bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary results of IODP Expedition 401, the first element of the Miocene Mediterranean-Atlantic Gateway (IMMAGE) Land-2-Sea drilling project
Authors: Flecker Rachel , Ducassou Emmanuelle , Williams Trevor ,   IODP Expedition 401 participants
Published: March 2024

Warm and saline Mediterranean overflow today is an important driver of thermohaline circulation in the North Atlantic. In the latest Miocene, Mediterranean salinity varied dramatically as the Messinian salt giant formed. The precipitation of a ~1.5 km thick evaporite layer across the Mediterranean seafloor requires substantial changes both to the geometry of the Atlantic-Mediterranean gateway and the nature of exchange between the two basins. This salinity crisis was the consequence of on-going Africa-Eurasia collision, which formed, narrowed, and ultimately closed the two ancestral marine connections that pre-date the Gibraltar Strait. One of these connections is now preserved on land in southern Spain, the other in northern Morocco. Both the initiation of Mediterranean overflow, variations in its size and salinity, and the establishment of the present-day overflow pattern in the early Pliocene are likely to have impacted thermohaline circulation, climatic change and deep water sedimentation during the late Miocene and Pliocene.IMMAGE (Investigating Miocene Mediterranean-Atlantic Gateway Exchange) is a land-2-sea drilling project designed to recover a complete record of Late Miocene-Pliocene exchange (8-4Ma) offshore with International Ocean Discovery Program (IODP) in both the Atlantic and Mediterranean and onshore with International Continental Scientific Drilling Program (ICDP) in Morocco and Spain. IODP Expedition 401 is the first element of the land-2-sea drilling to take place. At the time of abstract submission, Expedition 401 is at sea (December 2023-February 2024) in the process of recovering these critical records. We propose to present an overview of the sediments recovered during the expedition and initial shipboard analytical results.
Measurement and analysis of anomalous diffusion in porous rock
Authors: Berkowitz Brian , Rajyaguru Ashish , Metzler Ralf , Dror Ishai , Grolimund Daniel
Published: March 2024

Molecular diffusion, or more specifically, diffusion-controlled transport, of tracers, contaminants, and chemical species --- in soil and rock formations, and in river, lake, and marine sediments --- plays a critical role in many dynamic processes that affect water chemistry and properties of the host domain. The spreading of dissolved ionic species via Brownian motion is generally described by a Gaussian law for the probability density function, with diffusion (embodying Fick’s second law) then being described by the classical diffusion equation. Solution of this equation shows that the spreading pattern of chemical species is characterized by a mean squared displacement that scales linearly with time. However, in other porous domains like biological tissues and cells, dense liquids, and gels, diffusion behavior often deviates from Fickian, instead exhibiting anomalous (or non-Fickian) diffusion. More specifically, tracer movements in these “crowded environments” exhibit a spreading pattern wherein the mean squared displacement scales as a power law. Somewhat surprisingly, in studies involving water-saturated porous rock, diffusion of chemical species is generally assumed to follow Fick’s second law, ignoring the possible occurrence of anomalous diffusion. To test this assumption, we measure molecular diffusion in five chalk and dolomite rock samples using a specially designed diffusion cell. The set-up enables high-resolution measurement of extended, long-time tailing at the measurement plane, which is required to distinguish between Fickian and anomalous diffusion behavior. In all of the rock samples, the diffusion behavior is demonstrated to be significantly different than Fickian, with extreme long-time tailing of tracer advance relative to conventional Fickian diffusion. The measured breakthrough curves are then analyzed using a continuous time random walk framework that describes anomalous diffusion in heterogeneous porous materials. The analysis (i) provides a framework to distinguish between Fickian and anomalous diffusion, and (ii) demonstrates that anomalous diffusion in geological formations is likely ubiquitous and implies that diffusion-controlled transport processes should be analyzed using tools that account for such behavior.
Assessment of climate simulation over the Tibetan Plateau based on multidomain simulations within CORDEX-II
Authors: Niu Xiaorui , Li Ping
Published: March 2024

The climate simulation over the Tibetan Plateau (TP) remains a challenge for climate models, limiting the reliability of future climate projections over there. This study focuses on the performance of regional climate models (RCMs) under the Coordinated Regional Climate Downscaling Experiment (CORDEX-II) in reproducing the climate over the TP, an overlapping regions that is encompassed by the CORDEX-EA, CORDEX-CA and CORDEX-WA, and assesses the uncertainty due to the choice of domain. The results show that all RCMs can capture the observed spatial distribution and annual cycle of temperature and precipitation over the TP, with overall cold and wet biases. Compared to the RCM itself, the choice of domain has little impact on the simulations, and such impact is larger in summer than in other seasons. Further analysis suggests that the downward shortwave radiation is the main contributor to the diverse temperature simulations among the RCMs for all seasons, and the underestimated number of wet days (R1mm) in the RCMs may be related to the lower frequency of 1-5mm rainfall. Furthermore, the effects of the choice of domain on precipitation simulation are mainly in the magnitude, while the effects on temperature simulation are mianly in the interannual variability.
Impact of iron fertilisation on Southern Ocean ecosystems and global carbon cycle during the last glacial cycle
Authors: Saini Himadri , Meissner Katrin , Menviel Laurie , Kvale Karin
Published: March 2024

Rising atmospheric CO2 concentration is a major driver of climate change. One of the several processes proposed to explain the lower atmospheric CO2 concentration during the last glacial period is an increase in aeolian iron flux into the Southern Ocean. As the Southern Ocean is a high-nutrient-low-chlorophyll region, increased iron deposition can impact Southern Ocean marine ecosystems,  increase export production, and reduce surface Dissolved Inorganic Carbon (DIC) concentration. Here, we investigate the responses of Southern Ocean marine ecosystems to changes in iron flux and their impact on ocean biogeochemistry and atmospheric CO2 during the last glacial period. We use a recently developed complex ecosystem model that includes four different classes of phytoplankton functional types and fully incorporated iron, silica and calcium carbonate cycles. We show that the changes in atmospheric CO2 are more sensitive to the solubility of iron in the ocean than the regional distribution of the iron fluxes. If surface water iron solubility is considered constant through time, we find a CO2 drawdown of ∼4 to ∼8 ppm. However, there is evidence that iron solubility was higher during glacial times. A best estimate of solubility changing from 1 % during interglacials to 3 % to 5 % under glacial conditions yields a ∼9 to 11 ppm CO2 decrease at 70 ka, while a plausible range of CO2 drawdown between 4 to 16 ppm is obtained using the wider but possible range of 1 % to 10 %. We also show that the decrease in CO2 as a function of Southern Ocean iron input follows an exponential decay relationship, which arises due to the saturation of the biological pump efficiency and levels out at ∼21 ppm in our simulations.We also investigate the role of iron flux changes on the abrupt atmospheric CO2 increase during Heinrich Stadials, which are associated with a near collapse of the Atlantic Meridional Overturning Circulation (AMOC), a sudden decrease in Greenland temperature and warming in the Southern Ocean. Previous modelling studies have investigated the role of the ocean circulation in driving changes in atmospheric CO2 concentration during these abrupt events, while the role of reduced aeolian iron input during Heinrich stadials remained poorly constrained. We show that a weakened iron fertilisation during Heinrich Stadials can lead to ~6 ppm rise in CO2 out of the total increase of 15 to 20ppm as observed. This is caused by a 5% reduction in nutrient utilisation in the Southern Ocean, leading to reduced export production and increased carbon outgassing from the Southern Ocean.
A Systematic Overview of Hazard Interrelationships in the Philippines
Authors: Ybañez Richard , Lagmay Alfredo Mahar Francisco , Malamud Bruce
Published: March 2024

Natural hazards interrelationships include one natural hazard process triggering or influencing another (e.g., an earthquake triggering a landslide) and often contribute to the severity of disasters. This study focuses on a methodology for systematically providing an overview of natural hazard interrelationships in the Philippines. We first explore the breadth of single hazards that might occur in the Philippines, subdividing them into 22 different natural hazard types (with groupings of geophysical, hydrological, shallow-earth, atmospheric, biophysical, space). A 22x22 natural hazard interaction matrix is subsequently developed to identify primary natural hazards that could potentially trigger or increase the probability of secondary natural hazards. Then, for each potential interrelationship (e.g., earthquake-flood) we critically review the literature to find evidence whether that interrelationship might occur, based on past case histories or theory. In total, we use 250 sources, consisting of local scientific and grey literature, and civil defence bulletins. The detailed information is synthesized into a database of 12 types of information (e.g., process, primary and secondary hazards, date and period). Interactions without existing records in the Philippines, but plausible based on global literature, are also incorporated. A total of 76 interrelationships out of a possible 484 were identified. High-impact interrelationships between natural hazards commonly observed in the Philippines include earthquake-triggered landslides, rainfall-induced landslides, and subsidence. Less common hazard interrelationship examples are the 2022 Abuyog landslide-tsunami and the 2008 Panay landslide-flood. The majority (34 out of 76) of the primary hazards involved geophysical hazards such as earthquakes, volcanic eruptions, and landslides, triggering or increasing the likelihood of other geophysical hazards, flooding, and shall earth hazards. Tropical storms, having a very high frequency in the Philippines, also trigger or increase the likelihood of several secondary hazards. The number of unique interactions (76) identified in the matrix continues to grow as more literature, both in the Philippines and globally, are collected. This matrix would serve to inform scientists, policymakers, and first-responders on possible secondary hazards in anticipation of an impending natural hazard impact. The Philippines’ geologic and meteorological setting exposes it to a large variety of high frequency and magnitude natural hazards necessitating the identification of historical and hypothetical hazard interactions for the purpose of preparedness and mitigation.
Study on the gravity flow depositional system of three sections of the Dongying Formation in the eastern slope zone of the Chengbei Low Bulge in the Bohai Bay Basin
Authors: Zhou liangyu , Zhang liqiang
Published: March 2024

Abstract: In order to clarify the sedimentary characteristics and spatial evolution of the deep-water gravity flow deposits of the third segment of the Dongying Formation in the eastern slope belt of the Chengbei Low Uplift, under the guidance of sedimentology and sequence stratigraphy, the sedimentary characteristics, sand body distribution, sedimentary facies distribution characteristics, and evolution rules of the study area were analyzed in depth by analyzing the seismic response characteristics of the seismic profile, the combination morphology of logging curves, and the core debris. The results show that the eastern slope belt of the Chengbei Low Uplift is divided into nearshore subaqueous fans (nearshore turbidite fans) and lakebed fans (farshore turbidite fans) under the control of material sources and paleogeography. The distribution of sedimentary facies belts, fan body distribution area, sand body extension direction, and distribution pattern on the plane are controlled by the lake level, material source supply, and paleogeomorphological changes. The steep slope zone (fault zone) controls the sedimentary body with a continuous thickness of thick sand bodies that extend forward in the direction of the source and have a band-like distribution, which is a nearshore subaqueous fan. The gentle slope zone (slope zone) gradually develops into a lakebed fan with a larger scale and thinner sand distribution. It is concluded that during the sedimentary period of the third segment of the Dongying Formation in the study area, the lake level changes control the size of the gravity flow sedimentary distribution; the size of the material source supply controls the degree of development of the deep-water gravity flow sedimentation; the orientation of the material source supply controls the deep-lake-deep water gravity flow turbidite fan sedimentation mode in the distribution area of the gravity flow sedimentation, providing a geological basis for the study of the sand body development law within the fan body and oil and gas exploration and development in the study area.Keywords: Chengbei Low Uplift; Dongying Formation; gravity flow; sedimentary system; sand body distribution.
Arctic sea ice drift fields extraction based on feature tracking to MODIS imagery
Authors: Fang Yan , Wang Xue , Li Gang , Chen Zhuoqi , Hui Fengming , Cheng Xiao
Published: March 2024

Moderate-resolution optical imagery holds great potential in deriving Arctic sea ice drift fields because of its higher resolution than microwave radiometers and scatterometers, as well as its larger swath widths than most other optical and synthetic aperture radar (SAR) images. However, the application of such imagery is hindered by cloud influences and a lack of texture. In this study, we propose a method of deriving Arctic sea ice drift fields based on applying feature tracking to Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. To enhance the quality of the feature tracking step, a bundle of digital image processing techniques is first introduced, including histogram equalization which is based on the Cumulative Distribution Function (CDF) of the sea ice area, and Laplacian filtering which enhances image texture. Various MODIS bands and A-KAZE parameter settings are subsequently compared to balance the quality of sea ice drifting fields and calculation efficiency. Three pairs of MODIS images observed in different zones of the Arctic Ocean are selected to evaluate the performance of the proposed method. International Arctic Buoy Programme (IABP) buoy data are employed for validating the derived drift vectors with MODIS imagery. The results show that our proposed method effectively increases the number of vectors and their coverage rates of the sea ice drift fields extracted with MODIS images. The coverage rates of sea ice drift fields in three regions increase from 4.8%, 2.3%, and 2.5% to 56.5%, 23.5%, and 53.0% compared to using the A-KAZE algorithm directly, respectively. The MAEs of the derived sea ice motion vectors are 707 m/d in speed and 6.4° in direction, superior to the sea ice drift products based on the Advanced Very High Resolution Radiometer (AVHRR) imagery. The proposed method enables MODIS and other medium-resolution optical data to be utilized in deriving Arctic sea ice drift fields, which is of great significance to the long-term and large-scale Arctic environment, climate, and oceanography research in the future. 
Analysis of Upper Paleozoic trace element characteristics and paleoenvironmental significance in the Gubei area of Jiyang depression
Authors: Zhang Zhitong
Published: March 2024

The Upper Paleozoic in Gubei area of Jiyang Depression has a good combination of source, reservoir and cap, and has a good exploration prospect. The basic research on sedimentology and geochemistry of Upper Paleozoic restricts the oil and gas exploration of target strata. Moreover, the application of element characteristics is rarely applied, and there is almost no research on the longitudinal sedimentary environment evolution characteristics, and the research on paleo-environment and paleoclimate is not systematic enough. The core of the Upper Paleoozoic core bank in Gubei area was taken as the sample. The NITONXL 2·GOLDD handheld X-ray ore element analyzer of Thermo Scientific was used to test the element content of the sample, and the longitudinal variation rule of trace elements was analyzed. The enrichment degree and ratio of trace elements corresponding to different lithologies indicate the characteristics of paleoenvironment and paleoclimatology. Combined with the analysis of the geochemical characteristics of trace elements and rare earth elements, the core of three Wells (Gubeigu 1, Gubeigu 2 and Yi 136) was systematically measured and the content and ratio of elements were studied. The paleo-salinity, paleo-climate, paleo-water depth and REDOX degree of Upper Paleozoic sedimentary period in Gubei area are systematically discussed, which provides reliable evidence for the recovery of sedimentary environment evolution in this area. Among them, Gubei Gu1 well, Gubei Gu2 well and Yi 136 well are all fresh water deposits of continental facies, indicating arid climate, oxidation environment and shallow water depth.Keywords: Gubei area; Upper Paleozoic; trace element; paleoclimate; paleoenvironment
Tree ring oxygen isotope in Asia 
Authors: Xu Chenxi , Huang Ru , An Wenling , Zhao Qingyu , Zhao Yaru , Ren Junbo , Liu Yucheng , Guo Zhengtang
Published: March 2024

Tree-ring oxygen isotope (δ18OTR) is a powerful proxy for paleoclimatology, ecology and archaeology, δ18OTR studies in Asia over the past ~50 years have made signiffcant achievements in improving our understanding of Asian climatic and ecological systems. Here, we review these developments in δ18OTR research in Asia. Most study sites are located within East Asia, Southeast Asia, South Asia, and North Asia, and δ18OTR records from conifers, broadleaf trees, and shrubs have been produced. Progress has been made in the following areas: (1) Experimental techniques. The novel plate method for cellulose extraction has been developed, which reduces experimental time and greatly improves efffciency. (2) Development of δ18OTR chronologies. Ninety-six chronologies exceeding 200 years in length have been produced. A 4354-year δ18OTR chronology with an annualresolution has been produced in Japan, and a 6700-year δ18OTR chronology with a 1–5 year resolution has been produced in the northeastern Tibetan Plateau, which is the longest in Asia. (3) Biological inffuences on δ18OTR. Variations of intra- and inter-tree and inter-species δ18OTR have been investigated, and the relationship between tree age and δ18OTR has been explored. (4) Climatic implications. Seasonal δ18OTR records primarily reffect the variability of precipitation δ18O, facilitating high-resolution paleoclimate reconstructions, while interannual δ18OTR records mainly reffect summer moisture variability. (5) Climate reconstructions. Quantitative estimates have been produced for past precipitation, relative humidity, PDSI (Palmer Drought Severity Index), runoff, and other parameters from δ18OTR records. Since 1850, δ18OTR chronologies in monsoon regions show upward trends indicative of drying, while these from westerlies regions exhibit downward shifts implying wetting. (6) Dating. Intra- and inter-annual δ18OTR records help determine the annual growth of trees without rings and facilitate the cross-dating of trees with rings. Thus, the dating of archaeological and buried wood is feasible via comparisons with δ18OTR master chronologies. Promising areas of development include climatic implications (e.g., Position-speciffc isotope analysis, seasonal δ18OTR records on longer timescales and larger spatial scales), climate reconstructions (syntheses of multiple sites and records, development of long chronologies, deep time paleoclimate reconstructions) and ecological applications (e.g., the response of trees to climatic extremes, and the combinations with multiple tree-ring multiple proxies such as width and density). 
How the structure of rarefaction regions develops?
Authors: Ďurovcová Tereza , Šafránková Jana , Němeček Zdeněk
Published: March 2024

As the solar wind streams propagate with different speeds through the interplanetary space, they meet and interact. This leads to the formation of large interaction regions, one of which is the rarefaction regions (RRs). RRs develop at the trailing edge of the fast solar wind stream and come from an area of small longitudinal extent on the Sun. They exhibit a fine and complex structure, and the stream interface position is usually unclear. Superposed epoch analysis of the proton and alpha parameters for different regions within RRs reveals gradual transitions in many of them. Moreover, majority of our observations show that most of the RR plasma parameters correspond to the fast solar wind characteristics, only the alpha-proton drift velocity decreases from the beginning of RR. We investigate different ways of its reduction in the interplanetary space and show that this feature is likely associated with the mirroring of the multi-component solar wind. We identify the composition boundary where the alpha relative abundance and alpha-proton temperature ratio change abruptly from the values typical for the fast wind toward slow wind values. We suggest that this boundary is the most probable candidate for the stream interface. Based on these findings, we speculate that the RR formation occurs near the Sun and formulate two possible scenarios.
Toward Net Zero in the midst of the Energy and Climate Crises: the Response of Residential Photovoltaic Systems 
Authors: Piazza Lucia , Colelli Francesco Pietro , De Cian Enrica , Pasut Wilmer
Published: March 2024

This paper aims to provide insights on potential strategies for a sustainable energy transition amidst market fluctuations. We analyze the impact of PV adoption on electricity consumption during a volatile price time span, leveraging high-frequency consumption data of over 10,000 households in Northern Italy during the period of the 2022 energy crisis. Our findings reveal that PV adoption reduces electricity consumption responsiveness during extreme price and temperature events, enhancing energy security and affordability. Also, PV uptake effectively reduces greenhouse gas emissions deriving from electricity consumption in the residential sector. Based on estimated demand, we measure changes in consumer surplus loss, highlighting substantial benefits from PV adoption: the change in the annual consumer welfare due to the 2022 price increase is around minus 300 euros for the median consumer with no PV and minus 133 euros when PV is adopted by a comparable median household.  This study exploits high-frequency data of households residing in the municipality of Brescia between 2021-2022 to infer the impact of PV adoption and the influence of temperatures on grid electricity consumption, as well as to detect potential differences in price elasticity among different consumption groups and seasons. We find that adopting PV systems significantly reduces grid consumption: by 75% on average and by as much as 100% during sunny hours and warmer seasons. Exploiting the exogenous Russia-Ukraine price shock, we find that households who adopt solar PV are more likely to better manage increased temperatures at higher electricity price levels and price fluctuations. Furthermore, we find that "small" consumers can cope worse with high temperatures and are more sensitive to electricity-prices compared to "medium" and "large" consumers, highlighting electricity as a relevant source of inequality.
Evaluation of Shannon Entropy-based Information transfer in nonlinear systems 
Authors: Pires Carlos , Vannitsem Stéphane , Docquier David
Published: March 2024

We present a general theory for computing and estimating Shannon entropy-based information transfer in nonlinear stochastic systems driven by deterministic forcings and additive and/or multiplicative noises, by extending the Liang-Kleeman framework of causality inference to nonlinear cases. The method presents effective and computable formulas of the rates of information transfer between sets of causal and consequential system variables, relying on the evaluation of conditional expectations of the deterministic and stochastic forcings (Causal Sensitivity Method: CSM). The CSM can work with a) ensemble model runs, b) system time series in ergodic conditions and c) time series without a priori knowledge of model equations. The CSM also allows to express the information transfer parcels, which are attributable either to one-to-one interactions or to synergies across groups of variables and assess where the information is more relevant in the state space. The CSM is tested in two proof-of-concept low-order models: 1) a nonlinear model derived from a potential function and 2) the classical chaotic Lorenz model, both forced by additive and/or multiplicative noises. The CSM is also tested with a nonlinear regression model of the ice-cover time evolution, forced by radiation. The CSM estimation is much more robust and efficient than methods using the stochastic model’s full probability density function and its derivatives, whose estimation is rather unreliable in case of short data availability. The analysis also demonstrates that the CSM estimation is computationally cheap in the different experiments, providing evidence of the possibilities and generalizations offered by the method, thus opening new perspectives on real-world applications. This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020(https://doi.org/10.54499/UIDB/50019/2020),UIDP/50019/2020(https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020) and the project  JPIOCEANS/0001/2019 (ROADMAP). 
Chronostratigraphy of glaciomarine sediments off the West Greenland Shelf: a key to the understanding of the Quaternary evolution of the Greenland ice sheet
Authors: Zhang Yang , Faust Johan , Römer-Stange Nikolas , von Dobeneck Tilo , Kucera Michal
Published: March 2024

Six gravity cores (GC) and four sea-floor drill rig (MeBo) cores from water depths of ~1800–1400 m have been successfully collected off the outer Disko Bay fan in eastern Central Baffin Bay during the research expedition MSM111 in 2022. These sediment cores provide an up to 125 m long (MeBo 14, 20 and 23) record potentially reflecting the late- and mid-Pleistocene dynamics of the Western Greenland ice sheet. Besides the presence of a few turbiditic sequences a continuous sedimentation is well supported by the parasound seismostratigraphy as well as by lithostratigraphic log correlation based on X-ray Fluorescence (XRF) and magnetic susceptibility (MS). Establishing a chronostratigraphy of the Baffin Bay glaciomarine sediments is, however, challenging as e.g., carbonate dissolution impedes reliable foraminiferal δ18O stratigraphy.Here, we present our preliminary chronostratigraphic framework established by combining three stratigraphic tools: radiocarbon ages, relative paleointensity (RPI), and characteristic basin-wide detrital carbonate layers (BBDCs). BBDCs represent periods of elevated terrigenous deposition in response to increased meltwater discharge that can be well identified by XRF Ca/Ti. The GC 12&22 and MeBo 14&20 cores contain rhythmic alterations between sandy-rich detrital carbonate layers and clayish layers, which are clearly represented by Ca/Ti and MS data. Intriguingly, these cyclic alterations also display significant correlation with marine isotope stages (MIS), where higher Ca/Ti and MS values correspond to warmer periods. We thus estimated that our 125-m composite core lasts until MIS 16 or ~700 ka. This long duration is also partly supported by our RPI data from MeBo 20&23. Nevertheless, two major difficulties were encountered: (1) RPI data of GC 24&21 do not reveal an unambiguous match with global RPI reference stacks and/or regionally established RPI records, probably due to condensed sedimentation of these two deeper gravity cores; and (2) recurring BBDCs of the studied cores can be interpreted as high-frequency events reflecting the intrinsic dynamics of the North American Arctic-ice sheet complex, or, alternatively as glacial-interglacial cycles. In order to solve the current chronostratigraphy controversy between a Late Pleistocene age or of deeper mid-Pleistocene age, further carbon-14 ages from the condensed GC24 and collect RPI data from the more expanded MeBo 14 will be obtained.
Exploring the role of tropospheric stationary waves for the North Pacific response to SSWs
Authors: Wu Rachel Wai-Ying , Afargan-Gerstman Hilla , Domeisen Daniela I.V.
Published: March 2024

Stratospheric variability can have a significant impact on surface weather extremes in winter, in particular during stratospheric extreme events, so-called sudden stratospheric warming (SSW) events. The stratospheric downward impact has been shown to be communicated by both planetary-scale and synoptic-scale waves, but their relative roles and interactions are not fully understood. Since there is a strong average response to stratospheric forcing over the North Atlantic but a weak response over the North Pacific, studies of SSW downward impact generally focus on the North Atlantic, where the synoptic eddy-feedback plays a strong role. We here examine the relative roles of planetary-scale waves for the North Pacific after SSW events. By examining the case-by-case response over the North Pacific following SSW onset using ERA5 reanalysis, we identify differences between events in terms of their interactions between the wave anomalies induced by the stratosphere and the tropospheric stationary waves. Specifically, the destructive and constructive interference of zonal wavenumber-1 anomalies plays a dominant role in contributing to different responses over the North Pacific, which are associated with an equatorward and a poleward jet shift, respectively. We suggest that SSW events can exhibit opposite responses over the North Pacific, potentially explaining the generally weak response observed in this region when averaging across all SSW events.
Anthropogenic forcing inconsistently exacerbates global drought
Authors: Li Hongwei
Published: March 2024

Untangling the impact of anthropogenic forcing on drought is particularly essential for climate change mitigation. Previous studies have indicated that anthropogenic forcing exacerbates drought, raising concerns about global drought evolution, yet little is known about the impact of anthropogenic forcing on drought evolution through anthropogenic greenhouse gases (GHGs) and aerosol (AER). We integrated standardized precipitation evapotranspiration index (SPEI) data under different experiments to study drought development with Coupled Model Intercomparison Project Phase 6 (CMIP6) global climate models (GCMs). Subsequently, we conducted sensitivity analyses to quantify the changes in drought sensitivity to anthropogenic greenhouse gas (DSG) and aerosol (DSA) from 1900 to 2014. Our findings reveal different effects of AER and GHGs on drought trends during three periods. Specifically, GHGs slightly increased global drought severity in the early 20th century. Conversely, from 1956 to 1982, the drought-mitigating effects of AER surpassed the drought-enhancing effects of GHGs, and the global was humidified. Then, from 1982 to 2014, the trends of increasing DSG and decreasing DSA suggest that an important global shift is taking place. GHG re-emerged as the primary driver, thus leading to increased drought severity. Taken together, these findings elucidate how anthropogenic forcing impacts global drought severity through drought-enhancing effects of GHGs and drought-mitigating effects of AER, which provides new insights into understanding the risk of anthropogenic impacts on global drought.
Investigation of the Interfacial Transition Zone (ITZ) in asphalt mastic and its effect on the integrity of the mix: A Raman hyperspectral approach
Authors: Chakraborty Tuhin , Unitt Richard , Meere Pat
Published: March 2024

In the context of a circular economy, increasing the durability of existing infrastructure is of paramount importance. Roads are the lifelines of the modern economy, and it is imperative to increase their lifespan as part of sustainable growth. Most conventional roads are a mixture of rock aggregate and bitumen. The region where bitumen meets aggregate in any asphalt mix experiences a complex interaction between electrostatic, chemical, and mechanical forces resulting in the formation of an Interfacial Transition Zone (ITZ) (Zhu et al. 2017). More specifically, there is a complex behavior of materials that could result from three different types of interaction between the aggregates, fillers, and bitumen: i) physisorption ii) chemisorption iii) mechanical interlocking (Pasandín and Perez 2015).The integrity of the ITZ is one of the crucial factors for the overall durability of any mixture containing aggregate and binding materials. Due to the complex interaction of different minerals, present in the rock aggregate, with the bituminous binder, this junction is considered a weak link that dictates the overall structural durability of the mixture (Zhu et al. 2021). Most of the studies concerning the ITZ are based on mechanical tests at the aggregate-bitumen contact and generally do not include mineralogical observations.The present study focuses on the ITZ within laboratory-manufactured asphalt samples utilizing rock aggregate varieties typically used in surface courses in the Republic of Ireland. Structural and petrographic observations are made using a combination of digital microscopy and Raman spectroscopy. Early observations suggest that there is a strong control exerted by aggregate mineralogy on the formation of features within the ITZ, including the linear alignment of iron oxide particles in the bitumen. Iron-oxide particles could potentially create a zone of weakness in a stone-mix asphalt, especially where the key aggregate is greywacke.ReferencesZhu et al. 2017; Identification of interfacial transition zone in asphalt concrete based on nano-scale metrology techniques, Materials and Design. 129, 91-102.
Pasadin and Perez, 2015; The influence of the mineral filler on the adhesion between aggregates and bitumen, International Journal of Adhesion and Adhesives.
 
Seedling dynamics under the pressure of El Niño drought in a seasonally dry tropical forest in Northern Thailand
Authors: Nutiprapun Prapawadee , Hermhuk Sutheera , Marod Dokrak , Kanzaki Mamoru , Nanami Satoshi , Itoh Akira
Published: March 2024

El Niño’s impact on tropical forests is critical, as reduced rainfall and severe drought induced by this phenomenon affect species diversity and tree dynamics. As seedling is a crucial stage for forest regeneration to maintain population and species diversity in the forest, it is important to understand how El Niño-induced drought affects seedling dynamics. We monitored the seedling dynamics at monthly intervals for 7 years in a seasonally dry tropical forest (SDTF). We analyzed the differences in seedling recruitment and mortality during the El Niño and non-El Niño periods and compared two forest types in an SDTF: a deciduous dipterocarp forest (DDF) dominated by deciduous species, and an adjacent lower montane forest (LMF) with more evergreen species. The long-term data on seedling dynamics revealed that El Niño-induced drought triggered immense seedling mortality in both forest types. This effect was stronger in evergreen species, leading to higher mortality in the LMF during El Niño. However, El Niño increased seedling recruitment only in the DDF, mainly because of the massive recruitment of the deciduous oak, Quercus brandisiana (Fagaceae), which counterbalanced the seedling mortality in the DDF. Consequently, El Niño increased seedling density in the DDF while decreasing it in the LMF. Our findings showed that the El Niño-induced drought effects on seedling dynamics varied by forest type and leaf habit, suggesting that future changes in drought regimes may alter the species composition and spatial distribution of Asian seasonally dry tropical forests through differences in the response of seedlings to drought.
Formation of multistage garnet grains by fragmentation and overgrowth constrained by microstructural and microchemical mapping
Authors: Manzotti Paola , Regis Daniele , Petts Duane , Graziani Riccardo , Polivchuk Matthew
Published: March 2024

Garnet is an exceptionally useful mineral for reconstructing the evolution of metamorphic rocks that have experienced multiple tectonic or thermal events. Understanding how garnet crystallizes and its mechanical behaviour, is important for establishing a petrological and temporal record of metamorphism and deformation, and to recognize multiple geologic stages within the growth history of an individual crystal. In this study, we integrate fine-scale microstructural (EBSD) and microchemical (LA-ICP-MS mapping) data obtained on a polycyclic garnet-bearing micaschist from the Alpine belt. Results suggest that fragmentation of pre-Alpine garnet porphyroblasts occurred during the late pre-Alpine exhumation and/or the onset of the Alpine burial, such that the older pre-Alpine garnet fragments were transported/redistributed during Alpine deformation and acted as new nucleation sites for Alpine garnet growth. These processes produced a bimodal garnet size distribution (macro mm-sized and micro sub-mm-sized grains). Thermodynamic modelling indicate that Alpine garnet grew during the final stage of burial (from 1.9 GPa 480 °C to 2.0 GPa 520 °C) and early exhumation (down to 1.6 GPa 540 °C) forming continuous idioblastic rims on macro- and micro-grains, and sealing fractures preserved in pre-Alpine garnet porphyroblasts. We propose that fragmentation-overgrowth processes coupled with ductile deformation in polycyclic rocks may produce a bimodal garnet size distribution and form multistage crystals resembling neoblasts. This study highlights the importance of linking microstructural (EBSD) and microchemical (LA-ICP-MS mapping) data by providing valuable information about the dominant deformation mechanisms at a given site by identifying potential links between major/trace element mobility and crystal deformation.
Hydrothermal sealing and erratic explosive behaviour at Turrialba, Poás, and Rincón de Vieja volcanoes (Costa Rica)
Authors: Heap Michael , Avard Geoffroy , Baud Patrick
Published: March 2024

Reductions to the permeability of a volcanic system can increase pore fluid pressure and, in turn, promote volcanic hazards such as erratic explosive behaviour and slope failure. Hydrothermal alteration, ubiquitous at volcanoes worldwide, is one mechanism thought to reduce permeability and therefore increase volcanic hazard potential. Turrialba, Poás, and Rincón de Vieja, active stratovolcanoes in Costa Rica, are characterised by erratic explosive behaviour thought to be the result of the formation, maturation, and rupture of hydrothermal seals that clog the conduit. To better understand this process, we present here a systematic study in which we assessed the textural, mineralogical, and physical properties of hydrothermal seals from Turrialba, Poás, and Rincon de Vieja volcanoes, ejected as ballistics following recent explosive activity. We first document the type and intensity of the hydrothermal alteration preserved in the collected ballistics using X-ray powder diffraction and scanning electron microscopy. All samples are characterised by pervasive acid-sulphate alteration. Prior to sample preparation, the permeability of these ballistics was first estimated using a TinyPerm III, a portable handheld air permeameter. We find that the hydrothermal seal is characterised by low values of permeability, between 10−15 and 10−13 m2. Cylindrical samples were then prepared for a systematic physical property (porosity, permeability, P-wave velocity, thermal properties, and mechanical strength) characterisation in the laboratory. These laboratory data, together with fluid flow modelling, highlight how alteration can create a low-permeability hydrothermal seal that promotes cyclic, but erratic, explosive volcanic behaviour.
Improving Seismic Hazard Assessment in Southeast Spain through CyberShake: A Physics-Based Approach
Authors: Zamora Natalia , Monterrubio Marisol , Rojas Otilio , Blanco Rut , Bhihe Cedric , de la Puente Josep
Published: March 2024

The Eastern Betic Shear Zone (EBSZ) experiences slow seismic deformation that leads to relatively low seismicity rates. Due to this, historical records underscore the substantial impact that earthquakes have had on local communities. The dearth of comprehensive data on moderate to large seismic events in this area, limits the accurate generation of seismic hazard and risk maps, posing a significant challenge for seismic risk planning. A way to address these limitations is leveraging physics-based earthquake simulations in the Southeast Iberian Peninsula. These simulations first require integrating paleoseismic data, models of fault distribution –such as the Quaternary-Active Faults Database of Iberia, seismic source characterizations and historical seismic catalogs, to construct an Earthquake Rupture Forecast (ERF), where likelihood of each fault rupture is weighted by an occurrence probability. Our study focuses on developing physics-based rupture scenarios and shake maps using CyberShake. CyberShake is designed to perform physics-based probabilistic seismic hazard assessments (PB-PSHA) by simulating a vast set of synthetic ground-motion time histories from kinematic rupture scenarios on the ERF three-dimensional finite-fault array. Originally tailored for PB-PSHA studies in Southern California by the SCEC (Southern California Earthquake Center); this research represents the first CyberShake application for Southeast Spain. The resulting shake maps represent an alternative basis for updating regional probabilistic seismic hazard maps and also could support crucial decision-making processes following a local earthquake, offering valuable insights for effective response strategies.
Characterizing the Seafloor Sediment Layer Using Teleseismic Body Waves Recorded by Ocean Bottom Seismometers
Authors: Kim HyeJeong , Kawakatsu Hitoshi , Akuhara Takeshi , Takeuchi Nozomu
Published: March 2024

Kim et al. (2023; JGRse) presents an approach to better characterize the P-wave and S-wave velocity structure of the seafloor sediment layer using ocean bottom seismometers. The presence of low-velocity seafloor sediment layers influences the observed seismic record at the seafloor over a broad frequency range, such that detailed knowledge of this sediment structure is essential to predict its effect on teleseismic records. We use the radial component of teleseismic P waves and autocorrelation functions of the radial, vertical, and pressure components of teleseismic P and S waves to obtain sediment layer models using the Markov chain Monte Carlo approach with parallel tempering. Synthetic tests show that the body waves constrain the P- and S-wave impedances and travel times and the P- to S-wave velocity ratio of the sediment layers. The proposed method resolves thin layers at a high resolution, including the uppermost thin (∼50 m to a few hundred meters) low S-wave velocity layer. Real data applications at sites across the Pacific Ocean that are coincident with previous in situ studies demonstrate the effectiveness of this method in characterizing the seafloor sediment unit. Furthermore, we widely apply the methodology to data from various OBS arrays in the Pacific to estimate in-situ sediment structures. The sediment models show multiple layers in some regions, including the top water-saturated layer with low S-wave velocity and high Vp/Vs values. The scaling relationship of Vp/Vs to Vp shows higher values than the previously discussed ones (e.g., Brocher, 2005; Hamilton, 1979). Furthermore, the sediment layer model constrained from the body waves exhibits agreement in predicted Rayleigh wave admittance with the sediment model from the Rayleigh wave admittance (Bell et al., 2015). The sediment models characterized by this new approach will allow us to more accurately predict and correct the effects of sediment layers in generating P- and S-wave reverberations. Additionally, in this presentation, we will discuss how the in-situ high-Vp/Vs multi-layer sediment model differs in predicting the reverberation effects on receiver function analysis for ocean bottom seismometers.
AI Increases Global Access to Reliable Flood Forecasts
Authors: Nearing Grey , Cohen Deborah , Dube Vusumuzi , Gauch Martin , Gilon Oren , Harrigan Shaun , Hassidim Avinatan , Klotz Daniel , Kratzert Frederik , Metzger Asher , Nevo Sella , Pappenberger Florian , Prudhomme Christel , Shalev Guy , Shenzis Shlomo , Tekalign Tadele , Weitzner Dana , Matias Yossi
Published: March 2024

Floods are one of the most common  natural disasters, with a disproportionate impact in developing countries that often lack dense streamflow gauge networks. Accurate and timely warnings are critical for mitigating flood risks, but hydrological simulation models typically must be calibrated to long data records in each watershed. Here we show that AI-based forecasting achieves reliability in predicting extreme riverine events in ungauged watersheds at up to a 5-day lead time that is similar to or better than the reliability of nowcasts (0-day lead time) from a current state of the art global modeling system (the Copernicus Emergency Management Service Global Flood Awareness System). Additionally, we achieve accuracies over 5-year return period events that are similar to or better than current accuracies over 1-year return period events. This means that AI can provide flood warnings earlier and over larger and more impactful events in ungauged basins. The model developed in this paper was incorporated into an operational early warning system that produces publicly available (free and open) forecasts in real time in over 80 countries. This work highlights a need for increasing the availability of hydrological data to continue to improve global access to reliable flood warnings.Nearing, Grey, et al. "AI Increases Global Access to Reliable Flood Forecasts." arXiv preprint arXiv:2307.16104 (2023).