bluuebunny/crossref_metadata_2025 huggingface dataset:
Interhemispheric comparison of the ionospheric electron density response during geomagnetic storm conditions
Authors: Habarulema John Bosco , Bergeot Nicolas , Chevalier Jean-Marie , Pinat Elisa , Buresova Dalia , Matamba Tshimangadzo , Katamzi-Joseph Zama
Published: March 2020

The ionospheric electron density response to the occurrence of geomagnetic storms remains one of the challenges that is less understood partially on both short and long-term scales. This is even more complicated given that different locations within the same latitude region (for example in mid-latitudes) at times show different electron density responses as a result of complex dynamic and electrodynamics processes that may be present during one storm duration.  Mid-latitude regions are influenced by storm induced processes originating from both low and high latitudes. Using a combination of ionosonde and Global Navigational Satellite Systems (GNSS) observations, we show differences and or similarities in the electron density response during selected storm periods in both northern and southern hemisphere over the Europe-African sector. Physical mechanisms at play within different storm phases are explored using both observations and empirical modeling efforts.  
Updated determination of earthquake magnitudes at the Swiss Seismological Service
Authors: Racine Roman , Cauzzi Carlo , Clinton John , Fäh Donat , Edwards Benjamin , Diehl Tobias , Heimers Stefan , Deichmann Nicholas , Kästli Philipp , Haslinger Florian , Wiemer Stefan
Published: March 2020

The Swiss Seismological Service (SED; http://www.seismo.ethz.ch) at ETH Zürich is the federal agency in charge of monitoring earthquakes in Switzerland and neighboring areas, and for the assessment of seismic hazard and risk for the region. The SED seismic network largely relies on software and databases integrated in the SeisComP3 monitoring suite for waveform acquisition, automatic and manual event processing, event alerting, web infrastructure, data archiving and dissemination. Data from all digital seismic stations acquired by the SED over the last 30 years - broadband (presently ~230), strong-motion (~185), short-period (~65), permanent and temporary - are homogeneously integrated in the seismic network processing tools and products. Waveform data from the Swiss National Seismic Networks are openly available through the SED website and ORFEUS EIDA / Strong-Motion (http://orfeus-eu.org/data/) data gateways. The SED earthquake catalogue is publicly available through FDSN Event web services at  the SED (http://arclink.ethz.ch/fdsnws/event/1/). The Swiss seismic hazard maps are integrated in the EFEHR portal (http://www.efehr.org). The SED is updating its strategy for magnitude determination to make it fully consistent with the state-of-the-art in engineering seismology and seismic hazard studies in Switzerland, and to optimise the use of its dense seismic monitoring infrastructure. Among the planned changes are the: (a) adoption of a new ML relationship applicable in the near-source region at epicentral distances smaller than 15-20 km; (b) inclusion of ML station corrections based on empirically observed (de)amplification with respect to the Swiss reference rock velocity model and associated predictions; (c)  seamless computation of Mw based on spectral fitting of recorded FAS using a Swiss specific model. In this contribution we present and discuss the updated magnitude computations for a playback dataset of thousands of recorded earthquakes, and compare them with the current official estimates. We discuss the expected impacts of the new magnitude determination strategy on the SED event processing chain in SeisComP3, the SED catalogues and other seismological products. We welcome community feedback on our planned transition strategy.
On the time-varying characteristic of the 6-year oscillation signal in length-of-day
Authors: Duan Pengshuo , Xu Cancan , Xu Xueqing , Huang Chengli
Published: March 2020

A significant 6-year oscillation (SYO) signal existing in the length-of-day (LOD) variations may reflect the fast dynamics of the Earth cores. The time-varying characteristic (TVC) of this signal may reveal the relevant details on the geophysical excitation process. However, it is still debate about the TVC of the SYO. Our previous works indicated that the SYO signal was showing an obviously decaying trend during 1962~2012 based on the normal Morlet wavelet transform (NMWT) method, while other works did not show the similar decaying result based on the other methods (e.g., the least square fitting- LSF). Here, in order to solve this controversial issue, we revisit the SYO and its TVC. Through a lot of numerical simulation tests, NMWT method is further confirmed to be a good approach to quantitatively recover the target damped harmonic signals from the complex background noises, but the classical LSF method can destroy the original harmonic signal. This work indicates that the unattenuated SYO result obtained by the LSF method is not reliable. In addition, this work further analyzes the LOD data during a longer span (i.e., 1840~2018) and extracts the SYO result in the time domain, the result of which  shows: 1) the amplitude modulation phenomenon of the SYO itself on the longer time span, revealing the relevant excitation information within the Earth system; 2) a decreasing trend of the SYO signal in its amplitude after 1960s, which further supports the current SYO decaying result during 1962~2019. This recovered SYO result during a longer time-span obtained by this work is significant to understand the nature of the SYO change and its excitation process.
Geochemical significance and Formation of Suçatı Pb-Zn Deposits – Eastern Taurides
Authors: Bakkalbasi Ali Erdem , Bayram Hatice Nur , Kumral Mustafa , Unluer Ali Tugcan
Published: March 2020

Geochemical significance and Formation of  Suçatı Pb-Zn Deposits – Eastern Taurides

Hatice Nur Bayram(1)*, Ali Erdem Bakkalbaşı (1)*, Mustafa Kumral(1), Ali Tuğcan Ünlüer(1)

(1)Istanbul Technical University, Department of Geological Engineering, Istanbul/Turkey

(*E-mail: hnnurbayram@gmail.com)

 

The Middle Tauride Orogenic Belt is a productive enviroment in terms of Pb-Zn ore deposits, mostly associated with Permian aged dolomitized, shallow marine platform type carbonate rocks. There have been many studies on the origin of the ore deposits in the region, there are two important approaches that stand out for the formation of the ore deposits: the first theory is hydrothermal deposits with magmatic origin, and the other theory is Missisippi Valley-type (MVT) deposits related with the carbonate rocks commonly found in the region. Field studies at the Suçatı (Kayseri – Yahyalı, Central Anatolia, Turkey, East of Aladağlar extension of the Taurides) ore district in the Aladağ geologic unit indicate that the deposits in the region are associated with Paleo-Tethys limestones, fossiliferous limestones and dolomitic limestones. Mineralization is related to Lower Permian aged carbonate rocks include primary mineralization ore minerals as galena, sphalerite, smithsonite and goethite and as a product of hydrothermal activity, calcite mineral filled within fractures and cracks represents gangue minerals. As a result of geochemical analysis of the samples collected from the ore zones, PbO values range between 25.93% - 0.012%, ZnO values range between 51.01% - 0.042%, Fe2O3 values range between 42.81% - 10.21%. In conclusion hydrothermal activities closely related with compressional and extentional tectonic regimes took place in multiphase mineralization.

 

Keywords: Pb-Zn Deposits, MVT, Taurides, Yahyalı
Influence of grass invasion on soil parameters in a Belgian heathland
Authors: Arnauts Natascha
Published: March 2020

Until the early nineteenth century, the Belgian landscape was characterized mainly by the presence of heathland, a typical cultural landscape with important ecosystem services. Since then, urbanisation has led to the conversion of large stretches of heathland to be converted to forest, arable land or cities. Increased concentrations of exhaust gasses result in elevated concentrations of nitrogen (N) in the atmosphere. Through rainfall this N enters the soil and is fixed via precipitation reactions, which in turn leads to higher N soil concentrations. Because Calluna vulgaris (common heather; the dominant plant species in heathlands) thrives on soil containing low nutrient concentrations,  it is now being outcompeted by plant species more suited to these altered nutrient levels. As a result, the heathland is slowly evolving into grassland and, consequently, its ecosystem services and soil nutrient cycling are changing.

Here, we present the preliminary results of our investigation into the influence of grass encroachment on nutrient cycling in heathlands. For this research question, we set up a gradient of 14 plots of increasing grass cover from 0 to 100%. The woody structures of heather contain high concentrations of lignin, consequently the 100% heather plots have a more recalcitrant organic input. It is therefore hypothesized that the nutrient turnover in these plots are lower than in the 100% grass plots since grass has lower lignin concentrations and thus higher litter quality. We set up a series of measurements on pooled and homogenized soil samples of these 14 plots. We measured N mineralization and nitrification, 2 enzymes and relevant soil parameters. Interestingly, there were no significant results found for the N mineralization and nitrification. The measurement of the enzymes chitinase and phosphatase showed a significant correlation, indicating the impact of vegetation on the enzymatic activity, and therefore on the soil nutrient cycle.
Volcanically induced stratospheric water vapor changes
Authors: Kroll Clarissa , Azulay Alon , Schmidt Hauke , Timmreck Claudia
Published: March 2020

Stratospheric water vapor (SWV) is important not only for stratospheric ozone chemistry but also due to its influence on the atmospheric radiation budget.

After volcanic eruptions, SWV is known to increase due to two different mechanisms: First, water within the volcanic plume is directly injected into the stratosphere during the eruption itself. Second, the volcanic aerosols lead to a warming of the lower stratosphere including the tropopause layer. The increased temperature of the cold point allows an increased water vapor transit from the troposphere to the stratosphere. Not much is known about this process as it is obscured by internal variability and observations are scare.

To better understand the increased SWV entry via the indirect pathway after volcanic eruptions we employ a suite of large volcanically perturbed ensemble simulations of the MPI-ESM1.2-LR for five different eruptions strengths (2.5 Mt, 5 Mt, 10 Mt, 20 Mt and 40 Mt sulfur). Each ensemble consists of 100 realizations for a time period of 3 years.

Our work mainly focuses on the tropical tropopause layer (TTL) quantifying changes in relevant parameters such as the atmospheric temperature profile and the consequent increase in SWV. A maximum increase of up to 4 ppmm in the first two years after the eruption is found in the case of the 40 Mt eruption. Furthermore the large ensemble size additionally allows for an analysis of the statistical significance and influence of variability, showing that SWV increases can already be detected for the 2.5 Mt eruption in the ensemble mean, for single ensemble members the internal variability dominates the SWV entry up to an eruption strength of 10 Mt to 20 Mt depending on the season and time after the eruption. The study is complemented by investigations using the 1D radiative convective equilibrium model konrad to understand the radiative effects of the SWV increase.
Estimation of high-resolution soil moisture using machine learning, satellite observations and ground measurements. A case study in a hilly agricultural region
Authors: Zappa Luca , Forkel Matthias , Xaver Angelika , Dorigo Wouter
Published: March 2020

Remotely sensed data from microwave sensors have been successfully used to retrieve soil moisture on a global scale. In particular, passive and active microwave sensors with large footprints can observe the same location with a (sub-)daily frequency, but typically are characterized by spatial resolutions in the order of tens of km. Therefore, such coarse scale products can accurately capture the temporal dynamics of soil moisture but are inadequate in providing spatial details. However, several agricultural and hydrological applications could greatly benefit from soil moisture observations with a sub-kilometer spatial resolution while preserving a daily revisit time.

Here, we present a framework for downscaling coarse resolution satellite soil moisture products (ASCAT and SMAP) to high spatial resolution. In particular, we build robust relationships between remotely sensed soil moisture and ancillary variables on soil texture, topography, and vegetation cover. Such relationship is built through Random Forest regressions, trained against in-situ measurements of soil moisture. The proposed approach is developed and tested in an agricultural catchment equipped with a high-density network of in-situ sensors. Our results show a strong consistency between the downscaled and the observed spatio-temporal patterns of soil moisture. Furthermore, including a proxy of vegetation cover in the Random Forest regressions results in considerable improvements of the downscaling performance. Finally, if only limited training data can be used, priority should be given to increase the number of sensor locations to adequately cover the spatial heterogeneity, rather than expanding the duration of the measurements. 

Future research will focus on including additional ancillary variables as model predictors, e.g. Land Surface Temperature or backscatter, and on applying the downscaling framework to other regions with similar environmental and climatic conditions.
Simulating Antarctic subglacial hydrology processes underneath Pine Island Glacier, West Antarctica, using GlaDS model in Elmer/Ice
Authors: zhang yufang , Moore John , Wolovick Michael , Gladstone Rupert , Zwinger Thomas , guo xiaoran
Published: March 2020

Abstract: Very little is known about the subglacial hydrologic system under the Antarctic Ice Sheet due to the difficulty of directly observing the bottom of the ice sheet. Hydrology modeling is a powerful tool to simulate the spatial distribution of crucial hydrologic properties under the ice sheet. Here, we use the state-of-art two-dimensional Glacier Drainage System model (GlaDS) to simulate both distributed sheet flow and continuous channels under Pine Island Glacier (PIG), West Antarctica, one of the largest contributors to sea level rise in Antarctica.

We adopt an unstructured triangular mesh which enables channels to form along element edges. We drive the model with meltwater computed from an inversion and steady temperature simulation of PIG using a Stokes flow ice dynamic model. Our domain comprises the full PIG catchment. We aim to study the pattern and development of water pressure, hydraulic potential, water sheet thickness and discharge, as well as channel area and flux, which together describe the state of the basal system.

Our results for hydraulic potential correctly route water towards the grounding line, while we find near-zero effective pressure underneath the main trunk of PIG, consistent with the low basal drag and low driving stress there. This has implications for the representation of sliding in ice dynamic models: typical assumptions about hydrology connectivity to the ocean will overestimate effective pressure. When run forward in time, efficient channels evolve near the grounding line indicating an efficient drainage system where water fluxes are high in the downstream part of the PIG.

By applying GlaDS to a real marine ice sheet catchment we can better understand how basal hydrology modulates ice dynamics through basal sliding. We plan to compare our model predictions of effective pressure and drainage system with driving stress and inversions of basal drag. This will allow us to see the relationship between basal hydrology and basal sliding under PIG, and provide us better tools to predict the evolution of the region in view of future climate scenarios. Moving forward, we plan to couple the hydrology model with the ice dynamics model to make more accurate projections of sea level rise from PIG.

Key Words: West Antarctica, subglacial hydrology, drainage system, GlaDS, Elmer/Ice, Pine Island Glacier
Impact of emissions and long-range transport on Air Quality in Delhi
Authors: Graham Ailish , Pope Richard , Chipperfield Martyn , Stirling Ellen
Published: March 2020

Delhi is the world’s most polluted capital city, with annual mean concentrations of PM2.5, O3 and NO2 well above the safe legal limits for Europe. Exposure to these pollutants over short and long-time scales is associated with increases in diseases such as heart disease, stroke and lower respiratory tract infections. Local NO2 concentrations vary by month and season and are controlled by both emissions and meteorology. Locally, vehicle pollution contributes to 67% of the total air pollution load and 48% of NOx. The vehicle population has increased substantially in recent years due to an increase in the number of vehicles travelling into Delhi each day from surrounding areas. High pollution episodes, especially in winter, also contribute to the high annual mean observed. This may be due to the trapping of pollutants in a shallow, stable boundary layer or through the long-range transport of pollutants from surrounding regions to Delhi under favourable wind directions. However, the relative contribution of local vs regional emissions has not been quantified previously. This inhibits the introduction of targeted policies to reduce concentrations in the city.

We use observational datasets to quantify the relative contribution of local and regional emissions to local NO2 air quality in Delhi rather than running a computationally expensive atmospheric chemistry transport model (Stirling et al., 2020). We combine satellite data from the TROPOMI instrument on the Sentinel 5 – Precursor (S5P) platform with back-trajectories, from the Reading Offline Trajectory Model (ROTRAJ). This allows us to investigate how different wind directions affect the relative contributions of local and regional NO2 pollution to Delhi NO2. We will then quantify the contribution of different regions and sectors to NO2 in Delhi by combining the back-trajectories with a high resolution emission inventory for India and Delhi. This method also allows us to consider future emission control scenarios and quantify their impacts on air quality in Delhi.

 
Degrading permafrost threatens Arctic nature and built environment
Authors: Hjort Jan , Karjalainen Olli , Aalto Juha , Westermann Sebastian , Romanovsky Vladimir , Nelson Frederick , Etzelmüller Bernd , Luoto Miska
Published: March 2020

Arctic earth surface systems are undergoing unprecedented changes, with permafrost thaw as one of the most striking examples. Permafrost is critical because it controls ecosystem processes, human activities, and landscape dynamics in the north. Degradation (i.e. warming and thawing) of permafrost is related to several hazards, which may pose a serious risk to humans and the environment. Thaw of ice-rich permafrost increases ground instability, landslides, and infrastructure damages. Degrading permafrost may lead to the release of significant amounts of greenhouse gases to the atmosphere and threatens also biodiversity, geodiversity and ecosystem services. Thawing permafrost may even jeopardize human health. Consequently, a deeper understanding of the hazards and risks related to the degradation of permafrost is fundamental for science and society.

To address climate change effects on infrastructure and human activities, we (i) mapped circumpolar permafrost hazard areas and (ii) quantified critical engineering structures and population at risk by mid-century. We used observations of ground thermal regime, geospatial environmental data, and statistically-based ensemble methods to model the current and future near-surface permafrost extent at ca. 1 km resolution. Using the forecasts of ground temperatures, a consensus of three geohazard indices, and geospatial data we quantified the amount and proportion of infrastructure elements and population at risk owing to climate change. We show that ca. 70% of current infrastructure and population in the permafrost domain are in areas with high potential for thaw of near-surface permafrost by 2050. One-third of fundamental infrastructure is located in high hazard regions where the ground is susceptible to thaw-related ground instability. Owing to the observed data-related and methodological limitations we call for improvements in the circumpolar hazard mappings and infrastructure risk assessments.

To successfully manage climate change impacts and support sustainable development in the Arctic, it is critical to (i) produce high-resolution geospatial datasets of ground conditions (e.g., content of organic material and ground ice), (ii) develop further high-resolution permafrost modelling, (iii) comprehensively map permafrost degradation-related hazards, and (iv) quantify the amount and economic value of infrastructure and natural resources at risk across the circumpolar permafrost area.
Inventory and Assessment of Geosites for Geotourism Development in the southeastern Lake Tana region, northwest Ethiopia
Authors: Tessema Getaneh Addis , van der Borg Jan , Sewnet Amare , van Rompaey Anton , Adgo Enyew , Nyssen Jan , Asrese Kerebih , Van Passel Steven , Poesen Jean
Published: March 2020

Abstract

Geotourism is a niche type of sustainable tourism which focuses on geological and geomorphological features of an area, and associated culture and biodiversity. Geosites are important resources for geotourism development. The southeastern Lake Tana region in Ethiopia possesses several geosites that are of interest to both the scientific community and tourists having a broad interest. The area is also part of an important economic corridor and tourist route in the country. Currently, only the Blue Nile Falls, Lake Tana and its island monasteries are being visited. The objective of this study is, therefore, to inventory geosites in the southeastern Lake Tana region and to assess their potential for geotourism development. To this end, a geosite inventory and assessment methodology was developed. The criteria, indicators and sub-indicators used for assessment were prepared based on a review of publications. The indicators used for assessing the potential of geosites are scientific, educational, scenic, recreational, protection, functional and ecological values. A first list of 114 potential geosites have been inventoried based on stakeholder interviews and a review of relevant documents in the study area. Further screening and clustering resulted in a final list of 61 geosites. Among the major newly proposed geosites are viewpoints; waterfalls; hot springs; a large flood plain; caves and cave churches; rock-hewn churches;  a shield volcano; lava tubes; and volcanic plugs, cones and columns. Quantitative assessment of the potential of these geosites revealed that clustered  geosites received relatively higher scientific, scenic and recreational value scores. For sustainable development of geotourism in the Lake Tana area, it is important to improve access to geosites, and establish visitor centers and accommodation facilities at selected sites.

Keywords Geoheritage . Sustainable development . Volcanic features . Lake . Waterfalls . Flood plain . Geotouristic valorization.
Danish earthquake recorded by distributed acoustic sensing (DAS)
Authors: Rasmussen Camilla , Voss Peter H. , Dahl-Jensen Trine
Published: March 2020

On September 16th 2018 a Danish earthquake of local magnitude 3.7 was recorded by distributed acoustic sensing (DAS) in a ~23 km long fibre-optic cable. The data are used to study how well DAS can be used as a supplement to conventional seismological data in earthquake localisation. One of the goals in this study is extracting a small subset of traces with clear P and S phases to use in an earthquake localisation, from the 11144 traces the DAS system provide. The timing in the DAS data might not be reliable, and therefore differences in arrival times of S and P are used instead of the exact arrival times.
The DAS data set is generally noisy and with a low signal-to-noise ratio (SNR). It is examined whether stacking can be used to improve SNR. The SNR varies a lot along the fibre-optic cable, and at some distances, it is so small that the traces are useless. Stacking methods for improving SNR are presented.

A field test at two location sites of the fibre-optic cable was conducted with the purpose of comparing DAS data with seismometer data. At the field sites, hammer shots were recorded by a small array of three STS-2 sensors located in a line parallel to the fibre-optic cable. The recordings generally show good consistency between the two data sets. 
In addition, the field tests are used to get a better understanding of the noise sources in the DAS recording of the earthquake. There are many sources of noise in the data set. The most prominent are a line of windmills that cross the fibre-optic cable and people walking in the building where the detector is located. Also, the coupling between the fibre-optic cable and the ground varies along the cable length due to varying soil type and wrapping around the fibre-optic cable, which is also evident in field test data. Furthermore, the data from the field tests are used to calibrate the location of the fibre-optic cable, which is necessary for using the DAS data in an earthquake localisation.
Data processing is done in Matlab and SEISAN.
Using wehrlites to monitor the passage of CO2-bearing melts in the shallow lithosphere
Authors: Aulbach Sonja , Lin A-Bing , Weiss Yaakov , Yaxley Gregory
Published: March 2020

Continental rifting has been linked to the thinning and destruction of cratonic lithospheres and to the release of enough CO2 to impact the global climate [1]. This fundamental plate tectonic process facilitates the infiltration and/or mobilisation of small-volume carbonated melts, which interact with mantle peridotite to form wehrlite through the reaction: enstatite + CO32- (melt) = forsterite + diopside + CO2 (vapour) [2]. An analysis of the literature reveals that wehrlites are common in shallow mantle lithosphere in disrupted craton settings affected by either extension or subduction, and they have been linked to agents ranging from carbonatites to basanites [e.g. 3,4]. Conversely, the low abundance of wehrlitic diamond and garnet in cratonic mantle xenoliths (as opposed to lherzolitic or harzburgitic) indicate that wehrlitisation is not an important process at depths >~120 km. This may be due to the presence of a dominantly reducing lithosphere, which favours diamond precipitation or dissolution during reaction with carbonated silicate melts, depending on carbon saturation. Based on the relationship between wehrlite and small-volume carbonated melts, we suggest that wehrlite-bearing xenoliths can be used to monitor CO2 mobility through the shallow continental lithosphere. Assuming a depleted protolith, typically harzburgite at shallow lithospheric depth, the amount of newly-added cpx can be estimated and related to CO2 in the melt volume based on the above reaction. Considering the proportion of wehrlite in the xenolith population, an estimate of the total CO2 transported out of the shallow lithosphere can be made. For example, peridotite xenoliths from Liaoyuan in the reactivated northeastern North China craton sample the mantle beneath the mid-Cretaceous Tan Lu Fault Belt (TLFB), which is even vaster in size (5000 x 800-1000 km) than the EAR, the latter linked to degassing of 28 to 34 Mt C/yr over 40 Ma [1]. If wehrlitisation affected only a 10 km depth interval over a similar time, 23 Mt C/yr has passed through the TLFB, possibly contributing to the mid-Cretaceous greenhouse climate. Thus, wehrlites reveal the hidden carbon cycle in lithospheric provinces where CO2-rich melts are not necessarily observed at the surface.

 

[1] Foley and Fischer 2017 Nature Geosci 10; [2] Yaxley et al. 1998 J Petrol 39; [3] Aulbach et al. J Petrol 2017 58; [4] Lin et al. subm. J Geophys Res
Error estimation for soil moisture measurements with cosmic-ray neutron sensing and implications for rover surveys
Authors: Jakobi Jannis , Huisman Johan Alexander , Schrön Martin , Fiedler Justus , Brogi Cosimo , Vereecken Harry , Bogena Heye
Published: March 2020

The cosmic ray neutron (CRN) probe is a non-invasive device to measure soil moisture at the field scale. This instrument relies on the inverse correlation between aboveground epithermal neutron intensity (1eV – 100 keV) and environmental water content. The measurement uncertainty of the neutron detector follows Poisson statistics and thus decreases with decreasing neutron intensity, which corresponds to increasing soil moisture. In order to reduce measurement uncertainty (e.g. < 0.03 m3/m3), the neutron count rate is often aggregated over large time windows (e.g. 12h or 24h). To enable shorter aggregation intervals, the measurement uncertainty can be reduced either by using more efficient detectors or by using arrays of detectors, as in the case of CRN rover applications. Depending on soil moisture and driving speed, aggregation of neutron counts may also be necessary to obtain sufficiently accurate soil moisture estimates in rover applications. To date, signal aggregation has not been investigated sufficiently with respect to the optimisation of temporal (stationary probes) and spatial (roving applications) resolution. In this work, we present an easy-to-use method for uncertainty quantification of soil moisture observations from CRN sensors based on Gaussian error propagation theory. We have estimated the uncertainty using a third order Taylor expansion and compared the result with a more computationally intensive Monte Carlo approach and found excellent agreement. Furthermore, we used our method to quantify the dependence of soil moisture uncertainty on CRN rover survey design and on selected aggregation time. We anticipate that the new approach helps to quantify cosmic ray neutron measurement uncertainty. In particular, it is anticipated that the strategic planning and evaluation of CRN rover surveys based on uncertainty requirements can be improved considerably.
From Large Scale Hazard Mapping to Risk Assessment
Authors: Ortner Gregor , Bruendl Michael , Bresch David N. , Bühler Yves
Published: March 2020

Various studies show that changes in the climate system, such as temperature rise and extreme precipitation events strongly influence gravity driven hazards. In 2018, the research programme “Climate Change Impacts on Alpine Mass Movements” began at the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. Within this programme, we develop a framework to model risk caused by climate and socio-economic change. In a first approach, we model avalanche risk in central Switzerland. The changing hazard disposition is modelled with the RAMMS::LSHM Large Scale Hazard Mapping method and risks are assessed with the probabilistic, Python-based risk assessment platform CLIMADA developed at ETH Zurich. We use several hazard scenarios considering different 3-day increases in snow height, an algorithm for determining potential avalanche release areas, a high-resolution terrain model and a forest layer to model the spatial distribution of avalanche hazard for each of the chosen scenarios. The so-derived hazard indication maps are taken as input into CLIMADA to estimate the risk to buildings and infrastructure applying various functions to quantify the avalanche impact.
The result are risk maps which depict spatial and temporal changes of avalanche risk based on various hazard scenarios. The combination with exposure and damageability information, leading to spatio-temporally explicit risk maps provides a comprehensive basis and allows for the appraisal of appropriate risk management options. A risk based approach for lifelines and residential areas will contribute to decision support and highlight adaptations needed for climate change.
Latest Pliensbachian–Toarcian eustatic calibration using shallow-marine sedimentological record coupled with basinal geochemical analyzes
Authors: Krencker François-Nicolas , Fantasia Alicia , El Ouali Mohamed , Kabiri Lahcen , Bodin Stéphane
Published: March 2020

Sea-level fluctuation is an important parameter controlling the sedimentation in deep-marine environments and influenced also the expansion of oxygen-depleted conditions in neritic settings during oceanic anoxic events (OAEs). Despite this fundamental role, sea-level fluctuation remains on a short timescale (<1 Myr) one of the least constrained parameters for numerous OAEs. Here we refine the sequence stratigraphic framework for the uppermost Pliensbachian–Toarcian with a special focus on the Toarcian OAE interval. This study is based on sedimentological and total organic carbon isotope data used to correlate 16 sections located in the central High Atlas (Morocco). Palinspastically, those sections formed a 50-kilometer proximal–distal transect along the northern Gondwana continental shelf, which allow reconstructing the shoreline migration through time and space. Our sequence stratigraphic interpretation is then compared to the geochemical signals (e.g. detrital index, chemical index of alteration) measured on samples collected in deep-environment settings from numerous basins distributed worldwide. Our study shows that the relative sea-level changes recorded in Morocco can be correlated over large distances across those basins, indicating that the relative sea-level changes were driven by eustatic fluctuations. This study gives insights into the relationship between relative sea-level fluctuations and the geochemical record.
Relations and trends of Fire Weather Severity and MODIS Burned Area in Croatia
Authors: Marjanovic Hrvoje , Kern Anikó , Ostrogovic Sever Masa Zorana , Vucetic Visnja , Anic Mislav
Published: March 2020

Wildfires can inflict serious damage to forest ecosystems, agricultural areas and often endanger human settlements and lives. Rising global temperatures and changes in precipitation pattern increase the risk of severe fires. In Croatia, the areas currently most affected with high risk of forest fires are located in the Mediterranean region. Due to climate change the risk will likely increase and further strain the available fire-fighting resources. The situation could be even more alarming in Continental parts of the country where forest fires were not common in the past, but may become increasingly likely in the near future. Therefore, accurately assessing the wildfire risk is increasingly important in implementing fire-avoidance activities and optimizing the management of country’s fire-fighting resources.

The aim of our study is to assess the change in the spatio-temporal distribution of the fire Daily Severity Rating (DSR) and the Seasonal Severity Rating (SSR) in the last two decades, with respect to the reference period 1961–1990. We present a spatial analysis of SSR for the period 1989–2018 in Croatia based on the Croatian Meteorological and Hydrological Service (DHMZ) data and compare it with the one of European Forest Fire Information System (EFFIS). The relation between the SSR and the burned area, estimated from MODIS MCD64A1 Version 6 Burned Area data product, during 2001–2018 is investigated with the aim to facilitate locally optimized model for the assessment of the expected burned area associated with a given SSR. The results should contribute to improved understanding of the near-future risk of severe fires in Croatia related to possible future climate scenarios.
Identifying icequakes at ice-covered volcanoes in Southern Chile
Authors: Lamb Oliver , Lees Jonathan , Franco Marin Luis , Lazo Jonathan , Rivera Andres , Shore Michael , Lee Stephen
Published: March 2020

Volcanoes and glaciers are both productive sources of seismic activity which may be easily confused for each other, leading to potential missed warnings or false alarms. This presents a challenge for organizations monitoring active volcanoes with glaciers on or near the edifice. Cryogenic earthquakes (i.e. icequakes) have been studied at only a few volcanoes around the world and there is a ready need to develop robust methods for efficiently differentiating them from volcanic events. Here we present results from an ongoing study of icequakes at active ice-covered volcanoes in the Southern Chilean Volcanic Zone. The primary focus of the project so far has been on seismo-acoustic data collected at Llaima volcano, one of the largest and most active volcanoes in the region. The data, recorded in 2015 and 2019, was analysed using a combination of automatic multi-station event detection and waveform cross-correlation to find candidate repeating icequakes. We identified 11 persistent families of repeating events in 2015, and over 50 families in 2019; the largest family containing over 1000 events from January to April 2019. The persistent, repetitive nature of these events combined with their waveform characteristics and source locations suggest they originated from multiple sub-glacial sources on the upper flanks of the volcano. Low levels of volcanic activity at Llaima volcano since 2009 have allowed this clear discrimination of icequake events. We are also targeting Villarrica volcano in early 2020 with a network of seismo-acoustic sensors and to record icequake activity in concurrence with the ongoing eruptive activity at the summit. Altogether, the results from this project so far suggest icequakes may be more common than previously thought and has strong implications for how seismic data at ice-covered volcanoes may be interpreted.
PALM-4U – A building-resolving microscale model to support future adaptation of cities in a changing urban climate
Authors: Hettrich Sebastian , Maronga Björn , Raasch Siegfried
Published: March 2020

In a world with increasing extreme weather events, such as dry or extreme rain periods, due to climate change and an ever growing population specifically in urban areas, a forsighted planning and adaption of cities and their urban surroundings is becoming more and more important. Here, particularly health and comfort of the urban population, such as thermal comfort, air quality, ventilation or UV exposure, but also other aspects like safety and environmental sustainability play an important role. In order to create the cities of tomorrow that meet the real requirements to host healthy and firendly living conditions, city planners are relying on scientific models where they can simulate how changes in the urban environment can effect its climate. The PALM-4U (Parallelised Large-Eddy Simulation Model for Urban Applications) model was specifically developed to be able to simulate a large variety of parameters on short timescales and at the high resolution that is required to resolve single buildings or obstacles like trees within the city.

In September 2019, the second phase of the German research project MOSAIK (model-based city planning and application in climate change), a module within the large over-arching project [UC]² (Urban Climate Under Change) that focusses on the further development of the model, has started.

In this overview, we will present the PALM-4U‘s current capabilities and outline the planned future development in the coming years like windbreak modelling, coupling with traffic flow models, including biogenic volatile organic compounds in urban air quality modelling. Furthermore, our PALM-4U community model strategy will be explained.
Extreme TGF Imaging by ASIM
Authors: Reglero Víctor , Connell Paul , Navarro Javier , Eyles Christopher , Ostgaard Nikolai , Neubert Torsten , Fabro Ferran , Montanya Joan , Mezentsev Andrey , Chanrion Olivier , Christiansen Freddy , Kochkin Pavlo , Marisaldi Martino
Published: March 2020

One year after the starting of ASIM operational phase, we have succeeded to perform accurate Imaging of 54 TGF.  Among them, some have been analysed at extreme imaging conditions in terms of TGF position at the MXGS partially coded field of view.  20 TGF events have angular distances larger than 40º respect to the MXGS FOV centre. Extreme cases at angular distances larger than 50º are presented. Validation of TGF position by WLN data is included in the discussion.

The canonical value of 32 LED cnts as the minimum fluency for TGF imaging defined during MXGS development was checked using low luminosity TGF.  At the present, we have succeeded to obtain imaging solution for 7 TGF with less than 20 cnts. A sample is presented with indication of position accuracy and S/N ratios.  

Last part of the presentation is the discussion of a TGF with a very large and asymmetric probability distribution at the MXGS FOV that suggest the TGF as an extended source. Imaging data projected to the Earth surface is compared with GOES data, showing that the TGF is at the edge of a large convective cell, close to the TGF imaging data map.  Therefore, we can conclude that for some bright TGF it is possible to estimate the TGF fireball dimensions generated by the iteration of TGF photons with local atmospheric asymmetric matter distributions. The presence of a large CZT tail is coherent with the size of the convective cell.
Petrology of the Yubileynaya kimberlite pipe: application to the variation of kimberlites composition with the depth
Authors: Spetsius Zdislav , Ivanov Alexander
Published: March 2020

In this paper are summarized investigation results on the chemistry, petrography and mineralogy of kimberlitic rocks of the upper and deep levels of the Yubileynaya pipe. There are given original data on mineral phases contents in kimberlite ground mass,distribution of indicator minerals and olivine and its pseudomorphoses as well as autoliths (pyroclasts) in kimberlite drill cores of different levels (-)280 – (-)680m.

Petrologic evidence suggest that for the kimberlites of the Yubileynaya pipe is characteristic the prevalence garnet association of indicator minerals with the relatively low their whole content, predominance oflherzolitic pyropes, low content of titanium garnets, two types of ilmenites and chromespinelides.The particularity of this pipe is the presence, both eclogite and garnet websterite xenoliths as well as their diamondiferous varieties. This evidence is confirmed also by the composition of the paragenic associations of indicator minerals that is indicative of essential difference of lithospheric mantle under this given pipe in contrast with nearby kimberlitic pipes. It is possible to speculate that these peculiarities are specific for the kimberlite pipes of the middle diamond productivity.

Results of the garnets chemistry and the data of the distribution of eclogitic and ultramafic garnets in kimberlite concentrate of this pipe with the taking in account quantity of garnet variety potentially associated with diamonds suggest anincreased prevalence of eclogitic garnets among indicator minerals. This allowed making a statement about essential input of eclogitic paragenesis diamonds in the whole diamond production of this pipe. In our opinion these peculiarities also determine the increased content of large diamond crystals in kimberlites of the Yubileynaya pipe.    
CDOs for CMIP6 and Climate Extremes Indices
Authors: Wachsmann Fabian
Published: March 2020

The Climate Data Operators [1] tool kit (CDO) is a worldwide popular infrastructure software developed and maintained at the Max Planck Institute for Meteorology (MPI-M). It comprises a large number of command line operators for gridded data, including statistics, interpolation, or arithmetics. Users benefit from the extensive support facilities provided by the MPI-M and the DKRZ.

As a part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6), the German Federal Ministry of Education and Research (BMBF) is funding activities promoting the use of the CDOs for CMIP6 data preparation and analysis.  

The operator ‘cmor’ has been developed to enable users to prepare their data according to the CMIP6 data standard. It is part of the web-based CMIP6 post-processing infrastructure [2] which is developed at DKRZ and used by different Earth System Models. The CDO metadata and its data model have been expanded to include the CMIP6 data standard so that users can use the tool for project data evaluation.

As a second activity, operators for 27 climate extremes indices, which were defined by the Expert Team on Climate Change Detection and Indices (ETCCDI), have been integrated into the tool. As with CMIP5, the ETCCDI climate extremes indices will be part of CMIP6 model analyses due to their robustness and straightforward interpretation.

This contribution provides an insight into advanced CDO application and offers ideas for post-processing optimization. 

[1] Schulzweida, U. (2019): CDO user guide. code.mpimet.mpg.de/projects/cdo , last access: 01.13.2020.

[2] Schupfner, M. (2020):  The CMIP6 Data Request WebGUI. c6dreq.dkrz.de , last access: 01.13.2020.
Modeling of HDO in the Martian atmosphere
Authors: Rossi Loïc , Montmessin Franck , Forget François , Millour Ehouarn , Olsen Kevin , Vals Margaux , Fedorova Anna , Trokhimovskiy Alexander , Korablev Oleg
Published: March 2020

Mars is known to have had a significant liquid water reservoir on the surface and the D/H ratio is an important tool to estimate the abundance of the early water reservoir on Mars and its evolution with time. The D/H ratio is a measure of the ratio of the current exchangeable water reservoir to the initial exchangeable water reservoir. Many observations from the ground have shown that the current ratio is five times that of the reference in Earth's oceans (Encrenaz et al. 2018, Krasnopolsky et al. 2015, Villanueva et al. 2015).

H and D atoms in the upper atmosphere are coming from H2O and HDO, their sole precursor in the lower atmosphere. The lower mass of H over D atoms and the fact that H2O is preferentially photolysed over HDO (Cheng et al. 1999) explain the differential escape of these two elements. Finally, due to differences in vapor pressure for HDO and H2O, the solid phase of water is enriched in deuterium compared to the vapor phase. This effect is known as the Vapor Pressure Isotope Effect (VPIE) and can reduce the D/H ratio above the condensation level to values as low as 10% of the D/H ratio near the surface (Bertaux et al. 2001, Fouchet et al. 2000).

These fractionation processes can affect the amount of HDO with latitude, longitude, altitude and with the season. In particular, previous models (Montmessin et al. 2005) have shown that an isotopic gradient should appear between the cold regions where condensation occurs and the warmer regions. This leads to a latitudinal gradient of D/H (with variations greater than a factor of 5) between the warm and moist summer hemisphere and the cold and dry winter hemisphere. Yet some observations (Villanueva et al. 2015, Khayat et al. 2019) also show longitudinal variations of H/D ratios which are not explained so far.

Previous work has been done on modeling HDO using 3D GCMs, in particular around the IPSL Mars GCM (Montmessin et al. 2005). Since the GCM has considerably evolved since this first HDO introduction in the modeled water cycle, a reappraisal of HDO predictions is needed to account for the detailed microphysics that control cloud formation and thus HDO fractionation. 

The Trace Gas Orbiter, part of the ExoMars mission, is currently in orbit around Mars. Onboard is the Atmospheric Chemistry Suite, a set of spectrometers designed to study the atmosphere of Mars with a specific focus on trace gases such as methane. With TGO now in its mission phase, very strong and precise constraints will be soon available to evaluate the GCM prediction capability.

We will describe here our work on the update of the HDO model in the IPSL Mars GCM and will attempt first comparison with the early TGO/ACS observations, in particular in the context of the global dust storm of 2018.