bluuebunny/crossref_metadata_2025 huggingface dataset:
Seismic anisotropy beneath the western part of the Carpathian-Pannonianregion inferred from combined SKS splitting and mantle xenolith studies
Authors: Liptai Nóra , Gráczer Zoltán , Szanyi Gyöngyvér , Süle Bálint , Aradi László , Falus György , Bokelmann Götz , Timkó Máté , Timár Gábor , Cloetingh Sierd , Szabó Csaba , Kovács István ,   AlpArray Working Group
Published: March 2022

Information on mantle anisotropy can be obtained from methods such as
studying the lattice-preferred orientation (LPO) in mantle peridotites,
or conducting shear-wave splitting (SKS) analyses which allow to
determine whether it is a single or multi-layered anisotropy and the
delay time of the fast and slow polarized wave can indicate the
thickness. In this study we provide a detailed SKS mapping on the
western part of the Carpathian-Pannonian region (CPR) using an increased
amount of splitting data, and compare the results with seismic
properties reported from mantle xenoliths to characterize the depth,
thickness, and regional differences of the anisotropic layer in the
mantle.
According to the combined SKS and xenolith data, mantle anisotropy is
different in the northern and the central/southern part of the western
CPR. In the northern part, the lack of azimuthal dependence of the fast
split S-wave indicates a single anisotropic layer, which agrees with
xenolith data from the Nógrád-Gömör volcanic field. In the central
areas, multiple anisotropic layers are suggested by systematic azimuthal
variations in several stations, which may be explained by two,
petrographically and LPO-wise different xenolith subgroups described in
the Bakony-Balaton Highland. The shallower layer is suggested to have a
‘fossilized’ lithospheric structure, which could account for the
occasionally detected E-W fast S-orientations, whereas the deeper one
reflects structures responsible for the regional NW-SE orientations
attributed to the present-day convergent tectonics. In the Styrian
Basin, results are ambiguous as SKS splitting data hints at the presence
of multiple anisotropic layers, however, it is not supported clearly by
xenolith data.
Spatial coherency analysis of the splitting parameters put the center of
the anisotropic layer at ~140-150 km depth under the Western
Carpathians, which implies a total thickness of ~220-240 km. Thickness
calculated from seismic properties of the xenoliths resulted in lower
values on average, which may be explained by heterogeneous sampling by
xenoliths, or the different orientation of the mineral deformation
structures (foliation and lineation).
Reactive oxygen species control mineralization in permeable intertidal sediments
Authors: van Erk Marit , Bourceau Olivia , Moncada Chyrene , Basu Subhajit , Hansel Colleen , de Beer Dirk
Published: March 2022

We investigated the influence of reactive oxygen species (ROS) on microbial mineralization in intertidal permeable sediments. These sediments are crucial for coastal carbon cycling. Permeable intertidal sediments are further prone to variable surface oxygenation and active iron-sulfur cycling, and are therefore likely sites of intense ROS formation. We incubated sediment slurries from an intertidal sandflat in the German Wadden Sea over a transition to anoxic conditions, and found that removal of ROS by enzymes increased rates of aerobic and anaerobic respiration, including sulfate reduction. We additionally found high concentrations of the ROS hydrogen peroxide in sediment porewaters. Sulfate reduction was absent during the oxic period, but directly resumed upon anoxia.

This study shows the regulating effect of ROS on microbial mineralization and the impact of ROS and transient oxygenation on marine sediment biogeochemistry.
Graphical analysis applications to study variability and trends of rainfall and streamflow in Colombian catchments
Authors: Montenegro Gambini Julio Isaac , Cusipuma Ayuque Magaly
Published: March 2022

Monitoring trends and continuous changes to complement local studies on discharge and precipitation are becoming increasingly important, assessing systematically its temporal and spatial variation characteristics. It is also necessary to provide detailed study on the driving mechanisms of those variations, which can be a result of anthropogenic activities as it specifically affects particular regions and terrains. These data play very significant roles in measuring and forecasting potential impacts and lead to future improved regional flow regulations for better water resources management. One of the most effective methods for observing the effects of climate change on hydrometeorological variables is the trend analysis, with recently new graphical methods that represents an innovative alternative to the classical ones. In this work, mean monthly, annual mean, minimum and maximum precipitation was examined to analyze spatiotemporal variations, seasonality shifts and trends with records that can extend from 1910 to 2019 in the hydrometeorological network. The flow discharge were also analysed considering catchments with unimpaired streamflow in unregulated rivers. Different homogeneity and shift detection methods were used to check their homogeneity before conducting trend analysis. Innovative Polygon Trend Analysis (IPTA), Innovative trend analysis (ITA) with the Significance Test and Mann-Kendall (MK) non-parametric methods were compared, showing their sensitivity and their ability to explain a monthly trend sequence and periodicity in the studied region in order to explain adequately the temporal internal variability.
Science building on synthesis: From standardized palaeoclimate data to climate model evaluation
Authors: Rehfeld Kira
Published: March 2022

Efforts towards standardizing biogeochemical data from palaeoclimate archives such as speleothems, ice cores, corals, trees or marine sediments allow to tackle global-scale changes in palaeoclimate dynamics. These endeavours are sometimes initiated for very specific research questions. One such example is the multi-archive, multi-proxy dataset used in a characterization of changes in temperature variability from the last Glacial Maximum to the current Interglacial [1]. Here, we focused on collecting all published proxy time series for temperature that fulfilled sampling criteria, but we did not include a lot of metadata.

Another, quite prominent, example is the database that grew out of the working group on Speleothem synthesis and analysis (SISAL) in the Past Global Changes (PAGES) network. In its construction, researchers from all over the world collaborated, producing a quality-controlled data product with rich metadata. SISAL v2 [2] contains data from 691 speleothem records published over the decades, for more than 500 standardized age models were established. The design and data collection in the community allowed to draw together metadata and observations to reproduce the age modeling process of individual studies. This database has a rich set of purposes, ranging from the evaluation of monsoon dynamics, to that of isotope-enabled climate models [3].

Contrasting these two approaches I will discuss the challenges arising when multiple proxies, archives, modeling purposes and community standards need to be considered. I argue that careful design of standardized data products allows for a new type of geoscience work, further catalyzed by digitization, forming a basis for tackling future-relevant palaeoclimatic and palaeoenvironmental questions at the global scale. 

 

[1] Rehfeld, K., et al. "Global patterns of declining temperature variability from the Last Glacial Maximum to the Holocene." Nature 554.7692: 356-359, https://doi.org/10.1038/nature25454, 2018

[2] Comas-Bru, L., et al. (incl. SISAL Working Group members): SISALv2: a comprehensive speleothem isotope database with multiple age–depth models, Earth Syst. Sci. Data, 12, 2579–2606, https://doi.org/10.5194/essd-12-2579-2020, 2020.

[3] Bühler, J. C. et al: Comparison of the oxygen isotope signatures in speleothem records and iHadCM3 model simulations for the last millennium, Clim. Past, 17, 985–1004, https://doi.org/10.5194/cp-17-985-2021, 2021.
Spatially adaptive Bayesian estimation for Probabilistic Temperature Forecasts
Authors: Möller Annette , Thorarinsdottir Thordis , Lenkoski Alex , Gneiting Tilmann
Published: March 2022

To account for forecast uncertainty in numerical weather prediction (NWP) models it has become common practice to employ ensemble prediction systems generating probabilistic forecast ensembles by multiple runs of the NWP model, each time with variations in the details of the numerical model and/or initial and boundary conditions. However, forecast ensembles typically exhibit biases and dispersion errors as they are not able to fully represent uncertainty in NWP models. Therefore, statistical postprocessing models are employed to correct ensembles for biases and dispersion errors in conjunction with recently observed forecast errors.

For incorporating dependencies in space, this work proposes a spatially adaptive extension of the state-of-the-art Ensemble Model Output Statistics (EMOS) model. The new approach, named Markovian EMOS (MEMOS), introduces a Markovian dependence structure on the model parameters by employing Gaussian Markov random fields. For fitting the MEMOS model in a Bayesian fashion the recently developed Integrated Nested Laplace Approximation (INLA) approach is utilized, allowing for fast and accurate approximation of the posterior distributions of the parameters. To obtain physically coherent forecasts the basic MEMOS model is provided with an additional spatial dependence structure induced by the Ensemble Copula Coupling (ECC) approach, which makes explicit use of the rank order structure of the raw ensemble.

The method is applied to temperature forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF) over Europe, where it exhibits comparable or improved performance over univariate EMOS variants.
Evolution of Cold Subpolar North Atlantic Conditions in the Past Decade
Authors: Josey Simon , Sinha Bablu
Published: March 2022

The eastern North Atlantic subpolar gyre has become a focus of research in recent years, partly in response to the extreme cold anomaly (the 2015CA) that developed in winter 2013-14, peaked in 2015 and persisted in a weakened state for several years. The anomaly was evident both in sea surface temperature which exceeded 1.0 oC of cooling averaged over 2015 as a whole and in reduced temperatures at depth to of order 500 m. Here, we place it in a longer-term context by considering other anomalies in the observational record since 1980 and discuss its subsequent evolution through to 2022. We also explore the role played by large scale atmospheric modes of variability, particularly the East Atlantic Pattern (EAP) and North Atlantic Oscillation (NAO), in generating such anomalies. Furthermore, we draw a connection between the combined influence of these modes on both the eastern subpolar gyre and intense heat loss in the Irminger Sea which potentially leads to a coupling of mode and dense water formation processes in these two key North Atlantic regions.
Flood-regulation promotes salt-marsh drowning  and enhances loss of geomorphic diversity in shallow tidal embayments
Authors: Finotello Alvise , Tognin Davide , D'Alpaos Andrea , Viero Daniele Pietro , Pivato Mattia , Mel Riccardo , Defina Andrea , Bertuzzo Enrico , Marani Marco , Carniello Luca
Published: March 2022

Flood-regulation systems and storm-surge barriers are increasingly adopted to protect many coastal cities worldwide from the flooding hazard related to rising sea levels. Eminent examples include London, the Netherland, New Orleans, St. Petersburg, and Venice. Regulating the propagation of surges and tides, barriers will also change sediment transport, thus modifying the morphological evolution of estuarine systems nearby the protected urban areas. However, how the morphodynamic evolution of tidal environments will be affected by flood regulation is still an unresolved question.

We investigate the effect of the recently-activated storm-surge barriers designed to protect Venice (Italy) from flooding on the morphological evolution of the Venice Lagoon, combining numerical modelling and field data.

Artificially reduced water levels affect the interaction between tide and waves, enhancing sediment resuspension on tidal flats. Accumulation of resuspended sediments on salt marshes however is hindered by the reduced flooding intensity owing to lower water levels, thus potentially undermining marsh ability to keep pace with rising sea levels. Simultaneously, eroded sediments tend to accumulate within channels, thus mining water exchange and increasing dredging costs.

Over longer (i.e., seasonal) timescales, we suggest that although barrier closures reduce net sediment export toward the open sea, this does not point to preserving the characteristic lagoonal morphology, hindering salt-marsh accumulation and promoting tidal-flat deepening and channel infilling. Hence, the operation of flood barriers can trigger an important loss of tidal landforms, negatively impacting the conservation of shallow tidal environments and the ecosystem services they provide.
Expanding the interpretation of anthropogenic fire in the paleo-charcoal record through modern prescribed fires: A study of charcoal production and morphology during the 2021 Hitchiti Experimental Forest prescribed fire campaign, Georgia, USA
Authors: Snitker Grant , Strother Dexter
Published: March 2022

Differentiating between natural and anthropogenic fire activity in the past remains one of the principal challenges in interpreting paleo-charcoal records and has implications for contextualizing changing fire regimes in our world today. During the Holocene, cultural burning practices throughout the globe were motivated by diverse social institutions, values, and economics; however, the frequency, seasonality, spatial distribution, and ecological severity of global anthropogenic fire likely differed enough from natural fire to generate lasting ecological effects. Similarly, prescribed fire operations conducted by federal land managing agencies in the United States are modern examples of cultural burning to achieve desired ecological outcomes. Nonetheless, relatively few studies have utilized prescribed fires as laboratories for testing methods to interpret anthropogenic fire activity in charcoal records. In this paper, we present the results of a comprehensive study of charcoal production and morphology collected during a series of highly instrumented prescribed fires that occurred during March 2021 within the Hitchiti Experimental Forest, Georgia, USA. We relate both field-collected and lab-created charcoal datasets to pre-/post-burn vegetation inventories, thermal images capturing fire behavior, and radiometric measurement of energy release collected at 12 study plots throughout the burn area. Using this approach, we seek to expand the interpretive potential of paleo-charcoal records for identifying past anthropogenic fire activity similar to the frequent, low-severity prescribed fires practiced by land managers today.
Gain of efficiency with a new time scheme in NEMO : Runge Kutta 3rd order
Authors: Téchené Sibylle , Madec Gurvan , Chanut Jérôme , Coward Andrew , Storkey Dave
Published: March 2022

As Ocean General Circulation Models (OGCMs) become more complex, their computational efficiency remains a crucial challenge for ocean simulations. By using smart numerical choices, however, it is possible to increase the time step of an OGCM for a fixed spatial resolution, thereby reducing the computational cost and improving efficiency. To do this we are revisiting the NEMO time-stepping scheme. Modified Leapfrog  (MLF) has been used so far. We implement Runge Kutta 3rd order (RK3) from Wicker and Skamarock (2002) as an intermediate step toward a coupled space-time scheme. RK3 time stepping implemented in NEMO is a single step iterative method using a predictor-corrector like formulation. It uses three stages to integrate the model from time step n to n+1. During the first stage ( from n to n+⅓ ) we build guesses of tracers and momentum using an euler time stepping : on the one hand tracers are estimated by integrating advection terms only, on the other hand momentum are estimated by integrating advection, pressure gradient and coriolis terms only. During the second stage ( from n to n+½ ) we use n+⅓ tracers and momentum fluxes from stage 1 to build tracers and momentum guesses at n+½ using the same equations. The last stage integrates full equations from n to n+1 with n+½ tracers and momentum flux guesses from stage 2. We integrate the barotropic mode from n to n+1 at the beginning of the time step and interpolating it linearly at n+⅓ and n+½ as proposed in the accompanying paper by Lemarie et al. (2022). The new RK3 implementation is now ready to be validated in NEMO. It has been tested on most of NEMO's components : to dynamics, active tracers, sea ice, passive tracers, ice shelves, open boundaries and AGRIF zoom. Global simulations with sea ice and biogeochemistry at low resolution show that the model using RK3 is stable when doubling the time step and is almost twice as fast as MLF ( 80% speed up ). Nevertheless, some work remains before considering RK3 as fully operational in NEMO.
How do both valley head initiation and headwater catchment extent change with relief?
Authors: Chen Hui , Byun Jongmin
Published: March 2022

Headwater catchments, each of which consists of hillslopes, valley heads, and colluvial channels, make up a major portion of a drainage basin, supplying sediment, water, and nutrients downstream. In a headwater catchment, valley heads where hillslope diffusive transport transits to fluvial transport play an important role in channel initiation. Headwater catchments where mass movements are dominated are sensitive to human activities. Human activities in headwater catchments, such as logging and crop cultivation, change the rate of hillslope erosion, thereby increasing sediment inputs and leading to channel form change and stream habitat destruction. In recent years, such human activities have increased significantly in headwater catchments. As such, delineations of the extent of headwater catchment and valley head initiation become increasingly important for watershed protection and management. Previous studies have shown that the area of the headwater catchment ranges from 104 to 106 m2, but little is known about what factors affect its range. The evolution of headwater catchment topography is mainly determined by surface processes such as landslides and runoff. The rates of these processes vary depending on the hillslope gradient closely related to topographic relief. To understand the impacts of relief on the valley head initiation and the extent of headwater catchment, we analyzed the slope-area relations of the Seo River drainage in South Korea. Firstly, we found that the upslope area at the valley head shows a weak positive correlation with relief. This finding seems to be associated with hillslope material input to fill valley heads. Steep hillslopes in a high relief region could induce more hillslope material supply, consequently filling valley heads. Such abundant flux into valley heads probably enhances the hillslope length and makes valley head initiation downstream. Secondly, the upslope area of the headwater catchment, which is set by the downstream limit of the colluvial channel increased exponentially with relief. This exponential correlation would be related to the length of debris flow-dominated channel. In high relief regions where the channel slope is steeper, debris flows scour for a further distance, resulting longer colluvial channels. These results reveal the importance of relief as controls on valley head initiation and headwater catchment extent.
Nagra's Approach to Gas Release from Deep Geological Repositories
Authors: Leupin Olivier , Diomidis Nikitas , Reinicke Andreas , Papafotiou Alexandros
Published: March 2022

Geological disposal of low and intermediate-level and high-level waste in Switzerland may - due to corrosion and degradation related processes - result in the production of gas. In our presentation we will focus on the integration of gas related processes and phenomena in the safety case and site selection. In addition, we will elaborate on what technical strategies Nagra follows to limit the potentially detrimental effects on the safety related properties of the technical and natural barriers.

Geological disposal of low and intermediate-level and high-level waste in Switzerland may - due to corrosion and degradation related processes - result in the production of gas. In our presentation we will focus on the integration of gas related processes and phenomena in the safety case and site selection. In addition, we will elaborate on what technical strategies Nagra follows to limit the potentially detrimental effects on the safety related properties of the technical and natural barriers.
Comparison of tidal asymmetry descriptors – a sensitivity study based on one-year monitoring data of the Ems estuary
Authors: Wünsche Anna , Becker Marius , Jürges Jens , Kelln Jessica , Winter Christian
Published: March 2022

Estuarine management requires fundamental system understanding on drivers and effects of flow and transport dynamics. Among other system descriptors, tidal asymmetry is a fundamental prop-erty, used in many ways, e.g. to define the dominant direction of sediment transport in estuaries. There are several different parametrizations of tidal asymmetry, and the number of methods of their derivation has increased in recent years. We present an attempt to discuss comparability of descriptors for tidal asymmetry. We computed descriptors from one-year measured monitoring data of the Ems estuary. Using conformal mapping we scaled each of these for comparison. A sen-sitivity analysis shows the pronounced influence of freshwater discharge on descriptors derived from velocity data and, on the other hand, the influence of wind on quantities based on duration of tidal phases. The impact of spring neap variability changes over the estuary. Our results show that observations of short periods (e.g. two tides) are not robust compared to the average of a spring neap cycle. Finally, we conclude that the classification of the estuary in terms of flood or ebb dominant sediment transport is critically dependent on location and period of the input data. Further, we discuss how to interpret hydrodynamic parameters derived from point measure-ments. The actual characterization of an estuary requires more comprehensive data, such as var-iability over cross sections, data of suspended sediment concentration and a consideration of the entire density-driven circulation.
An Assessment Method of Squall Line Intensity Based on Cold Pool
Authors: Yang Ru , Jiang Yongqiang , Chen Chaohui , He Hongrang , Li Yi , Huang Hong
Published: March 2022

To quantify the intensity of squall line in mid-latitudes, the author recently proposed a squall line intensity assessment method based on cold pool, which provides a measure of squall line intensity.

The disturbance potential temperature density is calculated by using the potential temperature, water vapor and all kinds of water condensate output from the numerical weather forecast model, and the boundary of the cold pool is judged according to the disturbance potential temperature density less than -2K. Based on the contour surface buoyancy, the high surface buoyancy is calculated according to the disturbance potential temperature density, and then the strength of the cold pool is calculated. In this method, the intensity of squall line is analyzed comprehensively by principal component analysis, combined with the weather phenomena accompanied by squall line occurrence, such as cold pool intensity, surface wind speed, ground pressure variation, surface temperature variation, simulated radar echo and so on. The above analysis is the local intensity on different grid points when the squall line occurs, and the overall squall line intensity is obtained by accumulating the local intensity in the squall line range.

The method is verified by the model output data of a squall line process occurred in northern Jiangsu on May 16, 2013. The results show that the distribution of the local squall line intensity is coupled with the surface wind field and heavy precipitation. The intensity evolution of the overall squall line reaches the peak in a short time and then decreases, which corresponds to the life history of the birth, development, maturity and dissipation of the squall line, and also reflects the characteristics of the short life history of the squall line developing rapidly and then dissipating. This method provides technical support for the forecast of squall line and the emergency plan issued by meteorological department.

Acknowledgements. This research was supported by the National Natural Science Foundation of China (Grant Nos. 41975128 and 42075053).

Keywords: squall line, intensity, assessment method, disturbance potential temperature density
Surface salinity maximum in the western boundary of the Tropical Atlantic as observed from SMOS salinity maps
Authors: Castellanos Paola , Olmedo Estrella , Campos Edmo , Santis Wlademir , Dias Joaquim
Published: March 2022

The spatiotemporal evolutions of sea surface salinity measurements from the SMOS satellite reveal presence of a local salinity maximum in the northwestern tropical Atlantic beginning in September increasing with a Maximum in October and disappearing in January. Its structure and variability are analyzed through SMOS SSS daily products derived with advanced techniques developed at the Barcelona Expert Centre during 9 years. The results are compared with in situ data along the North Brazil Current (NBC) from the Prediction and Research moored Array in the Tropical Atlantic - PIRATA program. This seasonal tropical SSS maximum, produces the salty signature Northward of the NBC, which is seen as a localized salinity maximum on satellite imagery, in contrast to the fresh signature present in summer-early fall. These changes suggest a change in the composition of water masses that enter in the South Atlantic contributing to an alteration in the dynamics of global circulation.
Towards attributing change in tropical and subtropical precipitation
Authors: Hegerl Gabriele , Ballinger Andrew , Schurer Andrew
Published: March 2022

Precipitation changes are notoriously highly variable, and climate models misplace circulation features, making it difficult to evaluate if mechanisms of precipitation change are well reproduced in climate models. Several methods have been developed to detect externally forced precipitation change tracking circulation features rather than specific locations. For example, analysis of monthly ascending and descending regions in reanalysis show the increase of rainfall in ascending regions. Analysis of wet and dry regions in GPCP blended data shows that if the locations of wet and dry regions are tracked from month to month then trends over the past 3-4 decades can be attributed to a combination of human influences and the recovery from drying associated with the Mount Pinatubo eruption in wet regions. In response to volcanic eruptions, wet regions tend to dry and dry regions may get wetter, indicating a reduced moisture transport to the wettest regions of the tropics under strong volcanic forcing. However, this is also impacted by the hemispheric characteristics of the eruptions. 
PFAS as a test bed for the EU Green Deal zero pollution ambition from refractory and mobile organic chemicals: technologies, solutions and strategies developed under the H2020 project SCENARIOS
Authors: Dondero Francesco ,   SCENARIOS TEAM
Published: March 2022

In the last decade, per- and polyfluoroalkyl substances (PFAS) have been added to the list of pollutants of concern because they are persistent and potentially carcinogenic and have a high bioaccumulation rate. PFASs are detected in numerous environmental matrices, confirming their high persistence and mobility in the environment. In addition, the chemical structure of PFAS and their reactivity pose a technological challenge for remediation efforts. SCENARIOS is an H2020 research and innovation project involving 19 partners from 11 countries. The main objective is to fill knowledge gaps and achieve breakthrough TRL advances in toxicological assessment, congener detection and remediation of PFAS with unprecedented energy balance and virtually no external chemical additives, supporting EU countries in decision-making related to environmental safety and human health. The project will evaluate and develop state-of-the-art technologies and strategies for the detection, quantification, control, and elimination of PFAS in soil, vadose zone, and water by targeting outcomes within the 4 remediation quadrants: In-situ Soil, In-situ Water, Ex-situ Soil, and Ex-situ Water. Likewise, the project is developing a set of solutions to control pollution and remediate PFAS contaminated soils (agricultural and industrial) and groundwater. All these solutions will comply with the principle of green chemistry, zeroenergy, sustainability and circular economy. This paper presents the project progress in PFAS detection, monitoring and remediation.
Observation of acoustic normal modes of the atmosphere after the 2022 Hunga-Tonga eruption.
Authors: Widmer-Schnidrig Rudolf
Published: March 2022

The phreatic eruption of Hunga-Tonga on January 15, 2022 was so energetic that it excited globe circling air-waves. These wave packets with a dominant period of 30 minutes have been observed in single barograms even after completing at least  four orbits or 6 days after the eruption. Constructive and destructive interference between waves that have left the source region in opposite direction lead to the emergence of standing pressure waves: normal modes of the atmosphere.

 

We report on individual modes of spherical harmonic degree between 30 and 80 covering the frequency bend from 0.2 mHz to 0.8 mHz. These modes belong to the Lamb wave equivalent modes with a phase velocity of 313 m/s.  They are trapped to the Earth’s surface, decay exponentially with altitude and their particle motion is longitudinal and horizontal. The restoring force is dominated by incompressibility. 

 

In the frequency band where we observe these modes the mode branches do not cross with mode branches of the solid Earth. Hence we do not expect any significant coupling with seismic normal modes of the solid Earth. Such a crossing occurs at 3.7mHz and aboce.

 
Caldera subsidence during the Hunga-Tonga explosive eruption?
Authors: Walter Thomas R. , Cesca Simone ,   GFZ-DLR-Geomar Task Force Team
Published: March 2022

The Hunga-Tonga eruption culminated on January 15, 2022, with a high-intensity Plinian eruption exceeding 20 km height, tsunamis affecting local islands and the circumpacific region, locally air-coupled seismic surface waves recorded at teleseismic distances, and explosive shock waves that repeatedly travelled around the world. Hunga-Tonga is a flat-topped volcano that rises about 1700 m above the seafloor, hosting a submarine 3-4 km diameter caldera floor that lies at less than 200 m water depth and is surrounded by an elevated, approx. 100-200 m high caldera wall. Only small parts of the volcano are rising at the caldera wall above the sea level, such as the islands Hunga Tonga Hunga Ha'apai in the north and small unnamed rocks in the south. Satellite imagery acquired by Pleiades and Sentinel 1A suggests that during the January 15, 2022 eruption, the central part of the Hunga Tonga Hunga Ha'apai as well as the small rocks in the south disappeared. By analysing satellite radar and imagery, we constrain island perimeters and morphologies before and after the eruption, to find evidence for island subsidence and erosion. In addition, seismic data recorded during the January 15, 2022 eruption was analysed in the time and frequency domains, revealing high amplitude activity over ~1 hr. The comparison of seismic, GNSS and local tsunami recordings gives insights into the time-succession of the eruption. For instance, moment tensor inversion suggests that the largest amplitude seismic signal was produced by a dominant tensile non-double component, characteristic of volcanic explosions. Furthermore, we also found evidence for reverse polarity mechanisms in agreement with subsidence of a caldera, possibly indicating incremental activity of a ring fault. We discuss the possible contribution of a caldera to the evolving eruption dynamics and the need to improve geophysical monitoring of this island arc in general and acquire high-resolution submarine data Hunga Tonga Hunga Ha'apai in specific.
Persistence Hunga Tonga plume in the stratosphere and its journey around the Earth.
Authors: Legras Bernard , Khaykin Sergey , Podglajen Aurélien , Sellitto Pasquale ,   ASTuS
Published: March 2022

The Hunga Tonga eruption has generated an atmospheric plume rising above 40 km,  establishing an observational record. Due to the explosive nature of the eruption with a lot of water, the plume carried an unprecedented amount of water and a cloud of sulfated aerosols and possibly ultra-thin ashes was released. The aerosols have already persisted for four weeks with peak scatterring ratio initially above 200 that are still above 30 on many patches, as seen from CALIOP. These high values combined with low depolarization suggest a large amount of small sub-micronic spherical particles, confirmed by in situ balloon measurements. This is compatible with dominance of sulfated aerosols.

As the stratospheric flow has been mostly zonal with no breaking wave during the period and region of interest, and the horizontal shear dominates, the plume has been mostly dispersed in longitude keeping a similar latitudinal vertical pattern from the early days. A part has migrated to the tropical band reaching 10°N. Several concentrated patches have been preserved in particular a "mushroom" like pattern at 20S which has already circulated once around the Earth. . We will discuss the stability of this pattern in relation with vortical and thermal structures that are detected from several instruments and the meteorological analysis.

We will also discuss the likely impact on the stratospheric composition and the radiative effect on the yearly basis.  
Monitoring the local heat content change over the Atlantic Ocean with the space geodetic approach: the 4DATLANTIC-OHC Project
Authors: Fraudeau Robin , Ablain Michael , Larnicol Gilles , Marti Florence , Rousseau Victor , Blazquez Alejandro , Meyssignac Benoit , Foti Giuseppe , Calafat Francisco , Desbruyères Damien , Llovel William , Ortega Pablo , Lapin Vladimir , Rodriguez Mar , Killick Rachel , Rayner Nick , Drevillon Marie , von Schuckmann Karina , Restano Marco , Benveniste Jérôme
Published: March 2022

Given the major role of the Atlantic Ocean in the climate system, it is essential to characterize the temporal and spatial variations of its heat content. The 4DATLANTIC-OHC Project (https://eo4society.esa.int/projects/4datlantic-ohc/) aims at developing and testing space geodetic methods to estimate the local ocean heat content (OHC) changes over the Atlantic Ocean from satellite altimetry and gravimetry. The strategy developed in the frame of the ESA MOHeaCAN Project (https://eo4society.esa.int/projects/moheacan/) is pursued and refined at local scales both for the data generation and the uncertainty estimate. At two test sites, OHC derived from in situ data (RAPID and OVIDE-AR7W) are used to evaluate the accuracy and reliability of the new space geodetic based OHC change. The Atlantic OHC product will be used to better understand the complexity of the Earth’s climate system. In particular, the project aims at better understanding the role played by the Atlantic Meridional Overturning Circulation (AMOC) in regional and global climate change, and the variability of the Meridional Heat transport in the North Atlantic. In addition, improving our knowledge on the Atlantic OHC change will help to better assess the global ocean heat uptake and thus estimate the Earth’s energy imbalance more accurately as the oceans absorb about 90% of the excess energy stored by the Earth system.

The objectives of the 4DATLANTIC-OHC Project will be presented. The scientific requirements and data used to generate the OHC change products over the Atlantic Ocean and the first results in terms of development will be detailed. At a later stage, early adopters are expected to assess the OHC products strengths and limitations for the implementation of new solutions for Society. The project started in June 2021 for a 2-year duration.

Visit https://www.4datlantic-ohc.org to follow the main steps of the project.
Chaos and Predictability in vTEC time series
Authors: Materassi Massimo , Migoya-Orue Yenca , Alberti Tommaso , Radicella Sandro , Consolini Giuseppe
Published: March 2022

Modeling the Earth’s ionosphere is a big challenge, due to the complexity of the system. Any ionospheric model misses the behavior of the real system for some fluctuating component, that appears almost impossible to predict, and is particularly threatening for the human technologies (e.g., GNSS navigation). While producing models extremely rich, including many physical agents acting on the Earth’s ionosphere, it is necessary to understand whether the residual, non-modeled component is predictable in principle as a “simple" dynamical system, or is conversely so chaotic to be practically stochastic, and should be treated probabilistically.

The question of how chaotic and how predictable the time series of vertical total electron content (vTEC) are, depending on the different locations and solar activity conditions, is dealt with by employing tools of dynamical system theory.

In particular, we calculate the correlation dimension D2 and the Kolmogorov entropy rate K2 for the vTEC time series at different latitudes in both northern and southern hemispheres and during both high and low solar activity periods.

The quantity D2 is a proxy of the degree of chaos and dynamical complexity: the larger D2 is, the higher the number of dynamical variables needed to describe the phenomenon is. Instead, K2 measures the speed of destruction of the mutual information between the signal and a delayed copy of it, so that (K2)-1 is a sort of maximum time horizon for predictability.

The analysis of the D2 and K2 for the vTEC time series will then allow to give a measure of chaos and predictability of the Earth ionosphere. Being such analysis performed for different locations and different solar activity conditions, these characteristics will indicate possible differences depending on location.
Establishing the eastern alpine-dinaric transition with teleseismic receiver functions: Evidence for subducted European Crust
Authors: Mroczek Stefan , Tilmann Frederik , Pleuger Jan , Yuan Xiaohui , Heit Ben ,   SWATH-D and AlpArray Working Groups
Published: March 2022

The dense SWATH-D seismic network in the Central-Eastern Alps gives an unprecedented window into the collision of the Adriatic and European plates. We apply the receiver function method to the SWATH-D stations, covering approximately the area from 45-49°N and 10-15°E, supplemented by the AlpArray Seismic Network and the EASI data. A switch in the subduction polarity between the Central Alps (European subduction) and the Dinarides (Adriatic subduction) had been previously suggested to occur below the Eastern Alps but its location and nature are heavily debated. To probe this hypothesis we produce a high resolution Moho map of the Eastern Alps and derive Moho depths from joint analysis of receiver function images of direct conversions and multiple reflections, which enables us to map overlapping discontinuities. Contrary to the hypothesis suggesting the subduction of Adriatic lithosphere in the Eastern Alps, we observe the European Moho to be underlying the Adriatic Moho up to the eastern edge of the Tauern Window (~13.5°E). East of this longitude, a sharp transition from underthrusting European to a flat and thinned crust associated with Pannonian extension tectonics occurs, which is underthrust by both European crust in the north and by Adriatic crust in the south. The northeast-directed underthrusting of Adriatic lithosphere smoothly transitions to subduction below the northwestern Dinarides.

Teleseismic tomography and receiver functions show different aspects of the same system (velocity anomalies versus velocity gradients) making direct comparisons difficult. The common conversion point stacks and Moho picks show good agreement with the tomography however some key differences remain. In particular, teleseismic tomography indicates high velocity anomalies detached from the crust east of ~13°E while receiver functions, in particular the transverse component, show some evidence for connection with a continuous interface going to depth.
Toward the magnitude of carbon fertilization effect on total net primary production based on experiments
Authors: Zhang Huanyuan , Terrer César , Prentice Iain Colin , Keenan Trevor , Franklin Oskar , Stocker Benjamin
Published: March 2022

Recent syntheses of elevated CO2 (eCO2) experiments provide critical information to quantify the effects of rising CO2 on vegetation. However, although the eCO2 effect on aboveground biomass (βAGB) and soil carbon pool (βCsoil) have been estimated, little has been known about the eCO2 effect on total net primary production (βTNPP) - the sum of above and belowground - due to the difficulties of measuring NPP in eCO2 experiments. As a preliminary analysis of βTNPP, we ran a thorough meta-analysis of global eCO2 experiments and found that (1) Most of the experiments reported a larger βTNPP than βAGB (2) Most of the experiments reported a larger eCO2 effect on belowground (roots) biomass (βBGB) than total biomass (βTB) (for AM mycorrhizal association only) (3) On average, seedling experiments reported a larger βAGB than mature vegetation experiments. Aiming to improve estimates of βTNPP we hypothesized that βAGB could be underestimated due to short experimental time relative to biomass mean residence time, i.e., that βAGB increases with experimental time. We proposed a set of simple first kinetics equation to derive βTNPP with consideration of the imbalance between βBGB and βTB. We first validated the equations on experiments reporting both productivity and biomass before applying to other experiments. We found that, after the application, (1) On average, βTNPP of seedling experiments are insignificantly different to βTNPP of mature vegetation experiments (2) Compared with βAGB, the relative importance of mycorrhizal on βTNPP decrease, and soil CN ratio and soil phosphorus became the most important predictors. (3) The disagreement between experiments and models was smaller for βTNPP than for βAGB. 
Challenging our knowledge on flood frequency
Authors: Kauzlaric Martina , Schick Simon , Martius Olivia , Zischg Andreas Paul
Published: March 2022

In recent times water-related hazards have captured public attention and led to an increased interest in developing hydrologic forecasting systems, and quantifying their reliability. Despite major investments in flood forecasting and flood protection measures undertaken after recurring widespread inundations (e.g. 2002 and 2013 in Eastern Europe), heavy rainfall events led to severe flooding in Western Europe during July of the past summer, resulting in severe impacts and massive losses, including over two hundred deaths. Extreme precipitation, breaking observed records, is expected to have an increased likelihood under global warming, all the more we should question and scrutinize our knowledge about the frequency and severity of floods. Reliable estimates of these, and a better quantification of their uncertainty are key information for improving our preparedness and developing adaption measures in the future.

For this purpose we explore the potential of running pooled weather reforecasts through the flexible hydrological model framework DECIPHeR (Coxon et al.2019) in Switzerland, modified to include snow, glaciers and the effect of lakes and reservoirs on the river network. For three case studies of different climatic regions (one including regulated lakes), we compare floods generated by the 10 largest precipitation events and precipitation events of low frequency (return period >= 100 years), both extracted from the pooled data, for three accumulation periods (1, 3, 5 days) with the official flood frequency curves and flood frequency curves generated with long continuous simulation using the pooled data (> 1000 years). This analysis will show us possible deficiencies of record-based flood frequency curves, if running selected precipitation events according to a return period already gives us a representative “flood sample”, and what is the gain of running long continuous simulations (e.g. are there overlooked events, summoning hydrological extremes through particular spatio-temporal patterns? What is the effect of different initial conditions?).

 

References

Coxon G., Freer J., Lane R., Dunne T., Knoben W.J.M., Howden N.J.K., Quinn N., Wagener T. and Woods R. : DECIPHeR v1: Dynamic fluxEs and ConnectIvity for Predictions of HydRology. Geosci Model Dev.,12,2285-2306, https://doi.org/10.5194/gmd-12-2285-2019, 2019.
Quantifying the growth and decay of topography in collisional orogens 
Authors: Wolf Sebastian G. , Huismans Ritske S. , Braun Jean , Yuan Xiaoping
Published: March 2022

It is widely recognized that mountain belt topography is generated by crustal thickening and lowered by river incision, linking climate and tectonics. However, it remains enigmatic whether surface processes or lithospheric strength control mountain belt height, width, and longevity, reconciling high erosion rates observed for instance in Taiwan and New Zealand and low erosion rates in the Tibetan and Andean plateaus, as well as long-term survival of mountain belts for several 100s of million years as observed in the Urals and Appalachians. Here we use a tight coupling between a landscape evolution model (FastScape) and a thermo-mechanically coupled mantle-scale tectonic model (Fantom) to investigate mountain belt growth and decay. Using several end-member models and introducing the new non-dimensional Beaumont number, Bm, we quantify how surface processes and tectonics control mountain growth and define three end-member types of growing orogens: Type 1, non-steady state, strength controlled; Type 2, flux steady state, strength controlled; and Type 3, flux steady state, erosion controlled. Orogenic decay is determined by erosional efficiency and can be subdivided into two phases with variable isostatic rebound characteristics and associated timescales: First short-wavelength relief is removed within a few Myr, followed by removal of long-wavelength topography and effectively local isostatic rebound. Comparing model and scaling results to natural orogens explains why different orogens on Earth are rheology or erosion- (climate)-limited, and why long-term survival of topography seems to be the norm rather than the exception.