bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of contamination in the tightrope of Gran Canaria felsic magma differentiation
Authors: Cortes Calderon Edgar Alejandro , Ellis Ben , Neukampf Julia , Harris Chris , Mark Darren , Wolff John , Bachmann Olivier
Published: March 2020

Peralkaline magmatism is mostly sustained by extensive feldspar fractionation from mafic parents at shallow depths in intraplate settings. In this case, silica saturation is critical as it controls the differentiation trend that a peralkaline magma follows. SiO2-oversaturated parents fractionate towards rhyolites, and SiO2-undersaturated towards phonolitic compositions. The Miocene post-shield stage of Gran Canaria records both differentiation trends, which has previously been ascribed to changes in the mantle source. Such stage has been divided in the Mogan and Fataga Group based on silica saturation. Here, we propose that contamination plays a key role in the differentiation of Gran Canaria volcanics. This assumption is supported with new 40Ar/39Ar geochronology, mineral, glass and juvenile clast chemistry (oxygen isotopes, major and trace elements) merged with a detailed stratigraphy. Two types of contaminants were identified, one being cogenetic feldspar-dominated cumulates and the second one being sediments within the island crust. We propose that barium-rich trachytic magmas with positive europium anomalies are linked to melting of the feldspar cumulates left after extensive fractional crystallisation. The chemistry of such trachytes does not follow a liquid line of descent and contains reverse-zoned alkali-feldspars. The shift in silica saturation took less than 1 Ma and is marked by an increase in peralkalinity from 0.9 to 1.5 and a decrease in oxygen isotopes ratio from 7.0 to 5.0 ‰. We interpret these observations as the consequence of maturation of the shallow magma reservoir towards less sediment contamination. Such assimilation of sediments is limited thermally, and compositionally because the system should remain alumina deficient. Crustal assimilation in Gran Canaria did not produce voluminous silicic melts by itself but allowed the deviation of the differentiation trend of a more primitive, initially SiO2-undersaturated magma. The tightrope of differentiation is represented by the thermal divide between the granite and phonolite minima (i.e. feldspar join in petrogeny’s residua system). Contamination by sediments produces a transient SiO2-oversaturated system (Mogan Group). Cogenetic assimilation of cumulates by thermal rejuvenation of the reservoir attracts the magma towards the thermal divide (ubiquitous during the peralkaline stage). Armouring against sediment assimilation through time relaxes the system back to the initial SiO2-undersaturated conditions (Fataga Group).
Estimating surface nitrogen dioxide and ozone concentrations using satellite-based and numerical model-based data
Authors: Shin Minso , Im Jungho
Published: March 2020

Prolonged exposure to high concentrations of nitrogen dioxide (NO2) and ozone (O3) at ground level could be harmful to human health. In-situ air pollutant concentration data observed from ground monitoring stations are limited in providing spatially continuous information. Since there are only a few stations installed above the sea, it is difficult to monitor the concentrations of air pollutants over the sea. In this study, machine learning-based models were developed to estimate ground-level NO2 and O3 concentrations using satellite-based remote sensing data and model-based meteorological and emission data over East Asia during 2015-2017, to overcome such limitations. NO2 and O3 vertical column density products from the Aura Ozone Monitoring Instrument (OMI) were used as essential predictors to estimate NO2 and O3 concentrations. Missing pixels of OMI products due to row anomalies were filled using a temporal convolution approach to generate the spatiotemporally continuous distribution of NO2 and O3 concentrations. In order to estimate the air pollutant concentrations in both land and ocean, specific values were assigned to the ocean for land-only variables. Random forest (RF) was used to develop the estimation models for NO2 and O3 concentrations. The RF-based models showed the results with R2 values of 0.72 and 0.75, and RMSEs of 6.24 ppb and 10.56 ppb for NO2 and O3, respectively. The estimated results over the ocean were validated using coastal stations that are located within a 1 km distance from the coast. Compared to the model without land-only variables, the models using all variables had slightly better results. The satellite-based NO2 and O3 vertical column density were identified as significant variables in both models. Besides, urban land cover ratio, wind-related variables such as wind vectors, and stacked maximum wind speed had relatively high variable importance. The spatial variation of NO2 and seasonal variation of O3 were well shown in the estimated spatiotemporal distribution.
Ground penetrating radar investigations in Quebrada Montes, Lobitos, Peru
Authors: Lok Lai Bun , Almendrades Diego , Alderson Michael , Pizarro Alejandro , Bustamante Andres , Shi John
Published: March 2020

The dry equatorial forests in the north-western coast of Peru suffer from acute water stress and man-driven deforestation. Recent estimates indicate that the forests have reduced to approximately 10% of their original size. There are local reforestation efforts currently underway, for example to prevent the extinction of native species such as the Peruvian Plantcutter songbird (Phytotoma raimondii). However, irrigation needed to support such efforts is severely challenged by the issues of water scarcity in the region. These adverse effects are also being experienced at a local level by the nearby rural community in Lobitos.

The groundwater resources in Lobitos could potentially offer a solution to the above issues for the local community. However, a scientifically informed and sustainable method of mapping and utilising this resource is needed. To provide supporting evidence in this effort, an extensive ground penetrating radar survey was conducted using a commercial 80 MHz impulse radar to characterise the near subsurface within a 90 hectare plot called Ecológica Tallán, which is part of a natural dry water channel in Quebrada Montes and declared as an important conservation area for the district.

Through a pilot study between Lancaster University, EcoSwell Peru and University of Glasgow, we report on initial results from our ground penetrating radar survey to provide a better understanding of the subsurface characteristics in Quebrada Montes, Lobitos.

 
Lunar and Mars analogue research performed at the HI-SEAS research station in Hawaii, part of the EuroMoonMars - IMA - HI-SEAS campaigns
Authors: Musilova Michaela , Foing Bernard , Beniest Anouk , Rogers Henk
Published: March 2020

As of 2018, the International MoonBase Alliance (IMA), has been organizing regular simulated missions to the Moon and Mars at the Hawaii Space Exploration Analog and Simulation (HI-SEAS) habitat. HI-SEAS is a lunar and Martian analog research station located on the active volcano Mauna Loa in Hawaii. The missions that take place at HI-SEAS can be of varied duration, from several days to several months, depending on the needs of the researchers. They are open to space agencies, organizations and companies worldwide to take part in, provided their research and technology testing will help contribute to the exploration of the Moon and Mars. The crews are supported by a Mission Control Center based on the Big Island of Hawaii as well. A series of EuroMoonMars IMA HI-SEAS (EMMIHS) missions have been taking place at HI-SEAS since 2019. These missions bring together researchers from the European Space Agency (ESA), IMA, the International Lunar Exploration Working Group (ILEWG), European Space Research and Technology Centre (ESTEC), VU Amsterdam and many other international organizations. Crews on these missions perform geological, astrobiological and architectural research; technological tests using drones, 3Dprinters and rovers; as well as performing outreach and educational projects. The EMMIHS missions typically last for two weeks each. During this time, the crew is isolated within the HI-SEAS habitat, which they cannot leave without performing EVAs (Extra-Vehicular Activities) in analog space-suits and with the permission of Mission Control. The EMMIHS campaigns aim to increase the awareness about the research and technology testing that can be performed in analogue environments, in order to help humans become multiplanetary species. Furthermore, the research and technological experiments conducted at HI-SEAS are going to be used to help build a Moon base in Hawaii, and ultimately to create an actual Moon base on the Moon, as part of IMA’s major goals. Future missions at HI-SEAS include more EMMIHS campaigns, collaborative missions with ESA, NASA, University of Hawaii, University of South Florida and with companies, such as SIFT and Ketone Technologies.
Free slip conditions in 3D, what does it actually mean ?
Authors: Le Pourhiet Laetitia , Jourdon Anthony , Watremez Louise , Vendeville Bruno
Published: March 2020

For long time,3D tectonic modelling was reserved to analog methods and many practitioners spent a lot of time and energy developing methods and materials to make their naturally 3D "simulations" as cylindrical as possible.

Fighting with so-called boundary effects, they actually obtained a lot of interesting structures and dynamics related to "border effects" . In the last 5 years, 3D numerical simulations have really emerged thanks to new numerical technics and increase in available 'computational power. The two methods are now competing and sooner or later, with the emergence of exa-scale and quantum technology, it is quite certain that numerical simulations will dominate the field because it is much better suited to tackle multi- physics problems arising in long term tectonics.

However, before entering an era of mass production, it is interesting to re-think how we introduce 3 dimensionality in numerical models. Numerical models can easily produce perfectly free slip boundary conditions, and it has therefore never been a problem to simulate a perfectly cylindrical situation. Is it useful ? Not really since we can run 2D simulations.

However, many models introduce the 3 dimensionality by imposing inherited structures in simulations that use perfectly cylindrical boundary conditions. Technically this corresponds to imposing free slip boundaries in the third dimensions. Nobody question it, and in a way, we numerical modellers, are just mimicking traditional analogue model set ups and emphazing on the multi-physics aspect of our simulations.

Yet, comparing to analogue models, we some time reach different solutions and sometimes, analogue models with their boundary effects produce tectonic structures that are much more realistic than models with perfectly free slip boundaries.

In this pico presentation, I will show exemples of free slip boundaries that introduce biased in continental break-up propagation models and discuss in which conditions free slips are acceptable and in which conditions are should be carefull in our interpretations of simulation results.
Impact of site-specific fertilizing management in carbon and water footprint. The case of cotton under Mediterranean conditions
Authors: Papadopoulos Antonios , Troyanos Gerasimos , Kalivas Dionissios , Doula Maria , Kavasilis Stamatios , Zagklis Georgios , Kolovos Chronis
Published: March 2020

In field homogenous application of fertilizers can be considered as a non-environment friendly agricultural practice as it ignores site specific variations of soil and plant properties. Conventional fertilizing management usually results in overfertilization guiding to burdens of the environment in terms of chemical pollution in soil-water system and Greenhouse Gas (GHG) emissions in the atmosphere. The effects are expected to be more severe in Mediterranean region under the evolving climate change. Site-specific fertilizing management on the other hand, poses a practice that is adapted to high precision spatial soil, climatic and plant conditions. In this sense, the agricultural practices are properly adjusted to the needs of the crops. The research is focused on the assessment of the impacts of conventional and site-specific management of nitrogen fertilization to carbon and water footprint at cotton cultivation in field level. The study area concerns two cotton fields in Central Greece that were monitored with the use of classical soil analytical methods and remote sensing sensors throughout a cultivation period. The monitoring process led to the delineation of the fields in different management zones needing variable fertilizing doses. Further, all conventionally applied practices were annotated concerning the last 4-year period in order to collect historical fertilizing data. In both cases (conventional and site-specific) the carbon and water (blue, green, grey) footprints of the two fields were calculated. Carbon footprint was calculated by assessing IPCC 2006 guidelines (updated in 2019) as regards direct and LULUCF emissions. For this, Tier 2 emission factors were used for the main emission categories, as these were defined by the Greek State, while for the other categories, emission factors of Tier 1 of IPCC guidelines were used. For the determination of water footprint, local meteorological data and cotton development stages concerning Greek conditions were used. The determination of the footprints was realized with the use of a software tool developed by the BalkanROAD project in the framework of INTERREG Balkan-Mediterranean 2014-2020 programme, which addresses territorial competitiveness and environment. Preliminary results show encouraging prospective for the improvement of carbon and water footprint when shifting from conventional to site-specific management.
VGOS Intensives Ishioka-Onsala
Authors: Haas Rüdiger , Varenius Eskil , Klopotek Grzegorz , Diamantidis Periklis-Konstantinos , Matsumoto Saho , Schartner Matthias , Nilsson Jan Tobias
Published: March 2020

The VLBI Global Observing System (VGOS) is the VLBI contribution to GGOS. During the last years, several VGOS stations have been established, the VGOS observation program has started, and by 2020 VGOS has achieved an operational state involving eight international VGOS stations. Further VGOS stations are currently installed, so that the number of active VGOS stations will increase drastically in the near future. In the end of 2019 the International VLBI Service for Geodesy and Astrometry (IVS) decided to start a new and so-far experimental VGOS-Intensive series, called VGOS-B, involving Ishioka (Japan) and Onsala (Sweden). Both sites operate modern VGOS stations with 13.2 m diameter radio telescopes, i.e. ISHIOKA (IS) in Japan, and ONSA13NE (OE) and ONSA13SW (OW) in Sweden. In total 12 VGOS-B sessions were planned to be observed between December 2019 and February 2020, one every week, in parallel and simultaneously to legacy S/X INT1 Intensive sessions that involve the stations KOKEE (KK) on Hawaii and WETTZELL (WZ) in Germany. The 1-hour long VGOS-B sessions consist of more than fifty radio source observations, resulting in about 1.6 TB of raw data that are collected at each station. The scheduling of the VGOS-B sessions is done at Vienna University of Technology using VieSched++ and the subsequent steps (correlation, fringe-fitting, database creation) are planned to be carried out at the Onsala Space Observatory using DIFX and HOPS. The resulting VGOS databases are planned to be analysed with several VLBI analysis software packages, involving nuSolve, c5++ and ivg::ASCOT. In this presentation, we give an overview on the VGOS-B series, present our experiences, and discuss the obtained results.
Insights into measuring highly variable and sporadic N2O emissions in a fertile peatland forest with automatic chambers
Authors: Lohila Annalea , Korkiakoski Mika , Ojanen Paavo , Minkkinen Kari , Penttilä Timo , Rainne Juuso , Laurila Tuomas
Published: March 2020

Drainage and other management activities in peatlands make especially the fertile sites a source of greenhouse gases into the atmosphere. In addition to typically losing carbon dioxide (CO2) from the old peat, they act as sources of nitrous oxide (N2O) into the atmosphere. In contrary to CO2, N2O fluxes do not necessarily show a distinct seasonal cycle with high emissions in summer and low in winter. Instead, the most intense peaks in N2O fluxes have been earlier attributed to freezing-thawing cycles of peat soil. Emissions of N2O have been reported to vary greatly both in time and space. Due to instrument limitations, the fluxes have been typically measured using manual chamber technique which provides only a snapshot of the potentially highly dynamic fluxes.

In this presentation we show multi-year results of N2O fluxes captured by automatic chambers and compare those to temporally sparse manual chamber measurements. Our study site was a nutrient-rich drained peatland ‘Lettosuo’ located in Tammela in southern Finland. The peatland, originally an herb-rich tall sedge pine fen was drained for forestry in 1969. After that, the tree stand was a mixture of Scots pine, Norway spruce and Downy birch. N2O fluxes were measured hourly with six automatic chambers. We will address the temporal and spatial variability in the fluxes and the plausible reasons behind them, including the drought of summer 2018, and give a summary of the exploitability of different methods. Suggestions for an improved chamber configuration and for the optimal sampling frequency for manual chambers will be given based on the results.

 

 

 
Using class exercises to actively engage students in Structural Geology and Tectonics courses
Authors: de Bresser Hans
Published: March 2020

The Structural Geology and Tectonics (SGT) course I teach at Utrecht University is a 3rd year bachelor’s degree course with typically 20–40 participants. The course consists of 4 hours of lectures and 4 hours of practical (labs) per week, for a total of 8 consecutive weeks. It is well known that conventional lectures do not form the most effective way of teaching students in terms of learning outcomes, but constraints on classroom availability and (financial) limitations on the number of hours a lecturer is allowed to spend on a course make that we still schedule classical lectures. Interactive lecturing is the way out.

In order to improve student learning during lectures, I actively engage students in the classroom by regularly interrupting my lectures by giving short class-exercises. This is certainly not a new idea, as for example shown by the quick start-up guides for interactive lectures presented at https://serc.carleton.edu/onramps/index.html (NSF funded project). However, in my experience, class exercises are not widely used yet as a useful teaching strategy, which is a regrettable since it is easy to implement. 

I typically give two class exercises per lecture hour. They always have a well-defined aim and task, and take about 3–10 minutes each. The exercises bring back the attention of students, re-emphasize a topic that I’ve just talked about, and give the students a chance to directly apply a concept, equation or technique. The exercises may include a quick calculation, making a measurement, reading a graph, or interpreting a (seismic) section or rock (micro)structure. Discussion with the neighbours is encouraged and the answers are reviewed plenary. There is no formal assessment of individual answers.

Course evaluations show that students very much appreciate the interactive nature of the lectures induced by the class exercises. They feel engaged and later revisit the exercises in preparation for exams. Although hard to quantify, in my experience the exercises improve learning. In this presentation, I’ll show examples of the class exercises I designed, and will put forward the suggestion to come to a shared database of class exercises from which we all can easily draw.
Numerical strategies for characterizing fractured rock from heat tracer experiments
Authors: Roubinet Delphine , Zhou Zitong , Tartakovsky Daniel
Published: March 2020

Characterization of fractured rocks is a key challenge for optimizing heat harvesting in geothermal systems. The use of heat as a tracer, facilitated by the development of such advanced techniques as active line source (ALS) borehole heating and the distributed temperature sensing (DTS), shows the great potential for characterizing fractured rocks. However, there is so far a limited number of theoretical and numerical studies on how these tests could be used for estimating both fracture-network and rock-matrix properties.

We use deep neural networks to describe heat tracer test data and demonstrate how the cumulative density function (CDF) or probability density function (PDF) of the heat tracer test data can be deployed in the inversion mode, i.e., to infer the fracture parameters with. Our approach utilizes the methods of distributions, developed previously to estimate the CDF of solute concentration described by a reactive transport model with uncertain parameters and inputs. The method is applied to analyze several synthetic heat tracer test datasets obtained from a particle-based forward model of transport processes in heterogeneous fractured rocks. The study considers alternative representations of fracture networks with a large range of variation of the fracture network properties, as well as several experimental conditions (e.g., ambient/forced thermal and hydraulic conditions, pulse/continuous changes in temperature). This allows us to characterize the system by combining the information from several thermal tests.
Design and development of lightweight dropsondes for the monitoring of fugitive CO2-emissions from volcanic regions
Authors: Weber Konradin , Fischer Christian , Amend Detlef
Published: March 2020

One of the main compounds emitted by volcanoes or volcanic fields is CO2. This is not only emitted from localized craters, but can emerge as distributed and fugitive emission from extended volcanic regions. In this situation it is of interest to explore the distribution and horizontal concentration profiles of the CO2-emissions.     

For this purpose new dropsondes for sensor measurements of CO2 emissions are under development at the Duesseldorf  University of Applied Sciences. These dropsondes are designed to be dropped from aircraft or drones over volcanic areas in order to map the distributed CO2 concentrations over longer times in an unattended way. They are very lightweight and cheap, so that a large number of dropsondes might be deployed even over remote areas or regions with difficult access. The data are transmitted with GSM broadcasting and can be visualized on a geographical map.

The dropsondes use an NDIR CO2 sensor as a basis for the measurement unit. Additionally to the concentration of CO2 the atmospheric pressure, temperature and humidity are measured. The sensor unit is mounted in a special shock absorbing housing, which is designed to absorb impacts from the touch down after dropping of the sensor and is able to resist even adverse weather conditions.

First measurement results and more details of the design of the sensor unit are presented in this contribution.

 
Retrievals of glyoxal tropospheric vertical columns from TROPOMI observations
Authors: Lerot Christophe , De Smedt Isabelle , Theys Nicolas , Yu Huan , Vlietinck Jonas , Stavrakou Jenny , Müller Jean-François , Friedrich Martina , Hendrick François , Van Roozendael Michel , Alvarado Leonardo , Richter Andreas , Retscher Christian
Published: March 2020

Since its launch in October 2017, TROPOMI records earthshine radiances in spectral ranges from the ultraviolet to the shortwave infrared regions at an unprecedented spatial resolution (3.5 x 7 km² and 3.5 x 5.5 km² after August 2019). A suite of L2 operational products provide key information for the understanding and monitoring of the Earth-atmosphere system, and more particularly of aspects related to ozone layer protection, air quality and climate change.

The ESA S5p+ Innovation activity aims at further exploiting the capability of the TROPOMI instrument by supporting the development of a number of additional scientific products, including glyoxal tropospheric column retrievals. The latter provide information on VOC emissions as glyoxal is mainly released in the atmosphere as an intermediate product of VOC oxidation, but also directly emitted from biomass burning events.

We present here the BIRA-IASB S5p glyoxal product relying on a DOAS approach and its main features. We show how the large amount of TROPOMI data and its high resolution helps to better identify and localize VOC sources. The many intense fire events that occurred in the last years, e.g. in Northern America in 2018 or in Australia in 2019/2020, led to extreme levels of pollution and unprecedentedly high glyoxal columns are measured accordingly. We also highlight the excellent consistency between the TROPOMI and OMI glyoxal products, allowing thus to combine them in a 15-year data record. The validation of satellite glyoxal retrievals is difficult due to the scarcity of independent data and their own limitations caused by the low glyoxal optical depth. Nevertheless, a few ground-based data sets have been collected and preliminary comparisons with the S5p glyoxal product are presented.
Peatland hydrological behavior with global warming
Authors: Ferraris Stefano , Canone Davide , Gisolo Davide , Putti Mario , Teatini Pietro , Previati Maurizio
Published: March 2020

A peat deposit close to Venice was monitored both in the field and in the lab (1) to investigate the hydrological response of peat soil to changing meteorological conditions in the frame of land subsidence assessment. The whole area is about 3 meters lower than the sea level and therefore subsidence is a major issue. Predictions highlighted the risk of an almost complete disappearance of the peat layer in this area during the next 50 years, due to the increased frequency of warmer periods. Unfortunately, despite the considerable impacts that are expected to affect peatland worldwide, only a few measured datasets are currently available to assess the response of a peat deposit to enhanced drying due to global warming.

The lab measurements were performed both at the pedon and at the core scale. An undisturbed peat monolith of approximately 0.7 m3 was collected, transferred to the lab, and instrumented to monitor matric potential, water content, and total weight. This undisturbed peat lysimeter allows to monitor water content variations (both through the weight monitoring and time domain reflectometry sensors), and matric potential, with drier conditions with respect to the field campaign. A complete cycle of wetting and drainage was performed, raising the water table from the bottom to the top of the sample and down again. Additional measurements of matric potential and water content were collected by testing peat cores on a suction table.

A set of water retention curves was experimentally determined. They were derived for a range of  matric potential much broader than that experienced in situ . Variations were found, with respect to the field natural conditions, in the relations between the matric potential and the volumetric water content of different horizons as a result of the initial prolonged drying. Also, the hysteresis behaviours in the lab and in the field were different, with much wider loops in the lab conditions because of extended range of potential. Hydraulic non-equilibrium between the water content and water potential could also  be a possible cause, but further modelling work is necessary to assess it. The van Genuchten parameters were obtained for both wetting and drying, for modelling purposes.

(1) Previati et al. (2019), Hydrological Processes.
Did this really happen?! Analysis of a two-year initiative to draw everyday sexism in academia.
Authors: Arnould Maëlis , Adenis Alice , Bocher Marie , Coltice Nicolas , Gérault Mélanie , Mallard Claire , Ulvrova Martina
Published: March 2020

Like any other workplace, academia is not free from everyday gender stereotypes and sexist behaviours. They participate in the feeling of insecurity and devaluation of women and gender non-conforming individuals, which ultimately contributes to a persisting gender imbalance in this environment. Building on this observation, the Did this really happen?! project, born in 2018, aims at reporting real occurrences of everyday sexism experienced within the scientific community. Using comic strips, we raise awareness about such behaviours and their pernicious consequences, which are often difficult to notice. Through our website www.didthisreallyhappen.net, we have now collected more than 100 contributions from researchers all over the world, describing sexist biases that they have faced or witnessed in academia. We have already turned 25 of them into anonymous comics that we publish without any comments on the website. In hindsight, we have identified six repeating categories of sexist behaviours: 1) those that aim at maintaining women in stereotypical feminine roles, 2) those that aim at maintaining men in stereotypical masculine roles, 3) those that question the scientific skills of female researchers, 4) those where women have the position of an outsider, especially in informal networking contexts, 5) those that objectify women, and 6) those which express neosexist views. Here, we present our project in more details, propose a detailed analysis of these sexist situations, and we are happy to discuss further ways to engage with the scientific community on this topic.
Observations and simulations from an arctic fjord and valley environment in Svalbard
Authors: Jonassen Marius Opsanger , Wickström Siiri , Cassano John , Vihma Timo , Spengler Thomas , Kral Stephan , Frank Lukas , Reuder Joachim , Valkonen Teresa , Kähnert Marvin , Kristiansen Jørn
Published: March 2020

We present results from a set of field campaigns conducted in an arctic valley and fjord environment in central Spitsbergen, Svalbard. These field campaigns, which are conducted as part of a graduate class at the University Centre in Svalbard (UNIS), address a range of phenomena typical for the arctic atmospheric boundary layer using both observational and numerical means. These phenomena include low-level jets, cold pools, drainage flows, and air-sea interactions, several of which typically are challenging to accurately model. On the observational side, we utilise a range of sensors and instrumentation platforms, such as portable weather stations, a tethersonde (anchored weather balloon), small temperature sensors (TinyTags), sonic anemometers, automatic weather stations, and drones. As of this year, the sensor suite will also constitute a wind lidar and a microwave temperature profiler. The resulting datasets represent a unique model-independent data set from a region where observations are otherwise sparse. On the numerical side, we utilise data from the high-resolution (2.5 km horizontal grid spacing) AROME-Arctic weather prediction model. AROME Arctic is run operationally by the Norwegian Meteorological Institute (MET Norway) for a domain covering Northern Fennoscandia, larger parts of the Barents Sea, and Svalbard. We use the model data both to plan our fieldwork and for interpreting our observations. In turn, we use the observations for improving our understanding of the mentioned phenomena and also for validating the model.
Modelling the effects of permeability, groundwater flow and water table depth on landscape evolution
Authors: Luijendijk Elco
Published: March 2020

The role of groundwater flow in determining overland flow, drainage density and landscape evolution has long been debated. Landscape models often only address groundwater as a simplified storage term and do not explicitly include lateral groundwater flow, although recently some model codes have started to include lateral flow. However, the role of groundwater flow on landscape evolution has not been explored systematically to my knowledge. Here I present a new numerical and analytical model that combines groundwater flow, saturation overland flow, hillslope diffusion and stream erosion. A number of model experiments were run with different values of transmissivity and groundwater recharge. The model results demonstrate that transmissivity, groundwater flow and the depth of the watertable strongly govern overland flow, the incision of stream channels and erosion rates. The results imply that the permeability and transmissivity of the subsurface are important parameters for explaining and modelling landscape evolution.  
Generating an exclusion map for SAR-based flood extent maps using Sentinel-1 time series analysis
Authors: Zhao Jie , Chini Marco , Pelich Ramona , Matgen Patrick , Hostache Renaud , Cao Senmao , Wagner Wolfgang
Published: March 2020

Change detection has been widely used in many flood-mapping algorithms using pairs of Synthetic Aperture Radar (SAR) intensity images. The rationale is that when the right conditions are met, the appearance of floodwater results in a significant decrease of backscatter.  However, limitations still exist in areas where the SAR backscatter is not sufficiently impacted by surface changes due to floodwater. For example, in shadow areas, the backscatter is stable over time because the SAR signal does not reach the ground due to prominent topography or obstacles on the ground (e.g., buildings). Densely vegetated forest is another insensitive region due to low capability of SAR C-band wavelengths to penetrate its canopy. Moreover, although in principle SAR can sense water over different land cover classes such as arid regions, streets and buildings, the backscatter changes over time could not be detected because in such areas the scattering variation caused by the presence of water might be negligible with respect to the normal “unflooded” state. The identification of the abovementioned areas where SAR does not allow detecting water based on change detection methods, hereafter called exclusion map, is crucial for providing reliable SAR-based flood maps.

In this study, insensitive areas are identified using long time-series of Sentinel-1 data and the final exclusion map is classified in four distinctive classes: shadow, layover, urban areas and dense forest. In the proposed method the identification of insensitive areas is based on the use of pixel-based time series backscatter statistics (minimum, maximum, median and standard deviation) coupled with a local spatial autocorrelation analysis (i.e. Moran’s I, Getis-Ord Gi and Geary’s C). In order to evaluate the extracted exclusion map, which is quite unique, we employ a comprehensive ground truth dataset that is obtained by combining different products: 1) a shadow/layover map generated using a 25m-resolution DEM and the geometric acquisition parameters of the SAR data; 2) 20m resolution imperviousness map provided by Copernicus, as well as a high-resolution global urban footprint (GUF) data provided by DLR; 3) a 20m tree cover density (TCD) map provided by Copernicus. In the end, the exclusion map is used to mask out unclassified areas in the flood maps derived by an automatic change detection method, which is expected to enhance flood maps by removing areas where the presence or absence of floodwater cannot be evidenced. In addition, we argue that our insensitive area map provides valuable information for improving the calibration, validation and regular updating of hydraulic models using SAR derived flood extent maps.
Radiative transfer simulations and observations of airborne infrared emission spectra in the presence of PSCs: Detection of clouds and discrimination of cloud types
Authors: Kalicinsky Christoph , Grießbach Sabine , Spang Reinhold
Published: March 2020

Polar stratospheric clouds (PSCs) have an important influence on the spatial and temporal
evolution of different trace gases, (e.g. ozone, HNO3) in the polar vortex in winter due to direct
and indirect processes (e.g. activation of chlorine, redistribution of HNO3). Thus, the detection
of PSCs and a detailed distinction between the different PSCs types Nitric Acid Trihydrade
(NAT), Supercooled Ternary Solution (STS), and ice are important as they build a basis for
model comparisons to reduce uncertainties in the representation of PSCs in models. Infrared
limb sounder are well suited for this purpose as they enable both, the detection of clouds and
the discrimination between the different types.
The CRISTA-NF instrument, an airborne infrared limb sounder, observed a new spectral fea-
ture during measurements inside PSCs within the RECONCILE aircraft campaign. In contrast
to the previously known feature at 820 cm-1, which has been used in former studies for the
detection of NAT PSCs, the new feature was detected at about 816 cm-1. We performed a
large set of radiative transfer simulations for different PSC situations (varying PSC altitude
and thickness, PSC type, number density and median radius of the particle size distribution)
for the airborne viewing geometry of CRISTA-NF. The simulation results show that under the
assumption of spherical NAT particles the spectral feature transforms from the original feature
at 820 cm-1 to a shifted version (peak shifts to smaller wavenumbers) and finally to a step-like
feature with increasing median radius. Based on this behaviour we defined different colour ra-
tios to detect PSCs containing NAT particles and to subgroup them into three sizes regimes:
small NAT, medium size NAT, and large NAT. In addition, we used the simulation results to
adopt a method, which has been used to detect ice in MIPAS-ENV observations, to the airborne
geometry and to refine the corresponding threshold values.
We applied all methods of cloud detection and type discrimination to the CRISTA-NF observa-
tions during the RECONCILE campaign. The new defined NAT detection method is capable
to detect the shifted NAT feature, which is clearly visible in the radiance spectra.
Double cropping in the Amazon: its relation with moisture recycling
Authors: O'Connor John , T. Rebel Karin , J. Santos Maria , C. Dekker Stefan , A. Tuinenburg Obbe
Published: March 2020

Land use and land cover change in the Amazon results in the loss and degradation of ecosystem services vital to human wellbeing. The land-use transitions from forest to grasslands and to croplands modify the hydrological cycle as the non-forest cover has lower evapotranspiration and increased runoff.
The high rates of evapotranspiration of the Amazon forest drive the atmospheric moisture recycling system, which not only supports the forest itself but provides atmospheric moisture for precipitation downwind, important for agriculture, human consumption and hydropower across central Brazil. While deforestation reduces overall precipitation,  deforestation has also been correlated with a delay in the wet season onset leading to a longer dry season. Therefore agriculture presents itself as an interesting conundrum, as it is the main driver of deforestation, it also acts as both the degrader and one of the main beneficiaries of the system.

 

Recent advances in soybean double-cropping have increased agricultural productivity. However, as sowing is tightly coupled to the wet season onset, this strategy is dependent on a stable wet season onset.

Here, we analyse the contribution of terrestrial evapotranspiration to precipitation during the early wet season. We employed a Lagrangian moisture transport model which connects moisture source (evapotranspiration) locations with moisture sink (precipitation) locations in the agriculture state of Mato Grosso, Brazil. We calculated the fraction of precipitation derived from moisture recycling as well as estimate the delay in wet season precipitation under a scenario without moisture recycling. Finally, using this moisture transport model we identified and mapped source areas that contribute to two existing double-cropping locations, one in the Amazon biome (North) and one in the Cerrado biome (South).

We found that during the wet season transition, roughly 35% of the precipitation across Mato Grosso originates from moisture recycling. The fraction of moisture recycled precipitation is spatially correlated with latitude and longitude with the lowest fraction in the Northeast ≈20% and highest in the Southwest ≈60%. Both cropping locations showed a highly dispersed source area of precipitation. With 30% of recycled rainfall generated within 250 km of the precipitation location. The two cropping locations we analyzed shared a number of forest source areas highlighting their importance for moisture recycling. We found a 10-day delay in accumulated precipitation in our scenario without moisture recycling. This implies that double-cropping systems would become more uncertain as the sowing of soybean would most likely be delayed further into the year.
Partition of Ni, Ca and Mn between olivine and carbonated silicate melt
Authors: Zhan Ming-Jun , Zhang Guo-Liang , Wang Shuai
Published: March 2020

Phenocrysts of olivine with high Ni, low Mn and Ca relative to global MORBs are usually attributed to a stronger role of the pyroxenite melting (Soblev et al., 2005). The Hawaiian shield stage lavas (high Si group) with high bulk-rock and olivine Ni have usually been attributed to the role recycled oceanic crust. However, the Hawaiian plume also produces lavas with Si-undersaturated alkali basalt (low Si group) and relatively low Ni, whose origin has not been well understood. In this study, we examine the role of deep carbon on the magma compositions and their influences on olivine geochemistry. Here by comparing the whole rock and olivine geochemistry data of Hawaiian high Si group basalts with Hawaiian low Si group basalts, we find that the primary magmas of the latter have relatively lower Ni but comparable concentrations of Mn and Ca. However, the high Si group basalt olivines have indistinctive partition coefficient of Ni but significantly lower Mn and Ca than those of the high Si group basalts.

The deep Earth is a large reservoir of carbon, which when participates in mantle melting would significantly influence the mantle residual minerals and melt compositions. For example, mantle melting with CO2 is commonly shown to reduce SiO2 in the melts. Thus, the genesis of the Si-undersaturated alkali basalts has usually been attributed to the role of CO2 (Zhang et al., 2017). The role of CO2 in the genesis of Hawaiian alkali lavas have also been predicted in previous studies. Based on the observations from Hawaiian lavas, we suggest that CO2 played a key role in lowering the partition coefficients of Mn and Ca. We have conducted high pressure-temperature melting experiments on mantle rocks with CO2, and find that CO2 has a potential influence on the partition of Ni, Mn and Ca between olivine and silicate melts, more experiments remain to be further conducted. This work was financially supported by the National Natural Science Foundation of China (91858206, 41876040).
Using In-Situ Juno Observations to Understand the Evolution of Interplanetary Coronal Mass Ejections Within 1 AU and Beyond
Authors: Davies Emma , Forsyth Robert , Good Simon
Published: March 2020

Understanding the evolution of interplanetary coronal mass ejections (ICMEs) as they propagate through the heliosphere is essential in forecasting space weather severity. Much of our knowledge of ICMEs has been gained using in-situ measurements from single spacecraft, although the increasing number of missions in the inner heliosphere has led to an increase in multi-spacecraft studies improving our understanding of the global structure of ICMEs. Whilst most such recent studies have focused on the inner heliosphere within 1 AU, Juno cruise phase data provides a new opportunity to study ICME evolution over greater distances. We present analysis of ICMEs observed in-situ both by Juno and at least one other spacecraft within 1 AU to investigate their evolution as they propagate through the heliosphere. Investigation of the sheath region and timing considerations between spacecraft allows for the general shape of the shock front to be reconstructed. Combining in-situ observations and results of flux rope fitting techniques determines the global picture of the ICME as it propagates. However, effects on in-situ observations due to radial evolution and due to the longitudinal separation between multi-spacecraft remain hard to separate. We note the importance of the interplanetary environment in which the ICME propagates and the need for caution in radial alignment studies.  
Dyke segmentation: an experimental approach
Authors: Chàvez-Alvarez Maria Jazmin , Cerca-Martìnez Mariano
Published: March 2020

Hydrofractures induced by a pressurized fluid inside a solid host material occur in nature as joints, veins, and dykes. Due to the heterogeneity of the material properties, rock structure, fluid rheology, and in-situ stress state, the process of hydrofracturing in nature is highly complex. As a result, it is difficult to measure and predict the behavior of natural hydrofractures in field conditions. Fracture segmentation is observed in most materials at every scale from microns to kilometres and dykes are not the exception.  In particular, dykes not always emplace as individual, symmetric and planar structures in the host rock. In many cases even in homogeneous rocks, dykes exhibit segmentation of the type of en chelon-like structures and fingering. The causes of dyke segmentation have been associated with: (1) rock heterogeneity (i.e. pre-existing structures); (2) mixed-mode I+III loading; and (3) instabilities of dike growth process. However, there are still many open questions related to the origin of dyke segmentation, including at which level each of the mentioned processes influences its propagation. In order to have a first approach of study to this phenomenon, a series of laboratory experiments in transparent materials of dyke propagation have been performed. We present the results of experiments of analogue dykes that transport Newtonian and shear thinning fluids that lead to segmentation, in absence of rotational stresses and heterogeneity of the host media. We use these experiments as the most direct source of observations of dike geometry. These experiments allowed the visualization in real time of the developing geometry of the analog dykes and the direction of their propagation.
Assessment of the continuity of the orogenic root beneath the Cantabrian-Pyrenean orogen
Authors: Fernández-Viejo Gabriela , Cadenas Patricia , Acevedo Jorge , Llana-Funez Sergio
Published: March 2020

Crustal roots are a consequence of the contraction of continental masses during orogenesis identified in collisional chains worldwide. Frequently mirroring the summits of mountain systems, they portray the fundamental topic of isostasy. The northern Iberian Peninsula presents a rugged topography resulting of the collision with the European plate and the partial closure of the Bay of Biscay during the Cenozoic. Three differentiated systems formed along, from east to west:  a continental collisional chain, the Pyrenees, occupying the isthmus between Iberia and Europe; facing the Bay of Biscay, a deep Mesozoic basin inverted during contraction, the Basque-Cantabrian region, and in the west a crustal pop-up of Palaeozoic basement, the Cantabrian Mountains. The last two extend underwater in the form of a shortened platform, and an accretionary wedge fossilized by post orogenic sediments. The identification of a crustal root beneath the Pyrenees in the 80´s and the observation of a similar morphology beneath the Cantabrian range in the 90´s gave place to the interpretation of the thickening as a continuous feature of the Iberian crust. 
However, a reappraisal of vintage refraction profiles and new data from autocorrelations of ambient noise recordings, challenge the alleged continuity. The Pyrenean-Cantabrian orogeny is a three-plate interaction. Beyond the three types of convergent boundaries we may need to introduce the hyperextended-continent destructive boundary, where this is a well-studied example but not the only one. 