bluuebunny/crossref_metadata_2025 huggingface dataset:
How to circumvent the limitations of open source software and orthorectify how (or better) than with commercial software
Authors: Baiocchi Valerio , Onori Roberta , Monti Felicia , Giannone Francesca
Published: March 2020

High and very high resolution satellite images are now an irreplaceable resource for earth observation in general and for the extraction of hydrogeological information in particular. In order to use them correctly and compare them with previous surveys and maps, they must be treated geometrically to remove the distortions introduced by the acquisition process. Orthorectification is not a simple georeferencing because the process must take into account the three-dimensional acquisition geometry of the sensor. For this reason orthorectification must be performed within specific commercial software with additional costs compared to image acquisition which, in some cases, is currently free of charge.
Some orthorectification algorithms, mainly based on the RPC approach, are available in open source GIS software such as QGIS. OTB (Orpheus toolbox) for QGIS contains some of these algorithms but its interfaces are not clear and there are some incomprehensible limitations such as the impossibility to input three-dimensional ground control points (GCPs). This severely limits the final achievable accuracy because it does not allow to correctly estimate the influence of different ground morphologies on the acquisition geometry. To get around these limitations you can make a "pseudo DEM" and other expedients to complete the whole process obtaining absolute results comparable if not better than those of commercial software.
The proposed procedure may not be the fastest but it can be a valid alternative for those who use satellite images as a tool in their research work.

 
Combined event-based tritium and air mass back-trajectory analysis of Mediterranean precipitation events
Authors: Juhlke Tobias , Sültenfuß Jürgen , Trachte Katja , Huneau Frédéric , Garel Emilie , Santoni Sébastien , Barth Johannes A. C. , van Geldern Robert
Published: March 2020

Climate models are in need of improved constraints for water vapor transport in the atmosphere and tritium can serve as a powerful tracer in the hydrological cycle. Although general principles of tritium distribution and transfer processes within and between the various hydrological compartments are known, variation on short timescales and aspects of altitude dependence are still under debate. To address questions for tritium sources, sinks and transfer processes, sampling of individual precipitation events in Corte on the island of Corsica in the Mediterranean Sea was performed between April 2017 and April 2018. Tritium concentrations of 46 event samples were compared to their moisture origin and corresponding air mass history. Air mass back-trajectories were generated from the novel high-resolution ERA 5 data set of the ECMWF (European Centre for Medium-Range Weather Forecasts). Geographical source regions of similar tritium concentrations were predefined using generally known tritium distribution patterns, such as a ‘continental effect’, and from data records derived at long-term measurement stations of tritium in precipitation across the working area. Our model-derived source region tritium concentrations agreed well with annual mean station values. Moisture that originated from continental Europe and the Atlantic Ocean was most distinct regarding tritium concentrations with values up to 8.8 TU and near 0 TU, respectively. Seasonality of tritium values ranged from 1.6 TU in January to 10.1 TU in May and exhibited well-known elevated concentrations in spring and early summer due to increased stratosphere-troposphere exchange. However, this pattern was interrupted by extreme events. The average altitude of trajectories correlated with tritium concentrations in precipitation, especially in spring and early summer and if outlier values of extreme tritium concentrations were excluded. However, in combination with the trajectory information, these outlier values proved to be valuable for the understanding of tritium movement in the atmosphere. Our work shows how event-based tritium research can advance the understanding of its distribution in the atmosphere.
An approach to accommodate and estimate antecedent moisture in runoff curve number methodology- An experimental study
Authors: Mishra Surendra Kumar , Sharma Ishan , Pandey Ashish , Kumre Shailendra Kumar
Published: March 2020

Modelling of the event-based rainfall-runoff process has considerable importance in Hydrology, especially for assessment of water yield potential of a watershed, planning of soil and water conservation measures, reducing sedimentation, and flooding hazards downstream. Antecedent moisture (M) plays a significant role in governing the rainfall-runoff modelling process. It has been the focal point of research in the last decade for improving the Soil Conservation Service Curve Number (SCS-CN) method (also known as NRCS-CN method) for surface runoff computation. In this study, an innovative procedure is proposed to accommodate M in the basic structure of the SCS-CN methodology which otherwise was incorporated externally; to compute M using rainfall-runoff data and verify its applicability by comparing M with the in-situ soil moisture.

Natural rainfall, runoff, and soil moisture data from 6 small experimental farms with different land-use viz. Maize, Finger Millet, and Fallow land, located at Roorkee, India, are utilized. The M is computed by optimizing two parameters, i.e., absolute maximum potential retention (Sabs) and initial abstraction ratio (λ), and the optimization is accomplished by minimizing the root mean square error (RMSE). Results show that there exists a good correlation between theoretical M and measured in-situ moisture. Also, the optimized value of λ has the less error in computing M than the other standard values of λ (λ = 0.2; λ= 0.03). This study not only improves the SCS-CN method but also widens its application horizon in soil moisture studies.
Seasonal forecasting and the predictability of the rainy and dry seasons for Peru, Tanzania and India
Authors: Möller Thomas , Gates Lydia
Published: March 2020

With seasonal forecast models we investigate whether it is possible to give the people in Tanzania, Peru and India time to adapt and prepare to different weather conditions. In recent years, these countries have repeatedly experienced devastating droughts or floods, such as in East Africa in November 2019.

Under the framework of the research project EPICC (East Africa Peru India Climate Capacities) supported by the BMU (Federal Ministry for the Environment, Nature Conservation and Nuclear Safety), we aim to set up a seasonal forecast system. The goal is to make the data useful for the hydrologists at the project partner from PIK (Potsdam Institute for Climate Impact Research) for integration in a tool for adaption in local agriculture in the affected countries (India, Peru and Tanzania). In this study, we validate a number of variables of predicted anomalies in seasonal forecast models as well as of a multimodel product.

There are different methods of seasonal predictability, based on slow variations of boundary conditions, coupled ocean-atmosphere model simulations as well as the concept of ensembles, multi-model ensembles and uncertainties. The focus in this study is on the intercomparison of the single models and the multimodel in a forecast range between 1 and 6 months. In particular, we investigate three-month mean deviation from the long-term mean. It is important for the population (especially for the agriculture industry) in the focus region to know whether in a certain period (rainy season, dry season, El Nino etc.) the next 3 months will be colder, warmer, drier or even wetter compared to the long-term mean.

Due to the fact, that various seasonal forecasting models perform differently, it is the challenge, to find the best fitting seasonal forecast model for each of the affected countries.
Estimating structural and parametric uncertainties in the simulated early Eocene surface warming
Authors: Steinig Sebastian , Bragg Fran J. , Irvine Peter J. , Lunt Daniel J. , Valdes Paul J.
Published: March 2020

Simulating the proxy-derived surface warming and reduced meridional temperature gradient of the early Eocene greenhouse climate still represents a challenge for most atmosphere-ocean general circulation models. A profound understanding of uncertainties associated with the respective model results is thereby essential to reliably identify any similarities or misfits to the proxy record. Besides incomplete knowledge of past greenhouse gas concentrations and other boundary conditions, structural and parametric uncertainties are the main factors that determine our confidence in paleoclimate simulation results.

The recent publication of coordinated model experiments that apply identical paleogeographic boundary conditions for key time periods of the early Eocene (DeepMIP) allows a systematic analysis of inter-model differences and therefore of structural uncertainties in the simulated surface warming. Here we additionally explore the parametric uncertainty of the early Eocene climatic optimum (EECO) surface warming within one DeepMIP model. For this we performed perturbed parameter ensemble (PPE) simulations with HadCM3B at different atmospheric CO2 concentrations following the DeepMIP protocol. Twenty-one parameter sets based on changes in six atmospheric parameters, a sea-ice parameter and the ocean background diffusivity were branched off from the respective DeepMIP control simulations and integrated for a further 1500 model years. The selected parameter sets are based on previous results demonstrating their ability to simulate a pre-industrial global-mean surface temperature within ±2 °C of the standard configuration.

Preliminary results indicate a large spread of the simulated low-latitude surface warming in the PPE and therefore significant changes of the large-scale meridional temperature gradient for the EECO. Some ensemble members develop numerical instabilities at CO2 concentrations of 840 ppmv and above, most likely in consequence of high temperatures in the tropical troposphere. We further compare the magnitude of the parametric uncertainty of the HadCM3B perturbation experiments with the structural differences found in the DeepMIP multi-model ensemble and explore the sensitivity of the results to the strength of the applied greenhouse gas forcing. Model skill of the PPE members is tested against the most recent DeepMIP compilations of marine and terrestrial proxy temperatures.
Seismic response of three glacially overdeepened valleys – a comparison
Authors: Burschil Thomas , Buness Hermann , Brandt Anna-Catharina , Tanner David C. , Gabriel Gerald
Published: March 2020

Seismic imaging is a spiffing tool to explore the shape and stratigraphy of Quaternary structures such as glacially overdeepened valleys. Recent seismic investigations have unlocked some of the secrets of three of such valleys in the European Alps. Their locations range from distal Quaternary overdeepened basins in the Alpine foreland, i.e. Tannwald Basin (TB) in Germany and the Basadingen Valley (BV) in Switzerland, to the proximal, intra-mountainous Lienz Basin (LB) in Austria. All of them are also primary investigation sites of the project Drilling Overdeepened Valleys (DOVE), funded by the International Continental Scientific Drilling Program (ICDP).

Seismic reflections map the shape and the internal structure of the infill of these basins in detail. The LB shows a classical sedimentary succession of only one glacial cycle, i.e. (from bottom to top) tills, lacustrine sediments, and fluvial deposits. Reflections in the bedrock are not visible. This is in contrast to the distal foreland basins that incise Tertiary sediments and possess sediments of more than one glacial cycle. The reflection patterns of the substrata of the TB and BV basins consist of deeper, continuous horizons and a thick sedimentary package that was incised by glacial erosion. However, the internal reflections differ significantly. In the TB, we discriminate (from bottom to top) plucked molasses units, till of an older glacial cycle, lacustrine sediments, younger till and till sequences, as well as fluvial deposits on top. The preliminary result of the BV illustrates several unconformities and a spatial highly variable setting. The latter is supported by trackable horizons that show several laterally-shifted troughs within the basin fill.

The comparison of the seismic results thus reveals the difference of the sedimentary infill of all three glacially overdeepened valleys. Especially, the internal structure of both basins in the foreland shows unexpected variability.
The spatial distribution of dust in the inner comae of comets: Evidence for and modelling of nightside emission
Authors: Thomas Nicolas , Gerig Selina-Barbara , Pinzon Olga , Marschall Raphael , Wu Jong-Shinn , Herny Clemence
Published: March 2020

Spacecraft imaging of the inner comae of 1P/Halley (Giotto/HMC) and 19P/Borrelly (DS1/MICAS) indicated unexpectedly low ratios for the dust brightness above the dayside hemisphere to that above the nightside. Neither ratio was consistent with dust emission being directly proportional to sublimation loss of H2O using purely insolation-driven models. The near-terminator observations of 67P/Churyumov-Gerasimenko from Rosetta allow very precise separation of the dayside and nightside hemispheres and confirm low dayside to nightside dust brightness ratios. In the case of 67P values of ~3.3:1 were observed and an interesting trend towards increased ratios with decreasing heliocentric distance. Detailed modelling using insolation-driven models do not fit the data by factors of several. Dust from the dayside may contribute to the brightness on the nightside if particles are not escaping and therefore gravitationally bound. However, the radial distribution of brightness on the nightside is inconsistent with this interpretation as can be demonstrated with a simple model. The source is also not in the form of single nightside (e.g. “sunset”) jets. Furthermore, shadowing of emitted dust by the nucleus itself indicates that much of the observed brightness on the nightside is very close to the nucleus and distributed roughly uniformly around in the nightside hemisphere (Gerig et al., submitted).

Gas emission from the nightside has been a consistent element of source distributions (e.g. Bieler et al., 2015) required to model ROSINA/COPS data. However, the composition is frequently not specified. We have been investigating self-consistent, physically generated, numerical models of combined H2O and CO2 emission (see also Herny et al., submitted). Dust emission has been incorporated into the model chain allowing modelling of the observation of the gas composition, the gas density, and the dust brightness distribution in the vicinity of the nucleus for specific times. The results of investigation will be presented.
A record of seafloor methane seepage across the last 150 million years
Authors: Oppo Davide , De Siena Luca , Kemp David
Published: March 2020

Methane seepage at the seafloor is a source of carbon in the marine environment and has long been recognized as an important window into the deep geo-, hydro-, and bio-spheres. However, the processes and temporal patterns of natural methane emission over multi-million-year time scales are still poorly understood. The microbially-mediated methane oxidation leads to the precipitation of authigenic carbonate minerals within subseafloor sediments, thus providing a potentially extensive record of past methane emission. In this study, we used data on methane-derived authigenic carbonates to build a proxy time series of seafloor methane emission over the last 150 My. We quantitatively demonstrate that variations in sea level and organic carbon burial are the dominant controls on methane leakage since the Early Cretaceous. Sea level controls variations of methane seepage by imposing smooth trends with cyclicities in the order of tens of My. Organic carbon burial shows the same cyclicities and instantaneously controls the volumes of methane released thanks to the rapid generation of biogenic methane. The identified fundamental (26-27 My) cyclicity matches those observed in the carbon cycle associated with plate tectonic processes, the atmospheric CO2, the oceanic anoxic events, and mass extinction events. A higher (12 My) cyclicity relates to modulations of Milankovitch eccentricity cycles and to variations in global tectonics. These analogies demonstrate that the seafloor methane seepage across the last 150 My relates to a large spectrum of global phenomena and thus has key implications for a better understanding of methane cycling at the present day. Temporal correlation analysis supports the evidence that the modern expansion of hypoxic areas and its effect on organic carbon burial may lead to higher seawater methane concentrations over the coming centuries.
Decomposing barotropic transport variability in a high-resolution ocean model of the North Atlantic Ocean
Authors: Wang Yuan , Greatbatch Richard , Claus Martin , Sheng Jinyu
Published: March 2020

Temporal variability of the annual mean barotropic streamfunction in a high-resolution model configuration (VIKING20) for the northern North Atlantic is analyzed using a decomposition technique based on the vertically-averaged momentum equation. The method is illustrated by examining how the Gulf Stream transport in the recirculation region responds to the winter North Atlantic Oscillation (NAO). While no significant response is found in the year overlapping with the winter NAO index, a tendency is found for the Gulf Stream transport to increase as the NAO becomes more positive, starting in lead years 1 and 2 when the mean flow advection (MFA) and eddy momentum flux (EMF) terms associated with the nonlinear terms dominate in the momentum equations. Only after 2 years, the potential energy (PE) term, associated with the density field, starts to play a role and it is only after 5 years that the transport dependence on the NAO ceases to be significant. The PE contribution to the transport streamfunction has significant memory of up to 5 years in the Labrador and Irminger Seas. However, it is only around the northern rim of these seas that VIKING20 and the transport reconstruction exhibit similar memory. This is due to masking by the nonlinear MFA and EMF contributions.
Influence of seasonal changes on the mid-latitude trough properties
Authors: Matyjasiak Barbara , Przepiórka Dorota , Rothkaehl Hanna
Published: March 2020

The sub-auroral region of the main ionospheric trough is a very unique area strongly affected by different type of instabilities coming from both
the bottom (Earth's atmosphere) and the top (Earth's magnetosphere) neighbouring regions. The main ionospheric trough’s
general characteristics as well as the detailed features change accordingly to the time of day, season, solar cycle and many others. The
location of MIT in the latitude-longitude coordinate system throughout the year reflects seasonal changes. Annual variations are observed also in the
shape and intensity of the structure. Despite the representation of the structure in the geomagnetic coordinate system, northern and southern
trough are not symmetric in the same local season. However some similarities have also been observed. In particular for both hemispheres
the structure appears the deepest and well developed during local winter, whereas during local summer the structure becomes hardly visible.
Observations show that the MIT tends to shift equatorward for some longitudes in both hemispheres.
MIT properties for this study have been derived from DEMETER and COSMIC/FORMOSAT-3 observations.

 
Contributions of fault gouge mineralogy on aseismic creep of active faults: the East Anatolian Fault (Eastern Turkey) as a case study
Authors: Yazıcı Müge , Basmenji Mehran , Köküm Mehmet , Dogan Ugur , Zabcı Cengiz , Ergintav Semih
Published: March 2020

In the complex tectonic setting of the Eastern Mediterranean, the westward motion of the Anatolian Block is accommodated mainly along its boundary faults, the North Anatolian Shear Zone (NASZ) and the East Anatolian Shear Zone (EASZ). Although there are relatively limited studies on the active tectonics of the EASZ, horizontal slip rate is suggested to be of about 10 mm/yr, using geodetic data. In terms of instrumental and historical seismicity, this sinistral strike-slip fault generated surface rupturing earthquakes along almost its entire length except two segments, Palu in the northeast and Turkoglu in the southwest, creating two seismic gaps on the East Anatolian Fault (EAF), the most prominent member of the EASZ. In spite of the fact that there are some off-fault seismic activities such as the 2010 KovancÄ±lar Earthquake (M 6.1) in the vicinity of Palu Seismic Gap, recent geodetic measurements show significant aseismic creep, almost retaining the full far plate velocity (~10 mm/yr) for about 100 km-long section of the fault. Hence, the region is continuously monitored by various types of techniques, such as GNSS, InSAR, creepmeter, seismology, and high-resolution photogrammetry.

In addition to monitoring, we investigated the mechanical signature of the creep in the fault zone using fault rocks along the Palu Segment. We collected several samples directly from the deformation zone of the EAF, which makes the boundary between limestones of the Kirkgecit Formation and the chaotic alternation of volcanics, mudstones, and limestones of the Maden Complex, at two locations. The Underground Railway Tunnel Section (39.9504°N, 38.6976°E) is cut by the fault zone where the creep signals are recorded by a creepmeter. The X-Ray Diffraction (XRD) analyses of collected samples of this locality suggest the presence of montmorillonite (smectite group) as the main clay mineral in addition to chlorite-kaolinite with a negligible amount of illite-mica minerals within the fault rocks. This preliminary result suggests a linkage between the creeping and petrophysical properties of fault rocks, which are made of the weak smectite mineral and show no-frictional healing as the expected characteristics of the creep. However, the preliminary analyses of fault gouge samples from the Murat River Section (39.9696°N, 38.7043°E) yield a small amount of smectite group clays. We are going to extend our study at different locations in order to increase the spatial resolution on the relation between the fault rocks and creep motion. This study is supported by the TUBITAK Project no. 118Y435.
Using a dew point temperature scaling framework to interpret changes in hourly extremes from convection-permitting model simulations
Authors: Lenderink Geert , van Meijgaard Erik , de Vries Hylke , van Ulft Bert , Barbero Renaud , Fowler Hayley
Published: March 2020

While summer rain storms are very intermittent, chaotic and influenced by multiple atmospheric drivers, some statistics of observed short duration precipitation actually display surprisingly simple, regular behaviour. As an example, 10-min rainfall extremes derived from Dutch climate data show a dependency of 13% per degree over an almost 20-degree dew point temperature range. Similar behaviour has also been found in hourly precipitation observations. Each degree of warming reflects 6-7% more moisture in the air,  following from the well-known Clausius-Clapeyron (CC) relation which is the cornerstone to understand and quantify the influence of climate change on precipitation extremes.  According to the above finding, however, precipitation intensities may be increasing with temperature at a rate twice the commonly expected CC rate. In this presentation we will use output from a number of 10-year simulations for present-day and future climate with the convection permitting model HCLIM-AROME to investigate how hourly extremes respond to warming in both a pseudo global warming (PGW) and a GCM driven setup. In particular, we use the scaling diagram -- different percentiles of the rainfall distribution, usually the 90, and 99th conditioned on the occurrence of rain, as a function of dew  point temperature -- as a analysis environment. Focus will be on how the scaling diagram is affected by climate change, and what information can be derived from these changes in scaling. While changes in the scaling diagram between present-day and future climate are in general consistent with a CC prediction, evidence of super CC behaviour, between 10 and 14 % per degree dew point, is also present. The same applies to changes in the most extreme events from the simulations, which show super CC behaviour in both PGW and GCM driven setups when scaled with the appropriate dew point temperature change. 
Eddy statistics validation of an ORCA12 ocean and sea ice model for the Arctic with satellite data
Authors: Rynders Stefanie , Akesenov Yevgeny , Kozlov Igor
Published: March 2020

As sea ice and ocean models are moving to higher resolution it becomes possible to permit eddy formation even in the Arctic Ocean. Eddies can affect the three dimensional ocean state through causing mixing and even ventilation of subsurface ocean layers if they are deep enough. To ensure models have the potential to simulate the density structure correctly it is therefore necessary to start doing model validation of not only the large scale ocean state, but also of the eddy field. Eddy statistics for the Arctic are available from satellite for the Western Arctic Ocean and the Fram Strait, in particular on number, size and cyclonicity of eddies for open ocean versus ice covered sites. These are compared to a NEMO-LIM 1/12 degree sea ice and ocean simulation (resolution 2-5km), upon which the model based statistics are expanded to the whole Arctic. In the model it is also possible to examine the depth structure of eddies, allowing to generate size vs. depth statistics. This, together with climatological mixed layer depth, provides a first estimate to get satellite-based information on mixing from eddies in the Arctic. We also map the maximum depth of eddies, to examine ventilation and identify sites with especially deep eddies, for instance at the boundary current. Acknowledgements: Grant NE/R000654/1 “Towards a Marginal Sea Ice Cover” funded by the UK Natural Research Council (NERC) and the UK-Russia Arctic bursaries program funded by the United Kingdom’s Department for Business, Energy and Industrial Strategy. The study is also supported from the project “The Advective Pathways of nutrients and key Ecological substances in the Arctic (APEAR)” (grant NE/R012865/1) funded by the Joint UK NERC/German Federal Ministry of Education and Research Changing Arctic Ocean Programme. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 821926 (IMMERSE). IK acknowledges the support from RFBR grant No 18-35-20078.
Antarctic Atmospheric River Climatology and Impacts
Authors: Wille Jonathan , Favier Vincent , Gorodetskaya Irina V. , Agosta Cécile , Beeman Jai Chowdhry , Dufour Ambroise , Codron Francis , Turner John
Published: March 2020

Atmospheric rivers, broadly defined as narrow yet long bands of strong horizontal vapor transport typically imbedded in a low level jet ahead of a cold front of an extratropical cyclone, provide a sub-tropical connection to the Antarctic continent and are observed to significantly impact the affected region’s surface mass balance over short, extreme events. When an atmospheric river makes landfall on the Antarctic continent, their signature is clearly observed in increased downward longwave radiation, cloud liquid water content, surface temperature, snowfall, surface melt, and moisture transport.

Using an atmospheric river detection algorithm designed for Antarctica and regional climate simulations from MAR, we created a climatology of atmospheric river occurrence and their associated impacts on surface melt and snowfall. Despite their rarity of occurrence over Antarctica (maximum frequency of ~1.5% over a given point), they have produced significant impacts on melting and snowfall processes. From 1979-2017, atmospheric rivers landfalls and their associated radiative flux anomalies and foehn winds accounted for around 40% of the total summer surface melt on the Ross Ice Shelf (approaching 100% at higher elevations in Marie Byrd Land) and 40-80% of total winter surface melt on the ice shelves along the Antarctic Peninsula. On the other side of the continent in East Antarctica, atmospheric rivers have a greater influence on annual snowfall variability. There atmospheric rivers are responsible for 20-40% of annual snowfall with localized higher percentages across Dronning Maud Land, Amery Ice Shelf, and Wilkes Land.

Atmospheric river landfalls occur within a highly amplified polar jet pattern and often are found in the entrance region of a blocking ridge. Therefore, atmospheric river variability is connected with atmospheric blocking variability over the Southern Ocean. There has been a significant increase in atmospheric river activity over the Amundsen-Bellingshausen sea and coastline and into Dronning Maud Land region from 1980-2018. Meanwhile, there is a significant decreasing trend in the region surrounding Law Dome. Our results suggest that atmospheric rivers play a significant role in the Antarctic surface mass balance, and that any future changes in atmospheric blocking or tropical-polar teleconnections may have significant impacts on future surface mass balance projections.
Volcano-tectonic earthquake statistics for Campi Flegrei monitoring
Authors: Tramelli Anna , Godano Cataldo , Giudicepietro Flora , Ricciolino Patrizia , Caliro Stefano
Published: March 2020

The knowledge of the dynamic of the Campi Flegrei calderic system is essential to mitigate the volcanic risk in one of the most densely populated volcanic areas in the world. From 1950 to 1985 three bradyseismic crises occurred with a total uplift of almost 3 m (Del Gaudio et al., 2010). After more than 20 years of subsidence, at the end of 2005 the uplift started again accompanied by a low increment in the seismicity rate. In 2012 a further increment in the seismicity rate was observed and a variation in the gas composition of the fumaroles of Solfatara (central area of the caldera) revealed the injection of magmatic fluids into the hydrothermal system (Chiodini et al., 2017). This suggests that the investigation of the seismicity can represent a very useful tool for the risk mitigation. Here we analyze the seismic catalogue of Campi Flegrei (collected by INGV - Osservatorio Vesuviano) to check for any variation of the observed seismicity. This can be eventually associated with geochemical monitored parameters. In addition, we analyzed the most energetic swarms recorded in this period by comparing their locations, waveforms and source mechanisms. We find that occurrence rate, location and b-value change in time. The seismicity occurs in swarms, which, in the last years, tends to became closer but with a smaller number of events. The observed variations are correlated also with the geochemical monitoring parameters suggesting that the uplift process has probably modified the elastic and permeability properties of the shallow part of the crust. 
Using image-based deep learning to identify river defences from elevation data for large-scale flood modelling
Authors: Brown Catharine , Smith Helen , Waller Simon , Weller Lizzie , Wood David
Published: March 2020

National-scale flood hazard maps are an essential tool for the re/insurance industry to assess property risk and financial impacts of flooding. The creation of worst-case scenario river flood maps, assuming defence failure, and additional separate datasets indicating areas protected by defences enables the industry to best assess risk. However, there is a global shortage of information on defence locations and maintenance. For example, in the United States it is estimated that there are around 160,000 kilometres (100,000 miles) of defence levees, but the location of many of these is not mapped in large-scale defence datasets. We present a new approach to large-scale defence identification using deep learning techniques.

In the generation of flood hazard maps, the elevation depicted in the Digital Elevation Model (DEM) used in the hydraulic modelling is fundamental to determining the routing of water flow across the terrain and thus determining where flooding occurs. The full or partial representation of raised river defences in DEMs affects this routing and subsequently causes difficulty when developing both undefended and defended flood maps. To generate undefended river flood maps these raised defences need to be entirely removed, which requires knowledge of their locations. Without comprehensive defence datasets, an alternative method to identify river defences on a large-scale is required.

The use of deep learning techniques to recognise objects in images is fast developing. DEMs and other related datasets can be represented in a similar raster format to images. JBA has developed a successful methodology which involves training a U-Net Convolutional Neural Network, originally designed for image segmentation, to identify raised river defences in DEMs. Using this defence dataset, we have been able to generate true river undefended flood maps for a selection of countries including Italy, Germany, Austria and the US. We present details of the methodology developed, the model training and the challenges faced when applying the model to different geographical regions.
Assessing UAV survey performance for geomorphological monitoring of mountain rivers
Authors: de Graffenried Bob , Pascal Ivan , Trewhela Tomas , Martinez Valentina , Ancey Christophe
Published: March 2020

Characterising morphological changes in mountain areas is of fundamental importance for science
and engineering. Intense floods usually involve massive sediment transport, which may significantly
alter basin and river characteristics. Sediment erosion and deposition control the dynamics
of morphological structures such as alternate bars and meanders. By using unmanned aerial vehicles
(UAV), it has been possible to obtain high-precision bed elevation data at the sediment scale.
Our project aims to develop a consistent and optimised methodology for monitoring morphological
changes in an Alpine watershed using an UAV. Since 2017, we have been monitoring the Plat de la
Lé area drained by the River Navisence (Zinal, canton Valais, Switzerland). In mountainous regions,
poor accessibility and light conditions make it difficult to set control points on the ground. We first
analysed the relevance and influence of certain ground control points (GCP) on the the accuracy of
the digital elevation model (DEM) obtained from the UAV’s images. Errors in the GCP localisation
were much larger than the DEM resolution. Not only did the GCP number and flight height affect
these errors, as expected, but their positions and orientations also played a part. We then carried
out an additional monitoring campaign to understand the influence of these parameters on the DEM
accuracy. This campaign was ran on two areas: a steep-slope area with irregular topography and
a low-slope area that comprises the river channel and its floodplain. We built DEMs for each area
considering different GCP numbers (in the 3–18 range with 14 additional checkpoints) and flight
heights (in the 40–140-m range). The present study provides guidelines, including an optimal combination
of parameters that significantly reduce errors in the DEM, and a methodology that can be
used for monitoring Alpine watersheds on a regular basis.
Modelling Antarctica’s lithospheric structure and testing the West Antarctic mantle plume hypothesis
Authors: Pappa Folker , Bredow Eva , Ebbing Jörg , Ferraccioli Fausto
Published: March 2020

Numerous unresolved issues exist regarding the lithosphere of Antarctica, especially in terms of its fundamental density, temperature, and compositional structure. Estimates of total lithospheric thickness typically involve assumptions on the depth of the Moho discontinuity, which remains ill-constrained in several parts of Antarctica. Recent estimates of the Moho depth from different geophysical methods show significant discrepancies of 10-20 km in large sectors of the continent. While seismological methods suffer from a limited station coverage and ice reverberation, potential field methods, such as gravity studies, are inherently non-unique. By modelling multiple geophysical parameters in a consistent way and accounting for thermodynamically stable mineral phases of rocks as a function of pressure and temperature conditions, we were able to mitigate the detrimental effects of data sparseness while also reducing geophysical inconsistencies and ambiguities. Gravity gradient data from ESA’s satellite mission ‘GOCE’ are used here to constrain the density distribution within the lithosphere in an integrated 3D model of the Antarctic continent. Independent seismic estimates serve as a benchmark for the robustness of our results. Our model derives new estimates of the crustal and the total lithospheric thickness of Antarctica.
Based on our new 3D lithospheric model, we investigate the feasibility of a mantle plume beneath parts of West Antarctica, which has been inferred from previous geochemistry, seismology, and glacial isostatic adjustment studies. The impact of thermal anomalies, simulating ponded plume material, on different geophysical parameters, such as geothermal heat flux, seismic velocities, mineral phase transition changes, gravity, and topographic elevation are modelled for both Marie Byrd Land and Ross Island, two key candidate sites for putative plumes. Combined interpretation of the results is performed together with current understanding of geodynamic processes, such as locations of the LLVPs at the core-mantle boundary, representing potential ‘cradles’ for plumes.
Our results suggest that a deep-rooted mantle plume is unlikely beneath West Antarctica. However, the observed low seismic velocity zones could still correspond to proposed hot upper mantle zones characterised by lower viscosity. Alternative/additional explanations, such compositional effects and water content as causes for the seismic anomalies must also be further evaluated to better assess their effects on mantle viscosities. This is particularly important beneath regions of recent ice mass loss and recently observed remarkably high rates of GIA-induced bedrock uplift, such as the Amundsen Sea Embayment.
Variability of fine-grained basin floor turbidites and evaluation of controls on their development: Late Pleistocene, Gulf of Corinth, Greece
Authors: Fabregas Natacha , Gawthorpe Robert , Ford Mary , Muravchik Martin , Pechlivanidou Sofia , Röhl Ursula
Published: March 2020

The Gulf of Corinth is one of the World’s fastest extending continental rift basins. During the Late Pleistocene, it alternated between marine and lacustrine conditions due to climate-driven sea-level fluctuations connecting or isolating/semi-isolating it from the open ocean. Core from IODP Expedition 381 (Corinth Active Rift Development) provide a continuous record of depositional processes operating within this deep-water rift and the interaction of tectonic and climate drivers controlling deep-water deposition over the Middle to Late Pleistocene. Subaqueous sediment density flows affect the Gulf of Corinth and are classified either by physical flow properties and grain support mechanisms or by depositional processes. Existing classifications mainly describe deposits from decimetre to 10’s of meter scale with an emphasis on sandy beds. Thinner (millimetre to centimetre scale) and finer (muddy to sandy) subaqueous sedimentary density flows beds are understudied. Low energy flows and tail of flow processes need a better understanding and are the target of this work. The aim of this study is to characterise the variability of fine-grained subaqueous sedimentary gravity flow deposits and the controls on their development based on core data from Site M0079 (IODP Expedition 381).  This site is located in the deepest part of the Gulf of Corinth (857 m water depth), in the most distal part of the sediment routing system. Analyses were performed within a 100 m interval covering Marine Isotope Stages 6 and 7 (from ~130 to ~250 ka). Detailed, sub-centimetre visual logging recorded over 2 000 beds classified according to (1) the presence/absence of a coarse base, (2) the grain-size (silty or sandy) of the base (if any), (3) the presence/absence of laminations within the muddy intervals, (4) sedimentary structures. The bed types reflect the diversity of the sedimentary processes and the subaqueous sediment density flows are thus organised within the depositional model. Bed frequency analysis provides insight into the variability between marine and lacustrine conditions. Relative chemical composition obtained from high resolution (2 mm) X-ray fluorescence scanning is used: (1) to examine the interactions between tail of the flow and background sedimentation in the basin and (2) to assess the provenance of the sediments.
Benefits of dynamically modelled river discharge input for ocean and coupled system.
Authors: Zuo Hao , de Boisseson Eric , Zsoter Ervin , Harrigan Shaun , de Rosnay Patricia , Wetterhall Fredrik , Prudhomme Christel
Published: March 2020

River freshwater input is crucial in modelling global ocean. Most ocean models used in CMEMS services rely on climatological river discharge data with various deficiencies, which can lead to biased simulated ocean states. The Copernicus Emergency Management Service (CEMS) Global Flood Awareness System (GloFAS) provides state-of-the-art global flood forecasts and downstream river discharge. A GloFAS-ERA5 global river discharge reanalysis dataset has been produced using the same system, modelled by routing runoff from ECMWF’s (European Centre for Medium- Range Weather Forecasts) atmospheric reanalysis ERA5 via a river network. As a global gridded data set that covers from 1979 to near-real-time, GloFAS-ERA5 reanalysis can provide an improved and standardized input of land freshwater input for global, regional and coastal ocean models. Evaluation results suggest that the overall performance of this new river discharge reanalysis is reasonably good in general when verified against a global network of 1801 discharge observation stations. A new method has been developed for conversion of the GloFAS-ERA5 reanalysis data into land freshwater input for the NEMO ocean model. This method has been tested with a climatology of GloFAS-ERA5 river discharge. Compared to the DRAKKAR climatology of land freshwater input (BT06, hereafter) used by most CMEMS services, this new data set has an increased global mean value of ~1.33 Sv, but with reduced seasonal variations. Assessment of this GloFAS-ERA5 land freshwater input has been carried out with the operational ECMWF ocean analysis system-OCEAN5, driven by the same ERA5 atmospheric forcing. Evaluation of simulated ocean state against in-situ observations show improvements in regions affected by Amazon freshwater input when use GloFAS-ERA5 instead of BT06, by reducing a negative sea surface salinity bias in these regions. However, negative impact from switching to GloFAS-ERA5 land freshwater input is also visible in several regions, e.g. in the Maritime Continent and west coast of central America, which is associated with a large positive bias in the GloFAS-ERA5 river discharge at these regions. This issue can be mitigated by applying bias-correction to the GloFAS-ERA5 land freshwater input, and by adding extra vertical mixing in several affected regions that are close to the river mouth. Assessments of module simulated ocean Essential Climate Variables (ECVs) have been carried out to quantify the benefit of this realistic freshwater time series input. Improvements in climate signals like the Atlantic Meridional Overturning transports is also recorded.
Epicontinental seas as efficient carbon sinks: proto-Paratethys & West Siberian seas during the PETM
Authors: Kaya Mustafa , Dupont-Nivet Guillaume , Frieling Joost , Fioroni Chiara , Rohrmann Alexander , Özkan Altıner Sevinç , Vardar Ezgi , Plessen Birgit , Mamtimin Mehmut , Zhaojie Guo
Published: March 2020

Removal of carbon on geological timescales is generally assumed to be governed by the relative strength of silicate weathering and organic carbon burial. For past transient warming phases organic carbon burial has been considered as a relevant negative feedback, but it remains uncertain how this compares to present-day anthropogenic emissions. The ocean is very effective at organic carbon remineralization and, only certain regions bury significant amounts of organic carbon. Organic carbon burial hotspots include shallow water regions along active continental margins and permanently oxygen-deficient zones.

Shallow inland seas covering continents bear depositional settings with broad low-energy facies and delivery of low-reactivity, fossil (ancient) and terrestrial (both contemporary and aged, i.e., soil) organic carbon and lithogenic particles when they are associated with an active margin. These epicontinental seas might be hydrographically and geographically restricted resulting in oxygen-depleted environments. As such, epicontinental seas might serve as significant carbon sinks for all types of organic carbon components (i.e. marine, fossil, contemporary and aged terrestrial) with a high organic carbon preservation efficiency. However, oxygen deficient environments associated with epicontinental seas are currently rare and, as a consequence, organic carbon burial may be overestimated in importance as a negative feedback to anthropogenic emissions compared to the past.

As part of the ERC “MAGIC” project, we study the mechanics, relative contribution and preservation efficiency of ancient epicontinental seas as carbon sinks, using organic rich deposits dated to the Paleocene – Eocene Thermal Maximum (PETM) from the proto-Paratethys and West Siberian seas. We then calculate and compare the amount of organic carbon sequestered in these basins, relative to modeled estimates of global organic carbon burial. Our data corroborates the view that the sequestration of organic carbon arises due to enhanced recycling of phosphorus from sediments under anoxic conditions and coupled increase in biological productivity. We estimate ca. 1380 Gt C burial, plausibly more than half of the estimated global total excess burial across the PETM is focused in the proto-Paratethys and West Siberian seas. This supports the hypothesis that alongside the organic carbon burial on other continental margins, the proto-Paratethys and West Siberian basins acted as significant carbon sinks, leading to the termination of the PETM. An important implication of this is that, for the present-day and other periods in the geological past with small epicontinental seas, the effectiveness of this negative carbon cycle feedback is likely greatly diminished.