bluuebunny/crossref_metadata_2025 huggingface dataset:
A Data-Driven Approach to Isolate the Role of Radiative Heating in Tropical Cyclone Intensification
Authors: Tam Frederick Iat-Hin , Beucler Tom , Ruppert James
Published: March 2022

Quantifiable assessment of how different physical processes promote tropical cyclone (TC) development is paramount in improving basic understanding of TC genesis and TC intensification forecasts. This assessment can be made via Eulerian budgets or by linearizing the equations of motion. For instance, the Sawyer-Eliassen equation gives the secondary circulation driven by a steady thermodynamic forcing. However, existing diagnostic frameworks often make implicit assumptions such as axisymmetry and temporally-averaged forcing, precluding discussions on how spatially heterogeneous or transient forcing may affect TC intensity. 

In this work, we combine principal component analysis with multiple linear regression to build a linear framework that predicts the evolution of three-dimensional wind fields at different forecast windows, based on current heating and wind conditions. We apply this model to ensembles of WRF simulations on Hurricane Maria (2017) and Typhoon Haiyan (2013). Uniquely, the simulations include cloud radiative feedback denial experiments, which enables us to quantify the extent to which radiative processes drive TC intensification. Given their simplicity, our models are reasonably accurate, with coefficients of determination exceeding 0.8 for forecast windows longer than six hours. The linear nature of our model allows us to cleanly decompose the contributions of different physical processes to three-dimensional TC kinematic changes. Using radiative heating as an example, preliminary results suggest that this heating creates outward-propagating diurnal variability in wind perturbations during critical intensification periods of Hurricane Maria. These wind perturbations resemble a shallow lower-tropospheric secondary circulation; implications of this circulation to TC intensification are explored. 

More generally, our framework can map thermodynamic forcing to kinematic changes without relying on axisymmetric assumptions, which opens the door to data-driven discovery of the leading physical pathways to TC intensification.
Phyllosilicate precipitation in sediment and sill from the Guaymas basin : proxies for post magmatic and hydrothermal fluid circulation
Authors: Buatier Martine , Cheviet Alban , Gameiro Marie , Choulet Flavien , Aiello Ivano
Published: March 2022

The Guaymas Basin in the Gulf of California represents the nascent stage of an ocean, characterized by siliceous organic-rich sediments (diatom ooze) deposited at very high sedimentation rates. The basin is also characterized by a dense network of shallow mid-Pleistocene to recent sills that have intruded the subseafloor over a distance of several tens of kilometers from the spreading axis. These magmatic intrusions produce heat anomalies and sediment transformations in the contact aureoles that affect both organic and inorganic compounds, such as cracking of sediment OM, dehydration and dissolution of mineral phases, creation of porosity and convection of hydrothermal fluids. We focus our investigations on the phyllosilicates (clay minerals) that formed at the contact between the sill and the sediment (IODP Expedition 385, Sites U1546 and U1550): overall our results support the intepretation that these hydrated minerals can be used as proxies for fluid-rock interactions. In our study, we investigate sediment and sill samples from the contact zones by combining XRD analysis of oriented samples (< 2 and <16 µm fractions) with optical and SEM observations.  The XRD patterns from the clay fractions of the siliceous claystones suggest that the background (non metamorphosed) sediment of the Guaymas basin is mainly composed of detrital smectite, kaolinite and illite. However, in both the lower and upper aureole, the contact sediment displays a different clay assemblage characterized by the occurrence of mixed-layer smectite and chlorite. In the sediment located just above the sill contact at Sites U1546 and U1550 the corrensite (a regular smectite-chlorite mixed-layered) is also present. SEM images support the interpretation that this mineral is authigenic and occurs together with with euhedral pyrrhothite and quartz suggesting that it precipitated from hydrothermal fluid circulation. The magmatic sill is associated with two types of phyllosilicates. One is mica (biotite composition) which occurs as large crystals (~50 to ~100 µm) intergrowths with magmatic plagioclase suggesting a magmatic origin. The other one, smectite aggregates filling vacuoles and replacing magmatic glass, is widespread in most basaltic samples. The latter is a trioctahedral Mg-Fe smectite (Saponite) with K or Na in the interlayer. The formation of the smectites suggest that basalt further interacted with connate fluids or seawater and that a significant hydratation of the basalt is located at sediment contact.

Authigenic phyllosilicates are abundant at sediment-sill interface, they registered the last stages of the fluid-rock interaction probably related to hydrothermal fluid circulation.
Pulverized rock and episodic hydrothermal brecciation along the Median Tectonic Line, Japan
Authors: Agroli Geri , Uno Masaoki , Okamoto Atsushi , Tsuchiya Noriyoshi
Published: March 2022

The Median Tectonic Line is a major east-west-trending arc-parallel fault that separates Sanbagawa metamorphic rock and Ryoke granite. We present the novel field observation of possibly pulverized rock and its evolution toward the fault cataclasite/breccia in the Ichinokawa antimony deposit in Central Shikoku. Ichinokawa was considered as largest stibnite mine in the world with a huge stibnite aggregate in which occurs in the brecciated-pelitic schist of the Sanbagawa belt. Based upon the texture in the outcrop and particle size distribution (PSD), this breccia is classified into two types. Breccia-1 (bx-1) is characterized by a centimeter-meter (up to 5m) angular breccia-clast with minimum to no shear displacement and rotational block. This bx-1 subsequently grows to be highly comminuted to produce breccia-2 (bx-2) which appear to have chaotic-polymict clast with matrix-supported texture within the fault zone with variable width and cut the bx-1 by recognizable breccia margin. Both of these breccia are cemented by reddish rock-flour matrix consist of dolomite, quartz, mica, ± pyrite. In addition, bx-2 has a more rounded shape with most of the clast size being less than 50mm and it shows orientation nearly parallel to the fault plane under a thin section. Based on this macro and micro-scale observation breccia in Ichinokawa is more likely to form under different mechanisms. Pulverization is plausible to rupture the pelitic schist and generate bx-1 without rotating the fragment. Hydrothermal activity in this area can’t be neglected which is responsible to create bx-2 as a result of fluid injection and transporting comminuted-fragment of bx-1 into the damage/fault zone. This breccia also underpins the formation of stibnite deposits that mark the latest fluid activity in this area where quartz-stibnite±pyrite±kaolinte vein truncate both pelitic schists of bx-1 as well as bx-2.
The interannual variability of eddy activities in the Kuroshio region south of Japan and its relationship to Kuroshio latitudinal position over the Izu Ridge 
Authors: Wang Qiang
Published: March 2022

This study investigates the variability of eddy activities in the Kuroshio region south of Japan using both satellite sea surface height observation and high-resolution ocean reanalysis data. It is found that the eddy kinetic energy (EKE) measuring eddy activities has a significant interannual variability. On the meanwhile, the EKE variability is negatively leading correlated with the change in the Kuroshio latitudinal position over the Izu Ridge. We further find that the baroclinic instability and advection processes are responsible for the EKE interannual variability and its relationship to the Kuroshio latitudinal position over the Izu Ridge. Specifically, before the high EKE level occurs, a cyclonic eddy generates east of Kii Peninsula. The rapid development of this eddy and its eastward movement to the Kuroshio region induce the isopycnal inclinations there and the associated horizontal density gradient, which leads to the strong baroclinic instability and promotes the evolution of eddy field. The developed strong eddies move downstream to the Izu Ridge. This pushes the Kuroshio off the shore and causes the southerly Kuroshio latitudinal position. Contrarily, when the cyclonic eddies do not appear in the Kuroshio region, the isopycnals are relatively flat, which is not conducive to the generation of baroclinic instability. Consequently, the EKE level is low and only weak eddies are advected to Izu Ridge, which does not substantially shift the Kuroshio southward and thus results in the northerly Kuroshio position. This contributes to the understanding and prediction of the Kuroshio dynamics. 
Tropospheric corrections in GNSS orbit determination without the mapping step
Authors: Navarro Trastoy Angel , Strasser Sebastian , Tuppi Lauri , Vasiuta Maksym , Motlaghzadeh Sanam , Poutanen Markku , Mayer-Gürr Torsten , Järvinen Heikki
Published: March 2022

Neutral gas atmosphere bends and delays propagation of microwave signals in satellite-based navigation. Weather prediction models can be used to estimate these effects by providing 3-dimensional refraction fields for signal delay computation. In this study, a global numerical weather prediction model (Open Integrated Forecasting System (OpenIFS) licensed for Academic use by the European Centre for Medium-Range Weather Forecast) is used to generate the refraction fields. The slant delays are produced using a Least Travel Time (LTT) ray-tracer. Finally, the GNSS satellite orbits are solved using the GROOPS (Gravity Recovery Object Oriented Programming System) software toolkit of the Technical University of Graz which applies the raw observation method. Specifically, our implementation supplies the slant delays directly to the orbit solver without an intermediate mapping step, i.e., mapping of zenith delay to a prescribed functional form of azimuth and elevation angles. Essentially, this removes the assumption that signal delays follow some functional form, and allows hence to take full advantage of local refraction field asymmetries in GNSS signal processing that are partially lost in the mapping procedure. Our results indicate that this has clear benefits, both in terms of accuracy of the tropospheric correction and stream-lining the information flow in GNSS processing. Our view is that this new framework exposes the synergies in space geodesy and meteorology better than the earlier approaches.
Barents Sea Polar Front dynamics during fall and winter 2020-2021
Authors: Hugaas Kolås Eivind , Baumann Till , Fer Ilker , Koenig Zoe
Published: March 2022

The Barents Sea is one of the main pathways by which Atlantic Water (AW) enters the Arctic Ocean and is an important region for key water mass transformation and production. As AW enters the shallow (< 400 m) Barents Sea, it propagates as a topographically steered current along a series of shallow troughs and ridges, while being transformed through atmospheric heat fluxes and exchanges with surrounding water masses. To the north, the warm and salty AW is separated from the cold and fresh Polar Water (PW) by a distinct dynamic thermohaline front (the Barents Sea Polar Front), often less than 15 km in width.

Two cruises were conducted in October 2020 and February 2021 within the Nansen Legacy project, focusing on the AW pathways and ocean mixing processes in the Barents Sea. Here we present data from CTD (Conductivity, Temperature, Depth), ADCP (Acoustic Doppler Current Profiler) and microstructure sensors obtained during seven ship transects and two repeated stations across and on top of a 200 m deep sill (77°18’N, 30°E) at the location of the Polar Front between AW and PW. The ship transects are complemented by five underwater glider missions, two equipped with microstructure sensors. On the sill, we observe warm (>2°C) and salty (>34.8) AW intruding below the colder (<0°C) and fresher (34.4) PW setting up a geostrophic balance where currents exceed 20 cm/s. We observe anomalous warm and cold-water patches on the cold and warm side of the front, respectively, collocated with enhanced turbulence, where dissipation rates range between 10-8 and 10-7 W/kg. In addition, tidal currents on the sill reach 15 cm/s. The variable currents affect the front structure differently in the vertical. While the mid-depth location of the front is shifted by several kilometers, the location of the front near the bottom remains stationary.  The frontal dynamics on the sill result in transformation and mixing of AW, manifested in the troughs north of the sill as modified AW.
The effects of drip irrigation with nanobubbles aerated water on soil N transformation
Authors: Baram Shahar , Weinstien Maya , Kaplan Guy , Friedman Shmulik
Published: March 2022

In recent years, irrigation with nanobubbles aerated water (NB-water) [i.e., air or oxygen-NB (ONB)] has emerged as a new method to alleviate transient hypoxic conditions in the rhizosphere. We aimed to study the effect of surface and subsurface drip irrigation with ONB aerated waters [i.e., fresh (0.4 dS/m), secondary urban treated wastewater (TWW; 1.3 dS/m), saline (3dS/m)] on soil nitrogen transformations. Greenhouse lysimeter experiments were conducted in vertisol (58% clay), sand (98% sand), compost, and sand:compost (1:1) mixture, under well aerated and poorly aerated conditions. Ammonium-N to nitrate-N ratios in the irrigation waters ranged from 15% to 50%.  In all the experiments, irrigation with ONB water, with dissolved oxygen (DO) concentrations of 11 to 35 mg/L, increased the transient buildup of nitrite in the porewater, even under well-aerated conditions (soil air O2> 19%). The most significant effects were observed in the sand, sand:compost, and compost media, where nitrite concentrations were 2 – 8 times greater than the controls and reached over 65 mg/L. Despite the increased nitrite concentrations, irrigation with ONB waters reduced the nitrous oxide fluxes by 4 – 85%. Both phenomena suggested higher oxygen availability in the soil. Nitrite buildup implies that ammonia (NH3) oxidation may not be the rate-limiting step of nitrification under irrigation with ONB aerated water. 
Contribution of thermal weakening in the frictional rupture dynamics
Authors: Paglialunga Federica , Passelègue Francois , Lebihain Mathias , Violay Marie
Published: March 2022

The analogy between earthquakes (i.e. frictional ruptures) and shear crack motions is commonly used to investigate and understand the mechanics and occurrence of such natural phenomena. However, if on one side experimental works showed how shear cracks (obeying to a square root singularity, in the framework of Linear Elastic Fracture Mechanics) describe the onset of frictional ruptures, on the other side recent models suggested that frictional ruptures can be controlled by unconventional singularities (i.e., singularity orders that deviated from the square root singularity) if weakening occurs behind the rupture tip.

To study this, we performed stick-slip experiments with a biaxial apparatus working in a direct shear configuration. The tested samples consist of two polymethylmethacrylate (PMMA) blocks generating, once put into contact, an artificial fault interface. Normal load (1 to 5 MPa) and an increasing shear load were applied, leading to spontaneous ruptures nucleation. Rupture was captured through a strain gauge rosettes array along the fault, allowing the measurement of local strain and stress fields at high recording frequency (2 MHz).

Different events occurring at different rupture speeds (100 to 900 m/s) were studied. At the strain gauge location, a dual strength weakening is observed, reflected in a scale dependent evolution of breakdown work with fault’ slip, contrarily to fracture energy which is, by definition, scale independent. This behavior, probably caused by thermal weakening (i.e. flash heating) activated during slip, is well described by the recently developed unconventional theory of frictional ruptures (i.e. rupture driven by a non-square root singularity). We demonstrate that such unconventional singularity emerges from velocity strengthening behavior, related to heat diffusion far from the rupture tip. Moreover, these experiments suggest that an analysis of the propagating rupture in the framework of Linear Elastic Fracture Mechanics, which assumes a square root singularity, could prove to be not always sufficiently exhaustive when frictional weakening occurs far from the rupture tip.
Statistics on Alfvénic Structures of the Solar Wind in the inner Solar System
Authors: Mieth Johannes Z. D. , Hilgers Yannis , Heyner Daniel , Glassmeier Karl-Heinz , Plaschke Ferdinand
Published: March 2022

Based on measurements of the magnetometer MPO-MAG on board the spacecraft BepiColombo on its way to Mercury, we present a statistical overview on Alfvénic structures in the interplanetary magnetic field (IMF) in the inner solar system between approx. 0.3 – 1 AU and their implication on the offset calibration accuracy of space-borne magnetometers.
Different properties of the Alfvén waves are examined and statistically compared to each other, as are for example: orientation of the wave plane, orientation of the main magnetic field.
In addition to the spatial properties, the temporal properties like stability, occurrence rate and typical timescales of Alfvén Waves are also studied.
To highlight possible differences of the IMF between the inner Solar System and at Earth-distance, results are then compared to measurements of the Moon-orbiting ARTEMIS probes.
Flow regime shifts the carbon-nitrogen coupling of dissolved organic nitrogen losses in a subtropical mountainous catchment
Authors: Yu Yu-Lin , Lee Li-Chin , Huang Jr-Chuan
Published: March 2022

Dissolved organic nitrogen (DON) is a kind of reactive nitrogen in the nitrogen cycling processes, which has been neglected for decades because of the difficulty in measurement, leading to underestimating the nitrogen saturation in the ecosystem. As a result, the need for a complete understanding of DON export behaviors is urgent. This study compares the DON export behaviors to previous studies, focusing on the relationship between DON, dissolved inorganic nitrogen (DIN), dissolved organic carbon (DOC), carbon-nitrogen coupling. We analyzed the data collected at the Fushan Experimental Forest (FEF) in northeastern Taiwan. Preliminary research results showed that (1) behaviors of DON export were unchanged between wet and dry seasons, but only switched at typhoon events, (2) the concentration of DOC was deficient in stream water, (3) unknown endmember between DON and DOC appeared at typhoon events, (4) the high bioavailability of DON occurred in soil and stream water, and (5) the concentration of DOC in soil pool was significantly higher than that of stream water. This study infers that typhoon disturbance appeared to alter the carbon limiting at FEF, causing the change of DON export patterns.
Skillful Decadal Prediction of German Bight Storm Activity
Authors: Krieger Daniel , Brune Sebastian , Pieper Patrick , Weisse Ralf , Baehr Johanna
Published: March 2022

Can a decadal prediction system be used to generate skillful forecasts of small-scale climate extremes? For large-ensemble probabilistic predictions of German Bight storm activity (GBSA), the answer is yes. In this study, we show that the prediction skill of the Max-Planck-Institute Earth System Model (MPI-ESM) decadal hindcast system for GBSA is higher than the skill of persistence-based forecasts. We define GBSA every year via the most extreme three-hourly geostrophic wind speeds, which are derived from mean sea-level pressure (MSLP) data. Our 64-member ensemble of yearly decadal hindcast simulations spans the time period 1960-2018. For this period, we compare deterministically and probabilistically predicted MSLP anomalies and GBSA with a lead time of up to ten years against observations. The model shows limited deterministic skill for single forecast years, but significant positive skill for long averaging periods. For probabilistic predictions of high and low storm activity, the model is skillful over the entire forecast period, and outperforms persistence-based forecasts. For short lead years, the skill of the probabilistic prediction for high and low activity notably exceeds the deterministic skill.
The relationship between dayside and nightside Dynamics under northward interplanetary magnetic field substorms
Authors: Elhawary Reham , Laundal Karl , Reistad Jone , Ohma Anders , Hatch Spencer , Gasparini Sara
Published: March 2022

Substorms that occur under northward interplanetary magnetic field (IMF) conditions can elucidate the relationship between the dayside and nightside dynamics of the ionosphere. We investigate the relationship between the dayside and the nightside dynamics in response to northward IMF substorms. While the dynamics of the dayside ionosphere are directly related to the interaction between the solar wind interplanetary magnetic field (IMF) and the earth’s magnetic field, the dynamics in the nightside are strongly controlled by magnetotail activity like substorms. Under southward IMF conditions, both reconnection on the dayside and substorms on the nightside increase Dungey convection, making it difficult to distinguish the separate contributions of dayside and nightside processes to large-scale dynamics. Under northward IMF conditions, on the other hand, it is easier to distinguish between dayside and nightside processes, since northward IMF does not increase Dungey flows. We present a superposed epoch analysis of the equivalent current and magnetic perturbations above 60 deg magnetic latitude (mlat) from ground-based magnetometer stations based on 280 northward IMF substorms. We also investigate whether the dayside current pattern is influenced by the substorm onset.
Novel approaches to model assessment and interpretation in geospatial machine learning
Authors: Brenning Alexander
Published: March 2022

As the interpretability and explainability of artificial intelligence decisions has been gaining attention, novel approaches are needed to develop diagnostic tools that account for the unique challenges of geospatial and environmental data, including spatial dependence and high dimensionality, which are addressed in this contribution. Building upon the geostatistical tradition of distance-based measures, spatial prediction error profiles (SPEPs) and spatial variable importance proles (SVIPs) are introduced as novel model-agnostic assessment and interpretation tools that explore the behavior of models at different prediction horizons. Moreover, to address the challenges of interpreting the joint effects of strongly correlated or high-dimensional features, often found in environmental modeling and remote sensing, a model-agnostic approach is developed that distills aggregated relationships from complex models. The utility of these techniques is demonstrated in two case studies representing a regionalization task in an environmental-science context, and a classification task from multitemporal remote sensing of land use. In these case studies, SPEPs and SVIPs successfully highlight differences and surprising similarities of geostatistical methods, linear models, random forest, and hybrid algorithms. With 64 correlated features in the remote-sensing case study, the transformation-based interpretation approach successfully summarizes high-dimensional relationships in a small number of diagrams.

The novel diagnostic tools enrich the toolkit of geospatial data science, and may improve machine-learning model interpretation, selection, and design.
Time-lapse multi-frequency EMI mapping and ERT profiling for the characterization of soil water behavior in mountain catchments. 
Authors: Cassiani Giorgio , Censini Matteo , Nasta Paolo , Allocca Carolina , Sica Benedetto , Lazzaro Ugo , Mazzitelli Caterina , Verdone Matteo , Dani Andrea , Manca di Villahermosa Francesca , Penna Daniele , Romano Nunzio
Published: March 2022

Hydrological processes along mountain hillslopes involve complex interaction between soil storage and surface and subsurface flow, drainage and evapotranspiration. To capture this complexity, time-lapse extensive and intensive measurements are needed, potentially capable of providing spatially dense information in 3D and time frequent data. To this end, hydro-geophysical methods (ground penetration radar, GPR, electromagnetic induction, EMI and electrical resistivity tomography, ERT) based on electrical and electromagnetic laws are widely used as they naturally link to the electrical properties of soil moisture. ERT produces, especially in time lapse mode and using permanent installations, very detailed images of the water dynamics along hillslopes. While ERT requires galvanic contact with the ground, and thus relatively slow operations, EMI can be applied over large areas in a very short time. This method has been used for decades, mainly to produce apparent electrical conductivity (ECa) maps. Only recently, inversion of EMI data as a function of depth has become a viable practice.

In this work, we present two cases of hillslope monitoring using non-invasive methods, both performed as part of the WATZON project, funded by the Italian Ministry of University and Research (MIUR). The first case is the Mediterranean catchment of the Alento River, in southern Italy. The monitoring was carried out using 7 different EMI surveys, acquired in multifrequency mode (FDEM) between August 2020 and December 2021. The purpose of this survey was to characterize the structure of the basin’s subsoil within the first few meters, as well as to record the variation of electrical conductivity (EC) associated with seasonal variations. The second case is related to the Apennines catchment of the Re Della Pietra, located at the border between Tuscany and Emilia-Romagna in central Italy. The monitoring was carried out through 6 different EMI surveys, acquired in multifrequency mode (FDEM) between August 2020 and May 2021. The purpose of this survey was to characterize the structure of the basin’s subsoil within the first few meters, as well as to record the variation of electrical conductivity (EC) associated with seasonal variations. Furthermore, ERT measurements were carried out along a fixed line on the ground, according to the direction of the maximum slope. The combination of EMI and ERT proved particularly effective in delineating the hydrologic dynamics of the hillslope.
Assessment of sediment connectivity in a densely drained vineyard catchment: contributions from graph theory
Authors: Pic Jessica , Fressard Mathieu , Cossart Étienne
Published: March 2022

In agricultural catchments, the landscape structure elements (ditches, hedges, pounds etc.) are recognized to play a major role in hydro-sedimentary transfers. It determines not only sediments availability, but also sediment pathways, water and sediments (de)coupling and connectivity patterns from source to sinks. However, linear drainage infrastructures remain often poorly represented in hydro-sedimentary modelling. Therefore, understanding the link between the catchment landscape structure and the transfer processes at its outlet is still a major challenge. Graph theory has been proved to be a significant tool to investigate sediment connectivity among agricultural catchments as it allows an explicit representation of linear and punctual elements of the landscape.

Based on a detailed inventory of linear landscape elements and a continuous monitoring of sediment fluxes, we built a new graph theory framework to comprehend sediments transfers in a dense agricultural drainage network in the Beaujolais vineyard (France). It integrates all types of linear infrastructures that might canalize water and sediment fluxes (tracks, ditches and soil bunds) and sediment traps used by winegrowers. From the intersection of the drainage network and a topographic graph, we went for spatial analysis to take indices out (IC and RF indices), to extract effects of (dis)connectivity and to compare with a null model (i.e. topographic graph excluding linear infrastructures). Drainage network outlets were extracted to distinguish direct connections to the river in comparison to sediment sinks. The network structure emphasizes a reduction of sediment connectivity on the upper slope unlike on the lower slope where it is increased. Describing sediment structural connectivity through landscape structure analysis allows to identify the drainage infrastructures efficiency and might be of interest in a management perspective.
Processes responsible for the generation of internal solitons on a shelf: experimental evidences
Authors: Serebryanyy Andrey
Published: March 2022

Unlike surface waves, whose generation is mainly associated with wind action, internal waves, which are widespread in the oceans and seas, have many sources of generation. The knowledge about the parameters of internal waves in the ocean and their structure is quite complete by now, however, the area concerning the causes of the appearance of internal waves is still poorly understood. Only one mechanism is well known that leads to the formation of intense internal waves. It is associated with the collision of tidal currents with a continental slope or underwater ridges. The talk will present the processes responsible for the generation of intense soliton-like internal waves on the shelf. This information has been collected over 40 years of experimental research by the author. Eleven main processes were identified that are responsible for the generation of intense short-period internal waves on the shelf. Most of them were observed in the non-tidal Black Sea. These processes are as follows: 1. Generation by a local hydrological front moving towards the coast in the post-storm period; 2. Ggeneration by subsurface intrusion of waters returning to the coastal zone in the post-storm period; 3. Generation of a submesoscale eddy during the passage of a submesoscale eddy on the shelf; 4. Generation by internal inertial waves approaching the coastal zone; 5. Generation by a cold atmospheric front passing over the sea; 6. Generation by river runoff at the places where large rivers flow into the sea; 7. Generation associated with the upwelling process in the coastal zone; 8. Generation of internal soliton-like waves by moving intrusion of surface freshened waters; 9. Generation of internal soliton-like waves in the collision of currents; 10. Generation of packets of internal waves when tidal internal waves enter the shelf; 11. Generation of packets of internal waves when internal seiches enter the shelf. This work was supported by RFBR grant No. 19-05-00715.
Development of a local impact-based Landslide Early Warning System using physically-based multi-hazards modelling and machine learning in Java, Indonesia.
Authors: Subiyantoro Andy , Westen Cees van , Bout Bastian van den , Victor Jetten , Muntohar Agus , Mushthofa Akhyar , Yuniawan Ragil Andika , Satyaningsih Ratna
Published: March 2022

Early Warning Systems are one of the most effective tools for reducing disaster risk, however the development of Landslide Early Warning Systems (LEWS) is complicated due to the random nature of landslide occurrence and the uncertainty in mapping the parameters that cause them. Local LEWS have been effective for known landslides, but regional scale LEWS based on rainfall thresholds have not been very effective up to now. In recent years physically-based multi-hazard models have been developed which allow to predict mass movement hazards at a local scale. However, it is still difficult to apply these in LEWS in a local scale due to the coarse resolution of rainfall estimates and the high computational modelling requirements for running such models real-time. On the other hand, machine learning approaches have been used to assess the relationship between the distribution of the landslide hazard and the catchment morphometric features.

This research applies a physically-based multi-hazard model combined with machine learning to forecast the mass movement impact, based on rainfall predictions in an area in Java, Indonesia. The landslide inventory was developed using a combination of local reporting data and machine learning techniques. The integrated physically-based multi hazard model OpenLISEM is used to create a database of hazard intensity maps under various rainfall scenarios. The resulting hazard intensity maps are subsequently used to subdivide the area in homogeneous zones for which warning levels are given. Machine learning is used to query the database and extract the most likely hazard intensity map based on the rainfall prediction. The intensity is then combined with exposure information of people, buildings, transportation infrastructure and agriculture to provide impact forecasts. The output of combining physically-based models with machine learning approaches has the potential to improve the prediction of landslide impact. The method also allows to make more specific local decisions related to the actions for various levels of warning (e.g. increased vigilance, removal of resources, evacuation of people). The method is currently under development as part of an Indonesian-Netherlands collaboration project to develop a blueprint to use tailored rainfall data, in combination with empirical and physically-based hydrological and landslide models, and historical landslide data for the development of thresholds for landslides and debris flows, as the basis for early warning at settlement level, applied to several test sites in Java.
An interdisciplinary approach for reconstructing environmental evolution since the mid Holocene, in Agia (Lemnos Island, Greece)
Authors: Theocharidis Nikolaos , Koukousioura Olga , Kouli Katerina , Gkouma Myrsini , Aidona Elina , Syrides Georgios , Efstratiou Nikos
Published: March 2022

Lemnos Island (NE Aegean Sea) was inhabited since the Paleolithic times, as is suggested by archaeological evidence from the hunting campsite of Ouriakos (~12.000 BP). The Agia Bay, in the vicinity of Ouriakos site, is located on the southeastern coast of Lemnos Island. The coastal area today is characterized by aeolian sandy deposits (dunes), while a small river is discharging in the bay. The systematic investigation of a 15.5-m long sediment core from the coastal plain of Agia aims to set light to the paleoenvironmental evolution of the area. The exhaustive study of the faunal and floral remains of the deposits, including benthic foraminifera, ostracoda, molluscs, pollen and NPPs was further supported by sedimentological, micromorphological and elemental analyses, magnetic susceptibility measurements and radiocarbon dating.

Four main evolutionary stages are identified: (1) at the base of the sequence the fluvial activity is dominating the sedimentation in the area, while progressively seawater intrusions are observed as suggested by reworked marine foraminifera and mollusc specimens (2) before ~7000 BP a restricted fresh water wetland is formed, characterized by land snails, Cyperaceae and the presence of aquatic plant seeds (3) after ~7000 and until ~5000 BP a connection of the wetland to communication to the sea is established as indicated by the occurrence of euryhaline foraminifera (Ammonia tepida, Haynesina germanica), ostracoda (Cyprideis torosa, Cyprinotus salinus) and mollusc (Cerastoderma glaucum, Abra sp., Hydrobia sp.) assemblages accompanied by marine dinoflagellate cysts and charophytes (4) after ~5000 BP a nearshore environment is developed due the sea-level rise, characterized by Peneroplis pertusus, rotaliids and miliolids as well as Loxoconcha sp., Cerithium sp. and reworked foraminifera and mollusc specimens. Pollen assemblages record the occurrence of mixed deciduous oak forest with Ulmus and Carpinus/Ostrya in the island interior, while agricultural activities are inferred by pollen indicator species.
Geochronology of the unexposed crust within the Finnish Archean – insights from the Koillismaa Deep Hole in Kuusamo, northeastern Finland
Authors: Kurhila Matti , Anttilainen Teemu , Karinen Tuomo , Mikkola Perttu
Published: March 2022

A 3000 m deep hole is being drilled in the Archean Karelian Craton in northeastern Finland in an area where the granitoids dominating the surface have yielded Neoarchean ages (2.8–2.7 Ga). Archean greenstones and Paleoproterozoic dolerites are exposed within the domain as well. The drilling site lies between ca. 2.44 Ga Koillismaa and Näränkävaara mafic layered intrusions. This site was chosen based on gravimetric, magnetic, magnetotelluric and reflection seismic studies, which have revealed a deep anomaly that seems to connect the two mafic layered intrusions. Based on modelling of the geophysical data, the upper boundary of this ca. 60 km long, roughly E-W oriented anomaly lies at approximately 1.5 km depth.

We sampled various rock types from depths of ~40–1600 m for zircon U-Pb dating. The lithologies include leucogranites, tonalite gneiss, hornblende diabase, quartz diorite and granodiorite. Based on observations from the drill core extracted so far, the source of the anomaly is likely to be ultramafic cumulates. Also, presence of Paleoproterozoic granitoids is likely. We will perform the U-Pb analyses during the winter of 2022. The results are expected to confirm the interconnection of the two layered intrusions, clarify the age distribution of the granitoids in the region, and help to decipher the detailed tectonic evolution of the Archean Koillismaa area. 
Methane emissions from a rewetted bog – diurnal cycles, impact of vascular plants and role of plant functional groups
Authors: Welpelo Carla , Tiemeyer Bärbel , Dubbert Maren , Piayda Arndt
Published: March 2022

Natural raised temperate bogs are characterized by Sphagnum-dominated vegetation, facing increasing threats by vascular plant encroachment in the recent past. The VESBO-project is investigating the influence of this shift in vegetation composition on the water and carbon cycle in a rewetted bog in north-west Germany. Two study sites were established in close proximity on the same former peat extraction area, one showing near-natural Sphagnum-dominated vegetation and one exhibiting an increasingly dense birch stand and Eriophorum vaginatum cover, low in Sphagnum density.

As methane (CH4) emissions from rewetted bogs are of strong interest regarding the greenhouse gas balance, one focus of our project is to disentangle how vascular plant encroachment is influencing total ecosystem CH4 emissions and to quantify the contribution of different plant functional types, especially in relation to the different peat water levels on both sites.  Besides this, little is known about the diurnal cycle in CH4 emissions and which bio-meteorological parameters are its drivers.

We used closed chambers in combination with the Picarro GasScouter G4301 to measure methane fluxes on-site. The measurements were performed every 3-4 weeks over one year and on multiple plots equipped with different chamber designs: soil chambers which were located either on hummocks (Eriophorum-dominated) or hollows (Sphagnum-dominated) and branch/leaf chambers for Betula-branches and Eriophorum-leaves. In order to more precisely quantify the influence of birch roots on the gas exchange, the soil plots were further divided into plots located in close proximity and separated from birch trees.

The campaigns included transparent and opaque measurements over the course of the day to cover both the diurnal and annual ranges of soil temperature and photosynthetic active radiation, as well as to capture net ecosystem exchange and respiration.

We will show the preliminary results of the methane fluxes from September 2020 to October 2021. They indicate that the methane fluxes increased strongly with soil temperature and water level. Further analysis will relate the CH4 emissions to plant functional groups and flux-driving parameters.

In conclusion, the available data will provide valuable information on the contribution and the drivers of methane emissions to the greenhouse gas emissions in bogs, which is particularly important for planning and reporting of rewetting and restoration activities in peatlands.
The deglacial forest conundrum
Authors: Dallmeyer Anne , Kleinen Thomas , Claussen Martin , Weitzel Nils , Cao Xianyong , Herzschuh Ulrike
Published: March 2022

The forest expansion in the Northern Hemispheric extra-tropics during the deglaciation, i.e. the last some 22,000 years, starts earlier and occurs much faster in our model simulation using the MPI-ESM 1.2 than in the recently published synthesis of biome reconstructions by Cao et al. (2019). As a result, the simulated Northern Hemisphere maximum in forest cover is reached at 11ka in the model, whereas the forest distribution peaks substantially later (at 7ka in the spatial mean) in the reconstructions. The model-data mismatch is largest in Asia, particularly in Siberia and the East Asian monsoon margin. The simulated temperature trend is in line with pollen-independent temperature reconstructions for Asia. Since the simulated vegetation adapt to the simulated climate within decades, the temporal model-data mismatch with respect to the forest cover may indicate that pollen records are not in equilibrium with climate on multi-millennial timescales.

Our study has some far-reaching consequences. Pollen-based vegetation and climate reconstructions are commonly used to evaluate Earth System Models against past climate states, but to what extent the reconstructed vegetation is in equilibrium with the climate at the reconstructed time slice is still a matter of discussion. Our results raise the question on which time-scales pollen-based reconstructions are reliable. Although, it is so far not possible to identify the causes of the mismatch between our simulations and the reconstruction, we suggest critical re-assessment of pollen-based climate reconstructions. Last, but not least, our results may also point to a much slower response of forest biomes to current and future ongoing climate changes than Earth System Models currently predict.

 

References:

Cao, X., Tian, F., Dallmeyer, A. and Herzschuh, U.: Northern Hemisphere biome changes (>30°N) since 40 cal ka BP and their driving factors inferred from model-data comparisons, Quat. Sci. Rev., 220, 291–309, doi:10.1016/j.quascirev.2019.07.034, 2019.
Array signal processing on distributed acoustic sensing data: directivity effects in slowness space
Authors: Näsholm Sven Peter , Iranpour Kamran , Wuestefeld Andreas , Dando Ben , Baird Alan , Oye Volker
Published: March 2022

Distributed Acoustic Sensing (DAS) involves the transmission of laser pulses along a fiber-optic cable. These pulses are backscattered at fiber inhomogeneities and again detected by the same interrogator unit that emits the pulses. Elastic deformation along the fiber causes phase shifts in the backscattered laser pulses which are converted to spatially averaged strain measurements, typically at regular fiber intervals.

DAS systems provide the potential to employ array processing algorithms. However, there are certain differences between DAS and conventional sensors. The current paper is focused on taking these differences into account. While seismic sensors typically record the directional particle displacement, velocity, or acceleration, the DAS axial strain is inherently proportional to the spatial gradient of the axial cable displacement. DAS is therefore insensitive to broadside displacement, e.g., broadside P-waves. In classical delay-and-sum beamforming, the array response function is the far-field response on a horizontal slowness (or wavenumber) grid. However, for geometrically non-linear DAS layouts, the angle between wavefront and cable varies, requiring the analysis of a steered response that varies with the direction of arrival. This contrasts with the traditional array response function which is given in terms of slowness difference between arrival and steering.

This paper provides a framework for DAS steered response estimation accounting also for cable directivity and gauge-length averaging – hereby demonstrating the applicability of DAS in array seismology and to assess DAS design aspects. It bridges a gap between DAS and array theory frameworks and communities, facilitating increased employment of DAS as a seismic array.
Decrease in shell volume of large benthic foraminifers with progressing ocean warming
Authors: Kinoshita Shunichi , Kuroyanagi Azumi , Nishi Hiroshi , Sasaki Osamu , Fujita Kazuhiko , Suzuki Atsushi , Kawahata Hodaka
Published: March 2022

It is commonly thought that recent progress of ocean warming effect on ocean ecosystems. Especially on calcifying organisms, it is concerned negatively such as coral blanching. Larger benthic foraminifers (LBFs) are one of important calcifying organisms in coral reef area, their carbonate productivity is the third highest rate in there. Therefore, it is important to elucidate the relationship between seawater temperature and the response of LBFs for estimating future ocean environment particularly in coral reef area. It has been reported that LBFs shell growth would decline when they growth higher temperature, while the physical characteristics of their shell growth remain unknown since their small and complex structures make it difficult to quantify shell growth in three dimensions. In this study, to determine how their shell volume would be affected by growth temperature, we cultured two species of LBFs which calcifying systems are different (porcelaneous LBF Sorites orbiculus and hyaline LBF Calcarina gaudichaudii) under six different temperature situations (19°C−29°C). After three months culturing, their shells were scanned by micro X-ray computed tomography (MicroCT). Here we found that　their shell volume growths were optimal at 24.4 to 24.6°C (S. orbiculus) and at 26.2 to 26.4°C (C. gaudichaudii), and declining at lower and higher temperatures than optimum temperatures. On the other hand, the intensity of the response to water temperature varies in different species. If the shell of S. orbiculus would be grown in temperature that is ±3°C different from the optimum temperature, the shell volume would be reduced by about 15%. Meanwhile, the shell of C. gaudichaudii would be showed only 7% decreasing at the same degree of temperature change. C. gaudichaudii lives at relatively shallower site than S. orbiculus with larger diurnal variation in water temperature, this difference of water temperature tolerance may have influenced their abundance. In any case, these findings demonstrate that LBF growth is already suppressed in summer and might be exacerbated in the future by ocean warming.