bluuebunny/crossref_metadata_2025 huggingface dataset:
Linking future Gulf Stream warming and increased European winter precipitation in an eddy-rich model
Authors: Moreno-Chamarro Eduardo , Caron Louis-Philippe , Ortega Pablo , Loosveldt Tomas Saskia , Roberts Malcolm J. , Carreric Aude , Frigola Amanda , Martín Martínez Eneko
Published: February 2023

This contribution discusses future changes in Gulf Stream temperatures, winter precipitation over northwestern Europe, and their connection. We compare HighResMIP historical and ssp5-8.5 scenario simulations generated with five different configurations of the global coupled model HadGEM3-GC3.1, including one at a pioneering 50-km-atmosphere–1/12°-ocean global resolution. The highest resolution model projects an increase in winter rainfall over Europe outside or to the extremes of multimodel ensembles, such as CMIP6 and HighResMIP, for which both the highest ocean and atmosphere resolutions are essential: on the one hand, only the eddy-rich ocean (1/12°) projects a progressive northward shift of the Gulf Stream and substantial surface warming of the region; on the other, only the 50-km atmosphere translates such warming into strengthened extratropical cyclone activity over the North Atlantic and, hence, increased rainfall over Europe. The results suggest that climate projections relying on traditional ~100-km-resolution models might underestimate climate changes in the North Atlantic and Europe, demonstrating the importance of improved Gulf Stream representation for robust uncertainty estimates of climate risk.We also present the first results of the STREAM project, which aims to study the role of the ocean mesoscale in driving North Atlantic and European climate variability and predictability. We describe the results of the HighResMIP simulations generated with the EC-Earth global climate model at the T1270-ORCA12 resolution (about 15 km in both the atmosphere and the ocean) and explore the main model biases and response to climate change, as well as the variability in the North Atlantic circulation associated with subpolar oceanic deep mixing. 
The drivers of decadal fluctuation in the global mean sea level rise
Authors: Cha Hyeonsoo , Moon Jae-Hong , Kim Taekyun , Song Y. Tony
Published: February 2023

Recent advances in satellite and in-situ measurements have enabled the monitoring of GMSL budget components and provided insights into ocean effects on the Earth’s energy imbalance and hydrology. The global mean sea level rise slowed over the 2000s, which coincides with a global warming hiatus period, but has accelerated again since 2011. This decadal fluctuation in GMSL rise can be attributed to climate-related fluctuation in ocean heat and mass change. Sea level and Earth’s energy budget results demonstrate that the decadal climate variability has resulted in ocean mass loss and decreased ocean heat uptake, slowing the GMSL rise rate during the 2000s. After ~2011, the climate-driven fluctuations of ocean mass, heat, and GMSL rise rate were reversed. This result highlights the importance of natural variability in understanding the ongoing sea-level rise.
Labile and Stable Soil Organic Carbon in abandoned lands with different management
Authors: Nadal Romero Estela , Cortijos-López Melani , Llena Manel , Cammeraat Erik , Lasanta Teodoro
Published: February 2023

Soil is a key element in the Earth system, and changes in land management can affect soil organic carbon (SOC) dynamics and the provision of ecosystem services related to soil. The content and stock of SOC has been adopted as the measure to be used for land degradation assessment. Nevertheless, SOC dynamics linked to land use and land cover changes after land abandonment is still a controversial issue. From the mid-20th century, Mediterranean mountains have undergone intense transformations due to climate change and severe socio-economic marginalisation, linked to depopulation and cropland and pasture abandonment. These processes led to a very different landscape, with a massive invasion of shrubs, secondary succession to forest and afforested areas. The objective of this study is to analyse the effects of post-land abandonment management practices on soil organic carbon dynamics (stocks and fractions). We selected three land abandonment scenarios in the Central Pyrenees: (i) natural revegetation with broadleaf vegetation; (ii) natural revegetation versus afforestation with coniferous forest; and (iii) abandonment of grasslands and woody encroachment. The total SOC stocks and fractions (through density fractionation) were analysed: Free light Fraction (FLF), Occluded Light Fraction (OLF), and Heavy Fraction (HF). Results showed that: (i) revegetation resulted in a constant and slow SOC accumulation processes; (ii) grassland enhanced accumulation of SOC, and the woody encroachment of these areas produced a significant loss of SOC during the first revegetation stages; (iii) density fractions were significantly affected by land use and land cover changes; (iv) the labile fractions (FLF and OLF) were significantly higher under coniferous forest than under grassland and shrubland; and (v) differences were also observed between coniferous and broadleaf forest, suggesting that broadleaf litter is incorporated faster in the mineral soil. The present study showed that land abandonment in Mediterranean mountains does not only affect SOC stocks, but also triggers the addition of labile carbon into the soil. It also changes the dynamics and sequestration of stable SOC, making this information essential in the design of future post-land abandonment strategies. Acknowledgements: This research project was supported by the MANMOUNT (PID2019-105983RB-100/AEI/ 10.13039/501100011033) project funded by the MICINN-FEDER and the PRX21/00375 project funded by the Ministry of Universities of Spain from the “Salvador de Madariaga” programme. Melani Cortijos-López is working with an FPI contract (PRE2020-094509) from the Spanish Ministry of Economy and Competitiveness associated to the MANMOUNT project. Manel Llena has a “Juan de la Cierva Formación” postdoctoral contract (FJC2020-043890-I/AEI/ 10.13039/501100011033) from the Spanish Ministry of Science and Innovation.
Urban influences on rainfall interception of different tree species
Authors: Anys Markus , Weiler Markus
Published: February 2023

The rapid expansion of impermeable surfaces in cities has a major impact on hydrology and meteorology. The infiltration of rainwater is reduced resulting in more overland flow with higher peak flows, but also reduced evapotranspiration and hence higher sensible heat flux. Urban trees are becoming more important as stormwater management or climate adaptation tools. The rainfall interception of trees already reduces overland flow generation and increases latent heat flux. An in-situ field experiment to measure throughfall on the common urban trees Acer platanoides (Norway maple) and Tilia cordata (small-leaved lime) was conducted to determine the interception of solitary trees on urban sites with different degrees of surface sealing and shading from surrounding buildings in the city of Freiburg, Germany. The influence of rainfall characteristics and tree morphological traits on interception behaviour was investigated with eight trees per species. 76 recorded rainfall events were evaluated from April to September 2021. The recorded interception rates were much higher compared to typical values in forests. Average interception rates were higher for T. cordata (70.29 ± 6.56%) than for A. platanoides (54.76 ± 10.29%). The average interception loss of the recorded events per tree was 2.58 ± 0.60 mm and 3.73 ± 0.29 mm for A. platanoides and T. cordata, respectively. For both tree species, significant linear correlations were found between the relative interception values and other factors like rainfall characteristics, the leaf area index (LAI), and the plant area index (PAI) (adj.R2 > 0.45). Compared to A. platanoides, T. cordata showed significant relationships between several tree morphological parameters (CR, CPA, CC, CV, LAD, PAD) and the relative interception values (adj.R2 > 0.43). The lowest LAI of both tree species were observed at sites with highest degree of surface sealing (tree pits), which also impacts the interception process. Our results provide a better understanding of the interception process of solitary trees for different urban settings. However, further field experiments with various tree species need to be conducted in order to obtain a larger database for simplified applications in modelling approaches and to support urban planners in managing stormwater runoff and adapt to climate change.
Bioenergetic control of soil carbon dynamics across depth
Authors: Henneron Ludovic , Balesdent Jerôme , Alvarez Gaël , Barré Pierre , Baudin François , Basile-Doelsch Isabelle , Cécillon Lauric , Fernandez-Martinez Alejandro , Hatté Christine , Fontaine Sébastien
Published: February 2023

Soil carbon dynamics is strongly controlled by depth globally, with increasingly slow dynamics found at depth. The mechanistic basis remains however controversial, limiting our ability to predict carbon cycle-climate feedbacks. Combining radiocarbon and thermal analyses with long-term incubations in absence/presence of continuously 13C/14C-labelled plants, we show here that bioenergetic constraints of decomposers consistently drive the depth-dependency of soil carbon dynamics over a range of mineral reactivity contexts. The slow dynamics of subsoil carbon was tightly related to both its low energy density and high activation energy of decomposition, leading to an unfavorable ‘return-on-energy-investment’ for decomposers. We also observed strong acceleration of millennia-old subsoil carbon decomposition induced by roots (‘rhizosphere priming’), showing that sufficient supply of energy by roots is able to alleviate the strong energy limitation of decomposition. These findings demonstrate that subsoil carbon persistence results from its poor energy quality together with the lack of energy supply by roots due to their low density at depth. These findings provide insights into the bioenergetic control of SOC persistence and indicate that an increase in plant rooting depth induced by global change could threaten the storage of millennia-old SOC in deep layers.
Carbon Isotopic Composition of Carbonates of the Okcheon Metamorphic Belt in South Korea from Neoproterozoic to Early Cambrian Potential: Geological and Tectonic Significance
Authors: Park Kye-Hun , Ha Youngji
Published: February 2023

There has been considerable debate as to whether the Korean peninsula has evolved as part of the Sino-Korean Craton since Neoarchean or whether it is a product of the amalgamation of several continental fragments in the early Mesozoic Era. The relationship between the Neoproterozoic Okcheon Metamorphic Belt (OMB) and the Early Paleozoic Tabaeksan Basin (TB) in the central region of the Korean Peninsula has the potential to provide an answer to this question. Various carbonate rocks appear in OMB, showing unique carbon isotope values ​​according to their geologic age.The Hyangsanni Dolomite is distributed around the Gyemyeongsan Formation with metavolcanics of about 860 Ma. The Hyangsanni Dolomite has δ13C values between +2.9 ‰ and +6.2 ‰, markedly higher than the Cambro-Ordovician values, and are consistent with the Neoproterozoic values. Considering the low values ​​of 86Sr/87Sr, the deposition period of the Hyangsanni Dolomite is judged to be Tonian before the Sturtian Glaciation.The Geumgang Limestone has a maximum thickness of several tens of meters adjacent to the diamictite layer proposed as a glacial deposit but shows a very extensible distribution. The δ13C values ​​of the Geumgang Limestone range from -12.25 to -7.88 ‰, suggesting that they may be cap carbonates. However, whether their deposition was related to the Sturtian Glaciation or the Marinoan Glaciation is not yet known.Between the Cryogenian Seochangri Formation of OMB and the Cambrian Jangsan Formation of TB are carbonate rocks previously considered Ordovician. However, carbon and oxygen isotope values analyzed in this study require different interpretations. Zones with δ13C values ​​ranging from -3.4 to +1.3 ‰ agree with Ordovician seawater values. However, over a larger area, δ13C values ​​show mostly positive values ​​from +1.9 to +7.8 ‰. Also, a significant negative excursion of δ13C values ​​down to -6.9 ‰ occurs near the highest values ​​measured. These values correlate with Ediacaran or Early Cambrian carbonates better than Ordovician seawater. It is the first to discover the possible carbonate rocks of Ediacaran or Early Cambrian in South Korea, supporting that the Neoproterozoic OMB and Early Paleozoic TB have a tectonic evolutionary history of continuous deposition rather than an assembly of different continental fragments.
A high-resolution view on mesoscale eddy activity in the Eurasian Basin
Authors: Müller Vasco , Wang Qiang , Danilov Sergey , Koldunov Nikolay , Li Xinyue , Jung Thomas
Published: February 2023

Mesoscale eddies might play a substantial role for the dynamics of the Arctic Ocean, making them crucial for understanding future Arctic changes and the ongoing ‘atlantification’ of the Arctic Ocean. However, simulating high latitude mesoscale eddies in ocean circulation models presents a great challenge due to their small size and adequately resolving mesoscale processes in the Arctic requires very high resolution, making simulations computationally expensive.Here, we use a seven-year simulation from the unstructured‐mesh Finite volumE Sea ice-Ocean Model (FESOM2) with 1-km horizontal resolution in the Arctic Ocean. This very high-resolution model setup can be considered eddy resolving and has previously been used to investigate the distribution of eddy kinetic energy (EKE) in the Arctic. Now, with a simulation spanning several years, we evaluate the changes of EKE in the Eurasian Basin and the connection to other properties like sea-ice cover, baroclinic conversion rate and stratification. EKE seasonality is influenced predominantly by sea-ice changes, while monthly anomalies have different drivers for different depths levels. The mixed layer is strongly linked to the surface and thus to sea-ice variability. Deeper levels on the other hand are shielded from the surface by stratification and influenced more strongly by baroclinic conversion.
Simulation of diPAP Transformation and Related Metabolite Leaching Under Near-Natural Conditions
Authors: Weidemann Eva , Lämmer René , Göckener Bernd , Bücking Mark , Gassmann Matthias
Published: February 2023

Per- and polyfluoroalkyl substances (PFAS) are organic contaminants which are ubiquitous in the environment and anthropogenically manufactured. The presence of PFAS in the environment is connected to their production, use and disposal, i.e. the whole life cycle. Contact with organisms can have adverse effects such as toxicity, bioaccumulation and carcinogenicity depending on the specific compound. There are several thousands of different PFAS with different structures and properties, which differ in their environmental behaviour as well. One example is biotransformation, which is not observed for all PFAS, such as the persistent group of perfluoroalkyl acids (PFAAs). Other PFAS, such as polyfluoroalkyl phosphate diesters (diPAP), act as precursors which are transformed into the stable PFAAs. When released to the environment, it is important to have information about the relevant processes such as adsorption, transformation and formation of non-extractable residues (NER).In this study, leaching simulations were performed using a multi-objective parameter optimization algorithm (caRamel) in R connected to the MACRO 5.2 model. The simulation is based on a lysimeter study with two transformable precursors (6:2 diPAP and 8:2 diPAP) under near-natural conditions and a duration of two years. Objective functions of masses in the percolation water, in the soil and in the grass, planted on the lysimeter, were optimized simultaneously for diPAPs and related persistent PFAA metabolites. The model setup was based on past leaching simulations of soil columns with similar soils, the same substances and the same study duration. A comparison of lysimeter and soil column simulations indicates temperature-affected transformation kinetics, which could be related to the microbial activity. In further studies, the influence of environmental parameters on the transformation of diPAPs should be focussed to evaluate the results of this study.
Multiscale geophysical characterization of the continental crust of the Central Asian Orogenic Belt
Authors: Guy Alexandra , Schulmann Karel , Tiberi Christel , Ebbing Jörg
Published: February 2023

The Central Asian Orogenic Belt (CAOB) is a Paleozoic accretionary-collisional orogen located at the eastern Pangea in between the Siberian Craton to the north and the North China and Tarim cratons to the south. Several contradictory geodynamic models were proposed to explain the tectonic assemblage: oroclinal bending and strike-slip duplication of a giant intraoceanic arc or a progressive lateral accretion of linear continental and oceanic terranes towards the Siberian Craton. However, none is generally accepted. A multidisciplinary and multiscale approach integrating potential field analysis and modelling provides new insights into understanding the crustal structures beneath the CAOB.First, we present a synthesis of the previous geophysical studies, which constitute the constraints for the modelling. Second, based on global gravity and magnetic anomaly grids, the large-scale statistical analysis of their lineaments reveals the distribution of the contrasting tectonic zones. Then, the topography of the Moho is determined by 3D forward modelling of the GOCE gravity gradients, which is then integrated into 2D and 3D crustal scale models of southern and central Mongolia. A geodynamic model is derived from the resulting crustal architectures. Thus, the combination of these methods allows us to: (1) unravel the existence and distribution of suspect terranes in accretionary systems; (2) correlate the contrasting tectonic zones with the gravity and magnetic signals and the thickness of the crust, thereby revealing the inheritance of Paleozoic and Mesozoic orogenic history; and (3) determine the significance and possible origin of the major anomalies, which are related to tectonic processes such as lower crustal relamination, presence of deep-seated fault zones and sutures, or delimitation of main tectonomagmatic domains. Finally, with the case study of Central Mongolia, we demonstrate the real benefit and the significant progress, which can be achieved by using potential field analysis combined with seismic receiver function and geological analyses.
Projected changes in precipitation variability over Europe in CMIP6 climate models
Authors: Plavcová Eva , Beranová Romana , Huth Radan , Lhotka Ondřej
Published: February 2023

Changes in the amount, intensity, frequency and type of precipitation are observed in some places over recent decades (IPCC 2021). While much effort has been devoted to analyzing long-term changes in mean values and extremes, studies on changes in precipitation variability have been rather scarce. Long-term changes in climate variability are, nevertheless, an important aspect of the climate change with various impacts on society and environment. Therefore it is necessary to know whether and how the precipitation variability will change in the future. To this end, it is important that it is simulated correctly by recent climate models. In our study, we analyze outputs from an ensemble of different CMIP6 global climate models and several reanalyses and gridded observed datasets. We study long-term changes in day-to-day precipitation variability and how they differ between various datasets for the historical and current climate. We evaluate how successful the climate models are in reproducing precipitation variability, while identifying biases and errors common to all models or to groups of models. We analyze projected changes of short-term precipitation variability in model simulations over the whole 21st century. We focus on the North Atlantic-European sector. We consider wet-to-wet and dry-to-dry transition probabilities as a measure of short-term precipitation variability, focusing on winter and summer seasons separately. Ref.: IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)].
Impacts of climate change on temporal fragmentation of energy demand in Europe
Authors: Filahi Hajar , Omrani Hiba , Drobinski Philippe , Claudel Sandra
Published: February 2023

The energy demand will potentially be affected by climate change in the future. The heating needs are expected to decrease while the cooling needs are expected to increase under projected future global warming. The question addressed in this work in the impact and the quantification of this changes on the temporal fragmentation of energy demand during winter and summer. This fragmentation creates a need for flexibility in energy production which constitutes a challenge for energy systems. In this work, the question is addressed by exploiting a biais-corrected and downscaled climate projections from CMIP6 simulations using a statistical method at a spatial resolution of 0.25° x 0.25° over Europe. Ten variables were used to estimate the main change on energy demand related to heating degree days (HDD) and cooling degree days (CDD) under four scenarios (ssp1-2.6, ssp2-4.6, ssp3-7.0 and ssp5-8.5). The results showed a large decrease of HDD over Europe and an increase of CDD under all of scenarios ssp considered in this work. The analyses of the heating and air conditioning period duration and frequency showed a fragmentation of the periods of use of heating during winter in the future which can lead potentially to a fragmentation of energy demand related to heating. On the other hand, the periods of use of air conditioning in summer are expected to be more frequent and longer but still very fragmented in time compared to the present climate.
Seismic background level growth can reveal slowly developing long-term eruption precursors – A case study at Kirishima volcano, Japan
Authors: Ichihara Mie , Ohminato Takao , Konstantinou Kostas , Yamakawa Kazuya , Watanabe Atsushi , Takeo Minoru
Published: February 2023

The accelerating growth of seismic unrest before eruptions has been observed at many volcanoes and utilized for eruption forecasts. However, there are still many eruptions for which no precursory unrest has been identified, even at well-monitored volcanoes. The recent eruptions of Shinmoe-dake, an active cone of Kirishima volcano, Japan, had been another negative example of this kind. Here we present seismological evidence that the eruption preparation had been ongoing at the shallow depths beneath Shinmoe-dake for several months to a year.We investigated the seismic background level (SBL) of eleven-year data recorded around the volcano, including two stations about 1 km from the eruptive crater. We searched for persistent weak signals, focusing on low-amplitude time windows recorded during quiet nighttime. Then the spectra of daily background noise were classified by clustering analysis. The SBL analysis successfully revealed very weak precursory tremors from more than several months before the eruption, and residual tremors to the end of the eruptive period. The precursory signals grew acceleratory in a similar way as is assumed in the material failure forecast method applied to eruption forecasts. However, their growth was significantly slower and longer compared to previous cases. Such slow and quiet preparations would not be captured by conventional seismological methods but could be a common feature at volcanoes with developed hydrothermal systems. It is also noted that the SBL monitoring is potentially useful to judge the end of an eruption period. Further studies are necessary for clarifying the source locations and mechanisms of the SBL noise.
Modeling fluid-driven seismic cycles in subduction zones
Authors: Hegyi Betti , Dal Zilio Luca , Behr Whitney , Gerya Taras
Published: February 2023

Various geological and geophysical observations from different subduction zones attest to the importance of pore pressure fluctuations and fluid flow in triggering regular earthquakes, slow slip events and tectonic tremors. We use the Hydro-Mechanical Earthquake Cycle (H-MEC) code to model fluid-driven earthquake cycles in a subduction megathrust environment. The code uses  a finite differences-marker in cell method, and couples solid rock deformation with fluid flow. The code solves the mass and momentum conservation equations for both solid and fluid phases, with the addition of gravity and temperature-dependent viscosity. The brittle/plastic deformation is resolved through a rate-dependent strength formulation and the development of slip instabilities is governed by compaction-induced pore fluid pressurization. With such code we can demonstrate how the fluid pressurization can lead to localisation of deformation with slip rates up to m/s in a fully compressible poro-visco-elasto-plastic media. The models can reproduce all slip modes observed in nature from regular earthquakes to transient slow slip phenomena to aseismic creep. Here we investigate various controls on dominant slip mode and their expected distributions and interactions along a subduction interface model setup. Our initial results show that the dominant slip mode depends on porosity, permeability, plastic dilatation and viscosity of the matrix. An increase in the porosity will lead to aseismic deformation in the form of slow slip events and creep. We also investigate the effects of inclusions (clasts) along the subduction channel, acting as stress heterogeneities, with physical properties different from the subduction channel. We attempt to understand the role of inclusions with different viscosities and permeabilities embedded in the matrix. With this numerical framework, we can better understand fluid-driven seismicity, and the effects of fluids on long-term geodynamic processes. Our study also contributes to better understand the role of fluid pressure cycling in seismic and aseismic deformation in subduction zone environments, as well as provides new insights in the role of stress heterogeneities within the frictional-viscous shear zone. 
A portable, high-precision optical analyzer based on hybrid laser absorption cell for simultaneous measurements of N2O, CH4, and CO2 fluxes from soils
Authors: Yu Longfei , Wang Ying , Niu Zetong , Su Zhelin , Zheng Lintao , Lin Ting-Jung
Published: February 2023

Laser spectrometers have shown good capability in measuring mixing ratios for atmospheric greenhouse gases (GHGs). Given the fact that spectral bands of CO2, CH4, and N2O covering from near to mid-infrared (NIR to MIR) wavelengths, and the limitations in the wavelength coverage of the laser and photodetector, it is very challenging to analyze CO2, CH4, and N2O simultaneously for most cavity-enhanced analyzers using NIR lasers. Alternative solutions, such as combining multiple quantum cascade laser (QCL) beams and analyzing all GHGs in the MIR wavelengths, would significantly increase the instrumental cost.Here, we present a recently developed analyzer utilizing the advantages of detecting CO2/H2O in the NIR spectral region and N2O/CH4 in the MIR region, respectively. Through a unique optical design, two independent optical paths are formed in a single Herriott gas cell so that low temperature-related drift and mechanical robustness are achieved. The mixing ratios of CO2 and H2O are analyzed by a NIR laser and a photodetector at ~4995cm-1, while CH4 and N2O are analyzed by a QCL and an MCT photodetector at ~1275cm-1. The analyzer facilitates high-sensitivity, field-deployable measurements of CO2, CH4, N2O and H2O altogether in a compact, portable instrumental design. In addition, this analyzer can be completely powered by rechargeable battery, facilitating all-day in situ measurements without grid power supply.In the laboratory, side-to-side comparisons were performed between our newly developed analyzer and another commercial gas analyzer based on cavity ring down spectroscopy (CRDS). The results showed high consistency in GHG mixing-ratio measurements with the two spectrometers. Attached to soil chambers, we also found comparable performance of two analyzers in determining GHG fluxes. In particular, we found that the presented analyzer could precisely capture transient changes in gas mixing ratios from the soil chamber. Recently, field deployment in different soil conditions, including upland forest soils and riparian soils, was carried out for simultaneous N2O, CH4, CO2 soil flux measurements. The overall results suggest that our analyzer is suitable for continuous GHG flux monitoring under variable field conditions, and shows potentials in simultaneous measurements of multiple GHG fluxes from natural ecosystems.
Characterizing hydrologic similarity of precipitation and catchment wetness using repeating patterns in runoff
Authors: Hövel Adriane , Bogena Heye , Lücke Andreas , Stumpp Christine , Stockinger Michael
Published: February 2023

Understanding the reasons why a certain combination of precipitation event and catchment wetness condition causes a particular runoff response serves as the basis for a sustainable water resources management. Runoff responses at the catchment scale are highly variable in space and time due to numerous influencing factors, e.g., topography, land use, geology, and climatic conditions. Yet, despite previous studies having investigated these interdependencies, it remains difficult to differentiate between the various impacts on the runoff response and to determine which driving factors dominate under which conditions. Assuming that similar precipitation and catchment wetness (e.g. in terms of soil water content or groundwater level) lead to similar runoff responses, reoccurring patterns of these hydrological flux and state variables may be useful to assess the causes for similar or different runoff responses. Therefore, we compared precipitation and catchment wetness conditions and classified them as hydrologically similar if they lead to a similar runoff response. In this study, the similarity of runoff responses was assessed for the 38.5 ha, partly forested Wüstebach catchment in Western Germany using the goodness-of-fit (GOF) criteria Nash-Sutcliffe-Efficiency and Volumetric Efficiency. If the GOF exceeded a pre-defined threshold, the runoff responses were classified as similar and grouped together. Subsequently, for similar runoff responses, the corresponding rainfall and wetness conditions were compared calculating the Spearman’s rank correlation coefficient and descriptive statistics. A total of 22 similar out of 73 runoff events were identified for the Wüstebach catchment over a period of nearly 12 years and classified into seven groups with the largest group including in total eight events. Results show that for similar runoff responses in this representative group, soil water content as well as groundwater levels in the riparian zone are well correlated with r = 0.815 and r = 0.840, respectively, indicating a possible dominant control on runoff responses. However, rainfall patterns show overall weak correlations (r = 0.406), implying that the precipitation temporal pattern control on the runoff response might be limited for these types of runoff events in the Wüstebach catchment. In a next step, the here defined hydrologically similar precipitation and wetness conditions will be searched in the data of the Wüstebach catchment to compare the corresponding runoff responses, and hydro-meteorological variables will be used to explain similar or different runoff responses. 
Stoichiometrically constrained soil microbial community adaptation modeled with SESAM
Authors: Wutzler Thomas , Ahrens Bernhard , Schrumpf Marion
Published: February 2023

Describing the coupling of nitrogen (N), phosphorus (P), and carbon (C) cycles of land ecosystems requires understanding microbial element use efficiencies of soil organic matter (SOM) decomposition. These efficiencies are studied by the soil enzyme steady allocation model (SESAM) at decadal scale. The model assumes that the soil microbial community and their element use efficiencies develop in a way that maximizes the growth of the entire community. Specifically, SESAM approximated this growth optimization by allocating resources to several SOM degrading enzymes proportional to the revenue of these enzymes, called the Relative approach. However, a rigorous mathematical treatment of this approximation has been lacking so far. Therefore, this study derives explicit formulas of enzyme allocation that maximize total return from enzyme reactions, called the Optimal approach. When comparing predictions across these approaches, we find that the Relative approach is a special case of the Optimal approach valid at sufficiently high microbial biomass. However, at low microbial biomass, it overestimates  allocation to the enzymes having lower revenues.The model finding that a smaller set of enzyme types is expressed at low microbial biomass provides another hypothesis for why some substrates in soil are preserved over decades although being decomposed within a few years in incubation experiments. This study is another step in integrating a simple representation of an adaptive microbial community into coupled stoichiometric CNP SOM dynamic models. 
Detecting Critical Slowing Down under the influence of continuous-time Red Noise
Authors: Morr Andreas , Boers Niklas
Published: February 2023

The observational research of tipping elements in the climate system relies largely on time series analysis via so-called Early Warning Signals. An upward trend in the estimated variance or lag-1 autocorrelation of the observable may be a sign for Critical Slowing Down (CSD), a phenomenon exhibited during the destabilization a system’s fixed point. This approach has been employed extensively both for assessing contemporary tipping risks [1] and understanding the dynamics in the advent of past abrupt climate change [2]. However, this inference of destabilization from statistical observations is in general only valid under certain model assumptions with regard to both the deterministic dynamics and the stochastic component (noise). While the assumption of additive white noise is the most canonical approach to representing unresolved dynamics, it has long been understood that certain variabilities in the climate system exhibit correlation and persistence [3]. In this case, trends in the above indicators should no longer be attributed solely to CSD, since they may also be rooted in possibly changing correlation characteristics of the driving noise. While there has been progress in the development of indicators for discrete-time models incorporating correlated noise [4], the task of assessing discrete-time data from continuous-time models has not received as much attention. We present a simple linearly restoring stochastic model with red noise as its driving force and discuss possible avenues of estimating system stability from time series data through the autocorrelation structure and power spectral density of the observable. We quantitatively compare these methods to conventional Early Warning Signals, highlighting the potential pitfalls of the latter in this setting. [1] Boers, N. (2021). Observation-based early-warning signals for a collapse of the Atlantic Meridional Overturning Circulation. Nature Climate Change 11[2] Rypdal, M. (2016). Early-Warning Signals for the Onsets of Greenland Interstadials and the Younger Dryas–Preboreal Transition, Journal of Climate, 29(11)[3] Mann, M.E., Lees, J.M. (1996). Robust estimation of background noise and signal detection in climatic time series. Climatic Change 33[4] Rodal, M., Krumscheid, S., Madan,G. , LaCasce, J.H., and Vercauteren, N. (2022). Dynamical stability indicator based on autoregressive moving-average models: Critical transitions and the Atlantic meridional overturning circulation, Chaos 32
Hybrid generation based on machine learning to enhance numerical simulation for earthquake
Authors: Jacquet Gottfried , Clouteau Didier , Gatti Filippo
Published: February 2023

In the last decades, geophysicists have developed numerical simulators to predict earthquakes and other natural catastrophes. However, the more precise the model is, the higher the computational burden and the time to results. In addition, even if we could reproduce the phenomenon with more complex and more representative models, the underlying uncertainty would remain significantly high, affecting the reliability of the final prediction. In response to this challenge, we adopted a hybrid strategy, consisting into mixing physics-based numerical simulations and machine-learning. The goal is to transform synthetic earthquake ground motion, obtained via physics-based simulation, accurate up to a frequency of 5 Hz, into a broader-band prediction that mimics the recorded seismographs. In doing so, we factorize the latent representation of the seismic signal, by forcing an encoding that splits features into two parts: a low frequency one (0-1 Hz) and a high frequency one (1-20 Hz). In the following, we train a convolutional U-Net neural network and apply two different signal-to-signal translation techniques: pix2pix and BiCycleGAN. The latter strategies are compared with the prior work of Gatti et al., 2020, on the Stanford Earthquake Dataset (STEAD) showing their capability of mimicking recorded seismographs. We finally tested the two strategies on the synthetic time-histories obtained for the 2019 Le Teil earthquake (France).   
Ground-based imaging of NO2 emission plumes from Bełchatów Power Station using a hyperspectral camera
Authors: Külheim Felix , Knapp Marvin , Scheidweiler Leon , Kleinschek Ralph , Jagoda Paweł , Nęcki Jarosław , Butz André
Published: February 2023

Nitrogen oxides (NOx  = NO + NO2) are atmospheric pollutants that are detrimental to air quality and human health and play a major role in tropospheric ozone chemistry. Combustion processes produce NOx; thus, coal-fired power plants contribute significantly to the emission total (EEA 2017). Imaging atmospheric NOxcolumns with the Differential Optical Absorption Spectroscopy (DOAS) method is a well-established tool for NOx  emission monitoring (e.g. Lohberger 2004; Manago 2018). During field measurements in June 2022, we deployed a ground-based hyperspectral camera (HySpex) for the visible to near-infrared (VNIR) spectral range at a distance of 6 km from the largest coal-fired power plant in Europe, the Bełchatów Power Station in Poland. We present preliminary results of NO2  emission plume images using sky-scattered sunlight as the light source. Our HySpex VNIR-1800 hyperspectral camera records spatially highly resolved images with 2400 pixels horizontally and 1800 pixels vertically covering a 22°x16.5° field of view at a temporal resolution of ∼1 minute. The camera covers the spectral range between 400 nm and 1000 nm with a spectral resolution of ∼5 nm and sampling intervals of 3.2 nm. We retrieve pixel-wise differential slant column densities of NO2  using DOAS in the 420 - 550 nm spectral interval. Despite the low spectral resolution, NO2  absorption structures can be identified and fitted, as we demonstrate by lab measurements with pre-calibrated NO2  cells.We examine the performance of the NO2  camera and the potential for combining it with a co-deployed carbon dioxide (CO2) HySpex camera that operates in the shortwave-infrared spectral range. Simultaneous observations of NO2  and CO2  might enable insights into plume dynamics, photochemical processing in the plume and the emission ratio of the two species. References:European Environment Agency, 2017. Releases of pollutants to the environment from Europe’s industrial sector – 2015. url: https://www.eea.europa.eu /publications/releases-of-pollutants-to-the/releases-of-pollutants-from-industrial-sector (visited on 01/04/2023).Lohberger, Falko et al.,  Aug. 2004. “Ground-based imaging differential optical absorption spectroscopy of atmospheric gases”. In: Applied Optics 43.24, p.4711. doi: 10.1364/ao.43.004711. url: https://doi.org/10.1364/ao.43.004711.Manago, Naohiro et al.,  July 2018. “Visualizing spatial distribution of atmospheric nitrogen dioxide by means of hyperspectral imaging”. In: Applied Optics 57.21, p. 5970. doi: 10.1364/ao.57.005970. url: https://doi.org/10.1364/ao.57.005970.
Analysis of resolution-induced differences in soil - hydrology - vegetation interactions in the Arctic using state-of-the-art land surface model
Authors: Schickhoff Meike , de Vrese Philipp , Brovkin Victor
Published: February 2023

Arctic permafrost degradation and carbon decomposition do not occur homogeneously across Arctic ecosystems due to the rich landscape diversity and the high amount of small-scale heterogeneities. Traditionally, Earth system models (ESM) are deployed to investigate future climate change in the northern permafrost areas. The typical heterogeneous landscape characteristics of the Arctic are however in scale well below the usual ESM resolutions of several hundred kilometers. To take in-depth account of small-scale heterogeneous landscapes, a higher land surface model resolution is advantageous.To investigate whether and why resolution matters in simulating the interactions of soil physics, hydrology, and vegetation in the Arctic, we develop a high-resolution version of the land surface model (LSM) JSBACH3 on the scale of 5 km for a case study in the Chersky region in eastern Siberia. We then compare the results with the output of the same model in a low ESM resolution of about 200 km. The LSM simulations are performed in standalone mode (without feedbacks to climate) using the same climate forcing for both, high- and low- resolution setups. Our analysis shows that small-scale soil characteristics are more relevant regarding resolution than vegetation properties. We found that the formulation of supercooled water processes in the soil has a major impact on the differences between low and fine resolutions, as well as soil organic matter fractions. Other soil parameters such as hydraulic conductivity, soil porosity or heat conductivity have relatively minor effects on differences between model resolutions.We show the relevance of model resolution in the simulation of Arctic land physical and biogeochemical interactions and thus argue that the development of a high-resolution pan-Arctic LSM would be a major advancement in modelling future Arctic permafrost and carbon projections.
Decadal Variability of Transports through Barents Sea Opening: Changing impact of Large-Scale Wind Forcing
Authors: Heukamp Finn Ole , Aue Lars , Kanzow Torsten
Published: February 2023

The Barents Sea Opening (BSO) is one of two Atlantic gateways connecting the North Atlantic Ocean to the Arctic Ocean. The ocean transport through the BSO is composed of warm and saline Atlantic Water inflow in the central and southern parts of the section and cold Polar and modified Atlantic Water outflow in the north. The variability of strengths of both inflow and outflow largely controls the evolution of the net ocean heat transport into the Barents Sea, locally impacting e.g., ocean-atmosphere heat fluxes, sea ice extent, and deep-water formation. Moreover, changes in heat fluxes and sea ice extent have been shown to impact remote properties such as wintertime weather in northern Europe and water properties in the central Arctic Ocean.In this study, we identified and disentangled the contributions of local and remote atmospheric forcing mechanisms of the wintertime volume transport through BSO from 1970-2020. In order to understand the variability and co-variability of the local and remote forcing mechanisms and the linked transport anomalies, we performed dedicated model experiments with the unstructured ocean and sea ice model FESOM2. In addition to a hindcast control simulation using JRA55 reanalysis forcing, we performed two additional model experiments in which we combined JRA55 forcing with CORE1 normal year forcing in a way that the simulations are forced with JRA55 (CORE1) in the Arctic domain and CORE1 (JRA55) outside the Arctic domain. This setup allows the separation of local and upstream forced transport variability. Our experiments show, that both BSO inflow and outflow exhibit strong variability on interannual to decadal timescales. While inflow variability is forced to a similar degree by local alongshore winds and alongshore winds upstream in the Norwegian Sea, the outflow variability is almost entirely forced by wind stress curl anomalies over the northern Barents Sea shelf. Moreover, the inflow anomalies forced upstream are highly correlated with the North Atlantic Oscillation (NAO) while the transport anomalies forced locally exclusively correlate with the NAO during periods of a negative NAO. Furthermore, we observe a drastic drop in the correlation of inflow anomalies forced upstream and the NAO around the year 2000 - the same period in which winters with strongly enhanced outflow anomalies (97/98, 03/04) are found. By expanding our analysis to cyclone activity in the northern North Atlantic, we link the loss of co-variability of NAO and BSO inflow to an anomalous southward deflection of cyclones in these winters, affecting the alongshore winds in the Norwegian Sea as well as the wind stress curl over the northern Barents Sea shelf.In general, this study aims to improve our understanding of the drivers of volume and heat transport variability in the BSO as a key factor for (sub-)Arctic, ocean, weather, and climate variability. 