bluuebunny/crossref_metadata_2025 huggingface dataset:
Sub-shelf melting consequences of recent and future Pine Island Glacier ice shelf calving events
Authors: Bradley Alex , Holland Paul , Dutrieux Pierre
Published: March 2021

In recent years, the ice shelf of Pine Island Glacier has experienced several significant calving events. It is understood that the presence of the ice shelf in conjunction with a subglacial ridge provide a strong topographic barrier to warm Circumpolar Deep Water spilling onto the continental shelf, but it is not known how this barrier will respond to this recent, and possible future, calving events. In this presentation, I shall present results of numerical simulations of ocean circulation under Pine Island Glacier, which indicate a strong sensitivity to such calving events, and discuss the implications of these results for the overall stability of the glacier.
Reconstructing Holocene palaeoenvironmental conditions in the Baltic: Palynological and biogeochemical data from the Landsort Deep (IODP Expedition 347, Site M0063)
Authors: Kotthoff Ulrich , Bauersachs Thorsten
Published: March 2021

Restricted basins, such as the Baltic Sea, experience particularly large impact from ongoing global climate change, including severe oxygen depletion, intensified stratification and increased water temperatures. This results in significant and lasting ecosystem alterations. IODP Expedition 347 recovered sediment cores from the Baltic Sea which allow reconstructions of such changes in an as yet unprecedented quality and resolution. We analysed Holocene sediments from the Landsort Deep (IODP Site M0063) using a combined palynological and biogeochemical approach in order to reconstruct palaeoclimate and associated terrestrial and marine ecosystem changes as well as identify anthropogenic influence in the Baltic region. Pollen are used as proxy for terrestrial vegetation changes, including agricultural activity indicated by the presence of cereals. Comparison of pollen data with organic-walled dinoflagellate cysts and other palynomorphs such as the algal taxa Pediastrum, Botryococcus, and Radiosperma from identical samples provides a direct land-sea comparison. These analyses are complemented with the reconstruction of sea surface temperatures (TEXL86, LDI) and mean annual air temperatures (MBT’5Me) in the Baltic Sea region. For the late to middle Holocene (~8000 to ~4000 years BP), our data imply a strong brackish-marine influence which decreases around 4000 years BP. A gradually increasing proportion of long-chain n-alkanes around this time indicates a stronger terrestrial influence. Increasing percentages of spruce (Picea) point to the immigration of this taxon in the central Baltic region. Warmth-loving tree taxa such as hazel (Corylus) imply warm conditions between ~5000 and 4000 years BP but subsequently their pollen percentages are decreasing in general. Otherwise our data indicate only minor terrestrial ecosystem changes until ca. 1000 years BP. The past ca. 1000 years witnessed increased agricultural activity, indicated by higher abundances of rye (Secale) pollen, and probably anthropogenically induced deforestation. This increase is paired with high percentages of the enigmatic palynomorph Radiosperma corbiferum. During the past 500 years sea surface temperatures increased significantly, culminating in values comparable to the Holocene Climatic Optimum. Generally, the most rapid changes in the terrestrial ecosystems seem to have happened during the past millennium under anthropogenic influence.
The magnitude of pollution supply in small urban catchment (Różany Stream) in Poznan, Poland
Authors: Major Maciej , Chudzińska Maria , Majewski Mikołaj , Stefaniak Małgorzata
Published: March 2021

The recognition of natural environment current functioning is possible throughout the determination of the energy and material balance (mainly water and dissolved substances) in various catchments. Dissolved matter circulation in the river catchment reflects natural hydrometeorological and hydrochemical processes as well as anthropogenic activity, which appears primarily as the supply of pollutants.

The research was conducted in 4 hydrological years (2016-2019) within the borders of a small urban catchment in the northern part of the city of Poznań (Poland), the main watercourse of which is the Różany Stream (Różany Strumień). The natural environment of the Różany Stream catchment is characterized by significant transformations due to human activity. The most important environmental problems include threats related to the pollution of surface waters and groundwater as a result of processes related to the functioning of an urban catchment.

The main aim of this work is to present the magnitude of pollution supply into the catchment and to determine the temporal variability of matter circulation in a small urban catchment in years with different pluvial conditions and therefore quantitatively changing atmospheric supply reaching the geoecosystem.

The magnitude of pollution supply to the catchment was determined on the basis of systematic, comprehensive measurements of the natural environment. The measurement system and the field research methodology refer to the methodological concept of the system functioning, as well as the assumptions of the European International Cooperative Programme on Integrated Monitoring of Air Pollution Effects on Ecosystems (ICP IM) and Integrated Monitoring of the Natural Environment in Poland (ZMSP) programs.

This work presents the results of measurements of several components of the natural environment, initially including meteorological conditions (mainly precipitation and air temperature). The next elements of the research concerned air pollution with sulphur dioxide and nitrogen dioxide as well as the chemical composition of precipitation, which is considered as an entry into the geoecosystem. Moreover, there are also presented the results of the physicochemical properties of surface waters (including levels, flows and chemical composition) and groundwater.

The quantitative and qualitative characteristics of the atmospheric supply to the geoecosystem, the water cycle in the catchment and the water runoff confirm the assumptions that the dissolved matter circulation is one of the most important indicators of changes in the natural environment in the moderate morphoclimatic zone.
Depositional Palaeoenvironment and Models of the Eocene Lacustrine Source Rocks in the Northern South China Sea
Authors: Zhao Niubin
Published: March 2021

      Element geochemical analysis of 94 ditch cutting samples of the shale source rock from the Wenchang Formation in the Zhuyi sub-basin and the Liushagang Formation in the Weixinan sub-basin was conducted to determine their palaeoenvironment and main controlling factors and to further establish development models. The results indicate that freshwater and a warm and humid climate were characteristics of the depositional palaeoenvironment between Wenchang and Liushagang formations. During the deposition of Wenchang Formation, the parent rocks mainly consisted of felsic volcanic rocks, the water was characterized by a high palaeoproductivity, shallow-deep water depths, and weakly reducing conditions, whereas during the deposition of Liushagang Formation, the parent rocks mainly consisted of mafic volcanic rocks, and the palaeoproductivity, palaeowater depth, and reducing conditions of the water were better than during the deposition of Wenchang Formation. The formation of high-quality source rocks in the Liushagang Formation were mainly controlled by two factors: (1) the mafic igneous rock provenance and strong weathering provided macronutrients (e.g. P, Fe) for water; (2) high palaeoproductivity provided the source of organic matter, which played a much important role than preservation condition of organic matter. For Wenchang Formation, the good preservation of organic matter which was created by the reducing environment in deep water was also necessary. Accordingly, two models were briefly summarized: a productivity and preservation model for the Wenchang Formation source rocks and a productivity model for the Liushagang Formation source rocks, both of them can develop high-quality source rocks, but the source rock quality of the former were lower than of the latter, this was mainly attributed to the difference in the nutrients and palaeoproductivity. This study provides valuable guidance for oil and gas exploration in the northern South China Sea and the study of lacustrine source rocks in other areas.
The Solar Orbiter mission – Exploring the Sun and heliosphere
Authors: Mueller Daniel , Zouganelis Yannis , Nieves-Chinchilla Teresa , St. Cyr Chris
Published: March 2021

Solar Orbiter, launched on 10 February 2020, is a space mission of international collaboration between ESA and NASA. It is exploring the linkage between the Sun and the heliosphere and has started to collect unique data at solar distances down to 0.49 AU. By ultimately approaching as close as 0.28 AU, Solar Orbiter will view the Sun with very high spatial resolution and combine this with in-situ measurements of the surrounding heliosphere. Over the course of the mission, the highly elliptical orbit will get progressively more inclined to the ecliptic plane. Thanks to this new perspective, Solar Orbiter will deliver images and comprehensive data of the unexplored Sun’s polar regions and the side of the Sun not visible from Earth. This talk will highlight first science results from Solar Orbiter and provide a mission status update.
Tillage-residue management affects the distribution, storage and turnover of mineral-associated organic matter – A case study from northern Mexico 
Authors: Romero Carlos , Hao Xiying , Hazendonk Paul , Schwinghamer Timothy , Chantigny Martin , Fonteyne Simon , Verhulst Nele
Published: March 2021

Managing croplands for increased storage of soil organic matter (SOM) is a critical step towards developing resilient farming systems in a changing climate. We examined SOM dynamics in a wheat (Triticum durum L.) – maize (Zea mays L.) irrigated bed planting system established near Ciudad Obregón, Sonora, Mexico. Soil samples (0 – 15 cm) were collected from conventionally tilled raised beds (CTB) with all crop residues incorporated (CTB-I) and permanent raised beds (PB) with crop residues burned (PB-B), removed (PB-R), partly retained (PB-P) or fully retained (PB-K) receiving 0, 150 or 300 kg N ha-1, and analyzed for organic C (OC), total N (TN) and δ13C in whole-soil, light fraction (LF) and coarse- (sand) and fine- (silt and clay) mineral-associated organic matter (MAOM). Results indicated that PB-K and PB-B increased soil OC (P < 0.05) in whole-soil relative to CTB-I, mainly through increases in sand- and silt-size MAOM, respectively. Similarly, N-fertilization increased soil OC and TN contents in whole-soil, coarse-MAOM, and fine-MAOM, but not in the LF pool. Soil δ13C was higher (P < 0.05) in PB-K (-20.18‰) relative to PB-B (-20.67‰), possibly due to the stabilization of partly decomposed maize-C in silt- and clay-size MAOM. The composition of SOM surveyed by CPMAS 13C NMR was not affected by tillage-residue management and roughly consisted of 35% O-alkyl-C, 31% alkyl-C, 24% aromatic-C, and 10% carboxyl-C. Our results indicate that long-term PB-K and PB-B adoption increased surface soil OC contents relative to CTB-I, even though pathways of SOM stabilization differed between systems. Under PB-K, accumulation of fine-MAOM was mostly related to straw-C inputs, whereas in PB-B it was closely associated with black-C precursors. Fine-MAOM appeared responsive to crop residue management and should be therefore considered when analyzing mechanisms of SOM stabilization in irrigated croplands.
Accounting for high-dimensional predictors in RFA with MARS 
Authors: Msilini Amina , Masselot Pierre , Ouarda Taha B.M.J.
Published: March 2021

Hydrological processes and phenomena are naturally complex and nonlinear. Many physiographical variables such as those dealing with drainage network characteristics may influence streamflow characteristics and should be considered in regional frequency analysis (RFA). These variables have hence a significant impact on the effectiveness of flood quantile estimation techniques. Although many statistical tools are considered to estimate flood quantiles at ungauged sites in the hydrological literature, little attention has been given to the nonlinearity and to the high-dimensionality of physio-meteorological variable space. In this study, the multivariate adaptive regression splines (MARS) approach is introduced in RFA. This model allows to account simultaneously for non-linearity and interactions between variables hidden in high-dimensional data. MARS is hereby applied on two datasets of 151 hydrometric stations located in the southern part of the province of Quebec (Canada): a standard dataset (STA) including commonly used variables and an extended dataset (EXTD) combining STA with additional variables dealing with drainage network characteristics. It is then compared to generalized additive models (GAM), a state-of-the-art method for regional estimation. Numerical results show that MARS outperforms GAM, especially with the extensive database EXTD. The study suggests that MARS may be a promising tool to take into account the complexity of the hydrological phenomena involved and the increasing number of variables used in RFA.
Urban-focused satellite CO2 observations from the Orbiting Carbon Observatory-3: a first look at the Los Angeles Megacity 
Authors: Kiel Matthäus , Eldering Annmarie , Roten Dustin D. , Lei Ruixue , Feng Sha , Lin John C. , Lauvaux Thomas , Roehl Coleen M. , Oda Tomohiro , Iraci Laura T. , Blavier Jean-Francois
Published: March 2021

The OCO-3 instrument was launched on May 4, 2019 from Kennedy Space Center to the International Space Station. Since August 2019, the instrument has taken measurements of reflected sunlight in three near-infrared bands from which column averaged dry-air mole fractions of carbon dioxide (XCO2) are derived. The instrument was specifically designed to measure anthropogenic emissions and its snapshot area map (SAM) and target (TG) observational modes allow to scan large contiguous areas (up to 80×80 km2) on a single overpass over emission hotspots like cities, power plants, or volcanoes. These measurements result in fine-scale spatial maps of XCO2 unlike what can be done with any other current space-based instrument. Here, we present and analyze XCO2 distributions over the Los Angeles (LA) megacity derived from multiple OCO-3 TG and SAM mode observations using the vEarly data product. We find that urban XCO2 values are elevated by 2-6 ppm relative to a clean background. The dense, high resolution OCO-3 observations reveal fine-scale, intra-urban variations of XCO2 over the LA megacity that have not been observed from space before. We further analyze the intra-urban characteristics and compare the XCO2 enhancements observed by OCO-3 with simulated values from two models that can resolve XCO2 variations across the city: an Eulerian (WRF-Chem) and a Lagrangian approach (X-STILT). We show that the observed variations are mainly driven by the complex and highly variable meteorological condition in the LA Basin. Median XCO2 differences between model and observation are typically below 1.3 ppm over the entirety of the LA megacity with slightly larger differences for some sub regions. Further, we find that OCO-3’s multi-swath measurements capture about three times as much of the city emissions compared to single-swath overpasses. In the future, these observations will help to better constrain urban emissions at finer spatiotemporal scales.
Influence of Regional Tectonic and Rheological Structure on the Seismic Cycle for Northeast Japan
Authors: Vladimirova Irina , Gabsatarov Yurii , Steblov Grigory , Lobkovsky Leopold
Published: March 2021

The subduction zone is a natural laboratory for studying the seismic cycle. On March 11, 2011, in the central part of the Japan subduction zone, the strongest Mw=9.0 Tohoku earthquake occurred, terminating a seismic cycle that lasted about 1200 years. We analyzed two decades of GNSS observations at 1400 GEONET stations to reveal the peculiarities of the tectonic and rheological structure of the Japan subduction zone which driven such a long-term seismic cycle. We consider GNSS data within the framework of a generalized approach, including the assessment of the coupling of the interplate interface before the earthquake, the construction of a model of the distributed displacement in the source zone, and the study of postseismic processes characterizing the relaxation of elastic stresses in the vicinity of the source.

As a result, we found that in the last year before the earthquake, there was an increase in the rates of elastic deformation of the continental margin and a corresponding increase in the interplate coupling. To study the process of the release of elastic energy during the Tohoku earthquake, we built a model of the distributed slip in the source. We used different earth models during inversion of GNSS data to study the impact of the regional tectonic and rheological structure and confirm the resilience of our inversion technique. We used GNSS data to build a model of pure afterslip in the first six months after the Tohoku earthquake and a model of afterslip combined with the short-term viscoelastic relaxation to estimate the relative contributions of these postseismic processes to the observed displacement field. Long-term postseismic time series of GNSS displacements were used to build the model of viscoelastic relaxation in the asthenosphere following the Tohoku earthquake. To estimate the transition time of the subduction zone to the steady-state of elastic stress accumulation we constructed a forecast of attenuation of viscoelastic stresses in the asthenosphere on the basis of our viscoelastic relaxation model.

We also studied the possible block structure of the Japanese Islands and its impact on the seismic cycle performing cluster analysis of GNSS displacement data at different stages of the seismic cycle.

This study was supported by the Russian Science Foundation (project 20–17-00140).
Assessing the rotation and segmentation of the Porcupine Bank, Irish Atlantic margin, during oblique rifting using deformable plate reconstruction
Authors: Yang Pei , Welford J. Kim , King Michael
Published: March 2021

With an increasing number of global and regional plate reconstruction models established in recent years, the motion of the Porcupine Bank, Irish Atlantic continental margin, underlain by orogeny-related pre-rift crustal basement terranes, have been investigated and restored as well.  However, these reconstructed models of the Porcupine Bank margin mainly depend on potential field data analysis and lack seismic constraints, failing to reveal the role of inherited crustal sutures during rifting and associated crustal deformation over geological time. In this study, five deformable models with distinct structural inheritance trends are established in GPlates by adjusting a previously published regional restoration model for the North Atlantic realm. For each model, driving factors (e.g., such as whether the Orphan Knoll is included, the altered rotational poles of the Flemish Cap, and the motion of the eastern border of the Porcupine Basin) are also taken into consideration. Crustal thicknesses from gravity inversion and seismic refraction data modelling are compared against those from these deformable plate reconstruction models to identify the most geologically reasonable one. The resulting preferred model has the Porcupine Bank subdivided into four blocks with each experiencing polyphase rotations and shearing prior to final continental breakup, implying strong inheritance and segmentation of the Porcupine Bank and the Porcupine Basin. The derived reconstructed paleo-positions over time of the Flemish Cap and the Porcupine Bank within the deforming topological network reveal new and evolving conjugate relationships during rifting, which are assessed using regional seismic transects from both margins. Finally, extensional obliquity between both margins is quantitatively restored, showing time-variant orientations due to the rotation and shearing of associated continental blocks, which contributes to unraveling the spatial and temporal evolution of southern North Atlantic rifting during the Mesozoic, prior to the initiation of seafloor spreading.
Interaction of Fully-Nonlinear Internal Solitary Waves of Opposite Polarity
Authors: Lamb Kevin
Published: March 2021

Previous studies have suggested that fully nonlinear internal solitary waves (ISWs) are very soliton-like as the interaction of two ISWs results in only very small changes in amplitude of the interacting ISWs and in the production of a very small amplitude wave train. Previous studies have, however, considered ISWs with the polarity predicted by the sign of the quadratic nonlinear coefficient of the KdV equation. The Gardner equation, which is an extension of the KdV equation that includes a cubic nonlinear term, has ISWs of two polarities (i.e., waves of depression and elevation) when the cubic coefficient of the Gardner equation is positive. These waves are soliton solutions of the Gardner equations.  In this talk I will discuss the interaction of ISWs of opposite polarity in continuous asymmetric three layer stratifications. Regions in parameter space where ISWs of opposite polarity exist will be discussed and I will demonstrate via fully nonlinear numerical simulations that the interaction of ISWs of opposite polarity waves are far from soliton-like: their interaction can result in very large changes in wave amplitude and may produce a very complicated wave field with multiple large ISWs, a large linear wave field and breather-like waves. 
Interpreting the observed variability of deep waters in the Irminger Sea
Authors: Prieto Eva , Desbruyères Damien , Thierry Virginie
Published: March 2021

Temperature and salinity seasonal to interannual variability of Iceland Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW) is investigated by combining two in-situ datasets in the Irminger Sea for the period 1997-2020: 12-yr of repeated hydrography (1997-2018) provided by the FOUREX, OVIDE and RREX sections and 4-yr of data (2016-2020) from 8 Deep Argo floats deployed in the region between 2016 and 2018.

In order to enable a consistent analysis of ocean temperature and salinity variability from unevenly distributed vertical profiles (both in space and time), it is necessary to estimate the appropriate regional climatology to be removed from every observation. Two independent procedures are followed to compute anomalies and quantify uncertainties related to the choice of climatology: First, the global 1°-resolution World Ocean Atlas 2018 (2005-2017 averages) climatology is retrieved from every observed profile (Deep Argo, hydrography). Second, the well-known and sampled OVIDE transect (2002-2018 average) is used to build a reference section of geographical anomalies that are subsequently propagated along potential vorticity contours in the Irminger Sea. Neutral density surfaces 28.02 kgm-3 and 28.12 kgm-3 are then chosen from mean OVIDE 2002-2018 gridded fields as representative of ISOW and DSOW levels, respectively. Significant decadal trends in water mass properties are revealed by repeated hydrography, whereas some striking boundary-interior spatial patterns are captured by Deep Argo floats. Property changes of ISOW and DSOW are discussed in terms of changes of source waters in the Nordic Seas, entrainment of Atlantic waters into the overflow waters and cascading events from the Greenland slope.

 
Microplastics research at the interface of aquatic and terrestrial systems – Opinion
Authors: Prume Julia , Weber Collin
Published: March 2021

Rivers are often pictured as transport routes for plastics and microplastics from land to sea. Indeed, from a geological and geomorphological perspective, the main system function of rivers is the transport of water and sediments. An increasing amount of studies has detected microplastics not only in river waters but also in river sediments, banks and floodplains. The occurrence of microplastics in both aquatic and terrestrial systems raises the question of processes related to microplastics at the two system’s interface. However, in microplastics’ research, aquatic and terrestrial compartments are usually investigated separately from each other. Such a restricted perspective cannot explain reality adequately: Rivers are highly dynamic and complex systems, they are framed by and interact with terrestrial systems on different spatial and temporal scales. This interaction is known with regard to sediment deposition and erosion as well as pollutant or nutrient enrichment. In microplastics’ research, to date, little is known on interface processes such as (potentially bidirectional) horizontal and vertical plastic transport, deposition and erosion as well as remobilization. Little is known on the fate of plastics within both systems and at the interface: fragmentation, leaching and absorption of chemicals, biofilm formation, homoaggregation, heteroaggregation, intake by plant and animal organisms. However, a comprehensive understanding of sources, transport paths, as well as sinks is not only an academic problem but can support political stakeholders to manage pollution by microplastics. Therefore, we suggest to shed light not only on microplastics’ abundance in rivers or soils but also on processes at the interface of aquatic and terrestrial systems.
Geodiversity in the Liguria region: a preliminary GIS-based quantitative assessment
Authors: Ferrando Andrea , Faccini Francesco , Poggi Flavio , Coratza Paola
Published: March 2021

 Geodiversity is an important natural resource that must be considered in developing an effective land management strategy. In recent times there has been a great impulse on the research on geodiversity topics; particular attention has been given to geodiversity assessment methodologies, both qualitative and quantitative. The Liguria region in Northern Italy, despite its small geographic scale, encompasses a great variety of natural and cultural features of international significance. This wide variety is due to its particular geographical, geological and geomorphological conditions. In this work a first preliminary assessment of geodiversity in the Liguria region has been carried out, according to the quantitative method proposed by Melelli et al (2017). This GIS-based method uses spatial analysis techniques, taking into account five parameters: a geological index (lithology) and four morphometric indices (drainage density, roughness, slope position index and landform category), combined to obtain a total Geodiversity Index. The results show that the Liguria region is characterized by many areas with high geodiversity. The most important examples are the western Ligurian Alps, the Finalese, the Sestri-Voltaggio Zone and its surroundings, the eastern Ligurian Apennines, the Cinque Terre, which are in fact the areas with the greatest morphological and lithological variety. Most of these areas are well known by geoscientists for their significant geological and geomorphological heritage, and by the general public for their impressive landscapes. There is a correspondence between the most geodiverse areas, the main natural parks and the Natura 2000 network of protected areas, established to protect and enhance biodiversity. This suggest a link between geodiversity and biodiversity, that may be subject to further research.
Discrimination of earthquakes and quarry blasts in Mecsek Mountain region (Hungary) and its vicinity by using a linear discrimination function 
Authors: Kiszely Márta , Süle Bálint , Bondár István
Published: March 2021

Contamination of earthquake catalogues with anthropogenic events largely complicates seismotectonic interpretation. It is especially true for relatively low seismicity areas, such as Hungary. In the present study, we analyze the characteristics of earthquakes and blasts of quarries occurred between 2015 and 2020 in the Mecsek Mountains in southern Hungary within 120 km to MORH and KOVH stations.

The objective of this study was to determine the linear discrimination line between the two classes earthquakes and explosions. We investigated the effectiveness of P/S amplitude ratios using filtered waveforms at different ranges of frequencies. We applied waveform cross-correlation to build correlation matrices at both stations and performed hierarchical cluster analysis to identify event clusters. Because most of the quarry blasts were carried out by ripple-fire technology, we computed spectrograms and examined the spectral ratio between low and high frequencies and the steepness of spectra.

Classes of earthquakes and quarry blasts have separated well from each other by combining the amplitude ratio, waveform similarity and the different spectral methods. We compare the discrimination parameters and capability of both stations to identify the explosions in analyzed quarries that were misclassified as earthquakes in the Hungarian National Bulletins.
A method for recognizing the muon flux intensity modulations using the normalized variation functions for the URAGAN hodoscope matrix data
Authors: Chinkin Vladislav , Getmanov Viktor , Sidorov Roman , Gvishiani Alexei , Dobrovolsky Mikhail , Soloviev Anatoly , Dmitrieva Anna , Kovylyaeva Anna , Osetrova Natalia , Yashin Igor
Published: March 2021

Muon flux intensity modulation (MFIM) recognition is a relevant solar-terrestrial physics problem. The considered MFIM, recorded on the Earth's surface, are caused by extreme heliospheric events – the geoeffective solar coronal mass ejections.

The URAGAN muon hodoscope (MH), developed by NRNU MEPhI, a computerized device that measures the intensities of muon fluxes, is used. In the MH, the number of muons falling per unit time on the MH aperture is calculated for the selected system of zenith and azimuthal angles. MH matrix data time series are formed. In the MH data, there are angular modulations due to the action of the hardware function HF, temporal modulations due to atmospheric disturbances and noise: the values of these modulations significantly exceed the values of MFIM of cosmic origin. This circumstance prevents effective MFIM recognition.

A method for MFIM recognition is proposed, based on the mathematical apparatus of the introduced normalized variation functions for MH matrix data, and focused on overcoming the noted circumstance.

A two-dimensional normalized HF is defined for MH. A quite realistic hypothesis is accepted about the initialiy uniform muon flux intensity distributions on a small reference time interval, where there are no extreme heliospheric events and the corresponding reference MH data do not contain significant MFIMs. The estimation of the two-dimensional normalized HF is carried out on the basis of a multiparameter model and its optimization fit to the reference MH data. In order to reduce noise errors, the estimate of the two-dimensional normalized HF is subjected to two-dimensional filtering and subsequent threshold filtering.

Two-dimensional functions of variations of matrix MH datas with respect to two-dimensional normalized AF are calculated. The normalized variation functions are calculated by dividing the two-dimensional functions of variations of matrix MH data by the two-dimensional normalized HF. MFIM recognition method was tested on model and experimental MH data.

A time series of model matrix MH data containing model MFIM was generated. Testing led to a conclusion that it is possible to recognize MFIM with decreases of about 2-3%. A time series of experimental matrix MH data was generated, in which the model MFIM-containing areas were made. Testing led to a conclusion that it is possible to recognize MFIM with the magnitudes of the decreases almost commensurate with the decreases for the case of model MH data.

The proposed MFIM recognition method based on the normalized variation functions for matrix MH data has a favorable perspective for its application in solving problems of geomagnetic storm early diagnostics.
Progress on a comprehensive earth system model evaluation framework
Authors: Knoben Wouter , Vionnet Vincent , Clark Martyn
Published: March 2021

Thorough evaluation of model fidelity is critical to have faith in a model’s capability to simulate surprise; i.e. in the model’s capability to accurately simulate hydrologic behavior under changing conditions. We define three elements that should support such thorough model evaluation. First, test cases with known solution should be used to isolate the implementation of specific processes in a model and to make sure that the model code can reproduce these known solutions. Second, model simulations of individual processes should be compared to observations of these processes to determine the accuracy and appropriateness of the equations used to represent these processes in the model. Third, benchmarks need to be defined that both provide a lower limit to the accuracy we require the model to have and an upper limit to system’s predictability based on the information contained in the input and output observations.  We present progress on all three themes covering (1) the development of test cases with known solutions called “laugh tests”; (2) progress in setting up a continental-scale model for process-based model evaluation; (3) critical notes about the still common use of aggregated efficiency criteria for model evaluation; (4) a summary of existing work on the need of lower and upper benchmarks which will inform further benchmarking work. A guiding principle in our work is to make our code available as open-source, so that the community can reproduce and use our work if desired. As such, we explicitly invite the community to share their own thoughts about these topics with us.
A global analysis of spatial correlation lengths of water storage anomalies 
Authors: Sharifi Ehsan , Haas Julian , Boergens Eva , Dobslaw Henryk , Güntner Andreas
Published: March 2021

This study has been run in the context of the European Union research project G3P (Global Gravity-based Groundwater Product) on developing Groundwater storage (GW) as a new product for the EU Copernicus Services. GW variations can be derived on a global scale by subtracting from total water storage (TWS) variations based on the GRACE/GRACE-FO satellite missions variations in other water storage compartments such as soil moisture, snow, surface water bodies, and glaciers. Due to the nature of data acquisition by GRACE and GRACE-FO, the data need filtering in order to reduce North-South-oriented striping errors. However, this also leads to a spatially smoothed TWS signal. For a consistent subtraction of all individual storage compartments from GRACE-based TWS, the individual data sets for all other hydrological compartments need to be filtered in a similar way as GRACE-based TWS.

In order to test different filter methods, we used compartmental water storage data of the global hydrological model WGHM. The decorrelation filter known as DDK filter that is routinely used for GRACE and GRACE-FO data introduced striping artifacts in the smoothed model data. Thus, we can conclude that the DDK filter is not suitable for filtering water storage data sets that do not exhibit GRACE-like correlated error patterns. Alternatively, an isotropic Gaussian filter might be used. The best filter width of the Gaussian filter is determined by minimizing the differences between the empirical spatial correlation functions of each water storage and the spatial correlation function of GRACE-based TWS. We also analyzed time variations of correlation lengths such as seasonal effects. Finally, the selected filter widths are applied to each compartmental storage data set to remove them from TWS and to obtain the GW variations. 

 

Acknowledgement :

This study received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement nº 870353.
Exploring the potential of vegetation information for improving weather forecast performance
Authors: Ruiz Melissa , Oh Sungmin , Orth Rene , Balsamo Gianpaolo
Published: March 2021

The quality of weather forecasts is continuously improving for decades. However, increases in forecast skills have slowed down in recent years. This highlights the importance of exploring new avenues towards future forecast system improvements. Until now, (near) real-time information on vegetation anomalies is not used in most forecasting models. Addressing this gap, we explore the potential of the vegetation state for explaining the spatial and temporal variation in forecast accuracy globally across climate regions, seasons, and vegetation types. For this purpose, we employ re-forecasts from the European Centre of Medium-Range Weather Forecasting (ECMWF) and infer the vegetation status through the Enhanced Vegetation Index derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite observations during the 2000-2019 period. In particular, we focus on land surface variables such as evaporation and temperature to study the relationship between forecast errors and vegetation anomalies.

The results show a stronger correlation between forecast errors and vegetation anomalies in semi-arid and sub-humid regions during the growing season, which highlights that vegetation information has the potential to help advance weather forecast performance. To put these results into perspective, we will further perform a multivariate analysis to determine the relative roles of vegetation, hydrology and climate in explaining weather forecast errors. Thereby, our results can inform the future development of weather forecast models and underlying data assimilation schemes.
Extremely fast retrieval of volcanic SO2 layer heights from UV satellite data using inverse learning machines
Authors: Hedelt Pascal , Koukouli MariLiza , Michaelidis Konstantinos , Isabelle Taylor , Balis Dimitris , Grainger Don , Efremenko Dmitry , Loyola Diego
Published: March 2021

Precise knowledge of the location and height of the volcanic sulfur dioxide (SO2) plume is essential for accurate determination of SO2 emitted by volcanic eruptions, however so far not available in operational near-real time UV satellite retrievals. The FP_ILM algorithm (Full-Physics Inverse Learning Machine) enables for the first time to extract the SO2 layer height information in a matter of seconds for current UV satellites and is thus applicable in NRT environments.

The FP_ILM combines a principal component analysis (PCA) and a neural network approach (NN) to extract the information about the volcanic SO2 layer height from high-resolution UV satellite backscatter measurements. So far, UV based SO2 layer height retrieval algorithms were very time-consuming and therefore not suitable for near-real-time applications like aviation control, although the SO2 LH is essential for accurate determination of SO2 emitted by volcanic eruptions.

In this presentation, we will present the latest FP_ILM algorithm improvements and show results of recent volcanic eruptions.

The SO2 layer height product for Sentinel-5p/TROPOMI is developed in the framework of the SO2 Layer Height (S5P+I: SO2 LH) project, which is part of ESA Sentinel-5p+ Innovation project (S5P+I). The S5P+I project aims to develop novel scientific and operational products to exploit the potential of the S5P/TROPOMI capabilities. The S5P+I: SO2 LH project is dedicated to the generation of an SO2 LH product and its extensive verification with collocated ground- and space-born measurements.
Improving the sensitivity levels generated from hypothesis testing by combining VLBI with GNSS data
Authors: Küreç Nehbit Pakize , Glaser Susanne , Balidakis Kyriakos , Sakic Pierre , Heinkelmann Robert , Schuh Harald , Konak Haluk
Published: March 2021

The individual space geodetic techniques have different advantages and disadvantages. For instance, the global observing network of Very Long Baseline Interferometry (VLBI) consists of much fewer stations with a poorer distribution than the one of Global Navigation Satellite Systems (GNSS). In a combination thereof, this fact can be compensated, mainly to the benefit of the former.

The sensitivity level provides information on the detection capacity of observing stations based on undetectable gross errors in a geodetic network solution. Furthermore, sensitivity can be understood as the minimum value of the undetectable gross errors by hypothesis testing. The location of the station in the network and the total weight of its observations contribute to the sensitivity levels thereof. Also, the total observation number of a radio source and the quality of the observations are critical for the sensitivity levels of the radio sources. Besides these criteria, a radio source having a larger structure index has a larger sensitivity level. In this study, it is investigated whether the sensitivity levels of VLBI stations in the CONT14 campaign improve by combination with GNSS. The combination was done at the normal equation level using 153 GNSS stations in total, 17 VLBI radio telescopes, and local ties at 5 co-located stations which are ONSA-ONSALA60, NYA1-NYALES20, ZECK-ZELENCHK, MATE-MATERA, and HOB2-HOBART26 during the CONT14 campaign spanning 15 days. To evaluate the observations of GNSS and VLBI, the software of EPOS8 and VieVS@GFZ (G2018.7, GFZ, Potsdam, Germany) were used respectively. In the VLBI-only solution, FORTLEZA shows the poorest sensitivity level compared to the other VLBI radio telescopes. As a result of the combination with GNSS, it can be seen that the sensitivity levels of FORTLEZA improved by about 60% in all sessions of CONT14. It can be concluded that VLBI stations, which are poorly controlled by the other radio telescopes in the network, can be supported by the other space geodetic techniques to improve the overall quality of the solution.
Extreme wind speed climatology over Greece
Authors: Blougouras Georgios , Tzanis Chris G. , Philippopoulos Kostas
Published: March 2021

Extreme wind speeds are a multifaceted environmental risk. They may cause considerable damage to infrastructure (e.g., bridges, private property), they can jeopardize maritime and aviation activities, and sometimes even human safety. Furthermore, the design of wind turbines for on and off-shore wind farms requires a study of the return periods of extreme wind speeds in combination with the lifespan of the wind turbines. Windstorms also result in major economic losses and cause up to 80 % of the natural hazards' long term insurance loss in Europe. The scope of this work is to identify location-specific extreme wind speed thresholds and obtain accurate estimates of exceedances for multiple future horizons. In this context, the Extreme Value Analysis framework is used for providing the return periods and the respective return levels of extreme wind speeds. The Peaks Over Threshold method is utilized for the 10 m wind speed for a domain centered over Greece, in Southeastern Mediterranean. Wind speed data at 10 m are extracted from the ERA5 reanalysis dataset that provides hourly estimates of surface wind speed with a horizontal resolution of 0.25°x0.25°, from 1979/01/01 up to 2019/12/31 (i.e., 41 years). The thresholds are selected using the Mean Residual Life plots, which is the most reliable method for identifying accurate threshold values. The seasonal analysis of the exceedances is discussed in terms of the physical mechanisms in the region. The exceedances are modelled using the Generalized Pareto Distribution, whose shape and scale parameters (ξ and σ, respectively) are estimated using the Maximum Likelihood Estimation method. The return levels and their confidence intervals are estimated for return periods up to 100 years. Geographic Information Systems are used for mapping future projections of extreme wind speeds and the corresponding confidence intervals. The results are discussed in terms of identifying high-risk areas and the findings could assist in informed decision-making in the wind energy industry. The proposed methodological framework could be extended to other areas characterized by particularly high wind speeds and the results can contribute towards sustainable investments and support adaptation mechanisms.
LA-ICP-MS U-Pb geochronology of carbonates from Ag-Bi-Co-Ni-As±U veins in the Erzgebirge (Germany and Czech Republic): New insights into the timing of mineralization
Authors: Guilcher Marie , Albert Richard , Gerdes Axel , Gutzmer Jens , Burisch Mathias
Published: March 2021

Hydrothermal Ag-Bi-Co-Ni-As±U (five-element) veins are particularly prevalent across Central Europe, where this type of mineralization has been mined throughout the ages for its high-grade resources of Ag, Co, Ni, and U. The timing and the detailed geodynamic setting in which this style of mineralization formed remains, however, insufficiently understood due to the limited amount of geochronological data. In this contribution, we report the results of innovative LA-ICP-MS U-Pb geochronology on the carbonate gangue of Ag-Bi-Co-Ni-As±U mineralization from six districts in the Erzgebirge/Krušné Hory metallogenic province of Germany and the Czech Republic, with the goal to constrain the timing of ore formation in the context of Central Europe's geodynamic framework.

In-situ U-Pb ages of twelve samples, including dolomite-ankerite, calcite, and siderite cogenetic with Co-Ni-Fe-arsenides, range from 129.4 ± 8.2 to 85.93 ± 3.4 Ma. The ages of Ag-Bi-Co-Ni-As±U and fluorite-barite-Pb-Zn veins from the same occurrence (Annaberg-Buchholz district) overlap each other, suggesting that these two styles of mineralization are genetically related and may form coevally. The compilation of geochronological data from other Ag-Bi-Co-Ni-As±U occurrences in Europe suggests that the origin of this style of mineralization in Central Europe can be related to continental rifting associated with the Mesozoic opening of the Atlantic and/or the Alpine Tethys (200-100 Ma). This provides for the first time evidence for the formation of Ag-Bi-Co-Ni-As±U vein mineralization across Central Europe in response to continental rifting.
Harmonic Correction for Residual Terrain Modelling (RTM) Technique in Physical Geodesy Applications
Authors: Yang Meng , Deng Xiao-Le , Zhong Min
Published: March 2021

       In physical geodesy, the harmonic correction (HC), as one of the main problems when using residual terrain modelling (RTM), has become a research focus of high-frequency gravity field modelling. Over past decades, though various methods have been proposed to handle the HC issues for RTM technique, most of them focused on the HC for RTM gravity anomaly rather than other gravity functionals, such as RTM geoid height and gravity gradient. In practice, the HC for RTM geoid height was generally assumed to be negligible, but a quantification is yet studied. In this study, besides the highlighted HC for gravity anomaly in previous studies, the expressions of HC terms for RTM geoid height are provided in the framework of the classical condensation method under infinite Bouguer plate approximation. The errors involved by various assumption of the classical condensation method, e.g., mass inconsistency between infinite masses in the HC and limited masses in the RTM, and planar assumption of the Earth’s surface, are further studied. Based on the derived formulas, the quantification of HC for RTM geoid height when reference surface is expanded to degree and order of 2,159 is given. Our results showed the significance of HC for RTM geoid height, with values up to ~10 cm, in cm-level and mm-level geoid determination. With integration masses extending up to a sufficient distance, such as 1° from calculation point for the determination of RTM geoid height, the errors due to an infinite Bouguer plate approximation are neglectable small. The validation through comparison with terrestrial measurements proved that the HC terms provided in this study can improve the accuracy of RTM derived geoid height and are expected to be useful for applications of RTM technique in regional and global gravity field modelling.