bluuebunny/crossref_metadata_2025 huggingface dataset:
DOC mobilisation from forest soils governed by intermittent hydrological connectivity of subsurface water pools
Authors: Adam Sean , Lau Maximilian , Jackisch Conrad
Published: February 2023

Climate change in combination with forest management practices is leading to increased DOC release from a forested reservoir catchment in the western Ore Mountains in Germany. The most significant sources of DOC loadings are likely several disturbed patches of former peatland in the catchment. We suspect that the soil water availability and subsequent variable hydrological connectivity of water pools in the shallow subsurface could be major factors for DOC mobilisation impeding the drinking water production in the region.We present data from almost one year of intensive monitoring in two small catchments (1 ha) located on i) a shallow histosol with a highly compacted mineral subsoil and ii) a regolithic cambisol. Catchment drainage was constantly observed for water levels and in situ spectroscopy to infer discharge rates and DOC concentrations. Soil moisture and temperature, surface temperature and irradiation were continuously measured along the slope gradient. During monthly campaigns in the vegetation period, pore water samples were taken from high and low points of 15 m grid cells spanning the catchments.In our poster, we would like to discuss our findings that pore water availability is non-uniformly distributed suggesting discrete subsurface flow paths in the catchments. In low moisture conditions, subsurface water pools can be isolated from the pore water network. We argue that disconnected pools accumulate DOC during low moisture conditions, which is then released when the pools are reconnected during strong precipitation events.
Rapid large-amplitude vertical motions generated by subduction slab roll-back in back-arc basins (Valencia Trough, Western Mediterranean)
Authors: Tugend Julie , Fang Penggao , Kusznir Nick , Mohn Geoffroy , Ding WeiWei
Published: February 2023

The formation and evolution of back-arc basins is complex controlled by subduction dynamics, lithosphere delamination, magmatism, slab roll-back and extension. In such a complex geodynamic context, it is difficult to decipher the mechanisms which controls sedimentary basin subsidence history and distinguish the contribution of lithosphere tectonics from dynamic topography.Here we focus on one of the main basins of the Western Mediterranean, the Valencia Trough, which formed in the Cenozoic in relation with the slab roll-back of the Tethyan oceanic lithosphere. More specifically, we investigate the subsidence and geodynamic context related to the formation of a regionally observed unconformity, which separates Mesozoic from latest Palaeogene to Neogene sediments, and here referred to as the Miocene Unconformity.Using a dense grid of seismic reflection data, well data and 3D flexural backstripping, we show that the Miocene Unconformity subsided by more than 1.5 km from ~17 Ma to the present day at an average rate of 90 m/Myr in the SW Valencia Trough. The absence of Cenozoic extensional faults affecting the basement shown by seismic data indicates that this rapid subsidence is not caused by Cenozoic rifting. This subsidence cannot be explained by flexural loading related to the adjacent thin-skin Betic fold and thrust belt either, which only affects subsidence observed near the deformation front. Subduction dynamic subsidence generated by the positive mass anomaly of the subducting slab in the mantle is another mechanism that can control the subsidence evolution of back-arc basins. However, since the formation of the Miocene unconformity, the subduction has propagated westwards and southwards and has slowed or ceased under the Valencia Trough, which would have resulted in the progressive diminution of subduction dynamic subsidence, generating a relative uplift rather than subsidence.We propose an alternative mechanism and interpret the 1.5 km subsidence of the Miocene Unconformity as the collapse of a back-arc transient uplift event. Erosion during the uplift, resulting in the formation of the unconformity, is estimated to exceed 4 km. This transient uplift was likely caused by heating of back-arc lithosphere and asthenosphere, combined with mantle dynamic uplift, both caused by segmentation of Tethyan subduction resulting in slab tear. Rapid subsidence subsequently resulted from the removal of mantle flow dynamic support from the Tethyan subduction slab roll-back and thermal equilibration.Our observations and interpretation of rapid back-arc kilometre-scale uplift and collapse might have global applicability to explain some of the observed vertical motions and the subsidence evolution of other back-arc regions experiencing subduction segmentation and slab tear during subduction slab roll-back.
Impact of Land Use Change on Soil Carbon Storage in topsoil of the tableland of the Loess Plateau in Shaanxi in Recent Thirty Years
Authors: Liu Mengyun , Zhang Mengmeng , Chang Qingrui
Published: February 2023

The impact of land use change on soil organic carbon storages at the regional scale is crucial to the ecological effects of the local environment. According to soil samples and land use data, the effect of land use change on soil organic carbon density and reserves in the surface layer (0~20 cm) of the Loess Plateau, Shaanxi, from 1985 to 2015, was studied. The results show: ⑴The policy of returning farmland to forest has a great impact on the transformation of land use type in the tableland of Shaanxi Loess Plateau. The change of land type mainly focused on the area reduction of cultivated land and grassland, respectively reduced by 6.02% and 15.14%.And the areas of forest land and residential land increased, with an increase of 281.07% and 24.09% respectively. ⑵ In the past three decades, the spatial variation trends of soil organic carbon density in surface soils of the study area were quite different. The increase was 11.43% in 2006 compared with 1985, and 89.74% in 2015 compared with 2006. ⑶ From 1985 to 2006, the area of maintaining land use type was 111997.18 km2, and the surface soil carbon storage increased by 1404.31×106kg. The area of changing land use type was 776.15 km2, and the carbon storage increased by 14.49×106kg. From 2006 to 2015, the area of maintaining land use type was 9359.68 km2, and the surface soil carbon storage increased by 3829.98×106kg. The area of changing land use type was 776.15 km2, and the carbon storage increased by 1318.13×106kg. ⑷ In the past 30 years, the area of maintaining land use type decreased, and the area of changing land use type increased. The conversion of land use type to forest land and grassland was conducive to the formation of surface soil carbon sink, and the conversion to cultivated land and residential land resulted in the release of surface organic carbon. The comparative analysis between the two periods showed that the conversion of land use type was more intense and the soil carbon storage increased significantly after the policy of returning farmland to forests was implemented. Therefore, the policy of returning farmland to forests in the tableland of Shaanxi Loess Plateau can increase the carbon fixation of ecosystem.
Performance comparison of newly developed hydro-mechanical (hybrid) models for real-time induced seismicity forecasting
Authors: Clasen Repolles Victor , Rinaldi Antonio Pio , Ciardo Federico , Passarelli Luigi , Wiemer Stefan ,   Bedretto Team
Published: February 2023

The Adaptive Traffic Light System (ATLS) is a seismic risk mitigation tool that can be used during geoenergy exploitation projects such as in the creation of Enhanced Geothermal Systems (EGS). In real-time applications, ATLS needs to include a data assimilation scheme in order to produce adaptive and time-dependent probabilistic seismicity forecasts by using the maximum available information at the moment of the assessment during such industrial operation. Numerical models capable to robustly forecast in real-time the temporal evolution of induced seismicity while properly accounting for uncertainties are the core elements of a functioning ATLS. In this respect, hydro-mechanical (HM) hybrid models are suitable models since they combine both statistical and physics-based assumptions to forecast induced seismicity. They include an accurate modeling of the physical processes involved in the generation of seismicity caused by human activity by keeping the associated computational cost low. In this work, we have developed two classes of simplified hybrid models that are based on 1D radial pore-fluid diffusion and fluid injection. The first class (HM0) accounts for linear pore-fluid diffusion from the fluid source, while the second class (HM1) accounts for the non-linear response of the medium due to pressure-dependent permeability variations upon fluid injection. Each class is sequentially coupled to two stochastic seismicity models that trigger seismicity if the respective space-time pressure solution reaches a critical value according to the Mohr-Coulomb criterion. However, both seismicity models differ in the way they simulate seismicity. One model uses an analytical approach based on probability density functions of model parameters to simulate seismicity (CAPS), while the other model simulates seismicity via stochastic seed approach (SEED). In a hindcast experiment, we test the models’ real-time forecasting capabilities within a data assimilation scheme using datasets from in-situ injection experiments that encompass different spatial scales. An essential step towards building a reliable ATLS is to properly weight each candidate model according to its respective contribution to the seismic hazard calculation. Therefore, an important part in our calculations is to evaluate and compare the forecasting performance of each model for each of the presented cases. Our findings show that models that take into account reliable distribution of uncertainties on a-priori selected model parameters as well as models accounting for a physically more accurate pressure solution in space and time generate better forecasting performances.
Physical protection of soil organic carbon in Swedish arable soils in relation to oxalate-extractable aluminum.
Authors: Chilipamushi Miyanda , Colombi Tino , Kätterer Thomas , von Brömssen Claudia , Larsbo Mats
Published: February 2023

Stabilizing soil organic carbon (SOC) is essential for maintaining soil structure and carbon sequestration. Soil aggregation through organic-mineral associations helps to protect SOC from microbial decomposition physically. Recent research has shown that the chemical interactions between SOC and reactive aluminum (Al) phases may be central for this aggregation in acidic soils and, hence, for the protection of SOC. However, the role of reactive Al phases in protecting SOC on a national level in Sweden is unclear. We analyzed 100 topsoil samples from the Swedish national monitoring program ‘Swedish soil and crop monitoring inventory’ taken between 2001 and 2017 in a grid covering all major agricultural areas in Sweden and determined the Al and iron content after chemical extraction using ammonium oxalate acid. We also estimated silt-sized aggregation from the differences in particle size distributions measured with a laser diffraction analyzer (Partica LA-950 V2, Horiba) between mechanically and chemically dispersed samples. Preliminary results show that SOC is indeed positively correlated with oxalate extractable Al on a national scale in Sweden, while correlations with clay and oxalate extractable iron are much weaker. The results derived from this study can help to determine the relationship between reactive Al phases, soil aggregation, structure, and the potential for carbon sequestration in Swedish arable soils.
Investigation of Measured Non-Rogue Wave Time Series With Large Outstanding Spectral Solitons
Authors: Teutsch Ina , Wahls Sander , Weisse Ralf
Published: February 2023

We consider measurement data from a surface-following wave buoy in the southern North Sea. The data were collected in a water depth that lies within the range of applicability of the Korteweg-de Vries (KdV) equation. We intend to increase the understanding of nonlinear processes that might be responsible for the increased rogue wave occurrence observed at this site (Teutsch et al., 2020). More specifically, we investigate the role of (potentially “spectral”) solitons identified by the nonlinear Fourier transform (NLFT) for the KdV equation for the occurrence of rogue waves. In a previous study, we identified a connection between the spectral solitons and rogue waves at the considered station. Teutsch et al. (2022) showed that KdV-NLFT spectra containing one exceptionally large outstanding soliton often corresponded to measured time series including a rogue wave. Some of the time series with a large outstanding soliton however did not contain rogue waves. In this study, we investigate if these outliers might correspond to rogue waves at a different location. This is motivated by the fact that the NLFT soliton spectrum does not change under the KdV equation. We therefore propagate the time series without rogue waves, but with an outstanding soliton in the KdV-NLFT spectrum, according to the KdV equation, to investigate the occurrence of rogue waves shortly upstream or downstream of the recorded time series.References:Teutsch, I., Weisse, R., Moeller, J., and Krueger, O. (2020): A statistical analysis of rogue waves in the southern North Sea, Natural Hazards and Earth System Sciences, 20, 2665–2680.Teutsch, I., Brühl, M., Weisse, R., and Wahls, S (2022): Contribution of solitons to enhanced rogue wave occurrence in shallow water: a case study in the southern North Sea. Natural Hazards and Earth System Sciences Discussions, under review.
Monitoring Landcover changes of small-scale alluvial mining in Columbia Based on Multi-source Remote Sensing Data
Authors: Xiong Lifan , Jiang Jingyi
Published: February 2023

     Small-scale and artisanal mining is widespread in many countries and often causes severe eco-environment problems. The dynamic nature of this extractive activity and its spread in rural and remote areas make its mapping and monitoring very challenging. Therefore, the use of multi-source remote sensing data provides possibilities to monitor landcover changes as well as the destruction and restoration of vegetation in these regions. 

     The study area of this paper is located at the border of El Bagre and Zaragoza, in Bajo Cauca, Colombia, which is greatly affected by small-scale alluvial gold mining. This place has a typical tropical climate with frequent high cloud coverage. Therefore, the multi-source remote sensing images (Sentinel-2, Landsat-8 and Sentinel-1) are selected for this study to detect and map small-scale mining of gold placers. For both Sentinel-2 and Landsat-8 data, clouds are removed according to the information of pixel QA bands through the google earth engine (GEE). Then multiple images within each two months are aggregated after cloud removal. For Sentinle-1 data, post-processing including noise removal, calibration and orthorectification using DEM data is applied with GEE. When cloud-free data is not available within two months, Sentinle-1 data is added to improve the accuracy of the classification. The support vector machine classifier (SVM) is selected as the supervised classification approach. And to avoid possible classification errors, the post-classification based on local geographic information is also applied. Results show the landcover changes of mining areas in recent years and detect the location of mining areas, including mined bare soil and mining ponds and other important land cover. Furthermore, the change of vegetation cover in this area is monitored.
Indian summer monsoon versus mid-latitude drivers of boreal summer tropospheric circulation and heat extremes in the eastern Mediterranean
Authors: Di Capua Giorgia , Diedrich Dominik , Tyrlis Evangelos , Matei Daniela , Donner Reik V.
Published: February 2023

The lower tropospheric circulation over the eastern Mediterranean during boreal summer is markedly characterized by northerly winds known as the Etesians (Tyrlis et al., 2013). These winds are accompanied by large scale subsidence and clear skies, and can mitigate the emergence of heat waves by bringing colder air from the Eurasian landmass. Here, we employ Causal Effect Networks, obtained by applying the Peter and Clark Momentary Conditional Independence (PCMCI) causal discovery algorithm (Runge, 2018), to identify causal precursors of the Etesians both in mid-latitude circulation fields and tropical convective activity at two different intraseasonal time scales (3 and 7-day average). We identify wave train activity over the North Atlantic and North American region and convective activity over the Arabian Sea and western coast of the Indian peninsula to be causal precursors of Etesians winds defined as 850 hPa meridional wind variations over the eastern Mediterranean at a lag of 3-to-6 days. In general, the influence of tropical drivers, i.e. the Indian summer monsoon (ISM) system,  is found to be stronger than that of the mid-latitude wave train, thus corroborating the hypothesis that the ISM affects the circulation over the Mediterranean and Northeast Africa, as suggested by the monsoon-desert mechanisms (Rodwell and Hoskins, 1996). Moreover, at longer time scales (7 to 14-day lag), the main causal influence comes from tropical convective activity over the Indian peninsula, while the effect of the mid-latitude circulation weakens and becomes not significant. We finally employ event coincidence analysis to explore the relationship between Etesians and heat extremes in the eastern Mediterranean and assess the presence of trends in the strength of Etesians outbreaks at intraseasonal variability in the historical period.ReferencesRodwell, M. J. and Hoskins, B.: Monsoons and the dynamics of deserts, Q. J. R. Meteorol. Soc., 122, 1385–1404, 1996.Runge, J.: Causal network reconstruction from time series: From theoretical assumptions to practical estimation, 28, 075310, https://doi.org/10.1063/1.5025050, 2018.Tyrlis, E., Lelieveld, J., and Steil, B.: The summer circulation over the eastern Mediterranean and the Middle East: Influence of the South Asian monsoon, Clim. Dyn., 40, 1103–1123, https://doi.org/10.1007/s00382-012-1528-4, 2013.
Slab tear and rotation imaged with core-refracted shear wave anisotropy
Authors: Petrescu Laura , Mihai Andrei , Borleanu Felix
Published: February 2023

We investigate the complex flow field around the Vrancea slab in Romania, a steeply sinking seismogenic lithospheric block that experienced lateral tear-off and possible rotation. The Vrancea slab is located beneath the South-East Carpathians and generates frequent seismicity despite its remote location from active collisional boundaries. We analyse core-refracted shear wave (SKS) splitting recorded by permanent broadband seismic stations from the Romanian Seismic Network for periods up to 10 years, and compare our results with seismic tomography of the upper mantle. We identify several stations with large backazimuthal variations of SKS fast axis polarization and delay times both in the slab hinge zone, the back-arc and the circumslab region, indicating complex mantle deformation patterns. To investigate the effect of a two-level rotated slab we invert SKS waveforms using cross-convolutional misfit combined with a neighbourhood search algorithm to model two layers of anisotropy. In the shallow mantle, anisotropy aligns with the upper slab strike and reorients along the strike of the lower slab at depths below the hinge zone. In the backarc trench-perpendicular anisotropy switches to trench-parallel, due to the recent retreat and roll-back of the slab. Our results have important implications for understanding SKS interference from subducted slab fragments and provide evidence of the recent retreat, break-off and rotation of two Vrancea slab levels sinking into the upper mantle.
Constraining the limits to magma chamber evacuation during explosive eruptions
Authors: Berlie Nicolas , Kaus Boris J. P. , de Silva Shanaka L.
Published: February 2023

Only a fraction of the magma generated in the earth finds its way to the surface during volcanic eruptions, while most of it will cool down and crystallize at different depths in the crust. Of particular interest is the pre-eruptive level, typically between 10km to 2km. Here, understanding the ratio erupted vs non-erupted magma has implications for volcanic eruption forecasting, long-term magmatic evolution, pluton formation, volcanic cyclicity, and post-eruptive geophysical monitoring. With a special focus on crystal-rich or mushy magmas, we address this problem by exploring, once a conduit reaches the surface, how efficiently the magma reservoir gets depleted and what regions of the reservoir are affected. We address those questions here using an unstructured finite element code, Gridap, written in Julia (Badia et al. 2020).Results show that several modes of magma advection exist including the classical pipe flow mode where a new batch of magma added to a mush chamber moves through a dike to the surface. Yet, several other modes also exist, which include a Stokes flow mode where magma does not make it to the surface despite a pre-existing open connection, and various intermediate modes. We use the numerical simulations to determine how magma rising speeds depends on the material and geometrical parameters such as magma and mush viscosities, or sizes of the magma batch, mush chamber or dike widths. As the numerical simulations cannot be performed for the full range of realistic magma viscosities, we use them to derive scaling laws for each of the mechanical deformation modes. These scaling laws can be used to extrapolate results to natural conditions, and highlight the key controlling parameters that determine whether melt buoyancy will result in an eruption or not. Importantly, it shows that there are physical limits to the volume of magma that can be erupted from a newly added batch of magma in a mush chamber. We will discuss the application of the results to natural cases. References citedBadia, S., & Verdugo, F. (2020). Journal of Open Source Software, 5(52), 2520.
PickBlue: Seismic phase picking for ocean bottom seismometers with deep learning
Authors: Bornstein Thomas , Lange Dietrich , Münchmeyer Jannes , Woollam Jack , Rietbrock Andreas , Barcheck Grace , Grevemeyer Ingo , Tilmann Frederik
Published: February 2023

Detecting phase arrivals and pinpointing the arrival times of seismic phases in seismograms is crucial for many seismological analysis workflows. For land station data machine learning methods have already found widespread adoption. However, deep learning approaches are not yet commonly applied to ocean bottom data due to a lack of appropriate training data and models. Here, we compiled a large and labeled ocean bottom seismometer dataset from 15 deployments in different tectonic settings, comprising ∼90,000 P and ∼63,000 S manual picks from 13,190 events and 355 stations. We adapted two popular deep learning networks, EQTransformer and PhaseNet, to include hydrophone recordings, either in isolation or in combination with the three seismometer components, and trained them with the waveforms in the new database. The performance is enhanced by employing transfer learning, where initial weights are derived from models trained with land earthquake data. Our final model, PickBlue, significantly outperforms neural networks trained with land stations and models trained without hydrophone data. The model achieves a mean absolute deviation (MAD) of 0.06 s for P waves and 0.10 s for S waves. We integrate our dataset and trained models into SeisBench to enable an easy and direct application in future deployments.
Characterising recent drought events in the context of dry-season trends using current reanalysis and remote-sensing soil moisture products
Authors: Hirschi Martin , Crezee Bas , Dorigo Wouter , Seneviratne Sonia I.
Published: February 2023

Drought events have multiple adverse impacts on environment, society, and economy. It is thus crucial to monitor and characterise such events. Here, we compare the ability of selected current reanalysis and merged remote-sensing products to represent major seasonal and multi-year drought events of the last two decades globally. We consider the ERA5, and the related ERA5-Land, as well as the MERRA-2 reanalysis products, and the ESA CCI, and the corresponding near-real time C3S remote-sensing soil moisture products (both encompassing an ACTIVE, a PASSIVE and a COMBINED product). In addition, an ESA CCI-based root-zone soil moisture estimate derived from the COMBINED product is used. The considered products offer opportunities for drought monitoring since they are available in near-real time.We focus on soil moisture (or agroecological) drought and analyse documented events within pre-defined spatial and temporal bounds derived from the scientific literature. Based on standardised daily anomalies of surface and root-zone soil moisture, the drought events are characterised by their magnitude, duration, spatial extent, and severity (i.e., the combination of duration and standardised anomalies below -1.5).All investigated products capture the investigated drought events. Overall, responses of surface soil moisture are weakest for the ACTIVE remote-sensing products in all metrics. The magnitudes (i.e., the minimum of the standardised anomalies over time) are also reduced in MERRA-2. This is also the case for the spatial extents of most of the remote-sensing products. These differences in drought severity and magnitude for single events are also consistent with inter-product differences in dry-season trends in soil moisture, which are diverse and party contradictory. In the case of MERRA-2, the reanalysis shows regional biases in surface air temperature trends compared to a ground observational product, which suggests that this reanalysis product underestimate drought trends. In the case of the microwave remote sensing products, their lower penetration depth compared to that of the top layer of the involved land surface models, as well as sensing issues of active microwave remote sensing under very dry conditions are likely to explain their partly weaker drought responses. In the root zone (based on the reanalysis products and the ESA CCI root-zone soil moisture estimate), the drought events often show prolonged durations, but weaker magnitudes and smaller spatial extents. Based on the overall observational evidence and the consideration of the respective performance and limitations of the included products, the present analyses suggest a consistent global tendency towards drying during the last two decades in several regions.
Exploring the potential of 3D diffraction imaging for GPR data
Authors: Klahold Johanna , Schwarz Benjamin , Bauer Alexander , Irving James
Published: February 2023

Diffraction imaging has become an established tool in exploration seismology thanks to its potential to provide high-resolution information that is complementary to that contained in the corresponding reflected wavefield. In ground-penetrating radar (GPR) research, data processing schemes often neglect the diffracted wavefield, focusing instead on higher-amplitude reflected arrivals. However, these data typically contain a rich diffraction background due to the structural complexity of the near surface environment. Whereas the application of diffraction imaging to 2D GPR data has already been demonstrated, the potential of diffraction imaging for 3D GPR data is still underexplored. Building on recent studies, we adapt a coherence-based diffraction imaging workflow, originally designed for seismic data, to common-offset GPR data. The first step of the proposed scheme is the separation of diffracted arrivals from the often predominant reflections, i.e. the faint diffracted portion of the data is separated and made accessible for dedicated processing. To this end, we approximate the reflected wavefield in a fully data-driven fashion by means of a coherent stacking scheme, and we subtract it from the data. The remaining diffracted wavefield can then be further enhanced through a second local coherent stacking procedure. Ultimately, wavefield focusing of the diffraction-only data yields an image of the distribution of subsurface scatterers.The above-described analysis is applied to a range of 3D GPR data sets in an exploratory fashion. The localization of diffracting structures in these data sets provides valuable additional information about small-scale subsurface heterogeneities that can complement standard reflection analyses.
The effect of Natural Halogens on Tropospheric Ozone Chemistry in the Pre-Industrial vs Present-Day
Authors: Barrera Javier A. , Kinnison Douglas E. , Fernandez Rafael P. , Lamarque Jean-François , Cuevas Carlos A. , Tilmes Simone , Saiz-Lopez Alfonso
Published: February 2023

Halogens (I, Br and Cl) emitted from natural sources catalytically destroy a fraction of tropospheric ozone, a trace gas that plays a key role in atmospheric chemistry, both as a greenhouse gas and as a component of photochemical smog, affecting air quality and public health. Previous studies have explored the effect of halogens on ozone in present-day (PD) and future time, while the role of halogens in pre-industrial (PI) ambient conditions is quite uncertain. We use the Community Atmospheric Model with Chemistry (CAM˗Chem) to explore the effect of both natural sources and chemistry of halogens on tropospheric ozone in the PI and PD. The model results show that natural halogens have comparatively a larger impact on ozone under less polluted atmospheric conditions, with percentage changes in tropospheric ozone burden (TOB) of ˗14% for PI and ˗13% for PD. Individually, the role of iodine in ozone destruction is equivalent in both periods (ΔTOBI: ˗7%). Bromine plays a larger role in PI (ΔTOBBr: ˗5%) vs. PD (ΔTOBBr: ˗4%), while chlorine plays a larger role in PD (ΔTOBCl: ˗2.5% vs. ˗2%). The increase in anthropogenic ozone precursor emissions from PI to PD drives an enhancement in the inorganic halogen budget, as well as a change in the partitioning of inorganic halogens, shifting from reactive (X+XO, X= I, Br or Cl) to reservoirs (e.g. HOX and XONO2) species. Consequently, model results show that the halogen-mediated ozone depletion in the global lower troposphere is higher in PI than in PD. This study highlights the importance of including a complete chemical representation of natural halogens in chemistry-climate models to adequately assess their effects on tropospheric ozone in a changing climate
Water storage variations in a forest during a sequence of dry years: integrative monitoring with a superconducting gravimeter
Authors: Güntner Andreas , Reich Marvin , Rasche Daniel , Blume Theresa , Schröder Stephan , Brachmann Erik , Gebauer André , Wziontek Hartmut
Published: February 2023

Terrestrial gravimetry allows for integrative measurements of mass changes associated with water storage variations in all storage compartments above and below the Earth surface. Superconducting gravimeters (SGs) currently are the most precise instruments for continuous monitoring of gravity change. Their footprint typically covers a radius of about 1 km around the instrument, with most of the signal originating from within the first 100 meters. We installed a SG (iGrav033) in a mixed pine-beech-oak forest in the TERENO observatory in the lowlands of north-eastern Germany. It is housed in a small field enclosure with less than 1 m2 base area, on top of a stable concrete pillar. Complementary hydro-meteorological monitoring data are available at the site, including a weather station, a groundwater monitoring well, clusters of soil moisture sensors along deep soil profiles, interception measurements and near-surface soil moisture from Cosmic Ray Neutron Sensing. For quantification and correction of the long-term instrumental SG drift, repeated measurements with an FG5 absolute gravimeter were carried out. The gravity residual time series (gravity measurements reduced to the local hydrological effect) covers a sequence of years with below average precipitation, from 2018 to 2022. We show the gravity-based water storage variations in the forested landscape throughout this period, indicating that storage depletion during summer in most years is not fully recovered by the subsequent wetter winter periods. The amplitudes of gravity-based water storage variations tend to exceed those observed by soil moisture sensors in the top meters of the soil and of groundwater. This indicates the value of terrestrial gravimetry in revealing dynamics of the deeper unsaturated zone water storage.
From Romans to the Anthropocene: Geoarchaeological Investigations in the Central Vienna Basin (Austria)
Authors: Weissl Michael , Hatzenbühler Diana , Baumgartner Christian , Wagreich Michael
Published: February 2023

The project »From Romans to the Anthropocene, from Carnuntum to Vienna: An Urban Anthropocene Field Lab« (WWTF ESR20-027) focuses on the urban transformation from the Roman legionary camps of Carnuntum and Vindobona to Vienna's periurban areas. Combining historical and geoarchaeological methods, we investigate the diverging development of the two sites and their manifold relations over time. The Danube river crosses the mountain ranges of the Wienerwald and Malé Karpaty, forming the eastern and western limits of the central Vienna Basin. For many centuries, the river was both a barrier and a transportation route. The floodplains and river terraces along the Danube served as concentration areas and battlegrounds during countless conflicts between central Europe and its enemies. The legionary camps of Carnuntum and Vindobona were built during the first century AD at the rim of glacial river terraces, next to the shortest passages across the Danube. During late antiquity, the former provincial capital Carnuntum lost importance. However, Vindobona became first a local center and later the capital of the Austrian rulers. After a sudden Turkish siege in 1529, the fortifications of Vienna were strengthened and maintained until the middle of the 19th century.Urban development of the region over the centuries was limited not only by permanent military threats. North of the Danube, agriculture was always restricted climatically by aridity and sand drift. Most settlements on the riverbanks of the Danube and its tributaries were affected frequently by floods and erosion. Many villages vanished completely as a consequence of such natural hazards. Since some decades, natural river dynamics have been restricted technically, and many areas under cultivation are now irrigated artificially. The analysis of the sedimentary record downstream of Vienna clearly shows the anthropogenic impact on sedimentation processes. Contrary to Carnuntum, Vienna could evolve from a legionary camp step by step into a capital and a strong fortress. The demolition of the city walls after the middle of the 19th century, the following long period of peace, and, in particular, the consequent river engineering, were preconditions for the development into a modern metropolis.
SEEP - Building a SEabed Environmental baseline for Platform abandonment
Authors: Prins Lasse Tésik , Lauridsen Bodil Wesenberg , Clausen Ole Rønø , Røy Hans , Kjeldsen Kasper Urup , Knutz Paul
Published: February 2023

As societies gradually shift from oil and gas to renewable energy, many offshore wells will be plugged and abandoned, while some will be transformed to facilitate carbon storage (CCS). In order to mitigate any methane leakage associated with abandonment, it is necessary to understand whether the leakage has a natural or anthropogenic origin. During exploration and production, emphasis is almost exclusively on the reservoir, while post abandonment monitoring programs generally focus on the water column. Thus, only little attention has been given to the shallow subsurface, how it has been influenced by hydrocarbon production, and to which degree the geology facilitates or inhibits fluid migration. In order to monitor and evaluate future leakage of hydrocarbons to the marine environment, it is crucial to understand the natural seepage through the seabed both locally at platforms and regionally. For CCS, understanding the shallow subsurface is equally important as monitoring cannot be confined to the water column alone. Mapping potential migration paths is thus necessary in order to mitigate any leakage. The aim of the SEEP project is to develop a Danish North Sea baseline for methane seepage in the shallow subsurface, near oil and gas platforms and in areas without any hydrocarbon production. Applying such a baseline will facilitate identification of anthropogenic seepage and thus help recognize the potential local environmental impact associated with abandonment. Using newly collected geophysical data, we have categorized various types of shallow methane seeps, and placed them in a geological context. By combining the shallow seismic data with deep industry seismic data, we have identified potential sources and paths for thermogenic methane migrating from reservoir depths.  The geophysical data is then integrated with results from sediment core analysis. These include Facies analysis of cores, dating of sediments, benthic faunal variations between core sites, geochemistry of bivalves and foraminifera, studies of the chemical and isotopic composition of the dissolved gas in the pore water, as well as the community-composition of gas-degrading bacteria.This integrated approach will provide a solid model for gas distribution, frequency and origin, as well as impact on the environment in the shallow subsurface.    Here we present the different tools that are the foundation of such a baseline, including results and examples from geophysical mapping (both multibeam echosounder and seismic data), biostratigraphy, geochemistry and geomicrobiology.  
Trend analyses and characterization of discharge patterns of Austrian springs
Authors: Seelig Magdalena , Seelig Simon , Eybl Jutta , Winkler Gerfried
Published: February 2023

Climate change alters the processes and components of the global water cycle. With about 50 % of the Austrian water supply depending on springs, the response of spring discharge to changes in climate is a key question of sustainable water resources management. The monitoring system of the Hydrographic Service of Austria provides long-term data of 94 springs distributed over whole Austria. With this study we provide trend analyses related to climate change and statistical analyses of spring discharge patterns related to their runoff characteristics on a national scale. The analyses account for the structure of the time series and address requirements of objectivity, transparency and reproducibility. Trend significance is assessed employing the seasonal Mann-Kendall test, and trend magnitude is calculated by the Theil-Sen slope. Autocorrelation function and pardè coefficient are calculated for each spring, similarities are explored using cluster analysis and set in a regional context. The results identify spatiotemporal patterns across Austria and highlight the significance of accurate spring flow characterization with regard to future challenges of water resources management.
Gravity wave signatures in mesospheric/lower thermospheric winds caused by Hunga Tonga-Hunga Ha‘apai volcanic eruption identified by CONDOR and the Nordic Meteor Radar Cluster
Authors: Stober Gunter , Liu Alan , Kozlovsky Alexander , Qiao Zishun , Tsutsumi Masaki , Gulbrandsen Njål , Nozawa Satonori , Lester Mark , Belova Evgenia , Kero Johan , Mitchell Nicholas
Published: February 2023

Gravity waves are a major source of the middle atmospheric short-term variability. The Hunga Tonga-Hunga Ha‘apai volcanic eruption provided a unique opportunity to study gravity wave propagation around the globe from a well-defined source. The eruption triggered several atmospheric signatures including a lamb wave (troposphere/stratosphere/mesosphere) and a package of gravity waves. Here we present results of gravity wave signatures found in mesospheric winds leveraging multi-static meteor radar networks such as the Nordic Meteor Radar Cluster and CONDOR. We were able to identify the eastward and westward propagating gravity waves. Furthermore, it was possible to estimate the intrinsic wave properties such as a horizontal wavelength of approximately 1600-2000 km and an intrinsic phase speed of 200 m/s.
Tipping Points: A challenge for climate change projections
Authors: Stocker Thomas
Published: February 2023

Multiple equilibria are found in all members of the hierarchy of climate models, ranging from simple planetary energy balance models to fully coupled general circulation models. They arise from the physical and biogeochemical coupling of different climate system components, and hence they are a general feature of planetary dynamics. Transitions from one equilibrium to another can be triggered by a temporary perturbation of the system which crosses a tipping point. Greenland ice cores and many other paleoclimate archives have abundantly demonstrated that the Earth System had limited stability during the last ice ages and that tipping has occurred in the past. A particularly dynamic period was the transition from the last ice age to the present. We present recent model simulations that reconcile different paleoceanographic indicators and so permit the quantitative reconstruction of the transient changes of the Atlantic meridional overturning circulation. This circulation may also tip in the future depending on the level and rate of increases in greenhouse gas concentrations. However, reducing the uncertainties where such tipping points lie and how close the climate system is to them, requires much better resolved climate models.The tipping of regional systems has come into recent focus because the impacts on humans and ecosystems may be substantial. Among them are the various monsoon systems, parts of the Antarctic ice sheet, shifts in the statistics of extreme climate and weather events, the extent of the Amazon rain forest, or the grassland distribution in Eastern Africa, and hence biodiversity. Such changes would all have regional consequences that are not yet reflected in current climate change projections.Therefore, regional tipping needs to be assessed systematically by the scientific community using a new generation of climate models at kilometer-scale resolution. A cross-working group IPCC Special Report on “Climate Tipping Points and Consequences for Habitability and Resources” in its forthcoming 7th assessment cycle would help strengthening a consensus on this topic and trigger the much needed advances in scientific understanding to more comprehensively inform adaptation and mitigation strategies. 
Variations of tidal waves in the Mesosphere and Lower Thermosphere over China region
Authors: Li Na , Chen Jinsong , Wang Xiaobin , Tang Zhimei , Ding Zonghua
Published: February 2023

Wind observations by Meteor radars from the year of 2009 to 2018 are utilized to knowledge the climatological characteristics at Mohe (53.1N), Beijing (40.3N), Wuhan (30.5N), Kunming (25.6N) and Sanya (18N). The tidal components with the period of 24h (diurnal), 12h (semidiurnal) are derived by the decomposition of observations using harmonic fitting method. The results show that the magnitude of diurnal tidal amplitude in the zonal and meridional winds increases with decreasing latitude, especially for the meridional wind. Annual and semi-annual changes dominate the main features. However, large difference of annual and semi-annual changes between the zonal and meridional could be seen clearly. Moreover, the diurnal tidal amplitude in the zonal wind at Mohe shows opposite changes above 90km and below 88 km, which is that the amplitude displays large value below 88km during February and March, while small value is prevailing above 90km during this time. When the diurnal amplitude above 90km is large accompanying with small value below 88 km. For the semidiurnal tide, the annual variation is clearly found for the zonal and meridional winds in their amplitudes at all stations. Meanwhile, the magnitude of semidiurnal tidal amplitude decreases with decreasing latitude, and that of meridional amplitude is larger than that of zonal amplitude. At all stations, the zonal diurnal tidal amplitude at Wuhan is largest above 88km in Spring and 94 km in Summer, that at Kunming is largest below 92 km in autumn and winter. The meridional diurnal amplitude at Sanya is biggest above 88 km in four seasons, and that at Kunming is biggest below 86 km in four seasons. For all seasons, the amplitudes in the zonal and meridional winds at Mohe are smallest. For the zonal wind, semidiurnal tidal amplitude at Beijing is largest at 82 – 94 km in Spring, 82 – 96 km in Summer, above 92 km in Autumn. Meantime, the semidiurnal tidal amplitude at Mohe is larger above 94 km and below 82 in Spring, above 96 km and 82 km in Summer, below 90 km in Autumn and at all heights in Winter. Simultaneously, the semidiurnal tidal amplitude at Sanya is smallest in Spring, Summer, Autumn and above 98 km in Winter. However, the variation of meridional semidiurnal tidal amplitude becomes complicated.
Experiences from storm surge flood damage modelling driven by local decision makers
Authors: Drews Martin , Halsnæs Kirsten , Skougaard Kaspersen Per , Ankjær Nielsen Bodil
Published: February 2023

A large part of the current research on flood damage costs build on a similar methodological framework across studies that integrates climate data (hazard), flood modelling (exposure), damage cost assessments (impact) and calculate risks as the product of the likelihood of events and their consequences. A key question here is how relevant such a methodological framework is in relation to the perspectives of decision makers on establishing safe standards for investments in climate change adaptation in the context of the large uncertainties surrounding both estimates of the extreme event probability and on the damages of these. Particular issues that are often raised by decision makers are related to how extreme precipitation and storm surge levels could be, and on how well the damages of such events are represented in damage estimates recognizing the limitations of monetary evaluations as well as risk preferences of decision makers.The paper is addressing how the gap between conventional approaches applied to hazard and impact modelling and the needs and practice of decision makers can be diminished based on the experiences with the development and application of a detailed object based spatial DamageCost Model for storm surges. The model has been widely applied by Danish local governments as a basis for developing adaptation plans. Soon after the first version of the model was released, local Danish governments took over leading the model development from a user perspective in a close ongoing dialogue with DTU and the engineering consultants LNH Water, which through several projects, including the EU ARSINOE project continue to support further technical development and model use.Experiences from how the model development have been inspired by decision maker perspectives gained through model use are reported based on case studies for the Danish cities of Esbjerg, Odense, and Aabenraa.