bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Neogene carbonate productivity and terrigenous input in the central Western Pacific Warm Pool (IODP Site U1488)
Authors: Drury Anna Joy , Westerhold Thomas , Ravelo Ana Christina , Aiello Ivano , Wilkens Roy , Röhl Ursula , Kulhanek Denise
Published: March 2020

As the largest modern reservoir of oceanic heat, the Western Pacific Warm Pool (WPWP) plays an important role in atmospheric and oceanic circulation patterns. Little is known about how regional deposition patterns have changed over the past 10 Ma. To understand the interplay between regional processes and global climate evolution in the WPWP, we explore the late Neogene evolution of biogenic (carbonate/siliceous) versus terrigenous deposition.

We collected high-resolution (2 cm/~0.5 kyr) X-Ray fluorescence (XRF) core scanning data at IODP Site U1488 (Exp. 363) in the central WPWP. These data were especially useful for estimating the carbonate, siliceous and terrigenous components below 65 m CCSF, where the shipboard track data were less robust. The shipboard splice was verified and revised using the Ba/Sr ratio to ensure a continuous composite section down to ~330 m revised CCSF-A at Site U1488. Fe and Si likely reflect terrigenous and partially biogenic silica components. We calibrated the high-resolution ln(Ca/K) record to %CaCO3 using discrete shipboard %CaCO3 measurements.

Fe and Si decrease, whilst ln(Ca/K) increases downcore, in agreement with shipboard data showing increasing %CaCO3 and decreasing terrigenous/siliceous input­. During the late Pleistocene, the site shows high amplitude %CaCO3, Fe and Si cycles superimposed on low carbonate. The amplitude decreases during the early Pleistocene-mid Pliocene, although clear variability remains. The early Pliocene-late Miocene is dominated by high CaCO3 (80-90%). The %CaCO3, Fe and Si variability is considerably reduced, although clear obliquity-precession interference patterns are visible, in addition to longer-term ~400 kyr eccentricity modulation. The high-carbonate interval at IODP Site U1488 likely reflects the early Pliocene to late Miocene Biogenic Bloom (LMBB). The expression of the LMBB in the WPWP is distinctly different to the Atlantic and eastern equatorial Pacific. This indicates that although productivity was enhanced during the late Miocene-early Pliocene, regional processes determined the exact expression and timing of the LMBB in different areas.
Towards a more reliable reconstruction of the historical solar variability: a more realistic description of solar ephemeral magnetic regions
Authors: Hofer Bernhard , Krivova Natalie A. , Wu Chi-Ju , Usoskin Ilya A. , Cameron Robert
Published: March 2020

Solar irradiance is a crucial input to climate models, but its measurements are only available since 1978. The variability of solar irradiance on climate-relevant time-scales is caused by the competition between bright and dark features formed by the magnetic fields emerging on the solar surface. Thus, models have been developed that reconstruct past irradiance variability from proxies of the solar magnetic activity. The longest direct proxy is the sunspot number. The common problem of such reconstructions is, however, that while sunspots adequately describe the evolution of the active regions (ARs) (large bipolar regions hosting sunspots), the evolution of their smaller counterparts, the ephemeral regions (ERs), is not directly featured by sunspots. At the same time, these small regions are much more numerous and are believed to be the main source of the long-term irradiance changes, which are of special interest to climate models. We develop an improved description of the ephemeral region emergence taking different solar observational constraints into account. The model builds on the SATIRE-T model, in which the emergence of ARs is described by the sunspot number and the emergence of the ERs is linearly linked to that of ARs. The latter, however, implies that whenever the sunspot number drops to zero, no magnetic field emerges in the model. In the new model, the emergence of the ERs is no longer linked to sunspots linearly. Instead, ARs and ERs are considered to be parts of a single power-law size distribution of the emerging magnetic regions. This ensures that even in the absence of ARs (e.g., during the grand minima of solar activity), the emergence rate of ERs remains non-zero. In particular, the solar open magnetic flux reconstructed using this approach does not drop to zero during the Maunder minimum, in agreement with independent reconstructions from the cosmogenic isotope data. Such an improved description of the ERs will allow a better constraint on the maximum solar irradiance drop during grand minima events. This, in turn, will allow a better constraint on the potential solar forcing in the future.
The sensitivity of a critical zone model to the representation of hydraulic conductivity heterogeneity in a deeply weathered hard rock aquifer in West Africa
Authors: Herzog Amelie , Hector Basile , Cohard Jean-Martial , Lawson Fabrice-Messan , Vouillamoz Jean-Michel , de Graaf Inge
Published: March 2020

Currently 40 % of Africa's population still lacks access to clean water. Twice as many rural people live in hard rock areas as compared to sedimentary areas. In these hard rock areas a thick weathered regolith layer covers the crystalline basement, where groundwater (GW) circulates. In the Sudanian area of West Africa (WA) ,groundwater levels are shallow enough to interact directly with the surface water. Therefore, constructing coupled surface-groundwater models helps to estimate quantities of both, GW and surface flows, and their evolution over time to facilitate integrated water management. However, the sensitivity of such models to aquifer properties (saturated hydraulic conductivity (Ks), porosity, geometry), which are difficult to obtain in heterogeneous crystalline contexts, is still poorly constrained. The heterogeneity of aquifer properties at the scale at which most water management decisions are taken, is twofold: 1) bimodal vertical heterogeneity with an unconsolidated weathered zone (high porosity, low Ks) overlying a fissured zone (low porosity, high Ks) and 2) lateral heterogeneity controlled by substratum features and weathering history. We assessed the sensitivity of a coupled surface-groundwater model (PARFLOW-CLM) to vertical and lateral heterogeneity of Ks. The sensitivity to the lateral heterogeneity was explored either using simulations with homogeneous or distributed Ks following random field approaches with a range of spatial correlation lengths. The representation of a vertically uniform aquifer layer was compared to a two-layer scenario for each of the lateral heterogeneity cases. Here, we focused our analysis on the Northern Oueme catchment in Benin (14 000 km²) and we constructed a model with a spatial resolution of 1 km², preventing the analysis of smaller-scale features, such as macropores or clay accumulations. Hydraulic conductivity and aquifer geometry data to constrain the sensitivity experiments were derived from the literature specific to the target area, but also from regional hard rock aquifers in West Africa. As an output of the model, we obtained streamflow, water table head and evapotranspiration time series (in a monthly and daily resolution). The results that we gained with our model configuration (and resolution) point towards a low sensitivity of the model to lateral and vertical heterogeneity. However, we observed a significant impact of the magnitude of Ks on water table head and particularly on the streamflow amplitude. Regarding the water balance our results show that further exploration of the subsurface is crucial to improve critical zone modeling in the context of WA.
Top-down Support of Swiss non-CO2 Greenhouse Gas Emissions Reporting to UNFCCC
Authors: Henne Stephan , Vollmer Martin K. , Steinbacher Martin , Leuenberger Markus , Meinhardt Frank , Mohn Joachim , Emmenegger Lukas , Brunner Dominik , Reimann Stefan
Published: March 2020

Globally, emissions of long-lived non-CO2 greenhouse gases (GHG; methane, nitrous oxide and halogenated compounds) account for approximately 30 % of the radiative forcing of all anthropogenic GHG emissions. In industrialised countries, ‘bottom-up’ estimates come with relatively large uncertainties for anthropogenic non-CO2 GHGs when compared with those of anthropogenic CO2. 'Top-down' methods on the country scale offer an independent support tool to reduce these uncertainties and detect biases in emissions reported to the UNFCCC. Based on atmospheric concentration observations these tools are also able to detect the effectiveness of emission mitigation measures on the long term.

Since 2012 the Swiss national inventory reporting (NIR) contains an appendix on 'top-down' studies for selected halogenated compound. Subsequently, this appendix was extended to include methane and nitrous oxide. Here, we present these updated (2020 submission) regional-scale (~300 x 200 km2) atmospheric inversion studies for non-CO2 GHG emission estimates in Switzerland, making use of observations on the Swiss Plateau (Beromünster tall tower) as well as the neighbouring mountain-top sites Jungfraujoch and Schauinsland.

We report spatially and temporally resolved Swiss emissions for CH4 (2013-2019), N2O (2017-2019) and total Swiss emissions for hydrofluorocarbons (HFCs) and SF6 (2009-2019) based on a Bayesian inversion system and a tracer ratio method, respectively. Both approaches make use of transport simulations applying the high-resolution (7 x 7 km2) Lagrangian particle dispersion model (FLEXPART-COSMO). We compare these 'top-down' estimates to the 'bottom-up' results reported by Switzerland to the UNFCCC. Although we find good agreement between the two estimates for some species (CH4, N2O), emissions of other compounds (e.g., considerably lower 'top-down' estimates for HFC-134a) show larger discrepancies. Potential reasons for the disagreements are discussed. Currently, our 'top-down' information is only used for comparative purposes and does not feed back into the 'bottom-up' inventory.
Retrieval quality and column densities of iodine monoxide from multiple satellite sensors – from SCIAMACHY to TROPOMI
Authors: Schoenhardt Anja , Richter Andreas , Blechschmidt Anne-Marlene , Bracher Astrid , Burrows John P.
Published: March 2020

Iodine compounds are mainly emitted from the oceans through organic and inorganic pathways followed by photolysis and reaction with ozone to create iodine monoxide (IO) molecules. Emission sources of iodine species include the sea surface, phytoplankton and macroalgae as well as volcanic eruptions. IO is an indicator of active iodine chemistry, which may be relevant for tropospheric composition due to its impact on ozone levels, the NO/NO2 ratio and potential particle formation. Rapid changes in Polar sea ice coverage and conditions may have an impact on iodine levels in Polar Regions with respective consequences for tropospheric composition in the Arctic and Antarctic.

Differential Optical Absorption Spectroscopy is used to retrieve IO column densities from various satellite sensors, including SCIAMACHY (2002 to 2012), GOME-2 (since 2006) and TROPOMI (since 2017). Case studies are presented with a focus on the intercomparison of the retrieval quality and IO column densities from the applied instruments. Previous satellite studies have shown slightly enhanced IO column densities mainly above the Antarctic Region and within one occasion of a strong volcanic plume, while IO column densities in the Arctic remain mostly below the detection limit of the applied instruments.

Reported column densities of tropospheric IO, as previously measured from ground and from space, are fairly small and close to the detection limits of current and former satellite sensors. Optical depth values of IO absorption are on the order of a few times 10-4. Individual satellite spectra allow trace gas retrievals with residual RMS values which lie around and often above the expected IO absorption optical depth. This is a challenge for the identification of optimal retrieval settings, especially the choice of an adequate wavelength window. Several aspects for quality control are discussed. In addition to the immediate retrieval RMS, the IO standard deviation in areas with expected low IO absorption, consistency checks with other retrieval parameters as well as plausibility of IO column density results are considered.
Comparing methods for gap filling in historical snow depth time series
Authors: Aschauer Johannes , Bavay Mathias , Begert Michael , Marty Christoph
Published: March 2020

Switzerland has a unique dataset of long-term manual daily snow depth time series ranging back more than 100 years for some stations. This makes the dataset predestined to be analyzed in a climatological sense. However, there are sometimes shorter (weeks, months) or longer (years) gaps in these manual snow depth series, which hinder a sound climatological analysis and reasonable conclusions. Therefore, we examine different methods for filling data gaps in daily snow depth series. We focus on longer gaps and use different methods of spatial interpolation, temperature index models and machine learning approaches to fill the data gaps. We assess the performance of the different methods by creating synthetic data gaps and set the applicability of the methods in relation to the density of the available neighboring stations, elevation and climatic setting of the target station.
A comparative study of lipid extraction methods for the quantification of steroidal biomarkers within soil and cattle slurry
Authors: Manley Amber , Collins Adrian , Joynes Adrian , Mellander Per-Erik , Jordan Phil
Published: March 2020

Clean water is a precious resource and policies/programmes are implemented worldwide to protect and/or improve water quality. Faecal pollution can be a key contributor to water quality decline causing eutrophication through nutrient enrichment and also pathogenic contamination. The robust sourcing of faecal pollutants is important to be able to target the appropriate sector and to engage managers.  Biomarker technology has the potential for source confirmation, by using, for example, the biomarker suite of steroids. Steroids have been used in the differentiation of human and animal faeces; however, there is no unequivocal extraction technique regarding either suite’s analysis. Some of the methods used include: i) Soxhlet extraction, ii) Bligh and Dyer (BD) extraction, and iii) accelerated solvent extraction (ASE). The less costly and time intensive technique of ASE is particularly attractive, but a current research gap concerns further comparisons regarding ASE lipid extraction of soils/slurries compared with the more traditionally used methods of Soxhlet and BD extraction. Accordingly, a randomised complete block experiment was implemented to assess for differences between the three extraction methods, differences between the different sample types, and the interactions between these two factors. Following GC-MS, it was found that there was no significant difference between the steroid extraction method used, regardless of the type of sample used, for the quantity of each steroid extracted. It was concluded that ASE could be used confidently instead of the more established steroid extraction methods, thereby delivering time and cost savings.
A conceptual approach on optimising lead time for the forecasting of landslides using remote sensing systems
Authors: Keuschnig Markus , Hermle Doris , Krautblatter Michael
Published: March 2020

New remote sensing systems offer an increased spatiotemporal resolution and accuracy. These systems  increase the chance of snow- and cloud-free multispectral images to detect and monitor landslides for early warning issues. Various studies showed the applicability of multispectral remote sensing systems for landslide detection and monitoring. However, a systemic evaluation of the remote sensing systems especially in respect to early warning is still missing. In this study we present a new conceptional approach to evaluate the capability of different systems for early warning issues based on a well suited case study located in the Hohe Tauern Range, Austria.     

The Sattelkar is a highly dynamic west-facing deglaciated high-alpine cirque in the Großvenedigergruppe, Austria. The abundant rock debris exhibits high movement rates and showed massively enhanced landslide activity after ongoing heavy precipitation in 08/2014, resulting in a 170.000 m³ debris flow event. We estimated time demands for three successive steps consisting of (i) image collection, (ii) processing with motion delineation and (iii) the final evaluation. Digital image correlation, an established tool in landslide remote-sensing research, was used to derive displacement patterns and assess the capabilities of the multispectral images in terms of spatiotemporal resolution and data quality. For our study we used Sentinel-2, RapidEye and PlanetScope images and compared their deduced motion patterns and rates to those from accurate UAV data as well as manually digitized boulder tracks (≥10 m in diameter).

Within a reasonable amount of processing time, some satellite data revealed similar clustered motions identifiable in the UAV images. However, our analysis also showed identification limitations due positional inaccuracy, image errors and spatiotemporal resolution of the data. On that account, certain processing steps reduce the forecasting window and as a result the lead time, i. e. the remaining time to take action. We postulate that remote sensing data has the ability to support landslide monitoring, but the pre-selection of usable and sound data is essential as it directly influences the forecasting window. Sound knowledge of its different application possibilities enhances overall steps of image collection, processing and final analysis. The critical selection of which data source is best can lead to faster response times for landslide events. This increases the forecasting window, hence the time to take action until a landslide occurs.
Impact of crustal rheology on oblique rift development and geometry: a numerical study
Authors: Duclaux Guillaume , Huismans Ritske , May Dave
Published: March 2020

Fault network orientations and three-dimensional geometries of oblique rift systems and oblique passive margins vary widely at the surface of the Earth. In fact, rift width and conjugate passive margins asymmetries also evolve along-strike oblique extensional systems. This evolution can be linked to either changes in tectonic forces and plate motion direction, or transitions between contrasting geological provinces such as mobile belts and cratons.

Here, we use high-resolution 3D forward thermo-mechanical modelling with non-linear viscoplastic rheologies to assess the importance of crustal rheology on low to moderate oblique rifts and non-volcanic passive margins deformation patterns and finite geometries. We compare two crustal end-members model series, one with a stiff crust, and the second with a weak crust. We find that the rheology of the crust strongly controls the width and timing of formation of oblique rifts and passive margins. Coupling between the frictional plastic crust and upper mantle in the stiff models promotes narrow rift systems, while decoupling in the weak models promotes wide rifts. In these wide rifts, strain partitioning in the upper crust favours the development of an interconnected wide anastomosed shear zones network with a long lifespan. While stiff crustal rheology promotes Type I narrow margins, weak crustal rheology promotes the development of Type II margins, with a delayed continental crust breakup compared with the lithospheric mantle breakup. With increasing obliquity this transition in rifting style is accompanied by an evolution of the mantle lithosphere necking behaviour from cylindrical at low obliquity to segmented at higher obliquity. We compare these results with natural oblique rift systems and passive margins in order to decipher the relative impact of crustal rheology along different terrains.
Mapping Arctic Sea Ice Surface Roughness with Multi-angle Imaging SpectroRadiometry
Authors: Johnson Thomas , Tsamados Michel , Muller Jan-Peter , Stroeve Julienne
Published: March 2020

Surface roughness is a crucial parameter in climate and oceanographic studies, constraining momentum transfer between the atmosphere and ocean, providing preconditioning for summer melt pond extent, while also closely related to ice age. High resolution roughness estimates from airborne laser measurements are limited in spatial and temporal coverage while pan-Arctic satellite roughness have remained elusive and do not extended over multi-decadal time-scales.  The MISR (Multi-angle Imaging SpectroRadiometer) instrument acquires optical imagery at 275m (red channel) and 1.1 km (all channels) resolutions from nine near-simultaneous camera view zenith angles sampling specular anisotropy, since 1999. Extending on previous work to model sea ice surface roughness from MISR angular reflectance signatures, a training dataset of cloud-free pixels and coincident probability distribution functions of lidar derived elevations from the Airborne Topographic Mapper (ATM) is generated. Surface roughness, defined as the standard deviation of the within-pixel elevations to a best-fit plane, is modelled using Support Vector Regression with a Radial Basis Function kernel, hyperparameters are tuned using GridSearchCV, and performance is assessed using nested cross-validation. We present derived instantaneous and monthly averaged sea ice roughness products at 1.1km and 17.6km resolution over the timespan of IceBridge campaigns (March and April for 2009-2018) on an EASE-2 (Equal-Area Scalable Earth) grid. These show considerable promise in detecting newly formed smooth ice from polynyas, and detailed surface features such as ridges and leads.

 
ITRF use for global applications and estimation of linear velocities of dense networks
Authors: Matonti Francesco , Miller Adam , Krasovec Nejc
Published: March 2020

GNSS networks are required to continue meeting the ever-increasing demand for global positioning applications operating in a global reference frame. Meanwhile, the requirements of applications based in a local (regional) official reference frame must still be met. Using Bernese GNSS software (Dach, 2015), we can process GNSS networks in the ITRF2014 reference frame and, using Leica GNSS Spider, deliver GNSS corrections in ITRF2014, whilst continuing to serve those with local demands.  To maintain high precision of the GNSS network we perform a daily solution, which is computed based on precise orbits and following the guidelines of the EPN Analysis Centres. To ensure the daily solution runs with correct data, we maintain a database of all reference station equipment changes. Using the daily solution, we are estimating the linear velocity of reference stations within GNSS networks, and are also considering jumps due to equipment changes. The estimated velocities give the opportunity to monitor the long-term stability of the network as well as the quality of reference station coordinates. The daily solution and monitoring of GNSS networks are executed by the Leica Geosystems solution named Leica CrossCheck, which is based on Bernese GNSS software. Leica CrossCheck is capable to monitor GNSS networks of all scales. This includes the computation and monitoring of approximately 5000 GNSS reference stations worldwide, including those part of the HxGN SmartNet GNSS network.  

KEYWORDS: GNSS reference station network, Bernese GNSS 5.2, Leica CrossCheck, Leica GNSS Spider, HxGN SmartNet 
 

References: 
Dach, R., S. Lutz, P. Walser, P. Fridez (Eds); 2015: Bernese GNSS Software Version 5.2. User manual, Astronomical Institute, Universtiy of Bern, Bern Open Publishing. DOI: 10.7892/boris.72297; ISBN: 978-3-906813-05-9.   
 
Effect of soil organic carbon loss on the stability and structure of microaggregates: First insights from an organic carbon depletion field trial in a loess soil
Authors: Roosch Svenja , Felde Vincent , Uteau Daniel , Peth Stephan
Published: March 2020

Soil microaggregates are considered to play an important role in soil functioning and soil organic carbon (SOC) is of great importance for the formation and stabilization of these aggregates. The loss of SOC can occur, for example, after a change in land use and may lead to a decreased aggregate stability, which makes soils vulnerable to various threats, such as erosion or compaction. It is therefore important to understand the effect of SOC loss on aggregate stability in order to better understand and preserve the functioning of healthy soils.

We sampled two adjacent plots from a loess soil in Selhausen (North Rhine-Westphalia, Germany) in November of 2019 and measured aggregate stability and architecture of soil microaggregates. One plot was kept free from vegetation by the application of herbicides and by tillage (to a depth of 5 cm) from 2005 on, while the other plot was used for agriculture (conventional tillage). Over the course of 11 years, the SOC concentration in the bulk soil was reduced from 12.2 to 10.1 g SOC kg-1 soil. We took 10 undisturbed soil cores from two depths of each plot (Ap and Bt horizons).

The stability of aggregates against hydraulic and mechanical stresses was tested using the widespread wet sieving approach and a newly developed dry crushing approach. Isolated microaggregates gained from the latter procedure were tested against tensile stress by adapting a crushing test in a load frame to the microaggregate scale. To shed light on the effect of a decreased SOC content on microaggregate structure, we scanned several microaggregates with a high-resolution computed tomography scanner (Zeiss Xradia 520 versa) at sub-micron resolutions and analyzed the features of their pore systems.

This will give us valuable insights into the interplay of mechanical and physicochemical stability, as well as the structural properties of microaggregates with regard to SOC depletion. The consequences for various soil functions provided by microaggregates, like the habitat function for microorganisms or their capacity to store and transport gas, water and nutrients, are discussed.
Exploring NOx Emission from the Ground and the Air in London, UK
Authors: Drysdale Will , Vaughan Adam , Squires Freya , Nelson Beth , Pitt Joseph , Metzger Stefan , Durden David , Pingintha-Durden Natchaya , Grimmond Sue , Purvis Ruth , Lee James
Published: March 2020

NOx (the sum of NO + NO2) is emitted during most combustion processes. NO2 is a well-known air pollutant detrimental to human health, critical in the formation of tropospheric ozone and its concentration is regulated in many cities. London is a megacity which often finds itself in breach of these air quality regulations. Emission inventories are used in air quality forecast models to predict current and future air pollution levels and to guide abatement strategy. The National Atmospheric Emissions Inventory (NAEI) has been shown to underestimate NOx emission in London (Lee et al. 2012, Vaughan et al. 2016). Top down measurements allow assessment of emissions help understand the difference between measurement and model.

During March – June 2017 NOx emissions were measured using the eddy covariance method sampling from a height of 180 m at the British Telecom (BT) tower in Central London. In July of 2017 measurements of NOx by the UK’s Facility for Airborne Atmospheric Measurement (FAAM) were made as a part of the Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales (EMeRGe). A mass balance approach (after O’Shea et al. 2014 and Pitt et al. 2019) has been applied to these measurements producing a measurement of bulk emission of NOx from Greater London and surrounding areas.

Through comparison of these measurements with the NAEI we present an exploration of NOx emission from London and assess how this is captured in the emissions inventory.

 

Lee et al., Environmental Science & Technology, 2015, 49, 1025-1034

Vaughan et al., Faraday Discussions, 2016, 189, 455-472

O’Shea et al., J. Geophys. Res. Atmos., 2014, 119, 4940–4952

Pitt et al., Atmos. Chem. Phys., 2019, 19, 8931-8945
How vegetation drives initial soil development together with soil organic matter accrual in maritime Antarctica
Authors: Prater Isabel , Hrbacek Filip , Meier Lars Arne , Braun Christina , Nyvlt Daniel , Mueller Carsten W.
Published: March 2020

Antarctica with its unique conditions for soil development offers the opportunity to disclose basic soil biogeochemical processes in an environment with a low degree of ecosystem interactions. The region’s climate is divided by the mountain ridge of the Antarctic Peninsula: on the South Shetland Islands (King George Island (KGI)) in the west a maritime cold climate prevails, while James Ross Island (JRI) in the east faces the continental cold climate of a polar desert with less precipitation and distinctly more pronounced temperature variations throughout the year. In addition, the autochthonous vegetation differs; while it solely consists of cryptogams on JRI, on KGI two vascular plants (Dechampsia antarctica, Colobanthus quitensis) are endemic. This scarce vegetation patterns together with land surfaces ice-free for several millenia allows studying the complex interaction between soil organic matter (SOM) sequestration and soil structure development with respect to the varying presence and growth of vegetation.  

The main aim of our study is to decode the mechanisms determining the fate of SOM in maritime Antarctica and to understand how the scarce vegetation drives the chemical composition and distribution of SOM within specific physical SOM fractions. Therefore, we sampled transects ranging from vegetated patches to plant-free soil surfaces. The distance to these vegetation patches was reflected in clear variations in the distribution of carbon and nitrogen and in a decrease in labile SOM constituents as revealed by 13C-CPMAS NMR spectroscopy, while clay-sized mineral-associated SOM dominated the carbon storage throughout all sites. The ongoing climate change is assumed to significantly alter the vegetation distribution and thus drive the storage and composition of SOM. In the future, this will also strongly affect soil microbial activity and land-ocean transitions in Antarctica.
A Direct Application of Data Assimilation to Multi-Scale Regionalized Parameters
Authors: Schüler Lennart , Attinger Sabine
Published: March 2020

Streamflow observations are integrated signals of a catchment. This data is only weakly correlated to local observations (e.g. soil moisture and groundwater heads) or local parameters (e.g. hydraulic conductivity) of the catchment. On the one hand, this makes it next to impossible to estimate model parameters from streamflow observations alone. On the other hand, local observations only make parameter estimation possible in their immediate proximity. With data scarcity in mind, this multi-variate data assimilation alone has limited potential to solving the problem of estimating model parameters.
Therefore, we propose to not apply data assimilation to the model parameters directly, but to the global parameters of the multi-scale regionalization (MPR, Samaniego et al. 2010) approach. This approach relates a very limited number of global parameters through transfer functions to the model parameters. By doing so, the number of parameters to be estimated can be drastically reduced, saving computing time and with robust transfer functions, the local parameters can be estimated not only in the proximity of observations, but also throughout the catchment.
Using the DA-MPR approach, we investigate different experiment setups for estimating model parameters, e.g. a stationary cosmic ray sensor vs. a mobile one or how many local observations are actually needed in order to uniquely identify the model parameters.

Samaniego L., R. Kumar, S. Attinger (2010): Multiscale parameter regionalization of a grid-based hydrologic model at the mesoscale. Water Resour. Res., 46
Fluid mechanics of plastic debris clogging the hydraulic structures in Indonesia
Authors: Bertoncelj Vesna , Uijttewaal Wim , Farid Mohammad , Bricker Jeremy
Published: March 2020

The frequent urban floods in Jakarta and Bandung, Indonesia affect the lives and livelihoods of millions of people. Floods cause damage and casualties, while climate change, unchecked development and land subsidence are worsening the problem. One factor contributing to these floods is floating debris clogging the city's drainage structures. A major proportion of floating debris consists of macro plastics which are extremely persistent in the environment. Trash racks that are clogged due to continuous accumulation of plastics in front of them can block the water flow in the river, leading to an increase in upstream water level and causing floods. 

The understanding of transport and accumulation of the macro plastics in the river systems is limited as the field surveys are difficult to perform and the variety of properties of plastic debris is enormous. However, understanding of the origin, fate and pathway of plastic waste is required in order to come up with an optimal solution for plastic collection and prevention of harmful accumulation in front of the hydraulic structures. With this urge in mind field observations will be conducted on the selected river sections in Bandung and Jakarta during the monsoon season in 2020. Field observations will include the measurements of bathymetry, velocity profiles, concentrations and the characterization of floating debris, as well as identifying the accumulation hot spots of floating debris. Furthermore, experimental and numerical modelling will be performed based on the data collected during the field campaign in order to couple different debris classes to a range of riverine situations and understand the differences in their driving mechanisms.

Using a combination of field measurements, experimental modelling and empirical relations we aim to investigate the driving mechanisms of riverine plastic transport and changes in hydraulic properties due to local disturbances of the current. We will therefore link the type of hydraulic structures and the extend of obstructions due to accumulation of plastic debris to the changes in the upstream water level. This will lead to a better understanding of plastic transport in the river systems in Bandung and Jakarta, to formulate design criteria for structures in trash-laden streams and devise ways to pass trash during floods.
Siberian Arctic inland waters emit mostly contemporary carbon
Authors: Dean Joshua , Meisel Ove , Martyn Roscoe Melanie , Belelli Marchesini Luca , Garnett Mark , Lenderink Henk , van Logtestijn Richard , Borges Alberto , Bouillon Steven , Lambert Thibault , Röckmann Thomas , Maximov Trofim , Petrov Roman , Karsanaev Sergei , Aerts Rien , van Huissteden Jacobus , Vonk Jorien , Dolman Han
Published: March 2020

Inland waters (rivers, lakes and ponds) are important conduits for the emission of terrestrial carbon in Arctic permafrost landscapes. These emissions are driven by turnover of contemporary terrestrial carbon and additional “pre-aged” (Holocene and late-Pleistocene) carbon released from thawing permafrost soils, but the magnitude of these source contributions to total inland water carbon fluxes remains unknown. Here we present unique simultaneous radiocarbon age measurements of inland water CO2, CH4 and dissolved and particulate organic carbon in northeast Siberia during summer. We show that >80% of total inland water carbon emissions were contemporary in age, but that pre-aged carbon contributed >50% at sites strongly affected by permafrost thaw. CO2 and CH4 were younger than dissolved and particulate organic carbon, suggesting emissions were primarily fuelled by contemporary carbon decomposition. The study region was a net carbon sink (-876.9 ± 136.4 Mg C for 25 July to 17 August), but inland waters were a source of contemporary (16.8 Mg C) and pre-aged (3.7 Mg C) emissions that respectively offset 1.9 ± 1.2% and 0.4 ± 0.3% of CO2 uptake by tundra (‑897 ± 115 Mg C). Our findings reveal that inland water carbon emissions from permafrost landscapes may be more sensitive to changes in contemporary carbon turnover than the release of pre-aged carbon from thawing permafrost.
Evaluation of the effects of Caulerpa cylindracea on Posidonia oceanica through the analysis of primary production and morphometric characteristics
Authors: Boschi Marco , Caporale Giulia , Pasculli Lorenzo , Piazzolla Daniele , Mancini Emanuele
Published: March 2020

Today, biological invasions represent a threat to endemic animal and plant communities and a major cause of biodiversity loss worldwide. In the Mediterranean Sea, there are about 100 species of macrophytes, introduced intentionally or accidentally, most of which are highly invasive. Among these, the macroalga Caulerpa cylindracea Sonder, 1845, entered in the Mediterranean basin since 1990 through the Suez Canal and now it is widespread along the Italian coasts. This species is able to colonize a high number of coastal substrates and it can affect the density of some seagrasses, such as Cymodocea nodosa (Ucria) Ascherson, 1870 and Posidonia oceanica (L.) Delile, 1813. Its colonization ability is enhanced in environments with a high concentration of nutrients and its growth can modify the redox potential of the substrate making it unsuitable for the establishment of other seagrasses and algae. This work aimed to analyse and describe the potential interaction between the C. racemosa and P. oceanica in the coastal area of Civitavecchia. The potential effects of this interaction were studied inside of two different P. oceanica patches, located at a depth of 3-5 m and characterized by the presence/absence of the invasive alga, through the morphostructural analysis of the two species. In particular, the seagrass growth and primary production were analysed using some direct and indirect techniques (phenology and lepidochronology), while for the alga were analysed the phenological characteristics and the percentage of coverage of the substrate. The sampling campaigns were carried out in two different months of the same year, June and October 2019, in order to observe both the growth phase and the maximum bloom phase of the C. racemosa.
Cloud vertical structure studied with synergetic measurements of Radiosonde, ceilometer and Ka-band radar in Munich
Authors: Li Qiang , Ewald Florian , Groß Silke , Hagen Martin , Tetoni Eleni , Mayer Bernhard
Published: March 2020

Clouds play an important role in the radiation budget of the Earth’s atmosphere. The radiative heating and/or cooling by cloud vertical sturcture including cloud top and base, number and thickness of cloud layers, and the vertical distribution of multi-layer clouds couple strongly with the atmospheric thermodynamics, general circulation, and the hydrological cycle. Unfortunately, however, inadequate understanding of cloud properties and their vertical distributions still leads to high uncertainties in global climate models. In this study, we present the vertical distributions of multi-layer clouds derived from synergetic measurements of radiosonde and collocated ceilometer and the miraMACS Ka-band cloud radar on the roof of the Meteorological Institute Munich. Balloon-borne radiosondes penetrate the cloud layers and thus provide in-situ measurements. The profiles of temperature, relative humidity and pressure with radiosonde are used to derive cloud layers by identifying saturated levels in the atmosphere. The ceilometer is very efficient in detecting clouds and can provide a reliable estimate of the height of cloud base. The miraMACS cloud radar operating continuously in a vertical pointing mode provide radar reflectivities by hydrometeors within the radar beam. The radar observations allow for the determination of cloud layers with high temporal and vertical resolutions. Doing these exercises to the measurements of an entire year in 2018, we are able to evaluate the cloud layer retrieval methods with different instruments and to derive the statistical properties of cloud vertical structure in Munich.
Spatial-temporal variability of M2 internal tides modulated by the Kuroshio currents and mesoscale eddies northeast of Taiwan
Authors: Chang Hang , Liu Yahao
Published: March 2020

The spatial-temporal variability and energetics of M2 internal tides during their generation and propagation through the Kuroshio flows and robust eddies northeast of Taiwan are investigated using a high-resolution numerical model. The corrugated continental slopes, particularly the I-Lan Ridge and Mien-Hua Canyon, are identified as the energetic sources of M2 internal tides. The M2 internal tide generation is influenced by the horizontally varying and zonally tilting stratification associated with the Kuroshio currents and mesoscale eddies. In this situation, the magnitude of conversion rate and energy beam exhibit highly temporal variability. An energetic along-slope tidal beam from the I-Lan Ridge radiates southward against the northward Kuroshio flows, causing strong vertical displacement. Complex background currents lead to the time-varying inhomogeneous diapycnal mixing induced by internal tide dissipation.
SPRING-NEAP CHANGE IN TIDAL HYDRODYNAMICS IN THE LINGDINGYANG BAY OF THE PEARL RIVER DELTA, China
Authors: Zhang Ping , Cai Huayang
Published: March 2020

Understanding the evolution of estuarine hydrodynamics is essential for sustainable water resources management, since they directly link to estuarine environment by regulating the materials transportation (e.g. nutrients, sediments, organisms and pollutants). In this study, an enhanced harmonic analysis model for nonstationary tide (S_TIDE model) was used to extract the amplitudes and phases of two predominant tidal constituents (M2 and K1) in a daily scale in two tidal gauging stations (i.e., Chiwan, Sishengwei) in the Lingdingyang Bay of the Pearl River Delta from 1965 to 2016, with the purpose of exploring the spring-neap change in tidal hydrodynamics (e.g., tidal wave celerity and tidal damping/amplification rate). To understand the stepwise evolution of tidal hydrodynamics, we have divided the whole study period into three distinct periods: the pre-human (e.g., from 1965-1997), transitional (e.g., from 1998-2007) and post-human periods (e.g., from 2008-2016), based on the dynamics of wave celerity. It was shown that the long-term spring-neap change in tidal hydrodynamics was mainly driven by the highly-modified geometry (including deepening and narrowing) in the Lingdingyang Bay. To quantify the effects of estuarine morphological alterations in terms of deepening and narrowing on tidal hydrodynamics, an analytical hydrodynamics model was adopted to assess the spring-neap variations at different periods. The proposed method for evaluating the tidal dynamics owing to morphological changes is particularly useful for providing a theoretical guideline for protecting the estuarian environment in the Lingdingyang Bay and other estuaries that are subject to strong human interventions.
Experimental analysis at the meter scale of denitrifying woodchips bioreactor performance under variable loading conditions
Authors: Trevisan Luca
Published: March 2020

The excessive use of fertilizers in conjunction with agricultural tile drainage can lead to high levels of nitrate (NO3) in subsurface waters, which can pollute rivers, eventually causing eutrophication of larger water bodies. Among several water treatment alternatives, biological denitrification in edge-of-field woodchip bioreactors represents a popular option, given its relatively easy implementation, minimal maintenance and low cost. Since microbial denitrification is commonly catalyzed by facultative heterotrophic bacteria in anoxic environments, oxygen concentration is a key parameter to keep in consideration. To monitor dissolved oxygen concentration inside the test bioreactor in a non-invasive manner, oxygen optode sensors are used. Bioreactor performance also depends on several other factors, including hydraulic residence time, influent nitrate concentrations, and woodchips flow and transport parameters. One particular aspect that has been overlooked in the literature is how gas generation due to bacterial respiration can hinder the water flow through the bioreactor, hence reducing its effective porosity and denitrification performance. A continuous monitoring of inlet and outlet flow rates is applied to detect flow fluctuations during the experiments. Given the uncertainty and challenges associated with field observations, meter-scale experiments conducted under controlled boundary conditions and known porous media distribution represent a convenient method for studying the influence of water quality and hydraulic parameters on nitrate removal. The aim of this work is to characterize the bioreactor performance using woodchips with different particle sizes and to investigate the effect of retention time and inlet NO3 concentration on NO3 removal under variable flow conditions. For this purpose, a series of experiments are conducted in a 147.7 × 10 × 38.5 cm3 flume under well-controlled laboratory conditions.
Development of a processing chain of multispectral Sentinel–2 data to extract meandering river courses for geomorphometric analysis in Central Amazonia Region
Authors: Kósa Noémi , Székely Balázs
Published: March 2020

Freely-meandering rivers are sensitive indicators of neotectonic activity that is otherwise difficult to detect in low-relief areas. In this study sinuosity analysis has been carried out on 20 main rivers and tributaries of Central Amazonia Region as an aid for localization of river channel patterns influenced by on-going tectonic activity.

The main problem of such studies, however, the availability of accurate river channel data. For the Central Amazonia Region highly accurate dataset that has a good geographical coverage is hardly available: the datasets we found did not fulfill the accuracy criteria for our project.

Consequently, the first objective of this project was to develop a data processing method of high resolution satellite images which provides a quick and accurate way to digitize river sections of a large parts of the intracratonic sedimentary basin. Furthermore, this work aims to detect channel sinuosity changes that could indicate recent vertical crustal movements. To achieve this, the water courses were automatically digitized using Sentinel–2 data and classic sinuosity values were calculated using several window sizes. The distribution of sinuosity variations was analysed by classification and various representations of the calculated values like mapping, crossplots and sinuosity-spectrum.

As the visualization methods complement each other the variations in sinuosity values can be highlighted and verified in several aspects. The results compared to former neotectonic studies some significant sinuosity changes can be correlated to known faults. The mentioned sinuosity variations coincides with the location of NW–SE normal and thrust faults active since Pleistocene times and NE–SW Miocene normal faults supporting the idea that these structures may have been reactivated.

In conclusion, multi-window sinuosity index calculation applied to satellite data based digitized water courses is a useful tool for recognizing recent tectonic activity in large low-relief areas, such as Central Amazonia.