bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of root exclusion on the soil microbial community response to warming
Authors: Le Noir de Carlan Coline , de Tender Caroline , Metze Dennis , Bhattarai Biplabi , Pesqueda Argus , Sigurdsson Bjarni , Penuelas Josep , Richter Andreas , Janssens Ivan , Verbruggen Erik
Published: February 2023

World temperature has been steadily increasing over the past century, resulting in alterations of most ecosystems. Particularly, high latitudes regions are expected to undergo severe climate changes. Soil microbes are key actors of the terrestrial system, fulfilling major functions such as nutrient cycling and therefore considerable efforts are made to understand their response to warming. Besides, they can be in tight interaction with roots, and the effect of such interactions are well documented, however, whether soil microbial community response to warming is mediated by plants through roots remains unclear.Here, we took advantage of a geothermal temperature gradient (reaching a warming intensity of up to +6°C) located in two Subarctic grasslands to study the effect of middle (12 years) and long term (>60 years) warming on the root associated soil microbes. For this, we installed two differently mesh sized cores along the thermal gradient of both grasslands allowing us to compare portions of local soil either containing (1 mm mesh size) or excluding roots (30 µm mesh size).We investigated the response of fungal and bacterial communities to warming under both root inclusion and exclusion over the seasons using a metabarcoding approach targeting the 16S rRNA gene and the ITS1 fungal region. We found that warming shifted both bacterial and fungal communities, and that this response was depending on the warming duration. However, root exclusion did not alter the overall microbial community. Surprisingly, we did not find an effect of season on the fungal community while it had a slight effect on bacteria. In addition, we found that Carbon and Nitrogen content were altered differently by warming when roots were excluded.Overall, this study shows that, despite modifying soil conditions, root exclusion had low effect on the general soil fungal and bacterial communities response to warming.
Underwater Scuba Photogrammetry VS. MBES Acoustic Sounding: how to integrate multiscale data for a better understanding of Coralligenous outcrops
Authors: Varzi Andrea Giulia , Fallati Luca , Savini Alessandra , Bazzicalupo Pietro , Bracchi Valentina Alice , Basso Daniela
Published: February 2023

Coralligenous (C) includes calcareous build-ups of biogenic origin, characterised by the association of calcareous algae and several invertebrates. This habitat is one of the most important at the Mediterranean scale; it is a hot-spot of biodiversity thriving from shallow waters down to the limit of the mesophotic zone. The Italian project “CRESCIBLUREEF - Grown in the blue: new technologies for the knowledge and conservation of the Mediterranean reefs” aims at studying  peculiar C outcrops found along a depth gradient offshore Marzamemi village (SE Sicily). During the first project expedition (June 2021), we performed a Multibeam Echosounder (MBES) survey of the target area by using a R2Sonic 2022 system. A new 17 km2 high-resolution morpho-bathymetric map was realised, which interpretation led to the identification and classification of five major habitats, including different C morphotypes. C habitat in the form of banks was found mainly distributed between 30 and 35 m of water depth (w.d.). This investigation allowed us to observe and quantify the overall C distribution along a depth gradient spanning between 20 and 100 m of w.d., giving us a broad-scale perspective of its extension at the seafloor. A third marine survey (September 2021) was focused on collecting video and still images by using a Sony α Alpha 7ii reflex coupled with the Easydive Leo3 Wi housing and the Easydive illumination system Smart Sea - Gold Plus 7000 Lumen, through scuba diving. Data collection was performed over selected areas suitable for the application of underwater photogrammetry, taking into account the presence of C build-ups  (as confirmed by the interpretation of the MBES dataset) and the operational depth (i.e.: no more than 35 m of w.d.). Data collected by adopting this technique and processed using Structure-from-Motion (SfM) algorithms allowed us to get more information at the community level of such complex habitats, coupling the seafloor scale with the smaller scale obtained by direct observations. In this work, our intention is to improve the understanding of the geospatial context of Coralligenous distribution and extent from a multiscale perspective. Specifically, we want to show how eco-geomorphological indexes calculated using the high-resolution outputs of the C photogrammetry (3D meshes, DTMs, and orthomosaics) may be used to perform resolute investigations of such habitat on a broader scale, by considering their spatial distribution extrapolated from the MBES data.
Have roofs in Berlin become greener? Evaluation of Berlin's green roof subsidy program performance using geodata and deep learning
Authors: Chen Siling , Huth Margaux Antonia , Cominola Andrea
Published: February 2023

Green roofs are one of the most widely applied blue-green infrastructure in urban regions to serve several purposes moving towards climate change mitigation and urban adaptation. Their large-scale adoption is critical in enhancing resilience against urban hazards, such as urban flooding, urban heat island effects, and biodiversity loss. Currently, the most popular policy format to encourage their roll-out is subsidy programs. However, the success of such programs is oftentimes evaluated based on siloed governmental data, local evaluation reports, and non-recurrent monitoring campaigns, which may become inconsistent and incomparable across temporal scales and different geographical regions. Due to the lack of open data, complementary metadata, and standard quantitative evaluation tools, monitoring and consistently comparing the effectiveness of different green roof incentivization policies is a challenge in practice. This lack of data and high cost of frequent large-scale monitoring campaigns also hinders city-wide spatial distribution analysis of green roofs and identification of green roof development potential, which could support policymakers in devising effective and sustainable urban management strategies.Moving towards an automated frequent monitoring of green roof development, previous work by Wu and Biljecki developed “Roofpedia”, an open-source deep learning algorithm for green roof mapping and urban sustainability evaluation using satellite imagery. In this work, we validate Roofpedia and evaluate its accuracy in automatically identifying and classifying green roofs from satellite images with public ground truth data in Berlin, Germany. Furthermore, we develop a Berlin-based case study where Roofpedia is applied using geospatial data across temporal scales to assess the efficacy of Berlin’s green roofing subsidy program "GründachPLUS", which has provided 2.7 Million Euros of funding for green roof construction since 2019. We first retrieve open-access orthoimagery data, then extract green roof coverages in Berlin across two temporal steps (i.e., before and after subsidy program instigation), and finally evaluate how effectively and promptly the subsidy program fostered the development of green roofs. This study contributes a Machine Learning-based add-on to the current evaluation protocol of the Berlin municipality, which is implemented via threshold-based spectral analysis. We analyze the spatial distribution of green roofs and provide insights into further green roof potentials in the city of Berlin, by identifying interesting hotspots for future green roof development. Upon imagery availability, this automated assessment may be extended to multiple cities to enable comparative studies of various green roofing incentivization policies and offer a transferrable and scalable policy evaluation framework.
How are radiotracers shaping the research in submarine groundwater discharge?
Authors: Diego-Feliu Marc , Rodellas Valentí , Alorda-Kleinglass Aaron , Rodriguez-Puig Júlia , Alorda-Montiel Irene , Folch Albert
Published: February 2023

The use of radiotracer techniques has been a fundamental tool for characterizing fluxes of solutes and water flows into the coastal ocean driven by submarine groundwater discharge (SGD). Indeed, the scientific interest in the use of radionuclides as tracers of SGD started developing in the late 90s when high activities of Ra isotopes and 222Rn in the coastal ocean were associated with groundwater inputs. Since then, the number of articles published about SGD has considerably grown and the technical improvements in radiotracer methods have often been accompanied by concurrent scientific advances in the understanding of the process. Although current research in SGD is conducted through multiple techniques (direct measurements, hydrological, geophysical, and geochemical techniques), the use of tracers such as Ra isotopes and 222Rn continues to be the most used and widespread method. Therefore SGD estimates are likely to be highly dependent on the methodological biases associated with radiotracer techniques. The aim of this study is to evaluate the main biases and assumptions relative to the use of Ra isotopes and 222Rn in SGD studies through a meta-analysis of the published academic literature. The results of this work highlight that a significant number of SGD studies using radionuclides as tracers are based on erroneous assumptions or inaccurate calculations leading to unreliable SGD quantifications, thus preventing its use for comparison with other studies or extrapolating from local to regional-global scale. These results also emphasize that the SGD community should seek comparison, reproducibility, and multiapproach studies that help to understand the complexity of SGD in multiple sites and bridge the gap between different quantification methods.
Machine-learning algorithm for 24h Detection of Fog and Low Stratus over Europe based on MSG-SEVIRI infrared bands
Authors: Jahani Babak , Karalus Steffen , Zech Tobias , Fuchs Julia , Cermak Jan , Zara Marina
Published: February 2023

In this communication we present a pixel-based algorithm for detection of fog and low stratus (FLS) during the 24H day cycle over land and across Europe, based on geostationary satellite observations.Fog and low Stratus are both a persistent aggregation of water particles in liquid and/or solid phases (cloud) close to the Earth surface. As the cloud-base-altitude is the only real difference between the two (fog: touching the ground; low stratus: above ground), they are frequently treated together as a single category from satellite perspective (FLS). This study presents a pixel-based method for detection of FLS over land across Europe based on Meteosat-11 SEVIRI (Spinning Enhanced Visible and InfraRed Imager) infrared observations. The method is based on a gradient boosting machine learning model that is trained with the observations from Meteorological Aviation Routine Weather Reports (METAR) and German Weather Service (DWD) stations. An intensive validation of the product over 356 METAR stations across Europe over five years of daytime winter data revealed that the method proposed is well capable of detecting FLS over land.  Specifically, the algorithm is found to detect FLS with probabilities of detection (POD) ranging from 0.83 to 0.88 (for different inter-comparison approaches), and false alarm ratios (FAR) between 0.34 and 0.36. As the algorithm operates based on the SEVIRI infrared observations only, it can be applied over day and night, making it feasible to continuously monitor the FLS status over large areas over the 24H day cycle.
Effects of strain- vs. strain-rate-dependent faults weakening for continental corner collision: insight from 3D thermomechanical models
Authors: van Agtmaal Luuk , Balazs Attila , May Dave , Gerya Taras
Published: February 2023

Geological and geophysical observations have highlighted the multi-stage deformation history of the continental lithosphere. Such inherited heterogeneities, observed from microscopic to kilometre-scales, lead to important mechanical weakening for the subsequent development of orogens. This strain-weakening may be frictional (fault gauge, filled veins), ductile (banding, recrystallisation, etc) or caused by changes in grain-size, and largely determines the response of the lithosphere to stresses (Bercovici & Ricard, 2014). Representing the microstructural weakening mechanisms with the relatively low resolution of regional and global numerical modelling studies has been a longstanding challenge. Mechanisms are often grouped into an “effective” plastic strain weakening implementation, where the frictional strength decreases with increasing accumulated strain. Alternatively, materials can be modelled to weaken depending on the local strain-rate (Ruh et al., 2014), which is characteristic for e.g. coseismic frictional weakening of faults. Here we show key differences of strain- vs. strain-rate-dependent faults weakening in terms of orogenic strain propagation patterns in numerical models of a corner collision setting, based on the eastern corner of the India-Eurasia collision. The numerical model I3ELVIS (Gerya & Yuen, 2007) consists of a finite-difference, marker-in-cell method coupled to a diffusion-advection-based finite-difference surface process model, FDSPM (Munch et al., 2022). We highlight key differences between the results of a model with strain-rate-dependent weakening, and a model with conventional strain-dependent weakening based on accumulated strain. The former shows significantly sharper shear zones, as well as a higher number of thrust faults that are relatively evenly spaced, which is more realistic in natural collision zones.  Gerya, T. V., & Yuen, D. A. (2007). Robust characteristics method for modelling multiphase visco-elasto-plastic thermo-mechanical problems. Physics of the Earth and Planetary Interiors, 163(1), 83–105. https://doi.org/10.1016/j.pepi.2007.04.015Bercovici, D., & Ricard, Y. (2014). Plate tectonics, damage and inheritance. Nature, 508(7497), 513–516. https://doi.org/10.1038/nature13072Ruh, J. B., Gerya, T., & Burg, J.-P. (2014). 3D effects of strain vs. Velocity weakening on deformation patterns in accretionary wedges. Tectonophysics, 615–616, 122–141. https://doi.org/10.1016/j.tecto.2014.01.003Munch, J., Ueda, K., Schnydrig, S., May, D. A., & Gerya, T. V. (2022). Contrasting influence of sediments vs surface processes on retreating subduction zones dynamics. Tectonophysics, 836, 229410. https://doi.org/10.1016/j.tecto.2022.229410 
Cloudy with a chance it rained: Progress towards a proxy for palaeocloud
Authors: Fletcher Tamara , Tindall Julia , Voss Jochen , Haywood Alan
Published: February 2023

Cloud has profound impacts on climate, thus accurate cloud simulation is critical for accurate climate modelling. As the greatest source of uncertainty in such models, cloud drives discrepancies in the prediction of future climate. Cloud simulations are validated against recent observations; however, these records do not capture the climate space we are entering this century, limiting our ability to test model accuracy under near future conditions.The best analogue for the 21st Century climate trajectory comes from the Pliocene. Reconstructions of Pliocene cloud regimes would provide critical validation data for climate model performance with respect to cloud. However, despite the wealth ways to reconstruct other climate variables, no method has been developed for reconstructing cloud in deep time.We are working towards proxies capable of reconstructing past cloud, with the goal of establishing a global cloud database for the Pliocene. Our initial results demonstrate the relationship between vegetation and large-scale patterns in cloud in the modern, and tests the model derived from the modern data against palaeoclimate model vegetation and cloud.
Unravelling watershed fluxes to detect emerging changes of the water balance
Authors: Rietbroek Roelof , Karimi Sedigheh , Shakya Amin
Published: February 2023

In a warming climate, atmospheric water vapour will increase, intensifying the global water cycle. However, this ”wet-get-wetter” and ”dry-get-drier” paradigm does not hold on regional scales and models seem to contradict observations. Furthermore, it is unknown whether modelled atmospheric moisture fluxes, entering and leaving the watersheds, are mass consistent with river discharge and sinks and sources such as aquifers, soil layers and surface waters. Consequently, observational evidence of the changing water cycle components is crucial for scrutinizing models. It is also essential to assess climatic water cycle trends which have far reaching ecological and socio-economic consequences, through the occurrence of heat waves, flooding, forest fires and water availability.In this contribution, we introduce a 5 year research project, which was recently funded through the Vidi talent scheme programme of the Dutch Research Council. We will explain how we plan to use satellite gravimetry, radar altimetry, in a joint inversion scheme, to estimate water fluxes in and out of the watersheds of the North Sea region, and those of the Greater Horn of Africa. Furthermore, we’ll show how regional sea level change and vertical land motion will be consistently accounted for in the proposed estimation scheme.
Strata-dependent thrust localisation in multilayers
Authors: Sleath Phoebe , Butler Rob , Bond Clare
Published: February 2023

In most idealised models of thrust fault formation thrusts form along a weaker basal detachment and then propagate upwards through strata, producing a hang-wall anticline and developing in a piggy-back sequence. This idealised thrust fault geometry commonly fails to match actual outcrop structures. Conversely, in a stiff layer thrusting model, the thrust originates and localises in mechanically competent beams as ramps and the thrust tip propagates both up and down slowly to create a linked fault system. This model has had few tests at outcrop level and the lack of field examples has hindered adoption of this model. In the UK, thrust structures in the Old Red Sandstone are ideal test outcrops as they contain a multilayer stratigraphy of competent sandstone beds encased in cleaved mudrocks. Field and photogrammetric mapping has been applied to the St Brides Haven outcrop on the west coast of Pembrokeshire in SW Wales, the 10m high outcrop exposes an open fold pair cut by thrusts typical of Variscan deformation. The outcrop has an abrupt rheological change within the multilayer with a 1m thick sandstone bed within mudstones. Thrust faults are confined to the strong sandstone beam, with a fault spacing along the competent beam, with cleavage development in the mudstone above and below. The structural style is controlled by variations in the multi-layer rheology, and fault localisation in the competent sandstone beams appears to be balanced by distributed deformation in the form of cleavage development in the mudstones. The outcrop matches key features of the stiff layer thrusting model.Observations from this outcrop show that the observed thrust fault geometry evolved from soft to hard linked across the multilayer. Drag faults have developed in both the hanging and footwalls, showing thrusts initiate in the stiff layers. Cleavage developed in the mudstones and along rheological boundaries the cleavage and thrust trajectories connect. The outcrop matches key features of the stiff layer thrusting model. This work contributes to a series of studies on fold-thrust outcrops to expand the range of widely used models and avoid bias in interpretation of fold-thrust belts when basing work on theoretical models.
A mathematical perspective on the formalization of risk mitigation
Authors: Bilotta Giuseppe , Cappello Annalisa , Ganci Gaetana
Published: February 2023

The classic definition of risk as the product of hazard, exposure and vulnerability was initially intended as a qualitative rather than quantitative formula. Its informal nature becomes more apparent when evaluating strategies for risk mitigation, for which different informal equations have been presented in the literature.We offer here a mathematical perspective on the equations that define risk and a novel approach for a quantitative analysis of risk mitigation that help highlight decision variables among the many input variables that participate in risk analysis and modeling.We show how the classic Risk = Hazard * Exposure * Vulnerability formula represents a zero-order approximation of the more formal integral representation that we derive, and that risk mitigation can be quantified based on parallels with mathematical homotopies with an associated cost function, with an interesting outlook on the design of both long-term and short-term risk mitigation strategies.
Dynamics of sinkhole and uvala development on the eastern shore of the Dead Sea, 1980-2022
Authors: Schulten Hanna Z. , Watson Robert A. , Al-Halbouni Djamil , Al-Rabayah Osama Al-Rabayah , Abdulla Fayez , Holohan Eoghan P.
Published: February 2023

The Dead Sea is a hypersaline terminal lake whose level has been declining due to anthropogenic stresses since the 1960s. At its eastern shore, near Ghor-Al-Haditha in Jordan, over 1200 collapse sinkholes have been mapped roughly parallel to the shoreline from the 1980s until 2017. This mapping also documented five larger karstic depressions (uvalas), that formed in close spatial-temporal association with the sinkholes, and demonstrated that sinkhole and uvala formation during this period has migrated laterally, both in the direction of shoreline retreat (from east to west) and parallel with the shoreline from south to north.Here, we use new, high-resolution optical satellite imagery from the Pleiades and PNEO satellites, to show that over 500 new sinkholes have formed between 2018-2022. Furthermore, three new uvalas have developed to the north in accordance with the appearance of the sinkholes. Our study indicates quantitatively that the coalescence of sinkholes to form larger compound sinkholes is a subsequent stage of uvala development. New mapping confirms a previously established link between sinkhole size distribution and the mechanical properties of the sedimentary materials in which they form, with holes formed in salt-dominated morphologies being smaller in diameter than those in alluvium and lacustrine mudflats. Initial comparison to local meteorological records has shown that a temporal link between periods of high rainfall and enhanced sinkhole formation is not readily apparent at the resolution of the sinkhole mapping. Moreover, as previous studies had hypothesized, growth of the sinkhole population and the uvalas continues towards the north and is diminished to the south. Our results help to inform hazard monitoring and mitigation strategies at Ghor Al-Haditha: for example, presently growing areas of surface depressions are within 130 meters of a 700-meter-long stretch of the western main highway connecting the north and south of Jordan. Therefore, we suggest that infrastructure such as the highway continue to be monitored in light of the observed subsidence.
Fully synchronous coupled ice/ocean modelling of future changes in the Amundsen Sea Sector
Authors: Bett David , Bradley Alexander , Williams Rosie , Holland Paul , Arthern Robert , Goldberg Daniel
Published: February 2023

The Amundsen Sea Sector has some of the highest thinning rates of ice shelves in Antarctica, thought to be driven by high, but interannually variable, ocean driven melt rates. This thinning can lead to increased ice flow speeds, eventually leading to sea level rise. To fully represent these processes and other feedbacks, a fully coupled ice/ocean model must be used. Therefore, a fully synchronous mass conservative coupled ice-sheet/ocean model of the Amundsen Sea Sector has been developed. This new coupled model builds upon previous coupling developments and involves coupling of the WAVI ice-sheet model to the 3D ocean model MITgcm, via the Streamice ice-sheet model. Coupled model projections are presented, examining ice grounding line retreat rates and ice mass loss, along with ocean driven melt rate evolution. The sensitivity of these results to ocean forcings is shown, specifically the thickness of the relatively warm Circumpolar Deep Water layer and its variability. In addition, we discuss the impact of the present-day initialisation and tuning of the coupled model.
The impact of the 2018 Lombok earthquake sequence, Indonesia on the unrest Rinjani-Samalas volcanic complex inferred from the time-dependent seismic and volcanic source models
Authors: Zhao Siyuan , McClusky Simon , Miller Meghan , Cummins Phil
Published: February 2023

In 2018, four deadly (Mw 6.2 to 6.9) earthquakes struck the north coast of Lombok Island, on 28 July, 5August, and 19 August, distributed between the Flores back-arc thrust and the Rinjani-Samalas volcanic complex, causing hundreds of fatalities and extensive damage. We performed a comprehensive analysis of relocated aftershocks, static coulomb stress changes, and co-seismic and post-seismic deformation, to improve our understanding of this earthquake sequence. The fault geometries and slip distributions of the three mainshocks are modelled by inverting the co-seismic deformation imaged using an interferometric analysis of Sentinel-1 synthetic aperture radar (InSAR) measurements, based on rectangular dislocations embedded in a multi-layered elastic half-space. The earthquake sequence aftershocks were analysed using an unsupervised learning method (ST-DBSCAN) to cluster these relocated aftershocks so that we can identify the source of each aftershock. We used a time-series consisting of 658 descending and 370 ascending Sentinal-1 InSAR interferograms to investigate the time-dependent post-seismic deformation in the two years following the Lombok 2018 earthquake sequence, deriving a combined model that simulates the viscoelastic relaxation and afterslip simultaneously. The Coulomb stress change modelling based on the co-seismic and post-seismic rupture models indicates about 1 MPa of extensional stress change at 10 to 20 km of depth and 0.5 Mpa extensional stress change at 15 to 25 km of depth around the Barujari Crater region, respectively, which affects the open of the magma conduct, reflected as caldera-scale deflation and inflation. To quantify the influence of the earthquake sequence on the spatiotemporal deformation pattern of the volcano edifice, we extended our InSAR time-series range forward to the year 2014, just prior to the two eruptions that occurred on 25th October 2015 and 1st August 2016, and perform Principal Component Analysis to investigate the time-dependent inflation and deflation signals. We modelled the volume change and the location of the volcano pressure source for a better understanding of how changes in the magma body and magma movement may have been influenced by the 2018 Lombok earthquake sequence. A double-source compound model is used to invert the parameters of the magma chamber, including a shallow Moji point pressure source centred at 1.3 km north of the Barujari cone, and a deep source centred at 1.5 km northeast of the Rinjani cone, at ~3.9 km and ~3.5 km depth below the sea level respectively. We also used a uniform sill and dike combined model to interpret the co-eruptive signals surrounding the observed eruptive fissures. Our best-fit dike is nearly vertical, reaching a depth of 2 km below sea level with an opening of 8.5 cm, and the sill is at the depth of 3.1 km with a contraction of 40 cm.
A machine learning approach to recover GRACE-B accelerometer data
Authors: Behzadpour Saniya , Gou Junyang , Kiani Shahvandi Mostafa , Öhlinger Felix , Mayer-Gürr Torsten , Soja Benedikt
Published: February 2023

In gravimetry satellite missions GRACE (Gravity Recovery and Climate Experiment) and GRACE-FO (GRACE Follow-On), accelerometer measurements from both satellites are necessary for the gravity field recovery. The accelerometer provides accurate measurements of the non-gravitational forces acting on the spacecraft, such as atmospheric drag, solar radiation pressure and albedo. These measurements are required to separate any non-gravitational effect from the sought-after gravitational perturbations on the spacecraft motion. Therefore, the quality of accelerometer data, denoted as ACC products, significantly affects the quality of gravity field models.Near the end of the GRACE mission, due to the reduced battery capacity, the on-board accelerometer of the GRACE-B was turned off and its measurements were replaced by synthetic accelerometer data, called transplant data. The transplant data are generated by a series of adjustments to the GRACE-A ACC data. A similar approach was also employed for the GRACE-FO mission, when the GRACE-D ACC data degraded and were required to be replaced with synthetic data as well. Using the transplant data in both missions is one of the main challenges of providing high-quality gravity field models.We investigate the feasibility of Machine Learning (ML) algorithms for the recovery of GRACE-B ACC based on GRACE-A measurements and orbital data such as shadow factor and β angle. Taking advantage of ~14 years of GRACE-B measurements, this work aims to develop a model which can predict the missing accelerometer data under different orbital conditions. Two different architectures are implemented to forecast GRACE-B accelerometer data: Multilayer Perceptron (MLP) and Long Short-Term Memory (LSTM). The performance is evaluated using the Root Mean Square Error (RMSE) and by comparing the predicted data with the calibrated real data in the evaluated period. Furthermore, the ML-based ACC products will be compared to the transplant products and their impact on the gravity field will be discussed.
Characteristics of spectral energetics during excess and deficient rainfall years in India
Authors: Dhishana Ravi , Dubey Sarvesh Kumar
Published: February 2023

Significant spatial and temporal deviations from the seasonal mean precipitation, such as severe droughts (deficient rainfall) and floods (excess rainfall), have a major influence on India. The non-linear energy interactions between the various scale atmospheric systems are important as they play a crucial role in the Indian summer monsoon variability. Since studies have yet to look at the whole energy budget of the southwest monsoon, it is necessary to accurately capture these energy exchanges to represent the monsoon circulation better. In this study, we found the exact nature of complex non-linear energy interactions of synoptic-scale mainly low-pressure systems (LPSs) and Intraseasonal Oscillation (lSO) 30-60 day scale with other scales, including the seasonal mean, Indian Ocean Dipole (IOD), and El Niño–Southern Oscillation (ENSO) using the in-scale and out of scale energetics. These energy interactions are calculated in the frequency domain for the Indian monsoon region using the ECMWF ERA-5 data for 72 years (1950-2021) during the monsoon season (JJAS). Since the seasonal mean kinetic energy is highly correlated with the seasonal mean rainfall, we explored how these energy exchanges vary during excess and deficient rainfall years. We also found that the ISO and synoptic scale systems influence the interannual variability of the Indian Summer Monsoon mainly through the interactions with the mean flow. In addition, the monsoon mean flow and most energy exchanges show a significant relationship at the upper level (200 hPa) and lower level (850 hPa) atmosphere.
Quasi-Lagrangian studies of spatio-temporal correlation in incompressible MHD turbulence
Authors: Mäusle Raquel , Müller Wolf-Christian
Published: February 2023

Turbulence is of fundamental importance for many physical systems on Earth and throughout the universe. A turbulent flow can be described as the superposition of turbulent fluctuations of various length scales, which interact with each other non-linearly, leading to a transfer of energy across scales. We aim at a better understanding of the temporal and spatial properties of this energy transfer process in plasma turbulence, by studying the spatio-temporal correlation between turbulent structures in magnetohydrodynamic (MHD) turbulence.To this end we perform three-dimensional direct numerical simulations with a pseudo-spectral method. We employ the quasi-Lagrangian reference frame, in which tracer particles are followed in the flow each carrying with it a set of probes at fixed distances across which the fluctuations are computed. This avoids the large-scale sweeping effect, which in the case of fixed-grid (Eulerian) measurements would obscure the small-scale temporal dynamics. This approach is based on previous studies in Navier-Stokes turbulence [Physics of Fluids 23.8 (2011): 085107] and has been extended to account for the magnetic field.We investigate systems with different mean magnetic field strength. The spatio-temporal correlation functions yield insight into the nature of the cross-scale transfer of energy in terms of the direction, strength, and time scale of the transfer process. In particular, the scaling of the correlation times perpendicular and parallel to the local magnetic field, the influence of the mean magnetic field and the implications for the current understanding of the cross-scale transfer process are discussed.
Seasonal skew of tropical savanna fires
Authors: Eames Tom , Russell-smith Jeremy , Yates Cameron , Vernooij Roland , van der Werf Guido
Published: February 2023

Tropical savannas and grasslands are the most frequently burned biome in the world, and fire constitutes an important part of the ecosystem. In this ecosystem it can have both rejuvenating and destructive effects, depending on several factors including fuel conditions, weather conditions, and time of year. For centuries humanity has used fire in these landscapes for hunting, land clearance, agriculture, and most recently carbon offsetting. Land managers in locations with a monsoonal climate and frequent fire regimes such as tropical savannas use prescribed burning as a management tool in the ‘early dry season’ (EDS) shortly after the last rains of the year. Fires at this time tend to be cooler, restricted to surface level and less severe, meaning they can be controlled more easily and tend to go out at night without external input. Commonly a specific, fixed date is used to indicate when this window of safe burning has expired, set based on experience of the local or regional authority. In this work, we have defined a method of determining when this window expires on the basis of active fire hotspot data from the twin MODIS instruments from 2001 through to 2021. By using the relationship between day and night-time active fire detections, we set a flexible date for the transition between the early and late dry seasons in fire-prone savannas globally in the five major tropical savanna regions - Northern & Southern hemisphere South America (NHSA & SHSA), Northern & Southern hemisphere Africa (NHAF & SHAF), and Australia (AUST). The variability across each region was high (lowest mean standard deviation annually was 24 days in NHAF and highest was 56 in AUST). The fraction of area burned in the late dry season ranged from 15% (SHSA) to as high as 85% (AUST) on average, with many parts of Africa and Australia especially showing a significant skew towards the late dry season. This suggests potential for implementation of prescribed burning programmes to increase the amount of desirable fire in the global savanna ecosystems.
Parametric methods for assessing the production of suspended sediment and its deposition in artificial lakes - an example of Lake Trakošćan, Croatia
Authors: Oskoruš Dijana , Leskovar Karlo , Pavlić Krešimir
Published: February 2023

Abstract: A very common engineering task we encounter in practice is calculating the annual balance of sediments on some watercourse. This is particularly challenging when assessing the backfilling of river reservoirs that have a multifunctional function.Trakošćan Lake was built in the period from 1850 to 1862 as a pond and landscape addition to the park and Trakošćan castle. The topographic catchment area of the lake is 10.7 km2, it is about 1.5 km long, and its area is about 17 hectares, with an average depth of about 2.5 meters. The lake's total volume was originally 400,000 cubic meters, and downstream from the dam, the water of the Čemernica stream flows into the Bednja River.After 61 years, the lake was drained, and in 2022, work began on sediment excavation to improve the lake's ecological condition due to about 200,000 cubic meters of deposited silt in the lake. The projected depth of the lake after cleaning would be about 6 meters.In the example of this artificial lake, an estimate of the annual sediment spread by empirical parametric methods was carried out. Furthermore, the results were compared with the results of previous analysis obtained based on geotechnical sediment investigation at Lake Trakošćan.
Assessing global trends in lava flow impact events
Authors: Meredith Elinor , Jenkins Susanna , Hayes Josh , Lallemant David , Deligne Natalia , Teng Rui Xue Natalie
Published: February 2023

The destruction of thousands of homes by lava flows of Nyiragongo volcano, Democratic Republic of Congo, and La Palma, Canary Islands, in 2021 serve as a reminder of the devastating impact of lava flows. However, studies on lava flow impacts on the built environment are relatively rare. We reviewed literature to compile a global dataset of lava flow impacts to buildings and infrastructure from ~3500 BCE to 2022 CE, and use this to assess temporal and spatial trends of events. Our findings show a recent increase in recorded events, and that these occur more frequently than previously thought, with almost four impact events per decade in the past 100 years. This is likely from population expansion and reflecting a recent increase in recording. The majority of recorded events were in Italy, USA, and Réunion Island, France, with a rise in records in Africa since 1800 and the most impacted structures at Nyiragongo volcano, DRC. Impact records have developed from qualitative eruption reports to quantitative impact assessments, and the majority of studies report a binary impact on structures; with towns and/or structures stated as either destroyed or unaffected. However, several reports give specific details of damage indicating that lava flow impacts may not be binary. The dataset provides a baseline to assess past impacts, and be updated as future studies reveal past lava flow impact events, or when future lava impact events occur.
Evolution of aerosol plumes from 2019 Raikoke volcanic eruption observed with polarization lidar over central China
Authors: He Yun , Jing Dongzhe , Yin Zhenping
Published: February 2023

The Raikoke volcano erupted on 21-22 June 2019 and emitted ~1.5 Tg volcanic ash into the atmosphere. Several previous studies have focused on the large-scale dispersion of volcanic aerosol plumes with space-borne observations and dispersion models. However, height-resolved ground-based observations are still necessary to trace and cross-check the 3-D evolution of aerosol plumes due to their complicated structures. Here, we present a rare ground-based lidar observation of Raikoke aerosol plumes in the mid-latitudes of the Northern Hemisphere (site: Wuhan; location: 30.5°N, 114.4°E) from 25 July to 30 September 2019. Two types of volcanic aerosol plumes were observed, including the main aerosol plume and a single impacted aerosol cloud (referred to as ‘CCC’, or coherent circular clouds). The main aerosol plume first arrived at Wuhan on 25 July and was intermittently observed during the following two months at altitudes of 15.0-20.5 km, with layer-integrated AODs (aerosol optical depths) of 0.001-0.017. From 22 August to 23 September, this aerosol plume underwent two quasi-elliptical transport pathways in East Asia driven by an Asian monsoon anticyclone. The CCC arrived at Wuhan twice at 20.2-21.7 km on 30 July and at 23.2-25.0 km on 24-26 August after self-lofting, corresponding to the former two circles of their transport around the Northern Hemisphere. Both arrivals of the CCC were closely followed by a thin and horizontally extended aerosol plume (named ‘trail’) with a duration of several days. The unique observation location provided us with an opportunity to study the evolution of the vertical distribution and optical properties of volcanic aerosols, which is anticipated to be a crucial supplement/reference for dispersion model simulation, data assimilation, and forecasting refinement.
Methane emissions from offshore oil and gas production activities in Gabon and Angola: First results from the airborne METHANE-To-Go campaign 2022
Authors: Roiger Anke , Eckl Maximilian , Puehl Magdalena , Gottschaldt Klaus-Dirk , Braeuer Tiziana , Aufmhoff Heinfried , Eirenschmalz Lisa , Sakellariou Felicitas , Neumann Gregor , ventura guilherme , Cadete Winne
Published: February 2023

Methane (CH4) is after carbon dioxide the second most important anthropogenic greenhouse gas. Due to its comparatively short lifetime of ~10 years, a significant reduction in anthropogenic CH4 emissions would help to reduce the atmospheric concentration within a decade with near term temperature benefits. However, the development of efficient mitigation strategies needs to be informed by identifying, locating and quantifying CH4 emissions from the different sectors. A large part of CH4 emissions from the global oil and gas sector is expected to arise from offshore production, which currently however is understudied. Off the coast of Gabon and Angola, oil and gas production is spread over more than 800 kilometres across a wide variety of offshore installations, covering both shallow waters and deep sea. Here we report on airborne measurements conducted using the DLR Falcon along the west coast of Central Africa in September 2022. The DLR Falcon was equipped with a suite of different in-situ instruments to measure CH4 and a series of other trace species, as well as meteorological variables. Measurements were taken during 15 science flights to quantify emissions related to offshore oil production. We will present and discuss our airborne results on regional and facility-scales, in dependency of e.g. infrastructure type and age, and compare them with available inventory estimates and industry reportings. Our collected data, co-funded by the International Methane Emissions Observatory (IMEO), will help coal, oil and gas companies and governments, to prioritize their methane emission mitigation .
Use of biochar to enhance carbon sequestration in peatlands
Authors: Fearns-Nicol Emily , Worrall Fred , Knapp julia
Published: February 2023

Although peatlands are a great store of terrestrial carbon they are only a small sink compared to other nature-based or technological approaches to carbon sequestration. So as to exploit the considerable carbon storage potential of peatlands is it possible to enhance the magnitude of the peatland carbon sink with additional inputs of carbon? Biochar is refractory form of carbon that can be sourced from natural woody materials including biomass that may grow on peatlands. Biochar’s refractory nature means that it has commonly been proposed for nature-based carbon storage. The advantage of using biochar on peatlands is that natural accumulation of peat means that the growth of peat may absorb the added biochar where on mineral soils biochar may come to dominate with repeated additions of char. However, the fate and impact of biochar on the natural function of peat soils is not known – this study has aimed to fill this knowledge gap and assess whether biochar could be applied to peatlands?This study has conducted a random-block design based upon two different application rates of biochar to a former lowland raised bog in Yorkshire. The trial consisted of triplicated plots considered within the water table frame of the peatland and plots visited at least monthly for more than a year. The plots were monitored for: gross primary productivity; net CO2 exchange; ecosystem respiration; soil water quality; albedo; and vegetation coverage alongside measurement of water table depth and weather parameters.The study shows:that although biochar is alkali, and that there was an initial difference in pH due to biochar treatment, this difference did not last;
the soil water conductivity was dominated by changes in depth to water table and not biochar treatment;
after 10 months the DOC in soil water on treated plots was significantly higher on biochar treated plots;
vegetation had recovered from biochar treatment within 6 months; and
there was no significant difference in NER between treatments showing no ready decomposition of the biochar.
The limitations of biochar to enhance carbon storage in peatlands are more likely to be economic than biogeochemical.
Global ocean product of profiles of nutrients and carbonate system variables within the framework of Copernicus Multi Observations Thematic Assembly Center (MOBTAC)
Authors: Renosh Pannimpullath Remanan , Sauzède Raphaëlle , Claustre Hervé
Published: February 2023

To better understand the global ocean biogeochemical processes, it is crucial to strengthen the spatial coverage of high-quality biogeochemical variables. In this context, we provide high-quality nutrients (nitrate, phosphate and silicate) and carbonate system variables (total alkalinity, dissolved inorganic carbon, pH and partial pressure of carbon dioxide) profiles for BGC-Argo floats equipped with oxygen sensors and data qualified in delayed mode. These variables are derived using neural network models called CANYON-B and CONTENT for nutrients and carbonate system variables, respectively. For the Mediterranean Sea, we deliver these variables from a regional dedicated model called CANYON-MED. These variables are distributed from September 2002 to August 2022 as part of CMEMS MOBTAC service. The last update of the product will be available in CMEMS portal from March 2023.At the global scale, nitrate, phosphate and silicate are retrieved with an accuracy (from the root mean squared difference) of 0.68, 0.051, 2.3 µmol kg-1, respectivelyand the carbonate system variables, i.e., total alkalinity, dissolved inorganic carbon, pH and partial pressure of carbon dioxide are retrieved with an accuracy of 6.2 µmol kg-1, 6.9 µmol kg-1, 0.013 (unitless), and 15 µatm, respectively. The global models (CANYON-B and CONTENT) have also been validated with independent data collected from recent various oceanic cruises not used for the development of the methods (from GLODAPv2.2021 database) and the Hawaii Ocean Time series (HOT). These independent validations demonstrate the validity of these models for global ocean applications. The nitrate and pH products were again validated against measured nitrate and pH from BGC-Argo floats equipped with oxygen sensors. Overall validation results were quite satisfactory at global and regional spatial scales.Currently, the profiles are available for BGC-Argo floats with concurrent profiles of temperature, salinity and oxygen qualified in delayed mode. This product will be also available from near real-time observations from 2024.