bluuebunny/crossref_metadata_2025 huggingface dataset:
Flood induced channel morphodynamics variability of a braided river system in the lower Brahmaputra river basin, India
Authors: Devrani Rahul , Srivastava Pradeep , Kumar Rohit , Kasana Parv
Published: March 2022

The high and low flood events in a braided river system cause perpetual changes in the channel morphodynamics and make it difficult to understand a channel response.  Therefore, the management of braided channel morphodynamics becomes a challenging issue for flood mitigations and river restoration purposes. The lower Brahmaputra river basin has the world’s most extensive braided river system, and every year it confronts reoccurring monsoon driven flooding causing widespread flood inundation and changes in channel morphodynamics. Such adequate conditions promise a natural laboratory to understand dynamics channel morphodynamics changes with high and low flood events. The present work integrates the mutual effects of varying channel area, width and sinuosity, and sediment bar area along a braided channel reach in the selected reach in the Brahmaputra River in thirty events during high discharge months of 2018, 2019 and 2020. To observe detailed channel morphodynamics changes, we developed 100 grids with a width of ~6.25 km enclosing the selected reach. These grids are maintained stationary for each year and were used to extract the Brahmaputra River channel area (BRCA)  and Brahmaputra River sediment bar area (BRSBA) and average Brahmaputra River channel width (BRCW) for each grid. We developed a site-specific Google Earth Engine algorithm to delineate the channel and sediment bar in the selected reach to perform supervised classification on Sentinel-1 SAR GRD and Sentinel-2 level-1C.

The results show that grids upstream of the selected reach have a high BRCA, BRSBA and BRCW, and these grids are located around high clustered flood inundated hotspot regions.  We also found that the world's largest river island  (Majuli) is also located in this zone. In the present study, we also observe that if we consider BRCA, BRCW and BRSBA for the same event, the BRSBA has a high correlation with the BRCW compared to the BRCA. Further, we compared the impact of the sinuosity on BRCA, BRCW and BRSBA of regular and influential flood events. During influential events, the sinuosity has only a good impact on the BRCA, and during regular events, it has a higher impact on BRCA and BRSBA. We conclude that in the braided river system of the Brahmaputra River, the channel and bar area and channel width are highly correlated during flood events, and the channel sinuosity also controls channel and bar area and channel width during regular and influential flood events.
Magnetospheric ULF wave dependence on Interplanetary Coronal Mass Ejections and Stream Interaction Regions
Authors: Thanasoula Konstantina , Katsavrias Christos , Nasi Afroditi , Daglis Ioannis A. , Balasis Georgios , Sarris Theodore
Published: March 2022

Radial diffusion driven by Ultra Low Frequency (ULF) waves is very important for magnetospheric dynamics, because it contributes to relativistic electron enhancements and losses in the outer Van Allen radiation belt. Previous studies have investigated the dependence of ULF wave power spectral density and radial diffusion coefficients (DLL) on solar wind parameters. However, a conclusive correlation between the type of interplanetary drivers (such as Interplanetary Coronal Mass Ejections (ICMEs) and Stream Interaction Regions (SIRs)), ULF wave power spectral density and radial diffusion coefficients DLL is still an open topic. In this study, we use the "SafeSpace" database (https://synergasia.uoa.gr/modules/document/?course=PHYS120), which includes radial diffusion coefficients DLL and ULF wave power spectral density. This database was created using magnetic and electric field measurements by the THEMIS satellites for a 9-year period (2011- 2019). We conduct a statistical analysis of radial diffusion coefficients DLL, which contributes to relativistic electron radial diffusion quantification, and ULF wave power spectral density, to find out their dependence on ICMEs (25 events) and SIRs (46 events). In addition, we study how the parameters of these solar wind drivers influence the growth of ULF waves and  the behavior of radial diffusion coefficients.
GEB: Integrating farm-level human decision making in large-scale gridded hydrological models
Authors: de Bruijn Jens , Smilovic Mikhail , Burek Peter , Guillaumot Luca , Wens Marthe , van Loon Anne , Haer Toon , Wada Yoshihide , Aerts Jeroen
Published: March 2022

Humans play a key role in the hydrological system, for example by extracting large amounts of water for irrigation, often resulting in water stress. By implementing large-scale adaptation measures, such as the construction of irrigation reservoirs, water stress can be reduced. Yet we know that many decisions, such as adoption of more effective irrigation techniques or changing crop types, are made at the farm level by a heterogeneous farmer population. While these decisions are often advantageous for an individual farmer or their community, effects of these measures are frequently experienced downstream. Therefore, to fully comprehend how the human-natural water system evolves over time and space, and to explore which interventions are suitable to reduce water stress, it is important to consider human behaviour and feedbacks to the hydrological system simultaneously at the local household- and large basin scales.

Therefore, we present GEB (Geographical, Environmental and Behavioural model), a coupled agent-based hydrological model that can simulate the behaviour and daily bi-directional interaction of more than 10 million individual farm households and reservoir operators with the hydrological system on a personal laptop. Through this coupling, each individual farmer can decide to irrigate from various sources (i.e., surface-, reservoir-, or groundwater). Furthermore, farmers can decide to plant and harvest crops based on the available water in their environment, the status of their crops, their risk aversion, crop price, water price, and weather conditions etc. Moreover, farmers can adapt, for example by investing in water saving techniques, drilling boreholes, and changing crop type. Reservoir operators can regulate the availability of water for irrigation, and downstream releases of water. All these decisions can be made at a daily timestep.

GEB is dynamically linked with the spatially distributed hydrological model CWatM at 30’’ grid resolution (< 1km at the equator). Because many small-holder crop fields are much smaller, CWatM was specifically adapted to implement dynamically sized land management units at the sub-grid level, providing each agent with an independently operated hydrological response unit (HRU). While the model could be applied anywhere, we show an implementation in the heavily managed Krishna basin in India, encompassing ~8% of India’s land area and ~11.1 million farmers. Here, we show how six combinations of scenarios with endogenous and exogenous drivers of adaptation affect both the hydrological system and farmer population.
Spatial heterogeneity of monsoon precipitation over the Asian continent during the termination of MIS-9 
Authors: Subba Rachana , Ghosh Prosenjit , Thirumalai Kaustubh , Partin Judson , Yadava Madhusudhan G , Shen Chuan Chou , Clemens Steven C , Lone Mahjoor Ahmad , Yu Tsai Luen , Allu Narayana Chinna , Ramesh Rengaswamy
Published: March 2022

Understanding the spatial and temporal variability of rainfall which is regulated by the strength of Asian monsoon requires an observational network dispersed across the continental landmass. The operation of monsoonal circulation during the last one million years is possible to be reconstructed using the geochemical and isotopic record available from cave speleothems. The monsoonal circulation brings rain and excess precipitation due to interplay of monsoonal wind strength which is governed by the seasonal movement of Intertropical Convergence Zone (ITCZ) from ocean to the continent. A consensual view is that both the operation of East Asian Summer Monsoon (EASM) and Indian Summer Monsoon (ISM) are in accordance with the orbital forcing. However, the lack of terrestrial records of ISM rainfall variability over glacial interglacial time scales precludes insights into pan-Asian monsoon forcing and related mechanisms. Here, we present independent estimates of temperature change from the clumped isotope record in speleothem from Belum cave, continental India, covering glacial interglacial transition (MIS-9). The palaeo data is used in conjugation with the already reported δ¹⁸O records from Chinese caves and Mean Annual Precipitation from Chinese Loess Plateau (CLP), which are influenced by the EASM, to understand the spatial variability of δ¹⁸O records and its significance in regulation of moisture transport process away from equator. A comparative study across latitudes, particularly at the peak of the interglacial period MIS 9 (after ~320 ka) brings to light the intensification of rainfall accompanied by relatively higher temperature (~35°C in Belum cave- 15.10°N) exhibited by both the ISM system and EASM System (Xiao cave 26.04°N). However, shift in δ¹⁸O record of caves above 30° N (Sanbao and Linzhu caves) is less, though the trend is similar. A recent study of CLP (36.35°N) reported a drop in mean precipitation by ~300mm post 320 ka. Such variation of the mid-latitude precipitation intensity may probably be a consequence of the combined effect of ice volume and snow cover in the Northern hemisphere and low latitude climate changes.
Hydrological and hydrochemical haracteristics of the modified AABW in the Discovery Gap (Northeast Atlantic) in 2021.
Authors: Dvoeglazova Nadezhda , Kapustina Maria , Krechik Victor , Bocherikova Irina
Published: March 2022

Hydrological and hydrochemical characteristics of the Discovery Gap bottom water (deeper than 4000 m) were obtained during the 59th cruise of the R/V Akademik Ioffe (October 2021). Discovery Gap is the narrow gap of 150 km long, 10–50 km wide, oriented from southwest to northeast in Azores–Gibraltar Fracture Zone (Northeast Atlantic). Water with a potential temperature of less than 2 °C (modified Antarctic Bottom Water (AABW)) and high silicon concentrations was detected in the Discovery Gap. The terminal point of propagation of modified AABW in the exit sill of the Gap (depth more than 4700 m). There was cyclonic circulation in the Discovery Gap Narrows (the narrowest point of the Discovery Gap, 10 km wide, located in the northeastern part of it): in the northeast direction of more than 14 cm/s speed and with the high phosphate concentrations (1.46-1.54 μmol/l), in the southwest direction of 6-8 cm/s speed and with a low phosphate content (1.39-1.40 μmol/l). The localization of the extrema of phosphorus concentrations correlates with the maximum flow velocities, which may be associated with advective processes.

Acknowledgments:

The expedition and the hydrochemical processing of the data received during the 59th cruise of the R/V Akademik Ioffe was carried out with a support of the state assignment of the IO RAS (No. 0128-2021-0012), the hydrophysical measurements were supported by the Russian Science Foundation (project no. 21-77-20004).

We thank the crew of the R/V Akademik Ioffe for assistance, B.V. Chubarenko for valuable comments and E.I. Gmyrya for preparing the map.
Fossil charcoals as a means for reconstruction of past hydroclimate variability through the Last Glacial Maximum: a case study from two archaeological sites in the Winter and Year-round Rainfall Zones, South Africa
Authors: Khumalo Wendy , Hare Vincent , Kirsten Kelly , Parkington John , Pickering Robyn
Published: March 2022

The hydrology of the Last Glacial Maximum (LGM) in South Africa has been an active area of research over the last six decades due to the richness of many proxy records and the high preservation potential of deposits of this age at sites recording human occupation. Here we review the merits of using a Weighted Average – Partial Least Squares regression on the archaeological charcoal records from Elands Bay Cave (EBC) and Boomplaas Cave (BPC) to quantitatively reconstruct palaeoclimate. These sites are both spatially and temporally ideal to track the changes in the Southern Hemisphere Westerlies – the proposed driver of the change in hydroclimate and have been used to infer LGM climate conditions. A database of the modern-day distribution of the taxa identified in the stratigraphy at EBC and BPC was created using the Global Biodiversity Information Facility, this was then paired with the modern climate data from WorldClim to perform a WA-PLS regression to reconstruct Mean Annual Temperature and Total Annual Precipitation. Many of the WA-PLS regressions reconstructed temperature differences from the LGM to present close to 5°C (consistent with regional records). The TAP reconstructions suggest decreased precipitation during the LGM at BPC and despite unrealistic values for the EBC charcoal record, they suggest higher TAP values during the LGM. The TAP reconstructions posed more problems and highlighted some major flaws in the reconstructions. When compared to the pollen record from EBC, MAT  reconstructions reflect the same trend however the TAP reconstructions from pollen indicate slightly lower TAP values during the LGM. Due to the nature of these records, there are some important differences that influence the outcomes of the reconstruction. These being the biases which exist within the records themselves and propagating through to the reference databases. With the use of a Canonical Correspondence Analysis, we can compare the modern distribution of the taxa and better understand what the reconstructions are reflecting and in some cases failing to reflect. While a WA-PLS regression is widely used for reconstructions, other regressions should be compared alongside it.
Studying the Earth’s heat budget with geoneutrinos
Authors: Strati Virginia , Bellini Gianpaolo , Inoue Kunio , Mantovani Fabio , Serafini Andrea , Watanabe Hiroko
Published: March 2022

The Earth is cooling down and its surface heat flux is the highest among all the terrestrial planet of the Solar System. The total heat loss (Q) is due to the energy released by the secular cooling of our planet (C) and of the radiogenic heat (H) produced by the radioactive decays of the radioelements contained therein. Can geoneutrino disentangle these two contributions?

Since while decaying, the uranium, thorium and potassium radioisotopes contained in the Earth release geoneutrinos in a well-fixed ratio, we can attempt to answer affirmatively to this question. Indeed, geoneutrinos are able to pass through most matter without interacting, so they can bring to surface useful information about the Earth’ deep interior. Concretely, measuring the geoneutrino flux at surface hence translates in estimating H and in turn constraining C once that Q is known.

The only two experiments which collected data in the last 15 years are KamLAND (Japan) and Borexino (Italy). By combining theoretical models and experimental flux with a sophisticated analysis, we inferred valuable insights on mantle radioactivity and of contribution of H to the Earth’s energy budget. We estimated a total radiogenic heat accounting for H = 20.8+7.3-7.9 TW and, by subtracting this value from the total heat power of the Earth, we derived a secular cooling C = 26 ± 8 TW. The obtained results are discussed and framed in the puzzle of the diverse classes of formulated Bulk Silicate Earth models, analyzing their implications on planetary heat budget and composition.

The effectiveness in investigating deep earth radioactivity demonstrated by geoneutrino studies confer them a prestigious role in the comprehension of geodynamical processes of our planet.
Physicochemical properties of a marine lake in the central Adriatic (Lake Rogoznica): interaction with the atmosphere, the sea and the surrounding karst
Authors: Dominović Iva , Marguš Marija , Geček Sunčana , Bakran-Petricioli Tatjana , Petricioli Donat , Dutour Sikirić Mathieu , Ciglenečki Irena
Published: March 2022

Lake Rogoznica (also known as "Dragon's Eye") is a karstic, marine lake on the Gradina peninsula located at the Adriatic coast at 43° 32' N and 15° 58' E. Most of the time the lake is stratified, with an upper oxic layer, an anoxic bottom layer, and a chemocline in between. Every few years the stratification suddenly breaks down and the entire water column becomes mixed, anoxic, and euxinic, with HS- presence throughout the water column. This leads to mass mortality of aerobic populations in the lake, which require long periods of time without mixing to recover. Rogoznica residents confirmed that the sudden overturning of layers had been occurring even before continuous research began in 1992, but also that it used to happen less frequently. In the last 30 years, five such events of complete anoxia have been recorded: in September 1997, October 2011, October 2016, October 2020, and October 2021. As the sudden mixing now occurs year after year, the lake's ecosystem does not have nearly enough time to recover. Previous work has indicated that the main trigger for the abrupt mixing is a sudden drop in surface temperature caused by an overpassing low-pressure system. Nevertheless, the process of overturning and sudden release of bottom-layer sulfides is a very delicate one, and determining other biological, physical, and chemical triggers is an important question that remains to be answered. Another key question is whether the increase in the overturn frequency is solely a part of the natural life cycle of the lake, a result of the changing climate with more extreme weather events, or a more direct consequence of human activities in the area.

Comparison of the most recent water level measurements from June 2021 with those from 2013 indicate that the tidal signal in the lake requires a somewhat different analytical approach than the standard ocean tidal analysis procedure. Moreover, measurements at the boundaries of the lake show that the water entering the lake from the karst at high tide is not only colder but also has a lower salinity. Additionally, in this work we present new insights into the physicochemical properties of the lake's water column (σT-stratification, dissolved oxygen concentration) and the direct influence of atmospheric wet deposition on the lake's surface layer.
Terrestrial Gamma-ray Flashes produced by complex thunderstorm electric structures
Authors: Stadnichuk Egor
Published: March 2022

One of the possible sources of Terrestrial Gamma-ray Flashes (TGF) is Relativistic Runaway Electron Avalanches (RREA) accelerated in large-scale thunderstorm electric fields. In order to produce short and bright gamma-ray flash, a huge number of RREAs must exist simultaneously. This can be obtained through positive feedback mechanisms in RREA dynamics. At quasi-uniform thunderstorm electric fields, relativistic feedback provides RREAs multiplication via positrons and reversed gamma-rays. A significant disadvantage of relativistic feedback is that it requires high electric field strength in order to produce a TGF.

In complex thunderstorm electric structures, an additional feedback mechanism appears, the reactor feedback. Reactor feedback emerges if a thunderstorm consists of several RREA-producing regions, cells. A RREA developed in a cell radiates bremsstrahlung gamma-rays. Gamma-rays have high penetrative power and propagate through semi-critical electric field regions, where runaway electrons can stop, reaching other cells. There gamma-rays interact with air molecules, producing RREAs. Therefore, cells amplify each other by the gamma-ray exchange. The amplification rate can be strong enough to make RREAs self-sustainable, that is infinite reactor feedback. Infinite reactor feedback requires lower electric field strength compared to infinite relativistic feedback. Moreover, such RREA multiplication can cause a TGF.

In this report, a theoretical technique is developed to describe relativistic runaway electron avalanches dynamics in complex electric structures. Cells' interaction via high-energy particles exchange can be described with the Feedback Matrix, which is a matrix consisting of feedback operators. A feedback matrix action on RREA starting point distribution in i-th feedback generation creates RREAs starting point distribution in the next (i+1)-th generation. Matrix elements depend on thunderstorm electric field parameters and include RREA development physics and gamma-ray propagation physics. Diagonal matrix elements describe the self-action of cells, which is the relativistic feedback. The proposed approach includes all the feedback mechanisms and reduces the problem of avalanche dynamics to finding eigenvalues and eigenfunctions of the feedback matrix, as the eigenvalues are feedback coefficients.

With the feedback matrix solutions for RREA dynamics in different electric field geometries are obtained. Thunderstorm conditions required for TGF development are found. It is shown that the more complex the electric structure is the lower the electric field strength is required to produce a TGF.
Psychology in high demanding environments
Authors: Reymen Brent , Avila-Rauch Celia
Published: March 2022

Our research aims to demonstrate that Emotional Intelligence Skills (EIS) could be a tool to support the cognitive processes that will be influenced by the complexity of tasks required during long duration space travel. Emotions, apart from being functional states of the whole organism, involve both physiological (organic) and psychological (mental) processes, therefore the management of EIS plays an important role in the regulation and self-control of a person, as well as their self-knowledge. This, in turn, contributes to professional and personal success. Very few research on this topic has been done with people working in the space sector which could be interesting since we are talking about professions that require high performance under special conditions with high levels of stress and moral responsibility. This research uses a series of questionnaires given to analog astronauts in the Analog Astronaut Training Center in Poland and groups of people brought together by the EuroMoonMars group who conducted scientific work in extreme environments. The questionnaires included in this research are: Emotional Meta-awareness Scale (TMMS-24); Group Environment Scale (GES-E & GES-R); HEXACO personality inventory; Cognitive and Affective Empathy Scale (TECA); Depression, Anxiety, Stress Scale (DASS); and the SCL-90-S, a psychopathology indicator. These questionnaires will provide comparative and orientation data from which we can examine if there is a possible emergence of an ideal personality style which leads to high EIS, how emotional processes can influence cognitive functions, and whether training in emotional intelligence can affect long-term cognitive processes in these kind of environments. This would be imperative for future astronauts in order to maintain their attention, their vigilance, and reduce the effects of fatigue and stress while in space.
Fires and forests: A reconstruction of Holocene fire-vegetation relationships in Central Yakutia, Siberia
Authors: Glückler Ramesh , Geng Rongwei , Grimm Lennart , Baisheva Izabella , Herzschuh Ulrike , Kruse Stefan , Andreev Andrei , Böhmer Thomas , Vyse Stuart , Pestryakova Luidmila , Dietze Elisabeth
Published: March 2022

The year 2021 set new records for wildfire extent in the Republic of Sakha (Yakutia) in eastern Siberia, Russia. Wildfire seasons in this unique region, characterized by its deciduous boreal forest and permafrost landforms, are becoming more intense. Some fires are threatening local communities, while their smoke covers vast stretches of land every summer, posing health risks to people even in the distance. At the same time, the larch trees of the eastern Siberian boreal forest stabilize the permafrost soils below as guardians of a continental-scale storage of terrestrial carbon. It is still largely unknown how the current trend of wildfire intensification will develop in the future, and how it will modify the structure of the boreal forests within the next decades to centuries. However, even though needed for a well-founded evaluation of long-term impacts of changing fire regimes, data on past trends of wildfire activity still remains scarce in eastern Siberia.

Here, we present a new reconstruction of boreal fire and vegetation dynamics, spanning the last ca. 10.8 ka. Continuously analyzed macroscopic charcoal particles and a REVEALS-transformed pollen record from a sediment core from Lake Satagay (N 63.078, E 117.998) give insight into long-term trends and relationships between changes in fire regime and vegetation composition and coverage. The data indicates that modern larch-dominated forests co-exist with a lower severity fire regime, whereas early Holocene open larch-birch woodlands enabled increased charcoal accumulation and thus supported a higher severity fire regime. Considering the expected increase in tree mortality caused by wildfires and insect damage, likely to thin out currently denser tree stands, this fire-vegetation relationship suggests a potential upcoming positive feedback on intensifying fire regimes.
Analogues of a historical extreme-impact event and their implication for climate change risk assessment
Authors: Moreno Dumont Goulart Henrique , van der Wiel Karin , Folberth Christian , Balkovic Juraj , van den Hurk Bart
Published: March 2022

Meteorological conditions can affect crop development and yield in multiple and non-linear ways. Many studies have investigated the influence of climate change on crops by simulating crop responses to the most likely mean climatic projections in the future. However, this approach can potentially overlook changes in extreme-impact events, highly relevant for society, due to their low probability of occurrence and to potential different behaviour with respect to the mean conditions. One way of focusing on extreme-impact events is through the use of physical climate storylines. Storylines enable the construction of self-sustained and physically-plausible chain of events that recreate historical events from source to impact. In addition, storylines allow the exploration of future analogues of the historical events under different circumstances to account for externalities, such as climate change. In this experiment, we use physical climate storylines to reconstruct a historical extreme-impact event and to explore potential analogues of the same event under climate change influence. We develop two types of analogues, event-analogues and impact-analogues, and compare how the future manifestation of the historical event depends on the analogue definition. We use soybean production in the US as an example, with the year of 2012 being the historical extreme event. Based on a random forest model, we link the historical event to meteorological variables to identify the conditions associated with the failure event. To quantify the frequency of occurrence of the different analogues under climate change, we apply the trained random forest model to large ensembles of climate projections from the EC-Earth global climate model. We find that the 2012 failure event is linked to low precipitation levels, and high temperature and diurnal temperature range (DTR) levels during July and August. The analogues of the historical event greatly diverge: while event-analogues of the 2012 season are rare and not expected to increase, impact-analogues show a significant increase in occurrence frequency under global warming, but for different combinations of the meteorological drivers than experienced in 2012. The results highlight the importance of considering the impact perspective when investigating future extreme crop yields.
Dissolved oxygen budget in the eastern Mediterranean over the period of 2012 - 2020 using a 3D physical-biogeochemical model
Authors: Habib Joelle , Ulses Caroline , Estournel Claude , Marsaleix Patrick , Coppola Lauren , Fakhri Milad
Published: March 2022

The Levantine basin is the area of formation of the Levantine Intermediate Water. In this study, a 3D hydrodynamic-biogeochemical model (Symphonie/Eco3MS) was used to gain understanding in the dynamics of dissolved oxygen in the Levantine basin and estimate its annual budget and its interannual variability over the period of 2012-2020. Comparisons of model results with compiled in situ data from cruises and Argo floats showed that the model was able to reproduce well the seasonal variability of the dissolved oxygen. They also show that during winter, surface temperature decreased, generating  oxygen  undersaturation in the Levantine basin that absorbed atmospheric oxygen. From March to September, due to the increase of surface temperature the basin became oversaturated and released oxygen into the atmosphere. The estimate of the annual oxygen budget revealed that the Levantine basin acted as a sink of atmospheric oxygen. Gain of oxygen in the upper layer through air-sea exchanges and biogeochemical processes were counterbalanced by the loss of oxygen through physical processes via downward export into  intermediate depths and lateral transport towards the western regions. At the annual scale, the air-sea oxygen exchange term dominated the biogeochemical process term in the budget. Regarding the spatial distribution, maximum annual atmospheric oxygen uptake and biogeochemical fluxes were found in the Levantine Intermediate Water formation area of the Rhodes gyre where oxygen-poor and nutrient-rich waters were supplied in the upper layer and surface temperature was minimum. The current study revealed high interannual variability with large oxygen uptakes and physical exports during winters marked by intense heat losses.
The tip of the iceberg: U-Pb dating shows that cave systems can be twice as old as their surface expression
Authors: Weij Rieneke , Woodhead Jon , Sniderman Kale , Hellstrom John , Reed Elizabeth , Bourne Steven , Drysdale Russell
Published: March 2022

Caves are important fossil repositories providing records extending back over million-year timescales. While the physical processes of cave formation are well understood, a more important parameter to studies of palaeontology, palaeoanthropology and archaeology — that of the timing of initial cave development and opening — has proved more difficult to constrain. The Naracoorte Cave Complex (NCC) in southern Australia is a World Heritage site with a rich record of Pleistocene vertebrate fossils, including extinct megafauna, and serves as a natural laboratory in which to investigate these fundamental cave processes. Using U-Th-Pb dating of speleothems we show that the NCC is at least 1.32 million years old, extending the current understanding of initial speleothem formation by ~70% and the antiquity of initial cave development at this site by at least ~20%. We use charcoal and pollen trapped in the same speleothems to place robust constraints on the timing and extent of subsequent cave opening. The findings of this study provide an important means for researchers working on the plethora of fossil-rich sites worldwide to assess the potential upper limit of vertebrate fossil records within caves.
Quantifying the rate of erosion of simple terrestrial meteorite impact craters
Authors: R. Chandran Saranya , James Shania , Padmakumar Devika , M. Nair Varsha , Kochappi Sathyan Sajinkumar
Published: March 2022

The surface of the earth is continuously modified by the action of various active geological agents, and one of the resultant is erosion. Climate, lithology, slope, precipitation, temperature, vegetation and anthropogenic activities are the chief controlling factors of erosional processes. The rate of erosion associated with various geomorphological features has been estimated using several different methods. Meteorite impact craters being a positive relief feature, formed by an impetuous process, thus, is an ideal candidate for quantifying the rate of erosion. Several authors have attempted to quantify the erosion rate with the availability of scanty number of terrestrial impact craters. In this study, apart from taking into account other factors, paleoclimatic parameters have been incorporated to estimate the erosion rate of simple impact craters. The rate of erosion has been quantified in selected terrestrial simple impact craters considering the influence of various climatic zones traversed by the crater in relation to its topographical parameters and the geological province where the crater is located. The temporal range of each crater in distinct paleoclimatic zoneshave been derived to better constrain the influence of climate on erosion. The rate of erosion of the region hosting the impact craters and the individual crater are estimated separately using different methods. In the first method, the relief of the geological province where the crater is located is considered and in the second method, the initial relief of the transient impact crater is calculated using a set of crater morphological parameters. The estimated values of erosion rates of craters are correlated with the published works. The values are found to be similar except for the older craters, which we believe due to the large uncertainties associated with paleoclimatic data. Difference in the erosion rates of older craters can also be attributed to dynamic evolutionary trends of terrestrial simple impact craters pertaining to the influence of various regional elements in the vicinity of the crater including the drainage, tectonic activities, precipitation, temperature and lithology.
Automatized drought impact detection from newspaper articles using natural language processing and machine learning
Authors: Sodoge Jan , de Brito Mariana Madruga , Kuhlicke Christian
Published: March 2022

Droughts are expected to increase both in terms of frequency and magnitude across Europe. While they impose diverse impacts on social-ecological systems, most impact assessments focus on particular sectors or economic aspects. Existing multi-sectoral datasets are limited in spatio-temporal homogeneity and scope due to the manual extraction of impacts from text-based sources. To address this, we developed a novel method for the automatized detection of drought impacts based on newspaper articles. By employing natural language processing and machine learning models, our method is able to extract different classes of drought impacts (e.g. agriculture, forestry, livestock) and their geographic and temporal scope from text data. We applied this method to generate a multi-sectoral dataset of drought impacts in Germany between 2000 and 2021. About 41121 articles from different journals were considered. Accuracy levels of 92-96% per impact class were obtained for the automatic classification of the impacts when evaluated on a human-annotated dataset. For validation against independent data, first results show that our method can replicate both temporal and spatial trends. Our approach advances existing techniques because it (1) requires a significantly lower workload, (2) allows addressing large amounts of data, (2) reduces subjectivity and human bias, and (4) is generalizable to other hazard types as well as text corpora while achieving sufficient levels of accuracy. The findings highlight the applicability of natural language processing and machine learning to create comprehensive impact datasets. Furthermore, the generated information can be used for validating drought risk assessments and impact models.
Oil in glacial till as drivers of ice streaming and surging
Authors: McCerery Rebecca , Woodward John , McHale Glen , Winter Kate , Esegbue Onoriode , Jones Martin
Published: March 2022

The driving mechanisms of glacier fast flow and the cyclical instability inherent in ice streams and surging glaciers are not fully understood, with current theories of sliding and basal deformation being insufficient in explaining glacier dynamics. Previous work on soil water repellency and interfacial physics shows that the incorporation of a lubricating oil into a sediment enhances the water repellent and water shedding properties. This can form a Slippery Liquid-Infused Porous Surface (SLIPS), whereby a liquid-liquid interface is created when the sediment is exposed to water resulting in extreme water shedding.

In Alberta, Canada, oil sands material has been detected in surficial sediment and in glacial sediments south of the Alberta Oil Sands deposits. It has been hypothesised that this material was eroded and transported subglacially during the Laurentide Glaciation. Here, sediments from the Central Alberta Ice Stream flow track in the former Laurentide Ice Sheet were analysed and compared to samples of the Alberta Oil Sands from mines and natural exposures using oil-oil correlation by gas chromatography-mass spectrometry. The results show evidence of Alberta Oil Sands throughout the Central Alberta Ice Stream flow track, in particular at the terminating margins to the east of Calgary and in the Cooking Lake area to the southeast of Edmonton. These results indicate glacial erosion and long-distance mobilisation of oil sands deposits from Northern Alberta. Three scenarios of SLIPS at the ice-bed interface caused by the presence of a lubricating oil at the bed can be assumed from these results; (i) an oil-wet macroscale SLIPS, (ii) a water-wet macroscale SLIPS, and (iii) a microscale SLIPS.  These SLIPS mechanisms would influence the degree of ice-bed coupling and therefore the proportion and rates of sliding and basal deformation. By understanding the physics occurring at the ice-bed interface it is possible to better predict glacier flow conditions. It is therefore critical that properties affecting wettability and water shedding of sediments such as the presence of an oil are considered in our understanding of transient flow conditions.
Sinistral Strike Slip Faults of the Kyrgyz Tien Shan
Authors: Pierce Ian , Abdrakhmatov Kanatbek , Baikulov Sultan , Rakhmedinov Erkin , Tilek Kyzy Gulkaiyr , Johnson Ben , Seitz Gordon , Arrowsmith Ramon , Rizza Magali , Walker Richard
Published: March 2022

The Tien Shan are an intracontinental mountain belt experiencing shortening as a result of far field deformation from the ongoing India-Eurasian collision. At the longitude of Kyrgyzstan the Tien Shan accommodate ~20 mm/yr of shortening. In central Kyrgyzstan, the most well studied faults include the northwest-striking right-lateral Talas Fergana fault and the series of east-striking reverse & thrust faults that form the basins and subranges that accommodate most of this compression. Yet in satellite imagery, some of the most prominent fault ruptures appear on a series of east-northeast-striking left-lateral strike slip faults. Little is known about the paleoseismology, rate of slip, or tectonic role of these faults. Here we present new drone-based high resolution topography and imagery along with geomorphic, geochronology, paleoseismic, and slip rate data for four of these sinistral faults. The studied faults are in the Aksay, Kazarman, Issyk Kul, and Song Kol basins. These data reveal that each fault has produced Holocene surface ruptures with single event displacements as great as 5-7 m along faults as long as ~100 km, corresponding to M~7.5 earthquakes. We propose a structural model to explain how these faults may have evolved from reverse faults that have rotated about their horizontal axis and then reactivated as strike slip faults due to their optimal alignment in the current stress field. How the existence of these faults affects seismic hazards is a question of discussion, as they are currently not considered in the regional strain budget that is largely based on compression.
Accuracy of remote sensing techniques in beach geomorphological surveys: a case study of Hvar island, Croatia
Authors: Mićunović Marin , Faivre Sanja , Gašparović Mateo
Published: March 2022

Beaches, as a shore accumulation of loose, unconsolidated sediment, are under constant change. Natural processes intertwined with increasing anthropogenic pressure cause changes in their morphology. Monitoring of beaches can provide quality data and information, which could be used for coastal management as beaches are an important resource in Hvar island touristic offer. Nowadays, there are many easily available remote sensing sources (satellite and aerial imagery) suitable for beach surveys. In this work, the accuracy and quality of remote sensing data, based on three different sources have been assessed, covering a 10-year period. The area and length were measured and compared on 20 different gravel pocket beaches on the island of Hvar.

Fundamental beach morphology measurements were done using historical satellite imagery from the Google Earth Pro desktop application, from which 5 different years (2013,2016,2018,2019 and 2020) have been selected, based on their spatial and temporal resolution quality. Furthermore, orthophotos provided by Croatian State Geodetic Administration – Geoportal, including four different orthophoto generations (2011,2014,2017 and 2019), were used. The recent period was collected with UAV – DJI Phantom 4 Pro v2.0. and Trimble GNSS GeoXH (<0,1 m). The fieldwork took place in November 2020 and May 2021. Collected images were processed in Drone2Map software, which is based on structure from motion algorithm (SfM). Photogrammetric data processing resulted in high-resolution models (DEM, DSM and orthophoto). Measurements were done using a digital measurement tool and by connecting WMS to ESRI ArcGIS Pro software.

The accuracy of measured values was calculated using Root Mean Square Error (RMSE) and percentage error. As UAV have much better spatial resolution than satellite or aerial imagery, it was chosen for a reference value. A measured beach area and length values from all sources revealed strong correlation (r2=>0,98). An average RMSE for beach area was 7,2% and length 2,5%, while deviation was calculated -2,3% to 5,6% for beach area, and -1% to 2,7% for beach length. Thus, linear feature measurement (e.g., shoreline) is more accurate than the polygon-based (e.g., beach area). Considering the 10-year period, as expected, recent imagery proved to have more accurate data than those from the beginning of the past decade. However, this work showed that different remote sensing sources (including the older ones) could be used in relatively accurate geomorphological beach investigations taking into account the errors. Defining the quality and errors of initial data sources represent a good base for further monitoring and analyses of beach morphological changes and vulnerability assessment, but also for coastal management in the future.

This research was made with the support of the Croatian Science Foundation (HRZZ-IP-2019-04-9445).
Coordinated observations of relativistic electron enhancements following the arrival of consecutive Corotating Interaction Regions
Authors: Nasi Afroditi , Daglis Ioannis A. , Katsavrias Christos , Sandberg Ingmar , Li Wen , Allison Hayley , Miyoshi Yoshizumi , Imajo Shun , Mitani Takefumi , Hori Tomo , Shprits Yuri , Kasahara Satoshi , Yokota Shoichiro , Keika Kunihiro , Shinohara Iku , Matsuoka Ayako , Kasahara Yoshiya
Published: March 2022

During July-October of 2019, a sequence of Corotating Interaction Regions (VSW ≥ 600 km/s) impacted the magnetosphere, for four consecutive solar rotations. Even though the series of CIRs resulted in relatively weak geomagnetic storms (SYM-Hmin ≈ -60 nT, Kpmax ≈ 5), the net effect of the outer radiation belt during each disturbance was different, depending on the electron energy. During the August-September CIR, intense substorm activity was recorded (SMLmin ≈ - 2000 nT), as well as significant enhancement of ultra-relativistic electrons.

We exploit coordinated and cross-calibrated particle measurements from the Van Allen Probes, Arase and Galileo 207, 215 satellites, to investigate the relative contribution of radial diffusion and gyro-resonant acceleration, using both electron fluxes and Phase Space Density (PSD) radial profiles, also compared with a 1D Fokker-Planck simulation.

Additionally, we use chorus wave amplitude and radial diffusion coefficient (DLL) estimations, from the SafeSpace DLL database, density measurements from the GFZ-Potsdam database, as well as solar wind and geomagnetic parameters, for a detailed investigation of these events.

This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace project.
Evaluation of the MERRA-2 PM2.5 mass and its constituent chemical species concentrations over a COALESCE network site in Bhopal, India 
Authors: Devaliya Sandeep , Maheshwarkar Prem , Bhardwaj Ankur , Haswani Diksha , Shukla Deeksha , Sunder Raman Ramya
Published: March 2022

Modern-Era Retrospective analysis for Research and Applications (MERRA-2) generated  PM2.5  concentrations are widely used to understand the spatio-temporal variability of PM2.5 across the globe. Only PM2.5 data from black carbon, organic carbon, sulphate, sea-salt, and dust are provided by MERRA-2. However, previous studies validated MERRA-2 PM2.5 concentrations obtained by combining all five species data against in-situ ​total PM2.5 concentrations. To the best of our knowledge, this is the first study over India to validate MERRA-2 species wise PM2.5 concentrations utilizing in-situ surface measurements made over a site at Bhopal (23.285° N, 22.277° E). Bhopal is one of the eleven COALESCE (Carbonaceous Aerosol Emissions, Source Apportionment and Climate Impacts) network regionally representative sites in India. 24 hour integrated filter-based samples (N = 165) collected during 2019, using the MetOne SASS® speciation sampler were used to measure mass and aerosol species concentrations by a variety of analyses. Our results show that the MERRA-2 well captures the aerosol species data at Bhopal. However, MERRA-2 underestimated the annual mean in-situ concentration of organic carbon, black carbon, and sulphate by 1.9 µg m -3 (~22 %), 1.3 µg m -3 (~47 %) and 0.9 µg m -3 (~11 %), respectively and overestimated the sea salt and dust components by 0.75 µg m -3 (~95 %) and 8.5 µg m -3 (~153 %), respectively.  It is pertinent to note that dust from surface aerosol chemical species measurements was re-constructed using elemental aluminium, silicon, potassium, calcium, titanium, manganese concentrations. Further, the annual mean MERRA-2 PM2.5 mass (reconstructed from its constituent species) underestimated the average in-situ PM2.5 mass by 13.55 µg m -3 (~26.16 %). This underestimation is likely due to aerosol nitrate not being included in the MERRA2 PM2.5 mass and uncertainties in aerosol species concentrations resulting from limitations in the chemical transport model set-up and emissions inventories. This study discusses the possible causes of disagreements between in-situ measurements and MERRA2 products, in addition to estimating the effect of including nitrate in the MERRA2 PM2.5 mass reconstruction.