bluuebunny/crossref_metadata_2025 huggingface dataset:
Incorporating spatial gradient observations into seismic noise interferometry
Authors: Paitz Patrick , Sager Korbinian , Boehm Christian , Fichtner Andreas
Published: March 2021

With an increasing availability of next-generation instruments in seismology such as Distributed Acoustic Sensing (DAS) interrogators and rotation sensors, as well as public datasets from these instruments, there is a demand for incorporating these new gradient observables into the workflows of seismic interferometry and noise source inversion.

Dropping the common assumption of Green’s function retrieval, we derive a generalized formulation for seismic interferometry that can utilize not only displacement measurements but also spatial and temporal gradients thereof – including velocity, strain and rotation.

Based on this formulation, we are able to simulate interferometric wavefields of displacement and gradient observations or arbitrary combinations of these observables, for heterogeneous visco-elastic media, and for arbitrary noise source distributions.

We demonstrate how to derive adjoint-based expressions for finite-frequency sensitivity kernels of the interferometric wavefields with respect to subsurface structure and noise source distributions, for a wide range of observed quantitates and combinations thereof. We provide numerical examples of such sensitivity kernels.

Especially in environments where the common assumption of a homogeneous noise source distribution is violated, our formulation enables correlation-wavefield based inversions, combining different seismic observables.

The discussed theoretical and numerical developments bring us one step closer to multi-observational full waveform ambient noise inversion, underlining the potential and possible impact of recent developments in seismic instrumentation to seismology across all scales.
Analysis of tidal average saturated suspended sediment concentration of cohesive sediment in the Yangtze Estuary
Authors: Tao Junyu , Hu Peng , Li Wei , He Zhiguo
Published: March 2021

It is generally believed that sediment erosion and deposition can’t occur simultaneously, which is also reflected in the classical Partheniades-Krone formulas used to calculate erosion and deposition flux. In this study, the erosion and deposition fluxes of cohesive sediment are integrated in the tidal period respectively, and when they are equal, the corresponding suspended cohesive sediment concentration is called ‘tidal average saturated concentration of cohesive sediment’. Theoretical analysis of the factors affecting the saturated concentration indicates that a large erosion coefficient results in a high saturated concentration level. The corresponding critical erosion and deposition shear stresses (i.e., τe and τd) at saturated concentration have many possibilities. Therefore, it is understandable that good agreement of suspended sediment concentration between simulation and observation have been obtained by adjusting τe and τd in the previous numerical simulation calibration. According to the relative magnitude of τe and τd at saturated concentration, the erosion and deposition fluxes of cohesive sediment can be divided into four situations: weak erosion (i.e., τe  > τd), intense erosion (i.e., τe  < τd), intense deposition (i.e., τe  < τd), and weak deposition (i.e., τe > τd ). A two-dimensional numerical model is applied to calculate the temporal and spatial variation of the saturated concentration of cohesive sediment in the Yangtze Estuary. Simulation results shows the following findings. 1) The impact of the fraction of the kth size class in the surface (top) layer of bed material on erosion flux of non-uniform cohesive sediment is necessary to be considered. Otherwise, the calculated saturated concentration of cohesive sediment is greater than the measured. 2) The differences between saturated concentration and the field calculated/measured suspended sediment concentration can be applied to infer bed erosion/deposition characteristics to some extent, and compared it with the measured erosion/deposition result, which in turn verifies the values of  τe and τd in the model. This finding provides insights for the following research on transport and diffusion of cohesive sediment in estuary and coastal areas.
Lava flow hazard of the 2018 Etna eruption: What happened and what could happen
Authors: Bilotta Giuseppe , Calvari Sonia , Cappello Annalisa , Corradino Claudia , Del Negro Ciro , Ganci Gaetana , Hérault Alexis
Published: March 2021

On 24 December 2018 a flank eruption started on Etna from an eruptive fissure opened on the eastern side of the New Southeast Crater (NCSE) at about 3,100 m asl, which in few minutes, propagated to the south-east, overcoming the edge of the western wall of the Valle del Bove (VdB), reaching an altitude of 2,400 m asl and a total length of about 2 km. The eruption, which lasted only three days, produced lava flows from different vents along the eruptive fissure that reached a distance of about 4.2 km and covered an area of about 1 km2. The satellite monitoring of the 2018 Etna eruption was performed using the HOTSAT system using mid and thermal infrared data acquired by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), which provided minimum and maximum estimates for the lava thermal flux, the effusion rate and the lava volume. The SEVIRI-derived effusion rate estimates were used as input of the MAGFLOW model to simulate the actual lava flow field, obtaining a very good fit. We also simulated different eruptive scenarios assuming the lava emission wouldn’t run out in only three days to forecast if, when and how the lava flow could reach the inhabited areas, causing possible significant damage. 
Hydropower potential assessment made easy via the unit geo-hydro-energy index
Authors: Risva Konstantina , Sakki Georgia Konstantina , Efstratiadis Andreas , Mamassis Nikos
Published: March 2021

The design of hydropower works typically follows a top-down approach, starting from a macroscopic screening of the broader region of interest, to select promising clusters for hydroelectric exploitation, based on easily retrievable information. Manual approaches are very laborious and may fail to detect sites of significant hydropower potential. In order to facilitate this kind of studies, we provide a novel geomorphological approach to assess the hydropower potential across river networks. The method is based on the discretization of the stream network into segments of equal length, thus providing a background layer of head differences between potential abstraction and power production sites. Next, at each abstraction point, we estimate the so-called unit geo-hydro-energy index (UGHE), which is a key concept of our approach. UGHE is defined as the ratio of annual potential energy divided by the upstream catchment area, the head difference, and the unit annual runoff of the catchment, which is set equal to 1000 mm. The method is further expanded, to estimate the actual hydropotential, if spatially distributed runoff data are available. All analyses are automatized by taking advantage of the high-level interpreted programming language Python and the open-source QGIS tool. The proposed framework is demonstrated at the regional scale, involving the siting of run-of-river hydroelectric works in the Peneios river basin.
A framework to quantify bias for improved drought forecasting 
Authors: Mammas Konstantinos , Lekkas Demetris F. , Pechllivanidis Ilias
Published: March 2021

The Standardized Precipitation Index (SPI) is one of the most popular indices for characterizing the meteorological drought on a range of time scales.  To date, SPI has been thoroughly used to monitor and predict drought in the precipitation signal and to further support early warning and climate services. While many studies focus on the performance improvement of drought models, there is to our knowledge no reference around the correct computation of SPI in a drought forecasting setting. As SPI is typically computed on the entire data set, prior to model-validation, bias is introduced to both the training and validation sets. This stems from the fact that the distribution parameters of the index are estimated using observations from the validation and test sets leading to information leakage. Here, we propose a modified calculation of SPI oriented for forecasting applications by measuring the bias introduced to the SPI values in the training set. Moreover, we propose the best practice for calculating the SPI during model-validation and encapsulate these in a drought forecasting framework. The proposed framework is further demonstrated using a 50-year data set from Sweden. Our findings suggest that the amount of bias introduced to the training sets increases with increased SPI scale, significantly affecting in some cases more than 80% of the available basins.
Link between opaque cloud properties and atmospheric dynamics in observations and simulations of current climate in the Tropics, and impact on future predictions
Authors: Perpina Miguel , Noel Vincent , Chepfer Helene , Guzman Rodrigo , Feofilov Artem
Published: March 2021

Climate models predict a weakening of the tropical atmospheric circulation, more specifically a slowdown of Hadley and Walker circulations. Many climate models predict that global warming will have a major impact on cloud properties, including their geographic and vertical distribution. Climate feedbacks from clouds, which amplify warming when positive, are today the main source of uncertainty in climate forecasts. Tropical clouds play a key role in the redistribution of solar energy and their evolution will likely affect climate. Therefore, it is crucial to better understand how tropical clouds will evolve in a changing climate. Among cloud properties, the vertical distribution is sensitive to climate change. Active sensors integrated into satellites, such as CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization), make it possible to obtain a detailed vertical distribution of clouds. CALIOP measurements and calibration are more stable over time and more precise than passive remote sensing satellite detectors. CALIOP observations can be simulated in the atmospheric conditions predicted by climate models using lidar simulators such as COSP (CFMIP Observation Simulator Package). Moreover, cloud properties directly drive the Cloud Radiative Effect (CRE). Understanding how models predict cloud vertical distribution will evolve in the future has implications for how models predict the Cloud Radiative Effect (CRE) at the Top of the Atmosphere (TOA) will evolve in the future.

The purpose of our study is to compare, firstly, based on satellite observations (GOCCP) and reanalyzes (ERA5), we will establish the relationship between atmospheric dynamic circulation, opaque cloud properties and TOA CRE. Then, we will compare this observed relationship with the one found in climate model simulations of current climate conditions (CESM1 and IPSL-CM6). Finally, we will identify how model biases in present climate conditions influence the cloud feedback spread between models in a warmer climate.
A new framework for identifying and investigating seasonal climate extremes
Authors: Röthlisberger Matthias , Hermann Mauro , Frei Christoph , Lehner Flavio , Fischer Erich M. , Knutti Reto , Wernli Heini
Published: March 2021

Previous studies have recognized the societal relevance of climatic extremes on the seasonal timescale and examined physical processes leading to individual high-impact extreme seasons (e.g., extremely wet or warm seasons). However, these findings have not yet been generalizing beyond individual case studies since at any specific location only very few seasonal events of such rarity occurred in the observational record. In this concept paper, a pragmatic approach to pool seasonal extremes across space is developed and applied to investigate hot summers and cold winters in ERA-Interim and the Community Earth System Model Large Ensemble (CESM-LENS). We identify spatial extreme season objects as contiguous regions of extreme seasonal mean temperatures based on statistical modeling. Regional pooling of extreme season objects in CESM-LENS then yields considerable samples of analogues to even the most extreme ERA-Interim events, which allow for climatological analyses of their statistical and physical characteristics.

This approach offers numerous opportunities for analyzing large samples of extreme seasons across regions, and several such analyses are illustrated exemplarily. We perform a climate model evaluation with regard to extreme season size and intensity measures and estimate how often an extreme winter like the cold North American 2013/14 winter is expected anywhere in mid-latitude regions. Moreover, we present a large set of simulated spatial analogues to this event, which allows to study commonalities and differences of their underlying physical processes. Finally, substantial but spatially varying climatological differences in the size of extreme summer and extreme winter objects are identified.
Estimating the effective spatio-temporal resolution of integrated water vapor trends based on VLBI, GNSS, and weather model data
Authors: Bamahry Fikri , Balidakis Kyriakos , Heinkelmann Robert , Schuh Harald
Published: March 2021

How far apart can two space geodetic sites be located to consider the integrated water vapor (hereinafter IWV) trends as equal, from a statistical viewpoint? How to do efficient feature selection with a given IWV time series? To address these questions, we utilize spatio-temporal variations of long-term IWV trends that were estimated employing very long baseline interferometry (VLBI), Global Navigation Satellite Systems (GNSS), and numerical weather prediction data (ERA5 reanalysis). We estimate coefficients for several spatial covariance functions; Hirvonen's model proves to be the most precise for our area of interest, Greater Europe. We find that the effective spatial resolution is around 56 km (for error level (p) < 0.05). Our investigations indicate that among else, altitude and proximity to the ocean are key factors affecting the IWV trend decorrelation lengths. We find good agreement between the spatially varying decorrelation lengths and established climate classification systems such as the latest Köppen-Geiger model. Moreover, the IWV trend variation as a function of data span and temporal resolution has been investigated. We find that varying the temporal resolution from one hour up to 30 days does not yield a statistically significant difference (p < 0.05) in the IWV trend and its uncertainty, provided the inherent autocorrelation is factored in and the data span remains. We also find that given the IWV time series length, the spread calculated from the estimated trends varying the start point of the time series, follows an exponential decrease σ(Δt) = 22Δt -1.7 + 0.008.
GNSS-A seafloor geodetic observation capability in 2021 and its applicability to global geodesy
Authors: Yokota Yusuke , Ishikawa Tadashi , Watanabe Shun-ichi , Nakamura Yuto
Published: March 2021

Recently, the GNSS-A (Global Navigation Satellite System – Acoustic combination technique) seafloor geodetic observation technology, developed in the Hydrographic and Oceanographic department in Japan Coast Guard (JCG), was upgraded to be able to monitor a subseafloor interplate coupling condition of about 1 cm/year and an interplate shallow slow slip event of about 5 cm (e.g., Yokota et al., 2018, Scientific Data; Ishikawa et al., 2020, Front. Ear. Sci.). By observing such small-scale seafloor crustal movements, GNSS-A technology makes a decisive contribution to subduction seismology and disaster prevention sciences (e.g., Yokota et al., 2016, Nature; Yokota and Ishikawa, 2020, Sci. Adv.). This technology was achieved by connecting high-precision underwater acoustic ranging technology and high-rate GNSS on a vessel at sea surface.

The GNSS-A, which is carried out all over the world, especially in the Pacific Rim, has been constructed for observation of plate boundary subduction processes and fault movement processes. Unlike the GNSS network, GNSS-A has never contributed to global geodesy within the framework of the Global Geodetic Observing System (GGOS). However, it can be a unique observation method for the construction of the International Terrestrial Reference Frame (ITRF). It can make an important contribution in determining the movement and Euler pole on an oceanic plate that have few land area.

In the future, if an extensive seafloor geodetic observation network as shown by Kato et al. (2018, JDR) will be established, there is a possibility of constructing a next-generation reference frame that completely explains the plate motion on the earth's surface. This presentation will present the current state of the GNSS-A ability and cost and future prospects for the contribution to global geodesy.
Diagnosis of environmental controls on daily actual evapotranspiration across a global flux tower network: the roles of water and energy
Authors: Han Qiong , Liu Qin , Wang Tiejun , Wang Lichun , Di Chongli , Chen Xi , Smettem Keith , Singh Shailesh
Published: March 2021

Relative contributions from environmental factors to daily actual evapotranspiration (ETa) across a variety of climate zones and ecosystem types is a widely open research question, especially regarding the roles played by soil water content (SWC; water supply) and net radiation (Rn; energy supply) in controlling ETa. Here, the boosted regression tree method was employed to quantify environmental controls on daily ETa using the global FLUXNET dataset. Overall, the SWC impact on daily ETa increased with increasing aridity index (Φ). However, unlike the traditional Budyko theory that is applied at annual and mean annual scales, the daily FLUXNET data revealed that Rn still played a pivotal role at most sites (roughly Φ < 4), indicating that Rn could be a leading control on daily ETa even at water-limited sites. The variations in the relative controls of SWC and Rn also partly depended on factors affecting water availability for daily ETa (e.g., vegetation characteristics, soil texture, and groundwater depth). Especially, leaf area index exerted a stronger influence on ETa at drier sites than at relatively humid sites, suggesting that near-surface hydrological processes are more sensitive to vegetation variations due to their ability to extract deep soil water and enhance ETa, particularly under arid and semi-arid climatic conditions. As a result, the net effect of environmental controls other than SWC and Rn on ETa was more important at drier sites. Our findings illustrate how environmental controls on daily ETa change as climate and ecosystem vary, which has important implications for many scientific disciplines including hydrological, climatic, and agricultural studies.
Hazelnut products traceability through Isotope Ratio Mass Spectrometry approach
Authors: Sammarco Giuseppe , Rossi Mattia , Suman Michele , Cavanna Daniele , Dall'Asta Chiara , Iacumin Paola
Published: March 2021

The geographical origin of hazelnuts products is nowadays a relevant aspect of high-quality food characterization. Isotope Ratio Mass Spectrometry (IRMS) could play a key role in origin discrimination. The present study aims to assess the geographical provenience of Italian roasted hazelnuts and paste of hazelnuts, by analysing relative isotopic ratios of carbon, nitrogen, and oxygen, through Elemental Analyzer – and Thermal Conversion – Isotope Ratio Mass Spectrometry. Method development is performed by evaluating test samples repeatability, considering 15 replicates measurements on the same day, reproducibility, considering 30 replicates measurements on two different days, and robustness, considering 30 replicates measurements, varying mass parameter. Preliminary outcomes highlight reproducible and robust results, having acceptable standard deviation values (from 0.07 to 0.3). One-way ANOVA test demonstrates a significant statistical difference between Italian and Georgian hazelnut test samples (ca. 1 δ of difference). A Design of Experiment, for training and validation sets building, is prepared, taking into account factors as harvesting year, variety, processing, and percentage of the peel. A total of n=30 processed hazelnuts lots, from Italy, Turkey, Georgia, and Azerbaijan, are going to be analysed for origin evaluation. Despite further analysis are still in progress, this strategy could potentially be the election method for a lot of food chain traceability since food isotopic abundances reflect ground and climate-related features, typical of precise locations. Moreover, this approach consists of limited or even inexistent sample preparation and provides for high sensitivity.
Excitation of Oxygen Ion Cyclotron Harmonic Waves in the Inner Magnetosphere
Authors: Liu Kaijun , Min Kyungguk , Feng Bolu , Wang Yan
Published: March 2021

Oxygen ion cyclotron harmonic waves, with discrete spectral peaks at multiple harmonics of the oxygen ion cyclotron frequency, have been observed in the inner magnetosphere. Their excitation mechanism has remained unclear, because the singular value decomposition (SVD) method commonly used in satellite wave data analysis suggests that the waves have quasi-parallel propagation, whereas plasma theory reveals unstable modes at nearly perpendicular propagation. Hybrid simulations are carried out to investigate the excitation of these waves. The simulation results show that waves at multiple harmonics of the oxygen ion cyclotron frequency can be excited by energetic oxygen ions of a ring-like velocity distribution. More importantly, analyzing the simulated waves in a three-dimensional simulation using the common SVD method demonstrates that, while the excited waves have quasi-perpendicular propagation, the superposition of multiple waves with different azimuthal angles causes the SVD method to yield incorrectly small wave normal angles. In addition, the scattering of oxygen ions by the excited waves is examined in the simulations. The waves can cause significant transverse heating of the relatively cool background oxygen ions, through cyclotron resonance. The waves may also scatter energetic radiation belt electrons through bounce resonance and transit time scattering, like fast magnetosonic waves.
Suppression of air-sea CO2 transfer by surfactants – direct evidence from the Southern Ocean
Authors: Yang Mingxi , Smyth Timothy , Kitidis Vassilis , Brown Ian , Wohl Charel , Yelland Margaret , Bell Thomas
Published: March 2021

Uncertainty in the CO2 gas transfer velocity (K660) severely limits the accuracy of air-sea CO2 flux calculations and hence hinders our ability to produce realistic climate projections.  Recent field observations have suggested substantial variability in K660, especially at low and high wind speeds.  Laboratory experiments have shown that naturally occurring surface active organic materials, or surfactants, can suppress gas transfer.  Here we provide direct open ocean evidence of gas transfer suppression due to surfactants from a ~11,000 km long research expedition by making measurements of the gas transfer efficiency (GTE) along with direct observation of K660.  GTE varied by 20% during the Southern Ocean transect and was distinct in different watermasses.  Furthermore GTE correlated with and can explain about 9% of the scatter in K660, suggesting that surfactants exert a measurable influence on air-sea CO2 flux.  Relative gas transfer suppression due to surfactants was ~30% at a global mean wind speed of 7 m s-1 and was more important at lower wind speeds.  Neglecting surfactant suppression may result in substantial spatial and temporal biases in the computed air-sea CO2 fluxes.
Subpolar Gyre – AMOC – Atmosphere Interactions on Multidecadal Timescales in a Version of the Kiel Climate Model
Authors: Sun Jing , Latif Mojib , Park Wonsun
Published: March 2021

There is a controversy about the nature of multidecadal climate variability in the North Atlantic (NA) region, concerning the roles of ocean circulation and atmosphere-ocean coupling. Here we describe NA multidecadal variability from a version of the Kiel Climate Model, in which both subpolar gyre (SPG)-Atlantic Meridional Overturning Circulation (AMOC) and atmosphere-ocean coupling are essential. The oceanic barotropic streamfuntions, meridional overturning streamfunctions, and sea level pressure are jointly analyzed to derive the leading mode of Atlantic variability. This mode accounting for about 23.7 % of the total combined variance is oscillatory with an irregular periodicity of 25-50 years and an e-folding time of about a decade. SPG and AMOC mutually influence each other and together provide the delayed negative feedback necessary for maintaining the oscillation. An anomalously strong SPG, for example, drives higher surface salinity and density in the NA’s sinking region. In response, oceanic deep convection and AMOC intensify, which, with a time delay of about a decade, reduces SPG strength by enhancing upper-ocean heat content. The weaker gyre circulation leads to lower surface salinity and density in the sinking region, which eventually reduces deep convection and AMOC strength. There is a positive ocean-atmosphere feedback between the sea surface temperature and low-level atmospheric circulation over the Southern Greenland area, with related wind stress changes reinforcing SPG changes, thereby maintaining the (damped) multidecadal oscillation against dissipation. Stochastic surface heat-flux forcing associated with the North Atlantic Oscillation drives the eigenmode.
Stress State Analysis and Active Tectonics of Çavdarhisar (Kütahya) Province, (NW Anatolia, Turkey) from Pre-Late Cenozoic to Quaternary
Authors: Tunç Gülen , Özden Süha
Published: March 2021

Çavdarhisar (Kütahya) province plays a very important role to understand geology and tectonics of the Western Anatolia. Active tectonics characteristics of the region give major information about the evolution of tectonics of the Çavdarhisar (Kütahya) and surrounding areas especially from Late Cenozoic to present day. In this study, kinematic analysis of observed faults in the field and focal mechanism solutions of earthquakes from this region and surroundings are used to reveal the Late Cenozoic stress states of Çavdarhisar (Kütahya). Kinematic analysis results of the faults give four different stress state (SS) regimes from Pre-Late Miocene to Quaternary. Firstly, a main strike-slip faulting (transpressional) (SS.1) has been developed under a NE-SW local compressional tectonic regime in Pre-Late Pliocene with 32°/31° (σ1) and 124°/10° (σ3) trends and Rm ratio was calculated as 0.616. Secondly and consistently with first regime, a NW-SE trending extensional regime (SS.2) produce a local normal faulting presents a minimum stress with 329°/6° (σ3) trend as in horizontal plane in the same period. Then, a NW-SE trending compressional tectonic regime has been efficient in Late Pliocene. This tectonic regime (SS.3) developed a strike-slip faulting (transtensional) has showing by a maximum stress axis by 325°/19° (σ1) and 60°/8° (σ3) trends and Rm ratio was calculated as 0.499. Finally, in the study area, a tectonic regime change has occurred during Quaternary time interval. This regime (SS.4) is oriented a minimum stress state trend as in horizontal plane by a NE-SW directed extensional regime produce a normal faulting in present day and shows a minimum stress with 58°/17° (σ3) trend and Rm ratio is calculated as 0.549. Focal mechanism solutions of the earthquakes that hit the study area show NNE–SSW extension direction which is consistent with present day extensional regime of Çavdarhisar (Kütahya) and surrounding areas. The reason for the regionally effective NNE–SSW trending extensional regime in western and south western Anatolia is related with complex subduction processes between African and Anatolian plates.

 Key words: Çavdarhisar, Kütahya, kinematic analysis, tectonic regime, active tectonics, stress state
Harmonized web-based information systems for shallow geothermal energy use in Austria
Authors: Steiner Cornelia , Goetzl Gregor , Fuchsluger Martin , Rehbogen Alexander
Published: March 2021

Neither regional development, construction projects nor infrastructure development – structural planning does not fully consider energy supply in Austria (yet). The project “Spatial Energy Planning for Heat Transition” is part of the research initiative “Green Energy Lab”, which has a project life-time from June 2018 to May 2021. It aims to provide a sound basis for the integration of heat in private and public planning processes and for the implementation of the energy infrastructure of the future together with energy providers.

Three Austrian states (Vienna, Styria and Salzburg), their capital cities and pilot-municipalities of all scales work together to provide all information necessary for the implementation of spatial heat-planning – as role model for Austria and other European countries. The GIS-based web-tool “heat-atlas” will provide this harmonized data and serve an information platform for project developers as well as for regional planning, fostering a sustainable use of all available sustainable energy resources and infrastructures to their full extent. The system of the information platform is arbitrarily scalable and is aimed to be expanded to other interested regions of Austria on demand.

One part of this “heat-atlas” is about shallow geothermal energy and covers vertical closed loop and open loop systems. The Geological Survey of Austria developed new methods to estimate capacity and energy resources as well as to show possible limitations of shallow geothermal energy use on property level. The resource calculations combine location-specific parameters such as thermal conductivity, underground temperature and groundwater availability with system-specific parameters such as mode of operation, operational hours, geometry and threshold values demanded by official regulations.

The method provides not only information about the maximum amount of energy available on the property, but also about the cover ratio of the demand. So called level-1 maps show the resources for standardized well-doublets and borehole heat exchangers independently of the property. The calculations for level-2 maps consider site-specific properties such as heating and cooling demand, operational hours and size of the property. This enables the estimation of the overall energy resources and the cover ratio of the property.

The results are shown as maps and as location specific query, which gives a concise summary of all relevant information for one location in form of an automatically generated report. More information about the project is available at http://www.waermeplanung.at/.
Validation of SMAP and AMSR2 satellite soil moisture data over the Critical Zone Observatory in central Ganga plains, North India using ground-based observations
Authors: Dash Saroj , Sinha Rajiv
Published: March 2021

Soil moisture (SM) products derived from the passive satellite missions have been extensively used in various hydrological and environmental processes. However, validation of the satellite derived product is crucial for its reliability in several applications. In this study, we present a comprehensive validation of the descending SM product from Soil Moisture Active Passive (SMAP) Enhanced Level-3 (L3) radiometer (SMAP L3-Version 3) and the Advanced Microwave Scanning Radiometer 2 (AMSR2) Level-3 (Version 1), over the newly established Critical Zone Observatory (CZO) within the Ganga basin, North India. The AMSR2 soil moisture product used here, has been derived using the Land Parameter Retrieval Model (LPRM) algorithm. Four SM derived products from SMAP (L-band) and AMSR2 (C1- and C2- and X-band) are validated against the in-situ observations collected from 21 SM monitoring locations distributed over the CZO within a period from September 2017 to December 2019, for a total of 62 days. Since the remotely sensed SM product has a coarser spatial resolution (here 9 km for SMAP and 10 km for AMSR2), the assessment has been carried out for the temporal variation of the measured values. Four statistical metrics such as bias, root mean square error (RMSE), unbiased root-mean-square error (ubRMSE) and the correlation coefficient (R) have been used here for the evaluation. The SMAP Level-3 products are found to show a satisfactory correlation (R>0.6) compared to the other three SM product. Both the SMAP L3 and the AMSR2 C2 SM shows a negative bias, -0.05 m3/m3 and -0.04 m3/m3 respectively whereas these values are found to be 0.04 m3/m3 and 0.06 m3/m3 for C1 and X bands of AMSR2, respectively. Furthermore, the RMSE between the SMAP L3 and in-situ data is 0.07 m3/m3, which is slightly underperformed when considering the required accuracy of SMAP. This is possibly due to variation in the sampling depth along with the sampling day distribution over CZO. The AMSR2 SM products (C1-, C2- and X-bands) are found to have a higher RMSE than SMAP L3, ranging from 0.08-0.1 m3/m3. In addition, the ubRMSE for all remotely sensed soil moisture product range from 0.06-0.08 m3/m3 with the lowest value for the SMAP L3 and AMSR2 C1. The results in this study can be used further for relevant hydrological modelling along with evaluating various downscaling strategies towards improving the coarser resolution satellite soil moisture.
The GGOS Bureau of Products and Standards
Authors: Angermann Detlef , Gruber Thomas , Gerstl Michael , Heinkelmann Robert , Hugentobler Urs , Sanchez Laura , Steigenberger Peter
Published: March 2021

This presentation gives a summary of the role and the activities of the Bureau of Products and Standards (BPS) to support IAG’s Global Geodetic Observing System (GGOS) in its goal to provide observations and consistent geodetic products needed to monitor, map and understand changes in the Earth’s shape, rotation and mass distribution. In its present structure, the two Committees “Earth System Modeling” and “Essential Geodetic Variables” as well as the Working Group “Towards a consistent set of parameters for the definition of a new GRS” are associated with the BPS. A key objective of the BPS is to keep track and to foster homogenization of adopted geodetic standards and conventions across all IAG components as a fundamental basis for the generation of consistent geometric and gravimetric products. Towards this aim, an updated 2nd version of the BPS inventory of standards and conventions used for the generation of IAG products has been published in the Geodesist’s Handbook 2020. In the framework of the renewing of the GGOS website, the BPS supports the GGOS Coordinating Office in particular regarding the representation of geodetic products. Furthermore, the BPS contributes to the rewriting of the IERS Conventions as Chapter Expert for Chapter 1 “General definitions and numerical standards” and interacts with external stakeholders regarding standards and conventions, such as ISO, IAU, BIPM, CODATA and the UN GGIM Subcommittee on Geodesy, including its Working Group “Data Sharing and Development of Geodetic Standards”.
Secondary Microseisms generated by typhoons in the Northwestern Pacific Ocean
Authors: Benbelkacem Nassima , Stutzmann Eléonore , Schimmel Martin , Farra Véronique , Ardhuin Fabrice , Barruol Guilhem , Mangeney Anne
Published: March 2021

Secondary Microseisms (SM) are recorded by seismometers in the period band 3-10 s. They are generated by the interaction of ocean gravity waves of similar frequencies and coming from nearly opposite directions. Typhoons create such ocean waves, and the purpose of this study is to investigate the relationship between typhoons and microseism source characteristics. We focused our study on the Northwestern Pacific and we analyzed seismic signals recorded by the Alaska array and the corresponding storm catalog. While P body waves enable to characterize the amplitude and the localization of the sources, secondary microseisms are dominated by surface waves. Therefore, we apply beamforming technique to the vertical components in order to highlight the weaker body wave signals. This analysis permits us to track the localization of SM sources every 6 hours. Our results show three cases: In the case of one active typhoon, the positions of SM sources are localized close to the typhoon position. In the case of two nearby typhoons acting simultaneously, the SM sources are localized in between the typhoons. Finally, when the typhoon arrives close to the coast, we observe sources generated by ocean wave reflections. In conclusion, the three mechanisms proposed by Ardhuin et al., (2011) are necessary to explain secondary microseisms generated by typhoons.
Tracking ice-sheet dynamics by detrital feldspar Pb-isotope and 87Rb/87Sr dating during the Middle Miocene Climatic Transition, Weddell Sea, Antarctica
Authors: Neofitu Roland , Mark Chris , O'Connell Suzanne , Kelley Samuel , Rösel Delia , Zack Thomas , Daly J. Stephen
Published: March 2021

Antarctic ice-sheet instability is recorded by ice-rafted debris (IRD) in mid- to high-latitude marine sediment, especially throughout climate transitions. The middle Miocene climatic transition (MMCT), 14.2 to 13.8 Ma, which marks the end of a significant warm period during the mid-Miocene, saw a rapid cooling of ca. 6-7 °C in the high-latitude Southern Ocean. This climatic shift was also accompanied by a global δ18O excursion of ca. 1‰, indicating a time of global cooling and significant Antarctic ice expansion (Shevenell et al., 2004). The MMCT is recorded by numerous IRD-rich sediment horizons in deep-sea sediment cores around the Antarctic margin, reflecting iceberg calving during times of ice-sheet instability. Resolving the locations of iceberg calving sites by detrital provenance analysis during the MMCT will be an important tool for forecasting effects of anthropogenic climate change.

Here we present results of a multi-proxy provenance study by using K- and plagioclase feldspar, selected due to their relative abundance in clastic sediment, and tendency to incorporate Rb (Kfs only), Pb, and Sr at analytically useful concentrations, thus enabling source-terrane fingerprinting. While Pb-isotope fingerprinting is an established method for provenance analysis of glaciogenic sediment (Flowerdew et al., 2012), combining in-situ Sr-isotope fingerprinting with 87Rb/87Sr dating is a novel approach. These techniques are applied to deep-sea core ODP113-694, which was recovered from the Weddell Sea; as this is located ca. 750 km from the continental rise, in 4671.3 m of water. This location is ideal, as it acts as a major iceberg graveyard making it a key IRD depocenter (Barker, Kennett et al., 1988). Within the core, several IRD layers were identified and analysed with preliminary depositional ages of 14 to 14.4 Ma.

We discuss the implications of our results in terms of location of active iceberg calving sites and further consider the viability of our multi-proxy provenance approach to the Antarctic offshore.

Barker, P.F., Kennett, J.P., et al., 1988, Proc. Init. Repts. (Pt. A): ODP, 113, College Station, TX (Ocean Drilling Program).

Flowerdew, M.J., et al., 2012, Chemical Geology, v. 292–293, p. 88–102, doi: 10.1016/j.chemgeo.2011.11.006.

Shevenell, A.E., et al., 2004, Science, v. 305, p. 1766-1770, doi: 10.1126/science.1100061.
Mapping the spatiotemporal development of groundwater drought from data: the 2018-2019 drought in the Netherlands
Authors: Brakkee Esther , van Huijgevoort Marjolein , Bartholomeus Ruud
Published: March 2021

The 2018-2019 drought in northwestern Europe caused severe damage to a wide range of sectors, and has made clear that even in temperate-climate countries adaptations are needed to cope with increasing future drought frequencies. A crucial component of drought strategies is to monitor the status of groundwater resources. However, providing up-to-date assessments of regional groundwater drought development remains challenging due to the limited quality of available data. We set up a time series modelling-based method for data preparation to map the spatiotemporal development of the 2018-2019 groundwater drought in the southeastern Netherlands, based on a large amount of monitoring data. The data preparation method was evaluated for its usefulness and reliability for groundwater drought studies and prediction. The analysis showed that the 2018-2019 meteorological drought caused extreme groundwater drought throughout the southeastern Netherlands, breaking 30-year records almost everywhere. Drought onset and duration were strongly variable in space. Groundwater drought development appeared to be governed dominantly by the spatial distribution of rainfall and the geological-topographic setting. The time series modelling-based data preparation method was found a useful tool for the given situation to enable a detailed, consistent record of groundwater drought development. The time series simulations were generally found to be reliable; however, the use of time series simulations rather than direct measurement series may bias drought estimations especially at a local scale, and underestimate spatial variability. Finally, time series modelling was also found a promising tool for regional-scale drought nowcasting and prediction. Further development of time-series based validation and simulation methods, combined with accessible and consistent monitoring data, will be valuable to enable better groundwater drought monitoring in the future. 
Cluster analysis of the ensembles of EURO-CORDEX simulations
Authors: Kalmár Tímea , Pongrácz Rita , Pieczka Ildikó
Published: March 2021

Climate models play an important role in global and regional climate change research, improving our understanding and predictability of climate behaviour. The CORDEX (Coordinated Regional Downscaling Experiment) program was established to provide a framework for the assessment of Regional Climate Models (RCMs) and to contribute to climate change impact assessment and adaptation processes. The climate simulations are based on multiple dynamical and empirical-statistical downscaling models forced by multiple global climate models (GCMs). The motivation behind the use of multiple models in climate change research is to cover different sources of uncertainties, that is why it is recommended to use all available simulations in climate change studies. However, many climate change impact studies face difficulties (e.g., limited computing resources or free access to climate data) using all the available simulations, and therefore it is quite often the case that only subsets of simulations are used. Another problem is that the ensembles of GCM-RCM simulations are too big to be handled by many impact modellers. The selection of model simulations is subjective in most cases, and it is often reduced by hand-picking climate simulations depending on the partners involved in the project. An objective method can be based on cluster analysis, which is a flexible and unsupervised numerical technique that involves the sorting of data into statistically similar groups. These groups can be either (i) determined entirely by the properties of the data themselves or (ii) guided by user constraints. In the present study, we focus on Central-Eastern Europe, because the model simulations are particularly uncertain in the precipitation and temperature distribution over this region. The aim of the study is to develop a method based on the precipitation and temperature values of 55 EURO-CORDEX simulations for a near-present historical period (1995–2014), which could help to select suitable subsets of ensembles of climate simulations tailored to the needs within climate change impact studies.

 

Acknowledgement: This study is supported by the ÚNKP-20-3 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development and Innovation Fund.
Reference indicators enabling preliminary evaluations of the impact of radioactive releases on agricultural products
Authors: Ferrucci Barbara , Telloli Chiara
Published: March 2021

After the release of high levels of radioactivity into the environment, one of the main concern relates the contamination foodstuffs. In some exposure scenarios the transfer of radionuclides through the food chain to consumers represents a major contribution to human dose. Therefore an accurate estimation of radionuclide activity concentrations in agricultural products is crucial to evaluate the ingestion dose to the population consuming locally produced food. There are many mechanisms contributing to the radioacive contamination of agricultural products as interception, retention, absorption and translocation, due to mechanisms as deposition to the exposed plant surfaces, and/or root uptake. In the last decades several efforts have been spent in developing mathematical models to predict the potential transfers of radionuclides in plants and their concentration in the edible parts. Nevertheless the relative significance of each pathway depends on a large amount of variables and parameters that increase the complexity of the models, moreover the lack of expermental data, often limit the possibility to make any meaningful results. The main aspect that make difficult to predict the uptake of radionuclides by plants is the dynamic nature of the contamination scenarios due primarly to the the growing of plants. Nevertheless, there are some factors that can be considered as ‘static’ for each specific geographic area, and each specific radionuclide, as the soil characteristics, the type of crop, and the behavour of some radionuclides in the environment. In the framework of a preliminary safety assessment of a radioactive release scenario, these factors could be taken as reference indicators of the potential impact on the local human food chain radioactive contamination. In this work we focus on the analysis of the scientific literature pertaining to all experimntal studies in radionuclide plant uptake, from 2000 to 2020. The aims of this analysis is to collect set of some characteristics allowing to classify, in a macroscopic scale, specific reference indicators that most contribute to the radioactive contamination of agricultural products in different geographyc areas.
Simulating detailed spatial patterns of ice shelf basal melt
Authors: Lambert Erwin , Jüling André , Holland Paul , van de Wal Roderik
Published: March 2021

The contact between ice shelves and relatively warm ocean waters causes basal melt, ice shelf thinning, and ultimately ice sheet mass loss. This basal melt, and its dependence on ocean properties, is poorly understood due to an overall lack of direct observations and a difficulty in explicit simulation of the circulation in sub-shelf cavities. In this study, we compare a number of parameterisations and models of increasing complexity, up to a 2D ‘Layer’ model. Each model is aimed at quantifying basal melt rates as a function of offshore temperature and salinity. We test these models in an idealised setting (ISOMIP+) and in a realistic setting for the Amundsen Sea Embayment. All models show a comparable non-linear sensitivity of ice-shelf average basal melt to ocean warming, indicating a positive feedback between melt and circulation. However, the Layer model is the only one which explicitly resolves the flow direction of the buoyant melt plumes, which is primarily governed by rotation and by the basal topography of the ice shelves. At 500m resolution, this model simulates locally enhanced basal melt near the grounding line, in topographical channels, and near the western boundary. The simulated melt patterns for the Amundsen Sea ice shelves are compared to satellite observations of ice shelf thinning and to 3D numerical simulations of the sub-shelf cavity circulation. As detailed melt rates near the grounding line are essential for the stability of ice sheets, spatially realistic melt rates are crucial for future projections of ice sheet dynamics. We conclude that the Layer model can function as a relatively cheap yet realistic model to downscale 3D ocean simulations of ocean properties to sub-kilometer scale basal melt fields to provide detailed forcing fields to ice sheet models.