bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling Gas Exchange and Biomass Production in West
African Sahelian and Sudanian Ecological Zones
Authors: Rahimi Jaber , Ago Expedit Evariste , Ayantunde Augustine , Berger Sina , Bogaert Jan , Butterbach-Bahl Klaus , Cappelaere Bernard , Demarty Jérôme , Diouf Abdoul Aziz , Falk Ulrike , Haas Edwin , Hiernaux Pierre , Kraus David , Roupsard Olivier , Scheer Clemens , Srivastava Amit Kumar , Tagesson Torbern , Grote Rüdiger
Published: February 2021

Abstract. West African Sahelian and Sudanian ecosystems are providing essential services to people and also play a significant role within the global carbon cycle. However, climate and land use are dynamically changing and it remains uncertain how these changes will affect the potential of these regions for providing food and fodder resources or the biosphere-atmosphere exchange of CO2. In this study, we investigate the capacity of a process-based biogeochemical model, LandscapeDNDC, to simulate net ecosystem exchange (NEE) and aboveground biomass of typical managed and natural Sahelian and Sudanian savanna ecosystems. We tested the model for various sites with different proportions of trees and grasses, as well as for the most typical arable cropping systems of the region. In order to describe the phenological development with a common parameterization across all ecosystem types, we introduced soil-water availability in addition to temperature as a driver as seasonal soil water-shortage is a common feature for all these systems. The new approach was tested by using a sample of sites (calibration sites) that provided NEE from flux tower observations and leaf area index data from satellite images (MODIS). For assessing the simulation accuracy, we applied the calibrated model to 42 additional sites (validation sites) across West Africa for which measured aboveground biomass data were available. The model showed a good performance regarding simulated biomass development. Overall, the comparison of simulated and observed biomass at sites with a dominating land cover of crops, grass or trees yielded correlation coefficients of 0.82, 0.94, and 0.77 and the Root Mean Square Error of 0.15, 0.22, and 0.12 kg m−2, respectively. In absolute terms, the model results indicate above-ground carbon stocks up to 1733, 3291, and 5377 kg C ha−1 yr−1 for agricultural, savanna grasslands, and savanna mixed tree-grassland sites. Carbon stocks as well as exchange rates correlated in particular with the abundance of trees. The simulations indicate higher grass biomass and crop yields under more humid climatic conditions as can be found in the Sudanian savanna region. Our study shows the capability of LandscapeDNDC to accurately simulate carbon balances in natural and agricultural ecosystems in semi-arid West Africa under a wide range of conditions, so that it might be used to assess the impact of land-use and climate change on the regional biomass productivity.
Spatio-temporal soil moisture retrieval at the catchment-scale using
a dense network of cosmic-ray neutron sensors
Authors: Heistermann Maik , Francke Till , Schrön Martin , Oswald Sascha E.
Published: February 2021

Abstract. The method of Cosmic-Ray Neutron Sensing (CRNS) is a powerful technique to retrieve representative estimates of soil water content at a horizontal scale of hectometers (the field scale) and depths of tens of centimeters (the root zone). This study demonstrates the potential of the CRNS technique to obtain spatio-temporal patterns of soil moisture beyond the integrated volume from isolated CRNS footprints. We use data from an observational campaign between May and July 2019 which featured a network of more than 20 neutron detectors with partly overlapping footprints in an area that exhibits pronounced soil moisture gradients within 1 km2. The present study is the first to combine these observations in order to represent the heterogeneity of soil water content at the sub-footprint scale as well as between the CRNS stations. First, we apply a state-of-the-art procedure to correct the observed neutron count rates for static effects such as sensor sensitivity, vegetation biomass, soil organic carbon and lattice water, as well as for the influence of the temporally dynamic factors barometric pressure, air humidity, and incoming flux of neutrons. Based on the homogenised neutron data, we investigate the robustness of a uniform calibration approach using one calibration parameter value across all CRNS stations. Finally, we benchmark two different interpolation techniques in order to obtain space-time representations of soil moisture: first, Ordinary Kriging with a fixed range; second, a heuristic approach that complements the concept of spatial interpolation by the idea of a geophysical inversion (constrained interpolation). For the latter, we define a geostatistical model of the spatial soil moisture variation in the study area, and then optimize the parameters of that model so that the error of the forward-simulated neutron count rates is minimized. In order to make the optimization problem computationally feasible, we use a heuristic forward operator that is based on the physics of horizontal sensitivity of the neutron detector. The comparison with independent measurements from a cluster of soil moisture sensors (SoilNet) shows that the constrained interpolation approach outperforms Ordinary Kriging by putting a stronger emphasis on horizontal soil moisture gradients at the hectometer scale. The study demonstrates how a CRNS network can be used to generate consistent interpolated soil moisture patterns that could be used to validate hydrological models or remote sensing products.
A reduced-complexity model of ﬂuvial inundation with a sub-grid
representation of ﬂoodplain topography evaluated for England,
United Kingdom
Authors: Dadson Simon J. , Blyth Eleanor , Clark Douglas , Davies Helen , Ellis Richard , Lewis Huw , Marthews Toby , Rameshwaran Ponnambalan
Published: February 2021

Abstract. Timely predictions of fluvial flooding are important for national and regional planning and real-time flood response. Several new computational techniques have emerged in the past decade for making rapid fluvial flood inundation predictions at time and space scales relevant to early warning, although their efficient use is often constrained by the trade-off between model complexity, topographic fidelity and scale. Here we apply a simplified approach to large-area fluvial flood inundation modelling which combines a 5 solution to the inertial form of the shallow water equations at 1 km horizontal resolution, with two alternative representations of sub-grid floodplain topography. One of these uses a fitted sub-grid probability distribution, the other a quantile-based representation of the floodplain. We evaluate the model's performance when used to simulate the 0.01 Annual Exceedance Probability (AEP; 100-year) flood and compare the results with published benchmark data for England. The quantile-based method accurately predicts flood inundation in 86 % of locations, with a domain-wide hit rate of 95 % and 10 false alarm rate of 10 %. These performance measures compare with a hit rate of 71 %, and false alarm rate of 9 % for the simpler, but faster, distribution-based method. We suggest that these approaches are suitable for rapid, wide-area flood forecasting and climate change impact assessment.
Bias-correcting individual inputs prior to combined calibration leads to more skillful forecasts of reference crop evapotranspiration
Authors: Yang Qichun , Wang Quan J. , Hakala Kirsti , Tang Yating
Published: February 2021

Abstract. Reference crop evapotranspiration (ETo) is calculated using a standard formula with temperature, vapor pressure, solar radiation, and wind speed as input variables. ETo forecasts can be produced when forecasts of these input variables from numerical weather prediction (NWP) models are available. As raw ETo forecasts are often subjective to systematic errors, calibration is necessary for improving forecast quality. The most straightforward and widely used approach is to directly calibrate raw ETo forecasts constructed with the raw forecasts of input variables. However, the potential predictability of ETo may not be fully explored by this approach, which ignores the non-linear interactions of input variables in constructing ETo forecasts. We hypothesize that reducing errors in individual inputs as a precursor to ETo forecast calibration will lead to more skillful ETo forecasts. To test this hypothesis, we evaluate two calibration strategies, including (i) calibration directly applied to raw ETo forecasts constructed with raw forecasts of input variables, and (ii) bias-correcting input variables first, and then calibrating the ETo forecasts constructed with bias-corrected input variables. We calibrate ETo forecasts based on weather forecasts of the Australian Community Climate and Earth System Simulator G2 version (ACCESS-G2). Calibrated ETo forecasts with bias-corrected input variables (strategy ii) demonstrate lower bias, higher correlation coefficient, and higher skills than the calibration based on raw input variables (strategy i). This investigation indicates that improving raw forecasts of input variables could enhance ETo forecast calibration and produce more skillful ETo forecasts. This calibration strategy is expected to enhance future NWP-based ETo forecasting.
Pesticide peak concentration reduction in a small vegetated treatment system controlled by chemograph shape
Authors: Greiwe Jan , Olsson Oliver , Kümmerer Klaus , Lange Jens
Published: February 2021

Abstract. Pesticides may impact aquatic ecosystems when entering
water bodies. Measures for mitigation against pesticide inputs include
vegetated treatment systems (VTSs). Some of these systems have very short
hydraulic retention time (< 1 h) but nevertheless manage to
effectively reduce peak concentrations of contaminants as a result of
dispersion. We hypothesize that the effect of dispersion on contaminant
mitigation in VTSs depends on the shape of the contaminant input signal
chemograph, which in turn is related to factors affecting contaminant
mobilization in the contributing catchment. In order to test this hypothesis,
we grouped chemographs of six contaminants originating from a viticultural
catchment during 10 discharge events into clusters according to chemograph
shape. We then compared peak concentration reduction and mass removal in a
downstream VTS, both among clusters and in terms of compound properties and
discharge dynamics. We found that chemograph clusters reflected combined
effects of contaminant source areas, transport pathways, and discharge
dynamics. While mass loss was subject to major uncertainties, peak
concentration reduction rate was clearly related to chemograph clusters and
dispersion sensitivity. These findings suggest that mitigation of acute
toxicity in a VTS is stronger for compounds with sharp-peaked chemographs,
whose formation is related to the contributing catchment and can be analyzed
by chemograph clustering.
The development of geophysics in the early period of the People's Republic of China based on the Institute of Geophysics, Chinese Academy of Sciences (1950–1966)
Authors: Zhang Zhihui , Wang Rui
Published: February 2021

Abstract. From the perspective of the social history of science and transnational history, this paper reviewed the development of the Institute of Geophysics, Chinese Academy of Sciences (IGCAS), rather than focusing on its scientific achievements. Before the 1950s, the discipline of geophysics in China, except for the branch of meteorology, had a very weak foundation, and few researchers were engaged in it. The systematic development of geophysics began with the establishment of IGCAS. In this paper, the early development of IGCAS was researched thoroughly. At first, we briefly reviewed the establishment process for IGCAS. After being promoted by the desire of scientists to develop big geophysics, the Chinese Academy of Sciences (CAS) integrated scattered academic forces, which included geomagnetism and geophysical exploration, to establish the IGCAS. The IGCAS was based on the Institute of Meteorology of Academia Sinica in the Republic of China era. After that, we summarized work done by IGCAS in the development of geophysics from the 1950s to 1966, the year in which the Cultural Revolution began. We focused on policy support, adjustment of organizational structure, and scientific capacity building, when China was facing an isolated international diplomatic environment, continuous domestic political movements, and an austere social economy. Then, to bolster the development of geophysics in China, the slogan of “Missions Drive Disciplines”, which was instilled and implemented by the Chinese scientific community, was introduced briefly. The scientific development of the IGCAS and typical examples in several branches of geophysics, which included atmospheric science, seismology, space physics, and other fields, were systematically summarized and benchmarked to the international academic level. We then summarized the basic research on geophysics carried out by the institute in economic construction and national defense. Finally, the experience and lessons in the development of this institute and its effect on geophysics in China were explored.
Overhauser Dynamic Nuclear Polarization Enhanced Two-Dimensional Proton NMR Spectroscopy at Low Magnetic Fields
Authors: Keller Timothy J. , Maly Thorsten
Published: February 2021

Abstract. The majority of low-field Overhauser Dynamic Nuclear Polarization (ODNP) experiments reported so far have been 1D NMR experiments to study hydration dynamics. In this work, we demonstrate the application of ODNP-enhanced 2D J-resolved (JRES) spectroscopy to improve spectral resolution beyond the limit imposed by the line broadening introduced by the paramagnetic polarizing agent. Using this approach, we are able to separate the overlapping multiplets of ethyl crotonate into a 2nd dimension and clearly identify each chemical cite individually. Crucial to these experiments is interleaved spectral referencing, a method introduced to compensate for temperature induced field drifts over the course of the NMR acquisition. This method does not require additional hardware such as a field-frequency lock, which is especially challenging when designing compact systems.
Competing Transfer Pathways in Direct and Indirect Dynamic
Nuclear Polarization MAS NMR Experiments on HIV-1 Capsid
Assemblies: Implications for Sensitivity and Resolution
Authors: Sergeyev Ivan V. , Quinn Caitlin M. , Struppe Jochem , Gronenborn Angela , Polenova Tatyana
Published: February 2021

Abstract. Dynamic nuclear polarization-enhanced (DNP) magic angle spinning (MAS) NMR of biological systems is a rapidly growing field. Large signal enhancements make the technique particularly attractive for signal-limited cases, such as studies of complex biological assemblies or at natural isotopic abundance. However, spectral resolution is considerably reduced compared to ambient-temperature non-DNP spectra. Herein, we report a systematic investigation into sensitivity and resolution of 1D and 2D 13C-detected DNP MAS NMR experiments on HIV-1 CA tubular assemblies. We show that the magnitude and sign of signal enhancement as well as the homogeneous line width are strongly dependent on the biradical concentration, the dominant polarization transfer pathway, and the enhancement buildup time. Our findings provide guidance for optimal choice of sample preparation and experimental conditions in DNP experiments.
Analysis and control of state jump in space deployable structures under alternating temperature loads
Authors: Chen Congcong , Li Tuanjie , Tang Yaqiong , Wang Zuowei
Published: February 2021

Abstract. State jump has been experimentally observed in space
deployable structures working in alternating temperature environments. State
jump is a phenomenon in which the geometric shape of the structure changes after
the temperature loading and unloading process, which makes the working
accuracy of the space deployable structure intrinsically unpredictable. This
paper aims to investigate the causes of this state jump phenomenon and seek
measures to reduce its effect. Firstly, the static multiple-stable-state
phenomenon resulting in state jump is analyzed for clearance joints in
deployable structures. Then, an equivalent model consisting of a variable
stiffness spring and a contact element for state jump analysis is proposed,
which is verified by a finite element simulation. Influence factors and
control methods of state jump are further explored. Finally, numerical
results of a space deployable structure of an umbrella-shaped antenna show
the effectiveness of the developed analytical method.
Optimizing and validating the Gravitational Process Path model for
regional debris-flow runout modelling
Authors: Goetz Jason , Kohrs Robin , Parra Hormazábal Eric , Bustos Morales Manuel , Belén Araneda Riquelme María , Henríquez Cristián , Brenning Alexander
Published: February 2021

Abstract. Knowing the source and runout of debris-flows can help in planning strategies aimed at mitigating these hazards. Our research in this paper focuses on developing a novel approach for optimizing runout models for regional susceptibility modelling, with a case study in the upper Maipo river basin in the Andes of Santiago, Chile. We propose a two-stage optimization approach for automatically selecting parameters for estimating runout path and distance. This approach optimizes the random walk and Perla's two-parameter modelling components of the open-source Gravitational Process Path (GPP) modelling framework. To validate model performance, we assess the spatial transferability of the optimized runout model using spatial cross-validation, including exploring the model's sensitivity to sample size. We also present diagnostic tools for visualizing uncertainties in parameter selection and model performance. Although there was considerable variation in optimal parameters for individual events, we found our runout modelling approach performed well at regional prediction of potential runout areas. We also found that although a relatively small sample size was sufficient to achieve generally good runout modelling performance; larger samples sizes (i.e. ≥ 80) had higher model performances and lower uncertainties for estimating runout distances at unknown locations. We anticipate that this automated approach using open-source software R and SAGA-GIS will make process-based debris-flow models more readily accessible and thus enable researchers and spatial planners to improve regional-scale hazard assessments.
Risk perception of local stakeholders on natural hazards: implications for theory and practice
Authors: Mărgărint Mihai Ciprian , Niculiţă Mihai , Roder Giulia , Tarolli Paolo
Published: February 2021

Abstract. In Romania, local stakeholders' knowledge plays a decisional role in emergencies, supporting rescue officers in natural hazard events, coordinating and assisting, both physically and psychologically, the affected populations. However, despite in Iași Metropolitan area (NE of Romania), the occurrence and severity of natural hazards are increasing there is a lack of knowledge of local stakeholders to address the population toward safety actions. For this reason, 118 local stakeholders were interviewed to determine their risk awareness and preparedness capacities over a set of natural hazards to understand where the lack of knowledge, action, and trust are exacerbated the most. Results reveal substantial distinctions among stakeholders and the different threats based on their cognitive and behavioral roles in the communities. The role of responsibility and trust has been seen as important driving factors shaping their perception and preparedness. Preparedness levels were low, and, not for all, learning and preparatory actions are needed to withstand the negative occurrences of natural hazards. As their role is to refer with direct interventions in affected areas managing communication initiatives with the entire population of the community, there is the need to create stakeholders' networks, empowering local actors that could serve as a bridge between authorities' decisions and local people in order to make effective risk management plans and secure more lives and economies.
A dynamic bidirectional coupled surface flow model for flood inundation simulation
Authors: Jiang Chunbo , Zhou Qi , Yu Wangyang , Yang Chen , Lin Binliang
Published: February 2021

Abstract. Flood disasters frequently threaten people and property all over the world. Therefore, an effective numerical model is required to predict the impacts of floods. In this study, a dynamic bidirectional coupled hydrologic–hydrodynamic model (DBCM) is developed with the implementation of characteristic wave theory, in which the boundary between these two models can dynamically adapt according to local flow conditions. The proposed model accounts for both mass and momentum transfer on the coupling boundary and was validated via several benchmark tests. The results show that the DBCM can effectively reproduce the process of flood propagation and also account for surface flow interaction between non-inundation and inundation regions. The DBCM was implemented for the floods simulation that occurred at Helin Town located in Chongqing, China, which shows the capability of the model for flood risk early warning and future management.
A model for interpreting the deformation mechanism of reservoir landslides in the Three Gorges Reservoir area, China
Authors: Zou Zongxing , Tang Huiming , Criss Robert E. , Hu Xinli , Xiong Chengren , Wu Qiong , Yuan Yi
Published: February 2021

Abstract. Landslides whose slide surface is gentle near the toe and
relatively steep in the middle and rear part are common in the Three Gorges
Reservoir area, China. The mass that overlies the steep part of the slide
surface is termed the “driving section”, and that which overlies the gentle
part of the slide surface is termed the “resisting section”. A
driving–resisting model is presented to elucidate the deformation mechanism
of reservoir landslides of this type, as exemplified by Shuping landslide.
More than 13 years of field observations that include rainfall, reservoir
level, and deformation show that the displacement velocity of Shuping
landslide depends strongly on the reservoir level but only slightly on
rainfall. Seepage modeling shows that the landslide was destabilized
shortly after the reservoir was first impounded to 135 m, which initiated a
period of steady deformation from 2003 to 2006 that was driven by buoyancy
forces on the resisting section. Cyclical water level fluctuations in
subsequent years also affected slope stability, with annual “jumps” in
displacement coinciding with drawdown periods that produce outward seepage
forces. In contrast, the inward seepage force that results from rising
reservoir levels stabilizes the slope, as indicated by decreased
displacement velocity. Corrective transfer of earth mass from the driving
section to the resisting section successfully reduced the deformation of
Shuping landslide and is a feasible treatment for huge reservoir landslides
in similar geological settings.
Simulating historical flood events at the continental scale: observational validation of a large-scale hydrodynamic model
Authors: Wing Oliver E. J. , Smith Andrew M. , Marston Michael L. , Porter Jeremy R. , Amodeo Mike F. , Sampson Christopher C. , Bates Paul D.
Published: February 2021

Abstract. Continental–global-scale flood hazard models simulate design floods, i.e. theoretical flood events of a given probability. Since they output phenomena unobservable in reality, large-scale models are typically compared to more localised engineering models to evidence their accuracy. However, both types of model may share the same biases and so not validly
illustrate their predictive skill. Here, we adapt an existing continental-scale design flood framework of the contiguous US to simulate historical flood events. A total of 35 discrete events are modelled and compared to observations of flood extent, water level, and inundated buildings. Model performance was highly variable, depending on the flood event chosen and validation data used. While all events were accurately replicated in terms of flood extent, some modelled water levels deviated substantially from those measured in the field. Despite this, the model generally replicated the observed flood events in the context of terrain data vertical accuracy, extreme discharge measurement uncertainties, and observational field data errors. This analysis highlights the continually improving fidelity of large-scale flood hazard models, yet also evidences the need for considerable advances in the accuracy of routinely collected field and high-river flow data in order to interrogate flood inundation models more comprehensively.
The transient sensitivity of sea level rise
Authors: Grinsted Aslak , Christensen Jens Hesselbjerg
Published: February 2021

Abstract. Recent assessments from the Intergovernmental Panel on
Climate Change (IPCC) imply that global mean sea level is unlikely to rise
more than about 1.1 m within this century but will increase further beyond
2100. Even within the most intensive future anthropogenic greenhouse gas
emission scenarios, higher levels are assessed to be unlikely. However, some
studies conclude that considerably greater sea level rise could be realized,
and a number of experts assign a substantially higher likelihood of such a
future. To understand this discrepancy, it would be useful to have scenario-independent metrics that can be compared between different approaches. The
concept of a transient climate sensitivity has proven to be useful to
compare the global mean temperature response of climate models to specific
radiative forcing scenarios. Here, we introduce a similar metric for sea
level response. By analyzing the mean rate of change in sea level (not sea level
itself), we identify a nearly linear relationship with global mean surface
temperature (and therefore accumulated carbon dioxide emissions) both in model projections and in observations on a century scale. This
motivates us to define the “transient sea level sensitivity” as the increase
in the sea level rate associated with a given warming in units of
meters per century per kelvin. We find that future projections estimated on climate model
responses fall below extrapolation based on recent observational records.
This comparison suggests that the likely upper level of sea level
projections in recent IPCC reports would be too low.
Properties of surface water masses in the Laptev and the East Siberian seas in summer 2018 from in situ and satellite data
Authors: Tarasenko Anastasiia , Supply Alexandre , Kusse-Tiuz Nikita , Ivanov Vladimir , Makhotin Mikhail , Tournadre Jean , Chapron Bertrand , Boutin Jacqueline , Kolodziejczyk Nicolas , Reverdin Gilles
Published: February 2021

Abstract. Variability of surface water masses of the Laptev and the East Siberian seas in August–September 2018 is studied using in situ and satellite data. In situ data were collected during the ARKTIKA-2018 expedition and then complemented with satellite-derived sea surface temperature (SST), salinity (SSS), sea surface height, wind speed, and sea ice concentration. The estimation of SSS fields is challenging in high-latitude regions, and the precision of soil moisture and ocean salinity (SMOS) SSS retrieval is improved by applying a threshold on SSS weekly error. For the first time in this region, the validity of DMI (Danish Meteorological Institute) SST and SMOS SSS products is thoroughly studied using ARKTIKA-2018 expedition continuous thermosalinograph measurements and conductivity–temperature–depth (CTD) casts. They are found to be adequate to describe large surface gradients in this region. Surface gradients and mixing of the river and the sea water in the ice-free and ice-covered areas are described with a special attention to the marginal ice zone at a synoptic scale. We suggest that the freshwater is pushed northward, close to the marginal ice zone (MIZ) and under the sea ice, which is confirmed by the oxygen isotope analysis. The SST-SSS diagram based on satellite estimates shows the possibility of investigating the surface water mass transformation at a synoptic scale and reveals the presence of river water on the shelf of the East Siberian Sea. The Ekman transport is calculated to better understand the pathway of surface water displacement on the shelf and beyond.
Paleozoic-Mesozoic thermal evolution along the East European
Platform margin based on kerogen thermal maturity analysis
combined with apatite and zircon low temperature
thermochronology in NE Poland
Authors: Botor Dariusz , Mazur Stanisław , Anczkiewicz Aneta A. , Dunkl István , Golonka Jan
Published: February 2021

Abstract. The Phanerozoic tectono-thermal evolution of the SW slope of the East European Platform (EEP) in Poland is reconstructed by means of thermal maturity, low temperature thermochronometry and thermal modelling. We provide a set of new thermochronometric data and integrate stratigraphic and thermal maturity information to constrain the burial and thermal history of sediments. Apatite fission track analysis (AFT) and zircon (U-Th)/He (ZHe) thermochronology have been carried out on samples of sandstones, bentonites, diabase and crystalline basement rocks collected from 17 boreholes located in central and NE Poland. They penetrated sedimentary cover of the EEP subdivided from the north to south into the Baltic, Podlasie and Lublin Basins. The average ZHe ages from Proterozoic basement rocks as well as Ordovician to Silurian bentonites and Cambrian to lower Carboniferous sandstones range from 848 ± 81 Ma to 255 ± 22 Ma with a single early Permian age of 288 Ma, corresponding to cooling after a thermal event. The remaining ZHe ages represent partial reset or source ages. The AFT ages of samples are dispersed in the range of 235.8 ± 17.3 (Middle Triassic) to 42.1 ± 11.1 (Paleogene) providing a record of Mesozoic and Cenozoic cooling. The highest frequency of the AFT ages is in the Jurassic and Early Cretaceous prior to Alpine basin inversion. Thermal maturity results are consistent with the SW-ward increase of the Palaeozoic and Mesozoic sediments thickness. An important break in a thermal maturity profile exists across the base Permian-Mesozoic unconformity. Thermal modelling showed that significant heating of Ediacaran to Carboniferous sedimentary successions occurred before the Permian with maximum paleotemperatures in the earliest and latest Carboniferous for Baltic-Podlasie and Lublin Basins, respectively. The results obtained suggest an important role of early Carboniferous uplift and exhumation at the SW margin of the EEP. The SW slope of the latter was afterward overridden in the Lublin Basin by the Variscan orogenic wedge. Its tectonic loading interrupted Carboniferous uplift and caused resumption of sedimentation in the late Viséan. Consequently, a thermal history of the Lublin Basin is different from that in the Podlasie and Baltic Basins, but similar to other sections of the Variscan foreland, characterised by maximum burial at the end of Carboniferous. The Mesozoic thermal history was characterised by gradual cooling from peak temperatures at the transition from Triassic to Jurassic due to decreasing heat flow. Burial caused maximum paleotemperatures in the SW part of the study area, where the EEP was covered by an extensive sedimentary pile. However, farther NE, due to low temperatures caused by shallow burial, the impact of fluids can be detected by VR, illite/smectite and thermochronological data.
Basin inversion: Reactivated rift structures in the Ligurian Sea
revealed by OBS
Authors: Thorwart Martin , Dannowski Anke , Grevemeyer Ingo , Lange Dietrich , Kopp Heidrun , Petersen Florian , Crawford Wayne , Paul Anne ,   the AlpArray Working Group
Published: February 2021

Abstract. The northern margin of the Ligurian Basin shows notable seismicity at the Alpine front, including frequent magnitude 4 events. Seismicity decreases offshore towards the Basin centre and Corsica, revealing a diffuse distribution of low magnitude earthquakes. We analyse data of the amphibious AlpArray seismic network with focus on the offshore component, the AlpArray OBS network, consisting of 24 broadband ocean bottom seismometers deployed for eight months, to reveal the seismicity and depth distribution of micro-earthquakes beneath the Ligurian Sea. Two clusters occurred between ~10 km to ~16 km depth below sea surface, within the lower crust and uppermost mantle. Thrust faulting focal mechanisms indicate compression and an inversion of the Ligurian Basin, which is an abandoned Oligocene rift basin. The Basin inversion is suggested to be related to the Africa-Europe plate convergence. The locations and focal mechanisms of seismicity suggest reactivation of pre-existing rift structures. Slightly different striking directions of faults in the basin centre compared to faults further east and hence away from the abandoned rift may mimic the counter-clockwise rotation of the Corsica-Sardinia block during ~20–16 Ma. The observed cluster events support the hypothesis of strengthening of crust and uppermost mantle during rifting related extension and thinning of continental crust.
Controls on heterotrophic soil respiration and carbon cycling in
geochemically distinct African tropical forest soils
Authors: Bukombe Benjamin , Fiener Peter , Hoyt Alison M. , Doetterl Sebastian
Published: February 2021

Abstract. Heterotrophic soil respiration is an important component of the global terrestrial carbon (C) cycle, driven by environmental factors acting from local to continental scales. For tropical Africa, these factors and their interactions remain largely unknown. Here, using samples collected along strong topographic and geochemical gradients in the East African Rift Valley, we study how soil chemistry and soil fertility, derived from the geochemical composition of soil parent material, can drive soil respiration even after many millennia of weathering and soil development. To address the drivers of soil respiration, we incubated soils from three regions with contrasting geochemistry (mafic, felsic, and mixed sedimentary) sampled along slope gradients. For three soil depths, we measured the potential maximum heterotrophic respiration under stable environmental conditions as well as the radiocarbon content (Δ14C) of the bulk soil and respired CO2. We found that soil microbial communities were able to mineralize C from fossil as well as other poor quality C sources under laboratory conditions representative of tropical topsoils. Furthermore, despite similarities in terms of climate, vegetation, and the size of soil C stocks, soil respiration showed distinct patterns with soil depth and parent material geochemistry. The topographic origin of our samples was not a main determinant of the observed respiration rates and Δ14C. In situ, however, soil hydrological conditions likely influence soil C stability by inhibiting decomposition in valley subsoils. Our study shows that soil fertility conditions are the main determinant of C stability in tropical forest soils. Further, in the presence of organic carbon sources of poor quality or the presence of strong mineral related C stabilization, microorganisms tend to discriminate against these sources in favor of more accessible forms of soil organic matter as energy sources, resulting in a slower rate of C cycling. Our results demonstrate that even in deeply weathered tropical soils, parent material has a long-lasting effect on soil chemistry that can influence and control microbial activity, the size of subsoil C stocks, and the turnover of C in soil. Soil parent material and its lasting control on soil chemistry need to be taken into account to understand and predict C stabilization and rates of C cycling in tropical forest soils.
Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling
Authors: Guillemot Antoine , Baillet Laurent , Garambois Stéphane , Bodin Xavier , Helmstetter Agnès , Mayoraz Raphaël , Larose Eric
Published: February 2021

Abstract. Among mountainous permafrost landforms, rock glaciers are mostly
abundant in periglacial areas, as tongue-shaped heterogeneous bodies.
Passive seismic monitoring systems have the potential to provide continuous
recordings sensitive to hydro-mechanical parameters of the subsurface. Two
active rock glaciers located in the Alps (Gugla, Switzerland, and Laurichard,
France) have been instrumented with seismic networks. Here, we analyze
the spectral content of ambient noise to study the modal sensitivity of rock
glaciers, which is directly linked to the system's elastic properties. For
both sites, we succeed in tracking and monitoring resonance frequencies of
specific vibrating modes of the rock glaciers over several years. These
frequencies show a seasonal pattern characterized by higher frequencies at
the end of winters and lower frequencies in warm periods. We interpret
these variations as the effect of the seasonal freeze–thawing cycle on
elastic properties of the medium. To assess this assumption, we model both
rock glaciers in summer, using seismic velocities constrained by active
seismic acquisitions, while bedrock depth is constrained by ground-penetrating radar surveys. The variations in elastic properties occurring in
winter due to freezing were taken into account thanks to a three-phase
Biot–Gassmann poroelastic model, where the rock glacier is considered a
mixture of a solid porous matrix and pores filled by water or ice. Assuming
rock glaciers to be vibrating structures, we numerically compute the modal
response of such mechanical models by a finite-element method. The resulting
modeled resonance frequencies fit well the measured ones over seasons,
reinforcing the validity of our poroelastic approach. This seismic
monitoring allows then a better understanding of the location, intensity and
timing of freeze–thawing cycles affecting rock glaciers.
Effect of ephemeral snow cover on the active layer thermal regime and
thickness on CALM-S JGM site, James Ross Island, eastern Antarctic
Peninsula
Authors: Hrbáček Filip , Engel Zbyněk , Kňažková Michaela , Smolíková Jana
Published: February 2021

Abstract. This study aims to assess the role of ephemeral snow cover on ground thermal regime and active layer thickness in two ground temperature measurement profiles on the Circumpolar Active Layer Monitoring Network – South (CALM-S) JGM site on James Ross Island, eastern Antarctic Peninsula during the high austral summer 2018. The snowstorm of 13–14 January created a snowpack of recorded depth of up to 38 cm. The snowpack remained on the study site for 12 days in total and covered 46 % of its area six days after the snowfall. It directly affected ground thermal regime in a study profile AWS-JGM while the AWS-CALM profile was snow-free. The thermal insulation effect of snow cover led to a decrease of mean summer ground temperatures on AWS-JGM by ca 0.5–0.7 °C. Summer thawing degree days at a depth of 5 cm decreased by ca 10 % and active layer was ca 5–10 cm thinner when compared to previous snow-free summer seasons. Surveying by ground penetrating radar revealed a general active layer thinning of up to 20 % in those parts of the CALM-S which were covered by snow of > 20 cm depth for at least six days.
Tropospheric eddy feedback to different stratospheric conditions in idealised baroclinic life cycles
Authors: Rupp Philip , Birner Thomas
Published: February 2021

Abstract. A pronounced signature of stratosphere–troposphere coupling is a robust negative anomaly in the surface northern annular mode (NAM) following sudden stratospheric warming (SSW) events, consistent with an equatorward shift in the tropospheric jet. It has previously been pointed out that tropospheric synoptic-scale eddy feedbacks, mainly induced by anomalies in the lowermost extratropical stratosphere, play an important role in creating this surface NAM signal. Here, we use the basic set-up of idealised baroclinic life cycles to investigate the influence of stratospheric conditions on the behaviour of tropospheric synoptic-scale eddies. Particular attention is given to the enhancement of the tropospheric eddy response by surface friction and the sensitivity to wind anomalies in the lower stratosphere. We find systems that include a tropospheric jet only (modelling post-SSW conditions) to be characterised by an equatorward shift in the tropospheric jet in the final state of the life cycle, relative to systems that include a representation of the polar vortex (mimicking more undisturbed stratospheric wintertime conditions), consistent with the observed NAM response after SSWs. The corresponding relative surface NAM signal is increased if the system includes surface friction, presumably due to a direct coupling of the eddy field at tropopause level to the surface winds. We further show that the jet shift signal observed in our experiments is mainly caused by changes in the zonal wind structure of the lowermost stratosphere, while changes in the wind structure of the middle and upper stratosphere have almost no influence.
Set-point optimization in wind farms to mitigate effects of flow blockage induced by atmospheric gravity waves
Authors: Lanzilao Luca , Meyers Johan
Published: February 2021

Abstract. Recently, it has been shown that flow blockage in large wind farms may lift up the top of the boundary layer, thereby triggering atmospheric gravity waves in the inversion layer and in the free atmosphere. These waves impose significant pressure gradients in the boundary layer, causing detrimental consequences in terms of a farm's efficiency. In the current study, we investigate the idea of controlling the wind farm in order to mitigate the efficiency drop due to wind-farm-induced gravity waves and blockage. The analysis is performed using a fast boundary layer model which divides the vertical structure of the atmosphere into three layers. The wind-farm drag force is applied over the whole wind-farm area in the lowest layer and is directly proportional to the wind-farm thrust set-point distribution. We implement an optimization model in order to derive the thrust-coefficient distribution, which maximizes the wind-farm energy extraction. We use a continuous adjoint method to efficiently compute gradients for the optimization algorithm, which is based on a quasi-Newton method. Power gains are evaluated with respect to a reference thrust-coefficient distribution based on the Betz–Joukowsky set point. We consider thrust coefficients that can change in space, as well as in time, i.e. considering time-periodic signals. However, in all our optimization results, we find that optimal thrust-coefficient distributions are steady; any time-periodic distribution is less optimal. The (steady) optimal thrust-coefficient distribution is inversely related to the vertical displacement of the boundary layer. Hence, it assumes a sinusoidal behaviour in the streamwise direction in subcritical flow conditions, whereas it becomes a U-shaped curve when the flow is supercritical. The sensitivity of the power gain to the atmospheric state is studied using the developed optimization tool for almost 2000 different atmospheric states. Overall, power gains above 4 % were observed for 77 % of the cases with peaks up to 14 % for weakly stratified atmospheres in critical flow regimes.
Incorporation of Fluconazole and Ocimum Sanctum Oil in Soft Denture Liners to Treat Biofilms of Candida albicans Associated with Denture Stomatitis
Authors: Godil Aamir Zahid , Bhagat Diksha , Das Parijat , Kazi Ashi Ilyas , Dugal Ramandeep , Satpute Surekha
Published: February 2021

Purpose: To investigate the In Vitro activity of incorporated antifungal agents like Fluconazole and Ocimum sanctum oil (Tulsi) in the denture soft liners to reduce the risks associated with the biofilms of Candida albicans.Materials and Methods: In the current study, the minimum inhibitory concentration (MIC) of two antifungal agents namely Fluconazole and O. sanctum (Tulsi oil) against C. albicans (ATCC 10231) was evaluated to examine their effect in reducing the count of candida and its biofilms. Analysis of physical properties such as surface roughness and hardness of soft denture liners (test and control) were also performed. The effect of both antifungal agents was also observed on cell morphology of candida cells using scanning electron microscopy (SEM).Results: Studies confirmed MIC value for fluconazole and O. sanctum oil as 600 and 400 µg/ml respectively. Surface hardness and roughness of soft denture material (test) remained unaltered. Finally, SEM studies also proved the effectiveness of incorporated antifungal agents on the cell morphology of C. albicans at their respective MIC values.Conclusions: This approach allows the prolonged drug release in the oral cavity which simultaneously treats the injured denture bearing tissues and also the infection, biofilms of candida without compromising on their physical properties. These studies are significant and have tremendous medicinal and therapeutic relevance.
Central Place Theory and the Emergence of Floating Markets in the Mekong Delta of Vietnam
Authors: NGO Thi Phuong Lan
Published: February 2021

This research re-examines Walter Christaller (1933)’s central place theory paradigm to explain the emergence of a network of floating markets in the Mekong River Delta’s dense network of rivers and canals. Because road transportation is underdeveloped, floating markets play an important role for local people. They provide access to transportation and opportunities to trade, especially for the region’s diverse agricultural products. Furthermore, the floating markets support inland infrastructures. This research challenges Christaller’s (1933) assumptions about population thresholds and geographical range, and Mulligan et al.’s (2012) understanding of interaction among consumer choices, company aggregation and functional hierarchy. It finds that riverine traders employ flexible transaction strategies.
The role of local bodies
Authors: Fowler M.
Published: February 2021

Responsible local authorities throughout New Zealand anticipate a recurrence of earthquakes which experience and historical records have proven. Some have declared themselves bound by the M.C. Act, Clause 301A, which requires earthquake risk buildings demolished or upgraded to at least a minimal acceptable standard. All are bound to require new buildings to conform to present earthquake resistant codes, and most have established a Civil Defence organisation. None are programmed to operate upon the advice of the anticipated time of a predicted earthquake. Yet the application of the science of Earthquake Prediction will require not only the total co-operation of Central Government, but even more importantly that of Local Government to align the population to the worthwhileness  of heeding both false and true predictions.