bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuously operating reference stations in Russia: current state and future enhancements
Authors: Mazurova Elena , Stoliarov Igor , Gorobets Vladimir
Published: March 2020

     At the present time the Russian  state geodetic reference frame of the new generation consists of the three hierarchical levels that include: 1. fundamental astronomical-geodetic reference frame ; 2. high-precision geodetic reference frame; 3. satellite-based geodetic reference frame of the first category.  The spatial coordinates of the networks of these three levels are determined by satellite methods.   However, only the points of the fundamental astronomical-geodetic reference frame are continuously operating reference stations.  Many surveying engineers, geodesists, map-ping specialists, as well as scientists from different backgrounds, are using RINEX files every day freely downloading them from the site //rgs.centre.ru

    At the same time, private networks of Continuously operating reference stations are developing rapidly in Russia. These networks are owned by various corporations, both private and public, as well as stations owned by private individuals.  Now,  a center is being created, the main task of which is to unite all Continuously operating reference stations located on the territory of Russia into a unified network.

    This paper addresses the current state of the Continuously operating reference stations network  in Russia and plans for enhancing it within the next few years.

Key words: Russian continuously operating reference stations network
Can Swarm and SLR contribute to closing the global sea level budget?
Authors: Lück Christina , Uebbing Bernd , Löcher Anno , Rietbroek Roelof , Kusche Jürgen , Androsov Alexey , Schröter Jens , Danilov Sergey , Yakhontova Alisa
Published: March 2020

Sea level change is an important indicator of global warming. In order to predict future sea level changes, it becomes more and more important to understand the complex contribution of different components (steric changes, melting of ice sheets and glaciers, hydrology,…) to the total sea level change on global and regional scales.

To distinguish between steric and mass-related sea level changes, we consider (1) satellite altimetry, which measures total sea level change, and (2) Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) data to derive mass changes within the Earth system. The information of both methods can be combined in a joint inversion approach to derive the individual components of sea level change. However, there is a gap of 11 months between GRACE and GRACE-FO and there are numerous (bi-)monthly gaps since 2011, which means that there is no dedicated gravity field mission to derive ocean mass changes during these times.

In this contribution, we use time-variable gravity field data from the Swarm satellite mission and Satellite Laser Ranging (SLR) as an additional source of information on mass changes within the inversion approach. Thus, we are able to derive inversion results even in times without GRACE(-FO), albeit at the expense of an inevitably lower spatial resolution. We compare results with GRACE(-FO) data to those without GRACE(-FO) data. Furthermore, we quantify the leverage of Swarm and SLR on the low-resolution mass signal at basin scale in the combined inversion approach during the GRACE(-FO) lifetime.
A performance assessment method for SAR satellite-derived surface soil moisture data using a soil-water balance model, meteorological observations, and soil pedotransfer functions.
Authors: Beale John , Waine Toby , Corstanje Ronald , Evans Jonathan
Published: March 2020

The validation of surface soil moisture products derived from SAR satellites data is challenged by the difficulty of reliably measuring in-situ soil moisture at shallow soil depths of a few centimetres, consistent with the penetration depth of the microwave beam. Our analysis shows that the apparent accuracy of the remote sensing products is underestimated by comparison with inconsistent probe data or measurements at greater soil depths. Our alternative approach uses in-situ meteorological measurements to determine rainfall and potential evapotranspiration, to be used with soil hydrological properties as inputs to a water balance model to estimate surface soil moisture independently of the satellite data. In-situ soil moisture measurements are used to validate and refine the model parameters. The choice of appropriate soil hydrological parameters with which to convert remotely sensed surface soil moisture indices to volumetric moisture content is shown to have a significant impact on the bias and offset in the regression analysis. To illustrate this, Copernicus SSM data is analysed by this method for a number of COSMOS-UK soil moisture monitoring sites, showing a significant improvement in the coefficient of determination, bias and offset over regression analysis using in-situ measurements from soil moisture probes or the cosmic ray soil moisture sensor itself. This will benefit users of such products in agriculture, for example, in determining actual soil moisture deficit.
Experiments of determining the geopotential difference using two hydrogen atomic clocks and two-way satellite time and frequency transfer technique
Authors: Ning An , Wu Kuangchao , Shen Wen-Bin , Shen Ziyu , Cai Chenghui , Sun Xiao
Published: March 2020

Abstract In this study, we carried out experiments of the geopotential difference determination at CASIC, Beijing with the help of two hydrogen atomic clocks, using the two-way satellite time and frequency transfe technique. Here the ensemble empirical mode decomposition method is adopted to extract geopotential-related time-elapse signals from the original observations. The clock-comparison-determined geopotential difference in the experiments is determined, which is compared to the previously known results determined by conventional approach. Results show that the geopotential difference determined by time comparison deviates from that determined by conventional approach by about 1589 m2s-2, which is equivalent to 162 m in height, in consistence with the stability of the hydrogen atomic clocks applied in the experiments (at the level of 10-15/day). Since the stability of the optical clocks achieve 10-18 level, the geopotential determination by accurate clocks is prospective, and it is prospective to realize the unification of the world vertical height system. This study is supported by NSFCs (grant Nos. 41721003, 41631072, 41874023, 41804012, 41429401, 41574007) and Natural Science Foundation of Hubei Province of China (grant No. 2019CFB611).
Peninsular Thailand as a part of the Pleistocene savanna corridor: isotopic evidence of mammalian tooth enamel from the cave of Tham Phedan
Authors: Suraprasit Kantapon , Bocherens Hervé
Published: March 2020

How climatic and environmental conditions contributed to early human migration between mainland and island Southeast Asia during the Pleistocene is one of the most hotly debated topics in paleoanthropological communities today. As Peninsular or Southern Thailand is regarded as an obligatory pathway for humans and mammals during their dispersal between these two terrestrial areas, the understanding of paleoenvironments and vegetation covers in this region is highly relevant. The hypothesis of a “savanna corridor” or a band of open vegetation (seasonal forests and grasslands) stretching from Central Thailand to Java during several periods of lowering sea level and exposed land bridges though the Pleistocene has been suggested for explaining the facilitated route of early humans and associated large mammals in migrating out of mainland Southeast Asia towards Sundaland southwards. However, the existence of savanna grasslands in Peninsular Thailand during the Pleistocene has rarely been demonstrated due to the scarcity of available proxies.

Here we reconstructed the Pleistocene vegetation and environments of the region using stable isotope analyses of mammalian tooth enamel from the channel cave deposits of Tham Phadan (Nakhon Si Thammarat Province in Peninsular Thailand) where diversified large mammal fossils were collected. The mammal fauna is tentatively attributed to a late Middle to early Late Pleistocene age according to the presence of an extirpated spotted hyaena Crocuta crocuta ultima. The stable carbon isotope results, ranging from -13.9‰VPDB to +4.3‰VPDB, reveal that an open vegetation/forest-grassland mosaic was dominant in this region, unlike the present-day landscapes that are mostly covered by rainforests, thus confirming the existence of a savanna corridor in Peninsular Thailand during that time. The extreme southward distribution of some grassland-related taxa (such as spotted hyaenas and Himalayan gorals), which were common in mainland Southeast Asia during the Pleistocene, reflects the habitat continuity from north to south of Thailand. However, the lack of fossil records of these two taxa in Peninsular Malaysia and the islands of Indonesia suggests that the open vegetation band did not extend far beyond the transequatorial region. Further investigations of the Pleistocene mammal faunas in the Thai-Malay Peninsula will be helpful to identify such a corridor and to examine the paleobiogeographic affinities of Southeast Asian large mammals in the future, providing empirical data for understanding the timing and pathways of human migrations into island South-East Asia.
Comparison of the surface velocity of a debris flow at the Gadria creek using pulse compression radar and digital particle image velocimetry (DPIV).
Authors: Schöffl Tobias , Nagl Georg , Hübl Johannes
Published: March 2020

Comparison of the surface velocity of a debris flow at the Gadria creek using pulse compression radar and digital particle image velocimetry (DPIV).

 

Tobias Schöffl, Georg Nagl, Johannes Hübl

Institute of Mountain Risk Engineering, University of Natural Resources and Life Sciences, Vienna, Austria

 

A central aspect of protection against debris flows is the understanding of the process. The flow velocity is an important parameter which is used, for example, in the dimensioning of protective structures, for technical building protection and for early warning systems. The measurement of the surface velocity which is regarded as the maximum velocity occurring within a debris flow, is therefore an essential link in the chain of fundamental process research and applied protection against natural hazards.

Due to the further development of various technologies such as video technology and high-frequency radar technology, the non-contact measurement of the surface speed of a debris flow has improved significantly in recent years. Radar technology provides a wide aspect of applications in alpine mass movements such as debris flows, avalanches and rockfall and is able to detect such processes up to a range of 2500 meters in distance. An additional beneficial feature is the possibility of non-contact measurement of the surface velocity. In the catchment area of the Gadria basin (South Tyrol, Italy), the measuring station, which has been in operation since 2016, has been extended by a pulse compression radar and a new HD video camera. On July 26, 2019 a debris flow consisting of several surges was recorded with both the radar and the HD video camera. To obtain surface velocity data from the video material, the material was analyzed and evaluated using digital particle image velocimetry by making use of the MATLAB software and its freely accessible ADD-On "PIVlab".

The results of the compared surface velocity data showed a value of up to 0.74 according to the statistical mean of the coefficient of determination. The results demonstrate the high effectiveness of the pulse compression radar and the DPIV analysis in a wide range of the assessment of surface velocity of natural debris flows. There is great potential in both measuring systems and the chosen comparative analysis provides a blueprint for future recorded debris flows.
Towards robust optimization of cascade operation of reservoirs considering streamflow uncertainty
Authors: He Shaokun , Solomatine Dimitri , Marquez-Calvo Oscar , Guo Shenglian
Published: March 2020

Abstract: Modern water resource management requires a more robust flood control operation of cascade reservoirs to cope with a more dynamic external environment, whose ultimate goal is to ensure the robust optimization for multiple purposes. To this end, a number of studies with the theme of flood control operation have developed various methods for robust optimization in the presence of uncertainties and in some cases, they may work well. However, these approaches usually incorporate uncertainty into the flood control objectives or constraints and consequently lack explicit robustness indicators that can assist the decision-makers to fully assess the impact of the uncertainty. In order to construct a mature framework of explicit robust optimization of flood control operation, this study uses the Robust Optimization and Probabilistic Analysis of Robustness (ROPAR) technique to identify the robust flood limited water levels of cascade reservoirs for satisfactory compromise hydropower production and flood control risk taking into account the streamflow variability during the flood season: (1) The Monte Carlo method is employed to sample the input set according to the historical streamflow records; (2) The effective non-dominated sorting genetic algorithm II algorithm (NSGA-II) generates a series of Pareto fronts for each hydrograph sample; (3) the ROPAR technique helps building the empirical distribution of the values of hydropower production corresponding to the chosen levels of flood control risk and carry out probabilistic analysis of the Pareto fronts; (4) the ROPAR technique identifies the final robust solutions according to certain criteria. A reservoirs cascade in the Yangtze River basin, China, is considered as a case study. The presented approach allows for studying propagation of uncertainty from the uncertain inflow to the candidate optimal solutions, and selecting the most robust solution, thus better informing decisions related to reservoir operation.

Key words：multi-objective reservoir system, robust optimization, uncertainty, flood control operation, Yangtze River basin

Reference:

Marquez-Calvo, O.O., Solomatine, D.P., 2019. Approach to robust multi-objective optimization and probabilistic analysis: the ROPAR algorithm. J Hydroinform, 21(3): 427-440. DOI:10.2166/hydro.2019.095
Electron irradiation of water ice samples in the laboratory - Implications for icy moons and comets
Authors: Galli André , Cerubini Romain , Pommerol Antoine , Wurz Peter , Vorburger Audrey , Rubin Martin , Oza Apurva , Tulej Marek , Thomas Nicolas , Ligterink Niels F.W.
Published: March 2020

The surfaces of icy bodies in the solar system are continuously irradiated by charged particles from planetary magnetospheres or from the solar wind. This irradiation induces chemical reactions in the surface ice and also acts as an atmospheric release process. Remote observations, theoretical modelling, and laboratory experiments must be combined to understand this plasma-ice interaction. In this presentation, we concentrate on laboratory experiments with electron irradiation (energy range of 0.1 to 10 keV) of water ice. The samples include thin ice films on a microbalance as well as thick layers of porous ice, resembling regolith. The physical and optical properties of the latter make them realistic analogues for the surfaces of icy moons.

We measure the sputtering yield and monitor the irradiation-induced alterations in the ice samples with a dedicated new time-of-flight mass spectrometer.
Previous results obtained with an earlier quadrupole mass spectrometer (Galli et al. 2018, Planetary and Space Sciences) indicated that most water escaping the ice sample upon electron irradiation does so in the form of the radiolysis products H2 and O2. The freshly produced H2 appeared to leave the porous water ice sample immediately whereas the O2 escape slowly increased until reaching a steady-state ratio of 1:2 of O2 to H2. With the new mass spectrometer, we investigate the release and storage of radiolysis products at a higher temporal resolution and sensitivity for a variety of ice sample porosities and thicknesses. We pay special attention to less abundant radiolysis products such as H2O2 and to the O2/H2O ratio in the irradiated water ice layer.
Separation of the daily quiet variation from the geomagnetic field observations with the principal component analysis
Authors: Morozova Anna , Rebbah Rania , Pais M. Alexandra
Published: March 2020

Geomagnetic field (GMF) variations from external sources are classified as regular diurnal or occurring during periods of disturbances. The most significant regular variations are the quiet solar daily variation (Sq) and the disturbance daily variation (SD). These variations have well recognized daily cycles and need to be accounted for before the analysis of the disturbed field. Preliminary analysis of the GMF variations shows that the principal component analysis (PCA) is a useful tool for extraction of regular variations of GMF; however the requirements to the data set length, geomagnetic activity level etc. need to be established.

Here we present preliminary results of the PCA-based Sq extraction procedure based on the analysis of the Coimbra Geomagnetic Observatory (COI) measurements of the geomagnetic field components H, X, Y and Z between 2007 and 2015. The PCA-based Sq curves are compared with the standard ones obtained using 5 IQD per month. PCA was applied to data sets of different length: either 1 month-long data set for one of 2007-2015 years or data series for the same month but from different years (2007-2015) combined together. For most of the analyzed years the first PCA mode (PC1) was identified as SD variation and the second mode (PC2) was identified as Sq variation.
OpenPlanetaryMap Updates: Planetary Basemaps and Geocoding Web Services
Authors: Manaud Nicolas , Gasperi Jérôme , Nass Andrea , van Gasselt Stephan , Pio Rossi Angelo , Hare Trent
Published: March 2020

OpenPlanetaryMap (OPM) is a collaborative project to build the first Open Planetary Mapping and Social platform for researchers, educators, storytellers, and the general public. We want to make it easy for anyone to create and share maps and locations on any planets or bodies in our Solar System [1].

Our platform architecture is based on four main service-oriented components: (1) an open repository of geospatial datasets; containing information used to create basemaps and to enable location-based searches, (2) basemaps that are needed to build any types of web mapping applications or geospatial data visualisation, (3) geocoding and geo-referencing APIs/web services to enable location-based searches and crowdsourcing of our datasets repository, (4) Web app, Python module and CLI interfaces to search, add and share places on planetary bodies.

Since the project started as an initiative funded by Europlanet in 2017, we have consolidated our network of collaborators and we published our first planetary basemaps and design concept [2]. Instructions on how to use our basemaps are available from our new website [3]. External projects have started to use OPM basemaps, for example: PLANMAP Stories [4] and CaSSIS Map Interface [5]. While we continue to improve our basemaps and create new ones, we have been working on providing an open planetary geocoding API/web service and user interfaces.

The purpose of our planetary geocoding API is to provide a common and consistent way of defining and searching for places on the surface of bodies in the Solar System, including the Earth. We are first implementing our geocoding API as a JavaScript module, along with our first web map interface that demonstrates its use. We will then focus on implementing our geocoding API as a Python module.

We introduce the project and present recent updates on OPM planetary basemaps, geocoding APIs and user interfaces.

[1] Manaud et al. (2018). OpenPlanetaryMap: Building the first Open Planetary Mapping and Social platform for researchers, educators, storytellers, and the general public. European Planetary Science Congress 2018, 12, EPSC2018-78. [2] Nass et al. (2019). Towards a new face for Planetary Maps: Design and web- based Implementation of Planetary Basemaps. Adv. Cartogr. GIScience Int. Cartogr. Assoc., 1, 15, 2019. https://doi.org/10.5194/ica-adv-1-15-2019 [3] http://openplanetarymap.org [4] https://stories.planmap.eu/mars/gale [5] http://cassis.halimede.unibe.ch
Periodic imbalances of kinetic and magnetic energies in rotating magnetohydrodynamic turbulent flows
Authors: Sirazov Rustem , Petrosyan Arakel
Published: March 2020

A significant number of observed flows in geophysics, astrophysics, and laboratory experiments are in a state of magnetohydrodynamic turbulence. Among them are flows in the Earth’s outer core, in plasma shells of Earth, planets, and satellites of the solar system with strong magnetic fields, as well as flows in the Sun, stars, and astrophysical disks. Despite significant advances in the study of turbulence under the conditions typical of thermonuclear fusion devices, studies of the fundamental properties of homogeneous turbulence in rotating magnetohydrodynamic flows are still fragmentary and mainly concern turbulence in astrophysical disks, the solar tachocline and convective region of the Sun, and two-dimensional magnetohydrodynamic flows on the β-plane. Only in a few exceptional works were the properties of magnetohydrodynamic turbulence studied by simple analytical methods using Fourier series for similarity parameters, characteristic of the Earth’s core.

The aim of this work is to study the influence of the interaction of Alfvén wave packets on the dynamics of homogeneous turbulence. The method of calculation o magnetohydrodynamic turbulence we developed allows numerical simulation at large characteristic times and large external magnetic fields. The proposed method of setting the initial conditions for the velocity field makes it possible to satisfy the divergence-free, homogeneity, and turbulence isotropy conditions, as well as to set an arbitrary spectral distribution of the energy at the initial time without additional calculations. Numerical experiments demonstrate a nontrivial behavior of turbulent kinetic and magnetic energies. It is shown that periodic imbalance in energies occurs in the system in the form of conversion of kinetic energy into magnetic energy and vice versa. The analysis of the results shows that the detected nontrivial temporal dynamics of turbulence is caused by the periodic collisions of Alfvén wave packets.

This work was supported by the Russian Foundation for Basic Research (project no. 19-02-00016).
Quantitatively deciphering paleostrain from digital outcrops model and its application in the eastern Tian Shan, China
Authors: Wang Xin , Gao Feng
Published: March 2020

The knowledge of the strain/stress field evolution in time is important to seismic hazard assessment and risk mitigation, and is fundamental to the understanding of the earth dynamic system. Based on the principle that past tectonic stress should have left traces in the rocks, geologists have been trying to determine the paleostress history from evidence found in rocks for decades. Recent development of techniques for automatic extraction of fracture surfaces from digital outcrop models and estimation of historical shear deformation on rock fractures provide an efficient way of quantitatively acquiring large amount of high quality fracture/fault slip data (direction and sense of slip occurs on the fault plane) from outcrops. So unlike traditional paleostress inversion methods whose data is manually collected in the field, this high quality fracture/fault slip data provide an opportunity to develop fully automatic and quantitative methods for deciphering paleostrain. In this study, for slip on each fracture, the corresponding local strain tensor is calculated, then the local strain tensors are grouped into populations corresponding to far-field strain events and local strain events using a clustering analysis technique. The applications on outcrops in the eastern Tian Shan area give a clear picture of the paleostrain variation over space and time, and also throw light on the relationship between paleostrain, fracture development and the distribution of shear displacements in a thrusting environment.
Investigating spatio-temporal variability of soil moisture in a small farmland: from point to catchment scale
Authors: Li Tailin , Noreika Nina , Jeřábek Jakub , Krasa Josef , Zumr David , Dostál Tomáš
Published: March 2020

Many studies in recent years have focused on spatio-temporal variability of soil moisture and its value in hydrology and agriculture. The highly dynamic of soil moisture is controlled by soil properties, topography, landuse, climate conditions, and anthropogenic impacts. However, the understanding of soil moisture dynamics is limited by measurement restrictions. The aim of this study is to analyse spatio-temporal patterns of soil moisture using various soil moisture monitoring techniques and numerical modelling approaches that have been developed for application at differing scales at the Nucice experimental catchment (0.53 km2), which is located just outside of Prague, the Czech Republic.

The experimental catchment is dominated by agricultural activities. To identify spatio-temporal patterns in the catchment, we have implemented shallow soil moisture measurements at point-scale, hillslope-scale, and catchment-scale. We have deployed FDR (frequency domain reflectometry) sensors at different depths for point-scale measurements. The monitoring of hillslope-scale and catchment-scale have been mostly accomplished by field surveys with HydroSense II sensors. Subsequently, we have applied geostatistical analyses (Kriging and inverse distance weighting interpolation) for the measured soil moisture data to discover spatial patterns in soil moisture across the catchment. Besides, numerical models Hydrus (1D and 2D), MIKE-SHE, and SWAT have been set up at this study site. These models have been calibrated with event-based data and soil moisture measurements, which present a better image of the hydrological processes and spatio-temporal dynamics of soil moisture at various scales. The modelling outcomes have not only fit agreeably with the observed discharge and the temporal dynamics of soil moisture but have also identified wet zones along hillslopes.

Further research will intensify the soil moisture monitoring at the catchment-scale by using remote sensing and Comsic-ray soil moisture probes. Also, anthropogenic impacts (e.g. influence of wheel track) should be considered in the modelling approach. Ultimately, we should be able to understand and predict the spatio-temporal dynamics of soil moisture in small scale agricultural catchments under different climate conditions.

This research has been supported by project H2020 No. 773903 SHui, focused on water scarcity in European and Chinese cropping systems.
Nanoscale compositional segregation in complex In-bearing sulfides: Results from atom probe tomography and transmission kikuchi diffraction
Authors: Krause Joachim , Reddy Steven M. , Rickard William D. A. , Saxey David W. , Fougerouse Denis , Bauer Matthias E.
Published: March 2020

Indium-bearing sphalerites from the Hämmerlein skarn deposit, located in the western Erzgebirge (Germany), show complex distribution patterns of major and minor elements on a micrometer to sub-micrometer scale. However, with the spatial resolution of traditional analytical methods, such as SEM-based image analysis and field emission electron probe microanalysis (FE-EPMA), many features in these spalerites cannot be resolved. It remains unclear whether Cu, In and Fe are in solid solution in the sphalerite, are concentrated in nanoparticles or form discrete phases.

Atom probe tomography combined with transmission kikuchi diffraction has been used to resolve both the compositional heterogeneity and the nanostructure of these complex In-Cu-Fe-sphalerites. The obtained data indicate a complex structure with micro- to nanometer sized, plate-shaped inclusions of chalcopyrite in the sphalerite. In addition, a nanometer scale In-Cu-sulfide phase forms plate-like segregations in the sphalerite. All types of segregations have similar crystal structure and record the same crystal orientation indicating that they likely formed by exsolution.

The results indicate that complex sulfides containing cations of more than one element as minor or major constituents may represent discrete, exsolved phases, rather than solid solutions or being concentrated in nanoparticles. This heterogeneous nature will affect the nanoscale properties of the sphalerite, which may have implications for the economic extraction of precious elements such as In, when processing these minerals for beneficiation. Furthermore these nanoscale properties will open up new perspectives on formation processes of In-Cu-Fe-sphalerites, which might be relevant for other chemically complex minerals as well.

 
Thermal remote sensing data enhancement over Alpine Vegetated Areas for evapotranspiration modelling
Authors: Bartkowiak Paulina , Castelli Mariapina , Colombo Roberto , Notarnicola Claudia
Published: March 2020

The main objective of this study is to exploit thermal remote sensing data for evapotranspiration (ET) modelling in the European Alps. This geographic region has been noted as a hot spot of climate change triggered by increasing number of drought events in recent years, with impacts on natural and agricultural vegetation. Evapotranspiration is considered as one of the major indicators for examining water anomalies in plants. The state-of-art ET models exploiting thermal remote sensing data have shown a large potential in water cycle monitoring. However, existing satellite-derived products do not provide adequate spatial resolution for mountain ecosystems affected by complex orography, common overcast and land-cover heterogeneity. Even though fine resolution imagery fills the gap regarding non-homogenous areas, its long revisit time and frequent cloud contamination hamper spatially continuous ET modelling. In this context, our aim is to overcome these limitations by downscaling and gap-filling 1-km MODIS LST (MOD11A1) to retrieve daily LST maps at 250 m spatial resolution, which can be considered a reasonable scale in the selected area. Firstly, we downscale MODIS LST images with the Random Forest (RF) algorithm by exploiting the relationship between coarse resolution MODIS LST and 250-m explanatory variables, including digital elevation model and normalized difference vegetation index. The 1-km MODIS LST and the downscaled product were compared with fine resolution Landsat LST images. The random forest results show an improvement of about 20% in the agreement between Landsat and 250-m MODIS LST compared to statistics obtained for MOD11A1. Secondly, we propose to recover missing values of LST pixels beneath the clouds. Considering local-scale climate variability of the study area, we present a novel approach based on investigating the relationships between LST and meteorological data under clear- and cloudy-sky conditions. The abovementioned improvements are planned to be used for energy balance modelling of ET with relevant implications on water availability assessment in the Alpine region.
BigData@Geo: A Climate Atlas for Lower Franconia (Germany)
Authors: Schönbein Daniel , Keupp Luzia , Pollinger Felix , Paeth Heiko
Published: March 2020

Within the frame of BigData@Geo, a collaborative EFRE-funded project between the University of Würzburg and several medium-sized companies in regional pomi- and viticulture, a webportal similar to a climate-atlas is built. An Ensemble of six RCM/GCM-Couples from EURO-CORDEX with EUR-11 resolution is therefore retrieved. After a Nearest-Neighbour-Remap onto a 1x1km-grid within Lower Franconia (Bavaria, Germany), a linear bias-correction of air-temperature and precipitation is executed. The applied method calibrates mean seasonal cycles for the reference period 1970-1999 using gridded observation data from the German Weather Service. Subsequently, climatic tendecies of seasonal temperature and precipitation as well as various derived indizes (e.g. frostdays, hot days, tropical nights, vegetation period, huglin index) are evaluated along emission pathways rcp45 and rcp85 during the 21st century.
Analyzing topographic changes through LiDAR and SfM techniques: assessing the deposition-erosion patterns and estimation of debris-flow volume in the eastern Italian Alps
Authors: Chen Xuewei , Cucchiaro Sara , Bernard Martino , Mauri Luca , Chen Jianping , Tarolli Paolo , Gregoretti Carlo
Published: March 2020

On 4 August 2015, a very high intensity storm, 31.5 mm in 20 min (94.5 mm/h), hit the massif of Mount Antelao on the Venetian Dolomites (eastern Italian Alps) triggering stony debris flow characterized by high magnitude. It routed along the Ru Secco Creek and progressively reached the resort area and the village of San Vito di Cadore, causing fatalities and damages. The aim of the present research is the study of this debris-flow event by means of pre and post-event topographic data derived by LiDAR (Light Detection and Ranging) and Structure-from-Motion (SfM) photogrammetry technique associated to its occurrence. This study analyzes the Digital Terrain Models (DTMs) derived from LiDAR survey carried out in July 2015 and UAV-SfM data obtained in September 2019. The most important step to compare these multi-temporal surveys was the co-registration process, fundamental to guarantee the coherence among the two different surveys. The post-event SfM-DTM of the area routed by debris flow subtracted to the pre-event LiDAR-DTM, provided a DoD (DTM of Difference) that was useful to assess the deposition-erosion patterns and estimate debris-flow volume. Multi-temporal topographical data are important to analyze the phenomenon and its characteristics. This allowed us to more in depth analyzed the debris-flow effects and provide valuable information for the planning of risk prevention measures.
Analysis and nowcasting of deep convective systems over Germany in multi-source data
Authors: Zöbisch Isabella , Forster Caroline , Zinner Tobias , Wapler Kathrin
Published: March 2020

By using a multi-source data set consisting of high resolution satellite, radar, lightning, and model data this study presents the analysis of characteristics of deep convective systems over Germany and first results of a new model to predict the remaining lifetime of existing thunderstorms. Contrary to previous studies, the analysis was performed for the full mixture of observed convective systems regardless of their organization type, since our focus is an operational forecasting environment where no simple method is available to differentiate organization types. Basis for the study are all deep convective cell detections in satellite data (using Cb-TRAM, Thunderstorm Tracking and Monitoring) in a five month period (June 2016, May, June, and July 2017, and June 2018). The lifetimes of all cells are normalized, averaged and separated into life cycle phases to investigate the behavior of the parameters from the different data sources during the detected lifetime. Furthermore, the thunderstorm cells are sorted by their lifetime to determine differences between the characteristics of long- and short-lived convective systems. Parameters with predictive skill are then combined with fuzzy logic to determine the actual stage of a thunderstorm, and to nowcast its remaining lifetime. It will be shown that the new lifetime prediction model contributes to an improvement of the thunderstorm nowcasting.
Dark microbial CO2 fixation in temperate forest soils increases with CO2 concentration
Authors: Spohn Marie , Müller Karolin , Höschen Carmen , Müller Carsten W. , Marhan Sven
Published: March 2020

Dark, that is, nonphototrophic, microbial CO2 fixation occurs in a large range of soils.
However, it is still not known whether dark microbial CO2 fixation substantially contributes
to the C balance of soils and what factors control this process. Therefore,
the objective of this study was to quantitate dark microbial CO2 fixation in temperate
forest soils, to determine the relationship between the soil CO2 concentration and
dark microbial CO2 fixation, and to estimate the relative contribution of different
microbial groups to dark CO2 fixation. For this purpose, we conducted a 13C-CO2 labeling
experiment. We found that the rates of dark microbial CO2 fixation were positively
correlated with the CO2 concentration in all soils. Dark microbial CO2 fixation
amounted to up to 320 μg C kg−1 soil day−1 in the Ah horizon. The fixation rates were
2.8–8.9 times higher in the Ah horizon than in the Bw1 horizon. Although the rates of
dark microbial fixation were small compared to the respiration rate (1.2%–3.9% of the
respiration rate), our findings suggest that organic matter formed by microorganisms
from CO2 contributes to the soil organic matter pool, especially given that microbial
detritus is more stable in soil than plant detritus. Phospholipid fatty acid analyses
indicated that CO2 was mostly fixed by gram-positive bacteria, and not by fungi. In
conclusion, our study shows that the dark microbial CO2 fixation rate in temperate
forest soils increases in periods of high CO2 concentrations, that dark microbial CO2
fixation is mostly accomplished by gram-positive bacteria, and that dark microbial
CO2 fixation contributes to the formation of soil organic matter.

Reference

Spohn M, Müller K, Höschen C, Mueller CW, Marhan S. Dark microbial CO2 fixation in temperate forest soils increases with CO2 concentration.
Glob Change Biol. 2019;00:1–10. https ://doi.org/10.1111/gcb.14937
LANDSLIDE INCIDENCE ANALYSIS BY MEANS OF A-DInSAR OPEN ACCESS SERVICE AND LANDSLIDE DATABASE
Authors: Cuervas-Mons Jose , Domínguez-Cuesta María José , Mateos-Redondo Félix , Valenzuela Pablo
Published: March 2020

Landslides are one of the most common and dangerous threats in the world that generate considerable damage and economic losses. The aim of this study is to analyse the suitability of using the ESA G-POD (European Space Agency Grid Processing On Demand) environment to detect landslide incidence.

This free service allows to gain Mean Deformation Maps (mm/year and cm/year) by means of P-SBAS (Parallel-Small Baseline Subset) method, which is a kind of A-DInSAR (Advanced-Differential SAR Interferometry) technique.

The study area is in the Northwest of Spain, where there are and have been some significant well-known active landslides. ENVISAT ASAR satellite data collected from 2003 to 2010, have been contrasted with the slope instabilities inventory of Asturias (BAPA: Base de datos de Argayos del Principado de Asturias - Principality of Asturias Landslide Database), from 2003 to 2010. Afterwards, a new check with instability data registered in BAPA dataset from 2010 to 2017 has been done.

A-DInSAR and BAPA data have been jointly integrated and examined in a GIS. The results obtained indicate that there is consistency between both types of data. In addition, this research has been useful to highlight the G-POD free service as a reliable, economic and adequate tool to analyse movements of terrain during time periods of several years in the North of Spain.
High-resolution teleseismic body-wave tomography with a 3D initial crustal model for crust-to-upper mantle images in highly heterogeneous media.
Authors: Clutier Adeline , Gautier Stéphanie , Tiberi Christel
Published: March 2020

Local and teleseismic body wave inversions are two approaches commonly used to obtain 3D Earth velocity models for shallow and mantle scale, respectively. However, each method used separately is poorly resolved at the mantle/crust boundary while imaging that interface is important to understand the geodynamic processes (e.g. magmatic underplating, mantle delamination, crustal thinning or thickening) occurring at this depth. In order to develop a high-resolved final velocity model, the two approaches were combined. First, an irregular grid was settled, with a higher density of nodes at crustal scale (from 0 to 40 km) and an increasing node step when approaching the limits of the model. Then, an a priori 3D crustal velocity model (from an independent local tomography) was inserted within the 1D IASP91 lithospheric one. Finally, the teleseismic tomographic inversion was carried out at crust-to-upper mantle scale using this new mixed initial model and teleseismic data. We applied the method on a real case that includes both tectonic and magmatic processes, the North Tanzanian Divergence (NTD). Synthetic tests showed that we had no resolution between 0 and 35 km. However, a fine crustal grid with the 3D local model helps to better constrain ray paths, limiting the artefacts and smearing from the mantle to the crust, enhancing details, sharpening the velocity anomalies and modifying the geometry of anomalies at depth (> 150 km). Following these tests, we propose then a final scheme in which we include the a priori crustal 3D velocity model in the finer crustal grid, and we prevent the inversion from modifying it. This insertion of strong crustal constraints in teleseismic inversion provides sharper spatial resolution at both crustal and mantle scales, including areas with poor ray coverage, beneath the NTD region. Our strategy allows to counteract the degradation of the results in areas with low velocity zones (such as rift and hotspot), where the seismic rays go around these anomalies.
Wetland biomass inversion and space differentiation – Using the Yellow River Delta Nature Reserve as an example
Authors: Han Mei
Published: March 2020

As one of the world's three major ecosystems, the study of wetland health has global environmental implications. Vegetative biomass has emerged as one of the most valuable indicators of wetland health. The ongoing development of remote sensing techniques, coupled with improved data processing and modeling, creates new possibilities to monitor and understand wetlands. Multiple regression model types were employed to find the best fit between Landsat-8 images, vegetation indices, and field measured biomass in the Yellow River Delta Nature Reserve. Then, these models were used to estimate the spatial distribution of wetland vegetative biomass. Further, the relationship between wetland vegetative biomass and soil factors (organic matter, nitrogen, phosphorus, potassium, water soluble salt, pH, and moisture) was correlated and modelled. It was discovered that the Landsat-8 images and vegetative indices are better at predicting biomass when dry weight data is used rather than fresh weight data. Using multiple regression model types, we were able to achieve higher correlation and higher fit accuracy with vegetative indices and Bands 1-5 as independent variables and biomass dry weight as the dependent variable. Several soil factors were discovered, such as soil moisture and salt concentrations, which affect spatial distribution patterns of biomass in this wetland. Continued research using and improving upon these techniques will yield new insights into how to better promote wetland health.
Exact analytical solutions for three-dimensional multispecies advective-dispersive transport equations sequentially coupled with first-order decay reactions in a semi-infinite domain
Authors: Liao Zhong-Yi , Chen Jui-Sheng
Published: March 2020

Analytical solutions to a set of simultaneous multispecies advective-dispersive transport equations sequentially coupled with first-order decay reactions have been widely used to describe the movements of decaying or degradable contaminants such as chlorinated solvents, nitrogens and pesticides in the subsurface. This study presents an exact analytical solutions for three-dimensional coupled multispecies transport in a semi-finite domain. The analytical model are derived for both the first-type and third-type inlet boundary conditions. A method of consecutive applications of three integral transformation techniques in combination with sequential substitutions is adopted to derive the analytical solutions to the governing equation system. The developed analytical model is robustly verified with a chlorinated solvent transport problem. It is applied to investigate the effect of inlet-boundary conditions on the multispecies plume migration and the model could be a very efficient tool that can be used to simulate the degradable contaminant sites.

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Combining air quality network data and chemistry-transport modeling for the attribution of extreme pollution events: a case study of Santiago, Chile
Authors: Lapere Rémy , Menut Laurent , Mailler Sylvain , Huneeus Nicolás
Published: March 2020

In wintertime, high background concentrations of atmospheric fine particulate matter (PM2.5) are commonly observed in the metropolitan area of Santiago, Chile. Although the frequency of alert events has been decreasing in the recent years, two short-lived peak events reaching up to 600µg/m3 for a few hours were observed in the city on June 18th and June 26th 2016, triggering emergency measures for the next day.

The observed meteorological conditions at the time of these peaks are not unusual. In addition, a high-resolution meteorology and chemistry-transport simulation with the WRF meteorological model and the CHIMERE chemistry-transport model reproduces fairly well the meteorology and levels of PM for June 2016, except for those two particular events that are not captured by the model. The combination of these elements leads to the conclusion that sporadic strong emissions are at play.

The analysis of recorded concentration ratios of PM2.5, NOx and CO points to a specific source, departing significantly from the average signal for the season. Based on the literature and HTAP emission ratios, usual sources of PM such as traffic, residential heating and industry can be ruled out. The temporal correlation of the events with soccer games of the Chilean team and the recorded chemical footprint lead to conclude to the dominant contribution of massive barbecue cooking at the peak times.

Following the source identification via surface stations analysis, the next question was to quantify the potential transport and impact of such pollution peaks in the Santiago Metropolitan area. An additional source term was added in the chemistry-transport simulation, and maps of PM changes were analyzed. For both events, the same region in the Southwest of Santiago was impacted by the plume.

A natural continuation of this work is the study through modeling of the dispersion patterns of polluted plumes outside of the Santiago basin on a longer time scale. In particular, significant deposition of light-absorbing particles has been measured on glaciers near the capital city, without a clear identification of their source or the underlying processes of transport.
The role of arctic forecast errors in the evolution of northern extra-tropical forecast skill
Authors: Haiden Thomas
Published: March 2020

Increases in extra-tropical numerical weather prediction (NWP) skill over the last decades have been well documented. The role of the Arctic, defined here as the area north of 60N, in driving (or slowing) this improvement has however not been systematically assessed. To investigate this question, spatial patterns of changes in medium-range forecast error of ECMWF’s Integrated Forecast System (IFS) are analysed both for deterministic and ensemble forecasts. The robustness of these patterns is evaluated by comparing results for different parameters and levels, and by comparing them with the respective changes in ERA5 forecasts, which are based on a ‘frozen’ model version. In this way the effect of different atmospheric variability on the estimation of skill improvement can be minimized. It is shown to what extent the strength of the polar vortex as measured by the Arctic and North-Atlantic Oscillation (AO, NAO) influences the magnitude of forecast errors. Results may indicate whether recent and future changes in these indices, possibly driven in part by sea-ice decline, could systematically affect the longer-term evolution of medium-range forecast skill.