bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracing dynamic water uptake and transport from root to canopy by online monitoring of water isotopes in an enclosed tropical forest in response to drought
Authors: Kuehnhammer Kathrin , van Haren Joost , Kuebert Angelika , Dubbert Maren , Ladd Nemiah , Meredith Laura , Werner Christiane , Beyer Matthias
Published: March 2020

Online (or: in situ) methods for measuring soil and plant water isotopes have been identified as an innovative and crucial step to address recently identified issues in studying water uptake using stable isotope techniques.

During a controlled three month drought and rewetting experiment at the Biosphere 2 (B2) enclosed rainforest, a recently developed online method for measuring stem water isotopes (Marshall et al., 2019), namely ‘stem borehole equilibration’, was combined with online monitoring of soil water isotopes and transpired water isotopes as well as sap flow and stem water storage. This enabled us to study root water uptake depths of different tree species and dynamic changes during the dry down and rewetting. After two months of drought, the system was supplied with isotopically labelled water (deuterated water) from down below via a pipe system spanning across the complete B2 rainforest in order to identify deep water uptake of the rainforest trees and hydraulic redistribution.

Results show that – as expected – all monitored trees responded to the drought by changing their root water uptake towards deeper soil depths while sap flow rates of most trees decreased. When rewetting the system, deep water uptake from the base of B2 (between 2.5m and 4m soil depth) was identified in all large, mature trees (Clitoria faichildiana, Hibiscus tilliaceus, Hura crepitans, Pachira aquatica). No deep water uptake was found in the smaller trees (mainly Pachira aquatica). Furthermore, stem water storage was notably different between species and affected their adaptation to drought and response to rewetting. The labelled water was also identified in the transpired water more than one month after re-starting rainfall at B2.  However, no hydraulic redistribution was identified.

The holistic approach for monitoring the interactions of soils and plants provides inevitable insights into the adaptation of (enclosed) rainforests under drought and might have implications for natural rainforests. In particular, the capability of large trees to develop deep roots and the role of stem water storage are important elements for adaptation to climatic changes and need to be studied further under ‘real’ conditions.

References

Marshall, J.D., Cuntz, M., Beyer, M., Dubbert, M., Kühnhammer, K., 2019. Borehole equilibration: testing a new method to monitor the isotopic composition of tree xylem water in situ. Front. Plant Sci.
ARPEGE cloud cover forecast post-processing with convolutional neural network
Authors: Dupuy Florian , Mestre Olivier , Pfitzner Léo
Published: March 2020

Cloud cover is a crucial information for many applications such as planning land observation missions from space. However, cloud cover remains a challenging variable to forecast, and Numerical Weather Prediction (NWP) models suffer from significant biases, hence justifying the use of statistical post-processing techniques. In our application, the ground truth is a gridded cloud cover product derived from satellite observations over Europe, and predictors are spatial fields of various variables produced by ARPEGE (Météo-France global NWP) at the corresponding lead time.

In this study, ARPEGE cloud cover is post-processed using a convolutional neural network (CNN). CNN is the most popular machine learning tool to deal with images. In our case, CNN allows to integrate spatial information contained in NWP outputs. We show that a simple U-Net architecture produces significant improvements over Europe. Compared to the raw ARPEGE forecasts, MAE drops from 25.1 % to 17.8 % and RMSE decreases from 37.0 % to 31.6 %. Considering specific needs for earth observation, special interest was put on forecasts with low cloud cover conditions (< 10 %). For this particular nebulosity class, we show that hit rate jumps from 40.6 to 70.7 (which is the order of magnitude of what can be achieved using classical machine learning algorithms such as random forests) while false alarm decreases from 38.2 to 29.9. This is an excellent result, since improving hit rates by means of random forests usually also results in a slight increase of false alarms.
Assessing nitrous oxide emissions from European peatlands at variable degradation status and land use to improve national GHG inventories
Authors: Lennartz Bernd , Liu Haojie , Wrage Mönnig Nicole
Published: March 2020

Nitrous oxide (N2O) is 300 times more potent than carbon dioxide in atmospheric warming and it is the main driver of stratospheric ozone depletion. The N2O emissions from peatlands are often estimated by applying published IPCC default emission factors, neglecting the stages of peat degradation. Here, we introduce soil bulk density (BD) as a proxy for peat degradation to estimate N2O emissions. A synthesis of soil physical and geochemical data from global boreal and temperate peatlands revealed a strong relationship between BD and annual N2O emissions (R2=0.56, p<0.001), and the BD was superior to other parameters (C/N, pH) in estimating annual N2O emissions. The results indicate that the more a peat soil is degraded, and the larger the values for BD are the larger the risk of N2O emission in peaty landscapes. Even after rewetting, highly degraded soils may exhibit large N2O release rates. A BD distribution map of European peatlands was generated and the estimated annual N2O-N emissions from European peatlands sum up to approximately 46.9 Gg. In conclusion, this research shows that explicitly accounting for the stage of peat degradation as expressed in measured BD values gives reliable N2O emission estimates from peatlands on a national scale.
Modelling slab age and crustal thickness: numerical approaches to drivers of compression in the overriding plate in Andean style subduction zone systems
Authors: Withers Craig , van Hunen Jeroen , Allen Mark
Published: March 2020

The Andes Mountains are formed at a destructive plate margin, where dense oceanic crust descends beneath relatively buoyant continental crust. In this geological setting, we typically would not expect to see such a high and wide mountain belt forming. Numerical modelling shows that if slabs roll back, continents are stretched, causing tension and potentially back-arc extension. The formation of the Andes has been hypothesized to be due to anchoring of the slab in the lower mantle, subduction of buoyant features in the Nazca plate, or compression driven by large-scale convection cells underneath South America.

Previous research suggests a clear correlation between slab age and overriding plate crustal thickness, globally, but in particular for South America. In this project, we hypothesize that this age variation plays a significant role in the formation of the Andes. As subducting slabs descend into the mantle, their properties differ in conjunction with their age affecting their buoyancy and strength, thereby generating different dynamics, surface tectonics, and slab morphologies. Using numerical modelling code ASPECT, we examined the role of slab properties and related dynamics on the state of stress in the overriding plate.

We quantify how much compression occurs in the overriding plate to use as a proxy for topographic growth. Typically, older slabs anchor more readily, causing more rollback and therefore extension. Our models however, predict that a stronger pull force acting on the overriding plate from older slabs causes stronger coupling than their younger counterparts, due to these buoyancy controls and increased density, resulting in greater compression. But, in doing so mantle convection contributes to corner flow in the static mantle wedge, increasing compression further. An increase in overriding plate thickness from 50 to 100km increases the amount of compression in the overriding plate by 10 Mpa , while an increase in slab age from 40 to 80 Myrs generates a similar increase in compression. Finally, slab morphology effects the geometry and vigour of convection cells beneath the overriding plate, which also affects the compressional state of the plate. This is in qualitative agreement with previous work.
The enigma of the Albian Gap: spatial variability and the competition between salt expulsion and extension
Authors: Muniz Pichel Leonardo , Jackson Christopher
Published: March 2020

The Albian Gap is an enigmatic salt-related feature in the Santos Basin, offshore Brazil. It is a uniquely large, up to 65 km wide and >450 km long structure, located in the updip portion of the basin and trending NE (i.e. sub-parallel to the coast). The gap is characterized by the near-complete absence of Albian strata above depleted Aptian salt. Its most remarkable feature is an equivalently large, post-Albian seaward-dipping rollover that is up to 9 km thick. Due to its unique geometry, size, and counter-regional aspect, the Albian Gap has been the centre of debate for >25 years. This debate revolves around two competing models for its origin and evolution; i.e. did it form due to thin-skinned extension, or progradation loading and expulsion? The extension-driven model invokes that the rollover and the Albian Gap formed due to post-Albian gravity-driven extension associated with a large, counter-regional, listric normal fault, the Cabo Frio Fault. Conversely, the expulsion-driven hypothesis suggests that the Albian Gap was established earlier, during the Albian, and that post-Albian deformation was controlled by differential loading, vertical subsidence, and basinward salt expulsion without significant lateral extension. This study utilizes a large (c. 76,000 km2) and dense depth-migrated, 2D seismic dataset that covers and which thus permit a detailed, 3D structural analysis of the entire Albian Gap, focusing on i) base-salt relief and original salt thickness variations and ii) the geometry of the post-Albian rollover, and its related faults and salt structures. We also apply novel structural restoration workflows incorporating flexural isostasy, along with a detailed sequential reconstruction of the rollover sequences, to constrain the kinematics of the Albian Gap, and how this relates to base-salt relief. Our results show that the geometry and kinematics of the Albian Gap vary along-strike and that both post-Albian extension and expulsion play a significant role on its evolution. Seaward-dipping growth wedges, salt rollers and normal listric faults evidence extension, whereas sigmoidal wedges, halokinetic sequences, and upturned near-diapir flaps, the latter two associated with inflated diapirs bounding the downdip edge of the gap, indicate basinward salt expulsion and inflation. Where the Albian gap is relatively wide (>50 km), these processes alternate and operate at approximately equal proportions. Our results are consistent with the observed amount of basinward translation further downdip within ramp basins in the Sao Paulo Plateau and seemingly reconciles one of the longest-running debates in salt tectonics. Our results have implications for understanding the regional kinematics and dynamics of salt-related structures in other salt basins, in particular, the controls on the development of large, salt-detached, counter-regional faults.
European Standard Loess as baseline for paleoenvironmental interpretations of loess granulometric variations
Authors: Schulte Philipp , Sprafke Tobias , Lehmkuhl Frank
Published: March 2020

Loess-paleosol sequences are sensitive terrestrial archives of Quaternary aeolian dynamics and paleoclimatic changes. Loess is predominantly formed during glacial periods, whereas soils form during interglacials and interstadials, when dust sedimentation is reduced or absent. Common grain size (GS) based proxies used in loess research mainly reconstruct past sedimentation dynamics. However, the GS distribution of a loess sample is not solely a function of aeolian dynamics; rather complex polygenetic depositional and post-depositional processes must be taken into account.

Here we integrate GS data of primary loess samples from 14 profiles in Europe as baseline to identify and quantify the imprint of local paleoenvironments on GS distribution along vertical loess sections. Our GS data are measured by the same laser diffraction device (Beckmann Coulter LS13320) and available in the database of the Physical Geography laboratory at the RWTH Aachen University. Based on a catalogue of criteria, samples with least signs of weathering and reworking (e.g. low GS mean and good sorting, low magnetic susceptibility, low geochemical weathering proxies) are defined as primary loess of the studied loess sections. GS distributions of these loess samples show little variation, both within individual profiles (temporal) and in a supra-regional comparison (spatial). We calculate an averaged loess sample and interpret it as baseline loess or European Standard Loess. We discuss the significance of deviations from this standard loess related to different geomorphological conditions during deposition and later pedogenetic processes.
AlterEco: An Alternative Framework to Assess Marine Ecosystem Functioning in Shelf Seas
Authors: Palmer Matthew R. , Williams Charlotte , Akpinar Anil , Mahaffey Claire , Hull Tom , Toberman Matt
Published: March 2020

A recognized global increase in the extent of shelf sea and coastal oxygen deficiency calls for an urgent need to increase the spatial and temporal measurement of oxygen and a better understanding of the processes that lead to oxygen deficiency. This need is severely impeded by the natural complexity of ecosystem functioning, the impact of a changing climate, connectivity between different regions of our shelf seas and large-scale external forcing from ocean and atmosphere. Currently, methods are severely restricted in resolving this complexity due to poor resolution in observational coverage, which calls for the development of new strategies for observing and monitoring marine ecosystem and environmental status to better enable national and regional assessments.

AlterEco is a UK based project that has been jointly funded by academic and government agencies and the WWF to address this challenge using a novel monitoring framework to deliver improved understanding of key shelf sea ecosystem drivers. This framework capitalizes on recent UK investments in marine autonomous vehicles, such as ocean gliders and wave-driven surface vehicles, and state-of-the-art chemical sensors to investigate the physical and biogeochemical functioning in the North Sea from autumn 2017 to spring 2019. The chosen area is known to undergo variable physical, chemical and biological conditioning and includes areas previously identified to experience seasonal bottom layer oxygen depletion. We will present analysis of the effectiveness of the chosen framework to meet assessments of good environmental status and will discuss the global transferability of this approach.
Towards reproducing seismic interpretation uncertainties using open-source stochastic geomodeling in Python
Authors: Schaaf Alexander , de la Varga Miguel , Bond Clare E. , Wellmann Florian
Published: March 2020

Seismic data plays a key role in developing our understanding of the subsurface by providing 2-D and 3-D indirect imaging. But the resulting data needs to be interpreted by specialists using time-intensive, error-prone and subjective manual labour. While the automation of data classification using Machine Learning algorithms is starting to show promising results in areas of good data quality, the classification of noisy and ambiguous data will continue to require geological reasoning for the foreseeable future. In Schaaf & Bond (2019) we provided a first quantification of the uncertainties involved in the structural interpretation of a 3-D seismic volume by analysing 78 student interpretations of the Gullfaks field in the northern North Sea. Our work also concretized the question of to which degree the seismic data itself could provide useful information towards a prediction of interpretation uncertainty.

We now look at the same dataset in an effort to answer the question if we can adequately reproduce the observed interpretation uncertainties by approximating them as aleatoric uncertainties in a stochastic geomodeling framework. For this we make use of the Python-based open-source 3-D implicit structural geomodeling software GemPy to leverage open-source probabilistic programming frameworks and to allow for scientific reproducibility of our results. We identify potential shortcomings of collapsing interpretation uncertainties into aleatoric uncertainties and present ideas on how to improve stochastic parametrization based on the seismic data at hand.

 

Schaaf, A., & Bond, C. E. (2019). Quantification of uncertainty in 3-D seismic interpretation: Implications for deterministic and stochastic geomodeling and machine learning. Solid Earth, 10(4), 1049–1061. https://doi.org/10.5194/se-10-1049-2019
Recent Advances in Galileo and BeiDou Precise Orbit Determination
Authors: Dilssner Florian , Schönemann Erik , Mayer Volker , Springer Tim , Gonzalez Francisco , Enderle Werner
Published: March 2020

To produce Global Navigation Satellite System (GNSS) orbits and clocks with high accuracy and for all constellations, the ESA’s Navigation Support Office (NSO) continually strives to keep abreast and improve its precise orbit determination (POD) strategies. In this presentation, we report on NSO’s recent developments and progress in Galileo and BeiDou POD. We first discuss the approach of improving Galileo POD solutions through a prudent combination of radiometric and satellite laser ranging (SLR) measurements at the observation level. For this technique to be effective, SLR normal point (NP) data from the Galileo SUCCESS campaign are used. Launched by the European Laser Network (EUROLAS) in the middle of May 2019, this three-week tracking campaign provided over 1000 NPs for two selected Galileo spacecraft: GSAT0102 and GSAT0220. We show that the precision of the GSAT0102 and GSAT0220 orbits is more than 10 percent better than that produced by solutions without SLR data. In this performance evaluation, we also discuss the presence of station-specific SLR biases, taking advantage of near-simultaneous SLR tracking by two or three separate laser sites. Additionally, we demonstrate that the SLR full-rate data from a single kHz laser system can be used to determine the Galileo satellites’ yaw state during eclipse maneuvers. This approach takes advantage of the 1.0 m distance between a Galileo spacecraft’s laser retroreflector array (LRA) and rotation axis to estimate the yaw angle in a recursive least-squares algorithm epoch by epoch. The method may serve as an interesting alternative to reverse kinematic point positioning (RPP), particularly for LRA-equipped satellites without significant transmit antenna phase center offsets. Finally, we present the first centimeter-quality orbit solutions for BeiDou’s third-generation series of medium Earth orbit (MEO) spacecraft. We discuss the POD strategy underlying these orbits and evaluate its performance by way of several metrics including laser range residuals, day-to-day orbit overlaps, satellite clock residuals, as well as RPP estimates as measure for the attitude model accuracy. Challenges pertaining to the satellite antenna phase center and radiation force modeling are addressed. The results on the overlap and SLR residuals suggest that our BeiDou-3 MEO orbits are accurate to better than 5 cm in all three components. Therefore, the new BeiDou constellation is fully integrated into our operational multi-GNSS routine, bringing the total number of daily processed GNSS satellites to more than 110 (http://navigation-office.esa.int/products/gnss-products).
Probabilistic constraints on lithospheric forces, fault tractions, and rheology in the eastern Mediterranean region
Authors: Herman Matthew , Govers Rob , van de Wiel Lukas , Nijholt Nicolai
Published: March 2020

The Aegean Sea region sits in a complex deformation zone between the African, Eurasian, and Anatolian plates. It contains the Hellenic subduction zone, where African oceanic lithosphere descends under the Aegean Sea. The subducting slab may be torn or fragmented at both its eastern (Pliny-Strabo zone) and western (Kefalonia fault) edges. The overriding Aegean Sea is cut by numerous active normal faults accommodating north-south extension. On top of this, the collision of Arabia with Anatolia farther east drives Anatolia and the connected Aegean Sea westward, resulting in the left lateral North Anatolian fault (and its extension into the Aegean), as well as greater relative velocities between the subducting slab and the overriding plate. These geodynamic processes and geological features all affect the present-day kinematics of the Aegean region.

Surface velocities measured at Global Navigation Satellite System stations throughout the Aegean provide important constraints on these underlying geodynamic forces. Previous studies have attributed the surface motions to some combination of plate boundary interactions, lateral variations in gravitational potential energy (GPE), subduction and slab tearing, internal faulting, and mantle tractions. The expected imprint of these processes also varies with the rheology of the lithosphere. Up to this point, there has been little effort to systematically evaluate the relative contributions of these different forces. In this study, we implement a Markov Chain Monte Carlo approach to efficiently and precisely determine the likely values and uncertainties of these geodynamic forces and the lithospheric rheology. We also identify trade-offs between processes that produce similar surface signals.

Preliminary results indicate that the dominant imprint on surface velocities comes from the southwestward rollback of the Hellenic slab and the westward escape of Anatolia. Although lateral variations in GPE also have an effect on the velocities, these are generally less important than slab rollback and Anatolian escape. At a lithospheric scale, the North Anatolian fault has little shear resistance to allow a relatively sharp velocity transition across it. Including resistive tractions on intraplate faults within the Aegean Sea has a smaller effect on the modeled velocity field. By using the velocity field to guide a statistical analysis of the geodynamic drivers, we have been able to better constrain the primary drivers of deformation in the eastern Mediterranean.
Quantification of past temperature variability during the last 36 kyr using organic-derived proxies in the Padul wetland, southern Iberia
Authors: Rodrigo-Gámiz Marta , García-Alix Antonio , Jiménez-Moreno Gonzalo , Camuera Jon , Ramos-Román María J. , Torney Jaime L. , Sachse Dirk , Anderson R. Scott
Published: March 2020

The study of climate variability in especially sensitive areas is crucial for a better understanding of the response of Earth’s different components to abrupt changes and envisage future climate responses. In this regard, the southern Iberian and western Mediterranean regions have demonstrated hemispheric-scale teleconnections during the last glacial period. Long-records from continental sedimentary archives are scarce, and the Padul wetland represents one of the longest and most continuous continental record in this area, detecting climate variability at centennial to millennial-scale from the Pleistocene to the Holocene. The applicability of organic-based proxies in this organic rich continental archive is a promising tool because the variations in different biomarkers are closely related to biological sources and environmental factors such as temperature. Particularly interesting from a paleoclimatic point of view are glycerol dialkyl glycerol tetraethers (GDGTs), which are membrane lipids from Bacteria and Archaea, ubiquitous in a range of natural archives, including wetlands. Previous works have demonstrated their applicability as a significant past continental air temperature proxy, where the distribution of bacterial branched GDGTs (brGDGTs) is correlated with mean annual air temperature (MAAT) and soil pH. Here we present a first quantification of past temperatures using brGDGTs in the Padul sedimentary record. Preliminary results have evidenced substantial variations in derived-MAAT and distribution of the different brGDGTs during the last 36 kyr that are consistent with abrupt climate periods, such as Henrich Stadial 1 and the Holocene onset. Nevertheless, different absolute MAAT values using the peat-specific calibration and the mineral soil calibration have been obtained and they need to be evaluated.
Investigation of inter-annual and seasonal variations of the Martian convective PBL by GCM simulations
Authors: Senel Cem Berk , Temel Orkun , Porchetta Sara , Sert Hakan , Karatekin Ozgur , van Beeck Jeroen
Published: March 2020

The Martian planetary boundary layer (PBL) is an important component of the Martian climate. It is the lowest portion of the atmosphere where the strong buoyant and shear forces influence the interaction between surface and atmosphere [1]. The Martian PBL exhibits extreme events compared to the Earth's PBL, such as global dust storms, local dust devils, turbulent gusts and strong updraughts. Due to the thinner atmosphere of Mars and lower surface thermal inertia, the Martian planetary boundary layer shows stronger diurnal variations compared to its terrestrial counterpart. Moreover, as a result of the thinner atmosphere, radiative heat forcing is stronger, such that the Martian planetary boundary layer height can reach up to 10 km. Radiative forcing on Mars is affected by the atmospheric cycles, i.e. CO2, water and dust cycles. In this study, we perform GCM simulations, using dust climatologies corresponding to the last 10 Mars years and present the inter-annual and seasonal variations in the planetary boundary layer height, mixed-layer potential temperature, convective velocity scale, friction velocity and Richardson number. To perform these GCM simulations, the Mars version of planetWRF (MarsWRF) model [2] is utilized, that solves the fully-compressible, non-hydrostatic Euler equations in a finite difference framework.

[1] Hinson, D. P., Pätzold, M., Tellmann, S., Häusler, B., & Tyler, G. L. (2008). The depth of the convective boundary layer on Mars. Icarus, 198(1), 57-66.

[2] Richardson, M. I., Toigo, A. D., & Newman, C. E. (2007). PlanetWRF: A general purpose, local to global numerical model for planetary atmospheric and climate dynamics. Journal of Geophysical Research: Planets, 112(E9).
Copernicus Sectoral Information System for the Biodiversity Sector
Authors: De Ridder Koen , Lefebre Filip , Vanuytrecht Eline , Berckmans Julie , Wouters Hendrik
Published: March 2020

Biodiversity is increasingly under pressure from climate change, which affects the habitat suitability for species as well as the efficiency of ecosystem services. Management of these issues, for instance through ecosystem restoration or species dispersal measures, is often hindered by a lack of appropriate information about (future) climate conditions.  To address this, an operational Sectoral Information System (SIS) for the Biodiversity sector (SIS Biodiversity) is designed within the Copernicus programme Climate Change Service (C3S). This new SIS provides tailored bio-climatic indicators and applications, and delivers novel evidence regarding impacts of past, present and future climate. As such, it provides support to decision making challenges that are currently facing unmet climate data needs.
 
The new climate service for SIS Biodiversity will be demonstrated, including the outline, workflow and outcomes of the use cases. The service is built upon the Copernicus Data Store platform (CDS; ), and takes into account (1) the barriers in ongoing bio-climate assessments and (2) the user requirements of diverse stakeholders (e.g. researcher institutes, local NGO’s, the International Union for Conservation of Nature and Natural Resources (IUCN),…). These have been collected during workshops and bilateral meetings in 2019. A common barrier is the lack of reliable and high-resolution information about states and dynamics of the soil, sea, ice and air for the past and the future climate. Therefore, the service provides relevant bio-climatic indicators on the basis of a wealth of available variables from the latest ERA5 reanalysis datasets and the CMIP5 global climate projections available in CDS. In order to provide information at high resolution and minimize inconsistencies between observed and modelled variables, different downscaling and bias-correction techniques are applied. A common requirement is a universal and flexible interface to the bio-climatic indicators in an easy-to-use and coherent platform that is applicable for different fauna and flora species of interest. Therefore, different applications have been developed within CDS for generating bio-climate suitability envelopes from the high-resolution indicators and to evaluate climate suitability and impacts for the species under present and future climate. Finally, the service is currently tested and refined on the basis of specific use cases. Special attention is given to their transferability to other global and topical studies, hence maximizing external user uptake throughout existing research and policy networks.
Fire-vegetation feedbacks in JULES-INFERNO
Authors: Burton Chantelle , Betts Richard , Jones Chris , Kelley Douglas
Published: March 2020

Fire has an important impact on the terrestrial carbon cycle, affecting the growth and distribution of vegetation, and altering carbon stores in vegetation and soils. This is further complicated by the interaction with people, through land-use change, ignitions and fire management. This work presents the latest results from the recently coupled JULES-INFERNO fire enabled land surface model, and the interaction of fire, dynamic vegetation and varying land use. The results of historical and present-day global simulations are evaluated using observations of burned area and emissions, and through use of tools such as ilamb. The model performs well globally compared to observations, and improves the simulation of vegetation especially in the tropics. The model is also used to address how fire may change under different climate scenarios, including El Niño events, and future simulations of climate change. Results show that burned area increases in some areas with El Niño conditions such as those of 2015/16, especially in South America where a 13% increase in burned area and emitted carbon is simulated. This negatively impacts carbon uptake in this region, and reduces the terrestrial carbon sink.
Multi-method approach combining isotopic tracers, anthropogenic contaminants and mapping to retrace socio-environmental trajectories of groundwater-dependent coastal hydrosystems
Authors: Erostate Melanie , Huneau Frederic , Garel Emilie , Pasqualini Vanina
Published: March 2020

Coastal lagoons are unique and complex ecosystems. Resulting from both terrestrial (fresh groundwater and surface water) and marine water inﬂuences, these ecosystems are often maintained by direct or indirect groundwater supplies and collectively known as groundwater dependent ecosystems (GDEs). Because they provide a wide range of ecosystem goods and services on which a large part of the human population depends, coastal GDEs are considered as complex socio-economic and ecological component worldwide. The increasing human development in coastal areas induces yet a strong pressure on water resources and the expected effects of climate change could exacerbate the pressures on these environments. To limit the risks of degradation and to ensure the sustainability of ecosystem services, the implementation of proper water resources management strategies is essential. This requires a strong knowledge of the environmental and socio-economic trajectories of hydrosystems, and particularly of the behavior and role of groundwater.

To this end, only the combined use of several tools allows a global understanding of the spatial and temporal dynamics of the system. The correlation between isotopic tracers (18O, 2H, 3H, 15N, 11B), anthropogenic contaminants (organic micro pollutants) and mapping approaches (land-use and vulnerability) allows a historical analyze of the hydrosystem. In addition, to better constraint the hydrosystem hydrological behavior, it is also possible to highlight the current status of water resources, the historical legacy of pollutants and the consequences of past developments and practices, which continue to jeopardize the current quality of the water resource. This methodology was applied to a Mediterranean hydrosystem, in connection with a coastal lagoon (Corsica Island, France). The identification of degradation processes and their chronology could then be traced back in time.

It appears that the current deterioration is mainly due to a legacy pollution resulting from the development of policies implemented 60 years earlier. In the case of coastal GDEs that are highly anthropized and subject to ever-increasing development, this methodology proposes new key elements for the establishment of relevant management strategies to ensure the future sustainability of water resources.
Fault stressing in the overriding plate due to megathrust coupling along the Nankai trough, Japan
Authors: Hashima Akinori , Sato Hiroshi , Ishiyama Tatsuya , Freed Andrew , Becker Thorsten
Published: March 2020

The Nankai trough has hosted ~M8 interplate earthquakes with the interval of 100-200 years. The crustal activity in southwest (SW) Japan in the overriding plate was relatively quiet after the last coupled megathrust ruptures occurred in 1944 and 1946. In the recent 20 years, however, SW Japan has experienced ~M7 earthquakes such as the 2016 Kumamoto earthquake. Similar activation of crustal earthquakes in the later stage of the megathrust earthquake cycles can be found in the historical earthquake occurrence based on paleographical studies. Such a change cannot be resolved by the probabilistic approaches, which usually rely on paleo-seismological data on longer timescales. Here, we show a deterministic way to quantify the current stressing state on the source faults due to megathrust coupling at the Nankai trough, making use of the data captured by the dense, modern geodetic network in Japan.

We constructed a 3-D finite element model (FEM) around the Japanese islands including the viscoelastic feature in the asthenosphere. The geometry of plate boundary on the Philippine Sea slab is based on earthquake distributions determined by the previous studies. In particular, the bended geometry at the junction of the Nankai trough and the Ryukyu trench is crucial for calculating stress. The plate boundary is divided into 8 x 27 patches to generate Green’s functions. The model region is divided into about 1000,000 tetrahedral elements with dimension of 5-100 km. We revised the source fault model by the Headquarters for Earthquake Research Promotion based on recent geophysical and geological data and added new faults in the Sea of Japan.

Our inter-seismic inversion suggests ~8 cm/year slip-rate deficit, which is consistent with the previous studies. Using the slip distribution, we calculate stressing rates on the source faults over SW Japan. In particular, positive Coulomb stressing rate on the source faults of the 2016 Kumamoto earthquake and the other M7 earthquakes is consistent with their occurrence. The crustal earthquakes before the 1944 and 1946 megathrust events also occurred in the region with source faults with positive Coulomb stressing rate.
Flank instability of coastal and ocean island volcanoes: Why it is not enough to look at the tip of the iceberg
Authors: Urlaub Morelia
Published: March 2020

Volcanoes are among the most rapidly growing geological structures on Earth. Consequently, their edifices suffer structural instability that may result in lateral flank collapses, such as the 1980 Mt St Helens event or the 2018 collapse of Anak Krakatau (Indonesia). The seafloor displays the geological remnants of collapses of nearly all ocean island volcanoes, including Hawaii and the Canary Islands. Such collapses and their associated tsunamis are among the largest and most disastrous natural processes on Earth, because of the enormous energy involved. Numerous coastal and ocean island volcanoes worldwide show signs of flank instability, documented by ground deformation measurements. However, it is difficult to evaluate their hazard potential mainly due to a lack of understanding of the causes of collapse. For coastal and ocean island volcanoes, most research and the vast majority of monitoring activities are biased towards the often comparatively small part of the volcano above sea level, while the largest part of the volcanic edifice is typically submerged in water. Using the example of Mount Etna (Italy) as well as several other case studies, I demonstrate that shoreline crossing analyses of volcano-tectonic structures and edifice deformation are necessary for understanding the mechanisms that control the volcano’s structural stability. I further argue that the earliest and most important precursory signals for imminent edifice collapse may occur below sea level. Data acquisition and monitoring in the deep sea is technologically and logistically challenging, but possible. It significantly extends onshore data sets with the potential to revolutionise our current understanding and hazard monitoring.
Particle Induced X-ray Emission at Mercury and the Moon.
Authors: Grande Manuel , Cooper Rose
Published: March 2020

Mercury and the Moon are examples of terrestrial bodies which lack an atmosphere and therefore have surfaces which interact directly with the space environment. Thus the surfaces can be reprocessed by plasma impact, and in the process can emit X-rays via the Particle Induced X-ray Emission (PIXE) process. We will present and review existing measurements, particularly from SMART-1 and Chandrayaan at the Moon, and Messenger and Mercury, in order to predict opportunities for new science at Mercury by BepiColumbo. We will present predictions of PIXE signals from different regions of the Mercury surface, and examine the possibility of using the signal for direct diagnosis of particle interactions with the surface. These include the auroral signatures of substorm like behaviour, and interactions with coronal mass ejections.
The tipping points of Pine Island Glacier, West Antarctica
Authors: Rosier Sebastian , Reese Ronja , Donges Jonathan , De Rydt Jan , Gudmundsson Hilmar , Winkelmann Ricarda
Published: March 2020

Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Central to this is the marine ice sheet instability: once a critical threshold, or tipping point, is crossed, ice-internal dynamics can drive a self-amplifying retreat committing a glacier to substantial ice loss that is irreversible at time scales most relevant to human societies. This process might have already been triggered in the Amundsen Sea region, where Pine Island and Thwaites glaciers dominate the current mass loss from Antarctica. However, current modelling and observational techniques have not been able to establish this rigorously, leading to divergent views on the future mass loss of the West Antarctic Ice Sheet. Here we aim at closing this knowledge gap by conducting a systematic investigation of the tipping points of Pine Island Glacier using established early warning indicators that detect critical slowing as a system approaches a tipping point. We are thereby able to identify three distinct tipping points in response to increases in ocean-induced melt. The third and final event, triggered for less than a tripling of melt rates, leads to a retreat of the entire glacier that could initiate a collapse of the West Antarctic Ice Sheet.
Impacts of Aerosol Concentration Variability on Turbulence in Convective Low Level Mixed-phase Clouds in the Arctic
Authors: Chylik Jan , Mertes Stephan , Neggers Roel
Published: March 2020

Arctic mixed-phase clouds are still not properly represented in weather forecast and climate models. Recent field campaigns in the Arctic have successfully probed low level mixed-phase clouds, however it remains difficult to gain understanding of this complex system from observational datasets alone. Complementary high-resolution simulations, properly constrained by relevant measurements, can serve as a virtual laboratory that provides a deeper insight into a developing boundary layer in the Arctic.

Our study focus on the impact of variability in cloud condensation nuclei (CCN) concentrations on the turbulence in Arctic mixed-phase clouds. Large-Eddy Simulations of convective mixed-phase clouds over open water were performed as observed during the ACLOUD campaign, which took place in Fram Strait west of Svalbard in May and June 2017. The Dutch Atmospheric Large Eddy Simulation (DALES) is used including a well-established double-moment mixed-phase microphysics scheme of Seifert & Beheng.

The results highlight various impact mechanisms of CCN on the boundary layer thermodynamic state, turbulence, and clouds. Lower CCN concentrations generally lead to decreased turbulence near the cloud top. However, they can also enhance the turbulence in the lower part of the boundary layer due to increased amount of sublimation of ice hydrometeors. Further implications for the role of mixed-phase clouds in the Arctic Amplification will be discussed.
Selection and integration of Earth Observation-based data for an operational disease forecasting system
Authors: Ainscoe Eleanor A , Hofmann Barbara , Colon Felipe , Ferrario Iacopo , Harpham Quillon , James Samuel JW , Lumbroso Darren , Malde Sajni , Moschini Francesca , Tsarouchi Gina
Published: March 2020

The current increase in the volume and quality of Earth Observation (EO) data being collected by satellites offers the potential to contribute to applications across a wide range of scientific domains. It is well established that there are correlations between characteristics that can be derived from EO satellite data, such as land surface temperature or land cover, and the incidence of some diseases. Thanks to the reliable frequent acquisition and rapid distribution of EO data it is now possible for this field to progress from using EO in retrospective analyses of historical disease case counts to using it in operational forecasting systems.

However, bringing together EO-based and non-EO-based datasets, as is required for disease forecasting and many other fields, requires carefully designed data selection, formatting and integration processes. Similarly, it requires careful communication between collaborators to ensure that the priorities of that design process match the requirements of the application.

Here we will present work from the D-MOSS (Dengue forecasting MOdel Satellite-based System) project. D-MOSS is a dengue fever early warning system for South and South East Asia that will allow public health authorities to identify areas at high risk of disease epidemics before an outbreak occurs in order to target resources to reduce spreading of epidemics and improve disease control. The D-MOSS system uses EO, meteorological and seasonal weather forecast data, combined with disease statistics and static layers such as land cover, as the inputs into a dengue fever model and a water availability model. Water availability directly impacts dengue epidemics due to the provision of mosquito breeding sites. The datasets are regularly updated with the latest data and run through the models to produce a new monthly forecast. For this we have designed a system to reliably feed standardised data to the models. The project has involved a close collaboration between remote sensing scientists, geospatial scientists, hydrologists and disease modelling experts. We will discuss our approach to the selection of data sources, data source quality assessment, and design of a processing and ingestion system to produce analysis-ready data for input to the disease and water availability models.
Microbial Redox Reactions During Underground Storage of Hydrogen
Authors: Krueger Martin , Dohrmann Anja
Published: March 2020

Underground storage of hydrogen (H2) could be an alternative or important supplement to energy storage. However, there is still lack of knowledge about fundamental biogeochemical aspects of underground H2 storage. The BMBF-funded project H2_ReacT investigates fundamental petrophysical, geochemical and biogeochemical aspects of underground H2 storage. The work presented here addresses the microbial consumption of H2 and the involved microorganisms at potential underground storage sites.

Microbial reactions that consume H2 are still a major uncertainty factor for underground H2 storage. Microbial life is widespread in the crust of the earth and geological formations suitable for underground H2 storage often contain a deep subsurface biosphere. Thus, an underground H2 storage site needs to be seen as a habitat for microorganisms. Microbial activity at the H2 storage site might affect the stored H2 as well as the integrity of the storage site itself. A specific interest is to gain information about microbial activity that might result in a loss of stored hydrogen as well as the production of unwanted metabolic products e.g. H2S. The importance of specific conditions with relevance for underground hydrogen storage i.e. elevated pressure, high temperature and rock material, will be addressed.

Preliminary results showed the consumption of H2 by indigenous microorganisms from a porous rock reservoir fluid. Hydrogen was consumed at different temperature and pressure conditions relevant for underground H2 storage. Here, hydrogen consumption rates were strongly influenced by temperature and pressure. Currently effects of several geochemical parameters on microbial H2 consumption are studied in more detail. Furthermore, molecular biological approaches are used to identify the involved microorganisms.
Intercomparison of anthropogenic ocean heat uptake processes in AOGCMs
Authors: Couldrey Matthew , Gregory Jonathan
Published: March 2020

Thermosteric sea level change, resulting from ocean heat uptake, is a key component of recent and future sea level rise. The various atmosphere-ocean general circulation models (AOGCMs) used to predict future climate produce diverse spatial patterns of future thermosteric sea level rise. Most of this model spread occurs because the representation of ocean circulation and heat transport is different across models. These effects can be analysed through new simulations carried out as part of the Flux Anomaly Forced Intercomparison Project (FAFMIP), in which the exchanges of heat and salt are attributed to specific ocean circulation processes, namely the vertical dianeutral processes (convection, boundary layer mixing, shear instability mixing etc), isopycnal diffusion and residual-mean advection. Here, we present an intercomparison of ocean heat content change in FAFMIP experiments from a water-mass following perspective, to distinguish oceanic heat redistribution and uptake. We find that the redistribution of heat is a key difference across AOGCMs.