bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Mesoscale Soil Moisture Patterns on Convective Initiation over the Tibetan Plateau
Authors: Barton Emma , Taylor Christopher , Klein Cornelia , Harris Phil
Published: March 2020

The Tibetan Plateau is the highest and most extensive plateau in the world, profoundly affecting climate and weather in the region. Due to its average elevation of more than 4000m, provides a strong thermal and dynamical forcing in the mid-troposphere during the summer months, fostering the frequent development of intense storms. Mesoscale convective systems (MCSs) are known to be associated with particularly extreme rainfall events and contribute up to ~60% of rainfall over the Tibetan Plateau (TP) and adjacent areas. In particular, MCSs that form on the TP may move off and bring heavy rain and flooding to downstream parts of China, affecting millions of people. A better understanding of the processes that impact MCS genesis over the TP could contribute to improved forecasting of these extreme events. Furthermore, there is strong evidence for accelerated climate warming on the TP, which may affect convection and makes the identification of factors for MCS development even more important.

Previous work in the Sahel has shown that mesoscale soil moisture patterns can influence the initiation of new MCSs, however the relationship has yet to be investigated for the more hydrologically and topographically complex TP. In this study we investigate the impact of mesoscale soil moisture features on convective initiation over the TP during the monsoon season (May – September) using satellite imagery. Convective clouds are identified using the Fengyun-2 cloud top temperature product. Fengyun-2 is a series of geostationary satellites that provide hourly data, allowing us to track systems as they evolve. Land surface temperature anomalies are used as a proxy to map pre-storm mesoscale soil moisture patterns.

Despite the presence of complex topography, we identify a tendency for MCS initiations to occur in the vicinity of mesoscale soil moisture gradients. Our results suggest that improved representation of land-atmosphere coupling on the TP within weather and climate models could impact the entire region.
A physically based Lagrangian procedure for the push-pull test analysis in heterogeneous aquifer
Authors: Maggi Maria Rita , Di Gialleonardo Anna , Perrotta Laura , Petrella Giovanni , Sperati Federico , Zarlenga Antonio
Published: March 2020

Many previous studies showed how the single well push-pull (SWPP) tracer test is a widely used in situ approach to define the aquifer characteristics. The SWPP test usually consists in two main phases: during the first one, the push phase, a tracer solution is injected into the aquifer through a single well; during the second one, the pull phase, the flow is inverted and the solution is extracted from the same well. The solute movement through the aquifer is driven by different phenomena advection dispersion mixing and dilution.By the analysis breakthrough curves (BTCs) obtained in the pull phase is possible to estimate significant transport parameters such as the dispersion and sorption coefficients. The  more common approaches for the BTC interpretation assume the aquifer as homogeneous.

We propose a semi-analytical physically based Lagrangian procedure for the SWPP analysis, mimicking the transport processes taking place in heterogeneous aquifer by a particle tracking procedure. We consider the well fully penetrate a stratified aquifer unbounded laterally. The isotropic log-hydraulic conductivity is normally distributed  log K=Y∈ N(0,σY2) with given vertical integral scale IY,V and unbounded horizontal integral scale IY,H= ∞. The flow field is assumed to be steady state in both phases. The advective transport is driven by the local flow velocities different for each layer; the pore scale dynamics are modelled as Wiener process. Our procedure can be applied to a wide range of heterogeneity degrees Peclet numbers and test duration; the results emphasise how by different test set up it is possible to get different aquifer parameters: for instance a short test duration allows the estimate of the pore-scale dispersion while for longer test duration the solute experiences more formations emphasizing the  effects of the macrodispersion. Finally despite its simplicity our procedure is a useful tool for the SWPP interpretation in heterogeneous aquifers.
A great response from small ecosystem â€“ the last 500 years of history of a kettle hole mire in W Russia
Authors: Mroczkowska Agnieszka , Kittel Piotr , Marcisz Katarzyna , Dolbunova Ekaterina , Gauthier Emilie , Kublitsky Yuri A. , Lamentowicz Mariusz , Mazurkevich Andrey , Płóciennik Mateusz , Tjallingii Rik , Kramkowski Mateusz , Łuców Dominika , Słowiński Michał
Published: March 2020

Peatlands are natural geoarchives which record within organic deposits a picture of the past environmental changes. Depending on the preserved proxy, we are able to reconstruct various aspects of palaeoenvironmental changes, e.g. using pollen (vegetation composition), plant macrofossils (local vegetation changes), testate amoebae and zoological remains (hydrological changes) or XRF scanning (geochemical changes). Here, we investigated changes in land use and climate of western Russia using a range of biotic and abiotic proxies. This part of Europe is characterized by a continental climate, which makes this region very sensitive to climate change, in particular to precipitation fluctuations. Furthermore, in the last two centuries strong human impact in that area has been noticed.  

The Serteya kettle hole mire (55°40'N 31°30'E) is situated in the Smolensk Oblast in Western Dvina Lakeland. Study site is located close to the range of plant communities belonging to the hemiboreal zone, making it an ideal position to trace the plant succession of Eastern Europe. Preliminary dating of the material proves that the average rate of biogenic deposits in the reservoir was approx. 1 m per 600 years. The majority of the European peatlands was in some sense transformed as a result of drainage and land use practices in their basins. Serteya kettle hole mire allowed us to accurately track how a small ecosystem responds to palaeoenvironmental changes. Preliminary results will show the major fluctuations of the mire hydrology accompanied by the changes in the land use in the region. Our goal is also to determine the resistance and resilience of peat bogs to disturbances.
Advancement of the AMSSP for Ground-Based Measurements of the Complete Stokes Vector
Authors: Jänicke Lena , Ruhtz Thomas
Published: March 2020

Climate models which predict the Earth’s temperature and which are a basis for estimating climate change have large uncertainties induced by the lack of understanding of aerosol effects. Polarimetry is the most promising technique to gain information about aerosols and to understand their effect on the climate.

The airborne multispectral sunphotometer and polarimeter (AMSSP) can measure complete polarization information, including circular polarization for the visible spectral range. The transformation of intensity measurements measured by the AMSSP to polarization information is only possible with a sufficient calibration of the instrument. Laboratory calibration measurements resulted in calibration parameters that convert the intensity measurements to accurate polarization information with only small deviations.

On the basis of recent experiences during a previous field campaign, an improved ground-based polarimeter is going to be developed. A Pan-Tilt tracking system allows direct measurements of the sun which enables the optimization of the relative adjustments of the optical paths. The ground-based system allows a flexible measurement geometry within the upper hemisphere without additional mirrors. With this, the impact and uncertainty of the previously used mirror sytsem are eliminated. In addition, it is planned to optimize the optical components of the polarimeter.

The new setup will be tested during the measurement campaign ASKOS in Cape Verde in summer 2020.

 

 
Mapping and quantifying groundwater inflow to the Spree River (Lusatia) and its role in Fe fluxes, precipitation and coating of the river bed.
Authors: Gilfedder Benjamin , Wismeth Fabian , Frei Sven
Published: March 2020

The spatial distribution and temporal dynamics of groundwater inflow to rivers is often poorly defined but central to understanding water and matter fluxes. This is especially true for the Spree River which drains the Lusatia mining district, Brandenburg Germany. In the Spree catchment iron and sulphate fluxes to the river stem from the pyrite rich groundwater system, and the area’s history of open-pit lignite mining and re-flooding of many of these mines at the end of their lifetime. This iron flux threatens the river ecosystem, tourism in downstream communities (Spreewald) and the drinking water of Berlin. Iron is often observed as precipitates along the river bed, as well as colouring the river water yellow-brown, indicating the presence of iron (oxy)hydroxides such as ferrihydrite and goethite. In this work we have used radon as a natural groundwater tracer to delimited areas of active groundwater discharge to both the main Spree River and the Kleine Spree River to better understand the spatial destitution of groundwater input to the system. This was combined with mass-balance modelling to quantify the groundwater flux along the river using the FINIFLUX model. This was complemented by measurement of iron and sulphate concentrations in the steam and stream-near groundwater. During two measurement campaigns during 2018 the total groundwater inflow for a 20 km long reach of the Kleine Spree and a 34 km long reach of the Spree ranged between ~3,000 and ~7,000 m³ d-1 (Kleine Spree) and ~20,000 and ~38,000 m³ d-1 (Spree). Particularly high groundwater inflow was identified (up to 70% of total inflow) along the Spreewitzer Rinne, a local aquifer consisting of excavated mining materials. For the Kleine Spree the dominant groundwater and Fe flux occurred shortly before the confluence with the Spree. For these river reaches large amounts of dissolved iron and sulphate enters the rivers with inflowing groundwater as calculated from the radon data. Using the measured iron and sulphate loadings we calculated that up to 120 tons/day of iron (oxy)hydroxide was retained in the combined Spree and Klein Spree catchments, a large amount of which remains in the mining lakes.
Generating sea-level information for coastal adaptation: a risk management perspective
Authors: Hinkel Jochen
Published: March 2020

Despite the widespread need to use sea-level rise information in coastal adaptation decision making, the production of this information rarely starts from a decision making perspective. This constitutes a major gap, because the specific sea-level information needed for adaptation depends on the type of decision a coastal decision maker is facing. Recent work developed in the context of the World ClimateResearchProgram (WCRP) Grand Challenge “Regional Sea-Level Change and Coastal Impacts” and the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) of the Intergovernmental Panel on Climate Change (IPCC) has started to address this gap by drawing upon the decision analysis literature. This paper presents this work identifying what kind of mean sea-level rise (SLR) information is needed for local coastal adaptation decisions. A special emphasis is placed on the contributions of the melting of the ice sheets of Greenland and Antarctica to global mean SLR, as these processes may contribute significantly to future SLR and, at the same time, are most uncertain. First, different types of coastal adaptation decisions are characterized in terms of decision horizons and users' uncertaintytolerance. Next, suitable decision analysis approaches and sea-level information required for these are identified. Finally it is discussed if and how these information needs can be met given the state-of-the-art of sea-level science. It is found that four types of information are needed: i) probabilistic predictions for short term decisions when users are uncertainty tolerant; ii) high-end and low-end SLR scenarios chosen for different levels of uncertainty tolerance; iii) upper bounds of SLR for users with a low uncertainty tolerance; and iv) learning scenarios derived from estimating what knowledge will plausibly emerge about SLR over time. Probabilistic predictions can only be attained for the near term (i.e., 2030-2050) and for locations for which modes of climate variability are well understood and the vertical land movement contribution to local sea-levels is small. Meaningful SLR upper bounds cannot be defined unambiguously from a physical perspective. Low to high-end scenarios for different levels of uncertainty tolerance, and learning scenarios can be produced, but this involves both expert and user judgments. The decision analysis procedure elaborated here can be applied to other types of climate information that are required for adaptation purposes.
Polarisation Based Interferometric Optical Fibre Geophone Sensor Designed for High Resolution Seismic Detection
Authors: Jena James , Wassin Shukree , Bezuidenhout Lucian , Doucouré Moctar , Gibbon Tim
Published: March 2020

Geophones are essential for monitoring seismic activity to study the structure of the earth for ground surveys, mineral exploration and early warning detection of geo-hazards. Traditional electromagnetic based geophones are fairly effective in detecting micro-seismic activity and ambient signals. Their induction based mass-spring sensing mechanism can however be somewhat performance limiting. Limitations include reduced frequency response, resolution and recovery times between successive activities. This ultimately impacts the sensitivity and performance of the device. In this paper, we present a novel optical fiber geophone sensor that addresses these issues through superior sensitivity, performance and ease of deployment. Our optical fiber geophone is polarization based, single ended and operates on a Michelson interferometric principle. Tests were performed to compare the performance of our optical fibre geophone to that of a commercial electromagnetic geophone. Vibrations of varying magnitude were remotely generated at 1.065 m from both devices. Sensor signal responses to disturbances of energy lower than 1.1 mJ were plotted and analysed. Observed traces from the sensor responses were compared, showing that the fiber geophone has significantly shorter response and recovery times. As a result, the resolution between rapidly succeeding signals is considerably greater for the optical fiber geophone. Sensitivity plots of the amplitude response to the vibration energy gave a scatter of points depicting a higher degree of precision and accuracy for the fiber geophone. Response slopes of 11.70 a.u/mJ and 10.31 a.u/mJ respectively were obtained for the sensitivity of the optical fiber geophone versus the electromagnetic geophone. While the typical spurious frequency is close to 150 Hz for the traditional geophone, the bandwidth of the optical fiber geophone is an order of magnitude greater.

Keywords- Geophone, Optical fibre, Polarisation, Michelson Interferometer
Sensitivity of resolved gravity wave momentum fluxes on different background separation methods in a high resolution simulation.
Authors: Procházková Zuzana , Šácha Petr , Kuchař Aleš , Pišoft Petr , Kruse Christopher
Published: March 2020

Internal gravity waves (GWs) and their interaction with the atmospheric circulation present a complex problem for global climate models (GCMs) due to a variety of spatial and temporal scales involved. GWs and their effects in GCMs are parameterized by employing various simplifications and restrictions
(propagation, spectrum). Also, our incomplete knowledge of the GW properties in the real atmosphere complicates the situation. Global (satellite) observations of the GW activity are spatiotemporally sparse, making the quantification of the GW interaction with the circulation hardly possible. Recently, atmospheric models capable of resolving most of the GW spectrum have been emerging due to the increasing performance of computing systems. It is increasingly acknowledged that a combination of various types of observations with dedicated high-resolution, GW resolving, simulations has a potential to provide the most precise information about GWs. This combination will allow us to better understand the uncertainty of satellite observations of GW activity, which in turn will be used to develop new GW parameterizations or in development of GW resolving models.
In this study, we will analyze sensitivity of GW momentum flux and its divergence on background separation (and other GW detection) methods and approximations (Boussinesq, anelastic) used in the formulas. We analyze data from high-resolution model simulations produced for an observing system simulation experiment of the ISSI team "New Quantitative Constraints on Orographic GW Stress and Drag" (to be introduced in an invited presentation by Ch. Kruse).
The formation of new glacial lakes at the Jostedalsbreen ice cap in southwest Norway and their future implications
Authors: Laute Katja , Beylich Achim A.
Published: March 2020

In recent years, the number and size of glacial lakes in mountain regions have increased worldwide associated to the climate-induced glacier retreat and thinning. Glacial lakes can cause glacial lake outburst floods (GLOFs) which can pose a significant natural hazard in mountainous areas and can cause loss of human life as well as damage to infrastructure and property.

The glacial landscape of the Jostedalsbreen ice cap in south-western Norway is currently undergoing significant changes reflected by progressing glacier length changes of the outlet glaciers and the formation of new glacial lakes within the recently exposed glacier forefields. We present a new glacier area outline for the entire Jostedalsbreen ice cap and the first detailed inventory of glacial lakes which were formed within the newly exposed ice-free area at the Jostedalsbreen ice cap. In detail, we explore (i) the glacial lake characteristics and types and (ii) analyse their spatial distribution and hazard potential.

For the period from 1952-1985 to 2017/2018 the entire glacier area of the Jostdalsbreen ice cap experienced a loss of 79 km2. A glacier area reduction of 10 km2 occurred since 1999-2006. Two percent of the recently exposed surface area (since 1952-1985) is currently covered with newly developed glacial lakes corresponding to a total number of 57 lakes. In addition, eleven lakes that already existed have enlarged in size. Four types of glacial lakes are identified including bedrock-dammed, bedrock- and moraine-dammed, moraine-dammed and ice-dammed lakes. Especially ice- or moraine-dammed glacial lakes can be the source of potentially catastrophic glacier lake outburst floods. According to the inventory of glacier-related hazardous events in Norway GLOFs represent the most common hazardous events besides ice avalanches and incidents related to glacier length changes. Around the Jostedalsbreen ice cap several historical but also recent events are documented. The majority of the events caused partly severe damage to farmland and infrastructure but fortunately no people have been harmed by today.

Due to the predicted increase in summer temperatures for western Norway until the end of this century, it is very likely that the current trend of an accelerated mass loss of Norwegian glaciers will continue. As one consequence of this development, further new lakes will emerge within the newly exposed terrain. The development of new glacial lakes has diverse regional and global socio-economic implications. Especially in mainland Norway, where glaciers and glacier-fed streams have a high importance for hydropower production, tourism and climate research it is essential to gain a better understanding of the possible impacts of glacial lakes for being prepared for risks but also advantages arising from these newly emerging landscape elements.
Stress Drop Mapping in the Northern Chilean Subduction Zone
Authors: Folesky Jonas , Kummerow Joern , Shapiro Serge A.
Published: March 2020

The Northern Chilean subduction zone has been monitored by the IPOC network for more than ten years. During this time period two very large earthquakes occurred, the 2007 MW7.7  Tocopilla earthquake and the 2014 MW8.1 Iquique earthquake. Over the entire subduction zone a vast amount of seismic activity has been recorded and a huge catalog was compiled including over 100000 events (Sippl et al. 2018). With this exceptional data base we attempt a systematic analysis of the stress drops of as many events from the catalog as possible. We apply different estimation techniques, namely the spectral ratio type, the spectral stacking approach, and the lower bound method. A goal of our research is a comparison and possibly a combination of the techniques to obtain reliable and well constrained results.

The data set covers events at the interface, within the subducting plate, crustal events, and intermediate depth events. It therefore bears a great potential to better understand the stress drop distribution within a subduction zone. Also, the long observation interval allows to analyze temporal variations according to pre-, inter-, and post-seismic phases of megathrust earthquakes.   

We present preliminary results where a subset of 730 events with a magnitude range of ML2.7 - ML4.8  was used for analysis with the spectral ratio technique. For these events we show maps of spatial stress drop variation, and we analyze the time dependent stress drop variance. 
Gamma spectra from uranium mining residues simulated for airborne geometries and detectors
Authors: Preugschat Benedikt , Ibs-von Seht Malte
Published: March 2020

Legacies from uranium mining pose an acute risk to human health and the environment in Central Asia in the countries of Kyrgyzstan, Tajikistan, Uzbekistan and Kazakhstan. This risk is due to the emission of radioactive radiation and the potential contamination of groundwater with radionuclides from the mining residues. A precise knowledge of the location and the contained concentrations of these contaminated sites is necessary in order to obtain an assessment of the hazard and to define areas with the highest remediation priority.

The Federal Institute for Geosciences and Natural Resources in Germany (BGR) currently carries out the project DUB-GEM (Development of a UAV-based Gamma spectrometry for the Exploration and Monitoring of Uranium Mining Legacies), funded by the German Federal Ministry of Education and Research. Within the project, an Unmanned Aerial Vehicle (UAV) based system is to be developed with which the exploration of contaminated sites can be carried out both with low risk for the measurement technician and quickly and cheaply. The challenge lies in the nuclide-specific determination and differentiation of heap and tailing materials with airborne measurements and scintillation detectors. Due to the low spectral resolution of such detectors, this was not possible for a long time. However, with new technologies, scintillation materials and better computer algorithms there is now a potential to solve the problem.

In the DUB-GEM project, one of the detectors to be used will be a large volume (600 ml) CeBr3-detector. In preparation for the field campaign in 2021, we calculated theoretical gamma spectra for this detector using Monte Carlo simulations with the program MCNP6. The simulations were done for varying survey parameters such as flying height and speed, as well as for varying source parameters such as nuclide-specific composition and ground distribution of the mining residues to be mapped. The results of the theoretical investigations will be used to design and optimize survey parameters and to estimate minimum detectable activities.
Kinetic-scale plasma turbulence evolving in the magnetosheath: case study
Authors: Rakhmanova Liudmila , Riazantseva Maria , Zastenker Georgy , Yermolaev Yuri
Published: March 2020

Large set of in-situ measurements with high time resolution in the Earth's magnetosheath provides a great opportunity to explore influence of kinetic processes on the turbulent cascade in the collisionless plasma. Recent statistical studies reveal dependence of characteristics of the turbulent spectra on position of the viewing point behind the bow shock. Detailed analysis of dynamics of the turbulence inside the magnetosheath requires a case study prepared in several points. Present study deals with in-situ measurements of kinetic-scale fluctuations in two points located close to one stream line in different parts of the magnetosheath. We analyze fluctuation spectra of ion flux value and magnetic field magnitude in the frequency range 0.01-2 Hz obtained simultaneously from Spektr-R and Themis spacecraft. The range of frequencies corresponds to transition from magnetohydrodynamic range of scales to the scales where kinetic effects become dominant. We demonstrate deviation of turbulent cascade from the shape predicted typically by the models of developed turbulence in the vicinity of the bow shock and in the subsolar magnetosheath. We show the recovery of the spectral shape during plasma propagation toward the tail. Also, we consider influence of the upstream solar wind conditions on the evolution of turbulence in the magnetosheath.
Structure and variability of the Antarctic coastal easterly winds
Authors: King John , Bracegirdle Thomas
Published: March 2020

The belt of climatological easterly (westward) winds that lies to the south of the circumpolar trough of low pressure surrounding Antarctica has received less attention than the westerlies to the north of the trough, yet it plays a crucial role in atmosphere-ocean-cryosphere interactions in the near-coastal region. The westward-directed wind stress associated with the easterly winds drives a coastal westward ocean current and a westward transport of sea ice around the continent. Easterly winds also inhibit the flow of warm water masses from intermediate depths onto the continental shelves, thus protecting coastal ice shelves from enhanced basal melt. We use the ECMWF ERA-Interim reanalysis to study the mean structure and variability of the coastal easterly winds. The surface component of the easterlies generally extends no more than 200 km to the north of the coast. The easterlies are quite shallow (~ 1-2 km) and are relatively weak (generally < 3 m s-1 at the surface in the annual mean) over the ocean but become both deeper (~ 2-3 km) and stronger (~ 7 m s-1) over the steep coastal slopes of the continent. While persistent katabatic flow down these slopes is a source of easterly momentum (through the action of the Coriolis force), the primary driver of the easterlies appears to be the large-scale baroclinicity of the flow, which is enhanced in the coastal region where isentropes are forced to follow the steep coastal orography. Variability of the easterlies on monthly and longer timescales is related to variations in the strength and latitude of the circumpolar trough. On shorter (synoptic) timescales, large variations in the strength of the easterlies at coastal locations are forced by cyclones that move south from the circumpolar trough and decay in the coastal region.
Discontinuities in sediment connectivity controlled by human-environment interaction along the sediment cascade of a mesoscale catchment in Central Germany
Authors: Fuchs Markus , Steup Raphael , Korthiringer Katja , Seregely Timo
Published: March 2020

In many Central European river catchments changes in long-term sediment dynamics are caused by external driving forces (e.g. human impact, climate change). In addition, the sensitivity of fluvial systems to environmental change is controlled by the catchment’s geomorphic connectivity of individual sediment sinks. In this study, we reconstruct the temporal evolution of different types of sediment reservoirs along the sediment cascade in a mesoscale upland catchment to assess its sensitivity to external changes. The chronological evolution of hillslope and floodplain sediments is based on 79 OSL and 83 C14 ages. Our results show that deposition of hillslope sediments coincides with the first evidence for human-induced soil erosion triggered by the earliest European farmers, but were decoupled from the river network for more than two millennia when the aggradation of overbank fines started and steadily increased. Therefore, the connectivity between the colluvial and alluvial sediment sinks of the catchment is mainly controlled by the landscape geometry and frequency and magnitude of erosion, transport and deposition processes.
Spatial Variability of Source and Attenuation Characteristics in Large Ground-Motion Datasets
Authors: Kotha Sreeram Reddy , Weatherill Graeme , Bindi Dino , Cotton Fabrice
Published: March 2020

Ground-Motion Models (GMMs) characterize the random distributions of ground-motions for a combination of earthquake source, wave travel-path, and the effected site’s geological properties. Typically, GMMs are regressed over a compendium of strong ground-motion recordings collected from several earthquakes recorded at multiple sites scattered across a variety of geographical regions. The necessity of compiling such large datasets is to expand the range of magnitude, distance, and site-types; in order to regress a GMM capable of predicting realistic ground-motions for rare earthquake scenarios, e.g. large magnitudes at short distances from a reference rock site. The European Strong-Motion (ESM) dataset is one such compendium of observations from a few hundred shallow crustal earthquakes recorded at a several hundred seismic stations in Europe and Middle-East.

We developed new GMMs from the ESM dataset, capable of predicting both the response spectra and Fourier spectra in a broadband of periods and frequencies, respectively. However, given the clear tectonic and geological diversity of the data, possible regional and site-specific differences in observed ground-motions needed to be quantified; whilst also considering the possible contamination of data from outliers. Quantified regional differences indicate that high-frequency ground-motions attenuate faster with distance in Italy compared to the rest of Europe, as well as systematically weaker ground-motions from central Italian earthquakes. In addition, residual analyses evidence anisotropic attenuation of low frequency ground-motions, imitating the pattern of shear-wave energy radiation. With increasing spatial variability of ground-motion data, the GMM prediction variability apparently increases. Hence, robust mixed-effects regressions and residual analyses are employed to relax the ergodic assumption.

Large datasets, such as the ESM, NGA-West2, and from KiK-Net, provide ample opportunity to identify and evaluate the previously hypothesized event-to-event, region-to-region, and site-to-site differences in ground-motions. With the appropriate statistical methods, these variabilities can be quantified and applied in seismic hazard and risk predictions. We intend to present the new GMMs: their development, performance and applicability, prospective improvements and research needs.
Evaluation of a Hydro-Meteorological Model System for Flood Forecasting of a Mediterranean Basin in Turkey
Authors: Kilicarslan Berina M. , Duzenli Eren , Pilatin Heves , Yucel Ismail , Yilmaz M. Tugrul
Published: March 2020

Floods, which are considered as one of the most destructive extreme weather events, are being more severe issues with changing climate, and they are threatening both human life and property. To address flood hazard issues, this study evaluates the application of a hydro-meteorological model system as an early warning system approach. The Weather Research and Forecasting Hydrological model system (WRF-Hydro), a fully-distributed, multi-physics, multi-scale hydrologic model, has the capability of accurately capturing the flood hydrographs in terms of shape and peak time corresponding to storm precipitation. WRF-Hydro model system is implemented with meteorological forcing data obtained from the Weather Research and Forecasting (WRF) atmospheric model. WRF/WRF-Hydro model system is operated in uncoupled mode. The study area is the Oymapinar Basin in Southern Turkey has complex topographic characteristics, and in the upstream basin area, the river network originates from mountainous region. Five heavy rainfall events occurred between January 2015 and May 2015 in the basin selected to assess the model performance of simulating flood hydrograph. The model calibration process is performed by covering three heavy rainfall events, while two of them are used for validation of the model system. This study provides an initial evaluation for possible coupled atmospheric-hydrological model simulations between WRF and WRF-Hydro model systems for future applications.
On the initial-state assimilation for limited-area air-quality forecasts
Authors: Kouznetsov Rostislav , Sofiev Mikhail
Published: March 2020

An ensemble of 9 regional Air Quality models is being run operationally within CAMS-50 project providing the 3D fields of air-pollutant distribution over Europe. The models are initialized from their previous-day's forecasts for 00Z and run for 4 days forward. The same models are used for near-real-time reanalysis of the previous day involving the air-quality observations to adjust the modelled  fields via data assimilation methods, such as 3D-var or optimal-interpolation procedures.  In this set-up the observed near-real-time data do not affect the forecasts.  Development of a method to improve the forecast quality by using the assimilated fields from the previous-day analysis is one of the goals for the CAMS-61 project.

As a prototype evaluation for this study, we made several tests with SILAM model (http://silam.fmi.fi) initializing the simulations from the assimilated or non-assimilated states and evaluated the evolution of the model skill scores along the forecast lead time. The tests were made for summer and winter seasons and for initialization time of 00Z vs 12Z.  In order to generalize the results, and make them independent on particular implementation of 3D-VAR in SILAM, the tests were made also with initialization from the analyses made with other CAMS-50 models.  That experiment utilized the list of species and vertical available in the CAMS-50 product catalog. 

The results of the simulation corroborated with our earlier studies that showed a quite quick relaxation of the scores for runs initialized from analyses to the free-run state: with certain variability between the species, the runs converged to the free-run trajectory generally within several hours.  We also investigated the issues connected with initialization from the incomplete set of species and sparse vertical, which might make the scores of the forecast initialized from the incomplete assimilated model state being worse than the ones from the free-run model.

 
Radar Corner Reflector installation at the OCA geodetic Observatory (France)
Authors: Collilieux Xavier , Courde Clément , Fruneau Bénédicte , Aimar Mourad , Schmidt Guillaume , Delprat Isabelle , Pesce Damien , Wöppelmann Guy
Published: March 2020

Geodetic observatories play a fundamental role in the determination of the International Terrestrial Reference System releases. They host several geodetic permanent instruments whose coordinates can be determined at the centimeter level or better. They comprise Global Navigation Satellite System (GNSS) permanent antenna/receivers, Satellite Laser Ranging (SLR) stations, Very Long Baseline Interferometry (VLBI) telescope and Doppler Orbitography Integrated by Satellite (DORIS) beacons. The Calern site of the Observatoire de la Côte d’Azur (OCA) is an example of such a multi-technique site located in the South of France. It hosts a DORIS beacon, a SLR/LLR station and two GNSS permanent stations.

 

In the process of determining coordinates of geodetic instruments in a unified reference frame, the relative positions of the instruments at co-location sites are integrated in the ITRF combination. Thanks to the additional measurements obtained from local surveys, it is possible to determine global biases between coordinates determined by individual space geodetic techniques, and express them in the same reference system. An additional fundamental assumption of the combination process is that stations located on the same site do not move with respect to each other. Spaceborne Synthetic Aperture Radar Interferometry (INSAR technique), is an interesting tool to evaluate that hypothesis as it allows measuring ground displacements in the line of sight of the satellite,  and has been used only occasionally in the past for this purpose,. Notably, the Persistent Scatterer (PS) Interferometry enables determining time series of ground displacements on particular scatterers exhibiting phase stability in a stack (or series ?) of SAR images. To ensure the existence (or presence ?) of such PS, artificial corner reflectors can be installed.

 

We present the procedure that we adapted from Parker et al. (2007) to install and validate the installation of a corner reflector at OCA observatory, close to the currently operating GNSS, SLR and DORIS stations, specifically designed for Sentinel-1 satellite. An initial local tie survey was carried out to assess the stability of the reflector through time.
Rare Earth Elements – Environmental occurrence and mobilities
Authors: Sager Manfred
Published: March 2020

Because the abundances of rare earth elements are strongly intercorrelated, lacking data can be estimated from adjacent element concentrations. Because Ce can be oxidized to Ce(IV) and Eu can be reduced to Eu(II), deviations from the calculated values have been defined as positive or negative anomalies. The anomalies permit conclusions of mineral weathering, transportation and adsorption.

Anomalies detected in soils did not cause respective anomalies in apple leaves, blossom leaves nor fruits, which prevents conclusions of geographical origin. In the apple plants, Ce showed negative anomalies throughout, particularly in the blossom leaves. To the contrary, Eu showed positive anomalies throughout, particularly in the green leaves, which suggests uptake similar to Ca.

In green leaves (apples) growing in the temperate climatic zone, concentrations of rare earth elements increase with age, like for other elements of low physiological interaction also, whereas nutritional and essential trace elements remain constant or decrease.

 
Performance Evaluation of Cloud Analysis in GRAPES 3km Model over Northwest China
Authors: Ren Xuwei , Shao Aimei , Liu Weicheng , Chen Xiaoyan
Published: March 2020

Cloud analysis module (GCAS) in GRAPES model can combine radar reflectivity data, satellite data and surface observations to provide there-dimensional cloud information. To show application effect of GCAS on 3-km resolution forecasts in arid and semi-arid areas of Northwest China, three sets of forecast experiments were conducted with GRAPES_Meso model, which includes control experiment (Con_exp), gcas experiment (Gcas_exp) and hot-start experiment (Hot_exp). The impact of cloud analysis on the prediction effect was investigated using 13 heavy rainfall cases and one month continuous experiments.

These experimental results show the use of cloud analysis can significantly improve forecasting skills of precipitation. Compared with hourly precipitation observations, Gcas_exp performed better than Con_exp and Hot_exp, which gets a higher threat scores of precipitation both for 13 cases and for one-month continuous experiments. Hot_exp presented an positive effect only in the first few hours. Oftentimes, Hot_exp got a worse forecast than Con_exp after the first several hours. In addition, gcas_exp has a positive effect on the prediction of 2m temperature, 10m wind and other variables, but forecasted composite reflectivity was stronger than its observations. Hot_exp can reduce this strength bias to some extent.
Space-time characteristics of areal reduction factors and precipitation mechanisms
Authors: Breinl Korbinian , Müller-Thomy Hannes , Blöschl Günter
Published: March 2020

We link areal reduction factors (ARFs, the ratio of annual maxima catchment precipitation and point precipitation) to the dominating precipitation mechanisms in Austria (84,000km²), using a new efficient method of estimating ARFs based on block kriging. A better understanding of the precipitation mechanisms help assess the plausibility of the ARFs estimated, but ARFs likewise contribute to a better understanding of the precipitation mechanisms as they are a fingerprint of the spatial statistical behavior of extreme precipitation. Our main focus is on two sub-regions in the West and East of Austria, dominated by stratiform and convective precipitation, respectively. ARFs are estimated using rain gauge data with hourly resolution across five durations. ARFs decay faster with increasing area in regions of pronounced convective activity than in regions dominated by stratiform processes. Low ARF values are linked to increased lightening activity (as a proxy for convective activity), but low ARFs can likewise occur in areas of reduced lightning activity as, in summer, convective precipitation can occur everywhere in the country. ARFs tend to decrease with increasing return period, possibly because the contribution of convective precipitation is higher. Our analysis is a key component towards a better understanding of the hydrometeorology in the region, as the process links of the ARFs relate to the space-time scaling of floods.
Social science for hydrologists: considerations when doing fieldwork with human participants
Authors: Rangecroft Sally , Banks Eddie , Day Rosie , Di Baldassarre Guiliano , Frommen Theresa , Hayashi Yasunori , Höllermann Britta , Lebek Karen , Mondino Elena , Rohse Melanie , Rusca Maria , Wens Marthe , Van Loon Anne
Published: March 2020

Water is at the core of many current and future global challenges, which involve hydrological, technical and social processes. Therefore, successful interdisciplinary research on how water-related issues interact with human activities, actions and responses is increasingly important. Qualitative data and diverse perspectives provide much-needed information to improve our understanding and management of water-related issues. To collect this information, hydrologists are increasingly conducting fieldwork with human participants (e.g. individuals, policy-makers, community leaders, government representatives, etc.) themselves, and collaboratively with others. Although collaboration between hydrologists and social scientists in interdisciplinary projects is becoming more common, several barriers, including lack of understanding and experience, can result in hydrologists and social scientists remaining somewhat separate during research, leading to suboptimal research outcomes. Hydrologists who are planning and undertaking fieldwork involving human participants may be underprepared because they are unfamiliar with key social science approaches and concepts. Therefore, here, we help guide hydrologists to better understand some important issues to consider when working with human participants, to facilitate more collaborative research.

As a group of social, natural, and interdisciplinary scientists, we discuss a number of important elements of fieldwork involving human participants that hydrologists might be unfamiliar with, or might have different approaches to than social scientists. These elements include good ethical practice, research question frameworks, power dynamics, communication of science (e.g. participatory mapping, photovoice, videography, and interactive graphs), and post-fieldwork reflections. There are also issues to consider when working collaboratively with social scientists, such as vocabulary differences and different methodologies and data collection approaches (e.g. interviews, focus groups, questionnaires, workshops, ethnography).

We believe that by introducing hydrologists (and natural scientists in general) to some of the key considerations when working with human participants in the field, more holistic, ethical, and successful research outcomes can be achieved. We also want to stress that collaboration with social scientists stays important and research ethics, design, participant involvement, and results, may be compromised without the input and experience of social scientists themselves. Facilitating these collaborations between the natural and social sciences will improve interdisciplinary water research, resulting in a better understanding of the interactions between water and society.
Occurrence of earthquake doublets in the light of the ETAS model
Authors: Grimm Christian , Käser Martin , Küchenhoff Helmut
Published: March 2020

While Probabilistic Seismic Hazard Assessment is commonly based on earthquake catalogues in a declustered form, ongoing seismicity in aftershock sequences is known to be able to add significant hazard, which can also increase the damage potential to already affected structures in risk assessment. Especially so-called earthquake doublets (multiplets), i.e. a cluster mainshock being followed or preceded by one (or more) events with a similarly strong magnitude occurring within pre-defined temporal and spatial limits, can cause loss multiplication effects to the insurance industry, which therefore has a pronounced interest in investigating the frequency of earthquake doublets to happen worldwide. A widely used method to analyse and simulate the triggering process of earthquake sequences is the Epidemic Type Aftershock Sequence (ETAS) model. We estimate the ETAS model parameters for some regional areas and produce synthetic catalogues, which are then analysed particularly with respect to the occurrence of earthquake doublets and compared to the observed history. Also, different seismic subduction-type regions in the world are pointed out to have shown differing relative frequencies of earthquake doublets. Regression models are used to study whether certain mainshock and local, geophysical properties such as magnitude, dip and rake angle, depth, distance to subduction plate interface and velocity of converging subduction plates nearby show explanatory power for the probability of a cluster containing an earthquake doublet.
Energy conversion at the terrestrial bow shock
Authors: Hamrin Maria , Lopez Ramon , Dredger Pauline , Gunell Herbert , Goncharov Oleksandr , Pitkänen Timo
Published: March 2020

At Earth’s bow shock, the supersonic solar wind is slowed down and deflected around the magnetosphere. To many this is "just a bow shock", a simple and quite passive element of solar-terrestrial physics. However, it has recently been realized that the bow shock plays a significantly more important role with currents on the bow shock connecting through the magnetosheath to the magnetospheric current systems. The bow shock current cannot close locally, since the magnetic field compression in the magnetosheath cannot be maintained globally. The bow shock current is inevitably a generator current extracting mechanical energy from the supersonic solar wind, and feeding it to other processes such as acceleration of the magnetosheath flow, local particle acceleration at the bow shock and dissipation in the distant ionosphere. Here we use data from the first dayside season of the Magnetospheric Multiscale (MMS) mission to investigate the generator properties of the terrestrial bow shock. Typically, the main shock ramp shows clear generator properties, but for some of the more turbulent bow shocks, generator properties may also be observed slightly downstream the ramp. This may be due to effects from shock motions and shock nonstationaity and reformation. Moreover, sometimes a weaker load can be seen in the upstream foot region due to local particle acceleration. We also find that the generator capacity of the bow shock decreases with decreasing bow shock angle as well as with increasing upstream plasma beta and solar Mach number. A better understanding of the energy conversion properties of the terrestrial bow shock will be useful also for the understanding of other astrophysical shock currents. The currents must close somewhere and deposit energy somewhere.