bluuebunny/crossref_metadata_2025 huggingface dataset:
Spreading dynamics of central Labrador and Irminger Sea Waters
Authors: Handmann Patricia , Visbeck Martin , Biastoch Arne
Published: March 2020

Water mass formation in the Subpolar North Atlantic and successive southward export, connects high latitudes with lower latitudes, as a part of the lower Atlantic meridional overturning (AMOC) limb. The role of regional importance, in particular the respective roles of the Labrador and Irminger Sea, in this process are in debate. 

This study analyses pathways connecting the Labrador and Irminger Sea in detail, using simulated Lagrangian particle trajectories. To give further insight on interconnectivity and flow patterns we used two setups with different velocity fields, a high-resolution ocean model (VIKING20X) and a gridded Argo float displacement climatology. Both setups indicate two distinct pathways with interconnectivity on the order of 20% of the total amount of seeded particles between the Labrador Sea and Irminger Sea. One pathway is following the recirculation in the Labrador Sea along the Greenland shelf break; the other is along the Newfoundland shelf break turning to the north/northwest at the Orphan-Knoll region towards the central Irminger Sea. For the Argo based advective-diffusive particle trajectory integration a 2.5–3.5 year travel time scale was derived between the Labrador and the Irminger Sea, while the experiments with the temporarily varying high-resolution model output revealed significantly shorter spreading times of about 1.5–2 years. While both pathways are represented in either setup, the pathway following the Newfoundland shelf break is populated stronger in the model-based experiments. In general we found that connectivity between the two regions is weaker in the experiments based on the climatological mean velocity output of the model than in those based on the Argo derived fields, first results indicate that this is due to stronger boundary currents and a weaker recirculation in the Labrador Sea.
Data-driven synthesis of primary plane-wave responses
Authors: Meles Giovanni Angelo , Zhang Lele , Thorbecke Jan , Wapenaar Kees , Slob Evert
Published: March 2020

Seismic images provided by standard Reverse Time Migration are usually contaminated by artefacts associated with the migration of multiples.

Multiples can corrupt seismic images by producing both false negatives, i.e. by destructively interfering with primaries, and false positives, i.e. by focusing energy at unphysical interfaces. Free-surface multiples particularly affect seismic images resulting from marine data, while internal multiples strongly contaminate both land and marine data. Multiple prediction / primary synthesis methods are usually designed to operate on point source gathers, and can therefore be computationally  demanding when large problems, involving hundreds of gathers, are considered.

In this contribution, a new scheme for fully data-driven retrieval of primary responses of plane-wave sources is presented. The proposed scheme, based on convolutions and cross-correlations of the reflection response with itself,  extends a recently devised Marchenko point-sources primary retrieval method for to plane-wave source data. As a result, the presented algorithm allows fully data-driven synthesis of primary reflections associated with plane-wave source data. Once primary plane-wave responses are estimated, they are used for multiple-free imaging via standard reverse time migration. Numerical tests of increasing complexity demonstrate the potential of the proposed algorithm to produce multiple-free images only involving the migration of few datasets.

The plane-wave source primary synthesis algorithm discussed in this contribution could then be used as an initial and unexpensive processing step, potentially guiding more expensive target imaging techniques. Moreover, the method could be applied to large 3D problems for which standard methods are prohibitively expensive from a computational point of view.
Activities and plans of the GGOS Focus Area Unified Height System
Authors: Sanchez Laura , Barzaghi Riccardo
Published: March 2020

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG), providing precise geodetic infrastructure and expertise for monitoring the System Earth, promotes the standardization of height systems worldwide. The GGOS Focus Area "Unified Height System” (GGOS-FA-UHS, formerly Theme 1) was established at the 2010 GGOS Planning Meeting (February 1 - 3, Miami, Florida, USA) to lead and coordinate these efforts. Starting point was the results delivered by the IAG Inter-Commission Project 1.2 "Vertical Reference Frames" (IAG ICP1.2 VRF), which was operative from 2003 to 2011. During the 2011-2015 term, different discussions focussed on the best possible definition of a global unified vertical reference system resulted in the  IAG resolution for the "Definition and realization of an International Height Reference System (IHRS)” that was approved during the 2015 General Assembly of the International Union of Geodesy and Geophysics (IUGG) in Prague, Czech Republic. The immediate objectives of the GGOS-FA-UHS are (1) to outline detailed standards, conventions, and guidelines to make the IAG Resolution applicable, and (2) to establish the realization of the IHRS, i.e., the International Height Reference Frame (IHRF). This contribution summarizes the main achievements of the GGOS-FA-UHS and provides a review of the open questions that need to be resolved in the near future.
Enhancing the completeness of statistical landslide susceptibility modeling by integration of release and propagation zones
Authors: Lima Pedro Henrique , Steger Stefan , Glade Thomas , Mergili Martin
Published: March 2020

Statistical landslide susceptibility models have been satisfactorily fulfilling the aim of predicting where future slides might happen, or more specifically, be initiated. By aiming to answer where landslides are likely to be initiated, those models mostly build upon mapped landslide release zones to create spatial predictions. The potential downslope propagation zones are usually neglected. This is a substantial limitation with regard to their applicability in the context of risk assessment in areas characterized by steep slopes. In fact, slide-type movements often evolve into flow-like movements, traveling long distances and thereby impacting also moderate and even nearly flat slopes. At this point, the integration of modeling approaches able to predict downslope landslide routes can contribute to enhance the completeness of the model.

This study aims to explore the added value of combining statistical modeling of landslide release areas with a data-driven runout model for a 54 km² catchment in the Nova Friburgo area in southern Brazil. In January 2011, a severe rainfall event in that mountainous region triggered numerous landslides, some of them evolving into hillslope debris flows affecting downslope areas. The hundreds of slides mapped after this event are here used as reference data.

The methodology consists of three steps: (a) the creation of multiple statistical landslide release susceptibility models; (b) back-analyzing the probability density functions of the angle of reach and travel distance, derived from the observed runout zones with the r.randomwalk model; (c) integration of the best performing release susceptibility model with r.randomwalk, computing the propensity of downslope regions to be affected, based on the release susceptibility and the probability density functions derived in (b).

Despite the appropriateness of purely statistical models for predicting future slide release zones, these models indeed overlook downslope propagations. The combined model, in its turn, not only succeeds in informing where landslides would initiate, but also about their downslope impact areas. The difference between the models is even more evident when analyzing how both models would predict the susceptibility for settled areas. While the release susceptibility model assigns more than 60% of this area to the low and very low susceptibility classes, the combined model predicts that actually less than 30% of this area would be assigned to the same classes. In a region where thousands of people are living, this difference might inform a large number of people and key infrastructure prone to be landslide affected. This greatly enhances the potential of landslide susceptibility models to be applied for hazard and risk management purposes also in those areas where landslides develop into hillslope debris flows.
Updated Mapping of the Hydrogen Distribution in the Lunar Polar Regions
Authors: Sanin Anton , Mitrofanov Igor , Bakhtin Boris , Litvak Maxim
Published: March 2020

It is well known that methods of nuclear physics allow one to study distribution of hydrogen-bearing compounds in the upper 1–2 m subsurface soil layer of atmosphereless celestial bodies or planets with thin atmospheres like Mars by measuring neutron spectra leak from the surface. For this study one needs not only to measure neutron spectra but to perform also a set of numerical simulations of the neutron production by the Galactic Cosmic Rays (GCRs) in subsurface soil, leakage of these neutrons from the surface, their transport to the neutron spectrometer on the orbit and processes of neutron interactions with the instrument’s detectors. These simulations make possible a model dependent deconvolution of the measured data to obtain the hydrogen concentration and/or other soil properties at a particular region of the planet.

Currently a number of numerical codes are being used for simulations of the neutron production and transport in planetary applications. All these codes provide a reasonable precision both in modeling of laboratory experiments and nuclear planetology tasks. However, the gravitational field description appropriate for simulation of a neutron propagation on planetary scales is not well addressed. For the planetary scales, it is not just enough to implement a uniform gravitational field (this option is available in some numerical codes). The planetary gravity should be described as a full-scale central force field with its potential depending from the distance from the center of planet.

We have developed a method of accounting effects of lunar gravity force and finite neutron lifetime on the spectral and angular distributions of neutron flux at different altitudes above Moon surface. This method was implemented to reprocess the data gathered by the collimated detectors of LEND instrument operated onboard NASA LRO spacecraft. The gravitational field description appropriate for simulation of a neutron propagation on planetary scales was not well addressed earlier.

As the result of the updated LEND data reprocessing with the discussed method, we obtained a new estimations of Water Equivalent Hydrogen (WEH) abundance in the lunar regolith and new maps of WEH distribution in the lunar polar regions. It is shown that difference of new derived values of WEH is about 0.08 wt% larger in comparison with the previously estimated value. The updated polar maps shows slightly different WEH distribution over the polar regions in comparison to the early published. The new polar maps will be used to select the landing sites of future landers.
The upper 2121 m at EastGRIP - Results from physical properties of NEGIS
Authors: Stoll Nicolas , Weikusat Ilka , Kerch Johanna , Eichler Jan , Shigeyama Wataru , Homma Tomoyuki , Jansen Daniela , Franke Steven , Kuiper Ernst-Jan , Wallis David , Westhoff Julien , Saruya Tomotaka , Faria Sérgio Henrique , Kipfstuhl Sepp , Azuma Kumiko Goto , Azuma Nobuhiko , Dahl-Jensen Dorthe
Published: March 2020

Here we present the ice microstructure and CPO (c-axes fabric) data from the upper 2121 m of the EastGRIP ice core, an on-going deep drilling project on the North East Greenland Ice Stream. Understanding ice flow behaviour of fast flowing ice streams is crucial for accurate projections of future global sea level rise, but is still poorly understood due to e.g. missing observational fabric data from ice streams.

The presented CPO patterns found at EastGRIP show (1) a rapid evolution of c-axes anisotropy compared to deep ice cores from less dynamic sites, (2) a CPO evolution towards a strong vertical girdle and (3) CPO patterns that have not previously been directly observed in ice. Furthermore, data regarding grain properties (e.g. grain size) and indications of dynamic recrystallization, already at shallow depths, are presented.

The ice CPO shows a clear evolution with depth. In the first measurements at 111 m depth a broad single maximum distribution is observed, which transforms into a crossed girdle CPO (196-294 m). With increasing depth, an evolution towards a vertical girdle c-axes distribution occurs. Below 1150 m the CPO evolves into a vertical girdle with a higher density of c-axes oriented horizontally, a novel CPO in ice. These CPO patterns indicate a depth-related change in deformation modes, from vertical compression to extensional deformation along flow.

Grain size values are similar to results from other Greenlandic deep ice cores. Grain size evolution is characterized by an increase until 500 m depth, a decrease until 1360 m depth and mainly constant values in the Glacial. These findings are accompanied by indications of an early onset of dynamic recrystallisation e.g. irregular grain shapes, protruding grains and island grains.

The presented high-resolution data enable, for the very first time, a detailed and data- based look into a fast-flowing ice stream and are an important step towards a better understanding of the rheology of ice and its flow behaviour.
Multi-Model Ensemble Crop Growth Simulation by use of the model framework Expert-N
Authors: Priesack Eckart , Duan Xiaohong , Gayler Sebastian , Heinlein Florian
Published: March 2020

We present an example for the generation of model ensembles by use of the model framework Expert-N. Different crop models are obtained by choosing different sub-models, which represent important processes to determine the dynamics of crop growth. In this way, different sub-models to simulate potential evapotranspiration, actual evaporation, actual transpiration, soil water flow, soil nitrogen transport, soil carbon and nitrogen turnover, crop development, canopy photosynthesis, potential and actual nitrogen uptake and crop growth are combined resulting in different crop models building a model ensemble. The sub-models are based on process descriptions that are included in the crop models CERES, SUCROS, SPASS and GECROS, but also stem from known soil models such as CENTURY, SOIL, SOILN, NCSOIL, LEACHM or HYDRUS.

The generated model ensemble is applied to simulate winter wheat growth at a field site in Southern Germany. We compare simulation results to measurements of crop biomasses and yields, and to soil water and nitrogen contents. It is concluded that model frameworks as the model system Expert-N can help to analyse structural uncertainties which lead to different simulation results between models of a model ensemble.
Transboundary delineation, characterisation and monitoring of groundwater bodies in the Dnipro river basin of Ukraine and the Pripyat river basin of Belarus under the European Water Initiative Plus for Eastern Partnership Countries (EUWI+)
Authors: Vasniova Olga , Biarozka Olga , Lyuta Nataliia , Sanina Iryna , Scheidleder Andreas , Humer Franko
Published: March 2020

The EU-funded program European Water Initiative Plus for Eastern Partnership Countries (EUWI+), which is the biggest commitment of the EU to the water sector in the EaP countries, helps Armenia, Azerbaijan, Belarus, Georgia, Moldova, and Ukraine to bring their legislation closer to EU policy in the field of water management, with a main focus on the management of trans-boundary river basins. It supports the development and implementation of pilot river basin management plans, building on the improved policy framework and ensuring a strong participation of local stakeholders.

Project funding is provided by the European Commission (DG NEAR), the EU support program for improved cooperation in the eastern EU neighborhood region and the EU Water Initiative Plus (EUWI+). On a national level, financial support comes from the Austrian Development Agency, the Austrian Federal Ministry for Sustainability and Tourism as well as from the French Office International de l’Eau. Up to 2020, management plans for selected river basins and transboundary rivers will be implemented under the leadership of a European project consortium headed by the Environment Agency Austria.

One important first step is the delineation of groundwater bodies according to the principles of the EU Water Framework Directive and the harmonization of transboundary groundwater bodies between Belarus and Ukraine. Groundwater experts of the Ukrainian Geological Prospecting Institute and the Belarus Unitary Enterprise “Research And Production Centre For Geology” identified and characterized the transboundary groundwater bodies which are crossing country boarders in the Dnipro river basin in Ukrainian and the Pripyat river basin in Belarus. Furthermore, a corridor which is supposed to be in transboundary groundwater interaction was identified. All methodological work was bilaterally agreed.

The experts of both countries made an inventory of existing groundwater monitoring sites and a proposal of monitoring sites which should be subject to transboundary monitoring and bilateral data exchange. In addition, a joint transboundary groundwater survey including the joint selection of monitoring parameters, a common sampling campaign and a joint interpretation of the monitoring results is planned for the period until August 2020.

A statement of the quantitative and chemical status and the risk of not achieving good status in future, as a conclusion of all collected information and monitoring data will be given.

The already available results of the joint investigations are presented.
Loss of work productivity in a warming world: Differences between developed and developing countries
Authors: Yu Shuang , Yan Zhongwei , Xia Jiangjiang , Zhao Alcide , Zhang Anzhi , Xia Yang , Guan Dabo , Han Jiarui , Wang Jun , Chen Liang , Liu Yakun
Published: March 2020

Comparable estimates of the heat-related work productivity loss (WPL) in different countries over the world are difficult partly due to the lack of exact measures and comparable data for different counties. In this study, we analysed 4363 responses to a global online survey on the WPL during heat waves in 2016. The participants were from both developed and developing countries, facilitating estimates of the heat-related WPL across the world for the year. The heat-related WPL for each country involved was then deduced for increases of 1.5, 2, 3 and 4 °C in the global mean surface temperature under the representative concentration pathway scenarios in climate models. The average heat-related WPL in 2016 was 6.6 days for developing countries and 3.5 days for developed countries. The estimated heat-related WPL was negatively correlated with the gross domestic product per capita. When global surface temperatures increased by 1.5, 2, 3 and 4 °C, the corresponding WPL was 9 (19), 12 (31), 22 (61) and 33 (94) days for developed (developing) countries, quantifying how developing countries are more vulnerable to climate change from a particular point of view. Moreover, the heat-related WPL was unevenly distributed among developing countries. In a 2°C-warmer world, the heat-related WPL would be more than two months in Southeast Asia, the most influenced region. The results are considerable for developing strategy of adaptation especially for developing countries.
Exchange coefficients derived from GPS-sonde and SFMR measurements in hurricane conditions
Authors: Ermakova Olga , Rusakov Nikita , Poplavsky Evgeny , Troitskaya Yuliya , Sergeev Daniil , Balandina Galina
Published: March 2020

Insufficient knowledge of the atmosphere layer momentum, heat and moisture transfer between the wavy water surface and marine atmospheric boundary layer under hurricane conditions lead to the uncertainties while using weather forecasting models and models of climate. In particular, there is a significant lack of data for heat and moisture exchange coefficients. In this regard, it is necessary to analyze and process the vertical profiles of wind speed and thermodynamic quantities. The present study is concerned with the analysis and processing of measurements from the NOAA falling GPS-sondes for hurricanes of categories 4 and 5 of 2003-2017, which represent an array of data on wind speed, temperature, altitude, coordinates, etc.

The proposed approach for describing a turbulent boundary layer formed in hurricane conditions is based on the use of the self-similarity properties of the velocity and enthalpy profiles in the atmospheric boundary layer, which includes a layer of constant flows, transferring into its “wake” part with height. Based on the proposed approach, the aerodynamic drag coefficients Cd and the enthalpy exchange coefficient Ck for a selected group of hurricanes were restored. As the value of Ck/Cd represents a determining factor in the formation of a hurricane, the dependence of this ratio on the wind speed was constructed.

This work was supported by the RFBR projects No 19-05-00249, 19-05-00366, 18-35-20068 (remote sensing data analysis) and RSF No 19-17-00209 (GPS-sonde data assimilation and processing).
Land-Ocean interactions at the southwest Greenland margin during the Holocene
Authors: Allan Estelle , de Vernal Anne , Seidenkrantz Marit-Solveig , Hillaire-Marcel Claude , Pearce Christof , Meire Lorenz , Røy Hans , Mathiasen Anders Møller , Nielsen Mikkel Thy , Plesner Jane Lund , Perner Kerstin
Published: March 2020

Palynomorph analysis of marine cores raised off Nuuk (southwestern Greenland) provided records of sea-surface conditions and climate-ocean-ice dynamics at centennial resolution over the last 12,000 years. Transfer functions using dinocyst assemblages provided information about the sea-ice cover, seasonal sea-surface temperature (SST) and salinity (SSS), as well as primary productivity. At about 10,000 cal. years ago, an increase in species diversity and the rapid increase of phototrophic taxa (light-dependent), marks the onset of interglacial conditions, with summer temperature increasing up to ~10°C during the Holocene Thermal Maximum (HTM). Low SSS and high productivity conditions are recorded during the interval, which we associate to increased meltwater and nutrient input from the Greenland Ice Sheet. After ~5000 cal. years BP, the decrease of phototrophic taxa marks a two-steps cooling associated with the Neoglacial trend. Since ~2000 cal. years BP, an increase in the high-frequency variability of sea surface conditions is noticeable. The second step change towards colder and more unstable conditions starting about 3000 cal. years BP coincides with the disappearance of the Saqqaq culture. The gap of human occupation in western Greenland, between the Dorset and the Norse settlements, i.e., from ca. 2000 to 1000 cal. years BP, may thus be linked to the highly unstable conditions in surface waters.
Diurnal cycle in anthropogenic aerosol impacts on clouds
Authors: Rahu Jorma , Toll Velle , Post Piia
Published: March 2020

The cooling effect of anthropogenic aerosols on Earth's climate offsets part of the greenhouse gas warming effect. To reduce the uncertainty in the aerosol cooling effect on climate, aerosol impact on clouds needs to be better understood. In this research, we extend satellite observations of polluted cloud tracks from Toll et al. (2019, Nature, https://doi.org/10.1038/s41586-019-1423-9) with analysis of temporal evolution of anthropogenic cloud perturbations using satellite data from SEVIRI instrument onboard geostationary Meteosat satellite. Study area is concentrated to European part of Russia as we have found strong contrast between properties of polluted and unpolluted clouds in this area. We analyze the properties of polluted clouds at pollution hot spots and compare these to the properties of the nearby unpolluted clouds. We compare the temporal evolution of the properties of the polluted and unpolluted clouds to study the importance of diurnal cycle in aerosol-cloud interactions.
Structural Characteristics and Evolution Process of the Western Slope of Xihu Sag
Authors: Dai Yining , Wu Zhiping , Cheng Yanjun , Xu Bin
Published: March 2020

The western slope is the most promising area for hydrocarbon accumulation in Xihu Sag. Since Cenozoic, the western slope has undergone multiple stages of evolutions, which resulted in the complex structure of the slope and complicated the hydrocarbon exploration in the study area. Based on the fine seismic interpretation, fault activation rate calculation and balanced cross section restoration, this paper analyzes the structural characteristics and evolution process of the western slope, in order to provide supports to the hydrocarbon exploration. The results show that the western slope is controlled by NNE-striking and NW-striking faults. Seperated by NW-striking faults, the western slope can be divided into sub-Hangzhou slope, sub-Pinghu north slope, sub-Pinghu south slope and sub-Tiantai slope from north to south. (1) The sub-Hangzhou slope is a faulted-step gentle slope. In faulting episode I (Cretaceous-Paleocene), the slope was controlled by step faults. In faulting episode II (Early Eocene), the slope changed from fault-controlled slope to gentle strata slope. In depressional period (Late Eocene-Middle Miocene), the slope was a gentle strata slope. (2) The sub-Pinghu north slope is a graben-horst slope. In faulting episode I (Cretaceous-Paleocene), the slope was controlled by two sets of step faults with opposite tendencies. In faulting episode II (Eocene), the slope changed from fault-controlled slope to gentle strata slope. In depressional period (Oligocene-Middle Miocene), the slope was a gentle strata slope. (3) The sub-Pinghu south slope is a faulted-step steep slope. In faulted period (Cretaceous-Paleocene), the slope was controlled by Pinghu fault and secondary step faults. In depressional period (Oligocene-Middle Miocene), the activation of Pinghu fault became weak, but this fault still divided the strata. (4) The sub-Tiantai slope is a single-fault steep slope. In faulted period (Cretaceous-Paleocene), the slope was controlled by Baoshi fault. In depressional period (Oligocene-Middle Miocene), the activation of Baoshi fault became weak, but this fault still divided the strata. Differences of structural characteristics and evolution process influence the hydrocarbon accumulation in different sub-slopes.
Satellite and ground-based magnetic field observations related to volcanic eruptions
Authors: Schwingenschuh Konrad , Magnes Werner , Shen Xuhui , Wang Jindong , Cheng Bingjun , Pollinger Andreas , Hagen Christian , Lammegger Roland , Ellmeier Michaela , Schirninger Christoph , Eichelberger Hans-Ulrich , Mandl Bernhard , Boudjada Mohammed Y. , Besser Bruno P. , Rozhnoi Alexander A. , Zhang Tielong , Delva Magda , Jernej Irmgard , Aydogar Özer , Leonhardt Roman
Published: March 2020

In this study we investigate volcanic eruption phenomena related to ionospheric disturbances, e.g. Heki (2006) used total electron content (TEC) measurements for this task. In particular, a model is developed how discharge phenomena (e.g. Houghton etal, 2013) can produce magnetic field variations at SWARM and CSES satellite orbits, i.e. altitudes of ~500 km in the F-region. Several coupling mechanism between lithosphere, atmosphere, and ionosphere are discussed by Simões etal (2012).
Experimental evidence is based on magnetic field observations aboard CSES mission in the time frame July 2018 to January 2019. The theoretical considerations include the source mechanism, propagation path, and the signal strength at low earth orbit satellite altitude.

Ref:
(1) Heki, K., Explosion energy of the 2004 eruption of the Asama Volcano, central Japan, inferred from ionospheric disturbances, GRL, 33, L14303, 2006. doi:10.1029/2006GL026249
(2) Houghton, I. M. P., K. L. Aplin, and K. A. Nicoll, Triboelectric Charging of Volcanic Ash from the 2011 Grı́msvötn Eruption, PRL, 111, 118501, 2013. doi:10.1103/PhysRevLett.111.118501 arXiv:1304.1784
(3) Simões F., R. Pfaff, J.-J. Berthelier, J. Klenzing, A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms, SSR, 168:551–593, 2012. doi:10.1007/s11214-011-9854-0
Quantifying active tectonics in the case of dynamic and instable landscape: an example from the Bhutan Himalayas
Authors: Sassolas-Serrayet Timothee , Simoes Martine , Cattin Rodolphe , Le Roux-Mallouf Romain , Ferry Matthieu , Drukpa Dawchu
Published: March 2020

The quantification of active tectonics from geomorphological and morphometric approaches most often implies that erosion and tectonics have reached a certain balance. Such equilibrium conditions may however be seldom found in nature, as questioned and documented by recent theoretical studies, in particular because drainage basins may be quite dynamic even though tectonic and climatic conditions remain constant.

Here, we document this drainage dynamics from the particular case example of the Bhutan Himalayas. Evidence for out-of-equilibrium landscape features have for long been noticed in Bhutan, from major (> 1 km high) river knickpoints and from the existence of high-altitude low-relief surfaces within the mountain range. These geomorphologies were generally interpreted in the literature as representing a recent change in climatic and/or tectonic conditions, either related to the uplift of the Shillong Plateau (climate/tectonic change) or to the initiation of uplift over a blind ramp within the mountain range (tectonic change).

To further characterize these geomorphologies and discuss their origin and meaning in terms of regional tectonic or climatic evolution, we perform a detailed quantitative geomorphometric analysis using c plots and basin averaged aggressivity metrics, at various spatial scales, from large Himalayan rivers to local streams draining the low-relief surfaces. Our results first emphasize that the morphology of Bhutan does not result from a general wave of incision propagating upstream, as expected from most previous interpretations. Rather, we find that the river network is highly unstable and dynamic, in particular for the rivers draining the low-relief surfaces, hampering a proper quantification of tectonics from classical approaches based on denudation or incision rates. Finally, we discuss the origin and meaning of the observed dynamics, and from there draw some useful guidelines for future morpho-tectonic studies of active landscapes.
CryptoTEPHras in the ICDP Dead Sea deep core to synchronise past eastern MEditerranean hydroclimate (TEPH-ME)
Authors: Neugebauer Ina , Schwab Markus J. , Blockley Simon , Lane Christine S. , Plessen Birgit , Tjallingii Rik , Wulf Sabine , Brauer Achim
Published: March 2020

The hypersaline Dead Sea is a key palaeoclimate archive in the south-eastern Mediterranean region, situated at a critical position between more humid Mediterranean climate and the hyper-arid Saharo-Arabian desert belt. The ca 450 m long ICDP drill core 5017-1, recovered from the deepest part of the Dead Sea, spans the last ~220,000 years as constrained by radiocarbon, U-Th dating and floating δ18O stratigraphy methods. Nevertheless, an independent dating method is much needed because (i) radiocarbon dating is limited to the last ~40,000 years; (ii) U-Th dating of authigenic carbonates requires a complex correction procedure leading to large age uncertainties; and (iii) wiggle matching of oxygen isotope data is not independent and, hence, does not allow the identification of lead- and lag-phase relationships of changing hydroclimate in comparison to other palaeoclimate records.

Tephrochronology has been demonstrated a powerful tool for dating and synchronisation of palaeoclimate records for regional and global comparison. Due to a lack of visible tephra layers in the Dead Sea sediment record, direct links with the eastern Mediterranean tephrostratigraphical lattice are still absent. Recently, the first cryptotephra ever identified in Dead Sea sediments has been associated with the early Holocene S1-tephra from central Anatolia. This discovery encouraged a systematic search for tephra time-markers in the ICDP deep-basin core 5017-1, with the aim of improving the chronology of the deep record significantly and providing a tool for precise regional synchronisation of proxy records.

In the first phase of the TEPH-ME project focusing on the early last glacial (ca 100-110 ka) and lateglacial (ca 11-15 ka) time intervals in the ICDP core, we have identified more cryptotephra layers than expected. First glass geochemical data suggest that the majority of volcanic ash in the Dead Sea sediments originates from Anatolian volcanic provinces. Even though proximal Anatolian tephra data for comparison are still limited, the identification of cryptotephra in the long Dead Sea record provides novel opportunities to advance the tephrostratigraphical framework in this region, e.g. through synchronising the Dead Sea and Lake Van (eastern Anatolia) sediment records, but also with archaeological and palaeoenvironmental sites that are currently investigated in the Levant and in Arabia.
Dynamics of water quality and phytoplankton community driving by extreme inflow in a huge drinking water source reservoir, China
Authors: Zhu Guangwei , Da Wenyi , Zhu Mengyuan , Li Wei
Published: March 2020

The tail of reservoir is the un-stable zone in water quality and phytoplankton community. Therefore, it is the crucial zone in aquatic ecosystem transition. To understand the transition characteristics and driving mechanisms of water environment dynamics, eighteen months high frequent monitoring of water environment and phytoplankton community in tail of a deep and large reservoir, Xin'anjiang Reservoir in southeast of China, were undertaken by water quality monitoring buoy and 3-days interval water sampling. The result showed that, there are clearly seasonal thermal and oxygen stratification in the river mouth of the reservoir. The nutrient and chlorophyll-a concentrations also show stratifying phenomenon during thermal stratification period. Heavy rain and inflow will shortly destroy the stratification. Nutrient concentrations were high dynamic in the river mouth. Total phosphorus ranges among 0.011 mg·L-1 to 0.188 mg·L-1, and total nitrogen ranges among 0.75 mg·L-1 to 2.76 mg·L-1. The dissolved phosphorus occupied 56% of total phosphorus, and dissolved nitrogen occupied 88% of total nitrogen, respectively. Nutrient concentrations influenced strongly by rainfall intensity and inflow rate. Total phosphorus and nitrogen concentrations were significantly related to 3-days accumulated rainfall. Nutrient concentration in flood season (March to June) was significantly high than non-flood season (P
How hurricanes influence social and economic changes ?
Authors: Gargani Julien , Pasquon Kelly , Jouannic Gwenael
Published: March 2020

The understanding of the long-term influence of hurricanes on the coastal zone deal with the monitoring the geomorphological evolution and the socioeconomic changes. In this study we analyze, the evolution of the Saint-Martin Island (West Indies, Caraïbean Sea) from 1947 to 2019. During the last 70 years, several hurricanes occurred and Saint-Martin has seen huge economic and environmental changes due to (1) fiscal laws, (2) a huge population increase, (3) coastal urbanization. Based on aerial photos and satellite images, we have analyzed this development. We have described the urban, agricultural and natural change. The transformation of the agricultural economy into an economy dominated by tourism, has significantly changed the coastal zones. The new spatial and economical configuration of the island has led to a higher risk of marine flooding.

Hurricane Irma (2017) seriously damaged coastal infrastructures and dwellings, caused fatalities as well as triggered the mangrove partial destruction. Field study comparison with satellite images observation show that non-negligible mistakes on the dwelling damage could be done. The damage quantification is often use to elaborate plan risk and must be carefully taken into account. In the Saint-Martin Island, the population disagree with plan risk focusing only on natural hazard without integrating socioeconomic risk and difficulties that strongly affect the inhabitants since several decade. Solution proposed to manage natural risk often trigger the conditions that favored the occurrence of social crisis and social crisis management has often generated an increase of the vulnerability to natural hazard (Gargani and Jouannic, 2015 ; Gargani, 2016 ; Jouannic et al., 2017). As a consequence of Irma Hurricane, social inequalities are expected to increase (Gargani, 2019).

 

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Gargani J., Prévenir les catastrophes naturelles ou alibi de réorganisation urbaine en faveur des plus riches ? Le journal du MAUSS, 28 octobre 2019.

Jouannic G., Gargani J., Legendre T., Gastaud P., Kolli Z., Crozier D., Arki F., Stratégie d’adaptation et réduction de la vulnérabilité : exemple de l’évolution des rives dans la vallée du Rhône et de la Saône. Espace populations sociétés, 2016/3, 2017.

 
Neural Networks to estimate world forest foliar elemental composition and stoichiometry
Authors: Vallicrosa Helena , Sardans Jordi , Zuccarini Paolo , Maspons Joan , Peñuelas Josep
Published: March 2020

We developed global maps of N, P, K concentrations and ratios in leaves for woody plants by modeling with Neural Networks at 1km resolution. We gathered georeferenciated data from published data bases (like TRY and ICP) and a total of 206 peer-published papers (ISI WEB) achieving 28736 records of N, P and K leaf concentrations that we split in 6 morphoclimatic groups (tropical evergreen, tropical deciduous broadleaves, temperate coniferous, temperate evergreen broadleaves, temperate deciduous broadleaves and boreal). We trained Neural Networks with climatic, soil and atmospheric deposition data and morphoclimatic groups to model the foliar elemental composition and project it at global scale according to a Land Cover map. The models provide maps with information of the foliar concentrations of each element at pixel level, their uncertainty and goodness of fit, and relative importance of the independent variables. Linear models were also created to show the relationship between dependent and independent variables. These maps and these relationships will improve the understanding of the biogeochemical processes and provide better input nutritional data for the global models of carbon cycle and climate change.
Geophysical investigation of the western end of the Carlsberg Ridge: preliminary results of the CARLMAG cruise
Authors: Chamot-Rooke Nicolas , Janin Alexandre , Rodriguez Mathieu , Delescluse Matthias , Dyment Jérôme , Fournier Marc , Huchon Philippe , Olive Jean-Arthur , Rabaute Alain , Vigny Christophe
Published: March 2020

A sizeable portion of oceanic lithosphere has been produced at the Carlsberg Ridge, one of the three major ridge branches that shaped the Indian Ocean. Accretion started in the Paleocene with the ultra-fast widening of the Arabian Sea to the North and the Eastern Somali Basin to the South (full spreading rate of ~130 mm/yr between 61 Ma and 49 Ma), both basins opening in the wake of the rapid migration of India towards Eurasia. Spreading rate abruptly dropped to ultra-slow after 47 Ma and a long period of accretion stagnation prevailed (full rate <12 mm/yr) until the establishment of the slow present-day regime at ~20 Ma (mean 24 mm/yr rate since Chron 6 at the western end of the Carlsberg Ridge). Mode and rate of production of ocean floor at the Carlsberg Ridge seem to have interacted with a number of regional tectonic events since the beginning of the Himalayan orogeny, including the early Indian continent collision, the westward propagation of the Sheba Ridge into the Africa/Arabia continent and the coeval initiation of the Owen transform and opening of the Gulf of Aden. Here we report the results of the recent CARLMAG survey (Spring 2019) conducted at the westernmost edge of the Carlsberg Ridge close to its intersection with the active Owen transform fault. The cruise was conducted aboard BHO Beautemps-Beaupré operated by the French Naval Hydrographic and Oceanographic Service. We explored the post-50 Ma ocean floor along a set of long profiles crossing both sides of the ridge using multibeam bathymetry, bottom reflectivity, mud penetrator, magnetic and gravimetric measurements. For the first time, semi-complete multibeam coverage allows detailed mapping of the seafloor until it gets buried below the sediments of the Indus fan, at least over the northern limb. The southern limb, devoid of sediments, shows clear rotation of the main fault trends towards older ages, which we attribute to changes in India-Somalia kinematics. The region close to the ridge axis and close to the Owen transform is rich in oceanic core complexes, some of them known from patchy previous acquisitions, and others discovered in the course of our survey. Their highly corrugated surfaces show a wide variety of shapes at various distances from the ridge axis that may be seen as snapshots through time, bearing important information regarding their formation and progressive erosion as they move away. A clear pattern of Miocene oceanic magnetic lineations is recognized, as well as a few older anomalies at the extreme Northern and Southern limits of the survey. This dataset allows us to build a new structural and kinematic scenario for the evolution of this segment of the Carlsberg Ridge and frame it into a more regional geodynamic framework.
Satellite thermal monitoring of Balkan region by means of Robust Satellite Techniques: the case of Albania (26 November 2019, Mw 6.4) earthquake
Authors: Tramutoli Valerio , Genzano Nicola , Colonna Roberto , Filizzola Carolina , Lisi Mariano , Pergola Nicola , Satriano Valeria
Published: March 2020

Since 2001, Robust Satellite Techniques (RST; Tramutoli 1998, 2007) has been used to study - by analyzing long-term TIR observations provided by passive satellite sensors - the enhancement of the Earth thermally emitted radiation, possibly related to seismic activities.

Such an approach has demonstrated to be able (especially when applied to geostationary satellite radiances) to isolate TIR anomalies possibly related to earthquake occurrence from those expected as a consequence of others natural (e.g. meteorological) or observational (e.g. measurement time and/or place) sources. Among the others TIR anomalies, those more significant (in term of Signal/Noise ratio), extended (in space) and persistent (in time) have been considered (SSTAs, Significant Sequence of TIR Anomalies, Eleftheriou et al., 2016) for further analyses. Up to now, long-term statistical correlation analyses between seismic events and RST-based SSTAs carried out in different European seismic regions (i.e. Greece, Italy and Turkey by using MSG-SEVIRI) highlights that the 75% of SSTAs are in apparent space-time relation with earthquakes with magnitude greater than 4. In all testing regions/periods a non-casual relation has been found.

In this paper, we will show the results achieved by real-time thermal monitoring over Albania region at time of the strong earthquake of magnitude Mw 6.4 occurred on 26 November 2019. Moreover, we will discuss about the impact of the use of the "RST-based satellite TIR anomalies" parameter in the framework a multi-parametric system devote to the seismic hazard assessment in the short-term.
Climate changes along the Labrador coasts during the Holocene based from pollen assemblages
Authors: Roy Natasha , Fréchette Bianca , de Vernal Anne
Published: March 2020

The rapid ongoing warming recorded across northern regions is unprecedented. This warming is however not uniform across the territory and large regional discrepancies exist. It is therefore relevant to document the variations of climate in the past in both time and space in order to understand the regional climate dynamics. However, in Labrador, instrumental and historical data are rare and only cover a short period of time. Our knowledge of the natural evolution of the climate is therefore limited, which hampers our capacity to evaluate the natural modes of variability and simulate changes at regional scales. From this viewpoint, quantitative climate reconstructions from pollen assemblages are useful because they allow the development of time series covering long periods of time. Here, we report on pollen data from peat and lake sediments collected in the area of Okak, Nain and Dog Island along the Labrador coast.  These data are used for climate reconstruction over the last millennia, thus allowing to document natural climate variability at regional scale. The climate parameters we reconstruct by the means of the modern analogue technique include the summer temperature, sunshine and precipitation. The results provide new insights about the climate of Labrador at local to regional scale, illustrating notably the importance of the Labrador Current on climatic conditions at nearshore locations. In fact, our climate reconstructions demonstrate a disparity with the regional climate curve which may testify of the east-west climatic gradient between islands and the land.
Impact of mangrove age on sediment retention and wave dissipation and its links to ecosystem services in the Red River Delta, Vietnam
Authors: Hackney Chris , Carrie Rachael , Tan Van Dao , Ahmed Joshua , Teasdale Serena , Quinn Claire , Stringer Lindsay , Le Hue van Thi , Nguyen Quang Hong , Pham Thi Thanh Nga , Parsons Daniel
Published: March 2020

Mangroves provide critical ecosystem services that support livelihoods and communities at the coastal margin. They are key natural flood defences to tropical cyclone driven storm surges, they store sediment that is vital for maintaining delta surface elevations in the face of rising sea levels, and transfer key nutrients to agricultural land. Over the past few decades, stressors on mangroves have increased with associated declines in global areal extent, and growing concern about their condition, including for forests that have been restored or afforested. Most remaining mangrove forests comprises a mix of ages and quality. Limited research exists exploring how differing age, structure and health of mangroves impacts sediment retention and aids the dissipation of wave and storm energy, and links these physical processes to the delivery of ecosystem services.

 

In this study, we demonstrate how mangrove age and health differentially impacts rates of sedimentation, attenuates water level and tidal propagation and aids storm energy dissipation along a section of mangrove forest in Thai Binh province on the Red River Delta in Vietnam. Data were collected over a four month period and highlight spatially variable responses to tides and the increasing influence of the nearby Thai Binh River. We show that sedimentation rates vary from 0.8 m/yr to 0.14 m/yr with increasing distance inland, whilst peak tidal range varies from 1.5 m to 0.5 m with mangrove age.  We demonstrate that these spatial patterns correlate not only to distance inland, but also mangrove age, and the provision of ecosystem services as recorded by household surveys from local communities. This highlights the need for global mangrove databases to account for mangrove quality and health data in order to capture definitively the ecological, hydrodynamic and sedimentological impacts of mangrove forests on coastal and deltaic regions.