bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical frequency dissemination via fiber networks: The Clock Network Services (CLONETS) project and potential applications in the geosciences
Authors: Kusche Juergen ,   CLOck NETwork Services - Design Study (CLONETS DS) Team
Published: March 2021

Precise measurement of time and frequency has been instrumental in the development of modern geosciences. It has enabled us to quantify many observations, including plate motion, the variations of Earth rotation, and modern-day sea level rise.

Over the past decade, European National Metrology Institutes (NMIs), together with National Research and Education Networks (NRENs) and partners from universities and research institutes have pioneered the dissemination of ultra-stable optical frequency and timing signals via optical fibers. Initially started as proof-of-concept experiments, this technology has matured to aim for a paradigm change: making precise time and frequency signals available to the wider scientific community and thereby enabling new research avenues.

The CLOck NETwork Services Design Study (CLONETS-DS) is a research and innovation action intended to facilitate the vision of a sustainable, pan-European optical fiber network for precise time and frequency reference dissemination.

Here, we will present the envisioned technology, its performance parameters, and discuss potential applications, requirements and limitations for geophysical applications, for example in geodesy (chronometric levelling, gravity field observation), seismology, and very-long-baseline interferometry (VLBI).
Simulation of a subtropical cyclone using the HARMONIE-AROME model
Authors: Sastre Mariano , Díaz Fernández Javier , Quitián Hernández Lara , Bolgiani Pedro , Santos-Muñoz Daniel , González-Alemán Juan Jesús , Valero Francisco , Sebastián-Martín Luis Ignacio , López Laura , Farrán José Ignacio , Martín María Luisa
Published: March 2021

According to their thermal structure and dynamics, different types of tropospheric cyclones can be defined. Subtropical cyclones (STC) are low pressure systems that share tropical and extratropical characteristics, having a hybrid thermal structure. The impacts of this kind of cyclones are typically like the ones due to tropical storms or even hurricanes, leading to widespread social damage and significant economic losses. Moreover, because of its complex dynamics and rapid intensification, these systems remain a phenomenon of interest, as well as a challenge in terms of prediction. Consequently, effective numerical model simulations become the key tool in order to reliably forecast these extreme events. In this study, a STC event, which occurred in October 2014 nearby the Canary Islands, is assessed by means of the high-resolution numerical weather prediction model HARMONIE-AROME, which is currently operated at 2.5 km grid resolution. This model was developed in the framework of the collaboration of the ten European National Meteorological Services that belong to the HIRLAM international research consortium, together with the sixteen countries that comprise the ALADIN consortium. To evaluate the performance of the simulation, airport observations and sounding data in the vicinity of the STC are considered for local analyses, and satellite images are used to assess the global cloudiness arrangement.
Science-policy integration for sea-level adaptation in the United Arab Emirates
Authors: Melville-Rea Hannah , Eayrs Clare , Anwahi Nasser , Holland Denise , Holland David
Published: March 2021

The United Arab Emirates (UAE), a young oil-rich nation, may not seem a likely candidate to lead cross-sectoral exchanges for climate research. Yet, the UAE’s long-term policy horizon, financial capital, and vision for a sustainable knowledge-based economy situates it as a potential leader for climate science. 

At the center of its pivot towards climate research is a growing concern for sea-level rise and natural hazards. Over 85% of the population and more than 90% of the nation’s infrastructure is within a few meters of present-day sea-level. With its low-lying and shallow-sloping geography (about 35cm per km), this high-value coastline with Dubai and Abu Dhabi is particularly vulnerable to sea-level rise. Meanwhile, limited regional research and data scarcity creates deep uncertainty for sea-level projections. In the wake of COVID-19, the UAE is doubling down on government-led coordination for community health and security.

We set out a roadmap for the UAE to capitalize on its strengths to create usable and relevant sea-level projections for the region. With a newly established Climate Change Research Network, the UAE government is beginning to draw together academia, industry and policy makers for "furthering effective data collection and management, and advancing policy-relevant research on climate impacts and adaptation". By consolidating ideas from the science community within the UAE, we identify existing barriers to data gathering, information sharing, science-policy communication and access to funding. Our paper proposes pathways forward for the UAE to integrate sea-level science with coastal development and form best practices that can be scaled across the region.
Probabilistic Streamflow forecast for Narmada River Basin
Authors: Vegad Urmin , Mishra Vimal
Published: March 2021

Ensemble Streamflow Prediction (ESP) is a widely used method in forecasting streamflow, particularly for extremely low or high flows. However, the incorporation of reservoir operations in using ensemble streamflow prediction has not been investigated till yet. We calibrated Variable Infiltration Capacity (VIC) model for daily streamflow for Narmada river basin at four stations (Sandia, Handia, Mandleshwar and Garudeshwar) considering the effect of four reservoirs (Bargi, Tawa, Indira Sagar and Sardar Sarovar). The model is well-calibrated for the selected river basin (R2>0.55) at all locations. Further, routing of streamflow is done considering the reservoir storage dynamics and operating rules. Input data for ensemble prediction is taken from all 16 members of the Extended Range Forecast System (ERFS) developed by Indian Institute of Tropical Meteorology (IITM) and implemented by India Meteorological Department (IMD). Post-processing of the results gave us probabilities of uncertainties associated with streamflow prediction using ERFS members. This study provides key information in predictions of streamflow by incorporating the reservoirs based on the ERFS ensemble members, which can be used to effectively mitigate life and property losses associated with extreme flows in rivers.
Computer vision model for detecting block falls at the martian north polar region.
Authors: Martynchuk Oleksii , Fanara Lida , Hauber Ernst , Oberst Juergen , Gwinner Klaus
Published: March 2021

Dynamic changes of Martian north polar scarps present a valuable insight into the planet's natural climate cycles (Byrne, 2009; Head et al., 2003)1,2. Annual avalanches and block falls are amongst the most noticeable surface processes that can be directly linked with the extent of the latter dynamics (Fanara et al, 2020)3. New remote sensing approaches based on machine learning allow us to make precise records of the aforementioned mass wasting activity by automatically extracting and analyzing bulk information obtained from satellite imagery.  Previous studies have concluded that a Support Vector Machine (SVM) classifier trained using Histograms of Oriented Gradients (HOG) can be used to efficiently detect block falls, even against backgrounds with increased complexity (Fanara et al., 2020)4. We hypothesise that this pretrained model can now be utilized to generate an extended dataset of labelled image data, sufficient in size to opt for a deep learning approach. On top of improving the detection model we also attempt to address the image co-registration protocol. Prior research has suggested this to be a substantial bottleneck, which reduces the amounts of suitable images. We plan to overcome these limitations either by extending our model to include multi-sensor data, or by deploying improved methods designed for exclusively optical data (e.g.  COSI-CORR software (Ayoub, Leprince and Avouac, 2017)5).  The resulting algorithm should be a robust solution capable of improving on the already established baselines of 75.1% and 8.5% for TPR and FDR respectively (Fanara et al., 2020)4. The NPLD is our primary area of interest due to it’s high levels of activity and good satellite image density, yet we also plan to apply our pipeline to different surface changes and Martian regions as well as on other celestial objects.

 

1. Head, J.W., Mustard, J.F., Kreslavsky, M.A., Milliken, R.E., Marchant, D.R., 2003. Recent ice ages on Mars. Nature 426, 797–802

2. Byrne, S., 2009. The polar deposits of Mars. Annu. Rev. Earth Planet. Sci. 37, 535–560.

3. Fanara, K. Gwinner, E. Hauber, J. Oberst, Present-day erosion rate of north polar scarps on Mars due to active mass wasting; Icarus,Volume 342, 2020; 113434, ISSN 0019-1035.

4. Fanara, K. Gwinner, E. Hauber, J. Oberst, Automated detection of block falls in the north polar region of Mars; Planetary and Space Science, Volume 180, 2020; 104733, ISSN 0032-0633.

5. Ayoub, F.; Leprince, S.; Avouac, J.-P. User’s Guide to COSI-CORR Co-registration of Optically Sensed Images and Correlation; California Institute of Technology: Pasadena, CA, USA, 2009; pp. 1–49.
Elucidating sources and pathways of dissolved organic carbon in a small, forested catchment – A qualitative assessment of stream, soil and shallow groundwater
Authors: Blaurock Katharina , Garthen Phil , Gilfedder Benjamin S. , Fleckenstein Jan H. , Peiffer Stefan , Hopp Luisa
Published: March 2021

Dissolved organic carbon (DOC) constitutes the biggest portion of carbon that is exported from soils. During the last decades, widespread increases in DOC concentrations of surface waters have been observed, affecting ecosystem functioning and drinking water treatment. However, the hydrological controls on DOC mobilization are still not completely understood.

We sampled two different topographical positions within a headwater catchment in the Bavarian Forest National Park: at a steep hillslope (880 m.a.s.l.) and in a flat and wide riparian zone (770 m.a.s.l.). By using piezometers, pore water samplers (peepers) and in-stream spectrometric devices we measured DOC concentrations as well as DOC absorbance (A254/A365 and SUVA254) and fluorescence characteristics (fluorescence and freshness indices) in soil water, shallow ground water and stream water in order to gain insights into the DOC source areas during base-flow and during precipitation events.

High DOC concentrations (up to 80 mg L-1) were found in soil water from cascading sequences of small ponds in the flat downstream part of the catchment that fill up temporarily. The increase of in-stream DOC concentrations during events was accompanied by changing DOC characteristics at both locations, for example increasing freshness index values. As the freshness index values were approaching the values found in the DOC-rich ponds in the riparian zone, these ponds seem to be important DOC sources during events. Our preliminary results point to a change of flow pathways during events.
First Results from Solar Orbiter’s Energetic Particle Detector
Authors: Rodriguez-Pacheco Javier ,   EPD Team
Published: March 2021

In this presentation, we will show the first measurements performed by EPD since the end of the commissioning phase until the latest results obtained. During these months EPD has been scanning the inner heliosphere at different heliocentric distances and heliolongitues allowing - together with other spacecraft - to investigate the spatio-temporal behavior of the particle populations in the inner heliosphere during solar minimum conditions. Solar Orbiter was launched from Cape Canaveral on February 10th, 2020, thus beginning the journey to its encounter with the Sun. Solar Orbiter carries ten scientific instruments, six remote sensing and four in situ, that will allow the mission main goal: how the Sun creates and controls the heliosphere. Among the in situ instruments, the Energetic Particle Detector (EPD) measures electrons, protons and heavy ions with high temporal resolution over a wide energy range, from suprathermal energies up to several hundreds of MeV/nucleon.
Tracking the South Pacific convergence zone variability and recent acidification reconstructed from tropical corals
Authors: Todorović Sara , C. Wu Henry , Linsley Braddock , Dissard Delphine , Kuhnert Henning , Benthien Albert , Richter Klaus-Uwe , Raitzsch Markus , Bijma Jelle
Published: March 2021

Massive tropical corals represent one of the most important natural archives of modern climate change. Coral based reconstructions give us the possibility to extend the instrumental oceanographic records and observe hydrographic variability on seasonal to interdecadal scales in tropical oceans. South Pacific convergence zone (SPCZ) variability, Interdecadal Pacific Oscillation (IPO) and El Niño-Southern Oscillation (ENSO) events are major drivers of global climate and may exert control on regional CO2 absorption, outgassing and pH variability.

Porites sp. corals from Tonga and Rotuma (Fijian dependency) are being analyzed for multi-proxy (e.g. Sr/Ca, δ18O, δ13C, δ11B, B/Ca) reconstructions of sea surface temperature and salinity (SST, SSS) and carbonate chemistry, on a monthly to annual resolution. Preliminary data of the Rotuma Porites sp. coral shows δ18O has been decreasing by 0.004 ‰ per year at the end of the 20th century, suggesting freshening and/or warming of the surface water. In the same period, we observe a δ13C decrease of 0.017 ‰ per year in-line with the anthropogenic CO2 driven Suess effect. Initial results of the δ11B Tonga Porites sp. show high interannual variability, and a strong trend of decrease of -0.0626 ‰ per year in the last five decades of the record (1949-2004) suggesting acidification. The results are in agreement with published coral-based reconstructions from the region.

When completed, the new records will facilitate exploring the effects of modern anthropogenic influence on ocean carbonate system and pH variation, and the relationship between them and interannual and decadal-interdecadal climatic fluctuations.
Dynamics of collective action to conserve a large common-pool resource
Authors: Ringsmuth Andrew , Andersson David , Bratsberg Sigrid , de Wijn Astrid
Published: March 2021

A pressing challenge in the Anthropocene is sustainable and just management of large-scale common-pool resources (CPRs) including the atmosphere, biodiversity and public services. This poses a difficult collective action problem because such resources may not show signs that usage restraint is needed until tragedy is almost inevitable. To solve this problem, a sufficient level of cooperation with a pro-conservation behavioural norm must be achieved, within the prevailing sociopolitical environment, in time for the action taken to be effective. In this work, we investigate the transient, nonequilibrium dynamics of behavioural change in an agent-based model on structured networks that are also exposed to a global external influence. Our model combines elements of rational choice theory with psychology-based opinion dynamics to reflect that individuals who promote collective action to conserve a large CPR are rationally motivated and also face psychosocial constraints. We find that social polarisation emerges naturally, even without assuming bounded confidence, but that for rationally motivated agents, it is temporary. The speed of convergence to a final consensus is controlled by the rate at which the polarised clusters are dissolved. This depends strongly on the combination of external influences and the network topology. Both high connectivity and a favourable environment are needed to rapidly obtain final consensus. Our findings expand the evidence that designing systems to encourage constructive engagement between disagreeing groups could be a powerful promoter of large-scale collective action.
Promoting Sustainable Housing with Fundamental Shift beyond Net-Zero and Green Building
Authors: Bharali Biswadeep , Rajbanshi Basanta , Yangzom Tashi , Dahal Himal , Rai Muden , Sewa Bhuwan
Published: March 2021

Net positive buildings can be the solution to slow down climate change. Old buildings and minimum code buildings only strive for structural protection, but they do not play a part in climate change mitigation solutions. In this study, we try to demonstrate net positive buildings' contribution in reducing global greenhouse gas emissions by taking the Guwahati region (India) as a study area. First, we developed a north-facing 3-B-H-K residential building plan with a two-car garage using the most commonly used construction materials in the region as a base case scenario. The weather data (like Temperature, Relative Humidity, and Airspeed) for 2020 is collected. With these inputs, the annual total energy consumption for the present climatic condition is simulated using the Ecotect tool. Then three different scenarios (modification of walls, modification of roofs, and floor modification) were created. The energy interpretation for the overall modified case was done and compared with the base case scenario. The result indicates that the total annual energy consumption for the overall modified case was reduced by 70% as compared to the base case model. The remaining 30% of the energy usage was supplied by renewable energy sources using photovoltaic cells to make net energy consumption zero.  These findings suggest that the old building can be renovated and modified to act as a mitigation solution to climate change.
Tsunami Hazard of the Caspian Sea
Authors: Medvedeva Alisa , Medvedev Igor
Published: March 2021

A regional model of tsunami seismic sources in the zone of the Main Caucasian thrust has been developed. The parameters of probable models of seismic sources and their uncertainties were estimated based on the available data on historical earthquakes and active faults of the region. The scenario modeling technique was used for the tsunami zoning of the Caspian Sea coast. The time period covered by the model catalog of earthquakes used to calculate the generation and propagation of tsunamis is about 20 000 years, which is longer than the recurrence periods of the strongest possible earthquakes. The recurrence graphs of the calculated maximum tsunami heights for the entire sea coast were plotted. On their basis, the maximum heights of tsunami waves on the coast were calculated with recurrence periods of 250, 500, 1000 and 5000 years and the corresponding survey maps of the tsunami zoning of the Caspian Sea were created. The algorithm for calculating the tsunami run-up on the coast is improved, taking into account the residual (postseismic) displacements of the bottom and land relief. Estimates of tsunami hazard for the coast near the city of Kaspiysk were carried out: within the framework of the deterministic approach, the maximum wave heights and run-up distance were calculated. It is shown that the deterministic approach slightly overestimates the maximum heights of tsunami waves with certain return periods. It is shown that changes in the mean sea level can affect the features of the propagation of tsunami waves in the Caspian Sea. Thus, at an average sea level of -25-26 m, the Kara-Bogaz-Gol Bay is linked with the entire sea through a narrow strait. It leads to the propagation of tsunami waves into the water area of the bay and a decrease in wave height on the eastern coast of the sea. When the mean sea level decreases below -27 m, the positive depths in the strait disappear and water exchange through the strait stops, and the wave height in this part of the sea increases.
The low-energy ion event on 2020 June 19 measured by Solar Orbiter
Authors: Aran Angels , Pacheco Daniel , Laurenza Monica , Wijsen Nicolas , Samara Evangelia , Lario David , Balmaceda Laura , von Forstner Johan L. Freiherr , Benella Simone , Rodriguez Luciano , Gómez-Herrero Raúl ,   The low-energy ion event on 2020 June 19 study Team
Published: March 2021

Shortly after reaching the first perihelion, the Energetic Particle Detector (EPD) onboard Solar Orbiter measured a low-energy (<1 MeV/nuc) ion event whose duration varied with the energy of the particles. The increase above pre-event intensity levels was detected early on June 19 for ions in the energy range from ~50 keV to ~1 MeV and lasted up to ~12:00 UT on June 20. In the energy range from ~10 keV to < 40 keV, the ion event spanned from June 18 to 21. This latter low-energy ion intensity enhancement coincided with a two-step Forbush decrease (FD) as displayed in the EPD > 17 MeV/nuc ion measurements. On the other hand, no electron increases were detected. As seen from 1 au, there is no clear evidence of solar activity from the visible disk that could be associated with the origin of this ion event. We hypothesize about the origin of this event as due to either a possible solar eruption occurring behind the visible part of the Sun or to an interplanetary spatial structure. We use interplanetary magnetic field data from the Solar Orbiter Magnetometer (MAG), solar wind electron density derived from measurements of the Solar Orbiter Radio and Plasma Waves (RPW) instrument to specify the in-situ solar wind conditions where the ion event was observed. In addition, we use solar wind plasma measurements from the Solar Orbiter Solar Wind Analyser (SWA) suite gathered during the following solar rotation, for comparison purposes. In order to seek for possible associated solar sources, we use images from the Extreme Ultraviolet Imager (EUI) instrument onboard Solar Orbiter. Together with the lack of electron observations and Type III radio bursts, the simultaneous response of the ion intensity-time profiles at various energies indicates an interplanetary source for the particles. The two-step FD shape observed during this event suggests that the first step early on June 18 was due to a transient structure, whereas the second step on June 19, together with the ~50 –1000 keV/nuc ion enhancement, was due to a solar wind stream interaction region. The observation of a similar FD in the next solar rotation favours this interpretation, although a more complex structure cannot be discarded due to the lack of concurrent solar wind temperature and velocity observations.

Different parts of this research have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0) and grant agreement No 01004159 (SERPENTINE).
Environmental benefits of traditional irrigation ditches in the Sierra Nevada (Spain) ecosystem by analysing the spatial-temporal evolution of NDVI on different time scales
Authors: Aparicio Javier , Pimentel Rafael , Polo María José
Published: March 2021

In Mediterranean mountain regions, traditional irrigation systems still persist in areas where the  modernization approaches do not succeed in being operational. It is common that these systems alter the soil uses, vegetation distribution and hydrological natural regime. 

This is the case of the extensive network of irrigation ditches in the Sierra Nevada Mountain Range in southeastern Spain (an UNESCO  Reserve of the Biosphere, with areas as Natural and National Park), which originated in Muslim times, and is still operational in some areas. These ditches have contributed to maintaining local agricultural systems and populations in basins dominated by snow conditions, and they constitute a traditional regulation of water resources in the area. The network is made up of two types of irrigation ditches: “careo” and irrigation ditches. The first, the "careo", collects the meltwater and infiltrates it along its course, maintaining a high level of soil moisture and favouring deep percolation volumes that can be later consumed by the population through springs and natural fountains. The second, the irrigation ones, are used to transport water from the natural sources to the agricultural plots downstream the mountain area. In 2014, several irrigation ditches were restored in the Natural Park. This is a chance to further explore and quantify the role of this network in the hydrological budget on a local basis.  

The aim of this work is to evaluate to what extent the existence of these intermittent water networks affects the evolution of the surrounding vegetation. For this, one of the restored systems,  the Barjas Ditch in the village of Cañar, with a successful water circulation along its way, was selected from the increase of the soil water content in the ditch influence area and, indirectly a differential development of vegetation. Two analyses are performed using remote sensing information. The Normalized Difference Vegetation Index, NDVI, which is a spectral index used to estimate the quantity, quality and development of vegetation that can therefore be used indirectly as an indicator of the state of soil moisture, was used as the indicator of evolution. For this purpose, a historical set of LandSat satellite images  (TM, ETM+ and OLI) has been used. On the one hand, a global analysis on the whole mountainous range was carried out, comparing NDVI patterns in areas affected and non-affected by the ditches. On the other hand, the restored  Barjas ditch is used to assess vegetation changes before and after the restoration.
Composition of the Fe-Mn nodules and associated microbial communities of the Kara Sea, Arctic Ocean
Authors: Shulga Natalia , Abramov Sergej , Gavrilov Sergej , Ryazantsev Konstantin
Published: March 2021

This work is based on ferromanganese nodules, crusts and underlying sediments collected from the different parts of the Kara Sea shelf (Arctic). The geochemistry, morphology and organic matter content of nodules, crusts and sediments were determined with ICP-MS, SEM-EDS and GC/MS. The associated microbial communities were identified with 16S rRNA (gene) sequencing. Nodules from the Kara Sea shelf significantly differ from their more common abyssal analogues. These shelf nodules have an irregular tabular morphology and relatively low abundances of Mn (up to 19 wt.%), Fe (up to 24 wt.%), other trace metals and the REYs. The Kara Sea nodules show concentric layering that is also typical of deep-sea diagenetic nodules. Samples subdivided into two groups: Mn-rich (Mn/Fe = 0.35 on av.) and Fe-rich (Mn/Fe = 1.65 on av.). The negative Ce anomaly suggests a diagenetic origin of the nodules and crusts. The input of organic matter to the ore deposits in the study area has three main sources (according to n-alkane composition): 1) marine (planctonogenic); 2) low-transformed terrestrial organic matter derived from river run-off; 3) microbial-derived source. Microbial communities of nodules and crusts are substantially different from benthic microbial communities in sediments. They dominated by taxa involved in N cycle, particularly responsible for denitrification (Cyclobacteriaceae and Kiloniellaceae), nitrification (“Candidatus Nitrosopumilus” and Nitrosomonas), comammox (Nitrospira) and anammox (Nitrosococcaceae) [1]. Dissimilatory Fe(III)- and Mn(IV)-reducing Geopsychrobacter was identified in Fe-rich ore samples. This taxon can be involved in Fe(III)- and Mn(IV)-dependent anaerobic oxidation of methane [2]. In contrast, microbial community of underlying sediments dominated by sulfate-reducing bacteria (SRB). Some of the identified SRB (e.g. Desulfobulbaceae and Desulfosarcinaceae) are able to form syntrophic associations with anaerobic methanotrophic archaea [3]. Identified n-alkanes can be oxidized by Anaerolineaceae growing in syntrophic association with methanogens. Furthermore, we revealed that manganese nodules and crusts can be used potentially as important electron acceptors for oxidation of organic compounds by Geopsychrobacter, Desulfuromonadales and Colwellia. Applied multi-disciplinary approach to the study of the Fe-Mn nodules and crusts will help to determine their contribution in formation of unique biogeochemical environments in the Kara Sea.

This work was supported by the Russian Science Foundation (grant 19-77-00107).
Analysis of fishways in the Middle and Lower Jinsha River Basin (China)
Authors: Tong Siqi , Wieprecht Silke , Schletterer Martin
Published: March 2021

This study was carried out in the middle and lower reaches of the Jinsha River in southwest China, which represents the upper Yangtze River. Hydraulic structures (14 cascade hydropower stations) are planned and/or constructed in this system, which is considered as largest hydropower base. We aim to summarize appropriate measures to restore the riverine continuum in the middle and lower reaches of the Jinsha River, where high-head cascade hydropower dams are located or planned.

We distributed a questionnaire to Chinese researchers in the related fields (scientists, hydropower operators and NGOs in China, n = 60). According to the responses, fishways, fish lift, fish lock, trap-and-truck system as well as fish hatcheries (artificial breeding) are recognized to ensure passing respectively preserving fish in the Jinsha River basin.

A longitudinal connectivity assessment of the study area revealed a severely disturbed continuity status. Based on the biological analyses of the demands of the target fish species and review of fish pass technologies, a vertical-slot fishway is proposed.

Considering the dam heights and the geographical conditions, it is recommended to combine the vertical-slot fishway with these alternatives to achieve a higher efficiency in passing fish as well as to recover the river continuity towards regional sustainable development.
Phosphorus critical source areas identification in an agricultural watershed of Three Gorges Reservoir Area, China
Authors: Zhou Yiwen , Li Zhaoxia
Published: March 2021

Agricultural non-point sources (ANPS) pollution are considered to pose risks to water quality in Three Gorges Reservoir Areas (TGRA), especially when those pollution source comes from the hydrologically sensitive areas (HSAs) that generate surface runoff pathways. Therefore, it is necessary to identify the critical source areas (CSAs) or the sensitive regions of pollutants from agricultural lands in order to control and mitigate ANPS pollution effectively. In this study, an improved method integrating the Phosphorus Index (PI) and the Soil Topographic Index (STI) was applied to predict the risk of phosphorus loss and delineate the CSAs of phosphorus in a typical agricultural watershed in TGRA, China. The results showed that using a STI threshold value of 8.5, the HSA was identified 22.08% of watershed areas. The intersection of above two parts account 5.47% of the total watershed, compared with 24.41% of watershed areas based on an existing approach that uses just one criterion. As the results showed , the CSAs of phosphorus loss were mainly located near streams, with high or relatively high soil phosphorus contents or phosphorus fertilizer, or intense soil erosion are observed. The calculated results are in good agreement with the actual situation. Since the approach is based on GIS, and is a relatively simple application uses readily available geospatial data, therefore the technic could be used to improve cost-effectiveness and provide a useful screening tool for water resource managers responsible for identifying and remediating critical NPS source areas. 
Climate Land Energy Water nexus models reviewed across scales: progress, gaps and best accessibility practices
Authors: Vinca Adriano , Riahi Keywan , Rowe Andrew , Djilali Ned
Published: March 2021

Approaches that integrate feedbacks between climate, land, energy and water (CLEW) have increasingly advanced and have become more complex. Such so called nexus approaches have already been useful in quantitatively assessing strategies under resource scarcity, planning infrastructure for achieving the Sustainable Development Goals or assessing cross-sectoral climate change impacts. However, most of the models and frameworks do often miss some important inter-linkages that could actually be addressed by using newest models. The reason for such negligence is often technical and practical, as many of the newly developed and open-source frameworks are not yet widespread. We review and present these models so that decision maker needing tools for analysis could identify what is best for their needs. Particular attention is given to model usability, accessibility, longevity and community support. At the same time we discuss research gaps, and room for improvement for next development of the models from a scientific point of view. We explore at different scales where and why some nexus interaction are most relevant. We find that both very small scale and global model tend to neglect some CLEW interaction, but for different reasons. The first rarely include climate impacts, which are often marginal at local level. While the latter mostly lack pieces because of the complexity of large full CLEW system at the global level.
The vertical structure and variability of the meso-scale motion field in the trades
Authors: George Geet , Stevens Bjorn , Bony Sandrine , Vogel Raphaela
Published: March 2021

We use measurements from the Elucidating the role of clouds-circulation coupling in climate (EUREC4A) campaign to characterise the variability in the meso-scale divergence and vertical motion (pressure velocity, 𝜔) ranging across time-scales from a few hours to a month (the entire campaign period from 19th January - 15th February, 2020). The area-averaged divergence is estimated using measurements of horizontal winds from dropsondes launched in a circular flight path (~200 km diameter), something that was carried out extensively during EUREC4A – 85 circles over 19 flight-days in the North Atlantic trade-wind region.

From these estimates, we characterise the vertical structure and variability of divergence and 𝜔 in the trades. We find that 𝜔 above the sub-cloud layer is quite consistent vertically when averaged over long periods. The value stays around 1-1.5 hPa/h, which agrees well with the roughly 1.5 K/day cooling rate of the trades. However, significant intra- and inter-day variability can be found between 𝜔 profiles, in terms of the magnitudes, ranging from -7 hPa/h to 6 hPa/h as well as in terms of the vertical structure of these profiles. Daily mean sub-cloud layer divergence varies significantly from that of the cloud-layer in magnitude, and for most flight days, we also observe a sign change between the two. Changes in the vertical structure over different days suggest that a local maximum of either divergence or convergence is usually seen near the inversion layer. Our findings can provide insight into how the atmospheric state varies over short time-scales, as well as their impact on cloudiness, thus providing clues about a predominantly important question in climate science — the clouds-circulation coupling.
Modelling 1-D quasi-static potential structures at Jupiter
Authors: Constable Dave , Ray Licia , Badman Sarah , Arridge Chris , Gunell Herbert
Published: March 2021

Quasi-static potentials have long thought to be one of the significant drivers of the main ultraviolet emission associated with Jupiter’s auroral oval. The magnetic field lines connecting to the auroral zone extend into Jupiter’s middle magnetosphere, at radii of 20RJ – 50 RJ. Such quasi-static potential structures are capable of accelerating charged particles into the planetary ionosphere and generating aurora, with the Juno JEDI instrument observing inverted-V potential structures on the order of megavolts. However, Juno’s observation of quasi-static potentials has not been as ubiquitous as was initially theorised. Juno has observed more frequent instances of bi-directional electron beams on the same field line, indicating the presence of dynamic processes occurring at different altitudes. In addition, this suggests that quasi-static potentials may not be a significant driver for the main UV emission.

 

In this paper, we present new results from a 1-D Vlasov model of the high-latitude magnetic field lines in the Jovian mid-magnetosphere. Our model is time-dependent and features a non-uniform mesh close to the ionosphere, allowing us to examine the formation of quasi-static potential structures in the upward current region over the course of a simulation. We will also present simulations showing the collapse and reformation of these potential structures, with the collapse showing the propagation of electron beams in both directions along the modelled field line.
Characterization of Alpine peatlands based on remote sensing of vegetation and water content
Authors: Silvestri Sonia , Borgia Alessandra
Published: March 2021

Storing up to 70 kg of carbon per cubic meter, peatlands are among the most carbon-dense environments in the world. If in pristine conditions, peatlands support a number of ecosystem services as for example water retention and mitigation of droughts and floods, water purification, water availability to wildlife. Their preservation is one of the main goals of the EU policy and of other initiatives around the world.

Despite their importance, Alpine peatlands have been rarely studied and their presence is not even included in the EU maps, as for example the JRC Relative Cover of Peat Soils map, and only some sites are included in the Corine Land Cover map. The precise localization of peatland sites and the assessment of their extent is the first fundamental step for the implementation of adequate conservation policies. To this end, satellite remote sensing is the ideal instrument to provide adequate spatial resolution to detect and characterize Alpine peatlands at the regional scale. In this study, we use Sentinal-2 satellite data combined with 2m spatial resolution digital elevation model (from LiDAR data) to detect and quantify the extent of peatlands in the Trentino - Alto Adige region, an area of about 12,000 sq km located in the heart of the Italian Alpine region. Ground truth data include 71 peatlands that cover a total surface of more than 2,000 sq m. Field campaigns and lab analyses on some selected sites show that, on average, the sampled peatlands have depth of about 1m, Bulk Density of 0.128 g cm-3 and LOI of 63%, hence indicating that the organic carbon content by soil volume is high, being on average 0.04 g cm-3. Satellite data analysis allowed us to detect a large number of peatland sites with high accuracy, thus confirming the importance of Alpine peatlands as carbon stock sites for the region. Moreover, thanks to the correlation between two indices (NDVI and NDWI) we could characterize the water content of these sites, hence analyzing its seasonal variation and inferring possible future scenarios linked to climate change effects.
LESbrary: A library of large eddy simulation data for the calibration and uncertainty quantification of ocean surface boundary layer turbulence parameterizations
Authors: Wagner Gregory , Souza Andre , Hillier Adeline , Ramadhan Ali , Ferrari Raffaele
Published: March 2021

Parameterizations of turbulent mixing in the ocean surface boundary layer (OSBL) are key Earth System Model (ESM) components that modulate the communication of heat and carbon between the atmosphere and ocean interior. OSBL turbulence parameterizations are formulated in terms of unknown free parameters estimated from observational or synthetic data. In this work we describe the development and use of a synthetic dataset called the “LESbrary” generated by a large number of idealized, high-fidelity, limited-area large eddy simulations (LES) of OSBL turbulent mixing. We describe how the LESbrary design leverages a detailed understanding of OSBL conditions derived from observations and large scale models to span the range of realistically diverse physical scenarios. The result is a diverse library of well-characterized “synthetic observations” that can be readily assimilated for the calibration of realistic OSBL parameterizations in isolation from other ESM model components. We apply LESbrary data to calibrate free parameters, develop prior estimates of parameter uncertainty, and evaluate model errors in two OSBL parameterizations for use in predictive ESMs.
Development of a Fast Three-Dimensional Dynamic Radiative Transfer Solver for Numerical Weather Prediction Models 
Authors: Maier Richard , Mayer Bernhard , Emde Claudia , Voigt Aiko
Published: March 2021

The increasing resolution of numerical weather prediction models makes 3D radiative effects more and more important. These effects are usually neglected by the simple 1D independent column approximations used in most of the current models. On top of that, these 1D radiative transfer solvers are also called far less often than the model’s dynamical core.

To address these issues, we present a new „dynamic“ approach of solving 3D radiative transfer. Building upon the existing TenStream solver (Jakub and Mayer, 2015), radiation in this 3D model is not solved completely in each radiation time step, but is rather only transported to adjacent grid boxes. For every grid box, outgoing fluxes are then calculated from the incoming fluxes from the neighboring grid cells of the previous time step. This allows to reduce the computational cost of 3D radiative transfer models to that of current 1D solvers.

Here, we show first results obtained with this new solver with a special emphasis on heating rates. Furthermore, we demonstrate issues related to the dynamical treatment of radiation as well as possible solutions to these problems.

In the future, the speed of this newly developed 3D dynamic TenStream solver will be further increased by reducing the number of spectral bands used in the radiative transfer calculations with the aim to get a 3D solver that can be called even more frequently than the 1D two-stream solvers used nowadays.

Reference:
Jakub, F. and Mayer, B. (2015), A three-dimensional parallel radiative transfer model for atmospheric heating rates for use in cloud resolving models—The TenStream solver, Journal of Quantitative Spectroscopy and Radiative Transfer, Volume 163, 2015, Pages 63-71, ISSN 0022-4073, .
Multi-scale variability of surface currents in the Gulf of Tonkin derived from HF radar observations
Authors: Tran Manh Cuong , Sentchev Alexei , Nguyen Kim Cuong
Published: March 2021

The surface circulation in the Gulf of Tonkin (GoT) was analyzed using 2.5 year-long dataset from the High-Frequency radar (from April 2014 to October 2016). High temporal resolution of the measurements and large coverage from HFR dataset enable us to characterize the variability of surface circulation in the GoT in a wide range of scales: from tidal to annual scale. A number of techniques of data including rotary spectral analysis (RSA), principal component analysis (PCA), harmonic tidal analysis, coherent analysis, etc. were used to identify the dominant modes of variability. The tidal motions, accounting for approximately 62% of the total variability, revealed the dominance of diurnal components (K1 and O1) with 4 times larger magnitude than that of semi-diurnal constituent (M2). At seasonal scale, the monsoon wind plays an important role in driving the surface circulation in the GoT. This was supported by a tight correlation (0.7) between the wind stress and current velocities and by a large contribution (more than 50%) of the Ekman-driven component to the total variability of currents in the offshore area. Along the shore, large seasonal variability of circulation was highlighted. During the year, the seaward extension of the coastal current is primarily controlled by the cross-shore wind stress while the flow intensity is modulated by the Red River discharge.
Microbial functional limitations and rhizosphere priming effect in permafrost
Authors: Monteux Sylvain ,   co-authors
Published: March 2021

Considering the potential positive feedback between climate warming and the release of greenhouse gases following the increased decomposition of the organic matter stored in permafrost soils as they thaw is an important challenge for the upcoming climate change assessments. While our understanding of physico-chemical constraints on thawing permafrost SOM decomposition has vastly improved since IPCC’s fifth assessment report, biotic interactions can still be the source of large uncertainties. Here we discuss the effects of two biotic interactions in the context of thawing permafrost: rhizosphere priming effect and microbial functional limitations. Rhizosphere priming effects are still-unclear mechanisms that result in increased SOM decomposition rates in the vicinity of plant roots. We consider these effects through the PrimeSCale modeling framework, discussing its predictions and its limitations, in particular which observations and data should be acquired to further improve it. Microbial functional limitations were recently evidenced in permafrost microbial communities and consist in missing or impaired functions, likely due to strong environmental filtering over millennial time-scales. We present what this mechanism can imply in terms of permafrost soil functioning and briefly discuss what could be the next steps before its inclusions in modeling efforts.
Mathematical modeling of the process of magma formation in the Earth’s crust
Authors: Utkin Ivan , Podladchikov Yury , Melnik Oleg
Published: March 2021

One of the mechanisms of magma generation in the Earth's crust is the reaction of dehydration during subduction process. Water is released from subducting lithosphere which leads to the lowering of the melting temperature of mantle rock by hundreds of degrees.

In this work, we present a numerical study of the formation and rise of magma to the Earth's surface, considering partial melting and crystallization of rocks and chemical differentiation of magma. We develop a coupled model of the filtration flow of melt and magmatic fluid through deformable permeable rocks and a thermodynamic model of plagioclase melting based on Gibbs energy minimization approach. The formation of regions with a high melt concentration due to spontaneous focusing of filtration flow being the result of viscoplastic (de)compaction of the pore space is shown. The influence of mechanical properties of rocks and chemical composition of the system on the dynamics of the process is investigated.
Reliability of Extreme Significant Wave Height Estimation from Satellite Altimetry and In Situ Measurements in the Coastal Zone
Authors: Timmermans Ben , Shaw Andrew , Gommenginger Chrsitine
Published: March 2021

Measurements of significant wave height from satellite altimeter missions are finding increasing application in investigations of wave climate, sea state variability and trends, in particular as the means to mitigate the general sparsity of in situ measurements. However, many questions remain over the suitability of altimeter data for the representation of extreme sea states and in particular applications that examine extremes in the coastal zone. In this paper, the limitations of altimeter data to estimate coastal Hs extremes (<10 km from shore) are investigated using the European Space Agency Sea State Climate Change Initiative (CCI) L2P altimeter data v1.1 product recently released. This Sea State CCI product provides near complete global coverage and a continuous record of 28 years. It is used here together with in situ data from moored wave buoys at a number of sites around the coast of the United States. The limitations of estimating extreme values based on satellite data are quantified and linked to several factors including the impact of data corruption nearshore, the influence of coastline morphology and local wave climate dynamics and the spatio-temporal sampling achieved by altimeters. The factors combine to lead to considerable underestimation of estimated Hs 10-yr return levels. Sensitivity to these factors is evaluated at specific sites, leading to recommendations about the use of satellite data to estimate extremes and their temporal evolution in coastal environments.