bluuebunny/crossref_metadata_2025 huggingface dataset:
Different types of PCA-NN model for TEC with space weather parameters as predictors: advantages and disadvantages of different NN algorithms
Authors: Morozova Anna , Gafeira Ricardo , Barata Teresa , Barlyaeva Tatiana
Published: February 2023

A PCA-NN model for the total electron content (TEC) for the midlatitudinal region (Iberian Peninsula) presented here uses the principal component analysis (PCA) to decompose TEC variations into different modes and to reconstruct/forecast amplitudes of these modes using neural networks (NN) with different sets of space weather parameters as predictors.Feedforward, convolutional and recurrent NN algorithms are tested with different sets of predictors. The performance of the models is tested on 3.5 years of observational data obtained at the declined phase of the 24th solar cycle, which allows us to estimate the models’ performance in relation to the solar activity level. The advantages and disadvantages of different NN algorithms are discussed.
Long-term evolution of the spectral content of continuous seismo-volcanic signals from a network-based analysis
Authors: Caballero Emmanuel , Shapiro Nikolai , Journeau Cyril , Seydoux Léonard , Soubestre Jean , Barajas Andrés
Published: February 2023

Volcanoes are multi-physics systems where different phenomena interact, such as magma transport, degassing, crystallization, and pressure-induced faulting. These interactions create a series of seismic signals, among which we have volcano-tectonic earthquakes, long-period events, and volcanic tremors. Thanks to these signals, there has been an improvement in the comprehension of volcanic systems. However, due to its complexity, there is still a debate regarding the observed seismic signals, i.e., their precise origin and characteristics. In the past, some techniques, such as spectral analysis and simple earthquake location were used. However, these techniques lack the resolution that we currently need. In this regard, network-based methods have been developed to determine the level of wavefield coherence and to classify different seismicity types from complex continuous signals.In this work, we analyze eight years (from 2011 to 2020) of continuous seismic data of Piton de la Fournaise, la Réunion, France, using a network array including approximately 20 stations. We use a method based on the covariance matrix combining interstation single-component cross-correlations. From the continuous velocity records, we create temporal overlapping windows in which we estimate the covariance matrix in the frequency domain. We then evaluate its rank through the estimation of the width of its eigen-values distribution, in other terms, the number of independent seismic sources. This method allows us to quantitatively measure the presence of coherent sources recorded by the array and to characterize their frequency content.The resulting distributions of the spectral width show that continuous signals are characterized by multiple narrow spectral peaks clearly observed in the co-eruptive tremors but also during periods without visible volcanic activity. To enhance these peaks, we re-normalize the distribution of spectral width in the frequency and time domains. As a result, we observe in the 1-3 Hz frequency band many spectral peaks that remain nearly constant during very long periods (weeks to months). At the same time, we observe a clear difference in the distribution of these frequencies between the co-eruptive and quiet periods and also some significant variations during long-standing eruptions. We suggest that variations of the spectral lines can be related to the properties of seismo-volcanic sources and eventually to the structural changes and, therefore, can be used in volcano monitoring.
Understanding the variability and trend of the regional Hadley Cell over Asia-Pacific
Authors: Baruah Pratiksha Priyam , Joseph Mani Neena
Published: February 2023

The zonal mean Hadley Cell (HC) has been reported to be expanding poleward in the last few decades. However, there has been no consensus on whether the zonal mean HC is strengthening or weakening. The features of longitudinally averaged HC are collectively modulated by various regional HCs, controlled by the regional differences in land-ocean distribution and topography. However, there have not been many studies exploring the variability and trend of regional HCs in a detailed manner. In this study, we examine the variability and long-term trend of the regional HC over the Asia-Pacific and explore the different factors contributing to the regional HC variability. Moist convection can regulate regional HCs on synoptic time scales through equatorial wave dynamics. The ocean–atmosphere coupled variability associated with the El Niño-Southern Oscillation (ENSO), and the modulation of tropical convection and equatorial waves are considered to exert a dominant control on the regional HC variability in the interannual timescale. In addition to the tropical forcing, the regional HC variability is also affected by fluxes transported by the midlatitude eddies from the subtropics to the tropics. In this study, we will be quantifying the relative role of these tropical and extratropical forcings in modulating the variability of regional HC over Asia-Pacific. 
Effects of nitrogen and phosphorus inputs on the diversity of carbon-, nitrogen-, and phosphorus- mineralization microbial communities in subtropical Chinese fir plantations
Authors: Liu Shuang , Zhang Xinyu , Wang Huimin , Pan Junxiao , Tang Yuqian , Chen Fusheng
Published: February 2023

The regulation of N and P input on microbial communities is related to the bottom-up effects of soil resources (i.e., nutrients), and the top-down effects of predators (i.e., protists). However, it is not clear how exogenous N, P, and NP inputs effect on the bottom-up (pH, soil nutrients, and eco-stoichiometry ratio of C: N: P), and top-down (abundance and diversity of protist community) factors to estimate soil microbial community involved in C-, N-, and P- mineralization. In this study, we explored the effects of a 7-years N, P, and NP inputs on the bottom-up and top-down controls on the abundance and diversity of functional microbial communities in the subtropical Chinese fir plantations using metagenomic sequencing. The results showed that N and NP inputs decreased soil pH and soil acidifying cause a reduction in the alpha diversity of microbial function. Exacerbated soil microbial C limitation under N, P, and NP inputs was negatively correlated with the alpha diversity of metagenomic function. The alpha diversity of bacteria was negatively correlated with the ratios of soil total and available N: P, due to increasing available P content. Regarding top-down effects of protists on the abundance and diversity of microbial C-, N-, and P- mineralization community, P and NP inputs increased alpha diversity of protist, thus, selectively increased the relative abundances of Calditrichaeota involved in C-mineralization, and decreased the relative abundances of Elusimicrobia and Marinimicrobia involved in N-mineralization. Although protozoa feed on both bacteria and fungi, changes in protists under N, P, and NP inputs mainly affected bacterial diversity and abundance, with no significant changes in fungi. Overall, the present results provide important knowledge on bottom-up (pH, soil nutrients, and eco-stoichiometry ratio of C: N: P), and top-down (abundance and diversity of protist community) factors of the abundance and diversity of the microbial community involved in C, N and P mineralization in the context of elevated N and P input.
Physical/biogeochemical modelling of the global coast with ICON-coast – the impact of continental runoff
Authors: Logemann Kai , Mathis Moritz , Schrum Corinna
Published: February 2023

ICON-coast is the coastal version of the newly developed global ocean model ICON-O, which is itself part of the ICON (Icosahedral Non-hydrostatic) earth system modelling framework, developed by the Deutscher Wetterdienst and the Max-Planck-Institute for Meteorology. ICON-coast uses an unstructured, triangular computational mesh with a regular bisection-type mesh refinement technique to increase the horizontal resolution along the global coast. The global tides are included and crucial shelf-specific processes are added to the pre-installed biogeochemical sub-model (HAMMOC). Furthermore, an interface to the FABM 1.0 framework was implemented, which enables a coupling with the biogeochemical model ECOSMO. We present first ICON-coast/ECOSMO experiments in order to investigate the impact of the continental runoff and its related eutrophication on the global coastal ecosystem.
Slumping regime in lock-release turbidity currents
Authors: Gadal Cyril , Mercier Matthieu , Lacaze Laurent
Published: February 2023

Most gravitational currents occur on sloping topographies, often in the presence of particles that can settle during the current propagation. Yet, an exhaustive exploration of associated parameters in experimental devices is still lacking. Here, we present an extensive experimental investigation on the slumping regime of turbidity (particle-laden) currents in two lock-release (dam-break) systems with inclined bottoms. We identify 3 regimes controlled by the ratio between settling and current inertia. (i) For negligible settling, the turbidity current morphodynamics correspond to those of saline homogeneous gravity currents, in terms of velocity, slumping (constant-velocity) regime duration and current morphology. (ii) For intermediate settling, the slumping regime duration decreases to become fully controlled by a particle settling characteristic time. (iii) When settling overcomes the current initial inertia, the slumping (constant-velocity) regime is not detected anymore. In the first two regimes, the current velocity increases with the bottom slope, of about 35% between 0° and 15°. Finally, our experiments show that the current propagates during the slumping regime with the same shape in the frame of the moving front. Strikingly, the current head (first 10 centimeters behind the nose) is found to be independent of all experimental parameters covered in the present study. We also quantify water entrainment coefficients E, and compare them with previous literature, hence finding them proportional to the current Reynolds numbers.
Biological effects of munition left on war wrecks on the health of caged blue mussels (Mytilus edulis, L.) in the southern North Sea
Authors: Brenner Matthias , Schuster Romina , Binder Franziska
Published: February 2023

The North Sea was the scene of many naval battles during both World Wars. As a result, military ships, civilian merchants, and cargo vessels sank. Today, the German Maritime Museum in Bremerhaven, Germany, suspects approx. 240 wrecks in Danish, at least 100 in Belgian and about 120 military wrecks including airplanes in the German EEZ and territorial waters. Many of these wrecks were partially or fully loaded with munition at the time of the sinking. However, based on archive information, visible inspections or survey reports only rough estimates about remaining quantities of munition on or in the vicinity of these wrecks can be made. After 75-100 years in the marine environment munition shells are corroding and start leaking chemicals of their explosive cargo into the marine environment. They main component of munition is 2,4,6 trinitrotoluene (TNT). Next to its ability to explode, TNT is also known for its toxicity and for being carcinogenic and mutagenic. In order to test for leaked explosives in the surrounding waters, sediments and biota field studies were conducted on wrecks sites in Belgium, Germany and Denmark. The measured concentration of explosive were subsequently correlated with potential health impairments, using blue mussels (Mytilus edulis) deriving from munition free site. These mussels were exposed for several weeks in steel cages on or near three wrecks sites. In Belgian waters the KW 58 Hendricus a transport vessel loaded with several tons of landmines sunken during WW II was selected for this investigations. In German waters the light cruiser SMS Mainz laying approx. 40sm west of the island of Heligoland was chosen and in Danish waters a German mine laying submarine (UC30) situated a few miles west of Esbjerg was investigated using caged blue mussels. Three to four cages filled with blue mussels were placed at different locations on each of the three wrecks. At the end of the exposure time mussels were retrieved and first examined for mortality, subsequently dissected and analysed in the lab for biomarker responses according to a multi-biomarker approach. First results show very different water concentrations around the wreck sites ranging from low ng/L of dissolved TNT up to the µg/L and mg/L level. Further, also the uptake of TNT by mussels could be proven resulting in measurable biomarker responses of the exposed blue mussels.
On the estimation of potential evaporation under wet and dry conditions
Authors: Tu Zhuoyi , Yang Yuting
Published: February 2023

Potential evaporation (EP) is an important concept that has been extensively used in hydrology, climate, agriculture and many other relevant fields. However, EP estimates using conventional approaches generally do not conform with the underlying idea of EP, since meteorological forcing variables observed under real conditions are not necessarily equivalent to those over a hypothetical surface with an unlimited water supply. Here, we estimate EP using a recently developed ocean surface evaporation model (i.e., the maximum evaporation model) that explicitly acknowledges the inter-dependence between evaporation, surface temperature (Ts) and radiation such that is able to recover radiation and Ts to a hypothetical wet surface. We first test the maximum evaporation model over land by validating its evaporation estimates with evaporation observations under unstressed conditions at 86 flux sites and found an overall good performance. We then apply the maximum evaporation model to the entire terrestrial surfaces under both wet and dry conditions to estimate EP. The mean annual (1979-2019) global land EP from the maximum evaporation model (EP_max) is 1272 mm yr-1, which is 11.2% higher than that estimated using the widely adopted Priestley-Taylor model (EP_PT). The difference between EP_max and EP_PT is negligible in humid regions or under wet conditions but becomes increasingly larger as the surface moisture availability decreases. This difference is primarily caused by increased net radiation (Rn) when restoring the dry surfaces to hypothetical wet surfaces, despite a lower Ts obtained under hypothetical wet conditions in the maximum evaporation model.
Cluster occurrence of extreme rainfall events over Indo-Pacific and their associated diverse Rossby wave patterns
Authors: Song Yurong , Lu Mengqian
Published: February 2023

Clustering extreme rainfall events are successive occurrences over multiple regions. As climate continues to warm up, cluster occurrence is becoming a prevailing feature of extreme weather events and leading to significant socioeconomic impacts. Understanding the associated atmospheric teleconnection patterns and their underlying mechanisms can help quantify their risk, i.e., the probability of occurrence and severity of cluster extremes in the future. In this study, we identified over 400 events of clustering extreme rainfall events over South Asia, East Asia, and North America in the past 42 years. Diagnostic analyses of these events reveal the diversity of teleconnection that paved the road to the events. Three Rossby wave patterns: (1) circum-Pacific Rossby wave, (2) cross-Pacific Rossby wave, and (3) Pacific anticyclone Rossby wave breaking, are the major synoptic-scale dynamics responsible for clustering rainfall events. Specifically, the circum-Pacific Rossby wave dominates in autumn and early winter, while the cross-Pacific Rossby wave pattern prevails during the Indian summer monsoon season. The occurrence frequency of the anticyclone Rossby wave breaking does not show significant seasonal differences.The key driving mechanisms behind these wave patterns are: 1) The poleward propagation of the circum-Pacific wave can be excited by the heating anomaly originating in the tropics. 2) The mid-latitude cross-Pacific Rossby wave is a portion of the circum-global teleconnection pattern. This recurrent Rossby wave connects Asia and North America, influenced by the Indian summer monsoon. 3) Pacific anticyclone Rossby wave breaking is a quasi-stationary synoptic wave pattern causing persistent extreme weather. The frequency of this pattern increases significantly during La Niña years with a relatively weak subtropical jet. The single or synergistic effects of these three patterns cause the cluster occurrence of extreme rainfall. Findings from this work offer a better understanding of rainfall teleconnection and tropic/midlatitude interaction.
Wildfire impacts on water: improving impact assessment though model adaptation
Authors: Basso Marta , Keizer Jacob , Serpa Dalila , Mateus Marcos , Vieira Diana
Published: February 2023

Wildfires are a threat to water security worldwide, due to the negative effect of the post-fire mobilization of sediments and associated nutrients and contaminants on the waterbodies located downstream of burned areas. Such impacts have been assessed in field studies and, more recently, also through modelling approaches. Models are valuable tools for anticipating the potential negative impacts of wildfires, allowing to test different environmental scenarios. The state of the art in post-fire model adaptation has shown that most studies simulate the hydrological and erosion response in the first post-fire year in situ, without considering the cascading effects on downstream waterbodies. In addition, few studies have evaluated the long-term impacts of wildfires, likely due to the limited available data. Among the existing gaps in post-fire modelling, ash transport has recently been identified as a priority. The lack of ash modelling studies has been ascribed to the limited understanding of ash behavior and the difficulties of incorporating ash-related processes into the structure of existing models.As a way to fulfill these research gaps and advance the state of the art in post-fire hydrological modeling, the authors provided several contributions in recent years.For instance, a watershed model has been coupled with a reservoir model to simulate the effects of fires on drinking water supplies, using the outputs of the main streams as inputs to the reservoir branches. As most simulations commonly end at the watershed outlet, a simple methodology was proposed to assess how the impacts on watercourses propagate to the drinking water supply inlet. The results showed that integrated modeling frameworks are critical for anticipating the off-site impacts of fires.Post-fire management can also influence the impacts of fires beyond the first post-fire rainfall events, when the soil is exposed and ash and sediment transport is greatest. Another modelling exercise evaluates the long-term impacts of different post-fire management options, more specifically terracing, mulching and natural recovery, on water availability and quality.As post-fire ash and sediment mobilization is typically limited to the duration of the rainfall events, which typically lasts for a few hours, hydrological models that run at a daily time-step can underestimate the environmental impacts of fires. To improve the knowledge of post-fire hydrological processes at event-based scale, two hydrological models (LISEM and MOHID) were calibrated, accounting for burn severity and initial soil moisture conditions before each specific rainfall event.The work done in the past years is expected to be of added value for the post-fire modeling community, providing future directions on post-fire hydrological modelling studies. 
Geology, geochemical typification and petrogenic model of formation of Middle Paleozoic metabasites of the Khrami crystalline massif (Georgia)
Authors: Shengelia David , Tsutsunava Tamara , Beridze Giorgi , Javakhishvili Irakli
Published: February 2023

The Khrami crystalline massif is located in the northern part of the Lesser Caucasus, in the Black Sea - Transcaucasian terrane. The massif outcrops Middle Paleozoic metabasites, which crosscut the Precambrian gneiss-migmatite complex and, in turn, are cut by Late Variscan granites. These metabasites have not experienced Precambrian prograde HT/LP (720-770°C, P<1.5 kbar) regional metamorphism, although retrograde LT/LP (T≈430-5100C, P≈0.6-1 kbar) metamorphism, associated with the Sudetian orogeny has been recorded. According to the presented geological data, the age of metabasites is within the Cambrian and Upper Paleozoic. Considering the analogy between the metabasites spread in the Dzirula crystalline massif, which is exposed in the same terrane, and the metabasites of the Khrami massif, the age of the latter is most likely Middle Paleozoic (Shengelia et al., 2022). The metabasites of the Khrami massif are represented by veins (1-60 m) and stock-shaped bodies (80-800 m) of fine-grained ophitic gabbro, gabbro-diabases and diabases of various thicknesses. They are cut by numerous granite veins and penetrated by thin quartz-feldspar injections. The paragenesis of the high-temperature magmatic stage - Cpx+Pl78-84 has been preserved in metabasites in some places; Further, under the conditions of greenschist facies, the paragenesis Ab+Act(Tr)+Chl+Ep±Qz develops. According to the petrogenic diagrams Na2O+K2O – SiO2, the metabasites of the Khrami massif belong to the formations of the subalkaline series (Irvine and Baragar, 1971), correspond to basalts and andesite-basalts (Le bas et al., 1986) and basalts and picrites (Cox et al., 1979). This is confirmed by the data of diagrams Zr/Ti-Nb/Y (Pearce, 1996) and Zr/TiO2 – Yb/Y (Winchester, Floyd, 1977). According to the Na2O+K2O–FeO*-MgO (Irvine and Baragar, 1971), a great part of the metabasites is of tholeiitic composition, and only a small part is of calc-alkaline composition. On the diagram Fe*-SiO2 (Frost et al., 2008) the dots denoting metabasites are completely disposed in the magnesian field. According to the TiO2 - Zr/(P2O5*104) diagram (Winchester, Floyd, 1976), the metabasites correspond to tholeiite basalts. According to the diagram V-Ti/1000 (Shervias, 1982), the metabasites belong to the MORB genetic formation, and according to the diagram Cr-Y (Pearce, 1982), they belong mainly to the VAB, and also to the MORB. According to the ratio MnO-TiO2/10-P2O5 (Mullen, 1983), dots of mafic rocks are located in the island-arc tholeiitic field. Thus, the Middle Paleozoic metabasites of the Khrami crystalline massif are represented by shallow subvolcanic magmatites predominantly of andesite-basalt and tholeiite-basalt groups of the tholeiitic series. They correspond to the MORB and VAB genetic groups.
Next generation of European forest disturbance maps based on the Landsat archive
Authors: Viana Soto Alba , Senf Cornelius
Published: February 2023

Forest canopy disturbances such as caused by bark beetle, fire, windthrow or harvest have increased in the past three decades and are expected to increase further in response to climate and land use change. Consistent information on forest canopy disturbances is therefore essential to understanding changes in forest dynamics, structure and demography over time and space. As part of the ForestPaths Horizon project we aim to create the next generation forest disturbance maps, extending both the time frame and context of existing pan-European forest disturbance assessments. Disturbances are mapped using the Landsat archive at 30 meters resolution for 1984-2021. A new machine-learning based approach trained on manually labelled reference pixels is applied to the time series, estimating forest disturbances annually and accounting for stand-replacing and non-stand replacing disturbances, as well as different causal agents (i.e., bark beetle, fire, windthrow or harvest). Summarising annual disturbance maps over time ultimately allows to detect multiple disturbance events and recovery signals per pixel and thus for the characterization of complex disturbance trajectories (e.g., multiple fires, thinnings before final harvest). We test our approach at national levels for three countries accounting for three forest biomes: boreal (Finland), temperate (Germany) and Mediterranean (Spain); covering a total land area of 1,194,526 km2 and a total of 65,623 Landsat images. The results from those initial tests will provide information on the accuracy and precision of the annual, wall-to-wall maps of forest disturbances and pave the road for a consistent disturbance monitoring system of all of Europe’s forests.
Plant lipids as proxies to trace the origin and dynamics of soil organic carbon
Authors: Jansen Boris
Published: February 2023

Lipids from the wax layers of plant leaves and plant roots as preserved in soils and sediments have been used for decades as proxies for environmental reconstructions. In particular the n-alkanes of higher chain-lengths (ca. C25-C37) are used to this end. The past decade has seen an increased research attention for the use of plant lipids as molecular proxies. This includes an emerging interest in applications aimed at unravelling the dynamics of soil organic matter (SOM) rather than answering purely palaeo-ecological questions[1] as well as in reconstructing multiple environmental factors at once. Here I highlight these developments via two examples of recent work by our group. In the first example we applied analysis of n-alkanes and n-alcohols preserved in plaggic Anthrosols to reconstruct the origin of the plant material that was used as the stable fillings that were applied to fertilize the soils in this unique agricultural system. In the second example we examined plant derived n-alkanes preserved in soils along an altitudinal transect in the Ecuadorian Andes as part of a coupled reconstruction of palaeo-vegetation and palaeo-climate. I discuss both the exciting new insights gained as well as the challenges that still remain.References[1] J.M. van Mourik, T.V., Wagner, J.G. de Boer, B. Jansen, (2016). The added value of biomarker analysis to the genesis of plaggic Anthrosols; the identification of stable fillings used for the production of plaggic manure. SOIL, 2, 299-310[2] B. Jansen, H. Hooghiemstra, S.P.C. de Goede, J.M. van Mourik, (2019). Chapter 5 - Biomarker analysis of soil archives, Eds. J.M. van Mourik, J.J.M. Van der Meer, Developments in Quaternary Sciences, 18: 163-222[3] M.L. Teunissen van Manen, B. Jansen, F. Cuesta, S. León-Yánez, S., W.D. Gosling, (2020). From leaf to soil: n-alkane signal preservation, despite degradation along an environmental gradient in the tropical Andes. Biogeosciences, 17, 5465-5487
Estimating the Oceanic Kinetic Energy Cascade from Satellite Along-Track Altimetry
Authors: Schubert René , Gula Jonathan
Published: February 2023

The transfer of kinetic energy between currents of different horizontal scales shapes the structure of the global ocean circulation and associated heat, salt, nutrient, and oxygen fluxes, as well as atmosphere-ocean interactions. In particular the geostrophically balanced part of the flow has been shown to be associated with a net inverse cascade from currents of smaller scales to currents of larger scales. Here, we show with a submesoscale-permitting simulation of the Atlantic that the respective scale kinetic energy flux averaged over 5º x 5º boxes is linearly related to the product of quantities that are computable from along-track altimetry when they are averaged over the same region. This linear relationship is applied to JASON-3 along-track sea-surface height data to estimate for the first time the geostrophic kinetic energy cascade at scales between 60 and 200 km, as well as its regional distribution and seasonal cycle for large parts of the global ocean on the basis of observations. The results are consistent with previous findings based on regional observations, simulations, and indirect comparisons of spectral properties of satellite data.
Distinct Responses of Marine Phytoplanktons to the Asteroid Impact and Volcanism at the Cretaceous-Paleogene Boundary (K-Pg)
Authors: Chen Yihui , Zhang Jian , Liu Yonggang , Hu Yongyun
Published: February 2023

One of the prominent features of the Cretaceous/Paleocene (K-Pg) mass extinction is the highly selective extinction of marine phytoplankton. It is generally thought that the disturbances in the marine biogeochemical processes were caused by the asteroid impact in the Yucatan and/or the Deccan volcanism. However, which one is dominant remains debated. Here, we use Community Earth System Model (CESM1.2.2) to explore their influences on the latest Cretaceous marine biosphere. It is found that the asteroid impact led to a decrease by ~32% in the calcareous algae but an increase of ~95% in the diatom, consistent with the divergent trends of the abundance of calcium carbonate and biogenic silica archived in marine sediments. The rapid decline of the calcareous algae was because of lowered temperature and decreased light due to the asteroid impact, whereas the increase of diatoms was induced by the input of impact-generated debris and enhanced vertical mixing of the surface ocean, both of which increased nutrient supply. The counteraction between calcareous algae and diatom, to some extent, ensured the resilience of the bulk ocean biogeochemical cycle to the asteroid impact in the latest Cretaceous, with the total biomass increasing by ~2.7%. In comparison, the long-term forcing  (CO2-induced warming) due to Deccan volcanism reduced 10-20% of all types of phytoplanktons. The trend and magnitude of this change are significantly different from that triggered by the asteroid impact, suggesting that asteroid impact was more likely the primary driver of the selective phytoplankton extinction at the K-Pg boundary.
Implicit cost of carbon emissions: Design the internal carbon price in the decision-making process
Authors: Wu Hsin-hua , Tung Ching-pin
Published: February 2023

In the debate on carbon reduction, carbon pricing has become the norm to motivate the actors to work on the issue through economic incentives. Given that more and more relevant policies such as emission allowances or taxes are being released recently and might have a direct impact on operating costs, it is far more essential for companies to identify the implicit cost of emissions.Internal Carbon Pricing is one of the strategies increasingly used by companies to support the decision-making process to deal with the risk associated with the additional cost of emissions, which helps drive environmental efficiency, change internal behavior, and navigate greenhouse gas regulations across departments. However, there remains a lack of an appropriate approach to accurately express the implicit cost of emissions, which makes it difficult for companies to devise the internal pricing level. In addition, the collection of the pricing policy largely depends on the level of energy consumption of each department, which casts doubt on the representativeness of environmental efficiency.This study proposes an analysis of implicit carbon pricing based on the concept of the marginal cost of emissions, which includes the additional investment needed in emissions-reducing or -removing projects and the incremental cost that come from relevant regulations that might increase with the emission level. The work calculates the marginal cost of emissions by using linear programming; economic performance serves as an objective function and the mitigation target of the company as well as the available resources constitute the constraints. Moreover, to estimate the environmental efficiency, the study introduces Data Envelopment Analysis (DEA) to measure the relative efficiency between departments and derive an efficiency score as a marginal cost adjustment factor in designing the internal pricing level.By the calculation of the marginal cost of emissions, which is still under discussion at present, this study develops a strategy to assist companies in accurately establishing internal pricing levels, thus ensuring the effectiveness of the internal carbon pricing policy that is in line with the company's mitigation target.
Understanding Energy Pathways in the Gulf Stream
Authors: Contreras Marcela , Renault Lionel , Marchesiello Patrick
Published: February 2023

The Gulf Stream (GS) is one of the strongest ocean currents on the planet. Eddy-rich resolution models are needed to properly represent the dynamics of the GS, however kinetic energy (KE) can be in excess in these models if not dissipated efficiently. The question of how and how much energy is dissipated and in particular how it flows through ocean scales thus remains an important and largely unanswered question. Using a high-resolution (2 km) ocean model (CROCO), we characterize the spatial and temporal distribution of turbulent cascades in the GS based on a coarse-grained method. We show that the balanced flow is associated with an inverse cascade while the forward cascade is explained by interactions between unbalanced and balanced motions. The forward cascade, which represents an interior route to dissipation, is compared to both numerical and boundary dissipation processes. The contribution of interior dissipation is an order of magnitude smaller than that of the other energy sinks.
Turbulence properties inside and outside trade-wind cumulus clouds
Authors: Nowak Jakub , Wacławczyk Marta , Malinowski Szymon
Published: February 2023

Shallow trade-wind cumulus clouds originate from thermals which rise from the turbulent subcloud layer and penetrate high enough to reach their lifting condensation level. Those thermals transport heat and moisture into the cloud layer. Analogously, the subject of such a transport can be the small-scale turbulence.Turbulence measurements near the cloud base and in the subcloud layer were performed in the course of the EUREC4A field campaign by the ATR research aircraft in a large number of repeatable flight segments (Brilouet et al., 2021). In this study, we exploit this extensive dataset to derive properties of turbulence corresponding to short 'local' domains, of the size of the order of 100 m, e.g. turbulence kinetic energy dissipation rate, anisotropy and inertial range scaling. Taking advantage of the substantial amount of data provided by the EUREC4A measurements, we compare the statistics of those parameters between the areas inside cumulus clouds, outside them at the same altitude and at three levels inside the subcloud layer.Such a comparison indicates that the character of small-scale turbulence inside cumulus clouds can be considered comparable to the one observed in the subcloud layer but significantly differs from that observed at the same level outside the clouds. As the cloud fraction at cloud base is typically rather a small number (about 4% during EUREC4A), it is in consequence inherently difficult for large scale models to accurately parameterize the intensity of turbulence and mixing in the trade-wind regime.
A novel approach for assessing regionally differentiated ocean contributions to Earth Energy Imbalance from GRACE(-FO) and multi-mission altimetry
Authors: Uebbing Bernd , Vielberg Kristin , Aschenneller Bene , Rietbroek Roelof , Köhl Armin , Kusche Jürgen
Published: February 2023

Earth Energy Imbalance (EEI) results from a net positive radiative flux at the top of atmosphere. Over 90% of this excess energy is stored as heat in the ocean causing present day ocean heat content (OHC) change. This in turn leads to volumetric or steric expansion of the water column and sea level rise. Utilizing observed bias-corrected short- and long-wave energy fluxes from the CERES project, it is possible to estimate EEI at the top of atmosphere. However, bias corrections rely on reanalysis OHC, potentially resulting in overestimation of ocean heat uptake (OHU).Combining GRACE(-FO) and altimetry observations and constructing global sea level budgets allows to derive (thermo-)steric sea level change and convert this to OHU; the latter is generally achieved considering a literatute-based ocean-mean expansion efficiency of 0.52 [W/m^2 / mm/yr]. Nonetheless, this approach is valid for global mean steric sea level change only and it is unclear to what extent one can use it for investigating regional OHU.Here, we develop a novel approach for deriving global and regional observation based OHC and OHU, which consists of three steps. (1) Fitting mass and steric spatial patterns, so called fingerprints, to GRACE(-FO) and altimetry data in a joint least-squares inversion. (2) Projecting reanalysis OHC onto the same spatial patterns that we use to explain steric variability. (3) Rescaling reanalysis OHC based on the observed steric sea level changes and reconstruction of spatial maps of OHC. These can then be further analyzed in order to derive global and regional OHU.Based on preliminary results for years 2005-01 till 2015-12, we find ~1.2 mm/yr (thermo-)steric sea level change. Global-mean OHU of 0.62 [W/m^2] can be derived from the literature expansion efficiency above, while we find 0.63 [W/m^2] from the novel rescaling approach and 0.87 [W/m^2] based on ORAS5 ocean model data only. Regionally analyzing these results regarding individual ocean contributions reveals that the ocean model seems to significantly overestimate the uptake of the Atlantic and Pacific oceans, while slightly underestimating the Indian ocean contribution.
A probabilistic assessment of induced seismicity and fluid flow in the Carboniferous Limestone of northwest England: Implications for geothermal energy
Authors: Healy David , Hollis Cathy
Published: February 2023

Faults slip in response to changes in stress or fluid pressure, and these changes can be natural or anthropogenic. Estimating the likelihood of fault slip for a given change in loading is critical for safe geological storage and energy extraction in faulted rocks, as well as effective communication of risks to policy makers and the public. The energy transition and decarbonization are urgent and essential tasks: we will only be successful if we manage to balance public perceptions of risk with the technical challenges inherent to the exploitation of faulted rock. To accomplish both, we need to do a better job of quantifying the uncertainties in our mechanical and geometrical data. Measures of fault stability include slip (Ts) and dilation (Td) tendency, and fracture susceptibility (Sf, the change in fluid pressure to push effective stress to failure). The input values for any of these measures are always uncertain, and they are uncertain to varying degrees. For example, while the vertical stress can be well constrained from wireline density log data, the maximum horizontal stress is generally much harder to quantify from any source.Probabilistic models of fault stability for the Mississippian (Lower Carboniferous) Limestone underlying much of northern England are presented. This is an undrilled target for geothermal energy. Fault maps are derived from published geological maps and recently reprocessed seismic reflection data. Stress and pressure constraints are derived from legacy onshore hydrocarbon wells and wireline logs. Coefficients of friction and cohesive strength remain poorly constrained, not only in terms of their magnitude, but critically in the shapes of their statistical distributions. In addition, the applicability of simplified indices of fault stability (Ts, Td, Sf) to complex natural fault zones is questionable, and our predictions could be improved through weighting by information derived from long-term seismological records.  This contribution raises two key points: 1) Laboratory data rarely include repeat measurements from quasi-identical samples of the same rock, and therefore the statistical distributions of friction or cohesion are poorly known. This is important because skewed distributions – and the direction of that skewness (high or low) – can significantly affect predictions of fault stability; 2) What is the best way to weight the calculated probability of slip in complex natural fault zones to account for geometrical weakening? Specifically, is total fault length more or less important than fault smoothness (roughness)?
Sustainable management of agricultural soils: Balancing multiple perspectives and tradeoffs
Authors: Garland Gina
Published: February 2023

As the global population expands, the demand for food, fuel and fiber rises steadily. Meeting these needs in a sustainable manner, without depleting natural resources or polluting the environment remains one of the greatest challenges of our time. What is more, anticipating changes in these systems as a result of climate change, and across a multitude of environmental and socioeconomic contexts adds yet even further complexity to this already convoluted issue. At the heart of this matter lies agricultural soils, and how management practices are used to modify and adapt their capacity to sequester carbon and provide nutrients and water to growing plants. While soils are notoriously heterogenous on their own, this is further enhanced by their role as an important environmental reservoir linking plants and residues to soil microbial communities and soil fauna, the atmosphere, and water. Understanding how management practices influence these interactive aspects of the soil environment is key to developing agricultural management systems in a sustainable, effective and site-specific manner.In this presentation I will highlight how it is vital for future studies to consider a) how management practices will simultaneously impact a variety of different soil functions or services, not just one or two, in order to assess environmental tradeoffs within a given system, b) how these are impacted across different spatial scales, and c) the importance of developing management practices that are adapted to local, site-specific conditions. It is clear that the complexity of modifying agricultural systems to survive in a rapidly changing climate demands interdisciplinary approaches. It is thus my hope that this presentation will foster open discussion and meaningful collaborations to address such challenging societal questions.
The Cenozoic sea surface temperature evolution offshore Tasmania
Authors: Bijl Peter , Hoem Frida , Hou Suning , Thöle Lena , Sauermilch Isabel , sangiorgi Francesca
Published: February 2023

During the Cenozoic (66–0 Ma) Tasmania has continuously been at a crucial geographic location. It represented the final tectonic connection between Australia and Antarctica before complete separation of both continents in the late Eocene, and therefore a barrier for circumpolar flow. Since the Eocene-Oligocene transition, the northward drifting Tasmania was bathed by the throughflow of the subtropical front, but remained an obstacle of the ideal flow path of strengthening ocean currents. The sedimentary record around Tasmania thus represents a perfect archive to record the oceanographic consequences of this regional tectonic change. We here present a new TEX86 and UK’37-based SST compilation from 4 sediment cores: ODP Site 1172 (East Tasman Plateau), Site 1170 and 1171 (South Tasman Rise) and Site 1168 (western Tasman margin). We paired these reconstructions with microplankton (dinoflagellate cyst) assemblage data which reflect qualitatively the surface water conditions: nutrients, temperature, salinity. Together, the >1.300 samples portray the SST evolution around the island, from the time it was still connected to the Antarctic continent in the Paleocene to its near-subtropical location today. Trends in the SST compilation broadly follow those in benthic foraminiferal stable isotope compilations, but with some interesting deviations. Differences in SSTs on either side of the Tasmanian Gateway are small in the early Paleogene (66–34 Ma), even when the Tasmanian Gateway is considered closed. Widening of the Tasmanian Gateway around the Eocene-Oligocene transition (34Ma) immediately allows throughflow of what later becomes the Leeuwin Current, which warms the sw Pacific. Oligocene and Neogene SST trends follow those of the benthic d18O, and with continuous influence of the proto-subtropical front. While the SST evolution of Tasmania is remarkably stable in most of the Oligocene, prominent cooling steps are inferred in the Late Oligocene (26 Ma), at the MMCT (~14 Ma), in the mid-to-late Miocene (9 Ma, 7 Ma and 5.3 Ma) and in the Pliocene (2.8 Ma). The remarkably strong Neogene cooling of the subtropical front implies expansion of subpolar temperate conditions and probably gradual strengthening of the Antarctic circumpolar current. Pliocene-Pleistocene SST variability is strong over glacial-interglacial cycles. Taken together, the sites portray a complete overview of local environmental change of the subtropical front area, and provides crucial context to the history of Southern Ocean heat transport and regional climate.
Phase field modelling of glacial crevasses subject to meltwater-driven hydro-fracture
Authors: Clayton Theo , Duddu Ravindra , Siegert Martin , Martinez-Pañeda Emilio
Published: February 2023

Surface crevasses are predominately mode I fractures that penetrate tens of metres deep into grounded glaciers and floating ice shelves. However, elevated surrounding temperatures have resulted in the production of surface meltwater, which accumulates in neighbouring crevasses and applies additional tensile stresses to crack walls. This process is known as hydrofracture; and if sufficient, can promote full thickness crevasse propagation, and lead to iceberg calving events. Net ablation of ice sheets has become of great concern, as it has become the largest contributor to sea-level rise. To overcome the limitations of empirical and analytical approaches to crevasse predictions, we here propose a thermo-dynamically consistent phase field damage model to simulate damage growth in both ice sheets and floating ice shelves using the finite element method.The model incorporates the three elements needed to mechanistically simulate hydrofracture of surface and basal crevasses: (i) a constitutive description of glacier flow, incorporating the non-linear viscous rheology of ice using Glen’s flow law, (ii) a phase field formulation capable of capturing cracking phenomena of arbitrary complexity, such as 3D crevasse interaction, and (iii) a poro-damage mechanics representation to account for the role of meltwater pressure on crevasse growth. To assess the suitability of the method, we simulated the propagation of surface and basal crevasses within grounded glaciers and floating ice shelves and compared the predicted crevasse depths with analytical methods such as linear elastic fracture mechanics and the Nye zero stressmethod, with results showing good agreement for idealised conditions.ReferencesT. Clayton, R. Duddu, M. Siegert, E. Martínez-Pañeda, A stress-based poro-damage phase fieldmodel for hydrofracturing of creeping glaciers and ice shelves, Engineering Fracture Mechanics272 (2022) 108693 