bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and temporal patterns of snowmelt refreezing in a Himalayan catchment
Authors: Veldhuijsen Sanne , De Kok Remco , Stigter Emmy , Steiner Jakob , Saloranta Tuomo , Immerzeel Walter
Published: March 2021

Seasonal snow contributes significantly to the annual runoff in the Himalaya and both timing and volume are important for downstream users.  In  polar regions, meltwater refreezing within snowpacks has been well-studied. While the conditions in the Himalaya are considered favorable for refreezing, little is known about refreezing in this region, hindering a complete understanding of seasonal snowmelt dynamics. In this study, we simulated refreezing with the seNorge (v2.0) snow model for the Langtang catchment in the Nepalese Himalaya covering a 5-year period. Thereby, we aim to improve our understanding about how refreezing varies in space and time and to provide a framework for future snow modeling studies. The first part of this study focuses extensively on developing meteorological forcing data, which were derived from an unique elaborate network of meteorological stations and high-resolution meteorological simulations. The snow model was validated against in-situ snow observations and snow cover satellite data. In the second part of this study, we analyze the spatial and temporal refreezing patterns, and attempt to identify possible driving factors. The results show that the annual average refreezing amounts to 122 mm (21% of the total melt). We found that the magnitude of refreezing varies strongly in space depending on elevation and aspect. In addition, there is a strong seasonal altitudinal variability related to air temperature and snow depth, with most refreezing during the early melt season. We also found a substantial intra-annual variability, which mainly results from fluctuations of snowfall, highlighting the importance of using multi-year time series in refreezing assessments. Daily refreezing simulations decreased by 84% (to an average 19 mm year-1) compared to hourly simulations, emphasizing the importance of using sub-daily time steps to capture diurnal melt-refreeze cycles. Climate sensitivity experiments revealed that refreezing is highly sensitive to future changes in air temperature, as a temperature increase of 2°C leads to a refreezing decrease of 35%. We conclude that including refreezing with a sub-daily temporal resolution is highly relevant for understanding snow dynamics in the current and future climate of the Himalaya.

 
The influence of different cover crop residues quantities on soil structural stability
Authors: Stegarescu Gheorghe , Reintam Endla , Tõnutare Tõnu
Published: March 2021

Cover crops are widely known for their capacity to improve the soil biological properties and soil structural stability. Nevertheless, the cover crop residues quantity necessary to improve these soil properties is not yet really known. A 30-day incubation experiment was conducted to explore the effect of oilseed rape (Brassica napus) residues (ORR) as a cover crop on the soil aggregate stability of sandy loam soil. The fresh ORR was mixed with the soil at different rates starting from 1.0 to 6.0 g C kg-1 of soil. The experiment consisted of five treatments: bulk soil (I), soil mixed with ORR at a rate of 1 g C kg-1 of soil (II), soil mixed with ORR at a rate of 2 g C kg-1 of soil (III), soil mixed with ORR at a rate of 4 g C kg-1 of soil (IV), soil mixed with ORR at a rate of 6 g C kg-1 of soil (V). During 30 days of incubation the soil moisture, soil water stable aggregates, and microbial substrate induced respiration rates were measured. The aggregate stability significantly increased after 30 days only in the treatment with 1 g C kg-1 of soil. In turn, the ORR applied at a rate of 6 g C kg-1 of soil significantly decreased the soil aggregate stability. The higher the ORR addition rate the lower was the soil basal respiration and substrate induced respiration. The general conclusion was that the higher quantity of ORR increased the soil moisture which subsequently created unfavorable conditions for the soil microbial activity and led to soil aggregate stability degradation. However, this conclusion must be validated in a field study where the soil moisture and temperature conditions are much more variable compared to our incubation experiment.
Estimating Individual Sea Vessel NO2 Emissions using Spatial Autocorrelation on S5P-TROPOMI Satellite Data
Authors: Kurchaba Solomiia , Veenman Cor J. , van Vliet Jasper , Verbeek Fons J.
Published: March 2021

Starting from January 2020, new IMO regulations limiting the Sulphur content of the fuel used by seagoing vessels came into force. As of 2021, new and stricter NOx emission standards are applied for newly built ships entering the North and Baltic Sea. There are various methods that are used to measure the pollution produced by ships in ports or off the coastal areas. Due to practical limitations, however, the conduction of such monitoring above the open sea has not been possible up to now.

The TROPOspheric Monitoring Instrument onboard the Copernicus Sentinel 5 Precursor satellite (TROPOMI/S5P) provides the atmosphere monitoring data with an unprecedented spatial resolution. With this instrument plumes produced by individual ships of substantial size can be detected. In our study we focus on application of the TROPOMI NO2 tropospheric column for tracking back the emission produced by individual ships at open sea.

On a global scale, individual ships are considered to be low-source pollution emitters. As a result, it is difficult to separate an emission plume from the background pollution, especially, in case of comparable background concentration. In order to improve the distinction between the plume and the background, we propose the use of the local spatial autocorrelation measure Moran’s I. This measure amplifies regular shaped high-concentration structures and suppresses random co-occurring concentration peaks. By means of the Automated Identification Signal (AIS) data that records historical ship locations, the detected structures can be associated with individual ships. We further propose heuristic algorithms using local weather conditions (wind speed/direction) for an efficient ship-plume matching and NO2 concentration estimation.

We evaluate the quality of a ship-plume assignment by comparing the estimated NO2 concentration with model-based emission estimations determined from speed and length of the ship. Notable linear correlation between our estimations and the model-based values supports the proposed method.

This work contributes to realising global scale verification/estimation of emission plumes with satellites by providing automated and enhanced processing of satellite retrievals for identifying and quantifying of NOx plumes produced by individual seagoing vessels.

This work is funded by the Netherlands Human Environment and Transport Inspectorate, the Dutch Ministry of Infrastructure and Water Management, and the SCIPPER project which receives funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement Nr.814893.
Nature Based Solutions for Ecosystem Restoration in Southern Europe
Authors: Kapovic Solomun Marijana , Ferreira Carla , Ristić Ratko , Kalantari Zahra , Rahmati Omid
Published: March 2021

The southern Europe has been recognized as a “hot spot” of ongoing climate change in Europe, being particularly vulnerable to natural disasters in the recent decade. Southern Europe suffers from frequent and disastrous floods, drought and wildfires which foster land degradation while certainly threatening ecosystems in a changing climate. Measures for ecosystem restoration and climate change mitigation are of utmost importance particularly for agricultural and forestry ecosystems. The urgent action to combat climate change impacts calls for measures e.g. by implementing nature-based solutions (NBS) in key sectors to achieve ecosystem restoration and land degradation neutrality, and thus assure relevant ecosystem services to society and human wellbeing. Various approaches can be used to apply NBS, in different fields but practical implementation of NBS needs participatory involvement, institutional and human resources capacity building, requiring local communities and vulnerable groups inclusion. Ecosystem restoration and climate change mitigation achieved by multiple functions of NBS also contribute to the implementation of UN 2030 Agenda for Sustainable Development Goals and Land Degradation Neutrality targets, and lead to enhanced development of circular economy. This research investigates NBS as an opportunity for ecosystem restoration in southern Europe, aiming to provide a comprehensive overview of main obstacles and opportunities for the regional specific conditions.

Key words: ecosystem restoration, southern Europe, climate change, land degradation
Examination of ultraviolet germicidal radiation for inactivating microorganisms in melted snow and ice samples
Authors: Nakazawa Fumio , Goto-Azuma Kumiko
Published: March 2021

The storage of melted snow and/or ice samples from snow pits and ice cores in a refrigerator for long durations may be limited by an increase in particle concentration caused by microbial growth after approximately 1–2 weeks. In this study, we examined an ultraviolet (UV) disinfection method for the storage of melted snow and/or ice samples. Surface snow obtained from Glacier No. 31 in the Suntar-Khayata Range, eastern Siberia, Russia was divided into two portions for UV treatment and untreated controls. Particle concentrations in the samples were measured using a Coulter counter (Multisizer 4e; Beckman Coulter, USA). Whereas the particle concentration in untreated samples increased, no obvious increase was observed over 53 days in the samples subjected to UV treatment. In addition, the original particle concentrations were unaffected by UV treatment. These findings indicate that the antimicrobial effect of UV radiation is effective for long-term sample storage of melted water samples. A detailed analysis of the particle size distribution for untreated samples indicated that particles of 0.7–1.2 µm appeared within the first 7–14 days. Measurements using a viable particle counter (XL-10BT2 and XL-28A1; RION Co. Ltd., Japan) confirmed that these were biological particles, suggesting that microbial growth occurs during this period. Subsequently, the particles shifted to a smaller size and a higher concentration, suggesting that the decomposition of microorganisms occurred in the water samples. Therefore, the size distribution of particles in untreated samples reflected the growth and decomposition of microorganisms over time.
Heat transport in turbulent electro-hydrodynamics
Authors: Zaussinger Florian , Haun Peter , Szabo Peter , Egbers Christoph
Published: March 2021

Electro-hydrodynamics (EHD) plays an important role in many industrial applications. Ink-jet printers, microwave drying facilities, and lab-on-a-chip devices utilize dielectric properties of the working fluids and their manipulation without moving parts. Another application is found in heat exchangers, where the dielectrophoretic force is used to increase heat transfer due to thermal buoyancy. In particular, the dielectrophoretic force has great advantages in low- and micro-gravity conditions since the force can be used to mimic a gravitational force field. Hence, convection in a rectangular cavity induced by EHD is a model system comparable to Rayleigh-Benard (RB) convection. However, the electric-driven buoyancy term and dielectric heating make the system more complex. The direction of the triggering dielectrophoretic force depends mainly on the temperature gradient which can be used to manipulate the heat flux or the entire structure of the convective flow. Layer formation, comparable to double-diffusive convection, and convective overshooting are two representative cases which can be established by EHD, too. We will present first results of turbulent convection induced by EHD in the rectangular cavity and the impact of volumetric heating. For this purpose, the Boussinesq approximation, as well as compressible models for EHD, are tested also for applicability in geophysical relevant regimes. This is a crucial point as the limitations by incompressible modeling are not well-understood for EHD. The main focus of the study is the analysis of the heat flux as a function of the thermo-electric feedback and the dielectric heating rate. Convective overshooting and layer formation are examined closely. Results of this study are used to estimate transport properties and time scales. Applications using EHD are the GeoFlow and AtmoFlow experiments. The GeoFlow experiment was conducted several years on the International Space Station and gained deep insight into EHD driven convection in the spherical shell geometry. The AtmoFlow experiment is under construction and is planned for operations on the ISS in 2024. This experiment is designed to study atmospheric like flows in the spherical shell.
Spherical gravity inversion of GRAIL data
Authors: Chepigo Lev , Lygin Ivan , Bulychev Andrey , Kirill Kuznetsov
Published: March 2021

Taking into account sphericity is one of the most relevant questions of interest for gravity researchers today. It’s especially important in data analysis of regional surveys and satellite missions.

Modern satellite missions are characterized by high accuracy of measurements, as well as a high degree of detail, which makes it possible to construct detailed grid density models of Earth and Moon, however, when automating this process, the following problems arise:

- long duration of the inversion process;

- need for a large amount of RAM when using standard approaches to solving the linear inverse problem of gravity prospecting for grid models;

- high sensitivity of gravity inversion algorithms to the upper cells;

The first problem can be solved by inverting of gravity in the spectral domain using the fast Fourier transform. In this case, the time complexity of the inversion algorithms is reduced by times, which significantly accelerates the selection of the model.     

To reduce the memory used, it is necessary to memorize the gravity spectrum for only one cell for each pair of coordinates depth - latitude, since cells with at the same depth and latitude have the same gravitational effects, shifted by the step of cells in the grid model.

Finally, to increase the sensitivity of the inversion algorithms to deep cells, you can use the variable parameter of the gradient descent step (learning rate in machine learning), depending on the depth as an exponential or any other function, in combination with regularization.

The proposed approach was applied to the data of the GRAIL mission, and as a result, a density model of the Moon was constrained with the following grid steps: 0.5o in latitude, 0.7o (pi / 512) in longitude and 10 km in depth.

The fitted model was used to estimate the possible parameters of the sources of lunar mascons. It stands to mention the differences in the geometry of the mascon sources, which can be divided into two groups: isometric sources and sources with channels ascending to the surface, through which, probably, lunar basalts entered the surface.

The proposed approach allows constrain density models of celestial bodies fast enough using a personal computer (less than an hour for a model with the parameters mentioned above), and also takes into account the weak sensitivity of standard inversion algorithms to deep cells.
Microplastics in Lake Onego sediments: occurrence and accumulation patterns.
Authors: Zobkov Mikhail , Belkina Natalia , Kovalevski Vladimir , Zobkova Maria , Efremova Tatiana , Galakhina Natalia
Published: March 2021

Lake Onego is the second largest lake in Europe. Sediment samples (23) were collected in different regions of the lake. Microplastics (MPs) were extracted from sediments with heavy liquid, oxidized and its abundance was determined using a microscope with a magnification of 40x. The extraction efficiency and the level of external contamination were evaluated, the results were blank-corrected. The anthropogenic origin of randomly selected MPs items was confirmed by Raman spectroscopy. MPs were detected in all samples. Maximum MPs abundances in sediments were observed in areas associated with the mouth of the second largest tributary of the lake – river Shuya and Petrozavodsk Bay (2244 ± 1901 pcs/kg DW; n= 6, p = 0.95), the open part of the lake (2356 ± 1689; n = 5, p = 0.95) and in Kizhi National Park (3413 ± 2005; n = 4, p = 0.95). In mean MPs abundance in Lake Onego was 2141±1144; n=22; p = 0.95).   Fibers dominated in most of the samples (64±14%; n=22; p = 0.95). It was established, that fibers accumulate in sediments together with medium silt fraction (0.01-0.05 mm). MPs abundance was extremely high in Kondopoga bay (217 000 pcs/kg DW) and was mainly represented by microcapsules, possibly due to impact of the wastewaters of the Pulp and Paper mill plant at this site. In mean, MPs abundance in Lake Onego sediments was at least two times higher, than was previously established in Baltic Sea with similar methodology. Further comprehensive assessment of MPs contamination rates and forecasting consequences of this contamination to ecosystem is an urgent need in current research.

The study was supported by the Russian Science Foundation grant number 19-17-00035.
A new method to evaluate the accuracy of the sediment source mixing model
Authors: Shi Peng , Yu Yang , Bai Lulu , Li Peng
Published: March 2021

Fingerprint identification technology has been widely used to extract sediment source proportions, but the only indicator currently available to assess the accuracy and applicability of the results is good-fit (GOF). We have proposed a new method to evaluate sediment source results and quantitatively evaluate the applicability of sediment source mixing models. A typical check dam in the Loess Plateau was used to evaluate the new method by combining field sampling and numerical simulations. Collins (C) and modified Hughes mixing (M-H) models were used to quantitatively analyze the sediment sources of the check dams built and operated until July 2017. The results showed that the best combination for the fingerprint factors in the dam-controlled watershed, was Zn, Mg, Mn, and d (0,1), which had an 86.1% identification ability. With rainfall, the relative sediment contribution rates from gullies, sloping farmland, grasslands, and branch ditches were 54.22%, 23.56%, 15.54%, and 6.68%, respectively. The M-H mixing model had a higher comprehensive score (2.72) when compared with the C mixing model (2.54). The comprehensive evaluation method could provide an effective scientific theoretical basis for optimal allocations of water and soil conservation in small watersheds.
Analysing the Return Period and Risk under the Influence of Physical Covariates on Hydrological Extreme
Authors: Das Jew , Umamahesh Nanduri , Jha Srinidhi
Published: March 2021

For sustainable water resources planning and management, it is necessary to redefine the concept of return period, risk, and reliability of hydrologic extreme under non-stationary condition. Thus, the present study aims to examine the return period, risk introducing physical based covariates in the location parameter of the generalised extreme value (GEV) distribution. The study is performed over the Godavari River basin, India. The expected waiting time (EWT) approach is used to make comparison of return period, risk between stationary and non-stationary approaches. From the analysis, it is found that 50% of the gauging stations are impacted by large scale modes/oscillations and regional hydrological variability, primarily by Indian Summer Monsoon Index (ISMI) and precipitation. The EWT interpretation estimates that the non-stationary return period, risk, and reliability are significantly different from stationary condition. Hence, it is concluded that return period analysis and risk assessment using non-stationary approach can be beneficial to water managers and policy makers in order to devise sustainable and resilient water resources infrastructure under climate change scenario.

Keywords: Extreme value analysis; Return period; Risk; Non-stationarity; Uncertainty
Subseasonal forecasts of the northern Queensland floods of February 2019: Causes and forecast evaluation
Authors: Tsai Wayne Yuan-Huai , Lu Mong-Ming , Sui Chung-Hsiung , Cho Yin-Min
Published: March 2021

During the austral summer 2018/19, devastating floods occurred over northeast Australia that killed approximately 625,000 head of cattle and inundated over 3000 homes in Townsville. This disastrous event was attributed to a quasi-stationary monsoon depression over northeast Australia and the convection associated with MJO over the western Pacific (Cowan et al. 2019). We found that the unusual rainfall was a record-breaking subseasonal peak rainfall event (SPRE) based on the CMORPH daily precipitation data since1998 (Xie et al. 2017). The SPRE is defined as the highest 15-day accumulative rainfall in the running 90-day windows (Tsai et al. 2020). Results of observational data analysis over the recent 21 years (1998~2020) of ERA-interim, OLR, and CMORPH datasets suggest that the northeastern Australian SPREs can be influenced by multiple large-scale drivers, in particular the MJO and equatorial Rossby waves. The occurrence time of the SPRE is associated with MJO activity, while the mean rainfall intensity is more closely associated with the equatorial Rossby waves. The circulation pattern of the SPREs can also be influenced by the equatorial Rossby waves. Using the hindcast data in S2S database we found that the models can capture the SPREs up to one week of the lead times. Characteristics of the activities of MJO and equatorial Rossby waves over the Indonesia-Australia region and their implication to the extended-range SPRE predictability will be discussed.

Key words: S2S prediction, Australian summer monsoon, subseasonal peak precipitation event, extreme rainfall

References:

Cowan, T., Wheeler, M.C., Alves, O., Narsey, S., de Burgh-Day, C., Griffiths, M., Jarvis, C., Cobon, D.H., Hawcroft, M.K., 2019. Forecasting the extreme rainfall, low tempera- tures, and strong winds associated with the northern Queensland floods of February 2019. Weather Clim. Extremes 26 (100), 232. https://doi.org/10.1016/j.wace.2019. 100232.

Tsai, W. Y.-H., M.-M. Lu, C.-H. Sui, and P.-H. Lin, 2020: MJO and CCEW Modulation on South China Sea and Maritime Continent Boreal Winter Subseasonal Peak Precipitation. Terr. Atmos. Oceanic Sci., DOI: 10.3319/TAO.2019.10.28.01

Xie, P., R. Joyce, S. Wu, S. Yoo, Y. Yarosh, F. Sun, and R. Lin, 2017: Reprocessed, Bias-Corrected CMORPH Global High-Resolution Precipitation Estimates from 1998. J. Hydrometeor., 18, 1617–1641, https://doi.org/10.1175/JHM-D-16-0168.1
Observed Long-Term Trends of the Atmospheric Circulation and of Dry and Moist Static Energies
Authors: Franzke Christian , Harnik Nili
Published: March 2021

The atmospheric circulation response to global warming is an important problem which is theoretically still not well understood. This is a particular problem since climate model simulations provide uncertain, and at times contradictory, projections of future climate. In particular, it is still unclear how a warmer and moister atmosphere will affect the atmospheric circulation and mid-latitude storms. Here we perform a trend analysis of various atmospheric circulation measures and of the budgets of dry and moist static energy transports, which will contribute to our understanding of the role of moisture in circulation changes. Our analysis is based on the JRA-55 reanalysis data covering the period 1958 through 2018 for both winter and summer seasons. We focus our analysis on zonal mean quantities for the full latitudinal circles as well as for the Atlantic and Pacific sectors.

We find significant trends in zonal wind, eddy kinetic energy, Eady growth rate, diabatic heating rates, and specific humidity. The zonal wind changes appear to be in thermal wind balance. We also find that the increase in specific humidity is intensifying the trend in eddy moist static energy transport when compared with eddy dry static energy transport. Since band-pass filtered eddy moist static energy transports are related to storm tracks this suggests that increasing moisture in the atmosphere is contributing to the intensification and meridional shifts of storm tracks. Furthermore, our results suggest that global warming predominantly enhance heat fluxes and to a lesser extend momentum fluxes.
Estimating energy dissipation in internal solitary waves breaking on slopes
Authors: Terletska Kateryna , Maderich Vladіmir , Talipova Tatiana
Published: March 2021

The shoaling mechanisms of internal solitary waves that propagate horizontally are an important source of mixing and transport in the coastal zones. Numerical modelling, llaboratory experiments and observations are needed for understanding wave energetics, especially energy transformation during waves interaction with the slopes. Two shoaling mechanisms are important during interaction with the slope: (i) wave breaking that results in mixing and dissipation, (ii) changing of the polarity of the initial wave of depression on the slope. Classification based on regimes of interaction with the slope was presented in [1]. Four zones were separated in αβγ (γ - is slope angle, α-  is the non-dimensional wave amplitude (wave amplitude normalized on the thermocline thickness) and β – is the blocking parameter that is the ratio of the height of the bottom layer on the shelf to the incident wave amplitude) classification diagram: (I) without changing polarity and wave breaking, (II) changing polarity without breaking; (III) wave breaking without changing polarity; (IV) wave breaking with changing polarity. It was shown that results of field, laboratory and numerical experiments are in good agreement with proposed classification.  In the present study we estimate energy dissipation for all the types of interaction and present the algorithm for building a zone map with a ‘hot spot’ of energy dissipation for real slopes in the ocean.

 

[1] K Terletska, BH Choi, V Maderich, T Talipova  Classification of internal waves shoaling over slope-shelf topography RUSSIAN JOURNAL OF EARTH SCIENCES vol. 20, 4, 2020, doi: 10.2205/2020ES000730
Assessment of the Socio-Economic Impact of Flooding in Shkodra Region, Albania.
Authors: Hasaj Alkida
Published: March 2021

In the recent years, flood situations have been experienced in some regions of Albania, but those that constitute a greater risk are those in the sub localities of Shkodra region. Fortunately, natural disaster are events that occur rarely, but the truth is that they have a high impact on the lives of many people, especially those belonging to developing countries such as Albania. They are associated with the loss of many lives, causing major impact on economic performance and social aspects as well as breaking, the chain of macro and microeconomic balances.

The purpose of this study is to identify the socio-economic impact of floods in the Shkodra region. Describing also the different categories of cost imposed by natural hazard as flood and the most effective way of economic recovery in the conditions of a small developing countries such as Albanian economy. This valuation will be carried out using secondary data such as; the macro and micro economic impact of these natural disasters, climate change, floods over the years in the Shkodra region, damage caused and management of these natural disasters. While primary data are provided through the qualitative method of structured interviews, designed to highlight the socio-economic impact of the flood on individuals and families in these areas, during 2018 flood.

Many catastrophes cannot be avoided, especially natural disasters, however their effects can be mitigated through good management. Over the last 30 years, investments in rehabilitating flood protection infrastructure have been minimal. Flood damage has been assessed mainly after events and detailed flood protection models have been prepared mainly based on emergency responses. Residents affected by flood experienced damage and loss, and while seasonal rains begin, they are worry and fear for loss property and livestock.

 

Key word; Flood, Climate Change, Economic Impact, Social Impact, Shkodra Region.

 
Transient Electromagnetics at Stromboli volcano, Italy: a virtual and field experiment
Authors: Schneider Carolin , Spitzer Klaus , Hort Matthias
Published: March 2021

Among others, the transient electromagnetic method (TEM) is used in investigating volcanic systems. It is capable of imaging conductive structures, such as hydrothermal systems and magmatic pathways, which are of great volcanological interest since they are attributed a key role in volcanic eruptions. Based on this motivation, we aim to investigate the medium depth resistivity structure of Stromboli volcano, Italy. Its persistent activity makes it an ideal target to investigate whether TEM can image changes in the subsurface conductivity structure associated with volcanic eruptions.
In order to determine a reasonable measurement configuration, we conduct so-called virtual experiments, i.e., three-dimensional TEM simulations on a digital elevation model. The sophisticated routine combines vectoral finite elements for spatial discretization and a time integration based on a Krylov subspace method. Furthermore, in order to minimize computational cost and run-time, automated adaptive mesh refinement is included.
Within the presentation, we introduce our modelling workflow and simulation routine, and link our numerical findings to the results of our field measurement at Stromboli volcano, Italy, in June 2019.
Actively heated fiber optics based thermal response test
Authors: Gu Kai , Zhang Bo , Shi Bin , Liu Chun , Bayer Peter , Wei Zhuang
Published: March 2021

In the pursuit of sustainable development and the mitigation of climate change, shallow geothermal energy has been widely recognized as a type of clean energy with great potential. Accurate estimation of thermal ground properties is needed to optimally apply shallow geothermal energy technologies, which are of growing importance for the heating and cooling sector. A special challenge is posed by the often significant heterogeneity and variability of the geological media at a site.

As an innovative investigation method, we focus on the actively heated fiber optics-based thermal response test (ATRT) and its application in a borehole in Changzhou, China. A copper mesh heated optical cable (CMHC), which both serves as a heating source and a temperature sensing cable, was applied in the borehole. By inducing the electric current to the cable at a relatively low power of 26 W/m, the in-situ heating process was recorded at high depth resolution. This information serves to infer the thermal conductivity distribution along the borehole. The presented field experience reveals that the temperature rise in the early phase of the test should not be used due to initial heat accumulation caused by the outer jacket of the CMHC. The comparison of these results with those of a conventional thermal response test (TRT) and a distributed thermal response test (DTRT) in the same borehole confirmed that the ATRT result is reliable (with a difference less than 5% and 1%, respectively). Most importantly, this novel method affords much less energy and testing time.

Additionally, to estimate the uncertainty and limits associated with the method, a 2D axisymmetric numerical model based on COMSOL Multiphysics® has been developed. The results indicate that an accurate calculated thermal conductivity requires heating duration to be in the range of 90~400 min considering test efficiency and cost. Our study promotes ATRT as an advanced geothermal field investigation method and it also extends the applicability of the thermal response test as a downhole tool for measurement of soil hydraulic properties.
Towards Efficient Online Deformation Monitoring of Transport Infrastructure using Sentinel-1 Interferometry
Authors: Piter Andreas , Haghshenas Haghighi Mahmud , Motagh Mahdi
Published: March 2021

The transport infrastructure is an important basis for the German economy. Therefore, the German land surveying authorities use conventional levelling methods to monitor potential deformations at roads and bridges. So far, the deformation monitoring is time consuming and expensive, making it impossible to cover whole Germany in near real-time. The project SAR4Infra aims at supporting the German land surveying authorities by exploiting the full potential of radar remote sensing. The focus of the project is to develop an operational platform using satellite Interferometric Synthetic Aperture Radar (InSAR) to assess health and stability of infrastructure in near-real time. As the increasing amount of available Sentinel-1 images from the Copernicus program comes with computational challenges for the creation and processing of large interferometric stacks, we implement our development on a cloud computing platform ”CODE-DE” provided by the DLR. CODE-DE comes with both all Sentinel-1 images for whole Germany and the required computational power that enable big data applications in remote sensing. In the implementation, we focus on open-source software to make online deformation monitoring affordable for the German land surveying authorities. Here, we present our first results for mapping  and monitoring of deformation using CODE-DE and discuss example applications for infrastructure in northeast Germany.
A mantle plume origin for the Scandinavian Dyke Complex: a “piercing point” for 615 Ma plate reconstruction of Baltica?
Authors: Tegner Christian , Andersen Torgeir B. , Kjøll Hans Jørgen , Brown Eric L. , Hagen-Peter Graham , Corfu Fernando , Planke Sverre , Torsvik Trond H.
Published: March 2021

The origin of Large Igneous Provinces (LIPs) associated with continental breakup and the reconstruction of continents older than c. 320 million years (pre-Pangea) are contentious research problems. Here we study the petrology of a 615 - 590 Myr dolerite dyke complex that intruded rift-basins of the magma-rich margin of Baltica and now is exposed in the Scandinavian Caledonides. These dykes are part of the Central Iapetus Magmatic Province (CIMP), a LIP emplaced in Baltica and Laurentia during opening of the Iapetus Ocean within the Caledonian Wilson Cycle. The >1000 km long dyke complex displays lateral geochemical zonation from enriched to depleted basaltic compositions from south to north. Geochemical modelling of major and trace elements shows these compositions are best explained by melting hot mantle 75-250°C above ambient mantle. Although the trace element modelling solutions are non-unique, the best explanation involves melting a laterally zoned mantle plume with enriched and depleted peridotite lithologies, similar to present-day Iceland and to the North Atlantic Igneous Province. The origin of CIMP appears to have involved several mantle plumes. This is best explained if rifting and breakup magmatism coincided with plume generation zones at the margins of a Large Low Shear-wave Velocity Province (LLSVP) at the core mantle boundary. If the LLSVPs are quasi-stationary back in time as suggested in recent geodynamic models, the CIMP provides a guide for reconstructing the paleogeography of Baltica and Laurentia 615 million years ago to the LLSVP now positioned under the Pacific Ocean. Our results provide a stimulus for using LIPs as piercing points for plate reconstructions.
High resolution numerical investigation of the indirect effects of aerosols on orographic precipitation
Authors: napoli anna , pasquero claudia , parodi antonio
Published: March 2021

Mountains play a key role for humanity providing freshwater for the areas downstream. The amount of precipitation at a given location is significantly affected by orography. Since changes of rainfall are expected in the changing climate, understanding how orographic precipitation responds to global warming and to anthropogenic forcing is becoming particularly pressing. To better understand the physical processes at play, in this study we investigate the indirect effects of aerosols on precipitation using the Weather Research Forecasting (WRF) Model: sentivity experiments are run with different numbers of water-friendly and ice-friendly aerosols in the atmospheric boundary layer.  5-years long simulations at high spatial resolution (4Km) have been run in the Great Alpine Region, where orographic lifting plays an important role and precipitation has a large spatial variability due to the complex orography. Results indicate that the indirect effects of aerosols modify cloudiness and precipitation in different ways among the flatlands (Po Valley) and the mountain areas. Physical mechanism at the base of those differences are discussed.
Study of the accuracy of monthly time-variable satellites gravity field estimates
Authors: Lecomte Hugo , Rosat Severine , Mandea Mioara
Published: March 2021

The GRACE and GRACE Follow-On (GRACE-FO) missions have been providing monthly time-variable gravity field estimates since 2002 with a one-year gap between 2017 and 2018. The Level 2 data products are available through several processing centers with independent computation strategies. The Center of Space Research (CSR), the German Research Centre for Geosciences (GFZ) and the Jet Propulsion Laboratory (JPL) as part of the GRACE/GRACE-FO Science Data System (SDS) process gravity data with RL06 standards. The French National Centre for Space Studies (CNES) and the Graz University of Technology delivered GRACE gravity fields models respectively named CNES/GRGS RL05 and ITSG-GRACE2018. Besides GRACE data, the European Space Agency (ESA) delivers Level 2 data products for the Swarm mission. Swarm data enables the evaluation of gap-filling methods between the GRACE and GRACE-FO missions. These datasets are very valuable inputs in studying the Earth's deep interior and could open new windows into the study of core-mantle boundary processes and core dynamics.

 

Earth's core dynamical processes inferred from geomagnetic field measurements are characterized by large-scale patterns. Studying them via gravity field observations involves the use of spherical harmonic coefficients up to degree and order 10. Particular attention needs to be dedicated to Stokes coefficients that are affected by problematic reconstruction effects such as C2,0 or C3,0. The comparison of time-series from various processing centers with Satellite-Laser Ranging (SLR) gravity products and hydrological loading models provides information on the consistency between different solutions and the accuracy of space gravity field measurements. The correction of hydrological and glacial isostatic adjustment (GIA) effects is an additional source of error in the determination of the gravity field. For example, the actual uncertainty of the GIA model over North America might lead to an error of 10% for some Stokes coefficients. Mismodelling in the seasonal loading could also affect the retrieved Stokes coefficients.

 

This study firstly provides a comparison of existing gravity field solutions and their accuracy. Secondly, a detailed analysis of different error sources provides us with better estimates of the current limits in the determination of elusive signals coming from the deep Earth's interior. It also offers the possibility to better describe the external sources and then to minimize their contribution to the signal we are interested in.
Exploring the 36Cl/Cl input in arid environments: New insights gained by 81Kr groundwater dating in the Negev Desert, Israel
Authors: Ram Roi , Purtschert Roland , Vockenhuber Christof , Yokochi Reika , Adar Eilon M. , Zappala Jake C. , Yechieli Yoseph , Lu Zheng-Tian , Mueller Peter , Bishof Michael , Jiang Wei , Sy Adrien , Burg Avihu
Published: March 2021

   36Cl and 81Kr (half-lives of 301 and 229 kyr, respectively) are among a very few age tracers with dating capabilities in the 104–106 yr timescale. Although widely applied since the 1980s in various hydrological studies, the 36Cl/Cl system has been found complex as an effective dating tool. In contrast, 81Kr has become a practical tool only recently and is considered to be an ideal dating tool due to the inert properties of the noble gas. In the present study, simultaneous measurements of both radioisotopes were used to assess the 36Cl/Cl input ratios and the Cl- content for paleorecharge into the deep, transboundary Nubian Sandstone Aquifer (NSA) which stretches below the hyperarid deserts of the Sinai Peninsula (Egypt) and the Negev (Israel).

   By means of 81Kr data, reconstructed Cl- content of recharge that occurred during the late Pleistocene was found to be 300–400 mg/L with an initial 36Cl/Cl ratio of 50 × 10-15. This latter value is in agreement with the 36Cl/Cl ratio in recent local rainwater, indicating constancy over prolonged periods with possible variable climatic conditions. This similarity in values suggests a process that is rather insensitive to atmospheric 36Cl fallout rates. Erosion and weathering of near-surface materials in the desert environment could dominate the hydrochemistry of rains, floods, and the consequent groundwater recharge. This near-surface Cl- reservoir integrates various sources and processes, including marine and terrestrial Cl-, cosmogenic 36Cl fallout, and cosmogenic 36Cl production in the shallow unsaturated zone, all of which are active over long timescales and accumulate on the land surface and in the epigene zone.  Spatial differences in the reconstructed initial 36Cl/Cl ratio are attributed to differences in the mineral aerosol sources for specific recharge areas of the NSA. The results of this study highlight the potential of integrating 81Kr age information in evaluating the initial 36Cl/Cl and Cl- input, which is essential for the calibration of 36Cl radioisotope as a long-term dating tool for a given basin.
​Slip modes and interaction in a simplified strike-slip fault system with increasing geometrical complexity
Authors: Rudolf Michael , Podlesny Joscha , Heckenbach Esther , Rosenau Matthias , Glerum Anne , Kornhuber Ralf , Brune Sascha , Oncken Onno
Published: March 2021

The release of elastic energy along an active fault is accommodated by a wide range of slip modes. It ranges from long-term slow slip events (SSEs) and creep to short-term tremors and earthquakes. They vary not only in their characteristic duration but also in their magnitude, spatial extent and slip velocities. The exact relationship is unclear, as in some regions many slip modes occur simultaneously (e.g. Tohoku-Oki) and in others certain slip modes are completely absent (e.g. Cascadia).

One of the driving factors in the generation of this large variety of slip modes is the interplay of fault heterogeneity and geometrical complexity of the fault system. We test various settings in terms of fault heterogeneity and geometrical complexity with a scaled physical model. The experimental results are then validated and benchmarked through multi-scale numerical simulations. We describe the system using a rate-and-state frictional framework and introduce on-fault heterogeneity with variable frictional properties. All properties are the same for analogue and numerical simulation as far as they can be determined or realized experimentally (a-b, vload, Shmax, Shmin, etc...). As analogue material we use segmented, decimetre sized neoprene foam blocks in multiple configurations (e.g. biaxial shear at forces <1 kN) to simulate the elastic upper crust. The contact surfaces are spray-painted with acrylic paint to generate velocity weakening characteristics in between the blocks which is similar to the frictional behaviour of natural faults. We add heterogeneity to the fault surface by varying the fault area that is velocity weakening using grease. Geometrical complexity is implemented using conjugated or parallel sets of additional faults with the same characteristics.

We are able to reliably generate frequent stick-slip events of variable size and recurrence intervals. The slip characteristics, such as slip distribution, are in good agreement with analytical solutions of fault slip in elastic media. In a geometrically simple strike-slip model the recurrence behaviour and magnitude follows straightforward scaling relations in accordance with existing studies. If geometrical complexity is added to the model we observe clustering and variable recurrence that differ from the simpler geometry. Additionally, we are going to give an outlook on the interaction behaviour of multiple faults in dependence of their geometric configuration and the generation of power-law type magnitude scaling relations.
Improving assessment of flood inundation of Navsari (India) via open-source data and HEC-RAS model
Authors: Pathan Azazkhan Ibrahimkhan , Agnihotri Dr.Prasit Girishbhai , Patel Dr. Dhruvesh , Prieto Dr. Critina
Published: March 2021

Flooding seems to be the most widespread and common catastrophe in a tropical country such as India. Efficient rainfall, industrial development, huge population, the effect of the tide, and urban growth are actual reasons for flooding in urban coastal regions. Navsari, the city of Gujarat, located 19 km upstream of the Arabian Sea. The city has experienced a devastating flood on 4rth August 2004. Flash flooding and maximum discharge estimated at the Mahuva gauge station of about 8836 m3/sec were responsible for a disaster that resulted in massive damage to property and lives. A two dimensional (2D) flood simulation model is carried out to assessment of flood inundation in an urban coastal area. HEC-RAS is one of the most popular open-source hydraulic software having 2D capabilities including GIS features. In the present study, the distance between the Mahuva gauge station to the Arabian sea was considered for flood inundation assessment, whereas the SRTM 30 m DEM was used for grid generation for Navsari city. The inflow hydrograph was used as the upstream boundary condition, and normal depth was used as the downstream boundary condition during the 4th August 2004 flood event. The unsteady flow simulation was performed and validated for the year of 2004 flood event. The simulated outcomes show that major areas such as Viraval, Kachiawad, Jalalpore, near Railway station, Kaliawad, Tavdi village, and Near TATA School were flooded with 2-4 m depth. Furthermore, the simulated result demonstrates that, if the discharge exceeds 8836 m3/sec in the area of a floodplain, it may take 11 to 13 hours to make the city inundated. The R2 value for the model is 0.9679, which shows that the observed value is the best match with the simulated value. The research study illustrates the accurate flood inundation assessment in the urban coastal area using open-source 2D HEC-RAS model. The present study described the applicability of open-source data and model in flood inundation assessment. The study will fill the gap of flood assessment through 2D HEC-RAS model worldwide areas, which are situated nearby coastal region, accompanied by the benefits of open-source dataset and model.