bluuebunny/crossref_metadata_2025 huggingface dataset:
Delayed and altered post-fire recovery pathways of Mediterranean shrubland under 20-year drought manipulation
Authors: Liu Daijun , Zhang Chao , Pugh Thomas , Penuelas Josep
Published: March 2021

Increasing anthropogenic and natural disturbances have disturbed 75% of global land area, indicating many plant communities are unstable or in recovery process. Increasing water deficits by rainfall reduction may decrease resilience (rate of recovery) and trigger different succession pathways (e.g. delayed, altered mature status and advanced degradation). Knowledge on the effects of future drought on community structure and demographic dynamics is key to project the fate of vegetation and yet it is limited. 

Here we assessed the impacts of long-term (20 years) experimental drought (-30% rainfall) on the successional pathways of species diversity, community composition and demographic changes for an early-successional Mediterranean shrubland (4 years after a wildfire). The results indicated that experimental drought significantly decreased species richness and shifted community composition compared to control plots. Significant decreases in abundance and increases in death ratios at both community (all species) and shrub (shrub species) levels were found in experimental drought. However, the abundance of Globularia Alypum was significantly increased by drought while Erica multiflora was not affected; the death ratios for the two species were significantly lower in drought than control plots. Species richness, community composition and abundance followed pathway 2 (altered mature state) while shrubland abundance followed pathway 3 (advanced degradation). Principal Component Analysis (PCA) indicated that the variance in vegetation metrics was notably explained by the first two dimensions (49.4%), mainly related to the death ratio of G. alypum and E. multiflora (27.3% for PC1) and abundance of community and shrub levels (22.1% for PC2). The space variation in PC1 significantly increased over time, which was orthogonal with PC2. Within two dimensions of PC1 and PC2, the scores in control were significantly higher than drought. 

Our findings suggest that drier condition simulated by long-term drought could delay and alter the succession pathways of species diversity, community composition and abundance of the plant communities in Mediterranean ecosystems. The results also imply the importance to analyse long-term drought and extreme events on ecosystem functions (the strength of carbon storage in vegetation and soil) for such recovering communities.
Deep Borehole Repository of HLW and SF - State of knowledge by SITEX.Network
Authors: Zeleznik Nadja , Richer Muriel , Wales Colin , Bernier Frédéric , Karastanev Doncho , Pfingsten Wilfried
Published: March 2021

Many countries develop geological disposal projects for high-level radioactive waste (HLW) and/or spent fuel (SF) when considered as waste. The most widely selected option is the deep geological repository (DGR) concept, a mined repository with galleries located underground in geological layers into which packaged waste would be placed; the sites for such DGR have been selected in Finland, France and Sweden, and a site selection process is on-going in several other countries, such as in the United Kingdom, Germany and Switzerland.

As an alternative concept to the DGR, the deep borehole repository (DBR) concept, where waste packages are placed into single boreholes, relies on a similar safety strategy: confining and isolating the waste from the biosphere and surface natural phenomena in order to respectively rely on the geological environment to ensure long term passive safety and reduce the risk of human intrusion. The concept of DBR was first considered in the 1950s, but was rejected until the 2000s as it was far beyond existing drilling capabilities among others, given the constraints for HLW and SF management.

New technical developments in the drilling field relaunched the interest of a safe management of HLW and SF based on DBR concept in several countries. Therefore, the SITEX.Network association developed an overview of the existing studies that have been published on the DBR concept with information on the concept itself, on deployment strategies and methods, on issues associated with requirements related to waste packages and borehole equipment, hydro-geology, disposal operation, backfilling and sealing, and finally on safety analyses. The main aim is to provide bibliographical overview providing the state of knowledge about the DBR concept, the technical solutions for its implementation or major obstacles evidenced as a basis to identify safety issues important to deal with in a Safety Case. This could be considered to identify for the future R&D as well. This paper discusses also the controversial issue of DBR trying to provide information from different viewpoints, like the design options, R&D programs required, societal concerns and regulatory needs.
Calculating Global Dissipation of Internal Tides in Submarine Canyons
Authors: Nazarian Robert , Burns Christian , Legg Sonya , Buijsman Maarten , Arbic Brian
Published: March 2021

The breaking of tidally-generated internal gravity waves (hereafter internal tides) is a significant driver of ocean mixing, and observations and model simulations show that a non-negligible amount of this internal tide-driven mixing occurs in submarine canyons. While previous studies have used single observations of canyon mixing to estimate the global magnitude of internal tide-driven mixing within canyons, there is still significant uncertainty in these estimates.

To address this question, we have constructed an algorithm based on the modelled energy loss in idealized simulations (Nazarian & Legg 2017b) to calculate the magnitude of mixing in each submarine canyon and to determine the percentage of the global internal tide energy budget that is dissipated in canyons. The algorithm utilizes the Harris et al. 2014 analysis of the SRTM30_PLUS global bathymetry map to provide the geometrical properties of each canyon (i.e. height, length, width) and a high-resolution, tidally-forced HYCOM simulation to determine the internal tide field (sea surface height, angle of propagation, stratification, etc.). Preliminary calculations show that the canyon’s geometrical properties as well as local hydrographic properties have significant effects on the magnitude of mixing. Specifically, canyons that are tall relative to the depth of the water column and long relative to the incoming internal tide’s wavelength dissipate approximately 100% of the incoming wave’s energy. Consistent with previous studies, we find that regardless of bathymetry, submarine canyons can dissipate a significant fraction of the incident internal tide energy. Our estimate of the globally-integrated energy dissipation in canyons, taking into account geometric properties of each canyon, is two to three times larger than prior global estimates extrapolated from observations of individual canyons. Furthermore, our research highlights canyon hotspots of internal tide-driven mixing in the global ocean, for which observations do not presently exist. Taken together, these results raise larger questions about the location of internal tide dissipation and the inclusion of such dissipation in global ocean models.
Large-scale Arctic sea ice motion from Sentinel-1 and the RADARSAT Constellation Mission
Authors: Howell Stephen , Brady Mike , Komarov Alexander
Published: March 2021

As the Arctic’s sea ice extent continues to decline, remote sensing observations are becoming even more vital for the monitoring and understanding of this process.  Recently, the sea ice community has entered a new era of synthetic aperture radar (SAR) satellites operating at C-band with the launch of Sentinel-1A in 2014, Sentinel-1B in 2016 and the RADARSAT Constellation Mission (RCM) in 2019. These missions represent a collection of 5 spaceborne SAR sensors that together can routinely cover Arctic sea ice with a high spatial resolution (20-90 m) but also with a high temporal resolution (1-7 days) typically associated with passive microwave sensors. Here, we used ~28,000 SAR image pairs from Sentinel-1AB together with ~15,000 SAR images pairs from RCM to generate high spatiotemporal large-scale sea ice motion products across the pan-Arctic domain for 2020. The combined Sentinel-1AB and RCM sea ice motion product provides almost complete 7-day coverage over the entire pan-Arctic domain that also includes the pole-hole. Compared to the National Snow and Ice Data Center (NSIDC) Polar Pathfinder and Ocean and Sea Ice-Satellite Application Facility (OSI-SAF) sea ice motion products, ice speed was found to be faster with the Senintel-1AB and RCM product which is attributed to the higher spatial resolution of SAR imagery. More sea ice motion vectors were detected from the Sentinel-1AB and RCM product in during the summer months and within the narrow channels and inlets compared to the NSIDC Polar Pathfinder and OSI-SAF sea ice motion products. Overall, our results demonstrate that sea ice geophysical variables across the pan-Arctic domain can now be retrieved from multi-sensor SAR images at both high spatial and temporal resolution.
Feasibility of sedimentation strategies for the Mekong delta to counterbalance relative sea-level rise
Authors: Dunn Frances E. , Minderhoud Philip S. J.
Published: March 2021

As one of the largest deltas in the world, the Mekong delta is home to over 17 million people and supports internationally important agriculture. Recently deposited sediment compacts and causes subsidence in deltas, so they require regular sediment input to maintain elevation relative to sea level. These processes are complicated by human activities, which prevent sediment deposition indirectly through reducing fluvial sediment supply and directly through the construction of flood defence infrastructure on deltas, impeding floods which deliver sediment to the land. Additionally, anthropogenic activities increase the rate of subsidence through the extraction of groundwater and other land-use practices.

This research shows the potential for fluvial sediment delivery to compensate for sea-level rise and subsidence in the Mekong delta over the 21st century. We use detailed elevation data and subsidence scenarios in combination with regional sea-level rise and fluvial sediment flux projections to quantify the potential for maintaining elevation relative to sea level in the Mekong delta. We present four examples of localised sedimentation scenarios in specific areas, for which we quantified the potential effectiveness of fluvial sediment deposition for offsetting relative sea-level rise. The presented sediment-based adaptation strategies are complicated by existing land use, therefore a change in water and sediment management is required to effectively use natural resources and employ these adaptation methods. The presented approach could be an exemplar to assess sedimentation strategy feasibility in other delta systems worldwide that are under threat from sea-level rise.
Cenozoic magmatism in the Alps with special reference to the Ligurian knot
Authors: Berger Alfons
Published: March 2021

More than half a century of investigations on the chemical and isotopic compositions and on geochronological data of the Cenozoic magmatic rocks in the Alps and the transition to the Apennine will be summarized. The Alps itself are dominated by a calc-alkaline series between ~42 and 30 Ma, which we summarized as Periadriatic magmatism. This magmatism includes also eroded volcanic parts and several dykes in the Southern Alps and Tyrol. In addition, Sesia Zone magmatic rocks are characterized by ultrapotassic, shoshonitic and calc-alkaline rocks between 33 and 30 Ma. Two other magmatic provinces are located in between the Alps and the Apennine: (1) Veneto volcanic province (=VVP; nephelinites, basanites and alkali basalts between 52 and 30 Ma); (2) Mortara volcano (~28 Ma). Another group is the Esterél magmatic province, which is located in the Alps and their direct foreland, but are not related to Alpine geodynamics. These are basalts, andesites and dacites with mantle signature developed between 40 and 20 Ma. In the hanging plate of the early Apennine geometry, some minor volcanic activity is preserved in Sardinia. The major volume of Apennine magmatism itself (Elba etc.) is Late Miocene-Pleistocene in age and is related to roll back dynamics of the Apennine.

The Eocene/Oligocene Periadriatic magmatism of the Alps requires significant melt production in the crust combined with some ACF processes. This is possible by infiltration of fluids in the mantle wedge and the lower crust and a change of P-T conditions in the mantle. Their calc-alkaline character is related to Na-dominated input in the mantle and crust, which is commonly inferred to result from subduction of oceanic units. Ultrapotassic melts in the Sesia-unit most likely result from infiltration of K-dominated fluids, related to dehydration of continental material. The dynamics of Apennine and possible related forearc extension would allow an extensional related magmatism in the Esterél. This magmatism overlap in time with Alpine magmatism, and require a small-scale mantle dynamic due to the development of two slabs. In addition, the VVP and the Mortara volcano are located on the non deformed continental fragment of Adria between the Alps and Apennine. This area is characterized by overfilled basins and local magmatism inside the Adriatic continental plate.

The sometimes minor preserved volumes, but well constrain timing of magmatic rocks at the interaction between Alps and Apennine give insights in the lower crust/mantle dynamics at Oligocene/Early Miocene times. These interpretations may differ from models based on upper crustal tectonics, due to the decoupling between upper crust and lower crust/mantle.
A new spatio-temporal graph neural network method for the analysis of GNSS geodetic data
Authors: Kiani Shahvandi Mostafa , Soja Benedikt
Published: March 2021

Graph neural networks are a newly established category of machine learning algorithms dealing with relational data. They can be used for the analysis of both spatial and/or temporal data. They are capable of modeling how time series of nodes, which are located at different spatial positions, change by the exchange of information between nodes and their neighbors. As a result, time series can be predicted to future epochs.

GNSS networks consist of stations at different locations, each producing time series of geodetic parameters, such as changes in their positions. In order to successfully apply graph neural networks to predict time series from GNSS networks, the physical properties of GNSS time series should be taken into account. Thus, we suggest a new graph neural network algorithm that has both a physical and a mathematical basis. The physical part is based on the fundamental concept of information exchange between nodes and their neighbors. Here, the temporal correlation between the changes of time series of the nodes and their neighbors is considered, which is computed by geophysical loading and/or climatic data. The mathematical part comes from the time series prediction by mathematical models, after the removal of trends and periodic effects using the singular spectrum analysis algorithm. In addition, it plays a role in the computation of the impact of neighboring nodes, based on the spatial correlation computed according to the pair-wise node-neighbor distance. The final prediction is the simple weighted summation of the predicted values of the time series of the node and those of its neighbors, in which weights are the multiplication of the spatial and temporal correlations.

In order to show the efficiency of the proposed algorithm, we considered a global network of more than 18000 GNSS stations and defined the neighbors of each node as stations that are located within the range of 10 km. We performed several different analyses, including the comparison between different machine learning algorithms and statistical methods for the time series prediction part, the impact of the type of data used for the computation of temporal correlation (climatic and/or geophysical loading), and comparison with other state-of-the-art graph neural network algorithms. We demonstrate the superiority of our method to the current graph neural network algorithms when applied to time series of geodetic networks. In addition, we show that the best machine learning algorithm to use within our graph neural network architecture is the multilayer perceptron, which shows an average of 0.34 mm in prediction accuracy. Furthermore, we find that the statistical methods have lower accuracies than machine learning ones, as much as 44 percent.
The influence of global climate and local hydrological features over streamflow extremes.  Case of study in a tropical Andean basin
Authors: Avilés Alex , Contreras Juan , Mendoza Daniel , Pacheco Jheimy
Published: March 2021

Hydrological extremes such as floods and droughts are the most common and threatening natural disasters worldwide. Particularly, tropical Andean headwaters systems are prone to hazards due to their complex climate conditions. However, little is known about the underlying mechanisms triggering such extremes events. In this study, the Generalized Additive Models for Location, Scale and Shape (GAMLSS) were used for investigating the relations between the Annual- Peak-Flows (APF) and Annual-Low-Flows (ALF), respecting to climate and land use/land cover (LULC) changes. Thirty years of daily streamflow data-sets taken from two Andean catchments of southern Ecuador are used for the experimental research. Global climate indices (CI), describing the large-scale climate variability were used as hypothetical drivers explaining the extreme’s variations on streamflow measures. Additionally, the Antecedent-Cumulative-Precipitation (AP) and the Standardized-Precipitation-Index (SPI), and LULC percentages were also included as possible direct drivers – synthetizing local climate conditions and localized hydrological changes. The results indicate that AP and SPI clearly explain the extreme streamflow variability. Nonetheless, global variables play a significant role underneath the local climate. For instance, ENSO and CAR exert influence over the APF, while ENSO, TSA, PDO and AMO control ALF. Furthermore, it was found that LULC changes strongly influence both extremes; although this is particularly important for relative more disturbed catchments. These results provide valuable insights for future forecasting of floods and droughts based on precipitation and climate indices, and for the development of mitigation strategies for mountain catchments.
Soliton turbulence in weakly nonlinear and weakly dispersive media
Authors: Didenkulova Ekaterina
Published: March 2021

A short review on weakly nonlinear and weakly dispersive dynamics of soliton ensembles, the so-called soliton turbulence is given. Such processes take place in shallow water waves, internal waves in the atmosphere and the ocean, solid mechanics and astrophysical plasma; they are described by the integrable models of Korteweg – de Vries equation type (modified Korteweg – de Vries equation, Gardner equation). Here, soliton turbulence means an ensemble of solitons with random parameters. The property of solitons to interact elastically with each other gives rise to an obvious association with the gas of elastically colliding particles. Strictly speaking, soliton turbulence (soliton gas) is a deterministic dynamical system due to the integrability of equations describing the evolution of waves (solitons). However, due to the great complexity of its behavior (due to the large number of participating solitons and nonlinear nature of their interactions), the dynamics of the system can be considered random and, accordingly, may be investigated using methods typical for such problems.

Firstly, pair soliton collisions have been analyzed as an elementary act of the soliton turbulence for further understanding of their impact on multi-soliton dynamics. Different types of solitons have been considered: “thick” or “top-table” solitons, algebraic solitons, solitons of different polarities. From the point of view of the turbulence theory, the interactions of waves (particles) should be described by the statistical moments of the wave field. It was shown that the interaction of solitons of the same polarity leads to a decrease in the third and fourth moments characterizing the skewness and kurtosis. However, the interaction of solitons of different polarity leads to an increase in these moments of the soliton field. Then, the study of collision patterns of breathers (localized oscillating packets) with each other and with solitons has been carried out. The determination of conditions leading to an extreme scenario, as well as statistical properties, probability and features of large wave manifestation has been provided. As a result of numerical modeling of the multi-soliton field dynamics, the appearance of anomalously large waves in bipolar soliton fields has been demonstrated. Though most of the soliton collisions occur between the pairs of solitons, which may result in maximum two-fold wave amplification, multiple collisions also happen (they make about 10% of the total number of collisions). The long-term simulation of the soliton gas dynamics has shown a significant decrease in skewness and significant increase in kurtosis, confirming the fact of abnormally large wave (so-called “freak/rogue wave”) occurrence.

The reported study was funded by RFBR according to the research projects 19-35-60022 and 21-55-15008.
The effect of reed beds distributions on the Ecohydraulic dynamics of wetlands and lowlands: experimental analyses and simulations
Authors: Lama Giuseppe Francesco Cesare
Published: March 2021

The interplay between riparian vegetation and water flow in vegetated water bodies has a key role in the dynamic evolution of aquatic and terrestrial ecosystems in wetlands and lowlands. The present study analyzes the effects of the spatial distribution of reed (Phragmites australis (Cav.) Trin. ex Steud.) beds, an invasive riparian species extremely widespread in wetland and lowlands worldwide, on the main hydraulic and hydrodynamic properties of an abandoned vegetated reclamation channel located in Northern Tuscany, Italy. A field campaign was carried out to obtain Leaf Area Index (LAI) and Normalized Difference Vegetation Index (NDVI) of reed beds through both ground-based and Unmanned Aerial Vehicle (UAV) methodologies, and to correlate them to the channel’s flow dynamic and water quality main features. Then, Hydrodynamic simulations of the vegetated reclamation channel were performed and validated based on the experimental measurements of the hydraulic and vegetational parameters acquired in the field to build up a robust model to be employed also in future Ecohydraulic researches. The evidences of this study constitute useful insights in the quantitative analysis of the correlation between the spatial distribution of riparian vegetation stands in natural and manmade vegetated water bodies and their hydrodynamic and water quality main features.
Double-Nosed Low-Level Jets over Complex Terrain: Driving Mechanisms and Analytical Modeling
Authors: Brogno Luigi , Barbano Francesco , Leo Laura Sandra , Fernando Harindra Joseph , Di Sabatino Silvana
Published: March 2021

Low-level jets (LLJs) are a peculiar feature of the nocturnal Planetary Boundary Layer (PBL) and they have been extensively observed both in flat and complex terrain configurations. On the contrary, double-nosed LLJs have been rarely investigated. They essentially consist in the simultaneous occurrence of two noses (i.e. two wind-speed maxima) within the PBL vertical profile of wind speed, but their origin and mechanisms remain rather unclear.

Data collected in an open valley during the MATERHORN field experiment are used here first to demonstrate that double-nosed LLJs are frequently observed at the site during stable nocturnal conditions, and second to describe the mechanisms that drive their formation. Structural characteristics of these double-nosed LLJs are originally described using refined criteria proposed in the literature.

Two driving mechanisms for double-nosed LLJs are newly proposed in the current study. The first mechanism is wind-driven, in which the two noses are associated with different air masses flowing one on top of the other. The second mechanism is wave-driven, in which a flow perturbation generates an inertial-gravity wave. This wave vertically transports momentum causing the occurrence of a secondary nose, leading to the formation of a double-nosed LLJ. Careful examination of the temporal evolution of these events also revealed the short-lived and transitional nature of the secondary nose in both the mechanisms, as opposite to the primary nose whose evolution appeared instead driven by inertial oscillations. Application of two analytical inertial-oscillation models retrieved from the literature confirms this hypothesis. Indeed, both models satisfactorily reproduce the observed single-nosed LLJs but fail to capture the temporary formation of the secondary nose.
Diagnosing jet waveguidability in the presence of large-amplitude eddies
Authors: Wirth Volkmar , Polster Christopher
Published: March 2021

The waveguidability of an upper tropospheric zonal jet quantifies its propensity to duct Rossby waves in the zonal direction. This property has played a central role in previous attempts to explain large wave amplitudes and the subsequent occurrence of extreme weather. In these studies, waveguidability was diagnosed with the help of the refractive index using the zonal average of the observed flow as the relevant background state. Here, it is argued that this method is problematic both conceptually and mathematically.

The issue is investigated in the framework of the non-divergent barotropic model. This model allows the straightforward computation of an alternative "zonalized" background state, which is obtained through conservative symmetrisation of potential vorticity contours and which is argued to be superior to the zonal average. Using an idealized prototypical flow configuration with large-amplitude eddies, it is shown that the two different choices for the background state yield very different results; in particular, the zonal-mean background state diagnoses a zonal waveguide, while the zonalized background state does not. This result suggests that the existence of a waveguide in the zonal mean background state is a consequence of, rather than a precondition for large wave amplitudes, and it would mean that the direction of causality is opposite to the usual argument.

The analysis is applied to two heatwave episodes from summer 2003 and 2010, yielding essentially the same result. It is concluded that previous arguments about the role of waveguidability for extreme weather need to be carefully re-evaluated to prevent misinterpretation in the future.
Lithospheric deformation and mantle convection, a geological approach
Authors: Jolivet Laurent
Published: March 2021

Whether the deformation of continents is entirely caused by stresses transmitted from plate boundaries horizontally through the lithospheric stress-guide or also by viscous coupling with the asthenosphere flowing underneath, which was part of Arthur Holmes’ early vision,  is a long-standing question. An increasing amount of observations suggests an efficient coupling between mantle flow and crustal deformation far from plate boundaries, tipping the scale toward the second option. Modern seismic reflection profiles probing the entire crust down to the Moho show asymmetrical features implying simple shear at crustal scale in compressional (mountain belts) and extensional (rifts and passive margins) contexts. Comparison of crustal-scale strain field with seismic anisotropy in strongly extended regions shows homoaxiality of crustal and mantle deformation in continental rifts and back-arc regions. 2-D and 3-D numerical models show that the flow of mantle underneath these regions is faster than in the crust and drives crustal deformation. Beside seismic tomography that images ancient slabs preserved as velocity anomalies in the deep mantle but does not provide any information on the timing, the geological history of basins and orogens, although indirectly, is the only record of past mantle convection. Looking for evidence of coupling between the tectonic history of wide regions and mantle convection in parallel with numerical modelling can provide clues on how convection drives crustal deformation. The recent evolution of numerical modelling, with high-resolution 3-D experiments, can now match the first order of regional models based on geological observations, including the timing and the sequence of events, which are both crucial elements of geological models. This will allow testing complex conceptual models that have been discussed for long. In this lecture, I review different contexts where these questions are debated. Among these contexts complex in 3-D where the geological data set is abundant, the Mediterranean and the Middle East allow discussing the respective contributions of whole-mantle convection involving large plumes vs more local convection in the upper mantle due to slab dynamics in crustal deformation. Studying the dynamics of the India-Asia collision, and the respective roles of lithospheric-scale indentation on the one hand and asthenospheric flow due to slab retreat on the Pacific rim and to large-scale plumes, on the other hand, is also likely to bring interesting insights on how deformation propagates within continents at long distance from plate boundaries.
Heterogeneity in microclimate and soil parameters support diverse and unique vegetation on small natural features
Authors: Deák Balázs , Kovács Bence , Rádai Zoltán , Apostolova Iva , Kelemen András , Kiss Réka , Lukács Katalin , Palpurina Salza , Sopotlieva Desislava , Báthori Ferenc , Valkó Orsolya
Published: March 2021

Small natural features (SNFs) are small landmarks that differ in their abiotic characteristics from the surrounding landscape. SNFs, such as road verges, midfield islets, rocky outcrops and ancient burial mounds, provide safe havens for grassland specialist species in human-modified landscapes; therefore, their great ecological importance is in contrast to their small size. SNFs often have a high topographical heterogeneity and a related high variability in abiotic conditions; therefore, they provide a unique opportunity for establishing links between environmental heterogeneity (EH) and biodiversity. We investigated the EH components of topographically heterogeneous SNFs in a comprehensive framework, by linking environmental and biotic parameters. We studied ancient millennia-old burial mounds built by nomadic steppic tribes that are covered by semi-natural grasslands in the Pannonian (Hungary) and Continental (Bulgaria) biogeographical regions. We designated 16 study sites, each containing a few-metre-high mound with five microsites (top, north-, east-, south- and west-facing slopes) and a nearby plain grassland. At each microsite, we measured soil moisture, soil chemical properties, solar radiation and microclimate; and recorded the list and cover of vascular plants in a total of 480 plots. On the mounds, topographical heterogeneity was associated with sharp differences in microclimate and soil properties. Besides the contrast between mild north-facing and harsh south-facing slopes, east- and west-facing slopes also sustained unique microsites characterised by dynamic diurnal changes in air temperature and vapour pressure deficit. Various combinations of the EH components resulted in unique plant species compositions within the microsites, and supported the co-occurrence of species typical of contrasting habitat types, even within a couple of metres. By combining high-resolution measurements of abiotic factors with fine-scale vegetation sampling, our study provides evidence that widespread SNFs with complex topography harbour several grassland-specialist plant species and introduce a high level of EH to otherwise homogeneous plain landscapes, which cover one third of the global land area.
The HydroSocial Cycle approach to deepen on socio-ecological systems analysis and water management
Authors: Ricart Sandra , Castelletti Andrea
Published: March 2021

Balancing socio-ecological systems among competing water demands is a difficult and complex task. Traditional approaches based on limited, linear growth optimization strategies overseen by command/control have partially failed to account for the inherent unpredictability and irreducible uncertainty affecting most water systems due to climate change. Governments and managers are increasingly faced with understanding driving-factors of major change processes affecting multifunctional systems. In the last decades, the shift to address the integrated management of water resources from a technocratic ‘‘top-down’’ to a more integrated ‘‘bottom-up’’ and participatory approach was motivated by the awareness that water challenges require integrated solutions and a socially legitimate planning process. Assuming water flows as physical, social, political, and symbolic matters, it is necessary to entwining these domains in specific configurations, in which key stakeholders and decision-makers could directly interact through social-learning. The literature on integrated water resources management highlights two important factors to achieve this goal: to deepen stakeholders’ perception and to ensure their participation as a mechanism of co-production of knowledge. Stakeholder Analysis and Governance Modelling approaches are providing useful knowledge about how to integrate social-learning in water management, making the invisible, visible. The first one aims to identify and categorize stakeholders according to competing water demands, while the second one determines interactions, synergies, overlapping discourses, expectations, and influences between stakeholders, including power-relationships. The HydroSocial Cycle (HSC) analysis combines both approaches as a framework to reinforce integrated water management by focusing on stakeholder analysis and collaborative governance. This method considers that water and society are (re)making each other so the nature and competing objectives of stakeholders involved in complex water systems may affect its sustainability and management. Using data collected from a qualitative questionnaire and applying descriptive statistics and matrices, the HSC deepens on interests, expectations, and power-influence relationships between stakeholders by addressing six main issues affecting decision-making processes: relevance, representativeness, recognition, performance, knowledge, and collaboration. The aim of this contribution is to outline this method from both theory and practice perspective by highlighting the benefits of including social sciences approaches in transdisciplinary research collaborations when testing water management strategies affecting competing and dynamic water systems.
Evaluation of critical atmospheric patterns for the occurrence of forest fires in a climate change context in the northwest of Argentine Patagonia.
Authors: Dankiewicz Verónica , Rusticucci Matilde M. , Collazo Soledad M.
Published: March 2021

Forest fires are a global phenomenon and result from complex interactions between weather and climate conditions, ignition sources, and humans. Understanding these relationships will contribute to the development of management strategies for their mitigation and adaptation. In the context of climate change, fire hazard conditions are expected to increase in many regions of the world due to projected changes in climate, which include an increase in temperatures and the occurrence of more intense droughts. In Argentina, northwestern Patagonia is an area very sensitive to these changes because of its climate, vegetation, the urbanizations highly exposed to fires, and the proximity of two of the largest and oldest National Parks in the country. The main objective of this work is to analyze the possible influence of climate change on some atmospheric patterns related to fire danger in northwestern Argentine Patagonia. The data were obtained from two CMIP5 global climate models CSIRO-Mk3-6-0 and GFDL-ESM2G and the CMIP5 multimodel ensemble, in the historical experiment and two representative concentration pathways: RCP2.6 and RCP8.5. The data used in this study cover the region's fire season (FS), from September to April, and were divided into five periods of 20 years each, a historical period (1986-2005), which was compared with four future periods: near (2021-2040), medium (2041-2060), far (2061-2080) and very far (2081-2100). The statistical distribution of the monthly composite fields of the FS was studied for some of the main fire drivers: sea surface temperature in the region of the index EN3.4 (SST EN3.4), sea level pressure anomalies ​​(SLP), surface air temperature anomalies (TAS), the Antarctic Oscillation Index (AOI) and monthly accumulated precipitation (PR). In addition, the partial correlation coefficient was calculated to determine the independent contribution of each atmospheric variable to the Fire Weather Index (FWI), used as a proxy for the mean FS danger. As a result, we observed that SST EN3.4 is the only one that could indicate a reduction in fire danger in the future, although no variable presented a significant contribution to the FWI with respect to the others. In the RCP8.5 scenario, greater fire danger is projected by the TAS, the PR, the SLP, and relative by the AOI, while in the RCP2.6 scenario, only the TAS shows influence leading to an increase, which would be offset by the opposite influence of SST EN3.4 for the same periods in this scenario. In conclusion, in RCP8.5 it could be assumed that there is a trend towards an increase in fire danger given the influence in this sense of most of the variables analyzed, but not in RCP2.6 where there would be no significant changes.
Impact of spatial data uncertainty in global debris flow susceptibility analysis
Authors: Kurilla Laurie , Fubelli Giandomenico
Published: March 2021

There are many types and degrees of uncertainty associated with spatial data and processes. 

There are many factors and attributes associated with debris flow analyses which are prone to uncertainty.  For simplicity, in this presentation, only two attributes of debris flow events are investigated along with the impact of their uncertainty on the determination of environmental predisposing factors.    These two attributes, critical to debris flow susceptibility analyses, are landslide classification and event location.  The associated predisposing factors studied herein are lithology, soils, climate, ecophysiographic units, topography, hydrology, and tectonics.

In a landslide susceptibility analysis, landslide event location accuracy is paramount yet often inaccurately known.  Landslide inventories are often constructed based on mapping from aerial imagery, media reports, and field work by third party sources; and in a data-driven approach to debris flow susceptibility analysis the landslide type is important in modeling the relevant predisposing factors distinctive to each landslide type. 

In a study of global debris flow susceptibility an analysis of the impact between known location and a location accuracy offset, and landslide categorization uncertainty demonstrates the impact of uncertainty in defining the appropriate predisposing factors associated with debris flows.

This analysis is part of a larger debris flow global susceptibility determination which trains on known debris flow events and the predisposing factors associated with them to identify potential areas that may be susceptible to debris flows.  This study looks at the impact/differences that mis-categorization or location uncertainty have on the determination of predisposing factors, along with methods of conveying uncertainty information. 
How does a Homogeneous Nucleation Event respond to changes of Parameterizations of Water Activity and Saturation Vapor Pressure?
Authors: Baumgartner Manuel , Krämer Martina , Rolf Christian
Published: March 2021

Homogeneous nucleation of ice crystals via freezing of small supercooled solution particles represents a major pathway in the formation of cirrus clouds with high ice water content at low temperatures. A reasonable physical explanation of this type of freezing is provided by Koop's nucleation theory, relating the homogeneous nucleation rate to the water activity of the solution particles. While the homogeneous nucleation rate encodes the probability of freezing of solution particles, the water activity represents the ratio of water vapor saturation pressures over the solution to that over pure water in Koop's portrayal.

By using the ice microphysics model "CLaMS-Ice", we investigate the effect of various formulations of the water activity and the water vapor saturation pressure on the resulting cirrus clouds. Although CLaMS-Ice is a two-moment bulk model, it implements a comparatively detailed ice microphysics formulated by Spichtinger and Gierens. Such a microphysics scheme is suitable to be implemented in full three dimensional atmospheric models in contrast to even more detailed bin microphysics schemes.

We performed sensitivity simulations over a wide range of temperatures and vertical velocities by using two different direct parameterizations of water activity based on thermodynamic models in addition to the one used by Koop. Also, three different formulations of the water vapor saturation pressure are applied in the simulations. The results are evaluated regarding the predicted number of ice crystals and the ice onset humidities. In particular, one major finding is that the freezing thresholds are increased compared to Koop's freezing lines.
The effect of satellite rainfall uncertainty on landslide predictions
Authors: Zhao Binru , Chen Enze , Shen Qi
Published: March 2021

With the development of remote sensing technology, satellite rainfall products have become more and more credible. Although the potential of satellite rainfall products in landslide hazard assessments has been recognized, few studies evaluate the effect of satellite rainfall uncertainty on landslide predictions. This study attempts to explore the effect of satellite rainfall uncertainty on rainfall-triggered landslide predictions. We select the Emilia-Romagna region in northern Italy as the study area, and the NASA GPM-based IMERG data as the representative of satellite rainfall estimates. Satellite rainfall uncertainty is first characterized by generating rainfall ensembles for rainfall conditions responsible for landslides. The generated rainfall ensembles are then applied to the definition of rainfall thresholds using the bootstrap technique. The prediction performance of rainfall thresholds is finally evaluated through calculating the criteria of hit rate and false alarm rate. We anticipate that this study will encourage the research community to account for the satellite rainfall uncertainty when exploring the use of satellite rainfall in landslide hazard assessment.
Compound and cascading drought impacts do not happen by chance: a proposal to quantify their relationships
Authors: Madruga de Brito Mariana , Kuhlicke Christian
Published: March 2021

Rather than being isolated events, natural hazards often occur simultaneously or successively, resulting in compounding and cascading impacts. For instance, droughts and heatwaves often occur together (i.e. compound hazards) and trigger secondary hazards such as wildfires (i.e. cascading hazards). Furthermore, their impacts compound (i.e. compound impacts) and propagate through socio-economical systems (i.e. cascading impacts).

To move from cascading hazards towards cascading impacts, the use of qualitative tools such as narratives, storylines, and cognitive maps have emerged. Still, to predict how the impacts cascade across and within societies, quantitative methods are required.

Here, a new methodology for quantifying and visualizing drought compound and cascading impacts is presented using the case of the 2018/19 drought in Germany. The use of network inference and data mining tools is proposed to unravel patterns in an existing drought impact dataset (de Brito et al. 2020). Based on a co-occurrence analysis, the strength of compound impact patterns was quantified. Moreover, the most common cascading paths were identified through sequential pattern mining.

Results demonstrate that the occurrence of compound and cascading drought impacts follow a pattern and do not happen by chance.  Indeed, statistically significant co-occurrence associations outnumbered randomly distributed ones (91.1% versus 8.9%). This has important implications for impact mitigation, suggesting that the understanding of past patterns can help in the prediction of future consequences. Based on this information, efforts can be directed to reduce the initiation of impact interaction networks. Moreover, the visualizations used can support the communication regarding impacts interactions, facilitating a knowledge-driven response by those involved in drought risk management.

The tools used here can be applied to other hazards. The obtained results can serve help to develop complex models for understanding causalities between drought consequences. They can, for instance, support the development of system dynamics and agent-based models. Hence, instead of using qualitative perceptions, the causal equations would be data-driven. We expect that this work will encourage a more holistic approach to natural hazards impact research.

 

de Brito, M.M., Kuhlicke, C., Marx, A. (2020) Near-real-time drought impact assessment: A text mining approach on the 2018/19 drought in Germany. Environmental Research Letters. doi:10.1088/1748-9326/aba4ca