bluuebunny/crossref_metadata_2025 huggingface dataset:
Controls on the characteristics and distribution of sedimentary organic matter in the Western Mediterranean Sea 
Authors: Ausin Blanca , Paradis Sarah , Bossert Gina , Haghipour Negar , Eglinton Timothy
Published: March 2022

Marine sediments comprise the primary long-term sink of organic matter (OM) in marine systems. A key mechanism for stabilization of OM in marine sediments occurs via protection on mineral surfaces. However, fine-grained minerals are prone to resuspension and redistribution prior to final burial, potentially further exposing OM to degradation. Here, we examine the sedimentological properties and geochemical characteristics of organic carbon (OC) in surface sediments from the Western Mediterranean Sea to shed light on the origin of OM and the underlying mechanisms that determine its fate in this semi-enclosed basin. We analysed the isotopic (ẟ13C, ẟ15N, and Δ 14C) and elemental (carbon and nitrogen content and C/N) composition of OC in 104 surface sediments retrieved from the Western Mediterranean Sea and the adjacent Atlantic Ocean, west of the Strait of Gibraltar. Corresponding grain-size and mineral surface area data were used to shed light on OM-mineral relationships and sedimentary transport mechanisms. The influence of this latter process was further evaluated by comparing the 14C age of OC and planktic foraminifera and analysing excess 210Pb concentration in surface sediments. The OC content and ẟ13C and Δ 14C signatures depict a clear SW-NE gradient defined by strong differences between the westernmost (Alboran Sea) and the easternmost sub-basins (Northwestern and Balearic Sea). This gradient is attributed to differences in local primary productivity and delivery of terrestrial OC. When explored in a sedimentological context, our results suggest that both OM protection via association with mineral surfaces and selective degradation of labile OM during secondary transport plays an important role magnifying the contrast between endmembers manifested in these geochemical gradients.
Improved removal performance of Gram-negative and Gram-positive bacteria in sand filtration system with arginine modified biochar amendment
Authors: Mengya Zhang , Tong Meiping
Published: March 2022

Bacterial removal by sand filtration system is commonly inefficient due to the low bacterial adsorption capacity of sand. To improve the bacterial removal performance, biochar fabricated at different temperatures (400 °C, 550 °C and 700 °C) and arginine modified biochar were added into sand filtration columns as filter layers (0.5 and 1 wt%). Addition of biochar into sand columns could improve the removal efficiency for both Escherichia coli and Bacillus subtilis under both slow (4 m/day) and fast (240 m/day) filtration conditions. Bacterial removal efficiency in sand columns with the addition of biochar fabricated at 700 °C were higher than those fabricated at 400 °C and 550 °C due to its best bacterial adsorption capacity. Modification of biochar with arginine could further improve the bacterial removal performance. Specifically, complete bacterial removal (1.35×107 ± 10% cells/mL) could be achieved under both slow and fast filtration conditions in sand columns with 1 wt% arginine functionalized biochar amendment. The enhanced bacterial adsorption capacity mainly contributed to the increased bacterial capture performance in columns with addition of arginine-modified biochar. Bacteria more tightly bounded with arginine-modified biochar than bulk biochar. Moreover, complete bacterial removal with the copresence of 5 mg/L humic acid in suspensions was acquired in columns with addition of 1 wt% arginine-modified biochar. Efficient bacterial removal in actual river water, multiple filtration cycles as well as longtime injection duration (100 pore volumes injection) was also obtained. The results of this study demonstrated that arginine-modified biochar had great potential to treat water contaminated by pathogenic bacteria.
Tectono-thermal evolution of the External Western Alps (France): evidence for rift-related thermal event
Authors: Célini Naïm , Mouthereau Frederic , Lahfid Abdeltif , Gout Claude , Callot Jean-Paul
Published: March 2022

Raman Spectroscopy on Carbonaceous Material (RSCM) approach is commonly used to calculate thermal peaks recorded by rocks. A first calibration of the RSCM was developed to measure temperatures ranging from 330°C to 640°C (Beyssac et al., 2002). Its applicability was later expanded to lower temperatures from 200°C to 350°C (Lahfid et al., 2010). Here, we apply the RSCM approach to Digne Nappe area - thrust front of the SW Alps - in order to evaluate the thermal evolution of the sub-Alpine domain from rift to the present. About 150 temperatures have been obtained along seven continuous stratigraphic sections sampled along the strike the whole Digne thrust sheet. The base of the Digne thrust sheet (i.e. the Lias syn-rift carbonates) shows temperatures ranging from 250°C to 330°C. These temperatures are 200-240°C in post-rift marls dated to Callovian-Oxfordian and rapidly drop upsection in the Kimmeridgian-Tithonian carbonates and younger Cretaceous rocks to temperatures below 100-120°C. While these temperatures are seen to decrease from bottom to top we note the lack of well-defined apparent geothermal gradients. One of our section (Serre-Ponçon) structurally positioned beneath the Embrunais-Ubaye thrust sheets is remarkable because the temperatures are rather homogeneous, ranging between 300°C and 350°C along the whole 5km-thick sedimentary pile from the Lias until the Eocene. The regional dataset suggests that the thermal history of the sub-Alpine fold-and-thrust belts varies along-strike and requires the succession of several thermal events. The drop of temperatures observed in the Late Jurassic sediments is interpreted to be related to increasing heat flow during crustal thinning associated to the formation of the Alpine Tethys rifted margin.  The high temperatures observed along the Serre-Ponçon specifically indicate a burial beneath the Embrunais-Ubaye thrust sheets during Alpine orogeny, possibly combined with high geothermal gradients inherited from the Mesozoic Alpine Tethys thinning phase.
Regionalizing the Sea-level Budget Using a Neural Network Approach
Authors: Machado Lima de Camargo Carolina , Marcos Marta , Hernandez-Carrasco Ismael , Hermans Tim H.J. , Riva Riccardo E.M. , Slangen Aimée B.A.
Published: March 2022

Understanding the drivers of present-day sea-level change is vital for improving sea-level projections and for adaptation and mitigation plans against sea-level rise. Sea-level budget (SLB) studies focus on attributing the observed sea-level change to its different drivers (steric and barystatic changes). While the global mean SLB is closed, explaining the drivers of sea-level change on a finer spatial scale leads to large discrepancies. Recent studies have shown that closing the regional budget on a regular 1x1˚ grid is not possible due to limitations of the observations itself, but also due to the spatial patterns and variability of the underlying processes. Consequently, the regional budget has been mainly analyzed on a basin-wide scale.

 In this study we use Self-Organizing Maps (SOM), an unsupervised learning neural network, to extract regions of coherent sea-level variability based on 27 years of satellite altimetry data. The SOM clusters have a higher level of spatial detail compared to entire ocean basins, while being large enough to allow for a consistent sea-level budget analysis. The clusters also show how sea-level variability is interconnected among different ocean regions (for example, due to large-scale climate patterns). We perform the clustering analysis on the Atlantic and Indo-Pacific Oceans separately, obtaining a total of 18 clusters. Preliminary results show that we can close the sea-level budget from 1993-2017 in 67% of the clusters. The regions with discrepancies highlight important regional processes that are affecting sea-level change and have not thus far been included in the sea-level budget. In this way, using neural networks provides new insight into regional sea-level variability and its drivers.
Portable low cost devices for in situ measurements of CO2 exchange and vegetation spectral indices: Design and first results.
Authors: Macagga Reena , Antonijevic Danica , Monzon Rodrigo , Bayot Rinan , Lueck Matthias , Asante Michael , Sossa Leonce Geoffroy , Sanchez Pearl , Augustin Juergen , Hoffmann Mathias
Published: March 2022

Measurements of greenhouse gas (GHG) emissions such as carbon dioxide (CO­­2) play an important role in finding solutions to mitigate the global climate crises. In case of direct treatment comparisons, dynamic manual closed chamber systems are often used to measure the CO2 exchange and determine the treatment corresponding net ecosystem C balance (NECB). These measurements are commonly accompanied by records of non-destructive spectral vegetation indices such as RVI and NDVI, which can be used to validate obtained CO2 flux dynamics, to improve the accuracy and precision of determined CO2 exchange during gap-filling, and for up-scaling purposes. However, commercially available systems for both measurements of CO2 exchange and spectral vegetation indices are usually cost-intensive, which resulted in a long-term focus in GHG research on the northern hemisphere and the fact that studies on agroecosystems in sub-Saharan Africa as well as Southeast Asia are still being underrepresented.

We present two portable, inexpensive, open source devices to measure in situ 1) CO2 fluxes using the manual closed chamber method; and 2) vegetation spectral indices, such as NDVI and RVI. The CO2 flux measurement device consists of a combination of multiple low-cost sensors, such as a NDIR-based CO­2 sensor (K30FR; 0-10,000 ppm, ± 30 ppm accuracy), a DHT-22 (humidity and temperature) and a BMP280 (air pressure). Sensors are connected to a bluetooth enabled, battery powered, compact microcontroller based logger unit for data visualization and storage.  The handheld, NDVI measurement device consist of a combination of two faced up and two faced down visible (AS7262) and IR (AS7263) sensors, as well as a CCS811 and BME280 for parallel measurements of relevant environmental parameters (e.g., ambient temperature and relative humidity). Sensor control, data visualization and storage is implemented using again a bluetooth enabled, battery powered, compact microcontroller based logger unit. Here, we present the design, and first results of both low-cost devices. Results were validated against results of customized CO2 and NDVI measurement systems using regular scientific sensors (LI-COR 850 and SKR 1840(ND) and data logger components (CR1000). 

Keywords: CO2 exchange measurements, closed chamber, NDVI, low-cost open source DIY device
Assessment of drought index response to changes in forest cover across different climate zones
Authors: Li Yan , Rust Henning W.
Published: March 2022

Drought is a complex climatic hazard with major impacts on both human and natural system. It is very likely leading to agricultural loss, forest mortality and drinking water scarcity. In recent years, the occurrence frequency and intensity of droughts has been increasing within a warming climate. This poses serious threats to future food security, ecosystem (e.g., changing the forest structure and carbon content) and fresh water stress for small islands. Precipitation, temperature and other atmospheric factors have an influence on the drought conditions. Furthermore, the impact of land cover change on climate mostly on precipitation and temperature has been established in previous studies. To our best knowledge, the effect of change in land cover, especially in large forest cover, on droughts is largely unexplored. This, however, is important to understand the impact of land cover on climate variability and the sensitivity of the droughts to changes in the climate. This study aims at quantifying the effect of forest cover change and changing meteorological factors  on long-term and short-term droughts across four different climate regions (i.e. equatorial, arid, temperate and snow region).

We analyse the influence of forest cover changes to droughts. Meteorological data (precipitation and temperature), land cover dataset, and drought indices (the Palmer Drought Severity Index and the Standardized Precipitation Evapotranspiration Index) for almost 30 years are used to study the influence of forest cover fraction variability on droughts for different time scales and across different climate zones. Linear model and analysis of variance (ANOVA) have been used in the analysis to explore how forest cover changes impact on the drought occurrence frequency and intensity. Our findings can be used in making policy decision involved in forest management and water resource planning. 
High soil organic carbon losses in response to forest windthrow 
Authors: Mayer Mathias , Rusch Silvan , Didion Markus , Baltensweiler Andri , Walthert Lorenz , Zimmermann Stephan , Hagedorn Frank
Published: March 2022

Storms represent a major disturbance factor in forest ecosystems, but the effects of windthrows on soil organic carbon (SOC) stocks are quantitatively poorly known. Here we present a comprehensive analysis of windthrow-induced changes in SOC stocks in Swiss forests by combining field-based measurements and modelling simulations. We measured the SOC stocks of 19 windthrown forests across Switzerland, about 10 and 20 years after they were disturbed by the storms ‘Lothar’ and ‘Vivian’ and compared them to the stocks of adjacent intact forests. We also calibrated the process-based model Yasso07 for additional 77 windthrown forests. Our results show that the effect of windthrow on SOC is strongly related to the size of the initial SOC stocks in the organic layer. In absolute and relative terms, the largest SOC losses occurred in high-elevation forests with thick organic layers, where initial SOC stocks decreased by up to 90% (or 30 t C ha-1). In contrast, SOC stocks of low-elevation forests with thin organic layers were hardly affected. The likely reason for this pattern is the high stocks of easily mineralizable organic matter in thick organic layers of mountain forests, while at low elevations a greater SOC fraction is stabilized by mineral interactions. Modelling simulations further show longer-lasting SOC losses and a slower recovery of SOC stocks after windthrow at high-elevations compared to low-elevations, due to a slower regeneration of mountain forests and associated lower C inputs into soils. We also upscaled the SOC changes after windthrow to the whole forested area of Switzerland and estimated a total SOC loss of ~0.3 Mt C after the storms ‘Lothar’ and ‘Vivian’. Our results provide strong empirical evidence that windthrows can reduce the SOC stocks of forest ecosystems, with mountain forests being hotspots for SOC losses.
A global stratification product of the thermocline based on Argo observations
Authors: Roch Marisa , Brandt Peter , Schmidtko Sunke
Published: March 2022

Enhanced ocean stratification is projected as a result of a warming climate. Changes of upper-ocean stratification can have a potential impact on physical as well as biogeochemical and ecological processes, such as ocean circulation and redistribution of heat and salt, ocean ventilation and air-sea interactions and in addition, nutrient fluxes, primary productivity and fisheries. However, in what terms these processes might be affected still remains uncertain. This investigation particularly addresses variations of the vertical stratification maximum which is found at the depth of the thermocline/pycnocline. The analysis separates between summer and winter stratification. Trends of the vertical stratification maximum are computed for both seasons, respectively. Our intention is to show regional differences in the trends as well as to identify whether the corresponding seasonal cycle is changing. The aim of this study is further to produce a world-wide product of the stratification maximum based on Argo observations from 2006-2021. The goal is to create an algorithm that takes the uneven vertical resolution of Argo profiles into account. In order to verify our product, we compare the results of the Argo data to other CTD measurements as obtained from research vessels and buoys. With this we receive a quality-controlled global product which allows us to make a statement about the global variability of the stratification in the thermocline. Understanding the changes of the vertical stratification maximum will help to identify their impact on ocean ventilation and nutrient supply to the euphotic zone.
Faster model calibration using the Fourier transform
Authors: Anwar Faizan , Bárdossy András
Published: March 2022

We propose a new methodology for faster calibration of multiparameter models using the Fourier transform. The HBV (rainfall-runoff) model is used to demonstrate the concept. It requires precipitation, temperature and potential-evapotranspiration as input time series with a total of 10 calibration parameters. By changing each parameter, the resulting runoff series is affected in a unique way. We observed that these changes are independent of others in the frequency domain. Parameters that show combined effects with others may be calibrated together. Indirectly, we can also find out model parameters that produce unique effects and the ones that are dependent on each other. The advantage is that it is easier to do multiple one-dimensional calibrations as compared to a single high-dimensional one.
Hourly air temperature mapping in Guangdong province utilizing machine learning
Authors: Chen Guangzhao , Shi Yuan , Ren Chao , Ng Edward
Published: March 2022

Air temperature is a crucial variable in urban climate and relevant to many studies, such as urban heat islands, heat waves, climate change, energy consumption, and health-related heat exposure risk studies. Previous studies used land surface temperature (LST) and inversion methods to obtain air temperature maps with spatial detail or used weather station observations and spatial interpolation to obtain air temperature maps with high temporal resolution. However, fine spatial detail and high temporal resolution have not been resolved simultaneously. Moreover, there are differences in LST and air temperature definitions, which cannot be equated. Therefore, in this study, we carried out hourly air temperature mapping at 1-km resolution over a multi-year summer period for Guangdong Province, China, employing machine learning algorithms as well as meteorological and landscape data. The meteorological data were hourly observations from 86 weather stations in Guangdong containing variables such as air temperature, relative humidity, precipitation, barometric pressure, and wind speed. The landscape data were mainly from the landscape indices calculated based on local climate zone (LCZ) maps, mapped via Google Earth Pro and Google Earth Engine. Then, we employed the random forest (RF) algorithm for the hourly air temperature mapping. The validation results showed that the hourly air temperature maps achieved good accuracy from 2008 to 2019 with a mean R2 value of 0.8001. The importance assessment of the driving factors showed that meteorological factors, especially relative humidity, make the most outstanding contribution to air temperature mapping. Simultaneously, the landscape factors also played a non-negligible role. Further analysis revealed that the maps steadily maintained high accuracy at nighttime (20:00-7:00), which is the most critical period for studying urban heat islands. In addition, the air temperature patterns showed a correlation with the landscape. Air temperatures in contiguous mountainous areas with dense trees were significantly lower than those in the plains. Moreover, there is a correlation between nighttime air temperature changes and urban morphology, and urban-rural differences exist simultaneously. Air temperatures tend to fall more slowly in the core of metropolitan areas than in the urban fringe. Overall, this study employed machine learning to reliably improve the temporal resolution of air temperature mapping with more spatial detail. Furthermore, it reveals spatially explicit air temperature patterns in and around cities at different times in a day during the summer. In addition, it provides a new valuable and advantageous dataset for relevant applications.
The use of satellite data to support the volcanic monitoring during the last Vulcano island crisis
Authors: Silvestri Malvina , Rabuffi Federico , Romaniello Vito , Musacchio Massimo , Buongiorno Maria Fabrizia
Published: March 2022

The “La Fossa” summit crater of Vulcano island (Sicily, Italy) showed increasing volcanic activities, characterized by strong gases emissions and high soil temperatures, during July 2021 (https://cme.ingv.it/stato-di-attivita-dei-vulcani-eoliani/crisi-idrotermale-vulcano-2021). The National Civil Protection Department declared the “yellow alert” level and the Mayor of the island issued an order to prohibit citizens to stay in areas surrounding the harbor due to large amounts of gases emitted; an alternative accommodation was sought for about 250 persons. In this work, we report and analyze the surface temperature estimated by using satellite data (ASTER and Landsat-8) from 2000 to 2022. These analyses extend the study described in “Silvestri et al., 2018” which reports a time series of thermal anomalies from 2000 to 2018, with a focus on two specific sites of the Vulcano island: “La Fossa” and “Fangaia”. So, we updated the dataset up to 2022 and analyzed space-borne remotely sensed data of the surface temperature on the whole island. We applied the Pixel Purity Index technique to ASTER and Landsat-8 satellite data (GSD=90 m) in order to detect pixels that are most relevant from the thermal point of view; thus, we used these pixels as significant points for the time series analysis. Moreover, strong carbon dioxide emissions could be detected from satellite data acquired by the new Italian space mission PRISMA (GSD=30 m) carrying onboard a hyperspectral sensor operating in the range 0.4-2.5 µm; this possibility will be explored by analyzing data on active fumaroles in the island. The goal of the analysis is also to verify if volcanic activity variations (in terms of thermal anomalies and gases emissions), in the Vulcano island, can be detected by satellite data.
Forest soils under threat too.
Authors: Vieira Diana
Published: March 2022

Forest soils are undeniably recognized to help deliver essential ecosystem services. Nevertheless this provision is facing serious threats at a moment we need forests the most. The increasing frequency of fire-prone weather conditions in the EU such as the ones causing exceptional wildfire scars in 2017 (San-Miguel-Ayanz et al., 2018), combined with extreme climate demands (IPCC, 2021) and an escalation of forest mechanisation driven by a systematic increase in the use of forest products (EUROSTAT, 2021), have been putting  EU forest soils to a new level of pressure. As a result, key ecosystem services such as clean water provision and flood control, habitats for life and biodiversity,  biomass provision and carbon sinks, are at stake.

On the other hand, several positive policy initiatives have been initiated under the umbrella of the European Green deal, such as the EU Forest and Biodiversity strategies for 2030. These aim for more healthy, diverse and resilient EU forests, ensuring we can count on their contribution for the most recent climate and biodiversity ambitions. Such initiatives combined with the new EU Soil Strategy should underpin a new era of ecosystems resilience and halt the latest land degradation trends. But the question remains: what is the current state of the EU forest soils after so many years of coexistence with the Europeans?

This presentations aims to provide an overall perspective on current threats affecting forest soils. Issues such as recurrent wildfires, inappropriate land management, land use and land cover changes are all sides of the same coin. Not surprisingly these will lead to land degradation, triggered most frequently by soil erosion. In addition, this paper will identify several misconceptions driven by remote sensing based assessments, such as the identification of good soil conditions under vigorous leaf area indexes, or the consideration of good soil management practices in all forest terraces.

With this argumentation the author hopes to trigger a healthy discussion on the idea that our EU forest soils are not in their best shape, and they too need to be cared for and managed. 
Application examples of underground muography
Authors: Surányi Gergely , Hamar Gergő , Nyitrai Gábor , Gera Ádám
Published: March 2022

Muography (or muon tomography) is one of the most effective methods for locating unknown density inhomogeneities, (eg. ore bodies or voids) underground. The geometric conditions have limitations, but otherwise there is no any other competing geophysical method, either the resolution or the simplicity is considered.

In the last years thanks to the continuous R&D in Wigner Research Centre for Physics, Budapest, we have been provided low-cost, portable muon detectors as well as newly-developed data processing methods. We have several ongoing natural and artificial cavity exploration projects and density inhomogeneity location projects for mining applications.

Here we present case studies carried on in Hungarian underground sites, where we could find unknown cavities and verify the method by locating known artificial shafts and adits with high precision. We have achieved that if the characteristic size of the void is only 2-3% of the rock thickness between the detector and the surface, the cavity location is feasible. To reach these unknown voids and density anomalies is in progress either by conventional caving exploration techniques or by drilling.

Further measurements are ongoing by the new upgraded detectors. By decreasing the gas consumption and supporting the electric power by solar cells, we are able to measure even at remote locations without the need of any direct access for several months duration.
Towards waveform seismic filtering of mantle convection models
Authors: Fuji Nobuaki , Dhabaria Nirmit , Roncoroni Giacomo , Myhill Robert , Durand Stéphanie , Borgeaud Anselme , Tackley Paul , Nakagawa Takashi , Deschamps Frédéric
Published: March 2022

Earth science has been heavily data-driven due to the abundance in data. Yet, when there are relatively a small number of hypotheses to verify, the inverse problem becomes a classification problem. It is then worth directly examining observed seismic data against predicted data. Concretely, we chain forward modelling from geodynamics  to seismology. We call this process ‘waveform Seismic Low Filtering of Earth’s models’ (SeLFiE). We take seismic signals of the snapshots of forwardly generated Earth models with that of the actual Earth, as if we took a photo of ourselves. Although there have several studies on how the seismological tomographic technique can perceive the geodynamical models, there are few studies on the seismic waveform sensitivity to geodynamical or petrological parameters. A pilot test of our SeLFiE methodology was encouraging, since we used only one seismic station to constrain the melt transportation manner beneath the Réunion island (Franken et al. 2020). Here in this contribution we present our strategy and developed tools towards the waveform filtering that have been developed during and after the CLEEDI week in August, 2020.
Animals as soil and landscape engineers
Authors: Kristensen Jeppe Aagaard
Published: March 2022

The ‘o’ for organisms in Jenny’s famous formula for soil formation (s), s=f(cl,o,r,p,t,…) [Jenny, 1941], should have put organisms up there with climate, relief/topography, parent material and time as a fundamental soil formation factor. The contribution to weathering by organic acids has secured indirect recognition of the role of organisms in soil formation. Yet, this recognition has mainly been given to plants, while the direct mechanical displacement of soil particles by animals has merely remained a curiosity in the quantitative sciences.

In this talk, I will share my view on the role animal ecosystem engineers have played, play and could possibly again play in shaping our soils and landscapes, and the implications for ecosystem processes. This is particularly important in a time where reintroduction of key mammal species are increasingly viewed as an effective strategy for restoring nature, not least due to their role as ecosystem engineers. Therefore, I will particularly focus on animals with large body sizes (>45 kg), and how they affect soil formation and erosion through own behaviour (e.g. wild boar grubbing, elephants and donkeys digging for water in arid environments, trampling), but more importantly through their association with more effective vertebrate (e.g. moles, gophers, pikas, prairie dogs) and invertebrate soil engineers (e.g. earthworms, termites, ants and dung beetles).

I will conclude by outlining the next steps I think we as a community should take to get quantitative estimates of bioturbation and effects on erosion at relevant spatial and temporal scales. This includes i) further development of methods for point estimation of long-term rates, e.g. with sediment luminescence data, ii) upscaling with remote sensing, and iii) earth system model development with specific representation of bioturbation and erosion.   

Literature cited: Jenny, H., Factors of Soil Formation: A System of Quantitative Pedology, New York: McGraw-Hill, 1941.
Releasing the banks: initial morphological responses after removal of groynes and installation of a longitudinal dam
Authors: Carranza Coleen , Onderwater Nard , Larsen Annegret , Candel Jasper , Bense Victor , Hoitink Ton , Wallinga Jakob , van der Ploeg Martine
Published: March 2022

Longitudinal dams (LD) are novel engineering structures built parallel to the river channel that support sustainable river management. The recent replacement of groynes by longitudinal dams in low-land rivers such as the Waal has been successful in restoring the ecological river functions while simultaneously achieving its navigation, recreation, and flood-protection functions. However, the impact of the LD on the riverbanks is still unknown despite recent investigations on the flow dynamics in the side channel behind it. We fill this knowledge gap by investigating initial bank responses and quantifying changes in sediment dynamics over five years since the completion of the LD in the Waal at Wamel. We rely on available annual high-resolution LiDAR-derived DTMs, orthophotos, and in situ measurements to estimate erosion and deposition rates and their changes over the study period. A two-stage initial response is revealed with the largest bank erosion (~140 x 103 m3/yr) and deposition (~20 x 103 m3/yr) confined in the first year after installation, as the banks adjust to a new hydrogeomorphic equilibrium. This is followed by successively lower rates of surface-level changes (<70 x $103 m3/yr eroded and <10 x 103 m3/yr deposited) as a response to the hydrogeomorphic dynamics in the new system. The overbank deposits from recent floods have a similar distribution with those prior to LD construction based on the DTMs. However, higher volumes of sandy deposits are found post- compared to pre-LD construction for floods of similar magnitude and duration. This increase is caused by the additional contribution of the bank sediments that have been made available through the removal of groynes. Although eroding banks may be a threat to infrastructure and navigability, they have a positive effect on restoring ecological diversity and floodplain connectivity.
Performance of the AOTF-based NO2 camera for urban pollution imaging
Authors: Dekemper Emmanuel , Vanhamel Jurgen , Van Roozendael Michel
Published: March 2022

An instrument capable of imaging the field of NO2 in various open-air situations has been designed, manufactured, and tested. It is an improved version of the NO2 camera relying on an AOTF (acousto-optical tunable filter) which has demonstrated, amongst other things, its capability to quantify the NO2 released by power plant smokestacks. The improved version which is presented has a larger field of view, a higher frame rate, and better spectral registration performance.

The working principle of the instrument has been preserved: by driving the AOTF with the appropriate acoustic frequency, a spectral image of the scene captured by the camera is recorded at a particular wavelength. The recording of a number of spectral images allows to form an hypercube: two spatial dimensions, and a spectral one.

While the earlier instrument was relying on a handful of wavelengths to quantify the slant column density of NO2 observed in each pixel line of sight, the new instrument can now record "continuous" portions of the visible-light spectrum, typically between 440, and 460nm, where the NO2 exhibits some of its largest absorption lines.

When the target is stable, like the air observed above a city skyline, the NO2 camera has enough time to build a large hypercube, and the spectrum measured in each pixel can be processed by the DOAS (differential optical absorption spectroscopy) method. This approach is better suited when NO2 is expected across the entire scene, not just in the plume of a smokestack for instance.

The new instrument will be presented, and results of measurements performed in an urban context will be shown. The performance of the NO2 camera will be discussed based on the results of an intercomparison with the MAX-DOAS of Uccle, Brussels, and other air quality stations.
Substorm onset and current sheet flapping in a 6D global ion-kinetic simulation
Authors: Palmroth Minna , Ganse Urs , Pfau-Kempf Yann , Alho Markku , Suni Jonas , Grandin Maxime , Turc Lucile , Battarbee Markus , Johlander Andreas , Tarvus Vertti , Zhou Hongyang , Bussov Maarja , Dubart Maxime , George Harriet , Horaites Konstantinos , Manglayev Talgat , Papadakis Konstantinos , Nakamura Rumi , Pulkkinen Tuija
Published: March 2022

Among the most unpredictable phenomena within the near-Earth space are substorms, periods of energy loading and explosive release within the magnetospheric tail. Substorms are global, as energy is extracted from the solar wind via dayside reconnection, while the tail energy release takes place in a vast domain within a few tens of seconds. Due to the scarcity of space-borne observations, it has been difficult to conclusively separate between the onset scenarios that include magnetic reconnection and various ion-kinetic instabilities, which occur at mesoscales, and small scales. Another decades-long investigation concerns the flapping of the plasma sheet, occurring within a large area favouring the substorm growth phase, although it has been observed at other times as well. Mechanisms to explain the flapping are presently unknown. Modelling efforts have failed to explain the substorm onset either because all the required physics has not been included in the simulation, or the simulation does not cover the entire domain, thus possibly missing important drivers. Vlasiator is a  model describing the global magnetosphere accurately at ion-kinetic scales, including the ion-kinetic effects that are absent in the fluid descriptions. Unlike many other kinetic simulations, Vlasiator extends the simulation domain to global scales and accurately represents the Earth’s unscaled magnetosphere from the dayside to the tail, in six dimensions including the 3D real space and 3D velocity space without noise that is present in the alternative PIC method. We present the first global 6D simulation encompassing the entire near-Earth space to simulate ion-kinetic magnetospheric dynamics self-consistently. We determine reconnection, ion-kinetic instabilities, plasma sheet flapping, and bursty bulk flows in the simulation domain, and show how they all contribute to the whole and work in concert in developing the substorm onset. Our results help to understand spacecraft measurements and the overall substorm process, which will significantly improve understanding space physics and eventually space weather. Our results can also be used in strategies to design a mission, which will finally and conclusively capture the substorm onset with in situ measurements.
Evaluation of no-tillage as an alternative management for the improvement of the physical condition of agricultural soils through the analysis of water retention curves.
Authors: Aldaz Alaitz , Giménez Rafael , Virto Iñigo , Campo Miguel Ángel , Arregui Luis Miguel
Published: March 2022

Physical degradation of agricultural soils manifests itself in different ways: decrease in infiltration rate and water storage, poor aeration and, compaction. All these symptoms have a common cause: the deterioration of the soil's natural structure due to the usual agricultural management practices.

Soil water retention curves are a valuable tool for diagnosing the physical state of the soil. Soil properties are the ones that regulate the shape of this curve, with special relevance to texture and structure. For example, changes in macroporosity –associated to soil aggregates and therefore to its structure– would be reflected in changes in the shape of this function in the low suction range.

This work evaluates no-tillage as an alternative to conventional tillage in a typical soil of Navarre (Spain), based on the analysis of soil water retention curves (SWRC).

Two plots were selected, identical in soil type and use, but contrasting in their management: (i) no-tillage (18 continuous years) after conventional tillage and (ii) conventional tillage. In both treatments, undisturbed soil samples were taken (0-5 cm). From these, SWRCs were obtained in the laboratory using the Hyprop device. Dexter’s S index was determined for each SWRC.

The S index did not show significant differences between the two treatments. However, the SWRCs present significant differences between treatments regarding pore size distribution. The tilled soil showed higher macroporosity (gravitational water). Therefore, the soil (surface horizon) under no-tillage could store ca. 10 % more water for the crop.
A hierarchical Constrained Bayesian (ConBay) approach to jointly estimate water storage and post glacier rebound from GRACE(-FO) and GNSS data
Authors: Mehrnegar Nooshin , Forootan Ehsan
Published: March 2022

Gravity Recovery and Climate Experiment (GRACE) and its Follow-On mission (GRACE-FO) provide time-variable Earth's gravity fields that contain signals related to different processes such as non-steric sea level changes, Terrestrial (surface and sub-surface) Water Storage Changes (TWSC), ice sheet melting, and Post Glacial Rebound (PGR). Although the GRACE(-FO) data represent an accurate superposition of these anomalies, separating them into individual storage and surface deformation contributors is desirable for many geodynamic and hydro-climatic applications. Particularly, for hydrological applications, the PGR is often removed as a linear trend, during the post-processing, using the output of Glacial Isostatic Adjustment (GIA) models. As a result, estimating trends in TWSC depends on the accuracy of GIA models, which has considerable uncertainties. In this study, a hierarchical constrained Bayesian (ConBay) approach is formulated to apply GRACE(-FO) fields and the uplift rate measurements from the Global Navigation Satellite System (GNSS) stations to simultaneously estimate the contribution of TWSC and PGR. The proposed approach is formulated based on a hierarchical Markov Chain Monte Carlo optimization algorithm to update available information within a dynamic multivariate state-space model, while accounting for the uncertainties of models and observations. To evaluate the proposed approach, its numerical implementation is demonstrated over the Great Lakes area in North America on grids with 0.5-degree spatial resolution, covering 2003-2017, where the W3RA water balance model and the ICE-5G(VM2) GIA model are used as a priori information of individual water storage changes and PGR rates. Validations are done against independent measurements, i.e., in-situ USGS groundwater level observations, as well as independent GNSS measurements (not used in the optimization procedure). The results indicate that the bias between GIA model output and the in-situ GNSS observation reduced by 72% (from 7.8 to 2.2 mm/yr) and the root-mean-square-of-differences between USGS measurements and model-derived groundwater changes is reduced by 36%, after merging observations with models through ConBay. The ConBay updates, introduced to the long-term trends, as well as the seasonal and inter-annual components, are found to be realistic.

 

keywords: Bayesian Signal Separation; GRACE(-FO); GNSS; Terrestrial Water Storage Changes; Post Glacial Rebound; 
Plastic accumulation on riverbanks after the July 2021 Meuse flood
Authors: Hauk Rahel , van Emmerik Tim , Boonstra Marijke , de Winter Winnie , van der Ploeg Martine
Published: March 2022

The majority of mismanaged plastic waste does not reach the oceans, and rather accumulates in terrestrial and freshwater environments. Since 2017, riverbanks along the Dutch part of the river Meuse have been monitored by volunteers in spring and fall. At each monitored riverbank macroplastic and other litter items were collected along a 100 m section and classified in over 100 specific item categories. In July 2021, the Meuse was hit by a severe flood event with an estimated return period between 100 - > 1000 years, similar to other rivers in Germany, France, Belgium, and the Netherlands. Flood conditions can highly increase plastic (re)mobilization and transport within river systems, and plastic discharge into the oceans. However, the impact of a severe flood event on plastic litter accumulation on riverbanks, to the authors knowledge, was never measured before. Within three weeks after the flood event we counted and classified macroplastic and other litter items on 25 riverbanks along the Meuse, from the Dutch-Belgian border to the river mouth. The additional sampling allows us to, for the first time, assess the impact of such a flood event on plastic accumulation on riverbanks. In this presentation we compare plastic accumulation on riverbanks after this flood event to plastic accumulation during normal conditions. We compare the amounts and types of litter, and possible litter sources. This study aims to contribute to better understand mobilization, transport, and accumulation dynamics of plastics in river systems, and the role and impact of extreme events on plastic accumulation on riverbanks.
Monitoring gas dynamics in underwater volcanic environments using iXblue SeapiX multi split beam echosounder: an example from the Laacher See (Eifel, Germany)
Authors: Jouve Guillaume , Caudron Corentin , Matte Guillaume , Mosca Frédéric
Published: March 2022

Forecasting volcanic and limnic eruption for improving early warning systems is crucial to prevent severe impact on human lives. One of the main triggers of explosive eruptions is volcanic gases which, contrary to the atmosphere, are easily detected in water column, particularly using hydro-acoustic methods [1]. Two pioneering studies have monitored gas venting into Kelud Crater Lake (Indonesia) from a hydroacoustic station shortly before a Plinian eruption in 1990 [1] and, nearly two decades later, by empirically quantifying CO2 fluxes by acoustic measurements in the same lake just before a non-explosive eruption [2]. However, despite hydroacoustic detection capabilities, fundamental advances are limited by technology performances. Overall acoustic detection of a bubble field is easy, while its quantification remains complex due to the 3D structure of clouds, heterogeneous bubbles sizes and acoustic interactions between them. It is thus necessary to accurately map the different bubble clouds, to monitor their evolution through time to reduce the volcanic risk, which is major in aqueous environments. Here, we present preliminary results of water column gas distributions and quantification from an Eifel crater lake (Germany), using iXblue Seapix 3D multi splitbeam echosounder. SeapiX acoustic array is based on very special geometry, a dual/steerable multibeam echosounder with a Mills Cross configuration. It allows a 120° x120° coverage (quasi realtime coverage) with 1.6° resolution, made by 128 single elements. All beams in all steering direction process Split Beam TS measurement to provide true acccurate volumic TS from all single target in the volume. Backscatter profiles of elements in the water column allowed to distinguish fish and gas bubbles, which demonstrates a potential for the development of an automatic gas detection module using the Seapix software. Ongoing research on the Target Strengh (TS) of bubbles suggest they are of very small size (35 μm), much smaller than observed elsewhere using single beam echosounders, which might also explain why, in the same spot, we did not observe gas bubbles using camera mounted on ROV. Using the steerable capability of the system, a recent mission performed a 4D monitoring of gas bubbling of a single gas plume, in a static position placed on a USV and anchored, raising new perspectives to anticipate the tipping point of a critical enhancement of gas release and to mitigate the volcanic risk.

[1] Vandemeulebrouck et al (2000) J. Volcanol. Geotherm. Res 97, 1-4: 443-456

[2] Caudron et al (2012) JGR: Solid Earth 117, B5

 
WCB characteristics and impacts and how they are interrelated in ERA5
Authors: Heitmann Katharina , Binder Hanin , Sprenger Michael , Wernli Heini , Joos Hanna
Published: March 2022

The warm conveyor belt (WCB) transports moist air from low levels in the warm sector of an extra-tropical cyclone (ETC) as a coherently ascending airstream to the upper troposphere. WCBs are associated with an elongated cloud band and precipitation and were found to be responsible for 40-60% of the total precipitation in the midlatitude. Furthermore, the release of latent heat during cloud formation has the potential to modify potential vorticity (PV) below and above the level of maximum heating. Due to the modification of PV, WCBs can affect the synoptic-scale flow, e.g., by disturbing the jet stream on triggering Rossby waves in the upper troposphere, as well as the intensification of ETCs.

While the occurrence of WCBs has been studied from a climatological viewpoint before, the spatial distribution and temporal evolution of WCB characteristics and impacts, as well as the link between them, remain largely unknown. Therefore, we developed a novel method to quantify a set of WCB metrics that describe its characteristics (intensity, ascent rate, curvature, moisture content, position, and age relative to the cyclone evolution) and impacts (PV modification at low and upper levels, precipitation rate and volume). In addition, we considered the metric evolution along the whole lifecycle of the WCB. Applying this method in a case study, the WCB reached maximum intensity and ascent rate during the cyclone’s strongest intensification. In terms of impacts, maximum precipitation rates decreased over the lifetime of the WCB, while maximum PV values at lower levels increased. We then extended the analysis to the 40-year time span 1980 - 2020 covered by ECMWF’s most recent reanalysis ERA5, by calculating WCB trajectories globally for the entire period. Thereby, we were able to identify from a climatological viewpoint for the first time: (i) the global spatial distribution of WCB characteristics and impacts; (ii) the link between them; and (iii) their distinct lifecycle. This analysis showed that the characteristics and impacts of WCBs differ between different regions and seasons while the link between them remains largely constant. For instance, in the North Atlantic, we found two regions of enhanced WCB intensity which are also linked with enhanced precipitation volume. While the precipitation volume correlates strongly with the WCB intensity, the highest precipitation rates are associated with the most rapidly ascending WCBs. On a global scale, WCB-related low-level PV depends mainly on latitude, however, if restricted to a latitudinal band, inflow moisture becomes important.