bluuebunny/crossref_metadata_2025 huggingface dataset:
Early detection of the Weddell polynya re-opening using SAR imagery
Authors: Lemos Adriano , Heuzé Céline
Published: March 2020

The sea ice thickness in the Weddell Sea during the austral winter normally exceeds 1 m, but in the case of a polynya, this thickness decreases to 10 cm or less. There are two theories as to why the Weddell Polynya opens: 1) comparatively warm oceanic water upwelling from its nominal depth of several hundred metres to the surface where it melts the sea ice from underneath; or 2) opening of a lead by a passing storm, lead which will then be maintained open either by the atmosphere or ocean and grow. The objective of this study is to estimate how long in advance the recent Weddell Polynya opening could have been detected by synthetic aperture radar (SAR) images due to the decrease of the sea ice thickness and/or early appearance of leads. We use high temporal and spatial resolution SAR images from the Sentinel-1 constellation (C-band) and ALOS2 (L-band) during the austral winters 2014-2018. We use an adapted version of the algorithm developed by Aldenhoff et al. (2018) to monitor changes in sea ice thickness over the polynya region. The algorithm detects the transition of the sea ice thickness through changes in small scale surface roughness and thus reduced backscatter, and allowing us to distinguish three different categories: ice, thin ice, and open water. The transition from ice to thin ice and then to open water indicates that the polynya is melted from under, whereas a direct transition from ice to open water will reveal leads. The high resolution and good coverage of the SAR imagery, and a combined effort of different satellites sensors (e.g. infrared and microwave sensors), opens the possibility of an early detection of Weddell Polynya opening.
Climate change and human lakeside adaptation in the Central Afar Region (Lake Abhe basin, Ethiopia & Djibouti) during the Later Stone Age - Neolithic transition: a multi-scalar and multi-proxy approach
Authors: Mologni Carlo , Khalidi Lamya , Revel Marie , Bruxelles Laurent , Cauliez Jessie , Arnaud Fabien , Malet Emmanuel , Chaumillon Eric , Colombier Thibault , Davtian Gourguen , Schenini Laure , Ménard Clément , Crevecoeur Isabelle
Published: March 2020

Throughout the last 20 ka, tropical Africa was the site of significant hydrological changes related to variations in the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that gradual long-term monsoon humid oscillations (African Humid Period ~14 – ~6 ka) were punctuated by centennial-scale episodes of hyperaridity (HS1, YD, 8.2 ka, 4.2 ka). These abrupt hydrological changes could have caused drastic transformations in landscape patterns, providing favourable ecosystems, but also produced arid environments that may have restricted human exploitation of the landscape.

The Abhe Lake basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater and terrigenous inputs from the Ethiopian Highlands, and is a hydro-sedimentary system sensitive to hydroclimatic change. Since 2014, in the context of the VAPOR-Afar and PSPCA programs (in Ethiopia and Djibouti respectively), we have intensified scientific investigations over this basin with the objective of exploring the evolution of Holocene hydroclimatic change, its impact on landscapes and on prehistoric human behaviour during one of the most forcible transitions in human history, that from a dominantly hunter-gathering way of life to the food production societies one.

We present the first results of this research that combines paleoclimatological, geomorphological and geoarchaeological studies based on a new set of 14C datations on two lacustrine cores, on several morpho-sedimentary outcrops and on 8 new archaeological sites spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the modalities of the African Humid Period and of the 8.2 and 4.2 ka hyperarid episodes, coupling paleolake-level reconstitution and lacustrine sediment analysis (paleolimnology, geochemistry); b) evaluate the impact of these hydroclimatic oscillations on perilacustrine sedimentary formation processes, especially for pedogenic formations; c) and better understand the relationship between environmental change and the development of one of the most important economic and cultural innovations, that of domestication.  
CyanoTRACKER: A cloud-based integrated multi-platform architecture for global observation of cyanobacterial harmful algal blooms
Authors: Mishra Deepak
Published: March 2020

Over the past decade, the global proliferation of cyanobacterial harmful algal blooms (CyanoHABs) have presented a major risk to the public and wildlife, and ecosystem and economic services provided by inland water resources. As a consequence, water resources, environmental, and healthcare agencies are in need of early information about the development of these blooms to mitigate or minimize their impact. Results from various components of a novel multi-cloud cyber-infrastructure for initial detection and continuous monitoring of spatio-temporal growth of CyanoHABs is highlighted in this study. The novelty of this CyanoTRACKER framework is the integration of community reports, remote sensing data and digital image analytics to differentiate between regular algal blooms and CyanoHABs. Individual components of CyanoTRACKER include a reporting website, mobile application (App), remotely deployable solar powered enabled automated hyperspectral sensor (CyanoSense), and a cloud-based satellite data processing and integration tool. All components of CyanoTRACKER provided important data related to CyanoHABs assessments for regional and global waterbodies. Reports and data received via social cloud including the mobile App, Twitter, Facebook, and CyanoTRACKER website, helped in identifying the geographic locations of CyanoHABs infested waterbodies. A significant increase (124.92%) in tweet numbers related to CyanoHABs was observed between 2011 (total relevant tweets = 2925) and 2015 (total relevant tweets = 6579) that reflected an increasing trend of the harmful phenomena across the globe as well as increased awareness about CyanoHABs among Twitter users. The CyanoHABs infested geographic locations extracted via social cloud were utilized for the deployment of CyanoSense at smaller waterbodies and analysis of satellite data for larger waterbodies. CyanoSense was able to differentiate between ordinary algae and CyanoHABs through the use of their characteristic absorption feature at 620nm. The results and products from this infrastructure can be rapidly disseminated via CyanoTRACKER website, social media, and direct communication with appropriate management agencies for issuing warnings and alerting lake managers, stakeholders and ordinary citizens to the imminent dangers posed by these environmentally harmful phenomena.
Toward a new ice-shelf melt rate parameterization with large-eddy simulations
Authors: Begeman Carolyn Branecky , Asay-Davis Xylar , Van Roekel Luke
Published: March 2020

Predictions of ice shelf melting depend on dynamical insights into ocean boundary layers below ice shelves. Fundamental questions regarding the nature of stratified turbulence below the sloped and ablating ice shelf base remain. Laboratory experiments, direct numerical simulations, and observations have yielded important insights, but have yet to produce a robust relationship between ice shelf melt rates and shear- and buoyancy-driven mixing. This relationship is the target of our Large-Eddy Simulations (LES) of the ice-shelf ocean boundary layer. Several new developments were applied to the LES code PALM to produce dynamic melting as well as tides. In this presentation, we demonstrate these new model capabilities. We contrast profiles of vertical turbulent fluxes of heat, salt and momentum across different simulated ice shelf settings: cold, shear-dominated settings vs. warm, buoyancy-dominated settings. We also discuss our recent work toward a new ice-shelf melt parameterization for use in large-scale ocean models on the basis of these simulations. A new melt parameterization is a critical component of ongoing ice-ocean coupling efforts, both to place melt rate predictions on a more physical footing and to achieve convergence with vertical ocean model resolution, on which current parameterizations fail.
Earthquake stress drop: what can we resolve from observations, and what can we infer about earthquake triggering processes
Authors: Chen Xiaowei , Abercrombie Rachel , Wu Qimin
Published: March 2020

The average stress drop during an earthquake is a parameter fundamental to ground motion prediction and earthquake source physics, but it has proved hard to measure accurately. This has limited our understanding of earthquake rupture, as well as the spatiotemporal variations of fault strength. In this study, we investigate the resolution limits of spectral analysis based on synthetic spectra with similar magnitude range, average stress drop and frequency bands to a fluid-injection induced earthquake sequence in Oklahoma near Guthrie.

Synthetic tests using joint spectral fitting method define the resolution limit of corner frequency as a function of maximum frequency for both individual spectra and averaged spectra from multiple stations. Synthetic tests based on stacking analysis find that the improved stacking approach can recover the true input stress drop if the corner frequencies are within the resolution limit defined by joint spectral fitting.

The improved approach is applied to the Guthrie sequence, different wave types and different signal-to-noise criteria are examined to understand the stability of the stress drop distributions. The results suggest no systematic scaling relationship for stress drop for M≤ 3.1 earthquakes, but larger events M≥3.5 tend to have higher average stress drops. Results with lower signal-to-noise ratio requirement and direct P-wave tend to have higher scaling factor compared to results with high signal-to-noise ratio and S-waves.

Comparison of results from several different methods suggest that the average stress drop is well resolved and not subject to tradeoff with attenuation. Some robust spatiotemporal variations can be linked to triggering processes and indicate possible stress heterogeneity within the fault zone. Tight clustering of low stress drop events at the beginning stage of the sequence suggests that pore pressure influences earthquake source processes. Events at shallow depth have much lower stress drop compared to deeper events. The largest earthquake occurred within a cluster of high stress drop events, and involved cascading failure of several sub-events.   
Impact of Sustainable Urban Drainage Systems (SUDS) on Vadose Zone Water
Authors: Reck Arne , Paton Eva , Kluge Björn
Published: March 2020

Sustainable Urban Drainage System (SUDS), like bioretention for stormwater runoff infiltration, offer several advantages compared to the traditional centralised sewage drainage. Such approaches maintain the natural water cycle in the urban critical zone and help to mitigate climatic extremes impact on urban areas by retarding, storing and evaporating stormwater runoff. Although SUDS are established since longer time (>25 years for example in Germany) we lack systematic investigations on the hydrological functionality and pollutant retention performance of these systems after long-term operation. We employed laboratory and field experiments coupled with numerical simulations to investigate three long-term operated bioretention systems in Germany with following objectives: (i) a detailed mapping of spatial contamination patterns; (ii) a soil hydrological and -chemical substrate characterisation; (iii) an event-based influent and effluent trace metal concentrations monitoring covering 36 months in total; and (iv) a soil water balance simulation using HYDRUS-1D. Regarding the pollution patterns, we found significantly enhanced trace metal contents in the soil substrate mainly as a function of the drainage area type and kind of inflow regime. Nonetheless, average free metal ion concentrations in the soil seepage water extracted below the upper soil layers (30-45 cm) fall below German trigger values considering the soil-groundwater pathway at all three investigated sites. Compared to influent concentrations, average load reduction of the major pollutants Cu and Zn was 55-95 % within the upper soil layers. With regard to infiltrated runoff volumes, simulated water balances revealed hydraulic load reductions of 10-40 % by evapotranspiration. Our current findings demonstrate no risk of groundwater degradation suggesting bioretention as a powerful tool in terms of maintaining the natural water cycle in the urban vadose zone even after long-term operation. Debatable might be the handling of soil substrates modified by stormwater infiltration showing enhanced trace metal contents and a certain amount of technogenic sediments like tyre wear. On the one hand, a big metal pool is specifically bound meaning it can easily turn into free ions during changing conditions like the application of de-icing agents. On the other hand, these substrates perfectly fulfil pollutant retention and water conductivity requirements as mandatory for an effective stormwater treatment using SUDS approaches.
A Fast Intermediate Complexity Atmospheric Model for Precipitation Modeling
Authors: Gutmann Ethan , Rasmussen Roy , Arnold Jeffrey
Published: March 2020

When is good enough, good enough? The spatio-temporal variability of precipitation makes measurements extremely challenging, particularly in the mountains.  Simultaneously, the improvements in physical realism of atmospheric models makes them increasingly valuable for fields such as hydrology, particularly in the mountains.  However, the computational cost of such models renders them impractical for many applications, in or out of the mountains.  Here we describe an intermediate complexity atmospheric model (ICAR) capable of capturing around 90% of the variability in orographic precipitation for 1% of the computational cost of a state of the science non-hydrostatic atmospheric simulation.  ICAR uses an analytical solution for flow perturbations created by topography and simulates the core processes responsible for orographic precipitation (e.g. orographic lifting, advection, cloud microphysical processes). We show that key aspects of orographic precipitation spatial patterns are well simulated in ICAR, including some that gridded observation based products are missing. We then show some early results when using ICAR to simulate regional climate changes forced by global models at higher spatial resolutions than it is currently practical to run traditional regional climate models. These simulations quantify plausible shifts in precipitation resulting in the transition from snow to rain, as well as elevation dependent warming caused by the snow albedo feedback.  Further, the computational efficiency of ICAR permits us to run these simulations with many different physics configurations to better explore the sensitivity of these changes to assumptions in the microphysics and land surface model components. 
Challenges of DAS measurements in seismic urban areas: case study at Etna volcano eastern flank
Authors: Napoli Rosalba , Currenti Gilda , Chalari Athena , Jestin Camille , Contrafatto Danilo , Jousset Philippe , Larocca Graziano , Pellegrino Daniele , Pulvirenti Mario , Sicali Antonino
Published: March 2020

We present the use of distributed acoustic sensing of telecommunication fibre to perform seismic monitoring on the lower eastern flank of Etna volcano. Eastern flank of Etna is structurally characterized by the existence of many faults until under the sea. One of the clearest morphological feature is the Timpe Fault System (TFS) crossing highly populated urban areas. The TFS is formed by several main segments producing shallow seismicity with a dominant normal faulting style and a right-lateral component, related to WNW-ESE regional extension. This area is highly seismogenic, with occurrence of a very frequent seismic activity punctuated by destructive earthquakes with magnitude ranges 4.3≤ML≤5.1 and a mean recurrence time of about 20 years.

To monitor the seismic response of this area we deployed an “intelligent” Distributed Acoustic Sensing (iDAS) system (SILIXA) in order to interrogate a 12-km-long telecommunication fibre-optic cable, managed by TELECOM Italia internet provider. The telecom cable runs from Linera to Zafferana villages along two primary directions roughly N-S and E-W and crosses the Santa Venerina and the Fiandaca faults, both part of the TFS. The former was entirely hidden until the 2002 eruption when a ML 4.4 earthquake exposed the fault at the surface and heavily damaged Santa Venerina village. The latter has been reactivated during the 2018 Etna activity, when a ML4.8 earthquake strongly damaged the Fleri village.

The iDAS was in acquisition for three months (11 September - 9 December 2019) and recorded the strain rate from natural and anthropogenic sources at a sampling frequency of 1 kHz with 2-m spatial resolution and a gauge length of 10 m. A second fibre in the same cable, was interrogated simultaneously by a FEBUS A1 system (FEBUS OPTICS) from 2 to 9 December 2019 with a spatial resolution and a gauge length of 5 m at a sampling frequency of 200 Hz. To validate the DAS measurements, gathered by both systems, two broadband seismometers (Trillium Compact 120 s) were deployed in the vicinity of the cable. We located using hammer shots along the cable at key positions.

During the acquisition period more than 800 local seismic events occurred on Etna with ML ranging between 0.4 and 3.4. Several regional earthquakes from Greece and Albania also occurred up to ML6.1. These seismic sources allows for investigating the response of the fibre and the detectability thresholds of iDAS and FEBUS A1 in urban areas with heterogeneous installation conditions of the telecommunication cable (cased conduit, attached conduit, aerial track).  We perform data analysis to characterize DAS amplitude and frequency responses to better estimate the coupling of the fibre to the ground.
Testing statistical methods to predict pesticide drift deposition
Authors: Garcia-Santos Glenda , Scheiber Michael , Pilz Juergen
Published: March 2020

We studied the case of the Andean region in Colombia as example of non-mechanized small farming systems in which farmers use handheld sprayers to spray pesticides. This is the most common technique to spray pesticide in developing countries. To better understand the spatial distribution of airborne pesticide drift deposits on the soil surface using that spray technique, nine different spatial interpolation methods were tested using a surrogate tracer substance (Uranine) i.e. classical approaches like the linear interpolation and kriging, and some advanced methods like spatial vine copulas, the Karhunen-Loève expansion of the underlying random field, the integrated nested Laplace approximation and the Empirical Bayesian Kriging used in ArcMap (GIS). This study contributes to future studies on mass balance and risk assessment related to environmental drift pollution in developing countries.
Effect of maintenance liming with olivine, dolomite and calcite on growing-season N2O emissions in an arable soil of SE Norway
Authors: Todorcic Vekic Teodora , Bakken Lars , Dörsch Peter
Published: March 2020

 

There is growing evidence that liming reduces the magnitude of N2O emissions in acidic soils. Here we report N2O emissions from a liming experiment with olivine, dolomite and calcite and of maintenance liming with the same materials in clay loam soil at Norwegian University of Life Sciences research farm. The field was bulk limed in 2014 and monitored for N2O fluxes by an autonomous filed flux robot (FFR). Over the course of four years, the fluxes varied but showed a potential of lime as a mitigation tool, with calcareous treatments (dolomite and calcite) displaying a clear decline in N2O emissions compared to unamended plots. To explore the effect of maintenance liming, subplots were maintenance limed and compared with bulk limed controls after sowing the field to winter wheat (Triticum aestivum L.) in summer and fertilizing with 50 kg NPK-N.

Growing-season N2O emissions (June-September) in maintenance limed dolomite plots were on average 26% lower than bulk limed plots and the corresponding reduction in calcite plots was 16%. There was no effect of maintenance liming in the olivine treatment. N2O emissions decreased in the order unlimed control > olivine > dolomite > calcite, covering a pHCaCl2 range of 4.9 to 6.5.

Our results suggest that maintenance liming, as a component of good agricultural practice, is important to maintain the N2O reducing effect of liming over time. However, the amount of CO2 released by the dissolution of lime should be investigated in order to fully explore the mitigation potential of soil pH management in crop production.
Water- and land-borne geophysical measurements before and after the sudden drainage of large karst lakes in southern Mexico
Authors: Bücker Matthias , Pérez Liseth , Flores Orozco Adrián , Gallistl Jakob , Steiner Matthias , Aigner Lukas , Hoppenbrock Johannes , Morales Barrera Wendy , Pita de la Paz Carlos , García García Emilio , Razo Pérez José Alberto , Buckel Johannes , Hördt Andreas , Schwalb Antje
Published: March 2020

The karst lakes of the sparsely-populated Lacandon Forest in Chiapas, southern Mexico, and their associated sediment infill are attracting increasing attention as high-resolution and continuous environmental and climate archives. To evaluate the information stored in the sediments, paleolimnologists retrieve sediment cores and analyze multiple biological and non-biological indicators. Our geophysical measurements presented here were motivated by the need to determine coring locations providing continuous sediments records from a total of four lakes of the Lacandon Forest. Therefore, we mapped the sediment thickness on the lake floor by applying seismic, electrical, and electromagnetic methods. The measurements were carried out with floating devices – and, after the sudden drainage of two of the studied lakes, complemented by measurements on the exposed lake floor.

During a first campaign in March 2018 when lakes were filled, we collected seismic data with a sub-bottom profiler (SBP). Furthermore, we collected transient electromagnetic (TEM) data with a floating measuring device to investigate the potential of the method for the determination of sediment thicknesses as an alternative to seismic methods. After the lake-level maximum that coincided with the first campaign, the water levels of two of the studied lakes dropped dramatically by July 2019, leaving lake Metzabok (maximum depth ~15 m) dry and lake Tzibaná (~70 m) with a water level decreased by approx. 30 m. In October 2019, when lake levels were still low, we conducted a second survey covering the dry lake floor of lake Metzabok and some dry parts of lake Tzibaná. During this second campaign, we collected electrical resistivity tomography (ERT), induced polarization (IP), and seismic refraction tomography (SRT) data along selected lines of the 2018 survey.

Our 2018 results from the water-borne survey show that sediment thickness estimates from seismic (SBP) and electrical (TEM) data agree well for water depths up to 20 m and sediment thicknesses ranging from 2 m to 10 m. The 2019 data collected on the dry lake floor confirms the findings of the first campaign and – due to the smaller distance between measuring devices and target – results in a more detailed picture of sediments and the underlying limestone bedrock.
Redox control on chromium isotope behaviour in silicate melts in contact with magnesiochromite
Authors: Bonnand Pierre , Bruand Emilie , Matzen Andrew , Jerram Matthew , Schiavi Federica , Wood Bernard , Boyet Maud , Halliday Alex
Published: March 2020

Transition metals are of special interest for understanding the conditions of differentiation processes such as core formation. Those that have more than one oxidation state can also provide powerful constraints on changing redox conditions in the mantle over time. The ability to determine isotopic fractionations associated with differentiation processes has provided a new dimension to exploration of the conditions in the early Earth in particular. It has been recently shown that Cr isotope variations in igneous systems are strongly affected by redox conditions and chromite crystallisation.

In this study, we have investigated the variations in chemical composition and Cr isotopic compositions in both magnesiochromite and silicate melts during experiments performed under controlled redox conditions. The Cr isotopic compositions measured in the silicate melts in our experiments are strongly influenced by oxygen fugacity and experiments performed at 1300 °C and -12 < logfO2 < -6 are correlated with fO2. This suggests that Cr isotopes are a powerful tool to study changes in redox conditions in high temperature processes. The Cr isotopic composition of silicate melt reacted under more oxidising conditions (logfO2 > -6) are isotopically much lighter compared to melts reacted at lower oxygen fugacity. Three hypotheses are proposed to explain such variations: (i) a change in Cr bonding environment in the silicate melt (ii) a change in Cr bonding environment in the chromite (iii) volatile loss of Cr from the silicate melt. More work is needed to definitively determine the factors that control the isotopic behaviour of Cr in silicate melts.
The past and the future of the tropical forest carbon sink: insights from permanent forest inventory plots
Authors: Hubau Wannes , Lewis Simon L. , Phillips Oliver L. , Beeckman Hans ,   AfriTRON consortium & the RAINFOR consortium
Published: March 2020

Structurally intact tropical forests sequestered ~1 Pg C yr-1 over the 1990s and early 2000s, equivalent to ~15% of fossil fuel emissions. Climate-driven vegetation models typically predict that this carbon sink will continue for the remainder of the 21st century. However, recent plot inventories from Amazonia show a declining rate of carbon sequestration, potentially signaling an imminent end to the sink. Here we assess whether the African tropical forest sink is also declining.

Records from 244 multi-census plots across 11 countries reveal that the African tropical forest sink in aboveground live biomass has been stable for three decades, at 0.66 Mg C ha-1 yr-1, from 1985-2015 (95% CI, 0.53-0.79). Thus, the carbon sink responses of Earth’s two largest expanses of tropical forest have diverged over recent decades. A statistical model including CO2, temperature, drought, and forest dynamics can account for the trends. Despite the past stability of the African carbon sink, our data and model show that very recently the sink has begun decreasing, and that it will continue to decline in the future.  This implies that the intact tropical forest carbon sink on both continents is set to end decades sooner than even the most extreme vegetation model estimates.

Published independent observations of inter-hemispheric atmospheric CO2 concentration indicate increasing carbon uptake into the Northern hemisphere landmass, offsetting a weakening of the tropical forest sink, which reinforces our conclusion that the intact tropical forest carbon sink has already saturated. Nevertheless, continued on-the-ground monitoring of the world’s remaining intact tropical forests will be required to test our prediction that the intact tropical forest carbon sink will continue to decline. Our findings were recently published in Nature (March 2020) and have important policy implications: given tropical forests are likely to sequester less carbon in the future than Earth System Models predict, an earlier date to reach net zero anthropogenic greenhouse gas emissions will be required to meet any given commitment to limit the global heating of Earth.
How model selection can determine flood risk estimates – a case study in the Ganges basin using the GLOFRIM framework
Authors: Hoch Jannis , Eilander Dirk , Ikeuchi Hiroaki
Published: March 2020

Fluvial flood events are a major threat to people and infrastructure. To compute flood risk estimates, modelling cascades are often applied. Therein, flood hazard is driven by hydrologic or river routing and floodplain flow processes. As such, model selection within such a cascade can determine how well some of these processes can be simulated. Depending on the selection made, obtained flood maps can vary and, in turn, can have major implications for the analysis of how many people, buildings, economic values and so forth is at risk. Understanding the role of model selection in the flood risk modelling process is thus of great importance.

By means of GLOFRIM 2.0, we coupled the global hydrologic model PCR-GLOBWB with the hydrodynamic models CaMa-Flood and LISFLOOD-FP for the delta region of the Ganges-Brahmaputra basin. Applying the model-coupling framework GLOFRIM facilitates forcing various models with identical boundary conditions and thus transparent and objective inter-comparison of flood models.

While replacing the kinematic wave approximation of the hydrologic model with the local inertia equation of hydrodynamic models does not yield better discharge estimates in the Ganges basin, flood maps obtained with LISFLOOD-FP improved representation of observed flood extent. Compared to downscaled products of PCR-GLOBWB and CaMa-Flood, the critical success index increases by around 50 %.

Combining the obtained flood maps with actual exposure maps gives then a first-order estimate how the selection for one specific model set-ups translates into varying flood risk estimates. The research thus shows how those model selections, deliberately made or not, are an important driver of simulated flood risk. As such, it is detrimental that the various specifics of a model are known to facilitate the optimal model selection for objective-specific modelling requirements.
Impact of the Icelandic hotspot on GPS time series in southeast Greenland
Authors: Barletta Valentina R. , Bordoni Andrea , Khan Shfaqat Abbas
Published: March 2020

The mass lost from Greenland ice sheet is one of the most important contribution to the global sea level rise, and it is under constant monitoring. However, still little is known about the heat flux at the glacier bedrock, and how it affects dynamics of the major outlet glaciers in Greenland. Recent studies suggest that the hotspot currently under Iceland have been under eastern Greenland at ~40 Ma BP and that the upwelling of hot material from the Iceland plume towards Greenland is ongoing. A warm upper mantle has a low viscosity, which in turn causes the solid Earth to rebound much faster to deglaciation. We have good reasons to believe that mantle beneath SE-Greenland has very low viscosity (Khan, et al. 2016), as also suggested by the discrepancy between the GPS velocities and the predicted purely elastic deformations caused by present-day ice loss. Here we present a preliminary computation of the Earth deformation driven by a low viscosity mantle excited by the deglatiation since the little ice age (LIA) to the present day. We produce the time series of such deformation and compare it with GPS time series, the oldest dating back to 1992.
Design of an experimental hydrological network to record and evaluate the differences in hydrological functioning across restored, unrestored and near-natural peatland
Authors: Donaldson-Selby Gillian , Quinn Nevil , Artz Rebekka
Published: March 2020

Approximately 70% of drinking water in Scotland is sourced from peat-dominated headwater catchments. Healthy peatlands provide high-quality water which requires minimal processing. However, many of Scotland’s upland peatlands show extensive evidence of gully erosion.  The consequences of peatland erosion include: the release of dissolved organic carbon (DOC) and particulate organic carbon (POC) in water supplies, increased risk of flooding, reduced biodiversity and carbon release into the atmosphere.

The 1992 European Community Habitats Directive led to legislative protection for several UK peatlands, and peatland catchment planning is a requirement of the EU Water Framework Directive. Peatland restoration is an important aspect of Scottish Government’s Climate Change planning, with a target of restoring 250 000 ha (41%) of degraded Scottish peatlands by 2030.  Although there has been an increase in UK peatland restoration projects (and associated funding) relatively few studies have sought to understand and evaluate the effectiveness of restoring the underlying hydrology, including water table depth, runoff, flow patterns and water quality.

Here we propose an experimental design to monitor and record data from restored, unrestored and near-natural peatland micro-catchments, with a view to analysing and integrating the empirical data with that from modelling studies, so as to synthesise new understanding of the relationship between restoration measures and hydrological functioning and assess potential hydrological trajectories.
Minibasin mobility and obstruction on salt-detached slopes: implications for canopy dynamics and sediment routing
Authors: Fernandez Naiara , Duffy Oliver , Peel Frank , Hudec Michael , Apps Gillian , Jackson Christopher
Published: March 2020

In salt-detached gravity-gliding/spreading systems the detachment geometry is a key control on the downslope mobility of the supra-canopy (supra-salt) sequence. As supra-canopy minibasins translate downslope, they also subside into salt. If the base of salt has high relief, minibasins may weld and stop from further free translation downslope. The degree of minibasin obstruction controls both the kinematics of the individual basins, and the more regional pattern of supra-canopy strain. Here, we use regional 3D seismic data to examine a salt-stock canopy in the northern Gulf of Mexico slope, in an area where supra-canopy minibasins subsided vertically and translated downslope above a complex base-of-salt with high relief.

At a regional scale, we distinguish two structural domains in the study area: a highly obstructed or locked domain and a highly mobile domain. Large-scale translation of the supra-canopy sequence is recorded in the mobile domain by two different structures (a far-travelled minibasin and a ramp syncline basin). Although identifying the deformation area between the two regional domains is challenging due to its diffusive nature, characterizing domains according to base-of-salt geometry and supra-canopy minibasin configuration is helpful in identifying structural domains that may share similar subsidence and downslope translation histories.

At minibasin scale, minibasins that become obstructed modify the local strain field, typically developing a zone of shortening immediately updip of it and an extensional breakaway zone immediately downdip. Seismic attribute analysis performed in a cluster of minibasins in the study area illustrates a long-lived sediment transport system affected by the complex strain patterns associated with minibasin obstruction. At an early stage, a submarine channel system is captured and subsequently rerouted in response to the updip shortening associated with minibasin obstruction. At a later stage, a mass-transport complex (MTC) is steered by the topographic barrier created by the downdip extensional breakaway associated with minibasin obstruction.

Our work illustrates how salt-tectonic processes related to minibasin obstruction can affect the canopy dynamics at both regional and minibasin scale. Furthermore, we show that minibasin obstruction processes can modify the seafloor and subsequently control deepwater sediment dispersal, which, ultimately can affect hydrocarbon reservoir distribution on salt-influenced slopes
Visual assessments and model estimations of soil erosion and relations to soil organic carbon
Authors: Djuma Hakan , Bruggeman Adriana , Eliades Marinos
Published: March 2020

Visual soil erosion assessment methods and erosion models are widely applied around the globe. The objective of this research is to assess the relation between soil organic carbon (SOC) concentrations (sampled) and two different soil erosion estimates (visual assessment and model). For the visual assessment, the method of the World Overview of Conservation Approaches and Technologies (WOCAT) was used, which is based on expert field observations per land cover unit. For the model assessment, the Pan-European Soil Erosion Risk Assessment (PESERA) model was used to simulate hill slope soil loss based on land cover, soil texture, meteorological data and slope profile. The research was conducted in Peristerona watershed in Cyprus (surface area: 106.4 km2, elevation: 300 to 1,540 m above sea level, average annual precipitation: 270 mm downstream and 750 mm upstream). The WOCAT questionnaires were completed by a trained specialist during site visits for 79 mapping units in 15 different land cover types. These results were compared with SOC concentrations from 29 points in the same watershed (0-25 cm depth, grid-based sampling, variety of land covers). For erosion modelling comparison, SOC concentrations from 11 paired sites of productive and abandoned terraced vineyards (0-10 cm depth, random sampling) were compared to the PESERA estimates of the same sites. A transect was drawn from the slope top to the SOC sampling point and erosion was estimated for the slope section where sampling was performed. Both the visual assessment and the modelling method showed that SOC concentrations were lower for areas with higher soil erosion. The mean SOC concentration was 1.7% (n=19) for areas ranked as “light erosion” in the WOCAT assessment and was 0.8% (n=10) for areas ranked as “moderate erosion”. Similarly, the abandoned sites that showed higher PESERA estimated erosion than the productive sites (more than 10 times higher erosion rate (n=2)) had lower SOC concentrations than their productive counterpart (half the SOC concentrations). The SOC concentrations almost doubled for abandoned sites compared to the productive sites when PESERA estimated erosion went from 10 times more to 5 times more (n=6) for the abandoned sites. Results from both methods indicate that soil erosion rates and top soil SOC concentrations are related and need to be considered in erosion models. 
Shifting eruption dynamics: Constraints from mineral chemistry and plagioclase-hosted melt inclusions at Santiaguito volcanic dome complex, Guatemala
Authors: Hartung Eva , Wallace Paul A. , Von Aulock Felix W. , Hornby Adrian , Lavallée Yan
Published: March 2020

Activity at Santiaguito volcanic dome complex started in 1922 with the continuous eruption of crystal-rich dacitic-andesitic lavas, which over the course of the last century, constructed a series of four domes and were host to frequent minor explosions. In 2016, a drastic shift in activity occurred with an 8-months period of heightened explosion intensity. We present records of textural and compositional variations in plagioclase, orthopyroxene and plagioclase-hosted melt inclusions of a series of ash and ballistic samples erupted and collected in-situ between 2015 and 2019 to reconstruct the magmatic processes associated with such shifts in activity.

Plagioclase phenocrysts show a wide range of compositions (An90-35) and can be grouped into three populations based on compositional and textural variations: crystals with resorbed albite-rich cores (An35–40), anorthite-rich cores (An85–90) and patchy zoned cores (An50–85). All plagioclase crystals contain homogenous rims of An50 that are marked by an increase in Fe content from about 3000 to 5000 ppm and a higher Mg content (of up to 300 ppm) towards the rim. Orthopyroxene phenocrysts show constant enstatite compositions from core to rim (En68-70). However, rims are relatively enriched and depleted in Ti and Mn contents respectively. Plagioclase-hosted melt inclusions are found in reversely zoned crystals, in crystal rims and between glomerocrysts. Irregularly shaped melt pockets are frequently observed in patchy zoned cores. Melt inclusions overall range in silica content from 71 to 78 SiO2 wt.% (anhydrous) and are marked by relatively high TiO2 and K2O contents.

Melt and mineral compositions and textures suggest that a shallow magma storage zone currently exists below Santiaguito volcanic dome complex. Pressure estimates of plagioclase-hosted melt inclusions yield an average of about 150 MPa (± 50 MPa) using rhyolite-MELTS indicating magma storage at depth of about 4 to 8 km. The observed increase in Fe, Mg and Ti contents in the rims of the plagioclase and orthopyroxene phenocrysts and microlite crystals are consistent with recharge of new magma into the upper crust, which was likely responsible for the drastic shift in eruption dynamics at Santiaguito volcanic dome complex in 2015-2016.
Impact of non-Arctic observations on the AROME-Arctic regional model
Authors: Randriamampianina Rogerr
Published: March 2020

In the framework of the Applicate project (https://applicate.eu), ECMWF (European Centre for Medium-Range Weather Forecasts) performed global (Bormann et al. 2019) and Arctic (Lawrence et al. 2019) observing system experiments. Use of the results of these experiments as lateral boundary conditions (LBC) for our regional model opens opportunity to study the following: 1) the impact of observations through regional data assimilation (DA); 2) the impact of observations that are assimilated in a global model through LBC in a regional model; 3) the impact of global loss of observations in a regional model; and 4) the impact of non-Arctic observations in an Arctic regional model.

In the framework of the Alertness project, we performed experiments for the two special observation periods (SOP) 1 and 2 and found considerable impact (significant for some cases) of both conventional and satellite observations through both regional DA and LBC. So far, the impact of non-Arctic observations on our Arctic regional model AROME-Arctic analyses and forecasts was checked during SOP1 with microwave radiance only. The impact was found to be positive, especially on day-2 forecasts.

In this presentation, the impact of other non-Arctic observations (conventional and satellite) on our regional model AROME-Arctic will be discussed through different forecast skill scores verification.
Drivers of oceanic exchange through the Indonesian Throughflow since the late 1800s – a synthesis of coral δ18O and high-resolution ocean models
Authors: Murty Sujata , Ummenhofer Caroline , Scheinert Markus , Behrens Erik , Biastoch Arne , Böning Claus
Published: March 2020

The Indonesian Throughflow (ITF) serves as an important oceanic teleconnection for Indo-Pacific climate, altering heat and buoyancy transport from the Pacific to the Indian Ocean. Equatorial Pacific wind forcing transmitted through the ITF impacts interannual to interdecadal Indian Ocean thermocline depth and heat content, with implications for preconditioning Indian Ocean Dipole events. Yet the modulation of Indian Ocean thermal properties at seasonal timescales is still poorly understood. Here we synthesize coral δ18O records, instrumental indices (El Niño Southern Oscillation (ENSO), Asian Monsoon), and simulated ocean variability (sea surface salinity (SSS) and temperature (SST), heat content, mixed layer depth) from state-of-the-art NEMO ocean model hindcasts to explore drivers of seasonal to multi-decadal variability. All coral sites are located within main ITF pathways and are influenced by monsoon-driven, buoyant South China Sea (SCS) surface waters during boreal winter that obstruct surface ITF flow and reduce heat transport to the Indian Ocean. Makassar and Lombok Strait coral δ18O co-varies with simulated SSS, subsurface heat content anomalies (50-350m) and mixed layer depth at the coral sites and in the eastern Indian Ocean. At decadal timescales, simulated boreal winter ocean variability at the coral sites additionally indicates a potential intensification of the SCS buoyancy plug from the mid- to late-20th century. Notably, the variability in these coral and model responses reveals sensitivity to phase changes in the Interdecadal Pacific Oscillation and the East Asian Winter Monsoon. These results collectively suggest that the paleoproxy records are capturing important features of regional hydrography and Indo-Pacific exchange, including responses to regional monsoon variability. Such proxy-model comparison is critical for understanding the drivers of variability related to changes in ITF oceanic teleconnections over the 19th and 20th centuries.
Towards understanding nitrogen legacies in European catchments
Authors: Sarrazin Fanny , Kumar Rohini , Van Meter Kimberly , Weber Michael , Musolff Andreas , Basu Nandita , Attinger Sabine
Published: March 2020

Reducing nitrogen (N) levels in European water bodies is a pressing issue, as evidenced by the recent fines imposed by the European Count Justice on countries such as France, Germany and Greece for exceeding the regulatory limits for nitrate (World Bank report on “Quality Unknown: The Invisible Water Crisis” by Damania et al., 2019). N levels can depend not only on current N inputs to the landscape, but also on the past N inputs that have accumulated through time in the soil root zone and the groundwater in so-called ‘legacy stores’. Effective N management strategies should therefore account for these N legacies.

This study aims to gain a better understanding of the impact of N legacies on in-stream nitrate concentration and loading at annual time scale in European catchments. To this end, we apply a parsimonious nitrate model, called ELEMENT (Van Meter et al., 2017, Global Biogeochem Cycles), given the limited amount of information available to constrain and test the model simulations. We construct a nitrogen input dataset (N-surplus) to force the model from the early 19th Century, thus ensuring the build-up of the model soil and groundwater legacy stores. We estimate the model parameters based on the application of ‘soft rules’, to account for the uncertainty in the model inputs and the output measurements, and we examine the model controlling processes using sensitivity analysis.

We present here the results for the case of the Weser catchment, a large catchment in northern Germany that discharges into the North Sea. In particular, our results show that the model reproduces well nitrate stream loading. Despite the parsimonious structure of the ELEMENT model, we identify the presence of parameter equifinality, when the model is constrained using in-stream concentration and loading only. We discuss the possibility of using additional information (such as soil organic N content) to improve parameter identifiability and the overall simulation results.
Detection of surface subsidence using SAR SENTINEL 1A imagery and the short baseline InSAR method – a case study of the Belchatow open pit mine, Central Poland.
Authors: Wajs Jaroslaw , Milczarek Wojciech J.
Published: March 2020

The work focuses on time series analysis application through the high temporary resolution imagery from the SENTINEL 1A/1B mission. The analysis of surface subsidence in open pit mining area was performed by the selected InSAR approach - small baseline InSAR. This methodology allows for continuous monitoring of the mining area. The study was performed in the 700 km^2 mining area of the PGE GiEK KWB Belchatow mine in Central Europe (Area Of Interest, AOI). The SAR imageries acquired by the SENTINEL 1A/1B satellite for the 124-descending track in two years period - 10.2015 and 01.2017 have been used in the analysis. The post-proceed satellite LOS (Line of Sight) displacement indicates vertical changes of the surface within the dumping and excavation area. The analyzed AOI shows total subsidence of ca. -500 mm, whereas the excavation area shows a trend of terrain uplift ca. +250 mm during the analyzed periods. The presented processing pathway allows for the early detection of landslides in near real-time. Future work will focus on the accuracy assessment of analyzed data and detection of horizontal displacements of the AOI.