bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Conjugated Chlorophyll from Natural Dye (Imperata cylindrica) to Apply in Hybrid DSSC as Third Generation Solar Energy
Authors: Ishak Nurhayati , Salleh Hasiah , Rahman Salisa Abdul , Dagang Ahmad Nazri , Kamarulzaman Nurul Huda , Ahmad Zakiyah , Abd Majid Siti Nurhaziqah , Ghazali Salmah Mohd
Published: March 2020

High performances of Hybrid Dye Sensitized Solar Cell are necessary in absorbing more sunlight and needed renewable energy source to replace depleted fossil fuels via green energy. Hybrid DSSC is another promising option towards green energy to explore. This research aims, i) to study conjugated chlorophyll in order to increase charge carrier in molecule structure besides, increase the absorption spectrum via conjugating process with the addition of different amount Ferric (III) Chloride (FeCl3) acting as catalyst and, ii) to determine the effect of FeCl3 on the performance of conjugated dye as sensitizers in Hybrid DSSC. The conjugated chlorophyll shows a using UV-Visible analysis corresponding to conjugated chlorophyll absorbed in high region called red shifted which the maximum absorption obtain at a wavelength of 360nm and 311nm. Fourier Transform Infra-Red characterization of the an existing Fe-O bond appears at 430 cm-1 to 445 cm-1 and C≡C bond at 2244 cm-1 to 2260 cm-1. 10% FeCl3 in conjugated chlorophyll produce huge impact to electrical conductivity and efficiency with the highest value; 0.114 S/cm and 0.14%; respectively. Thus, it can be conclude that 10% FeCl3 of conjugated chlorophyll – Imperata cylindrica (iCHLO-IC) was suitable to be used for the next generation of hybrid DSSC.
Broadband Anti-Reflection in Black Silicon Fabricated by Two-Step Silver-Assisted Wet Chemical Etching for Photovoltaics
Authors: Abdulkadir Auwal , Md. Noor Nur Afidah , Aziz Azlan Abdul , Pakhuruddin Mohd Zamir
Published: March 2020

This paper reports broadband anti-reflection in black silicon (b-Si) fabricated by two-step metal-assisted chemical etching (MACE) for potential photovoltaic (PV) applications. The method involves deposition of silver nanoparticles (Ag NPs) in aqueous solution of HF:AgNO3, followed by etching in HF:H2O2:DI H2O solution for different duration (10-25 s). Effects of etching time towards surface morphological and optical properties of b-Si nanowires are investigated. Surface morphological characterization confirms presence of b-Si nanowires with heights of 350-570 nm and diameter of 150-300 nm. The b-Si nanowires exhibit outstanding broadband anti-reflection due to refractive index grading effect. This is represented as weighted average reflection (WAR) in the 300-1100 nm wavelength region. After 20 s of etching, b-Si nanowires with height of 570 nm and width of about 200 nm are produced. The nanowires demonstrate WAR of 5.5%, which represents the lowest WAR in this investigation. This results in absorption of 95.6% at wavelength of 600 nm. The enhanced broadband light absorption yields maximum potential short-circuit current density (Jsc(max)) of up to 39.7 mA/cm2, or 51% enhancement compared to c-Si reference. This facile b-Si fabrication method for broadband enhanced anti-reflection could be a promising technique to produce potential PV devices with high photocurrent.
Impact of Eu Nanoparticles Substitution for Ca Site in Bi(Pb)-2223 Cuprates Superconductor
Authors: Nurbaisyatul E.S. , Azhan H. , Azman Kasim , Ibrahim Norazila , Saipuddin Siti Fatimah
Published: March 2020

The sample with nominal composition of Bi1.6Pb0.4Sr2Ca2-xEuxCu3Oy where x = 0.000, 0.0025, 0.020, 0.050 and 0.100 were synthesized through solid state reaction method. The effect of Eu2O3 nanoparticles doping on the superconducting and structural properties were studied by means of critical temperature, TC, critical current density, JC, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The amount of 2223 phase gradually decreased with the increment of Eu concentration which indicates that Eu nanoparticles substitution at Ca site favours the growth of 2212 phases. The sample with higher porosity was found to be decreased in critical temperature, TC as well as critical current density, JC due to the lack of effective surface area for current flowing. The best superconducting properties were observed at x = 0.0025 substitutes into Ca site for Bi (Pb)-2223 host sample.
Study on Effect of Fiber Orientation on Flexural Properties of Glass Fiber Reinforced Epoxy Composite Laminates for Structural Applications
Authors: Marzuki Haslan Fadli Ahmad , Ubaidillah Engku Ahmadhilmi Engku , Sivarasa Sivakumar A/l , Syamsul Mohd , Jaafar Mariatti
Published: March 2020

Composite laminate design is an important procedure in defining the mechanical properties of laminated composite structure to be used in multi-directional service loading application. Composite technologies or manufacturers who is lack of knowledge regarding the importance of laminate design, tend to develop a composite structure that will collapse or fail below the service requirement. The purpose of this study is to determine the effect of fiber orientation on flexural properties of the designed glass fiber reinforced epoxy laminated composite. Six sets of laminates with different fiber orientation and sequence were simulated using CompositeStar© software to determine its flexural properties. Samples were fabricated to verify the simulated data and were tested in accordance to ASTM D2344. Moreover, crack pattern within the samples after the flexural test is studied. From the simulated results, it shows that laminates which have fiber in tri-direction and quasi-direction display a higher flexural modulus and strength compared to laminates with fiber in uni-directional and bi-directional. In addition, data from tested fabricated laminates samples displayed the same modulus patterns against the simulated data, with variants from 8% to 35%. Additionally, it is found that samples with fiber in ±45 direction shows a transverse and shear cracking which prolonged the cracking propagation before the samples show a complete failure.
Agarose-Chitosan Based Hydrogel Waveguide Matrix: Comparison Synthesis and Performance for Optical Leaky Waveguide (OLW) Biosensor
Authors: Makhsin Siti Rabizah , Gardner Peter , Goddard Nicholas J. , Scully Patricia J.
Published: March 2020

In this work, a hydrogel-based optical leaky waveguide (OLW) biosensor was developed to detect biomolecules using changes in refractive index (Dn). Hydrogels formed from chitosan and agarose were synthesised to be used as a waveguiding thin film in OLW biosensor. The concentration and thickness of the hydrogels defined by the spin coater speeds and time were optimised to produce a device chip with a single waveguide moded operation of OLW biosensor. The cladding layer was fabricated using 9.5nm titanium coated glass substrate for metal-clad (MCLW) and addition of dye particles (reactive blue 4) for dye-clad (DCLW) format. For the performance of the fabricated device for detection of Dn of a glycerol solution, the highest sensitivity of detection was obtained from MCLW chip made of 2% w/v of chitosan-agarose hydrogel spun at 6000 rpm with LOD: 4.28 x 10–6 RIU, while for DCLW format, the LOD measured at 7.46 x 10–6 RIU. The performance of the device to monitor the protein (bovine serum albumin; BSA and anti-BSA) interaction, the binding affinity in respect of change in peak angle (DӨ°) of chitosan matrix to the protein was measured at DӨ°~(6.2 ± 0.5°)x10–6.
Establishment and Validation of a Nomogram for Nasopharyngeal Carcinoma Patients Concerning the Prognostic Effect of Parotid Lymph Node Metastases
Authors: Lin Chao , Sun Xue-Song , Liu Sai-Lan , Li Xiao-Yun , Lu Nian , Li Xin-Ling , Tang Lin-Quan , Guo Ling
Published: March 2020

Purpose The prognosis of nasopharyngeal carcinoma (NPC) patients with parotid lymph node (PLN) metastasis remains unclear. This study was performed to investigate the prognostic significance and optimal staging category of PLN metastasis and develop a nomogram for estimating individual risk.Materials and MethodsClinical data of 7,084 non-metastatic NPC patients were retrospectively reviewed. Overall survival (OS) was the primary endpoint. A nomogram was established based on the Cox proportional hazards regression model. The accuracy and calibration ability of this nomogram was evaluated by C-index and calibration curves with bootstrap validation.ResultTotally, 164/7,084 NPC patients (2.3%) presented with PLNs. Multivariate analyses showed that PLN metastasis was a negative prognostic factor for OS, progression-free survival (PFS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRFS). Patients with PLN metastasis had a worse prognosis than N3 disease. Five independent prognostic factors were included in the nomogram, which showed a C-index of 0.743. The calibration curves for probability of 3- and 5-year OS indicated satisfactory agreement between nomogram-based prediction and actual observation. All results were confirmed in the validation cohort.ConclusionNPC patient with PLN metastasis had poorer survival outcome (OS, PFS, DMFS, and LRFS) than N3 disease. We developed a nomogram to provide individual prediction of OS for patients with PLN metastasis.
Utility of ‘dual phase’ cone beam computed tomography during radioembolisation in patients with hepatocellular carcinoma: what is really changing in flow dynamics before and after 90Y delivery?
Authors: Gormez Aysegul , Gonca Eldem Fatma , Volkan Salanci Bilge , Fani Bozkurt Murat , Ugur Omer , Peynircioglu Bora
Published: March 2020

Introduction

The aims of the study were: 1) to compare two phases of dual-phase cone beam computed tomography (DP-CBCT) achieved before and after Yttrium-90 (90Y) administration and to evaluate additional benefits during radio­embolisation (RE) procedures; and 2) to compare DP-CBCT with pre-procedure contrast enhanced cross-sectional images in terms of tumour detection.

Material and methods

Twenty-three hepatocellular carcinoma patients undergoing RE treatment were scanned with DP-CBCT consisting of early arterial (EA) and late arterial (LA) phases before and after 90Y administration. The CT-like datasets were compared according to embolisation effect, enhancement patterns, lesion detectability, image quality, and artifacts by two interventional radiologists blinded to each other. The compatibility of the two radiologists was evaluated with kappa statistical analysis, and the difference between EA and LA phases was evaluated with marginal homogeneity test. Also, DP-CBCT images were compared with preprocedural cross-sectional images (CT/MRI).

Results

For 23 patients 92 data were acquired. Thirteen patients showed a decrease on post-embolisation images both visually and on Hounsfield unit (HU) measurements. No statistical difference was found for tumour detection between EA and LA phases (p = 1.0). Tumour enhancement was visually superior at LA phases whereas EA phases were better for arterial mapping for selective catheterisation. DP-CBCT images were not inferior to preprocedural cross-sectional imaging findings.

Conclusions

DP-CBCT is a promising tool for predicting tumour response to therapy and is not inferior to preprocedural cross-sectional imaging in terms of tumour detection. It allows better assessment during RE procedures because early phases provide good mapping for superselective catheterisation whereas late phases are better for visualisation of tumour enhancement.
Diagnostic accuracy of magnetic resonance imaging in the evaluation of pulmonary infections in immunocompromised patients
Authors: Singh Rashmi , Garg Mandeep , Sodhi Kushaljit S. , Prabhakar Nidhi , Singh Paramjeet , Agarwal Ritesh , Malhotra Pankaj
Published: March 2020

Introduction

To evaluate the accuracy of magnetic resonance imaging (MRI) for diagnosing pulmonary infections in immunocompromised adults.

Material and methods

Computed tomography (CT) and MRI chest were performed in 35 immuno-compromised patients suspected of pulmonary infection. The MRI sequences that were performed included axial and coronal T2 half-Fourier acquisition single-shot turbo spin-echo (HASTE), spectrally attenuated inversion recovery (SPAIR), true fast imaging with steady-state free precession (TRUFI), and three-dimensional fast low angle shot (3D FLASH) using breath-hold and respiratory triggered BLADE (proprietary name for periodically rotated overlapping parallel lines with enhanced reconstruction). The presence of nodules, consolidations, and ground-glass opacities was evaluated. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for MRI using CT scan as a reference standard.

Results

The sensitivity of MRI in nodule detection was 50% overall and 75% for nodules measuring more than 5 mm. Consolidation was detected with 100% sensitivity. Sensitivity and PPV for the detection of ground-glass opacities (GGOs) were 77.7% and 53.8%, respectively. T2 HASTE axial had the fewest image artefacts. Respiratory triggered MR pulse sequence did not add any significant diagnostic information as compared to the non-respiratory triggered MR pulse sequences.

Conclusions

Sensitivity for detecting small nodules and GGOs on MR is poor; CT scan remains the imaging modality of choice for the evaluation of pulmonary infections in immunocompromised patients. However, MRI can be used in the follow-up imaging of these patients.
Sources and sinks driving sulphuric acid concentrations in contrasting environments: implications on proxy calculations
Authors: Dada Lubna , Ylivinkka Ilona , Baalbaki Rima , Li Chang , Guo Yishou , Yan Chao , Yao Lei , Sarnela Nina , Jokinen Tuija , Daellenbach Kaspar R. , Yin Rujing , Deng Chenjuan , Chu Biwu , Nieminen Tuomo , Kontkanen Jenni , Stolzenburg Dominik , Sipilä Mikko , Hussein Tareq , Paasonen Pauli , Bianchi Federico , Salma Imre , Weidinger Tamás , Pikridas Michael , Sciare Jean , Jiang Jingkun , Liu Yongchun , Petäjä Tuukka , Kerminen Veli-Matti , Kulmala Markku
Published: March 2020

Abstract. Sulphuric acid has been shown to be a key driver for new particle formation and subsequent growth in various environments mainly due to its low volatility. However, direct measurements of gas-phase sulphuric acid are oftentimes not available, and the current sulphuric acid proxies cannot predict for example its nighttime concentrations or result in significant discrepancies with measured values. Here, we define the sources and sinks of sulphuric acid in different environments and derive a new physical proxy for sulphuric acid to be utilized in locations and during periods when it is not measured. We used H2SO4 measurements from four different locations: Hyytiälä, Finland; Agia Marina, Cyprus; Budapest, Hungary; and Beijing, China, representing semi-pristine boreal forest, rural environment in the Mediterranean area, urban environment and heavily polluted megacity, respectively. The new proxy takes into account the formation of sulphuric acid from SO2 via OH oxidation and other oxidation pathways, specifically that via stabilized Criegee Intermediates. The sulphuric acid sinks included in the proxy are its condensation sink (CS) and atmospheric clustering starting from H2SO4 dimer formation. Indeed, we found that the observed sulphuric acid concentration can be explained by the proposed sources and sinks with similar coefficients in the four contrasting environments where we have tested it. Thus, the new proxy is a more flexible and an important improvement of previous proxies. Following the recommendations in the manuscript, a proxy for a specific location can be derived.
Flow trends in Western Hungary
Authors: Mátyás Kevin , Bene Katalin , Koch Róbert
Published: March 2020

Knowledge of available water resources is essential in water management and water policy. In accordance with the EU Water Framework Directive, Hungary reviews and updates its assessment of water balance through the River Basin Management Plan (RBMP) every 7 years. In many cases, the available water resources in the RBMP for small streams are based on expert judgment, since it is not always possible to measure the actual water level or discharge. Consideration of climate change and its effects is also a big question: what are the effects of these changes on small streams, and is there a trend in the runoff?

For water managers, water scarcity and abundance are major concerns. To address this issue, our study focused on high-flow and low-flow signatures. This paper presents flow trends during the last 36 years in Western Hungary. During the period 1980-2016, daily discharge measurements were collected at 74 small streams. Twelve flow signatures were selected for trend analyses. Trends were determined for three time periods: the full measured time period at each station, and two eighteen-year periods between 1980-1998 and 1999-2016. At each location, trends were determined with 10% significance using the Mann-Kendall test.

The results show that in the low-flow signatures, no significant changes in flow trends occur at the individual watershed and regional scales during the two eighteen-year time periods, as well as during the full time period. In contrast, high-flow signatures have significantly changed for all three time periods, at both the individual and regional scales.

This work was undertaken as part of a project funded by the EFOP-3.6.1-16-2016-00017.
Evolution and stratigraphy of the Nakdong River valley deposits in response to late Quaternary sea-level change
Authors: Yoo Dong-Geun , Hong Seok-Hwi , Lee Gwang-Soo , Kim Jin-Cheul , Kim Gil-Young , Choi Yun-Soo
Published: March 2020

Sequence analysis using borehole samples and high-resolution seismic data in the Nakdong River valley reveals that the Nakdong River valley deposits, approximately 60 - 70 m thick, consist of a set of lowstand, transgressive, and highstand systems tracts that corresponds to a fifth-order (20 ka) sea-level cycle. Four main depositional systems, including ten sedimentary facies, constitute these systems tracts: fluvial, estuary, coastal/shoreface, and delta. The lowstand systems tract (LST), consisting of gravelly sand, forms a fluvial depositional system (Unit I) which fills the thalweg of river valley mainly developed approximately before 12 ka. The transgressive systems tract (TST) can be divided into two depositional systems (Unit II and III). The river-derived sediments were trapped within the paleo-estuary, forming an estuarine depositional system (Unit II) developed between 12 and 6 ka. As the transgression continued, the coarse sediments were deposited and redistributed by coastal processes, resulting in coastal/shoreface depositional system (Unit III). It is characterized by an isolated sand body and thin sand veneer. The HST is composed of deltaic depositional system including delta plain, delta front, and prodelta (Unit IV). During the delta progradation, most coarse-grained sands derived from the river were deposited in the lower delta plain and delta front, forming sand bars and shoals less than 15 m deep. The remaining fine-grained sediments were transported further offshore in a suspension mode and deposited in the inner shelf off the present river mouth, forming a subaqueous prodelta. Radiocarbon and optically stimulated luminescence (OSL) dating suggest that the recent deltaic system was initiated by aggradational and progradational stacking patterns at approximately 8 ka during the last stage of decelerated sea-level rise, and was then followed by a prograding clinoform after the highest sea level at approximately 6 ka.
The MARVEL gravity and reference frame mission proposal
Authors: Lemoine Jean-Michel , Mandea Mioara ,   MARVEL Team
Published: March 2020

The "MARVEL gravity and reference frame mission" proposal has been selected by CNES for the start of a pre-phase A study. 
MARVEL aims at reaching in one single mission two major and complementary goals:
- The monitoring of mass transfers within the Earth system with increased precision,
- The realization, at the millimeter level, of the terrestrial reference frame.

In the nominal configuration, a LEO satellite (400 - 450 km) in polar orbit, acting as a gravity sensor, performs optical ranging measurements on two MEO satellites (7000 km) orbiting on the same plane. The MEO satellites are equiped with the four geodetic techniques (GNSS, SLR, DORIS, VLBI), in order to meet the GGOS Earth reference frame accuracy objectives.

We also propose two alternative (and less costly) configurations, where only the first goal is fully reached:
- one by replacing the MEO satellites by two or more cubesats on the same orbit,
- the second one by using specially equipped GNSS satellites as targets for the LEO optical ranging measurements.

In any case, the goal of monitoring mass change with enhanced precision is attained through the use of high-low SST laser tracking.

We will present in detail the different configurations proposed and present the simulation plan for this pre-phase A study.
Live fast-die young: Scaling CO​2 fertilization effects from leaf to ecosystem levels
Authors: Marques Laura , Weng Ensheng , Stocker Benjamin
Published: March 2020

Global environmental changes are rapidly altering the functioning and structure of terrestrial ecosystems.Particularly, rising CO2 atmospheric concentrations have been reported to increase photosynthesis by increasing carbon assimilation and water-use efficiency. This leaf-level CO2 fertilization effect may lead to an increase in the biomass stock in forest stands. However, previous studies argued that an enhanced tree growth rate is associated with a reduction in the longevity of trees, thus reducing the ability of forest biomass to act as carbon sinks over long timescales. In addition, faster growth may lead to an acceleration of self-thinning whereby tree density in the stand is reduced due to progressive mutual shading as tree crowns expand and a resulting increase in shaded individuals’ mortality. Nevertheless, previous results relied on empirical relationships between tree growth rates and longevity, without considering any positive effects of elevated CO​2 on individual tree’s carbon balance. Individual-based forest datasets such as tree ring width data and forests inventories have been widely used to monitor long-term changes in forest demography. Yet, the mechanistic underlying these processes remains poorly understood and challenges persist in upscaling from individual measurements to higher level of organization.

Here, we use a vegetation demography model (LM3-PPA) which simulates vegetation dynamics and biogeochemical processes by explicitly scaling from leaf up to ecosystem level by resolving leaf-level physiology, growth, and height-structured competition for light, using the perfect plasticity approximation (PPA). Using this simulation model, we investigate the links between individual trees’ carbon balance under rising CO2 levels, their longevity under alternative mortality parametrizations, and the implications for forest dynamics and self-thinning rates. Inventory data from long-term forest reserves is used to assess empirical support for these simulated links. Specifically, we test the hypothesis of faster growth-earlier death in order to assess forests’ capacity to store carbon under environmental changes. This provides key mechanistic insights to reveal whether increased CO2 fertilization on leaf-level photosynthesis positively affects tree’s C balance and thereby reduces the mortality under competition for light in the canopy.

 
Distributed climate change impacts and uncertainty throughout mountainous catchments
Authors: Moraga Jorge Sebastián , Peleg Nadav , Fatichi Simone , Molnar Peter , Burlando Paolo
Published: March 2020

A combination of high-resolution models in space and time was used to evaluate the impacts of climate change on streamflow statistics and their uncertainties throughout three mountainous catchments in Switzerland (Thur, K. Emme and Maggia). The two-dimensional AWE-GEN-2d model was used to simulate ensembles of gridded climate variables at an hourly and 2-km resolution based on ground and remote-sensing observations. The model was re-parametrized using the “factors of change” approach, calculated from regional climate models, and it was used to simulate ensembles of climate data until the end of the 21st century. These ensembles were subsequently used as inputs into the fully distributed hydrological model Topkapi-ETH, which is suitable for simulating streamflow over complex terrain, and considers all the relevant hydrological processes. Based on large ensembles of simulated hydrological variables, the changes of the hydrological components in space and time were evaluated along with their uncertainty due to the internal variability of the climate and the climate model selection. Results indicate a rather uniform increase in temperature for all catchments, characterized by high uncertainty toward the end of the century (with strongest increases of over 5°C). On the other hand, the magnitude and spatial patterns (namely, mountain vs valley) of change in precipitation differ between catchments, and the uncertainty of changes in extreme events is of larger magnitude than the climate change signal. The changes in climate are foreseen to affect the hydrological components in the catchments: evapotranspiration is projected to increase, while snowmelt contribution to the streamflow is expected to decrease by 50% at the end of the century. Model results indicate a decrease in streamflow at the outlet during the summer months and an increase in winter as early as the 2020-2049 period. Conversely, changes in extreme discharge show an uncertainty greater than the change signal for most climate models. Spatially heterogeneous changes in temperature and precipitation lead to elevation-dependent hydrological responses: e.g., streamflow annual means would decrease 20% in the upper reaches of the Thur catchment, while decreasing a similar amount in the downstream reaches. Correspondingly, hourly extremes are expected to decrease 20% in the upper reaches and increase up to 50% in the lowest part of the catchment. However, the signals of the change for extreme streamflow, compared to their uncertainty, are stronger for the upper parts of the river network. These results illustrate the benefit of using stochastic downscaling of climate variables to capture climate variability and assess uncertainty, and emphasize the importance of investigating the distributed impacts of climate change in mountainous areas, which may differ between high and low elevation reaches. 
Blocking, gap flow and mountain waves along the coastal escarpment of South Africa
Authors: van der Mescht Deon , Geldenhuys Markus , Dyson Liesl
Published: March 2020

A fatal crash of a light aircraft occurred in the complex coastal mountainous terrain along the South African South Cape in December 2015. An investigation of the meteorological conditions on that day revealed the interaction between mountain waves, gap flow and blocking near a cold front and terrain. The crash made it clear that it is necessary to provide forecasters with knowledge of the turbulence that will arise under these circumstances. Against this background, experiments were carried out near the crash site, with automatic weather stations and radio stations to answer this question. Turbulence has been successfully characterized by the Froude number, Froude altitude scale and thermal wind equation. The Bernoulli equation, which classifies the gap flow, was not helpful due to the effect of the upwind blocking area. Phenomena in descending order of the generated wind force were, compression effect above the peak (44.7 ms-1), blocking (26 ms-1) and finally gap flow. The gap flow had a negative impact on the strength of the barrier jet. Phenomena in descending order of the turbulence intensity were; gap flow, mountain wave/rotors and finally blocking. Gap flow generated higher vertical speeds than mountain waves. These mountain waves generated the highest vertical speeds measured in South Africa to date, combined with the waves of the shortest wavelength. A blocking jet with a depth of 600 m and a width of 80 km changed the formation of mountain waves significantly. The blocking jet was so strong, that it extended up to 30 km beyond the end of the mountain range. Most likely, a combination of mountain waves, gap flow and blocking contributed to the crash, which shows that these three features cannot be seen as separate processes.
The Current Feedback to the Atmosphere: Implications for the Ocean Dynamics, Air-Sea Interactions, and Climate.
Authors: Renault Lionel , Masson Sebastien , McWilliams James C.
Published: March 2020

In the past few years, it has been demonstrated that the regional Ocean-Atmosphere interactions can strongly modulate the variability and the mean physical and biogeochemical state of the ocean. In this presentation, the focus will be on the influence of the surface current on the atmosphere (i.e., current feedback). Based on satellite observations and using a set of regional ocean and atmosphere coupled simulations carried out over different regions encompassing a realistic Tropical Channel, and Eastern and Western boundary current systems, we will illustrate to which extent those interactions can control the exchange of energy between the Ocean and the Atmosphere, the mean, mesoscale, and submesoscale circulations, and the Western Boundary Currents Dynamics. Implications for climate, thermal air-sea interactions and how to force an oceanic model is furthermore discussed.
Joint seismic and geodetic transdimensional earthquake source optimization guided by multi-array teleseismic backprojection
Authors: Steinberg Andreas , Sudhaus Henriette , Krüger Frank , Vasyura-Bathke Hannes , Daout Simon , Isken Marius Paul
Published: March 2020

Earthquakes have been observed to initiate and terminate near geometrical irregularities (bends, step-overs, branching of secondary faults). Rupture segmentationinfluences the seismic radiation and therefore, the related seismic hazard. Good imaging of rupture segmentation helps to characterize fault geometries at depth for follow-up tectonic, stress-field or other analyses. From reported earthquake source models it appears that large earthquakes with magnitudes above 7 are most often segmented, while earthquakes with magnitudes below 6.5 most often are not. If this observationreflects nature or if it is rather an artifact of our abilities to well observe and infer earthquake sources can not be answered without an objective strategy to constrain rupture complexity. However, data-driven analyses of rupture segmentation are not often conducted in source modeling as it is mostly pre-defined through a given and fixed number of sources. 

We, here, propose a segmentation-sensitive source analysis by combining a model-independent teleseismic back-projection and image segmentation methods with a kinematic fault inversion. Our approach is twofold. We first develop a time-domain multi-array back-projection of teleseismic data with robust estimations of uncertainties based on bootstrapping of the travel-time models and array weights (Palantiri software, https://braunfuss.github.io/Palantiri/). Backprojection has proven to be a powerful tool to infer rupture propagation from teleseismic data and identify irregularities of the rupture process over time.

We then model the earthquake sources with the results obtained from the backprojection and additional information obtained from the application of image segmentation methods to the InSAR displacement maps. For this second step, we use a combination of different observations (teleseismic waveforms and surface displacement maps based on InSAR) to increase the resolution on the spatio-temporal evolution of fault slip. We develop a novel Informational criterion based transdimensional optimization scheme to model an adequate representation of the source complexity. We present our method on two cases study: the 2016 Muji Mw 6.7 earthquake (Pamir) and the 2008-2009 Qaidam (Tibet) sequence of earthquakes. We find that the 2008 Qaidam earthquake ruptures one segment, the 2016 Muji earthquake on two segments and the Qaidam 2009 earthquake on two or three segments.

This work is based on the open-source, python-based Pyrocko toolbox and is conducted within the project “Bridging Geodesy and Seismology” (www.bridges.uni-kiel.de) funded by the DFG through an Emmy-Noether grant.

 
Coastal morphodynamics in an Arctic fluvial-tidal transition zone in the deglaciated Dicksonfjord, Svalbard
Authors: Kim Dohyeong , Jo Joohee , Choi Kyungsik
Published: March 2020

Pronounced morphologic changes such as coastal retreat and delta progradation occur widely along the Arctic coastal regions in response to increased sediment flux, freshwater runoff, and wave activity caused by climate changes. Compared to open coast and large-scale deltas in the Arctic region, the coastal morphodynamics and associated sediment transport in the Arctic fluvial-tidal transition zone (FTTZ) are less well understood. A series of recurved spits are developed on the upper intertidal zone of microtidal flats in the FTTZ of deglaciated Dicksonfjorden, Svalbard. The morphodynamics and sediment fluxes of the spit complexes were quantified using unmanned aerial vehicle (UAV)-assisted photogrammetry and Real-Time Kinematic GPS. Repeated annual survey indicates that the spits have elongated at 22 m yr-1 and have migrated landward at 4.3 m yr-1 over the last four years. The growth and migration rate of the spits increases seaward, where coastal cliffs consisting of an unconsolidated mixture of angular gravels and muds retreats at 0.2 m yr-1 with net erosion rate of 0.02 m yr-1 and provides local sediment source for the spits. In contrast, isolated gravel ridges, i.e., cheniers, on the tidal flats in the further landward did not migrate during the survey period. Archives of aerial photographs indicate that the cheniers had remained stationary since the 1930s, when a shoreline was located near the cheniers. The present study demonstrates that wave-induced overwash and longshore drift of coarse-grained sediments originated from the retreating cliffs are vital to the annual spit morphodynamics even in the innermost part of the fjord. Tidal flat progradation accelerated since the Little Ice Age with global warming trends by increased runoff from snow-fed rivers and alluvial fans, controls the centennial spit morphodynamics and distribution of wave-built morphology in the FTTZ of glacier-free Dicksonfjorden by regulating episodic sediment delivery via a seaward-shift in the locus of wave shoaling.
Thermohaline Fingerprints of the Greenland-Scotland Ridge and Fram Strait Subsidence Histories
Authors: Hossain Akil , Knorr Gregor , Lohmann Gerrit , Stärz Michael , Jokat Wilfried
Published: March 2020

 Changes in ocean gateway configuration are known to induce basin-scale rearrangements in ocean characteristics throughout the Cenozoic. However, there is large uncertainty in the relative timing of the subsidence histories of ocean gateways in the northern high latitudes. By using a fully coupled General Circulation Model we investigate the salinity and temperature changes in response to the subsidence of two key ocean gateways in the northern high latitudes during early to middle Miocene. Deepening of the Greenland-Scotland Ridge causes a salinity increase and warming in the Nordic Seas and the Arctic Ocean. While warming this realm, deep water formation takes place at lower temperatures due to a shift of the convection sites to north off Iceland. The associated deep ocean cooling and upwelling of deep waters to the Southern Ocean surface causes a cooling in the southern high latitudes. These characteristic impacts in response to the Greenland-Scotland Ridge deepening are independent of the Fram Strait state. Subsidence of the Fram Strait for a deep Greenland-Scotland Ridge causes less pronounced warming and salinity increase in the Nordic Seas. A stronger salinity increase is detected in the Arctic while temperatures remain unaltered, which further increases the density of the North Atlantic Deep Water. This causes an enhanced contribution of North Atlantic Deep Water to the abyssal ocean and on the expense of the colder southern source water component. These relative changes largely counteract each other and cause little warming in the upwelling regions of the Southern Ocean.
Limits of the WTQ method for calculating momentum flux
Authors: Preusse Peter , Geldenhuys Markus , Ern Manfred
Published: March 2020

The acceleration of the large scale circulation by gravity wave is commonly described via the vertical gradient of the vertical flux of horizontal pseudomomentum, or in short of the momentum flux. The momentum flux vector is given by

 (Fpx,Fpy) = (1-f2/ω2) ( ,)

where < > describes the spatial or temporal mean of at least one wavelength or period of the gravity wave. If one is going actually to calculate momentum flux from an observation or high-resolution model, several difficulties arise. First, one has to know the intrinsic frequency ω of the wave, second one tacitly assumes that only a single wave is causing the wind perturbations u', v' and w', and third one needs to find an appropriate averaging interval. One possibility to solve this is to perform spectral analysis. An alternative was introduced by Geller et al. (2013) which, based on the polarization relations, infers ω directly from the perturbation wind temperature quadratics and is hence referred to as WTQ. In a brief study we will investigate the implication of the single wave assumption for the momentum flux calculated from data sets calculating multiple waves.
Impact of Rossby waves on Norther-Hemisphere continental climate
Authors: Graversen Rune Grand
Published: March 2020

Mid-latitude continental weather and climate are strongly affected by the atmospheric circulation patterns such as Rossby waves and cyclones. For instance these patterns may lead to warm- and humid-air advection over western part of the continents in winter and cold-air advection in these regions during summer. By applying a newly developed method for splitting the atmospheric latent and dry-static energy transport into waves, hereby decomposing the energy transport into parts accomplished by e.g. Rossby waves and synoptic-scale weather systems, the effect of different atmospheric circulation patterns on Northern-Hemisphere continental climate is investigated.

Climate change and the associated Arctic temperature amplification may impact mid-latitude atmospheric circulation. Here we investigate the effect on Northern-Hemisphere continental climate from changes over recent decades in the atmospheric circulation patterns using the above-mentioned method.
Towards new online access services for the EMSO ERIC temperature and salinity data
Authors: Novello Alice , Lefevre Dominique , LoBue Nadia , Rodero Ivan , Bardaji Raul , Cannat Mathilde
Published: March 2020

The European Multidisciplinary Seafloor and water column Observatory (EMSO) consists, to date, of 11 regional multiple sensor-equipped platforms distributed around Europe from the Atlantic Ocean to the Mediterranean, and the Black Sea. Each system collects multidisciplinary measurements in the water column as well as at the seafloor addressing several critical questions related to ocean health, climate change, marine ecosystems and natural hazards. EMSO is a European Research Infrastructure Consortium (ERIC) since 2016, and one of the many challenges has been to design new online services promoting marine data produced by the whole network. Here, we report on an on-going activity to compile, control and deliver quality controlled temperature and salinity data and metadata gathered through the EMSO network from the sea surface down to 4000m. As part of this effort, we work on the development of online tools for temperature and salinity data visualization and knowledge discovery based on widely used software components such as dashboards. These services aim to support the stakeholders' needs (from scientists and industries to institutions and policymakers) by providing relevant information on multidisciplinary oceanographic data. They also highlight the importance of filling the knowledge gap on the abyssal ocean by delivering useful deep long-term series necessary to assess the impact of key processes on global issues such as climate change and marine ecosystem sustainability.
Spatial coherence of interplanetary coronal mass ejection-driven sheaths at 1 AU
Authors: Ala-Lahti Matti , Ruohotie Julia , Good Simon , Kilpua Emilia , Lugaz Noé
Published: March 2020

We report on the longitudinal coherence of sheath regions driven by interplanetary coronal mass ejections (ICMEs). ICME sheaths are significant drivers of geomagnetic activity at the Earth, with a considerable fraction of ICME-driven storms being either entirely or primarily induced by the sheath. Similarly to Lugaz et al. (2018; doi:10.3847/2041-8213/aad9f4), we have analyzed two-point magnetic field measurements made by the ACE and Wind spacecraft in 29 ICME sheaths to estimate the coherence scale lengths, defined as the spatial scale at which correlation between measurements falls to zero, of the field magnitude and components. Scale lengths for the sheath are found to be mostly smaller than the corresponding values in the ICME driver, an expected result given that ICME sheaths are characterized by highly fluctuating, variable magnetic fields, in contrast to the often more coherent ejecta. A relatively large scale length for the magnetic field component in the GSE y-direction was found. We discuss how magnetic field line draping around the ejecta and the alignment of pre-existing magnetic structures by the preceding shock may explain the observed results. In addition, we consider the existence of longitudinally extended and possibly geoeffective magnetic field fluctuations within ICME sheaths, the full understanding of which requires further multi-spacecraft analysis.
Variability of seawater property after typhoon passage in the Philippine sea of the western North Pacific
Authors: Oh Kyung-Hee , Lee Seok , Min Hong Sik , Kang Sok-Kuh
Published: March 2020

Sea water temperature and salinity measurements have been collected onboard in September in the Philippine seas of the western North Pacific. This area is close to typhoon occurrence area and is the path through which developed typhoons pass, and also large and small eddies are developed. Therefore variability of sea water property is large.  As a result of analysis, the seawater properties of the upper water showed a big difference before and after the typhoon. After the typhoon, surface water temperature dropped by about 1 degree C and salinity by 1 psu.  Mixed layer became deeper, and changes in seawater properties occurred throughout the upper layers. The depth of the mixed layer was largely different by more than 30-50m, especially the water temperature was changed more than 3 degree C at the depth below thermocline. Real-time sea surface water temperature and salinity measurements show more easily identify the physical property change of sea surface water before and after typhoon.
Optimal VGOS telescope location for the estimation of Earth orientation parameters
Authors: Schartner Matthias , Böhm Johannes , Nothnagel Axel
Published: March 2020

In this investigation, we identify optimal locations for VGOS radio telescopes to estimate Earth orientation parameters (EOP) with a new method based on bulk schedule generation and large-scale Monte-Carlo simulations. Thereby, we focus on a high number of simulations and a proper consideration of scheduling to minimize these undesired error sources.

The location of the telescope is varied over 477 possible locations, homogeneously distributed over land areas on the globe. The antenna is added to a fixed network of 6, 12 and 18 existing and upcoming VGOS stations. The optimal location is defined through the minimal resulting repeatabilities of the simulated EOP. In this study, a special focus was laid on the generation of high-quality observing plans to minimize the effects of scheduling combined with a high number of simulations to minimize their randomness. To remove the unintended effects caused by scheduling over 93 thousand schedules were iteratively generated. Each schedule is further simulated 1000 times leading to over 5 trillion simulated and analyzed observations. Besides showing our results for the best telescope location, we will highlight how scheduling and the number of simulations affects the repeatability of the estimated EOP. This will help further simulation studies to improve their results.

The optimal telescope location depends on the EOP of interest and the existing network. For simple network geometries, such as the 6 station network which consists of antennas in Europe and North America, the importance of east-west baselines can be seen for the determination of dUT1 while the importance of north-south baselines can be seen for the determination of polar motion and nutation. For more complex network geometries and an increasing number of VGOS stations, the lack of southern stations becomes more prominent. For the 12 and 18 station network, the location of an additional antenna in south America can significantly improve the accuracy of the EOP by up to 60%.
Increasing institutional inclusivity through productive community dialogs
Authors: Yehudai Maayan , Tweed Lucy E.
Published: March 2020

As relatively older, international PhD student, the process of moving to a new institution in a new country presented me with challenges I have not faced before and motivated me to explore the issue of diversity in academia and beyond. In the summer of 2016, as a third year PhD student, I gathered a small group of women at Lamont Doherty Earth Observatory to discuss actions to increase inclusivity within our department. A few months later we had our first Gender and Diversity Coffee hour. We met monthly, initially with no agenda, to talk about things that bothered us and to explore what could be done both in the short and long-term. What started as a small grass-roots initiative, evolved into a widely attended monthly meeting, where we covered many subjects (some “tabooed”) including family and academia, harassment, impostor syndrome, academia stress culture, mental health stigma, long distance relationships, minorities being penalized for promoting women and minorities issues, non-binary identities and more. Over time a core group formed around these issues, consisting of both higher and lower ranks at Lamont. Some conversations were very hard: the lesson that different people experience reality in different ways is not an easy one. Nevertheless, these meetings provided space for people to express their feelings and frustrations, while also listening, building understanding, and developing actionable solutions. Varied feedback has shown that people have come out of the meetings feeling empowered to make their work environment healthier and more inclusive. In what has since become an inseparable part of the institutional routine, and which is now left to run by other talented hands, I believe this group contributed significantly to cultural changes at Lamont. In this presentation, I will share my personal experience of establishing the group and coordinating the meetings. I will also explore how dialog within the meetings, projected out to the whole community and beyond; promoting a better work environment, especially for students and junior staff at Lamont. 