bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface radiocarbon record from the northern Indian Ocean: understanding surface ocean processes
Authors: Raj Harsh , Bhushan Ravi
Published: March 2021

Due to nuclear bomb tests during mid 1950s and 1960s, enormous amount of bomb radiocarbon was introduced into the atmosphere and subsequently to the ocean. Corals growing in shallow oceanic region record the radiocarbon variations in ocean surface waters. The bomb radiocarbon signature embedded in coral can be useful in providing information about natural processes affecting the surface waters of the region. In this regard, coral based radiocarbon records from the Lakshadweep Islands and the Andaman Islands from the northern Indian Ocean has been analysed. The analysed coral ∆14C values of recent period show comparable or even higher than the atmospheric ∆14C values, suggesting that major fraction of bomb radiocarbon have transferred in to the ocean. The northern Andaman region show ∆14C decline rate of about 3.1 ‰ yr-1 between 1978 to 2014. Whereas, the southern Bay of Bengal and the Lakshadweep records show relatively lower decline rate of 2.5 ‰ yr-1 for the same period. Based on the coral and atmospheric radiocarbon values, air-sea CO2 exchange rate over the Lakshadweep and Andaman region has been estimated. The bomb radiocarbon based estimate of air-sea CO2 exchange rate over Lakshadweep is 13.4 ± 2.1 mol m-2 yr-1 and over northern Andaman is 8.8 ± 1.3 mol m-2 yr-1. The Lakshadweep region show net regional CO2 flux of 2.5 ± 0.4 Tg C yr-1, while the northern Andaman region shows value of -0.3 ± 0.04 Tg C yr-1. This study discusses the spatial and temporal radiocarbon changes in the northern Indian Ocean and has implications to constraining the carbon flux over the region.
Isotopically labelled water - A valuable tracer to track initiation and progress of bud dormancy in temperate trees
Authors: Walde Manuel Gabriel , Saurer Matthias , Vitasse Yann
Published: March 2021

Leaf-out of deciduous trees is regulated by a set of environmental factors such as cool temperatures during winter-dormancy (chilling), warm spring temperatures (forcing), and daylength (photoperiod), with complex interactions between these factors. Teasing apart these different factors in situ is challenging as no visible changes occurs during the dormancy phase. Manipulating these factors in climate chamber experiments may overcome this issue but may not reflect how they truly interact in natural conditions. Previous researches suggested that bud meristems are disconnected from the xylem flow during endodormancy and that the connection become progressively restored once exposed to a certain duration of chilling. Here we developed a new method using isotopically labelled water (D2O) to quantify the amount of water that can reach buds during the whole dormancy till budburst for 5 different species (Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica, Quercus petraea, Tilia cordata).

In detail, we harvested twig cuttings from leaf fall to budburst (~every two weeks, 12 times) of these species from two different sites (about 5°C of difference) and placed them into labelled water during 24 h at constant light and 20°C. Buds were then cut and water content extracted to quantify δD. Thus, tracing back the water flow into the buds by the amount of D2O taken up. In parallel a subset of twigs was left in the room at 20°C to assess the time to budburst as a proxy for dormancy depth. Analyses of the data are ongoing and preliminary results show progressive increase of water uptake after induction of winter dormancy until budburst as chilling duration increased. Further, we also found distinct differences between species whereas Carpinus betulus showed the highest and Tilia cordata the lowest label uptake during winter dormancy. Furthermore, individuals growing at higher elevation took up less label indicating a stronger dormancy at lower winter temperatures. In summary, we think that our method seems a valuable tool to track quantitative changes in dormancy depth of temperate species especially, in combination with investigations on the molecular level such as sugars or hormones during winter-dormancy.
Unexpected Fast Monoterpene Oxidation In Eastern China
Authors: Wang Haichao
Published: March 2021

Monoterpene plays an important role in the formation of secondary aerosols and ozone in the troposphere. However, the field characterization of monoterpene chemistry in ozone pollution is still very sparse. Here we report fast daytime oxidation of monoterpene by hydroxyl radical, nitrate radical and ozone based on field measurements in Eastern China. We find fast monoterpene oxidation produces peroxy radicals efficiently and enhances the photochemical ozone production largely with an additional 8.6 ppb of ozone production per day on average (14%), whose effect was even more important than that of isoprene chemistry in the analyzed dataset. We propose that the reduction of anthropogenic volatile organic compounds should be much more stringent in the presence of high monoterpenes to alleviating ozone pollution.
Deep learning based F-Mask alternative for Sentinel-2 images in polar regions
Authors: Seehaus Thorsten , Nambiar Gopikrishnan Kamal , Morgenshtern Veniamin , Hochreuther Philipp , Braun Matthias
Published: March 2021

Screening clouds, cloud shadows, and snow is a critical pre-processing step that needs to be performed before any meaningful analysis can be done on satellite image data. The state of the art 'F-Mask' algorithm, which is based on multiple pixel-level threshold tests, segments the image into clear land, cloud, cloud shadow, snow, and water classes. However, we observe that the results of this algorithm are not very accurate in polar and tundra regions. The unavailability of labeled Sentinel-2 training datasets with these classes makes the traditional supervised machine learning techniques difficult to implement. Experiments with large, noisy training data on standard deep learning classification tasks like CIFAR-10 and ImageNet have shown neural networks learn clean labels faster than noisy labels. 

We present a multi-level self-learning approach that trains a model to perform semantic segmentation on Sentinel-2 L1C images. We use a large dataset with labels annotated using the F-mask algorithm for the training, and a small human-labeled dataset for validation. The validation dataset contains numerous examples where the F-mask classification would have given incorrect labels. At the first step, a deep neural network with a modified U-Net architecture is trained using a dataset automatically labeled with the F-mask algorithm. The performance on the validation dataset is used to select the best model from the step, which would then be used to generate more training labels from previously unseen data. In each of the subsequent steps, a new model is trained using the labels generated using the model from the previous step. The amount of data used for training increases with each step and the application of techniques like data augmentation and dropout improves the generalization of the trained model. We show that the final model from our approach can outperform its teacher, i.e. F-Mask algorithm. 
A reconstruction of the Cycladic Blueschist Domain (Cyclades, Greece)
Authors: Soukis Konstantinos , Stockli Daniel
Published: March 2021

The birth and death of oceanic areas have often proved to involve contemporaneous destruction of previously created and evolved oceanic domains and the initiation of new ones in back-arc areas. As a result, several and often competing geodynamic processes, have been taking place at the same time, thus creating a complex tectonostratigraphy.

The Attic-Cycladic Crystalline Complex (ACCC), in the Aegean Sea (Greece), the outcome of the formation and destruction of Paleotethyan and Tethyan oceanic domains, is one such case. Four major units have been identified in the ACCC. These are from top to bottom, the complex Upper Cycladic Nappe, the Cycladic Blueschist Unit, the pre-alpine Cycladic Basement, and the Basal Unit. The present-day configuration has resulted from an Eocene stage of subduction and metamorphism under blueschist to eclogite facies and an Oligocene-Miocene exhumation and metamorphic core complex formation, through a combination of contractional and extensional mechanisms. Original relations between these four units have been obscured from the Cenozoic tectonometamorphic processes and several conflicting views have been expressed in the literature, regarding the nature of the Cycladic Blueschist domain, the relation between the Cycladic Blueschist Unit and the Cycladic Basement.

In this paper, we make a reconstruction of the domain, from which the Cycladic Blueschist Unit originated, based on a synthesis of structural, tectonostratigraphic, geochemical, and geochronological data. Through this reconstruction, we attempt to reconcile existing controversies and differences of views in the literature and to highlight the major structures that controlled the main features and geological evolution of this remarkable area.
The aggradation process of transversal dunes since late-Pleistocene in Badain Jaran Desert, northwest China revealed by OSL dating
Authors: Shen Qinjing , Lai Zhongping
Published: March 2021

Transversal dunes are widespread in many deserts, but the application of these un-stabilized dunes in the palaeoclimate region is limited. Because transversal dunes normally migrate too fast, which means this kind of dune has a low possibility to record long period paleoclimate information. Nevertheless, both model simulations and field observation demonstrate that larger (higher) dunes containing a greater mass of sand have longer turn-over times. If so, there may be particular giant transversal dunes, in which long periods of climate changes are actually preserved and could be used as geoproxy to reconstruct paleoenvironment changes.

The Badain Jaran desert, situated in north-western China, features the tallest dunes (about 480 m) on the earth. More than 50% of the sand sea is covered by transversal dunes with an average height of 200 to 300 m. Here, we investigated two representative mega-dunes in the center of the desert and took 22 OSL samples systematically to try to reconstruct the deposition history of these two mega-dunes. Our result demonstrates that one of the dunes is formed since ~62 ka, with two phases of superposed dunes dated to 26~32 ka and modern time. Another mage-dune started to deposited from 29 ka and climbed by early to middle Holocene superposed-dunes and modern ones. Furthermore, while other active sand seas preserve scarcely aeolian sand deposited during the LGM period (Last Glacial Maximum: 26.5-19.0 ka BP), 11 of our 22 OSL dating results fall into the LGM period, which indicates that mega-dunes in the Badain Jaran desert continue aggradation during LGM. In that case，we speculate there are at least three factors facilitating the mega-dunes in Badain Jaran desert different from other transversal dunes that can preserve LGM sediments. (1) Badain Jaran desert, situated in a relatively subsiding basin, has a favor deposition condition; (2) The desert is close to the aeolian sand provenance area, an alluvial fan stored abundant silt-sand material derived from the southeast Tibet; (3) the shallow buried wet sand in Badain Jaran desert may promote the formation of the mega-dunes and reduce their migration speed, so that extend the turn-over times of the mega-dunes.
Understanding the atmospheric connection between the western Amazon and the Altiplano: A modelling approach
Authors: Segura Hans , Junquas Clementine , Espinoza Jhan Carlo , Lebel Thierry
Published: March 2021

The relationship between precipitation over the southern tropical Andes (STA; 20S-12S) and the Bolivian High has been revisited in a recent study (Segura et al., 2020). Western Amazon convection during the austral summer (DJF), which is located on the western side of the regional Hadley cell associated with the mature phase of the South America Monsoon System (SAMS), has been proposed as a new mechanism controlling interannual precipitation in this Andean region. This change in the controlling mechanisms is associated with the recent intensification of this regional Hadley cell, in particular, convection over the western Amazon, which has decreased the atmospheric stability in most of western tropical South America, including the southern tropical Andes. In this study, we explore the relationship of precipitation over the STA and these two atmospheric mechanisms by using the WRF model on a global scale to simulate 38 December-February seasons (1980-2017). First, we performed a series of experiments by changing the scheme of parametrization to select the one reproducing two characteristics of the SAMS: the regional Hadley Cell and the Bolivian High. On the other hand, the best set of parameterization schemes, even if reproducing these two climatic features, presented bias in precipitation and atmospheric circulation over South America. Additionally, WRF could not reproduce the long-term variability of precipitation over the STA. Aside from these expected biases, precipitation over the STA is also related to both identified mechanisms (the Bolivian High and the regional Hadley cell) in WRF simulation. Using the moist static energy approach, we explore the reasons for the relationship between the precipitation over the STA and western Amazon convection. In the following experiment, we explore the influence of western Amazon convection on the regional circulation over South America by no permitting the development of deep convection in this Amazonian region.
Identification and Evaluation of Ecosystem-based Approaches for Flood Risk Reduction in the Transboundary Lower Mono River Catchment in Benin and Togo
Authors: Schudel Lorina , Walz Yvonne , Akpamou Kokouvi Gbétey
Published: March 2021

Floods in West Africa repeatedly cause devastating impacts on human life and livelihoods, infrastructure and the environment and they are expected to increase in frequency and severity under a changing climate. Ecosystem-based approaches can be a cost-effective, efficient way to reduce flood risk while at the same time providing co-benefits. However, qualitative and quantitative assessments of ecosystem-based approaches that are suitable for the climatic conditions and socio-ecological system of the region are scarse. This study therefore identifies and evaluates climate-sensitive ecosystem-based approaches for the transboundary Lower Mono River Basin in Benin and Togo. The identification of ecosystem-based approaches has been done based on a review of scientific literature and complemented by a participatory approach with experts from the catchment. During focus group discussions, national stakeholders and policy makers identified, prioritized and mapped existing measures and provided their perspectives on prospective measures to reduce flood risk in the transboundary catchment. They include measures to reduce flow velocity, increase soil infiltration and improve water management. In a next step, we used a multi-criteria analysis considering ecological, climatic and flood hazard data to create suitability maps for different clusters of identified ecosystem-based approaches. This study is part of the CLIMAFRI project, which aims at creating a river basin information system for the Lower Mono Basin as well as creating a flood risk management plan. Through the integration of the suitability maps into the flood risk assessment tool, which has been created in the scope of this project, the ecosystem-based approaches are evaluated quantitatively. In a second round of focus group discussions with representatives from the local communities, feasibility of selected ecosystem-based approaches, co-benefits and trade-offs of the measures are discussed. Through the combination of qualitative and quantitative data, a holistic evaluation of ecosystem-based approaches and their contribution to hazard mitigation, increase of coping capacity, ecosystem resilience and overall flood risk reduction can be achieved.
Developing a novel monitoring system to determine rainfall interception from different forest types
Authors: Cooper Matt , Dickens Max , Patil Sopan , Thomas Huw
Published: March 2021

Natural Flood Management (NFM) seeks to utilise natural processes within the landscape to reduce flood risk and is increasingly being viewed as a sustainable, cost effective, and complementary addition to flood defence infrastructure.  One NFM measure is to increase the proportion of forested lands within catchments draining to the communities at risk. Tree cover has good potential to reduce flood risk by increasing canopy evaporation, enhancing below and above ground flood storage and slowing the flow of water towards streams.  However, the extent to which these mechanisms are superior for forestry, compared to other land uses, and how they vary throughout the year and for different forest types remains difficult to predict, which is a major gap in our ability to quantify how forest cover can help reduce flood risk.

 

Here, we present a study that utilises LoRaWAN, a developing wireless sensor network technology, to provide real time collection of canopy interception and streamflow data at the Pennal catchment in Wales, UK.  LoRaWAN is an emerging Low Power Wide Area Network (LPWAN) protocol designed for Internet of Things (IoT) applications. The capability of LoRaWAN to operate under harsh attenuation and interference conditions make it well suited to the forest catchment area which is characterised by dense vegetation and varied topography.

 

This study will utilise a network of tipping bucket rain gauges and stream flow monitors distributed in different forest types and densities. The rain gauges and water level monitors are the end devices (IoT things) in the network which perform a direct communication with LoRaWAN Gateways, from which the data is ‘pushed’ to a server for storing and assimilation. The data will be used to develop and validate a coupled canopy and soil hydrology model.  This will guide forest management and aid in quantifying the effects of natural flood management techniques, initially within the Pennal catchment, with a view to expanding to the regional scale.
Ground-Based GNSS Meteorology and Reflectometry Studies on Horseshoe Island during the 4th National Antarctic Science Expedition of Turkey: Installation and configuration of sea/ice level and water vapor monitoring stations.
Authors: Selbesoglu Mahmut Oguz , Yavasoglu Hasan Hakan , Karabulut Mustafa Fahri , Gulal V. Engin , Karaman Himmet , Kamasak Mustafa E. , Oktar Ozgun , Ozsoy Burcu
Published: March 2021

The radiation balance of our planet affect climate system that showing signs of breaking down due to the rising temperatures, melting of ice and water flows to the oceans from glaciers. In the last decade, GNSS Meteorology and Reflectometry methods are increasingly used for global climate change studies that provides important parameters such as water vapor in the troposphere and ice/sea level measured based on reflected signals. The main purpose of the study is retrieving meteorological and physical parameters of the Earth's surface in the Antarctica to contribute monitoring climate change. For this purpose, dual antenna and single antenna GNSS stations were specially designed within the scope of TUBITAK research project 118Y322 to produce output by combining an ultrasonic sensor to detect real-time ice/sea level. These two GNSS stations including meteorological station were installed on Horseshoe Island during 4th National Antarctic Science Expedition of Turkey (TAE-4). It is believed that these stations will contribute to monitor global climate change by providing important information about troposphere and physical characteristics of Earth surface. In this study, the processes and objectives from the design works of the stations to their installation in Antarctica are explained.  
A comparison of lidar depolarization and particle asphericity in high altitude clouds
Authors: Lucaferri Lorenza , Di Liberto Luca , Snels Marcel , Afchine Armin , Kraemer Martina , Cairo Francesco
Published: March 2021

We present and discuss the comparison between particle depolarization measurement observed in-situ by a backscattersonde (MAS) and particle asphericity measured by an optical particle counter and sizer with detector for particle asphericity (NIXE-CAPS), in high altitude clouds.

To our knowledge, this is the first time the in situ measurements of particle asphericity are directly compared with particle depolarization, an optical parameter usually accessible in remote sensing.

The two instruments flew together on the high altitude research aircraft M55 Geophysica, during the STRATOCLIM campaing in 2017, over Nepal. Particle asphericiy and depolarization measured in cirrus clouds will be compared and their dependence on the particle size distribution parameters will be studied. While relationships have been found between depolarization, asphericity and some microphysical parameters of the particle size distribution, quantitative correlations between asphericity and depolarization do not appear. We will discuss possible explanations for this apparent lack of quantitative correlation.
CryoSat-2’s contribution to the complete sea level records from the Polar Oceans 
Authors: Rose Stine Kildegaard , Andersen Ole Baltazar , Fleury Sara , Ludwigsen Carsten , Tsamados Michel , Dinardo Salvatore , Bouffard Jerome , Benveniste Jerome
Published: March 2021
The volcanic provinces of the Lennon-Picasso basin (Mercury)
Authors: Ferrari Sabrina , Massironi Matteo , Pozzobon Riccardo , Bedon Simone
Published: March 2021

The volcanic provinces are embedded between the NE margin of b56 /Lennon-Picasso basin and high terrain bounding structures. Resulting plains are interested by endogenic pits associated with pyroclastic activity, in agreement with the observation that Mercury's explosive volcanic vents tend to be located along major fold and thrust belts (Byrne et al 2014) and around large impact basins. Recent large scale mapping defined them intercrater plains partly covered by smooth plains (Malliband et al 2019; Whitten et al 2020). In addition to endogenic pits, these provinces display several 10-km diameter prominent cones, sometimes aligned forming high-relief ridges, resembling  constructional edifices. In colour composite images, cone tops are peculiarly darker (blue) or, alternatively, brighter (and yellow) with respect to the surrounding material. On the surface Mercury, Wright et al. (2019) interpreted two randomly located constructional edifices of similar size, attributing their origin to a late highly viscous  stage of volcanism that followed lower-viscous stage that are thought to provide typical smooth plains. Wider et al. (2016) proposed that the encounter of highly-viscous lavas with C-rich material during the magma ascent can easily provide volatiles (Zolotov et al. 2011) that progressively accumulate and lead to explosive eruptions. The resulting high reflectance of pyroclastic deposits would arise from removal of graphite as it was consumed during oxidation. The study aims to reveal the nature of cones at the margin of the Lennon-Picasso basin and to explain the relationship between a potential long-lasting volcanic activity and the concurrent global contractional regime.

Authors received funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47 and from European Union’s Horizon 2020 research grant under agreement 776276- PLANMAP.
Hybridization capture of Larix candidate adaptive genes from sedimentary ancient DNA.
Authors: Meucci Stefano , Schulte Luise , Stoof-Leichsenring Kathleen R. , Kruse Stefan , Krutovsky Konstantin , Herzschuh Ulrike
Published: March 2021

Siberian larch forests dominate large areas of northern Russia and contribute important roles for the world´s ecosystem. In order to understand the past dynamics of larches and their adaptive genetic variation, sedimentary ancient DNA (sedaDNA) extracted from lake sediment cores is a crucial source of genetic material. The difficulty of retrieving extremely rare DNA sequences from samples reaching back up to 25000 years in age, is challenging. Previous studies (Schulte et al.) showed that the hybridization capture allowed an enrichment of targeted sequences by several orders of magnitude in comparison to shotgun sequencing method. Therefore, we established for the first time, a hybridization capture method targeting 65 candidate adaptive genes laying on the Larix nuclear genome. Our preliminary results showed the ability of our newly established method to enrich extremely rare DNA sequences of the targeted Larix candidate adaptive genes, which were not retrieved by shotgun sequencing method applied on the same samples. Furthermore, the results allowed to detect and compare specific nucleotide polymorphism of adaptive candidate genes among sedaDNA samples distributed in space and time. The establishment of this new method is laying the basis to investigate possible adaptive variation of larch species acquired across the dry and cold conditions of the Last Glacial Maximum (LGM); as well as their possible advantages or disadvantages in relation to the current environmental changes toward dry and warm conditions.
Matching crystal habits and radiosonde profiles in Northern Finland
Authors: Mignani Claudia , Zimmermann Lukas , Kivi Rigel , Berne Alexis , Conen Franz
Published: March 2021

Crystal habits encode atmospheric conditions. Temperature and relative humidity with respect to ice and liquid water are the microphysical drivers of the growth of snow crystals in terms of shape, size and degree of riming, while cloud thickness and the related growth time of crystals are the dynamical drivers. According to current versions of Nakaya’s habit diagram, rather large and eventually rimed crystals are formed above supersaturation. Below supersaturation compact and unrimed snow crystals are to be expected. In this study, we combine radiosonde profiles with snowflake images captured at the surface by a multi-angle snowflake camera during two-and-a-half winter seasons in Northern Finland (67.367 °N, 26.629 °E). Our objective is to quantify how well crystal habits correspond with what would be expected from radiosonde profiles at this continental site in the Arctic.
The permeability of magma mush assembled from anisotropic tabular crystals
Authors: Bretagne Eloïse , Wadsworth Fabian B. , Dobson Katherine J. , Vasseur Jérémie , Coumans Jason P.
Published: March 2021

The extraction of melt from a mush in a magma reservoir is of wide interest. All models for melt extraction from a mush require knowledge of mush permeability, and yet this remains poorly constrained. This permeability is typically calculated using the Kozeny-Carman model or variants thereof, which require a priori knowledge of the microstructural geometry. Such models are not calibrated or tested for packs of crystals of a range of shapes found in natural mush piles, leading to the potential for oversimplification of complex natural systems.

Essentially, a magma mush with minimal crystal-crystal intergrowth is composed of packed crystals where the pore space is filled with interstitial melt. Therefore, this can be studied as a granular medium. We use numerical methods to create domains of closely packed, randomly oriented cuboids in which we keep the short and intermediate axes lengths equal (i.e. square cross section) and vary the long axis magnitude. Our synthetic ‘crystals’ therefore cover the range from oblate to prolate, passing through a cubic shape. We supplement these with 3D numerical packs of spherical particles in cubic lattice arrangements or random arrangements. For the sphere packs we use various polydispersivity of sphere sizes. The permeability of all of these pack types is calculated using a numerical simulation (both LBflow and Avizo-based algorithms) with imposed periodic boundary conditions. The preliminary results suggest that the permeability of a granular medium scales with the specific surface area exclusively, without requiring prior knowledge of the geometry and size distribution of the particles.

We suggest that the model toward which we are working will allow magma mush permeability to be modelled more accurately. If our approach is embedded in existing continuum models for mush compaction and melt extraction, then more accurate estimates of melt accumulation rates prior to very large eruptions could be found.

Keywords: melt segregation, compaction, granular media, fluid flow, numerical simulation
Mapping, Monitoring, Forecasting and Assessing the Impact of Climate Change in Groundwater Systems in Ireland
Authors: Campanyà i Llovet Joan , McCormack Ted , Doherty Damien , Schuler Philip , Kabza Monika , Mullarkey Ellen , Naughton Owen
Published: March 2021

In recent years Ireland has experienced significant and unprecedented flooding events, such as groundwater floods, that extended up to hundreds of hectares during the winter flood season, lasting for weeks to months, and affecting many rural communities in Ireland. In response to the serious flooding of winter 2015-2016, specifically related to groundwater, Geological Survey Ireland (GSI) initiated a project (GWFlood, 2016-2019), in collaboration with Trinity College Dublin (TCD) and Institute of Technology Carlow (ITC), to investigate the drivers, map and numerically model the extent of groundwater flooding in Ireland. Through this project, the use of remote sensing data, Sentinel-1 satellite imagery from the European Space Agency Copernicus program, was key to overcome the practical limitations of establishing and maintaining a national field-based monitoring network. The main outputs for this project included: 1) a national historic groundwater flood map, 2) a methodology for hydrograph generation using satellite images, and 3) predictive groundwater flood maps for Ireland.

Subsequently GSI started a new project (GWClimate, 2020-2022), in collaboration with ITC, to monitor floods in Ireland using remote sensing data, to enable short-term forecasting groundwater floods at a national scale, and to evaluate the potential that climate change may have on Irish groundwater resources, both in terms of flooding and drought issues. The GWClimate project is enhancing the tools developed by GWFlood in order to deliver: 1) seasonal flood maps for Ireland, 2) near-real time satellite-based hydrographs, 3) groundwater flood forecasting tools, and 4) maps evaluating the impact of climate change in groundwater systems in Ireland. The outputs of this project will contribute to monitor and quantify the impacts of flooding in Ireland at a national scale, improve the national capacity to understand how groundwater resources respond to climatic stresses, and improve the reliability of adaptation planning and predictions in the groundwater sector.

Data and maps from GWClimate and GWFlood projects are available at: 1) https://gwlevel.ie, and 2) https://www.gsi.ie/en-ie/programmes-and-projects/groundwater/activities/groundwater-flooding/gwflood-project-2016-2019/Pages/default.aspx
Surface velocity variations of glaciers on Kenai Peninsula, Alaska, 2014-2019
Authors: Yang Ruitang , Hock Regine , Kang Shichang , Shangguan Donghui , Guo Wanqin
Published: March 2021

We characterize the spatiotemporal variations surface velocity of glaciers on the Kenai Peninsula, Alaska, using intensity offset tracking on a set of repeat-pass Sentinel-1 data and TerraSAR-X data. We derived 92 velocity fields and generated time-averaged annual and seasonal surface velocity maps for the period October 2014 to December 2019, as well as time series surface velocity profiles along centerlines for individual glaciers. We find considerable spatial and seasonal variations in surface velocity in the study area, especially a pronounced average spring speedup of 50% averagely compared to annual mean velocity. Ice velocities varied systematically between glaciers with different terminus types. Generally, the pixel-averaged velocity of tidewater and lake-terminating glaciers are up to 2 and 1.5 times greater than those of the land-terminating glaciers, respectively. For Bear glacier, with the analysis of surface velocity profile and the terminus change, we state this glacier retreat and accelerate. While the time-series result shows the velocity speed-up of the Bear glacier synchronizes well with the ice-damaged lake outburst flood (GLOF) events.
Night-time NO emissions suppress large amounts of chlorine radical formation in Delhi
Authors: Haslett Sophie , Kumar Varun , Prevot Andre , Slowik Jay , Bell David , Tripathi Sachi , Mishra Suneeti , Singh Atinderpal , Rastoji Neeraj , Ganguly Dilip , Thornton Joel , Dällenbach Kaspar , Yan Chao , Mohr Claudia
Published: March 2021

Concentrations of particulate chloride can reach values over 100 µg m-3 during the winter in Delhi, which is among the highest levels recorded across the globe. In the presence of nitrogen pentoxide (N2O5), this chloride can form nitryl chloride (ClNO2), which photolyses in sunlight and releases the Cl radical. The Cl radical is an incredibly potent oxidant, reacting with some volatile organic compounds (VOCs) orders of magnitude faster than more common oxidants such as OH. Chlorine would therefore be expected to play a significant role in the oxidation of VOCs in Delhi.

We carried out intensive measurements of particle- and gas-phase physical and chemical properties during a field campaign in Delhi in early 2019. A suite of instruments was used, including a chemical ionisation mass spectrometer fitted with a filter inlet for aerosols and gases (FIGAERO-CIMS) to measure N2O5 and ClNO2. Despite N2O5 typically being considered a night-time compound, we in fact observed the highest concentrations in the mid-afternoon and almost none at all during the night. Further analysis indicated that the ubiquity of night-time NOx emissions in the city suppresses night-time production of N2O5. As a result of this unusual diurnal pattern, high concentrations of ClNO2 are unable to form overnight. The morning peak in ClNO2 and the subsequent release of chlorine radicals, while large compared with some other urban environments, is therefore much smaller than might have been expected given the high levels of particulate chloride.

In this presentation, I will discuss our observations and the impact of this unusual diurnal pattern on the atmospheric chemical profile. Impacts include a shift of even typically ‘night-time’ oxidation patterns to the day and a likely overall reduced oxidative capacity in the city’s atmosphere. Our results indicate that a reduction in chlorine emissions must be considered in tandem with NOx emission reductions in efforts to reduce Delhi’s pollution.
Land-use change effects on biodiversity through mechanistic simulations: A case study with South-Asian mammals
Authors: P. Silva Andre , Thorn Filip , Zurell Damaris , Cabral Juliano
Published: March 2021

Land-use change remains the main driver of biodiversity loss, and fragmentation and habitat loss are expected to lead to further population declines and species losses . We apply a recently developed R package for a spatially-explicit mechanistic simulation model (RangeShiftR), which incorporates habitat suitability, demographic as well as dispersal processes to understand temporal effects of land-use change (Land-use harmonization scenarios for the 1900-2100 period) on abundance and richness of mammalian species in South-Asia. We then compare land-use scenarios with and without protected areas to understand if current spatial conservation strategies are able to sustain viable populations independently of the land-use scenarios followed. Our approach is innovative in assessing how land-use scenarios can influence animal populations through underlying ecological processes.
The CMEMS High Resolution Coastal Service
Authors: Van der Zande Dimitry , Stelzer Kerstin , Böttcher Martin , Cardoso dos Santos João Felipe , Lebreton Carole , Vanhellemont Quinten , Sterckx Sindy
Published: March 2021

High-quality satellite-based ocean colour products can provide valuable support and insights in management and monitoring of coastal ecosystems. Today’s availability of Earth Observation (EO) data is unprecedented including traditional medium resolution ocean colour systems (e.g. SeaWiFS, MODIS-AQUA, MERIS, Sentinel-3/OLCI), high resolution land sensors (e.g. Sentinel-2/MSI, Landsat-8/OLI, Pleiades) and geostationary satellites (e.g. SEVIRI). Each of these sensors offers specific advantages in terms of spatial, temporal or radiometric characteristics.

As a new production unit, the high resolution coastal service will be integrated in CMEMS. It offers 12 different products which are covered within the Ocean Colour Thematic Assembly Centre (OCTAC). The products can be categorized in two groups: 1) near real time (NRT) and Multi-Year near real time (MYNRT). The products are generated the coastal waters (20km stripe for the coastline) for all European Seas and are provided in 100m spatial resolution. All products are based on Sentinel-2 MSI data. The primary OCTAC variable from which it is virtually possible to derive all the geophysical and transparency products is the spectral Remote Sensing Reflectance (RRS). This, together with the Particulate Backscatter Coefficient (BBP), constitute the category of the optics products. The spectral BBP product is generated from the RRS products using a quasi-analytical algorithm. The transparency products include turbidity (TUR) and Suspended Particulate Matter (SPM) concentration. They are retrieved through the application of automated switching algorithms to the RRS spectra adapted to varying water conditions. The geophysical product consists of the Chlorophyll-a concentration (CHL) retrieved via a multi-algorithm approach with optimized quality flagging. The NRT products are generally provided withing 24 hours after end of the acquisition day, while monthly averaged products are provided few days after end of the respective month. A third group of products are daily gap-filled products which are provided once in a quarter. Validation of the variables has been performed by match-up analysis with in situ data as well as by comparison of the high resolution products with the well established Low Resolution CMEMS Ocean Colour products. The products will be introduced in the CMEMS service by May 2021. We will present the products themselves as well as the validation results for the different variables. The known limitations will be reported in order to provide a full picture of the new service.
Fossil molluscan fauna reflects zonation of a Late Pleistocene reef of the Red Sea
Authors: Haider Anna , Ivkić Angelina , Kroh Andreas , Mansour Abbas , Zuschin Martin
Published: March 2021

Many studies focus on modern coral reefs and their associated invertebrate fauna, but not much is known about the paleoecology and diversity of molluscs of Late Pleistocene coral reefs, which were formed during the last interglacial MIS5e. This study is investigating the molluscan assemblage of a Late Pleistocene coral reef in southern Egypt, at the locality Sharm El Luli, in the area of Marsa Alam. The locality is characterized by a variety of reef- and reef associated habitats, including a reef flat, reef slope, a patch reef, and soft bottoms of a lagoon and in the backreef area. We quantitatively and qualitatively sampled 10 sites with a total of 79 samples and collected 2126 shells, which belong to 177 taxa, mostly identified to the species level.   Most taxa were found with the qualitative sampling approach. The most abundant bivalves taxon was the epifaunal, encrusting Chama spp., the most abundant gastropod species was the cerithiid Rhinoclavis vertagus. Regarding the life habitats most bivalve species are infaunal filter feeders, while most gastropods are epifaunal carnivores.    Alpha diversity is highest in the coral patch and in the upper reef region, which implies the reef slope, the reef flat as well as the transition between reef slope and the lagoon. Preliminary statistical results suggest a division in coral-patch, lagoon and backreef as well as a cluster of upper-reef habitats. From these two broad environments can be distinguished: hard bottoms associated to reefs and reef-associated soft bottom environments. The former are best characterized by encrusting taxa such as Chama spp. and Spondylus spp., and by Tridacna maxima and Perigylypta spp., which are well-known reef associates. Gastropods in this environment are predatory conids and cypraeids. All of these species live on - or occur cryptically in - structured hard bottoms. Reef associated-soft bottom environments are best characterized by infauna, such as the tellinid Quidinipagus palatam and the lucinids Anodontia kora and Pillucina vietnamica. Furthermore, many soft bottom gastropod species such as the strombid Gibberulus gibberulus albus, the cerithiid Rhinoclavis vertagus, both with an herbivorous diet, and the nassariid Nassarius fenistratus, a scavenger, can be found here.  A comparison with modern datasets from the Red Sea indicates strong similarities in faunal composition and habitat diversity between fossil and recent reefs.  Furthermore, our preliminary results suggest that Late Pleistocene molluscan assemblages can aid in reconstruction of associated fossil reef habitats. 
How does the suspended sediment yield change in the North Caucasus during the Anthropocene?
Authors: Tsyplenkov Anatoly , Golosov Valentin
Published: March 2021

Processes linked to climate change and intensified anthropogenic pressure influence the environment, the hydrology and by extent the denudation processes in the Caucasus mountain belt. Quantitative assessments of sediment fluxes and their temporal evolution in this mountain region required for various environmental and engineering purposes, including the planning and maintenance of water reservoirs and other structures. This paper presents an analysis of the suspended sediment load data from almost 40 gauging stations located in the mountain part of the Terek river basin (North Caucasus, Russia). The collected dataset include river basins with various glacier cover (0%-20%) and human impact. All river basins show consistent decreases in mean annual suspended sediment load (SSL, kg/s) up to 1–2% per year during 1925–2018 (according to Mann-Kendall test). The cumulative deviation curve of the mean annual SSL for the last 60 years indicates that SSL has increased significantly from ca. 1970-1980 to 1990-2000 for the most North Caucasus rivers. However, after the 2000s mean annual values of the SSL show a stable decrease in all observed rivers. Possible mechanisms of observed changes are discussed. This study provides the data on climate-related changes in the sediment yield for a previously not investigated region.
Seismic wave attenuation due to fluid pressure diffusion at the mesoscopic scale: an experimental and numerical study
Authors: Chapman Samuel , Borgomano Jan V. M. , Quintal Beatriz , Benson Sally M. , Fortin Jerome
Published: March 2021

Monitoring of the subsurface with seismic methods can be improved by better understanding the attenuation of seismic waves due to fluid pressure diffusion (FPD). In porous rocks saturated with multiple fluid phases the attenuation of seismic waves by FPD is sensitive to the mesoscopic scale distribution of the respective fluids. The relationship between fluid distribution and seismic wave attenuation could be used, for example, to assess the effectiveness of residual trapping of carbon dioxide (CO2) in the subsurface. Determining such relationships requires validating models of FPD with accurate laboratory measurements of seismic wave attenuation and modulus dispersion over a broad frequency range, and, in addition, characterising the fluid distribution during experiments. To address this challenge, experiments were performed on a Berea sandstone sample in which the exsolution of CO2 from water in the pore space of the sample was induced by a reduction in pore pressure. The fluid distribution was determined with X-ray computed tomography (CT) in a first set of experiments. The CO2 exosolved predominantly near the outlet, resulting in a heterogeneous fluid distribution along the sample length. In a second set of experiments, at similar pressure and temperature conditions, the forced oscillation method was used to measure the attenuation and modulus dispersion in the partially saturated sample over a broad frequency range (0.1 - 1000 Hz). Significant P-wave attenuation and dispersion was observed, while S-wave attenuation and dispersion were negligible. These observations suggest that the dominant mechanism of attenuation and dispersion was FPD. The attenuation and dispersion by FPD was subsequently modelled by solving Biot’s quasi-static equations of poroelasticity with the finite element method. The fluid saturation distribution determined from the X-ray CT was used in combination with a Reuss average to define a single phase effective fluid bulk modulus. The numerical solutions agree well with the attenuation and modulus dispersion measured in the laboratory, supporting the interpretation that attenuation and dispersion was due to FPD occurring in the heterogenous distribution of the coexisting fluids. The numerical simulations have the advantage that the models can easily be improved by including sub-core scale porosity and permeability distributions, which can also be determined using X-ray CT. In the future this could allow for conducting experiments on heterogenous samples.
Accuracy assessment of bare soil map of Hungary based on Sentinel satellite data
Authors: Mészáros János , Takáts Tünde , Árvai Mátyás , Laborczi Annamária , Szatmári Gábor , Pásztor László
Published: March 2021

As Earth observation (EO) data is increasing in volume, fast and reliable data-processing tools are also required especially for analyzing large areas with high spatial resolution. Google Earth Engine (GEE) platform provides wide sets of EO imagery and elevation data in a cloud-based processing environment. This research focused on i) the generation of bare soil map of Hungary and ii) the accuracy assessment of created soil maps representing soil texture (clay, sand, silt) and soil chemical parameters (SOC, pH and CaCO3).

In this study Copernicus Sentinel-1 SAR and Sentinel-2 optical images acquired on a mid-term time period between 2017 April and 2020 December were used to generate a median composite. Optical images were filtered for cloud coverage less than 50% and a cloud mask was also implemented on all remaining images. The threshold values for Normalized Difference Vegetation Index and Normalized Burn Ratio indices were 0.55 and 0.35 respectively to differentiate bare soil pixels.

We tested the prediction accuracy of bare soil composite supplemented by various environmental datasets as additional predictor variables in different scenarios: (i) using solely bare soil composite data (ii) composite data, elevation and its derived parameters (e.g. slope, aspect) (iii) composite data and spectral indices and (iv) all aforementioned data in fusion.

For validation two types of datasets were used: i) the reference points of the Hungarian Soil Information and Monitoring System with a five-fold cross-validation method and ii) the recently compiled national maps for soil texture and soil chemical parameters.

Acknowledgment: Our research was supported by the Hungarian National Research, Development and Innovation Office (NKFIH; K-131820 and K-124290) and by the Scholarship of Human Resource Supporter (NTP-NFTÖ-20-B-0022).