bluuebunny/crossref_metadata_2025 huggingface dataset:
Representation of the extratropical circulation in the MiKlip decadal prediction system - impacts of resolution and initialization
Authors: Grieger Jens , Schuster Mareike , Kadow Christopher , Richling Andy , Ulbrich Uwe
Published: March 2020

This study analyzes the representation of the extratropical circulation over the North Atlantic (NA) region using the German decadal prediction system (MiKlip) of two different spatial resolutions. Four quantities are assessed, i.e. the storm track, blocking frequencies, cyclone frequencies, and windstorm frequencies. We investigate the effect of model initialization for the representation of the circulation in a lower resolution (LR, atm: T63L47, ocean: 1.5° L40) and higher resolution version (HR, atm: T127L95, ocean: 0.4° L40) of the decadal prediction system.

While LR shows common deficits in the climatological representation in both the initialized prediction system and the uninitialized historical projection, e.g. an overly zonal extratropical storm track and a deficit in blocking frequencies over the North Atlantic and Europe, the higher resolution version counteracts these biases. The initialized LR prediction system largely overestimates NA cyclone frequency, which is not the case for the uninitialized LR counterpart. This positive bias is mainly due to weak and short lived systems and is an effect of the initialization in the LR prediction system. Similar biases cannot be identified in the windstorm frequency which implies that the short lived cyclones are low of impact with respect to wind speed.

The initialization effect leading to an overestimation of weak and short lived cyclones cannot be found in the HR version. The overall better representation of the extratropical circulation in the HR version leads to an increased decadal prediction skill, which is measured in terms of anomaly correlation, with the increase in resolution for all four quantities. 
Predicting past tipping points: The Dansgaard-Oeschger events of the last glacial period
Authors: Lohmann Johannes , Ditlevsen Peter
Published: March 2020

The Dansgaard-Oeschger (DO) events of the last glacial period provide a unique example of large-scale climate change on centennial time scales. Despite significant progress in modeling DO-like transitions with realistic climate models, it is still unknown what ultimately drives these changes. It is an outstanding problem whether they are driven by a self-sustained oscillation of the earth system, or by stochastic perturbations in terms of freshwater discharges into the North Atlantic or extremes in atmospheric dynamics.

This work addresses the question of whether DO events fall into the realm of tipping points in the mathematical sense, either driven by an underlying bifurcation, noise or a rate-dependent instability, or whether they are a true and possibly chaotic oscillation. To do this, different ice core proxy data and empirical predictability can be used as a discriminator.

The complex temporal pattern of DO events has been investigated previously to suggest that the transitions in between cold (stadial) and warm (interstadial) phases are purely noise-induced and thus unpredictable. In contrast, evidence is presented that trends in proxy records of Greenland ice cores within the stadial and interstadial phases pre-determine the impending abrupt transitions and allow their prediction. As a result, they cannot be purely noise-induced.

The observed proxy trends manifest consistent reorganizations of the climate system at specific time scales, and can give some hints on the physical processes being involved. Nevertheless, the complex temporal pattern, i.e., what sets the highly variable and largely uncorrelated time scales of individual DO excursions remains to be explained.
Changes in microbial community structure by methane fluxes at arctic cold seeps
Authors: Carrier Vincent , Kalenitchenko Dimitri , Gründger Friederike , Svenning Mette M.
Published: March 2020

Cold seeps are areas of the seafloor where hydrocarbon-rich fluids, primarily composed of methane (CH4), migrate from below reservoirs through the sediments to reach the seafloor surface. This CH4 is an important energy source for biological communities at cold seeps and it is taken up by specialized archaeal and bacterial methane oxidizers in anaerobic and aerobic environments. Reaction products, such as sulphide, are thereafter cycled into the microbial food web, by other microbial functional groups, underlining the importance of microorganisms in supporting biological production at cold seeps. However, large gaps of knowledge on total microbial biodiversity at these methane seeps and their spatial distribution remain, especially at high latitudes. South of Svalbard, five geological mounds shaped by the formation of CH4 gas hydrates (gas hydrate pingos GHPs), have been described recently. While one GHP was inactive, four of them showed CH4 seeping activity with flares primarily concentrated at the summits. This suggest that the environmental conditions gradually change from the rim of the GHP toward the summit. We hypothesized that the microbial biodiversity varies along that gradient, where the summits would harbor the highest abundances of methane oxidizers. In order to test this hypothesis, we investigated the microbial community structure at two active GHPs, an inactive GHP and a reference site. Porewater chemistry and sequencing-based community analyses of Archaea, Bacteria and Eukaryotes were investigated at several depths of the sediment along a distance gradient from the summit to the rim of each GHP. We show that local environmental conditions, such as the presence of CH4, do affect the microbial community structure and composition. The anaerobic methane oxidizing ANME-1 dominates the archaeal libraries and are detected various types of sulphate-reducing bacteria, although none demonstrated a clear co-occurrence with the predominance of ANME-1. Additional common taxa observed in these CH4-rich sediments that likely benefited from the metabolites of CH4 oxidation were sulphide oxidizing Epsilonproteobactaerota, as well as organic matter degraders, such as Bathyarchaeota, Woesearchaeota or thermoplasmatales MBG-D, and heterotrophic ciliates and Cercozoa. Beyond our expectations, the distribution of the different community types were not separated in concentric zones around the GHPs and similar methane oxidizing communities could be retrieved at different location over a GHP.
The QBO as driver of lower stratospheric ozone variability as quantified in the CCM SOCOLv3
Authors: Stenke Andrea , Ball William T. , Domeisen Daniela
Published: March 2020

The quasi-biennial oscillation (QBO) is the dominating mode of variability in the tropical stratosphere. The oscillation of zonal winds between downward propagating easterlies and westerlies induces a secondary meridional circulation. This, in turn, modulates tropical upwelling, which also affects transport between tropical and extratropical regions and can induce large swings in tracer anomalies. Chemistry-climate models (CCMs) need a sufficiently high vertical resolution to spontaneously generate a QBO, while models with lower resolution often nudge zonal winds to observed equatorial wind profiles. Here, we evaluate the QBO impact on lower stratospheric ozone variability in the CCM SOCOLv3 using various model set-ups. Composites of stratospheric ozone observations demonstrate large interannual variations in mid-latitudes driven by QBO phase-dependent variability. From a large ensemble of free-running model simulations with nudged QBO, we find simulated ozone anomalies in the tropical stratosphere consistently reproduce those observed. However, extratropical anomalies show significant deviations from observations. In the southern hemisphere, about 65% of all cases from our ensemble agree in the sign of the observed anomalies, but the amplitude is underestimated. In contrast to the free-running model, simulations in specified dynamics mode show an overall good agreement with observations, including extratropical regions. This suggests a strong impact of the state of the large-scale stratospheric circulation on the QBO effect upon mid-latitudes. This is supported by model simulations where specified dynamics are applied to the troposphere only. Here we present a detailed analysis of the interaction between simulated stratospheric circulation and the QBO-induced secondary circulation. The realistic representation of such QBO-driven events in terms of frequency and strength in CCMs may be crucial for reproducing the observed large interannual variability in lower stratospheric tracer concentrations and, hence, for correctly retrieving lower stratospheric ozone trends.
Three Dimensional Radiative Transfer in ICON-LEM
Authors: Jakub Fabian , Mayer Bernhard
Published: March 2020

Recent studies have shown that the effects of three dimensional
radiative transfer may impact cloud formation and precipitation.
While one-dimensional solvers are favoured due to their computational
simplicity, they do however neglect any horizontal energy transport.
In particular, the 1D approximation neglects 3D effects such as cloud side illumination
and the displacement of the cloud's shadow at the surface which are
relevant whenever the sun is not in the zenith.
This has a detrimental effect on the results of high resolution simulations.
3D radiative transfer has the potential to considerably change the
boundary layer dynamics, the evolution of clouds, their lifetime and
precipitation onset.
To this date, studies that investigate the influence of 3D effects on
realistic NWP settings are rare,
primarily because there haven't been 3D radiative transfer solvers
around that were fast enough to be run interactively in a forecast
simulation.

For that purpose we adapted the TenStream solver (parallel 3D radiative
transfer solver for LES) to unstructured meshes and coupled it to ICON-LEM.
We will present the new solver in the context of ICON-LEM simulations,
the methodologies used and its characteristics.
Fate of microplastic particles in agricultural soil systems: Transport and accumulation processes in contrasting environments
Authors: Hurley Rachel , Crossman Jill , Schell Theresa , Rico Andreu , Futter Martyn , Vighi Marco , Nizzetto Luca
Published: March 2020

There is a paucity of data regarding the sources and fate of microplastics in agricultural settings. This is despite indication that these environments may receive significant contributions of microplastics from a range of inputs. Several studies have documented the enrichment of sewage sludge by microplastic particles as a result of wastewater treatment processes. In many countries, sludge is applied to agricultural soils as a soil conditioner. Based on the extent of application and microplastic loads in sludge material, it is expected that sludge application to land represents a considerable release pathway for microplastic particles to the environment. The fate of these particles across spatial and temporal scales is, however, unknown. This includes the potential for the propagation of contamination to connected aquatic systems and beyond.

The Water JPI-funded IMPASSE project addresses significant gaps in our understanding of microplastic contamination in agricultural systems. As part of this project, two case study locations in contrasting environments were selected for study: the semi-arid Henares catchment in central Spain and the humid continental Beaver and Orillia catchments in the Lake Simcoe watershed in Ontario, Canada. Agricultural fields subjected to different sludge application treatments (timing and origin of material) were assessed for microplastic contamination through repeat soil core sampling. This was coupled with runoff experiments using modified Pinson collectors to track the mobilisation of sewage sludge-derived particles from soils. Laboratory analysis was performed according to Hurley et al. (2018). Thorough characterisation of all microplastics particles down to a lower size limit of 50 µm was achieved, including particle size, morphology, polymer type, and estimated mass. Microplastic loads in soils increased following sludge application. The dynamics of contamination from soil core analyses show complex spatio-temporal patterns of accumulation and vertical and lateral transport of particles. Through the use of experimental runoff plots, the mobilisation of microplastic particles from agricultural soils has been documented for the first time. Preferential accumulation and transport of different particle morphologies – e.g. fibres vs fragments – was also observed. These findings form the basis of innovative modelling work in the case study catchments to predict dynamics of agricultural microplastic contamination and subsequent transfer to aquatic environments.
Modeling the Atmospheric Contribution to the Interior Characterization of sub-Neptunes and its Effect on Habitability
Authors: MacKenzie Jasmine , Baumeister Philipp , Godolt Mareike , Tosi Nicola , Kubyshkina Daria , Fossati Luca
Published: March 2020

As the number of confirmed exoplanets has increased, so too has the diversity in their physical parameters, namely their mass and radius. A common practice is to place these planets on a Mass-Radius diagram with various calculated density curves corresponding to some bulk composition. However, these lines don’t necessarily correspond to the structure of the planet found using interior models, particularly for low mass planets with masses less than 20 M⊕ and 4 R⊕, which we call “sub-Neptunes.” Planets in this range can have highly degenerate solutions with no solar system analog, from so-called “ocean worlds” to small dense cores with extended primary composition atmospheres. We have created a model that is able to cover the range of solutions possible for sub-Neptunes, with various levels of complexity for both the interior and atmosphere. This includes both an isothermal and semi-grey atmosphere, along with a high-pressure solar composition envelope when atmospheric pressures exceed approximately 1000 bar. We then apply this model to known sub-Neptunes located in the extended habitable zone of their star using a hydrogen-helium dominated atmosphere. An atmospheric escape model is used to investigate the longevity of the atmosphere and its effect on the overall habitability of the planet.
Constraints on late Miocene ice volume variability from a global benthic δ18O compilation (8.0-5.0 Ma)
Authors: Drury Anna Joy , Westerhold Thomas , Hodell David , White Sarah , Ravelo Ana Christina , Wilkens Roy
Published: March 2020

Accurate stable isotope stratigraphies are essential for understanding how past climates are influenced by orbital forcing. Deep-sea benthic foraminiferal δ18O and δ13C stratigraphies can provide precise astronomical age control and record changes in past deep-sea ocean temperatures, global ice volume and the carbon cycle. Our understanding of Plio-Pleistocene climate dynamics has improved through the development of global (LR04; Lisiecki & Raymo, 2005) and regional stacks (Ceara Rise; Wilkens et al., 2017). However, the late Miocene climate system remains poorly understood, in part because the late Miocene benthic foraminiferal δ18O stratigraphy is notoriously low amplitude.

Here, we present the first global late Miocene global benthic foraminiferal δ18O compilation spanning 8.00-5.33 Ma. We formed a “Base Stack” using six continuous benthic stratigraphies from the Atlantic (ODP Sites 982 (N), 926 (E) and 1264 (S)) and Pacific Oceans (IODP Sites U1337 and U1338 (E), ODP Site 1146 (W)). To avoid misidentification of individual excursions between sites, we verified existing splices, generated isotope data where necessary and established independent astrochronologies. To accompany the “Base Stack”, we compiled a “Comprehensive Stack”, which incorporates single-hole benthic δ18O stratigraphies to optimise global coverage.

The new global late Miocene benthic foraminiferal δ18O stack represents a stratigraphic reference section back to 8.00 Ma. The stack is accurately tied to the Geomagnetic Polarity Time Scale between Chrons C3r and C4n.2n using the magnetostratigraphy from IODP Site U1337. We recognise 68 new δ18O Marine Isotope Stages (MIS) between 7.7 and 6.5 Ma. An exceptional global response is imprinted on the dispersed sites between 7.7-6.9 & 6.4-5.4 Ma, when a strong 40 kyr heartbeat dominates the climate system. The origin of these cycles remains unclear. The influence of deep-sea temperature on the benthic δ18O stack is explored at IODP Site U1337 using Mg/Ca data. The dominant 40-kyr δ18O cycles are asymmetric, suggesting at least a partial ice volume imprint and raising the possibility that these cycles relate to early signs of northern hemisphere glaciation.
A novel spectroscopic approach for detection of chlorine reservoir species: HCl-TILDAS
Authors: Halfacre John , Edwards Pete , Herndon Scott , Roscioli Joseph , Dyroff Christoph , Yacovitch Tara , Marsden Nicholas , Bannan Thomas , Percival Carl , Coe Hugh , Veres Patrick , Brown Steven
Published: March 2020

Atomic chlorine radicals are known to affect atmospheric oxidation and pollutant lifetimes, but are challenging to detect due to their low ambient concentrations.  A lack of field observations limits useful assessments of the impacts of tropospheric chlorine oxidation on important atmospheric processes, such as regional ozone production, reactive nitrogen loss, and global methane removal.  In the last decade, instrumental innovations have enabled detection and speciation of much more stable chlorine atom reservoir species, such as nitryl chloride, through techniques such as cavity ring down spectroscopy and mass spectrometry.  HCl is the most abundant and long-lived tropospheric chlorine reservoir species, yet few observations exist.  Here, we present a specific method for detection of HCl via Tunable Laser Infrared Direct Absorption Spectrometer (TILDAS), which has been further extended for the detection of nitryl chloride.  This analytical method has several advantages over current observational techniques (e.g. chemical ionisation mass spectrometry), and will provide a much needed constraint on the tropospheric chlorine atom budget.
Methane emission detection and flux quantification from exploratory hydraulic fracturing in the United Kingdom, using unmanned aerial vehicle sampling
Authors: Shah Adil , Ricketts Hugo , Pitt Joseph , Shaw Jacob , Kabbabe Khristopher , Leen Brian , Allen Grant
Published: March 2020

Unmanned aerial vehicle (UAV) sampling was used to derive high-precision methane mole fraction measurements downwind of the United Kingdom’s first onshore exploratory operation to horizontally hydraulically fracture shale rock. Sampling took place using two UAVs on five intermittent sampling days between October 2018 and February 2019. One UAV carried an on-board prototype sensor while the other was connected to a sensor on the ground, using a tethered air inlet. Both instruments used near infrared spectroscopy. Methane emissions were observed on one sampling day (14th January 2019) over a 1.4-hour sampling window, due to cold venting of methane following a nitrogen lift. The nitrogen lift procedure was used to induce gas flow during liquid unloading. The near-field Gaussian plume inversion flux quantification method was used to derive four instantaneous flux ranges (within uncertainty) from the four UAV flight surveys conducted during the emission window.
Automatic flood extent mapping using long time series of SAR imagery and water levels or discharge data
Authors: Berezowski Tomasz
Published: March 2020

Long time series of flood extent mapping are valuable for flooding frequency analysis, wetlands monitoring and hydrological model validation. In this study an automatic algorithm for flood extent mapping using long time series of synthetic aperture radar (SAR) imagery and observed water levels or discharge is presented. The key assumption of this algorithm is that the flooding extent is correlated to these two observed variables and the highest correlation is obtained when the flood/no flood threshold value of SAR backscatter coefficient is optimal. This study is conducted in the Biebrza River floodplain (approximately 220km2) located in NE Poland. The floodplain is a natural wetland, relatively untouched by human, with complex inundation that involves not only river flooding, but also groundwater discharge and rain or snowmelt local inundation. In order to map 2014-2018 flooding series the automatic thresholding algorithm is run on Sentinel 1 data from one relative orbit, yielding 161 SAR scenes. The estimated 2014-2018  water line match well water levels from independent water gauge and the inundation maps agree with the MODIS 500m reflectance image. This approach was unable to identify inundation in remote parts of the floodplain except very intensive groundwater discharge events. This behavior may have several reasons, of which the most probable are that the dense vegetation obscuring inundated ground and that groundwater, snowmelt or rainfall inundation is not correlated to the variables recorded at a water gauge located in the river.
How efficient are Early Career Scientists in peer-review activities?
Authors: Casado Mathieu , Gremion Gwenaëlle , Aho Kelsey , Caccavo Jilda , Champollion Nicolas , Choy Emily , Dey Rahul , Fernandez Alfonso , Fugmann Gerlis , Höfer Juan , Jawak Shridar , Mayers Kyle , Maes Sarah , Mojica Jhon Fredy , Lizotte Martine , Pandit Prashant , Rosenbaum Paul , Seyboth Elisa , Shakil Sarah , van Soest Maud
Published: March 2020

In our collective endeavour towards global sustainability, there is now a broad appreciation that producing scientifically robust knowledge requires new forms of engagement between scientists, stakeholders and society. But what is the role of Early Career Scientists (ECS) in these processes that are closing the gap between science and policy? Because opportunities to interact with more experienced peers through science refereeing are scarce, the role of ECS in the peer-review process remains minor despite ECS possessing strong academic credentials. Such engagement in the peer-review process represents a valuable opportunity for ECS and the scientific community as a whole. This opportunity provides a robust platform for ECS to understand the overall review process and editorial activities related to high-credibility publications such as those conducted by the Intergovernmental Panel on Climate Change (IPCC). During May/November 2018, 174 ECS on behalf of the Association of Polar Early Career Scientists (APECS) reviewed the first and second-order drafts of the IPCC “Special Report on Ocean and Cryosphere and in a Changing Climate (SROCC)”. Here, we present the methodology, results, and lessons learned from these group reviews. Altogether, data from participant surveys on their experience and their comments catalog illustrate ECS as competent reviewers, comparable to more experienced researchers. The diverse disciplines and geographic perspectives, fostered through APECS and its partners, are currently being mobilized in the First Order Draft of the Working Groups I and II of the Assessment Report 6 of the IPCC, and will continue during the second round of reviews of these reports in early 2020. Information gathered during these ongoing reviews will add to the findings obtained during the review of the SROCC.
Air mass characterization based on VOC measurements downstream of European and Asian Major Population Centers (MPC) during the research aircraft campaign EMeRGe (2017/2018)
Authors: Förster Eric , Bönisch Harald , Neumaier Marco , Obersteiner Florian , Lichtenstern Michael , Hilboll Andreas , Kalisz Hedegaard Anna B. , Vrekoussis Mihalis , Zahn Andreas
Published: March 2020

EMeRGe (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales) aims to investigate the impact of MPC emissions on air pollution and chemical processing at local, regional and hemispheric scales by making dedicated airborne measurements using the German research aircraft HALO. Transects and vertical profiling for diverse MPCs (e.g. Rome, London, Taipei, Manila) were performed to determine the composition and transformation of various pollution plumes in Europe and Asia.

To characterize air masses we evaluate different volatile organic compounds (VOCs), measured by a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS), with different or similar sources and different lifetimes. We use the specific tracer acetonitrile to identify air masses influenced by biomass burning (BB), the aromatic compound benzene to tag anthropogenic pollution plumes (e.g. from traffic or industry) and short-lived isoprene as indicator for fresh biogenic influences. Back trajectories based on FLEXTRA (FLEXible TRAjectory model) are used to determine potential source regions of BB affected air and anthropogenic pollution plumes.

Results show that in Europe only minor BB influenced air masses were sampled. However, in Southern France fresh BB close to the source was detected. In contrast to Europe, numerous plumes affected by BB were identified in Asia originating mostly from Southeast Asia.

Air masses with enhanced concentrations in benzene and low concentrations in acetonitrile, indicating anthropogenic pollution, were sampled in Europe over the Po-Valley, Rome, Barcelona and the English Channel. In Asia, plumes were identified along the west coast of Taiwan, the East China Sea and Manila originating from local sources as well as transported from Mainland China.

Significant fresh biogenic influence was found in Europe, as the measurements were performed mostly in summer over land in contrast to Asia were just a minor influence was detected.
Jurassic to Cretaceous structural evolution and subsidence patterns of the Southern Central Graben (North Sea) – a combination of extensional tectonics and salt movement
Authors: Warsitzka Michael , Müller Simon , Jähne-Klingberg Fabian , Bense Frithjof
Published: March 2020

The Southern Central Graben is a prominent evaporite-influenced rift structure in the Central European North Sea region. The evolution of the graben probably started in the Permian followed by several minor rifting phases during the Mid to Late Triassic. After a phase of regional uplift from the latest Early to Mid Jurassic, a major rifting phase occurred during the Late Jurassic and lasted until Early Cretaceous. In the Late Cretaceous, the graben was partly inverted due to tectonic compression. The southern part of the graben, located in the German and Dutch North Sea sector, is characterized by a half-graben structure bounded by a complex normal fault system at the eastern flank. The internal structure of the graben is differentiated into several sub-basins. More importantly, the Post-Permian graben fill was affected by mobilization of the Upper Permian Zechstein evaporites. Numerous salt diapirs and adjacent depocentres developed due to salt redistribution in particular during the Jurassic and Cretaceous.

Even if the overall tectonic and sedimentary evolution of the graben is well known, a detailed survey on the extensional phases and the influence of salt movement on the subsidence patterns has not yet been carried out. In this study, we intend to investigate these aspects based on interpretation of 2D and 3D seismic data and cross section restoration. With special focus on the Late Jurassic to Early Cretaceous main rift event, we aim to distinguish the effects of extensional tectonics and salt movement on the local subsidence patterns. In the study area (northern Dutch, German and southern Danish North Sea sectors), we mapped 15 stratigraphic Post-Permian horizons in total of which 9 belong to the Jurassic and Early Cretaceous. Based on the depth-converted seismic interpretations, depth and thickness maps were constructed. Subsidence analysis and 2D backstripping of the depocentres enabled us to constrain timing and spacing of the tectonic activity and the salt migration.

The outcomes of this study show that depocentres at the graben edges are mainly controlled by fault movement at the base of the salt. In contrast, structural patterns of post-Permian layers in the graben interior are often decoupled from base-salt features, i.e. faults in the base do not penetrate into supra-salt layer. Instead the post-Permian strata is gently folded, affected by thin-skinned extension, and penetrated by salt diapirs. The subsidence patterns of the Mesozoic strata were controlled by differential movement of sub-salt faults and overprinted by movement of the underlying Zechstein evaporites. We suggest that salt migration and its influence on subsidence patterns were strongest during the Late Jurassic probably accompanied by the initiation and acceleration of salt diapir growth and the lateral migration of depocentres.
Lagoa de Santo André - The Holocene evolution of a coastal lake at the Atlantic coast of Portugal
Authors: Frank Sebastian , Laermanns Hannes , Pint Anna , Wagner Barbara , Bellanova Piero , Feist Lisa , Mathes-Schmidt Margret , Reicherter Klaus , Brückner Helmut
Published: March 2020

The Lagoa de Santo André is a coastal lake located ca. 80 km south of Lisbon at the Atlantic coast of Portugal. The region is highly vulnerable to earthquake-triggered tsunami events due to its exposure to the very active tectonic boundary between the Eurasian and the African plates. Despite several natural and artificial breaches of beach barrier in the past, the lagoon still represents an appropriate geo-bio-archive for reconstructing the Holocene palaeoenvironmental evolution. For this purpose, a 10-m-long sediment core was taken from the centre of the lake by using a floating platform. Sedimentological, geochemical and micropalaeontological analyses were performed in order to unravel the former geological and climatic conditions, and to identify short-term events like tsunamis or storm surges that might have crossed or breached the shielding barrier, leaving their footprint in the sedimentary record of the lagoon.

The sediment core covers the palaeoenvironmental evolution of Lagoa de Santo André for at least the last eight millennia. The sandy deposits of the lowermost part of the core most likely represent the littoral phase of a palaeo-beach that had developed when the postglacial marine transgression had reached the area. Above alternating layers indicate varying environmental conditions that are characterised by peat growth, stagnant-water areas and intercalating sand layers that deposited during disconnections from and reconnections with the open sea. Since 3000 BC at the latest, the longshore transport had formed a beach barrier that separated the coastal lake from the open sea. As yet no deposits of an extreme wave event have been detected. However, the ongoing microfaunal analysis will clarify, if sudden changes of the salinity have occurred due to significant saltwater intrusions, which would hint at potential extreme wave events.
Inconsistent hydrological frequency calculation and attribution analysis of annual runoff of Lancang river basin based on LWHM-LUCC model
Authors: Xie Ping , Yu Tao , Wu Linqian , Wu Ziyi
Published: March 2020

In the context of global climate change and intensive human activities, the runoff process in the Lancang River Basin has been greatly changed. This study proposed a lumped watershed hydrological model considering land use/cover change (LWHM-LUCC) for the frequency calculation and attribution analysis of annual runoff of Lancang River Basin from physical causes aspect. We first detected the variability of precipitation, evaporation, and runoff time series at annual time scale of the Lancang River Basin during 1961–2014 through the hydrological variation diagnosis system. Then, the inconsistent runoff frequency calculation method based on LWHM-LUCC model were applied to analyze the annual runoff frequency distribution in past, current and future period, respectively. Besides, the contribution rates of climate change and human activities on runoff variation were quantatively determined based on LWHM-LUCC model and scenarios simulation. The result showed that there was an abrupt increase of evaporation in 2002, and an abrupt decrease of runoff in 2004. From the distant past period, near past period, to the current period, the design runoff in the Lancang River Basin showed a declined trend, whereas the runoff in the current and future periods remained basically unchanged, and the difference between current and distant past period was much larger than that between current and near past period. The contribution rates of precipitation, evaporation, land use and other human activities to runoff variation were around 38%, 31%, 0% and 31%, respectively. This indicated climate change has greater impact on runoff variation than human activity in the Lancang River Basin.
Impact of antibiotic pollution from wastewater irrigation on soils and agroecosystems
Authors: Stockdale James , Sallach Brett , Zealand Andrew , McCann Clare , Bey Ergun , Ring-Hrubesh Fin , Graham David , Boxall Alistair , Toet Sylvia
Published: March 2020

Growing global demand of water use, and regional changes in precipitation in many regions, has resulted in increasing long-term irrigation of agricultural soils with post-treatment waste water. Overlaying this trend with the rising use of pharmaceuticals has created a new pathway for these pollutants, including biologically active compounds such as antibiotics, to enter the soil environment. We present results from a new interdisciplinary study of the response of an agroecosystem which was repeatedly contaminated with a typical combination of antibiotics at a representative concentration found in waste water effluent. Results from this experimental manipulation, show the impact of different concentrations of antibiotics in the soil and the unexpected repercussions throughout the agroecosystem. This includes effects on soil microbial communities, microbial function (anti-microbial resistance), abiotic soil condition, antibiotic persistence in the soil, ecosystem function (greenhouse gas exchange) and the effect on the arable crop itself. Implications of this study are relevant to fully understanding the impact of this land management technique on the sustainability of food production.

This study was funded through the UK’s N8AgriFood Programme.
Land subsidence prediction with uncertainty analysis by a smoother algorithm with a multiple calibration-constrained null-space Monte Carlo method
Authors: Aichi Masaatsu
Published: March 2020

Predicting the future land subsidence caused by groundwater abstraction is necessary for the planning and decision-making of groundwater usage in coastal area. Although numerical modeling is expected to quantitatively predict land subsidence, a single calibrated model cannot provide a reliable prediction because of the uncertainty on properties and conditions in the subsurface. In addition, applying ensemble Kalman filter or ensemble smoother to land subsidence modeling is not straightforward because of the highly nonlinear and hysteric characteristics in clay compaction process.

This study developed a smoother algorithm with a multiple calibration-constrained null-space Monte Carlo method for a numerical simulator of groundwater mass balance with modified Cam-clay model. The developed algorithm calibrates a model ensemble using a newly obtained observed value in each observation step. Based on the calibration-constrained null-space Monte Carlo method, a new model ensemble in the null-space is produced in each observation step. In this step, both the current and past state as well as parameters in the model are updated like ensemble smoother in order to follow the hysteretic behavior in the soil compaction. The produced ensemble can be used not only for prediction uncertainty analysis at that step but also as initial estimates of a multiple calibration-constrained null-space Monte Carlo method in the next observation step.

The proposed method was applied to the land subsidence modeling in the Tokyo lowland area, Japan. The proposed method could make model ensemble with satisfactory good reproducibility and show the range of uncertainty of future prediction for several scenarios of future groundwater level change.
The SpannEnD Project - Numerical modelling of the 3D stress state of Germany
Authors: Ahlers Steffen , Röckel Luisa , Henk Andreas , Reiter Karsten , Hergert Tobias , Müller Birgit , Schilling Frank , Heidbach Oliver , Morawietz Sophia , Scheck-Wenderoth Magdalena , Anikiev Denis
Published: March 2020

One important criterion for the characterization of a potential nuclear waste repository is the crustal stress field. However, stress data are sparse and usually incomplete regarding the six independent components of the stress tensor. The World Stress Map (WSM) is a valuable compilation of stress data, but it does not include information about stress magnitudes as only the orientation of the maximum horizontal stress (SHmax) is provided. To receive a comprehensive and continuous 3D description of the stress field in a particular area, geomechanical-numerical modelling is required. Key objectives of the SpannEnD project (Spannungsmodell Endlagerung Deutschland) is to provide such a model for Germany and to develop methods for robust stress predictions at the local scale.

The SpannEnD model is based on finite element techniques and comprises a 3D lithosphere-scale structural model of Germany. The lateral extent of the model covers a pentagon-shaped area of Central Europe with dimensions of 1000 x 1250 km². The model has been chosen significantly larger than Germany to reduce boundary effects in the study area. Furthermore, on the base of the observed stress orientation pattern, the boundaries have been defined parallel or perpendicular to the known orientation of SHmax to simplify the definition of the boundary conditions. The vertical extent of the model is from the surface to a depth of 100 km, incorporating several sedimentary layers, several basement units and the Mohorovičić discontinuity. The mesh is laterally homogenous with a resolution of about 4 km and vertically inhomogeneous with a decreasing resolution with increasing depth, to provide the finest mesh in the layers of the greatest interest, near the surface. These units also provide the most stress data measurements to calibrate the model. Furthermore, a selected number of important faults is implemented in the model. This structural model is discretized into about 4 million elements. For the calibration of the model we use a new compilation of stress magnitude data. We present the workflow, the model geometry, and some first results.
Future impact of the Harmony InSAR satellite mission on land ice monitoring
Authors: Mulder Gert , Kleinherenbrink Marcel , Theodosiou Andreas , Lopez-Dekker Paco
Published: March 2020

Current InSAR satellite missions have proven to be a valuable tool to monitor land ice worldwide. Applications are monitoring of glacier motion, ice/snow characteristics, but also glacier and snow type extend. Because these satellites work under all weather and lighting conditions, these missions are especially valuable in polar regions.

However, almost all current systems are restricted to repeat-pass interferometry and a single viewing geometry, limiting their use for land ice applications.

Harmony, an Earth Explorer 10 candidate mission, will strongly improve the capabilities of InSAR data for monitoring of land ice worldwide. This constellation comprises of two satellites that will fly as companions of one of the Sentinel-1 satellites. Harmony will make single-pass interferometry possible, which will be used to create improved, high-resolution digital elevation models to monitor ice mass loss. Additionally, single-pass interferometry will also provide us more details on ice and snow characteristics. Finally, every scene will be viewed from different look angles, which can enhance current ice flow estimates and allows the generation of precise three-dimensional ice motion products over the ice sheets.

In this study we show the future capabilities of the Harmony for land ice monitoring using performance models. Where possible, these models are calibrated and compared with already available Sentinel-1 data. Capabilities of the Sentinel-1 satellites for the monitoring of year-round ice movements and ice/snow characteristics are illustrated by a number of case studies.
Applying causal discovery algorithm to find predictors for transformation process of wood combustion emission
Authors: Leinonen Ville , Tiitta Petri , Sippula Olli , Czech Hendryk , Leskinen Ari , Karvanen Juha , Isokääntä Sini , Mikkonen Santtu
Published: March 2020

Aerosols and their transformation process in atmosphere have significant effects on climate. Transformation process is a complex combination of physical and chemical reactions. Multiple oxidizing agents and other factors, such as radiation, affect the transformation process. Characterization of these factors and their strength is a problem, where advanced methods might help to gain more understanding.

In this work, we modeled transformation of wood combustion emission measured in the environmental chamber by using causal modeling (Pearl, 2009). The aim of the study was to use state-of-the-art causal discovery methods to search causal pathways between measured variables: precursors and particle products. The data used in the modelling are introduced in Tiitta et al. (2016).

In addition to wood combustion experiments, we simulated artificial datasets to understand abilities of the model. We wanted to evaluate the accuracy of our model to confirm the correct structure between variables and reproduce the measured transformation. This helps us to understand the model performance in real datasets.

We found that model could reproduce the measured evolution well. The structure between emission parts was not completely matching to prior assumption. Usually incorrect predictors in the modeled structure are highly correlated with correct causes.

 

References:

Pearl, J.: Causality : Models, Reasoning and Inference., Cambridge University Press., 2009.

Tiitta et al., Atmos. Chem. Phys., 16, 13251-13269, 2016.
TROPOMI/S5P MLS/BASCOE tropospheric ozone product and TROPOMI observation of ozone precursors
Authors: Heue Klaus-Peter , Loyola Diego , Romahn Fabian , Zimmer Walter , Lerot Christophe , van Roozendael Michel , de Smedt Isabelle , Theys Nicolas , Chabrillat Simon , Errera Quentin , Christophe Yves , Eskes Henk , van Geffen Jos
Published: March 2020

 Sentinel 5 Precursor (S5P) satellite was launched into a polar orbit in October 2017, carrying the TROPOMI instrument. S5P has sun synchronous orbit with an equator crossing time of 13:30 LT; TROPOMI achieves an almost daily coverage, due to the wide swath width of 2600 km. Based on the observed spectra in the UV-Vis range the trace gases ozone, formaldehyde and nitrogen dioxide are retrieved. We developed a research tropospheric ozone product based on the operational total column from S5P and the stratospheric column obtained from Aura MLS assimilated ozone profiles using the BASCOE system. The enhanced tropospheric ozone columns are observed at several places and often collocate with locale enhancements of NO2 and HCHO. Both these trace gases are known to be involved in the tropospheric ozone formation.

The tropospheric ozone product will be briefly presented; the focus will be on large scale enhancements of tropospheric ozone and collocated HCHO and NO2 observations. In addition examples of enhancemnets of HONO or Glyoxal may be stduied. The large fires in the Amazonian forest and Australia cause an enhancement compared to previous years. Over the southern US both HCHO and tropospheric ozone are enhanced in summer time. Some transport of ozone and its’ precursors can be found in East Asia.
Observed seasonality in internal wave energy and associated mixing in a temperate shelf sea
Authors: Wihsgott Juliane , Palmer Matthew , Sharples Jonathan , Hopkins Jo
Published: March 2020

Long-term observations (March’14 − July’15) of ocean density and velocity from the North West European shelf reveal a seasonality in internal wave energy linked to the seasonal cycle of stratification. Further, this seasonality extends to internal mixing associated with internal waves that can be effectively described by the buoyancy frequency (N2), with the strongest mixing associated with strongly stratified summer conditions. To better understand these results a model was used that employed three different, commonly used parameterisations of internal mixing. Each parameterisation produced some degree of seasonality in internal mixing. Contrary to observed results however, all three model scenarios produced a minimum in internal mixing during summer, with enhanced mixing observed during spring and autumn. This failure in each model was attributed to the lack of realistic levels of enhanced baroclinic energy and shear (S2) that is identified in observations to be attributable to internal waves. These observations reveal a close relationship between N2and S2, resulting in a near continuous state of marginal stability; where the gradient Richardson number is maintained at a near critical level. Due to the observed strong dependence of internal wave energy and internal mixing on stratification, a modified version of the MacKinnon and Gregg (2003a) turbulence scaling was employed. This modified parameterisation successfully replicated the observed seasonality in internal mixing. This important result implies that future parameterisations should aim to scale internal mixing on enhanced levels of S2 from internal waves, which are shown here to be suitably predicted by the seasonal cycle of stratification (N2).
Design and Performance Evaluation of Internet of Things (IoT) Based Multifunctional Device for Plant Ecophysiology & Hydrology: Toward Stem Water Content & Sap Flow
Authors: Asgharinia Shahla , Belelli Marchesini Luca , Gianelle Damiano , Valentini Riccardo
Published: March 2020

Using IoT technologies represents a novel low cost and efficient tool for studies in many disciplines (plant ecophysiology and hydrology) to unravel the vulnerability of an ecosystem to climatic stress. Taking advantage of IoT, a new multifunctional device, the “TreeTalker”, was developed to monitor in real time physical and biological parameters of single trees as well as some additional ecosystem-related variables. Here, we present performance of the TreeTalker to illustrate mainly the role of stem water content and water transport in tree behavior and function with respect to internal and external forces. TreeTalker is designed based on Granier-type thermal dissipation probe (TDP) and a capacitance sensor to measure stem water content.

In this study, two main experiments are analyzed. In the first experiment, procedures for calibration and use of capacitance sensors are presented. Considering the effect of wood density on frequency data, calibration is performed on different species and diameter harvested stems to convert the sensor-reported values to stem volumetric water content. In the second experiment, application of 20 TreeTalkers with particular emphasis placed on measuring hourly, daily and monthly sap flow and stem water content fluctuations under well-irrigated and deficit-irrigated treatments of Juglans regia L. was conducted on a study site in northeast of Italy.  

The results show that the range of stem water content is highly influenced by environmental factors. Stem water content has a significant portion of the daily tree water uptake. Low water storage occurs in response to drought and less soil water availability, which clarifies the high dependency of trees on stem water content under deficit-irrigated treatments. The diurnal-nocturnal pattern of stem water content and sap flow revealed an inverse relation. Such finding, still under investigation is explained by the important water recharge during the night, likely due to stem volume changes and lateral water distribution rather than by vertical flow rate. 