bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying Convective Aggregation using the Moist Tropical Margin’s Length
Authors: Windmiller Julia , Leutwyler David , Beucler Tom
Published: March 2020

A peculiar feature of the tropical atmosphere is its tendency to be either rather moist or very dry. It has

been shown that the two states are separated by a sharp margin, well identified by the anti-mode of

the bimodal tropical column water vapor distribution (CWV). Despite recent progress in understanding

physical processes governing the spatio-temporal variability of CWV near the Equator, the behavior of

this meander remains elusive, and we lack a simple framework to understand the bimodality of tropical

CWV in observations. A tendency of the atmosphere to be either moist or dry can also be found in

idealized simulations of radiative-convective equilibrium (RCE). A number of studies assessing self-

aggregation of convection in RCE simulations have indicated that positive feedbacks between

radiation and moisture lead to spatially concentrated moisture in a small area of the computational

domain. As a result, RCE simulations also exhibit a bimodal distribution of CVW and a distinct moist

margin.

Motivated by theory originating from statistical physics, we argue that, in steady-state RCE, the length

of the margin separating moist and dry regions should minimize. Based on these ideas, we design a

diagnostic relating the moist margin length to the circumference of a defined equilibrium shape. Using

that Moist Margin Length Index (MMLi), we assess the evolution of self-aggregation in idealized

convection-resolving RCE simulations and contrast it to the oscillations of the Atlantic Inter-Tropical

Convergence Zone in the ERA5 reanalysis product.

We find that MMLi successfully describes aspects of convective organization not captured by more

traditional metrics of convective organization (e.g., the CVW's interquartile range) while offering a new

way to characterize the seasonal cycle of convective organization in the Atlantic ITCZ. Overall, our

new framework uses the moist meander margin to connect the observationally-motivated, object-

oriented view of convective organization with the processes driving the spatio-temporal evolution of

the CWV field. It can be broadly deployed across models and observations to lead further insight into

the bimodal nature of CWV while offering an efficient and visual way to quantify convective

organization.
Thermal anomalies in Late Mesozoic to Cenozoic basin deposits: What can they tell us about the separation of Greenland from Svalbard?
Authors: Meier Katrin , Jochmann Malte , Blumenberg Martin , Kus Jolanta , Piepjohn Karsten , O'Sullivan Paul , Monien Patrick , Kolb Vera , Lisker Frank , Spiegel Cornelia
Published: March 2020

Paleogene rocks from Svalbard yield exceptionally high vitrinite reflectance values up to 4%. Even higher vitrinite reflectance data, along with high bitumen reflectance values, are found from Cretaceous to Paleogene rocks of the conjugated northeast Greenland margin. These rocks also contain coke. Since the distinct pattern of high thermal maturity affects both sides of the Fram Strait, it is interpreted to be caused by a heating event during a time when Greenland and Svalbard / Eurasia were still contiguous or close together. As heating overprints Paleogene sediments, we further assume that it postdates the Eocene Eurekan deformation and is related to subsequent (trans-)tensional movement leading to continental separation and eventually to the opening of the Fram Strait. The Fram Strait is the only deepwater connection of the Arctic Ocean with other oceans and is key for understanding the climatic, tectonic and paleo-oceanographic evolution of the Arctic realm. Timing and trigger mechanisms for mid- to late Miocene tectonic activity around the Fram Strait are still poorly constrained. For this study, we will test the following hypotheses using apatite fission track and apatite (U-Th-Sm)/He thermochronology: (i) Heating of the west and east side of the Fram Strait occurred simultaneously and was caused by incipient sea floor spreading in the Fram Strait; (ii) heating occurred during mid- to late Miocene in relation to uplift/exhumation and enhanced magmatic activity. Vitrinite reflectance data indicate temperatures high enough to reset low-temperature thermochronometers, thus our results will allow to date the thermal event and to investigate how it was temporarily and spatially connected to the separation of Greenland from Svalbard and thus to the opening of the northern North Atlantic Ocean and the Fram Strait. First Data will be presented.
Heat ascribed mortality in southeast England
Authors: Sahani Jeetendra , Debele Sisay , Di Sabatino Silvana , Kumar Prashant
Published: March 2020

Global warming induced climate change is bringing periods of extremely hot summer days called heatwaves across the world. Its frequency, intensity and magnitude have escalated multifold in recent decades and have been predicted to keep intensifying. Many past studies have only focused on cities for heatwave risk assessment overlooking the risks in suburban and rural areas. The aim of this work is to form a scientific framework for preparing and managing the human-health impacts of heatwaves in more pastoral regions. We associated  the extreme temperature with mortality to evaluate its risk using recent data on daily-deaths and maximum temperature from nine counties of southeast England for the period of 1981-2014. The reproduced methodology will also be applied to OPERANDUM project’s test regions called open-air laboratories across Europe. The relationship between temperature and daily-deaths has been examined using  a poisson regression model combined with a distributed-lag nonlinear model (DLNM). We computed the absolute excess (numbers) and relative excess (fraction) deaths owed to temperature or relative risk (RR) of mortality by comparing the extremely hot temperature (99th percentile) with the minimum mortality temperature (MMT). Total heat ascribed mortality is given by the sum of the contributions from all the days of the time-series, and its ratio with the total number of deaths. Significant and non-linear associations between temperature and daily-deaths were noticed. The overall cumulative RR at the extremely hot vs. MMT was 1.292 (95% CI: 1.251–1.333). The results of this study can help in location-centric heat management action plans to certain areas at most risk.

Acknowledgements: This work is supported by the European Union's Horizon 2020 research and innovation programme; funded by and carried out within the framework of OPERANDUM project (Grant no. 776848).

Key words: Heatwaves, climate change, mortality, DLNM, risk.
EPOS ICS Data Portal
Authors: Freda Carmela , Paciello Rossana , Michalek Jan , Atakan Kuvvet , Bailo Daniele , Jeffery Keith , Harrison Matt , Cocco Massimo , Team Epos
Published: March 2020

The European Plate Observing System (EPOS) addresses the problem of homogeneous access to heterogeneous digital assets in geoscience of the European tectonic plate. Such access opens new research opportunities. Previous attempts have been limited in scope and required much human intervention. EPOS adopts an advanced Information and Communication Technologies (ICT) architecture driven by a catalog of rich metadata. The architecture together with challenges and solutions adopted are presented. The EPOS ICS Data Portal is introducing a new way for cross-disciplinary research. The multidisciplinary research is raising new possibilities for both students and teachers. The EPOS portal can be used either to explore the available datasets or to facilitate the research itself. It can be very instructive in teaching as well, for example by demonstrating scientific use cases. 

EPOS is a European project about building a pan-European infrastructure for accessing solid Earth science data. The finished EPOS-IP project includes 47 partners plus 6 associate partners from 25 countries from all over Europe and several international organizations. However, the community contributing to the EPOS integration plan is larger than the official partnership of EPOS-IP project, because more countries are represented by the international organizations and because there are several research institutions involved within each country.

The recently developed EPOS ICS Data Portal provides access to data and data products from ten different geoscientific areas: Seismology, Near Fault Observatories, GNSS Data and Products, Volcano Observations, Satellite Data, Geomagnetic Observations, Anthropogenic Hazards, Geological Information and Modelling, Multi-scale laboratories and Geo-Energy Test Beds for Low Carbon Energy.

The presentation focusses on the EPOS ICS Data Portal, which is providing information about available datasets from TCS and access to them. We are demonstrating not only features of the graphical user interface but also the underlying architecture of the whole system.
Modelling Tropical Precipitation in the mid-Pliocene Warm Period
Authors: Tindall Julia , Haywood Alan
Published: March 2020

Models from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) show that the mid-Pliocene Warm Period (mPWP) was a warmer and wetter world than today. However, there is not strong model agreement as to how tropical precipitation was different in the mPWP. Although PlioMIP2 models agree that there was more precipitation associated with the African Monsoon and the Asian Monsoon, away from these regions models do not show a consistent and robust change in precipitation between the mPWP and the preindustrial.

Here we use the HadGEM2 model to explore changes in tropical precipitation between the mPWP and the preindustrial, particularly those associated with the position and strength of the Intertropical Convergence Zone (ITCZ). Reasons for these changes within HadGEM2 will be discussed. We will also expand our discussion of the ITCZ to the PlioMIP2 ensemble in order to show the differing factors that could influence ITCZ characteristics in a warmer world.
Efficient modelling of water temperature patterns in river systems – benchmarking a set of machine learning approaches
Authors: Herrnegger Mathew , Feigl Moritz , Lebiedzinski Katharina , Schulz Karsten
Published: March 2020

Many approaches for modelling river water temperature are available, but not one exist that can be applied without restrictions. The applied method depends on data availability, dominant processes, scales and transferability. Process-based models are currently the best way to evaluate detailed management scenarios on reach scale and to understand underlying processes.  Due to limitations of data availability, however, more simplified approaches are frequently applied, where different meteorological or hydrological time series are statistically related to water temperature (or in the simplest case only using air temperature). Here, machine learning methods could help bridging a gap by allowing for more complex relationships without setting prior assumptions. They are thus integrating reasonable processes and dynamics within the catchment by learning from given data. However, up-to-date machine learning approaches have rarely been used in this field until now.

This contribution analyses a set of machine learning approaches for large-scale river temperature modelling. Deep learning methods, random forests and boosting methods are compared with the performance of commonly used simple and multiple regression models. These approaches are tested on 10 catchments with different characteristics, human impacts (e.g. hydropower, river regulation) and time series lengths (10 to 39 years). They are situated in the Austrian Alps or flatlands with areas ranging from 200 to 96.000 km². Observed data including daily means of river water temperature, air temperature, discharge, precipitation and global radiation are grouped to simple and advanced sets of input variables to analyse possible data dependencies. 

In summary, we compare up-to-date machine learning approaches for their applicability in river water temperature prediction. By implementing necessary data preprocessing steps and machine learning routines in a R package, we aim to make these findings easily accessible and reproducible for the community. This tool provides an attractive approach for large-scale river temperature modelling, where the requirements for using process-based models are not able to be met. Future applications can include e.g. short and long term forecasting of river water temperature to find management options for balancing environmental requirements. 
Retrieval of basic soil physical properties by assimilating radiometry observations in the community land surface model
Authors: Zhao Hong , Zeng Yijian , Su Bob , Han Xujun
Published: March 2020

Accurate basic soil properties information is fundamental for obtaining reliable soil moisture using land surface models. In view of the passive microwave remote sensing, basic soil properties have an impact on soil dielectric constant, together with soil moisture and temperature. The common link enables to use coupled land surface model with microwave emission model for retrieving basic soil properties in space, especially in remote areas such as the third pole region. The Maqu site in the eastern Tibetan Plateau, including ELBARA-III radiometry observations, was taken as the case. This paper employed an improved observation operator— a discrete scattering-emission model of L-band radiometry with an air-to-soil transition model embedded in, which considers both geometric and dielectric roughness impacts from heterogeneous topsoil structure on surface emission. Community Land Model 4.5 together with Local Ensemble Transform Kalman Filter algorithm were used by mean of the Open Source Multivariate Land Data Assimilation Framework. The retrieved basic soil properties were compared to in situ measurements, as well as the update soil moisture and temperature and energy fluxes. The impacts from surface roughness consideration and polarization configuration on parameter retrieval were also evaluated. To gain an insight on the impact from time interval of observations on parameter retrieval, results using observations at SMAP descending and ascending time were discussed.
Emissions of CH4, CO2, C2H6, CO and isotopic signatures in the Upper Silesian Coal Basin, Poland
Authors: Fiehn Alina , Kostinek Julian , Eckl Maximilian , Galkowski Michal , Chen Jinxuan , Gerbig Christoph , Röckmann Thomas , Maazallahi Hossein , Schmidt Martina , Korben Piotr , Necki Jarek , Wildmann Norman , Mallaun Christian , Klausner Theresa , Bun Rostyslav , Fix Andreas , Roiger Anke
Published: March 2020

The Upper Silesian Coal Basin (USCB) represents one of the largest European CH4 emission source regions, with a total sum of 500 Gg CH4/a released by individual coal mine ventilation shafts. During the CoMet (Carbon Dioxide and Methane Mission) campaign in late spring 2018, airborne in-situ measurements were carried out aboard the DLR research aircraft Cessna Caravan. The Cessna was equipped with a cavity ring-down and a quantum cascade laser system to measure CH4 and CO2, as well as related tracers such as CO and C2H6. Additionally, air samples were collected and analyzed for greenhouse and trace gases, including isotopic ratios of CH4 and CO2. Meteorological parameters were measured with a boom mounted sensor package.

During nine research flights, CH4 emissions were studied by using an airborne Mass Balance Approach. Depending on the wind situation, different areas of the USCB region were targeted. To account for the lower part of the plume not accessible by the aircraft, a number of vans with mobile in-situ measurement systems conducted ground-based measurements in a coordinated manner. The derived methane emission estimate agrees well with bottom-up inventories like the Emission Database for Global Atmospheric Research (EDGAR) and the European Pollutant Release and Transfer Register (E‑PRTR). The CO2 emission estimate is at the lower end of the inventories. The CO emission estimate is higher than inventory values.

From simultaneous methane and ethane measurement the emission ratios of different subregions of the USCB could be determined. The emission ratios range from 19 to 290 CH4/C2H6 and are, thus, quite variable within this coal basin. From the analysis of collected flask air samples the isotopic composition of CH4 emissions was determined. Isotopic signatures of Polish USCB CH4 emissions are between -52.7‰ and -49.4‰ for δ13C and between -241‰ and -178‰ for δD. Samples taken in the Czech part of the USCB had a δD isotopic ratio of around -309‰, hinting at a larger influence of biogenic sources in this region.
Disastrous landslides under changing forcing factors triggered end 2019 in West Kenya
Authors: Schlögel Romy , Belabbes Samir , Dell Oro Luca , Déprez Aline , Malet Jean-Philippe
Published: March 2020

End of 2019 was particularly damaging in some Central and Eastern African countries due to the heavy rain which triggered numerous mass movements. Extremely heavy rainfall were recorded in Pokot South and Sigor Sub counties located in West Pokot County (Kenya) on 23 and 24 November 2019. An official from the West Pokot county government said 53 people died after devastating rains caused huge landslides in this County while several roads in the valley have been affected and at least 5 bridges were reported as destroyed. Indeed Kenya has seen several villages heavily affected by landslides after floods and torrential rain. These movements were detected from a combination of high-resolution Sentinel 2 images and very high-resolution Pléiades-1 images acquired before and after the landslide catastrophe with the engagement of the UNOSAT’s rapid mapping service which activated the International space charter mechanism. In the following days, a series of analysis of the affected zones from very high-resolution optical data were delivered in the following days to UNOSAT and the emergency response authorities in Kenya. This study explains the mechanism of the rapid mapping activation and the use of the Disaster Charter mechanism to help to detect the extent of the phenomena and impacted infrastructure by providing a rapid mapping related analysis, conducted at UNOSAT with satellite data provided by space agencies involved in the International Space Charter. Science-driven landslide inventories were created with the ALADIM change detection algorithm integrated on the ESA GeoHazards Exploitaton Platform. Over the studied region of 400 km2, nearly 6000 landslides were detected, corresponding to an affected area of ca. 18 km2. Then, the triggering factors of this disaster were analysed understanding how changing raining conditions is affecting the area while it was not considered as landslides-prone. This research aims to state if this particular event is considered as abnormal according to rainfall trends and landslide occurrence looking at long time series and/or human practices play a major role in triggering this type of catastrophe.
Seasonal fluctuations in the secondary microseism wavefield recorded offshore Ireland
Authors: Le Pape Florian , Bean Christopher J.
Published: March 2020

Generated in the ocean, secondary microseisms result from the interaction of opposing ocean wave fronts and represent the strongest ambient seismic noise level measured on land. The recorded noise energy will vary with seasons due to changes in storm activity and associated secondary microseism source locations. Here, ocean bottom seismometer (OBS) data collected offshore Ireland in 2016 have been processed to look into the seasonal variations of the ambient noise wavefield recorded at the seafloor. Daily cross-correlations of OBS pairs located on top of thick sediments in deep water highlight seasonal changes between Rayleigh waves fundamental mode and first overtone for winter and summer months. Comparisons with ocean wave directional spectrum data derived from ocean wave model hindcasts suggest those variations are correlated with changing patterns in ocean waves interactions and therefore microseism source locations. In order to understand those observations in detail, we use 3D numerical simulations to show how the water column but also the subsurface structure below the sea bottom will affect the recorded wavefield at the seafloor for different stations and sources locations. Compared to land stations, the secondary microseism wavefield observed in the ocean and in particular changes in the excitation of Rayleigh modes due to site effects can help characterize the microseism source locations that fluctuate through the seasons.
Influence of organic and biogenic substances on the ice nucleation properties of mineral dust particles
Authors: Klumpp Kristian , Marcolli Claudia , Peter Thomas
Published: March 2020

The formation of ice in mixed phase clouds occurs in the presence of aerosol particles with the ability to nucleate ice on their surface. These ice-nucleating particles (INPs) represent usually a small fraction of particles in an atmospheric aerosol. One of the main particle types which act as INPs are mineral dust particles. Among other factors, the accumulation of semivolatile substances on the particle surface can alter the ice nucleation properties of such particles.

In recent immersion freezing experiments, we investigated the influence of organic acids, amino acids and polyols on the highly ice nucleation active K-feldspar microcline. Microcline dust was suspended in solutions of the above-mentioned substances and frozen in a differential scanning calorimeter (DSC). These experiments give us insight into the ice nucleation characteristics of the particles in the presence of the tested organic and biogenic substances. Our measurements show an overall decrease in ice nucleation activity of microcline in the presence of organic acids and amino acids.
Variations of lithospheric structures around the Mt. Baekdu (Changbaishan) volcano from Bayesian joint inversions with receiver functions and surface wave dispersions
Authors: Lim Yeonjoo , Kim Seongryong
Published: March 2020

The distribution of magmatic structures within lithosphere beneath Mt. Baekdu is important to understand the origin, evolution history, and current status of the volcano. A previous study using ambient noise surface wave dispersions (Kim et al., 2017) suggested a feature of magma fractionation and cooling with layering of mafic and felsic structures in deeper crust. However, the existence of melt directly beneath the Mt. Baekdu and corresponding modification of lithosphere are still unclear. In this study, we additionally calculate P-wave receiver functions for stations in Mt. Baekdu and surrounding regions to confirm the previously defined structures and to check the existence of partial melting. We obtain data from three temporary arrays distributed over areas in Northeast China and DPRK. A harmonic decomposition approach is used to account for anisotropy and to obtain isotropic receiver functions. A series of joint inversions is performed for isotropic receiver functions and surface wave dispersion data using a hierarchical transdimensional Bayesian method. Retrieved isotropic radial receiver functions from stations near (<50 km) the Mt. Baekdu show a consistent negative signal between P and Ps conversion, which indicates low velocity layers in the crust. In addition, relatively high energy of tangential receiver functions with two- and four-lobe patterns indicate that effects of azimuthal anisotropy and/or tilted interfaces are also significant beneath the volcano. On the other hand, stations away from the volcano show features of more isotropic and homogeneous crustal structures. Inverted models show a clear pattern of thicker crust (35-40 km) with slower S-wave velocities (3.2-3.4 km/s in the crust and 4.0-4.2 km/s in the upper mantle) beneath the Mt. Baekdu compared to other regions with relatively shallow Moho (33-35 km) and high velocities (>3.4 km/s in the crust and >4.2 km/s in the upper mantle). The result indicates that a localized structure with elevated temperature and potentially partial melting is exist directly beneath the volcano. With further analysis, more detailed variations of whole lithosphere structures will be presented.
The genesis of a climate archive: snow pack studies at four polar sites
Authors: Freitag Johannes , Hörhold Maria , Weinhart Alexander , Kipfstuhl Sepp , Laepple Thomas
Published: March 2020

Understanding the deposition history and signal formation in ice cores from polar ice sheets is fundamental for the interpretation of paleoclimate reconstruction based on climate proxies. Polar surface snow responds to environmental changes on a seasonal time scale by snow metamorphism, displayed in the snow microstructure and archived in the snowpack. However, the seasonality of snow metamorphism and its link to the deposited signal in isotopes and impurity load is poorly known.

Here, we apply core-scale microfocus X-ray computer tomography to continuously measure snow microstructure of four snow cores from Greenlandic (Renland ice cap-drill site (2m), EASTGRIP drill site (5m)) and Antarctic sites (EDML-drill site (3m), COFI7/Plateau station (4m)) covering a wide range of annual temperatures from -18°C down to -56°C. In our multi-parameter approach we compare the derived microstructural properties on the mm- to cm-scale to discretely measured trace components and stable water isotopes, commonly used as climate proxies. We will show how ice and pore intercepts, the geometrical anisotropy, specific surface area, crusts anomalies and small-scale density distributions are represented under different climate conditions. Their profiles will be discussed in the context of snow metamorphism and deposition history using trace components and isotopes as additional constraints on timing.
Structural styles of the External Rif and Flysch Domain (Rif belt, northern Morocco) through thermal maturity and structural data
Authors: Schito Andrea , Atouabat Achraf , Corrado Sveva , Haissen Faouziya , Mohn Geoffroy , Frizon De Lamotte Dominique
Published: March 2020

Located in northern Morocco, the Rif belt represents the western edge of the Maghrebides system. This domain underwent a significant Cenozoic alpine compressional deformation, due to the collision between the North African margin and the south-western margin of the exotic Alboran Domain. This collision led to the development of a nappe stack during the Miocene.

This contribution aims to characterize the main tectonic mechanisms driving the evolution of the Rifain wedge, its burial-exhumation paths and to understand the former architecture of the North African paleo-margin. The work focuses mainly on the Flysch domain, originated from the Maghrebian branch of the Tethys and on the External domain (namely Intrarif, Mesorif and Prerif) that belong to the former north African margin. To define the thrust sheet stacking pattern and their burial-exhumation paths, a regional transect from Chefchaouen and Ouezzane towns (Central Rif), crossing the orogenic wedge from the Flysch to the Prerif Units is constructed.

The methodological approach consists in combining petrography and Raman micro-spectroscopy on organic matter and 1D thermal modelling, together with field structural data.

A new paleo-thermal data set of vitrinite reflectance (Ro%) and Raman micro-spectroscopy displays levels of thermal maturity between early and deep diagenetic conditions (Ro% ranges from 0.50% to 1.15%).

Preliminary results show an abrupt change in the thermal maturity and the rate of shortening in the Loukkos sub-unit (Intrarif Domain) that is structurally squeezed between Tangier sub-unit (Intrarif Domain) and the “Izzaren Duplex” (Mesorif).

Furthermore, previous studies show that the thickest crust below the Rif fold-and-thrust belt is located below the Izzaren area, suggesting a deep crustal imbrication at the transition between the Intrarif and the Mesorif. These observations joined with the thermal maturity data and 1D thermal modelling allow revisiting the structural evolution of the central part of the Rif belt, by defining the rate of shortening and proposing a new geological restoration with respect to the Mesozoic North African margin structural original setting.
Performance of upcoming CO2 monitoring satellites in the new high-resolution inverse model CTDAS-WRF
Authors: Reum Friedemann , Florentie Liesbeth , Peters Wouter , Dogniaux Matthieu , Crevoisier Cyril , Sic Bojan , Houweling Sander
Published: March 2020

Efforts to reduce greenhouse gas (ghg) emissions require support by independent monitoring. The inverse modeling emission quantification approach, based on measurements of atmospheric ghg mixing ratios, promises objective ghg flux estimates consistent across country borders. Yet, ghg flux quantification on national scales and below is impeded both by the sparsity of atmospheric data and uncertainties in atmospheric ghg transport modeling. To overcome these challenges, the EU supports two concept studies for ghg monitoring satellites via the H2020 projects CHE (CO2M satellite) and SCARBO. Both systems aim at vast coverage and high accuracy and precision. Within these projects, we developed a variant of the CarbonTracker Europe inverse model (van der Laan-Luijkx et al., 2017) that uses WRF-GHG (Beck et al., 2011) to model atmospheric transport (CTDAS-WRF). In this presentation, we first introduce how the versatility of WRF-Chem and modular structure of CTDAS enables our model to estimate ghg fluxes across scales, from point sources to integrated continental fluxes. Next, we used our new model to demonstrate the potential skill of the proposed SCARBO satellite constellation for reducing uncertainties of national-scale CO2 fluxes, focusing on aerosol-induced errors. We demonstrate that this concept has the potential to greatly improve upon existing CO2 monitoring systems because of its unprecedented coverage. Lastly, we outline our plans for using CTDAS-WRF to assess the skill of the proposed CO2M monitoring system to estimate city-scale CO2 emissions.

References:
Beck, V., et al.: The WRF Greenhouse Gas Model (WRF-GHG) Technical Report, [online] Available from: https://www.bgc-jena.mpg.de/bgc-systems/pmwiki2/uploads/Download/Wrf-ghg/WRF-GHG_Techn_Report.pdf, 2011.
van der Laan-Luijkx, I. T., et al.: The CarbonTracker Data Assimilation Shell (CTDAS) v1.0: Implementation and global carbon balance 2001-2015, Geosci. Model Dev., 10(7), 2785–2800, doi:10.5194/gmd-10-2785-2017, 2017.

Acknowledgements:
This work has received funding from the European Union’s H2020 research and innovation programme under grant agreement No 769032 (SCARBO) and 776186 (CHE).
Improving the robustness of single grain K-feldspar IRSL sediment age estimates from active tectonic contexts
Authors: Rhodes Ed , Ivester Andrew
Published: March 2020

The range of applicable contexts for dating fault-offset geomorphic features and seismically deformed sediment has been extended by recent developments in luminescence dating, in particular using the post-IR IRSL (Infra-Red Stimulated Luminescence) at 225 degrees centigrade for single grains of potassium feldspar. Sediments in desert contexts as well as coarse gravels deposited under high-energy fluvial conditions appear to provide consistent age estimates. At first order, single-grain K-feldspar post-IR IRSL-225 is reliable and accurate.

 

However, situations where a deposit is composed of grains that were well-exposed to light prior to burial is reworked at night or during a storm may pose a limitation. The degree that an earlier event may be distinguished from the final deposition depends on the luminescence characteristics of grains, the age difference between the two depositional events, and the proportions of grains each event provides to the target deposit. This effect may be referred to as “shadowing”.

 

We are developing new measurement protocols to help identify grains that were well-bleached, that is they were exposed to sufficient daylight to reduce their trapped charge population to a low level before deposition. We are applying IRSL photochronometry, a determination of light exposure duration, for each grain as part of the dating protocol. This is performed with multiple elevated temperature (MET) IRSL, isolating IRSL signals with different sensitivities to light. Age assessment can be based only on responses from grains that were well-bleached, reducing reliance on the assumption that shared apparent age is correctly identifies depositional age populations. The approach can provide age estimates for multiple past events and information about the environmental conditions that existed before final deposition.
Mapping snow avalanche releases by unmanned aerial vehicles (UAV) in Krkonoše mountain range, the Czech Republic
Authors: Souckova Marketa , Juras Roman
Published: March 2020

Snow avalanche risk in the Czech Republic is mainly constrained to Krkonoše mountains. Approximately twenty snow avalanches release every year during winter season, usually lasting from November to May. Although Krkonoše belongs to mid-mountain range (highest peak 1602 m a.s.l.) due to its prevailing influence of moist, cold air masses and mean annual temperature about 0 °C climate conditions are similar to high-elevation or subpolar climate. Despite the low altitude, Krkonoše experiences considerable avalanche activity at fifty-five permanent paths and even cause fatalities. The monitoring of avalanche releases has been conducted since 1961, therefore most of the avalanches were reported to the extensive database (> 1100 events). The land use of the mountain range is changing and many areas are being deforested resulting in new avalanche prone areas. The presented research is based on results of previous project focused on the avalanche risk assessment in the Krkonoše mountains and thus results are extended, and monitoring methods and creation of avalanche susceptibility maps are improved.

It is clear, from abovementioned, that existing avalanche risk maps have to be reassessed. Therefore, release zones and avalanche susceptibility map must be determined.

Mapping of avalanche activity includes continous monitoring of the avalanche paths by unmanned aerial systems photogrammetry (UAS-P) and ground GPS measurements of the avalanche path. This data will be used for evaluation of the mass movement dynamic model (RAMMS).  Such a monitoring covers:

Determination of release areas and snow heights must be accurate as the RAMMS result simulations are significantly affected by these inputs. This will be measured by UAV as it represents spatially high-resolution mapping of snow depths (accuracy of one decimetre) and due to safety reasons. Furthermore, snow depth determined by photogrammetry is spatially more accurate than interpolation of the ground GPS measures.

Mapping the extent and depth of avalanche deposition along the avalanche track and in the runout zones

Monitoring of snow characteristics in the avalanche prone area and incorporate this data into avalanche susceptibility model

The result of RAMMS model for entire Krkonoše mountain range including czech and polish side will be parametrised and compared to newly obtained data of avalanche releases. The results can be then used by public authorities such as: Krkonoše National Park administrations, Mountain rescue service of the Czech Republic or Institute of Forest Management.

 
Transient tectonic switch in volcanic arcs: observations from the Southern Andes ( 33S - 38S).
Authors: Lupi Matteo , Trippanera Daniele , Gonzalez-Vidal Diego , Tassara Andres , D'Amico Sebastiano , Catalina Cabello , Marc Muelle Stef
Published: March 2020

It has been shown that in the aftermath of megathrust earthquakes the forearc region moves trenchwards promoting crustal extension alterating the long term stress regime in place before the earthquake during the inter-seismic periods. In the far field such variations are less well-recognised and their influence on volcanic arc activity poorly constrained.

To tackle this problem we deployed a temporary seismic network in the volcanic arc of Southern Andes from November 2013 to April 2015 to investigate the tectonic deformation imposed by the M8.8 2010 Maule megathrust earthquake. The network is centred on the Nevados de Chillan Volcanic Complex is an Andean-transverse NW-oriented structure whose orientation is not well compatible with the current tectonic regime. The Nevados de Chillan faces one of the regions that slipped the most during the 2010 M8.8 Maule earthquake. The system was also reactivated after the earthquake and its activity is still ongoing at writing.

We compared the deformation of the geological records such as faults, fractures and dikes (assumed to be representative of inter-seismic periods) against the focal mechanisms inverted from shallow moderate-magnitude earthquakes occurred in the arc from 2010 to 2015. We found out that the geological record shows the imprinting of both long term inter-seismic and perturbed shorter term post-seismic deformation. In particular, the latter may create the conditions to re-activate NW pre-existing tectonic structures enhancing the magma upwelling sitting in the upper lithosphere.

Our work suggests that the kinematics driving the growth of NW-striking volcanic systems in the Southern Central Andes are affected by both magmatic and tectonic processes, with the latter experiencing short-lived perturbations.
Crustal structures across the young and oblique North-eastern Gulf of Aden margin
Authors: Watremez Louise , Leroy Sylvie , d'Acremont Elia , Rouzo Stéphane
Published: March 2020

The Gulf of Aden is a young and active oceanic basin, which separates the south-eastern margin of the Arabian Plate from the Somali Plate. The rifting leading to the formation of the north-eastern Gulf of Aden passive margin started ca. 34 Ma ago when the oceanic spreading in this area initiated at least 17.6 Ma ago. The opening direction (N26°E) is oblique to the mean orientation of the Gulf (N75°E), leading to a strong structural segmentation.

The Encens cruise (2006) allowed for the acquisition of a large seismic refraction dataset with profiles across (6 lines) and along (3 lines) the margin, between the Alula-Fartak and Socotra-Hadbeen fracture zones, which define a first order segment of the Gulf. P-wave velocity modelling already allowed us to image the crustal thinning and the structures, from continental to oceanic domains, along some of the profiles. A lower crustal intermediate body is observed in the Ashawq-Salalah segment, at the base of the transitional and oceanic crusts. The nature of this intermediate body is most probably mafic, linked to a post-rift thermal anomaly. The thin (1-2 km) sediment layer in the study area allows for a clear conversion of P-waves to S-waves at the top basement. Thus, most seismic refraction records show very clear S-wave arrivals.

In this study, we use both P-wave and S-wave arrivals to delineate the crustal structures and segmentation along and across the margin and add insight into the nature of the rocks below the acoustic basement. P-wave velocity modelling allows for the delineation of the structure variations across and along the margin. The velocity models are used as a base for the S-wave modelling, through the definition of Poisson’s ratios in the different areas of the models. Picking and modelling of S-wave arrivals allow us to identify two families of converted waves: (1) seismic waves converted at the basement interface on the way up, just before arriving to the OBS and (2) seismic waves converted at the basement on the way down, which travelled into the deep structures as S-waves. The first set of arrivals allows for the estimation the S-wave velocities (Poisson’s ratio) in the sediments, showing that the sediments in this area are unconsolidated and water saturated. The second set of arrivals gives us constraints on the S-wave velocities below the acoustic basement. This allows for an improved mapping of the transitional and oceanic domains and the confirmation of the mafic nature of the lower crustal intermediate body.
Impact of river confluences on return periods of large floods
Authors: Guse Björn , Wietzke Luzie , Ullrich Sophie , Merz Bruno , Vorogushyn Sergiy
Published: March 2020

The severity of floods is not only affected by the physiogeographic characteristics and the meteorological conditions of the catchment, but also by the river network. If a flood occurs at the same time in tributary and main river, the tributary flood wave can amplify the flood wave in the main river. To investigate the impact of flood wave superposition, the 6-10 largest floods in the four main German river basins (Danube, Elbe, Rhine, Weser) are analyzed. The flood waves are tracked along the river course. Flood magnitude and flood timing are analyzed at each triple point. A triple point consists of the hydrological stations in the tributary and in the main river (upstream and downstream of the confluence). The return periods are calculated separately at each triple point for all three hydrological stations. In addition, changes in the return periods along a river course are analyzed for each flood event. The flood magnitudes and their return periods are compared with the spatiotemporal precipitation distributions and other influencing factors. The results show that the contribution of the different confluences to the flood severity at the main river is event-specific. Partly, the return period is only high at the lower parts of the river basin, partly a high return period in the upper parts of the river basin does not lead to a high return period downstream.
Pressure conditions in coupled magma bodies and their evolution during eruptions and caldera collapse: Piton de la Fournaise 2007
Authors: Sigmundsson Freysteinn , Peltier Aline , Li Siqi , Ferrazzini Valerie , Di Muro Andrea
Published: March 2020

Understanding the interplay between pressure evolution in magma bodies in volcano roots and caldera collapses is important to for the general understanding of volcanoes and how calderas form. We use lessons-learned regarding caldera collapse dynamics and inferred 2014-2015 pressure evolution in a magma body under the Bardarbunga caldera, Iceland, to revisit the dynamics of the 2007 caldera collapse at Piton de La Fournaise volcano, La Reunion, in a project supported by EUROVOLC trans-national access. At Piton de la Fournaise, (rising to 2632 m above sea leve) a shallow and small magma body (close to sea-level; volume less than one cubic kilometer) played a central role. The overpressure compared to lithostatic prior to collapse is inferred to have been small (< 5 MPa), based on models of driving pressure for minor eruptions that occurred on 18-19 February and 30 March prior to the caldera forming lateral flank eruption that occurred 2 April – 1 May, 2007. The site of the lateral flank eruption occurred at an elevation of 500 m, much lower than the summit.  This elevation difference is inferred to a key factor for creating high driving pressure for magma flow. We infer that rapid flow of magma led to fast drop in pressure in a shallow magma body under the caldera, triggering inflow of magma from a deeper magma body under Piton de la Fournaise, that was in important element of the 2007 eruptive activity.  This deep inflow did, however, not sustain enough the pressure in the shallow magma body during the eruption, causing development of significant under-pressure leading to the collapse.
Monitoring marine heatwaves in CMEMS ocean analysis systems
Authors: de Boisseson Eric
Published: March 2020

 Since 2015, CMEMS has been providing near-real time and multi-year ocean analyses that describe both past and current ocean states. In the recent years, the increased frequency of marine heatwave events has raised the attention of the community. Strong and long-lasting events have been shown to have a significant impact on the marine ecosystems and industries. In the work presented here, recent cases of marine heatwaves have been analysed in the ECMWF ORAS5 reanalysis that is part of the CMEMS catalogue of multi-year products. Marine heatwaves are detected from time series of Sea Surface Temperature using a tool developed at CSIRO. Various aspect of the heatwaves are investigated in ORAS5 fields such as the strength and duration of the events and their propagation into the subsurface. The characteristics of recent heatwave events in the North Pacific and off New Zealand as captured in ORAS5 will also be discussed. Particular attention will be brought onto the Pacific Ocean 'Blob', the longest marine heatwave on record that lasted from 2014 to 2016. ORAS5 captured the ‘Blob’ and its propagation down the vertical column in coastal regions where the fishing industry usually strives. The extent of the ecological and economical impact of such an event is still felt to this day. The evolution of future marine heatwave events will be monitored in ORAS5. The predictability of these heat waves at monthly and seasonal range is under investigation.
High-resolution 3D seismic investigation of fine scale faults and fractures along the Vestnesa Ridge, western Svalbard Margin
Authors: Cooke Frances , Plaza-Faverola Andreia , Bünz Stefan , Singhroha Sunny
Published: March 2020

Methane seepage on continental margins derived from shallow gas reserves and gas hydrate stores is significant globally, with initial observations most commonly derived from pockmark expressions on the seafloor. The processes driving fluid flow (liquids and gases) through upper (200m) marine sediments is not well understood. Pockmarks signify present or past seepage events, and are prominent across Vestnesa Ridge. Not all pockmarks are active (venting), suggesting that the mechanism behind fluid flow varies across the ridge.  The main structures observed in the seismic are gas chimneys, faults and fractures. Here we study the characteristics of the observed features through attribute analysis at three significant horizons (age estimates: <0.2Ma, ~0.2Ma and ~1.5Ma). We extract fault orientations through the generation of 3D fault attributes and analysis of fault detect volumes. Attribute extracts at horizons, using amplitude and edge detection methods, together with spectral decomposition and RGB blending, have revealed fine-scale (<10m) faults. High amplitude lineaments at multiple depths match fault trends and radial fracturing is observed around gas chimneys. Small faults propagate outwards from gas chimneys and feed into larger tectonically derived faults, suggesting horizontal inter-connectivity at specific depths.  Enhanced imaging of gas chimneys and small scale features, contribute to our understanding of how fluids migrate through the sediment column. We hypothesize that the connecting fractures, forming between main fault zones may suggest sediment overpressure and restricted flow through tectonically induced faults resulting in horizontal fluid transport.