bluuebunny/crossref_metadata_2025 huggingface dataset:
Perspectives and methodological challenges of imaging soil hotspots and coupling soil images of different origin in multi-imaging approach
Authors: Bilyera Nataliya , Banfield Callum C. , Dippold Michaela A.
Published: February 2023

Soil imaging visualizes and quantifies processes in soil hotspots across space and time involving microorganisms, roots and carbon and nutrient sources, thereby helping to elucidate mechanisms. A wide range of individual approaches exists to determine spatial distributions of soil pH (optodes), root exudation and pesticides (14C phosphor imaging), fertilizers (33P phosphor imaging), nutrient fluxes (DGT), etc.Since processes and mechanisms are clearly multi-factorial, combining individual approaches is key for any real understanding of soil processes. Multi-imaging comes with a set of challenges as firstly, scales need to be bridged as imaging methods operate at different spatial scales from cm to nm. Secondly, their time scales vary from minutes to days. Thirdly, the sequence of method application needs careful consideration as some methods leave behind chemicals, which may interfere with other measurements.Imaging methods were initially developed for laboratory-controlled conditions, and only several were already adapted for field conditions. We will present the challenges for application soil imaging techniques in the field and problems related to sequential application. We will suggest a workflow for multi-imaging, which includes suggestions on coupling methods to study defined soil process, the sequence of the methods application, image alignment, hotspot thresholding and analysis, co-localization of images and quantitative image analysis. The perspectives, advantages and challenges of multi-imaging approaches will be comprehensively discussed.
Thermochronologic constraints on exhumation associated with the Main Pamir Thrust
Authors: Sobel Edward , Kley Jonas , Rembe Johannes , Thiede Rasmus , Glodny Johannes , Grimm Lennart , Rometsch Maximilian , Newigy Asil , Ali Nowrad , Altyeb Wafaa , Espinoza Tapia Daniela
Published: February 2023

The Pamir orogen forms the northwest prolongation of the Tibetan plateau. The most important surficial structure bounding the northern and northwestern margin is the Main Pamir Thrust (MPT); however, despite the importance of the structure, surprisingly little is known about the displacement history of the fault. Together with the younger, foreland-oriented Pamir Frontal thrust system (PFT), displacement estimates range from 50 to over 300 km. The larger estimates are based on the estimated Cenozoic northward indentation of the Pamir with respect to Tibet as well as the length of the intracontinental Pamir seismic zone. However, recent work suggests that some of the indentation predates the Cenozoic or is related to an original Paleozoic embayed paleogeography and other studies have suggested that the seismic zone is not related to intracontinental subduction. Shortening estimates in the hanging walls of the MPT and PFT suggest more modest amounts: between 30 and 75 km in the north, with higher values for SE-NW shortening in the Tadjik depression.Constraining the onset of deformation has proven challenging. Most publications suggest a late Oligo-early Miocene onset age. Cenozoic stratigraphic sequences are unfossiliferous and poorly dated. We have attempted to resolve this question by collecting samples for thermochronologic analysis from many locations along the arcuate margin. In general, zircon (U-Th-Sm)/He (ZHe) samples yield ages between ~60 and 17 Ma. Many are likely to be partially reset. Ages are slightly older in the east, which could reflect an overall westward increase in exhumation. The relatively small amount of exhumation in the north supports our structural interpretation that the MPT there has a low dip angle and might not have produced pronounced topography. Apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) are often much younger; often between <15 and 10 Ma in the MPT hanging wall and < 10 Ma in the footwall. These younger ages may reflect the activation of a second pulse of exhumation linked to motion along the PFT. We are modeling these data sets using QTQt to try to better constrain the exhumation history of the fault system. In turn, these should help constrain shortening estimates.
Lagrangian analysis of convective rainfall under different synoptic forcing
Authors: Meredith Edmund P , Ulbrich Uwe , Rust Henning W
Published: February 2023

Precipitation is commonly analysed from an Eulerian perspective, in which rainfall is considered at a fixed location. Lagrangian analysis of precipitation represents an alternative approach. Here, precipitation objects – for example, convective cells – are identified in a precipitation field and are then tracked through space and time, allowing object properties over the whole life of a convective cell to be collected. This approach offers additional insights into the mechanisms by which convective cells develop and behave across their lifecycle, which would not be evident from standard analysis methods.In this study, we perform Lagrangian analysis of convective cells under different large-scale circulation regimes. Tracking is based on convection-permitting simulations with the COSMO-CLM at 0.025° resolution over central Europe. All identified precipitation objects are tracked through space and time, collecting cell characteristics for each object, e.g. cell area, intensity, distance travelled, etc. Here we associate precipitation objects with categorical synoptic-scale circulation patterns and compare the cell properties between the different categories.
Near realtime tomographic reconstruction of atmospheric water vapour using multi-GNSS observations in Central Europe
Authors: Rozsa Szabolcs , Turak Bence , Khaldi Abir
Published: February 2023

Continuously operating reference stations (CORS) are widely used to provide near realtime estimates of zenith tropospheric delays and tropospheric gradients to be assimilated in numerical weather models. Due to the latest evolution of global satellite navigation systems and ground based augmentation services, it became feasible to estimate the 3D distribution of wet refractivities in near realtime.This paper presents a near realtime tomographic reconstuction algorithm utilizing the zenith tropospheric delays and tropospheric gradients obtained from the processing of several GNSS networks in Hungary (HU), Slovakia (SK), Romania (RO) and Ukraine (UK). The estimated zenith tropospheric delays (ZTDs) and tropospheric gradients are used to restore the slant wet delays (SWD) affecting the observed satellite-receiver range. The SWDs are used as input for a tomographic reconstruction algorithm based on the multiplicative algebraic reconstruction technique. The developed software tool includes a stepwise outlier detection module to select the most reliable slant wet delays for the tomographic reconstruction. It provides the wet refractivities in a pre-defined voxel model on an hourly basis over the HU-SK-RO-UA cross-border region.The derived refractivity profiles have been validated with radiosonde observations. The results show that our GNSS tomography approach could reconstruct the refractivities with the standard deviation of 5 ppm below 3 km of altitude, while the standard deviation decreased to the level of 0.3 ppm at the altitude of 10 km.The estimated tropospheric delays as well as the refractivity profiles are made available online to the meteorologists community in Little-R format and can be directly assimilated in the Weather Research & Forecast numerical model. 
Full vector inversion of magnetic microscopy data using Euler deconvolution as a priori information
Authors: Ferreira de Souza Junior Gelson , Ivan Ferreira da Trindade Ricardo , Uieda Leonardo , Fu Roger , Araujo do Carmo Janine
Published: February 2023

Classically, paleomagnetic data is obtained from bulk samples, where the signal is obtained from the sum of all magnetic moments within the sample volume. This typically includes stable and unstable remanence carriers. With the advance of microscope imaging techniques (e.g., SQUID microscopes, Quantum Diamond Microscopes) it is now possible to spatially isolate the contribution of single grains or clusters of grains. Yet, despite recent advances in the inversion techniques to derive full vector information from the magnetic microscopy data, there is still no inversion protocol capable of obtaining the magnetization directions of each magnetic particle without using a priori information or physically separating the spatial position of each anomaly. Here we present an algorithm capable of automatically identifying the position of each magnetic anomaly source by combining signal processing and tridimensional Euler deconvolution. Subsequently, we recover both the direction and the intensity of the magnetic moment of each magnetic source with no need for any kind of additional information. The method presented here is a potential technique that may help increase the statistical accuracy of data obtained in paleomagnetic studies from magnetic microscopy data, especially in the case of complex characteristic remanent magnetization.
İs it science fiction movie or reality of the future ?
Authors: Akin Ayca
Published: February 2023

Global warming, which is the agenda issue of the global challenge of sustainable development, will become the big problem of today's younger generation. Recently various studies have been carried out on this subject in many fields such as energy, transportation, agriculture and architecture. As a biology teacher, this situation of the future generation, causes me concern as global warming will be the main focus of their lives. For this reason, I believe that raising student awareness about global warming is a priority. In my opinion, the first step of this awareness is to make students pay attention to this extremely important topic. I usually use ‘research-review educational method’ in my biology lessons for raising awareness by giving a real situation and problem that the students must solve. By doing this, they should be able to grasp the subject and working together in teams, acquire important problem-solving skills, which will enable them to come up with creative ideas which can then be evaluated. Our story starts with the question 'What challenges life in Antarctica other than the cold?' continues with the next question ‘what kind of life will we expect in the future?’ and concludes with a global warming awareness survey. Based on the living conditions of Antarctica, I carry out a study by drawing attention to what they know about this subject and what they could do if they were in such a situation. I am planning to present some processes from student's work in my poster. As a result, children’s imagination and awareness can be the science fiction movie for today but maybe it is a reality of the future.
Drivers of very rapid sea ice loss on sub-seasonal timescales
Authors: Aylmer Jake , Feltham Daniel , Methven John , Volonté Ambrogio
Published: February 2023

Very rapid ice loss events (VRILEs) are extreme, local reductions in Arctic sea ice extent on timescales of days to weeks. They are poorly captured in operational forecasts that are used, for instance, to inform shipping through the Arctic Ocean. A better understanding of the drivers and underlying processes is thus critical to a range of stakeholders. We analyse summertime (May–September) VRILEs occurring in a simulation (1980–2022) with the sea ice model CICE forced by atmospheric reanalyses. Our configuration includes novel marginal ice physics such as a prognostic floe size distribution and an explicit form drag scheme. Most VRILEs are dominated by thermodynamic processes. However, many events occurring near the start or end of the melt season are driven by advective redistribution, often associated with the presence of a cyclone. We illustrate this with key case studies and generalise the results to all simulated VRILEs using simple metrics quantifying the dominant contributions to the sea ice concentration tendencies and atmospheric conditions in each event. Finally, a suite of parameter sensitivity studies highlights factors with potential to improve forecasting of VRILEs.
Comparing Life-Cycle Environmental Impacts of Natural Gas-Fired and Renewable Electricity Generation
Authors: Young Michael , Gulen Gurcan , Ur Rehmman Atta , Chapman David
Published: February 2023

The mission of the Comparing Electricity Options (CEO) research program at UT Austin is to understand and quantify trade-offs among society’s goals of providing reliable and affordable energy, mitigating climate change, and improving local environments that can sustain a healthy economy for future populations. Our goals are to create tools that support decision makers in the energy and policy sectors with better environmental and economic assessments to manage environmental, social, and governance risks across global supply chains; highlight where innovation can mitigate impacts; and, inform policies that encourage innovation. This is done by conducting a three-phase, data-driven study of natural gas-fired, wind, and solar power plants (including batteries to address intermittencies). We use several methodologies and will develop interactive tools to allow wider audiences to quickly compare alternative scenarios. In Phase 1, which we anticipate will be completed in early 2023, we conduct a life-cycle assessment (LCA) of power plants for 18 impacts covering greenhouse gas and local (PM, SOX, NOX) emissions; land and water use and pollution, biodiversity and ecosystem services, etc. The LCA system boundaries encompass extraction of natural resources, manufacturing of generation equipment, power plant operations, and end-of-life. In Phase 2, which will begin in mid-2023, we investigate electric power grids instead of individual power plants, and aggregate environmental impacts and costs associated with transitioning generation mixes over time, including new transmission and distribution infrastructure. In Phase 3, we use results from Phases 1 and 2 to develop a new cost estimate for electricity at the consumer level that includes environmental and system costs. We show early results from Phase 1 and how environmental impacts are manifested along the global supply chains needed to support energy development, at different times during the 30-year lifespan of the facilities.
Top-down constraint of net carbon exchange in tropical South America
Authors: Botía Santiago , Munassar Saqr , Koch Thomas , Abdi Amir Hossein , Basso Luana S. , Komiya Shujiro , Lavric Jost , Walter David , Gatti Luciana V. , Gloor Emanuel , Miller John , Peters Wouter , Rödenbeck Christian , Gerbig Christoph
Published: February 2023

The contribution of vegetation to the South American carbon balance is critical for understanding the regional dynamics in net carbon exchange. Of particular interest is the role of the Amazon region as a sink or source of carbon to the atmosphere. Recent evidence indicate a weakening of the Amazon carbon sink, and when taking fires into account, the region represents a source of carbon to the atmosphere. In this study we use a regional atmospheric inversion system together with data from the Amazon Tall Tower Observatory (ATTO) and airborne profiles of CO2, to constrain the Net Biome Exchange (NBE) in tropical South America. At the domain-wide scale we find that the atmospheric observations can constrain 64% of the land mass, with uncertainty reductions in most of the Amazon region, and the adjacent Cerrado and Caatinga biomes. Furthermore, we provide a sub-regional-specific analysis showing the effect of assimilating the Amazon Tall Tower Observatory CO2 time series on the mean seasonal cycle of NBE for four areas within the Amazon, the Cerrado and the Caatinga. An emerging sink-source gradient between the Amazon region (sink) and the integrated effect of the Cerrado and Caatinga (source) is found, but the source is located in the boundaries and outside the eastern border of the legal Amazon. Optimized NBE estimates at regional and subregional scales are shown and the importance of the continuous measurements at ATTO is highlighted. Finally, we indicate the areas with a limited data constraint in our system and conclude that the observational network has to be further expanded for reducing the remaining uncertainty in top-down inverse approaches for this region.
Ambient noise monitoring of the Bayou Corne sinkhole evolution
Authors: Mordret Aurelien , Lavoué Anais , Witten Benjamin , Baig Adam , Beaupretre Sophie , Courbis Romeo , Gradon Chloé
Published: February 2023

The collapse at depth of a cavern on the side of the Napoleonville salt dome, Assumption Parish, Louisiana, led to the formation of a large sinkhole at the surface. Besides surficial evidence from direct observations, the precise timeline of the evolution of the sinkhole is poorly known.  Here, we used two years of continuous ambient seismic vibrations recorded at 11 3-component seismic stations located around the Bayou Corne sinkhole to monitor the daily relative seismic velocity changes associated with the sinkhole activity. The sinkhole started to form in 2012 and had several phases of activity. The seismic network was installed in early 2013 and recorded the last major collapses before settling in 2014. Following standard seismic interferometry processing, we computed the full 9-component tensors of ambient vibrations cross-correlations between each pair of sensors. After a drastic quality check of the correlations, we rejected several components for which we did not have enough data or for which the data were corrupted in a way that was difficult to correct. We monitored the relative velocity variations (dv/v) during the studied period using the stretching method in the 0.9-3 Hz frequency band within the early coda of the correlations. We employed a reference-less inversion procedure to obtain a dv/v time series for each component and each pair of stations. The multi-component pairs curves are averaged to get the final time series. The results show significant velocity changes in early 2013 associated with the collapse phases of the sinkhole. The velocity recovers steadily after the second half of 2013 and all of 2014. Two seismically active periods generate smaller velocity drops. In agreement with the spatial extension of the sinkhole toward the southwest seen from the surface, the pairs of stations the most affected by large velocity drops are the ones located along the southwestern shore of the lake.Our monitoring allows for refining the timeline of the events affecting the sinkhole and its overall activity with a daily temporal resolution. From the analysis of these two years of data, the sinkhole stabilized after intense activity in early 2013. The large velocity variations indicate a strong destructuring of the ground, with potential fracturing and water invasion.
Coronal Diagnostics of Solar Type-III Radio Bursts Using LOFAR and PSP Observations
Authors: Nedal Mohamed , Kozarev Kamen , Zhang Peijin , Zucca Pietro
Published: February 2023

Understanding the physical processes underlying solar radio bursts requires both high- and low-frequency observations, as well as imaging capabilities. In this study, we implement a fully automated approach to detect and characterize type III radio bursts, image their sources in the corona, and characterize the plasma environment where the bursts are triggered. We utilize data from the Low-Frequency Array (LOFAR) and the Parker Solar Probe (PSP) to investigate several type-III radio bursts that occurred on April 3, 2019. Through data pre-processing and combining the LOFAR and PSP dynamic spectra, we study the solar radio emissions between 2.6 kHz and 80 MHz. By extracting the frequency drift and speed of the accelerated electron beams, we gain insight into the physical processes driving these bursts. Additionally, by using LOFAR interferometric observations to image the sources of the radio emission at multiple frequencies, we are able to determine the locations and kinematics of the sources in the corona. We also use Potential Field Source Surface (PFSS) modeling and magnetohydrodynamic (MHD) simulation results to determine the magnetic field configuration and plasma parameters in the vicinity of the moving emission sources. These observations and analysis provide valuable constraints on the coronal conditions that trigger solar radio bursts.
Heat sources for Variscan high temperature-low pressure metamorphism: constraints from a petrochronological investigation of the Trois Seigneurs Massif, French Pyrenees
Authors: Connop Charlotte , Smye Andrew , Garber` Joshua
Published: February 2023

The thermal budget of metamorphic terranes with evidence for kilometric-scale partial melting in the shallow crust (< 15 km depth) cannot be solely explained by conductive relaxation of thickened crust. Such high temperature-low pressure (HT-LP) metamorphism demands a prodigious heat supply to overcome the cooling effect of heat loss from the Earth’s surface. In this study, we present results from a systematic monazite and zircon petrochronological investigation of a classic HT-LP terrane: the Variscan-aged Trois Seigneurs Massif, French Pyrenees.The massif is composed of a progressive metamorphic sequence from chlorite-bearing phyllites to sillimanite-bearing migmatites, culminating in an S-type granitoid body that occupies over one-third of the massif’s area. Phase equilibrium modelling refines established pressure-temperature (PT) conditions of melting and granite formation to 4-6 kbar and >685 °C. Monazite from five metapelitic samples spanning the structural thickness of the massif records an extended period of metamorphism from 330-290 Ma, with only the low-grade andalusite schists recording a significant population of U/Th-Pb dates older than 310 Ma. Higher-grade schists and migmatites preserve dates from 310-295 Ma, constraining the duration of peak metamorphism, which overlaps zircon U-Pb dates obtained from the S-type granitoid (305.1 ± 1.9 Ma). Peak metamorphic conditions and granitoid emplacement dates at the Trois Seigneurs massif overlap with other published dates for HT-LP metamorphism and granitoid emplacement across the entire Variscan Pyrenees. Combining these PT estimates with those derived from proximal Variscan Pyrenean massifs defines a composite ‘dogleg’ geotherm with elevated dT/dz through the shallow crust (>50 °C/km, <12 km) but near-isothermal conditions through the mid-crust (12-25 km).A simple thermal model is used to show that this ‘dogleg’ thermal structure can be attained in <15 Myr by advection of magmatic heat between the lower and shallow crust. For such a mechanism to operate on orogenic length scales, however, requires a critical combination of: i) a fertile lower crust buffering the deep crust at the wet solidus, ii) attenuated mantle lithosphere during the waning stages of orogenesis, and ii) significant focusing of melt through the crustal column. We speculate that melt-driven HT-LP metamorphism should be present in other orogenic belts where these conditions are met.
A glacio-hydrological perspective on the extreme year 2022 in Switzerland
Authors: Van Tiel Marit , Huss Matthias , Zappa Massimiliano , Farinotti Daniel
Published: February 2023

Summer 2022 broke numerous glaciological, hydrological and climatological records in Europe. Dry and warm conditions led to extreme low-water levels and problems with water supply. The hot summer in combination with little snow in winter was disastrous for the Swiss glaciers; they never lost as much volume in the century-long observational record. At the same time, this massive glacier melt meant an alleviation of the downstream hydrological drought situation. Glacier contributions to streamflow during hot and dry periods, as well as their changes due to glacier retreat are, however, poorly quantified.In this study, we characterize the glacio-hydrometeorological extremeness of the hydrological year 2022 in Switzerland and compare it with other exceptional years in the past. Observational streamflow records from about 80 stations along glacier-fed rivers were analyzed, together with (i) temporally downscaled and spatially extrapolated glacier mass balance observations, as well as (ii) temperature and precipitation information. Results show that precipitation and temperature were exceptional, but there have been years since 1961 that were warmer or drier. However, the combined effect of low precipitation and high temperatures led to record-low summer flows throughout Switzerland, apart from the Rhone river, the upstream part of the Aare river, and a few high-elevation catchments. Catchments with a glacier cover of more than 20% even resulted in above normal summer streamflow in 2022.The annual relative meltwater contribution from glacierized areas ranged from a few percent up to 80% of the total streamflow among the catchments and equaled up to double the mean contribution estimated for the period 1981-2010. Although 2022 glacier volume losses broke records, only a few catchments showed a record amount of glacier melt water contribution to streamflow. This may hint that for most catchments, glacier retreat is dominating the melt response to extreme warm conditions, instead of differences in the respective meteorological conditions. This process reduces the crucial capacity of glaciers to alleviate downstream drought conditions. Overall, the study highlights the need for an integrated analysis of meteorological, hydrological and glaciological data to understand the spatiotemporal dynamics of extreme dry and warm years. 
Twenty four years of geochemical monitoring of the oceanic active volcanic island of El Hierro, Canary Islands
Authors: Di Nardo Daniel , Hernández William , Rodríguez Claudia , Rodríguez Fátima , Barrancos José , Padrón Eleazar , Melián Gladys V. , Padilla Germán D. , Pérez Nemesio M. , Asensio-Ramos María , Hernández Pedro A.
Published: February 2023

El Hierro (278 km2) is one of the eight islands of the Canary Islands archipelago. It is an oceanic island formed ~1.2 Ma ago and one of the most active from a volcanic point of view of all the Canary Islands. Its last historical eruption was submarine eruption that began on 12 October, 2011 until 5 March, 2012, off its southern coast, which was the first to be monitored in the Canary Islands. Since 1998, periodic diffuse CO2 surveys have been carried out (except for the 2011-2012 seismic-volcanic unrest and eruptive periods, when the surveys frequency increases, Melián et al., 2014) by means of the accumulated chamber method measuring the diffuse CO2 emission at 601 points distributed homogeneously throughout the emerged 278 km2 of El Hierro. CO2 emission rate measured in the entire island has been varying over time, registering highest values in the pre-eruptive and eruptive periods where a significant increase of this gas emission rate was registered. Soil CO2 efflux values for the 2022 survey ranged between non-detectable (<0.5 g·m−2·d−1) to 38.0 g·m−2·d−1, with an average value of 2.6 g·m−2·d−1. Diffuse CO2 output from the studied area was estimated in 616 ± 26 t·d-1 for El Hierro Island, a value above the background average of CO2 emission estimated on 412 t d-1, but within background range of 181 t·d-1 (−1σ) and 930 t·d-1 (+1σ) calculated at El Hierro volcano during the quiescence period 1998-2010 (Melián et al., 2014). The monitorization of the diffuse CO2 emission has demonstrated that contributes to detect early warning signals of volcanic unrest, especially in areas where visible degassing is non-existent as in the El Hierro Island. Melián et al. (2014), J. Geophys. Res. Solid Earth, 119, 6976–6991, DOI 10.1002/2014JB011013
Kinetic modeling of the interaction of solar wind discontinuities with the bow shock-magnetosheath-magnetopause system
Authors: Berchem Jean , Lapenta Giovanni , Escoubet Philippe , Wing Simon
Published: February 2023

Modeling the interaction of solar wind discontinuities with the bow shock-magnetosheath-magnetopause system is an important step in comprehending the effects of solar wind structures on the magnetosphere. Our procedure is to first run a global MHD simulation to predict the overall configuration of the solar wind-magnetosphere system before the discontinuity interacts with the bow shock. Then fields and plasma moments within a large sub-domain of the global MHD simulation are used to set the initial conditions of an implicit PIC simulation of the interaction of the discontinuity with the dayside magnetosphere. This procedure allows us to follow the evolution of kinetic processes as the discontinuity interacts with the bow shock and propagates through the magnetosheath before impacting the dayside magnetopause. In this presentation, we show some results of the interaction of a rotational discontinuity where the interplanetary magnetic field, initially southward, turns northward. As expected, the discontinuity slows down abruptly after interacting with the bow shock, the transverse component of the magnetic field being greatly enhanced in the process.  While the initial MHD state of the magnetosheath was laminar, kinetic waves and instabilities lead to a turbulent state for all plasma moments and electromagnetic fields. In particular, transients are observed ahead of the discontinuity as it propagates Earthward. At later stages of the simulation, the discontinuity interacts with the magnetopause. Magnetic field lines are bent strongly in the transverse direction, affecting reconnection processes with the production of large magnetic flux ropes.
Impact of reduced aircraft emission on HOx Chemistry in the upper troposphere during BLUESKY Campaign 2020.
Authors: Sreekumar Sreedev , Tsokankunku Anywhere , Marno Daniel , Rohloff Roland , Martinez Monica , Tadic Ivan , Hamryszczak Zaneta , Pozzer Andrea , Curtius Joachim , Fischer Horst , Bohn Birger , Obersteiner Florian , Lelieveld Jos , Harder Hartwig
Published: February 2023

Hydroxyl radicals are the most predominant daytime initiator for atmospheric oxidation processes. Due to the COVID -19 pandemic, there was a considerable reduction in emissions from industry and all means of transportation during spring 2020. The main objective of the BLUESKY campaign is to understand the effect of these reduced emissions on atmospheric composition such as trace gases, aerosols, and cloud properties. OH and HO2 were measured with HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy), during eight research flights from the boundary layer up to 14 km.  Here we present the impact of reduced aircraft emissions and the meteorological situation on the HOx Chemistry in the upper troposphere over Europe during the COVID-19 lockdown. We contrast the findings during BLUESKY with results from previous campaigns and analyze the occurrence of HOx during daytime in the outflow of electrified and non-electrified convective systems.
Solar radiation management from Icelandic volcanoes during the Medieval Quiet Period
Authors: Sigl Michael , Gabriel Imogen , Abbott Peter , Behrens Melanie , Burke Andrea , Chelman Nathan , Cook Eliza , Fleitmann Dominik , Fuglestvedt Herman , Hörhold Maria , Hutchison William , Krüger Kirstin , McConnell Joseph R. , Óladóttir Bergrún Arna , Plunkett Gill , Preiser-Kapeller Johannes , Zhuo Zhihong
Published: February 2023

“Solar Radiation Management” aims to mitigate global warming by either seeding aerosols into clouds to change their radiative properties and occurrence frequency, or injecting sulfur into the atmosphere to shield the Earth’s surface from incoming solar radiation. These approaches are inspired, among other things, by the effect of volcanic eruptions on the climate system.Here we provide a critical reassessment of a time period commonly referred to as the “Medieval Quiet Period”. For several centuries in early Medieval times (c. 750-1050 CE) the climate system was postulated to have been relatively unperturbed by natural climate forcing, resulting in a unique period of climate stability. We present evidence that just the opposite is true. In large parts of the Northern Hemisphere and in the Arctic, atmospheric aerosol loads were persistently high during this period as a result of increased volcanic activity, especially in Iceland.Our new insight is supported by evidence taken from an array of synchronized ice cores from Greenland with high time-resolution records of a large suite of trace elements, including volcanic volatiles such as sulfur, chlorine, fluorine, and heavy metals. We use crypto-tephra in ice cores to provenance the sources of many volcanic eruptions and sulfur isotopes (33S, 34S) to delineate if volcanic gas emissions occurred above or below the ozone layer.We define an “Iceland Active Period”, a time period of frequent and prolonged volcanic activity, producing persistently high levels in atmospheric aerosol burdens in the Northern Hemisphere Arctic’s preindustrial atmosphere lasting for decades to centuries. The frequency and cumulative amount of emissions of climate-impacting trace substances (e.g., sulfates, halogens, ash) is unprecedented in the late Holocene. It is exceeded at times only in the Anthropocene (since about 1900) and in the early-middle Holocene (e.g. during rapid deglaciation). We demonstrate that previous reconstructions of volcanic forcing used in PMIP3 and PMIP4 strongly underestimate volcanic aerosol emissions in the early Medieval and argue that this period should not be considered a reference climate state for the Common Era.Finally, we investigate possible aerosol-climate interactions following these eruptions using climate proxies and state-of-the-art chemistry climate models with prognostic stratospheric aerosols and chemistry.
Evaluating the accuracy of the Greenland Ice-Core Chronology (GICC)
Authors: Rasmussen Sune Olander , Sinnl Giulia , Svensson Anders , Vinther Bo Møllesøe
Published: February 2023

The full potential of palaeoclimate data relies on reliable time scales, i.e., a relation tying the physical dimension of the palaeoclimate archive with age. For many records, including ice cores, identification and counting of annual layers is the most direct and accurate way to obtain a time scale provided that high-resolution measurements of parameters showing annual variability are available. Annual-layer counting can provide very precise estimates of event durations and rates of change, but as errors accumulate with age, the accuracy decreases with depth/time. In contrast, radiometric methods often have good accuracy, and in principle, the two approaches can be combined to form highly accurate and precise time scales provided that the archives and their time scales can be robustly aligned. This can be done based on e.g. volcanic markers, common and correlatable features in cosmogenic isotope records, or on climatic wriggle-matching when the possible leads and lags between records is considered.The Central Greenland ice cores are drilled in the interior areas of the ice sheet where precipitation rates are appropriate for the formation and preservation of annual layers, thereby allowing annual layers to be identified in the Holocene period and well into the last glacial period. The Greenland Ice-Core Chronology (GICC) is an attempt to derive a consistent, common time scale for the Greenland ice cores by combining data from multiple cores, using for each time period all available annually resolved data and then applying the time scale to the other cores by means of matching patterns of volcanic eruptions and other reference horizons. In this way, data from all the ice cores can be interpreted together on a common time scale (i.e., with very small relative dating uncertainty), greatly reducing the risk of artificial offsets due to misinterpretation of individual records. The first version of GICC, named GICC05, was published in 2006 and 2008, where the dating covered the time period back to 60 ka b2k, at which point the layers had thinned too much to continue with continuous annual layer counting.Since then, high-resolution data from the newer Greenland ice cores NEEM and EGRIP have appeared, and comparisons to other palaeoclimate records on radiometric time scales have shown that in some sections, GICC05 was not as accurate as initially estimated, motivating a revision on the time scale. The top 3.8 ka of the time scale was recently revised, leading to changes in age of 10-15 years for the section older than 2500 years (see presentation by Giulia Sinnl). Here, we review the older sections of GICC05 in the context of other well-dated palaeoclimate archives and cosmogenic isotope records, as well as model-based estimates of climate leads and lags relevant when aligning climate records, and outline a plan for how to continue the revision of GICC05.
On the critical layer interaction of the stratospheric Kelvin waves
Authors: Shaaban Ahmed , Roundy Paul
Published: February 2023

Stratospheric Kelvin waves are known to be absorbed by the background flow via mechanical and thermal damping and, to less extent, by the critical layer interaction. Critical layer interaction occurs when the Kelvin waves' phase speed approaches the background flow's speed. This study aims to depict the structure of the Kelvin waves while approaching the critical layer, where the phase speed of the wave matches the speed of the background flow. In the time domain, the wavelet filtering technique filters Kelvin waves at a specific location and phase speeds using ERA-I zonal wind. Linear regression yields the pattern of specific phase speed's Kelvin wave. Yet, the critical layer interaction of the Kelvin waves with the environmental flow could be studied by choosing a background environment in which its flow speed matches the wave's phase speed, which could be implemented using the varying-coefficient regression technique. We found that the in-phase relationship between the zonal wind and height, associated with the structure of the Kelvin waves, relaxes with the decreasing of the Doppler-shifted speed; then, at a further reduction of the Doppler-shifted speed, the Gill pattern appears. Furthermore, Kelvin waves were found to be absent under an environment of westerly shear.
Initiation and mechanism of rock slope failures triggered by the 2016 Mw 7.8 Kaikōura earthquake
Authors: Singeisen Corinne , Massey Chis , Wolter Andrea , Stahl Tim , Bloom Colin , Kellett Richard , Bruce Zane , Gasston Caleb , Mason Doug , Jones Katie
Published: February 2023

The 2016 Mw 7.8 Kaikōura earthquake on New Zealand’s South Island triggered c. 30,000 landslides. Around 70% of landslides occurred in Torlesse greywacke rock mass, which is characterised by closely spaced but low-persistence joints. Most failures in this rock mass were relatively shallow rock avalanches which do not appear to follow traditional failure mechanism models. Here, we use detailed site characterisation and dynamic numerical modelling to better understand landslide hazard and risk from Torlesse greywacke slopes. Using multi-method site characterisation including 3D pixel tracking in pre- and post-earthquake aerial imagery, geomorphic mapping, rock mass characterisation, geophysical ground investigations and a geotechnical borehole, we developed engineering geological ground models for individual sites. We then used these to develop a conceptual framework of failure mechanism in Torlesse greywacke and propose a ‘joint-step-path’ failure mechanism in which rupture surface propagation occurs along pre-existing, but low-persistence joints through multiple degrees of kinematic freedom. Torlesse greywacke failures typically evolve in three main landslide failure stages – incipient, transitional and rock avalanching. Hazard can increase for the same slope when it transitions from the incipient failure stage to sliding and/or avalanching. To quantify the transition between failure stages, we analysed coseismic displacement and strain for six landslides. As many displacement based coseismic landslide susceptibility models require some threshold, above which the slope is assumed to transition into a landslide, this information could potentially serve as a useful tool. For slopes at the incipient and transitional stage, 1D maximum total strain appears to be closely correlated with source slope angle. Based on these results, we develop the ‘transitional slope strain index’ (TSSI) that combines 1D maximum total strain with source slope angle. The TSSI relates to the likelihood of a slope transitioning into a more mobile, and therefore more hazardous, rock avalanche at a given level of earthquake shaking. Dynamic numerical back-analysis of the initiation of two landslides in Torlesse greywacke supports our empirical hypotheses that landslide susceptibility in this rock mass is strongly influenced by slope angle and rock mass strength. Coseismic failure initiation is, furthermore, strongly dependent on ground motion input. The geometry of failures can be reproduced using a random Voronoi joint network and adopting residual joint strength parameters, which further lends weight to the ‘joint-step-path’ failure mechanism hypothesis.
Weather regime characterisation of the atmospheric environment leading to the development of tropical cyclones in the Northern Tropical Atlantic
Authors: Gaetani Marco , Flamant Cyrille , Jonville Tanguy , Chaboureau Jean-Pierre , Lavaysse Christophe , Cuesta Juan , Menut Laurent , Castillo Natalia , Formenti Formenti
Published: February 2023

At the end of the monsoonal season in West Africa, tropical cyclones (TCs) start to develop in the Northern Tropical Atlantic off shore Senegal, south of Cape Verde. TCs generally develop from low pressure disturbances travelling westward from West Africa embedded in the African easterly waves (AEWs), characterised by organised convection and high specific humidity. Some of these TCs eventually evolve into tropical storms and hurricanes. However, whereas there is overall agreement concerning the main necessary conditions, involving sea surface temperature (SST) and vertical wind shear, for a TC to evolve into a tropical storm or a hurricane, the elements concurring to the formation of TCs from easterly depressions are still unclear. Indeed, the environment where the transition occurs is characterised by complex interactions involving atmospheric dynamics and aerosol-cloud-radiation interactions not fully understood yet.The purpose of this study is to contribute to enlighten the mechanisms leading an easterly African depression to evolve (or not) into a TC in the Northern Tropical Atlantic, by characterising the atmospheric environment off shore Senegal and south of Cape Verde, where TCs start to develop. To this aim, a weather regime (WR) classification of the atmospheric variability is first performed on a climatological time scale in a region including West Africa and Northern Tropical Atlantic. The WR classification is then used to characterise the relevant atmospheric variables involved in the TC development. In particular, the role of major outbreaks of mineral aerosols from the adjacent Sahara Desert is investigated. Data from ERA5 and CAMS reanalysis products are analysed for the period 1991-2020.
Carbon Monitor Europe, a near-real-time and country-level monitoring of daily CO2 emissions for European Union and the United Kingdom
Authors: Ke Piyu , Deng Zhu , Zhu Biqing , Zheng Bo , Wang Yilong , Boucher Olivier , Ben Arous Simon , Zhou Chuanlong , Dou Xinyu , Sun Taochun , Li Zhao , Yan Feifan , Cui Duo , Hu Yifan , Huo Da , Pierre Jean , Engelen Richard , J. Davis Steven , Ciais Philippe , Liu Zhu
Published: February 2023

With the urgent need to implement the EU countries pledges and to monitor the effectiveness of Green Deal plan to reduce greenhouse gases emissions, Monitoring Reporting and Verification tools are needed to track how emissions are changing for all the sectors. Current official inventories only provide annual estimates of national CO2 emissions with a lag of 1+ year which do not capture the variations of emissions due to recent shocks including COVID lockdowns and economic rebounds, supply chains tensions and rising prices of energy and commodities, war in Ukraine. Here we present a near-real-time dataset of daily fossil fuel and cement emissions to monitor country-level emissions from January 2019 through December 2021 for 27 European Union countries and the United Kingdom. This dataset is called Carbon Monitor Europe. The data are calculated separately for six sectors: power, industry (incl. cement production), ground transportation, domestic aviation, international aviation, residential emissions which includes the built environment. Daily CO2 emissions are estimated from a large set of activity data compiled from different sources, including hourly to daily electrical power generation data, monthly production data and production indices of industry, daily mobility data and indices for the ground transportation. Individual flight location data and monthly data were for aviation sector estimates. Monthly fuel consumption data downscaled in time with daily air temperature are used to estimate daily emissions from commercial and residential buildings. The goal of this dataset is to improve the timeliness and temporal resolution of emissions for European countries, to inform the public and decision makers about current emissions changes in Europe.
Carbonate-platform response to the Toarcian Oceanic Anoxic Event in the Tethys Himalaya
Authors: Han Zhong
Published: February 2023

The Toarcian Oceanic Anoxic Event (T-OAE, ~183 Ma) was a profound short-term environmental perturbation associated with the large-scale release of 13C-depleted carbon into the global ocean-atmosphere system, which resulted in a significant negative carbon-isotope excursion (CIE). The general lack of characteristic T-OAE records outside of the northern hemisphere means that the precise environmental effects and significance of this event are uncertain. Many biotic carbonate platforms of northern hemisphere from the western Tethys drowned or shifted to comparatively unfossiliferous oolitic platforms during the early Toarcian. However, southern hemisphere records of Toarcian carbonate platforms are rare, and thus the extent and significance of biotic platform demise during the T-OAE is unclear. Here we present high-resolution biostratigraphical, sedimentological, and geochemical data across two Pliensbachian–Toarcian shallow-water carbonate-platform sections exposed in the Tethys Himalaya. These sections were located paleogeographically on the open southeastern tropical Tethyan margin in the southern hemisphere. The T-OAE in the Tethys Himalaya is marked by a negative CIE in organic matter. Our sedimentological analysis of the two sections reveals an abundance of storm deposits within the T-OAE interval, which emphasizes a close link between warming and tropical storms during the T-OAE, in line with evidence recently provided from western Tethyan sections of the northern hemisphere. In addition, our analysis also reveals extensive biotic carbonate-platform crisis by drowning or changing to unfossiliferous carbonates coincident with the onset of the CIE where the proxies of continental weathering (e.g. Ti, Sc, Th) and redox (e.g. Mn, Ce and Ce) show obviously increase. Taken together, the drastically enhanced terrigenous flux and deoxygenation likely played a pivotal role in the more severe crisis for benthic carbonate producers during the negative phase of the CIE.