bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of cumulative anthropogenic carbon emissions, emission duration, and negative emission scenarios on melting of the Greenland ice sheet
Authors: Höning Dennis , Calov Reinhard , Talento Stefanie , Willeit Matteo , Ganopolski Andrey
Published: March 2022

Budgets of remaining anthropogenic carbon emissions have been estimated to keep global warming below a limit (IPCC report 2021). A main impact of global warming is the rise of the sea level caused by melting of the Greenland ice sheet. However, the response of the Greenland ice sheet to temperature rise is strongly nonlinear. Melting depends on the time interval at which the ice sheet is exposed to high temperatures and on its rate of change, and a short time interval of high emission would therefore not necessarily result in the same sea level rise as long intervals of low emission. In order to make adequate predictions about sea level rise associated with melting of the Greenland ice sheet at specific times in the future, it is therefore crucial to explore the impact of cumulative emissions in combination with the emission duration.

We simulate Earth’s evolution for the next 20,000 years using CLIMBER-X, a fully coupled Earth System model of intermediate complexity, including modules for atmosphere, ocean, land surface, sea ice and the interactive 3-D polythermal ice sheet model SICOPOLIS, which is applied to the Greenland ice sheet at a spatial resolution of 16 km. In a first step, we explore equilibrium states of the volume of the Greenland ice sheet using constant partial pressures of atmospheric CO2. We also explore tipping points related to these states, i.e. unstable states of the ice volume where smaller values would lead to further melting until the associated stable state is reached. Next, we investigate the critical cumulative carbon emission to cross these tipping points. Finally, we assess the influence of the emission duration on crossing the tipping points and on the convergence rate towards the associated equilibrium states. We also investigate to what extent future negative emissions could limit sea level rise.

Our results show how high carbon emission rates, even throughout a short time interval, cause the Greenland ice sheet system to rapidly approach equilibrium states of smaller ice volume. This convergence cannot completely be offset by future negative emissions. In contrast, a quick decrease of global emissions, even if in combination with an extended time period of small net emissions in the future, would substantially delay sea level rise and could even prevent the system from crossing the tipping points.
Can the use of basalt dust mitigate the drought stress effects in grapevine? Setup of monitoring approach and protocols in a case study on Falanghina in Southern Italy
Authors: Petracca Francesca , Cirillo Chiara , Bonfante Antonello , Arena Carmen , Giulioli Marco , Erbaggio Arturo , Damiano Nicola , Caputo Rosanna , De Micco Veronica
Published: March 2022

In the inland of Southern Italy, climate change puts viticulture at risk of sustainability. Cultivar-specific cultivation techniques, also designed to suit peculiar pedoclimatic conditions of the vineyard, are needed to stabilize the productivity of vines, increase the grape quality, and improve the use efficiency of resources. Currently, the Italian legislation requires that vineyards are cultivated as rainfed to achieve quality and/or geographical indication labels. However, climate forecast models indicate that in the next decades there will be an increase in severity and duration of drought events that will affect the growth and productivity of vines beyond a threshold level making rainfed vineyards unsustainable.

The aim of this study was to verify whether foliar applications of basalt dust can mitigate the negative effects of drought stress in a vineyard of Falanghina grapevine in Southern Italy. The vineyard is in an inland area of Campania Region, at the premises of the La Guardiense farm, in Guardia Sanframondi, Benevento. A pedological survey, supported by a geophysical campaign, was performed to detect the soil spatial variability of the area and to identify the four subplots where the following treatments were imposed: 1) rainfed with the application of basalt powder on the leaf surface during the vine vegetative-productive cycle (i.e. from April to September); 2) rainfed,without distribution of basalt powder; 3) irrigated, with basalt powder; 4) irrigated, without basalt powder. The irrigation plan was defined weekly, applying a model considering precipitation and evapotranspiration, to reintegrate the water losses by transpiration. The growth and the ecophysiological traits of vines were monitored in the main phenological phases by measuring morphological parameters, fertility, leaf gas-exchanges, chlorophyll a fluorescence emission, leaf water potentials, and leaf anatomical characteristics, while the meteorological data and soil water content were collected through weather stations and time-domain reflectometry (TDR) technique. The production of each experimental plot was evaluated in terms of chemical characterization of musts and wines in order to assess the oenological potential. Specific attention was paid to the setup of protocols for ecophysiological measurements to avoid bias and evidence the occurrence of possible photoprotection mechanisms. Results of the first year of experiments indicated the occurrence of interaction between the two main factors in a year particularly dry. The repetition of the experiments in the next years will allow us to unravel both the interference with climatic variability and the long-term effects due to the combination of factors.
Screening dilute sources of rare earth elements for their circular recovery 
Authors: Lima Ana Teresa , Kirkelund Gunvor , Ntuli Freeman , Ottosen Lisbeth M.
Published: March 2022

Metals, including rare earth elements (REE), are the cornerstone of our current and future low-carbon urban infrastructure. This study looks at different waste resources and contaminated materials present in the urban setting as REE sources. Wastes and other dilute sources such as incineration ashes, sediments, and mine tailings are not only essential sources of REE in achieving a circular, carbon-neutral economy but may be the most realistic one. E-waste, being the most REE concentrated waste, faces serious reservations regarding handling in largescale facilities, and this waste is generally landfilled. After analyzing different residues, coal fly ashes and stormwater retention pond sediments present the most promising ones. While coal fly ashes have the highest critical REE contents from the studied wastes, the sediments collected from a stormwater retention pond showed the highest REE leachability. Critical REE Nd, Dy, and Er can mainly be found in sediments/soils near highways, coal ashes, and bauxite residue. Overall, coal fly ashes contain the highest critical REE contents found in the studied wastes but sediments collected from stormwater water ponds present the highest leachable REE. In fact, up to 100% of total REE found in these sediments are leachable at room temperature low pH. Future REE resource extraction efforts should account for REE speciation in wastes and not only total contents.
Subsurface warming trends in response to climate change and local heat sources in Central Europe
Authors: Bayer Peter , Benz Susanne A. , Menberg Kathrin , Blum Philipp , Noethen Maximilian , Hemmerle Hannes
Published: March 2022

Under natural conditions the thermal signature at the Earth´s surface equilibrates with the geothermal heat flux. Given that downward propagation of heat by conduction and advection is magnitudes lower than the daily and seasonal variation at the surface, these short-phased patterns impart a dampened and long-phased temperature response in the shallow subsurface. While climate change manifests in temperature trends that correlate at decade scale this signature is integrated by the slow heat transfer in gradual subsurface warming. In many places land use and small scale anthropogenic structures overprint the thermal response of the subsurface to climate change at the surface. In our contribution we present evidence of subsurface warming in natural and anthropogenic settings for different case studies in Central Europe. Repeated temperature depth logs reveal that in natural environments shallow subsurface temperature rise is trailing when compared to the rise in surface temperature and diminishes towards greater depths (e.g. +0.35 K per decate at the surface, +0.28 at 20 m, and +0.09 at 60 m below ground level for 32 wells in Bavaria). While in general a coherent pattern is found for different locations in natural environments, site-specific trends have a high spread (e.g. +0.36±0.44 K per decade for 227 wells in Austria) and temperature can also be dependent on vertical or lateral groundwater flow in the region. In built-up areas temperature rise in the subsurface is characterised by a higher variance and often exceeds the rise of surface temperature. Especially in dense urban areas ground temperature is elevated indicating local extreme temperature rises that are magnitudes higher than temperature rise at the surface. The high variance originates partially from the scarcity of reliable and long-term monitoring. Monitoring data typically lacks either depth or time resolution as temperature is either continously logged at a single-depth, erratically measured as depth profile, or measured at the surface during groundwater quality measurements.
Assessing the potential of heliospheric imager data assimilation to improve CME modelling.
Authors: Barnard Luke , Owens Mathew , Scott Chris
Published: March 2022

Modelling the heliospheric evolution of Coronal Mass Ejections (CMEs) is challenging and fraught with uncertainty for a range of confounding reasons. For example, there are significant uncertainties in the boundary conditions of heliospheric numerical models and such models often use CME parameterisations which are known to be overly simplistic e.g. hydrodynamic perturbations without magnetic structure. Consequently, the uncertainty on modelled CME evolution remains high and simulations often struggle to accurately represent both in-situ and remotely sensed CME observations.

Data assimilation (DA) provides a framework for merging observations and a model of a system to return simulations that better represent the true state of a system. We are exploring how to use data assimilation techniques with the white-light Heliospheric Imager (HI) CME observations to generate CME simulations that better represent the observed evolution of CMEs.

Here we present the results of a set of Observing System Simulation Experiments that begin to quantify the potential gains from assimilating HI data into the HUXt solar wind model, using a particle filter data assimilation scheme based on Sequential Importance Resampling.

We explore several specific questions: 1) By how much does the HI DA improve the simulated kinematics profiles of CMEs. 2) From which observing location are HI data best able to improve simulations of Earth directed CMEs. 3) Is it necessary to assimilate the full HI image data, or is it sufficient to assimilate HI derived data products, such as the time-elongation profile of the CME front.
Kilometre-scale isotopic heterogeneity in abyssal peridotites from the Doldrums Fracture Zone (Mid Atlantic Ridge, 7-8ºN).
Authors: Sani Camilla , Sanfilippo Alessio , Payve Alexander A. , Genske Felix , Stracke Andreas
Published: March 2022

In Nd-Hf isotopic space the great majority of the global abyssal peridotites plot in the field defined by global MORBs. However, Hf isotope ratios by far exceeding those in ridge basalts, are locally observed in abyssal peridotites showing that the Earth’s mantle is more heterogeneous that inferred from ridge basalts [1]. Mantle peridotites exposed at the Doldrums Fracture Zone at the Mid Atlantic Ridge (7-8° N) reveal that such heterogeneity coexists on a kilometre-scale. Abyssal peridotites from the northern part of the Doldrums FZ domain can be grouped into residual peridotites and melt-modified (refertilized) samples [2]. New Nd-Hf isotopic data show that the refertilized peridotites preserve highly radiogenic Hf values (εHf up to 101) associated with MORB-like Nd isotopes (εNd up to 12), reflecting partial resetting of ancient highly depleted mantle by recent melt-rock interaction. On the other hand, despite a very depleted incompatible element compositions, the residual peridotites have Nd-Hf isotope ratios similar to the local MORB (εNd = 7-12 and εHf =12-19). They most likely reflect highly depleted mantle that has been entirely reset by reaction with extracted or retained melts, and hence developed with only modest incompatible element depletion until recent melting at the Mid Atlantic ridge axis, which led the strong incompatible element depleted of these peridotites. The kilometre-scale association of such isotopically heterogeneous domains suggests that the upper mantle exposed in this portion of Atlantic formed by a combination of ancient melting and melt-rock reaction processes, preceding its emplacement below the present-day Mid Atlantic ridge axis.

 [1] Stracke, A., et al., 2011. Abyssal peridotite Hf isotopes identify extreme mantle depletion. Earth and Planetary Science Letters, 308(3-4), pp.359-368. [2] Sani, C., et al., 2020. Ultra-depleted melt refertilization of mantle peridotites in a large intra-transform domain (Doldrums Fracture Zone; 7–8° N, Mid Atlantic Ridge). Lithos, 374, p.105698.
Slope stability monitoring system via three-dimensional simulations of rockfalls in Ischia island, Southern Italy
Authors: De Matteo Ada , Alvioli Massimiliano , Bonfante Antonello , Buonanno Maurizio , Castaldo Raffaele , Tizzani Pietro
Published: March 2022

Volcanoes are dynamically active systems in continuous evolution. This behaviour is emphasized by many different processes, e.g., fumarolic activity, earthquakes, volcanic slope instabilities and volcanic climax eruptions. Volcanic edifices experience slope instability as consequence of different solicitations such as i) eruption mechanism and depositional process, ii) tectonic stresses, iii) extreme weather conditions; all these events induce the mobilization of unstable fractured volcanic flanks.

Several methods exist to gather information about slope stability and to map trajectories followed by individual falling rocks in individual slopes. These methods involve direct field observation, laser scanning, terrestrial or aerial photogrammetry. Such information is useful to infer the likely location of future rockfalls, and represent a valuable input for the application of three-dimensional models for rockfall trajectories.

The Ischia island is volcano-tectonic horst that is a part of the Phlegrean Volcanic District, Southern Italy. It covers an area of about 46 km2 and it has experienced a remarkable ground uplift events due to a resurgence phenomenon. Slope instability is correlated both with earthquakes events and with volcanism phenomena. Specifically, evidences suggest that rockfalls occurred as an effect of the gravitational instability on the major scarps generated by the rapid resurgence, eased by the widespread rock fracturing.

We present results of an analysis relevant to the most probable individual masses trajectories of rockfall affecting the slopes of Ischia island. We first identified the prospective rockfall sources through an expert-mapping of source area in sample locations and statistical analysis on the whole island. Probabilistic sources are the main input of the three-dimensional rockfalls simulation software STONE.

The software assumes point-like masses falling under the sole action of gravity and the constraints of topography, and it calculates trajectories dominated by ballistic dynamics during falling, bouncing and rolling on the ground. Analysis of high-definition critical sector pictures, achieved by using UAV (Unmanned Aerial Vehicle) platform, will allow a detailed localization of source areas and an additional more robust simulations.

The procedure can be viewed as a multiscale analysis and allows besting allocating computational efforts and economic resources, focusing on a more detailed analysis on the slopes identified as the most risky ones during the first, large-scale analysis of the whole area.
Wood water content influences sap flux estimations under water limited conditions in a deciduous forest in Michigan
Authors: Restrepo Acevedo Ana Maria , Agee Elizabeth , Matheny Ashley
Published: March 2022

Sap flux measurements are the most common individual-scale measurements and are used as a proxy for transpiration through the conservation of mass. While multiple heat-tracer style sensor types exist, the most broadly used are Granier-style thermal dissipation probes (TDP). Beginning in 2014, work at University of Michigan Biological Station pioneered continuously monitoring wood water content using capacitance sensors in mature trees. This unique data set has been used to demonstrate the key role of stem-stored water, or the trees’ capacitance, to buffer transpiration against water stress. Furthermore, increasing evidence has shown diurnal variations in the hydraulic capacitance of stems as a result of changes in water stress under laboratory conditions. These variations may induce inaccuracy in the nocturnal maximum temperature (Tmax) baseline of TDP and cause underestimation of sap flux measurements. Therefore, it is critical to study the dynamics between wood water content and sap flux measurements under natural conditions to establish the likely impact of these variations and their influence on estimations of transpiration.

We pair continuous time-series measurements of wood water content with raw sap flux observations made using traditional thermal dissipation probes in a mixed forest in northern lower Michigan. We demonstrate that decreases in wood water content result in increases in the Tmax signal of the thermal dissipation probe under water stressed conditions. This behavior is in accordance to the theory of heat conductance and the specific heat capacity of solids with respect to changes in water content. Our results suggest that the diurnal dynamics of wood water content may be an important source of error in sap flux data during drought and other water limited conditions, and should potentially be considered for use as a correction factor when using thermal based sap flux measurement techniques.
Data-Driven Sentinel-2 Based Deep Feature Extraction to Improve Insect Species Distribution Models
Authors: Phillips Joe , Zhang Ce , Williams Bryan , Jarvis Susan
Published: March 2022

Despite being a vital part of ecosystems, insects are dying out at unprecedented rates across the globe. To help address this in the UK, UK Centre for Ecology & Hydrology (UKCEH) are creating a tool to utilise insect species distribution models (SDMs) for better facilitating future conservation efforts via volunteer-led insect tracking procedures. Based on these SDM models, we explored the inclusion of additional covariate information via 10-20m2 bands of temporally-aggregated Sentinel-2 data taken over the North of England in 2017 to improve the predictive performance. Here, we matched the 10-20m2 resolution of the satellite data to the coarse 1002 insect observation data via four methodologies of increasing complexity. First, we considered standard pixel-based approaches, performing aggregation by taking both the mean and standard deviation over the 10m2 pixels. Second, we explored object-based approaches to address the modifiable areal unit problem by applying the SNIC superpixels algorithm over the extent, with the mean and standard deviation of the pixels taken within each segment. The resulting dataset was then re-projected to a resolution of 100m2 by taking the modal values of the 10m2 pixels, which were provided with the aggregated values of their parent segment. Third, we took the UKCEH-created 2017 Land Cover Map (LCM) dataset and sampled 42,000, random 100m2 areas, evenly distributed about their modal land cover classes. We trained the U-Net Deep Learning model using the Sentinel-2 satellite images and LCM classes, by which data-driven features were extracted from the network over each 100m2 extent. Finally, as with the second approach, we used the superpixels segments instead as the units of analysis, sampling 21,000 segments, and taking the smallest bounding box around each of them. An attention-based U-Net was then adopted to mask each of the segments from their background and extract deep features. In a similar fashion to the second approach, we then re-projected the resulting dataset to a resolution of 100m2, taking the modal segment values accordingly. Using cross-validated AUCs over various species of moths and butterflies, we found that the object-based deep learning approach achieved the best accuracy when used with the SDMs. As such, we conclude that the novel approach of spatially aggregating satellite data via object-based, deep feature extraction has the potential to benefit similar, model-based aggregation needs and catalyse a step-change in ecological and environmental applications in the future.
Systemic modelling of soil functions under the impact of agricultural management
Authors: Weller Ulrich , König Sara , Betancur-Corredor Bibiana , Lang Birgit , Ließ Mareike , Mayer Stefanie , Stößel Bastian , Vogel Hans-Jörg , Wiesmeier Martin , Wollschläger Ute
Published: March 2022

The increasing demand for food and bio-energy gives need to optimize soil productivity, while securing other soil functions such as nutrient cycling and buffer capacity, carbon storage, biological activity, and water filter and storage. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soil with those functions, as well as the feedbacks between these functions.

We present a systemic soil model to simulate the impact of different management options and changing climate on the named soil functions by integrating them within a simplified system. The model operates on a 1d soil profile and integrates different processes including dynamic water distribution, soil organic matter turnover, crop growth, nitrogen cycling, microbial activity, and root growth.

We present the main features of our model by simulating a long-term field experiment and comparing the simulation results with measured data on yield, carbon, nitrogen and microbial biomass. Additional simulations on soil tillage show the relevance of soil structure for the main soil functions. This is possible due to the dynamic water submodel, which allows for a non rigid pore structure.

To evaluate the simulation results, we propose a combination of our mechanistic modelling with an indicator-based approach for a dynamic soil function evaluation.
A hybrid ML-physical modelling approach for efficient approximation of tsunami waves at the coast for probabilistic tsunami hazard assessment
Authors: Ragu Ramalingam Naveen , Johnson Kendra , Pagani Marco , Martina Mario
Published: March 2022

This work investigates a novel approach combining numerical modelling and machine learning, aimed at developing an efficient procedure that can be used for large scale tsunami hazard and risk studies. Probabilistic tsunami hazard and risk assessment are vital tools to understand the risk of tsunami and mitigate its impact, guiding the risk reduction and transfer activities. Such large-scale probabilistic tsunami hazard and risk assessment require many numerically intensive simulations of the possible tsunami events, involving the tsunami phases of generation, wave propagation and inundation on the coast, which are not always feasible without large computational resources like HPCs. In order to undertake such regional PTHA for a larger proportion of the coast, we need to develop concepts and algorithms for reducing the number of events simulated and more rapidly approximate the simulation results needed. This case study for a coastal region of Japan utilizes a limited number of tsunami simulations from submarine earthquakes along the subduction interface to generate a wave propagation database at different depths, and fits these simulation results to a machine learning model to predict the water depth or velocity of the tsunami wave at the coast. Such a hybrid ML-physical model can be further coupled with an inundation scheme to compute the probabilistic tsunami hazard and risk for the onshore region.
Semi-Analytical Method for Simulating Rotational Ground Motion in Two-Dimensional Heterogeneous Elastic Half-Space
Authors: Singla Varun , Lokmer Ivan
Published: March 2022

The seismic waves responsible for shaking civil engineering structures undergo interference, focusing, scattering, and diffraction by the inhomogeneous medium encountered along the source-to-site propagation path. The subsurface heterogeneities at a site can particularly alter the local seismic wavefield and amplify the ground rotations, thereby increasing the seismic hazard. However, due to paucity of direct recordings of rotational motions, little research has been done towards characterizing the amplifications of ground rotations in the presence of subsurface heterogeneities. This study aims to quantify these amplifications in the case of a 2-D heterogeneous elastic half-space excited by plane SH waves. A semi-analytical method based on the perturbation theory is developed to obtain the translational and rotational motions in the spectral domain. In this method, the problem of simulating motion in a heterogeneous medium is reduced to calculating the response of a homogeneous medium subjected to body forces representing the heterogeneities. Since the dynamic response of a homogeneous half-space subject to body forces is easier to synthesize, the proposed method is convenient to implement. The method is tested for accuracy by comparing its solution with that of a spectral finite element-based solver. Furthermore, the method is shown to be stable at high frequencies (up to 10 Hz) as well as when the subsurface heterogeneities are strong (~20%). The method is applied to an example 2-D heterogeneous medium to ascertain the amplifications in the ground rotations.
Global three-dimensional draping of magnetic field in Earth's magnetosheath from in-situ measurements
Authors: Michotte de Welle Bayane , Aunai Nicolas , Nguyen Gautier , Lavraud Benoit , Genot Vincent , Smets Roch , Jeandet Alexis
Published: March 2022

Understanding where the magnetic reconnection occurs at the Earth’s magnetopause is one of the important remaining questions about this phenomena. Since the last decades various models predicting the position of the X-line have been made. These models largely depend on the orientation of the magnetic field in the magnetosheath close to the magnetopause, such as the Maximum Magnetic Shear model (Trattner et al 2007). Therefore understanding how it  is structured as a function of the solar wind and interplanetary magnetic field is of pivotal importance. Machine learning was used to collect around 45 million measurements in the magnetosheath at 5s resolution in all available Cluster, MMS, Double Star, THEMIS dataset, and to build detailed maps of the field structure in that region as a function of the IMF orientation. It allowed us to reconstruct for the first time the three dimensional magnetic field draping in the dayside magnetosheath from in-situ data only. Our results reveal how the frozen-in condition constrains the draping around the magnetopause. A comparison of the draping obtained with in-situ data with the one from a widely used magnetostatic model (Kobel et al 1994) was made. Differences of up to 180° were found for cone angle between 12.5° and 45°, for which the consequences regarding the position of the X-line will be discussed. 

 
Challenges in modelling radionuclide transport in the German nuclear waste repository search
Authors: Behrens Christoph , Luijendijk Elco , Kreye Phillip , Panitz Florian , Bjorge Merle , Gelleszun Marlene , Renz Alexander , Miro Shorash , Rühaak Wolfram
Published: March 2022

The current phase of the site selection procedure for a high-level nuclear waste repository in Germany includes representative preliminary safety assessments of potential suitable areas that cover approximately half of the territory of Germany. These safety assessments rely in part on numerical models of radionuclide transport. The modelling of radionuclide transport faces several challenges: 1) Estimation of radionuclide transport for a large set of potentially suitable areas with different hydrogeological settings and 2) scarcity of site-specific hydrogeological data for the parameters that govern radionuclide transport. To overcome these challenges we discuss potential workflows that combine the analysis of hydrogeological data and numerical models of radionuclide transport. We introduce a suite of numerical model codes that combines computationally efficient one-dimensional codes with more computationally demanding 2D and 3D codes. The 2D and 3D codes will be employed to simulate regional groundwater flow fields. These are subsequently combined with large sets of 1D model runs to quantify the effects of parameter variation and future geological developments on radionuclide transport. We discuss methods to combine site-specific data with global data to constrain the bandwidths of hydrogeological parameters and the range of radionuclide transport. Our contribution aims for an open discussion of model strategy and exchange with the scientific community.
Hotspots of Changes in Exposure to Multivariate Extremes at Different Global Warming Levels
Authors: Batibeniz Fulden , Hauser Mathias , Seneviratne Sonia Isabelle
Published: March 2022

It is now certain that human-induced climate change is increasing the frequency, intensity, and spatial extent of climate and weather extremes globally. While a number of studies investigated these characteristics of individual extremes, an IPCC risk framework-like holistic approach introducing the potential impacts of the changes in concurrent and multivariate extremes is more informative. By using CMIP6 climate projections, historical and future population estimates we assess the influence of human and climate change on four concurrent extreme events (heatwave–drought, warm nights–high relative humidity, extreme 1-day precipitation–wind, drought–warm days-low relative humidity) in the preindustrial period (1850-1900) and at four global warming levels (GWLs from +1 °C to +3 °C). Our results show that concurrent occurrences of the investigated extremes become 1.2 to 8 times more frequent for the 3ºC GWL. The most dramatic increase is identified for compound heatwave–drought events, with an eight-fold increase in subtropical countries, a seven-fold increase in northern middle and high latitude countries, and a five-fold increase in tropical countries, respectively. Additionally, the number of events per capita showing the contribution of climate change alone exhibits a dramatic increase in compound heatwave–drought and warm days–low relative humidity-drought events over the Mediterranean countries, Europe, China, Australia, Russia, the United States, and the Northern part of South America, emphasizing the potential risk increase in the case of lack of concerted effort to cut greenhouse gas emissions.
Inverse modelling of herbicide transport during transient flow in vegetated weighable lysimeters
Authors: Imig Anne , Augustin Lea , Groh Jannis , Pütz Thomas , Rein Arno
Published: March 2022

  

Metolachlor, terbuthylazine, nicosulfuron and prosulfuron are among the typical crop protection products used on maize plantations. Leaching of those lead to a decrease of groundwater and surface water quality. Often measured individual pesticides and their metabolite concentrations in drinking water are exceeding the limit established by the European Council in drinking water. In our work we investigate contamination potential of these four herbicides to groundwater bodies using lysimeter studies and numerical modelling with HYDRUS-1D. The four herbicides were applied at specific times in the vegetation phase over a period of three years on two lysimeters located in Wielenbach, Germany. The studied lysimeters contain soil cores dominated by sandy gravel (Ly1) and clayey sandy silt (Ly2) and are both vegetated with maize. To identify governing transport and fate processes in the unsaturated zone of the lysimeters and determining dynamics and rates of these, different model structural approaches were compared. In a first step we have characterized soil hydraulic and transport parameters of each soil core by investigating stable water isotopes (δ18O and δ2H). For Ly2, model performance was improved by considering immobile water in a dual-porosity approach whereas for Ly1 a single-porosity approached seemed to yield satisfying results. This might be explained by a higher fraction of fine particles in Ly2 which can be available for water storage. Based on these findings reactive transport parameters were fitted also for root water and chemical plant uptake, sorption, and biodegradation.

It was found that sorption plays a significant role in herbicide transport whereas root water uptake and chemical plant uptake is of minor influence. Metabolite formation was observed; however, biodegradation seems to show minor influence, only, which is also reflected by measured carbon isotopes (slight δ13C increase). Non-equilibrium and non-linear sorption were compared leading to no significant difference in model results. This was especially surprising for the charged herbicides prosulfuron and nicosulfuron. Measured herbicide concentration peaks in seepage water seemed to be connected in time with higher amounts of precipitation events indicating the influence of preferential flow. Such influences could be considered in a dual-permeability flow model setup which however was not available for stable water isotope modelling in HYDRUS-1D. Contrary to our expectations, the coarser soil of Ly1 did not lead to an increase in leached herbicides which might be explained by a higher organic matter content and thus higher sorption.

 
Quantifying the contributions of Pacific Plate motion change and hotspot drift to the formation of Hawaiian-Emperor Bend
Authors: Hu Jiashun , Gurnis Michael , Rudi Johann , Stadler Georg , Müller Dietmart , Zhang Jie
Published: March 2022

The Hawaiian-Emperor Seamount Chain changed its strike by 60° around 47 Ma, causing the Hawaiian-Emperor Bend (HEB). Both a change in Pacific Plate motion and a change in plume dynamics have been proposed to account for the HEB, but vigorous debates remain on their relative contribution. In order to have a better understanding, we build high–resolution global mantle convection models and test alternative plate reconstructions of North Pacific to quantify the contribution of each mechanism. For the contribution of Pacific Plate motion change, we find that Izanagi Plate subduction, followed by demise of the Izanagi–Pacific ridge and Izu–Bonin–Mariana subduction initiation alone, is incapable of causing a sudden change in plate motion, challenging the conventional hypothesis on the mechanisms of Pacific Plate motion change. Instead, with the alternative intra-oceanic subduction model, the Paleocene slab pull from Kronotsky subduction in North Pacific exerts a northward pull on the Pacific Plate, with its demise causing a sudden 30-35° change in plate motion. We further quantify the Hawaiian Hotspot drift using global mantle convection models with both the traditional and the alternative plate reconstructions. We find both models yield a fast southward drifting Hawaiian plume due to the push of slabs on the edge of the Pacific LLSVP. In the end, we discuss the combinational effects of Pacific Plate motion change and Hawaiian hotspot drift on the formation of HEB under different scenarios to gain insights on the possible history of North Pacific since the Late Cretaceous.
Retrieval of tropospheric NO2 columns from GEMS observations using the Sentinel-4 breadboard algorithm 
Authors: Richter Andreas , Lange Kezia , Boesch Tim , Zilker Bianca , Behrens Lisa , Burrows John P. , Kim Si-Wan , Seo Seunghwan , Kim Kyoung-Min , Hong Hyunkee , Lee Hanlim , Park Junsung
Published: March 2022

Nitrogen oxides (NOx) play an important role in tropospheric chemistry and are key pollutants in particular in industrialised regions. While some natural emission sources exist such as lightning and bacterial soil activities, anthropogenic emissions dominate, mainly from transport, energy production, heating and industrial sources. To better understand the role of nitrogen oxides in the troposphere and to monitor the effects of measures taken to reduce emissions, continuous and global measurements of NO2 abundances in the troposphere are needed.

Passive remote sensing of NO2 from space is possible as it has strong and structured absorption features in the UV and visible part of the solar spectrum. Global measurements of tropospheric NO2 have been achieved from a series of instruments including GOME, SCIAMACHY, GOME2, OMI and TROPOMI. While these data sets provide a wealth of information on NO2, they all are from satellites in sun-synchronous orbits and provide little insight into the diurnal evolution of NO2. This has changed with the launch of the Korean GEMS instrument that is the first to provide hourly NO2 measurements over Asia.

In this study, spectra from the GEMS instrument were analysed for tropospheric NO2 using the IUP-Bremen NO2 retrieval code developed as breadboard algorithm for the upcoming European geostationary instrument Sentinel-4. Very good agreement is found between GEMS and concurrent measurements from TROPOMI. Validation using ground based MAX-DOAS measurements in Incheon, Republic of Korea during the GMAP-2021 campaign shows good correlation but a systematic underestimation, similar to what is reported for TROPOMI data. A number of sensitivity studies have been performed to explore the changes of the retrievals when using different stratospheric correction schemes, different a priori NO2 profiles, and different surface reflectivity assumptions. The results will be presented and discussed, in particular in view of their impact on the diurnal variations retrieved for NO2 over different cities in Asia.
Late Holocene sea-level change in southern New Zealand 
Authors: Garrett Ed , Gehrels Roland , Hayward Bruce , Newnham Rewi , Gehrels Maria , Morey Craig , Dangendorf Sonke
Published: March 2022

We present new proxy-based sea-level reconstructions for southern New Zealand spanning the last millennium. These palaeo sea-level records usefully complement sparse Southern Hemisphere proxy and tide-gauge sea-level datasets and, in combination with instrumental observations, can test hypotheses about the drivers of 20th century global sea-level change, including land-based ice melt and regional sterodynamics. We develop sea-level transfer functions from regional datasets of salt-marsh foraminifera to establish a new proxy-based sea-level record at Mokomoko Inlet, at the southern tip of the South Island, and to improve the previously published sea-level reconstruction at Pounawea, located about 110 km to the east. Chronologies are based on radiocarbon, radiocaesium, stable lead isotope and pollen analyses. Both records are in good agreement and show sea level several decimetres below present over the last millennium, before a rapid sea-level rise in the first half of the 20th century that reached maximum rates in the 1940s. Previously reported discrepancies between proxy-based sea-level records and tide-gauge records are partially reconciled by accounting for barystatic and sterodynamic components of regional sea-level rise. We conclude that the rapid sea-level rise during the middle 20th century along the coast of southern New Zealand was primarily driven by regional thermal expansion and ocean dynamics.
Bacterial abundance, growth and community composition in oligotrophic, metal-rich running waters of Southern New Caledonia
Authors: Weinbauer Markus , Motegi Chiaki , Migon Christophe , Mari Xavier
Published: March 2022

The basic bacterial ecology and diversity was investigated in five running water systems of Southern New Caledonia (including a former Cr/Co mine). These running waters were characterized by potential P-limitation and high concentrations of Ni, Fe, Mn, Cr and Co. The low concentrations of dissolved organic carbon, bacterial and viral abundance, bacterial production and growth efficiency support the characterization of the running waters as oligotroph to ultraoligotroph. Despite these similarities, there were strong differences (<50% similarity) in bacterial community composition between some habitats based on 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) fingerprints (e.g. the Cr/Co) mine). The high coverage of sequenced DGGE bands found for Betaproteobacteria is typical for freshwater systems, however, we found also a strong representation of Gammaproteobacteria. Indeed the three bands found at all stations were related to Limnohabitans (Comamonadaceae) and Alteromonadaceae. Strong differences were also found between the free-living and the attached bacterial fraction with Gammaproteobacteria dominating in two systems. A higher representation of Gammaproteobacteria seems typical for metal-rich freshwater habitats. Consistent with fresh water habitats, majority of phylotypes detected in the sediment was affiliated to proteobacteria. Also, none of the sequences showed a 100% identity with data bases, and 10 of the 22 and 2 of the 23 sequences had similarities higher than 97% in the freshwater and sediment. This could indicate specific adaptations of the community composition either due to the high metal concentrations or due to the geographical isolation of the New Caledonia. 
Halogens in sub-Antarctic ice cores modulated by wind forcing, sea ice and primary productivity
Authors: Segato Delia , Thomas Elizabeth R. , King Amy , Tetzner Dieter , Moser Dorothea Elisabeth , Turetta Clara , Saiz-Lopez Alfonso , Markle Bradley , Pedro Joel , Spolaor Andrea
Published: March 2022

Over the last four decades, the Southern Ocean has been characterized by now-persistent stronger westerly winds, with consequences for the Antarctic region climate, including variations in sea ice extent and primary productivity. Here we present the first ever bromine, sodium and iodine records, tracers of sea salt aerosols, sea ice and primary productivity, from five sub-Antarctic ice cores, retrieved from Bouvet, Young, Peter I and Mount Siple Island and Mertz glacier. The aim of the study is (1) to assess if halogens deposited in sub-Antarctic regions are influenced by recent changes in wind forcing and (2) to better understand the underlying processes of halogens emission from ocean/sea ice, their transport and deposition over the Antarctic region.

The trends of sodium and bromine, emitted and transported with sea salt aerosols, suggest that wind strengthening leads to more halogens deposited in the sub-Antarctic. Also, we find that bromine is depleted with respect to the bromine-to-sodium sea-water ratio at all sites, indicating that bromine species are sustained in the marine boundary layer by halogen chemistry and are less prone to be deposited. Iodine records show a positive correlation with marginal sea ice and primary productivity variability, suggesting that iodine species emitted at the edge are deposited more efficiently than bromine species.
Characteristics of Fragmented Aurora-like Emissions (FAEs)
Authors: Dreyer Joshua , Partamies Noora , Whiter Daniel , Ellingsen Pål G. , Baddeley Lisa , Buchert Stephan C.
Published: March 2022

We present observations of a new type of small-scale aurora-like feature, which is further referred to as fragmented aurora-like emission(s) (FAEs).

They seem to appear in two categories – randomly occurring individual FAEs and wave-like structures with regular spacing between FAEs alongside auroral arcs. FAEs show horizontal sizes typically below 20 km, a lack of field-aligned emission extent, and short lifetimes of less than a minute. Emissions were observed at the 557.7 nm line of atomic oxygen and at 673.0 nm (N2; first positive band system) but not at the 427.8 nm emission of <span tabindex="0" role="presentation" data-mathml='N2+'>N2+ or the 777.4 nm line of atomic oxygen. This suggests an upper limit to the energy that can be produced by the generating mechanism. Their lack of field-aligned extent and 777.4 nm emissions indicates a different generation mechanism than for aurorae, which are caused by particle precipitation. Possible sources are Farley–Buneman instabilities or electrostatic ion cyclotron waves.
Model error correction with data assimilation and machine learning
Authors: Farchi Alban , Bocquet Marc , Laloyaux Patrick , Bonavita Massimo , Chrust Marcin , Malartic Quentin
Published: March 2022

The idea of using machine learning (ML) methods to reconstruct the dynamics of a system is the topic of recent studies in the geosciences in which the key output is a surrogate model meant to emulate the dynamical model. In order to treat sparse and noisy observations in a rigorous way, ML can be combined with data assimilation (DA). This yields a class of iterative methods in which, at each iteration a DA step estimates the system's state, and alternates with a ML step to learn the system's dynamics from the DA analysis.

This framework can be used to correct the error of an existent, physical model. The resulting surrogate model is hybrid, with a physical and a statistical part. In practice, the correction can be added as an integrated term (i.e. in the model resolvent) or directly inside the tendencies of the physical model. The resolvent correction is easy to implement but is not suited for short-term predictions. The tendency correction is more technical since it requires the adjoint of the physical model, but also more flexible and can be used for any forecast lead time.

In this presentation, we start by a proof of concept for the use of joint DA and ML tools to correct model error. We use the resolvent correction with simple neural networks to correct the error of a two-dimensional, two layer quasi-geostrophic layer. The difference between the resolvent and the tendency correction is then illustrated with the two- scale Lorenz model. Finally, we show that the tendency correction opens the possibility to make online model error correction, i.e. improving the model progressively as new observations become available. We compare online and offline learning using the same twin experiment with the two-scale Lorenz model.

 
Validation of profile probe for measurement of soil moisture in an Internet of Things system
Authors: Wilczek Andrzej , Kafarski Marcin , Majcher Jacek , Szypłowska Agnieszka , Lewandowski Arkadiusz , Skierucha Wojciech
Published: March 2022

The study of water transport in the vadose zone is difficult to describe because of the variety of phenomena determining changes in soil moisture. A profile probe can be a tool that can help in the analysis of topsoil moisture. However, in order to analyse phenomena at different scales, it is necessary to integrate many probes in one system.

The aim of this work was to develop a solution to collect soil moisture and temperature data and visualise them in a user-friendly way. The use of cloud technologies and the Internet of Things IoT provided easy integration to enable further scaling of similar solutions. The developed solution based on TDR probes and the PTDT profile probe allowed the collection of data for analysis for over a year. Tests indicate that the system can be used to study water transport (dynamic moisture changes) associated with precipitation, evaporation or capillary rise. Additional temperature analysis allows the determination of soil frost depth. The current deepening water deficit and intensifying climate change indicate the need to accelerate work related to the implementation of such soil moisture monitoring systems.

Acknowledgments: The research was supported by the Polish National Agency for Academic Exchange under Grant no. PPI/APM/2018/1/00048/U/001.