bluuebunny/crossref_metadata_2025 huggingface dataset:
Drone-based electromagnetic survey system for environmental applications
Authors: Pirttijärvi Markku , Korkeakangas Pekka
Published: February 2023

During the last few years, the number of applications utilizing unoccupied aerial vehicles (UAVs), or drones, has increased rapidly in geophysics. The main benefits of airborne surveys are the ability to avoid terrain obstacles such as lakes, rivers, swamps, and ravines and the ability to collect evenly sampled data over large areas quickly. Drone surveys are safer and more cost-effective than ground surveys, especially in rough terrain. Compared to manned aircrafts, drones are cheaper to acquire and to operate. Drones are also versatile, fast to deploy, and ecologically more friendly.Presently, drones are commonly used for magnetic surveying, and in addition to normal photogrammetry, drones are also used for multispectral and thermal imaging. Electromagnetic (EM), radiometric and gravity applications have been scarce, because the instruments are heavy compared to the modest payload of reasonable priced drones. Special adaptation or completely new instrumentation is needed to enable more drone applications.Radai is a private Finnish company specialized in drone-based geophysical and environmental surveys. For the last five years Radai have been developing Louhi – a frequency-domain electro­magnetic (EM) system that is lightweight enough to be operated by drones. Presently, Louhi is operated using a large (Ø 100 m) ground loop as the EM source and a standalone 3-component EM receiver is towed by a VTOL (vertical take-off and landing) drone. Radai also develops a fully airborne system where a smaller transmitter loop (Ø 1 m) is fixed to the drone and receiver is towed either by the same drone or by a second drone that flies in tandem with the first one. The applications of the new EM system include geological mapping, mineral exploration, groundwater and geotechnical investigations and environmental monitoring. This paper gives details of the drone-based Louhi EM system and shows results from the first environmental survey made over a tailings pond dam of closed Pyhäsalmi Zn-Cu mine in Finland. The work is made as a part of EU Horizon 2020 funded Goldeneye project.
Geostatistical analysis of groundwater data in a mining area
Authors: Varouchakis Emmanouil , Diamantopoulou Evgenia , Pavlides Andreas
Published: February 2023

Geostatistical methods are increasingly used in earth sciences and engineering to improve space and time predictions. During mining activities, it is essential to monitor contaminant concentrations in soil and groundwater and estimate their spatial distribution in the area to guide environmental monitoring and reclamation once mining operations have been finished. In this work, we present the geostatistical analysis of the groundwater content in certain pollutants (Cd and Mn) in a group of adjacent mines. The available monitoring locations were Sixty-two. The challenge in this work is the grouped location of monitoring stations within the borders of the adjacent mines. This work aims to map the spatial distribution of Cd and Mn concentrations in groundwater in the entire mining area. The Correlation between Cd and Mn was investigated during the preliminary analysis of the data and found significant. The logarithm of the data values was used, and after removing a linear trend, the variogram parameters by means of a spherical model were estimated. In order to create the necessary contaminants concentration maps, we employed the Ordinary Kriging (OK) method and inversed the transformations. Cross-validation shows promising results (ρ = 92% for Cd and ρ = 88% for Mn, RMSE = 5.1 ppm for Cd and RMSE = 18.2 ppm for Mn), while the uncertainty was calculated in acceptable bounds.
Structural analysis and tectonic evolution of the El Bolon and Bateig secondary minibasins in the Eastern External Betics (Betic fold-and-thrust belt—Iberian Peninsula)
Authors: Canova David P. , Naim Zeina , Roca Eduard , Ferrer Oriol , Escosa Frederic O. , Garcia-Sellés David
Published: February 2023

The Eastern External Betics correspond to the external part of the Betic fold-and-thrust belt that crops out in the Valencia and Alicante provinces. It mainly consists of a system of ENE-trending cover folds and thrust sheets detached in the Triassic salt along with a significant amount of diapirs and allochthonous sheets made by this salt. Most primary diapirs formed during the extensional evolution of the southern Iberian passive margin during Jurassic to early Santonian time. These diapirs were later shortened and squeezed forming syn-contractional salt sheets and secondary minibasins during the Africa/Eurasia convergence that, beginning at late Santonian times, led to the formation of the Pyrenean and Betic orogens.Based on detailed stratigraphic analysis, structural field mapping, fracture analysis, and by comparison with other salt-bearing fold-and-thrust belts we revisit one of the major allochthonous salt sheets of the area, the Elda salt sheet, to reinterpret its structural evolution. The Elda salt sheet includes fragments of the feeding diapir roof as well as secondary minibasins made by late Santonian to middle Miocene syn-contractional sediments and it is covered by upper Miocene to Pliocene post-contractional deposits.This presentation will focus on the evolution of the El Bolon and Bateig secondary minibasins. El Bolon minibasin is characterized by a basal section comprising Late Cretaceous (Senonian) marls that correspond to the carapace above a diapir. The Senonian sequence is conformably overlain by Paleocene-Eocene siliciclastics that are characterized by a series of syn-sedimentary normal faults that sole into the salt with significant variations in thickness throughout the minibasin. In Oligocene times, coeval with the onset of the Betic Orogeny, renewed diapirism resulted in the extrusion of allochthonous salt and dismembered the diapiric roof. Diapir derived detritus (Jacintos de Compostella) in the Oligocene-Miocene sequence indicate that allochthonous salt was exposed at the surface while El Bolon minibasin continued to passively grow. Throughout the Early to Middle Miocene El Bolon minibasin developed hook halokinetic sequences and episodic unconformities with onlaps recording the progressive rotation of the minibasin. By the end of the Middle Miocene the whole minibasin was completely encased in salt. Coeval to or shortly after the encasement of the El Bolón minibasin the Bateig minibasin, comprising Miocene calcarenites and siliciclastics, began to subside into the allochthonous sheet. Continued shortening due to the Betic Orogeny further rotated the El Bolón minibasin around a horizontal axis to its present position (vertical to overturned) contemporaneous with the southward tilting and partial encasement of the Bateig minibasin.
The Sea Ice Drift Forecast Experiment (SIDFEx): Introduction and applications
Authors: Ludwig Valentin , Gößling Helge ,   SIDFEx Team
Published: February 2023

We introduce the Sea Ice Drift Forecast Experiment (SIDFEx) database. SIDFEx is a collection of close to 180,000 lagrangian drift forecasts for the trajectories of specified assets (mostly buoys) on the Arctic and Antarctic sea ice, at lead times from daily to seasonal scale and mostly daily resolution. The forecasts are based on systems with varying degrees of complexity, ranging from free-drift forecasts to forecasts by fully coupled dynamical general circulation models. Combining several independent forecasts allows us to construct a best-guess consensus forecast, with a seamless transition from systems with lead times of up to 10 days to systems with seasonal lead times. The forecasts are generated by 13 research groups using 23 distinct forecasting systems and sent operationally to the Alfred-Wegener-Institute, where they are archived and evaluated. Many systems send forecasts in near-real time.One key purpose when starting SIDFEx in 2017 was to find the optimal starting position for the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC). Over the years, more applications evolved: During MOSAiC, the SIDFEx forecasts were used for ordering high-resolution TerraSAR-X images in advance, with a hit rate of 80%. During the Endurance22 expedition, we supported the onboard team with near-real time forecasts, contributing to the success of the mission. Currently, we evaluate drift forecasts for several buoys of the MOSAiC Distributed Network (DN). We know that there is skill in predicting the location of single buoys. Now, we extend this to studying the deformation of the polygon spanned by the DN buoys. Deformation is derived from the spatial velocity derivatives of the buoy array. We find low correlation coefficients between the deformation in the models and the observed deformation for a small-scale DN configuration, but larger and significant correlations around 0.7 for larger configurations and an Arctic-wide buoy array.
Representation of tropical SST trends in ECMWF seasonal hindcasts and implications for recent ENSO forecasts
Authors: Mayer Michael , Alonso Balmaseda Magdalena , Tietsche Steffen
Published: February 2023

Operational seasonal forecasts are routinely issued with their bias removed, which is estimated from hindcasts covering a sufficiently long period. An increased number of false alarms for the occurrence of El Nino by various dynamical forecasting systems in recent years challenges the view that forecast biases are stationary. Here we assess the ability of ECMWF’s operational seasonal prediction system SEAS5 to represent observed trends in tropical SSTs since 1993, with a focus on the Pacific.SEAS5 hindcasts overestimate SST warming in the equatorial Pacific when compared to observations. Although present for all start dates, the trend error is most pronounced for May starts. As a result, SEAS5 forecasts in recent years tended to predict too warm ENSO states despite bias correction. The hindcasts also fail to reproduce the observed meridional dipole in SST trends in the eastern Pacific, with warming in the northern and cooling in the southern subtropics. We assess several numerical experiments to investigate the role of the evolving ocean observing system, the ocean data assimilation system, and the atmospheric model. Results show that the increase in Argo observations amplifies the spurious trends in the hindcasts, which points to biases in the ocean initial conditions when observational constraints are lacking prior to Argo. Furthermore, observed-SST experiments show that the atmospheric model is unable to reproduce the magnitude of increasingly northward winds that are observed in the eastern equatorial Pacific, which are associated with the meridional structure of observed SST trends and have been speculated to reduce ENSO variability. This suggests that shortcomings of the atmospheric model physics further contribute to the system’s inability to predict the recent triple La Nina period. The results call for more sophisticated calibration methods of seasonal forecasts and ultimately improved models and initialization to provide more reliable ENSO forecasts under varying background conditions.
A multidisciplinary approach to constrain hydrothermal alteration history on Mt Ruapehu (New Zealand)
Authors: Kereszturi Gabor , Álvarez-Valero Antonio M. , D'Mello Nessa , Miller Craig , Coulthard Jr Daniel A.
Published: February 2023

Composite volcanoes can progressively weaken through hydrothermal alteration, which may lead to volcano collapse, forming far-reaching debris avalanches. Hydrothermal minerals can also contribute to flank instability as they play a critical role in moderating volcanic degassing by changing the porosity and permeability of the rock and thereby changing the local pore-pressure distribution. Therefore, a robust model and understanding of hydrothermal alteration within a volcanic edifice is important to improve hazard assessment efforts. This study investigates the type and extent of hydrothermal alteration on Mt Ruapehu, New Zealand, using a combination of mineralogical, hyperspectral imaging, and aero-magnetic studies.Mt Ruapehu shows a diverse suite of surface weathering and hydrothermal alteration minerals, which are distributed heterogeneously on the surface. The surface weathering has abundant goethite, hematite and phyllosilicate mineral associations, while the hydrothermal alteration is characterised by phyllosilicates, Fe-oxides, pyrite, jarosite, alunite, gypsum anhydrite, and native sulphur minerals. Although surficial evidence of alteration on Mt Ruapehu is limited, aero-magnetic data and inversion modelling indicate deep-seated (≤500 m) alteration of demagnetized rocks. The decrease of magnetic susceptibility can be linked to the dissolution of (Ti-) magnetite phases, as well as the deposition of brecciated horizons between lava flows and intercalated glacial till and volcaniclastics. Surface outcrops mapped by airborne hyperspectral imaging combined with Scanning Electron Microscopy (SEM-EDS), Short wavelength Infrared (SWIR) Spectroscopy, X-Ray Diffraction and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) data of ground samples reveal a complex alteration history developed around older vent/crater systems of Mt. Ruapehu in last 250 ky. This study provides a simplified geological model to capture the hydrothermal processes on Mt Ruapehu, aiding future studies on delineating areas prone to mass movements.
Searching for the VHF signature of the tip of an intra-cloud positive leader
Authors: Scholten Olaf , Hare Brian , Dwyer Joe , Liu Ningyu , Sterpka Christopher
Published: February 2023

We have used the LOw-Frequency ARray (LOFAR) to search for the growing tip of an intra-cloud (IC) positive leader. LOFAR is an extended astronomical radio telescope consisting of many (thousands antennas arranged is stations operating at very-high frequencies (VHF). For these lightning observations we have used about 170 dual polarized antennas in the Netherlands with baselines up to 100 km.  Even with our most sensitive beamforming method, where we coherently add the signals of all 170 antenna pairs, we were not able to detect any emission from the tip of an IC positive leader. Instead, we put constraints on the emissivity of VHF radiation from the tip at 1 aJ/MHz at 60 MHz, well below the intensity of the galactic background.We conclude that these IC positive leaders propagate in a continuous process which is in sharp contrast to what is seen to the step-wise propagation seen in some cloud-to-ground positive leaders and for negative leaders.
Impact of groundwater pumping on river flow
Authors: de Graaf Inge
Published: February 2023

In many regions of the world more groundwater is used than recharged by precipitation or infiltrating river water. While overuse of groundwater can have a variety of undesirable effects, among the most immediate and visible effects are reduction of river flows and the impact on freshwater ecosystems can be devastating.In an alluvial aquifer, groundwater pumping can reduce the flow of water in a river in two ways: 1) pumping can intercept water that would otherwise discharge into the river; 2) pumping draws groundwater levels down below the level of the river and river water will infiltrate. In this study the impacts of groundwater pumping on river flow are estimated using a coupled global-scale groundwater-surface water model. Results show that nearly half of the pumped groundwater reduces river flow. Globally, approximately 20% of the pumped groundwater comes from increased river capture and 16% from a reduction in storage (averaged over the model period 1960-2010). Critical thresholds for groundwater discharge to support ecological integrity have already been crossed due to groundwater pumping in 15-21% of all river basins and are likely to be crossed in more than half of all river basins by 2050.
A method for estimating localized CO2 emissions from co-located satellite XCO2 and NO2 images
Authors: Fuentes Andrade Blanca , Reuter Maximilian , Buchwitz Michael , Bovensmann Heinrich , Burrows John P.
Published: February 2023

CO2 emissions need to be rapidly reduced in order to peak greenhouse gas emissions and limit global warming to well below 2ºC. Most of these anthropogenic CO2 emissions result from the combustion of fossil fuels from localized sources. Therefore, it is essential to monitor these emissions to corroborate the compliance with the objectives of the Paris Agreement. Under this agreement, the parties report their national greenhouse gas inventories, usually computed using bottom-up methods based on statistical activity data and emission factors. Top-down approaches, based on atmospheric observations, can complement and verify these inventories. Satellite-based observations have the advantage of potential global coverage and the feasibility of providing independent emission estimates from localized sources, like cities and power plants.In this study we present a top-down method to quantify the CO2 emissions from localized sources by using XCO2 (the column-averaged dry-air mole fraction of CO2) retrievals from the Orbiting Carbon Observatory 3 (OCO-3) in its snapshot area mode. It is a cross-sectional flux method, so that our estimate of the source rate is obtained from the flux through a number of cross-sections downwind of the source.The detection of CO2 emission plumes is challenging due to the small enhancements resulting from anthropogenic emissions from individual source points compared to the background concentrations and the satellite’s instrument noise. NO2 is co-emitted with CO2 in the combustion of fossil fuels and its vertical column densities can exceed background values and sensor noise by orders of magnitude in emission plumes, what makes it a suitable tracer for recently emitted CO2. Therefore, our plume detection method uses TROPOMI NO2 data which is co-located with the XCO2 snapshot.We expose the CO2 emissions estimates for 7 overpasses over the Bełchatów power plant, in Poland, together with bottom-up emission estimates for comparison, showing that we can repeatedly monitor power plant CO2 emissions.
Multicriteria decision-making approach as a strategy to deal with land subsidence in affected areas
Authors: Pla Concepción , Valdes-Abellan Javier , Navarro-Hernandez Maria I. , Guardiola-Albert Carolina , Ezquerro Pablo , Bru Guadalupe , Elçi Alper , Meisina Claudia , Tomas Roberto
Published: February 2023

Unsustainable groundwater extraction may cause groundwater levels drawdown leading to compaction of the aquifer systems and causing the lowering of ground surface, i.e., land subsidence. Thus, to prevent from land subsidence caused by the overexploitation of aquifer systems it is essential avoiding the unsustainable decline of groundwater levels. An effective policy to mitigate land-subsidence should include systematic monitoring and modelling of groundwater bodies in exposed areas, evaluation of potential damages, and cost-benefit analyses permitting the implementation of adequate mitigation or adaptation measures. Among others, these measures should consider groundwater regulation and strategic long-term measures, such as the development of alternative water supplies, the introduction of changes and reallocation of water demands in the different sectors, or the implementation of severe legal control related to water uses.The RESERVOIR project (PRIMA Foundation) aims to provide new products and services for a sustainable groundwater management model. Within this global aim, one specific task of the project focuses on the establishment of good management practices related to groundwater uses in areas affected by land subsidence.In this study, a multicriteria decision-making approach is suggested to evaluate the potential possibilities and different scenarios for subsidence mitigation in the affected areas. This methodology is based on the analytical hierarchical process (AHP), an easy-to-use procedure which allows individual and group decisions. The procedure, which has been applied to multiple real-life scenarios, requires the evaluation of various criteria and sub-criteria by assigning them relative weightings to finally choice between a set of alternatives.The methodology is proposed as a tool to evaluate the different possibilities to deal with subsidence in the affected areas and might be particularized by selecting the criterions to be considered (for instance, environmental, economic, social, technical, or legal, among others) in order to group the different sub-criteria to be evaluated and weighted. This tool can be particularly applied to different areas. In addition, based on the final purpose, different agents (technicians, stakeholders, farmers, businessman, general population, etc.) can contribute to obtain the results and final conclusions of the analysis.This study has been carried out in the framework of the RESERVOIR project (sustainable groundwater RESources managEment by integrating eaRth observation deriVed monitoring and flOw modelIng Results), funded by the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) programme supported by the European Union (G. A. Nº 1924).
Mapping spatial and vertical repartitions of soil carbon stocks, additional storage potential and storage dynamics at the regional scale
Authors: Derrien Delphine , Chirol Clémentine , Saint-André Laurent , Séré Geoffroy
Published: February 2023

Soils constitute a carbon reservoir that can help to mitigate climate change, or conversely accelerate greenhouse gas emissions if not managed properly. Soils are heterogenous and dynamic systems, which physico-chemical properties impact their current soil organic carbon (SOC) stocks and their capacity to store more carbon. Land-use planning aiming to preserve and increase SOC stocks should therefore be aware of the spatial repartition of various soil types and of the SOC dynamics therein.
This project aims to map the effect of soil typology on the spatial and vertical repartition of soil carbon stocks, additional storage potential and storage dynamics at a regional scale to improve guidance of SOC storage strategies. The study site is a 320 km2 temperate rural region in NE France. Eight dominant soil types are defined, notably Calcaric cambisols in the agricultural valleys, deep silty and acidic soils in the forested plateaus, shallow rocky calcaric soils on the hillslopes, and deep clay-rich hydromorphic soils in the alluvial valleys.  
Based on logarithmic fits of soil carbon data extracted from 197 full-depth soil profiles, mean soil organic carbon stocks are obtained as a function of depth for each represented soil type and land cover. The additional storage potential corresponds to the difference between the current stock and the maximum stock, as estimated by the fit of the upper 25% of the soil carbon content data.  Finally, a depth-dependent SOC dynamic model using multilayer soil modules is used to simulate SOC stock evolution. Results are mapped by combining the spatial information given by a pedological map and a map of land covers.
Median soil carbon stocks over the full soil profile range from 78 to 333 tC ha-1, of which 59 to 148 tC ha-1 are in the topsoil (0-30 cm). The lower stocks are found in the shallow, rocky cultivated soils, and the highest stocks in the gleysols under grasslands. The additional storage potential varies from 19 tC ha-1 for shallow, rocky forest soils to 197 tC ha-1 for cultivated gleysols. SOC build-up is heterogenous and depends on the mean residence time of carbon in the represented soil types.
Maps of carbon stocks show the areas to preserve to avoid C losses, and maps of additional storage capacity for different time horizons show areas in which to implement carbon storage practices. Going forward, the association of carbon stock mapping and modelling should allow us to estimate at which depths and over which timescales.
Tapered drip laterals and manifolds in flat and rectangular irrigation units
Authors: Palermo Salvatore Samuel , Baiamonte Giorgio
Published: February 2023

Multiple-diameter laterals and manifolds reduce the total cost in microirrigation systems, however, the length of each sublateral should be determined carefully to assure appropriate performance and uniformity of emitter flow rates. The most accurate method is numerical trial and error, which is time-consuming. Many research efforts have been made to propose simple analytical design procedures. By using the power-law form of the Darcy-Weisbach formula, and equal emitters spacing for the sublaterals, Sadeghi et al. (2016) extended a previously introduced design solution for one-diameter laterals to tapered laterals. Recently, a simplified procedure to design dual-diameter drip laterals has been introduced (Baiamonte and Palermo, 2022), providing relative errors in pressure heads less than 0.5%, and allowing to set different Hazen-Williams coefficients, flow rates, and emitter interspaces for each sublateral. Moreover, this analytical procedure easily allows the detection of the required commercial emitter characteristics. The objective of this work is to extend the aforementioned solution to rectangular irrigation units laid on flat fields. 
Equitable Letters for Space Physics
Authors: Halford Alexa , Burrell Angeline , Jones McArthur , Coxon John , Zawdie Kate
Published: February 2023

 Equitable Letters in Space Physics (ELSP) is an organization that aims to encourage merit-based recommendations and nominations in the space physics community by providing resources and reviews. Recommendation and award nomination letters are a known source of bias that affect education and job opportunities, career progression, and recognition for scientists from underrepresented backgrounds. ELSP was founded to mitigate this bias within the current system by providing a proof-reading service that focuses on identifying phrasing and structure within letters that unintentionally undermines the purpose of the recommendation or nomination. If you are writing a recommendation letter for someone you know professionally, you can send it to us and we will send it out to our reviewers. They will provide recommendations on how you can make your letter more equitable and less biased, using a combination of the techniques and resources described on our site, with the aim to make unbiased recommendation letters more accessible to all. If you are interested in being a reviewer or having your writing reviewed, please reach out to us. We're a relatively young initiative and are keen to engage with and involve many diverse voices. Our website with more information, sample letters, and other resources can be found at https://equitableletterssp.github.io/ELSP/
Global Layer——An integrated, fully online, cloud based platform
Authors: Yang Xingchen , Song Yang , Wu Zhenhan , Wu Chaowei
Published: February 2023

In the current stage of scientific research, it is necessary to break the barriers between traditional disciplines and promote the cross integration of various related disciplines. As one of the important carriers of research achievements of various disciplines, maps can be superimposed and integrated to more intuitively display the results of multidisciplinary integration, promote the integration of disciplines and discover new scientific problems. Traditional geological mapping is often based on different scales for single scale mapping, aiming at the mapping mode of paper printing results. It is difficult to read maps between different scales at the same time. To solve this problem，an integrated platform named Global Layer is being built under the support of Deep-time Digital Earth (DDE). Global Layer is embedded with several core databases such as Geological Map of the World at a scale 1/5M, Global Geothermal Database etc. These databases presented in form of electronic map which enables the results of different scales to be displayed and browsed through one-stop hierarchical promotion. In addition, Users can also upload data in four ways: local file, database connection, cloud file and arcgis data service, and data or maping results can be shared to Facebook, Twitter and other platforms in the form of links, widgets, etc. Construction of Global Layer could provide experience and foundation for integrating global databases related to geological map and constructing data platforms.
GeoLatinas beyond earth sciences: for an equitable, inclusive, and diverse planetary and space science
Authors: Gonzalez Arismendi Gabriela , Guerra Clairet , Nowajewski-Barra Priscilla , Carvajal-Chitty Humberto
Published: February 2023

GeoLatinas in Space is an initiative that fosters scientific literacy in an inclusive environment. For decades access to space-related formation has been precluded to social advantage groups. Minorities have faced low visibility of role models in leadership positions, language barriers, lack of access to resources and information, and ultimately non-inclusive working spaces, resulting in an even more challenging environment. In light of current and historical social challenges that minorities face, GeoLatinas’ visionary purpose offers a platform that aims to empower Latinas in Earth and Planetary sciences. Our community intends to create an inclusive, safe space for scientists from different backgrounds to converge. The new space race is growing exponentially, and occupations in space are becoming more and more relevant. The technology revolution is already here, but it is still centered and constrained by linguistic restrictions. As the new space race gets underway, a need for scientifically competent individuals from other fields will also arise. To promote literacy and communication in planetary sciences, GeoLatinas in Space has established a community that encourages information sharing, makes it approachable, and assures that it is evenly circulated in multiple languages. By providing and expanding accessibility to space literacy content and encouraging the creation of professional profiles dedicated to space projects and the cosmos, our goal and efforts are focused on closing knowledge gaps in developing nations, particularly Latin America. By showing that space jobs are feasible today and accessible to those who are interested in pursuing them, we engage a broader audience and work to inspire younger generations.
What causes GPR signal scattering in temperate ice?
Authors: Ogier Christophe , Van Manen Dirk-Jan , Maurer Hansruedi , Hertrich Marian , Raess Ludovic , Bauder Andreas , Farinotti Daniel
Published: February 2023

Ground penetrating radar (GPR) has been extensively used in glaciology to characterize englacial and subglacial properties such as ice thickness, liquid water content or water drainage pathways. However, GPR radargrams in temperate ice often appear blurred by undesirable noise, mostly appearing as highly scattered signal and strong attenuation. It is often suggested that this noise originates from englacial water inclusions, since water and ice  have a large contrast in their di-electric permittivity. Here, we use the open-access software gprMax to forward-model a GPR signal in temperate ice and to quantitatively assess the role that water scatterers have as noise source. In particular, we explore how different liquid water contents (LWC) and water-inclusions size affect the GPR signal, and show that their effect is much larger than the potential presence of a wet snowpack or a heterogenous distribution of ice permittivity. This confirms previous hypotheses suggesting that water inclusions within the ice are the main factor for the typical noise seen in GPR data for temperate ice. For simulations referring to 25 MHz GPR antennas, we find that a bulk LWC  equal or superior to 0.2 %, associated to decimeters-scale water inclusions, already constitute a limit in bedrock detectability for ice thicknesses larger than 100 m. These values of LWC and water-inclusion size are typical for Alpine field settings, clarifying why noisy signals are often encountered in such environments. Our numerical simulations for different LWC values also suggest than distinguishing between cold and temperate ice based on GPR scattering might be more difficult than previously assumed.
The influence of synoptic-scale processes on the paired H2O–O3 distribution in the UTLS: case study of a North Atlantic jet stream
Authors: Schäfler Andreas , Sprenger Michael , Wernli Heini , Fix Andreas , Wirth Martin
Published: February 2023

The distribution of H2O and O3 in the midlatitude UTLS is of key relevance for the Earth’s weather and climate. Tropospheric and stratospheric dynamical processes, acting on different time-scales, interact with chemistry and determine the composition of the UTLS and the extratropical transition layer (ExTL) therein. In this study, we investigate how strongly the fine-scale trace gas distribution in the UTLS/ExTL is related to interacting, tropospheric weather systems on synoptic time scales, which shape transport and mixing.We present range-resolved, collocated lidar H2O and O3 measurements from a research flight during the Wave-driven ISentropic Exchange (WISE) campaign, which was conducted across a jet stream located over the eastern North Atlantic on 1 October 2017. The observations are combined with 10-day backward trajectories along which meteorological parameters and turbulence diagnostics are traced. The derived transport and mixing characteristics are projected to the vertical cross sections of the lidar measurements and to the H2O–O3 phase space (Tracer-Tracer space) to explore linkages with the evolution of synoptic-scale weather systems and their interaction.We find that the formation of H2O and O3 filaments in the troposphere and stratosphere, the high variability of tropospheric H2O and the formation of the ExTL mixing layer can, to a large extent, be explained by transport and mixing associated with interacting tropical, midlatitude and arctic weather systems in the region of the jet stream on synoptic time scales. The mixed ExTL air exhibits a strong influence of turbulent mixing in the jet stream during the two days before the flight. The diagnosed non-local and transient character of mixing points to the complexity of the formation and interpretation of mixing lines in T–T space. The presented work is accepted for publication in ACP:Schäfler, A., Sprenger, M., Wernli, H., Fix, A., and Wirth, M.: Case study on the influence of synoptic-scale processes on the paired H2O-O3 distribution in the UTLS across a North Atlantic jet stream, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2022-692, accepted, 2022. 
Slab to back-arc to arc: fluid and melt pathways through the mantle wedge beneath the Lesser Antilles
Authors: Hicks Stephen , Bie Lidong , Rychert Catherine , Harmon Nicholas , Goes Saskia , Rietbrock Andreas , Wei Songqiao , Collier Jenny , Henstock Timothy , Lynch Lloyd , Prytulak Julie , Macpherson Colin , Schlaphorst David , Wilkinson Jamie , Blundy Jonathan , Cooper George , Davy Richard , Kendall John-Michael
Published: February 2023

Volatiles expelled from subducted plates promote melting of the overlying warm mantle, feeding arc volcanism. However, debates continue over the factors controlling melt generation and transport and how these determine the placement of volcanoes. To broaden our synoptic view of these fundamental mantle wedge processes, we image seismic attenuation beneath the Lesser Antilles arc, an end-member system that slowly subducts old, tectonised lithosphere. Punctuated anomalies with high ratios of bulk-to-shear attenuation (Qκ-1/Qµ-1 > 0.6) and VP/VS (>1.83) lie 40 km above the slab, representing expelled fluids that are retained in a cold boundary layer, transporting fluids towards the back-arc. The strongest attenuation (1000/QS~20), characterising melt in warm mantle, lies beneath the back-arc, revealing how back-arc mantle feeds arc volcanoes. Melt ponds under the upper plate and percolates toward the arc along structures from earlier back-arc spreading, demonstrating how slab dehydration, upper plate properties, past tectonics, and resulting melt pathways collectively condition volcanism.
Trends of sea breezes over the Western Mediterranean basin,1981-2021: are they affected by large-scale atmosphericcirculation changes?
Authors: Bedoya-Valestt Shalenys , Azorin-Molina Cesar , Minola Lorenzo , Gimeno Luis , Andres-Martin Miguel
Published: February 2023

Western Mediterranean sea-breezes are becoming more frequent during winter and less frequent in summer. Further, observed trends in the mean wind speed show a weakening of the sea-breezes in all time scales. These changes could have direct implications for the air pollution dispersion in winter, or for the hydrologic cycle and desertification due to the sea-breeze thunderstorm losses in summer; among other environmental effects.  The drivers and physical mechanisms that underpin long-term sea-breeze changes are yet to be understood, but the response of the atmospheric circulation patterns to the anthropogenic driven warming might be one of the main triggers for the increased occurrence over the Western Mediterranean basin. Recent studies focused on the Eastern Iberian Peninsula suggest that more frequent anticyclonic circulations might be behind the increase of sea-breeze occurrence in winter. This work aims to advance on the likely causes driving sea-breeze changes by investigating their relationship with the Jenkinson and Collison weather type classification. To do so, we will analyze homogenized hourly wind speed data from 40 weather stations across the Western Mediterranean basin (i.e., Spain, France, Italy, Tunisia and Algeria) for 1981-2021. Sea-breeze episodes will be identified by applying a robust automated algorithm based on objective criteria considering the large- and local-scale conditions. The sign, magnitude and statistical significance of the trends in the occurrence, wind speed and gusts of Western Mediterranean sea-breezes will be quantified, as well as for the Jenkinson and Collison weather type regimes. Finally, we will estimate the relationship between these sea-breeze parameters and the synoptic weather classification. This study will provide new knowledge about the historical changes and multidecadal variability of sea-breezes across the Western Mediterranean basin and its response to global atmospheric circulation changes.
Protecting Coastal Communities from Sea Level Rise and Extreme Weather Events: An Analysis of Adaptation and Risk Reduction Measures
Authors: Okutan Pelin , Otay Emre
Published: February 2023

Coastal communities around the world are facing increasing risks of sea level rise and extreme weather events, including storm surges, coastal flooding, and erosion. These risks have the potential to devastate infrastructure, disrupt economies, and displace vulnerable populations. In order to protect these communities and reduce their vulnerability to these impacts, it is essential to understand the potential impacts of sea level rise and extreme weather events and to develop and implement effective adaptation and risk reduction measures. In this study, we aim to assess and mitigate coastal vulnerability to sea level rise and extreme weather events by exploring the use of tools such as sea level rise projections, storm surge modeling, and coastal erosion analysis to understand the potential impacts of climate change on coastal communities. We will evaluate the effectiveness of various adaptation and risk reduction measures, such as beach nourishment, sea walls, and managed retreats, in different coastal settings. Through this research, we hope to provide valuable insights and recommendations for policymakers, practitioners, and other stakeholders working to reduce the vulnerability of coastal communities to sea level rise and extreme weather events.
The UNIGRAZ ESA H-ESC tool “STEREO+CH” – upgrade and preparation for cycle 25
Authors: Milosic Daniel , Temmer Manuela
Published: February 2023

We present the ESA service STEREO+CH which forecasts the solar wind speed for Earth, based on persistence modeling from STEREO in situ measurements combined with multi-viewpoint EUV observational data. By comparing the fractional areas of coronal holes (CHs) extracted from EUV data of STEREO and SoHO/ SDO, we add an uncertainty level derived from changes in the CH areas, and apply those changes to the predicted solar wind speed profile at Earth (see Temmer, Hinterreiter, and Reiss, 2018). In principle, the service was developed to work with in situ and EUV data from the location behind Earth (e.g., future Vigil mission) providing a lead time of solar wind speed forecast for a couple of days. As STEREO-A will switch its location to ahead of Earth, we perform additional statistical studies and upgrade the service by adding co-latitude information of the CHs and dynamic thresholding for CH extraction to keep the performance level up. With that we make the ESA service ready for solar cycle 25.
Vegetation optical depth reveals changes in ecosystem-level water stress for global forests
Authors: Junttila Samuli , Descals Adrià , Filella Iolanda , Peñuelas Josep , Brandt Martin , Wigneron Jean-Pierre , Vastaranta Mikko
Published: February 2023

Plant water stress due to climate change is posing a threat to various ecosystem services such as carbon sequestration, food and wood production, and climate regulation. To address this issue, methods are needed to assess and monitor plant water stress at various spatial and temporal scales. Passive microwave emission observations from satellites have proven useful in monitoring changes in vegetation water content and assessing plant water stress at a low spatial resolution (> 9 km). In this study, we used vegetation optical depth (VOD) and measurements of hydraulic vulnerability to create a novel model for assessing ecosystem-level water stress. We used L-band VOD and global measurements of xylem water potential at 88% loss of stem hydraulic conductivity (P88) from the TRY database (including 1103 measurements of P88 from 463 species and nine different vegetation biomes) to create a linear regression model between L-band VOD and biome-level P88. We used monthly mean values of L-band VOD and calculated ratios of yearly minimum and maximum VOD (L-VODmin/max) for each pixel to describe average variability in ecosystem-level water content. The developed L-VODmin/max metric explained 75% of the variation in P88 at the biome level (R2=0.75) indicating that the novel L-VODmin/max metric is capable of capturing changes in plant water status. We then used the L-VODmin/max metric and daily climate data from the ERA5 to see if water stress has increased over time in the world's forests that are more water limited (aridity index below 1.5). For these areas, we found a positive trend in maximum daily vapour pressure deficit, which correlated negatively (p<0.05) with L-VODmin/max trend for the same time period further confirming that L-VODmin/max is capable of explaining differences in plant water status. Additionally, we examined the trend in L-VODmin/max for global forests for the same 2011-2020 period and found a significant negative trend (increasing water stress, p<0.05) for forests in central Africa, southeast Asia, and eastern Australia, and a positive trend (decreasing water stress) for boreal forests in North America and rainforests in Indonesia. Further studies are required to confirm our results suggesting that some of the world's largest carbon sinks are experiencing rapid changes in water stress as a result of climate change.
Basal melt rates and mechanical properties of the Ekström Ice Shelf, East Antarctica, inferred from repeat, quad-polarimetric radar data
Authors: Drews Reinhard , Oraschewski Falk , Ershadi Mohammadreza , Henry Clara , Višnjević Vjeran , Bons Paul , Koch Inka , Hawkins Jonathan , Eisen Olaf
Published: February 2023

Ice shelves buttress ice flow from Antarctica’s interior and provide the interface for ice-ocean interactions. Here, we present a comprehensive dataset collected with autonomous phase-sensitive radio-echo sounders (ApRES) on the Ekström Ice Shelf in East Antarctica. The data include a one year time series of basal melt near the grounding zone and > 40 repeat and quad-polarimetric observations covering the entire ice shelf with the transition to grounded ice and multiple lateral shear zones. The inferred melt rates are put into context in terms of their seasonality and with respect to spatial patterns which were mapped in the internal ice stratigraphy. The polarimetric backscatter show signs of anisotropic ice fabric and spatial changes can be traced coherently from the grounding line to the ice-shelf front. We investigate those signatures in conjunction with the vertical strain rates inferred from ApRES and ice-flow modelling to learn more about ice-shelf rheology, particularly with respect to the stress exponent n.
Assessing the variability of Irminger Water at AR7W between 1993 and 2022 using time-dependent property thresholds
Authors: Wiegand Kevin Niklas , Kieke Dagmar , Myers Paul G. , Yashayaev Igor
Published: February 2023

Irminger Water (IW) is a prominent water mass in the subpolar North Atlantic (SPNA). It is warm and saline and originates from the North Atlantic Current and the Irminger Current. The water mass delivers anomalously large amounts of heat and salt to the Labrador Sea. Like any other water mass, IW is subject to temporal and spatial variability, which needs to be adequately identified and tracked.To separate IW from ambient waters, previous studies identified IW at different times using static thresholds of salinity, temperature, and density (i.e., constant over time within the individual studies). However, given the tremendous variability in the region, such static definitions often do not detect IW sufficiently since these definitions do not account for shifts in the large-scale hydrographic state of the SPNA. To address this issue, this study aims to identify non-static thresholds (i.e., incorporating temporal variability) to analyze IW variability. We refer to the method of identifying IW based on non-static thresholds as the phenomenological approach. To do so, we utilize the observation-based data set ARMOR3D between 1993 and 2022. This new approach allows us to compare estimates of IW properties and volume transports to respective estimates obtained from the static approach.In the case of the static approach being applied to the AR7W section in the eastern part of the Labrador Sea as a test region, the water column was anomalously saline in years of high IW volume transport. Hence, the static approach identified more IW and thus overestimated its volume transport. In contrast, the water column was anomalously fresh in years when the static approach reveals a low IW volume transport. Hence, applying the static approach, less IW is identified, and thus its volume transport is underestimated. In contrast, the phenomenological approach reveals less pronounced decadal variability of the IW volume transport.Applying a static IW definition will likely create stronger gradients between IW and ambient water masses when both are fresher. In turn, these gradients may impose or modulate unrealistic changes in the IW volume transport simply because the actual boundary of IW does not coincide with a certain isohaline or isotherm. Any correlated change or shift in IW properties and, for example, Labrador Sea Water will relocate the IW boundary causing the transport to change. The phenomenological approach introduced in our study resolves this issue.