bluuebunny/crossref_metadata_2025 huggingface dataset:
Four nationwide Digital Surface Models from airborne historical stereo-images
Authors: Ginzler Christian , Piermattei Livia , Marty Mauro , Waser Lars T.
Published: March 2024

Historical aerial images, captured by film cameras in the previous century, have emerged as valuable resources for quantifying Earth's surface and landscape changes over time. In the post-war period, historical aerial images were often acquired to create topographic maps, resulting in the acquisition of large-scale aerial photographs with stereo coverage. Using photogrammetric techniques on stereo-images enables extracting 3D information to reconstruct Digital Surface Models (DSMs), and orthoimages.This study presents a highly automated photogrammetric approach for generating nationwide DSMs for Switzerland at 1 m resolution using aerial stereo-images acquired between 1979 and 2006. The 8-bit scanned images, with known exterior and interior orientation, were processed using BAE Systems' SocetSet (v5.6.0) with the "Next-Generation Automatic Terrain Extraction" (NGATE) package for DSM generation. The primary objective of the study is to derive four nationwide DSMs for the epochs 1979-1985, 1985-1991, 1991-1998, and 1998-2006. The study assesses DSM quality in terms of vertical accuracy and completeness of image matching across different land cover types, with a focus on forest dynamics and management research.The elevation accuracy of the generated DSMs was assessed using two reference datasets. Firstly, the elevation differences between a nationwide reference Digital Terrain Model (DTM - swissAlti3d 2017 by Swisstopo) and the generated DSMs were calculated on points classified as "sealed surface". Secondly, elevation values of the DSMs were compared to approximately 500 independent geodetic points distributed across the country. Six study areas were chosen to assess completeness, and it was calculated as the percentage of successfully matched points to the potential total number of matched points within a predefined area. This assessment was conducted for six land cover classes based on the land cover/land-use statistics dataset from the Federal Office of Statistics.Across the entire country, the median elevation accuracy of the DSMs on sealed points ranges between 0.28 to 0.53 m, with a Normalized Median Absolute Deviation (NMAD) of around 1 m (maximum 1.41 m) and an RMSE of a maximum of 3.90 m. The elevation differences between geodetic points and DSMs show higher accuracy, with a median value of a maximum of 0.05 m and an NMAD smaller than 1 m. Completeness results reveal mean completeness between 64 % to 98 % for the classes "glacial and perpetual snow" and "sealed surfaces," respectively and 93 % specifically for the “closed forest” class.This work demonstrates the feasibility of generating accurate DSM time series (spanning four epochs) from historical scanned images for the entire Switzerland in a highly automated manner. The resulting DSMs will be available upon publication, providing an excellent opportunity to detect major surface changes, such as forest dynamics.
High methane emissions from a eutrophic marine coastal basin driven by bubble release from the sediment
Authors: Zygadlowska Olga M. , Venetz Jessica , Lenstra Wytze K. , van Helmond Niels A. G. M. , Klomp Robin , Röckmann Thomas , Veraart Annelies J. , Jetten Mike S. M. , Slomp Caroline P.
Published: March 2024

The production of methane in coastal sediments and its release to the water column is intensified by anthropogenic eutrophication and bottom water hypoxia, and it is uncertain whether this enhances methane emissions to the atmosphere. Here, we assess seasonal variations in methane dynamics in a eutrophic, seasonally euxinic coastal marine basin (Scharendijke, Lake Grevelingen). In-situ benthic chamber incubations reveal high rates of methane release to the water column (74 – 163 mmol m-2 d-1) between March and October 2021. Comparison of in-situ benthic and calculated diffusive fluxes indicates that methane was primarily released from the sediment in the form of bubbles. In spring and fall, when the water column was oxic, most of the dissolved methane was removed aerobically in the bottom water. In early summer, in contrast, methane accumulated below the oxycline. Enrichments in δ13C–CH4 and δD-CH4 and the abundant presence of methane oxidizing bacteria point towards removal of methane around the oxycline, possibly linked to iron oxide reduction. Methane emissions to the atmosphere were substantial in all seasons with the highest, in-situ measured diffusive chamber fluxes (1.2 mmol m-2 d-1) observed upon the onset of temperature-induced mixing at the end of summer. Methane release events detected in the chamber incubations and model calculations point towards a high year-round flux of methane to the atmosphere in the form of bubbles (55 – 120 mmol m-2 d-1), which bypass the microbial methane filter. Because of such bubble formation, methane emissions from eutrophic coastal systems are likely much higher than previously thought.
Empirical scaling correlations between fault lengths and fault slip-rates in seismically-active extensional regions: The Calabria and Messina Strait region (southern Italy) as case study
Authors: Meschis Marco , Roberts Gerald , Sgambato Claudia , Michetti Alessandro Maria , Livio Franz , Mildon Zoe , Faure Walker Joanna , Iezzi Francesco , Robertson Jennifer , Gattuso Alessandro , Barberio Marino Domenico , Randazzo Paolo , Caracausi Antonio
Published: March 2024

In this study, we present scaling relationships between fault lengths, fault slip-rates and historical seismicity for an active normal fault system, seismically accommodating crustal extension within the upper plate of the Ionian subduction zone (southern Italy). This crustal extension is confirmed by historical seismicity and instrumental geodesy, with GNSS-derived values of horizonal deformation within a range of 2-3 mm/yr throughout Calabria and the Messina Strait region. We collated data for fault slip-rates, fault lengths and historical earthquakes for a given fault to explore whether fault slip-rates are correlated with fault size and their geometric moment.We present new results showing a robust correlation between fault lengths and fault slip-rates, which supports the idea of a relationship for a given fault between fault slip-rates and the geometric moment.We discuss our results in terms of how these correlations should be used if regional deformation is accommodated by localised strain on faults mostly arranged along strike rather than distributed strain on multiple faults across-strike. For instance, we compare our empirical correlation between fault lengths and fault throw-rates over the Middle-Late Pleistocene in Calabria and the Messina Strait with those from Central and Southern Apennines over the Holocene, characterized by strain distributed on multiple faults across-strike and strain localised on faults mostly arranged along-strike, respectively.Tectonic and seismic hazard implications are discussed for future investigations based on fault slip-rates, fault size and historical seismicity.
Adaptive Mesh-free Approach for Gravity Inversion
Authors: Liu Yan , Huang Yao , Lü Qingtian
Published: March 2024

We proposes a method of gravity inversion based on an adaptive mesh-free approach by using a modified radial basis function . It can parametrize the density distribution by using a mesh-free approach. The subsurface space is generally discretized into regular grid cells, while mesh-free methods can avoid the expensive mesh generation and manipulation required in traditional approaches. Scattered points are introduced in most mesh-free methods to discretize the given equations. To deal with the problem of unstructured nodal discretization, we use a mesh-free discretization strategy to establish a mapping of subsurface grid cells to a cloud of discrete points. The nodes are adaptively refined during the inversion process to better recover abnormal bodies. In addition, the hybrid basis function and the modified radial basis function are used to improve the accuracy and stability of the solution. We verify the effectiveness of the proposed method by using several synthetic and empirical tests.
The sensitivity of ocean heat uptake to numerical mixing in forced and coupled ocean models
Authors: Megann Alex
Published: March 2024

The oceans are believed to be responsible for taking up over 90% of the heat retained by anthropogenic greenhouse gases in the atmosphere. For this reason it is important for the ocean component in climate models to have an acceptably realistic representation of the processes that transport heat from the surface into the ocean interior. It is known that ocean models tend to have significant levels of spurious numerical diapycnal mixing, arising chiefly from truncation errors in the tracer advection scheme. It is therefore important to quantify the sensitivity of the simulated climate to numerical mixing, and then to evaluate remedies for the numerical mixing.     A large ensemble of forced and coupled simulations with a 1/4° NEMO ocean is shown to have a global mean surface heat flux ranging from -1.5 to +1.5 W/m2. We demonstrate a strong negative correlation between global ocean surface heat flux and the global mean effective diapycnal diffusivity, a metric of total ocean mixing that includes both explicit and numerical contributions. Several potential mechanisms for this apparently paradoxical result are discussed, including changes in upwelling in the Southern Ocean, mixing of bottom waters in the Pacific and Atlantic, and the Atlantic meridional overturning circulation. Approaches to reducing numerical mixing will be described. 
Large-eddy simulations of the stratocumulus to cumulus transition in the Northeast Pacific using ICON
Authors: Schnelke Moritz , Ahlgrimm Maike , Possner Anna
Published: March 2024

The Northeast Pacific stratocumulus deck is one of the well-known subtropical semipermanent stratocumulus decks that transitions into shallow cumuli along the sea surface temperature gradient away from the Californian coast line. In this study we use observational data from the Marine ARM GPCI Investigation of Clouds (MAGIC) ship campaign to evaluate stratocumulus to cumulus transitions (SCTs) in idealised large-eddy simulations (LESs) with the ICOsahedral Nonhydrostatic Model (ICON). The simulations are conducted with a horizontal resolution of 50 m and a vertical resolution of at most 10 m in the lowest 3 km of the atmosphere. From previous studies of SCTs, including MAGIC and in particular Leg15A, it is well known that entrainment processes drive an important, and likely dominant role in forcing the transition. However, recent studies have shown that microphysical effects like sedimentation or precipitation can significantly alter the course of the SCT. Suppressed precipitation through a higher number of cloud droplets often leads to a delayed SCT. On the other hand, this is counteracted by the associated increase in entrainment, which benefits the transition. This raises the question of the mechanism of this interaction and the overall strength of microphysical effects. Here we present the evaluation of ICON LES and the characterisation of nine selected transitions from the MAGIC campaign, including the well analysed Leg15A. 
Utilizing high-resolution Pléiades satellite imagery for Habitat Quality Modeling in the forested rural eco-regions of Sai Yok National Park, Thailand
Authors: Mukhopadhyay Anirban , Pal Indrajit , Pramanick Niloy , Ganni Aditya , Sukwanchai Kullanan , Kumar Anil , Hati Jyoti Prakash , Acharrya Rituparna , Pal Anushree
Published: March 2024

This Study emphasizes the potential of employing high-resolution Pléiades data for future global forest-habitat eco-region monitoring and management. The assessment involves two key steps: habitat quality modelling and habitat risk assessment. The InVEST Habitat Quality model is employed to estimate the range of habitat and vegetation types, along with gauging their level of degradation using habitat quality and land use land cover as indicators. Concurrently, the Habitat Risk Assessment model is utilized to evaluate the threats posed by human activities to habitats of forested rural eco-regions. These models incorporate elevation, slope, road networks, river systems, and land use as crucial input parameters for modeling and identifying areas where conservation efforts would have the most positive impact on habitat. Indices-based spatial analysis has been coupled with the InVEST model output to refine the habitat quality model output. Furthermore, the study aims to observe the trade-offs between various ecosystem services arising from anthropogenic pressures and the effects of climate change.
Evolution processes of Ross sea polyny aassociated with modified Circumpolar Deep Water intrusion
Authors: Qin Qing , Wang Zhaomin , Yan Liangjun , Liu Chengyan , De Rydt Jan
Published: March 2024

In the central Ross Sea continental shelf, the modified Circumpolar Deep Water could intrude the continental shelf between March and July, and reach about 76 °S. According to seal-CTD data, in March and April, the potential temperature of the modified Circumpolar Deep Water was up to - 0.55 °C, and was widely distributed within the depths of 100 - 300 m. In May and June, the potential temperature of the modified Circumpolar Deep Water was up to - 0.65 °C, and was found to the north of 76 °S above the depth of 350 m, but discontinuous above the depth of 200 m. In July, the modified Circumpolar Deep Water sharply cooled, with the maximum potential temperature being -1.45 °C.By analysing the seal-CTD observations and the numerical model results, this study found strong mixing in the central part of the shelf, owing to topography-induced upwelling. The resulted mixed layer warming is also attributed to the intrusion of the modified Circumpolar Deep Water. This oceanic process, along with the katabatic wind forcing, contributed to forming unique sea ice distribution characteristics in the Ross Sea Polynya, featured by ‘’less ice, more ice, less ice” from the front of the Ross Ice Shelf to the upwelling zone. This kind of sea ice distribution characteristics can also promote the northward expansion of the Ross Sea Polynya.
Eddy Covariance (EC) measurements in a restored floodplain area at the Morava River in Austria within the EU funded REWET project
Authors: Lindenberger Anna , von der Thannen Magdalena , Rauch Hans Peter
Published: March 2024

Although occupying only 7% of the earth's surface, wetlands store 33% of the world's terrestrial carbon. When these ecosystems are drained to be converted into agricultural, forestry or mining exploitations, they release greenhouse gases contributing to climate change. While bringing together 18 partners from 9 countries, the REWET (REstoration of WETlands to minimise emissions and maximise carbon uptake – a strategy for long term climate mitigation) project focuses on determining how the restoration and management of wetlands can be optimised to maximise their carbon uptake while in balance with type-specific natural processes and biodiversity.The REWET project draws upon a network of seven Open Labs (OLs) located in different geographical areas of Europe and covers different types of terrestrial wetlands: freshwater wetlands, peatlands and floodplains. The heterogeneity of the Open labs allows the application of different restoration methodologies while following the same monitoring plan to provide replicable knowledge.This paper presents the measurements and the first result of the OL in Austria within the REWET project. The site is a restored and now protected floodplain area at the Morava River. EC measurements are used to calculate the CO2 and CH4 fluxes and the seasonal as well as annual carbon balance of the ecosystem. Furthermore, the effect of floodplain water levels and grazing in this area is investigated. The EC instruments have been set up on a floating platform to allow measurements also during flood events, when understudied, critical transition of GHG fluxes may occur. The CO2/H2O analyser started collecting the first data in the middle of October 2023 whereas the CH4 analyser was added in end of December 2023. Since the CO2 analyser was put on site first flood events occurred end of December, which is the first data to be processed and analysed. Additional to the results the challenges in setting up an EC tower in a floodplain area will be presented.   Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or CINEA. Neither the European Union nor the granting authority can be held responsible for them.
High-Precision Vertical Movement of the Tibetan Plateau
Authors: Wu Yanqiang , Su Guangli , Li Jingwei , Pang Yajin , Chen Changyun , Jiang Zaisen , Bo Wanju
Published: March 2024

Quantitative and high-precision vertical movements are indispensable for resolving the geological diversity of the Tibetan Plateau. In this study, we proposed a joint geodetic adjustment with Helmert iteration algorithm, systematically analyzed its merits with simulated data, and then jointly processed the datasets, including 116,000 km of leveling data, 21 continuous GNSS data sets, and their connecting surveying data, to get a high-precision vertical velocity field for the Tibetan Plateau. The primary results are as follows: (a) Compared with the single leveling data adjustment, the joint Helmert adjustment results of leveling data (i.e., the leveling data and errors are generated by simulation under the first order leveling regulations, which includes 55,708 km, 4605 segments, 4584 points, 22 loops and 40 nodes) and 500 geodetic simulated data (including 2–4 mm/yr errors) demonstrate that the Helmert adjustment can reduce the residual distribution range by roughly 46%; (b) Vertical uplift is dominant on the southern, northeastern, and southeastern margins of the plateau, with uplift rate ranges of 2.0–3.0, 1.0–3.8, and 1.0–2.0 mm/yr, respectively; (c) Conspicuous subsidence is located along the southern portion of the Ganzi fault, with vertical rates ranging from −3.3 to −0.5 mm/yr; (d) Velocity profiles show that vertical deformation varies in different parts of the Tibetan Plateau, which is mostly accommodated by large strike-slip and thrust faults, such as the Kunlun, Ganzi, and Longmenshan faults. Most of the surface uplift is accommodated by crustal shortening in the interior of the Tibetan Plateau; abrupt changes in vertical rates in eastern Tibet and the widely distributed surface subsidence of southeastern Tibet are consequences of crustal flow and gravitational collapse. Overall, the Tibetan Plateau is characterized by continuous deformation, with large spatial variations accommodated by complicated tectonic processes.
The role of a weakening AMOC in shaping future Euro-Atlantic atmospheric circulation
Authors: Vacca Andrea Vito , Bellomo Katinka , Fabiano Federico , von Hardenberg Jost
Published: March 2024

Climate change simulations predict a weakening of the Atlantic Meridional Overturning Circulation (AMOC). In the North Atlantic, where the deep convection occurs, the AMOC has a particularly marked influence. Here, the AMOC decline could have significant implications for the evolution of weather patterns, resulting in societal risks for densely populated areas of Europe. We employ the Weather Regime framework to analyse the change in the daily variability of large-scale atmospheric circulation in three coordinated experiments from the CMIP6 archive (i.e., ssp2-4.5, ssp5-8.5 and abrupt-4xCO2). We find that models that simulate a larger AMOC decline feature a net increase in NAO+ regime frequency and persistence compared to models that simulate a smaller AMOC decline. We show that this is due to the influence of a reduced warming of the subpolar North Atlantic (SPNA) on mean geopotential height, caused by the AMOC weakening. We further show that this also causes the storm track to strengthen due to an increased baroclinicity of the atmosphere in the region, with possible consequences on future extreme events.Overall, our results suggest that the evolution of the Euro-Atlantic atmospheric circulation depends on the AMOC decline. We conclude that ocean circulation is a main driver of NAO variability in projections of future climate change, in addition to previously known drivers. 
Thermal characteristics of springs fed by mountain permafrost in Val di Sole (Eastern Italian Alps)
Authors: Carturan Luca , Zuecco Giulia , Boaga Jacopo , Morino Costanza , Pavoni Mirko , Seppi Roberto , Tolotti Monica , Zanoner Thomas , Zumiani Matteo
Published: March 2024

In alpine areas, spring-water temperature is affected by the presence of permafrost and by changes in the periglacial domain caused by the current atmospheric warming. Our interest in spring-water temperature is related to the possibility of investigating the spatial distribution of alpine permafrost and its changes. In particular, spring-water temperature might be helpful as indicator of permafrost occurrence in areas where it is discontinuous or sporadic, and in general where its distribution is poorly known.The spring-water temperature in late summer is a useful evidence of permafrost, and various authors employed such method as auxiliary permafrost evidence, or as a stand-alone method that can be used for mapping permafrost distribution at the catchment scale. However, little is known on the spatial and temporal variability of water temperature at springs with different permafrost contribution and characteristics.Here we present an analysis of the spatial and temporal variability of spring-water temperature in a 795 km2 catchment located in the Eastern Italian Alps, aimed at investigating the spatial distribution of permafrost and its effect on spring-water temperature. From 2018 to 2021, we measured the late-summer spring-water temperature at 220 springs, 133 of which are located downslope of rock glaciers, 81 downslope of other deposits, and 8 in bedrock. In addition, we installed dataloggers for continuous temperature measurements at 31 springs.Results show that the cold springs are mainly associated with intact rock glaciers but also with rock glaciers classified as relict, especially if they have blocky and sparsely vegetated surface. Accordingly, the latter should be reclassified as pseudo-relict, i.e. they appear to be visually relict but host patchy permafrost, as confirmed by geophysics carried out at selected case studies. These results have important implications for the study and modelling of the hydrological, hydrochemical and ecological response of periglacial environments under ongoing climate change.
Heavy mineral analyses to reconstruct basin evolution, an insight from the Yukon-Koyukuk basin sandstones, Alaska. 
Authors: Seminara Simone , Pease Victoria , Toro Jaime
Published: March 2024

We present a heavy minerals study of several sedimentary units deposited within the Yukon-Koyukuk basin (YKB) in Alaska. The YKB started to form in middle to late Jurassic after the collision between an intraoceanic volcanic arc and the Arctic Alaska margin. The collision led to thrusting of the seafloor (mafic and ultramafic rocks of the Angayucham Terrane), over the future Brooks Range and Ruby Terrane. The basin is flanked on three sides by metamorphic rocks of the Seaward Peninsula to the west, the Ruby terrane to the east and the Brooks Range to the north. The remnants of the volcanic arc (Koyukuk Arc Terrane, KAT) divide the basin into a northern Kobuk-Koyukuk basin (KKB) and a southern Lower-Yukon basin (LYB).We present results from the Kv, Kvg, Ks, Kms, Kmc, and Kqc units (after Patton et al.2009), collected along the Koyukuk and the Yukon rivers. The units are as follows:Kv: formed by basaltic and andesitic lava flows interbedded with volcanogenic conglomerate to mudstone rocks. K-Ar ages vary from 134 Ma and 118 Ma with a U-Pb age obtained through a tuff of about 138 Ma.
Kvg: mainly consists of volcaniclastic greywacke and mudstone interbedded with tuffaceous layers which gave U-Pb ages comprised between 112 and 110 Ma (Albian). Molluscs of the same time have been reported throughout the entire unit.
Kms: mainly fine to coarse sandstone interbedded with shaly layers. Interpreted to be the marine tongue of the Ks deposits.
Ks: late Cretaceous in age, this unit consists of alternations of sandstone and shale layers deposited in fluvial to shallow marine environments.
Kmc: mafic igneous clasts conglomerate with mafic and calcareous greywacke and mudstone. Marine molluscs of Cretaceous age have been found.
Kqc: overall a quartz rich unit composed of conglomerate, sandstone and mudstone. Plant fossils date the unit to the Cretaceous.
We use Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN®) for heavy mineral (HM) analysis to establish a clear relationship between sediments and source regions and build a model for the basin formation and evolution. Kv and Kmc samples reflect a volcanic source, while Kvg, Kms, Ks, and Kqc display the progressive unroofing of deeper and higher grade metamorphic rocks. Combining these data with DZ and U-Pb absolute ages, we interpret the YKB to be formed prior to 138 Ma as the forearc basin of the intraoceanic arc. It evolved into a hinterland setting at about 110 Ma when the first deposition of metamorphic detritus is recorded by the Kvg unit, mainly derived from erosion of the Brooks Range.  Limited paleocurrent data along with the novel HM data attribute the Ks, Kms, Kmc and the Kqc to the erosion of the Ruby terrane as it uplifted during middle to late Cretaceous time.
The glacier views of Jean-Antoine Linck - a milestone for the Mont Blanc glacier history from the 18th to the 19th century
Authors: Nussbaumer Samuel U. , Zumbühl Heinz J.
Published: March 2024

Interdisciplinary approaches are needed to reconstruct the behaviour of glaciers beyond the beginning of systematic, direct measurements. Particularly for the period of the Little Ice Age (LIA), historical documents have been very valuable to successfully reconstruct former glacier extents at different sites. An analysis of historical documents on the well-documented Mont Blanc region, for example, provides unique insights into the LIA glacier development.The Mont Blanc area became popular with artists, scientists, and travellers in the mid-18th century, including Jean-Antoine Linck from Geneva, who is probably the artist to whom we owe the greatest number of unique glacier views. Jean-Antoine Linck was particularly interested in the icy regions, which he discovered and drew with alpinistic daring and naturalistic accuracy, preferably in gouache, although many pencil sketches have also been preserved. From a glacier history perspective, Linck's work is indispensable, even if many of his artworks are not precisely dated by the author: It represents the whole development of the Mont Blanc glaciers, specifically the Mer de Glace and Glacier des Bossons, but also other glaciers during the period from the end of the 18th century until the 19th century glacier maximum around 1820. As an amazing novelty, Linck was probably the first observer to show a glacier advance with the help of two realistic and accurate views from the same position; one as the Glacier des Bossons retreats and the other as it advances. In addition, various views by Linck make it possible to quantify smaller glacier extents, e.g. around 1800 at the Glacier des Bois (Mer de Glace), which were depicted much more rarely.To distribute his work, Linck subtly used the etching technique to create easily reproducible plates in large format, which are then hand-coloured with gouache and watercolour. This technique allowed him to create numerous reproductions of the same view, while still giving them a unique and original aspect, views that are remarkable for their serenity and silence, while offering luminous atmospheres. These illustrations introduced the realistic representation of the high mountains into the iconography of Genevese painting and thus led to a new kind of landscape painting with a permanent character.In terms of glacier history, the work of Jean-Antoine Linck has the same significance for the Mont Blanc area as that of Caspar Wolf and Samuel Birmann for the central Swiss Alps or that of Thomas Ender for the Austrian Alps in terms of glacier iconography. Linck was therefore both an artist and a glacier historian.
Context-dependent benefits of ectomycorrhiza on Aleppo pine seedling performance under ecologically relevant settings 
Authors: Livne- Luzon Stav , Herol Lior , Klein Tamir , Shemesh Hagai
Published: March 2024

Droughts significantly impact forests, with long-term forest existence largely depending on seedling recruitment. However, seedling establishment under natural conditions is often limited by numerous interacting factors such as water availability, competition with herbaceous vegetation, and interaction with ectomycorrhizal fungi (EMF). We performed two greenhouse experiments to examine these factors and their interacting effects on the establishment of Aleppo pine seedlings. In both experiments, Geopora, a genus known to colonize seedlings in dry habitats, predominantly colonized the seedlings' roots, regardless of the EMF inoculum's origin. EMF inoculation enhanced seedling height, biomass, and branch number. However, under combined drought and competition, EMF had no growth impact. When facing competition or consistent water scarcity, EMF's positive effects decreased. Interestingly, during intermittent drought periods (resource pulses), EMF benefits persisted even in severe drought. This discrepancy in pine performance across treatments highlights the complexity of benefits provided to seedlings by EMF under ecologically relevant settings. 
A wave ensemble prediction system for the Mediterranean Sea
Authors: Kampouris Konstantinos , Korres Gerasimos
Published: March 2024

An ensemble wave prediction system (EPS) at a 1/16o grid horizontal resolution is being developed for the Mediterranean Sea, based on the WAM Cycle 6 wave model implementation. Open boundary conditions are provided by a North Atlantic wave model at 1/6o resolution. Uncertainty is forced in the Med-waves EPS (in both the Mediterranean and the North Atlantic wave models), through a reduced size ensemble of 10m winds provided from the ECMWF atmospheric EPS (50 members + 1 control run) at approximately 18 km spatial resolution with a forecast horizon of 10 days ahead. The nominal ECMWF EPS ensemble size (50 ensemble + 1 control members) is reduced to 23+1 members using clustering techniques (k-means method). The Mediterranean 10-day ensemble wave forecasts are verified for a 6-month period (Jan-Jun 2022) against available satellite and wave buoys observations, as well as reference cases, like the forecast of the NRT Med-waves of the Copernicus Marine Service. A variety of both deterministic and probabilistic metrics are used in the verification process, in order to access as many forecast quality attributes as possible and to best determine the performance of the EPS. In general, the wave EPS shows a good forecast skill, which after the first 3-4 forecast days becomes even better than the skill of the deterministic Med-waves Copernicus Marine forecast system, indicating the importance of the ensemble approach as the forecast ranges increase.
Seismic velocity structure of the 25 °S OCC north of the Rodriguez Triple Junction at the Central Indian Ridge extracted from ocean bottom seismometer
Authors: Dannowski Anke , Engels Martin , Schramm Bettina , Schnabel Michael , Lucke Oscar , Barckhausen Udo , Heyde Ingo , Ladage Stefan , Lutz Rüdiger , Filbrandt Christian , Jegen Anna , Grevemeyer Ingo
Published: March 2024

Three tectonic plates meet at the Rodriguez Triple Junction in the Central Indian Ocean. The plates are separated by the Central Indian Ridge (CIR), the South-East Indian Ridge (SEIR) and the South-West Indian ridge (SWIR), which all show highly different spreading behaviours. While the northernmost segment of the SEIR is magmatically robust, the eastern tip of the SWIR is highly amagmatic. The CIR appears to oscillate between opening mechanisms, associated either with magmatic or magma-starved spreading processes, which can be observed over a very confined stretch of crust. Even though the area has been studied thoroughly, using a variation of geophysical and geological methods in the past decades, seismic images of the region were missing. From November 2023 to January 2024, RV Sonne (SO301 - SCIROCCO) set out for a seismic reflection and refraction survey to fill this gap and to provide a database for a better understanding of the tectonic setting and evolution of the area. A special focus was put on studying the structure and extent of the Oceanic Core Complex (OCC) at 25 °S.Here we present preliminary results of an east-west trending 150 km long profile crossing the OCC and the CIR. Along the profile, 33 ocean bottom seismometers were deployed with a spacing of 4-5 km that grew denser over the OCC. The shot spacing was between 50-110 m. Clear crustal refracted P- and S-phases were observed to offsets of up to 40 km in the shot sections and mantle reflections, as well as Pn-phases could be identified sporadically. First results of travel time tomographies, which were executed separately for P- and S-waves, and used for the calculation of a Vp/Vs-ratio section indicate a strongly variable crustal construction. Highly fractured areas seem to interchange with highly hydrated areas within short distances. Correlations of the new bathymetric data to the seismic images and the integration of the new gravimetric and magnetic data will sharpen the geophysical image and its tectonic interpretation along the profile.
Investigating the Subsurface of the Iranian Plateau using Adjoint Tomography: A 3D Seismic Velocity Model
Authors: komeazi Abolfazl , Kaviani Ayoub , Rümpker Georg
Published: March 2024

A 3D seismic velocity model of the Iranian plateau was constructed using adjoint tomography. The initial model used in this study is taken from a previous adjoint noise tomography investigation in the region, and was refined through the inversion of waveforms recorded at seismic broadband stations from 320 local/regional earthquakes for which a Centroid-Moment-Tensor (CMT) has been computed. The synthetic waveforms were calculated using the spectral-element method (SEM) through a mesh of 12 million grid points representing the Iran region. The model parameters were iteratively updated by Newton's method, using misfit and Hessian kernels to minimize the difference between observed and synthetic waveforms. The forward and adjoint simulations were computed on the HRL GPU-cluster in Frankfurt, requiring a total of 6720 simulations and approximately 13,000 node hours to achieve the final model after 11 iterations. Comparison of the synthetic waveforms produced by the proposed model to the observed waveforms for a subset of selected earthquakes indicates improved fit in the period range of 10-50 seconds confirms the model's ability to accurately predict actual waveforms. The identification of previously undetected anomaly features beneath the Iranian plateau was also observed, which could be attributed to geological features with sufficient data coverage and resolution.
Using a portable EM27/SUN FTIR-spectrometer for validating the TCCON site-to-site consistency: The COCCON Travel Standard
Authors: Herkommer Benedikt , Hase Frank , Groß Jochen , Alberti Carlos , Castracane Paolo , Dehn Angelika , Chen Jia , Dietrich Florian , Morino Isamu , Frey Matthias Max , Gillespie Lawson , Pak Nasrin Mostafavi , Wunch Debra , Deutscher Nicholas , Walker Brittany , García Omaira Elena
Published: March 2024

The precise knowledge of the global atmospheric concentrations of green-house gases (GHG) are crucial for understanding and monitoring climate change.Satellites for measuring GHGs are offering a global coverage, however, they need precise ground-based reference data for validation.This reference data is provided by ground-based measurements, foremost the Total Column Carbon Observing Network (TCCON).The TCCON measures column averages of GHG abundances at about 25 stations around the globe using Fourier Transform Infrared (FTIR) spectrometer.For achieving the high data quality needed for the validation of current and upcoming GHG measuring satellite missions the control of site-by-site biases across the network is of utmost importance. So far, the verification of the individual TCCON sites mainly depends on the collection of collocated in situ measurements of GHG profiles, using airplane overflights or balloon air-core measurements, the use of calibrated HCl gas cells and on the evaluation of XAIR. In this work we present a new supplemental approach by using the portable EM27/SUN FTIR spectrometer, which is the standard instrument of the Collaborative Carbon Column Observing Network (COCCON). This instrument type has proven its high stability in various field campaigns and long-term studies. In the framework of the ESA project “Fiducial Reference Measurements for Green-House Gases II” we are exploiting the stability of the instrument to use it as a Travel Standard (TS) for the TCCON. We visited sites in Japan, Canada, Germany, Australia, France and the Canary Islands to perform side-by-side measurements with the local TCCON spectrometers. Between the visits, the stability of the TS was monitored using the Karlsruhe TCCON site and the COCCON reference spectrometer.This allows to compare the different TCCON sites to a common reference and hence, to verify the level of station-to-station consistency currently achieved by the TCCON and support further improvements. Here, we present the results of the TS visit at the TCCON site Tsukuba(Japan), Wollongong(Australia) and Izana(Canary Islands).
Core transiting seismic waves on Mars: observations and implications
Authors: Irving Jessica , Lekić Vedran , Samuel Henri , Durán Cecilia , Drilleau Mélanie , Kim Doyeon , Rivoldini Attilio , Khan Amir , Horelston Anna ,   InSight Science Team
Published: March 2024

The InSight mission collected four years of seismic data from Mars, providing unprecedented data on the planet’s interior. Two seismic events – one marsquake and one meteorite impact – took place on the opposite side of Mars to InSight’s broadband seismometer [1]. These two far-side events were initially located using mantle-transiting PP and SS waves, but we demonstrate that their waveforms contain additional seismic arrivals which are sensitive to the properties of the Martian core.
Using multiple seismic methods, we obtain SKS differential travel times for S0976a, a distant marsquake, and S1000a, a distant impact. SKS travels through Mars’ core as compressional waves and is therefore sensitive to its elastic properties. We use these differential travel times to build the first seismically informed models of Mars’ core [2]. The core velocity of Mars is low: 4.9-5.0 km/s at the CMB. We use our seismic results to estimate the fraction of light elements in Mars’ core, finding a high fraction of sulphur is needed, together with lesser amounts of oxygen, carbon and hydrogen.
In addition to the SKS signals observed, the waveforms from S1000a contain evidence for a seismic wave which diffracts along a molten silicate layer at the base of the Martian mantle and also reflects from the core-mantle boundary. The presence of a basal silicate molten layer has implications for the areotherm, and could reduce both estimates of metallic core’s radius and its fraction of light elements [3].
The SKS detections reported provide information about the physical properties of the liquid core of Mars. A solid inner core at the centre of Mars is unlikely; we assess what structures inside the Martian core can be excluded based on existing data and models.
 
 
[1] Horleston et al., 2022. Seism. Rec., 2(2), 88-99
[2] Irving et al., 2023. PNAS, 120, e2217090120
[3] Samuel et al., 2023, Nature, 622, 712–717
Temperature and salinity changes in the abyssal Atlantic and Pacific Oceans over the Middle Pleistocene Transition
Authors: Thomas Nicola , Hodell David , Ford Heather , Greaves Mervyn
Published: March 2024

Ocean thermohaline circulation (THC) is driven by temperature and salinity in source areas of deep-water formation. THC underwent a fundamental change ~950 to 860 thousand years ago (ka) during the Middle Pleistocene Transition (Pena and Goldstein, 2014). However, the relative contributions of temperature (‘thermo-’) versus salinity ('haline’) change to this fundamental THC reorganization remain unclear. Here we compiled North Atlantic and Pacific Ocean stacks of deep-water temperature (estimated using foraminiferal Mg/Ca) and salinity (estimated from δ18Oseawater) for the past 1.5-million-years (Myr). The deep North Atlantic became colder and the deep Pacific saltier during glacial periods younger than ~900 ka. Cooling of northern sourced water likely led to increased salinity of southern sourced water by decreasing the melting of land-based ice around Antarctica (Adkins, 2013) and increasing sea ice formation and associated brine rejection. With increased stratification the abyssal ocean became a more effective carbon trap lowering the concentration of atmospheric pCO2, thereby permitting ice sheets to grow larger and lengthening the glacial cycle. Expansion of Antarctic ice sheets would have also contributed to increasing the salinity of southern source areas as Antarctica shifted from dominantly terrestrial melting to marine-based calving margins (Raymo et al., 2006). Our temperature and salinity reconstructions support a fundamental reorganization of the density structure and stratification of the abyssal glacial ocean across the Middle Pleistocene Transition. References:Adkins, J.F. (2013) ‘The role of deep ocean circulation in setting glacial climates’, Paleoceanography, 28(3), pp. 539–561. Available at: https://doi.org/10.1002/palo.20046.Pena, L.D. and Goldstein, S.L. (2014) ‘Thermohaline circulation crisis and impacts during the mid-Pleistocene transition’, Science, 345(6194), pp. 318–322. Available at: https://doi.org/10.1126/science.1249770.Raymo, M.E. et al. (2006) ‘Plio-Pleistocene Ice Volume, Antarctic Climate, and the Global’, Nature, 313(July), pp. 492–495. Available at: https://doi.org/10.1126/science.1123296. 
Calving MIP: Results and conclusions from the first phase of a model intercomparison project into ice shelf calving
Authors: Jordan Jim
Published: March 2024

The representation of ice shelf calving in numerical ice models is a new and emerging field in cryospheric modelling. As yet, there has been no systematic, in-depth study of how this process is implemented and whether the results can be trusted. Calving MIP is an ongoing model intercomparison project that seeks to address this issue by providing a common framework for model simulations of ice shelf calving, so that results between different models and approaches can be compared. We find it helpful to distinguish between a calving algorithm, the numerical implementation in a model of how ice is removed due to calving, and a calving law, a law with some physical basis that determines how much ice needs to be removed due to calving. The first phase of Calving MIP experiments are primarily interested in comparing different calving algorithms, whilst future experiments are planned to investigate different calving laws as well as compare simulated results with real world observations.We present here results from across the cryospheric modelling community from the first phase of Calving MIP experiments investigating calving algorithms as well as future plans for further experiments.
Tuning the performance of a borehole heat exchanger array in response to transient hydrogeological conditions
Authors: Soltan Mohammadi Hesam , Ringel Lisa Maria , Bott Christoph , Bayer Peter
Published: March 2024

Most shallow geothermal systems harness renewable energy from the ground by circulating a heat-carrier fluid through borehole heat exchangers (BHEs). While these systems have emerged as promising contributors to the ongoing energy transition, open questions regarding their durability and performance in practical applications remain. Critical factors are the uncertainty in the long-term heating/cooling demand as well as the uncertainty in the evolution of the ground thermal conditions. To enhance the environmental and economic appeal of such systems that should be operated for decades, optimal control procedures that adjust the heat extraction during the course of operation have been proposed. In this study, we introduce an improved sequential simulation-optimization procedure to tune the efficiency of BHEs exposed to transient groundwater flow conditions. The variability of groundwater flow not only perturbs subsurface heat transfer but also impairs the predictability through standard BHE modeling tools. For example, the well-established moving finite line source (MFLS) formulation offers no capabilities to represent transient trends in advective heat transport associated with groundwater flow. We restructure the MFLS by a time-varying groundwater flow term that ensures compliance with thermal equilibrium assumptions. This modified variant is validated with a numerical model and then interfaced with a linear programming algorithm to optimize the operation of the BHE array. To examine the efficacy of the proposed procedure, a synthetic field containing ten BHEs operating in the heating mode is implemented. Three distinct groundwater fluctuation scenarios, with monthly resolutions over a ten-year operational lifespan, are considered. The groundwater flow dynamic exhibits variations in an increasing, decreasing, and periodic manner. As the objective, local cooling is to be minimized. This is achieved by determining the monthly optimal load pattern for individual BHEs. The proposed methodology employs a cost function to minimize the maximum temperature change over two distinct temporal terms. The first term considers the entire operational lifetime, while the second term focuses on a forthcoming 12-month horizon.The proposed methodology does not only achieve optimal BHE operation, but it also facilitates calibrating unknown or transient model parameters. This is demonstrated for the groundwater flow velocity that is estimated by solving a nonlinear least-squares problem using the trust-region-reflective algorithm. The benefit of sequential learning is compared with results obtained by optimization without any model calibration. This calibration-optimization routine, informed by transient temperature changes in the simulated ground, outperforms sequential optimization that relies on non-tunable model parameters.