bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the effects of leaking gas in geological carbon sequestration through geophysical characterization of natural CO2 gas emission systems
Authors: Salone Rosanna , De Paola Claudio , Ferranti Luigi , Di Maio Rosa
Published: March 2022

Gas leakage from deep geologic storage formations to the Earth’s surface is one of the main hazards in geological carbon sequestration and storage. Permeable sediment covers or natural and artificial pathways, such as faults and well structures, are the main factors controlling surface leakages. Therefore, the characterization of natural systems, where large amounts of CO2 are released, can be helpful for understanding the effects of potential gas leaks from storage carbon systems. In this framework, we propose a combined use of geoelectrical investigations (i.e., resistivity tomography and self-potential surveys) for characterizing natural CO2 leakage areas, as well as gas storage sites. Such methodologies appear to be among the most suitable for revealing spatial distributions of carbon dioxide and monitoring subsurface fluid migration processes, because of the strong dependence of the electrical properties of water-bearing permeable rock, or unconsolidated materials, on many factors relevant to CO2 storage (i.e., porosity, fracturing, water saturation, etc.). Indeed, the electric resistivity of porous water-bearing sediments decreases significantly when CO2 dissolves in pore-water, in contrast to the effect in the gas phase and supercritical CO2, while the anomalous concentrations of natural electric charge are directly related to carbon dioxide migration along porous and fractured rock systems. The effectiveness of the suggested multi-methodological geoelectrical approach is tested in some areas of natural CO2 degassing located in the Southern Apennines (Italy), which could represent natural analogues of gas storage sites. Specifically, electrical resistivity and self-potential surveys are targeted at reconstructing shallow buried fracture networks in the cap-rock and detecting preferential CO2 migration pathways. Our findings are promising for imaging the CO2 plume within a carbon storage reservoir and for identifying possible CO2 leakages through the cap-rock formation, suggesting that the proposed approach can be very helpful also for the monitoring of carbon sequestration systems.  
All interglacials are different, but some are more different than others
Authors: Tzedakis Chronis , Hodell David , Nehrbass-Ahles Christoph , Wolff Eric
Published: March 2022

Examination of the palaeoclimate record of the last 800 kyr has revealed a large diversity among interglacials in terms of their duration, structure and intensity.  Interglacials may be classified as either short (mean duration 13 kyr) or long (mean duration 28 kyr).  The phasing of precession and obliquity appears to influence the persistence of interglacial conditions over one or two insolation peaks: the longest interglacials are characterized by the obliquity peak lagging the first precession minimum by 10±2 kyr and leading the second precession minimum by a similar amount; thus the first boreal summer insolation minimum occurs at the time of maximum obliquity, which overrides the increase in precession and prevents glacial inception associated with a decline in summer insolation.  The phasing of precession and obliquity also determines the structure of an interglacial, leading to two main categories: (1) shorter interglacials characterized by rapid deglaciation and an early temperature optimum, usually followed by a decline; and (2) longer interglacials characterized by protracted deglaciation and the persistence of interglacial values over two insolation peaks, with the interglacial peak occurring in the second insolation maximum.  With respect to intensity, a broad feature is that interglacials before the Mid-Brunhes Event (MBE; 430 ka) appear weaker (cooler, higher δ18Obenthic, atmospheric CO2 lower than pre-industrial concentrations).  The strongest interglacials occurred after the MBE, although MIS7e and MIS7c-a are closer in intensity to pre-MBE interglacials.  Of particular interest is MIS 11c, one of the most unusual Quaternary interglacials.  Its features include: (i) a high sea-level highstand attained under modest insolation forcing; (ii) a long duration extending over two insolation peaks; (iii) persistence of relatively stable atmospheric CO2 concentrations, remaining in the range 270-282 ppm for a 24 kyr period; and (iv) a decoupling between high CO2 and high sea level in the early part of the interglacial that is unique in the last 800 kyr.  Although some of these features are also encountered in other interglacials, their combination with strong interglacial intensity is unique to MIS 11c and appears to be a function of the high CO2concentrations from the beginning of the interglacial.
The CAIRT Earth Explorer 11 mission: A way towards global GW momentum budgets
Authors: Preusse Peter , Osprey Scott , Polichtchouk Inna , Ungermann Joern , Chipperfield Martyn , Errera Quentin , Friedl-Vallon Felix , Funke Bernd , Godin-Beekmann Sophie , Hoffmann Alex , Malavart Alizee , Raspollini Piera , Sinnhuber Bjoern-Martin , Verronen Pekka , Walker Kaley
Published: March 2022

Retrieving global observations of gravity waves (GWs) from recent satellite missions is challenging. Nadir viewing satellites such as AIRS provide directional momentum fluxes, but lack fine vertical resolution and hence observe only those GWs with exceptionally high intrinsic phase speed. Limb scanning instruments such as HIRDLS and SABER have only a single measurement track and hence provide only an estimate of absolute GW momentum flux. In addition, the sparse along-track sampling of these limb sounders introduce uncertainties in horizontal wavelength. GPS-RO can provide  GW profile triplets, allowing in principle the horizontal direction of GW propagation to be inferred, but these triplets are rare. Finally, direct wind measurements from Aeolus are restricted in altitude to less than ~25km and only provide the wind component in the direction of the lidar beam from one observational track. In consequence, also Aeolus cannot reveal horizontal propagation direction and GW momentum flux.

This situation could be dramatically improved by bringing a limb imager into space. A limb imager combines the very dense spatial sampling of a nadir viewing instrument with the high vertical resolution of a limb sounder. This will provide an almost complete description of the vertical spectrum of GWs, necessary for inferring drag estimates. Such global GW momentum flux data would for the first time allow to retrieve a global momentum budget from the mid-troposphere to the upper mesosphere.

The Changing-Atmosphere Infra-Red Tomography (CAIRT) mission candidate for ESA's Earth Explorer 11 proposes a limb imager for spatial sampling of 25 km across-track, 50 km along-track and 1 km in the vertical. From this we expect to infer directional GW momentum fluxes from the tropopause to 70 km or higher. This will allow longstanding scientific questions to be addressed such as the quantification of tropospheric GW sources and their related phase speed spectra and the identification of secondary wave generation in the stratosphere and lower mesosphere. Considering the momentum flux at higher altitudes, secondary wave generation competes with oblique GW propagation which allows GWs from low latitude sources to reach the high latitudes mesosphere and thus avoid critical levels. In general, two-way interaction with the background flow will be considered via the modulation of the GW spectrum by the winds and the mean wind accelerations by the GWs. In this contribution we will outline the CAIRT instrument concept, giving an overview of the mission’s objectives and demonstrate its potential using simulated observations.
Regional modeling of water storage variations in a Kalman filter framework
Authors: Wöhnke Viviana , Eicker Annette , Jensen Laura , Weigelt Matthias
Published: March 2022

Water mass changes at and below the surface of the Earth cause changes in the Earth’s gravity field which can be observed by at least three geodetic observation techniques: ground-based point measurements using terrestrial gravimeters, space-borne gravimetric satellite missions (GRACE and GRACE-FO) and geometrical deformations of the Earth’s crust observed by GNSS. Combining these techniques promises the opportunity to compute the most accurate (regional) water mass change time series with the highest possible spatial and temporal resolution, which is the goal of a joint project with the interdisciplinary DFG Collaborative Research Centre (SFB 1464) "TerraQ – Relativistic and Quantum-based Geodesy".

A method well suited for data combination of time-variable quantities is the Kalman filter algorithm, which sequentially updates water storage changes by combining a prediction step with observations from the next time step. As opposed to the standard way of describing gravity field variations by global spherical harmonics, we will introduce space-localizing radial basis functions as a more suitable parameterization of high-resolution regional water storage change. A closed-loop simulation environment has been set up to allow the testing of the setup and the tuning of the algorithm. In a first step only simulated GRACE data together with realistic correlated observation errors will be used in the Kalman filter to sequentially update the parameters of a regional gravity field model. However, the implementation was designed to flexibly include further observation techniques (GNSS, terrestrial gravimetry) at a later stage. This presentation will outline the Kalman filter framework, introduce the regional parameterization approach, and address challenges related to, e.g., ill-conditioned matrices and the proper choice of the radial basis function parameterization.
Hydrogen recovery from porous media decreases with brine injection pressure and increases with brine flow rate    
Authors: Thaysen Eike Marie , Butler Ian B. , Freitas Damien , Hassanpouryouzband Aliakbar , Alvarez-Borges Fernando , Atwood Robert , Humphreys Bob , Edlmann Katriona
Published: March 2022

Zero carbon energy generation from renewable sources can reduce climate change by mitigating carbon emissions. A major challenge of renewable energy generation is the imbalance between supply and demand. To overcome the energy imbalances, subsurface storage of hydrogen in porous mediais suggested as a large-scale and economic solution, yet its mechanisms are not fully understood. Important unknowns are the effect of the high migration potential of the small and mobile hydrogen molecule and the volume of recoverable hydrogen.

We conducted non-steady state, cyclic hydrogen and brine injection experiments at 2-7 MPa and flow rates of 2-80 µl min-1 using water-wet Clashach sandstone cylinders of 4.7 mm diameter and 53-57 mm length (Clashach composition: ~96 wt.% quartz, 2% K-feldspar, 1% calcite, 1% ankerite). Two sets of experiments were performed using our new transparent flow-cell designed for x-ray computed microtomography: 1) Experiments using a laboratory x-ray source (University of Edinburgh) imaged the flow, displacement and capillary trapping of hydrogen  by brine as a function of saturation after primary drainage and secondary imbibition. 2) Experiments using synchrotron radiation (Diamond Light Source, I12-JEEP tomography beamline) captured time-resolved hydrogen and brine flow and displacement processes. Pressure and mass flow measurements across the experimental apparatus complemented the microtomography volumes in both sets of experiments.

Results from a water-wet rock show that hydrogen behaves as a non-wetting phase and sits in the centre of the pore bodies, while residual brine sits in corners and pore throats. Hydrogen saturation in the pore volume is independent of the injection pressure and increases with increasing hydrogen/brine injection ratio up to ~50% saturation at 100 % hydrogen. Capillary trapping of hydrogen during brine imbibition occurs via snap off and is greatest at higher brine injection pressures, with 10 %, 12% and 21% hydrogen trapped at 2, 5 and 7 MPa, respectively. Higher brine flow rates reduce capillary trapping and increase hydrogen recovery at any given injection pressure. Based on these results, future hydrogen storage operations should inject 100% hydrogen and manage the reservoir pressure to avoid high pressures and minimize capillary trapping of hydrogen during brine reinjection.

Ongoing analysis of time-resolved experimental data will provide further insight into the critical pore-scale processes that ultimately influence the potential for geological hydrogen storage and recovery.
Subglacial topography and landscape evolution from radio-echo sounding data in the Evans-Rutford Region, southern Antarctic Peninsula.
Authors: Carter Charlotte , Bentley Michael , Jamieson Stewart , Ross Neil , Jordan Tom , Bodart Julien
Published: March 2022

Understanding the subglacial bed topography of the Antarctic ice sheet is important for the boundary conditions of ice sheet modelling and the assessment of basal hydrological conditions. Moreover, inferring landscape evolution from the geomorphology can also provide insight into ice sheet inception and history. We utilise radio-echo sounding data from the BAS GRADES-IMAGE and TORUS radar surveys to geomorphologically interpret the bed topography in the Evans-Rutford Region of Antarctica, between the Ellsworth mountains and the southern Antarctic Peninsula. The GRADES-IMAGE survey is a legacy radar survey that has not yet been examined in detail in terms of subglacial bed topography and consists of 11,500 line kilometres of data along 22 lines. We have updated the subglacial bed picks to develop a new Digital Elevation Model of the region. Here we report preliminary results of the mapped subglacial landscape, with potential interpretations of the topographic patterns and landscape evolution. Geomorphological observations of the key features include identification of flat plateau surfaces at similar elevations, sitting between deep incised glacial troughs, some of which have potential tectonic controls.
Characterization and warnings for mountain waves using HARMONIE-AROME
Authors: Díaz Fernández Javier , Bolgiani Pedro , Santos Muñoz Daniel , Sastre Mariano , Valero Francisco , Farrán Jose Ignacio , González Alemán Juan Jesús , Martín Pérez María Luisa
Published: March 2022

Mountain lee waves are a kind of gravity waves often associated with adverse weather phenomena, such as turbulence that can affect the aviation safety. Not surprisingly, turbulence events have been related with numerous aircraft accidents reports. In this work, several mountain lee wave events in the vicinity of the Adolfo Suarez Madrid-Barajas airport (Spain) are simulated and analyzed using HARMONIE-AROME, the high-resolution numerical model linked to the international research program ACCORD-HIRLAM. Brightness temperature from the Meteosat Second Generation (MSG-SEVIRI) has been selected as observational variable to validate the HARMONIE-AROME simulations of cloudiness associated with mountain lee wave events. Subsequently, a characterization of the atmospheric variables related with the mountain lee wave formation (wind direction and speed, static stability and liquid water content) has been carried out in several grid points placed in the windward, leeward and over the summits of the mountain range close to the airport. The characterization results are used to develop a decision tree to provide a warning method to alert both mountain lee wave events and associated lenticular clouds. Both HARMONIE-AROME brightness temperature simulations and the warnings associated with mountain lee wave events were satisfactory validated using satellite observations, obtaining a probability of detection and percent correct above 60% and 70%, respectively.  
Garnet zoning in Variscan pelitic schist from Zicavo, Corsica (France)
Authors: Dulcetta Lorenzo , Cruciani Gabriele , Franceschelli Marcello
Published: March 2022

The Zicavo septum in southern Corsica represents one of the Variscan remnants intruded by late Hercynian granitoids. It is made up of the following lithological units cropping out along a NNE-SSW direction with a general NW-SE striking trend: i) an augen orthogneiss; ii) a leptynite-amphibolite series with metapelites and serpentinite bodies, and iii) a metapelitic sequence (Faure et al., 2014). The sequence is polydeformed by two phases of ductile deformation, D1 and D2, the first characterized by top-to-the-SW and the latter by top-to-the-SE sense of shear. The D1 foliation in the amphibolite and metapelite is deformed by SE-verging folds of the D2 phase. Two garnet-bearing micaschist samples have been selected from the metapelitic sequence for detailed microstructural and mineralogical study. The millimetric garnet porphyroblasts (up to 4-5mm in size; ~12-15 vol%) are associated with plagioclase, quartz, biotite, staurolite, white mica, chlorite and chloritoid and minor ilmenite, zircon, monazite, and apatite. The garnet porphyroblasts are subhedral to euhedral, characterized by a high variety of mineral inclusions (Qz+Cld+Mnz+Ilm+Ms+Zrn+Ap; mineral abbreviations after Whitney and Evans, 2010) decreasing in abundance from core to rim. Garnet cores often preserve a relict foliation identified by the alignment of several microinclusions sometimes arranged into a sigmoidal pattern (snowball garnet). In the rock matrix, the pervasive foliation is identified by the preferred orientation of phyllosilicate minerals and by compositional (quartzo-feldsphatic vs. micaceous) layering. Garnet from Sample ZIC10 (mineral assemblage Grt+Bt+Chl+Ms+Qz+Pl+Ilm) show an increase of iron and magnesium contents from core to rim (29.5 - 34.5 wt.% and 1.5 - 2.5 wt.%, respectively) and a corresponding decrease of manganese and calcium (9 - 4.2 wt.% and 3.1 - 2.1 wt.%). Garnet in sample ZIC11 (coexisting with Chl+Cld+Ms+St+Qz+Pl+Ilm) shows a similar compositional trend (from core to rim, Fe = 26.8-33.5 wt.%; Mg = 1.2-2 wt.%; Mn = 6.5-1.6 wt.%; Ca = 6.8-4.1 wt.%). Preliminary estimation of metamorphic P-T conditions by using isochemical phase diagrams and compositional isopleths of garnet components indicates garnet core formation at ca. 1.6 – 1.7 GPa / 500°C. Garnet compositional zoning suggests an increase in temperature accompanied by a decrease in pressure, compatible with a clockwise P-T trajectory. Comparable P-T conditions and P-T path were observed in HP Variscan pelitic schist from northeastern Sardinia.

Faure M. et al. (2014) International Journal of Earth Sciences 103, 1533–1551.

Whitney D.L. and Evans B.W. (2010) American Mineralogist 95, 185–187.
How to illuminate the twilight world of engineering hydrology
Authors: Faulkner Duncan
Published: March 2022

In the words of David Sellars, engineering hydrologists ply their craft in the twilight, always looking for a shaft of illumination to enhance their understanding. Many decisions on flood risk management around the world are made using techniques that hydrological scientists would barely recognise. The Rational method, first formulated in 1850, is still widely used for design of structures, despite the availability of more scientifically justified alternatives. Software packages used by practitioners offer a variety of modelling techniques, sometimes without any guidance on their validity. It is common to see uncritical application of infiltration equations at a catchment scale with no acknowledgement that they ignore preferential pathway flow. There is a responsibility on both practitioners and software developers to improve scientific understanding.

Meanwhile, research projects and programmes, even with an operational focus, can produce reports, papers and even new techniques that never influence any engineering design, planning decision or operational forecast. In the UK, research into national flood frequency estimation by continuous simulation was completed in 2005 but has seen little implementation. One barrier was the decision to generalise rainfall-runoff model parameters using catchment properties which were not readily available to practitioners. Other UK initiatives have been more successfully adopted by practitioners, including recent development of guidance and tools for non-stationary flood frequency estimation. This produced a software tool that could be applied with a basic knowledge of the R language, along with practitioner-focused guidance, all freely available to download.

As an alternative to regulators trying to impose new approaches, a more promising avenue for implementation of research could be to create an environment in which the practitioner community is encouraged and incentivized to innovate, seeking out shafts of illumination from academia.
Multi-river Calibration Curve for Passive Acoustic Bedload Transport Monitoring.
Authors: Nasr Mohamad , Geay Thomas , Zanker Sébastien , Recking Alain
Published: March 2022

Bedload transport estimation is required for a variety of engineering and ecological applications. Measurement of bedload transport by direct sampling is expensive and time-consuming and rarely captures the spatio-temporal variability of bedload transport. Recent research shows that passive acoustic technology, such as hydrophone, has the potential to monitor bedload transport by recording Self Generated Noise (SGN) resulting from particles collision. In this work, we present a calibration curve relating specific bedload flux to cross-sectional acoustic power for 40 experiments conducted on 13 French rivers. We present the measurement protocols for bedload transport and SGN, the results of the campaign, and discuss the physics of the relationship between the measured quantities.
Impact of multi-temporal landslide inventories on landslide hazard assessment: a case study in the province of Belluno (Veneto Region, NE Italy)
Authors: Puliero Silvia , Meena Sansar Raj , Catani Filippo , Floris Mario
Published: March 2022

Frequent and extreme meteorological events can lead to an increase in landslide hazard. A multi-temporal inventory plays an essential role in monitoring slope processes over time and forecasting future evolution. In recent years, the province of Belluno (Veneto Region, NE Italy) was affected by two relevant and intense meteorological phenomena that occurred on October 27-30, 2018 (i.e. windstorm Vaia) and on December 4-6, 2020. Both events were characterized by heavy rainfall of up to 600 mm in 72 hours, triggering widespread landslides throughout the area. The analyses conducted on some local rain gauges in the sectors most affected by each storm show very high return periods (over 100 years) for both events, even though they occurred in a two-year time frame. This study aims to evaluate whether these strong meteorological phenomena are characterized by an increase in their frequency in the province of Belluno and to see what influence they have on slope instabilities, which are important for assessing landslide risk. The rainfall data available since 1950 have been investigated through statistical analysis to achieve these goals. The spatial and temporal evolution of slope instabilities has been examined through remote sensing techniques to compare landslides triggered in 2018 and 2020 with past instability phenomena in the same area. The results show the importance of multi-temporal databases for landslide hazard assessment after extreme meteorological events at the regional scale.
Coupled Greenland ice sheet-climate simulations with the Norwegian Earth System Model (NorESM2)
Authors: Goelzer Heiko , Langebroek Petra , Born Andreas
Published: March 2022

Long-term simulations of ice sheets and their interaction with the climate system require the application of Earth system models with interactive ice sheet components. To this end we present the first experiments performed with the CMIP6-type Norwegian Earth System Model (NorESM2) including a Greenland ice sheet model component. We present our coupling and modelling strategy, which builds on earlier work with the Community Earth System Model and show first results for two NorESM2 version with different resolution of the atmospheric component. We have performed and analyzed pre-industrial spinup and control experiments, historical runs and future projections under scenario ssp585, following the ISMIP6 protocol.
Building typologies for Norway: a case study for Oslo using machine learning
Authors: Ghione Federica , Mæland Steffen , Meslem Abdelghani , Oye Volker
Published: March 2022

To evaluate potential human and economic losses in a seismic risk assessment, it is important to define an exposure model by defining building materials and characteristics. The common approach to develop an exposure model is to have a first overview of the area with Google Earth and to perform extensive fieldwork in representative areas of the city. This procedure is time and cost consuming, and it is also subject to personal interpretation. To mitigate these costs, a Convolutional Neural Network (CNN) is used to automatically identify the different building typologies in the city of Oslo, Norway, based on facade images taken from in-situ fieldwork and Google Street View.

The present article attempts to categorize Oslo’s building stock in five main building typologies: timber (T), unreinforced masonry (MUR), reinforced concrete (CR), composite (steel reinforced concrete) (SRC) and steel (S). This method shows good results for timber buildings with 91% accuracy score, but only 41% for steel reinforced concrete buildings. These variations can be explained by differences in the number of labelled images for each typology, comprising the training data, and differences in complexity between typologies.

This work is the first tentative to identify Norwegian building typologies: based on experts judgement, the five types observed in Oslo can be applicable at national level. In addition, this study shows that CNNs can significantly contribute in terms of developing a cost-effective exposure model.
Trends in vegetation changes over wetland areas in Denmark using remote sensing data
Authors: Gutierrez Diaz Joan Sebastian , Humlekrog Greve Mogens , Wollesen de Jonge Lis
Published: March 2022

Land cover dynamics play a vital role in many scientific fields, such as natural resources management, environmental research, climate modeling, and soil biogeochemistry studies; thus, understanding the spatio-temporal land cover status is important to design and implement conservation measures. Remote sensing products provide relevant information regarding spatial and temporal changes on the earth’s surface, and recently, time series analyses based on satellite images, and spectral indices have become a new tool for accurate monitoring of the spatial trend, and land cover changes over large areas. This work aims to determine the trends of vegetation spectral response expressed as the Normalized Difference Vegetation Index (NDVI) over the period 2005 and 2018 and compare these trends with the land-use and cover changes between 2005 and 2018 in wetland areas across Denmark. Change detection methods between two years based on bi-temporal information may lead up to the detection of pseudo-changes, which hinders the land-use and cover monitoring process at different scales. We studied the potentiality of including NDVI temporal curves derived from a yearly time-series Landsat TM images (30-m spatial resolution) to obtain more accurate change detection results. We computed the NDVI temporal trends using pixel-wise Theil-Sen and Man-Kendall tests, then we explored the relationship between NDVI trends and the different land-use and cover change classes. We found a significant relationship between NDVI trends and changes in land use and cover. Changes from cropland to wetland and cropland to forest coincided with statistically significant (p≤0.05) negative NDVI, and positive NDVI trends, respectively. Changes from grasslands to permanent wetlands corresponded with statistically significant negative NDVI trends. The difference in vegetation productivity trends could be indicative of the combined effect of human activity and climate. We show that this combined analysis provides a more complete picture of the land use and cover changes in wetland areas over Denmark. This analysis could be improved if the NDVI time series is seasonally aggregated.
Compaction of cultivated peat soils, how does it affect GHG emissions and yield?
Authors: Hartmann Antonia , Berglund Örjan , Jordan Sabine , Berglund Kerstin
Published: March 2022

Objective: GHG emissions from cultivated peat soils can be substantial. Soil compaction by vehicular traffic alters aeration and water flow affecting gas flow and microbial activity. In tropical peatlands, compaction has sometimes been shown to reduce CO2 emissions. This project investigated how GHG emissions from cultivated peat soils in Sweden are affected by compaction using field and laboratory experiments.

Methods: In a long-term field trial, GHG emission and yield from compacted and non-compacted plots growing timothy, reed canary grass, and tall fescue on peat soil have been measured. Compaction in the field has been done by using a tractor with a total weight of 9640 kg. Compact density, penetration resistance, GHG emissions and yield in the different treatments were compared. In the lab, peat soil in steel cylinders were compacted using a uniaxial compression machine with defined stresses of 100, 200 and 300 kPa. GHG emissions were measured before, during and after compression.

Key results: Compact density of the peat soil changed for all crops, but the effect was just present in timothy one year after the compaction. In the lab, N2O emission increased with compaction, and CO2 emission decreased. 

Conclusions:  Compaction can alter the pore size distribution in the soil affecting GHG emissions. In this project, we found lower CO2 emissions from compacted peat but sometimes higher N2O emissions. Plots with reed canary grass and tall fescue were less affected by compaction than timothy, which is the traditional crop grown in the area.
Assimilating the remote sensing ocean color data into a biogeochemical model of the Baltic Sea
Authors: Liu Ye , Arneborg Lars
Published: March 2022

The objective of this study is to investigate if the assimilation of ocean color data into a complex marine ecosystem model can improve the hindcast of key biogeochemical variables in coastal seas. A localized Singular Evolutive Interpolated Kalman filter was used to make assimilation of the daily fully reprocessed product of Multi-Satellite chlorophyll observations into a three-dimensional ecosystem model of the Baltic Sea. Twin experiments are performed to evaluate the performance of the assimilation with respect to both satellite and in situ observations. Compared to the reference run, the assimilation was found to immediately and considerably reduce the bias, root mean square error, and increase the correlation with the spatial distributions of the assimilated chlorophyll data while this improvement is limited to the upper layer of the water column. This feature is explained by the weak correlation taken into account by the assimilation between the surface and deep phytoplankton. The assimilation scheme used is multivariate, updating all biogeochemical model state variables. The other variables were not degraded by the assimilation. More significantly, the skill metrics for non assimilated variables indicate that the hindcast of the mean data values at L4 was improved; however, improvements in the short-term forecast were not discernable. Our results provide general recommendations for the successful application of ocean color assimilation to hindcast key biogeochemical variables in coastal seas.
The Mie representation for Mercury‘s magnetospheric currents
Authors: Töpfer Simon , Narita Yasuhito , Heyner Daniel , Kolhey Patrick , Glassmeier Karl-Heinz , Motschmann Uwe
Published: March 2022

Poloidal–toroidal magnetic field decomposition is a useful application of the Mie representation for the reconstruction of Mercury‘s internal magnetic field. In addition, the decomposition method enables us to determine the current density observationally and unambiguously in the local region of magnetic field measurement. The application and the limits of the decomposition method are tested against the Mercury magnetic field simulation in view of BepiColombo‘s arrival at Mercury in 2025. The simulated magnetic field data are evaluated along the planned Mercury Planetary Orbiter (MPO) trajectories and the current system that is crossed by the spacecraft is extracted from the magnetic field measurements. Afterwards, the resulting currents are classified in terms of the established current system in the vicinity of Mercury.

 

Reference

Toepfer, S., Narita, Y., Exner, W., Heyner, D., Kolhey, P., Glassmeier, K. ‐H., Motschmann, U. (2021c)  The Mie representation for Mercury’s magnetospheric currents, Earth, Planets and Space 73:204. https://doi.org/10.1186/s40623-021-01536-8

Toepfer, S., Narita, Y., Glassmeier, K.-H., Heyner, D., Kolhey, P., Motschmann, U., Langlais, B. (2021a) The Mie representation for Mercury’s magnetic field, Earth Planets Space 73:65. https://doi.org/10.1186/s40623-021-01386-4

 

 
Identification of regional landslide triggering thresholds in the Lombardy region using multivariate statistical analysis 
Authors: Palazzolo Nunziarita , Peres David Johnny , Creaco Enrico , Cancelliere Antonino
Published: March 2022

Landslides represent a critical natural hazard in many mountain and hilly regions worldwide, provoking causalities and property damages. Landslide triggering thresholds are at the basis of early warning systems to protect livelihoods. Traditionally, landslide triggering thresholds are expressed in terms of not more than two or three precipitation variables, mostly rainfall event depth, and duration. Indeed, the availability of soil moisture information and its proxies (such as antecedent precipitation), can improve the performance of landslide triggering thresholds, thus calling for a multivariate approach.  

Given the above context, this study aims to develop regional landslide triggering thresholds by using multivariate statistical analysis to investigate the performance of multiple combinations of rainfall variables and event soil moisture data, in the identification of regional rainfall thresholds for landslide initiation. Lombardy region (northern Italy) was selected as a study area since it is one of the most susceptible Italian regions to landslide risk. The data on landslides were retrieved from the FraneIalia project that is a comprehensive spatio-temporal database of recent landslides affecting the Italian territory from 2010 onwards. For the Lombardy region, from 2010 to 2019, 592 landslides events triggered by rainfall were detected, all distributed within the mountain and hilly areas of the region.

Precipitation and soil moisture time series, instead, were derived from the ERA5-Land reanalysis dataset and the rainfall events were reconstructed using the CTRL-T code developed by IRPI-CNR, which characterizes each rainfall event by duration, mean intensity, total depth, and peak intensity. The most probable rainfall conditions associated with each landslide are, then, computed based on the distance between the rain gauge and the landslide location. Different combinations of precipitation and soil moisture variables are tested using dimensionality reduction multivariate statistical techniques. An optimization procedure is set up with the aim to maximize the True Skill Statistic (TSS) ROC index associated with parametric thresholds. Several multivariate combinations show better performances than the traditional depth-duration power-law thresholds.  
Integrated seismic and borehole investigation of the deep weathering structure – case study of Santa Gracia Reserve, Chile
Authors: Trichandi Rahmantara , Bauer Klaus , Ryberg Trond , Bataille Klaus , Krawczyk Charlotte M.
Published: March 2022

Subsurface imaging of the critical zone, where are regolith is produced from bedrock, plays a significant role in understanding the geological and biological interaction at depths. The depth where we can find the intact bedrock is also often referred to as the weathering front. In the scheme of the EarthShape project, we assess one of the hypotheses which link the advance of weathering front to different climate conditions. We present the seismic investigation result from Santa Gracia National Reserve, Chile, one of the main EarthShape sites, which is in a transitional area between the arid to the semi-arid climatic zone. We investigate the weathering profile of this area by acquiring a 500 m long near-surface seismic profile using weight drop sources and 3-component geophones. With the acquired data, we perform two different seismic imaging methods: 1) Body wave tomography, and 2) Multichannel Analysis of Surface Wave (MASW) with Bayesian inversion. Both methods allow us to image the P- and S-wave velocity of the subsurface down to 80 and 60 meters depth, respectively. In addition to the absolute velocity models, we also produce the vertical velocity gradient model, which also provides us with extra tools in interpreting the weathering structure. The resulting models were then validated by existing borehole data located in the middle of the profile. Using the 87 meters deep borehole information, we identified three major layers in the weathering profiles: saprolite, weathered bedrock, and bedrock. The layers were identified by the different seismic velocities, which represent different stages of weathering in the subsurface. Across the profile, the identified weathering front can be traced down to 30 meters depth and is relatively parallel to the surface topography. The interpreted weathering layers also correlate with existing geochemical analysis of the borehole coring and even another perspective in the multi-disciplinary interpretation of the weathering zone. Accordingly, seismic imaging of the critical zone using different methods allows us to improve the critical zone interpretation, either as a combined or independent approach in regions without borehole data available.
Soil erosion assessment via temporal and spatial high-resolution time-lapse Structure from Motion on rainfall simulation plots
Authors: Epple Lea , Bienert Anne , Grothum Oliver , Eltner Anette
Published: March 2022

High-resolution information on the processes and rates of soil erosion, transport, and deposition, offer important knowledge for soil erosion modelling, and the protection and sustainable management of soil. It helps improve the cross-scale understanding on aspects as aggregate breakdown, rill erosion, swelling and shrinking effects, and rill-network evolution. As a non-invasive, high-resolution, and cost as well as time-efficient method, Structure from Motion (SfM) presents a valuable tool to calculate soil loss, depict soil surface change detection, and offer high-resolution information on soil and soil erosion processes. Even though SfM shows in general higher erosion rates, due to the influence of non-erosive processes, the technique is altogether in good agreement with the sampling data at the outlet. We monitor soil erosion on multiple erosional plots and with spatial and temporal high-resolution photogrammetry to assess its feasibility over time.

For this purpose, we conduct 12 rainfall simulations on a three times one metre plot, on different sides, with different vegetation cover, tillage, and initial soil conditions. Seven to ten synchronized time-lapse cameras are set up around the plot, taking pictures every 10-60 seconds. The data thus obtained allow change detection assessment via digital elevation models of difference at least once per minute. The elevation change by SfM is validated via bulk density measurements, and sampling at the plot’s outlet assessing runoff, and sediment concentration at minute intervals. During an overflow experiment, we measure flow velocity via video using particle tracer and manually via colour tracer, gaining spatial and temporal distribution information on the flow velocity. Using low-cost sensors, we furthermore monitor the progress of the soil moisture and temperature during the whole rainfall simulation.

We present sampled and photogrammetric results based on a dozen rainfall simulations at the micro-scale with a very high temporal and spatial resolution. This gives an insight into spatial distribution and development of soil erosion processes on a sub-minute resolution. We compare these data to gain knowledge on the feasibility of temporal and spatial high-resolution SfM soil erosion assessment and their usability for the validation and calibration of process-based soil erosion models.
Recent Developments in Environmental Seismology
Authors: Walter Fabian
Published: March 2022

Seismologists use elastic waves to probe and study the Earth’s interior. With the advent of more portable instrumentation and dense sensor coverage, recent attention has been directed to small scales near our planet’s surface. The resulting field of “environmental seismology” includes a particular focus on natural hazards and mass movements ranging from small rock falls to massive avalanches made up of snow, ice and/or rock. Local and regional seismic networks also capture seismic signatures of stable deformation including sliding and fracture signals accompanying glacier and landslide creep. With the help of passive interferometry, such data furthermore reveal structural changes of potentially unstable masses that may represent failure precursors.

Over the past 1-2 decades, numerous studies have revealed the usefulness of seismology in environmental studies. Consequently, seismic instrumentation is being introduced into monitoring infrastructure to improve warning capabilities and scientific research. This presentation discusses recent seismometer deployments and data mining approaches in environmental seismology. The focus is on Alpine terrain, where dense coverage of earthquake monitoring stations and other seismometers exist, which lends itself to environmental studies. Provided that specific challenges in sensor design and data processing are soon tackled, a range of pilot projects suggests that seismic techniques will soon be part of the next generation of operational monitoring and warning systems in Alpine terrain.
Contributions of ocean bottom pressure and density changes to regional sea level change in the East Indian Ocean from GRACE, altimetry and Argo data
Authors: Yakhontova Alisa , Rietbroek Roelof , Kusche Jürgen , Stolzenberger Sophie , Uebbing Bernd
Published: March 2022

Understanding variations in the ocean heat content is tightly linked to understanding interactions of the global energy cycle with the regional water cycle. Mass, volume, temperature and density changes of  the ocean water column can be estimated with complimentary observations of sea surface height from radar altimetry, ocean bottom pressure from Gravity Recovery and Climate Experiment (GRACE), temperature and salinity from Argo floats. These three techniques have their specific deficiencies and advantages, which can be exploited in a joint inversion framework in order to improve temporal and spatial coverage of oceanic temperature and salinity estimates as well as regionally varying sea level contributions. Solving an inverse problem for temperature and salinity, forward operators are formulated linking the satellite observations to temperature and salinity at depth. This is done by (1) parametrization of temperature and salinity profiles over the full depth of the ocean with B-splines to reduce dimensionality while keeping complexity of the data intact and (2) linearization of the integrated density from parameterized T/S curves. We apply forward operators in the East Indian Ocean to resolve for sea surface height, ocean bottom pressure, temperature and salinity, and assess the regional importance of these factors. We explore the stability of a joint inversion using these forward operators in combination with along-track radar altimetry, GRACE and temperature and salinity by exploring a closed-loop inversion.
Characterization of regional heatwaves in southern South America
Authors: Suli Solange , Barripedro David , García-Herrera Ricardo , Rusticucci Matilde
Published: March 2022

Heat waves (HWs) can cause large socioeconomic and environmental impacts and they have become more intense and frequent across most land regions in the world since 1950s. Additionally, they will further increase in the future even if global warming stabilized at 1.5ºC. Therefore, HWs are one of the climate extremes of major concern. In this study we obtain for the first time a regional catalogue of warm season (WS: October – March). HW events for southern South America (approximately 17–60ºS, 35–80ºW) during 1979 – 2018 using maximum temperature data from 137 conventional weather stations. Moreover, we assess the synoptic patterns associated with regional HWs from daily data of the ERA5 reanalysis.

By applying hierarchical clustering of local HWs at the weather stations, we identify five regions based on stations with high co-occurrence of simultaneous HWs. Regional HW events are defined as WS periods of at least three consecutive days with maximum temperature exceeding the 90th percentile of the local TMax distribution on more than 40% of the stations of each region. We also calculate the accumulative maximum temperature anomaly to rank the magnitude of regional HW events.

For all regions, HW events are associated with significant and co-located positive 500 hPa geopotential height (z500) anomalies and with the intensification of the Northwestern Argentinean Low (NAL, The exception is the southernmost region, where HW events are linked to barotropic extratropical systems blocking the westerly flow. HW events affecting northern and central-eastern transitional regions are also associated with positive outgoing longwave radiation (OLR) anomalies, pointing to enhanced subsidence by intensification of the South Atlantic convergence zone (SACZ), as well as an intensification of the northerly low-level flow associated with South American Low-Level Jet (SALLJ) events. The results suggest that small changes in the magnitude and / or location of the aforementioned signatures can shape HWs over different regions of the domain. Finally, the frequency of regional HW days shows a significant increase over central and northern Chile, central Argentina, and northern Argentinian Patagonia. On the whole, except for the two southernmost regions, the most severe regional events have occurred during the 21st century.