bluuebunny/crossref_metadata_2025 huggingface dataset:
Scalable Change Detection in Large Sentinel-2 data with SEVA
Authors: Sips Mike , Eggert Daniel
Published: March 2022

We present SEVA, a scalable exploration tool that supports users in detecting land-use changes in large optical remote sensing data. SEVA addresses three current scientific and technological challenges of detecting changes in large data sets: a) the automated extraction of relevant changes from many high-resolution optical satellite observations, b) the exploration of spatial and temporal dynamics of the extracted changes, c) interpretation of the extracted changes. To address these challenges, we developed a distributed change detection pipeline. The change detection pipeline consists of a data browser, extraction, error analysis, and interactive exploration component. The data browser supports users to assess the spatial and temporal distribution of available Sentinel-2 images for a region of interest. The extraction component extracts changes from Sentinel-2 images using the post-classification change detection (PCCD) method. The error assessment component supports users in interpreting the relevance of extracted changes with global and local error metrics. The interactive exploration component supports users in investigating the spatial and temporal dynamics of extracted changes. SEVA supports users through interactive visualization in all components of the change detection pipeline.
Seafloor spreading modes across the Charlie Gibbs transform system (52°N, Mid Atlantic Ridge)
Authors: Sanfilippo Alessio , Skolotnev Sergey , Ligi Marco , Peyve Alexander ,   A.N. Strakhov Expedition S50 and A.N. Vavilov Expedition V53 Science Parties
Published: March 2022

The prominent Charlie Gibbs right-lateral multi-transform system (52°-53°N) offsets the Mid Atlantic Ridge (MAR) by ~340 km. The transform system is formed by two distinct transform faults linked by a short ~40 km-long intra-transform spreading centre (ITR). The two adjacent MAR segments are influenced by both the Azores and the Iceland mantle plume. Recently, high resolution multibeam surveys and a dense sampling program of the entire transform system, including the adjacent southern and northern MAR segments, were carried out during expeditions of R/V Celtic Explorer (2015, 2016 and 2018) [1], R/V A.N. Strakhov (2020) and A.S. Vavilov (2021) [2]. The new surveys show widespread occurrence of large structures with corrugated surfaces and exhumed lower crust and mantle rocks on both sides of the intra-transform spreading axis. Morphological analyses of the intra-transform domain and magnetic data indicate that crustal accretion was driven by flip-flop detachment faulting [3], with minimal ridge melt supply and little axial volcanism. The tectonic spreading persisted for tens of millions of years. Along axis MORB chemistry shows that changes in seafloor accretion styles are mirrored by variations in melt supply, in turn dependent on mantle temperature and by a large-scale mantle heterogeneity. Charlie Gibbs is a key case study of how seafloor accretion modes at a spreading segment is critically dependent on mantle thermal state but also on its intrinsic compositional heterogeneity.

[1] Georgiopoulou A. and CE18008 Scientific Party, 2018. Tectonic Ocean Spreading at the Charlie-Gibbs Fracture Zone (TOSCA): CE18008 Research Survey Report. Marine Institute of Ireland, Dublin, pp 1-24. [2] Skolotnev, S. et al., 2021. Seafloor Spreading and Tectonics at the Charlie Gibbs Transform System (52-53ºN, Mid Atlantic Ridge): Preliminary Results from R/V AN Strakhov Expedition S50. Ofioliti, 46(1). [3] Cannat, Met al., 2019. On spreading modes and magma supply at slow and ultraslow mid-ocean ridges. Earth and Planetary Science Letters, 519, 223-233.
Evaluating the skill of seasonal forecasts of sea ice in the Southern Ocean: insights from the SIPN South project 2017-2022
Authors: Massonnet François , Reid Phil , Lieser Jan , Bitz Cecilia , Fyfe John , Hobbs Will
Published: March 2022

The SIPN South project is an international, coordinated initiative endorsed by the Year Of Polar Prediction (YOPP), that aims at identifying the skill of current seasonal predictions of sea ice around Antarctica. Here, we review and analyze the results of five years of predictions of summer sea ice conducted by 20 groups since 2017, having contributed together more than 1000 forecasts. A wide range of approaches is considered, ranging from statistical data-driven to dynamical process-based models. We evaluate the ability of the forecasts to reproduce observed sea ice area at the circumpolar and regional levels and their skill relative to trivial forecasts (climatology, persistence). We find that a substantial spread exists already at day one in the dynamical forecasts, pointing at problems with the initialization. We also find that the forecasts based on statistical modeling perform generally better than forecasts based on dynamical modeling.
High frequency spatio-temporal dynamics of seagrass meadows in a mediterranean lagoon
Authors: Goodwin Guillaume , Marani Marco , Carniello Luca , D'Alpaos Andrea , Silvestri Sonia
Published: March 2022

Seagrass meadows are a famously productive habitat found globally in intertidal and shallow subtidal shelves, hosting a rich biodiversity and efficiently sequestering carbon. They also exert an influence on coastal morphodynamics by modifying tidal flat roughness and erodibility, affecting sediment dynamics in coastal environments in a way that is not yet fully documented.

Due to their sensitivity to environmental change and anthropogenic pressure, seagrass is prone to widespread die-off, which can be worsened by punctual degradation events such as dredging. Conversely, high primary productivity allows degraded meadows to recover rapidly, as well as expand through clonal and sexual reproduction. This potential for rapid change, however, is not currently matched by the frequency of observations of seagrass meadows, making it difficult to assess the spatial and temporal dynamics of seagrass meadows and their impact on intertidal zones.

Using a novel method combining machine learning and time-series analysis, we extract seasonal maps of seagrass cover in the Southern Venice Lagoon from over 150 Landsat images over the 1999-2021 period and over 100 Sentinel images over the 2017-2021 period. By analysing changes in seagrass distribution over time, we identify seasonal extrema in seagrass surface area and observe their decadal evolution. Furthermore, we record the frequency and magnitude of sudden seagrass die-off events as well as recovery times. From these data we identify regions of preserved root mat, and by coupling seagrass dynamics with additional environmental data such as water temperature, sediment concentration and wave height, propose a set of possible degradation drivers and conditions for seagrass meadow recovery.

With this contribution, we show how high-frequency mapping of seagrass distribution can reveal spatio-temporal dynamics of a highly productive coastal ecosystem, as well as offer keys to their response to environmental change.
New developments and diagnostics related to the mass flux convective parameterization in the NEMO ocean model 
Authors: Pelletier Charles , Bourdallé-Badie Romain , Giordani Hervé , Samson Guillaume , Garric Gilles , Perruche Coralie , Gutknecht Élodie
Published: March 2022

Ocean convective events are triggered by vertical density instabilities, e.g., following significant surface heat loss at dusk or upon sea-ice formation. They have a significant impact on the vertical distribution of ocean heat, salt, and biogeochemical content, most frequently in its shallowest few hundreds of meters, but also occasionally much deeper. The representation of such events within ocean models requires a specific treatment adapted to vertically nonlocal processes, since most turbulent closure schemes are based upon Boussinesq-derived diffusivity coefficients and are thus fundamentally local. Consequently, different methods have been employed for making vertical diffusion schemes also accounting for convection. Past examples used in NEMO include, e.g., adding a nonlocal term in the diffusivity parameterization (e.g., K-profile) or simply enhancing the vertical diffusivity. 

Another more recent example is the mass-flux convective (MFC) scheme, which has recently been adapted for the NEMO ocean model and can be used as a convective complement to any diffusion-only scheme (e.g., scaled from turbulent kinetic energy). The MFC scheme allows generating subgrid-scale buoyancy-driven convective plumes which can reach down to 2000m depth in extreme cases. Within the plumes, physical quantities of interest (e.g., temperature, salinity) are vertically transported independently from the large-scale model dynamics, at velocities which can exceed by far anything permitting by it (up to 20 cm s-1) implying fast, deep-reaching vertical mixing.  Hence, in addition to local fluxes associated with small, diffusion-related eddies, the large-scale model solution can also be affected by nonlocal convective fluxes associated with large eddies produced by the MFC scheme. 

In this talk, we present new developments and tests related to the MFC parameterization. Namely, we introduce the application of this scheme to passive biogeochemical tracers, as well as turbulent kinetic energy and model dynamics (i.e., ocean velocities). Results over 1D configurations illustrating the impact of these novelties are presented. Finally, we also show first results over a NEMO global 1/4° configuration involving previously unexplored convection-prone conditions, such as sea-ice formation.
Influence of energetic particle precipitation on Antarctic stratospheric chlorine and ozone over the 20th century
Authors: Maliniemi Ville , Arsenovic Pavle , Seppälä Annika , Nesse Tyssøy Hilde
Published: March 2022

Chlorofluorocarbon (CFC) emissions in the latter part of the 20th century reduced the stratospheric ozone abundance substantially, especially in the Antarctic region. Simultaneously, polar stratospheric ozone is also depleted catalytically by reactive nitrogen (NOx) gasses. Energetic particle precipitation linked to solar activity and space weather produces NOx in the polar mesosphere/lower thermosphere, which during winter descend to stratospheric altitudes via mean meridional residual circulation. NOx can also limit the CFC ozone destruction, e.g., by transforming active chlorine and nitrogen into a reservoir of chlorine nitrate. We study the interaction between EPP produced NOx, ClO and ozone over the 20th century by using free running climate simulations of the chemistry-climate model SOCOL3-MPIOM. Substantial increase of NOx descending to polar stratosphere is found during winter, which causes ozone depletion in the upper and mid-stratosphere. However, the EPP-NOx induced ozone depletion becomes less efficient in the Antarctic mid-stratosphere after 1960s, especially during springtime. At the same time, significant decrease in Antarctic stratospheric ClO between 1-30 hPa over winter and spring can be ascribed to the EPP-NOx. This is true even during the CFC era. Hence, chlorine gasses contributed to reducing the efficiency of the EPP-NOx ozone depletion at these altitudes and vice versa. Our results show that EPP has been a significant modulator of reactive chlorine in the Antarctic stratosphere during the CFC era. With the implementation of the Montreal Protocol, stratospheric chlorine is estimated to return to pre-CFC era levels after 2050. We can thus expect increased efficiency of chemical ozone destruction by EPP-NOx in the future Antarctic upper and mid-stratosphere.
Three-dimensional particle-in-cell simulation of high-speed plasma jets interacting with Mercury’s magnetosphere
Authors: Voitcu Gabriel , Echim Marius , Teodorescu Eliza , Munteanu Costel
Published: March 2022

The transport of high-speed plasma jets (or clouds, streams, blobs, plasmoids) across magnetic discontinuities/shocks is a key process for planetary magnetic environments. Recently, a large number of localized magnetic structures detected in-situ by MESSENGER in the Hermean magnetosheath has been reported in the literature. These structures are similar to the high-speed plasma jets identified in the Earth’s magnetosheath. Due to some limitations in the plasma measurements on-board MESSENGER, only the magnetic signature has been studied. The BepiColombo mission provides a great opportunity to further advance this type of investigation. In this paper we use 3d3v electromagnetic particle-in-cell simulations to study the transport and entry of high-speed plasma jets into Mercury’s magnetosphere. The physical setup is adapted to simulate the kinetic effects and their role on the dynamics of localized plasma structures propagating from the magnetosheath toward the Hermean magnetopause. The magnetospheric field of planet Mercury is provided by the KT17 model, while the high-speed plasma jets are defined as 3D finite-size elements with their bulk velocity pointing towards the dayside magnetopause. We investigate the space and time evolution of the plasma jets prior, during and after their impact on the Hermean magnetopause. We analyse the parallel and perpendicular dynamics with respect to the background magnetic field and emphasize key physical processes for the propagation of high-speed plasma jets across transverse magnetic fields. Our simulations shall support the future exploitation of in-situ data from BepiColombo.
Application of remote sensing big data in landslide identification
Authors: Song Yuqi , Hu Xie
Published: March 2022

Landslides are general natural disasters in the world. Knowledge on the landslide distribution is fundamental for landslide monitoring, disaster mitigation and reduction. Traditional in-situ observations (e.g., leveling, GPS, extensometer, inclinometer) usually have high accuracy, but they are expensive and labor intensive and may also involve risks in the field. Alternatively, remote sensing data can capture the regional land surface features and thus are efficient in landslide mapping. Recent studies on landslide identification mainly rely on the pixel-based or object-oriented classification using optical images. Nonetheless, landslide activities are governed by multiple processes including the topography, geology, land cover, catchment, precipitation, and tectonics (e.g., dynamic shaking or aseismic creeping). Remote sensing data and products are beneficial to extract some of these critical parameters on a regional scale. Rapid development of machine learning algorithms makes it possible to systematically construct landslide inventory by interpreting multi-source remote sensing big data. The populous California suffers from high risks of landsliding. The United States Geological Survey (USGS) compiles the landslide inventory in the State and reports that California has about 86k landslides. Steep slope in the costal ranges, wet climate in the northern California, youthful materials at the surface from active tectonics of the San Andreas Fault and secondary fault systems, dynamic and aseismic movements instigated from the faults all contribute to high landslide susceptibility in California. In May 2017, the steep slopes at Mud Creek on California’s Big Sur coast collapsed catastrophically. During January and February in 2019, several landslides occurred on the southern part of Santa Monica Mountains. In January 2021, a large debris flow hit the Rat Creek in Big Sur due to extreme precipitation. In addition, a fairly complete collection of remote sensing data and products are available in California. Here we use machine learning methods to refine landslides in California using remote sensing big data, including elevation, slope, and aspect derived from SRTM digital elevation models (DEM), the normalized differential vegetation index (NDVI) derived from Landsat 8 OLI images, the hydrometeorological observations, the nearest distance to rivers and faults, the geological and land cover maps, as well as Synthetic Aperture Radar (SAR) images. We will use the archived landslide inventory for model training and testing. We plan to further explore the critical variables in determining landslide occurrences and the inferred triggering mechanisms.
Sea-ice deformation forecasts for the MOSAiC Arctic drift campaign in the SIDFEx database
Authors: Ludwig Valentin , Goessling Helge ,   SIDFEx Team
Published: March 2022

The Sea Ice Drift Forecast Experiment (SIDFEx) database comprises more than 180,000 forecasts for trajectories of single sea-ice buoys in the Arctic and Antarctic, collected since 2017. SIDFEx is a community effort originating from the Year Of Polar Prediction. Forecasts are provided by various forecast centres and collected, and archived by the Alfred Wegener Institute (AWI). AWI provides a dedicated software package and an interactive online platform for analysing the forecasts. Their lead times range from daily to seasonal scales. Among the buoys targeted by SIDFEx are the buoys of the Distributed Network (DN) array which was deployed during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. In this contribution, we show to what extent the deformation (divergence, shear and vorticity) of the DN can be forecasted by the SIDFEx forecasts. We investigate the performance of single models as well as a consensus forecast which merges the single forecasts to a seamless best-guess forecast. 
Arctic Ocean Heat Content as a Driver of Regional Sea Ice Variability
Authors: Bianco Elena , Iovino Doroteaciro , Materia Stefano , Ruggieri Paolo , Masina Simona
Published: March 2022

The Arctic Ocean is transitioning from permanently ice-covered to seasonally ice-free, with thinner and more dynamic sea ice. This strengthens the coupling with the atmosphere and the ocean, which exert a strong influence on sea ice via thermodynamic and dynamic forcing mechanisms. Short-term predictions are met with the challenge of disentangling the preconditioning processes that regulate sea ice variability, as these often trigger a response that is not uniform in time nor in space.  This study assesses the role of ocean heat content (OHC) as a driver of sea ice variability for five different regions of the Arctic Ocean. We choose to focus on a sub-seasonal time frame, with the goal of investigating whether anomalies in ocean heat content offer a source of predictability for sea ice in the following months and whether this coupling varies across different regions and seasons. To account for the different processes that regulate the Arctic Ocean heat budget, we consider ocean heat content in the mixed layer (OHCML) and in the upper 300 m (OHC300), computed from the CMCC Global Ocean Reanalysis C-GLORSv5 for the period 1979-2017. Time-lagged correlations of linearly detrended anomalies suggest a link between heat content and sea ice variability in the following months. This source of predictability is stronger during the melt season and peaks in autumn, with highest correlations in the Kara and Chukchi regions. Consistent with previous studies, a distinctive response is observed for the Barents Sea, where sea ice is more strongly coupled with the ocean during the freezing season.  Our preliminary results support a central role of OHC as a driver of sea ice thermodynamic changes at sub-seasonal scales, a mechanism that is likely to become stronger under ice-depleted conditions.   
Can ferric iron reduction in paddy soils compensate phosphorus limitation of rice plants and microorganisms?
Authors: Wang Chaoqun , Dippold Michaela , Guggenberger Georg , Dorodnikov Maxim
Published: March 2022

Biogeochemical cycles of phosphorus (P) and iron (Fe) are tightly intertwined, especially in highly weathered and acidic subtropical and tropical soils rich in ferric Fe (Fe(III))oxides. In low-redox and P-deficient paddy soils, the quantitative contribution of the reductive dissolution of Fe(III)-bound P (Fe-P) to the demands of rice plants (Oryza sativa L.) and microorganisms remains unclear. We hypothesized that Fe(III) reductive dissolution can cover the P demand of microorganisms but not of rice plants during the initial growth stages, when P demand is high but the root system is still limited. We grew pre-germinated rice plants for 33 days in flooded rhizoboxes filled with a paddy soil of poor P availability. 32P-labeled orthophosphate sorbed to ferrihydrite (80 kg ha-1) was supplied either (1) in polyamide mesh bags (30 μm mesh size) to prevent roots from directly mobilizing Fe-P (Pellets-mesh bag treatment), or (2) in the form of pellets directly to the soil without mesh bags to enable roots’ accessing the Fe-P (Pellets-no-mesh bag treatment). With the application of Fe-P directly to the soil, P was more available resulting in the increases in microbial biomass carbon (MBC) by 18–55% and nitrogen (MBN) by 4–108% in rooted soil as compared to the pellet not available to roots directly. The maximum enzyme activities (Vmax) of phosphomonoesterase and β-glucosidase followed this pattern. During rice root growth, MBC and microbial biomass phosphorus (MBP) in both rooted and bottom bulk soil gradually decreased by 28–56% and 47–49%, respectively. In contrast to our hypothesis, the contribution of Fe-P to MBP strongly decreased from 4.5% to almost zero during 10–33 days after rice transplantation, while Fe-P compensated up to 16% of the plant P uptake 33 days after rice transplantation, thus outcompeting microorganisms.
Last Glacial Maximum ice shelf retreat and sea-ice dynamics in the Joides Basin, Ross Sea, Antarctica 
Authors: Pambianco Chiara , Capotondi Lucilla , Giglio Federico , Di Roberto Alessio , Belt Simon , Mollenhauer Gesine , Nogarotto Alessio , Tesi Tommaso
Published: March 2022

Here we present preliminary results from the Joides Basin, one of the depressions placed on the continental shelf adjacent to the Ross Ice Shelf (RIS) edge during the Last Glacial Maximum (LGM). We studied a south west – north east transect composed of four gravity cores and one piston core collected along the axis of the Joides Basin in order to reconstruct the past-LGM glacial sedimentary facies and provide new stratigraphic information. A suite of organic biomarkers were used to reconstruct sea-ice conditions and retreat of the RIS during the last termination.

The last glacial termination has been broadly targeted as a potential analogue to current/future global warming, and many studies on this timeframe have been conducted in the RIS, which, with its buttressing effect on continental ice, and its connection to the surrounding marine environment, represents a key element in bridging atmosphere and ocean. The RIS balance and behavior, during rapid climate change, however, is still poorly understood. Many questions are still open regarding the RIS retreat and warming effects on both the atmosphere and ocean, and concerns remain about the reliability of the chronology of marine sediments recovered from this region.

Based on radiocarbon dates of bulk organic carbon and foraminifera, our proposed age model provides new results on the paleo-environmental changes in the Joides Basin as the system moved from an ice-sheet dominated environment to a distal ice-sheet-system. Our preliminary results provide new information to better improve our understanding of the RIS modalities of retreat and the related effects to the surrounding marine and glacio-marine environment during the last deglaciation and Holocene.
Quaternary seismic stratigraphy of the Flemish Bight (southern North Sea): a re-evaluation
Authors: Plets Ruth , De Batist Marc , Missiaen Tine , De Clercq Maikel , Garcia David , Mestdagh Thomas , Versteeg Wim , Fitch Simon , Harding Rachel , Gaffney Vince , Busschers Freek , van Heteren Sytze
Published: March 2022

New high-resolution seismic data (Sparker) and very-high-resolution parametric echosounder (PES) data acquired in an area of the southern North Sea (the Flemish Bight) reveal its Quaternary seismic stratigraphy in unprecedented detail. The identified seismo-stratigraphic units and geomorphological features have been examined with the view to better understand the Quaternary evolution of the southern North Sea.

Seven acoustic units were recognised, including Lower Pleistocene deltaic sediments, Eemian to lower Weichselian shallow marine to coastal (lagoonal) clay-silt-sands, and Holocene coastal peat layers overlain by intertidal and marine sediments. Four erosional events were identified, two of which can be traced as regionally occurring surfaces, and two occurring as localised incisions. Mapping of geomorphological features revealed potential Elsterian moraines in the UK sector, an Elsterian ice-pushed ridge in the Dutch sector and possible permafrost-related structures (probably dating to MIS3).  Seven newly dated peat samples, acquired near a tidal sand ridge known as the Brown Bank from depths between 31 m and 34 m below sea level and dating to between 9.5 and 10.9 cal ka BP, indicate that this area was terrestrial during the early Holocene.

The results form the basis to further improve the regional Quaternary stratigraphic framework of the area, to better understand the region’s (de)glacial history, to enhance sea-level reconstructions and to examine the area’s geographical importance for human occupation during Prehistory.
Magnetosheath jet occurrence in solar wind parameter space
Authors: Plaschke Ferdinand , Koller Florian , Preisser Renteria Luis Federico , LaMoury Adrian T. , Hietala Heli , Temmer Manuela , Roberts Owen Wyn
Published: March 2022

Plasma jets in the magnetosheath are identified as strong local enhancements in dynamic pressure. Being created at the bow shock, they are able to traverse the entire magnetosheath and impact the magnetopause. There, they can severely indent the boundary, set up waves on it, and trigger magnetic reconnection. They are a key yet heavily underexplored element in the solar wind – magnetosphere coupling. Jets are mostly (but not exclusively) observed downstream of the quasi-parallel shock. Consequently, they have been observed significantly more often under low interplanetary magnetic field cone angle conditions.

In this study, we revisit the occurrence of jets, this time taking into account the whole space of parameters of solar wind input conditions. We answer the question where in this space jet occurrences cluster and how the emerging patterns change when the solar wind input becomes significantly different in nature, e.g., under the influence of coronal mass ejections or stream interaction regions.
Modelling Rockfall Source areas and hazard zoning along the Rhine-, Ahr- and Moselle-valleys in the Rhenish Massif, Rhineland-Palatinate, Germany
Authors: Süßer Philip , Hagge-Kubat Teemu , Wehinger Ansgar , Rogall Michael , Enzmann Frieder
Published: March 2022

Rockfall events, due to toppling or sliding rock slope failure are a common phenomenon within the Rhine-, Ahr- and Moselle-valley of the Rhenish Massif. Due to the dense traffic infrastructure, significant cases of damage with far-reaching economic and infrastructural consequences regularly occur in these areas. Therefore, there is a specific need for precautionary risk analysis in order to prevent further damage and to implement preventive measures. The research approach presented here aims to identify rockfall endangered zones for adjacent infrastructure in the valleys. It is assumed, that the main reason for these frequent occurrences are the high number of exposed rock faces and a complex fabric of intersecting foliation-, fracture- and cleavage- networks and faults. By using an index, calculated from the slope and real-surface area of high-definition LIDAR based DEM it is possible to extract areas with exposed rock faces as possible sources for rockfall modelling. To single out which parts of the outcrop are more likely to fail, we compute the aspect of natural occurring outcrops, characteristic of fabric orientations along which failure preferably takes place and pinpoint locations with highly varying directions. These intersection points, representing weakened areas within the outcrops serve as sources for our rock fall models using the Gravitational-Process-Path-Model by Wichmann (2017). Through the precise identification of the rockfall source areas and further input data like vegetation and relief energy numerous cases in the valley were modelled. By intersecting with real infrastructure data, it is possible to carry out risk assessments of specific sections of roads and railway lines. Validation using the mass movement database of the Rhineland-Palatinate Geological Survey and numerous ground checks show, that concrete rockfall events were plausibly simulated.
Xylem sap dynamics of 175-year-old Quercus robur under elevated CO2 at BIFoR FACE, UK
Authors: Quick Susan , Curioni Giulio , Krause Stefan , MacKenzie A. Rob.
Published: March 2022

Recent research highlights the ability of large trees to maintain transpiration during tree water stress, for example in summer dry periods, by using stored plant water held in the relaxed xylem. Use of soil water at different depths by shallow and deep roots according to soil water content may also vary by species and seasonal climatic conditions to maintain transpiration demands. Here we present daylight tree water usage measurements of mature oaks (Quercus robur L.) under future-forest CO2 conditions, derived from compensation heat pulse (HPC) xylem sap flux transducers deployed at Birmingham Institute of Forest Research (BIFoR) Free-Air CO2 Enrichment (FACE) forest in Staffordshire UK. We experienced longer dry periods in summers 2018 and 2019 and variable annual summer precipitation overall.  Xylem sap flux data is collected half-hourly from eighteen oak trees and a smaller number of subdominant trees (Acer pseudoplatanus and Crataegus monogyna) in nine experimental patches: 3 patches with elevated CO2 infrastructure (eCO2); 3 with infrastructure but ambient CO2 (aCO2); and 3 ‘ghosts’ (no treatment, no infrastructure).  Each tree has two probesets, E and W facing; long (7 cm 4-sensor) probes in oak and short (4cm 2-sensor) probes, to accommodate the smaller diameter subdominant trees, are deployed. We compare individual tree responses under the three treatments across the leaf-on seasons for early years of the FACE project 2017–2021. Between-individual within-species variability of summertime monthly average of daily daylight water usage in oak is linearly proportional to tree stem radius (ca. 2.9 litres per millimetre radius, range; 274mm ≥ radius ≤ 465 mm) at the point of probeset insertion ca. 1.1–1.3 m above ground level and oak responds sub-daily to solar radiation reduction events during cloud cover. Diurnal stem sap flux responses to canopy photosynthetic demand typically exhibit increased sap flux from dawn to around midday (UTC) and symmetrical decrease to dusk. We describe our continuing investigation of soil-plant-atmosphere flows, monitoring root-xylem-stomatal changes, and discuss how these results, from our tree-centred forest view, provide valuable new perspectives and help to improve our understanding of future-forest-water use at larger scales, contributing to development of more realistic ecohydrological vegetation, soil and landscape models.
Hydrological Impact Assessment of Climate Change on a Tropical River Basin in Southern India
Authors: Sharma Swatantra Kumar , Sinha Rakesh Kumar , T. I. Eldho
Published: March 2022

The climate change has a significant contribution in the uncertainty in the river flow. In this study, the uncertainty in the river flow of Pamba River Basin (PRB) in South India is investigated due to climate change impacts. In order to assess the hydrological impact in the basin for future preparedness and planning for sustainable use of water resources, an ensemble of five general circulation models (GCMs) and hydrological model SWAT (soil and Water Assessment Tool) were used. The objective of the present study was to understand the surface runoff change over the PRB in the near future (2016-2030) under representative concentration pathways (RCP) 4.5 and 8.5 of the downscaled ensemble GCM data. Furthermore, spatial runoff change at sub-basin scale and percentage runoff change at monthly scale in the PRB were assessed. Hence, to study the impact due to climate change, SWAT model was simulated with base period historical data (1984 – 2015) and future climate data (2016 – 2030), and then changes at spatial and monthly scale were plotted. The results shows that at basin scale, there is an overall increase in the mean runoff by the 1.4 % and 3.0% under RCP4.5 and RCP 8.5 scenarios respectively. At seasonal scale, winter shows a tremendous increase in the runoff with around 38% increase in both RCP 4.5 and RCP 8.5, followed by summer with 17.9% and 18.6% for RCP 4.5 and RCP 8.5 scenarios respectively. Notably, Monsoon witnesses a negative trend in both the scenarios with -18.6% and -15.5% runoff change from the base period. This study will be useful in future water resources management in the basin at micro-level due the spatial and temporal variations.

Keywords: Climate change; SWAT model; GCMs; runoff change; spatial, and temporal change.
A comparison study of process complexity in permafrost dominated regions 
Authors: Bangalore Lakshmiprasad Radhakrishna , Graf Thomas , Zhang Fan , Xiao Xiong , Coon Ethan T
Published: March 2022

The Qinghai-Tibet Plateau (QTP), also known as the “Water tower of Asia”, is threatened by climate warming. Climate warming leads to permafrost degradation, which in turn affects the natural and man-made environment. Permafrost is defined as ground where temperatures remain at or below 0°C for a minimum period of two consecutive years. Near-surface atmospheric processes give rise to seasonal thawing and freezing of permafrost. The thawing promotes groundwater movement because of the increase in liquid water content and hydraulic conductivity. The pore water phase change from ice to liquid also causes variation in the thermal parameters of the soil leading to non-linear coupled processes. Therefore, complex interactions exist between hydraulic and thermal surface and subsurface processes.

Numerical models are useful tools to study coupled processes. Model complexity arises as several physical processes need to be considered, especially due to the presence of permafrost. The amount of input data, parameters, boundary conditions and hence the difficulty increases as the number of physical processes increases. The main aim of this research work is to therefore conduct a comparison study of three modelling scenarios: (i) Coupled subsurface flow and energy transport with ice content, (ii) including coupled surface flow and surface energy balance to scenario (i), (iii) including snow component to scenario (ii). The Advanced Terrestrial Simulator (ATS) and Parameter ESTimation (PEST) codes were applied for simulation and calibration, respectively. The near-surface temperature and moisture measurements from a meteorological station at QTP were used for calibration. Results show that all three models have good agreement with the measurement dataset, however scenario (i) exhibited the best performance in terms of both matching the measured data and representative literature parameter values. Future work will focus on predicting permafrost behavior under various climate change scenarios.
Experimental taphonomy and in-vitro mineralisation of coleoid cranial cartilage at semi-natural conditions.
Authors: Lukeneder Petra , Heinz Petra , Gier Susanne , Lukeneder Alexander , Ottner Franz , Pojar Iulian , Hiden Teresa Elisabeth , Ritschl Helmut , Zuschin Martin , Reishofer Gernot , Tintner-Olifiers Johannes , Sihorsch Petra
Published: March 2022

Squids are an evolutionary-biological success model since the Palaeozoic. The presence of cartilage enables them to a high-speed predatory lifestyle. Although coleoid and vertebrate cartilage are histological very similar, there is no need for in vivo mineralisation in squids. Contrary, its mineralisation in dead specimens under laboratory conditions was investigated several times, but until now taphonomic studies on coleoid cartilage are rare. We present an experimental setting in which we investigate the decay and possible mineralisation processes of coleoid cartilage under semi-natural conditions, using a substrate from the eastern Black Sea, which was collected during the Mare Nigrum Expedition 226. Elemental analysis of the sediment with X-ray fluorescence (XRF) revealed hints for palaeoenvironmental similarities to the deposits of the Late Triassic Polzberg Konservat-Lagerstätte near Lunz am See (Lower Austria, Northern Calcareous Alps), which provides deep insights to the morphology and ecology of the fossil belemnitid Phragmoteuthis bisinuata, including the preservation of soft tissues such as cranial cartilage. Mineralogical composition of the recent sediment was analysed by X-ray diffractometry (XRD) and clay mineral analysis. In a test series, full specimens of the coleoid Loligo vulgaris were buried in the sediment samples for two months. After exhumation of the “fossilised” squid, decay processes will be documented with a strong focus on cephalic cartilage. Possible mineralisation can be determined by the use of XRD and Fourier-Transformation-Infrared-Spectroscopy (FTIR). Stained histological thin sections of Sepia officinalis cranial cartilage before and after the experiment, as well as Magnetic Resonance Tomography (MRI) of two cephalopod specimens (Octopus vulgaris and Loligo vulgaris) and the corresponding reconstructions constitute the dataset for cephalic cartilage morphology and its comparisons to the semi-fossilized cartilages. The fossilisation process will be tested under different environments, while changes in temperature, oxygen saturation and pH-values will be monitored. Associated morphological changes will be quantified with Micro-Computertomography (Micro-CT) and the methods above mentioned.

The obtained data on the decay and preservation in microenvironments of the coleoid carcasses and possible onset of cartilage mineralisation will increase the knowledge on the individual factors that are involved in the fossilisation processes, which lead to exceptional preservation in Konservat-Lagerstätten.
Least-squares-based formulation of deep learning: Theory and applications to geoscience data analytics
Authors: Amiri-Simkooei Alireza
Published: March 2022

As a specific family of machine learning algorithms, deep learning (DL), successfully applied to several application areas is a relatively new and novel methodology receiving much attention. The DL has been widely applied to a series of problems including email filtering, image and speech recognition, and language processing, but is only beginning to impact on geoscience problems. On the other hand, the standard least-squares (SLS) theory of linear models has been widely used in many earth science areas. This theory connects the explanatory variables to the predicted ones, called observations, through a linear(ized) model in which the unknowns of this relation are estimated using the least squares method. The design matrix, containing the explanatory variables of a set of objects, is usually linearly related to the predicted variables. There are however applications that the predicted variables are unknown (nonlinear) functions of explanatory variables, and hence such a design matrix is not known a-priori. We present a methodology that formulates the deep learning problem in the least squares framework of the linear models. As a supervised method, a network is trained to construct an appropriate design matrix, an essential element of the linear model. The entries of this design matrix, as nonlinear functions of the explanatory variables, are trained in an iterative manner using the descent optimization methods. Such a design matrix allows to employ the existing knowledge on the least squares theory to the DL applications. A few examples are presented to demonstrate the theory.
Detrainment and braking of small to medium snow avalanches interacting with forests.
Authors: Védrine Louis , Li Xingyue , Gaume Johan
Published: March 2022

Mountain forests provide natural protection against avalanches. They can both prevent avalanche formation in release zones and reduce avalanche mobility in runout areas. Although the braking effect of forests has been previously explored through global statistical analyses on documented avalanches, little is known about the mechanism of snow detrainment in forests for small and medium avalanches. This study investigates the detrainment and braking of snow avalanches in forested terrain, by performing three-dimensional simulations using the Material Point Method (MPM) and a large strain elastoplastic snow constitutive model based on Critical State Soil Mechanics. First, the snow internal friction is evaluated using existing field measurements based on the detrainment mass, showing the feasibility of the numerical framework and offering a reference case for further exploration of different snow types. Then, we systematically investigate the influence of snow properties and forest parameters on avalanche characteristics. Our results suggest that, for both dry and wet avalanches, the detrainment mass decreases with the square of the avalanche front velocity before it reaches a plateau value. Furthermore, the detrainment mass significantly depends on snow properties. It can be as much as ten times larger for wet snow compared to dry snow. By examining the effect of forest configurations, it is found that forest density and tree diameter have cubic and square relations with the detrainment mass, respectively. Finally, through an energetic and mass study, our results suggest that compared to a regular aligned arrangement, forests with random and regular staggered arrangements have better protective effect. The outcomes of this study may contribute to the development of improved formulations of avalanche-forest interaction models in popular operational simulation tools and thus improve hazard assessment for alpine geophysical mass flows in forested terrain.
Determination of the vertical distribution of hydraulic parameters using gadolinium as an anthropogenic tracer and inverse modelling
Authors: Erlmeier Klaus , Marazuela Miguel Angel , Formentin Giovanni , Bruenjes Robert , Hofmann Thilo
Published: March 2022

Bank filtration is widely used for drinking water production around the world. Due to the general composition of river water and the possibility of direct anthropogenic inputs, it is of great importance to understand the interaction between river and groundwater as well as the subsurface flow conditions. These can alter with increased runoff during flood events. Higher gradients between the surface water and groundwater, enlarged infiltration zones or the removal of colmation layers can lead to elevated infiltration rates and thus to changes in the river aquifer system. Due to often high hydraulic permeabilities and the potential spatial proximity between the river and the extraction system, short dwell times may therefore occur. Additionally, associated with stormwater runoff of wastewater treatment plants, higher contamination risks can therefore be expected in the extraction system during flood events.

In our investigations, we use a regional three-dimensional numerical groundwater model to help prevent changes in the quality of the extracted water through optimized operational management. However, the need to predict the flow paths between the river and the water work with maximum precision makes it necessary to complement the regional model with high resolution local models. To better capture vertical heterogeneities constraining local flow paths, a two-dimensional vertical model following the direction of maximum contribution of bank filtration to the water work was additionally created using FEFLOW 7.5 (DHI). Along this transect, the X-ray contrast agent gadolinium was sampled for use as a conservative anthropogenic tracer at different depths.

The sampling of gadolinium every 12 hours during a minor flood event showed a weekly, wastewater-influenced signal in the surface water, which could also be followed in the transect. This signal, together with 222Rn tracer ages, complements the time-resolved observations of groundwater levels to calibrate the vertical distribution of hydraulic parameters of the two-dimensional mass transport model. These are supposed to improve the conceptual regional model to ultimately optimize the operation of the waterworks and allow the extraction of the groundwater with the best possible quality.
First quantitative constraints on the Pliensbachian-Toarcian warming in polar regions
Authors: Letulle Thomas , Suan Guillaume , Rogov Mikhail , Daëron Mathieu , Vinçon-Laugier Arnauld , Lutikov Oleg , Reynard Bruno , Montagnac Gilles , Lécuyer Christophe
Published: March 2022

One of the most dramatic warming episodes of the Mesozoic occurred near the Pliensbachian-Toarcian transition (Early Jurassic). The occurrence of abundant exotic clasts and glendonites in marine strata of Siberia suggests cold conditions during the late Pliensbachian, which may have led to the episodic growth of high latitude ice-sheets. These conditions ended abruptly during the early Toarcian when temperature rose rapidly across an episode of global biogeochemical perturbation known as the Toarcian Oceanic Anoxic Event (T-OAE). The rapid marine transgression coinciding with the T-OAE onset has been tentatively attributed to the rapid demise of these polar ice-sheets, which possibly released large amounts of methane in the atmosphere through permafrost thawing. Nevertheless, the scarce quantitative estimates of Pliensbachian-Toarcian temperatures have exclusively been obtained from low paleolatitude sites. Plus, existing temperature records are mostly based on oxygen isotope thermometry and hence remain equivocal in the absence of constraints on the ocean oxygen composition of Pliensbachian-Toarcian oceans and its temporal variability. Clumped isotope (Δ47) data from aragonite bivalve shells from one NE Siberian site have recently provided the first quantitative evidence for extreme Toarcian polar warmth, with marine temperature estimates exceeding ~15°C north of the Anabar shield. In this study, we present new Δ47 data from bivalve samples from Tyung River, south of the Anabar shield that allow to substantially expand this record both spatially and temporally. Clumped isotope data from aragonite shells confirm elevated marine temperatures (~13°C) at the end of the T-OAE in polar areas some 850 km away from the previous record. Upper Pliensbachian calcite shells of Harpax collected from coastal to deltaic, boulder-bearing deposits of a nearby site record much lower temperature (~3°C) and extreme 18O-depletion of environmental waters (δ18O = -6.5‰VSMOW). These results provide the first quantitative evidence for near-freezing polar temperatures during the Late Pliensbachian, which is a key prerequisite for the hypothesis of episodic ice-sheet growth prior to the T-OAE. Beyond glacio-eustasy, our new data offer a rare glimpse of extreme changes in polar temperatures across a transition from coldhouse to greenhouse climate and will certainly prove useful for future earth system simulations of Mesozoic climates. 