bluuebunny/crossref_metadata_2025 huggingface dataset:
Zooming in: a single-cell perspective on nitrogen fixation in the rhizosphere of rice
Authors: Schmidt Hannes , Gorka Stefan , Seki David , Schintlmeister Arno , Woebken Dagmar
Published: March 2020

Our current understanding of microbial hotspots such as the rhizosphere mainly stems from observations through measurements at the macroscopic scale, integrating a multitude of microbial cells and taxa into a few measured variables. Consequently, we still lack an understanding of the individual participants that actively contribute to processes. Identifying microorganisms and relating their activity to these processes within the soil-plant interface on a microscopic scale represent a missing link in understanding nutrient flux in agriculturally important ecosystems such as rice cultivation.

I will present a novel workflow for single-cell isotope imaging in the rhizosphere that combines fluorescence in situ hybridization, gold-targeted secondary electron microscopy, and nano-scale secondary ion mass spectrometry. Based on correlative microscopy and hotspot detection, this approach now allows to (i) identify single bacteria on root surfaces that actively incorporate stable isotopes, (ii) quantify their contribution to processes of interest within a given population, and (iii) potentially trace nutrient fluxes among plants and bacteria on a microscale.

Illuminating plant-microorganism interactions on a microscale provides the potential to evaluate the actual impact of bio-inoculants applied as fertilizers and to engineer plant-microorganism associations which may be essential to increase the production of major staple crops for a growing world population.
Online ground temperature and soil moisture monitoring of a shallow geothermal system with non-conventional components
Authors: Duran Ludwin , Mottaghy Darius , Herrmann Ulf , Groß Rolf
Published: March 2020

We present first results from a newly developed monitoring station for a closed loop geothermal heat pump test installation at our campus, consisting of helix coils and plate heat exchangers, as well as an ice-store system. There are more than 40 temperature sensors and several soil moisture content sensors distributed around the system, allowing a detailed monitoring under different operating conditions.

In the view of the modern development of renewable energies along with the newly concepts known as Internet of Things and Industry 4.0 (high-tech strategy from the German government), we created a user-friendly web application, which will connect the things (sensors) with the open network (www). Besides other advantages, this allows a continuous remote monitoring of the data from the numerous sensors at an arbitrary sampling rate.

Based on the recorded data, we will also present first results from numerical simulations, taking into account all relevant heat transport processes.

The aim is to improve the understanding of these processes and their influence on the thermal behavior of shallow geothermal systems in the unsaturated zone. This will in turn facilitate the prediction of the performance of these systems and therefore yield an improvement in their dimensioning when designing a specific shallow geothermal installation.
New remote radio observations of Jupiter by Parker Solar Probe
Authors: Lecacheux Alain , Bale Stuart D. , Maksimovic Milan , Pulupa Marc
Published: March 2020

The FIELDS/RFS experiment aboard the Parker Solar Probe spacecraft, in orbit around the Sun, is able to detect and remotely study low frequency radio emissions from Jupiter. Accurate measurements of the intensity and polarisation of those emissions (mainly the HOM/DAM components) were obtained throughout years 2018 and 2019. They are compared to similar ones, obtained 20 years ago, during Cassini’s remote flyby of Jupiter. A particular emphasis is brought on the so-called “attenuation bands” phenomenon, - a well-defined intensity extinction/enhancement feature modulating the HOM dynamic spectrum -, which likely results from the radiation propagating to the observer through some permanent or long lived plasma structure (not firmly identified so far) lying in the rotating Jovian inner magnetosphere.
Climate change and recovery from eutrophication reduce benthic fauna and carbon processing in a coastal sea
Authors: Ehrnsten Eva , Norkko Alf , Müller-Karulis Bärbel , Gustafsson Erik , Gustafsson Bo
Published: March 2020

Nutrient loading and climate change affect coastal ecosystems worldwide. Unravelling the combined effects of these pressures on benthic macrofauna is essential for understanding the future functioning of coastal ecosystems, as it is an important component linking the benthic and pelagic realms. In this study, we extended an existing model of benthic macrofauna coupled with the physical-biogeochemical BALTSEM model of the Baltic Sea to study the combined effects of changing nutrient loads and climate on biomass and metabolism of benthic macrofauna historically and in scenarios for the future. Based on a statistical comparison with a large validation dataset of measured biomasses, the model showed good or reasonable performance across the different basins and depth strata in the model area. In scenarios with decreasing nutrient loads according to the Baltic Sea Action Plan, but also with continued recent loads (mean loads 2012-2014), overall macrofaunal biomass and carbon processing were projected to decrease significantly by the end of the century despite improved oxygen conditions at the seafloor. Climate change led to intensified pelagic recycling of primary production and reduced export of particulate organic carbon to the seafloor with negative effects on macrofaunal biomass. In the high nutrient load scenario, representing the highest recorded historical loads, climate change counteracted the effects of increased productivity leading to a hyperbolic response: biomass and carbon processing increased up to mid-21st century but then decreased, giving almost no net change by the end of the 21st century compared to present. The study shows that benthic responses to environmental change are nonlinear and partly decoupled from pelagic responses and indicates that benthic-pelagic coupling might be weaker in a warmer and less eutrophic sea.
Effect of a surface biofilm on sediment transport implemented in a 1D numerical model
Authors: Bastianon Elena , Malarkey Jonathan , Parsons Daniel
Published: March 2020

The transport of sediment shapes rivers and deltas, and has a huge impact on natural fluvial processes and human interaction within these environments. Conservation and hydraulic engineering applications in river basins crucially depend on understanding the processes of scour, transport and deposition of sediments. The sediment entrainment process in mathematical models are typically based on laboratory experiment using clean (abiotic) sediments. However, natural sediments are rich in biological communities, often forming visible biofilms which include sticky Extracellular Polymeric Substances (EPS). The presence of biological communities has been shown to significantly increase the critical shear stress of sediment entrainment compared with clean sediment, and these communities are recognized as ‘ecosystem engineers’ as they act as bio-stabilizers. Furthermore, biofilms provide stability, such that only the most energetic conditions can remove them in a sudden catastrophic way. In this study, a one-dimensional (1D) morphodynamic model for rivers is implemented to account for the development and growth of a surface biofilm subject to variable hydrodynamic disturbances (e.g. tidal forces) and with a biofilm-dependent erodibility. The 1D form of the shallow water equations are simplified with the aid of the quasi-steady approximation and the Exner equation expressing the conservation of bed material is used to compute the changes in channel bed elevation. The effect of geochemical drivers such as light, temperature and nutrients, which affect the presence or absence and growth of a biofilm, is accounted for in the model. Previous studies have shown that when sediments are covered by biofilms, entrainment occurs via biomat failure and the carpet-like detachment of biofilm-sediment composites. Different hydrodynamic conditions are tested to investigate their role in eroding the biofilm and detaching it from the sediment surface.
Internal wave energetics modulated by Indonesian Throughflow at Lombok Strait
Authors: Xu Zhenhua
Published: March 2020

The interaction between the energetic internal waves in the Indonesian Seas and the Indonesian Throughflow (ITF) is not well known. Here we conduct a series of high-resolution numerical simulations surrounding the Lombok Strait, Indonesia, which is an important exit channel for the ITF, to explore the influences of the ITF on the spatiotemporal variations of M2 internal tides and associated internal solitary waves from the Strait. The ITF enhances the north-south asymmetry of internal tide propagation from the Lombok Strait, thus resulting in the spatial variability of northward and southward internal solitary waves. Interannual variability of internal tide generation and dissipation are due to ITF and air-sea freshwaterflux induced stratification variations associated with El Niño-Southern Oscillation. The local dissipation efficiency q exhibits substantial seasonal and interannual variations, which may provide effective feedback to the climate processes in the low-latitude equatorial oceans.
Machine Learning for Cloud Masking
Authors: Sjöberg Johan , Jackson Sam , Adamek Karel , Armour Wesley , Thiyagalingam Jeyarajan
Published: March 2020

As the importance of satellite readings grows in fields as varied as meteorology, urban planning and climate change science so has the importance of satellite reading accuracy. This has in turn lead to an increased need for accurate cloud masking algorithms given the large impact that clouds have on the accuracy of these readings. At the moment there are some automatic cloud masking algorithms, including one based on Bayesian statistics. However, they all suffer from precision issues as well as issues with misclassifying normal natural phenomena such as ocean sun glint, sea ice and dust plumes as clouds. Given that these natural phenomena tend to be concentrated in certain regions, this also implies that the precision of most algorithms tends to vary from region to region.

This has led to eyes increasingly turning to machine learning and image segmentation techniques to perform cloud masking. In this presentation it will be described how and with what result these techniques can be applied to Sentinel-3 SLSTR data with the main focus being techniques that are variations of the so called fully convolutional networks (FCNs) originally proposed by Long and Shelhamer in 2015. Given that FCNs have performed well in areas such as medical imaging, facial detection, navigation systems for self-driving cars etc., there should be a large potential for them within cloud detection.

The presentation will also look into the regional variability of these machine learning techniques and whether one can improve the overall cloud masking accuracy by developing models specifically for a region. Furthermore, it will aim to demonstrate how one can, by performing simple perturbation techniques, increase the interpretability of the model predictions something that is a salient issue given the somewhat black box-like nature of many machine learning models.
Polar microbes and their implications in the aquatic mercury cycle
Authors: Lavergne Céline , Heimburger Lars-Eric , Bovio-Winkler Patricia , Chamy Rolando , Cabrol Léa
Published: March 2020

The methylmercury has the feature, in addition to its high toxicity for living organisms, to be easily incorporated, bioaccumulated and biomagnified through the food web in aquatic systems. Recently, the microorganisms implicated in the transformation of mercury to methylmercury have been found much more diverse than previously thought. Among them, 9 methanogenic Archaea strains are able to methylate the mercury in pure culture. However, few proofs exist in situ in polar aquatic systems. Antarctic polar regions receive atmospheric mercury through long-range transport of foreign emissions. In a context of increasing releases of heavy metals in aquatic environments and atmosphere, it is a crucial objective to elucidate the fate of mercury in Antarctic polar aquatic ecosystems and the role Archaea could play in mercury transformations. Hence, microbial diversity was investigated in pristine Antarctic lakes (South Shetland Islands, Antarctic, Chile) and continental sub-Antarctic beaver ponds (Tierra del Fuego, Chile) where benthic total mercury concentration was 14 ±6.5 and 89 ±13 ppm, respectively. Until 6.3% of the active community could be constituted by putative methylators and a positive significant correlation was found between total mercury concentration and putative methylator relative abundance (linear model, p-value=0.001). Putative methylator Archaea Methanoregula and Methanosphaerula have been detected but did not seem active in the studied ecosystems (RNA metabarcoding VS DNA metabarcoding).

Combined with these molecular data, mercury methylation and methylmercury demethylation activities were performed by addition of enriched stables isotopes of inorganic mercury and methylmercury, respectively and we expect to find highest methylation rates in the rich-organic matter ecosystems such as sub-Antarctic beaver ponds.
WiSED: A Quality-Controlled Surface Wind European Database
Authors: Rojas-Labanda Cristina , González-Rouco J. Fidel , García-Bustamante Elena , Navarro Jorge , Lucio-Eceiza Etor E. , Van de Schrier Gerard , Kaspar Frank
Published: March 2020

Surface wind is a fundamental meteorological variable that is relevant for a wide array of topics (e.g., crop growth, extreme events, power generation). Yet, for many regions, there is still a scarcity of good quality observational datasets and the uncertainties within data sources like reanalysis products and between those and observational databases are large, limiting the understanding of this variable and hampering the accuracy of subsequent analyses.

In order to address this need and within the frame of the NEWA's (New European Wind Atlas) project, a quality-controlled Wind Surface European Database (WiSED) is created. WiSED feeds from eight different datasets, provided by different institutions and with varying levels of quality control. This initial version is then submitted to a Quality Control (QC) process structured into six phases that deal with the detection of various issues in data quality: 1) compilation; 2) duplication errors; 3) physical consistency in the ranges of recorded values; 4) temporal consistency, regarding abnormally high/low variability in the time series; 5) detection of medium-term biases; and 6) removal of isolated records. The first three phases deal with issues often related to data storage and management, whereas the last three phases deal with measurement errors related to problems in the instruments, calibration procedures or siting.

The improved quality of the data and the high temporal and spatial resolution, as well as its spatial coverage, represents an added value over previous products available for the same region. 

This work summarises the application of the quality control, showing the results of different steps throughout it. Additionally, a preliminary analysis of the surface wind behaviour over Europe is presented.

With a maximum timespan of about 100 years, the creation of such database will allow for analyzing different aspects of both wind speed and direction variability over Europe from intra-daily to multidecadal timescales. Within the potentially relevant applications, it is worth to mention: the identification of subregions in Europe with homogeneous wind behaviour (regionalization), statistical downscaling exercises, analyses of wind extremes, wind power assessment and evaluation of climate model, both global and regional, simulations.
Multi-scale ocean colour synergy products for coastal water quality monitoring
Authors: Van der Zande Dimitry , Alvera-Azcárate Aida , Troupin Charles , Cardoso Dos Santos João , Van den Eynde Dries
Published: March 2020

High-quality satellite-based ocean colour products can provide valuable support and insights in the management and monitoring of coastal ecosystems. Today’s availability of Earth Observation (EO) data is unprecedented including medium resolution ocean colour systems (e.g. Sentinel-3/OLCI), high resolution land sensors (e.g. Sentinel-2/MSI) and geostationary satellites (e.g. MSG/SEVIRI). Each of these sensors offers specific advantages in terms of spatial, temporal or radiometric characteristics. In the Multi-Sync project, we developed advanced ocean colour products (i.e. remote sensing reflectance, turbidity, and chlorophyll a concentration) through the synergetic use of these multi-scale EO data taking advantage of spectral characteristics of traditional medium resolution sensors, the high spatial resolution of some land sensors and the high temporal resolution of geostationary sensors.

To achieve this goal a multi-scale DINEOF (Data Interpolating Empirical Orthogonal Functions) approach was developed to reconstruct missing data using empirical orthogonal functions (EOF), reduce noise and exploit spatio-temporal coherency by joining several spatial and temporal resolutions. Here we present the capacity of DINEOF to extract multi-scale information through the integration of Sentinel-3, Sentinel-2 and SEVIRI datasets.

The functionality of the advanced multi-scale products will be demonstrated in a case study for the Belgian Coastal Zone (BCZ) highly relevant to the user community: sediment transport modelling near the harbour of Zeebrugge in support of dredging operations. As stated in the OSPAR treaty (1992), Belgium is obliged to monitor and evaluate the effects of all human activities on the marine ecosystem. Dredging activities in and near Belgian harbors fall under this treaty and are performed daily to ensure accessibility of the port by ships. Optimization of these dredging activities requires monitoring data which is typically acquired through in situ observations or modelling data. In this case study we take advantage of Sentinel-3, Sentinel-2 and SEVIRI data characteristics to provide a satellite product that meets the end user requirements in terms of product quality and temporal/spatial resolution.

 
Total Electron Content and Seismic Ambient Noise analysis prior to significant earthquakes
Authors: Sahu Sabyasachi , Borah Kajaljyoti , Champati ray Prashant Kumar
Published: March 2020

The seismo-ionospheric interaction study with respect to earthquake events using Total Electron Content (TEC) data derived from Global Navigation Satellite Systems (GNSS) receivers can be used to detect pre-earthquake ionospheric anomalies. This is primarily because ionospheric anomaly variation has been emerged as one of the most promising precursors. In recent times, many studies have reported pre-seismic ionospheric anomalies of TEC prior to major earthquakes. However, the results are not uniform and therefore, considerable amount of data processing and validation is required before this can be used in operational mode.  To ensure the seismogenic cause of TEC variation, geomagnetic and solar-activities are also compared with TEC values prior to the earthquakes and our analysis has proved that TEC anomalies can be used as earthquake precursors. Several global events and Himalayan earthquakes have been studied and results are very encouraging for developing a methodology that can qualify for detection of early sign of earthquakes. It may be far from early warning system (EWS) with information on magnitude, location and time, but it is a significant achievement in the field of earthquake geology where no methodology exists on forewarning of seismic events.

 Seismic velocity changes computed by applying modern techniques in seismic interferometry reveals that considerably large earthquakes can trigger a decline in seismic velocity prior to the mainshock. Cross-correlation of diffuse wave fields, including ambient seismic noise can provide the Green’s function between pair of receivers recording seismic activity. Using the known properties of the seismic ambient noise, recorded over a large period of time, seismic velocity changes before the earthquake has been observed which can act as a potential precursor. Decrease in the seismic velocity few days before the main event suggest that co-seismic damage begins to occur even before the mainshock, which could be a result of foreshocks. The main shock records the lowest relative seismic velocity change. The potential use of the ambient noise as an earthquake precursor can be concluded after rigorous analysis.
Cultivation of industrial hemp using solid and liquid residues from municipal composting
Authors: Hirsch Florian , Matvejeva Agne , Dietrich Nils , Raab Thomas
Published: March 2020

Industrial hemp as a renewable raw material for fiber extraction like for construction material or as biomass for energy generation is a potential agricultural product for low productive soils in temperate climates. Soil and climate conditions in Lower Lusatia, South Brandenburg, generally qualify this region suitable for growing industrial hemp. But due to the nutrient requirements of the plants, fertilization is necessary for optimal growth. Fertilization on sandy soils is, however, often problematic, since the groundwater risk is increased by the entry of nitrogen and phosphorus from the fertilizer supply. In addition, the costs of fertilizers make resource-efficient and sustainable use of the locations problematic. The liquid phase obtained in the course of municipal composting would be a suitable fertilizer in terms of nutrient concentrations, but due to the potential risk to groundwater, the use of the liquid phase from composting is currently not feasible. The aim of the project is the development of a closed cultivation system for industrial hemp using hydroponics, whereby sand and pelleted soil additives from composting are used as a supporting substrate. Nutrients from the liquid phase from the municipal composting will be used as fertilizer. The cultivation will take place under controlled conditions (light, temperature, watering water and leachate) in a glasshouse experiment. A mixture of sand and pelletized soil additives is to be tested as a plant substrate in various additional amounts. The sandy substrate is representative for the soils in Lower Lusatia. The use of pelletized soil additives in combination with the liquid phase from municipal composting is an innovative process and on the one hand contributes to the development of a new sales market and on the other hand promotes the local and resource-saving use of recyclables in the sense of the circular economy. The use of hydroponics is a promising process that can be used regardless of the climate and without endangering soil and groundwater.
Investigating manganese dynamics in a coupled catchment-reservoir system: Lake Blagdon – SW England
Authors: Waterhouse Jack , Kjeldsen Thomas , Bryant Lee
Published: March 2020

Drinking water security in the UK is facing increasing pressure from rising demand, fuelled by population growth and rising periods of drought. Monitoring and regulation of water quality and related internal biogeochemical processes within drinking-water reservoirs is therefore paramount to maintaining security of supply, as well as allowing continued efficient and cost-effective management. In aquatic systems, internal biogeochemical processes are controlled by a complex set of oxygen-controlled forcing mechanisms; as diffuse pollution inputs from upstream catchments enter oxygen-dynamic reservoirs that frequently include nutrient- and metal-rich sediment, deleterious soluble chemical species (e.g., trace metals such as manganese, Mn) can be released from the sediment to the overlying water. Mn in particular is a problem for drinking water treatment plants. In light of oxygen-related water quality issues, almost all UK drinking water utilities use aeration systems to optimise oxygen concentrations and corresponding water quality and ecosystem health. 

Blagdon Lake in Somerset, SW England is one such medium-size (1.8km2), shallow depth (max: 13.1m) drinking-water reservoir underlain by Mn-rich sediments. The goal of this project was to investigate the dynamics of Mn release into the overlying water, by coupling a catchment model (SWAT) and a reservoir model (CE-QUAL-W2) together. The coupled whole-system model would be assessed using multiple atmospheric, land-use, and catchment management scenarios to discern the driving processes of Mn release and quantify risk to future water security.

An extensive five-month field campaign was undertaken in Summer 2019 to build water quality time series and calibration datasets for the reservoir model (CE-QUAL-W2). Techniques and equipment deployed during the field work included: water sample filtration & soluble/insoluble Mn analysis at 2m depth intervals; permanently installed thermistor chains using Onset TidbiT v2 loggers at 1m depth resolution; water quality profiles from an EXO3 Sonde, logging pH, chlorophyll-α, conductivity, and turbidity; and surface sediment core Mn analysis. This data was then collated with atmospheric data (ERA5), and existing datasets of nutrient concentration data at multiple inflows (inc. NO2/NO3, Ammonium, Total P/Ortho P). Initial analysis of the data collected during the field campaign suggest that periods of stratification align with elevated Mn concentrations in the water column, directly relating soluble Mn release to air temperature.
Design of database systems for optimized spatio-temporal querying to facilitate monitoring, analysing and forecasting in the "Internet of Water"
Authors: Bollen Erik , R. Pagán Brianna , Kuijpers Bart , Van Hoey Stijn , Desmet Nele , Hendrix Rik , Dams Jef , Seuntjens Piet
Published: March 2020

Monitoring, analysing and forecasting water-systems, such as rivers, lakes and seas, is an essential part of the tasks for an environmental agency or government. In the region of Flanders, in Belgium, different organisations have united to create the ”Internet of Water” (IoW). During this project, 2500 wireless water-quality sensors will be deployed in rivers, canals and lakes all over Flanders. This network of sensors will support a more accurate management of water systems by feeding real-time data. Applications include monitoring real-time water-flows, automated warnings and notifications to appropriate organisations, tracing pollution and the prediction of salinisation.

Despite the diversity of these applications, they mostly rely on a correct spatial representation and fast querying of the flow path: where does water flow to, where can the water come from, and when does the water pass at certain locations? In the specific case of Flanders, the human-influenced landscape provides additional complexity with rivers, channels, barriers and even cycles. Numerous models and systems exist that are able to answer the above questions, even very precisely, but they often lack the ability to produce the results quickly enough for real-time applicability that is required in the IoW. Moreover, the rigid data representation makes it impossible to integrate new data sources and data types, especially in the IoW, where the data originates from vastly different backgrounds.

In this research, we focus on the performance of spatio-temporal queries taking into account the spatial configuration of a strongly human-influenced water system and the real-time acquisition and processing of sensor data. The use of graph-database systems is compared with relational-database systems to store topologies and execute recursive path-tracing queries. Not only storing and querying are taken into account, but also the creation and updating of the topologies are an essential part. Moreover, the advantages of a hybrid approach that integrates the graph-based databases for spatial topologies with relational databases for temporal and water-system attributes are investigated. The fast querying of both upstream and downstream flow-path information is of great use in various applications (e.g., pollution tracking, alerting, relating sensor signals, …). By adding a wrapper library and creating a standardised result graph representation, the complexity is abstracted away from the individual applications.
Winter NAO significantly influences Baltic SST values throughout spring and summer
Authors: Piskozub Jacek
Published: March 2020

The aim of the study was to test the possibility of improving prediction skills of Baltic SST values throughout the year using past NAO index value. This could be possible due to the strong effect of NAO on Central and North European winter (DJFM) temperatures and the large thermal capacity of a sea, even as shallow as the Baltic.

 

First, the correlations of monthly NAO index and SST fields have been calculated. Significant (p<0.05) correlations were noted only in the central and southern Baltic in January, February and March, unlike in the air temperature - not shown – when significant correlations last from December to March. This may suggest one month delay in NAO affecting SST. To test this delay directly correlations with one month delay were performed showing significant values for five months of the year (from December to April SST temperatures).

 

Next, the main test of the study was performed by calculating the lagged correlations of average winter (DJFM) NAO values with SST fields. The results show that winter NAO significantly affects SST first in the central and southern basins (April to June) and later (July-September) also in the Bothnian Bay in the north. In some regions (mainly close to the Gulf of Riga) the influence of winter NAO is significant even in October, seven months after the end of the DJFM period when NAO influences the air temperatures. This shows that the effect must be caused by changes of heat content of the sea water. Also the fact that the effect of winter NAO spreads northwards during the summer can be explained with advection due to sea currents.

 

The results show that winter NAO values can be used to improve the skill of seasonal predictions of Baltic SST values in spring and summer. They also imply that if the observed significant correlation of the winter NAO values with global temperature will continue in the next decades, the prevailing positive winter NAO values should result in the spring and summer Baltic SST warming at a faster rate than the adjacent land.
New modified and extended stability functions for the stable boundary layer based on SHEBA data
Authors: Gryanik Vladimir M. , Grachev Andrey , Lüpkes Christof , Sidorenko Dmitry
Published: March 2020

The calculation of the near-surface turbulent fluxes of energy and momentum in climate and weather prediction models requires transfer coefficients. Currently used parametrizations of these coefficients are based on stability functions derived from measurements over land and not over sea ice. However, recently, a non-iterative parametrization has been proposed by Gryanik and Lüpkes (2018), which can be applied to climate and weather prediction models as well but uses stability functions of Grachev et al. (2007). These functions had been obtained from measurements during the Surface Heat Budget over the Arctic Ocean campaign (SHEBA) and thus from measurements over sea ice. A drawback of the scheme of Gryanik and Lüpkes (2018) is that there is still some complexity due to the complexity of the SHEBA based functions.

Thus new stability functions are proposed for the stable boundary layer, which are also based on the SHEBA measurements but avoid the complexity. It is shown that the new functions are superior to the former ones with respect to the representation of the measured relationship between the Obukhov length and the bulk Richardson number. Moreover, the resulting transfer coefficients agree slightly better with the SHEBA observations in the very stable range. Nevertheless, the functions fulfill the same criteria of applicability as the earlier functions and contain furthermore as an extension a dependence on the neutral Prandtl number. Applying the new functions, an efficient non-iterative parametrization of the near-surface turbulent fluxes of momentum and heat is developed where transfer coefficients result as a function of the bulk Richardson number (Rib) and roughness parameters. The new transfer coefficients, which are recommended for weather and climate models, agree well with the SHEBA data in a large range of stability (0< Rib<0.5) and with those based on the Dyer-Businger functions in the range Rib <0.08.

References

Grachev A.A., Andreas E.L, Fairall C.W., Guest P.S., Persson POG (2007) Boundary-Layer Meteorol., 124, 315–333.

Gryanik, V.M. and Lüpkes C. (2018) An Efficient Non-iterative Bulk Parametrization of Surface Fluxes for Stable Atmospheric Conditions Over Polar Sea-Ice,Boundary-Layer Meteorol 166:301-325
Testing geodynamic models with major elements geochemistry: implications for Edge-Driven Convection and Mantle plumes
Authors: Manjón-Cabeza Córdoba Antonio , Ballmer Maxim D. , Allison Chelsea , Gazel Esteban
Published: March 2020

Numerical modeling facilitates the exploration of geodynamic mechanisms that are inaccessible to direct geological sampling. However, quantitative comparison of geochemical signatures predicted by models with real petrological analyses remains restricted. On one hand, efficient melting parameterizations are limited in the information that they provide, on the other, thermodynamic models are not optimized for 3D geodynamic codes. In the Eastern Atlantic, several archipelagos are located near the continental margin, e.g. the Canaries, Cape Verde, Cameroon Volcanic Line, but the origin of this volcanic activity remains poorly understood. Suggested origins range from mantle-plume activity (deep origin) to Edge-Driven Convection (EDC, shallow origin), or an interaction of both mechanisms. To test and constrain these models, we use a recently developed parameterization, which can constrain major-element geochemistry of primary magmas in the form of wt% as a function of the P-T path, together with regional numerical models of EDC with or without plumes. In this work, using the finite-element code CITCOM, we explore 3D models with a step of lithospheric thickness (or “edge”) and with variable distances between an imposed plume and the edge. We predict characteristic compositional trends that depend on model parameters, such as plume temperature or distance of the plume from the continental edge, and compare them with actual melt-inclusion data from the Canary Islands and Cape Verde. We find geochemical trends ranging from alkalic – for the models without thermal anomalies or with weak plumes – to more tholeiitic – for the cases with vigorous plumes. In turn, EDC alone cannot explain the volcanic fluxes observed at the Canary Islands or Cape Verde, with predicted melting rates well below 1 km3 Myr-1. Comparison with melt inclusions points towards the importance of CO2, but a thermal anomaly (plume) is also needed. We use the obtained major elements together with the melt volumes and the plume buoyancy flux to constrain the most likely set of mantle properties that originate the aforementioned islands. Our preferred model is a weak, relatively cold plume (ΔT < 150 ˚C), moderately rich in volatiles, that is affected by the nearby EDC pattern.
ESA CCI and C3S Soil Moisture: latest product updates and climate assessments
Authors: Dorigo Wouter , Preimesberger Wolfgang , Pasik Adam , Gruber Alexander , Moesinger Leander , Scanlon Tracy
Published: March 2020

As part of the European Space Agency (ESA) Climate Change Initiative (CCI) a more than 40 year long climate data record (CDR) is produced by systematically combining Level-2 datasets from separate missions. Combining multiple level 2 datasets into a single consistent long-term product combines the advantages of individual missions and allows deriving a harmonised long-term record with optimal spatial and temporal coverage. The current version of ESA CCI Soil Moisture includes a PASSIVE (radiometer-based) dataset covering the period 1978 to 2019, an ACTIVE (scatterometer-based) product covering the period 1991-2019 and a COMBINED product (1978-2019). 

The European Commission’s Copernicus Climate Changes Service (C3S) uses the ESA CCI soil moisture algorithm to produce similar climate data records from near-real-time Level-2 data streams.  These products are continuously extended within 10 days after data acquisition and instantaneously made available through the C3S Climate Data Store. In addition to a daily product, monthly aggregates as well as a dekadal (10-days) products are produced.

In this presentation we give an overview of the latest developments of the ESA CCI and C3S Soil Moisture datasets, which include the integration of SMAP and various algorithmic updates, and use the datasets to assess the hydrological conditions of 2019 with respect to a 30-year historical baseline.

The development of the ESA CCI products has been supported by ESA’s Climate Change Initiative for Soil Moisture (Contract No. 4000104814/11/I-NB and 4000112226/14/I-NB). The Copernicus Climate Change Service (C3S) soil moisture product is funded by the Copernicus Climate Change Service implemented by ECMWF through C3S 312b Lot 7 Soil Moisture service.
Longitudinal Gradients in Field-Aligned Currents as Observed by Swarm
Authors: Marghitu Octav , Blăgău Adrian , Vogt Joachim
Published: March 2020

Field-aligned currents (FACs) are closely related to aurora and a key component of the magnetosphere-ionosphere-thermosphere system. Large scale FAC structures, like Region 1 / Region 2, threading the whole auroral oval, as well as smaller scale FACs, associated with auroral arcs, are often assumed to consists of upward / downward current sheet pairs, uniform in longitudinal direction. While such a uniformity is consistent with the prevalent 1D symmetry of the auroral arcs and oval, longitudinal gradients may develop at times, for example when the 1D symmetry prepares to break, during the growth phase of auroral substorms. The Swarm mission provides optimum conditions to explore systematically longitudinal gradients in FACs, namely a proper spacecraft configuration, with the Swarm A / Swarm C pair lining up periodically with Swarm B at auroral latitudes, and high quality magnetic field data. The present report concentrates on a set of auroral events observed by the Swarm satellites, in this suitable configuration, during the first six months of the mission operational phase. At that time, the distance between Swarm A / Swarm C and Swarm B was in the range of a few 100 km, comparable to the length scale of electrojet currents associated with auroral arcs. Not surprising, longitudinal gradients in FACs are occasionally significant, a feature which is discussed with respect to the location, activity level, and substorm phase of the event.
Saharan dust deposited in Lake Bastani, Corsica: The northernmost dust record of the termination of the Holocene African Humid Period?
Authors: Leblanc Maxime , Skonieczny Charlotte , Sabatier Pierre , Colin Christophe , Miska Serge , Govin Aline , Bout-Roumazeilles Viviane , Bory Aloys , Debret Maxime , Jouffroy-Bapicot Isabelle , Vannière Boris
Published: March 2020

Throughout the Quaternary, variations of the insolation received over Africa have governed the monsoon dynamics in this region, generating a recurrence of intense rainfall periods. These African Humid Periods (AHP) are characterized by a major transformation of the Saharan hydrological cycle, favouring the development of vast fluvial systems and tropical humid ecosystems in the currently hyper-arid Sahara Desert. In the current context of global warming, the mechanisms as well as the environmental responses associated with these periods of rapid changes between two extreme climatic contexts remain crucial to understand. Many studies have investigated the mechanisms associated with the last AHP that occurred in the early Holocene (9 to 5ka), and more particularly its initiation and termination. Despite all these efforts, these climatic transitions remain highly debated (e.g. influence of high latitudes versus regional forcing, vegetation feedback). Here, we propose to improve our understanding of the Holocene AHP by studying Saharan dust deposited in Lake Bastani (Corsica, western Mediterranean) during the last 12ka. Indeed, as dust emissions are function of the aridity of their sources, among other parameters such as wind intensity, Saharan dust fluxes recorded over and out of Africa may represent an indirect way to reconstruct Sahara past hydrological changes. Bastani Lake is a high elevation system with a very restricted watershed and has been described as a natural Saharan dust trap during the last 3ka (Sabatier et al., accepted). In this study, we present a Holocene multi-proxy characterization of the fine-grained sediments recorded in Bastani lake. We develop a multiproxies approach based on mineralogy and major elements composition of the clay fraction as well as microscopic observations and quantification of the biogenic silica, which complicates Saharan dust supply estimation in this system. This effort to decipher the Bastani lake sediments composition will allow us to qualify and quantify the Saharan dust signal from the bulk sediment record (watershed erosion/alteration, biogenic silica productivity) in order to discuss, to our knowledge, the northernmost aeolian response of the Sahara desert hydrological changes of the termination of this key climatic transition.

 

Reference: Sabatier et al., Past African dust inputs in Western Mediterranean area controlled by the complex interaction between ITCZ, NAO and TSI, Climate of the Past, accepted.

Keywords: Saharan dust, Saharan hydrological cycle, Paleoclimatology, Holocene, clay mineralogy, geochemistry, biogenic silica.
Greenhouse Gas Emission Estimate Using a Fully-automated Permanent Sensor Network in Munich
Authors: Dietrich Florian , Chen Jia , Voggenreiter Benno , Zhao Xinxu
Published: March 2020

To effectively mitigate climate change, it is indispensable to know the locations of the emission sources and their respective emission strength. As the majority of greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4) and carbon monoxide (CO) are generated in cities, our focus lies in the emission determination of urban areas. For this reason, we established a fully-automated sensor network in Munich, Germany to permanently measure GHGs.

Our permanent network is based on the differential column measurement principle [1] and measures the city emissions using five FTIR spectrometer systems (EM27/SUN from Bruker [2]). For these spectrometers we built a self-developed enclosure system and equipped them with several sensors (e.g. computer vision based solar radiation sensor) to measure the column-averaged concentrations of CO2, CH4 and CO in a fully-automated way. The difference between the column amounts inside and outside of the city reflects the pollutants abundance generated in the city. Four stations are placed at the city outskirts to capture the inflow/outflow column amounts in arbitrary wind conditions. One inner-city station, which has already been operating successfully since 2016 [3], is serving as a permanent downwind site for half of the city.

With the help of atmospheric transport models, combined with a Bayesian inverse modelling approach, those concentration differences are transferred into spatially resolved emission estimates of the city. After testing the network in two campaigns (2017 and 2018), the network is finally long-term operating since summer 2019 and continuously measures the GHG concentrations in Munich. We will show both the hardware achievements and first measurement and emission results after ten month of operation.

[1] Chen et al.: Differential column measurements using compact solar-tracking spectrometers. Atmos. Chem. Phys., 16: 8479–8498, 2016.

[2] Gisi et al.: XCO2-measurements with a tabletop FTS using solar absorption spectroscopy, Atmos. Meas. Tech., 5, 2969-2980, 2012

[3] Heinle and Chen: Automated Enclosure and Protection System for Compact Solar-Tracking Spectrometers, Atmos. Meas. Tech., 11, 2173-2185, 2018
Relation between the magnetic free energy and relative magnetic helicity in the MHD extreme state of solar corona
Authors: Yang Shangbin , Buechner Joerg , Zhang Hongqi
Published: March 2020

Magnetic helicity is a quantity describing the twist, writhe, and torsion of magnetic field lines and magnetic configurations . The concept of magnetic helicity has successfully been applied to characterize solar coronal processes. A conjecture about one approximation relation between free magnetic free energy and relative magnetic helicity in the MHD extreme state of solar corona has been proposed by using the concept of magnetic helicity conservation and Lie-Poisson mechanical structure of MHD. We use constant α force-free filed extrapolation to check out this relation. We also apply this relation to analyze the results from the simulations and observations. Such relation may be helpful to predict the solar activity like the solar flares and CMEs
The TopoToolbox v2.4: new tools for topographic analysis and modelling
Authors: Scherler Dirk , Schwanghart Wolfgang
Published: March 2020

The TopoToolbox v2 (TT2; available at https://github.com/wschwanghart/topotoolbox) (Schwanghart and Scherler, 2014) is a set of functions for the analysis of digital elevation models (DEM) in the MATLAB programming environment. Its functionality is mainly developed along the lines of hydrological and geomorphic terrain analysis, complemented with a wide range of functions for visual display, including a class for swath profiles. Fast and efficient algorithms in TopoToolbox form the backbone of the numerical landscape evolution model TTLEM (Campforts et al., 2017). In this presentation, we will demonstrate new functionalities that are part of the upcoming release v 2.4: DIVIDEobj and PPS.

DIVIDEobj is a numerical class to store, analyze and visualize drainage divide networks. Drainage networks are derived from flow directions and a stream network. We will present the extraction and analysis of the drainage divide network of the Big Tujunga catchment, CA, to illustrate it functionality and associated analysis tools. PPS is a class to explore, analyze and model spatial point processes on or alongside river networks. Specifically, PPS provides access to a set of statistical tools to work with inhomogeneous Poisson point processes that facilitate the statistical modelling of phenomena such as river bank failures, landslide dams, or wood jams at the regional scale.

Campforts, B., Schwanghart, W., and Govers, G.: Accurate simulation of transient landscape evolution by eliminating numerical diffusion: the TTLEM 1.0 model, Earth Surface Dynamics, 5, 47-66. https://doi.org/10.5194/esurf-5-47-2017, 2017.

Schwanghart, W., and Scherler, D.: Short Communication: TopoToolbox 2 – MATLAB-based software for topographic analysis and modeling in Earth surface sciences, Earth Surf. Dynam., 2, 1-7, https://doi.org/10.5194/esurf-2-1-2014, 2014.