bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal evolution of sea surface temperatures in the coastal upwelling off North Africa
Authors: Sicre Marie-Alexandrine , Moreno Eva , Klein Vincent , Alves Anna , Puaud Simon
Published: March 2021

This study presents new high-resolution reconstructions of sea surface temperatures (SSTs) obtained from alkenones off the coast of North West Africa between 19 °N and xx 27°N latitude. Sediment grain-size distributions were also generated to provide new information on the Moroccan and Mauritanian upwelling zone over the Industrial Era. Our data shows that over the past two centuries, SSTs gradually increased in the southernmost cores, while in the northernmost sites they show cooling. Changes in sea level pressure and temperature gradients between land and sea would have caused major changes in atmospheric circulation by disrupting and intensifying the system of North-East winds (Trade winds) and southwest Monsoon winds. With global warming, increase in the monsoon might be expected, causing the weakening easterly winds favorable to the formation of upwellings. Enhanced stratification of the water column would prevent upwelling to develop accounting for surface water warming with consequences on the ecosystems and fisheries.
Modeling of pollutant degradation inside 3D reconstructed porous soil structures using plasma technology
Authors: Bali Nadia , Aggelopoulos Christos , Skouras Eugene , Tsakiroglou Christos
Published: March 2021

A Dielectric Barrier Discharge (DBD) plasma reactor is modelled during soil remediation process. In this study we investigate the antibiotic degradation by highly reactive species that are created, when a nanosecond pulse is applied. Antibiotics are lately drawing much attention due to their highly concentration and persistency in soil ground. In addition, antibiotics transport enhances the need for immediate soil remediation. In this study, different soils are computationally reconstructed based on either random stochastic (such as Monte Carlo technique) or grid arrangement algorithms. Monte Carlo technique that is currently used is for randomly generated spheres with the constrain of non-overlapping spheres. On the other hand, structures based on grid arrangements are developed using equally sized spheres, creating structures according to FCC (face center cubic) packing and for the denser structures non-equally sized spheres are used according to HCP (hexagonal close packed). The structures that are regenerated through this process offer 3D computer representations, where plasma physics and mass transport models, using COMSOL Multiphysics® are applied. Emphasis is placed on plasma generation inside porous structures. Parameters such as soil porosity (dense or sparse medium) and electric mobility (characteristic parameter for ionized species transport) are estimated inside multiple soil structures. The models show that soil porosity and mobility do affect the plasma generation inside pores. In addition, during plasma generation (i.e. ionized species creation) the oxidized species that are responsible for antibiotic degradation (for instance Ozon, Nox etc.) are estimated and introduced in a macroscopic model for solving the mass and reaction problem. Pollutant degradation curve is estimated for the case of Ozone, where Ozone species (from plasma model inside porous soil) react with the antibiotic molecules. According to these calculations, antibiotic degradation caused by Ozone species inside the porous soil is estimated at one fifth of the total degradation.
Use eco-physiological modelling to investigate Potassium limitation of wood productivity in tropical eucalypt plantations
Authors: Cornut Ivan , Delpierre Nicolas , Le Maire Guerric , Guillemot Joannès , Nouvellon Yann , Campoe Otavio , Laclau Jean-Paul
Published: March 2021

Potassium (K) is essential for a wide range of physiological functions in plants, and a limiting element for wood productivity in numerous forest ecosystems. However, the contribution of each of the K-sensitive physiological processes to the limitation of wood productivity is poorly known. In trees, K deficiency acts both on the source and the sinks of carbon making it difficult to disentangle its effects on wood productivity. The literature dealing with the influence of K-limitation on tree physiologywhile disparate, shows some converging results. Furthermore, K-limited tropical Eucalyptus plantations have been studied extensively over the last 2 decades. Large scale fertilization experiments, run over multiple rotations, allow us to gain insight into the ecosystem’s K-cycle as a whole and the physiological processes that are impacted the most by K deficiency. Mechanistic modeling of this system should allow us to quantify the relative contribution of each process when it comes to wood productivity limitation by K. We have thus adapted an eco-physiological model (CASTANEA-CNP), previously used in temperate forest settings, to use in tropical eucalypt plantations. This has led us to adapt existing nutrient (N and P) eco-physiological modeling frameworks specifically for K as well as focus on processes that are little impacted by N and P availability but greatly by K availability. The biological K-cycle model was calibrated using the comprehensive experimental data. Carbon and water fluxes were calibrated using data from a flux tower site (Eucflux) with the same environmental conditions as the experimental plots. The development of a new canopy generation model was mandated by both the continuous nature of leaf generation in Eucalyptus grandis and the major interaction between leaf ontogeny and the K-cycle. At first we focus mainly on carbon assimilation at the canopy level. Here we present the preliminary results obtained by this model.
Indian Monsoon Precipitation over Orography: Verification and Enhancement of understanding – Outcomes of the IMPROVE project
Authors: Turner Andrew , Fletcher Jennifer , Hunt Kieran , Phadtare Jayesh , Griffiths Stephen , Ross Andrew , Schiemann Reinhard , Stein Thorwald
Published: March 2021

IMPROVE is motivated by the effects of orography on Indian precipitation as part of the diurnal cycle of convection, contributing to water supply, as well as its role in extreme events.  IMPROVE considers two focal regions.  The Western Ghats, which intercept the monsoon flow across the Arabian Sea, receive some of the most frequent and heaviest rainfall during summer as well as being subject to extremes such as the 2018 Kerala floods.  Meanwhile, the Himalayas play a vital role in separating dry midlatitude flows from tropical airmasses and are subject to extremes during the summer monsoon, as well as in winter due to the passage of western disturbances.  This presentation summarizes the key results of IMPROVE.  Firstly, we examine the impact of orography on the observed convective diurnal cycle and assess its simulation in models at a range of resolutions including convection-permitting scales.  MetUM and WRF model experiments are used to identify key mechanisms and test their capability at simulating scale interactions between forcing at the large scale from the BSISO and newly identified regimes of on- and offshore convection near the Western Ghats.  An additional aspect to this work is the construction of a two-layer analytical model to test the behaviour of sheared flow perpendicular to a ridge analogous to the Western Ghats.  Secondly, the role of orography in extreme events is considered.  For the Western Ghats, this focuses on the interaction between monsoon low-pressure systems and the southwesterly flow in enhancing local rainfall.  For the Himalayas, we focus on characterising interactions between tropical lows and western disturbances in enhancing the orographic precipitation.  The work in IMPROVE works towards a deeper understanding of orographic rainfall and its extremes over India and uncovering why such mechanisms may be poorly represented in models.
Climate change influence on calcification of the bivalve Chamelea gallina in the Adriatic Sea: exploring a temporal gradient from the Holocene to modern days
Authors: Cheli Alessandro , Mancuso Arianna , Prada Fiorella , Baseotto Andrea , Falini Giuseppe , Goffredo Stefano , Scarponi Daniele
Published: March 2021

The Mediterranean striped venus (Chamelea gallina) is a valuable economic species in the Mediterranean Sea. In the last decades the over-exploitation of this fishing resource and the occurrence of several mass mortality events, lead to a strong quantitative decline in clam population density in the Adriatic Sea. Studying the effects of climate-driven changes of environmental factors on C. gallina, therefore, is of increasing interest both from an academic and economic point of view.

Previous studies have mainly focused on population dynamics, shell growth and structure of this species in the present-day Mediterranean Sea. In contrast, there is no information about shell variations in relation to climate-driven environmental change along temporal gradients.

This ongoing study investigates and contrasts variations in shell microstructure and shell growth parameters of C. gallina assemblages from Holocene sedimentary archives of the Northern Adriatic (Italy). Four shoreface-related C. gallina horizons are being evaluated: two from the present-day Adriatic setting and two from the Middle Holocene sedimentary succession of the Adriatic-Po system, when regional sea surface temperatures were higher than today, thus representing a possible analogue for the near-future global warming. Specifically we aim to: 1) determine the life span of selected specimen using three independent ageing methods (shell surface growth rings, shell internal bands and stable isotope composition); 2) determine shell growth parameters and functions concerning linear extension and net calcification rates for each assemblage investigated.

This approach should give access to an archive of ecological responses to past climate transitions and enabling reconstruction of the C. gallina natural range of variability on time-scale well beyond the ecological monitoring or small-scale experiments. Additionally, the young (sub)fossil record should offer insights on the adaptive capacities of C. gallina facing near-future anthropogenic warming and may allow implementation of a more effective management of this economically important bivalve species in the near-future.
Methodological approaches to evaluate dehydrogenase activity as a good indicator of soil functionality.
Authors: Campos Juan Antonio , Moreno Carmen , Villena Jaime , Peco Jesús D. , García-Noguero Eva M. , Moreno Marta M.
Published: March 2021

Dehydrogenase activity (DHA) has been widely used as a good indicator to assess the oxidative status in soils. The common method determination relies on the reduction of an artificial electron receptor by the soil microorganisms, namely, a soluble tetrazolium salt that acquires a red color in its reduced form (formazan), being this way easily measured by colorimetry, after extraction by a proper solvent. This activity is very sensitive to all the factors that can reach the upper layer of soils, especially temperature and moisture, and its use has become very useful to determine the degree of xenobiotics toxicity or the goodness, or not, of agricultural procedures and management. To establish an appropriate methodology for the measurement and monitoring of this activity, in our work we evaluate the most relevant aspects that must be taken into account so that the determination of this activity is as consistent as possible.

Incubation time and pre-incubation: The incubation time appears as the main source of trouble in the interpretation of results. Most of the time, an incubation time of 24 hours is used, but some authors recommend shorter incubation periods to make the measurements at an initial rate and that way use a linear function. For this reason, some authors advise shorter periods of incubation after having a pre-incubation time with glucose or yeast extract. This way the reducing potential of the soil will be better represented.

Soil moisture:  For the DHA results of a certain area to be comparable, the degree of soil humidity has to be necessarily standardized since any change in soil moisture will lead to changes in DHA. Dry soils give figures of DHA close to zero. Precise readings of DHA can only be obtained minimizing the moisture interactions. A pre-incubation of 10 days with the soil hydrated with 50% of the water holding capacity, not only ensures equal moisture for all the samples but also serves to reactivate the soil microorganism population. After that, samples should be immediately incubated with the electron receptor and analyzed.

Formazan extraction: Special physicochemical properties of soils can lead to better or worse extraction of formazan. Some authors advise carrying out a simple trial to establish the degree of extraction of the formazan according to the slope of a linear function between the added formazan and that extracted.

Optimal TTC concentration: Some toxicity of TTC has been raised recently. Although the concentration of the substrate must be sufficient to saturate all the enzymatic capacity, it is advisable not to add an excess of TTC. The quantity and quality of organic matter may be behind the degree of severity of the toxic effect of TTC.
Aligning compound extreme events as defined from climate science and sectoral impact perspectives
Authors: Horton Radley , Keener Victoria , Kornhuber Kai , Lesk Corey , Walsh John
Published: March 2021

This talk will contrast how U.S. decision makers’ impacts-focused perspective on compound extreme events differs from climate science-based perspectives. Examples from around the U.S. will be provided, with an emphasis on cascading impacts that have spanned multiple regions and sectors. The talk will also propose a path forward for synthesizing ‘top-down’ and ‘bottom-up’ approaches to compound extremes, to facilitate adaptation. Time-permitting, preliminary findings from an analysis of sequential humid heat and extreme precipitation over the U.S. may be shown, as a guiding example. The work described reflects a collaboration of scientists funded by NOAA’s Regional Integrated Sciences and Assessments (RISA) program, charged with co-generating ‘useable science’ by working closely with stakeholders.   
The role of forests in securing water for agriculture globally
Authors: Pranindita Agnes , Teuling Adriaan J , Fetzer Ingo , Wang-Erlandsson Lan
Published: March 2021

Forests worldwide supply moisture to downwind precipitation through moisture recycling. Agricultural areas located downwind of forests are, hence, susceptible to changes in precipitation caused by upwind forest changes. In fact, human activities have driven extensive forest cover changes in different parts of the world, in different directions, and at different rates. Nevertheless, the forest-agriculture relationship has yet to be systematically quantified and mapped globally. Previous regional studies in South America show that upwind deforestation of the Amazon forest can reduce downwind precipitation and thus decrease agricultural production. A global coverage analysis of forest-agriculture relationship is therefore necessary to identify other hotspot regions where downwind agriculture relies heavily on upwind forests. In this study, we establish the global source-to-sink relationship between forests and their downwind agriculture by analysing 10 years of high resolution (0.25°x0.25°) ERA5-based moisture flows processed by the UTrack moisture tracking model. We assess the seasonality of the reliance on forests considering the growing season of crops cultivated in the downwind regions. Our study provides a global overview of the cross-sectoral and remote dependence of agriculture on forests globally through moisture recycling.
Green and sustainable plasma-based water pollution control
Authors: Erfani Rasool , Ciric Lena , Erfani Tohid
Published: March 2021

Sustainable urbanisation relies on green infrastructure (GI) for its successful delivery. GI includes a network of environmental features that delivers a range of services including water purification and pollution treatment (WPPT) as measures for health and disease mitigation and adaptation for recovery. Recently wide range of innovative approaches for WPPT are introduced. This study shows how plasma engineering can be considered as a cheap and efficient alternative for WPPT in context of GI. We present, in particular, Dielectric Barrier Discharge Plasma actuator features and its integration in current infrastructure. We investigate its beneficial point of use application for delivery of a promising resilient method in responding to urban public health emergency. In particular, we show how this can be advantageous for pollution control in both city- and catchment-scale studies without reliance on additive chemicals.
Using uncrewed aerial vehicles for wider coverage for geophysical observations
Authors: Envall Jouni , Tanskanen Eija
Published: March 2021

Sodankylä Geophysical Observatory (SGO) has conducted research and provided high quality data series for numerous geophysical disciplines for more than a hundred years. As the next step in developing SGO’s measurement network, we are developing capabilities to operate uncrewed aerial vehicles (UAV’s), which can be equipped with a wide variety of geophysical measurement instruments, such as magnetometers, radars or imaging devices. During the first phase we will build a fleet of multirotor drones with variable characteristics. Any individual aircraft can be optimized for e.g. covering wide areas, covering high altitudes, or lifting heavy instrument payloads. In the next phase the coverage of the measurements will be further expanded by use of fixed-wing aircraft, helium balloons and rockets. In this presentation we will give an overview of the current status of the aircraft and supporting instrumentation. Also, future plans and objectives are discussed.
Ice shelf internal reflection horizons reveal ice provenance, dynamics, surface accumulation and oceanic melt
Authors: Koch Inka , Drews Reinhard , Jansen Daniela , Franke Steven , Visnjevic Vjeran , Eisen Olaf , Oraschewski Falk , Pattyn Frank
Published: March 2021

Ice shelves are widely known to slow the transfer of Antarctic grounded ice to the ocean, especially if their flow is decelerated by local pinning points. Their longevity is influenced by variations in ice dynamics, surface accumulation and oceanic conditions in the ice shelf cavity. This is reflected in the ice shelf structure, which can be characterized by the shape of internal radar reflection horizons.

We aim to map the internal ice shelf stratigraphy of ice shelves, starting with the narrow belt of ice-shelves in the Dronning Maud Land area. The final goal will be to evaluate these as a spatiotemporal archive of ice provenance and ice dynamics. The bulk of the data presented here were collected with AWI’s airborne multi frequency ultra-wideband radar and we combine these new observations with airborne and ground-based radar surveys from previous years. We present a consistent set of internal radar isochrones on a catchment scale for the Roi Baudoin area including the Ragnhild ice streams, the grounding-zone, the iceshelf and multiple ice rises.  Using pattern matching technique we can link isochrones across different ice rises in the area, and hence provide first observational constraints on how ice rises jointly react to changes in atmospheric and oceanographic forcings. We also find a number of interesting features including dynamically induced dips in shear zones, truncating layers at the ice-shelf base, and the development of a meteoric ice layer distinguishing advected from newly accumulated ice in the iceshelf. The time series provided by radar observations over the last 10 years also offers the potential to map temporal changes. We use ice-flow modelling to provide age constraints for some internal layers and delineate portions within the shelf as a function of their advection history, hence marking areas of differing rheologies within the shelf. Taken together, this case study on a catchment scale is a primer to unravel the information stored in the isochronal stratigraphy of coastal Antarctica and contributes to international efforts (e.g., SCAR AntArchitecture)  of mapping stratigraphy on ice sheet scales.
Grassland dynamics of soil moisture and temperature
Authors: Ferraris Stefano , N'Sassila Mesmer , Gentile Alessio , Galvagno Marta , Stevenin Herve , Canone Davide , Previati Maurizio , Bevilacqua Ivan , Gisolo Davide , Painter Kevin
Published: March 2021

Alpine ecosystems are vulnerable to climate and land use changes. Measurement sites at different altitude and aspect can provide precious information on them. Also, vadose rootzone plays a major role in partitioning fluxes. In this work field data of soil water content, matric potential and soil temperature in some mountain grassland sites are compared with simulations results of the CLM model (The Community Land Model, NCAR, US). These are key state variables regulating the physical processes that determine the flows of two main greenhouse gases, water vapour and carbon dioxide, to the atmosphere in the presence of vegetation.

Some transients show significant differences between data and CLM simulation results and further analyses are performed using the HYDRUS model from the US Salinity Laboratory, in order to better explore the soil, grass, and atmosphere roles in the dynamics of those state variables. Some insight is finally provided about the effects on water vapour and carbon dioxide fluxes.
An inventory of dissolved oxygen conditions along the eastern boundary of tropical and subtropical Atlantic: building oxygen monitoring capacity in West African countries, 2013-2019
Authors: Coelho Paulo , Tchipalanga Pedro , Macuéria Marisa , van der Plas Anja , N’Guessan Benjamin , Desiré Kanga , Makaoui Ahmed , Bessa Ismail , Idrissi Mohamed , Ettahiri Omar , Hilmi Karim , Halo Issufo , Schmidtko Sunke , Dengler Marcus , Brandt Peter , Cervantes David , Lødemol Helene , Chierici Melissa , Ostrowski Marek , Bâ Mamadou Lamba ,   WG TOMSWA - Ad-Hoc  Working Group on Transboundary Oxygen Monitoring Status in West Africa
Published: March 2021

Climate change is expected to result in a reduction of oceanic oxygen concentration and an expansion of oxygen-minimum zones (OMZs) in the tropical ocean. Oxygen is perhaps the principal environmental variable influencing habitat and health of fish populations. In West Africa, where rich fisheries are essential for supporting the livelihood of coastal populations, the prospect of expanding hypoxic conditions into fishable coastal shelf waters is a major concern. A transboundary sharing of information on expanding OMZs could provide valuable operational data for fishers and managers, but the capacity for monitoring oxygen conditions at the trans-regional scale is today limited in many countries of the region. Here, we present an inventory of oxygen content in the coastal fringe off West Africa between 30°N and 30°S. Our aim is to present a unified and fisheries relevant information on oxygen water quality along the entire West African continental boundary. The inventory collates the results of recent international expeditions monitoring trans-regional oxygen data over the shelves of West African countries. The EAF Nansen Programme surveys on board the RV Dr Fridtjof Nansen in 2017 and 2019 provided one source such data. During these surveys, scientists representing regional research fisheries institutes carried out observations on dissolved oxygen conditions within their respective exclusive economic zones (EEZ). These data are complemented by oxygen data collected during different international expeditions particularly including research cruises with RV Meteor covering the EEZ of West African countries during 2013-2019. The Meteor results have long established the baseline for Oxygen Minimum Zone (OMZ) monitoring. Our inventory attempts to extend this baseline to cover the coastal West African waters.  In this presentation, we show the distribution of the mean and extreme oxygen conditions in the coastal fringe along the West African continental boundary, provide insight into the seasonal variability across the region, identify data-poor subregions, and discuss potential impacts of the observed oxygen distributions on local ecosystems and fisheries.
The impact of accelerometer calibration approach on estimation of thermospheric density variations 
Authors: Shabanloui Akbar , Flury Jakob , Svitlov Sergiy
Published: March 2021

The environmental non-gravitational accelerations observed by ultra-precise electro-static accelerometers onboard Low Earth Orbiters (LEOs) such as GRACE (FO) and Swarm missions provide a unique opportunity to estimate and monitor the neutral thermospheric density variations. One of main challenge in using such ultra-precise accelerometer observations for thermospheric density application is the calibration approach which delivers the realistic non-gravitational forces acting on satellite surface. The realistic scale factor and bias of accelerometers are estimated during retrieval of Earth’s monthly gravity field solutions.

In this contribution, a realistic accelerometer calibration approach based on Earth’s gravity solutions and precise satellite orbits is introduced and its impacts on neutral thermoshperic density variations for some special periods are investigated. This approach demonstrates the potential of using realistic calibrated ultra-prcise accelerometers for neutral thermospheric density studies.
Monitoring inner shelf sediment transport using fluorescent sand tracers: an example from the south coast of Portugal 
Authors: Cascalho João , Taborda Rui , Rosa Marcos , Garel Erwan , Teixeira Sebastião , Alberto Ana , Drago Teresa
Published: March 2021

The continuous need for beach nourishment requires a detailed understanding of the sediment transport characteristics at the shelf borrow sites, to assess their recovery rate and to evaluate the long-term sustainability of these operations. 

The main objective of this work is to assess sediment transport conditions at an inner shelf borrow site exploited to nourish a beach located at the updrift boundary of the same sedimentary cell (Belharucas, Albufeira, south coast of Portugal).

The work is supported by a sand tracer experiment, where 600 kg of coated sand with fluorescent ink was deposited (August 2020) by divers at 11 m depth (referred to the mean sea level). Periodic sediment sampling using a Van Veen grab was performed using an adaptative sampling grid that accounted for tracer’s dispersion trough time. The samples were washed and dried in laboratory and tagged particles were automatically identified using an automated image analysis procedure based on ultraviolet lighting.

Preliminary results show that sediment transport is dominated by a eastward component,probably related with the energetic events from the SW. Ongoing work relates the tracer’s displacement with ADCP (wave and current) data measured nearby the borrow site during the experiment.

 

The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and ECOEXA project (MAR-01.04.02-FEAMP-0016).

 

 
Neotectonic activity in Lake Sils (Engadine, Switzerland) as trigger of tsunamigenic delta collapses?
Authors: Fabbri Stefano C. , Nigg Valentin , Bellwald Benjamin , Kremer Katrina , Anselmetti Flavio S.
Published: March 2021

Tsunamigenic delta collapses in lacustrine environments are still poorly understood phenomena in terms of their recurrence rate, driving mechanism and hazard potential. A partial collapse of the Isola Delta in Lake Sils (Engadine, Switzerland) with an estimated depositional volume of at least 6.5 million m3 is radiocarbon-dated to 548-797 cal CE and may represent a typical tsunamigenic delta collapse in the Alpine environment. Recent studies propose that this basin-wide tsunami with a run-up height of 2–3 m and an inundation distance of 200 m at the lakeshore highlights the importance to better understand these processes and the associated hazards. The collapse was likely triggered by a strong regional earthquake responsible for several simultaneously triggered mass movements in nearby Lake Silvaplana and Lake Como. Increasingly available datasets from Lake Sils (short cores, high-resolution seismic reflection data, numerical tsunami simulations) are now complemented by multibeam swath bathymetry, providing a high-resolution (1 m grid) model of the lake floor that offers new insights into the failed slope masses, and post-failure basin morphology.

Lake Sils is located in the Upper Engadine in southeastern Switzerland at ~1800 m above sea level and has four major sub-basins (Maloja, Central, Sils & Lagrev Basins). A major tectonic element is the Engadine Fault Line (EFL), an oblique sinistral strike-slip fault that runs along the entire Upper Engadine valley. Its influence on the subaqueous morphology of the Maloja Basin in Lake Sils is expressed in the form of several localized troughs and ridges. It is suspected that the fault also cross-cuts the Isola Delta, possibly causing renewed delta failures in case of reactivation. In fact, recent studies have indicated that there is strong evidence for Quaternary left-lateral transcurrent faulting of the EFL, e.g. offsetting a river gully in the Forno Valley close to Lake Sils.

New bathymetric data from Lake Sils and their morphologic interpretations indicate subaquaeous slope failures, the extent of the Isola Delta collapse, and several trough-ridge features within the southwestern Maloja Basin. The latter are possibly indicative of ongoing faulting in the region since such features strongly suggest rhomboidal pull-apart basins within the Maloja Basin along the EFL. In general, such localized troughs within a lacustrine system are expected to level-out over time due to higher sedimentation rates in preferentially deeper regions of the lake. This study thus highlights the use of high-resolution bathymetric data in identifying the combined effects of deep-seated tectonic zones with shallow lake-floor processes, providing new insights into lacustrine hazard studies.
Three decades of landslide activity in western Nepal: New insights into trends and climate drivers
Authors: Muñoz-Torrero Manchado Alberto , Allen Simon , Ballesteros-Canovas Juan Antonio , Dhakal Amrit , Dhital Megh Raj , Stoffel Markus
Published: March 2021

Landslide activity in the Himalaya region is hypothesized to have increased over the last decades, as suggested by exiting landslide databases and disaster inventories. This trend has been linked to an enhancement of heavy rainfall events under warming climate, but also to anthropogenic factors that influences the slope stability as well as to an increase of exposed of people and infrastructures in prone areas. Yet, as recognized by the Intergovernmental Panel on Climate Change (IPCC), such positive trends are still unclear, mostly due to the lack of baseline data with enough spatio-temporal resolution. Focusing on Far-Western Nepal, we draw on remote sensing techniques to create a multi-temporal regional landslide inventory for the period 1992-2018 over an area covering 6,460 km2. To this end, we systematically interpret geomorphologically high-resolution satellite imagery from Google Earth. Besides, we analyze multispectral differences from Landsat images to interannual date the initiation or reactivation of the interpreted landslides. This massive effort includes the digitalization of 26,350 landslide events, of which 8,778 were dated at an annual scale. These events serve as a basis for the analyses of landslide frequency relationships and trends in relation to annual precipitation and temperature datasets, derived from ERA-5 climate reanalysis.
Our results show a strong correlation between the annual number of shallow landslides and the accumulated monsoon precipitation (r=0.74). Furthermore, warm and dry monsoons followed by especially rainy monsoons produce the highest incidence of shallow landslides (r=0.77). However, we find strong spatial variability in the strength of these relationships, which is linked to recent demographic development in the region. This highlights the role of anthropogenic drivers, and in particular, road cutting and land-use change, in amplifying the seasonal monsoon influence on slope stability. In parallel, the absence of any long-term trends in landslide activity, despite a widely reported increase in landslide disasters, points strongly to increasing exposure of people and infrastructure as the main driver of landslide disasters in this region of Nepal. Thus, our assessment could not determine evidence for any climate change signal related to landslide activity over this part of the Himalayas.
Study of water exchange in Kerch strait using NEMO model of Black Sea
Authors: Sedakov Roman , Bernard Barnier , Molines Jean-Marc , Mershavka Anastasiya
Published: March 2021

The Sea of Azov is a small, shallow, and freshened sea that receives a large freshwater discharge. Under certain external forcing conditions brackish water from the Sea of Azov flow into the north-eastern part of the Black Sea through the narrow Kerch Strait and form a surface-advected buoyant plume. Water flow in the Kerch Strait also regularly occurs in the opposite direction, which results in the spreading of an advected plume of saline and dense water from the Black Sea into the Sea of Azov. Using a regional Black Sea Azov Sea model based on NEMO we study physical mechanisms that govern water exchange through the Kerch Strait and analyze the dependence of its direction and intensity on external forcing conditions. We show that water exchange in the Kerch Strait is governed by a wind-induced barotropic pressure gradient. Water flow through the shallow and narrow Kerch Strait is a one-way process for the majority of the time. Outflow from the Sea of Azov to the Black Sea is induced by moderate and strong northerly winds, while flow into the Sea of Azov from the Black Sea is induced by southerly winds. The direction and intensity of water exchange have wind-governed synoptic and seasonal variability, and they do not depend on the variability of river discharge rate to the Sea of Azov on an intraannual timescale.
New paleomagnetic results obtained in Upper Cretaceous-Paleocene detritic deposits of the North Iberian Meseta
Authors: Villalaín Juan José , Calvín Pablo , Ayarza Puy , Soto Ruth , Calvo Manuel
Published: March 2021

The Iberian microplate and its evolution during the Mesozoic have been in-vogue topics in the field of Geodynamics, because of its location between two of the major tectonic plates, its interaction with both of them, and its significance in relation with the evolution of the western Tethys domain. Geodynamic models of Mesozoic Iberian evolution are based upon the knowledge of the kinematics of the microplate obtained from the ocean floor magnetic anomalies and particularly its apparent polar wander path (APWP) defined by existing paleomagnetic data. In this sense, the most important feature is the anticlockwise 30º-40º rotation that Iberia underwent during the Cretaceous. Nevertheless, there are still uncertainties about the chronology of this movement due to the poor definition of oceanic magnetic anomalies and the scarcity of high-quality paleomagnetic data in the continent. According to recent works, existing paleomagnetic poles are contradictory and inconsistent with the global apparent wander path (GAPWP) and ocean floor anomalies. This is due to the widespread presence of remagnetizations in the Mesozoic basins within Iberia.

To address this question we are starting to develop a new project that aims to obtain new paleomagnetic data from unexplored geological units meeting the necessary condition to obtain new Cretaceous paleomagnetic poles representative of the Iberian plate. In this talk we show new paleomagnetic data from detritic deposits with siliceous cement located at the Duero basin (North Iberian Meseta) ascribed to the upper Cretaceous-Paleocene (Areniscas de Salamanca Formation). A stable paleomagnetic component carried by hematite, showing normal and reversed polarities has been isolated. A stable paleomagnetic component carried by hematite, showing normal and reversed polarities has been isolated. We discuss the primary character of this magnetization in terms of inferring the age of this unit in the frame of the kinematic evolution of the plate.  
A 3-D Model of Antarctic Ice Shelf Surface Hydrology
Authors: Buzzard Sammie , Robel Alex
Published: March 2021

The formation of surface meltwater has been linked with the disintegration of many ice shelves in the Antarctic Peninsula over the last several decades. Despite the importance of surface meltwater production and transport to ice shelf stability, knowledge of these processes is still lacking. Understanding the surface hydrology of ice shelves is an essential first step to reliably project future sea level rise from ice sheet melt.

In order to better understand the processes driving meltwater distribution on ice shelves, we present results from case studies using a new 3-D model of surface hydrology for Antarctic ice shelves. It is the first comprehensive model of surface hydrology to be developed for Antarctic ice shelves, enabling us to incorporate key processes such as the lateral transport of surface meltwater. Recent observations suggest that surface hydrology processes on ice shelves are more complex than previously thought, and that processes such as lateral routing of meltwater across ice shelves, ice shelf flexure and surface debris all play a role in the location and influence of meltwater. Our model allows us to account for these and is calibrated and validated through both remote sensing and field observations. Here we present results from in depth studies from selected ice shelves with significant surface melt features.

This community-driven, open-access model has been developed with input from observations, and allows us to provide new insights into surface meltwater distribution on Antarctica’s ice shelves. This enables us to answer key questions about their past and future evolution under changing atmospheric conditions and vulnerability to meltwater driven hydrofracture and collapse.
Quantifying environmental signal propagation and preservation in ancient sediment routing systems using field data
Authors: Duller Robert , Toby Stephan , De Angelis Silvio , Straub Kyle
Published: March 2021

The assertion that stratigraphy will store environmental signals, such as sediment flux signals related to paleoclimate and tectonics, is debatable because that same stratigraphy can also store signals of autogenic processes that overprint and replace allogenic signals (“shred”). To establish the likelihood that strata will contain allogenic signals, the focus should be on quantifying autogenic processes. Models show that stratigraphic storage of allogenic sediment flux signals will only take place if it exceeds a threshold condition set by autogenic processes. This is supported by experimental and numerical models but its validation is hindered by low spatio-temporal resolution of stratigraphic datasets. We address this by reformulating a theoretical framework that dispenses with the need for exquisite temporal resolution. To demonstrate the applicability of our approach we explore the potential for environmental signal propagation and preservation in two ancient field systems: a small Pleistocene delta in Greece and a larger Eocene sediment routing system in the Spanish Pyrenees. This work demonstrates how short-term system dynamics can be integrated with long-term basin dynamics to provide a framework that assesses the capacity of sedimentary systems to store environmental signals.
Mapping shallow water bubbling reefs – a method comparison between topobathymetric lidar and multibeam echosounder
Authors: Andersen Mikkel Skovgaard , Hansen Lars Øbro , Al-Hamdani Zyad , Hansen Signe Schilling , Niederwieser Manfred , Baran Ramona , Steinbacher Frank , Ernstsen Verner Brandbyge
Published: March 2021

Bubbling reefs are submarine structures formed by aggregating carbonate resulting from leaking gases. The reef formations can form pillars rising several meters above the sea floor. They support a high diversity of benthic communities, and in the EU Habitat Directive they are specifically mentioned as a natural habitat type that require conservation.

Knowledge about the presence, locations and shape of bubbling reefs are usually obtained by geophysical surveying using multibeam echosounder (MBES), sidescan sonar and/or seismic acquisition systems, combined with ground truth verification. However, this traditional survey method is time consuming, especially for full coverage surveys in shallow water. Full coverage surveys are a requirement to capture the bubbling reefs due to their relatively small spatial extent. Besides, traditional geophysical vessel borne surveys have their limitations in shallow water due to low spatial coverage and vessel draft.

In recent years, airborne topobathymetric (green wavelength) lidar has emerged as a new possible surveying method in shallow water (e.g. Andersen et al., 2017). Compared to vessel borne MBES, full coverage lidar surveys can be conducted within hours instead of days/weeks, while also including full coverage in the shallow water and a seamless transition between land and water. Thus, topobathymetric lidar may be a good choice for carrying out full coverage surveys in large shallow water areas. However, the accuracy and the resolution of the collected dataset are important in these surveys, not least when mapping small scale features such as bubbling reefs.

In this study, we investigated the potential of mapping bubbling reefs in shallow water (<10 m) using topobathymetric lidar. The main objective was to assess the performance of airborne topobathymetric lidar to detect and resolve small scale objects, i.e. bubbling reefs, by comparison to MBES data. Both MBES and lidar data were acquired in spring 2019 in a designated Natura 2000 area close to Hirsholmene in the northern Kattegat region in Denmark. The comparison of the two datasets included a quantification of the accuracy, and an assessment of the performance for mapping bubbling reefs.

 

Reference:

Andersen M.S., Gergely A., Al-Hamdani Z., Steinbacher F., Larsen L.R., Ernstsen V.B. (2017). Processing and performance of topobathymetric lidar data for geomorphometric and morphological classification in a high-energy tidal environment. Hydrology and Earth System Sciences, 21: 43-63, DOI: 10.5194/hess-21-43-2017.
Global Instrumental Meteorological Database Before 1890 – a useful overview
Authors: Lundstad Elin , Brugnera Yuri , Brönnimann Stefan
Published: March 2021

This work describes the compilation of global instrumental climate data with a focus on the 18th and early 19th centuries. This database provides early instrumental data recovered for thousands of locations around the world. Instrumental meteorological measurements from periods prior to the start of national weather services are designated “early instrumental data”. Much of the data is taken from repositories we know (GHCN, ISTI, CRUTEM, Berkeley Earth, HISTALP). In addition, many of these stations have not been digitized before. Therefore,  we provide a new global collection of monthly averages of multivariable meteorological parameters before 1890 based on land-based meteorological station data. The product will be form as the most comprehensive global monthly climate data set, encompassing temperature, pressure, and precipitation as ever done. These data will be quality controlled and analyzed with respect to climate variability and they be assimilated into global climate model simulations to provide monthly global reconstructions. The collection has resulted in a completely new database that is uniform, where no interpolations are included. Therefore, we are left with climate reconstruction that becomes very authentic. This compilation will describe the procedure and various challenges we have encountered by creating a unified database that can later be used for e.g. models. It will also describe the strategy for quality control that has been adopted is a sequence of tests.
Short-term response of soil respiration and soil enzymatic activities to biochar application in semiarid agricultural soils under a climate change scenario
Authors: Benavente-Ferraces Iria , Rey Ana , Panettieri Marco , Zaccone Claudio , Gascó Gabriel , García-Gil Juan C. , Plaza César
Published: March 2021

The application of biochar is presumed to be a climate change mitigation strategy in agriculture. However, we still need to better understand the effects of biochar application on soil properties, particularly on soil microbial activity. This is because soil microorganisms play a key role in ecosystems functioning, as they have a central role in soil metabolic activity given that they are responsible for soil organic matter decomposition and nutrient cycling. Conversely, little is known about how climate change will affect the soil microbial activity.

In a rainfed field experiment, we studied the effect of forecasted warming and rainfall reduction on soil respiration and soil enzymatic activities after 3 years of consecutive application of biochar at a rate of 20 t/ha on a barley-camelina-fallow rotation in a semiarid region in Central Spain. Soil respiration was not affected by the application of biochar or/and warming and rainfall reduction treatments in comparison to the control treatment (no amendment). However, biochar amended soils had lower temperature sensitivity of soil C mineralization in the first two years when soils were cultivated but higher temperature sensitivity of soil C mineralization in the third year during fallow treatment. Enzymes involved in the C and N cycles (dehydrogenase, β-glucosidase and urease) significantly increased their activity under warming and rainfall reduction treatments, albeit biochar application tended to decrease the enzymatic activity under those treatments.

Acknowledgments: to the Spanish MICINN (MINECO, AEI, FEDER, EU) for supporting the research projects AGL2016-75762-R and CGL2015-65162-R.
F-UJI : An Automated Tool for the Assessment and Improvement of the FAIRness of Research Data
Authors: Huber Robert , Devaraju Anusuriya
Published: March 2021

Making research data FAIR (Findable, Accessible, Interoperable, and Reusable) is critical to maximizing its impact. However, since the FAIR principles are designed as guidelines and do not specify implementation rules, it is difficult to verify the practice of these principles. Therefore, metrics and associated tools need to be developed to enable the assessment of FAIR compliance of services and datasets. Such practical solutions are important for many stakeholders to assess the quality of data-related services. They are important for selecting such services, but can also be used to iteratively improve data offerings, e.g., as part of FAIR advisory processes. With the increasing number of published datasets and the need to test them repeatedly, there is a growing body of literature that recognizes this importance of automated FAIR assessment tools. Our goal is to contribute to this area of FAIR through the development of an open source tool called F-UJI.  F-UJI supports programmatic FAIR assessment of research data based on a set of core metrics against which the implementation of FAIR principles can be assessed. This paper presents the development and application of F-UJI and the underlying metrics. For each of the metrics, we have designed and implemented practical tests based on existing standards and best practices for research data. The tests are important to our expanded understanding of how to test FAIR metrics in practice that have not been fully addressed in previous work on FAIR data assessment. We demonstrate the use of the tool by assessing several multidisciplinary datasets from selected trusted digital repositories, followed by recommendations for improving the FAIRness of these datasets. We summarize the experience and lessons learned from the development and testing.