bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Reservoir Storage Capacity Loss and Investigating the Effects of Climate Variability on Reservoir Sedimentation in Italy
Authors: Patro Epari Ritesh , Michele Carlo De
Published: March 2021

Reservoir sedimentation has a prominent impact on the hydropower performance in the future and is a growing concern for hydropower stakeholders. Sedimentation caused by soil erosion is influenced by various parameters. Reservoir sedimentation is one of the most challenging problems that affect hydroelectric production since it overall causes a reduction of the reservoir capacity that overcomes the annual increase in storage volume and implies a dangerous net loss of energy. The first part of this study examined various Italian reservoirs (50 dams) to determine sedimentation rates and storage capacity loss based on available bathymetric surveys. All the reservoirs studied here have reached an average age of 74 years as of 2019, with the highest loss of capacity observed at 90% and the highest annual sediment yield of 2471 m3/km2/year. Out of all the reservoirs studied, 25% of them already have reached their half-life as of 2019. The second part of this study extended the work to the specific case study of the Ceppo Morelli hydropower plant. The study was carried out to analyse the water-sediment interaction, future sediment load and prioritizing of critical soil erosion areas using the Soil and Water Assessment Tool (SWAT). The distinguishing feature of this work lies in the possibility to exploit remote sensing data (i.e. actual/potential evapotranspiration) to successfully calibrate hydrological models in scarce data regions. Simulation results indicated that the discharge and sediment load entering Ceppo Morelli reservoir will decline and the rate of reduction of latter is higher than that of former for all the future climate scenarios implemented. This analysis will provide a starting point for management and prioritization of adaptation and remediation policies for addressing the issue of reservoir sedimentation. These results are part of the RELAID project funded through PRIN-Italy. The aim of this project is to integrate updated knowledge on hydrologic, hydraulics, and sedimentation processes to address the water and flood risk management of impounded Italian rivers through a holistic paradigm.

Keywords: reservoir sedimentation; hydropower; hydrological modeling; RELAID; Italy
Combining sub-field scale soil sampling and GIS interpolation techniques for mapping nutrient hotspots 
Authors: Hayes Emma , Higgins Suzanne , Mullan Donal , Geris Josie
Published: March 2021

The EU Water Framework Directive (WFD) aims to target prevalent poor water quality status. Of the various contributing sources agriculture is particularly important due to the high loading rates of sediment and nutrient losses associated with fertilisation, sowing, and cropping regimes. Understanding soil nutrient status and the potential pathways for nutrient loss either through point or diffuse sources is an important step to improve water quality from an agricultural perspective. Research has demonstrated extensive in-field variability in soil nutrient status. A sampling regime that explores this variability at a sub-field scale is necessary. Traditional soil sampling consists of taking 20-30 cores per field in a W-shaped formation to produce a single bulked core, however, it generally fails to locate nutrient hotspots at finer resolutions. Inappropriate generalised fertilisation and management recommendations can be made in which nutrient hotspots or deficient zones are overlooked. Gridded soil sampling can reveal the full degree of in-field variability in nutrient status to inform more precise and site-specific nutrient applications. High soil phosphorus levels and the concept of legacy nutrient accumulation due to long-term over-application of phosphorus fertiliser in addition to animal slurry is a problem across the island of Ireland.

This research aims to locate and quantify the presence of soil nutrient hotspots at several field-scale locations in the cross-border Blackwater catchment in Northern Ireland / Republic of Ireland. Based on 35 m sampling grids, the nutrient content at unsampled locations in each field was determined using GIS interpolation techniques. Particular attention was paid to phosphorus, given its role in eutrophication. Gridded soil sampling enables the identification of nutrient hotspots within fields and when combined with an analysis of their location in relation to in-field landscape characteristics and knowledge of current management regimes, the risk of nutrient or sediment loss potential may be defined. This research concluded that traditional W soil sampling of producing one average value per field is not appropriate to uncover the degree of spatial variability in nutrient status and is inappropriate for catchment management of agricultural systems for controlling nutrient losses. Soil sampling at multiple locations per field is deemed to be cost-prohibitive for many farmers. However, sub-field scale soil sampling and appropriate geostatistical interpolation techniques can reveal the degree of variability and suggest an appropriate resolution for field-scale nutrient management that may be necessary to achieve measurable improvements in water quality.
Can we use the Curve Number approach to predict gully head occurrence at the continental scale of Africa?
Authors: De Geeter Sofie , Vanmaercke Matthias , Verstraeten Gert , Poesen Jean
Published: March 2021

Gully erosion is an important land degradation process, threatening soil and water resources worldwide. However, in contrast to sheet and rill erosion, our ability to simulate and predict gully erosion remains limited, especially at the continental scale. Nevertheless, such models are essential for the development of suitable land management strategies, but also to better quantify the role of gully erosion in continental sediment budgets. We aim to bridge this gap by developing a first spatially explicit and process-oriented model that simulates average gully erosion rates at the continental scale of Africa.

We are developing a model that predicts the likelihood of gully head occurrence by means of the Curve Number (CN) method. This model will allow to simulate the spatial patterns of gully density at high resolution (30m) based on the physical principles that control the gully erosion process by using GIS and spatial data sources that are available at the continental scale. To calibrate and validate this model, we make use of an extensive database of 44 000 gully heads mapped over 1680 sites that are randomly distributed across Africa. The exact location of all gully heads was manually mapped by trained experts, using high resolution optical imagery available in Google Earth. This allows to extract very detailed information at the level of the gully head, such as the local slope and the area draining to the gully.

Based on an explorative analysis on a subset of this dataset we found that the CN method does not directly allow to make reliable predictions on gully head occurrence within a pixel. Although land use and land cover seem to play an important role (with gully heads being clearly located in erosion-prone land use classes), the hydrological soil groups (HSGs) based on soil texture do not provide a clear relation between soils with high runoff risk and gully occurrence. A potential cause for this is likely that compensating soil effects occur: i.e. HSGs that produce low runoff volumes may be characterized by a lower soil cohesion, making them nonetheless prone to gullying. This may then cause the combination of HSG and land use to be an insignificant predictor of gully occurrence. Also uncertainties on the input data likely play an important role in this.

Overall, our results indicate that modelling gully densities using a process-oriented and spatially explicit method offers opportunities to better quantify this important land degradation process at the global scale. Nevertheless, a key challenge lies in accurately quantifying the importance of soil characteristics and especially in better understanding their relative contribution to runoff production and soil cohesion.
Estimation of land surface key parameters for the study of energy and water cycle over the Tibetan Plateau based on geostationary and polar orbiting satellites
Authors: Zhong Lei , Ma Yaoming , Su Zhongbo , Ma Weiqiang , Hu Zeyong , Han Cunbo
Published: March 2021

Estimation of land surface characteristic parameters and turbulent heat fluxes is important for energy and water cycle studies, especially on the Tibetan Plateau (TP), where the topography is unique and the land-atmosphere interactions are strong. The land surface heating conditions also directly influence the movement of atmospheric circulation. However, high temporal resolution information on the plateau-scale land surface parameters has lacked for a long time, which significantly limits the understanding of diurnal variations in land-atmosphere interactions. On the other hand, how to remove cloud effects for optical satellite images is another important research issue. Based on Chinese FY geostationary satellite data and other polar orbiting satellite data, the hourly land surface characteristic parameters and turbulent heat fluxes were estimated. A new cloud‐free time series of vegetation index data sets was reconstructed, and the vegetation density showed a general increasing trend along with a warming trend in the TP. The regions showing significant increases accounted for 7.63% of the total Tibetan territory. Downwelling shortwave and longwave radiation parameterization schemes were improved to derive all-sky radiation over the TP. The diurnal and seasonal cycles of the land surface parameters were clearly identified, and their spatial distribution was found to be consistent with the heterogeneous land surface conditions and the general hydrometeorological conditions of the TP.
Twenty-First Century Trends in Mixing Barriers and Eddy Transport in the Lower Stratosphere
Authors: Abalos Marta , de la Cámara Alvaro
Published: March 2021

Future trends in isentropic mixing in the lower stratosphere remain largely unexplored, in contrast with the advective component of the Brewer-Dobson circulation. This study examines trends in effective diffusivity (κeff ), a measure of the potential of the flow to produce isentropic mixing, in recent chemistry-climate model simulations. The results highlight substantial reduction of κeff  in the upper flanks of the subtropical jets from fall to spring, which are strengthened in response to greenhouse gas increases. This contrasts with stronger eddy transport, associated with increased wave drag in the region, peaking in summer near the critical lines. The projected ozone recovery leads to enhanced κeff in polar austral spring and summer, associated with a weaker and shorter-lived austral polar vortex by the end of the 21st century.
The igneous plumbing system of the Early Permian Bolzano/Bozen supervolcano (North-eastern Italy)
Authors: Boscaini Andrea , Davies Joshua H.F.L. , Sassi Raffaele , Mazzoli Claudio , Callegaro Sara , De Min Angelo , Marzoli Andrea
Published: March 2021

Early Permian Post-Variscan magmatism is widespread throughout the Alps and consists mainly of felsic to mafic plutonic and volcanic bodies emplaced between ca. 285 and 275 Ma. This study focuses on the acidic to intermediate intrusions in the areas of Trento and Bolzano/Bozen (North-eastern Italy) like the Cima d’Asta gabbrodiorite/granite, the Pergine granodiorite, the Monte Sabion and the Bressanone (Brixen) granites. New U-Pb zircon data along with ages for the Ivigna (Ifinger) and Monte Croce (Kreuzberg) granites and the Bressanone (Brixen) gabbro constrain the age of the Permian intrusions and Hf isotopic data highlight the interaction between mantle-derived melts and crustal rocks during ascent of the former through the crust. Moreover, the studied intrusions represent the shallow crustal plumbing system of the coeval widespread volcanics of the Athesian Volcanic Group and the mega-caldera of the Bolzano/Bozen supervolcano. This acid intrusive-extrusive magmatism, which identified an elliptic structure of more than 4200 square kilometers, represents the biggest magmatic event outcropping in the Southern Alps and likely influenced the ecosystems of the Athesian Volcanic District and of the dolomitic area l.s. during the Permian.
The role of heat-flux–temperature covariance in the evolution of weather systems
Authors: Marcheggiani Andrea , Ambaum Maarten
Published: March 2021

Local diabatic heating and temperature anomaly fields need to be positively correlated for the diabatic heating to maintain a circulation against dissipation. Here we quantify the thermodynamic contribution of local air–sea heat exchange on the evolution of weather systems using an index of the spatial covariance between heat flux at the air–sea interface and air temperature at 850 hPa upstream of the North Atlantic storm track, corresponding with the Gulf Stream extension region. The index is found to be almost exclusively negative, indicating that the air–sea heat fluxes act locally as a sink on potential energy. It features bursts of high activity alternating with longer periods of lower activity. The characteristics of these high-index bursts are elucidated through composite analysis and the mechanisms are investigated in a phase space spanned by two different index components. It is found that the negative peaks in the index correspond with thermodynamic activity triggered by the passage of a weather system over a spatially variable sea-surface temperature field; our results indicate that most of this thermodynamically active heat exchange is realised within the cold sector of the weather systems. Finally, we will discuss the implications of our findings, including a link with meridional heat flux pulses and a novel way of understanding whether such pulses are due to enhanced correlations or enhanced variances.
Increasing rock phosphate efficient use through soil amendment with waste biomasses
Authors: Piscitelli Lea , Bennani Zineb , Mondelli Donato
Published: March 2021

Loss of soil organic carbon content can limit the soil's ability to provide goods and services. In agricultural soil this may lead to lower yields and affect food security. In this context, the proper use of waste biomasses as soil amendment is a valuable alternative to disposal with numerous benefits to soil fertility with a direct effect on soil organic matter content. Moreover, beside this direct effect waste biomasses can have a beneficial result on nutrients.

In modern agriculture the use of rock phosphate as fertilizer is crucial but abused. Although this non-renewable resource reserves may be depleted in 50-100 years, many farmers still use overabundant amount of rock phosphate-based fertilizers with an additional environmental burden. From a chemical point of view the efficient use of rock phosphate can be increased by some agricultural practices and amending soil with waste biomasses is one of them.

Here we propose the use of 3 different waste biomasses on phosphate rock dissolution and subsequent phosphorus availability. The 3 waste biomasses, citrus pomace, olive oil mill waste and barley spent grains, were selected mainly for their potential direct or indirect effect on pH. This experiment was composed by two steps a bench and a pot trial. In the bench trial the waste biomasses and phosphate rock were mixed and transferred in litterbags. In these litterbags pH, water soluble P, matter loss and total P were destructively analyzed each 10 days for a month. In the pot trial the same combination of waste biomasses and phosphate rock were tested in a soil plant system; some agronomic parameters were measured on rocket salad and pH, soil-P availability, acid phosphatase activity were analyzed in soil.

In bench trial, barley spent grain plus phosphate rock shows the highest water soluble P, citrus pomace plus phosphate rock showed a significant correlation between water soluble P and pH while olive oil mill waste plus phosphate rock has high correlation between water soluble P and matter loss. These two treatments were also the best performing in the pot trial in terms of rocket salad yield and soil available P. Even though the investigation was conducted on a short lived experiment, some results are encouraging and displays good agronomic performances of waste biomasses plus phosphate rock. Nevertheless, next studies should consider other waste biomasses within longer experiments. Additionally, scaling up the experiment to a field application can provide more thorough information about the effects on soil organic carbon and P dynamics.
A conceptual model for the estimation of flood damage to power grids
Authors: Asaridis Panagiotis , Molinari Daniela , Ballio Francesco
Published: March 2021

Flood damage assessment is a crucial component of any decision-making process on flood risk management and mitigation; for this reason, reliable tools for flood damage estimation are required, for all the categories of exposed elements. Despite networks can suffer high losses in case of flood, and in comparison with other exposed items, flood damage modelling to infrastructures is still a challenging task. This is due, on the one hand, to the complexity of networks as well as of their interconnections; on the other hand, to the lack of knowledge and data to investigate damage mechanisms and to calibrate and validate damage models. Grounding on the investigation of the state of art, this contribution presents a conceptualization of flood damage to power grids. The ultimate objective of the conceptual model is to be an operative tool in support of more comprehensive and reliable flood damage assessments to power grids, highlighting: (i) the different components of the damage (i.e. direct, indirect, and systemic, meaning damage due to the interdependencies among power grids and residential, commercial, industrial and other infrastructure sectors), (ii) their interconnections, (iii) the hazard, exposure and vulnerability variables on which they depend, (iv) the temporal and spatial scales for their assessment. The development of the model highlighted, on the one hand, the importance of dividing damage assessment in two steps: the estimation of damage in quantitative/physical units and the estimation of the consequent economic losses. On the other hand, the variety of damage mechanisms and cascading effects shaping the final damage figure arises, asking for an interdisciplinary and multi-scale evaluation approach. The development of the conceptual model is the first step of a PhD research on the development of flood damage models for infrastructures. Next steps will validate the model in real case studies and evaluate how the different damage components could be investigated in the Italian context.
Validation of Using SWARM to Fill-in the GRACE/GRACE-FO Gap: Case Study in Africa
Authors: Mohasseb Hussein , Abd-Elmotaal Hussein A , Shen WenBin
Published: March 2021

The American/German missions Gravity Recovery and Climate Experiment (GRACE) and the GRACE Follow-On (GRACE-FO) and the European mission (Swarm) play an important role in study of the Earth's gravity field with unprecedented high-precision and high-resolution measurements. The aim of this study is to use Swarm data to fill-in the data-gap between GRACE and GRACE-FO missions from July 2017 to May 2018, and evaluate the new datasets in Africa. We used the available data from the triple GRACE processing centers CSR, GFZ and JPL, in addition to the Swarm TVGF data provided by the Czech Academy of Sciences (ASU) and the International Combination Service for Time-variable Gravity (COST-G). The GRCAE and Swarm date have been tested in the frequency and space domains. For the frequency domain, the data assessed in two different levels: the potential degree variances and the harmonic coefficients themselves. The results show consistency between GRACE/GRACE-FO and Swarm for all processing centers. In the space domain, a comparison between GRACE/GRACE-FO and Swarm for the TWS, gravity anomaly, and the potential/geoid have been carried out. For the TWS, an artificial gap (AG) - simulating the gap between GRACE and GRACE-FO – has been artificially made in the GRACE data from July 2015 to May 2016. The GRACE AG has been filled by the two sets of the Swarm data for CSR, GFZ and JPL. The results indicated that the best agreement has been achieved between GRACE-CSR and Swarm COST-G. For the gravity anomaly and the potential/geoid, a better agreement between GRACE and Swarm data has been concluded. Eventually, we chose Swarm COST-G data to fill-in the gap between GRACE and GRACE-FO CSR in order to be used, among others, to estimate the TWS in Africa for the period from April 2002 to October 2020. This study is supported by the National Natural Science Foundations of China (NSFC) under Grants Nos. 42030105, 41721003, 41804012, 41631072, and 41874023.
OSNAP and water mass transport in CMIP6 models
Authors: Jackson Laura
Published: March 2021

The Atlantic Meridional Overturning Circulation (AMOC) influences our climate by transporting heat northwards in the Atlantic ocean. The subpolar North Atlantic plays an important role in this circulation, with transformation of water to higher densities, deep convection and formation of deep water. Recent OSNAP observations have shown that the overturning is stronger to the east of Greenland than the west.

Here we analyse a CMIP6 climate model at two resolutions (HadGEM3 GC3.1 LL and MM) and show both compare well with the OSNAP observations. We explore the source of low frequency variability of the AMOC and how it is related to the surface water mass transformation in different regions. We also investigate time-mean and low frequency water mass transformations in other CMIP6 climate models.
Sea surface height anomaly of the ice-covered oceans from ICESat-2 and CryoSat-2
Authors: Bagnardi Marco , Kurtz Nathan , Petty Alek , Kwok Ron
Published: March 2021

Rapid changes in Earth’s sea ice and land ice have caused significant disruption to the polar oceans in terms of fresh water storage, ocean circulation, and the overall energy balance. While we can routinely monitor, from space, the ocean surface at lower latitudes, measurements of sea surface in the ice-covered oceans remains challenging due to sampling deficiencies and the need to discriminate returns between sea ice and ocean.

The European Space Agency’s (ESA) CryoSat-2 satellite has been acquiring unfocussed synthetic aperture radar altimetry data over the polar regions since 2010, providing a key breakthrough in our ability to routintely monitor the ice-covered oceans. Since October 2018, NASA’s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) and its onboard Advanced Topographic Laser Altimeter (ATLAS) have provided new measurements of sea ice and sea surface elevations over similar polar regions. With over two years of overlapping data, we now have the opportunity to compare coincident sea surface height retrievals from the two missions and assess potential elevation differences over two entire freeze-melt cycles across both polar oceans .

Also, as of August 2020, CryoSat-2’s orbit has been modified as part of the CRYO2ICE campaign, such that every 19 orbits (20 orbits for ICESat-2) the two satellites align for hundreds of kilometers over the Arctic Ocean, acquiring data along coincident ground tracks with a time difference of approximately three hours.

In this work, we compare sea surface height anomaly (SSHA) retrievals from CryoSat-2 (Level 1b and Level 2 data) and  ICESat-2 (Level 3a data, ATL10). We apply a recently updated waveform fitting method to the CryoSat-2 waveform data (Level 1b) to determine the retracking corrections,  based on Kurtz et al. (2014). We apply the same mean sea surface adjustment used for ICESat-2 to CryoSat-2 data, and we apply similar geophysical and atmospheric corrections to both datasets.

While we find an overall good agreement between the two datasets, some discrepancies between CryoSat-2 and ICESat-2 SSHA estimates remain. In this work we explore the potential causes of these discrepancies, related to both lead finding/distribution, and range biases.

 
Forced solitary waves over complex topography
Authors: Makarenko Nikolay , Denisenko Danila
Published: March 2021

In present paper we consider the problem on solitary waves forced by a chain of gently sloped obstacles of small height. Steady two-dimensional free-surface flows over a complex topography are studied analytically in the case when the far upstream flow is slightly supercritical. Small height- and steepness restrictions are important here since these circumstances provide the balance between nonlinear dispersion and hydraulic effects both affecting nearly hydrostatic non-uniform flow. Fully non-linear irrotational Euler equations are formulated via the von Mises transformation that parametrizes the family of streamlines in a curvilinear flow domain. It is well known that the critical value of the Froude number is the bifurcation point providing non-uniqueness of stationary flow. In present work, we construct and analyze approximate solitary-wave solutions by using long-wave expansion procedure with two small parameters.  In addition, we apply the Lyapunov - Schmidt method which ensures an analytical condition of the wave-trapping formulated in terms of the Melnikov function. A specific class of multi-bumped topographies is considered in order to demonstrate multiplicity of forced waves. The amount of different wave regimes depends on the number of bumps and pits, as well as on their location and size in relation to each other.
Lithospheric structure of the Iberian Central System (Iberian Massif) imaged by the wide-angle seismic reflection/refraction CIMDEF experiment 
Authors: DeFelipe Irene , Ayarza Puy , Palomeras Imma , Andrés Juvenal , Ruiz Mario , Alcalde Juan , Martinez Poyatos David , Gonzalez-Lodeiro Francisco , Yenes Mariano , Torne Montserrat , Carbonell Ramon
Published: March 2021

The Iberian Central System represents an outstanding topographic feature in the central Iberian Peninsula. It is an intraplate mountain range formed by igneous and metasedimentary rocks of the Variscan Iberian Massif that has been exhumed since the Eocene in the context of the Alpine orogeny. The Iberian Central System has been conventionally interpreted as a thick-skinned pop-up mountain range thrust over the Duero and Tajo foreland basins. However, its lithospheric structure and the P-wave velocity distribution are not yet fully resolved. In order to place geophysical constraints on this relevant topographic feature, to identify lithospheric discontinuities, and to unravel the crustal deformation mechanisms, a wide-angle seismic reflection and refraction experiment, CIMDEF (Central Iberian Mechanism of DEFormation), was acquired in 2017 and 2019. It is a NNW-SSE oriented 360-km long profile that runs through the Duero basin, the Iberian Central System and the Tajo basin. First results based on forward modeling by raytracing show an irregularly layered lithosphere and allow to infer the depth extent of the northern Iberian Central System batholith. The crust is ~ 31 km thick under the Duero and Tajo basins and thickens to ~ 39 km under the Iberian Central System. A conspicuous thinning of the lower crust towards the south of the Iberian Central System is also modeled. Along this transect, a continuous and high amplitude upper mantle feature is observed and modeled as the reflection of an interface dipping from 58 to 62 km depth featuring a P-wave velocity contrast of 8.2 to 8.3 km/s. Our preliminary results complement previous models based on global-phase seismic and noise interferometry and gravity data, provide new constraints to validate the accuracy of passive seismic methods at lithospheric scale, and contribute with a resolute P-wave velocity model of the study area to unravel the effect of the Alpine reactivation on the central Iberian Massif.
This project has been funded by the EIT-RawMaterials 17024 (SIT4ME) and the MINECO projects: CGL2016-81964-REDE, CGL2014-56548-P.
High-latitude crochet (Solar flare effect) as a trigger of pseud-substorm onset
Authors: Yamauchi Masatoshi , Johnsen Magnar , Othani Shin-Ichi , Sormakov Dmitry
Published: March 2021

Solar flares are known to enhance the ionospheric electron density and thus influence the electric currents in the D- and E-region.  The geomagnetic disturbance caused by this current system is called a "crochet" or "SFE (solar flare effect)".  Crochets are observed at dayside low-latitudes with a peak near the subsolar region ("subsolar crochet"), in the nightside high-latitude auroral region with a peak where the geomagnetic disturbance pre-exists during solar illumination ("auroral crochet"), and in the cusp ("cusp crochet").  In addition, we recently found a new type of crochet on the dayside ionospheric current at high latitudes (European sector 70-75 geographic latitude/67-72 geomagnetic latitude) independent from the other crochets.  The new crochet is much more intense and longer in duration than the subsolar crochet and is detected even in AU index for about half the >X2 flares despite the unfavorable latitudinal coverage of the AE stations (~65 geomagnetic latitude) to detect this new crochet (Yamauchi et al., 2020).  

The signature is sometime s seen in AL, causing the crochet signature convoluting with substorms.  From a theoretical viewpoint, X-flares that enhances the ionospheric conductivity may influence the substorm activity, like the auroral crochet.  To understand the substorm-crochet relation in the dayside, we examined SuperMAG data for cases when the onset of the substorm-like AL (SML) behavior coincides with the crochet.  We commonly found a large counter-clockwise ∆B vortex centered at 13-15 LT, causing an AU peak during late afternoon and an AL peak near noon at higher latitudes than the high-latitude crochet.  In addition, we could recognize a clockwise ∆B vortex in the prenoon sector, causing another poleward ∆B, but this signature is not as clear as the afternoon vortex.  With such strong vortex features, it becomes similar to substorms except for its local time.  In some cases, the vortex expends to the nightside sector, where and when nightside onset starts, suggesting triggering of onset.  Thus, the crochet may behave like pseudo-onset at different latitude than midnight substorms, and may even trigger substorm onset.
On the uncertainty of real-time predictions of epidemic growths: A COVID-19 case study for China and Italy
Authors: Alberti Tommaso , Faranda Davide
Published: March 2021

While COVID-19 is rapidly propagating around the globe, the need for providing real-time forecasts of the epidemics pushes fits of dynamical and statistical models to available data beyond their capabilities. Here we focus on statistical predictions of COVID-19 infections performed by fitting asymptotic distributions to actual data. By taking as a case-study the epidemic evolution of total COVID-19 infections in Chinese provinces and Italian regions, we find that predictions are characterized by large uncertainties at the early stages of the epidemic growth. Those uncertainties significantly reduce after the epidemics peak is reached. Differences in the uncertainty of the forecasts at a regional level can be used to highlight the delay in the spread of the virus. Our results warn that long term extrapolation of epidemics counts must be handled with extreme care as they crucially depend not only on the quality of data, but also on the stage of the epidemics, due to the intrinsically non-linear nature of the underlying dynamics. These results suggest that real-time epidemiological projections should include wide uncertainty ranges and urge for the needs of compiling high-quality datasets of infections counts, including asymptomatic patients.

Alberti T. and Faranda D. (2020) On the uncertainty of real-time predictions of epidemic growths: A COVID-19 case study for China and Italy. Commun. Nonlin. Sci. Num. Sim., 90, 105372.
Transport Schemes in GungHo
Authors: Kent James
Published: March 2021

GungHo is the mixed finite-element dynamical core under development by the Met Office. A key component of the dynamical core is the transport scheme, which advects density, temperature, moisture, and the winds, throughout the atmosphere. Transport in GungHo is performed by finite-volume methods, to ensure conservation of certain quantaties. There are a range of different finite-volume schemes being considered for transport, including the Runge-Kutta/method-of-lines and COSMIC/Lin-Rood schemes. Additional horizontal/vertical splitting approaches are also under consideration, to improve the stability aspects of the model. Here we discuss these transport options and present results from the GungHo framework, featuring both prescribed velocity advection tests and full dry dynamical core tests. 
Simplified simulation of rock avalanches and subsequent debris flows with a single thin-layer model. Application to the Prêcheur river (Martinique, Lesser Antilles)
Authors: Peruzzetto Marc , Levy Clara , Thiery Yannick , Grandjean Gilles , Mangeney Anne , Lejeune Anne-Marie , Nachbaur Aude , Legendre Yoann , Vittecoq Benoit , Saurel Jean-Marie , Clouard Valérie , Dewez Thomas , Fontaine Fabrice R. , Mergili Martin , Lagarde Sophie , Komorowski Jean-Christophe , Le Friant Anne , Lemarchand Arnaud
Published: March 2021

This work focuses on the use of thin-layer models for simulating fast gravitational flows for hazard assessment. Such simulations are sometimes difficult to carry out because of the uncertainty on initial conditions and on simulation parameters. In this study, we aggregate various field data to constrain realistic initial conditions and to calibrate the model parameters. By using the SHALTOP numerical code, we choose a simple and empirical rheology to model the flow (no more than two parameters), but we model more finely the geometrical interactions between the flow and the topography. We can thus model both a rock avalanche, and the subsequent remobilization of the deposits as a high discharge debris flow.

Using the Prêcheur river catchment (Martinique, Lesser Antilles) as a case study, we focus on extreme events with a high potential to impact populations and infrastructures. We use geological and geomorphological data, topographic surveys, seismic recordings and granulometric analysis to define realistic simulation scenarios and determine the main characteristics of documented events. The latter are then reproduced to calibrate rheological parameters. With a single rheological parameter and the Coulomb rheology, we thus model the emplacement and main dynamic characteristics of a recent rock avalanche, as well as the travel duration and flooded area of a documented high discharge debris flow. Then, in a forward prediction simulation, we model a possible 1.9x106 m3 rock avalanche, and the instantaneous remobilization of the resulting deposits as a high-discharge debris flow. We show that successive collapses allow to better reproduce the dynamics of the rock avalanche, but do not change the geometry of the final deposits, and thus do not influence the initial conditions of the subsequent debris flow simulation. A progressive remobilization of the materials slows down the debris flow and limits overflow, in comparison to instantaneous release. However, we show that high discharge debris flows, such as the one considered for model calibration, are better reproduced with an instantaneous initiation. The range of travel times measured for other significant debris flows in the Pr\^echeur river is consistent with our simulation results, with various rheological parameters and the Coulomb or Voellmy rheology.
Local and remote Southern Hemisphere extratropical circulation responses to soil moisture anomalies in Australia
Authors: Romppainen-Martius Olivia , Wehrli Kathrin , Rohrer Marco
Published: March 2021

Hemisphere-wide remote Rossby wave responses of the upper-level flow to soil moisture anomalies have been reported for the Northern Hemisphere. Model experiments varying soil moisture over North America point to the involvement of both linear and non-linear wave dynamics. Here three sets of model experiments are performed with the Community Earth System Model to study the role of soil moisture anomalies as a boundary forcing for the formation of extra-tropical upper-level Rossby wave patterns during Southern Hemisphere summer.

In the model experiments, soil moisture over Australia is set to +1STD (wet) and to -1STD (dry) of the ERA-Interim reanalysis climatology for the years 2009 to 2016. With his set-up 50 ensemble members are run and the wet and dry simulations compared. The local response to the soil moisture forcing is a positive heating anomaly in the dry simulations that results in a thermal low-like circulation anomaly with an anomalous surface low and an anomalous upper-level anticyclone.

A circum-hemispheric flow response is identified both in the extra-tropical upper-level flow and in the surface storm tracks that overall resembles a positive Southern Annular Mode-like flow anomaly in the dry simulations. The structure of this atmospheric response strongly depends on the background flow. During two El Niño summers the response is strongly influenced by nonlinear Rossby wave forcing, while during two La Niña summers the flow response resembles a circum-hemispheric wave train reflecting linear wave propagation.
Plants and river morphodynamics
Authors: Gurnell Angela
Published: March 2021

Research within the field of fluvial biogeomorphology focuses on the impact of organisms, particularly plants, on physical processes and landform development within river environments. This research field has evolved and matured over 50 years such that strong links between plants and river morphodynamics are now established and are increasingly becoming embedded in river management practices.

In this presentation, I provide a personal perspective on the evolution of fluvial biogeomorphology, emphasising five parallel research themes that were initiated in different decades. Research within these themes continues and combines to underpin our current state of knowledge:

The 1970s       Natural vegetation colonises areas according to the degree of river disturbance such that certain plant communities are associated with particular river landforms.

The 1980s       Dead wood pieces influence river morphodynamics and support the development of particular assemblages of physical habitats.

The 1990s       Some large wood sprouts: dead and living trees drive a geomorphological continuum.

The 2000s       River and riparian forest dynamics are linked: field observations, laboratory experiments and numerical models converge.

The 2010s       Many riparian and aquatic plant species can act as river engineers: local engineer species reflect the environmental setting.

2020 onwards    Increasing integration: understanding how interactions between plants and rivers adjust with changes in the biogeographical setting, plant species pool and river energy.
Ground motion detection in Central South Asturias (N Spain) by using Sentinel-1 SAR data
Authors: Cuervas-Mons Jose , Domínguez-Cuesta María José , Mateos-Redondo Félix , Monserrat Oriol , Barra Anna
Published: March 2021

In this work, the A-DInSAR techniques are applied in a mountainous area located in the Central South of Asturias (N Spain), where there are significant landslide and subsidence phenomena. The main aim of this study is detecting and analysing ground deformations associated to slope instabilities and subsidence processes. For this, 113 SAR images, provided by Sentinel-1A/B between January 2018 and February 2020, were acquired and processed by means of PSIG software (developed by the Geomatics Division of the CTTC). The results show a velocity range between -18.4 and 10.0 mm/year, and minimum and maximum accumulated ground displacements of -35.0 and 17.5 mm. This study has made possible to differentiate local sectors with recent deformation related to landslide incidence, urban/mining subsidence, and land recuperation due to aquifer recharge. This work corroborates the reliability and usefulness of the A-DInSAR processing as a powerful tool in the study and analysis of geological hazards on regional and local scales using Sentinel-1 data collection, showing also the high difficulty of processing mountainous areas with few urban sectors.
Post-processing numerical weather prediction ensembles for probabilistic solar irradiance forecasting
Authors: Lerch Sebastian , Schulz Benedikt , El Ayari Mehrez , Baran Sándor
Published: March 2021

In order to enable the transition towards renewable energy sources, probabilistic energy forecasting is of critical importance for incorporating volatile power sources such as solar energy into the electrical grid. Solar energy forecasting methods often aim to provide probabilistic predictions of solar irradiance. In particular, many hybrid approaches combine physical information from numerical weather prediction models with statistical methods. Even though the physical models can provide useful information at intra-day and day-ahead forecast horizons, ensemble weather forecasts from multiple model runs are often not calibrated and show systematic biases. We propose a post-processing model for ensemble weather predictions of solar irradiance at temporal resolutions between 30 minutes and 6 hours. The proposed models provide probabilistic forecasts in the form of a censored logistic probability distribution for lead times up to 5 days and are evaluated in two case studies covering distinct physical models, geographical regions, temporal resolutions, and types of solar irradiance. We find that post-processing consistently and significantly improves the forecast performance of the ensemble predictions for lead times up to at least 48 hours and is well able to correct the systematic lack of calibration.
Subduction initiation in the Scotia Sea region and opening of the Drake Passage: when and why?
Authors: van de Lagemaat Suzanna , Swart Merel , Vaes Bram , Kosters Martha , Boschman Lydian , Burton-Johnson Alex , Bijl Peter , Spakman Wim , van Hinsbergen Douwe
Published: March 2021

During evolution of the South Sandwich subduction zone, which has consumed South American plate oceanic lithosphere, somehow continental crust of both the South American and Antarctic plates have become incorporated into its upper plate. Continental fragments of both plates are currently separated by small oceanic basins in the upper plate above the South Sandwich subduction zone, in the Scotia Sea region, but how fragments of both continents became incorporated in the same upper plate remains enigmatic. Here we present an updated kinematic reconstruction of the Scotia Sea region using the latest published marine magnetic anomaly constraints, and place this in a South America-Africa-Antarctica plate circuit in which we take intracontinental deformation into account. We show that a change in fracture zone orientation in the Weddell Sea requires that previously inferred initiation of subduction of South American oceanic crust of the northern Weddell below the eastern margin of South Orkney Islands continental crust, then still attached to the Antarctic Peninsula, already occurred around 80 Ma. We propose that subsequently, between ~71-50 Ma, the trench propagated northwards into South America by delamination of South American lithosphere: this resulted in the transfer of delaminated South American continental crust to the overriding plate of the South Sandwich subduction zone. We show continental delamination may have been facilitated by absolute southward motion of South America that was resisted by South Sandwich slab dragging. Pre-drift extension preceding the oceanic Scotia Sea basins led around 50 Ma to opening of the Drake Passage, preconditioning the southern ocean for the Antarctic Circumpolar Current. This 50 Ma extension was concurrent with a strong change in absolute plate motion of the South American Plate that changed from S to WNW, leading to upper plate retreat relative to the more or less mantle stationary South Sandwich Trench that did not partake in the absolute plate motion change. While subduction continued, this mantle-stationary trench setting lasted until ~30 Ma, after which rollback started to contribute to back-arc extension. We find that roll-back and upper plate retreat have contributed more or less equally to the total amount of ~2000 km of extension accommodated in the Scotia Sea basins. We highlight that viewing tectonic motions in a context of absolute plate motion is key for identifying slab motion (e.g. rollback, trench-parallel slab dragging) and consequently mantle-forcing of geological processes.
Lithospheric architecture of the Ligurian Basin from seismic travel time tomography
Authors: Dannowski Anke , Kopp Heidrun , Grevemeyer Ingo , Caielli Grazia , de Franco Roberto , Lange Dietrich , Thorwart Martin , Filbrandt Christian , msm71 Cruise participants , Working Group AlpArray
Published: March 2021

The Ligurian Basin is located north-west of Corsica at the transition from the western Alpine orogen to the Apennine system. The Back-arc basin was generated by the southeast retreat of the Apennines-Calabrian subduction zone. The opening took place from late Oligocene to Miocene. While the extension led to extreme continental thinning little is known about the style of back-arc rifting. Today, seismicity indicates the closure of this back-arc basin. In the basin, earthquake clusters occur in the lower crust and uppermost mantle and are related to re-activated, inverted, normal faults created during rifting.

To shed light on the present day crustal and lithospheric architecture of the Ligurian Basin, active seismic data have been recorded on short period ocean bottom seismometers in the framework of SPP2017 4D-MB, the German component of AlpArray. An amphibious refraction seismic profile was shot across the Ligurian Basin in an E-W direction from the Gulf of Lion to Corsica. The profile comprises 35 OBS and three land stations at Corsica to give a complete image of the continental thinning including the necking zone.

The majority of the refraction seismic data show mantle phases with offsets up to 70 km. The arrivals of seismic phases were picked and used to generate a 2-D P-wave velocity model. The results show a crust-mantle boundary in the central basin at ~12 km depth below sea surface. The P-wave velocities in the crust reach 6.6 km/s at the base. The uppermost mantle shows velocities >7.8 km/s. The crust-mantle boundary becomes shallower from ~18 km to ~12 km depth within 30 km from Corsica towards the basin centre. The velocity model does not reveal an axial valley as expected for oceanic spreading. Further, it is difficult to interpret the seismic data whether the continental lithosphere was thinned until the mantle was exposed to the seafloor. However, an extremely thinned continental crust indicates a long lasting rifting process that possibly did not initiate oceanic spreading before the opening of the Ligurian Basin stopped. The distribution of earthquakes and their fault plane solutions, projected along our seismic velocity model, is in-line with the counter-clockwise opening of the Ligurian Basin.