bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the accuracy of time-domain surface-wave measurements: evaluation and correction of the finite-frequency phase shift
Authors: Xu Yihe , Lebedev Sergei , Meier Thomas
Published: March 2022

Surface waves propagating from earthquakes, active sources or within the ambient noise wavefield are widely used to image Earth structure at various scales, from centimetres to hundreds of kilometres. The accuracy of surface-wave, phase-velocity measurements is essential for the accuracy of the Earth models they constrain. Here, we identify a finite-frequency phase shift in the phase travel time that causes systematic errors in time-domain, phase-velocity measurements. The phase shift arises from the approximation of monochromatic surface waves with narrow-band filtered surface waves. We derive an explicit formula of the finite-frequency phase shift and present a numerical method for its evaluation and for the correction of the measurements. Applications to high-frequency and long-period examples show that the phase shift is typically around π/60-π/16 for the common settings of ambient-noise imaging studies, which translates to 0.2-0.8% phase-velocity measurement errors. The finite-frequency phase shift depends on the (1) second derivative of the wavenumber with respect to frequency; (2) width of the narrow-band filter; (3) epicentral or interstation distance; (4) centre frequency of the filter. In conversion to phase velocity, the last two factors cancel out. Frequency-domain methods for phase-velocity measurements have the advantage of not producing the finite-frequency phase shift. Both time- and frequency-domain measurements, however, can be impacted by a break-down of the far-field approximation (near-field phase shift), which our calculations also show. Our method offers an effective means of improving the accuracy of the widely used time-domain, phase-velocity measurements via the evaluation of and corrections for the finite-frequency phase shift.
How Realistic are Tropical Cyclones in the ERA5 Reanalysis?
Authors: Dulac William , Cattiaux Julien , Chauvin Fabrice , Bourdin Stella , Fromang Sébastien
Published: March 2022

The ERA5 dataset from the ECMWF is the first global reanalysis product to reach a horizontal resolution of 0.28125° (31km), a resolution that is thought to allow for a realistic representation of small-scale atmospheric features such as tropical cyclones.
Using the CNRM Tropical Cyclone Tracking Scheme carefully calibrated for ERA5 and a track pairing algorithm that uses the International Best Track dataset (IBTrACS) as reference, we investigate how well tropical cyclones (TC) are represented in ERA5.

First we show that the majority of IBTrACS systems are found by the ERA5 tracking, but that performances in terms of probability of detection and false alarm rate varies from one geographical basin to the other. Moreover, by comparing the intensities between tracked TCs from ERA5 and their observational counterparts, we show that TCs in the reanalysis are rather weak considering the spatial resolution – both in terms of maximum wind speed and pressure minimum. By looking at mean wind speed life cycles in several geographic basins we also show that TCs de-escalate too quickly after reaching their peak intensity. Finally, using a compositing technique we look at the internal structure of TCs and and that despite the weak intensity, they present expected features regarding radial and tangential wind speed and upper-core temperature anomaly when sorted by Saffir-Simpson categories.
Tectonic activity at Mangatolu Triple Junction and the Fonualei Rift and Spreading Center: breaking apart the intra-oceanic Niuafo’ou-Tonga microplate, Lau Basin, South West Pacific Ocean
Authors: Beniest Anouk , Schnabel Michael , Barckhausen Udo , Dannowski Anke , Schmid Florian , Riedel Michael , Jegen Anna , Kopp Heidrun
Published: March 2022

 The Mangatolu Triple Junction (MTJ) and the Fonualei Rift and Spreading Center (FRSC) are two prominent bathymetric features in the northern Lau Basin in the southwest Pacific Ocean. We present the results of six W-E running Multi-Channel Seismic (MCS), magnetic and sediment echo sounding profiles acquired during the ARCHIMEDES-I expedition. These profiles cover the MTJ, the FRSC and the region just south of the FRSC to investigate the tectonic history and current tectonic activity of the Lau Basin. 

On all MCS profiles, we observe a heavily faulted basement on both sides of the MTJ and FRSC with faults that are covered with sediments, confirmed by the sediment echo sounding data. We consider these buried faults inactive today. We also observe faults that reach the seafloor. These faults are generally located closer to the MTJ and the FRSC and they correlate well with seismic activity recorded in the region. We thus consider these faults currently active. Seismically transparent bodies are observed on most profiles as well. We have interpreted those as volcanic intrusions, i.e. sills, or as volcanoes that pierce through the stratigraphy, especially closer to the volcanic arc. 

The two sets of faults, the notion that extension rates are higher at the MTJ (32 mm/yr) than at the southern tip of the FRSC (8 mm/yr) and the results from our newly acquired and interpreted magnetic data, have led to the interpretation that an earlier rift phase accommodated extension in a wide rift tectonic setting between 2.15 Ma and 0.85 Ma at the MTJ and 2.15 and 1.61 Ma at the FRSC. Today, the extension is accommodated in a narrow rift tectonic setting close to the MTJ and FRSC with a higher extension rate at the MTJ than at the southern tip of the FRSC. These findings suggest that the MTJ and FRSC are one, single intra-plate extension zone that is in the process of breaking apart the overriding Niuafo’ou-Tonga microplate along the MTJ and FRSC.
Ice microphysics of low-level ice clouds in the Arctic: Satellite analysis
Authors: Papakonstantinou Presvelou Iris , Sourdeval Odran , Quaas Johannes
Published: March 2022

Climate in the Arctic changes at a faster rate than in the rest of the globe, a phenomenon called “Arctic Amplification” that requires improved scientific  understanding. Boundary-layer clouds may play an important role. At temperatures below 0oC, mixed-phase clouds exist and their phase and longevity is influenced by the abundance of ice crystals, which in turn is a function of aerosols serving as ice nucleating particles (INPs). Previous studies from in situ observations suggested a local source of INPs due to biological activity over open ocean. Here we investigate the ice crystal concentrations at a large scale by exploiting a newly-developed dataset retrieved from active radar/lidar satellite remote sensing. The data allow to study pure ice clouds in the boundary layer. Clouds are distinguished i) by latitude bands, ii) according to the underlying surface type (sea ice or ocean) and iii) as coupled/decoupled from the surface. Contrary to previous expectation, we find that at a given latitude and temperature, there are more ice crystals over sea ice than over open ocean. This enhancement is particularly found for coupled clouds south of 70oN, but also for decoupled clouds.
Methodology for analyzing the risk of disruption of overhead power lines in Portugal
Authors: Gonçalves Ana , Loureiro Sílvia , Correia Marques Margarida , Nieto Raquel , Lopes Rodrigues Liberato Margarida
Published: March 2022

Power systems, such as power transmission infrastructure - overhead lines, and consumers have been heavily affected by extreme weather events, which are becoming more intense and more frequent. An efficient and effective way to respond to the adverse consequences of EWEs is the risk analysis and the consequent risk management, which play a decisive role in adapting to climate change. The main objective of this work is to present the methodology of the risk analysis of the EWEs on overhead powerlines in Portugal. In this way, the level of risk associated with each of the identified events was classified according to their probability of occurrence and respective consequence (in a risk matrix), and through the cause-and-effect analysis (a diagram) for better understanding. Thus, it is concluded that the wind is the main factor that provoked the disruption of the overhead power lines, between 28% to 40% of analyzed events associated with windstorms. The probability of damage to overhead power lines for the occurrence of compound events (wind and rain) is 21% to 30%, and this fact was verified when it was considered the events of the three or four last extended winters, respectively, for both cases. Therefore, these events represent a critical risk for electrical systems, and it is necessary to continue to develop effective solutions to minimize the associated impacts. Measures and solutions that go through the management of vegetation, the revitalization, the updating, and replacement of the line, the network monitoring, and the preparation of repair teams, among several others.

Keywords: Extreme weather events; Risk assessment; Energy systems; Disruption; Powerlines; Portugal.

Acknowledgments: This work is supported by the Portuguese Science and Technology Foundation (Fundação para a Ciência e a Tecnologia — FCT) through the projects UID/GEO/50019/2019, PTDC/CTAMET/29233/2017 (WEx-Atlantic) and UIDB/04033/2020 (CITAB). FCT is providing for Ana Gonçalves doctoral grant (2021.04927.BD). The EPhysLab group was also funded by Xunta de Galicia, Consellería de Cultura, Educación e Universidade, under project ED431C 2021/44 “Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas.
SciQLop: an open source project for in situ data analysis
Authors: Jeandet Alexis , Aunai Nicolas , Génot Vincent , Schulz Alexandre , Renard Benjamin , Bayane Michotte de Welle , Nguyen Gautier
Published: March 2022

The SCIentific Qt application for Learning from Observations of Plasmas (SciQLop) project allows to easily discover, retrieve, plot and label in situ space physic measurements from remote servers such as Coordinated Data Analysis Web (CDAWeb) or Automated Multi-Dataset Analysis (AMDA).  Analyzing data from a single instrument on a given mission can rise some technical difficulties such as finding where to get them, how to get them and sometimes how to read them.  Thus building for example a machine-learning pipeline involving multiple instruments and even multiple spacecraft missions can be very challenging. Our goal here is to remove all these technical difficulties without sacrificing performances to allow scientist to focus on data analysis.
SciQLop development has started in 2015 as a C++ graphical application funded by the Paris-Saclay Center for Data Science (CDS) then by Paris-Saclay SPACEOBS and finally it joined the Plasma Physics Data Center (CDPP) in 2019. It has evolved from  a monolithic C++ graphical application to a collection of simple and reusable Python or C++ packages solving one problem at a time, increasing our chances to reach users and contributors.

The SciQLop project is composed of the following tools:

Speasy: An easy to use Python package to retrieve data from remote servers with multi-layer cache support.

Speasy_proxy: A self-hostable, chainable remote cache for Speasy written as a simple Python package.

Broni: A Python package which finds intersections between spacecraft trajectories and simple shapes or physical models such as magnetosheath.

Orbit-viewer: A Python graphical user interface (GUI) for Broni.

TSCat: A Python package used as backend for catalogs of events storage.

TSCat-GUI: A Python graphical user interface (GUI).

SciQLop-GUI: An extensible and efficient user interface to visualize and label time-series with an embedded IPYthon terminal.

While some components are production ready and already used for science, SciQLop is still in development and the landscape is moving quite fast.
In this presentation we will give an overview of SciQLop, demonstrate its benefits using some specific cases studies and finally discuss the planned features development.
The effect of seawater freshening on the marine carbonate system variability in the high Arctic fjords
Authors: Koziorowska-Makuch Katarzyna , Szymczycha Beata , Thomas Helmuth , Kuliński Karol
Published: March 2022

The spatial variability in hydrography (salinity and temperature) and carbonate chemistry (alkalinity - AT, total inorganic carbon concentration - CT, pH, CO2 partial pressure - pCO2, and the saturation state of aragonite - ΩAr) in high meltwater season (summer) was investigated in four Spitsbergen fjords - Krossfjorden, Kongsfjorden, Isfjorden, and Hornsund. It was found that the differences in hydrology entail spatial changes in the CO2 system structure. AT decline with decreasing salinity was evident, however, this relationship was highly heterogenous. Significant surface water AT variability (1889-2261 µmol kg-1) suggests multiple freshwater sources having different alkalinity end-member values and biological processes occurring in the water column. Most of the AT values were within the dilution lines of Ocean Water with freshwater having alkalinity from 0 to ~600 μmol kg-1. However, the distribution of AT against salinity suggests that locally the freshwater AT­ maybe even higher. The effect of AT fluxes from sediments on the bottom water was rather insignificant, despite high AT values (2288-2666 μmol kg-1) observed in the pore waters. Low pCO2 results in surface water (200-295 μatm) points to intensive biological production, which can strongly affect the CT values, however, is less important for shaping alkalinity. It has also been shown that the freshening of the surface water in the fjords reduces significantly ΩAr (an increase in freshwater fraction contribution by 1% causes a decrease in ΩAr by 0.022). Although during the polar day, due to low pCO2, ΩAr values are still rather far from 1 (they ranged from 1.4 to 2.5), during polar night, when pCO2 values are much higher, ΩAr may drop markedly.

This study highlights that the use of salinity to estimate the potential alkalinity can carry a high uncertainty, while good recognition of the surface water AT variability and its freshwater end-members is key to predict marine CO2 system changes along with the ongoing freshening of fjords waters due to climate warming.
Shift towards ecosystem water limitation exacerbates hot temperature extremes
Authors: Denissen Jasper , Teuling Adriaan J. , Balsamo Gianpaolo , Orth Rene
Published: March 2022

Hot temperature extremes have severe implications for human health, crop yields and tree mortality. Whereas they are mostly introduced by atmospheric circulation patterns, the intensity of hot temperature extremes is modulated by ecosystem functioning; when soil moisture is abundant, evaporation of water through transpiration and evaporation from surfaces is high, which causes relevant evaporative cooling. This cooling is greatly reduced under drought stress, because ecosystems adapt to water-limited conditions by saving water e.g. through stomatal regulation which leads to decreased terrestrial evaporation. This in turn leaves more energy to potentially exacerbate hot temperature extremes. 

While it has been shown that ecosystem water limitation is projected to increase in the future, the respective implications on hot temperature extremes are unclear. In this study, we capture the ecosystem's water limitation through the so-called Ecosystem Limitation Index (ELI, Denissen et al. 2020). To mitigate the confounding influence of changes in mean temperatures, which possibly originate from heat advection and circulation, we focus on the differences between mean and hot temperature extremes. Based on global climate projections from the sixth Coupled Model Intercomparison Project (CMIP6) from 1980 - 2100, we find regions with significant correlations between future evolution of temperature differences and ELI, with hot spots in North and South America. We furthermore test the role of the initial ELI for these correlations and find weak effects in Earth System Models included in the CMIP6 ensemble, but higher relevance in reanalysis data from the ECMWF Reanalysis 5th generation (ERA5) from 1980 - 2020, where the highest correlations are found in initially water-limited regions. These findings show that in large areas across the globe, temperature extremes increase much faster than mean temperatures alongside ecosystem drying. Therefore, considering ecosystem drying is relevant for assessing the intensity of projected temperature extremes and their corresponding impacts. This way, improving the representation of vegetation dynamics in state-of-the-art models is necessary to more accurately estimate evaporative cooling and consequently hot temperature extremes.

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Denissen, J. M., Teuling, A. J., Reichstein, M., & Orth, R. (2020). Critical soil moisture derived from satellite observations over Europe. Journal of Geophysical Research: Atmospheres, 125(6), e2019JD031672.
Scaling invariance behaviour of thermal fluxes from an extensive green roof 
Authors: Castellanos Diaz Leydy Alejandra , Versini Pierre-Antoine , Bonin Olivier , Tchiguirinskaia Ioulia
Published: March 2022

Green roofs are widely recognized as a Nature-Based Solution that regulates the air temperature within urban environments. Thanks to the shading effect and the evapotranspiration process (ET), the temperature decreases in the green roof surrounding area. Hence, the implementation of green roofs in urban environment for this purpose requires the quantification of ET-related processes at different scales. Nevertheless, because of complexity of the ET process, different methods of measurement have been used at different scales. However, no agreement about the way to assess ET rates over green roofs has been reached between the scientific community, as well as its behaviour at different urban scales is still unclear. Therefore, more investigations on ET measurements are required for better understand and analyse its spatial and temporal variability at different scales.

For this purpose, a Larger Aperture Scintillometer (LAS) MKI from Kipp&Zonen was installed over a wavy-green roof of 1 ha, the Blue Green Wave (BGW), located in the Ecole des Points ParisTech (France). The main objective of this set-up was to assess the refractive index-structure parameter (Cn2) fluctuations from which ET can be deduced by means of the Monin-Obukhov similarity theory and the surface energy balance. As LAS is mainly influenced by fluctuations of air temperature, a radiometer equipped with a temperature sensor was installed in addition over the BGW. Then, the scaling statistics of Cn2 and temperature were studied through their power spectral density and their structure function.

The results obtained from the power spectral density demonstrated the scaling invariance of Cn2 and temperature over certain ranges of scales. The spectral exponents are close to 5/3 for Cn2 and to 2 for the temperature. Regarding the scaling exponents of the structure functions, the multifractal feature of the structure parameter Cn2 and the temperature was confirmed. The scale-invariant properties of the empirical data were characterised using the Universal Multifractal framework.
A novel plant growth chamber for separate and continuous monitoring of above-ground and below-ground gas exchange
Authors: Osuebi-Iyke Emmanuella Onyinyechi , Schymanski Stanislaus , O'Nagy Oliver , Minette Frank
Published: March 2022

A large part of photosynthetically fixed carbon is translocated below-ground in order to construct and maintain the roots needed to supply the shoot with adequate water and nutrients. However, the amount of carbon translocated below-ground is not easily quantified, as an unknown part is lost as root respiration, which is not easily distinguished from microbial soil respiration.

Here we present a novel plant growth chamber enabling continuous and separate monitoring of above-ground and below-ground gas exchange. The above-ground compartment is separated from the soil compartment by an impermeable fat layer, and a custom-developed carbon-free soil substrate is used to eliminate CO2 release due to microbial decomposition of pre-existing soil carbon. Each compartment of the growth chamber is connected to an infrared gas analyzer, enabling simultaneous monitoring of above-ground and below-ground fluxes. A novel experimental approach using chemical agents was employed to test if CO2 uptake and release was adequately quantified in each compartment over several days.

In a pilot experiment performed to identify a suitable carbon-free soil, maize plants grown at a 20% volumetric water content, 1.3g/cm3 bulk density and a 14h/10h day/night regime showed a correlation between evapo-transpiration and root length but not with root biomass, suggesting that the cost/benefit ratio of root allocation may be more related to root respiration and mechanical energy expenditure than accumulated root biomass. In fact, our preliminary results suggest that cumulative root respiration over 2 weeks was of a similar order of magnitude as the carbon stored in the root system at the end of the experiment, and that root respiration rates were relatively similar to nocturnal shoot respiration rates. A detailed analysis is underway and will be presented during the conference.
Co-Evolution of Structure and Heterogeneity in Natural Permeable Media: The Emergence of Niche-Diversity and Functions During Weathering and Pedogenesis
Authors: Totsche Kai Uwe
Published: March 2022

Natural permeable media like soils, sediments, but also rocks, provide niches of different quality for the inhabitation by a diversity of organisms and communities. The locations for colonization are the microstructured, frequently hierarchic organized heterogeneous biogeochemical interfaces (BGI) that evolve during weathering and pedogenesis. These BGIs are built from a vast variety of organic and inorganic materials and organisms and become manifest as crusts or (micro)aggregates that frame the void network and connect to the liquid and gaseous phases. Microaggregates, operationally defined as composite, microporous, and themselves already heterogeneous composite structures smaller than <250µm, are supposed to be fundamental structural components, because of their stability, persistence, ubiquitous presence, and growing fraction during weathering and pedogenesis. Although research on structure development and fluid-solid interaction in permeable media is an important, exciting and competitive field of soil science, in particular the co-evolution of structure and function due to the interplay of the multitude of biochemical and biophysical processes in view of the properties, functions and resilience of soils has yet to be unravelled. By now, it is well accepted that such and endeavour requires integration of soil physical, chemical, and biological disciplines and demands the development and application of joint advanced characterization and probing techniques including molecular biology within a multi- and inter-disciplinary research approach. Within the framework of the research unit 2179 “Microaggregate development and turnover in soil” and its preceding priority research program 1315 “Biogeochemical Interfaces in Soil”, collaborative research has been put in action that aim at the systematic characterization and functional exploration of aggregates structures and the associated BGI. The presentation will give a compact introduction on the propositions, concepts, and challenges of this exciting research field that aims to contribute to a fundamental understanding of the basics of the co-evolution of architecture and function and the consequences for soil based ecosystem services, and resilience of soils.
Agricultural management affects active carbon and nitrogen mineralisation potential in soils
Authors: Spiegel Heide , Hendricks Sophia , Zechmeister-Boltenstern Sophie , Kandeler Ellen , Diaz-Pines Eugenio , Schnecker Jörg , Alber Oliver , Miloczki Julia , Sandén Taru
Published: March 2022

Soil organic matter (SOM) is important for soil fertility and climate change mitigation. Agricultural management - including soil amendments - can improve soil fertility and contribute to climate change mitigation by stabilising carbon in soils. This calls for cost-effective parameters to assess  the influence of management practices on SOM. The current study aimed at understanding how sensitive the parameters active/permanganate oxidisable carbon (AC) and nitrogen mineralisation potential (NMP) react to different agricultural management practices compared to total organic carbon (TOC) and total nitrogen (Nt). We aimed to gain a better understanding of SOM processes, mainly regarding depth distribution and seasonality of SOM dynamics using AC and NMP.

Data were obtained in five Austrian long-term field experiments (LTEs) testing four management practices: i) tillage, ii) compost application, iii) crop residue management, and iv) mineral fertilisation.

AC was specifically sensitive in detecting the effect of tillage treatment at different soil depths. NMP differentiated between all different tillage treatments in the top soil layer, it showed the temporal dynamics between the years in the compost LTE, and it was identified as an early detection property in the crop residue LTE. Both AC and NMP detected short-term fluctuations better than TOC and Nt over the course of two years in the crop residue LTE. Thus, we suggest that AC and NMP are two valuable soil biochemical parameters providing more detailed information on C and N dynamics regarding depth distribution and seasonal dynamics and react more sensitively to different agricultural management practices compared to TOC and Nt. They should be integrated in monitoring agricultural LTEs and in field analyses conducted by farmers. However, when evaluating results of long-term carbon storage, their sensitivity towards annual fluctuations should be taken into account.
The role of surface heat fluxes on development of warm seclusion favouring subtropical cyclone Raoni transition over the Southwestern Atlantic Ocean
Authors: Reboita Michelle , da Rocha Rosmeri , Crespo Natália , Gozzo Luiz , Custódio Maria , Lucyrio Vinicius , de Jesus Eduardo
Published: March 2022

In June 2021, an unusual cyclone developed near the boundary of Uruguay and southern Brazil. It initially had extratropical characteristics, later acquired features of a Shapiro-Keyser extratropical cyclone and then underwent a subtropical transition. When the subtropical system reached Brazilian water (1200 UTC 29 June 2021), the local Navy named the cyclone “Raoni”. The aim of this study is to describe the main drivers that made the cyclone develop features of a Shapiro-Keyser extratropical cyclone. Cyclogenesis was registered at 1800 UTC 26 June, forced by a trough at mid-upper levels that crossed the Andes and caused surface pressure deepening. Less than 24-hours later, the cyclone evolved following the Shapiro-Keyser development model, presenting a frontal T-bone pattern and warm seclusion. Sensitivity numerical experiments carried out with two regional models (Regional Climate Model - RegCM and Weather Research Forecasting Model - WRF) driven by ERA5 reanalysis indicate that the suppression of the surface sensible and latent heat fluxes produces a weaker extratropical cyclone without warm seclusion. Hence, surface heat fluxes seem to be the main driver to the warm seclusion development.
Increased flood hazards within the Himalayan Karnali River catchment predicted for an ensemble of CMIP-6 climate change scenarios
Authors: Pink Ivo , Reaney Sim , Bovolo Isabella , Hardy Richard
Published: March 2022

The Himalayas are of exceptional importance for the water resources in Asia and provide fresh water for more than 1.4 billion people. However, they are also the source of frequent floods with the highest death-per-event rates in the world. The floods are caused by intense monsoon precipitation, but snow melt and glacier melt contribute to the flood peaks. Both, extreme precipitation and melt contributions are predicted to be impacted by climate change but it remains unclear how these changes will alter the flood risk in the region.

This study investigates the impact of climate change on peak runoffs in the transboundary Karnali River Basin (KRB) in Nepal / China using both hydrological and statistical modelling. The fully-distributed cryospheric-hydrological model SPHY is applied for the period 2002-2015 and calibrated and validated using the GLUE framework. The Nash-Sutcliffe efficiency, PBIAS of peak flows and extended GLUE are used as performance indicators for the selection of behavioural parameter sets. The model is run with the selected parameter sets and the outputs of 13 downscaled and bias-corrected CMIP-6 models of three different scenarios (historical, ssp245, ssp585) to quantify the climate-change-induced changes in peak flows until the end of the century. Extreme Value Analysis is then applied to estimate the exceedance probability from the simulated annual maximum flows for the climate models, scenarios and hydrological parameter sets.

The results indicate an increase in flood hazard frequency and magnitude until the end of the century. The mean magnitude of an event with 2% annual exceedance probability (AEP) increases by 23% (±19%) in the period 2020 - 2059, and 42% (±19%) in the period 2060 - 2099 for ssp245, and 28% (±23%) in the period 2020 - 2059 and 82% (±41%) in the period 2060 - 2099 for ssp585 compared to the baseline period (1975 - 2014). Flows with a 50 year return period (2% AEP) during the baseline period (10,900 m3/s) are projected to occur every 9 years in the period 2020 - 2059 and 7 years in the period 2060 - 2099 for ssp245 scenario, and every 9 and 3 years for ssp585 scenario, respectively. Glacier and snowmelt contributions are projected to change in terms of seasonality and quantity but the increase of peak flows is mainly driven by the increase in extreme precipitation.
Chemical weathering linked to global warming during the PETM: Insights from the Spanish Pyrenees
Authors: Jaimes-Gutierrez Rocio , Adatte Thierry , Puceat Emmanuelle , Tremblin Maxime , Pellenard Pierre , Braun Jean , Castelltort Sebastien
Published: March 2022

We aim to determine the intensity of chemical weathering of detrital clays, as well as the lag time between the onset of the Paleocene-Eocene Thermal Maximum (PETM) and the chemical weathering response in a source-to-sink system. The PETM was a hyperthermal event characterized by an abrupt increase in global temperature (5–8 °C) over a short period (20 ka). A negative carbon isotope excursion marks the onset of the PETM, which reflects the fast injection of light carbon into the ocean-atmosphere system, triggering global climatic changes. Thus, physical and chemical erosion acted as feedback mechanisms to recover the global climate to pre-onset conditions. We focus on the continental section of the source-to-sink system, near the locality of Esplugafreda in the Southern Pyrenean foreland basin. We analyzed the evolution of the clay mineral assemblages in two clay-sized fractions (<0.5 µm and <2 µm), which can provide insights into the hydrolyzing conditions on the continents. We then measured oxygen and hydrogen stable isotopes as indicators of paleo-precipitation, temperature, and elevation of the catchment areas. The clay mineralogy results show an interplay of reworked clays during the extreme events, together with more hydrolyzing conditions marked by the production of authigenic clay during the onset and body of the PETM. The stable isotope geochemistry results point towards a climatically controlled response, where temperature fluctuations, as opposed to precipitation, played the main role in shaping the climatic regime. This is evidenced in a negative δ18O excursion at the onset and body of the PETM found in both size fractions. Further, we combine hafnium and neodymium isotope analyses of both clay fractions to track the silicate weathering intensity. This method will help us constrain the weathering regime and its response time relative to the onset and the body of the PETM. The results obtained in this project will serve to test numerical models of landscape evolution incorporating the chemical weathering response to climatic changes. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 860383.
Performance of regional climate models in simulating rainy seasons in West Africa
Authors: Weber Torsten , Ajayi Vincent O. , Gbode Imoleayo E. , Abel Daniel , Ziegler Katrin , Paeth Heiko , Traore Seydou B.
Published: March 2022

Agriculture in West Africa is highly dependent on rainfall during the rainy seasons. Therefore, modifications in rainy season characteristics due to recent and future climate change have a direct impact on crop yields and production in the region. Consequently, stakeholders and decision-makers need reliable regional climate change information on rainy seasons in order to develop appropriate adaptation measures.

Regional Climate Models (RCMs) can provide information on climate change at high temporal and spatial resolution through dynamic downscaling of climate projections generated by Earth System Models (ESMs). In order to assess the performance of RCMs in simulating rainy seasons and their characteristics such as onset and cessation, length and total sum of rainfall, a thorough evaluation of RCMs is required.

The current study evaluates the performance of three different RCMs (REMO2015, RegCM4-7 and CCLM5-0-15) in simulating rainy seasons in West Africa using gridded observational data sets. For the assessment, we will use the ERA-INTERIM driven simulations of the RCMs from the Coordinated Output for Regional Evaluations (CORE) embedded in the WCRP Coordinated Regional Climate Downscaling Experiment (CORDEX) for Africa with a spatial resolution of about 25 km.
Process and mechanisms on the occurrence of massive glacier-rock avalanches in the southeastern Tibetan Plateau under anthropogenic warming
Authors: Yang Wei , Zhao Chuanxi , Westoby Matthew , An Baosheng , Wu Guangjian , Wang Weicai , Wang Zhongyan , Wang Yongjie , Dunning Stuart
Published: March 2022

Catastrophic mass flows originating from the mountain cryosphere can cause widespread loss of life, destruction of property, and significant geomorphological reworking along flow paths. Based on in-situ field investigations, high-resolution satellite imagery, digital elevation models (DEMs), seismic records, and meteorological data, we present the process reconstruction, triggering mechanism, and downstream implications of a 50 Mm3 ice-rock avalanche and mass flow that originated from 6500 m asl of the Sedongpu basin in southeastern Tibet on 22 March 2021.The avalanche transformed into a highly mobile mass flow which temporarily blocked the Yarlung Tsangpo river. The avalanche flow lasted ~5 minutes and produced substantial geomorphological reworking. This event, and previous ones from the basin (a total of ~50 Mm3 on October 2017 and into 2018 occurring close to the 2021 ice-rock avalanche source region, and the detachment of the low-angle tongue of Sedongpu Glacier in two separate events with a total of ~130 Mm3 on 17/18 October and 29 October 2018), occurred concurrently with, or shortly after periods characterized by record positive air temperature anomalies, which may have contributed to instability of the mountain cryosphere. The occurrence of future large mass flows from the basin under anthropogenic warming cannot be ruled out, and their likelihood and impacts must be carefully considered given potential risks to life and implications for sustainable hydropower and associated socioeconomic development along the Brahmaputra.
Impact of the atmospheric circulation on the Arctic snow cover and ice thickness variability 
Authors: Athanase Marylou , Schwager Merle , Streffing Jan , Andrés-Martínez Miguel , Loza Svetlana , Goessling Helge
Published: March 2022

The Arctic sea ice cover and thickness have significantly declined since the 1970s, while exhibiting large interannual variability. Snow cover on sea ice, acting as an insulating barrier, was shown to be instrumental in driving the variability and trends in sea-ice thickness. Yet, the Arctic snow depth remains scarcely measured and overlooked in climate models, which translates to “very limited predictive skill” according to the IPCC (Special Report on the Ocean and Cryosphere in a Changing Climate). Moreover, sea-ice thickness initialization has been shown to be an important element for skilful sea-ice forecasts, and it appears plausible that the same holds for the snow layer on top.

Here, we investigate the role of atmospheric circulation anomalies in shaping the Arctic snow-cover and sea-ice thickness anomalies. In this preparatory work, spectral nudging of the large-scale atmospheric circulation towards ERA5 reanalysis data is applied to the fully coupled AWI Climate Model (AWI-CM-3). We examine the variability and trends of Arctic snowfall, snow depth, sea ice cover and thickness over a 42-year period (1979-2021), and in particular the reproduction of observed anomalies. Two nudging configurations are used, differing in strength by their relaxation timescale τ and spectral truncation wavenumber T (namely τ=24 h, T20 and τ=1 h, T159). We demonstrate the importance of atmospheric circulation anomalies in shaping variations of snow and ice thickness at sub-seasonal to interannual scales, and discuss the potential of spectral nudging as a tool to improve the initialization of sea ice forecasts.
A New Seismic Source Zone Model for Lesser Antilles Seismic Hazard Assessment 
Authors: Foix Oceane , Mazzotti Stephane , Jomard Herve
Published: March 2022

Seismic hazard levels used as reference for the French Lesser Antilles are derived from probabilistic seismic hazard assessment studies performed in 2002. However, our scientific knowledge has greatly increased over the past 20 years in this area. As part of a project linking the French Ministry of Ecological Transition and Solidarity, and the Seismicity Transverse Action of RéSiF (French seismological and geodetic network), we are developing a new seismotectonic model of the Lesser Antilles Subduction Zone (LASZ). The LASZ results from the subduction of the North and South American plates beneath the Caribbean plate since the Eocene. The boundary extends along 850 km in an ENE-WSW convergence direction at 18-20 mm/yr. Significant N-S variations in tectonic, seismic and volcanic activities raise questions on the undergoing geodynamic processes. Fractures and ridges entering into the subduction deform the trench, adding seismotectonic complexities. Several controversial hypothesis remain, such as the origins of the 1839 (Mw 7.5-8) and 1843 (Mw 8-8.5) earthquakes and the long term interseismic coupling, which is currently interpreted as being low. New seismic imageries and more complete seismic catalogs help to better constrain the slab and Moho shapes, as well as the hydrological behavior of the plate interface. In this study, we propose a compilation of existing data and hypothesis, completed by an analysis of focal mechanisms rupture types averaged on grid and strain tensor derived from GPS. For the first time, we add a particular attention in the role and influence of the mantle wedge seismicity, observed in only few subduction zones.
Study of the effects of low head Pumped Hydro Storage technology on coastal environment and fish passage
Authors: De Luca Antonio , Scanu Sergio , Peviani Maximo , Marcelli Marco , Miccoli Andrea
Published: March 2022

Low head Pumped Hydro Storage (PHS) has been considered an opportunity for energy storage since the rise of wind and solar energy development in Europe. The study of environmental aspects (siting, fish friendliness, and land use) therefore plays an important role in the ALPHEUS project (Augmenting Grid Stability Through Low Head Pumped Hydro Energy Utilization and Storage), which is a project funded by the European Union’s Horizon 2020 program. The principal aim of the project is to improve reversible pump/turbine (RPT) technology to make pumped hydro storage economically viable in coastal environments. Within the project, one of the objectives is to evaluate the impacts on the coastal marine environments of a low head pump hydro device at a preliminary level. The area designated for the implementation of the prototype test site is in the North Sea. The project will evaluate a variety of measures to either prevent fish from entering machinery or maximize the survival rate of fish passage.

This study is part of the ALPHEUS activities that investigate environmental aspects, and, focuses on the production of a protocol for PHS with the identification of the characteristic elements of each test site as part of the application of the MSFD (Marine Strategy Framework Directives) principles. It is, therefore, possible to evaluate in advance which environmental components are potentially affected by seawater PHS devices. The descriptors that are affected by PHS interactions are D1, D3, D6, D8, D11. D1 and D3 descriptors are focused on biodiversity and on commercial fish health, for this reason, an in-depth study of the effects on fish is required. Considering this, it is applied an innovative methodology for the assessment of potential impacts, injuries, and mortality rates on selected fish species. Fish friendlessness is estimated using software called Biological Performance Assessment (BioPA) that assimilates hydraulic field data, Computational Fluid Dynamics (CFD) results, and laboratory fish-injury studies. This tool gives the probabilities that fish will encounter hazardous conditions during passage through specific regions of the turbines and the impacts induced by hydrodynamic stressors.
Evidence and possible causes of velocity pulsing in a turbidity current in Lake Geneva
Authors: Thorez Stan , Blanckaert Koen , Lemmin Ulrich , Barry David Andrew
Published: March 2022

Negatively buoyant riverine inflows plunge when entering lakes or reservoirs and form gravity-driven currents near the bed. When a high sediment load causes the density excess, such currents are called turbidity currents. They can supply momentum, heat, oxygen, sediments, nutrients and contaminants to deep lake basins and are the main cause of reservoir storage capacity loss. Even with steady inflow, turbidity currents have been observed to exhibit regularly pulsing velocity patterns, which are likely to enhance mixing between the inflowing and the ambient waters. Previously, literature linked this pulsing to several mechanisms, including interfacial waves such as Kelvin-Helmholtz instabilities and Rayleigh-Taylor instabilities related to surface lobes along the plunge line. However, to our knowledge, field measurements of the latter have not been reported.

In the present study, field measurements of the plunging inflow of the negatively buoyant Rhône River into Lake Geneva (Switzerland/France) were carried out. Vessel-mounted ADCP measurements of the longitudinal flow field of the plunging flow and the subsequent turbidity current were combined with remote time-lapse imagery capturing related surface patterns.

The ADCP measurements confirm that the inflowing river water plunges and forms a turbidity current. At the turbidity current-ambient water interface, regularly spaced “bulges” in the velocity pattern suggest pulsing. Simultaneously taken remote time-lapse images show that at the surface, the inflowing sediment-rich water forms a distinct plume with a triangular shape leading away from the river mouth in the downstream direction towards a sharp tip. At the edge and in the immediate surroundings of this plume, a variety of intermittent lobes and vortical structures whose periodicity might be related to that of the velocity pulsing in the turbidity current, is observed.
Attribution of 2009 extreme rainfall & landslide event in Austria 
Authors: Mishra Aditya Narayan , Maraun Douglas , Truhetz Heimo , Knevels Raphael , Bevacqua Emanuele , Proske Herwig , Petschko Helene , Leopold Philip , Brenning Alexander
Published: March 2022

Between 22-26 June 2009, Austria witnessed a rampant rainfall spell that spread across populated areas of the country. High-intensity rainfall caused 3000+ landslides in southeast Styria, and property damages worth €10 Million in Styria itself. Elsewhere in Austria, flooding amounted to reparations worth €40 Million. Numerous synoptic-scale studies indicated the presence of a cut-off low over central Europe and excessive moisture convergence behind the extreme event. In a warmer climate change scenario, such an extreme precipitation event may manifest into a more intense event due to the higher water holding capacity of air with increased temperatures, but this reasoning may not be so straightforward considering the complex physics of precipitation, more so in a topographically heterogeneous region such as the GAR (Greater Alpine Region).

The flooding and landslides caused in the region raise an alarm and thus motivate this study whereby we investigate if the rainfall event did become stronger with time due to climate change compared to how it would have been in a counterfactual (climate change free) past. Here we have deployed the CCLM high-resolution regional model coupled with a statistical landslide model to simulate this event (rainfall and landslides) in a pseudo (surrogate) warming scenario. A marked decrease in rainfall intensity is observed in the simulations for 1° cooler climate (pre-industrial past) and the consequent landslide risk is reduced varying across GCMs that were used to derive the boundary conditions from.

We discuss the results from the lens of attribution perspective - how conditional attribution is much more useful compared to the conventional risk-based approach of attributing extreme events. The novelty of our approach lies in using a high-resolution convection-permitting regional model for a landslide attribution study.
Constraining the Interior Structure of Europa with Gravity Measurements
Authors: Petricca Flavio , Genova Antonio , Castillo-Rogez Julie , Mazarico Erwan
Published: March 2022

The NASA mission Europa Clipper is designed to conduct multi-disciplinary investigations of the interior, composition, and habitability of the Galilean moon Europa. The measurement of Europa’s gravity field, tides, orientation, and moment of inertia (MoI) will enable an accurate characterization of the moon’s interior by constraining internal structure models through the inversion of geophysical measurements. The refined knowledge of Europa’s interior will provide a better understanding of its thermal evolution and of the processes that formed and maintained the liquid water ocean underneath the moon’s outer icy shell. The accurate estimation of the tidal Love number k2 is expected to provide geodetic evidence of the existence of the ocean, and its combination with the Love number h2 will enable the estimation of the icy shell mean global thickness.

The determination of the MoI, obtained either through measurements of the degree-2 gravity field with the hydrostatic equilibrium assumption or by also measuring Europa’s orientation and obliquity, will provide information on the deep interior of the moon, possibly constraining the size and the composition of the solid interior. Numerical simulations are performed to assess the expected accuracy of the key geophysical quantities from the analysis of Europa Clipper radiometric data. These measurements are used in a Bayesian Inversion (e.g., Monte Carlo Markov chain) to explore the properties of Europa’s hydrosphere and deep interior.