bluuebunny/crossref_metadata_2025 huggingface dataset:
Pixels to plates: reconstructing Pacific-Izanagi plate tectonics from seismic tomography
Authors: Wu Jonny , Lin Yi-An , Flament Nicolas , Wu Tsung-Jui , Liu Yiduo
Published: March 2020

Contrasted subduction histories have been proposed for the northeast Asian margin since mid-Cretaceous times due to extensive subduction, which has recycled the Izanagi-Pacific mid-ocean ridge, the entire Izanagi rift flank, and part of the western Pacific plate into the mantle.  Here we reconstruct northwest Pacific-Izanagi plate tectonics since Cretaceous times from imaged and predicted mantle structure.  We compare our tomography-led NW Pacific-Panthalassa plate reconstruction against a relatively independent, large (n>1000) magmatic and isotopic geochemical database from East Asia.  Our reconstruction reveals the ancient boundaries between the western Kula plate, the Izanagi plate, and the ‘Junction’ realm, which divided Pacific-Panthalassa from Tethys during Cretaceous times, providing a new NW Pacific-Panthalassa plate tectonic framework during late Mesozoic times.

We reconstructed the western Pacific plate by structurally-restoring (i.e. unfolding) imaged slabs from tomography using area conservation of cross-sectional slab areas, following Wu et al (2016).  The vanished Izanagi plate was then modeled as a conjugate rift flank.  Western Pacific slab areas were assessed from global tomography models MITP08, GAPP4, UUP07, and from the full-waveform regional tomography FWEA18 (Tao et al., 2018).  To mitigate image blurring, we introduced a new ‘tomographic smearing’ correction based on computing input and output slab volumes from synthetic slab resolution tests. 

Our tomography-led plate model indicates: (1) that the stagnant Pacific slabs have subducted along Eurasia since ~50 ± 10 Ma; (2) that the Izanagi-Pacific ridge intersected Korea to Kamchatka at a low angle ~50 ± 10 Ma, consistent with an observed 56 to 46 Ma magmatic gap between Japan and Sikhote-Alin, Russia, and with geodynamic models that assimilate low-angle 50 Ma ridge-trench intersection;  and (3) that subduction of the Izanagi plate during the mid- to late Cretaceous was limited between Bohai Bay, China, and westernmost Alaska.  During the late Cretaceous, the SW margin of the Izanagi plate was bounded by an extensive NW-SE transform that we call the ‘Qingdao line’.  The newly-proposed Qingdao line explains the well-recognized, but poorly-understood contrasts in Cretaceous magmatism between southeast and northeast China.  Subduction initiated along the Qingdao line during the Pacific plate motion change at ~50 Ma, forming the Izu-Bonin-Marianas subduction system. 
Controls on stratigraphic variability in a semi-closed rift basin over the Late Quaternary, Gulf of Corinth, Greece
Authors: Pechlivanidou Sofia , Sergiou Spyros , Geraga Maria , Gawthorpe Robert , Antoniou Dimitra , Angelopoulou Dimitra , Ford Mary , Fabregas Natacha
Published: March 2020

The Corinth Gulf is a semi-closed active rift basin, which alternated between marine and isolated/semi-isolated conditions as sea level fluctuated with respect to basin sills during Quaternary glacial/interglacial cycles. Results from the recent IODP Expedition 381 reveal cyclic variations of 10s-100s of kyr in sedimentation rates and basin paleoenvironment. In this study we investigate the controls on stratigraphic development of the Corinth basin during the last eustatic cycle and the Holocene based on core data from the IODP Expedition 381 Site M0079. We perform a multi-proxy analysis of the upper ~200 mbsf of core covering Marine Isotope Stages (MIS) 1-5 (i.e. last 130 kyr). Our analyses include grain size and micropaleontological (foraminifera) analyses at regular intervals (~0.5 m), Computed Tomography (CT-scanning) of selected u-channels and specific microscopic work (smear slides, SEM) on targeted samples. Our results show pronounced variability in sedimentation patterns during the isolated/semi-isolated phases compared to the marine intervals. Low density, thinly bedded and laminated muds alternating with high density homogenous mud beds and occasionally sandy, organic rich beds prevail during isolated/semi-isolated conditions. In contrast, homogenous and/or highly bioturbated successions characterize the marine sequences. The transitions from marine to isolated/semi-isolated conditions and vise-versa are often associated with authigenic carbonate deposition. Fine grained sediments (sand < 10%) dominate both the marine and the isolated sequences. Nevertheless, sandy turbidites (sand > 10%) are also present and are more often observed in the isolated phases, likely associated with climatic-driven changes in erosional processes onshore. Our analysis reveals short-lived isolated/semi-isolated sub-phases within the lower marine interval corresponding to the MIS5b and MIS5d lowstands. Short marine spikes also interrupt the isolated/semi-isolated conditions of the last glacial period indicating temporary sea level rises within MIS3. Overall, the marine intervals display significant paleoenvironmental differences although they share similar sedimentary patters. In particular, we observe more diverse palaeoceanographic conditions in the MIS5 marine sub-phases compared to the MIS1, especially regarding temperature and eutrophication levels of the water column.  
Integrating data from different sensors for damage assessment after a natural disaster in rural areas
Authors: Havivi Shiran , Maman Shimrit , Rotman Stanley R. , Blumberg Dan G.
Published: March 2020

Rapid damage mapping following a disaster event is critical to ensure that the emergency response in the affected area is prompt and efficient. Amongst major disasters, earthquakes are characterized as unpredictable and of high frequency of occurrence. Previous and current studies focus mainly on the mapping of damaged structures in urban areas after an event such as an earthquake disaster. Yet, research focusing on the damage level or its distribution in rural areas is absent. According to the UN, nearly half of the world's population lives in rural areas and is expected to rise. Furthermore, their resources and capabilities for disaster relief operations are limited. Therefore, there is a great importance to assess the damage following a disaster in these areas.

The primary aim of this study is to characterize and assess the damage (level and extent), temporally and spatially, following an earthquake event, in rural settlements. This will allow producing an algorithm suitable for rural area rapid mapping, which will contribute to our understanding and will provide insights of the damage extent and will allow a better response and access to the affected regions and remote population.

For this purpose, a damage assessment algorithm that will map the damage in both urban and rural environments is proposed. This algorithm makes use of combining SAR and optical data for rapid damage mapping.

As a case study we will demonstrate this algorithm using the areas affected by the Sulawesi earthquake and subsequent tsunami event in Indonesia that occurred on 28 September 2018. High-resolution COSMO-SkyMed images pre and post the event, alongside a Sentinel-2 image pre- event are used as inputs.

The affected areas were analyzed with the SAR data using interferometric SAR (InSAR) coherence map. To overcome the loss of coherence caused by changes in vegetation cover, a vegetation mask was applied by using the NDVI to identify (and remove) vegetated areas from the coherence map. Then, thresholds were determined for the co-event coherence map (≤ 0.5) and the NDVI (≥ 0.4) and the two layers were combined into one. Based on the combined map, a damage assessment map was generated by using GIS spatial statistic tools (Fishnet and Zonal statistics). This map provides a quantitative assessment of the nature and distribution of the damage in rural and urban environments, as well the differences of damage features between them. The preliminary results show that while in urban area many structures were damaged, still in the rural areas the damage is larger, since most of the structures were damaged or even destroyed.
(U-Th-Sm)/He dating of supergene Fe duricrusts in NE French Guiana: implications of a multiproxy approach
Authors: Heller Beatrix , Bressan Riffel Silvana , Gautheron Cécile , Allard Thierry , Morin Guillaume , Roig Jean-Yves , Coueffe Renaud
Published: March 2020

Laterites are developing under intense chemical weathering and low physical erosion rates. Despite their large extension at the Earth’s surface, there is still a lack of time constraints for their formation, evolution and relation with climatic change. Nevertheless, several chronological studies show that they represent a geological record at least all along the Cenozoic Era. Indeed, laterite samples often contain several coexisting generations of iron oxides and oxyhydroxides that indicate successive weathering processes due to the dissolution of previously formed phases followed by reprecipitation. This study focuses on the condition and chronology of weathering in Northeastern French Guiana which generated pedogenic iron crusts on Paleoproterozoic mafic and intermediate rocks. It offers the opportunity to document the evolution of this part of the Guyana Shield, known as a tectonically stable area since the Cretaceous. The two sampling sites, Kaw and Baduel, are paleosurfaces at 300m and 100m elevations, respectively, that have been dated previously by paleomagnetism, providing Eocene ages for both sites, albeit with some substantial uncertainties and dispersion [1].

Since the duricrust (top layer) of the lateritic profile is enriched in hematite and goethite, we aim to date those mineral phases using the (U-Th-Sm)/He method. Older ages are from Oligocene and Miocene epochs for the Kaw and Baduel sites, respectively, with a large dispersion in the age values, as expected from the presence of several generations of Fe-minerals. Identification of petrological relationship between these different generations is hindered by their intimate mixing. In order to overcome this difficulty and to identify the episodes of weathering and mineral precipitation, we coupled a number of mineralogical and geochemical analyses, namely through powder and single grain X-ray diffraction, energy dispersive X-ray spectrometry (SEM-EDS) and solution- and LA-ICP-MS. Data on formation ages of secondary iron phases will be discussed by reference to literature, in terms of geodynamic and paleoclimatic forcing.

[1] Théveniaut, H., and Freyssinet, P. (2002): Timing of lateritization on the Guiana Shield: synthesis of paleomagnetic results from French Guiana and Suriname. Palaeogeography, Palaeoclimatology, Palaeoecology (178) 91-117
Aftershock Activity at Intermediate-Depth Earthquakes in Northern Chile Controlled by Plate Hydration
Authors: Cabrera Leoncio , Ruiz Sergio , Poli Piero , Contreras-Reyes Eduardo , Mancini Renzo , Osses Axel
Published: March 2020

We investigate the differences of the seismic source and aftershock activity using kinematic inversions and template matching respectively, for the six largest intraslab intermediate-depth earthquakes occurred in northern Chile (Mw ~6.3) since 2010 at depths between 90 and 130 km and recorded by dense strong-motion and broad-band seismic networks. In addition, we developed a thermal model using the finite element method in the study region with the aim of analyze the impact of temperature on seismic behavior as the oceanic plate subducts. Our results show that geometries of rupture zones are similar, with semi-axis for an elliptical patch approach about 5 km, and stress drop values between 7 and 30 MPa. On the other hand, the number of aftershocks exhibits clear differences, and their amount decreases with increasing the depth within the slab bounded by the 450 ºC isotherm, which represents a limit between a high-hydrated and a dry or low-hydrated region. Furthermore, mainshocks occur at distances from the top of the slab from 7 to 40 km, and all of them exhibit normal focal mechanisms suggesting that the extensional regimen deepens within the slab to the 700-750 ºC isotherm-depth. We suggest that in northern Chile the abrupt decrease of aftershocks in the lower part of the extensional regimen is caused by the absence of a hydrated slab at those depths.
The role of soil characteristics on measured and modelled carbon dioxide and energy fluxes for Arctic dwarf shrub tundra sites
Authors: Meyer Gesa , Humphreys Elyn , Melton Joe , Lafleur Peter , Marsh Philip , Detto Matteo , Helbig Manuel , Boike Julia , Voigt Carolina , Sonnentag Oliver
Published: March 2020

Four years of growing season eddy covariance measurements of net carbon dioxide (CO2) and energy fluxes were used to examine the similarities/differences in surface-atmosphere interactions at two dwarf shrub tundra sites within Canada’s Southern Arctic ecozone, separated by approximately 1000 km. Both sites, Trail Valley Creek (TVC) and Daring Lake (DL1), are characterised by similar climate (with some differences in radiation due to latitudinal differences), vegetation composition and structure, and are underlain by continuous permafrost, but differ in their soil characteristics. Total atmospheric heating (the sum of latent and sensible heat fluxes) was similar at the two sites. However, at DL1, where the surface organic layer was thinner and mineral soil coarser in texture, latent heat fluxes were greater, sensible heat fluxes were lower, soils were warmer and the active layer thicker. At TVC, cooler soils likely kept ecosystem respiration relatively low despite similar total growing season productivity. As a result, the 4-year mean net growing season ecosystem CO2 uptake (May 1 - September 30) was almost twice as large at TVC (64 ± 19 g C m-2) compared to DL1 (33 ± 11 g C m-2). These results highlight that soil and thaw characteristics are important to understand variability in surface-atmosphere interactions among tundra ecosystems.

As recent studies have shown, winter fluxes play an important role in the annual CO2 balance of Arctic tundra ecosystems. However, flux measurements were not available at TVC and DL1 during the cold season. Thus, the process-based ecosystem model CLASSIC (the Canadian Land Surface Scheme including biogeochemical Cycles, formerly CLASS-CTEM) was used to simulate year-round fluxes. In order to represent the Arctic shrub tundra better, shrub and sedge plant functional types were included in CLASSIC and results were evaluated using measurements at DL1. Preliminary results indicate that cold season CO2 losses are substantial and may exceed the growing season CO2 uptake at DL1 during 2010-2017. The joint use of observations and models is valuable in order to better constrain the Arctic CO2 balance.  
Learn to Teach: how hands-on activities can promote scientific learning across multiple levels of education
Authors: Afonso Isabel
Published: March 2020

The teachers that work Teaching Sciences are frequently confronted with some fundamental questions such as "How to promote interest in the scientific culture?" and "How to engage young students in the development of science and technology?".

An effective way of motivating students to the fascination of discovery in these fields is through hands-on methodologies. This pedagogical tool is valid at any teaching level, from the youngest kindergarten children to older high-school level teenagers.

These hands-on methodologies are the learning experiences where the student is the lead and author of their own learning. Through activities where he himself has to plan, create and construct products or prototypes, using his creation and creativity skills to solve an everyday problem. These hands-on activities  are integrated experiences and promote an understanding of reality in a more complex way, positively changing the teaching/learning process.

In this project, high-school finalists were challenged to develop the "Science in Kindergarten" project. This project consisted of creating a children's story where the scenes would be illustrated with practical activities, based on experiments in Physics and Chemistry, instead of the traditional pictures/illustrations. The story was narrated by the older students to the younger students and backed up with the execution of the hands-on activities, where the younger ones were encouraged to participate.

In the second stage of this project, the younger students made their records of these activities through drawings and other types of materials and their work was used to illustrate the book that was subsequently printed.

Recreational experiences and discoveries help to recover the motivation and interest of students in these learning subjects where they have little to no affinity or that they discarded when it came the time to choose a professional field. This project was a successful example on how to promote scientific curiosity and knowledge in multiple ages and education levels.

"You cannot create experience. You must undergo it." Albert Camus
ENSO sensitivity to radiative forcing
Authors: Predybaylo Evgeniya , Stenchikov Georgiy , Wittenberg Andrew , Osipov Sergey
Published: March 2020

To improve El Niño / Southern Oscillation (ENSO) predictions and projections in a changing climate, it is essential to better understand ENSO’s sensitivities to external radiative forcings. Strong volcanic eruptions can help to clarify ENSO’s sensitivities, mechanisms, and feedbacks. Strong explosive volcanic eruptions inject millions of tons of sulfur dioxide into the stratosphere, where they are converted into sulfate aerosols. For equatorial volcanoes, these aerosols can spread globally, scattering and absorbing incoming sunlight, and inducing a global-mean surface cooling. Despite this global-mean cooling effect, paleo data confirm remarkable warming of the eastern equatorial Pacific in the two years after a tropical eruption, with a shift towards an El Niño-like state. To illuminate this response and explain why it tends to occur during particular seasons and ENSO phases, we present a unified framework that includes the roles of the seasonal cycle, stochastic wind forcing, eruption magnitude, and various tropical Pacific climate feedbacks. Analyzing over 20,000 years of large-ensemble simulations from the GFDL-CM2.1 climate model forced by volcanic eruptions, we find that the ENSO response comprises both stochastic and deterministic components, which vary depending on the perturbation season and the ocean preconditioning. For boreal winter eruptions, stochastic dispersion largely obscures the deterministic response, being the largest for the strong El Niño preconditioning. Deterministic El Niño-like responses to summer eruptions are well seen on neutral ENSO and weak to moderate El Niño preconditioning and grow with the eruption magnitude. The relative balance of these components determines the predictability and strength of the ENSO response. The results clarify why previous studies obtained seemingly conflicting results.
Iron-reducing bacteria play a key role in lignin degradation by electron transferring from soil organic matter
Authors: Merino Carolina , Matus Francisco , Kuzyakov Yakov , Jofré Ignacio , Najera Francisco
Published: March 2020

Electron acceptors (NO3–, SO42–, Fe3+, Mn4+) play a crucial function in the oxidation of soil recalcitrant organic compounds. Soils that present large amount of total Fe (8-57 g kg-1soil) and organic (C) (10-110 g kg-1soil), iron-reducing bacteria (IRB)  may play a importan role. In the present study we hypothesized that IRB which reduce Fe(III)(oxyhydr)oxide of low solubility to soluble Fe(II), can contribute substantially to the degradation of lignin from soil organic matter (SOM). The aim of this study was to isolate IRB and evaluate their importance in lignin degradation. IRB were obtained from topsoils of different climates (humid temperate, cold temperate, subpolar), vegetation type (steppe, rainforest) and parent materials (granitic, volcanic, fluvio-glacial, basaltic-Antartic and metamorphic). The potential of IRB to reduce Fe(III) was assessed with lactate substrate as source of carbon (C) and anthraquinone-2,6-disulfonate (AQDS) as electron acceptor. The contribution of IRB to lignin degradation was assessed in an anaerobic microcosms experiment for 36 h. The CO2 efflux from sterilized and reinoculated soil with IRB was compared with sterilized (abiotic), non-sterilized (biotic) and induced Fenton reaction. Lignin degradation by IRB was examined by: 1) bacterial growth containing alkali lignin and alkali lignin disappearance during incubation, 2) Lignin peroxidase and manganese peroxidase activities originated from IRB, 3) cells abundance estimated from ATP synthase from bacteria growing in alkali lignin and 4) lignin degradation monitored by fluorescence disappearance intensity. The major microbial group for Fe(III) reduction, as essayed by PLFA and nested-PCR and sequencing different species were Geobactericeae-strains (G. metallireducens and G. lovleyi) in all studied. The CO2 respiration in reinoculated soils was 140% higher than the CO2 release by abiotic and Fenton reaction and, 40% lower than biotic treated soil. The Fe(II) extractable in HCl in soil derived from basaltic-Antarctic parent material showed 362 % more Fe(II) solubilisation than that of biotic treatment. Fluorescence intensity decreased during lignin degradation and it was closely correlated with CO2 release in the same sample. We conclude that IRB community such as Geobacter spp. Uses intensively Fe(III) as an electron acceptor to oxidize lignin compounds, and this process is especially active in Fe rich soils.
The Western Canada Sedimentary Basin energy wells: δ13C gas isotopic mapping, from production to ground migration
Authors: Gonzalez Arismendi Gabriela , Muehlenbachs Kalis
Published: March 2020

Despite the emerging new technology in renewables, society still relies overwhelmingly on fossil fuels for energy. Overall, data indicate that there is an increase in natural gas production as a less expensive, more “environmentally friendly” and efficient resource.  ẟ13C studies are a standard tool to understand the origin, migration and mixing of natural gases. In the Western Canada Sedimentary Basin (WCSB), which is a major hydrocarbon producer, the isotopic variability of formations gases have been well characterized (i.e., Tilley and Muehlenbachs, 2006). Industry implements such information for predicting where economically substantial amounts of natural gas form. Ethane isotopic fingerprinting is more diagnostic of such thermally matured gases. Thus, it is a useful tool to identify unwanted fugitive gas emissions associated with petroleum resource development and activities. In an initiative to better understand, constrain and ultimately mitigate this historic engineering challenge, we contoured the isotopic values of 2800 SCV wells and 1200 GM, and used the production data to identify the source of gas emissions. Our outcomes are not only valuable to industry, but also to regulatory agencies to increase awareness about the use of organic (e.g. n-alkanes) and inorganic (e.g. CO2) carbon isotope fingerprinting as retrospective environmental indicators at a local and regional scale.

Reference:

Tilley, B., and Muehlenbachs, K. (2006). Gas maturity and alteration systematics across the Western Canada Sedimentary Basin from four mud gas isotope depth profiles. Organic Geochemistry, 37(12), 1857–1868.
Advanced Bridge Monitoring Strategies by Polarimetric GB-SAR
Authors: Zou Lilong , Sato Motoyuki , Tosti Fabio , Alani Amir M.
Published: March 2020

Use of advanced health monitoring strategies for bridges is essential to provide a comprehensive condition assessment of these structures and ensure their structural integrity. To this purpose, new technologies have been applied in recent years for both static and dynamic assessments offering unprecedented opportunities within the context of risk management and structural analysis. Among these, areal deformation measurement techniques from ground-based synthetic aperture radar (GB-SAR) sensors were successfully applied for continuous monitoring of dynamic and static displacements of bridges [1] [2]. However, a main limitation for the ground-based microwave interferometry is that, as a linear measurement technique, it is difficult to pinpoint the damage location and obtain accurate displacement time-series for bridges [3]. Moreover, it is known that vertical displacements are usually more relevant than horizontal displacements in the dynamic monitoring of bridges, and the GB-SAR interferometry can only provide the line-of-sight (LOS) displacement of the monitored bridge [4].

In this research, we focus on remote monitoring of the dynamic displacement responses of bridges with a polarimetric GB-SAR system. To this purpose, various strategies were used to overcome the existing limitations of this technique. Results from the monitoring of a long-span metallic railway bridge and a reinforced concrete Shinkansen bridge are discussed.

The aim of this research is to provide more comprehensive and accurate information for bridge health monitoring using a polarimetric sensor. To this extent, a polarimetric analysis was performed to identify the reflection from the side surface of the bridges. In addition, the information about the polarisation orientation angle and the local incidence angle were processed under the acquisition geometry to calculate the radar look angle. Therefore, the bridge deformation fields in the vertical direction were easily converted using the slant range distances and the corresponding maximum transient vertical deformation was transformed through the LOS deformation while a train passing the bridge.

 

References

[1] Monserrat, O. et al., 2014. A review of ground-based SAR Interferometry for deformation measurement. ISPRS Journal of Photogrammetry and Remote Sensing, pp. 40–48.

[2] Pieraccini, M. et al., 2006. Dynamic monitoring of bridges using a high-speed coherent radar. IEEE Transaction Geoscience and Remote Sensing, pp. 3284–3288.

[3] Sato M., Zou L., Nico G., 2017. Monitoring of Infrastructure by GB-SAR. IEICE technical report, pp. 11-16.

[4] Sato M., Zou L., Nico G., Kikuta K., 2019. Displacement and Vibration Monitoring by GB-SAR. IEICE Transactions on Communications, pp.844-852.
Understanding moisture transport associated with strong cyclones in the New Arctic
Authors: Boisvert Linette , Grecu Mircea , Shie Chung-Lin
Published: March 2020

The Arctic climate system is undergoing rapid and drastic change in recent decades, with the thinning and loss of sea ice coverage and a warming and moistening atmosphere since the 2000’s; coining the term the ‘New Arctic’. This New Arctic ice pack is more vulnerable to external forcings, and with the increase in open water and warmer temperatures it is suggested that this could impact the moisture transport into the Arctic. In fact, all aspects of the hydrologic cycle are likely affected by and also feedback on these large and rapid changes in the New Arctic. However, the majority of the precipitation and moisture transported into the Arctic Ocean is that associated with cyclones, but one caveat is that the true magnitude of precipitation during these events remain uncertain, and a better understanding of the intensity, frequency, and phase of this precipitation is critically needed specifically for the freshwater and energy budget of the New Arctic.

 

Our work aims to track the moisture and precipitation associated with strong cyclones that terminate in the Arctic in order to improve our knowledge of the frequency, intensity and phase of the moisture, how and if it is changing in the New Arctic on an annual, seasonal and regional basis. In order to do this we will create a database of strong Arctic cyclone trajectories and Lagrangian track the moisture associated with them using ERA-Interim reanalysis. To balance the moisture budget we will constrain the net precipitation using NASA GPM precipitation and AIRS evaporation data at each time step. We propose a novel approach to achieve a more comprehensive, balanced moisture transport associated with Arctic cyclones in an Optimal Estimation and Lagrangian Framework (OELaF) allowing for the fundamental moisture processes associated with Arctic cyclones to be better observed and investigated. In this new work, we plan to apply this method with a few cyclones in the winter months of 2015-2017.

 
The spatial and temporal characteristics of precipitation and the key contributing factors in the Loess Plateau since the implementation of Green for Grain Project
Authors: Gao Xuerui , Wang Jichao , Wang Yubao , Zhao Xining , Zhao Yong , Sun Miao
Published: March 2020

      Since the implementation of Green for Grain Project (GFGP) in the 1990s, the precipitation in the Loess Plateau has increased significantly. The warming and wetting trend in this area is becoming statistically significant. However, the correlation between precipitation increase and regional vegetation restoration is still controversial. To explore the main factors influencing the regional precipitation change, this study selected 6 main contributing factors of the precipitation in the Loess Plateau based on the cloud-precipitation physics and used the statistical methods to analyze the long-term change trend and the spatial and temporal distribution of precipitation in the Loess plateau before and after GFGP and to quantify the contribution rate of different factors to precipitation change in this area. The results show that: 1) the precipitation increased significantly (95% confidence level) after Green for Grain Project since 1999, with an increase rate of 4.96 mm/a; 2) From the perspective of spatial and temporal distribution, the precipitation in the southern part of the Loess plateau was significantly increasing with an increase rate of 20-50mm in the period of 2000-2015 compared with the average annual value in the base period (1985-1999). Among them, the summer precipitation increased significantly, while the winter precipitation changed non-significantly; 3) The contribution analysis shows that the summer precipitation in the Loess Plateau is mainly affected by regional actual evapotranspiration (AET) and vegetation coverage (NDVI) after GFGP, with the contribution rates of 27.1% and 40.0%, which respectively indicates that the summer precipitation in the Loess Plateau increased mainly due to the regional vegetation restoration and the associated ET increase. The winter precipitation in the Loess Plateau is mainly affected by the precipitable water (PW) in the air and water vapor flux (VF), with the contribution rates of 33.5% and 31.7%, which indicates that the winter precipitation is mainly affected by atmospheric circulation and transport of external water vapor. Based on this study, we speculate that the warming and wetting trend of Loess Plateau in recent years is not only closely related to global climate change, but also significantly affected by local climate change brought by vegetation restoration. The above conclusions are important for future ecological restoration and water resources management in the water-scarce Loess Plateau.
Towards large-scale characterization of subsurface vulnerability due to agrochemical pollutants across Europe
Authors: Kumar Rohini , Hesse Falk , Rao Suresh , Musolff Andreas , Jawitz James , Sarrazin Fanny , Samaniego Luis , Fleckenstein Jan , Rakovec Oldrich , Thober Stephan , Attinger Sabine
Published: March 2020

Subsurface contamination due to diffuse agrochemical pollutants such as pesticides, herbicides, excess nutrients (N, P, K) is a widespread problem in a cultivated areas across Europe. Large-scale spatio-temporal patterns emerge from interplay of heterogeneous and dynamic hydrologic and biogeochemical processes in the near-surface critical zone (top one-meter of root-zone soil layer) which contribute to landscape filtering of stochastic hydro-climatic forcing. Such outcomes are of interest in characterizing the transient behavior of transport-reaction dynamics operating in the root-zone soil compartment which drive recharge and solute loads to sub-surface compartments (shallow groundwater and eventually to river networks).  Here, using novel state-of-the art daily-scale hydrologic simulations (mHM; around 5x5 km grid) driven by observed hydro-climatic forcing, we demonstrate the strong spatio-temporal heterogeneity of hydrologic transport at the continental scale – reflected in time-varying travel time distributions (TTDs) – primarily controlled by the prevailing hydro-climatic gradient of aridity index across Europe. We link the space-time dynamics of TTDs – representing the intrinsic vulnerability of hydrologic system - to spatial heterogeneity and temporal fluctuations of biogeochemical turnover time-scales to provide a parsimonious  biogeochemical model for identifying the extent of subsurface contamination due to diffuse (agrochemical) pollutants. Our assessment results show a large increase in the extent of vulnerable areas that are prone to subsurface nitrate leaching across Europe, compared to current (static) indices based approaches. We highlight the implications of improved vulnerability maps to better support agricultural subsidies and nitrate management across Europe. 
How the Andean tectonics and dynamic topography shaped the landscape evolution in Amazonia: a numerical approach
Authors: Sacek Victor , Cordeiro Bicudo Tacio , Paes de Almeida Renato
Published: March 2020

The Andean orogeny had a profound impact on the evolution of the Amazon drainage system, modifying the climate in South America and the influx of sediments to the interior and marginal sedimentary basins. Additionally, the subduction of the Nazca plate under the continent produced dynamic topography that perturbed the landscape and the generation of accommodation space in the interior sedimentary basins mainly in western Amazonia. Therefore, the correct interpretation of the geological evolution of the northern South America during the Cenozoic depends on the coupling of different geodynamic processes with the erosion of the continents, deposition in the sedimentary basins and the interaction with the evolving climate. Due to the great complexity of the different processes involved in the geological evolution of Amazonia, the use of numerical models is a natural way to treat this problem. The aim of this work is to present numerical scenarios for the formation and evolution of the Amazon drainage system taking into account surface processes along with geodynamic processes like Andean uplift, flexure of the lithosphere, and dynamic topography induced by mantle convection. We conclude that the Amazon drainage system was formed essentially by the asymmetric influx of sediments from the Andes, while the dynamic topography modulated the timing for the transcontinental connection between western and eastern Amazonia and the stratigraphic evolution of interior basins.
Determination of Coastal Sea Level Heights around Taiwan by improved GNSS Reflectometry
Authors: Lee Chi Ming , Hung Shao Lun , Kuo Chung Yen , Sun Jian , Tseng Tzu Pang , Chen Kwo Hwa , Shum Ck , Yi Yuchan , Ching Kuo En
Published: March 2020

Rapid sea level rise, a severe consequence of global warming, could significantly damage the lives and properties of numerous human beings living in low-lying coastal areas. Therefore, realizing and monitoring coastal sea level variations are of great importance for human society. Conventionally, sea level heights are measured by using tide gauges; however, the records are contaminated by vertical land motions which are difficult to be separated. Recently, Global Navigation Satellite System Reflectometry (GNSS-R) technology has been proved to effectively monitor the coastal sea level changes from GNSS signal-to-noise ratio (SNR) data. However, the generation of detrended SNR ( SNR) depending on different satellite elevation angle intervals via a quadratic fitting, considerably influences the accuracy of sea level retrievals. Moreover, the quadratic fitting cannot perfectly describe the trend of SNR data. Therefore, we proposed a method combining ensemble empirical mode decomposition (EEMD) and ocean tide model to compute SLHs. EEMD can decompose the original SNR data into several intrinsic mode functions (IMFs) corresponding to specific frequencies. Then, Lomb-Scargle Periodogram (LSP) is applied to calculate the dominant frequency of the IMF with maximum spectral power. EEMD is not only suitable for dealing with nonlinear and nonstationary data but also eliminates the mode mixing problem of empirical mode decomposition (EMD) by adding white noises. In addition, we set an empirical SLH interval from ocean tide model as a quality control. In this study, the existing GNSS stations at the coasts of Taiwan are used to examine the proposed approach and then compare the results with those from the traditional quadratic fitting. Finally, the measurements from co-located or nearby traditional tide gauges are served as ground truth to evaluate the accuracy and stability of the mentioned methods.
Model investigation into rain enhancement by hygroscopic seeding in mixed-phase convective clouds
Authors: Tonttila Juha , Kokkola Harri , Raatikainen Tomi , Ahola Jaakko , Korhonen Hannele , Romakkaniemi Sami
Published: March 2020

Intentional release of large hygroscopic particles in a cloud, i.e. cloud seeding, is potentially capable of increasing rain formation. In this work, we focus on convective clouds of moderate intensity observed over the United Arab Emirates, where we use a large eddy simulator coupled with detailed bin aerosol-cloud microphysics module (UCLALES-SALSA) to study the processes controlling the seeding efficacy. Despite numerous field experiments, the conditions that favor efficient seeding induced rain enhancement are not well characterized. Models such as UCLALES-SALSA provide the means to study the microphysical effects in varying ambient conditions in a controlled setting. The clouds targeted by our simulations have a mixed-phase component and rain is primarily produced by the cold precipitation process. The results show that the fast growing droplets formed by the relatively large hygroscopic seeding aerosol affect the riming process in the mixed-phase region inside the clouds. The collision rate between the hydrometeors in the mixed-phase region is enhanced, producing larger frozen particles. Consequently, the ice tends to get more heavily rimed, as indicated by the fraction of rimed ice from the total ice mass, which promotes increased particle fall velocities.

 

However, the impact of seeding on the riming process depends on the state of the cloud and its environment. In conditions already favoring high rime fraction, often associated with relatively strong surface precipitation events, the effect of seeding is hindered, at least in terms of relative difference. Nevertheless, even if the effect of seeding on the total precipitation yield is small, it may still affect the timing of the precipitation onset, a topic currently under investigation. Work is also in progress to characterize the dependence between ambient conditions (in terms of aerosol and the thermodynamic properties of the atmospheric column) and the susceptibility of the mixed-phase clouds to seeding injection.
Ensemble Streamflow Assimilation with Coupled WRF-Hydro and DART
Authors: Noh Seong Jin , McCreight James , El Gharamti Moha , Hoar Tim , Rafieeinasab Arezoo , Johnson Benjamin
Published: March 2020

The Data Assimilation Research Testbed (DART) has been coupled with the community WRF-Hydro modeling system with the intent of providing efficient and flexible support for assimilating a wide range of streamflow and soil moisture observations and delivering an ensemble of model states useful for quantifying streamflow uncertainties. The coupled framework, named Hydro-DART, is used to study and assess the flooding consequences of Hurricane Florence over the Carolinas during August-September 2018 period.
Several extensions to earlier versions of Hydro-DART have been explored. These include: (1) a multi-configuration ensemble in which different ensemble members are run with different physical parameters (e.g., Manning's roughness and channel geometry) in order to create additional ensemble variability, (2) a variable transform, anamorphosis, which is introduced such that bounded quantities (e.g., streamflow) are transformed to a Gaussian space prior to the Kalman update as a way to avoid non-physical state updates, (3) a spatially-correlated noise, which is introduced to represent uncertainty of input forcings (e.g., overland and subsurface fluxes) in a physically meaningful way, and (4) an along-the-stream localization, which considers precipitation correlation length scale, rather than physical proximity. Hourly streamflow gauge data, from the flood-affected area, is used to test the impact of these extensions on the overall prediction accuracy. Analyses and hindcasts are compared to those based on the nudging assimilation currently employed in the National Water  Model (NWM) operations. Standard streamflow forecast metrics are also supplemented by a wavelet-based event timing error metric.
Pragmatic, fast and easy to use Model for Predicting Susceptibility to Concentrated Flow Erosion in a GIS in data-sparse regions
Authors: Mgbanyi Liberty Lazrus Orapine , Johnson Matthew , Thorne Colin
Published: March 2020

Less Economically Developed Countries (LEDCs) are at particular risk of gullying due to climate change, land-use change, poor agricultural practices and widespread farming intensification, but in these areas, the data required to apply most predictive models are usually unavailable. Therefore, an urgent need for a practical and rapid predictive tool for assessing gullying potential in data-sparse regions, to inform planning, agricultural practices and environmental management decision-making is required. Given the difficulty in applying existing empirical models to developing areas, where input data is sparse, but the risk of gullying is high, alternative methods need to be developed to identify areas susceptible to gullying. Here it is hypothesised that detailed data is required to apply existing models of soil loss from agricultural areas because they focus on predicting the quantities of sediment lost after agriculture has commenced. The data requirements for successful model application could be less if the focus were instead on identifying areas that are susceptible to gullying.  The decision to avoiding soil loss by either protecting them from agricultural development or at least applying soil conservation measures from the outset, without attempting to predict the extents or the specific metre-scale locations of individual gully channels will come much handy. The Compound Topography Index (CTI) meets the criteria for that candidate predictive model for concentrated flow erosion in the data-sparse regions. The CTI, however, required quality and high-resolution data(<5m LiDAR DEMs) available in data-rich regions to perform, but with weak quality and low-resolution data(30m DEM) found in the data-sparse regions, fuzzy logic data applied to this data before using it as input into the CTI model to at least on identifying areas that are susceptible to gullying. The accuracy of the model was moderately improved when used with high-resolution data, and consistent in prediction for coarse resolution DEMs. A key finding is that the fuzzy CTI reveals that much of the landscape has the potential to suffer gullying – i.e. there is sufficient planform and profile curvature to concentrate and accelerate overland flow. Soil degradation and loss of soil structure, or removal of natural vegetation and, especially forests, could exacerbate the condition rapidly lead to widespread gullying based on the occurrence of concentrated overland flow driven by the topography, while the incorporation of soil structural stability index in the fuzzy CTI slightly improved it performance as per modelling concentrated flow erosion. The calculation of CTI is easy, repeatable, require less comprehensive, sophisticated data collection and not over extended periods and could widely be an applicable predictor of gullying, for use in sparse data regions.
The Deflection Magnet Design for PKU Energetic Particle Instrument
Authors: Shi Weihong , Yu Xiangqian , Wang Yongfu , Wang Linghua , Huang Xin , Liu Zixuan
Published: March 2020

The Energetic Particle Instrument (EPI), proposed by Peking University for a L1 mission, is designed to provide the three-dimensional distribution of suprathermal electrons and ions with good time, energy and angular resolutions in the interplanetary space, respectively, at energies from 20 keV to 1 MeV and from 20 keV to 11 MeV.  The EPI consists of four dual-double-ended foil/magnet semi-conductor telescopes, which cleanly separate electrons in the energy range from 20 to 400 keV and ions from 20 keV to 6 MeV.

The magnet of semi-conductor telescopes consists of four type 677H rare earth permanent magnets and a soft iron frame. Due to the high saturation polarization and high magnetic anisotropy of the Nd2Fe14B strongly magnetic matrix phase, this system can make the magnetic field strong enough to make the electrons deflected.

A frame made of iron-cobalt alloy VACOFLUX 50 will be able to combine two pairs of magnets and cause the magnetic field to decay rapidly in the far field. In this way, the two air gaps in the system can simultaneously provide a deflecting magnetic field for a pair of anti-parallel sensor systems.
High Resolution Modeling of a Mountain Glacier in the Chilean Patagonia
Authors: Navarrete Héctor , Somos-Valenzuela Marcelo , Fustos-Toribio Ivo
Published: March 2020

Changes in climate are dramatically shaping the planet, imposing new conditions, and constraints on water systems that are not easy to foresee. The need for an integrated application of methodologies that links advances in climatology with hydrology and water management is now undeniably necessary. Given the latitude of the Chilean Patagonia, the effects of climate change are beginning to show more dramatically. However, there are analogous examples of glaciated systems in other parts of the world that can offer valuable insight into the effects that increases in temperature would have on the evolution of river flows in Patagonia. Where glaciers are present, stream flows are positively/negatively correlated with temperature/precipitation. In equilibrium, glaciers regulate river flows by smoothing the annual streamflow variations.  In the Chilean Patagonia, significant attention has been given to the evaluation of lake formation and the impacts of potential Glacier Lakes Outburst Floods, and studies of glacier melting contribution to sea-level rise. In this study, we will use the Weather Research Forecast Hydro (WRF-Hydro) with the Crocus snow/glacier module to model the Paulina glacier hydrology and to estimate the streamflow in the NEF river basin. We use a nested watershed to study and parameterize the models in high resolution. We carried fieldwork to collect streamflow and climate data to calibrate and correct the model results. We used an Unmanned Aerial Vehicle (UAV) to generate a high-resolution elevation model of the glacier terminal, as well as the use of Landsat imagery to determine changes in the glacier area, snow line, and ASTER imagery to determine changes in thickness.

Our expected result is the quantification of the volume contribution of freshwater from a small mountain glacier. Further, we will use this parameterization at a regional setting to evaluate the potential of transferring parameters from a small glacier watershed to a broader context in the Baker River Basin in the Chilean Patagonia.