bluuebunny/crossref_metadata_2025 huggingface dataset:
AI-based hydromorphological assessment of river restoration using UAV-remote sensing
Authors: Dacheneder Felix , Schulz Karen , Niemann Andre
Published: March 2022

Many hydromorphological restoration measures have been applied on German water courses since 2000 the European water framework directive has been induced. The measures aim to improve the diversity of habitat alteration. Often a positive effect on aquatic biota can’t be detected, therefore implementation and the hydromorphological development of such measures can be questioned. But also the common monitoring and assessment methods for physical river habitat mapping can be questioned as they are limited in spatial scale and objectiveness of the mapper itself.

In the last decade, Unmaned Areal Vehicle (UAV) in combination with high-resolution sensors open new opportunities in a spatial and temporal scales. This research shows a case study of the river Lippe for the detection of hydromorphological habitat structures using Structure from Motion (SfM) and Deep learning based classification methods. In detail, this work discusses the difficulties of creating digital surface and orthomosaics from field survey data, but also shows results from a case study using a deep learning classification approach to identify physical river habitat structures.
Spatiotemporal Analysis of the Causes and Effects of Wildfire by Landsat Imagery and in situ Data: Case studies of Taiwan and California, USA
Authors: Tung YuJen , Tsai Christina W.
Published: March 2022

Records from the Forestry Bureau of Taiwan show that dozens of wildfire events occur every year in Taiwan. Furthermore, it is known that with climate change-induced extreme weather events, e.g., heatwaves and droughts, occurring more frequently, the wildfire occurrences are consequently increasing. Although the scale of wildfires in Taiwan is much smaller than in other places around the world, the potential harm caused by Taiwan’s wildfires is worth investigating due to the potential health issue and the safety concerns of wildfires.

Unfortunately, little has been done on the issue of wildfires in Taiwan. One of the difficulties of wildfire research in Taiwan can be attributed to the lack of forest areas data due to the limited number of observation stations. As a result, satellite data with more information on forest areas are used in this investigation to supplement the missing data and to complete the time series and variables. Multi-dimensional Complementary Ensemble Empirical Mode Decomposition (MCEEMD) is applied to identify the spatiotemporal distribution of variables, the meteorological factors affecting wildfires, and the wildfire influences on the vegetation of forests detected by satellite image time-series data. In the meantime, a time-frequency tool, Complementary Ensemble Empirical Mode Decomposition (CEEMD), is conducted to evaluate the trend and the variability of the time series of wildfire occurrences.

Wildfires can be lightning-caused and anthropogenic-caused. Therefore, to verify the intrinsic correlation between meteorological variables and wildfire occurrences, a scale- and time-dependent correlation approach, time-dependent intrinsic correlation (TDIC), is used. On the other hand, to estimate the impacts of wildfire, which may include air pollution, water quality, and health issues, time-dependent intrinsic cross-correlation (TDICC) is applied by considering the time lag effect.

This study aims at quantifying the time-lag correlation between wildfires and their potential effects on air pollutions, water quality, and health issues. Furthermore, the high-risk areas of wildfires in Taiwan are also identified. Meanwhile, the classical wildfire study case, California, USA, will be studied as a comparison case due to its large-scale wildfire, unique climate, and wildfire research. The results can serve as a reference for the Taiwan government to make decisions on management strategies referring to wildfire occurrences and livelihood problems.
A comparison of Backscatter Intensity of Icebergs in C- and L-band SAR Imagery
Authors: Færch Laust , Dierking Wolfgang , Doulgeris Anthony P. , Hughes Nick
Published: March 2022

Images from satellite Synthetic Aperture Radar (SAR) systems are widely used for iceberg monitoring. Normally, icebergs are detected in SAR images by utilizing constant false alarm rate (CFAR) filters, which compare each pixel or cluster of pixels against its background and adaptively set a threshold based on several assumptions regarding the statistical distribution of the background clutter. CFAR algorithms are currently being applied on images from the C-band SAR Sentinel-1 and RADARSAT missions by the operational ice services responsible for Canadian and Greenland waters. Previous studies have shown that imagery from wide-swath C-band SAR is unsuitable for detecting icebergs surrounded by sea ice, but other studies have indicated that icebergs in sea ice may be detected in high-resolution L-band SAR images. Additionally, it is well known that L-band SAR is less sensitive to sea surface roughness than C-band SAR. Therefore, a future operational L-band SAR mission is currently being investigated by the European Space Agency (ESA) since it is expected that L-band images are valuable complements to current C-band imagery for iceberg detection in areas with drift ice and in rough windy seas.

In this project, we investigate the backscatter intensity contrast between icebergs and their surroundings using ALOS-2 PALSAR-2 (L-band) ScanSAR, and Sentinel-1 (C-band) extra wide swath imagery. The investigations are concentrated on SAR images from two test sites, one in the Labrador Sea, where we – for further analysis - identified 256 icebergs in open water, and another site in the region of Belgica Bank with 1013 icebergs embedded in fast ice. The investigation shows that the two SAR sensors performed similarly for the open water site, with a backscatter intensity contrast between icebergs and the background of 5-6 dB in both the HH and HV band.  But for icebergs surrounded by sea ice, the contrast between icebergs and background at both C- and L-band is greatly reduced to around 2 dB for the HH channel and 4-5 dB for the HV channel.  By further manually classifying the sea ice types around the icebergs, we show that the backscatter contrast between icebergs and background is similar at C- and L-band for icebergs embedded in smooth sea ice. However, for rough sea ice, the C-band contrast is decreasing, while remaining high at L-band. Our results indicate that L-band data will lead to better performance for detecting icebergs surrounded by sea ice.
Scale-dependent blending of ensemble rainfall nowcasts with NWP in the open-source pySTEPS library
Authors: Imhoff Ruben , De Cruz Lesley , Dewettinck Wout , Velasco-Forero Carlos , Nerini Daniele , Goudenhoofdt Edouard , Brauer Claudia , van Heeringen Klaas-Jan , Uijlenhoet Remko , Weerts Albrecht
Published: March 2022

Radar rainfall nowcasting, an observation-based rainfall forecasting technique that statistically extrapolates current observations into the future, is increasingly used for short-term forecasting (<6 hours ahead). These first hours ahead are a key time scale for e.g. (flash) flood warnings and they are generally not sufficiently well captured by the rainfall forecasts of numerical weather prediction (NWP) models.

A recent development in nowcasting is the transition to more community-driven, open-source models. The Python library pySTEPS is an example of this. One of its main features is an efficient Python implementation of the probabilistic nowcasting scheme STEPS. pySTEPS generates an ensemble of rainfall forecasts by perturbing a deterministic extrapolation nowcast with spatially and temporally correlated stochastic noise. It considers the dynamical scaling of the rainfall predictability by decomposing the rainfall fields into a multiplicative cascade and applies different stochastic perturbations for each scale. This results in large-scale features that evolve more slowly than the small-scale features.

Despite pySTEPS' representation of the uncertainty associated with growth and decay of rainfall in the first 1-2 hours of the nowcast, it quickly loses skill after 2 hours, or even less for convective rainfall events or small radar domains. To extend the skillful lead time to the desired time scale of 6 hours or more, a blending with NWP rainfall forecasts is necessary. We have implemented an adaptive scale-dependent blending in pySTEPS based on earlier work in the STEPS scheme. In this blending implementation, the blending of the extrapolation nowcast, NWP and noise components is performed level-by-level, which means that the blending weights vary per cascade level. These scale-dependent blending weights are computed from the recent skill of the forecast components, and converge to a climatological value, which is computed from a 1-month rolling window and can be adjusted to the (operational) needs of the user. To constrain the (dis)appearance of rain in the ensemble members to regions around the rainy areas, we have developed a Lagrangian blended probability matching scheme and incremental masking strategy.

We present a validation of the blending approach in a hydrometeorological testbed using Belgian radar and NWP data for the Belgian and Dutch catchments Dommel, Geul and Vesdre. We compare the resulting ensemble rainfall and discharge forecasts of the blending implementation with ensemble nowcasts from pySTEPS, ALARO (NWP) forecasts and a linear blending strategy.
Madden–Julian Oscillation related to the prolonged heavy rainfall in East Asia in 2020
Authors: Moon Byung-Kwon , Wie Jieun , Kang Jinhee
Published: March 2022

In East Asia, unusually long-term and heavy rainfall in 2020 resulted in concentrated socio-economic damage and flooding. In this study, the characteristics of the Madden–Julian Oscillation (MJO) related to the prediction of heavy rainfall in East Asia were analyzed using the sub-seasonal to seasonal (S2S) prediction model. In 2020, unusually high precipitation fell in East Asia, compared to an average year, for an extended time. Precipitation was concentrated from the end of June to the middle of August; therefore, the analysis was carried out with an initial model date of July 2, 2020, while the lead-time was selected 1–31 day (July 3 to August 1). The model underestimated cumulative precipitation compared to observations, with KMA and UKMO having the lowest errors and ECMWF and CMA having the largest errors. The 850-hPa position altitude and wind field anomaly was analyzed and averaged over the prediction period. The results revealed that models with large errors showed different locations for the western and northern boundaries of the high pressure in the western North Pacific region, relative to observations, or else underestimated the size of the high-pressure zone. Based on the MJO prediction phases for July in the S2S models, models with good precipitation prediction performance in East Asia mainly showed phases 1–3 that were similar to observations and their amplitudes were also large. In contrast, models with poor prediction performance exhibited fewer instances of phases 1–3 on strong days or their amplitudes were small. This suggests that if an S2S model predicts the characteristics of the MJO accurately, similar to observations, it could improve predictions of summer precipitation in East Asia.

This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2020-01212.
A systematic review of scientific literature on earthquake-induced landslides
Authors: Schilirò Luca , Rossi Mauro , Polpetta Federica , Fiorucci Federica , Fortunato Carolina , Reichenbach Paola
Published: March 2022

Earthquake-induced landslides (EQILs) are severe secondary effects of a seismic event. These phenomena can produce direct and indirect damages to structure, infrastructures and to the society. EQILs can also trigger secondary hazard cascading effects and impact civil protection activities. For this reason, the scientific community over the past decades has dedicated an increasing attention to EQILs, with the publication of numerous scientific papers. In this work we describe a preliminary outcome of a comprehensive review of the main articles published on this topic from 1984 to 2021 in peer reviewed international journals. The selected articles, which have been identified after a systematic search on the Clarivate analytics’ Web of Science-Core Collection™ online platform, have been catalogued in a database, whose structure was designed to include the information preparatory for the analysis. Specifically, for each of the 798 articles we reported: a) the bibliometric information (i.e., article title, author(s), publication year, journal name and number of citations); b) the specific topic addressed by the article, which can be distinguished with respect to the scale of the analysis (i.e., regional or single slope) and the type of research (e.g., mapping, characterization/description, modelling); and c) the information related to the earthquake(s) considered in the article. In the database, we have identified 139 earthquakes whose main characteristics (e.g., date of occurrence, location, magnitude, focal mechanism) have been organized in a sub-section of the database. The analyses pointed out different commonalities between articles which allowed us to infer general aspects related to EQILs and, at the same time, to describe a comprehensive state of art on the topic.
Investigating the wind conditions in the North Sea for wind turbines at sites N-3.5, N-3.6 and N-7.2
Authors: Brast Maren , Gehrke Michael , Hahn Johannes , Hüttl-Kabus Sabine , Möller Thomas , Outzen Olaf , Spangehl Thomas
Published: March 2022

The Offshore Wind Energy Act (Windenergie-auf-See-Gesetz - WindSeeG) legally requires annual tender procedures for sites in the North Sea in the Exclusive Economic Zone of Germany for the construction of wind turbines. The Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie - BSH) conducts so called preliminary investigation of sites (PIS), pursuant to §10 WindSeeG. These include investigations of the wind conditions at the site, to give the interested firms information for calculating a bid. The preliminary investigation of the wind conditions is conducted together with the German Weather Service (Deutscher Wetterdienst) and is based on three elements: a measurement campaign at the site for one year, an evaluation of reanalysis data by the German Weather Service, and a report which brings together all available information about the wind conditions. These reports are published together with the measurement and model data and the results of all other preliminary investigations via the PIS-Data Hub https://pinta.bsh.de as part of the tendering process.

The sites that are dedicated for the construction of wind turbines are defined in the Site Development Plan (Flächenentwicklungsplan), together with the year of the intended tendering process. The first PIS have been successfully completed for two sites in the southeastern North Sea and for one site in the Baltic Sea in March 2021. In the years 2022 and 2023, a call for tender for sites N-3.5, N-3.6 and N-7.2 will be published. These sites are located in the southwestern part of the German Exclusive Economic Zone in the North Sea. At or near these sites, meteorological measurements have been conducted, using a floating lidar which was installed on a buoy (site N-7.2) as well as scanning lidars installed on the transition pieces of wind turbines (N-3.5, N-3.6). These measurements resulted in time series of vertical profiles of wind direction and speed, covering one year each, and giving information about the wind conditions at the sites at relevant heights of future wind turbines. In addition, temperature, relative humidity, air pressure, and sea surface temperature were measured.
Understanding coastal groundwater processes in a changing climate: A perceptual model of global-scale coastal groundwater dynamics
Authors: Kretschmer Daniel , Reinecke Robert , Moosdorf Nils , Michael Holly , Wagener Thorsten
Published: March 2022

Groundwater is the primary drinking water supply of billions of people worldwide. While groundwater is under pressure globally due to extensive water abstractions, proximity to coasts amplifies these pressures due to potential sea water intrusion that can endanger groundwater quality. It is unclear how climate change (changing potential groundwater recharge), as well as rising sea levels, will alter coastal groundwater dynamics, i.e., submarine groundwater discharge and seawater intrusion.

Various factors impact coastal groundwater dynamics, including groundwater recharge & extraction, hydraulic gradients, permeabilities, water densities, and oceanic activity (e.g., tidal pumping and wave setup). It is currently unclear how much these different factors control submarine fluxes along global coastlines. We developed perceptual models of coastal groundwater fluxes based on a literature review of regional and global models. Here we present our perceptual model and discuss it in the context of currently available global data, uncertainties, climate change, and whether it can be implemented with an existing Open Source global groundwater modeling framework (G³M-f).
A Monte Carlo-Based Approach to Image Active 3D Fault Systems from Relocated Hypocenters
Authors: Truttmann Sandro , Diehl Tobias , Herwegh Marco
Published: March 2022

Despite the generally accepted concept that most earthquakes occur along pre-existing faults, the complex 3D geometries of seismically active fault systems at depth often remain unresolved. However, earthquake nucleation and migration processes are heavily influenced by the geometries and properties of such pre-existing structures, which limits our general understanding of earthquake nucleation and fault interactions.

Under the assumption that faults are reactivated at spatially and temporally different localities, previous studies have attempted to derive fault geometries from hypocenter locations, but were usually limited by the precision of relocation techniques. Enabled by the recent advances in hypocenter relocation techniques, we present a novel Monte Carlo-based method that uses relatively relocated hypocenters and their uncertainties to image geometries, stress states and kinematics of seismically active fault systems. The application of the developed Python toolbox on a natural earthquake sequence along the Rhone-Simplon fault zone in the northern Valais (Swiss Alps) reveals active strike-slip faults with a contractional stepover. Performed stress analyses indicate varying stress states along the fault system, which has direct implications for fault properties such as the reactivation potential or the fluid transmissivity. Overall, we document the migration of an earthquake swarm across a complex strike-slip fault system at an unprecedented spatiotemporal resolution.

Our toolbox can be applied to high-precision hypocenter catalogs of natural earthquake sequences or hydraulic stimulation experiments, which could help to improve our understanding of the role of pre-existing faults on earthquake nucleation and migration processes at various scales.
Towards a new autumn phenology model integrating seasonal productivity, climate, and day length
Authors: Zohner Constantin M. , Mirzagholi Leila , Bucher Raymo , Renner Susanne S. , Mo Lidong , Palouš Daniel , Vitasse Yann , Crowther Thomas W.
Published: March 2022

Predicting the timing of autumn leaf senescence in northern trees remains challenging because the seasonal interplay in the effects of day length, climate, and plant productivity is not well understood. This severely limits our ability to forecast vegetation activity and carbon uptake in temperate and boreal ecosystems. Here we present a new framework for predicting autumn senescence dates based on the idea that day length mediates the effects of climate on autumn phenology, with early-season (pre-solstice) growth and late-season temperatures constituting antagonistic forces. To test these predictions, we used a combination of satellite-derived vegetation productivity across Northern Hemisphere forests, ground-sourced European phenology observations of four widespread tree species, and a climate-manipulation experiment on European beech. Our results reveal important constraints on the late-season carbon uptake potential of northern trees, improving our understanding of vegetation dynamics in response to climate change.
Seasonal variation of dissolved Cs-137 concentrations in headwater catchments in Yamakiya district, Fukushima Prefecture
Authors: Kawano Taichi , Onda Yuichi , Takahishi Junko , Makino Fumiaki , Iwagami Sho
Published: March 2022

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred on March 11, 2011, and a large amount of Cs-137 was released into the environment. It is important to clarify the behavior of radioactive cesium-137 in headwater catchments because most of the Cs-137 falls and is deposited in forest areas and is transported in the environment through river systems.

The purpose of this study was to clarify the influence of water quality composition and organic matter on the seasonal variation of dissolved Cs-137 concentrations in stream water based on long-term monitoring since 2011 at four headwaters catchments in Yamakiya district, Fukushima Prefecture (Iboishiyama, Ishidairayama, Koutaishiyama, Setohachiyama), located about 35 km northwest of FDNPP.

Water temperature, pH, and EC were measured in the field, and SS and coarse organic matter were collected using a time-integrated SS (suspended sediments) sampler and organic matter net. The Cs-137 concentrations was measured in the laboratory using a germanium detector. Concentrations of cations (Na⁺,K⁺,Ca²⁺,Mg²⁺,NH₄⁺) and anions (Cl⁻,SO₄²⁻,NO₃⁻,NO₂⁻,PO₄²⁻) were measured by ion chromatography after 0.45μm filtration. In addition, dissolved organic carbon (DOC) concentrations was measured using a total organic carbon analyzer.

The results showed that K⁺, which is highly competitive with Cs-137, was detected at Iboisiyama, Ishidairayama, and Koutaishiyama, while NH₄⁺ was only detected in some samples at Iboishiyama. There was no obvious relationship between dissolved ion concentration and water temperature, and between dissolved ion concentration and dissolved ¹³⁷Cs concentration at all sites. However, a positive correlation between dissolved cesium concentration and water temperature and DOC and water temperature was observed at all sites regardless of the presence of K⁺ and NH₄⁺. On the other hand, there was no clear relationship between the cesium concentrations in SS and organic matter and water temperature. These results suggest that the seasonal variation in dissolved Cs-137 concentrations in stream water with water temperature could be caused by the seasonality of microbial decomposition of organic matter.
Inflation at Askja, Iceland. New and revisited relative microgravity data.
Authors: de Zeeuw van Dalfsen Elske , Sepulveda Araya Josefa , Hooper Andy , Sigmundsson Freysteinn , Sturkell Erik , Li Siqi , Lanzi Chiara , Koymans Mathijs , Giniaux Jeanne
Published: March 2022

In August 2021 Askja caldera in Iceland started to show uplift after decades of subsidence. The uplift signal is centered at the northwestern edge of lake Ӧskjuvatn and an order of magnitude larger than the subsidence in the last decade. In September 2021 a geodesy campaign was carried out at Askja, including relative microgravity measurements acquired with the use of two Scintrex CG-5 instruments. Relative microgravity campaigns at Askja are not straightforward due to the long walking distances between sites, which makes a “double loop” procedure impossible. We revisit existing Scintrex relative microgravity data sets (2015 onward) and analyse data using the same joint weighted least squares inversion routine. We define recommendations for future relative microgravity campaigns at Askja which will be important to establish the cause of the ongoing uplift. The density of subsurface magma is only identifiable with microgravity data. Knowledge of the type of magma accumulating under Askja is vital to assess possible hazard implications.
The effect of vertical urban greening on historical building materials
Authors: De Groeve Marie , Kale Eda , Orr Scott Allan , De Kock Tim
Published: March 2022

Due to hard coverage and building infrastructures, cities experience higher temperatures and higher pollution levels in their city centre relative to their less dense surroundings. This urban heat island effect is receiving an increasing amount of attention and concern. In response, cities are implementing green initiatives to mitigate elevated temperature and pollution levels, improving the health and well-being of their residents. However, the urban heat island is typically the largest in the historical core of the city, where the abundance of built heritage can make the implementation of green initiatives difficult. The dense urban fabric and the rules of conservation make such an implementation inconvenient. A major concern is how green initiatives might affect the condition of the historical building materials.

Therefore we scope the compatibility of vertical greening with built heritage, in terms of microclimatic changes, and considering impacts of salt crystallization, frost events, biodeterioration and pollutant deposition. The vertical greening represents vegetation growing along exterior walls. Either plants, rooted on the ground, climb up the facade by attaching themselves on the vertical surfaces or plants hang down from the top of the facade. Monitoring case studies in Antwerp and laboratory studies will help us investigate key changes, beneficial or adverse, in the material condition of heritage buildings. This project will develop our understanding of the relationship between the green initiatives and the historical materials in an urban area.
New sedimentological evidence of Lake Victoria’s palaeohydrological variability during the last deglacial transition (16-10 kyr BP)
Authors: Wienhues Giulia , Temoltzin-Loranca Yunuén , Vogel Hendrik , Grosjean Martin
Published: March 2022

The East African (hydro-)climate response to perturbations during the deglacial transition (e.g. Older and Younger Dryas) is complex and expressed heterogeneously in different paleoclimatic records. Lake Victoria (LV), Africa’s largest lake, desiccated entirely during the dry last glacial (>16.3 kyr BP) and subsequently refilled as climate conditions got more humid, reaching a highstand during the Early Holocene. However, existing sediment records from LV do not have sufficient resolution to fully resolve short-term hydroclimate changes during the deglacial transition (especially between 14 and 11 kyr BP). There is little direct evidence of late-glacial lake level fluctuations in LV so far because intermediate water depth coring sites suitable to record intermittent lowstands are missing.

By analysing sediment cores along a near-shore/shallow water (current water depth 22 m) to offshore/deep water (current water depth 63 m) coring transect covering the past 16,000 years, we aim at a more accurate spatial and temporal reconstruction of LV’s deglacial lake level history in response to regional hydroclimate changes.

Core stratigraphy and geochemical evidence, combined with a robust radiocarbon chronology, demonstrate a stepwise infilling of the Lake Victoria basin after its last complete desiccation (< 16.3 kyr BP). Following the dry late glacial Heinrich 1 event, an intermediate water level prevailed between 16.3 and 14.4 kyr BP, with uninterrupted deposition of fine-grained, organic matter-rich pelagic muds at our deep-water site and coarser, sandy-clay deposits at the near shore site. A second dry episode during the Older Dryas (~14 kyr BP) is marked by an abrupt decline in lake level with deposition of coarse mollusc shell bearing sediments at the near shore site indicating a littoral depositional environment. This shift in hydroclimate in the Lake Victoria basin is congruent with a brief period of cooling and drying during the Bölling/Alleröd (Dansgard Oeschger Event 1), which is also recorded in other East African Lakes. Subsequently, Lake Victoria reached maximum water levels with the onset of the African Humid Period in the early Holocene at around 11 kyr BP, which is expressed by elevated input of chemically weathered material (e.g. Rb/K) and deposition of fine-grained muds at both the near shore and offshore sites.
The medium energy electron direct effect on mesospheric dynamics during a sudden stratospheric warming event in 2010
Authors: Nesse Tyssøy Hilde , Zúñiga Héctor Daniel  López , Smith-Johnsens Christine , Maliniemi Ville
Published: March 2022

Medium energy electron (MEE) (30-1000 keV) precipitation enhances the production of nitric (NOx) and hydrogen oxides (HOx) throughout the mesosphere, which can destroy ozone (O3) in catalytic reactions. The dynamical effect of the direct mesospheric O3 reduction has long been an outstanding question, partly due to the concurrent feedback from the stratospheric O3  reduction. To overcome this challenge, the Whole Atmosphere Community Climate Model (WACCM) version 6 is applied in the specified dynamics mode for the year 2010, with and without MEE ionization rates. The results demonstrate that MEE ionization rates can modulate temperature, zonal wind and the residual circulation affecting NOx transport. The required fluxes of MEE to impose dynamical changes depend on the dynamical preconditions. During the Northern Hemispheric winter, even weak ionization rates can modulate the mesospheric signal of a sudden stratospheric warming event. The result is a game changer for the understanding of the MEE direct effect.
A new machine learning-based data assimilation technique to detect volcanic unrest from tremor
Authors: Girona Társilo , Caudron Corentin
Published: March 2022

Linking geophysical and geochemical observables with subsurface processes is crucial to detect volcanic unrest and better anticipate eruptions. One of the most important observables to monitor pre-eruptive volcanic activity is tremor, a more or less persistent, highly periodic, ground vibration recorded near active vents. Tremor is commonly being monitored in near real-time by volcano observatories to anticipate unrest, as it may emerge, or change properties, when subsurface pressure varies. For example, it has been observed that the dominant frequency of tremor may glide towards higher or lower values before eruptions; overtones may appear or disappear; and seismic amplitude may increase or decrease. However, similar variations can be also observed during quiescence and when activity decreases. This leads to the following questions: How does tremor actually reflect the overpressure of the subsurface? Can we infer when and where the pressure beneath active vents increases or decreases by monitoring volcanic tremor? In this work, we present a new data assimilation technique that combines new physics-based models of volcanic tremor with a machine learning-based inversion algorithm to track pressure changes beneath volcanic craters in near-real time. In particular, our inversion algorithm is based on a supervised random forest classifier trained with synthetic data, whereas our physics-based model extends from Girona et al. (2019) and is based on a stop-and-go mechanism, i.e., tremor is assumed to emerge when: (i) gas is supplied randomly to shallow levels of the volcanic plumbing system; (ii) accumulates temporarily beneath permeable caps (e.g., beneath a dome or in a leaky fracture); and (iii) transfers via permeable flow to the surface. Using this machine learning-based data assimilation technique, we find that the recent 2013 unrest phase of Kawah-Ijen volcano (Indonesia) was driven by a pressure increase in the subsurface of a factor 2-to-5. This technique is currently also being applied to unveil the pressure history of the shallow vents of Pavlof and Veniaminof volcanoes (Alaska). 

Girona, T., C. Caudron, C. Huber (2019). Origin of shallow volcanic tremor: the dynamics of gas pockets trapped beneath thin permeable media. J. Geophys. Res., doi: 10.1029/2019JB017482.
Classifying offshore faults for hazard assessment: A new approach based on fault size and vertical displacement
Authors: Laor May , Gvirtzman Zohar
Published: March 2022

For many countries, the methodology for offshore geohazards mitigation lags far behind the well-established onshore methodology. Particularly complicated is the mapping of active faults. One possibility is to follow the onshore practice, i.e., identifying a sub-seabed Holocene horizon and determining whether it displaces this horizon for each fault. In practice, such an analysis requires numerous coring and often ends without an answer.   

Here we suggest a new approach aimed for master planning. Based on high-quality seismic data, we measure for each fault the amount of its recent (in our specific case 350 ky) displacement and the size of its plane. According to these two independently measured quantities, we classify the faults into three hazard levels, highlighting the “green” and “red” zone for planning.

Our case study is the Israeli continental slope, where numerous salt-related, thin-skinned, normal faults dissect the seabed, forming tens of meters high scarp, which are crossed by gas pipelines. A particular red zone is the upper slope south of the Dor disturbance, where a series of big listric faults rupture the seabed in an area where the sedimentation rate is four times faster than the displacement rate. We suggest that this indicates seismic rupture rather than creep.
Fingerprints of provenance in atmospheric dust collected at Granada city (Southern Iberian Peninsula).
Authors: Molinero-García Alberto , Martín-García Juan Manuel , Fernández-González María Virginia , Delgado Rafael
Published: March 2022

Dust in the Earth´s atmosphere and deposition rates are both increasing in last decades. The south of Iberian Peninsula is deeply affected by air masses coming from Africa, one of the largest sources of atmospheric dust in the world (50%–70% of total emissions worldwide). Granada city (south of the Iberian Peninsula) has one of Spain’s highest atmospheric pollution levels (including particulate matter). African dust intrusion should be considered in the Iberian Peninsula because of the proximity of the Sahara Desert. Dust properties allows for a hypothesis on dust-provenance and dust-origin. Our study characterised atmospheric dust collected in Granada city during three monthly periods: 4PA (2012), 16PA (2013), and 28PA (2014). The main goal was to determine dust characteristics and genesis using a set of different techniques. The backward trajectories study separated the samples, according to their Saharan influence, into two groups: a) scarce influence (sample 16PA, 6% of days with Saharan influence); b) greater influence (samples 4PA and 28PA, ≈30% of days with Saharan influence). The two groups was confirmed by all the properties analysed, namely, PM10 concentration, deposition rates, grain size, mineralogy, and elemental composition (minor, including rare earth elements). Our samples showed similarities with soils from the Iberian Peninsula and other atmospheric dust collected in Granada. A remarkable discover was that particle morphology and surface microtextures on atmospheric quartz also verified the grouping. A principal component analysis of the quartz shape parameters insists on the differentiation of these groups, therefore we propose, as a fingerprint of provenance, the morphoscopy of atmospheric quartz grains (a main component of atmospheric dust).
Application of the International Guidelines on Natural and Nature Based Features for Flood Risk Management and the way forward
Authors: Schielen Ralph , Spray Chris , Haring Chris , Guy Jo , Burgess-Gamble Lydia
Published: March 2022

In 2021, the International Guidelines on Natural and Nature Based Features for Flood Risk Management  were published, as a result of a joint project between the Rijkswaterstaat (Netherlands), the Environment Agency (England) and the Army Corps of Engineers (USA). These Guidelines give direction in the application of Nature Based Solutions (NBS) for coastal and fluvial systems. In this contribution we will focus on the fluvial part of the guidelines. We will briefly discuss the process that lead to the origin of the Guidelines and discuss the intended use. It is important to realize that the location within a catchment, and the scale of a catchment determine the specifications of the most optimal NBS. Considering the classical ‘source-pathway-receptor’ approach, in the source of a catchment, NBS aim to hold back the water in the headwaters of larger catchments, enhancing management of water and sediment. In the pathways-receptor (floodplains),  NBS are more focussed on increasing the discharge capacity of the main stem. In smaller catchments, also temporarily storage of water in the floodplains occurs, if flooding of such a temporary nature can be accommodated. Rather than a detailed instruction guide, the Guidelines are intended to give best practices and list important points of attention when applying NBS. Furthermore, they act as inspiration through the many case studies that are listed.

We will also connect the Guidelines to other initiatives on the application of NBS, for example the impact that NBS might have on reaching the United Nations Sustainable Development Goals. This requires a proper assessment framework which has been developed in adjacent projects and which values the added co-benefits that NBS have, compared to grey or grey-green alternatives. These benefits are also addressed in the Guidelines. Finally, we will share some thoughts on upscaling and mainstreaming NBS and the actions that are needed to accomplish that.
Interseismic Strain Accumulation Along The Tabriz-Van (Iran-Turkey) Shear Zone
Authors: Nozadkhalil Tohid , Çakir Ziyadin , Ergintav Semih , Özakin Arkadaş
Published: March 2022

In order to improve our understanding of the present-day  continental deformation in the Iranian-Turkish plateau we map the surface motions across the Iranian-Turkish boundary between Ardabil (NW Iran) and Van (E Turkey) using Sentinel-1 satellites’ TOPSAR data between 2014 and 2021 on descending (6, 79, 152) and ascending (101, 174 and 72) tracks. Interferograms generated with GMTSAR are used to calculate PS-InSAR time series with the multi-temporal InSAR analysis tools of the StaMPS software. Mean line of sight (LOS) velocity fields reveal a dominant right-lateral shear zone between Tabriz and Van acting as a boundary between Eurasian and Arabian plates. The Tabriz-Van shear zone (TVSZ) comprises the North Tabriz, Kotur, Ozalp and Ercis faults. We model the LOS velocity fields using TDEFNODE, a fortran package for block modelling and estimate slip rates and locking depthes along the TVSZ. The best fitting model suggests a 9±2 km of looking depth and a westward increasing slip rate from 7 to 10±2 mm/yr, consistent with GNSS observations. To the west the TVSZ appears to join with Karliova Triple Junction (KTJ). This dextral slip fault zone accommodates a part of motion resulting from the Arabia–Eurasia collision and has experienced a westward migration in M > 5 events since the 18th century including the 18th and 19th century M > 7 events along the North Tabriz Fault. 
How to calibrate a climate model with neural network based physics?
Authors: Balogh Blanka , Saint-Martin David , Ribes Aurélien
Published: March 2022

Unlike the traditional subgrid scale parameterizations used in climate models, current neural network (NN) parameterizations are only tuned offline, by minimizing a loss function on outputs from high resolution models. This approach often leads to numerical instabilities and long-term biases. Here, we propose a method to design tunable NN parameterizations and calibrate them online. The calibration of the NN parameterization is achieved in two steps. First, some model parameters are included within the NN model input. This NN model is fitted at once for a range of values of the parameters, using an offline metric. Second, once the NN parameterization has been plugged into the climate model, the parameters included among the NN inputs are optimized with respect to an online metric quantifying errors on long-term statistics. We illustrate our method with two simple dynamical systems. Our approach significantly reduces long-term biases of the climate model with NN based physics.
Thoughts on cooking up a virtual field-trip in Google Earth and its digestion
Authors: Fernández Oscar
Published: March 2022

Field work is one of the fundamental tools for teaching structural geology. Remote teaching conditions over the past two years have represented a major challenge to in-person field trips with students. Whereas online and outdoor teaching are completely different in nature, online activities can be used to reach many of the objectives typically associated with in-person teaching.

In this presentation I will discuss the example of a 2-hour virtual field-trip organized for a specialist audience composed of experienced structural geologists and experienced geologists from other disciplines. The field trip was run to the Northern Calcareous Alps (Austria) and deals with brittle tectonics (mainly salt tectonics). The same field trip has later been modified (simplified) and offered to a mixed background of geoscientists. Both experienced structural geologists and a mixed audience were surveyed after the end of the field trip.

Feedback indicates that the virtual field trip proved to be a time- and resource-effective way of delivering overview content and fostering targeted discussion. Of particular value was the fact that the virtual environment made it possible for attendees to individually explore information in a georeferenced setting (in Google Earth) and key outcrops that had been generated in 3D and loaded to an open website (www.sketchfab.com).

Attendees also noted that the main drawbacks of the virtual setting were being at the usual workplace and the lack of the opportunity to think and discuss during field stops. They also highlighted that the single most critical factor in making a virtual field trip a success is the instructor (over other factors such as length or format of the field trip material). Finally, attendees mostly indicated that the virtual field trip would not replace an in-person experience, but rather acts as a complement.

Although the experience obtained with this field trip is limited and lacks a comparison to the equivalent in-person field-trip, it supports the idea that virtual field-trips can be used as: 1) complementary activities to in-person field-trips, particularly to deliver pre-trip background; 2) a cost- and time-effective way of delivering project results and enabling peer-to-peer discussions.
Modeling and evaluation of vegetation and carbon dynamics of European forest sites with CLM-FATES
Authors: Naz Bibi S. , Poppe Christian , Hendricks-Franssen Harrie-Jan , Vereecken Harry
Published: March 2022

Vegetation plays an important role in global carbon and water cycles. Long-term environmental changes modify vegetation distributions and consequently impact fluxes of carbon, water and energy. Vegetation dynamic models are useful tools to analyze terrestrial ecosystem processes and can simulate the impact of vegetation structure changes on carbon and water cycles and their interactions with climate when coupled to land surface models. Because of the complexity to represent plant growth processes, these models typically have a large number of parameters that can potentially contribute to uncertainty in model results and need to be adequately parameterized. In this study, we used the Community Land Model (CLM v5) coupled to the Functionally Assembled Terrestrial Simulator (FATES) and applied it to four forest sites from the database of European Long-Term Ecosystem Research Infrastructures (eLTER) which provides a wide range of observational data to calibrate and evaluate vegetation models. Using this database, we performed sensitivity analysis to evaluate parameter uncertainties in model results for forest growth, gross primary production, leaf area index, evapotranspiration, soil water content and soil temperature. We also explored the sensitivity of model parameters for different vegetation distributions and climate conditions. The results of this study allow us to understand the vegetation dynamics and their impact on carbon and water fluxes which will be helpful to improve model parameterization and to provide more accurate estimates of carbon and water fluxes and climate model projections.
Top-down controls on the ecological niche of marine N2 fixers
Authors: Landolfi Angela , Prowe A. E. Friederike , Pahlow Markus , Somes Christopher J. , Chien Chia-Te , Schartau Markus , Koeve Wolfgang , Oschlies Andreas
Published: March 2022

The factors that control the distribution of marine diazotrophs and their ability to fix N₂ are not fully elucidated. We discuss insights that can be gained from the emerging picture of a wide geographical distribution of marine diazotrophs and provide a critical assessment of environmental (bottom-up) versus trophic (top-down) controls. Expanding a simplified theoretical framework, we find that selective mortality on non-fixing phytoplankton is identified as a critical process that can broaden the ability of diazotrophs to compete for resources in top-down controlled systems and explain an expanded ecological niche for diazotrophs. Our simplified analysis predicts a larger importance of top-down control on competition patterns as resource levels increase. As selective mortality can control the faster growing phytoplankton, coexistence of the slower growing diazotrophs can be established. However, these predictions require corroboration by experimental and field data, together with the identification of specific traits of organisms and associated trade-offs related to selective top-down control. Elucidation of these factors could greatly improve our predictive capability for patterns and rates of marine N2fixation.

 