing the predicted permeability versus ground truth values as a bulk measure. Then, we study the accuracy of solute transport modelling. The results show that velocity fields obtained by CNN can have a considerable degree of error and are not suitable for accurate transport simulations. Finally, challenges and opportunities for the development of machine-learning approaches in porous media applications will be discussed.
Identifying the Deep-inflow Mixing Features in Orographically Locked Diurnal Convection
Authors: Chang Yu-Hung , Chen Wei-Ting , Wu Chien-Ming , Kuo Yi-Hung , Neelin J. David
Published: February 2023

This study focuses on the deep-inflow mixing features of the orographically locked diurnal convection, involving interactions between local circulation and the thermodynamic environment of the convection. Under the weak synoptic weather regime, orographically locked diurnal convection is a typical summertime phenomenon in Taiwan, a tropical island in the Asian monsoon region. Numerical simulations are carried out using the vector vorticity equation model with high-resolution Taiwan topography (TaiwanVVM), which can appropriately simulate the characteristics of diurnal convection and the evolution of boundary layer and local circulation. The semi-realistic approach, simplified by observed soundings as the uniform initial condition over the entire domain, emphasizes the decisive environmental factors that modulate the development of convection, representing the variability of the background environment by the ensembles. The analyses by the deep-inflow mixing framework, including the locally-derived convective structures and the upstream moist static energy (MSE) transport, improve the understanding of the interactive physical processes in the boundary layer development and local circulation evolution of orographically locked diurnal convection over complex topography. The convective structures of the deep-inflow mixing, increasing vertical velocity and convective mass flux with height through a deep lower-tropospheric inflow layer, are found in strong convective updraft columns within heavily-precipitating systems over precipitation hotspots. While the topography constrains the location of the convection, enhanced convective development is associated with higher upstream MSE transport through this deep-inflow layer via local circulation, augmenting the rain rate by 35% in precipitation hotspots. The results highlight the importance of non-local dynamical entrainment of the deep-inflow, transporting MSE via local circulation to supply the growth of orographically locked diurnal convection. Thus, the deep-inflow mixing framework can serve as the theoretical basis for describing the orographic locking feature of diurnal convection over complex topography. Guided by the simulations, the Storm Tracker mini-radiosondes are released upstream of the precipitation hotspot, targeting observations within the most common deep-inflow path. Initial field measurements support the presence of high MSE transport within the deep-inflow layer when organized convection occurs at the precipitation hotspot.
Transient Tropopause Waves
Authors: Dörnbrack Andreas
Published: February 2023

Horizontally short gravity waves are often observed near the tropopause. Here, airborne observations of mountain waves over southern Scandinavia are used to characterize these waves and to detect non-stationary modes. A series of two-dimensional numerical simulations is used to explain the generation of these transient wave modes that are trapped in the lowermost stratosphere and propagate horizontally downstream along the tropopause inversion layer. The numerical results reveal on which external parameters the properties of the short waves depend on. It turns out that the interaction of wave breaking aloft in the middle atmosphere and the tropospheric flow is the essential process explaining the generation of these non-stationary modes. Their characteristics is controlled by the sharpness of the tropopause inversion layer, the strength of the orographic forcing and, partially, by the spectra of the underlying orography exciting the vertically propagating mountain waves.
Nonlinear site-response of vertical ground motions
Authors: Kamai Ronnie , Frid Michael
Published: February 2023

The importance of vertical ground motions for design continues to gain recognition, as more evidence shows that vertical ground motions can significantly exceed their horizontal counterparts on very soft soils, at short source-site distances, and at short spectral periods. Assuming that the vertical component is largely comprised of compressional P-waves, new approaches and models are required to constrain the expected linear and nonlinear site response of the vertical component.In this study, we combine empirical analysis with laboratory experiments, to study and define the nonlinear behavior of the vertical component. We use 27 Kik-net stations to analyze nonlinearity of dry sandy deposits, comparing the full vertical component with the P-wave window, to help define the partial contribution of P-waves to the entire vertical component. We develop modulus degradation and damping (MRD) curves for the case of uncoupled and coupled shear-compression response. In addition, we compare the empirical MRD curves with experimental MRD curves, describing the response of sandy soil to cyclic compressional loading under Ko conditions. We show that vertical ground motions are less nonlinear than their horizontal counterpart, for the same incoming ground motion. We also show that pure P-waves are less nonlinear than the full vertical motion, suggesting that the vertical component is comprised of a combination of P and SV waves, thus implying that vertical site-response analysis should include both shear and compression-related properties and procedures.
Variability of the Indonesian Throughflow and Australian monsoon dynamism across the Mid Pleistocene Transition (IODP 363, Site U1483)
Authors: Matsuzaki Kenji , Holbourn Ann , Kuhnt Wolfgang , Gong Li , Ikeda Masayuki
Published: February 2023

The Mid-Pleistocene Transition (MPT) between ~1200 and ~800 ka was associated with a major shift in global climate and was marked by a change in glacial/interglacial periodicity from ~41 to ~100 kyr that resulted in higher-amplitude sea-level variations and intensified glacial cooling. The Indonesian Throughflow (ITF), which controls the exchange of heat between the Pacific and Indian Oceans, is a major component of the global climate system. On the other hand, Asian-Australian Monsoon dynamics play a key role in regional primary productivity. Therefore, reconstruction of ITF and Asian-Australian Monsoon variability during the MPT could potentially clarify the impact of the glacio-eustatic sea level changes on the climate and ecosystem of Northwest Australia. The International Discovery Program (IODP) Expedition 363 retrieved an extended, continuous hemipelagic sediment succession spanning the past two million years at Site U1483 on the Scott Plateau off Northwestern Australia.In this study, we analyzed radiolarian assemblages in core top samples retrieved during the RV Sonne Expedition 257 and downcore samples from IODP Site U1483 to estimate the variability in regional sea surface temperatures (SSTs) during the MPT, and to explore ITF dynamics in relation to glacio-eustatic sea-level variations and tropical monsoon strength. We suggest that glacio-eustatic sea-level variations have been a key factor affecting changes in SSTs at Site U1483, primarily because the shallow and hydrogeographically complex nature of the sea means that SSTs are highly sensitive to glacio-eustatic sea-level variation. Based on comparisons with SST data from the mid latitudes off Northwest Australia and the South China Sea, we suggest that the SSTs at Site U1483 are highly dependent on prevailing climate changes in the northern hemisphere rather than changes in the climate of the Southern hemisphere. In addition, comparisons of radiolarian total abundances with X-ray fluorescence-scanning elemental data suggested that, until the onset of the MPT (~1200 ka), radiolarian productivity was higher during strong summer monsoons during interglacial periods, probably because of the high riverine runoff generated by heavy summer monsoonal precipitation. However, since ~900 ka, there appears to have been a shift in the mode of radiolarian productivity that has resulted in increased radiolarian productivity during glacial periods when the delivery of nutrients is increased due to the enhanced mixing of the upper water column in the shallow sea caused by strong trade winds. 
Exploring the Effectiveness of Using Risk Reduction Instruments to Hedge against Extreme Rainfall Events in the Framework of Extreme Value Theory
Authors: Hsu Yaowen , Ho Shih-Ping , Hou Yu-An
Published: February 2023

Risk management for natural disasters is an important issue, especially in a rainy country like Taiwan where extreme rainfall can lead to significant economic losses. However, the availability of financial tools to diversify catastrophic risk is limited in the local insurance market. Therefore, this study aims to explore the effectiveness of financial tools used by some countries in the past to hedge against natural disaster risk. These financial tools were based on the concept of alternative risk transfer (ART). The goal of this study is to create a financial module within a natural disaster model to calculate the financial losses caused by Taiwan's monsoon, typhoon, and convectional rainfall, and produce expected losses table (ETL Table). The study then use the statistical framework of extreme value theory (EVT) to simulate the loss caused by these three types of rainfall in the form of extreme events. This will provide a more accurate assessment of the potential economic impact of these types of natural disasters on Taiwan. Furthermore, the study uses the CIR (Cox-Ingersoll-Ross) stochastic process to simulate Taiwan’s overnight interbank lending rate (Taiwan LIBOR). This is important because changes in the interbank lending rate affects the cost of borrowing for businesses and individuals, which in turn can impact the overall economy. By understanding how the interbank lending rate changes in the event of a natural disaster, financial institutions and policymakers can make more informed decisions about how to respond to such events. Finally, the study uses the Monte Carlo method to price catastrophe bonds, insurance, and futures. This provides a more accurate assessment of the potential financial value of these instruments, which can be used to hedge against natural disasters. By understanding the value of these financial tools, investors can therefore make more informed decisions about how to allocate their resources to protect against potential losses caused by natural disasters. Overall, this study strives to gain a deeper understanding of the financial tools that can be used to hedge against natural disaster risk, and how these tools can be applied to reduce the economic losses caused by extreme rainfall in Taiwan. By understanding the successes and challenges of these tools in other countries, Taiwan can better design and implement its own risk management strategies to protect against the financial impacts of natural disasters. The authors gratefully acknowledge the financial support from the National Science and Technology Council of Taiwan ( Grant Number: 111-2124-M-002-006) 
Sinkholes evolution in coastal settings: some examples from Southern Italy
Authors: Parise Mario , Liso Isabella Serena
Published: February 2023

The southernmost sector of Apulia Region can be described as a karst peninsula surrounded by the Adriatic and the Ionian Seas. The process of seawater intrusion, together with groundwater outflow, mainly coming out at the coastline, produces a water mixing that enhances the solution of soluble carbonate rocks. The effect of these processes can be observed along the coastline, characterized by several areas interested by sinkhole development and evolution. In some cases, they have become famous touristic attraction as at Grotta della Poesia, visited every summer by thousands of tourists; in other cases they represent spectacular sites of high ecological values, since they host peculiar ecosystems, with many fauna and flora species. At several sites along the Apulian coasts, sinkhole evolution form elongated bays, completely protected from sea waves, as in the sector between Fasano and Brindisi. Along this coastal stretch, field surveys revealed different sinkholes stages that can be described as successive phases in the development of bays: from opening of individual collapse sinkholes, typically at distance lower than 20 m from the coastline, to evolution in elongated sinkholes deriving from coalescence of nearby features, eventually leading to the final stage, with formation of protected bays, which main elongation depends upon the main discontinuity systems in the rock mass, and the main direction of sea storms as well. These examples highlight the importance of sinkhole processes in predicting the future evolution of the coast, and may be of help to local authorities for the most proper management of such a fragile environment.
Experimental and numerical simulation of the reactive contaminant migration for non-Darcian flow in a filled-single fracture
Authors: Pandey Snigdha , Sharma Pramod Kumar
Published: February 2023

Accurate prediction of flow and solute migration through the subsurface porous media is essential for the reclamation of the polluted aquifer and future contamination control. This study focuses on the dispersion process under non-Darcian flow conditions in the laboratory using a synthetic single fracture. A sand-packed single fracture of 1000 cm length and 0.3 cm fracture aperture was fabricated in the laboratory for conducting flow and contaminant transport experiments. Non-Darcian flow conditions prevailed in the filled-single fracture and were best simulated by the Forchheimer equation. Sodium Flouride (NaF) was used as a reactive contaminant in the experiments and was injected using Pulse-type boundary conditions. The resulting Breakthrough Curves (BTCs) were found to be non-Fickian with long tailings and early arrival. Solutions of the Convective-Dispersive equation (CDE) and Mobile Immobile (MIM) transport equations (for constant, linear, and exponential distance-dependent dispersion) were obtained through the Implicit finite difference technique. For different flow velocities, the MIM model was better at simulating the long tailings and early arrival of BTCs. Further, it is observed that constant (MIMC) and exponential distance-dependent (MIME) dispersion models are better at simulating observed BTCs compared to the linear-distance dependent (MIML) dispersion model. Through the statistical analysis and goodness of fit, the suitability of MIME and MIMC in describing contaminant transport through fracture was further confirmed.Keywords:  non-Fickian; Filled-single fracture; non-Darcian; Breakthrough curves; Forchheimer equation; MIM model.
Soil carbon quantity and form are controlled predominantly by mean annual temperature along 4000 km North-South transect of Eastern China
Authors: Gu Jie , Bol Roland , Sun Yajie , Zhang Huanchao
Published: February 2023

The forest ecosystem plays a key role in mitigating global climate change through carbon sequestration in its biomass and soils to limit the rising atmospheric concentration of CO2. However, the combined overall interaction of climate and forest type on the quantities and forms of soil carbon (organic vs. inorganic) has not yet been sufficiently investigated. In this study, the contents of soil total carbon (STC), soil organic carbon (SOC) and soil inorganic carbon (SIC) were measured along the 4000 km North-South Transect of Eastern China. We sampled 252 soil samples (6 replicates for each site, 3 depths for each site) from four long-term ecosystem  experimental stations in Dinghushan, Shennongjia, Beijing and Changbaishan, along the transect from south to north, including 14 different forest types. The contents of STC, SOC, and SIC in the upper 60 cm soil layer varied in different types of forest with 34–107 g C kg−1, 31–104 g C kg−1, and 1.5–8 g C kg−1, respectively. The northern fir and birch forest, most notably in Changbaishan, had the highest STC and SOC contents. The higher SIC contents were found in the southern evergreen broad-leaved forests in Dinghushan and Shennongjia. The contents of STC, SOC and SIC differed significantly in terms of mean annual temperature (MAT), mean annual  precipitation (MAP), forest type, and soil depth. In the upper 60 cm soil layer, the most significant correlations occurred between SOC (or STC) and MAT (R2SOC = −0.62, R2STC =−0.60) when compared with the correlation between SOC (or STC) and MAP (R2SOC= −0.45, R2STC=−0.45) or elevation (R2SOC=0.48, R2STC=0.48). The soil stratification ratio (SR) of STC and SOC were typically ~2–3 in most forests and even reached 5–7 in Changbaishan forest, indicating a well-functioning ecosystem overall. We concluded that on the near-continental scale (4000 km), forest soil carbon contents and forms (SOC, STC, SIC) were controlled most strongly by temperature (MAT). Therefore, an innovative selection of a specific forest type (fir or broad-leaved forest) within set temperature regimes can better contribute to maximizing soil carbon content and thus optimize its sequestration on the national to near-continental scale to mitigate climate change.
Fossils in the mountains: Understanding the relationship between biodiversity and geography during the Early Palaeozoic
Authors: Harper David
Published: February 2023

Fossils in the mountains: Understanding the relationship between biodiversity and geography during the Early Palaeozoic The eminent Alpine geologist, Rudolf Trümpy once stated, ‘One bad fossil is worth a good working hypothesis’. Although characterized by poor preservation, fossils have for many decades provided age and geographic constraints on the evolution of the World’s mountain belts. Palaeontological data helped expose horizontal and lateral crustal movements and signalled the importance of continental drift as a planetary-scale process. In Europe and North America the bioregionality of many fossil groups has provided key data for the definition of continents, microcontinents and volcanic arcs and their movements during the Early Palaeozoic. Moreover, identification of species pumps and refugia in the island terranes of the Iapetus and related oceans, now exposed along the length of the Caledonian-Appalachian orogenic belt, has enhanced our knowledge of the Great Ordovician Biodiversification Event and the Late Ordovician Mass Extinction. Mechanisms for the diversification and extinction of taxa can be hypothesized and many terranes hold key evidence on the early evolution and phylogeny of marine animal groups. The movement of most crustal units towards lower latitudes and their carbonate environments during the later Ordovician is correlated with the highest species richness of the period terminated by the intense, short-lived Hirnantian ice age.
Multi-analytical characterization of a Reykjanes Peninsula (Iceland) basalt
Authors: Stoicescu Daniel , Dumitras Delia , Duliu Octavian , Panaiotu Cristian , Costin Gelu , Zinicovscaia Inga , Dinca George , Necula Cristian , Porosnicu Ioana , Culicov Otilia
Published: February 2023

To get more data concerning de geochemistry and volcanology of Reykjanes Peninsula (Iceland) lavas, more high-precision analytical methods such as Instrumental Neutron Activation Analysis (INAA), Electron Microprobe Analysis (EMPA), X-ray Fluorescence (XRF), X-ray Diffraction (XRD), ICP-MS, X-ray microtomography (XRMT) and magnetism, coupled with mineralogical investigations were used. INAA, EPMA, XRF and ICP-MS were used to determine both major and trace element mass fractions. In the case of major elements, despite some differences inherent utilization of different analytical techniques, all analysis suggested a tholeiitic composition. Several discriminating diagrams clearly emphasize the subalkaline and tholeiitic trend, while the tectonic discrimination diagram assigned a “continental affinity”, as well as the existence of a minor crustal contamination. At their turn, the distribution of incompatible trace elements, represented into several discriminating diagrams, in agreement with PetDB database on Reykjanes Peninsula, as well as Hawaii and St Helen volcanic rocks, confirming the previous hypothesis based on major elements distribution on the tholeiitic and evolved character of the Reykjanes Peninsula lava, with an affinity towards ocean island basalts with traces crustal contamination. The results of mineralogical as well as BSE images analysis evidenced an abundance of plagioclase (albite), pyroxene (augite and pigeonite), as well as Fe-Ti oxides, while minerals such as olivine and spinel were less present. XRMT images revealed the presence of a multitude of vesicles showing preferred orientations, most probable due to lava flow, as the XRMT images loaded into stacks and analyzed by appropriate image analyzing software suggested. This particular features could suggest the existence of an important amount of volatiles, which lowering lava viscosity make them visible among larger vesicles. Raman spectroscopy results concerning the phases of each mineral, compared with literature and RRUFFTM database confirmed previuous finding concerning the geochemistry of investigated Reykjaned Peninsula basalt sample. A magnetic analysis, performed by means of FORC diagrams as well as magnetic susceptibility dependence on temperature and the magnetic field, evidenced the presence of titanomagnetite as a main magnetic present in the sample.Therefore, all analyses suggested that the investigated basaltic lava present a tholeiitic composition, with an evolved continental affinity, but not related to rifting. The structural features suggests the presence of an important amount of volatiles existed prior the eruption.
Modelling inter-event times from central volcanoes at São Miguel Island (Azores)
Authors: Aguiar Simone , Sandri Laura , Pimentel Adriano , Pacheco José
Published: February 2023

Central volcanoes can produce a wide spectrum of volcanic eruptions, with different magmatic compositions, styles, sizes, and recurrence periods. On volcanic islands, the eruptive record of central volcanoes is often incomplete, due to the small subaerial area, irregular topography, and high erosion rates typical of these islands, generating large uncertainties about the past eruptive activity and making the estimation of eruptive parameters, recurrence times and probabilities of future eruptions very challenging.São Miguel Island (Azores archipelago) is one of these cases, where most eruptions of the three active central volcanoes (Sete Cidades, Fogo, and Furnas) are undated or poorly reconstructed. Based on the known stratigraphy, Sete Cidades volcano erupted at least 36 times in the last 15 ky, producing 24 trachytic events, almost all explosive, and 12 basaltic flank eruptions; Fogo volcano erupted at least 21 times also in the last 15 ky, producing 16 trachytic explosive eruptions and 5 basaltic flank eruptions; while Furnas volcano erupted at least 22 times over the last 17 ky, all trachytic explosive events.Here, we model eruptive event times based on the generation of synthetic catalogues that follow the known stratigraphic sequence and include the uncertainty of eruption ages. The completeness of the eruptive records of each volcano was assessed by plotting the cumulative number of eruptions in time and identifying breaks in slope, which may indicate changes in the recording rate of events, as well as possible changes in the eruptive behaviour. In the parts of catalogues after the first break-in-slope we also checked the stationarity to identify the portions of the catalogues that could be modelled by renewal models. Fitting the stationary portion of data with several renewal models allowed to identify which statistical model best describes how eruptive events occur in time. This study presents a statistical analysis where data uncertainties are accounted for to model eruptive inter-event times, estimate recurrence periods and probabilities of future eruptions. This approach is crucial for a more robust long-term assessment of volcanic hazard, providing important clues to forecast the eruptive behaviour of central volcanoes, even in cases of low-activity systems or volcanic islands, where eruptive catalogues are frequently incomplete. In the case of São Miguel this approach allowed to estimate recurrence periods and the probability of a future event for each of the three active central volcanoes of the island. 
Evaluating the capacity of PlanetScope satellites for fine-scale phenology monitoring across temperate forests in eastern North America
Authors: Zhao Yingyi , Lee Calvin K.F. , Wang Zhihui , Wang Jing , Gu Yating , Xie Jing , Law Ying Ki , Song Guangqin , Bonebrake Timothy C. , Yang Xi , Nelson Bruce W. , Wu Jin
Published: February 2023

In temperate forests, leaf phenology – the study of the timing of periodic and recurring events in leaves – is a sensitive indicator of climate change and a main regulator of carbon and water cycling. Many studies have evidenced large intra-site leaf phenology variability across individual trees. However, monitoring individual tree-scale leaf phenology with conventional approaches (e.g., field observations and phenoCam observations) is often restricted to a small spatial extent and sample size. The availability of PlanetScope data with high spatial and temporal resolution offer opportunities to overcome this limitation, but comprehensive assessments of its capacity for individual tree-scale phenology monitoring is lacking. To fill this knowledge gap, we proposed a method that integrates 0.1 m resolution airborne imagery and ground phenology records of individual trees with time-series PlanetScope observations to monitor fine-scale phenology. We tested this method at six NEON forest sites in eastern North America. Our results show that PlanetScope-derived land surface phenology is able to 1) characterize significant individual tree-scale leaf phenology variability across different forest sites and years, with r ranging from 0.21 to 0.42 when comparing PlanetScope-derived phenological metrics with their ground correspondences at the individual tree scale. The relationship between PlanetScope-derived phenology and ground phenology observations is stronger at the species level (r=0.57-0.82) when more PlanetScope pixels are included; and 2) capture more variability in fall phenology but also with larger uncertainties (e.g., r=0.82 and RMSE=2.14; species level) compared with spring phenology (r=0.76 and RMSE=0.72). Additionally, when comparing with ground methods, PlanetScope satellites are also advantageous for providing spatially explicit information across large spatial coverages. These findings collectively demonstrate that PlanetScope data displays the capacity for fine-scale leaf phenology monitoring, and it also has the potential to provide rich fine-scale phenology information to advance the field of plant phenology research.
Dynamic Pressure Variations in the Lower Crust Caused by Localized Fluid-Induced Weakening
Authors: Jamtveit Bjørn , Moulas Evangelos , Kaus Boris
Published: February 2023

When continents collide, the Earth’s crust experiences structural and metamorphic transformations that control the geodynamic evolution of the orogen. Metamorphism of dry, lower crust requires fluid supply and produce mechanically weaker rocks. Metamorphism is often localized in shear-zones, which provide the available fluid pathways. Several field-based studies show that shear zone development is preceded by brittle faults, frequently portraying evidence for seismic slip rates and introduction of externally derived fluids. However, despite the extensive documentation of lower crustal metamorphism and associated deformation features, a unifying model coupling deformation to fluid migration and metamorphic reactions does not exist. Here, we present a visco-elasto-plastic model where the most pertinent features observed in transformed lower crust emerge from basic mechanical principles during the deformation of a coherent rock volume with associated fluid introduction. Characteristic features include a strikingly dynamic and heterogeneous pressure distribution in the reacting and deforming rock volumes. Lower crustal pressure variations may reach 1 GPa at any given depth. This will have first order effects on the pattern of fluid migration in the lower crust, and may also explain the apparent discrepancies between the relevant tectonic settings and petrologically-inferred burial depths. An additional petrological consequence of the positive pressure variations is the generation of fluid-undersaturated high-pressure assemblages. For common bulk-rock compositions that are observed in the Bergen Arcs (Norway), and for finite amounts of fluid, phase equilibria modelling results suggest that the quasi-isothermal pressurization will lead to the formation of H2O-undersaturated metamorphic rocks. These results highlight the importance of coupling between metamorphic reaction progress and deformation at high-grade conditions.  Acknowledgements:This project was supported by a research award from the Alexander von Humboldt foundation to BJ, by ERC Advanced Grant Agreement n°669972 to Jamtveit and ERC Consolidator Grant Agreement n°771143 to Kaus from the European Union’s Horizon 2020 Research and Innovation Programme. Parts of this research were conducted using the supercomputer MOGON2 and/or advisory services offered by Johannes Gutenberg University Mainz (hpc.uni-mainz.de), which is a member of the AHRP (Alliance for High Performance Computing in Rhineland Palatinate, www.ahrp.info) and the Gauss Alliance e.V. Andrew Putnis and Håkon Austrheim are acknowledged for numerous discussions. References:Moulas, E., Kaus, B., Jamtveit, B., 2022. Dynamic pressure variations in the lower crust caused by localized fluid-induced weakening. Communications Earth & Environment 3, 157. https://doi.org/10.1038/s43247-022-00478-7
Radar backscattering properties of lava flows on Earth and Venus
Authors: Murra Allegra , Mastrogiuseppe Marco , Alberti Giovanni , Gambacorta Letizia , Seu Roberto
Published: February 2023

VERITAS mission, recently selected as part of NASA's Discovery program, will allow the investigation of the geological history of Venus, the mapping of its surface to study volcanic and tectonic processes and giving to scientists a unique opportunity to understand its geological activity. The spacecraft will carry the instrument VISAR, an interferometric X-band synthetic aperture radar (SAR) that will provide global 30 m medium resolution imagery of the surface and topographic maps with a spatial resolution of 250 m and a height accuracy of 5 m.Looking at VERITAS mission, our work combines information obtained both from Digital Elevation Models (DEM) and SAR data acquired over time, in order to study terrestrial lava flows properties. We selected the Pacaya volcano in Guatemala and, supported by the corresponding geological maps, we identified and isolated some of its relevant lava flows. We used  SENTINEL-1 SAR data acquired at C band and surface local incidence angle obtained from high resolution DEMs,  to study lava flows backscattering coefficient behavior with respect to the incidence angle variation, along with EM formulation. Through fitting theoretical models, scattering laws provided us an estimate for lava flows dielectric properties and roughness. Our research shows a backscattering behavior which changes among different lava flows, in addition we find a seasonal behavior of the backscattering as function of the wet/dry periods of Pacaya. This behavior would not have been detectable without the initial lava flows segmentation, performed before the overall analysis. This selection indeed made possible the study of backscattering coefficient of regions with separately uniform and stationary surface parameters.
Statistical uncertainty analysis-based precipitation merging (SUPER): A new framework for improved global precipitation estimation
Authors: Dong Jianzhi , T.Crow Wade , Chen Xi , Tangdamrongsub Natthachet , Gao Man , Sun Shanlei , Qiu Jianxiu , Wei Lingna , Gao Hongkai , Duan Zheng
Published: February 2023

Multi-source merging is an established tool for improving large-scale precipitation estimates. Existing merging frameworks typically use gauge-based precipitation error statistics and neglect the inter-dependence of various precipitation products. However, gauge-observation uncertainties at daily and sub-daily time scales can bias merging weights and yield sub-optimal precipitation estimates, particularly over data-sparse regions. Likewise, frameworks ignoring inter-product error cross-correlation will overfit precipitation observation noise. Here, a Statistical Uncertainty analysis-based Precipitation mERging framework (SUPER) is proposed for addressing these challenges. Specifically, a quadruple collocation analysis is employed to estimate precipitation error variances and covariances for commonly used precipitation products. These error estimates are subsequently used for merging all products via a least-squares minimization approach. In addition, false-alarm precipitation events are removed via a reference rain/no-rain time series estimated by a newly developed categorical variable merging method. As such, SUPER does not require any rain gauge observations to reduce daily random and rain/no-rain classification errors. Additionally, by considering precipitation product inter-dependency, SUPER avoids overfitting measurement noise present in multi-source precipitation products. Results show that the overall RMSE of SUPER-based precipitation is 3.35 mm/day and the daily correlation with gauge observations is 0.71 [−] – metrics that are generally superior to recent precipitation reanalyses and remote sensing products. In this way, we seek to propose a new framework for robustly generating global precipitation datasets that can improve land surface and hydrological modeling skill in data-sparse regions.
PSO-SVR Rainfall Forecast-Assisted Real-time Optimal Operation of Urban Drainage Systems
Authors: rezaie Adaryani Fatemeh , Mousavi S. Jamshid , Jafari Fatemeh
Published: February 2023

One of the most effective parameters in hydrologic modeling and water resource management issues such as flood warning and real time control of urban drainage systems is short term rainfall forecasting accuracy [1]. In recent decades, developing real-time urban flood forecasting models has been investigated through various studies and different machine and deep learning models have been applied as a prediction model [2]. For instance, in [3], the role of short-term rainfall forecasts in predictive real-time optimal operation (PRTOP), for five adaptive PRTOP models, have been compared.In this study, based on the result of the [1], one of the superior rainfall forecasting models, the machine learning-based particle swarm optimization (PSO)-support vector regression (SVR) rainfall forecasting approach, is used to develop a 15-minute ahead forecast model of rainfall depth. The PSO-SVR model is linked then to the harmony search (HS)-storm water management model (SWMM) as an optimization-simulation model in a predictive real-time operation model to minimize the flood volume, objective function = min (flood volume), at the control point of a portion of an urban drainage system in Tehran, Iran. Subsequently, the effect of integrating forecasting model with the simulation-optimization model (HS-SWMM) has been examined.The application of the proposed real-time operation approach through optimizing the operation of the system for eight selected rainfall events, each of them has been selected from different classes, reveals its outperformance over a reactive real-time operation model (RTOP) by decreasing the flood volume at the control point up to 7.5%. Keywords: Urban Drainage Systems, Short-term Rainfall Forecasting, Real-time Operation, Machine Learning. [1] Adaryani, F. R., Mousavi, S. J., & Jafari, F. (2022). Short-term rainfall forecasting using machine learning-based approaches of PSO-SVR, LSTM and CNN. Journal of Hydrology, 614, 128463.[2] Piadeh, F., Behzadian, K., & Alani, A. (2022). A critical review of real-time modelling of flood forecasting in urban drainage systems. Journal of Hydrology, 127476.[3] Jafari, F., Mousavi, S. J., & Kim, J. H. (2020). Investigation of rainfall forecast system characteristics in real-time optimal operation of urban drainage systems. Water Resources Management, 34(5), 1773-1787.
Evidence of Fresh Injections Related to the Interchange Instability in the Io Torus
Authors: Kurth William , Hospodarsky George , Sulaiman Ali , Mauk Barry , Clark George , Allegrini Frederic , Connerney Jack , Bolton Scott
Published: February 2023

The Juno Waves instrument often detects brief, band-limited emissions when the spacecraft crosses magnetic fields threading Io’s M-shell, or vicinity thereof, up to about 30 degrees magnetic latitude. The disturbances have durations of order one minute and are observed below the electron cyclotron frequency. While plasma densities are often not available, it is thought that the frequency of the events are below the plasma frequency of the surrounding medium. Often, the first electron cyclotron half-harmonic is weakened or disrupted at the time of the events. While the events can be seen in isolation, there are typically a few of them with temporal spacing between about 15 to 40 minutes. Similar features were commonly seen by the Cassini radio and plasma wave instrument at Saturn and were identified as ’fresh’ injections or evidence of inward-moving flux tubes due to the centrifugal interchange instability. As such, they were characterized as having depleted thermal plasma and enhanced energetic plasma with electron distributions unstable to wave modes such as the upper hybrid band and chorus. Such events were also observed by Galileo. As fresh injections, the energetic particles associated with them have not had time to drift in longitude due to gradient and curvature drift forces.