bluuebunny/crossref_metadata_2025 huggingface dataset:
Vulnerability and robustness of networked infrastructures: beyond typical graph-based measures
Authors: Ponti Andrea , Candelieri Antonio , Archetti Francesco
Published: March 2021

The issue of vulnerability and robustness in networked systems can be addressed by several methods. The most widely used are based on a set of centrality and connectivity measures from network theory which basically relate vulnerability to the loss of efficiency caused by the removal of some nodes and edges. Another related view is given by the analysis of the spectra of the adjacency and Laplacian matrices of the graph associated to the networked system.

The main contribution of this paper is the introduction of a new set of vulnerability metrics given by the distance between the probability distribution of node-node distances between the original network and that resulting from the removal of nodes/edges. Two such probabilistic measures have been analysed: Jensen-Shannon (JS) divergence and Wasserstein (WST) distance, aka the Earth-Mover distance: this name comes from its informal interpretation as the minimum energy cost of moving and transforming a pile of dirt in the shape of one probability distribution to the shape of the other distribution. The cost is quantified by the amount of dirt moved times the moving distance. The Wasserstein distance can be traced back to the works of Gaspard Monge in 1761 and Lev Kantorovich in 1942. Wasserstein distances are generally well defined and provide an interpretable distance metric between distributions. Computing Wasserstein distances requires in general the solution of a constrained linear optimization problem which is, when the support of the probability distributions is multidimensional, very large.

An advantage of the Wasserstein distance is that, under quite general conditions, it is a differentiable function of the parameters of the distributions which makes possible its use to assess the sensitivity of the network robustness to distributional perturbations. The computational results related to two real-life water distribution networks confirm that the value of the distances JS and WST is strongly related to the criticality of the removed edges. Both are more discriminating, at least for water distribution networks, than efficiency-based and spectral measures. A general methodological scheme has been developed connecting different modelling and computational elements, concepts and analysis tools, to create an analysis framework suitable for analysing robustness. This modelling and algorithmic framework can also support the analysis of other networked infrastructures among which power grids, gas distribution and transit networks.
Unsupervised Solar Wind Classification Using Wavelet Variational Autoencoders and Self-Organazing Maps
Authors: Amaya Jorge , Jamal Sara , Lapenta Giovanni
Published: March 2021

Last year we published an automatic method for the automatic classification of the solar wind [1]. We showed that data transformation and unsupervised clustering can be used to classify observations made by the ACE spacecraft. Two data transformation techniques were used: Kernel Principal Component Analysis (KPCA) and Auto-encoder Neural Networks. After data transformation three clustering techniques were tested: k-means, Bayesian Gaussian Mixtures (BGM), and Self-Organizing Maps (SOM). Although the results were very positive we ran into a few difficulties: a) the data from the ACE mission contains a very small population of observations originated at high latitude coronal holes, b) the measured features contain a high degree of intercorrelation, c) the data distribution is compact in the feature space, and d) the final algorithm produces a single categorical class for a single point in time.

In this work we present an improvement of the model that redresses some of the limitations above. We are still making use of the two main features of our previous work, i.e. the data transformation using auto-encoders and the unsupervised classification using SOM. But in the present work: a) we include the analysis of Ulysses data with observations of the solar wind originated at high latitudes; b) we perform a Factor Analysis to reduce the number of features used as inputs; c) we transform windows of time of the multi-variate time series (instead of instantaneous observations) into scalograms using wavelet transformations; d) we apply the variational version of the auto-encoder [2] to parametrize the scalograms; f) we finally use the SOM to automatically classify the windows of time in different categories.

This method can be adapted to the classification of observations from the Parker Solar Probe and Solar Orbiter missions.

The work presented in this abstract has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 754304 (DEEP-EST, www.deep-projects.eu), and from the European Union's Horizon 2020 research and innovation programme under grant agreement No 776262 (AIDA, www.aida-space.eu).

[1] Amaya, Jorge, Romain Dupuis, Maria Elena Innocenti, and Giovanni Lapenta. "Visualizing and Interpreting Unsupervised Solar Wind Classifications." arXiv preprint arXiv:2004.13430 (2020).

[2] Kingma, Diederik P., and Max Welling. "Auto-encoding variational bayes." arXiv preprint arXiv:1312.6114 (2013).
Social media, diversity and vulnerability: their role in a disaster
Authors: Nardini Olga , Bonati Sara , Morelli Stefano , Pazzi Veronica
Published: March 2021

Very few research studies have been dedicated to understanding the role of social media, diversity and vulnerability during a highly impacting event for a society. Social media are very important nowadays as a way to be in "connection to" and "link between" individuals. Thanks to technological support it is possible to create new virtual and real social relationships and networks and to be always up to date about what happen in the world. The role that virtual space plays "reducing distances", connecting people and places and facilitating the provision of support to people in need, has been receiving increasing interest in disaster studies in last years. In particular, connectivity has assumed an increasing role in relation to the diffusion of means to reach people and places in virtual mode. Furthermore, the use of social media as a means of providing information on disasters and risks could help to reduce exposure in disasters. However, several knowledge gaps are still opened, and in particular which are the potential repercussions of a high connected disaster management process on vulnerability? How can the weight of diversity change into the virtual space? The premise is that not everyone has the same possibility of accessing social media (e.g. to be informed, to know what is happening and to link with rescuers). The difficulty of accessing social media can make people invisible into the disaster management process with the risk that someone could be left behind. Thus, this presentation aims to discuss the challenges that derive from an increasing use of social platform in providing and receiving information during disasters. A second relevant point, that this presentation aims to discuss, is linked to the way citizens perceive communication platforms and how the flow of information significantly impacts on the interpretation and on the management of risk. Conclusions of this work suggest that communication should take into account the risk perception models by the public and therefore the peculiarities of each vulnerable group, to provide "targeted" communications in relation to the cultural context with the aim of reducing vulnerability growing up citizens’ awareness and knowledge. This presentation is the result of the work provided as part of the EU H2020 founded project LINKS (http://links-project.eu). 
Flood vulnerability assessment: A critical comparison between site derived, national and international depth-damage functions and their use in assessing flood risk in Malaysia
Authors: M. Rehan Balqis , Sayers Paul , M. Alayuddin A. Ulwan , M. Ghamrawi M. Fadhil , D. Miller James , A. Kabirzad Shabir , Kaelin Alexandra , C. Penning-Rowsell Edmund , H. Basri Bakti , A. Bell Victoria , Zulkafli Zed , J. Stewart Elizabeth
Published: March 2021

Damage functions are widely used to determine flood losses. National and international published damage functions are often used with little scrutiny or validation at local scales; a lack of understanding that unquestionably adds uncertainty to national flood risk assessment and investment planning. This paper examines the differences in aggregate flood damage estimates based on damage functions derived locally using local surveys and questionnaires, published national sector-based damage functions and land-use based damage functions published for Malaysia in the international literature. The paper is presented in two parts: firstly, the construction of a damage function from site-specific post-event flood surveys (covering a range of building types and flood hazard variables) and secondly, the comparison of these locally derived function with available national and international functions. A 0.05 km2 residential area located in Kuala Lumpur, Malaysia, which consists of sparsely located houses was selected for the study. It was used to drive the site-specific damage function and an associated estimate of flood damage for a range of observed and modelled flood events. The results show that at higher depths, the use of the site-specific function suggest an aggregate damage of approximately twice than an estimate based on national functions but much less (less than 100%) than would be estimated based on international published functions. The paper concludes that the international published damage functions should be used with care and condition using local (where possible) or national understanding of flood damages to avoid a significant over estimation of losses.
Statistical downscaling of wind speed time series data based on topographic variables
Authors: Hu Wenxuan , Scholz Yvonne , Yeligeti Madhura , von Bremen Lüder , Schroedter-Homscheidt Marion
Published: March 2021

Renewable energy sources such as wind energy play a crucial role in most climate change mitigation scenarios because of their ability to significantly reduce energy-related carbon emissions. In order to understand and design future energy systems, detailed modeling of renewable energy sources is important. In the light of making energy system modelling possible at all variability scales of local weather conditions, renewable energy source information with high resolution in both space and time are required.

Nowadays, renewable energy resources data that are widely used among the energy modeling community are reanalysis data such as ERA5, COSMO REA6, and MERRA2. Taking wind speed as an example, reanalysis data can provide long term spatially resolved wind information on any desired height in a physically consistent way. However, their spatial resolution is coarse. In order to obtain a fine spatial resolution data focusing on wind speed, this paper proposes a statistical downscaling method based on reanalysis data, observation data, and the local topography.

While most statistical wind downscaling studies have focused on obtaining site specific data or downscaling probability density functions, this paper focuses on downscaling one-year hourly wind speed time series for Europe to 0.00833 degree X 0.00833 degree (approximately 1km X 1km) resolution. It has been proven by various studies that the local topography influences wind speed. The topographic structure in this study is determined by two metrics: TPI, a topographic position index that compares the elevation of each cell to the mean elevation of the neighborhood areas and Sx, a slope-based, direction-dependent parameter that describes the topography in the upwind direction. The observation data used in this study are MeteoSwiss measurement values which provide the hourly wind speed time series at the station heights. For each weather station with observation data, biases described by the local terrain features are introduced to minimize the root mean square error (RMS) and Kolmogorov-Smirnov D (KSD) statistic between the corrected and the observed wind speed. These biases are then assigned to grid points with the same terrain types as the weather station, which enables downscaling of the wind speed for whole Europe.

The results show that this downscaling method can improve the RMS and KSD for both ERA5 and COSMO REA6, especially at mountain ridges, which indicates that it can not only decrease the bias, but also provide a better match to the observed wind speed distributions.
Energy estimation of resonant waves in channels with lateral cavities
Authors: Navas-Montilla Adrián , Juez Carmelo , Garijo Noelia
Published: March 2021

Macro-roughness elements, such as lateral cavities and embayments, are usually built in the banks of rivers for different purposes. They can be used to create harbors, or to promote morphological diversity that enhance habitat suitability in an attempt to restore the sediment cycle in channelized rivers. In presence of lateral cavities, shallow water flows may exhibit a rhythmic water surface oscillation, called seiche. The formation of the seiche is triggered by the partially bounded in-cavity water body which leads to the generation of a standing wave. Amplitude and periodicity of the seiche is jointly controlled by the dominant eigenmodes of the standing wave and by the turbulent shear layer structures created at the opening of the cavity. Seiches have been studied in the past decades putting the focus on their impact on river hydrodynamics and morphodynamics. However, the study of the seiches from an energy harvesting perspective is still unexplored. Seiche waves could represent a distributed hydropower source with a low environmental impact, being energy extraction possibly integrated with river restoration works. In this work, we use an in-house  numerical simulation model to reproduce the water surface oscillation in a channel with multiple lateral cavities and study their wave energy potential. The interaction of multiple cavities has an additional effect in the propagation and formation of multiple standing waves, ultimately leading to two-dimensional and multi-modal seiche waves. Therefore, a detailed analysis of the seiche amplitude and energy spatial distribution is presented.
Local example for the compensation of negative global environmental phenomena
Authors: Balázs Pál , Berki Imre , Horváth Adrienn
Published: March 2021

The main negative global phenomena are climate change, biodiversity loss and biological invasions. Attaining the 2050 climate neutrality target is of great importance in agriculture and forestry. Land use is a significant factor in carbon sequestration from the atmosphere (carbon sink) and can be employed to potentially store carbon for decades. Land use can also contribute to climate change adaptation against aridification, preserve biodiversity, and reduce CO2 and NOx emissions. In addition, growing global environmental problems impact the entire world, which compels society to live with changed circumstances. Nevertheless, negative processes do not affect all territories equally. Some areas are more vulnerable and sensitive to changes, while others are more flexible and demonstrate higher resilience against negative changes. Nature compensates negative global environmental phenomena and people can contribute to this process. This compensation is hard in semi-arid and arid regions of the world, however, in humid regions it needs less effort.

Őrség - one of the southwestern landscape of the Carpathian basin - is a typical example of a humid-mesic climate. Due to its unique ecological, economic, and social characteristics, Őrség shows higher resistance against global changes. The humid-mesic climate and the acid soil with low fertility promote the forest succession on abandoned arable lands and pastures. Due to the warming and the anthropogenic CO2 and NOx forest areas show accelerating growth. High forest coverage (62%), extensive land management, high humidity, high proportion of nature close areas, unique landscape structure, and soft tourism all manifest themselves in higher stability against negative changes. Under these specific site conditions, reviving capacity of forests is relatively high: uncultivated lands quickly become forests without human intervention. Therefore, the best line of action would be to support this natural afforestation process with tree species that are less climate-sensitive and more drought-tolerant. The increasing proportion of forests parallel with the decreasing proportion of uncultivated land reduces the possibility of the invasion of alien plant species. The afforestation process of rural areas is highly supported by the present Hungarian policy. 

Our research aims to enhance the observation that rural landscapes provide great examples for sustainability. These areas have not only remained viable, they also safeguard our future.
Future global crop production increases by adapting crop phenology to local climate change
Authors: Minoli Sara , Jägermeyr Jonas , Asseng Senthold , Müller Christoph
Published: March 2021

Broad evidence is pointing at possible adverse impacts of climate change on crop yields. Due to scarce information about farming management practices, most global-scale studies, however, do not consider adaptation strategies.

Here we integrate models of farmers' decision making with crop biophysical modeling at the global scale to investigate how accounting for adaptation of crop phenology affects projections of future crop productivity under climate change. Farmers in each simulation unit are assumed to adapt crop growing periods by continuously selecting sowing dates and cultivars that match climatic conditions best. We compare counterfactual management scenarios, assuming crop calendars and cultivars to be either the same as in the reference climate – as often assumed in previous climate impact assessments – or adapted to future climate.

Based on crop model simulations, we find that the implementation of adapted growing periods can substantially increase (+15%) total crop production in 2080-2099 (RCP6.0). In general, summer crops are responsive to both sowing and harvest date adjustments, which result in overall longer growing periods and improved yields, compared to production systems without adaptation of growing periods. Winter wheat presents challenges in adapting to a warming climate and requires region-specific adjustments to pre and post winter conditions. We present a systematic evaluation of how local and climate-scenario specific adaptation strategies can enhance global crop productivity on current cropland. Our findings highlight the importance of further research on the readiness of required crop varieties.
Dryland landscapes in Brazil: the relationship between soils and vegetation
Authors: Alves Grace
Published: March 2021

The Brazilian semiarid have a diversity of soils and parent material, and this influences its flora. We observed different landscapes, and we revised papers about the vegetation surveys and their relationship with the landscape elements and their evolution. Brazil's semiarid area is between average latitudes 2º and 17º South, and longitudes 35º and 46º West, on the same latitude position of Amazon Forest and Savanna biomes, and one of the few sub-equatorial dryland regions. The semiarid biome is named Caatinga and characterized by Seasonally Dry Forests and Woodlands (SDFW), one of Brazil's most degraded and least studied biomes. It was considered low in species diversity and endemism for a long time, mainly because of the semiarid climate and low research quantities. Recent studies indicated high biodiversity, surpassing the Amazon concerning the number of plant species per area. The landscape presents vast rocky pediments scattered with Proterozoic crystalline massifs and elevated sedimentary basins forming table-like plateaus. Caatinga shows an average annual rainfall of around 600mm/year; marked by seasonal irregularity, the dry season occurs between August and October, and the rainy season concentrates during the summer. Orography effects are significant, and in the higher areas such as Plateaus, the precipitation can exceed 1000mm/year, and the lack of rainfall is distributed among depressions. Dry conditions started in the Miocene when the SDTFW arrived at the Brazil northeastern by connecting with two large SDTFW of South America. The crystalline shield is the basement of the Sertaneja Depression and the Borborema Plateau, both own soils related to semiarid conditions like Luvisols, Planosols, Phaeozems, Vertisols, and shallow soils, besides Lixisols at the colluvium materials at the foot of the hills.  These soils are mainly above granites, gneisses, and schists exposed during the notching of the Sertaneja surface, with some elevated areas by most resistant rocks. These areas harbor the most typical SDTFW of the Caatinga with deciduous and spiny woodlands or small forests, in the high altitude also influenced the vegetation assembly. On the Sedimentary regions, distinct floristic communities show seasonal dynamics not controlled exclusively by the rainfall supply; at least 50% of them maintain their leaves throughout the year. Flora presents independent events of ecological speciation over the last 1,5 Ma. Predominant soils are Ferrasols and Arenosols; the latter, in some cases, may represent an advanced stage of the Ferrasol with high clay loss. These soils did not form under current climatic conditions as they demand more and regular precipitation. We noted the close relationship between parent materials, soils, and vegetation controlling the landscape characteristics and their time and space evolution.
Variations of the Indian Ocean Walker circulation since the Last Glacial Maximum revealed by reconstructed and simulated zonal wind intensity
Authors: Zhou Xinquan , Duchamp-Alphonse Stéphanie , Kageyama Masa , Bassinot Franck , Shi Xiaoxu , Beaufort Luc , Lohmann Gerrit
Published: March 2021

Today, precipitation and wind patterns over the equatorial Indian Ocean and surrounding lands are paced by monsoon and Walker circulations that are controlled by the seasonal land-sea temperature contrast and the inter-annual convection over the Indo-Pacific Warm Pool, respectively. The annual mean surface westerly winds are particularly tied to the Walker circulation, showing interannual variability coupled with the gradient of Sea Surface Temperature (SST) anomaly between the tropical western and southeastern Indian Ocean, namely, the Indian Ocean Dipole (IOD). While the Indian monsoon pattern has been widely studied in the past, few works deal with the evolution of Walker circulation despite its crucial impacts on modern and future tropical climate systems. Here, we reconstruct the long-term westerly (summer) and easterly (winter) wind dynamics of the equatorial Indian Ocean (10°S−10°N), since the Last Glacial Maximum (LGM) based on i) primary productivity (PP) records derived from coccolith analyses of sedimentary cores MD77-191 and BAR94-24, retrieved off the southern tip of India and off the northwestern tip of Sumatra, respectively and ii) the calculation of a sea surface temperature (SST) anomaly gradient off (south) western Sumatra based on published SST data. We compare these reconstructions with atmospheric circulation simulations obtained with the general coupled model AWI-ESM-1-1-LR (Alfred Wegener Institute Earth System Model).

Our results show that the Indian Ocean Walker circulation was weaker during the LGM and the early/middle Holocene than present. Model simulations suggest that this is due to anomalous easterlies over the eastern Indian Ocean. The LGM mean circulation state may have been comparable to the year 1997 with a positive IOD, when anomalously strong equatorial easterlies prevailed in winter. The early/mid Holocene mean circulation state may have been equivalent to the year 2006 with a positive IOD, when anomalously strong southeasterlies prevailed over Java-Sumatra in summer. The deglaciation can be seen as a transient period between these two positive IOD-like mean states.
Wave propagation simulation on a 3D model of the Ruhr district for locations of seismic monitoring.
Authors: Gonzalez de Lucio Gabriela de los Angeles , Finger Claudia , Saenger Erik
Published: March 2021

The Ruhr district meets the necessary elements to carry out geothermal projects due to its geothermal potential and demand, as it is a densely populated industrial area. Currently, there are projects for direct use, whereas projects for electricity generation are planned. The latter, due to greater depths, reservoir enhancement techniques are required in some cases. This may increase the associated seismic risk which should be elaborated in detail.

With available data, a three-dimensional geological and structural model was created. The shallower parts have been widely studied and documented by mining activity in the Ruhr region during the last century.  Below a depth of 1 km, data are scarce, and uncertainties increase. The full elastic wavefield emitted by a realistic seismic source has been simulated using a finite differences scheme and the derived geological model. The elastic properties were estimated with well data. The source has common characteristics of real seismic events in the area.

The wave propagation simulations let us analyze the seismic response with different sources and velocities models. Three cases are considered, two seismic events with distinct depths based on real events. The third case is based on the proposed location of a deep geothermal project.

Especially for the case with the deeper source, the areas with relatively high amplitudes of displacement correlated with structural features of the model. Applying the imaging condition of maximum energy density allows us to define zones with a potentially increased seismic risk that should be monitored more closely.
Multi-Sensor Retrieval Algorithm for Daytime Total Column Water Vapor from Passive Imagers
Authors: El Kassar Jan Riad , Carbajal Henken Cintia , Preusker Rene , Fischer Jürgen
Published: March 2021

A novel algorithm for total column water vapor (TCWV) retrieval, which uses a combination of satellite-based measurements in the near-infrared (NIR) and infrared (IR) spectrum, is presented. The algorithm is built with a modular approach so that it can be used for a wide array of passive sensors. It is based on a fast forward model for NIR and IR bands at the water vapor absorption peaks in use on current and future instruments. 

An Ocean Land & Colour Imager (OLCI) TCWV retrieval for land surfaces has been developed, building on earlier work done for MERIS and MODIS, including extensive validation exercises using well-established ground-based TCWV observations as reference. The retrieval is extended to a synergy with IR measurements at 11 and 12um from the Sea and Land Surface Temperature Radiometer (SLSTR), also onboard the Sentinel-3 satellites. This allows more accurate TCWV retrievals over dark water surfaces. 

Moreover, support is planned for the polar-orbiting meteorological satellite instruments such as METimage on Metop - Second Generation (Metop-SG) and geostationary instruments such as the Flexible Combined Imager (FCI) onboard Meteosat Third Generation (MTG). 

Application examples of the newly derived TCWV observations include studying the potential of assimilating OLCI’s high spatial resolution TCWV fields in Numerical Weather Prediction (NWP) as well as detection of convective initiation in TCWV fields before the onset of clouds and precipitation within the German project RealPEP.
Uncertainty Chains in the Geological and Geotechnical Barriers of a HAW-disposal site
Authors: Mintzlaff Volker , Stahlmann Joachim
Published: March 2021

When projecting and planning a final high-level radioactive waste disposal site various uncertainties need to be addressed. A geological model is an abstraction of one possibility to interpret the exposed outcrops, drilling results and geophysical data. In numerical modelling the geological model is further simplified due to computational limitations. The behaviour of rocks is modelled with more or less complex constitutive models which are based upon laboratory experiments. Complex constitutive models have a huge range of input parameters, which rarely can be obtained completely by these experiments. The samples, which will be used in the laboratory experiments, are, as the data of the geological model, always a selection of drilling cores. For example, in a mechanical laboratory, harder rocks will be overrepresented in comparison to softer parts of the core.

Since the mentioned uncertainties are not avoidable many authors suggest that an open communication of these uncertainties can support the confidence of the public in the work of the professionals and as well as the projected development of the final disposal site. This contribution will present an overview of these uncertainties in the geological and geotechnical barriers of an final disposal site to discuss the relevance of these.
Investigating the diurnal variability of nitrous oxide emissions from soils 
Authors: Wu Yuk Faat , McNamara Niall , Whitaker Jeanette , Toet Sylvia
Published: March 2021

Diurnal variations in soil nitrous oxide (N­2O) emissions have been documented for nearly four decades yet consensus on their significance is still lacking. Resolving this question is important as soil N2O emissions have some of the highest uncertainties in national greenhouse gas inventories. A major challenge for understanding diurnal variation is that conventional measurements rarely operate at temporal frequencies that can observe and report this phenomenon. Some higher frequency studies have observed daytime peaking of soil N­2O emissions and often ascribe it to the diurnal oscillation of soil temperature. However, night-time peaking and irregular diurnal N­2O patterns have also been reported in a number of studies.

To investigate the prevalence and characteristics of diurnal N­2O variability, we systematically reviewed published studies that measured N2O at high temporal frequencies (≥ 5 times/day). We identified 46 published studies covering cropland, grassland and forest soils; and extracted sub-daily N­2O flux data and other soil parameters, yielding 286 individual days of data. Diurnal variability of N­2O emissions were found in ~80% of the data, with ~60% peaking during the day and ~20% at night. Diurnal N­2O patterns were associated with non-diurnal factors including soil texture and land use but the relationship between soil temperature and N­2O flux was inconsistent, with strong positive correlations (R > 0.7) only found in one-third of the datasets.

This talk explores the implications of the review results on the time of sampling using conventional approaches (single time-point flux measurements), and the potential drivers of diurnal N­2O variations for future research. In addition, this talk will also introduce a novel automated measurement technique allowing flux measurements at high temporal resolutions and how its application could enable experimental investigations of potential drivers of diurnal N­2O variability.
Present-day vertical land movement in San Fernando (La Union) and Currimao (Ilocos Norte), northwest Luzon, Philippines
Authors: Flores Paul Caesar , Rediang Abegail , Pasaje Nikki Alen , Alfante Rey Mark , Bauzon Maria Divina Angela , Reyes Rosalie , Siringan Fernando , Amedo-Repollo Charina Lyn , Bringas Dennis , Blanco Ariel
Published: March 2021

The northwestern coast of Luzon Island is located within the forearc region of the Manila Trench where emergent coral reef platforms have been reported; and an uplift rate of 0.5 m/kyr has been estimated for the past 7,000 years in San Fernando and Currimao. This study examined the present-day vertical land movement (VLM) in both sites using tide gauge records and retracked Jason satellite altimeter missions. Both the tide gauge and satellite data were corrected for tides using the T_Tide algorithm and the difference between the tide gauge sea level (TGSL) and sea surface heights (SSH) from the satellite were calculated. The influence of VLM was inferred from the differences between the TGSL and SSH, then validated using available GNSS data.

 

Hourly TGSL for San Fernando is available from 2002 to 2018 with a completeness index (CI) of 37%. The satellite products used were the 20 Hz MLE4 and 1Hz ALES retracked Jason satellite series downloaded from AVISO+ and OpenADB, respectively. The MLE4 product indicates subsidence with a rate of 0.43 ± 0.10 mm/yr, while ALES indicates uplift at 1.93 ± 0.42 mm/yr. GNSS observations at the San Fernando TG benchmark (TGBM) from 2017 to 2019 shows subsidence at 0.74 ± 0.40 mm/yr, which agrees well with the VLM estimate from the difference between TGSL and MLE4 SSH.    

 

Currimao TG station has a CI of 90% from 2008 to 2016. Satellite products used were the 20 Hz MLE4 and 20 Hz ALES retracked Jason-2 downloaded from AVISO+, and both indicate uplift with a rate of 7.30 ± 0.17 and 6.24 ± 0.25 mm/yr, respectively. The present-day uplift agrees with the geological records, however, there are no GNSS data at the TGBM to validate the present-day vertical motion.

 

The differences between the present-day vertical motion of San Fernando and Currimao may indicate the influence of other fault systems associated with the Philippine Fault or segmentation of the forearc. Subsidence in San Fernando could imply stress accumulation in the area and the observed uplift in the geological records are cumulative co-seismic vertical displacements.  
Disentangling human-fire-climate linkages at mid-elevations in the Šumava Mountains of central Europe
Authors: Kraklow Vachel , Moravcová Alice , Kuneš Petr , Dreslerová Dagmar , Finsinger Walter , Diaconu Andrei-Cosmin , Nývlt Daniel , Kadlec Martin , Tinner Willy , Heurich Marco , Florescu Gabriela
Published: March 2021

To distinguish human-caused from naturally-caused fire regimes, palaeoecological records must demonstrate that observed changes in vegetation and fire are in response to changes in human activity rather than driven by natural climate-fire relationships. Here, we use a high-resolution multi-proxy approach (testate amoebae derived depth to water table (DWT), macro- and micro-charcoal, charcoal morphologies, pollen, non-pollen palynomorphs, plant macrofossils, and XRF) from Pékna, a mid-elevation peat bog situated near Lipno Reservoir - an area rich in human land use - to investigate human-driven vs. naturally-driven fire regimes in the Šumava Mountains. Our results span the entire Holocene and illustrate that humans have been consistently modifying the landscape since 5,500 cal yr BP. Specifically, during the mid-Holocene (7,000 – 4,000 cal yr BP) when water table was at its highest at Pékna, relatively frequent, low-severity fires occurred and was accompanied by the prolonged presence of coprophilous fungi, secondary human indicators and an opening of the forest, suggesting human activities. Human land use intensified ~1,500 cal yr BP as indicated by increases in primary human indicator species, an increase in early successional tree species (Pinus and Betula) indicating an opening of the forest canopy, and the development of regional mining is suggested by a marked increase in the concentration of lead (Pb). While water table depths decreased indicating drier conditions ~1,500 cal yr BP, local fires persisted, burning at low severities as indicated by the continued presence of charred herb macrofossils. The most intensive land use occurred in the last 500 years with the highest abundance of primary and secondary human indicator species, and coprophilious fungi. Locally, marked increases in the concentration of both redox-sensitive elements such as iron (Fe), calcium (Ca), sulphur (S), and chlorine (Cl), and detrital elements such as potassium (K), aluminum (Al) and Titanium (Ti) indicate major changes in the depositional environment over the last 500 years, possibly due to peat draining. However, this time period witnessed decreased biomass burning as a result of a more open landscape and less fuels to burn. These results contribute to a growing body of literature illustrating the importance of prehistoric impact in the mid-mountains of Central Europe.   
Atmospheric impacts of short-lived chlorinated species over the recent past: a chemistry-climate perspective
Authors: Bednarz Ewa , Hossaini Ryan , Abraham Luke , Braesicke Peter , Chipperfield Martyn
Published: March 2021

The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl3) and dichloromethane (CH2Cl2), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised. 

 

We address this issue using the UM-UKCA chemistry-climate model (CCM). While not only the first, to our knowledge, model study addressing this problem using a CCM, it is also the first such study employing a whole atmosphere model, thereby simulating the tropospheric Cl-VSLSs emissions and the resulting stratospheric impacts in a fully consistent manner. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs.

 

We examine the impacts of rising Cl-VSLSs emissions on atmospheric chlorine tracers and ozone, including their long-term trends. We pay particular attention to the role of ‘nudging’, as opposed to the free-running model set up, for the simulated Cl-VSLSs impacts, thereby demostrating the role of atmospheric dynamics in modulating the atmospheric responses to Cl-VSLSs. In addition, we employ novel estimates of Cl-VSLS emissions over the recent past and compare the results with the simulations that prescribe Cl-VSLSs using simple lower boundary conditions. This allows us to demonstrate the impact such choice has on the dominant location and seasonality of the Cl-VSLSs transport into the stratosphere.
Climatic variations during the Holocene inferred from radiocarbon and stable carbon isotopes in a high-alpine cave
Authors: Welte Caroline , Fohlmeister Jens , Wertnik Melina , Wacker Lukas , Hattendorf Bodo , Eglinton Tim , Spötl Christoph
Published: March 2021

Laser ablation coupled online to accelerator mass spectrometry [1] allows analyzing the radiocarbon (14C) concentration in carbonate samples in a fast and spatially resolved manner. This novel technique can provide 14C data at a spatial resolution comparable to that of stable carbon isotope measurements and, thus, can help to interpret δ13C signatures. In this work, we analyzed δ13C and 14C of a Holocene stalagmite from the high-alpine Spannagel Cave (Austria). Combined δ13C and 14C profiles allow identifying three growth periods : (i) the period > 8 ka BP exhibits relatively low δ13C values with small variability combined with a comparably high dead carbon fraction (dcf) of around 60%. This points towards C contributions of an old organic carbon reservoir in the karst potentially mobilized due to the warm climatic conditions of the early Holocene. (ii) Between 3.8 and 8 ka BP, a strong variability in δ13C with values from -8 to +1‰ and a generally lower dcf was observed. The δ13C variability was most likely caused by changes in gas exchange processes in the cave, which are induced by reduced drip rates as derived from lower stalagmite growth rates. Additionally, the lower dcf indicates that the OM reservoir contributed less to stalagmite growth in this period possibly as a result of reduced precipitation or because the OM reservoir became exhausted. (iii) In the youngest section between 2.4 and 3.8 ka BP, comparably stable and low δ13C values combined with an increasing dcf reaching up to 50% are again hinting towards a contribution of an aged organic carbon reservoir in the karst.

[1] C. Welte, et al., (2016). Anal. Chem., 88, 8570– 8576.
Hydrogeochemical and nitrate isotopic indicators of vulnerability in the Katari-Lago Menor basin-aquifer, Lake Titicaca-Bolivia
Authors: Flores Avilés Gabriela Patricia , Duwig Céline , Sacchi Elisa , Spadini Lorenzo , Savarino Joel , Ramos Ramos Oswaldo Eduardo
Published: March 2021

In the semi-arid Bolivian Altiplano, the Katari and Lago Menor Basin, ranging between 6000 and 3800 m a.s.l. in altitude, hosts a major aquifer in Quaternary sediments of fluvioglacial and paleolacustrine origin. This basin supports a population of over 1.2 million of inhabitants and the largest city in the Altiplano, El Alto, one of the Latin America’s fastest growing cities in the 1980s. This rapid urban growth was accompanied by minimal land planning, and lack of basic infrastructure and environmental policies. In addition, the region is greatly affected by climate change, causing the glaciers to shrink. A multi-tracer approach was used to understand the main hydrogeochemical processes taking place along the groundwater flow, and to evaluate the impact of anthropogenic activities on groundwater quality and nitrate concentrations. In the upper part of the aquifer (above 4000m), in the Piedmont subsystem, siliciclastic and evaporitic rocks host groundwater of high quality. Here, groundwater chemistry is dominated by silicate weathering leading to a Ca(Mg)-HCO3 facies, low nitrate concentrations (<3.2 mgL-1), and low mineralization. At lower altitude, the anthropogenic impact is revealed by the increase in NO3- concentrations, reaching up to 35.6 mg L-1.  Nitrate stable isotopes allowed discriminating three main nitrate contributions:  leaching from areas influenced by manure piles, use of synthetic N fertilizers, and leakage from sewage collection pipes. Natural attenuation of nitrate occurs when fresh groundwater mixes with brackish groundwater of evaporitic origin. On the other hand, in the lacustrine plain (~3860 to 3810 m a.s.l), the groundwater geochemistry is dominated by evaporite dissolution and calcite precipitation, while nitrate originates from nitrification of synthetic fertilizers. This first hydrogeochemical study of one of the major groundwater systems in the Northern Altiplano is an important step towards a better management of this crucial water resource for the sustainable development of this region.

Fundings :

The present study was undertaken with the financial support of the Plurinational State of Bolivia provided through the Program “100 Scholarships for Postgraduate Education within the Framework of Technological and Scientific Sovereignty”, Supreme Decree 2100 (1 September 2014), and partly funded by LABEX OSUG@2020, ANR grant no.ANR-10-LABX-56 (financed by the Future Investments programme launched by the French government and implemented by the ANR).
A data fusion strategy for reanalysis and climate model winds 
Authors: Davison Silvio , Barbariol Francesco , Benetazzo Alvise , Cavaleri Luigi , Mercogliano Paola
Published: March 2021

Over the past decade, model reanalysis data products have found widespread application in many areas of research and have often been used for the assessment of the past and present atmospheric climate. They produce reliable fields at high temporal resolution (1 hour), albeit generally at low-to-mid spatial resolution (0.25°-1.00°). On the other hand, climatological analyses, quite often down-scaled (up to few km) to represent conditions also in enclosed basins, lack the actual historical sequence of events and are often provided at poor temporal resolution (6 hours or daily).

In this context, we investigated the possibility of using climate model data to scale ERA5 reanalysis wind (25-km and 1-hour resolution data) to assess the Mediterranean Sea wind and wave climate. We propose a statistical strategy to fuse ERA5 wind speeds over the sea with the past and future wind speeds produced by the COSMO-CLM (8-km and daily-mean data) climatological model. In the method, the probability density function of the ERA5 wind speed at each grid point is adjusted to match that of COSMO-CLM using a histogram equalization strategy. In this way, past ERA5 data are corrected to account for the COSMO-CLM wind distribution, while ERA5 scaled wind sequence can be also projected in the future with COSMO-CLM scenarios. Comparison with past observations of wind and waves confirms the validity of the adopted method.

We have tested this strategy for the assessment of the changing wind and, after WAVEWATCH III model runs, also the wave climate in the northern Adriatic Sea, especially in front of Venice and the MOSE barriers. In general, this data fusion strategy may be applied to produce a scaled wind dataset in enclosed basins and improve past and scenario wave modeling applications based on any reanalysis wind data.
Analysis of the hydrological and tectonic deformation in the eastern part of the Tibetan plateau, from FLATSIM automated time series analysis of Sentinel-1 InSAR
Authors: Lemrabet Laëtitia , Doin Marie-Pierre , Lasserre Cécile , Replumaz Anne , Métois Marianne , Leloup Philippe-Hervé , Chevalier Marie-Luce , Sun Jianbao
Published: March 2021

The global and systematic coverage of Sentinel-1 radar images allows characterizing, by radar interferometry (InSAR), surface deformation on a continental scale.

Our study focuses on the eastern part of the Tibetan plateau, where a combination of major strike-slip and thrust fault systems accommodates part of the deformation related to the collision between the Indian and Eurasian plates.

We use an automated Sentinel-1 InSAR processing chain based on the NSBAS approach (Doin et al., 2011, Grandin, 2015) to measure the interseismic deformation across these fault systems. Processing is made on the CNES high-performance computer center in Toulouse in the FLATSIM project framework (ForM@Ter LArge-scale multi-Temporal Sentinel-1 Interferometric Measurement, Durand et al., 2019). We perform a time series analysis of the 2014-2020 Sentinel-1 InSAR data set, for 1200 km-long tracks (acquired along 7 ascending and 7 descending orbits), covering a 1 700 000 km2 area, with a 160 m spatial resolution. From about 130 acquisitions per track, we perform about 600 interferograms, with short, three months, and one-year temporal baselines. After inversion, we obtain time series of line-of-sight (LOS) delay maps, including residual atmospheric delay and network misclosure measurements. The time series are fitted by a seasonal signal plus a velocity trend. The velocity field on overlap areas agrees within less than 1~mm/yr.

Finally, we decompose the LOS velocity maps into a vertical and a horizontal contribution.

InSAR velocity maps highlight surface deformation patterns mostly localized on known major faults, short-wavelength patterns attributed to slope instabilities phenomena, and hydrological signals.

The seasonal signal combines residual atmospheric phase delays and widespread hydrological phenomena in sedimentary basins, which we interpret in parallel with the regional geological map.  Masking areas affected by dominant gravitational slope or hydrological deformation allows to better focus on tectonic deformation.

We finally discuss slip partitioning on the various fault systems from the velocity maps and 2D profiles’ analysis.