bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the impact of Pleistocene climate change on early humans in the southern Kalahari
Authors: Wilkins Jayne , Pickering Robyn , von der Meden Jessica , Gliganic Luke , Brown Kyle S , Esteban Irene , Khumalo Wendy , Chiwara Precious , Sahle Yonatan , Kirsten Kelly , Schoville Benjamin J
Published: March 2021

Homo sapiens exhibit extreme behavioural plasticity, mediated by culture and technology, that permits us to adapt rapidly to new environments and situations. Understanding the role that past climate change played in selecting for Homo sapiens’ adaptability is a key question in human evolution research. The arid and semi-arid Kalahari Basin in southern Africa is an ideal region for addressing this question because fossil, genetic, and archaeological evidence supports an early origin for Homo sapiens in southern Africa. The growing archaeological record of the Kalahari Basin reveals that significant behavioural innovations accumulated in the region over the course of the Middle and Late Pleistocene, including ochre use, hafted hunting weapons, fishing, and figurative paintings. Here, we report the results of interdisciplinary investigations at two locales in the southern Kalahari; Ga-Mohana Hill and Witberg 1. The archaeological and palaeoenvironmental record (based on U-Th dating of tufas) at Ga-Mohana Hill reveals that site occupation correlated with a previous period of increased effective precipitation ~110-100 ka, and preliminary results suggest a more complicated relationship between occupation and precipitation after that time. At Witberg 1, Middle Stone Age archaeology is associated with the shoreline of a previously unidentified palaeolake. Current investigations are focused on dating the Witberg deposits, analysing the lithic technology, and generating palaeoenvironmental archives using phytoliths and diatoms. Collectively, this research provides a rare opportunity to evaluate Middle Stone Age occupation across a changing landscape from both stratified rockshelters and sealed open-air sites, to explore the complex interactions between past climate change and early human behaviors, and to better understand the origins of Homo sapiens extreme adaptability.
Applying stable water isotopes to determine root water uptake patterns in an urban forest land
Authors: Lan Zhiqing , Chen Han , Li Han , Huang Jinhui Jeanne , McBean Edward , Zhang Jiawei , Gao Junjie
Published: March 2021

The scarcity of water resources is an important issue in urbanization. Urban forest land water consumption accounts for a large part of urban water resources, the study of water uptake patterns in urban forest area is crucial for urban water saving and precision irrigation, but no identified research have investigated water uptake patterns in urban forest area until now. In this study, we measured the deuterium isotope ratio (δD) and the oxygen isotope ratio (δ18O) of precipitation, irrigation water, xylem water and soil water sources in a locust tree forest in Jinnan District of Tianjin City, China across 2019-2020. Water sources proportion in the root zone area of different growing seasons were obtained by IsoSource model, MixSIR model and SIAR model. Results show that there is a significant difference in soil moisture content between different stand age locust trees in time and depth variation. The trend of soil moisture of different stand ages of locust in time sequence intend to increase first and then decrease, the most significantly change of soil water content happened in shallow layer (0~40 cm). The change in vertical depth is about the same. The soil profile of 0-200 cm was discretized into three layers. The shallow layer (0~40 cm) soil water δD and δ18O fluctuated widely and decreased with the depth increased. This study revealed the dynamic replenishment of the root zone water in urban forest land, and provides insights into reforestation and water management in urban area.
Antarctic warmth in the last interglacial driven by Northern insolation and deglaciation
Authors: Obase Takashi , Abe-Ouchi Ayako , Saito Fuyuki
Published: March 2021

The global mean sea level in the last interglacial (LIG, about 130,000 to 115,000 years before present) was very likely higher than the present level, driven mainly by mass loss of the Antarctic ice sheet. Some studies have suggested that this mass loss may have been caused by the warmer temperature over the Southern Ocean in the LIG compared with the present interglacial. However, the ultimate cause of the difference in Antarctic warming between the last and current interglacials has not been explained. Here, based on transient simulations of the last deglaciation using a fully coupled ocean–atmosphere model, we show that greater meltwater (by a factor of 1.5 relative to the last deglaciation) during the middle and later stages of the deglaciation could have produced the difference in Antarctic warmth. Northern Hemisphere ice sheet model experiments suggest that the difference in meltwater was caused by slightly smaller orbital eccentricity in our current interglacial than in the LIG, indicating that mass loss of the Antarctic ice sheet is influenced by the preceding northern summer insolation and disintegration of Northern Hemisphere ice sheets.
Intelligently Gapfilling Earth Observations: Towards a coherent observational view of Land Hydrology
Authors: Bessenbacher Verena , Gudmundsson Lukas , Seneviratne Sonia I.
Published: March 2021

Earth observations have many missing values. Their complex patterns of missingness can be a significant hurdle for studying Earth system dynamics and climate change impacts. To overcome this issue, missing values are regularly imputed, i.e. infilled, using techniques such as interpolation. However, the common practice to do this for each variable separately can negatively affect the covariance between different data products, resulting in biased estimates. Moreover, relying solely on interpolation for infilling missing values makes only inefficient use of information that may be available from other variables at the same location in space and time.

Here we propose a modular gap-filling algorithm that exploits the multivariate nature of Earth system observations and builds upon the notion that if a value is missing, it is likely that some other variables will be observed at the same location and time and their relationship can be learned. To this end, the algorithm expands upon simple interpolation by additionally applying a statistical imputation method that is designed to account for covariance across variables.

The algorithm is tested using gap-free reanalysis data of relevant variables to land surface processes: ground temperature, precipitation, terrestrial water storage and soil moisture. These variables were masked to match missingness patterns of remote sensing observations. Subsequently, the gap fill estimates can then be compared to the original reanalysis values to assess the merit of the gap fill.

Overall, estimates of the proposed algorithm have lower bias and higher correlation compared to simple interpolation. Furthermore, we demonstrate that the multivariate core of the algorithm improves the physical consistency across the considered variables. In case studies focussing on large-scale droughts, extreme values are correctly reconstructed even in cases of high fraction of missing values. The algorithm can thus be used as a flexible tool for gapfilling remote sensing and in-situ observations commonly used in climate and environmental research and create a coherent observational dataset of a flexible set of observational products.
Carbon isotope and sequence stratigraphy of the upper Isachsen Formation on Axel Heiberg Island (Nunavut, Canada): High Arctic expression of oceanic anoxic event 1a in a deltaic environment
Authors: Dummann Wolf , Schröder-Adams Claudia , Hofmann Peter , Rethemeyer Janet , Herrle Jens O.
Published: March 2021

Oceanic anoxic event (OAE) 1a documents a major perturbation of the Early Cretaceous global carbon cycle with severe consequences for the ocean-climate-biosphere system. While numerous studies over the past decades have provided a relatively detailed picture of the environmental repercussions of OAE 1a at low and mid-latitudes, studies from high latitudes, in particular the High Arctic, are limited. In this study, we present a high-resolution carbon isotopic and sequence stratigraphic framework for the lower to lower upper Aptian interval of the Isachsen Formation of the High Arctic Sverdrup Basin (Canada). These data enable us to precisely locate the stratigraphic position of OAE 1a in a deltaic sedimentary environment. The carbon isotope record allows, for the first time, identification of the different carbon isotope segments (CISs) of OAE 1a in the Sverdrup Basin and thereby correlation of the High Arctic record with sections from lower latitudes. Based on this improved chemostratigraphy, we revise the age of upper Paterson Island, Rondon, and Walker Island Members, important regional lithostratigraphic marker units. Whole-rock geochemical data record two episodes of marine incursion into the Sverdrup Basin during OAE 1a (CISs Ap3 and Ap6), which are interpreted as regional maximum flooding surfaces. This information is used in conjunction with detailed sedimentological logs and geochemical grain-size proxies to refine the sequence stratigraphic framework for the upper Isachsen Formation. We propose that transgressive-regressive cycles in the Sverdrup Basin were mainly controlled by the combined effects of eustatic sea-level changes and regional tectonic uplift, potentially related to the emplacement of Alpha Ridge, which culminated at ca. 122 Ma during CIS Ap9.
Field evidence for fluid facilitated fracturing and Dissolution-Precipitaion creep explains observed off-fault tremor and continuous deformation: Field examples from the Alpine Fault, New Zealand 
Authors: McGrath Jack , Piazolo Sandra , Morgan Rebecca , Elliott John
Published: March 2021

Geophysical observations show that the Alpine Fault in New Zealand is characterised by mid-crustal off-fault recurring tremor events and off-fault regions of continuous deformation. While geodesy indicates that deformation is distributed across the South Island, evidence from the rock record shows deformation accommodated in a region within several km from the fault. This zone is characterized by a 100-300 m wide mylonitised central fault zone and an approximately 8--10km, wide deformation region marked by the presence of Alpine foliation. Magnetotelluric surveys of the Southern Alps indicate a mid-crustal, high signal area coinciding with the location of the recurring tremors.  

While the mylonites and their associated mechanisms have been extensively studied in the field area, the wider off-fault deformation region has not had the same scrutiny. In the latter region, we observe frequent layer parallel, folded and crosscutting quartz veins. Quartz vein orientation and geometries are consistent with fracturing in the presence of fluid within an overall tectonic stress regime. The observed overprinting of older veins by younger vein generations, as well as their successive reorientations, indicate recurring fracturing within a continuously deforming region. Quantitative analysis of vein geometries including their width and displacement shows that vein formation may trigger the observed mid-crustal tremor signal. Microstructural signatures within the host rock are consistent with dissolution-precipitation creep as the main deformation mechanism in the host rock and pre-existing veins.  

In summary, according to field evidence both geophysically observed transient and continuous deformation take place in the presence of fluid and occur contemporaneously. This implies that strain accommodation in the host rock facilitated by dissolution-precipitation creep is insufficient; consequently, stress is build-up over time triggering intermittent fracturing.  
From knowledge to action – can modern and active teaching formats help to bridge the value-action gap among school students and raise their climate-friendly behavior?
Authors: Feldbacher Eva , Waberer Manuela , Campostrini Lena , Weigelhofer Gabriele
Published: March 2021

Numerous studies and survey results indicate that the majority of the population is aware of climate change and displays worries about it, but only a few people show willingness to change their behavior accordingly and to act more climate-friendly. The discrepancy between knowledge and action (value - action gap) is seen as an obstacle to successful adaptation to climate change, and is particularly pronounced in the young population group. In addition to the lack of a sound basic knowledge, young people above all lack the believe in their own possibilities and the conviction that their actions are enough to achieve something (“bigger than self-dilemma”). 

We initiated a research – education – cooperation project to reach out for school students and tried to motivate them to engage intensively with climate change and to increase their climate-friendly behavior. Modern teaching and learning formats were used in order to contrast to the typical “learning” at school and foster voluntary engagement, to transfer positive messages and solutions, and to emphasize the self - efficacy of their actions. The aim of the project was to examine, whether an active engagement over a prolonged time period with topics around climate change can achieve a greater effect on the understanding of complex relationships and raise climate-friendly behavior more effectively than a short, passive learning phase. With the help of an online questionnaire all involved students answered climate-relevant questions of the categories “behavior, perception and knowledge” before and after the activities.

The questionnaire results revealed that a general knowledge about climate change and climate awareness exist among the students surveyed, even before the project activities. More than 90% believe that every single person can contribute significantly to tackle climate change. However, students had problems with understanding complex relationships and long-term interactions of the consequences of climate change on people and ecosystems. For example, it was difficult for students to correctly estimate virtual water consumption and to see the potential social consequences of climate change.

We believe that modern educational concepts on climate change should foster system understanding and seize on the young people’s positive attitude towards climate protection by pointing out concrete, climate-friendly ways of behavior. In this way it is possible to strengthen the young people’s believe in their actions (self-efficacy) and to reduce the gap between attitude and action.
Are Cryosphere-Driven Feedbacks a Requisite for Abrupt Climate Events? (Site U610, DSDP Leg. 94)
Authors: Holmes Dakota , De Vleeschouwer David , Morley Audrey
Published: March 2021

Abrupt climate events are important features of glacial climate scales on centennial and millennial timescales. These events' mechanistic trigger is often ascribed to either ice sheet-related feedback mechanisms or large freshwater pulses. In both cases, amplification occurs when these triggers bear upon the Atlantic Meridional Overturning Circulation (AMOC). However, the focus on glacial climate states in abrupt climate change research has led to an underrepresentation of research into interglacial periods. It thus remains unclear whether high-magnitude climate variability requires large cryosphere-driven feedbacks or whether it can also occur under low ice conditions. Using sediment core DSDP U610B (53°13.297N, 18°53.213W) located in the Rockall Trough, we present a high-resolution analysis of surface and deep water components of the AMOC spanning the transition from Marine Isotope Stage (MIS) 19.3 to 19.1 to test if orbital boundary conditions similar to our current Holocene can accommodate abrupt climate events. Above the core site, the dominant oceanographic feature is the North Atlantic Current and at 2417-m water depth, U610 is influenced by Wyville Thomson Overflow Water flowing southwards. We utilise a multiproxy approach including paired grain size analysis, planktic foraminifera assemblage counts, and ice-rafted debris counts within the same samples allowing us to resolve the timing between both surface and bottom components of the AMOC and their response to abrupt climate events during MIS-19 in the eastern subpolar gyre. We also present for the first time a new splice and composite depth scale for Site U610. Based on preliminary results, rapid shifts in both deep overflow and surface climate characterise this period.
Virtual outcrops: Field work on lockdown conditions using Drones
Authors: Borrás Fernando , Hopfenblatt Joaquín , Geyer Adelina , Aulinas Meritxell
Published: March 2021

The year 2020 was full of challenges in many aspects, and it was not an exception for Earth Science education. Field work, which is the most effective tool for developing the capacity of spatial visualization of Geology students, was restricted, or even banned, during long time periods. The lockdown conditions highlighted the immediate need of techniques that “could” bring the field to our classrooms and homes through electronic devices.

The use of “Remotely Piloted Aircraft System” (RPAS), commonly known as drones, for geological purposes is increasing year after year involving different fields of geology, such as hazard assessment, monitoring, volcanology, structural geology among others. Drones allow obtaining, for an affordable price (compared to airplane or helicopter renting) and under safe conditions, updated aerial photography from any perspective resulting in a more efficient fieldwork. At present, there are different working teams using drones mainly for geological research purposes. However, those focused on teaching innovation systems by combining science and drone technology are still limited.

We propose the use of this technology to create 3D virtual outcrops with research or teaching purposes. Indeed, in those cases in which face-to-face teaching is not possible or the outcrop is located in a hard-to-reach or hazardous areas, virtual fieldtrips can be a valuable and safe alternative. Moreover, it approaches geological outcrops to people with physical disability or with reduced mobility promoting a more inclusive environment. Virtual outcrops also offer scientist, students and the general public the opportunity to visit, explore and study remote places all over the world with the possibility of creating a worldwide virtual catalog of outcrops with importance in Earth Sciences. Among other interesting applications there is the possibility of combining drone generated products with geographic information systems (GIS), photogrammetry and virtual modelling software’s, widely used by research institutions and universities which would open a full new scope of studies for students and professors.

Since the second half of year 2020, “Drones4Geology” cooperative, in collaboration with universities and research centers, is building a collection of high-quality 3D virtual outcrops and orthomosaics obtained from drone photogrammetry of different sites of Catalonia considered of geological interest, (e.g., Southern Pyrenean fold and thrust belt, Hercynian intrusive rocks of la “Costa Brava”) aiming to put these 2D and 3D tools at the disposal of students and researchers.
Effective Uncertainty Visualization for Aftershock Forecast Maps
Authors: Schneider Max , McDowell Michelle , Guttorp Peter , Steel E. Ashley , Fleischhut Nadine
Published: March 2021

Seismicity rate estimates and the earthquake forecasts they yield vary spatially and are usually represented as heat maps. While visualization literature suggests that displaying forecast uncertainty can improve how forecast maps are used, research on uncertainty visualization (UV) is missing from earthquake science. We present a pre-registered online experiment to test the effectiveness of three UV techniques for displaying aftershock forecasts. These maps show the expected number of aftershocks at each location for a week following a hypothetical mainshock, and we develop maps of the uncertainty around each location’s forecast. Human participants complete experimental tasks using the aftershock forecast displayed with its uncertainty. Three different UVs are producted: (1) forecast and uncertainty maps adjacent to one another; (2) the forecast map depicted in a color scheme, with the uncertainty shown by the transparency of the color; (3) two maps that show the lower and upper bound of the forecast distriubiton at each location. We compare task performance using UVs and using the forecast map shown without its uncertainty (the current practice). Subjects complete two map-reading tasks that target several dimensions of the readability of the three UVs. They then perform a comparative prediction task, which demonstrates whether a UV is successful in reaching two key communication goals: indicating where an aftershock and no aftershocks are likely (“sure bets’’) and where the forecast is low but the uncertainty is high enough to imply potential risk (“potential surprises’’). All UVs perform equally well in the goal of communicating “sure bet’’ situations. But the UV with lower and upper bounds is significantly better than the other UVs at communicating “potential surprises.” We discuss the implications of these results for communication of forecast uncertainty within and beyond earthquake science.
Coherent and Non-Coherent Components of Mesoscale Variations of Hydroxyl Rotational Temperature near the Mesopause.
Authors: Popov Andrey A. , Gavrilov Nikolai M. , Perminov Vladimir I. , Pertsev Nikolai N. , Medvedeva Irina V. , Ammosov Petr P. , Gavrilyeva Galina A. , Kaltovskoi Igor I.
Published: March 2021

Mesoscale variations of the rotational temperature of excited hydroxyl (OH*) are studied at altitudes 85 – 90  km using the data of spectral measurements of nightglow emission at Russian observatories Zvenigorod (56 ° N, 37°E.) in years 2004  –  2016, Tory (52 ° N, 103°E) in  2012  –  2017 and Maimaga (63° N,  130° E) in  2014 - 2019. The filtering of mesoscale variations was made by calculations of the differences between the measured values of OH* rotational temperature separated with time intervals of dt ~ 0.5 - 2 hr. Comparisons of monthly variances of the temperature differences for various dt allow us to estimate coherent and non-coherent in time components of the mesoscale temperature perturbations. The first component can be associated with mesoscale waves near the mesopause. The non-coherent component may be produced by instrument errors and atmospheric turbulence. The results allow us correcting the observed mesoscale temperature variances at all listed sites for contributions of instrumental and turbulent errors. Seasonal and interannual changes in the coherent component of mesoscale variances of the temperature at the observational sites are studied, which may reflect respective changes in the intensity of mesoscale internal gravity waves in the mesosphere and lower thermosphere region.

     The analysis of nightglows data was supported by the grant #19-35-90130 of the Russian Foundation for Basic Research. Hydroxyl nightglow data at the Tory site were obtained with the equipment of the Center for Common Use «Angara» http://ckp-rf.ru/ckp/3056/ at the ISTP SB RAS within budgetary funding from the Basic Research Program (Project 0278-2021-0003). Data of the “Geomodel” Resource Center of Saint-Petersburg State University were used.
Missing data completion in wastewater network databases: the added-value of Graph Convolutional Neural Networks.
Authors: Belghaddar Yassine , Delenne Carole , Chahinian Nanée , Begdouri Ahlame , Seriai Abderrahmane
Published: March 2021

Wastewater networks are mandatory for urbanization. Their management, which includes reparation and expansion operations, requires precise information about their underground components, mainly pipes. For hydraulic  modelling purposes, the characteristics of the nodes and pipes in the model must be fully known via specific, complete and consistent attribute tables. However, due to years of service and interventions by different actors, information about the attributes and characteristics associated with the various objects constituting a network are not  properly  tracked and reported. Therefore, databases related to wastewater networks, when available, still suffer from a large amount of missing data.

A wastewater network constitutes a graph composed of nodes and edges. Nodes represent manholes, equipment, repairs, etc. while edges represent pipes. Each of the nodes and edges has a set of properties in the form of attributes such as diameters of the pipes. In this work, we seek to complete the missing attributes of wastewater networks using machine learning techniques. The main goal is to make use of the graph structures in the learning process, taking into consideration the topology and the relationships between their components (nodes and edges) to predict missing attribute values.

Graph Convolutional Network models (GCN) have gained a lot of attention in recent years and achieved state of the art in many applications such as chemistry. These models are applied directly on graphs to perform diverse machine learning tasks. We present here the use of GCN models such as ChebConv to complete the missing attribute values of two datasets (1239 and 754 elements) extracted from the wastewater networks of  Montpellier and Angers Metropolis in France. To emphasize the importance of the graph structure in the learning process and thus on the quality of the predictions, GCNs' results are benchmarked against non-topological neural networks. The application on diameter value completion, indicates that using the structure of the wastewater network in the learning process has a significant impact on the prediction results especially for minority classes. Indeed, the diameter classes are very heterogeneous in terms of number of elements with a highly majority class and several classes with few elements. Non-topological neural networks always fail to predict these classes and affect the majority class value to every missing diameter, yielding a perfect precision for this class but a null one for all the others. On the contrary, the ChebConv model precision is slightly lower (0.93) for the majority class but much higher (increases from 0.3 to 0.81) for other classes, using only the structure of the graphs. The use of other available information in the learning process may enhance these results.
Simulating the FIP effect in coronal loops using a multi-species kinetic-fluid model
Authors: Poirier Nicolas , Lavarra Michael , Rouillard Alexis , Indurain Mikel , Blelly Pierre-Louis , Réville Victor , Verdini Andrea , Velli Marco , Buchlin Eric
Published: March 2021

We investigate abundance variations of heavy ions in coronal loops. We develop and exploit a multi-species model of the solar atmosphere (called IRAP’s Solar Atmospheric Model: ISAM) that solves for the transport of neutral and charged particles from the chromosphere to the corona. We investigate the effect of different mechanisms that could produce the First Ionization Potential (FIP) effect. We compare the effects of the thermal force and of the ponderomotive force. The propagation, reflection and dissipation of Alfvén waves is solved using two distinct models, the first one from Chandran et al. (2011) and the second one that is a more sophisticated turbulence model called Shell-ATM. ISAM solves a set of 16-moment transport equations for both neutrals and charged particles. Protons and heavy ions are heated by Alfvén waves, which then heat up the electrons via collision processes. We show preliminary results on composition distribution along a typical coronal loop and compare with typical FIP biases. This work was funded by the European Research Council through the project SLOW_SOURCE - DLV-819189.
On the size dependence of cumulus cloud spacing
Authors: van Laar Thirza , Neggers Roel
Published: March 2021

The spatial variability of Trade wind cumulus cloud fields has been found to be of great importance for understanding their role in Earth's climate system. In this study the focus is on the spacing between individual cumulus clouds. The main objective is to establish how inter-cloud spacing depends on cloud size, information that is crucial for understanding cloud-radiation interaction and spatial organization, and for informing grey zone parametrizations. To this end, a large-domain high resolution ICON LES simulation of marine shallow cumulus cloud fields is used. The domain is located at the subtropical Atlantic and the simulations are performed for the time of the recent NARVAL South campaign (December 2013). The simulations are compared with MODIS satellite imagery and research flight measurements, showing a good agreement between observations and the simulation, on both cloud size statistics and the vertical structure of the boundary layer.  

To determine the size and locations of the clouds, a cluster analysis was applied to the data. The inter-cloud, or nearest neighbor spacing (NNS), is addressed using four different expressions, classic definitions but also novel ones. For all definitions the spacing increases with cloud size, but the dependence is strongly influenced by the used definition. The classic definition, the spacing between clouds of any size, shows a well-defined logarithmic dependence on cloud size. The logarithmic relation can be explained by the abundance of closely-spaced small clouds. The small distances between these clouds form an upper bound for the NNS for the larger cloud sizes. In contrast, the spacing between clouds of a similar size increases exponentially with size. We argue that the exponential size-dependence reflects the mesoscale dynamics that drive the horizontal size of large convective cells, of which the cumulus clouds are the visible parts.  
Integration of Hidden Markov States in a hydrological model calibration/validation protocol
Authors: Guilpart Étienne , Espanmanesh Vahid , Tilmant Amaury , Anctil François
Published: March 2021

Due to climate changes, the stationary assumption in hydrology has become obsolete. Moreover, the uncertainty regarding the future evolution of the Earth's climate and its impact on flow regimes is still large. Over the last decade, new risk management approaches have been proposed to support water resources planning under deep uncertainty. Those approaches rely at some point on a hydrological model to derive time series of streamflows for various hydro-climatic scenarios. One of the key issue is to make sure that the hydrological model is robust, i.e. that it performs well over contrasted hydro-climatic conditions. The differential split-sample test principle proposed by Klemes in 1986 recommends partitioning the time series into numerous and independent subperiods with different stationary climate features. Then, the hydrological model calibration is achieved on a specific climate period, and the validation on other(s). Classical detection methods commonly used to partition the times series, such as Mann-Kendall test or Pettitt test, can only detect a single change point, and thus are unable to handle complex climate sequences with multiple change points. We propose a calibration/validation protocol of hydrological models which rely on both the differential split-sample test and on an Hidden Markov Model to identify a succession of subsequences in a time series based on the state of the underlying process. We applied the proposed protocol on the Senegal River (West Africa). The hydrological model used is the conceptual GR2M model. Results show that (i) when the river discharges time series does not display a clear climate trend, and have multiple change points, classical rupture tests are not suitable. Hidden Markov Models are a good alternative as long as the climate sub-sequences are long enough (typically around 30 years or more); (ii) including a Hidden Markov Models in such protocol open up the range of possibilities for calibrate/validate, which can lead to an enhancement of the criterion function (but not necessarily).

Klemes, V.: Operational testing of hydrological simulation models, Hydrological Sciences Journal, 31, 13-24, 415 https://doi.org/10.1080/02626668609491024, 1986.
Investigations based on biaxial tiltmeter array and uniaxial hydrostatic levelling system at the Mont Terri rock laboratory
Authors: Rebscher Dorothee , Guglielmi Yves , Gutierrez Inma , Meier Edi , Schefer Senecio
Published: March 2021

In order to enable investigations and further comprehensive understanding of dynamical processes, it is clear one has to identify all relevant parameters and aim to record them all under best conditions concerning e.g. resolution, coverage in space, and in many cases on a multitude of scales in time. Obviously, it is also difficult to satisfy all these constrains in full. Especially scientific long-term observations often suffer the lack of necessary lasting commitment; secure funding, continual high quality maintenance, protected environment, or sufficient planning stability. Fortunately, the Swiss Mont Terri rock laboratory, with its history of now 25 years of forefront scientific expertise, a long-standing fruitful cooperation formed by the partners of the consortium and in consequence thereof state-of-the-art results obtained through 100 completed individual experiments and 45 additional experiments actually ongoing, ensures the conditions listed above.

Based on this favorable prospect, a now growing tiltmeter array is established at the underground laboratory. The instruments are embedded in several multidisciplinary experiments, dedicated to numerous, different scientific questions. Starting in April 2019, the first two platform tiltmeters became operational. Less than two years later, ten biaxial instruments are quasi-continuously monitoring deformation at various locations within the galleries and niches at Mont Terri. The envisioned, increasing spatial coverage of the network will facilitate geodetic observations of the underground rock laboratory as a whole and of its subregions as well.

Already in September 2012, a 50 m long hydrostatic levelling system (HLS) was installed along a gallery in the underground laboratory to detect displacements across an active geological fault zone. The combination of both, i.e. the uniaxial, integral deformations data provided by HLS together with the array of biaxial, point measurements acquired by the tiltmeters offers a unique concerted opportunity to achieve detailed deformation data in a large underground rock laboratory and to survey the associated dynamical processes occurring on timeframes covering seconds to decades.
U-Th dated late Pleistocene tufas linked to human occupation in the semi-arid southern Kalahari
Authors: von der Meden Jessica , Wilkins Jayne , Schoville Benjamin , Brown Kyle , Pickering Robyn
Published: March 2021

Ga-Mohana Hill North Rockshelter (GHN) in the Northern Cape Province of South Africa is situated within the Summer Rainfall Zone, in the semi-arid (~300-400mm mean annual rainfall) southeastern edge of the Kalahari Basin. This location is significant as the dominant narrative for the evolution of modern humans has focused on Middle Stone Age archaeological sites along the southern cape coast of South Africa, with coastal resources and favourable climate conditions argued as key factors in driving the evolution of Homo sapiens. Semi-arid regions in the interior of South Africa, such as the southern Kalahari Basin, are often considered to have been too dry to sustain significant human occupation and activity, and have thus been overlooked. However, GHN does indeed preserve rich stratified Middle and Later Stone Age deposits, as well as abundant large relict tufa deposits that cover the surrounding hillside. These tufas, which are ambient temperature, freshwater calcium carbonate deposits, are indicative of past periods of flowing surface waters and shallow pools on the hillside. Laser ablation trace element mapping was used to pre-screen the tufa samples to target layers with high 238U and little to no 232Th concentration for U-Th dating. The resultant ages show that the tufa system at Ga-Mohana was active during five distinct intervals over the last 110 ka, three of which closely coincide with the timing of human occupation at the site, itself dated via OSL. The coincidence of tufa formation and human occupation suggests that the tufa-forming waters were a critical resource to human populations living in the area. This hitherto undiscovered source of fresh water, more than 600 km inland and as far back as 110 ka, stands to challenge the notion of an empty and arid interior.
Understanding changes in meteorological drought in regional UK Climate Projections (UKCP18)
Authors: Reyniers Nele , Addor Nans , Darch Geoff , He Yi , Zha Qianyu , Osborn Timothy
Published: March 2021

Extreme droughts can cause enormous ecological and economic damage, and are expected to become more severe in some regions due to climate change. For water managers, it is crucial to understand extreme droughts and how they are projected to change compared to previous droughts, in order to plan for resilience to these events. 

Changes in water resources do not only result from changes in precipitation and periods of below normal precipitation (meteorological droughts), they are also shaped by changes in atmospheric moisture demand, characterized here by potential evaporation. Therefore we use two standardized indicators, the Standardized Precipitation Index (SPI) and the Standardized Precipitation-Evaporation Index (SPEI) to isolate the impact of projected changes in precipitation and potential evaporation. We consider the contribution of precipitation deficits and potential evaporation changes to projected changes in future drought duration, severity and frequency. We explore droughts and their development across different time scales, as their diversity – from flash droughts to creeping multi-year droughts – adds to the challenge.

We make use of the recently released 12-member 12-km horizontal resolution perturbed parameter ensemble of spatially coherent regional UKCP18 climate projections (with and without bias adjustment). This ensemble of projections was produced by the UK Met Office by dynamically downscaling a perturbed parameter ensemble of HadGEM3-GC3.05 simulations with a regional variant. The skill of the UKCP18 regional ensemble members for drought simulation is evaluated by comparison with observed drought metrics for the baseline period. 
Projected changes in UK climate according to the UKCP18 projections include wetter winters, drier summers and generally stronger temperature increases in summer than in winter. We assess how these changes contribute to changes in drought characteristics using SPI and SPEI for each member of the ensemble. 

While this work focusses on meteorological droughts, it will be followed by a future analysis of their propagation to hydrological droughts. This project aims to support adaptation to droughts in the region of East Anglia and is conducted in collaboration with the water company Anglian Water. 
Meltwater driven abrupt climate changes in the North Atlantic simulated in a Heinrich Stadial 1 background
Authors: Romé Yvan , Ivanovic Ruza , Gregoire Lauren
Published: March 2021

Heinrich stadial 1 is one of the most enigmatic episodes in the study of the last deglaciation. Following the Lamospheric forcing increased driving the vast ice sheets over North America and Europe to melt. Yet, the climate in the North Atlantic remained cold for another 6000 years before eventually switching to a warm interstadial state in an event referred to as the Bolling warming. If there is now a consensus on the central role of the Atlantic Meridional Overturning Circulation (AMOC), the mechanisms at stake are still highly debated, which is a real challenge when it comes to reproducing such behaviour in climate models.

We studied this period looking spest Glacial Maximum (LGM, ~21 thousand years ago), orbital and atcifically at the feedback between the climate and the freshwater released from melting ice. From a transient record of meltwater discharge across the last deglaciation derived from the GLAC1D ice sheet reconstruction, we produced General Circulation Model (GCM) simulations of the LGM climate with different freshwater forcing. More precisely, we examined three notable melting events that happened during the early deglaciation: a local minimum of discharge at the LGM, a peak in meltwater discharging the North Atlantic signal and a peak in meltwater discharging in the Arctic signal. The three experiments generated very different patterns in AMOC and in North Atlantic climate, including alternatively warm, cold and oscillating regimes depending on the forcing.  

These results provide a good framework to analyse further the relationship between abrupt climate changes and meltwater discharge and to highlight the key parameters to trigger climate transitions in state-of-art climate models in the context of the last deglaciation. It is also a great opportunity to describe some mechanisms at stake with salt oscillations in the Atlantic, sea-ice cover and deep-water formation sites feedback and shifts in the subpolar gyre during interstadial-stadial transitions.
Direct detection of auroral and equatorial jets in the stratosphere of Jupiter with ALMA
Authors: Cavalié Thibault , Benmahi Bilal , Hue Vincent , Moreno Raphael , Lellouch Emmanuel , Fouchet Thierry , Hartogh Paul , Rezac Ladislav , Greathouse Thomas , Gladstone Randall , Sinclair James , Dobrijevic Michel , Billebaud Françoise , Jarchow Christopher
Published: March 2021

The upper tropospheric zonal winds have been measured since decades using cloud tracking with maximum winds speeds of ∼ 100 m/s in the tropical region (Ingersoll et al. 1979). Juno measurements have shown that these winds extend in the deep layers of the planet (Kaspi et al. 2018). In the ionosphere, jets have been detected in the auroral zone with velocities of 1-2 km/s (Rego et al. 1999). In-between these atmospheric regions, in the stratosphere, there are no such tracers as clouds. Even if zonal winds can in principle be indirectly derived from temperature field by assuming the thermal wind balance (e.g. Flasar et al. 2004), this technique relies on a boundary condition often taken as the cloud-top structure which is located at levels that are separated from where the stratospheric temperature field is constrained. Also, this technique breaks down at equatorial latitudes.

Using the Atacama Large Millimeter/submillimeter Array, we mapped Jupiter’s stratospheric HCN emission in March 2017 to directly measure wind-induced Doppler shifts on the spectral lines. We imaged the HCN limb emission with an angular resolution of 1” and a very high spectral resolution. After subtracting the rapid rotation of the planet from the Doppler shifts measured on the spectral lines, we derived the wind speeds as a function of latitude on both limbs.

We find strong tropical jets at 1 mbar with velocities of 100-200 m/s lying atop the layers where the Quasi-Quadrennial Oscillation occurs. Most surprisingly, we find strong non-zonal winds in Jupiter’s polar regions at 0.1 mbar with counter-rotation velocities of 300-400 m/s. Their position coincides with the location of the main auroral oval.

In this paper, we will present our observations and results. We will also discuss their implications on the dynamics and chemistry of Jupiter’s stratosphere.
Living Matter as a Self-Organizing System
Authors: Korzh Vyacheslav
Published: March 2021

Biological evolution proceeded under the sign of the liberation of developing organisms from the power of random phenomena in the external environment. At a certain stage in the evolution of living matter - the totality of all living organisms, it became possible to basically implement liberation from the instability of the external environment. Back in the eighteenth century J.-B. Lamarck argued and tried to prove that all substances located on the surface of the globe and forming its crust were formed due to the activity of living organisms. V.I. Vernadsky wrote: “On the earth's surface there is no chemical force that is more permanently acting, and therefore more powerful in its ultimate consequences than organisms taken as a whole” [1]. We find convincing proofs of the formation of a biogeochemical environment by living matter in accordance with their needs in the work of V.V. Kovalsky's [2].

We have studied the dynamics of the global process of transfer of chemical elements in the ocean-atmosphere-continent-ocean system. Living matter is an active participant in this process. As a result of metabolic processes, living matter constantly creates and constantly maintains an increased concentration of trace elements in its environment. The biocenosis of the hydrosphere initiates  increasing of the soluble forms of microelements in its habitat. The terrestrial biocenosis acts in the opposite direction [3]. The nonlinear laws of the processes of redistribution of average elemental compositions in the biosphere between liquid and solid phases (hydrosphere-lithosphere system) have been established. We have established a universal constant of nonlinearity of these processes in the biosphere (equal to 0.7) [3].

Human activity makes irreversible changes in the dynamics of the biosphere, and at the present stage of development of a technogenic civilization, the scale of human expansion into natural processes is such that they begin to destroy the biosphere as an integral ecosystem. The impending global ecological catastrophe requires development of fundamentally new strategies in scientific  activities that ensure harmonious coexistence of man and nature. We are developing the concept of the harmonious integrity of the biosphere (the concept of biosphere homeostasis). The stability of biogeochemical and other processes on the Earth's surface is completely determined by the coordinated, purposeful activity of living matter as an integral system [3]. The universal constant of nonlinearity of the processes of formation of the elemental composition of the biosphere (equal to 0.7) established by us should be accepted as an ecological standard, violation of which is unacceptable.

References.