bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrocarbon-bearing fluid migration produces brecciation at high pressure condition in subduction
Authors: Giuntoli Francesco , Vitale Brovarone Alberto , Menegon Luca
Published: March 2022

It has been recently proposed that high-pressure genesis of abiotic hydrocarbon can lead to strain localization in subducted carbonate rocks1. However, the mechanical effects of the migration of these hydrocarbon-bearing fluids on the infiltrated rocks still need to be constrained.

In this study, we investigate omphacitite (i.e. omphacite-rich rock) adjacent to an high-pressure methane source from the Western Italian Alps (Italy) using a multiscale and analytical approach including petrographic, microstructural, X-ray compositional mapping and electron backscatter diffraction analyses (EBSD). In the field, omphacitite bands are 1-5 metres thick and tens of metres long and are adjacent to carbonate rocks affected by high-pressure reduction and methane production.

Hand specimens and thin sections display a brecciated structure, with omphacitite fragments ranging in size from a few microns to several centimetres, surrounded by a matrix of jadeite, omphacite, grossular, titanite, and graphite. X-ray compositional maps and cathodoluminescence images highlight oscillatory zoning and skeletal (jackstraw) textures in jadeite, omphacite and garnet in the matrix, suggesting a fast matrix precipitation under plausible disequilibrium conditions. CH4 and H2 are found in fluid inclusions in the jadeite grains. This feature suggests a potential link between the genesis of CH4 in the adjacent carbonate rocks and the brecciation event.

EBSD analysis was performed on omphacitite clasts close to their borders, where omphacite grain size varies between a few microns and a maximum of 100 microns. Those omphacite grains display no crystallographic preferred orientation, abundant low angle boundaries and low (< 5°) internal lattice distortion. We interpret these textures as formed by pervasive and diffuse micro-fracturing related to the brecciation occurring at high pore fluid pressure, reaching sub-lithostatic values. This study suggests that at high-pressure conditions in subduction zones, the genesis and migration of hydrocarbon-bearing fluids can trigger fracturing in adjacent lithotypes.

1Giuntoli, F., Vitale Brovarone, A. & Menegon, L. Feedback between high-pressure genesis of abiotic methane and strain localization in subducted carbonate rocks. Sci. Rep. 10, 9848 (2020).

This work is part of project that has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 864045).

 
The Coniacian-Santonian Oceanic Anoxic Event OAE3 - global correlation of subevents
Authors: Wagreich Michael , Mansour Ahmed
Published: March 2022

The Coniacian-Santonian was a time of strong differentiation in marine sedimentation, characterized by organic carbon-rich black shales and dark carbonates interpreted as the last oceanic anoxic event, OAE3, versus organic carbon-poor white/reddish limestones, chalk and claystones known as Cretaceous Oceanic Red Beds (CORBs). Based on compiled geochemical and isotope proxy data, two high-resolution global carbon isotope curves for carbonate and organic matter were reconstructed based on statistical analysis. Three main levels of short amplitude (around 0.5‰) carbon isotope excursions were identified. These excursions, each some 0.4 to 0.7 Ma in duration, were characterized by regionally restricted benthic anoxia and sea-level highstands that controlled regional organic matter accumulation during the OAE3 subevents defined herein as OAE3a (late mid-Coniacian, ca. 86.9 Ma, Kingsdown Event), OAE3b (late mid-Santonian, ca. 85.0 Ma, Horseshoe Bay Event), and OAE3c (late Santonian to Santonian-Campanian Boundary Event, ca. 83.5 Ma). Based on a compilation oxygen isotope temperature data and reconstructed pCO2 trends, the Coniacian-Santonian was characterized by: 1) a steady state phase of warm greenhouse climate during the Coniacian, followed by (2) a hot greenhouse during the early Santonian that might be consistent with activation of the Central Kerguelen large igneous province, and (3) a longer-term cooling of the warm greenhouse climate from the mid-Santonian onwards. Organic matter-rich deposition is largely restricted to the low-latitude Atlantic and adjacent epeiric and shelf seas. Areas of enhanced oceanic circulation systems with a westwards directed Tethyan current and regional eddies of water mass flow had a negative feedback resulted in well-developed water column oxygen content within the Tethys.
Reactive oxygen species in soil: Abiotic mechanisms of biotic processes and consequences for organic matter and nutrient cycling
Authors: Kuzyakov Yakov , Yu Guang-Hui
Published: March 2022

Although most organic matter (OM) in soil is mineralized by microorganisms, the nonmicrobial processes, e.g., Fenton reactions and photo-degradation, strongly contribute to OM decomposition and CO2 emission and are the chemical background of many biotic transformations. Fenton oxidation is a catalytic reaction chain of hydrogen peroxide (H2O2) with ferrous iron (Fe(II)) and Fe (oxyhydr)oxides that generates highly reactive hydroxyl radicals (HO•) oxidizing OM to CO2. Reactive Fe (oxyhydr)oxides store at least one quarter (~600 Gt) of organic C in soil, which may be subjected to Fenton reactions in which nano-sized Fe (oxyhydr)oxides act as nanocatalysts. The Fenton mechanisms depend on the sources of reactive oxygen species (ROS): O2•−, H2O2 and HO•. Because microorganisms continuously produce ROS, biotic Fenton chemistry is ubiquitous in all soils, especially with strong UV radiation, fluctuating O2 concentrations and redox, microbial hotspots such as rhizosphere and detritusphere, and high contents of Fe (oxyhydr)oxides. Charcoal and biochar catalyze ROS formation in soil as an electron shuttle or by electron transfer from the valence to the conduction band under UV irradiation. Despite the extremely short lifetime (from nanoseconds to a few days), ROS are continuously produced and sustain the ubiquity of chelators and Fe(III) reduction. For the first time we calculated the fundamental Eh-pH diagrams for ROS species and showed their relevance for Fenton reactions under soil conditions. HO• as one of the most powerful oxidants (Eo = 2.8 V) provides the most energy release from Fenton reactions in soil. In some ecosystems (hot deserts; red soils in the tropics and wet subtropics) Fenton reactions contribute to OM oxidation to 30% and even exceed 50% of total CO2 emissions. Fenton reactions are omnipresent and play a dual role for soil C cycling: stimulate OM mineralization (including the most stable pools) and facilitate long-term C stabilization due to the increased recalcitrance of remaining OM and organo-mineral complex formation. Summarizing, Fenton reactions and their effects on OM decomposition and formation are an emerging research field that explains the chemical background of many oxidative enzymatic processes, may crucially change our views on C, energy and nutrient cycling in soils.
Deep Learning and Sentinel-2 data for artisanal mine detection in a semi-desert area
Authors: Cuevas-González María , Nava Lorenzo , Monserrat Oriol , Catani Filippo , Meena Sansar Raj
Published: March 2022

In sub-Saharan Africa, artisanal and small-scale mining (ASM) represents a source of subsistence for a significant number of individuals. While 40 million people officially work in ASM across 80 countries, more than 150 million rely indirectly upon ASM. However, because ASM is often illegal, and uncontrolled, the materials employed in the excavation process are highly dangerous for the environment, as well as for the people involved in the mining activities. One of the most important aspects regarding ASM is their localization, which currently is missing in most of the African regions. ASM inventories are crucial for the planning of safety and environmental remediation interventions. Furthermore, the past location of ASM could be used to predict the spatial probability of the creation of newborn mines. To this end, we propose a Deep Learning (DL) based approach able to exploit Sentinel-2 open-source data and a non-complete small-size mine inventory to accomplish this task. The area chosen for this study lies in northern Burkina Faso, Africa. The area is chosen for its peculiar semi-desert environment which, in addition to being a per se challenging mapping environment, presents a wide spatial variability. Moreover, given the high level of danger involved in field mapping, it is fundamental to develop reliable remote sensing-based methods able to detect ASM. Performance comparison of two convolutional neural networks (CNNs) architectures is provided, along with an in-depth analysis of the predictions when dealing both with dry and rainy seasons. Models’ predictions are compared against an inventory obtained by manual mapping of Sentinel-2 tiles, with the help of multitemporal interpretation of Google Earth imagery. The findings show that this approach can detect ASM in semi-desertic areas starting with a few samples at a low cost in terms of both human and financial resources.
The impact of laterally varying scattering properties on subsurface monitoring using coda wave sensitivity kernels: Application to fault zone and volcanic areas
Authors: van Dinther Chantal , Wang Qingyu , Margerin Ludovic , Campillo Michel
Published: March 2022

Coda wave interferometry is an important tool to gain insights into the dynamic evolution of the Earth. A limitation of the majority of current studies employing this technique, is the neglect of variations in scattering strength in the lithosphere. Geological observations indicate that scattering properties can strongly vary laterally, especially in complex geological settings, e.g. in the vicinity of active tectonic or volcanic areas.

In presented work we explore the implications of non-uniform distribution of scattering strength on the spatio-temporal sensitivity of coda waves. In the first part, we numerically derive 2-D coda wave sensitivity kernels based on Monte Carlo simulations of the radiative transfer process, considering lateral heterogeneity of the crust. The kernels are calculated for three different observables, namely travel-time, decorrelation and intensity. Our results illustrate that laterally varying scattering properties can have a profound impact on the sensitivities of coda waves.

In a second part, we validate the kernels. Firstly, synthetic lapse-time based travel-time changes are calculated using the kernels for non-uniform media. Using these synthetic observations, we conduct damped least-squares inversions to localise changes in space for both a fault zone and volcanic setting. We compare the accuracy of localisation of the medium changes between inversions carried out with kernels for uniform and non-uniform media. Our results demonstrate that superior localisation of the seismic anomaly is obtained when considering local scattering information by employing kernels for non-uniform media. This holds for the fault zone as well as the volcanic setting. The stability of the results is verified by conducting inversions where 10dB white noise is added to the synthetic time-shift observations.
Nuanced responses of seasonal sea ice to a warmer Arctic climate during the Holocene Thermal Maximum
Authors: Pienkowski Anna J. , Husum Katrine , Belt Simon T. , Ninnemann Ulysses , Köseoğlu Denizcan , Divine Dmitry V. , Smik Lukas , Knies Jochen , Hogan Kelly , Noormets Riko
Published: March 2022

While climate model simulations provide valuable insight into potential future Arctic sea-ice scenarios, marine geological archives offer key information on how sea ice responded to substantial climatic warming in the past, particularly during periods characterized by warmer-than-present conditions. The HTM (Holocene Thermal Maximum), ~10.0-6.0 cal ka BP, was expressed in warmer air and ocean temperatures across the globe. Although a result of orbitally-forced summer insolation, the HTM constitutes a valuable parallel to the greenhouse-gas-driven setting of a current (and near-future) warmer world. At higher latitudes in the Northern hemisphere, the HTM has been proposed as an interval of reduced sea ice and increased Atlantic water inflow, similar to a projected future warmer Arctic Ocean. Two sediment archives elucidate the early Holocene HTM evolution of high Arctic seasonal sea ice in the northern Barents Sea (>80°N), a key area for Atlantic-Arctic Ocean water interaction in a hotspot of current climate warming. HBI (highly-branched) biomarkers (IP25, IPSO25, HBI III, HBI IV) unequivocally demonstrate the persistence of spring seasonal sea-ice as high as 55% between 11.7 and 9.1 cal ka BP. Concomitant high δ18O in benthic foraminifera and elevated phytoplankton biomarker (HBI III, HBI IV) concentrations indicate the influence of warm Atlantic-derived bottom water and peak bioproductivity, respectively. Our results highlight the nuanced and complex cryospheric response to climate warming, showing High Arctic sea ice persisting in a setting of warmer-than-present spring and summer conditions under a concomitant increased inflow of subsurface Atlantic Water. This raises important questions about the fate of Arctic sea ice, oceanography, and ecosystems (including commercially important fisheries) in an increasingly warmer climate driven by anthropogenic factors.
Assessment of the condition of Enguri High Dam in Georgia: the organisation of geodynamic monitoring
Authors: Goguadze Nino , Melikadze George , Mueller Birgit , Niederhuber Thomas
Published: March 2022

 In order to assess the reaction Enguri Dam nearby fault systems a monitoring system to study the seismicity and geodynamic situation has been set-up in recent years. To monitor the development of geodynamic processes, boreholes in the vicinity of the dam have been logged, intensively and permanent water level, temperature and conductivity monitoring was installed and where those parameters observations started to provide information about the stress field variation. The EGU presentation will introduce the different monitoring systems and present first results of data analysis. It also will show how repeated monitoring in boreholes can provide insight in the system stability.
Structure and seasonal variability of the Arctic Boundary Current north of Severnaya Zemlya 
Authors: Ruiz-Castillo Eugenio , Janout Markus , Kanzow Torsten , Hoelmann Jens , Schulz Kirstin , Ivanov Vladimir
Published: March 2022

We assessed the spatial and temporal variability of the Arctic Boundary Current (ABC) using a high-resolution array of 7 oceanographic moorings, deployed across the Eurasian continental slope north of Severnaya Zemlya in 2015-2018. In particular, we quantified transports and individual water masses based on temperature and salinity recorders and current profilers. The highest velocities (>0.30 ms-1) of the ABC occurred at the upper continental slope and decreased offshore to below 0.03 ms-1 in the deep basin. The ABC shows strong seasonal variability with velocities two times higher in winter than in summer. Compared to the upstream conditions north of Svalbard, the water mass distribution changed significantly within 20 km from the shelf edge due to mixing with- and intrusion of shelf waters. Further offshore, Atlantic Waters remained largely unmodified. The ABC transported 4.2±0.1 Sv across the region with 63-71% of the volume transport constrained within 30-40 km of the shelf edge. Water mass transport was 0.52±0.13, 0.9±0.27, 0.9±0.33 and 0.9±0.35 Sv for Atlantic Waters (AW), Dense Atlantic Water (DAW), Barents Sea Branch Water (BSBW) and Transformed Atlantic Water (TAW), respectively. A seasonality in TAW and BSBW transport was linked with temperature changes, where maximum transports coincided with minimum temperatures. Our results highlight the importance of the Barents Sea for the ABC along the Siberian slopes, and indicate that a continuing Barents Sea warming would directly translate to reductions in the TAW and BSBW cooling effect and thus lead to warmer oceanic conditions in the ABC pathway. 
Quantification of local groundwater inflow into the Spree River and its relevance to the iron precipitation problem in the Lusatian mining area (Germany).
Authors: Frei Sven , Gilfedder Benjamin
Published: March 2022

Groundwater inflow into the Spree River and its tributaries is an important factor for the iron precipitation problem of the Spree in the Lusatian mining district (Eastern Germany). The input of dissolved iron into the Spree is difficult to estimate mainly because of unknown groundwater inflow. As part of this study, the radio-active isotope 222-Radon (222Rn) was used as a natural tracer to localize and quantify groundwater inflow into the Spree River and one of its tributaries ( Kleine Spree). Based on two 222Rn monitoring campaigns in the catchment and by applying the 222Rn mass balance model FINIFLUX, we were able to quantify local groundwater inflow for a 20 km long river section of the Kleine Spree and a 34 km long section for the Spree River. For the first campaign in May 2018 total groundwater inflow was estimated with ~3,000 m³/d for the Kleine Spree and ~20,000 m³/d for the Spree River. For the second campaign in August 2018 estimated total groundwater inflows were significantly higher with ~7,000 m3 d−1 (Kleine Spree) and ~38,000 m3 d−1 (Spree). Preferential groundwater inflow areas were identified (with up to 70% of total inflow) along the Spreewitzer Rinne, a local high permeable aquifer consisting of excavated mining materials. Based on a stoichiometric ratio calculation and by measuring instream sulfate and dissolved iron loadings, we additionally were able to estimate iron precipitation rates for the entire catchment of the Spree in the Lusatian mining area. According to our calculations, for the entire catchment of the Spree River in the Lusatian mining district total iron precipitation rates reach values as high as 120 tons/day; large quantities of iron (oxy)-hydroxides that are retained within the catchment as iron precipitates.
3D geologic model of Uruk Sulcus region on Ganymede
Authors: Pozzobon Riccardo , Rossi Costanza , Lucchetti Alice , Massironi Matteo , Pajola Maurizio , Penasa Luca , Munaretto Giovanni
Published: March 2022

The surface of Ganymede, the largest satellite of Jupiter, consists of a strongly deformed and tectonized  brittle icy crust which stands on top of a large liquid body, possibly a global subsurface ocean. In fact, by means of multiple Galileo orbital mission flybys both geophysical and structural geology measurements constrained the average icy shell thickness to be comprised between 100 and 150 km. The surface can also be divided into two main units: bright and dark terrains depending on their relative albedo, impact crated density and tectonization. Furrows and grooves represent most of the structures on Ganymede’s surface, which are essentially extensional faults, dilatant structures and strike slip faults. We hereby present a 3D geologic modelling of the region of Uruk Sulcus based on structural mapping (Rossi et al., 2020) and using techniques borrowed from oil and gas exploration.

The Uruk Sulcus area is a NW-SE bright terrain of  ~400 km by ~2500 km size located between 150W-180W and 30N-10S, and characterized by pervasive sets of parallel/sub-parallel grooves of 10s-to-100s km length. The most favored hypotheses relate its formation either to a purely extensional context forming a tilt-block normal faulting, or to crustal necking with creation of horsts and grabens, or to be the result of a major dextral transpression. The overall structural framework and the fault geometries (in the form of 3D meshes) was created according to existing literature and with geologic interpretation and anchored on the surface to the global DEM by Zubarev et al., (2017), and at depth to the brittle ice-subsurface ocean interface to an average value of 120 km. This ice thickness value was obtained, among other methods, also by analyzing the scaling laws ruling the spatial distribution and the length size distribution of grooves and extensional structures, which proved to be fractal. One of the implications of this fractal behavior is that the structures themselves can be interconnected forming a percolating network favoring fluid circulation and connecting the subsurface ocean with the surface (see Lucchetti et al., 2020 and references therein).

By means of 3D modelling, we were able to isolate volumes of ice encompassed by major strike-slip structures of Uruk Sulcus and to exploit the scaling laws ruling the structures within such areas, in order to numerically simulate a DFN (digital fracture network) crosscutting the entire volume of ice.

This way we could analyze the volume of ice crosscut by such fracture network, and to predict the locations at surface where percolation is favored.

 

Acknowledgments: The activity has been realized under the ASI-INAF contract 2018-25-HH.0.
Evaluation of convective cloud microphysics in numerical weather prediction models with dual-wavelength polarimetric radar observations
Authors: Köcher Gregor , Ewald Florian , Hagen Martin , Knote Christoph , Tetoni Eleni , Zinner Tobias
Published: March 2022

The representation of microphysical processes in numerical weather prediction models remains a main source of uncertainty until today. To evaluate the influence of cloud microphysics parameterizations on numerical weather prediction, a convection permitting regional weather model setup has been established using 5 different microphysics schemes of varying complexity (double-moment, spectral bin, particle property prediction (P3)). A polarimetric radar forward operator (CR-SIM) has been applied to simulate radar signals consistent with the simulated particles. The performance of the microphysics schemes is analyzed through a statistical comparison of the simulated radar signals to radar measurements on a dataset of 30 convection days. 

The observational data basis is provided by two polarimetric research radar systems in the area of Munich, Germany, at C- and Ka-band frequencies and a complementary polarimetric C-band radar operated by the German Meteorological Service.  By measuring at two different frequencies, the dual-wavelength ratio that facilitates the investigation of the particle size evolution is derived. Polarimetric radars provide in-cloud information about hydrometeor type and asphericity by measuring, e.g., the differential reflectivity ZDR.

Within the DFG Priority Programme 2115 PROM, we compare the simulated polarimetric and dual-wavelength radar signals with radar observations of convective clouds. Deviations are found between the schemes and observations in ice and liquid phase, related to the treatment of particle size distributions. Apart from the P3 scheme, simulated reflectivities in the ice phase are too high. Statistical distributions of simulated and observed polarimetric and dual-wavelength radar signals demonstrate the challenge to correctly represent ice and rain particle size distributions. The polarimetric information is further exploited by applying a classification algorithm to obtain dominant hydrometeor classes. By comparing the simulated and observed distribution of hydrometeors, as well as the frequency, intensity and area of high impact weather situations (e.g., hail or heavy convective precipitation), the influence of cloud microphysics on the ability to correctly predict high impact weather situations is examined.
Sub-Saharan Africa's international migration and sustainable development under climate change
Authors: Li Qirui , Samimi Cyrus
Published: March 2022

In climate change, migration from sub-Saharan Africa (SSA) would affect socio-economic development in SSA and Europe. However, empirical evidence is unclear about the role of international migration in achieving sustainable development. This article first attempted to study the migration patterns and determinants between 1995 and 2020. Sustainability index and regression models were built to estimate the cascading effects of international migration on expatriates and asylum seekers in SSA or Europe and the feedback effects on SSA’s sustainable development. In particular, SSA asylum seekers into 14 European countries (EURO-14) were investigated for their push-pull factors and impacts on the socio-economic development of EURO-14. Results show that the international migration was primarily intra-SSA to low-income but high-population-density countries. Along with increased sustainability scores, international migration declined, but emigration rose. Climate extremes tend to affect migration and emigration but not universally. Dry extremes propelled migration, whereas wet extremes had an adverse effect. Hot extremes had an increasing but insignificant effect. SSA's international migration was driven by food insecurity, low life expectancy, political instability and violence, and high economic growth, unemployment and urbanization rates. The probability of emigration was mainly driven by high fertility. SSA's international migration promoted asylum seeking to Europe, with the diversification of origin countries and a motive for economic wellbeing. 1% more migration flow or 1% higher probability of emigration led to a 0.2% increase in asylum seekers from SSA to Europe. Large-scale international migration and recurrent emigration constrained SSA's sustainable development in terms of political stability, food security and health. Regarding the asylum seekers to Europe, political instability and violence of SSA were major pushing factors while high GDP per capita, low unemployment, and ageing populations of EURO-14 were major pulling factors. Development aid reduced the outflow from SSA, whereas common colonial language and migrant networks facilitated the immigration to the EURO-14. The immigration from SSA did not affect the political stability of EURO-14. In contrast, economic development was promoted by settled migrants but hampered by asylum seekers. Overall, climate change is one factor of many but not the dominant. It might gain more weight if climate change accelerates. These findings can inform policymakers of countries that continue to improve development aids, food security and political stability in SSA while promoting the integration and inclusion of immigrants in Europe for better migration management and planning towards sustainable development, besides mitigating climate change. 
Analysis of transport and mixing of generic trace gases in the martian atmosphere with MRAMS 
Authors: Pla-Garcia Jorge , Rafkin Scot C.R. , Ruíz-Pérez María
Published: March 2022

The Mars Regional Atmospheric Modeling System (hereafter MRAMS, Rafkin & Michaels, [2019]) is used to simulate, via passive (inert) tracers, the 3-D atmospheric transport, dispersion and mixing of trace gases released at different locations from instantaneous releases, and to evaluate whether air masses could make it to specific locations. The objective is to study if circulation (mean or regional) is favorable for transport trace gases from any point of the planet to specific locations. With the corresponding caveats, our modeling results can be used to investigate transport and mixing of trace gases like water vapor or methane. In these MRAMS experiments, a total of 18 tracers are strategically placed quasi-globally in the computational mother domain. Tracers are placed in 30 degree latitude belts (-90->-60, -60->-30, -30->0, 0->30, 30->60, 60->90) and then at above ground levels from 0-10 km, 10-30 km, and 30 km-model top.  We can determine from which latitude belt air is coming/going and from what level in the atmosphere.  The tracers also provide the means to quantify atmospheric mixing, diagnosed by evaluating the fraction of a given tracer mixing ratio compared to the total as a function of time. Tracer experiments show that northern high latitude air masses can be transported with very little dilution to some lower latitude locations, including Hrad Vallis and Jezero Crater.  In other locations, source air masses are highly diluted.
Evaluation of the extreme rainfall event of July 2021 in Western Germany and its impact based on the Catalogue of Radar-based Heavy Rainfall Events (CatRaRE)
Authors: Walawender Ewelina , Lengfeld Katharina , Winterrath Tanja , Weigl Elmar
Published: March 2022

Within a few days of July 2021, extreme heavy rainfall associated with the low-pressure weather system “Bernd” caused severe flooding in Western Germany (North Rhine-Westphalia and Rhineland-Palatinate), as well as in Luxembourg, and parts of Belgium and the Netherlands. In Germany, this devastating event resulted in at least 184 fatalities.

In our presentation, we take a closer look at this event as classified in the Catalogue of Radar-based Heavy Rainfall Events (CatRaRE), derived from 21 years of climatological radar data (RADKLIM 1km,1h) for the area of Germany.

The CatRaRE Catalogue covers both the attributes of all classified heavy rainfall events as well as their spatial extent. The dataset is published annually by the German Meteorological Service and is freely available for all interested users at: dwd.de/catrare.

We present the extent and parameters of this extreme rainfall as an event classified in the CatRaRE together with a comprehensive analysis and comparison against all heavy precipitation events lasting between 1 to 72 hours which occurred in Germany in the period from 2001 to 2020. Apart from various extremity statistics such as return period, heavy precipitation index, and weather extremity indices, additional variables are examined as predictors for a potential impact: e.g. antecedent precipitation index, population density, land cover, imperviousness degree and topography indices.
Inverse transfer of magnetic helicity in isothermal supersonic turbulence
Authors: Teissier Jean-Mathieu , Müller Wolf-Christian
Published: March 2022

The inverse transfer of magnetic helicity is studied through direct numerical simulations of the isothermal magnetohydrodynamics equations. Turbulent systems driven at large scales by either a solenoidal or a compressive forcing are considered, exhibiting root mean square Mach numbers ranging from 0.1 to about 10. The Fourier spectra of magnetic helicity present scaling exponents which become flatter with increasing compressibility. Considering the Alfvén velocity in place of the magnetic field leads however to more invariant spectra. A shell-to-shell transfer analysis reveals the presence of a subdominant direct transfer in the global picture of the inverse transfer, and that the inverse transport entails both local and non-local aspects. These three features (direct transfer, local inverse transfer, non-local inverse transfer) can be clearly associated with velocity fluctuations in distinct intervals of scale.

The results have been gained through a high-order finite-volume solver. Some practical aspects, benefits and challenges linked to the use of high-order numerics will also be discussed.
Chlorophyll-a estimation and evaluating the effect of land use change in a Ramsar Site of North East India
Authors: Baishya Bhaswatee , Talukdar Gaurav , Sarma Arup
Published: March 2022

Abstract

Chlorophyll concentration could potentially measure the relative productivity and health of lakes and ecosystem. The phytoplankton activities in the water bodies are measured by determining the amount of chlorophyll concentrations, which are used as a proxy for primary production and eutrophication. In addition, satellite imageries provide spatial and temporal changes that would indicate the health of the ecosystems. In this study, we have employed the Normalized Difference Chlorophyll Index (NDCI) algorithm to estimate the Chl-a concentrations based on the bands of Landsat-8 satellite imageries in the Deepor beel a Ramsar site, in Northeast India, Assam. The advantage of NDCI is that it can be used to detect algal bloom and qualitatively infer Chl-a concentration ranges, when the ground data is not available. Two spectral bands at 530 to 590 nm (Green Band) and 640 to 670 nm (Red Band) were selected to develop the index. We also performed the land use land cover (LULC) classifications from 2015-2021 within the lake using the supervised approach. The results indicated that the settlements within the area have increased due to human habitats with decrease in the marshy land, forest and vegetation cover. The runoffs from the settlements and nearby areas resulted in algal blooms, which could potentially result in reduced water quality for survival of aquatic habitats. Therefore, seasonal variability of the Chl-a concentrations during pre-monsoon and post monsoon period was intercompared over the years. It was observed that the Chl-a concentration undergoes both spatial and temporal variation. We found the values to be significantly high during the post monsoon period compared to the pre-monsoon period. Based on the analysis, the study would be of significant importance in evaluating the nutrient loading in lakes, where the fertilizer spill or toxicity levels may be an important aspect under consideration.

Keywords: Chlorophyll-a, Normalized Difference Chlorophyll Index, LULC
Investigations of comparison uncertainties for airborne validation of air quality satellite products
Authors: Merlaud Alexis , Van Roozendael Michel , Tack Frederik , Thomas Ruthtz , Ene Dragos , Calcan Andreea , Ardelean Magdalena , Constantin Daniel , Schuettemeyer Dirk
Published: March 2022

When validating atmospheric satellite observations, several error sources must be taken into account: the uncertainties of the satellite products, the uncertainties of the reference measurements, and the representativity of the latter with respect to the investigated satellite pixels. Compared to static ground-based reference measurements, airborne observations reduce the spatial component of the representativity error. Recent airborne campaigns indicate a remaining low-bias for TROPOMI tropospheric NO2 VCDs above polluted areas. This bias has been attributed in particular to wrong assumptions on the NO2 profiles in the satellite products. 

In the context of the RAMOS and SVANTE projects, we started regular continuous mapping of the NO2 tropospheric VCDs above Bucharest and Berlin, respectively. Both activities make use of compact whiskbroom imagers, namely SWING. In Bucharest, we also measure the profiles of NO2 and of aerosols from the aircraft and perform car-based DOAS measurements of tropospheric NO2 underneath the aircraft. We study the error budgets of the validation of the TROPOMI tropospheric NO2 VCD product in these two situations. We quantify the added values of the ancillary observations in Bucharest and assess the temporal component of the representativity error. Given the time duration of a scientific flight, several configurations are possible for our whiskbroom observations, and it may be useful to undersample satellite pixels to cover a large area. This work is therefore also useful to optimize the flight patterns and information content of future validation flights.
Improving calibrations of in-house water isotope standards using CRDS and OA-CRDS: memory effects versus drift
Authors: Wassenburg Jasper A. , Sinha Nitesh
Published: March 2022

The isotope composition of rainfall provides information on the initial isotope composition of the moisture source, conditions during evaporation and condensation of water vapor, and the rain-out history of an air-parcel. A standard method to analyze the rainfall isotope composition is by using Cavity Ring Down Spectrometry (CRDS). The accuracy of the analysis highly depends on the water isotope standards used, which determines the degree to which absolute values from different labs can be compared. The amount of international water isotope standards like VSMOW2 and SLAP2 primary water standards is extremely limited; therefore the International Atomic Energy Agency recommends calibrating in-house water isotope standards once a year by using VSMOW2 and SLAP2. The isotope range between VSMOW2 and SLAP2 is extreme, with 55.5‰ for d18O and 427.5‰ for d2H. The isotope range used in a sequence poses a problem for CRDS techniques that are characterized by significant memory effects.

In this study, we compare the behaviors of two different CRDS systems: a Picarro L2140i and a LGR WIA 35EP. We evaluate the relation between isotope differences of subsequent samples and the memory effect. We show that after 100 injections, memory effects may still be visible in hydrogen. Even when the isotope composition of subsequent injections of the same standard or sample does not show a trend anymore, the raw isotope data seems biased towards the isotope composition of multiple different samples or standards run prior. Running long sequences of for example 1100 injections in high precision 17O mode, also requires several vaporizer septa changes. The timing of a septa change is important, because opening the vaporizer allows water vapor from the atmosphere to enter the otherwise closed system, from which it takes approx. 20 injections to recover to the prior absolute values. Here we aim to provide a more practicle approach to a calibration sequence architecture and number of injections per primary and in-house standards, taking into account the potential drift of the analyzers.
RCM-Emulators for precipitation at daily scale
Authors: Doury Antoine , Somot Samuel , Gadat Sébastien
Published: March 2022

Delivering reliable regional or local climate change projections for the next decades that are both at fine scale and taking into account all sources of uncertainty is currently an unsolvable problem with dynamical models such as RCMs or CPRCMs. Indeed, it requires building large ensembles to capture the various sources of uncertainty (scenario choice, model choice, natural variability). However these fine scale models are very expensive to run, and the different CORDEX exercises highlight the complexity of completing large SCENARIO-GCM-MEMBER-RCM matrices. 

 

In order to tackle this issue we propose a novel hybrid downscaling method called RCM-Emulator. It aims at combining the physical basis of the dynamical downscaling approach (i.e. RCM) with the low computational cost of the empirical statistical downscaling (ESD) using recent machine learning techniques. The idea is to use existing RCM simulations to learn the transfer function from low resolution field to high resolution surface variables such as temperature or precipitation. The emulator developed here is based on a neural network architecture called UNet and is calibrated following a perfect model framework. The training dataset is a EURO-CORDEX simulation performed with the CNRM-ALADIN RCM at 12km, covering historical and scenario simulations. After presenting the concept of RCM-Emulator and the methodology used to learn the downscaling function, we will evaluate its ability to reproduce the high resolution daily precipitation over Europe in perfect conditions and finally apply it to GCM simulation outputs in order to study its transferability. If successful, this novel tool combined with specifically designed RCM simulations will allow to fill up the 4D-matrices over all CORDEX domains.
More than just fast flowing water: the landscape impact of the July 2021 west Germany flood
Authors: Bell Rainer , Dietze Michael , Thieken Annegret , Cook Kristen , Andermann Christoff , Beer Alexander , Vela Ana Lucia , Ries Johannes B. , Brell Maximilian , Eltner Anette , Roessner Sigrid , Schrott Lothar , Iserloh Thomas , Seeger Manuel , Öztürk Ugur
Published: March 2022

Rain driven flash floods have severe impacts on society and landscape functions. The July 2021 flood in the Eifel region, west Germany, was one drastic example of such impact. While media and scientists rightfully highlighted the meteorological and hydrological aspects of this flood, it was the concurrent reorganisation of important landscape conditions and the debris carried by the fast flowing water that made this flood so devastating and unpredictable.

Here, we take a process-based impact perspective and systematically ask, which were the specific roles of non-hydraulic but geomorphic dynamics that implemented the damage, caused flood non-linearities and amplified the landscape deterioration. We combine insights from field mapping campaigns during, right after and within the relaxation phase of the flood with high resolution geophysical and LiDAR surveys to discuss the role of hillslopes, vegetation, fluvial sediment mobilisation and the legacy of anthropogenic landscape reorganisation. We conclude that some of these elements emerged as the flood event evolved, causing either transient effects or persistent landscape features, thus modifying the response of the landscape to future events, also to less intense precipitation events.

Our findings not only support more tailored recovery efforts for the flood affected Eifel catchments, but should also inform landscape development trajectories and potentially crucial factors in other Central European regions.
Numerical modelling of the potential for landslide-induced tsunamis, Mount Gamalama, Indonesia
Authors: Saaduddin Saaduddin , Neuberg Jurgen , Thomas Mark , Hill Jon
Published: March 2022

Mount Gamalama is a stratovolcano forming Ternate Island in Indonesia. Collapse of the volcanoes flank has the potential to generate large tsunamis, potentially mega-tsunamis. This active volcanic island has a history of tsunami generation in 1608, 1840, and 1871. However, the generation mechanism of these tsunamis is unknown. Numerical simulation was used to understand the level of instability of the volcano flanks and the travel time and velocity of of the potential landslides and ensuing tsunamis on nearby coastlines. We also determined the factors that affect the size of the tsunami generated. An open-source finite-element code, Fluidity, was used to simulate the tsunami generation and propagation. A three-material model is considered: a viscous subaerial slide material, water, and air to capture the complex physics and interaction of the landslide and water. The results show that the subaerial mass failure takes around 2 to 6 minutes to enter the sea and can generate an initial wave of heights ranging from 35 m to 110 m. A volcanic flank collapse on Mount Gamalama would therefore have serious implications for the coastal population in neighbouring islands and submarine infrastructures like underwater cables.
Assimilated Watercolours: Pop up art exhibitions in Care Homes
Authors: Dance Sarah L , Dalton Hugo , Carolin Clare , Clark Joanna , Ferrando Jorge Nerea , Hooker Helen , Mason David
Published: March 2022

We present an ongoing series of pop-up exhibitions in residential care homes around Windsor, United Kingdom (UK).  Each display was created to give communities access to science and an understanding of research taking place in their local area. The artworks were created by artist Hugo Dalton from a residency with Prof. Sarah L Dance at the University of Reading, UK. They depict areas of her team’s research into mapping urban flooding by the River Thames. To contextualise the research and to spark interest with elderly viewers, historical watercolours of the area were also exhibited in collaboration with the Royal Collection Trust, Windsor. The watercolour genre has origins which coincide with the beginning of the Industrial Revolution: Watercolour and the picturesque movement can be seen as an early form of climate awareness.  

 

The scientific research that the collaboration builds on includes a method for detecting flooding in urban areas by merging near real-time satellite observations of flooding from Synthetic Aperture Radar (SAR) with model-derived flood hazard maps. Watercolour, as a painting medium, mirrors that the way that the data are used: Artists, like scientists, layer together different types of raw information to produce a coherent distillation for the viewer. Dalton painted in the exact locations where the scientific case studies were conducted, and developed these sketches in the studio into a series of artworks paired with scientific information.

 

For the art installation a frameless mobile fixing system was developed, working closely with the care home staff. This allowed artworks to be easily removed from the wall and inspected up close for residents with limited sight, or moved into the rooms of bed-bound residents. The reverse side of each had a short explanatory text.  Members of care home staff visited the artist’s studio to gain a deeper insight into the art and science. They could then recount this knowledge to their communities, becoming citizen advocates. Staff also used the artworks as starting points for activities.

 

This science-art collaboration empowers communities to understand and feel proud of science in their local area. The project’s wide reach extended beyond the residents to those who visited the homes, including relatives and their children.  Each paired set of artworks formed a talking point and enlivened the visual surroundings. Being geographically linked to their location the artworks provided a way for residents to share their lived experience of climate change. The future aim is to partner with other venues, including public houses and village halls to widen audience engagement.

 

 
Road network exposure, connectivity and hierarchy as input to assess landslide risk hotspots
Authors: Marques da Costa Nuno , Oliveira Sérgio C. , Zêzere José L. , Morgado Paulo , Rocha Jorge , Melo Raquel
Published: March 2022

From the territorial land use planning perspective new urban areas have been safeguarded during the last decades by the Portuguese regulation and practice that consider land use restrictions on landslide hazard prone areas. Nevertheless, the fatalities due to landslides did not reduce in number, mostly due to the occurrence of rapid shallow landslides, affecting people inside buildings and more recently, inside vehicles, as a consequence of the increasing people’s mobility. When the exposure is to deep-seated landslides, structures and infrastructures frequently undergo intense destruction, leading to severe disruption of economic and social activities.

The present work intends to evaluate actual exposure of road network to landslides in the context of a Landslide Early Warning System (LEWS) prototype, developed upon both soft and low-cost technology. To achieve this main goal, three specific objectives were defined: (i) to evaluate the road network exposure considering different road types; (ii) to evaluate the re-routing of circulation for users, the loss of access to functions or services, due to travel time increase; and (iii) to evaluate the road network connectivity hierarchy and its contribute to define landslide risk hotspots for evacuation and rescue access in case of disastrous landslide events.

The study area corresponds to four municipalities (Alenquer, Arruda dos Vinhos, Sobral de Monte Agraço and Vila Franca de Xira) that are partially included in the Grande da Pipa River (GPR) basin, which is one of the most landslide prone areas in Portugal. The road network hierarchy data is based on available official road network maps; the road segment connectivity role in regional network is based on graph analysis; and the landslide risk hotspots - are classified by combining the different types of road segments, the re-routing travel time scenarios and the road network hierarchy and network connectivity function with the shallow and deep-seated landslide maps produced in the context of the BeSafeSlide project.

The final results will be incorporated on the LEWS prototype, which is conceptualized to be people-centred, which means, not specifically focused on hazardous processes, but on reducing exposure and vulnerability, allowing an effective implementation of risk management strategies, contributing for increasing resilience and adaptive capacity building of local communities.

Acknowledgments: This work was financed by national funds through FCT (Foundation for Science and Technology, I. P.), in the framework of the project BeSafeSlide – Landslide early warning soft technology prototype to improve community resilience and adaptation to environmental change (PTDC/GES-AMB/30052/2017), and the Research Unit UIDB/00295/2020 and UIDP/00295/2020.