bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal predictions of energy-relevant Essential Climate Variables through Euro-Atlantic Teleconnections
Authors: Cionni Irene , Lledó Llorenç , Catalano Franco , Dell’Aquila Alessandro
Published: March 2020

Accurate and reliable information from climate predictions at seasonal time-scales can have an essential role to anticipate climate variability affecting supply of renewables energy and to stabilize and secure the energy network as a whole. A number of recognized modes of variability -often called teleconnections- explain a large part of Earth’s climate variations and represent an important source of climate predictability. The leading atmospheric variability modes in the Euro-Atlantic sector (EATC) affect surface variables such as 2 meters temperature, solar radiation downward, and surface wind anomalies in Europe.

Characterizing EATC in observations and assessing their simulation and prediction and their impact on the energy sector can help to better understand patterns of seasonal-scale inter annual variability in renewables resources and to consider to what extent this variability might be predictable up to several months in advance. Furthermore EATC can be used to formulate empirical prediction of local climate variability (relevant for the energy sector) based on the large scale atmospheric variability modes predicted by the forecast systems.

To achieve this goal we analyze reanalysis dataset ERA5 and the multi-system seasonal forecast service provided by the Copernicus Climate Data Store (C3S).

Geopotential height anomalies at 500 hPa have been employed to compute the four Euro-Atlantic teleconnections North Atlantic Oscillation, East Atlantic, Scandinavian and East Atlantic-West Russian. The impacts of those four variability modes on the energy - relevant  essential climate variables have been assessed in both observed and predicted system. We have found that the observed relationship between EATC patterns and surface impacts is not accurately reproduced by seasonal prediction systems. This opens the door to employ hybrid dynamical-statistical methods. The idea consists in combining the dynamical seasonal predictions of EATC indices with the observed relationship between EATCs and surface variables.  We reconstructed the surface anomalies for multiple seasonal prediction systems and benchmarked these hybrid forecasts with the direct variable forecasts from the systems and also with the climatology. The analysis suggest that predictions of energy relevant Essential Climate Variables are improved by the hybrid methodology in almost all Europe. 
An uppermost haze layer above 100 km found over Venus by the SOIR instrument onboard Venus Express
Authors: Takagi Seiko , Mahieux Arnaud , Wilquet Valérie , Robert Séverine , Vandaele Ann Carine , Iwagami Naomoto
Published: March 2020

The Venus cloud consists of a main cloud deck at 47 – 70 km, with thinner hazes above and below.The upper haze on Venus lies above the main cloud surrounding the planet, ranging from the top of the cloud (70 km) up to as high as 90 km.

The Solar Occultation in the InfraRed (SOIR) instrument onboard Venus Express was designed to measure the Venusian atmospheric transmission at high altitudes (65 – 220 km) in the infrared range (2.2 – 4.3 µm) with a high spectral resolution. We investigate the optical properties of Venus’s haze layer above 90 km using SOIR solar occultation observations. Vertical and latitudinal profiles of the extinction coefficient, optical thickness, and mixing ratio of aerosols are retrieved. One of the most remarkable results is that the aerosol mixing ratio tends to increase with altitude above 90 km at both high and low latitude. We speculate how aerosols could be produced at such high altitudes.
Macroturbulence Response to Vertical Stratification Change Using Linear Response Function of an Idealized Dry Atmosphere
Authors: Chan Pak-Wah , Hassanzadeh Pedram , Kuang Zhiming
Published: March 2020

Rossby radius and Rhines scale are two popular scaling arguments for eddy length scale. They have not been tested in a well-controlled experiment with increased vertical stratification and unchanged jet. This is done using the linear response function of an idealized dry atmosphere calculated by Hassanzadeh and Kuang (2016). The resulting change in zonal wind is mostly less than 0.2m/s when temperature near surface is cooled by more than 2K. In such experiment, energy-containing zonal scale decreases, which is against the prediction of Rossby radius but consistent with the prediction of Rhines scale. Eddy kinetic energy decreases for all wavenumbers and latitudes, but eddy momentum flux strengthens locally around zonal wavenumber 8 and 40°S. This local strengthening is associated with a stronger Pearson correlation between u and v.
National Mitigation Strategy against Earthquakes in Central Asia
Authors: Moon Sung-Woo , Hakimov Farkhod , Kim Jong , Reicherter Klaus , Havenith Hans-Balder , Ischuk Anatoly
Published: March 2020

Throughout history, earthquakes have caused extensive damages in urban areas with important infrastructures and high population density. Especially, earthquakes have extensively damaged many regions of Central Asia (e.g., Tashkent in 1966, and Almaty in 1911). Hence, the estimation of the seismic hazard of the urban areas in Central Asia is very important due to the high level of seismicity in Central Asia and the rapid construction of new buildings. The high earthquake-induced damages in the cities often result from the local geological conditions and engineering properties of the soils that can produce significant site effects. Such seismic effects combined with the high vulnerability of buildings can result in extreme disasters during earthquakes. Therefore, geotechnical engineers/seismologists should decide to divide the city into specific microzones depending on their site effects and soil properties. However, conventional approaches in Central Asia have been proposed, based on (1) general engineering geological information; (2) the building code based on the estimates of the ground motions in terms of MSK-64 scale developed in 1978; and (3) the quantitative assessment only mapping and overlaying the data.

By characterizing the soft layers of their nature, thickness, and structure, and assessing the numerical model developed for the high-seismicity area of Central Asia, we can better assess specific site effects in each region of Central Asia. In addition, to predict the essential consequences of earthquakes, physically-based ground motion simulations should be developed by numerical simulations considering all possible processes of seismic wave propagation. Compared to empirical ground-motion predictions, numerical simulations of earthquake scenarios will provide much more flexible and better-suited solutions for most applications – especially those involving complex city environments. The ground-motion prediction equations or stochastic ground-motion estimates integrate characteristics of the earthquake source, path, attenuation, and site effects via approximate or statistical approaches. This method will provide rapid solutions that may be valid for a well-known context and would also be applied in Central Asia, for comparison with the numerical simulations. Finally, the quantitative approach for microzoning map incorporated with numerical simulation/site response analysis, for infrastructures (e.g., buildings, bridges, and dams) will be significantly useful in the future.
Analysis of research trends using Latent Dirichlet Allocation for geologic subdisciplines in South Korea
Authors: Kim Taeyong , Yang Minjune
Published: March 2020

Since the mid-twentieth century, geology in South Korea has considerably advanced as a scientific discipline. Over the past few decades, geology has interacted with physical or engineering viewpoints. So, modern geology needs to be interpreted with an interdisciplinary perspective. This study aimed to classify geology’s academic subdisciplines in Korean and analyze the evolutionary trend of each subdiscipline in South Korea for 54 years from 1964 through 2018. In preprocessing, we collected 13,266 titles from 10 of Korean geological journals and deleted the words that do not require. After that, we classified geologic subdisciplines by Latent Dirichlet Allocation (LDA), a good tool to find topics in text data. According to the result of this study, the optimal number of subdisciplines in LDA was nine (mineralogy, petrology, sedimentology, economic geology, geotechnical engineering, engineering geology, environmental geology, geophysics, seismology). We then calculated the annual proportion from each subdiscipline to investigate evolutionary trends using polynomial regression. Results showed that mineralogy, petrology, sedimentology, and economic geology proportions increased in 1980. Geotechnical engineering and engineering geology proportions increased in 1990. Environmental geology, geophysics, and seismology proportions increased in 1995. The results of this study fill an important gap in understanding the research trends of geologic subdisciplines in South Korea, showing their emergence, growth and diminution.
Black Carbon and Light-absorbing impurities in the Antarctic Peninsula
Authors: Cordero Raul , Damiani Alessandro , Feron Sarah , Khan Alia , Jorquera Jose , Sepulveda Edgardo , Carrera Juan , Rowe Penny
Published: March 2020

Assessing the albedo response due to light-absorbing impurities (LAI) in coastal snowpacks has become of great interest in the light of the ‘Antarctic greening’. Reductions in the albedo (triggered by a change in air temperature or by the LAI deposition) can also enhance feedback mechanisms; as the albedo drops, the fraction of absorbed solar energy increases, which leads to additional albedo drops.

Here we assess the presence of Black Carbon (BC) and LAI in coastal snowpacks in the Antarctic Peninsula. The BC-equivalent contentwas assessed by applying the meltwater filtration (MF) technique to snow samples taken at 7 locations in theAntarctic Peninsula, from latitude 62oS to latitude 67oS. BC-equivalentconcentrations exhibited significant geographical differences,but were found to be generally lower than 5 ng/g (in the range of those reported for the Arctic Ocean and Greenland). Moreover, the Angstrom coefficients were found to be particularly high at the northern tip of the Antarctic Peninsula,likely due to the snow algae presence. After the onset of melt, red snow algae bloom, significantly affecting the surface albedo, as shown by our measurements.
Modeling and experimental investigation of the evolution of altered zones at the shale-fluid interface
Authors: Deng Hang , Molins Sergi , Steefel Carl , Bargar John , Jew Adam , Hakala Alexandra , Lopano Christina , Xiong Wei
Published: March 2020

Unconventional oil and gas production involves the use of acidic hydraulic fracturing fluids that interact with the rock matrix bordering the fractures. As a result, fracture permeability and mass transfer between the matrix and the fracture can be altered, affecting production performance. The evolution of the altered zones are controlled by the gradients of pH and concentrations of various species perpendicular to the fracture-matrix interface, mineral reactions in the matrix as the reactive fluid diffuse into the matrix, and potential mineral coating on the fracture surface where the matrix fluid and fracture fluid mix. In this study, we use reactive transport model to investigate the evolution of the altered zones bordering the fractures. The simulations are based on batch and fracture flow experiments of shales and syntheized hydraulic fracturing fluids. Through the simulations, we quantify the reaction front of different mineral phases and the change of local porosity, and examine their dependence on mineral composition and fluid chemistry. We also discuss the impacts of the altered zones on matrix diffusivity and fracture permeability.
Quantifying Irrigation Water Use over Regional Scales with Landsat and Climate Data
Authors: Bretreger David , Yeo In-Young , Hancock Greg , Willgoose Garry
Published: March 2020

Irrigated agriculture has been identified as using approximately 72% of water globally. Australia, like many places in the world, is subject to water sharing plans that cross government boarders and are subject to a mixture of management policies. There is a pressing need to develop a method to monitor irrigation water use to aid in water resource assessments and monitoring. This paper aims to test a previously developed method which monitors irrigation water use using remotely sensed observations over the catchment scale, without the need for in-situ observations, ground data or in‑depth knowledge of crops and their planting dates. Using conservative assumptions about agricultural land management practice, irrigation is calculated as Irr=AET-P. The method tests three vegetation indices derived from Landsat 5/7/8 images to calculate crop coefficients (Kc) based on multiple published relationships. These are combined through the FAO56 methodology using gridded rainfall and two reference evapotranspiration (ET0) products to find actual evapotranspiration as AET=ET0xKc, providing six ET0-Kc combinations. Validation data is sourced from Irrigation Infrastructure Operators (IIO) from across the Murray-Darling Basin, Australia which are required to record irrigation water deliveries for billing purposes. The majority of these regions are in arid or semi-arid regions. Data periods used in this study range from 2003/04 to 2016/17. Results indicate this method can effectively assess irrigation water use over a range of catchment sizes from ~6,000 to ~600,000 ha. The best results returned a monthly irrigation RMSE ranging from 1.13 to 2.42 mm/month. Issues arise when regions have a designated low water allocation volume for that season (<40%). The allocation percentage is a function of water storage levels, demand and forecasts. Comparisons with the Standardised Precipitation Index (SPI) and Evaporative Stress Index (ESI) show that the proposed method is robust to the rapid onset and short-term droughts. However, its performance was poor during the long term droughts with low water allocation years. The study results during these years has been predominately attributed to water stress in certain crops being undetected, agricultural managers skipping annual crop commodities as well as stock and domestic water use making up larger portions of total water use. This is a limitation of this approach, although when only comparing results in years with greater than 40% allocations, the results improved significantly showing it can monitor water use effectively. When adequate water is available, this approach is able to accurately predict irrigation water use for the sites examined.
The ocean response to changes of the Greenland Ice sheet in a warming climate
Authors: Madsen Marianne S. , Yang Shuting , Rodehacke Christian , Aðalgeirsdóttir Guðfinna , Svendsen Synne H. , Ringgaard Ida Margrethe
Published: March 2020

During recent decades, increased and highly variable mass loss from the Greenland ice sheet has been observed, implying that the ice sheet can respond to changes in ocean and atmospheric conditions on annual to decadal time scales. Changes in ice sheet topography and increased mass loss into the ocean may impact large scale atmosphere and ocean circulation. Therefore, coupling of ice sheet and climate models, to explicitly include the processes and feedbacks of ice sheet changes, is needed to improve the understanding of ice sheet-climate interactions.

Here, we present results from the coupled ice sheet-climate model system, EC-Earth-PISM. The model consists of the atmosphere, ocean and sea-ice model system EC-Earth, two-way coupled to the Parallel Ice Sheet Model, PISM. The surface mass balance (SMB) is calculated within EC-Earth, from the precipitation, evaporation and surface melt of snow and ice, to ensure conservation of mass and energy. The ice sheet model, PISM, calculates ice dynamical changes in ice discharge and basal melt as well as changes in ice extent and thickness. Idealized climate change experiments have been performed starting from pre-industrial conditions for a) constant forcing (pre-industrial control); b) abruptly quadrupling the CO2 concentration; and c) gradually increasing the CO2 concentration by 1% per year until 4xCO2 is reached.  All three experiments are run for 350 years.

Our results show a significant impact of the interactive ice sheet component on heat and fresh water fluxes into the Arctic and North Atlantic Oceans. The interactive ice sheet causes freshening of the Arctic Ocean and affects deep water formation, resulting in a significant delay of the recovery of the Atlantic Meridional Overturning Circulation (AMOC) in the coupled 4xCO2 experiments, when compared with uncoupled experiments.
Aspen detection in boreal forests: Capturing a key component of biodiversity using airborne hyperspectral, lidar, and UAV data
Authors: Kumpula Timo , Viinikka Arto , Mäyrä Janne , Kuzmin Anton , Hurskainen Pekka , Tanhuanpää Topi , Kivinen Sonja , Kullberg peter , Poikolainen Laura , Korpelainen Pasi , Stranden Max , Ritakallio Aleksi , Vihervaara Petteri
Published: March 2020

Importance of biodiversity is increasingly highlighted as an essential part of sustainable forest management. As direct monitoring of biodiversity is not possible, proxy variables have been used to indicate site’s species richness and quality. In boreal forests, European aspen (Populus tremula L.) is one of the most significant proxies for biodiversity. Aspen is a keystone species, hosting a range of endangered species, hence having a high importance in maintaining forest biodiversity. Still, reliable and fine-scale spatial data on aspen occurrence remains scarce and incomprehensive. Although remote sensing-based species classification has been used for decades for the needs of forestry, commercially less significant species (e.g., aspen) have typically been excluded from the studies. This creates a need for developing general methods for tree species classification covering also ecologically significant species.

 

Our study area, located in Evo, Southern Finland, covers approximately 83km2, and contains both managed and protected southern boreal forests. The main tree species in the area are Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst), and birch (Betula pendula and pubescens L.), with relatively sparse and scattered occurrence of aspen. Along with a thorough field data, airborne hyperspectral and LiDAR data have been acquired from the study area. We also collected ultra high resolution unmanned aerial vehicle (UAV) data with RGB and multispectral sensors.

 

Our aim is to gather fundamental data on hyperspectral and multispectral species classification, that can be utilized to produce detailed aspen data at large scale. For this, we first analyze species detection at tree-level. We test and compare different machine learning methods (Support Vector Machines, Random Forest, Gradient Boosting Machine) and deep learning methods (3D convolutional neural networks), with specific emphasis on accurate and feasible aspen detection. The results will show, how accurately aspen can be detected from the forest canopy, and which bandwidths have the largest importance for aspen. This information can be utilized for aspen detection from satellite images at large scale.
Biogeomorphology at the micro-scale: biogeochemical weathering of rock surfaces in the cold and warm deserts
Authors: Zerboni Andrea
Published: March 2020

Biogeochemical weathering of stable rock surfaces in warm and cold deserts is a notable biogeomorphological process, which contribute to mineralogical transformation of rock constituents and rock disaggregation. Endolithic microorganisms (mostly bacteria, fungi and lichens) play a major role in controlling the destabilization and rejunevation of rock surfaces; but occasionally, biofilms can stabilize rock surfaces. In most of the casis, endolithic communities precipitates byproducts (e.g. oxalates) contributing to enhance discotnituity and promoting exfoliation and disaggregation. On the contrary, rock varnish can develop as an external crust protecting the underliyng rock from erosion and dissolution. In this contribution, a number of case-studies of fossil and active examples of biogeochemical weathering from warm deserts of Africa and Arabian peninsula and from Antarctica are considered. The comaprison of evidence suggests a highly differentiate –  and occasioanlly surprisingly – array of effects of endolithic communities on rock surfaces.
Simultaneous Bayesian Estimation of Complex Non-planar Earthquake Fault Geometry and Spatially-variable Slip from Geodetic Data
Authors: Dutta Rishabh , Jónsson Sigurjón , Vasyura-Bathke Hannes
Published: March 2020

Earthquake fault ruptures are typically complex and can consist of en echelon segments, have bends, large step-overs, and be curved or warped at different spatial scales. Although surface fault ruptures can be mapped using a variety of geological and geophysical techniques, the subsurface topology of faults is challenging to estimate. One of the main options is to use geodetic data (InSAR and GPS) of coseismic surface deformation to estimate the subsurface earthquake fault geometry along with the distributed slip. The general practice is to assume a planar fault surface and estimate the strike and dip of a simple rectangular fault prior to the spatially-variable slip estimation. Using such simplistic fault geometry during source fault estimations of large earthquakes rarely captures all the crustal deformation details seen in the data and can cause biased estimation results of the fault slip. Here, we show how complex non-planar fault geometry can be estimated simultaneously with spatially-variable slip from geodetic data in a Bayesian framework, where our non-planar fault geometry parametrization approach allows for various undulations of the fault surface in both the along-strike and down-dip directions.

We exemplify this approach through synthetic tests considering a checkerboard-like slip pattern on a listric non-planar fault. The results show that fault slip can be over-estimated by about 50-100% when using pre-assumed planar fault geometry. In contrast, both the non-planar fault geometry and spatially-variable slip are better retrieved when using our estimation approach. We then apply this modeling approach to the 2011 MW9.1 megathrust Tohoku-Oki (Japan) earthquake. Here we use prior information like the location of the trench and earthquake hypocenters during the Bayesian estimation to reduce the extent of the model space. The resulting fault geometry shows variations in fault dip in both the along-strike and down-dip directions that compare well with Hayes’ slab1.0 model of the subduction interface. The estimated fault slip is also comparable to the results that pre-defined the fault geometry using the slab1.0 model. In the future, the proposed method could lead to more realistic source models of major earthquakes, aided by improving computational resources and spatial resolution of geodetic data.
Spatiotemporal investigation of material property changes in building stone following initial emplacement
Authors: Johnston Brian , McKinley Jennifer , Warke Patricia
Published: March 2020

Visual inspection of deterioration phenomena across the façades of a historical monument demonstrates the spatial variability of weathering processes. Multiple previous weathering simulation and exposure trials have been developed to investigate the connection between weathering processes and spatial variability of response. However, in landscape systems theory, stability is a function of both spatial and temporal components. Temporal sensitivity is a function of both the magnitude and frequency of formative events and the spatial sensitivity of the material.

One area of urban stone decay literature that requires further attention is the initial response of quarry ‘fresh’ material to emplacement within a building. Previous small-scale investigations have demonstrated that alteration commences within a few months to a year of emplacement. These early changes to the material will have a lasting influence upon the development of future weathering processes and their spatial distribution. The necessity to investigate both the spatial and temporal components of this transition, well suits the capabilities of spatiotemporal kriging tools.

The influence of aspect upon the initial alterations of the material’s properties are of significance to interpreting the weathering response to transition. Therefore, five sandstone blocks were placed within an exposure frame, located in South Belfast, for a duration of one year. One block was exposed to each of the four cardinal points whilst the fifth was positioned to represent a horizontal surface on a structure, such as a window sill or balustrade. Permeability measurements were recorded in a regular grid across the exposed surface of the block once a month, creating a data set that is both spatially and temporally dense. No previous studies have collected a similar quantity of points, across both space and time, to investigate weathering processes. The application of only spatial techniques proved to be inappropriate to fully interpret the complexity of the changing material properties. Use of spatiotemporal kriging allowed the modelling of the sample blocks to illustrate the changing material properties over time. The outcome of this work is the development of a better-informed understanding of the initial alteration of building stones placed within the urban environment. Additionally, the observed variance of the temporal component has improved our understanding of the nature of early episodic change within the stone decay system.
Changes in Köppen-Geiger Climate Types in the Iberian Peninsula using the e-OBS dataset (1950-2018).
Authors: Aguilar Enric
Published: March 2020

The recent decades have been characterized by a noticeable warming over most of the globe. This warming has been accompanied by a global increase in precipitation, although many regions are projected to evolve towards a dryer climate. This is the case for the flanks of the subtropical dry regions, such as the Mediterranean and, more specifically, the Iberian Peninsula

In this contribution, we use climate normal extracted from the E-OBS 20.0 gridded temperature and precipitation datasets E-OBS 20.0, from the EU-FP6 project UERRA (http://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://www.ecad.eu), with a resolution of 0.1 deg, to assess the evolution across three 20-year periods (1951-1970; 1971-1990 and the slightly shorter 1991-2018) of the extension occupied by the Köppen-Geiger climate types. In consonance with the observed and projected climate change, we observe an increase in the Iberian Peninsula of the extension of the dry (B) types, as replacement of the colder varieties by warmer ones.

The analysis with the gridded dataset is compared to station records corresponding to the areas which swap climate-types for validation purposes.     

 

This work has been funded by the INDECIS project. INDECIS is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union Grant 690462).

 
The associations between urban green spaces and self-reported health for university students in Singapore and Turin
Authors: Zhang Liqing , Tan Puay Yok
Published: March 2020

Numerous studies have found that green spaces can promote human health. However, most of the studies only investigate the relationship between green space and health in one single city. Therefore, whether the relationship between green space and health differs among cities with distinct differences in social-cultural and climatic context or there are universal patterns regarding such relationship is still remain unanswered. To investigate this question, this study aims to compare the associations between green space quantity and self-reported health for university students in Singapore and Turin, two high density cities with different social-cultural and climatic context. Students from National University of Singapore (NUS) and Politecnico di Torino (POLITO) were involved in an online survey to measure their self-reported health, use of green spaces and confounding factors. Through collecting the geographic location of student’s residence from online survey, the quantity of green spaces within 400 m-radius buffer surrounding the residence was calculated for each respondent. Through statistical analysis, the associations between green space quantity and self-reported health were revealed in both cities. The results from this work enhanced the knowledge regarding the dependence of green space-health relationship on social-cultural context.
Reduction of uncertainties in greenhouse gas accounting using Global Forest Watch forest loss database, LiDAR and stand wise inventory data
Authors: Ivanovs Janis , Lazdins Andis , Bardule Arta
Published: March 2020

Global Forest Watch (GFW) provides a global map of forest loss derived from LANDSAT satellite imagery, providing a tool for monitoring global forest change. In managed forests, GFW mainly provides information on commercial logging. This study is part of the INVENT project which aims to improve the National Forest Inventory based estimates of Carbon stock changes in forests reported to the UNFCCC. The purpose of this study is to evaluate the feasibility of using the GFW database to detect carbon stock changes in forest stands, using LiDAR (Light Detecting and Range) data and the stand wise forest database maintained by the State Forest Service (SFS) as additional data sources.

Only those forest loss areas from GFW database, which were detected according to the national LiDAR survey, were selected for data processing, thus obtaining 3D forest information prior to felling. Information on species composition and number of trees per hectare in the forest was obtained from the SFS stand wise forest database. Living biomass estimates were then calculated for each GFW pixel. For pixels outside the SFS stand wise forest database, living biomass values were determined by extrapolation. The average estimated live biomass per forest loss pixel in GFW database is 6792 kg.

Keywords: ERA-GAS INVENT, living biomass, carbon stock.
Arctic sea-ice decline impacts on primary production
Authors: Tedesco Letizia , Leu Eva , Macias-Fauria Marc , Mundy Christopher J. , Notz Dirk , Søreide Janne , Daase Malin , Doerr Jakob , Post Eric Stephen
Published: March 2020

Arctic food webs are short and relatively species poor, rendering them vulnerable to changes or perturbations at any individual trophic level. High-latitude warming represents one major source of potential perturbation to Arctic marine and terrestrial food webs, which may experience cascading effects derived from changes in primary production through so-called “bottom-up” effects. We synthesize current knowledge on i) the changing Arctic marine icescape, ii) the drivers of biological changes for Arctic marine primary production, iii) the different pulses of Arctic marine primary production, iv) patterns of marine trophic and phenological changes, and iv) some mechanisms through which sea-ice dynamics ostensibly influence terrestrial primary productivity. We deliver a set of predictions for key productivity indicators, propose a semi-quantitative model of the expected future changes in primary production in the ice-covered Arctic Ocean, and close with an overview of the challenges ahead for reaching a holistic and comprehensive understanding of the ecosystem dynamical consequences and associated impacts on human life of warming-related sea-ice decline.
PALAEO-RA: Combining an intermediate-size AGCM ensemble with historical observations and proxies to create a new dataset of the past 600 years of climate history
Authors: Brönnimann Stefan , Hand Ralf , Franke Jörg , Martynov Andrey
Published: March 2020

The recently started PALAEO-RA project aims at creating a new global monthly 3-dimensional reanalysis dataset of the past 600 years' climate. Large spatial and temporal gaps in the available historical data on these time scale make the climate history being an under-determined problem when using observations only. In PALAEO-RA we will addionally use information from an ensemble of simulations with an atmospheric general circulation model (AGCM). The model offers additional physical constraints. The model reproduces teleconnection patterns and reflects typical large-scale modes of variability to set the historical data into a physically consistent regional to global context.

In brief, the method that we plan to use consists of two steps: First, we are currently producing an  ensemble of historical simulations with the atmospheric general circulation model ECHAM6. Once finished, it will have a size of ca. 30 members, covering the period fom 1420 to present. The ensemble is supposed to reflect the range of realistic climate states under prescribed historical radiative forcings (based on the PMIP4 setup) and ocean boundary conditions (HadISST.2 & SST reconstructions by Samakinwa et al., see abstract EGU2020-8744).

Secondly, we will apply Ensemble Kalman Fitting, a technique for the offline assimilation of historical observations (instrumental observations, documentary data, tree ring width and other proxies), basing on the assumption that the occurrence of a distinct observation has a different probability depending on the meso- and large-scale circulation patterns of the atmosphere.

Our poster will give a brief overview on the project with a focus on introducing the AGCM ensemble, also to allow for discussions on further applications of the latter.
In Situ and In Transit Computing for Large Scale Geoscientific Simulation
Authors: Friedemann Sebastian , Raffin Bruno , Hector Basile , Cohard Jean-Martial
Published: March 2020

In situ and in transit computing is an effective way to place postprocessing and preprocessing tasks for large scale simulations on the high performance computing platform. The resulting proximity between the execution of preprocessing, simulation and postprocessing permits to lower I/O by bypassing slow and energy inefficient persistent storages. This permits to scale workflows consisting of heterogeneous components such as simulation, data analysis and visualization, to modern massively parallel high performance platforms. Reordering the workflow components gives a manifold of new advanced data processing possibilities for research. Thus in situ and in transit computing are vital for advances in the domain of geoscientific simulation which relies on the increasing amount of sensor and simulation data available.

In this talk, different in situ and in transit workflows, especially those that are useful in the field of geoscientific simulation, are discussed. Furthermore our experiences augmenting ParFlow-CLM, a physically based, state-of-the-art, fully coupled water transfer model for the critical zone, with FlowVR, an in situ framework with a strict component paradigm, are presented.
This allows shadowed in situ file writing, in situ online steering and in situ visualization.

In situ frameworks further can be coupled to data assimilation tools.
In the on going EoCoE-II we propose to embed data assimilation codes into an in transit computing environment. This is expected to enable ensemble based data assimilation on continental scale hydrological simulations with multiple thousands of ensemble members.
Watermark-based Copyright Protection Using Invariant Features for Remote Sensing Images
Authors: Ren Na , Zhu Changqing
Published: March 2020

With the development of remote sensing technology, the copyright protection of remote sensing images has become an urgent problem to be solved. In this paper, a blind watermarking scheme based on invariant features is applied. In the embedding process, the stable image features are firstly extracted from the original host using block DCT, and the embedding positions are constructed adaptively according to feature processing theory. Then, the watermark is embedded into the low-frequency coefficients by modifying the DC coefficients. For watermark extraction, according to the invariant image features in each region, the watermark location and the watermark information can be extracted without the original host. Experimental results show that the proposed watermarking is not only invisible and robust against common image processing, such as noise addition, image filtering, and JPEG compression, but also robust against cropping attack.
The effect of chemical pretreatment on grain size results of past and recent clastic sediments
Authors: Gresina Fruzsina , Varga György , Szabó Lili , Király Csilla , Szalai Zoltán
Published: March 2020

Laser diffraction grain size data have been widely used in paleoenvironmental reconstructions as physicochemical alteration-related proxies. Many studies are available on comparison of different laser diffraction devices, optical theories and optical settings. The ignorance of some uncertainty factors can lead to poorly comparable granulometric datasets. Other important factor leading to the aforementioned effect is the inadequate chemical pretreatment procedures which are often overlooked, but are capable to basically affect the results. In this study we examine a few past and recent sediment types from different geomorphological environments from the Carpathian Basin: lake and fluvial sediments, paleosols and loess. Our aim is to review and create a reliable methodology for laser diffraction particle size analysis and optical particle shape investigations. We compare widely used pretreatment methods -which can be found in the literature- with each other. We are also taking into account that different sediment types need different pretreatment methods. We can state that the duration of chemical pretreatment can affect the optical properties (color), the texture and the mineral composition of the sediments, as well as the size and shape of mineral particles in the samples. The changes in these significant parameters can mislead the researcher’s main objectives. The study is supported by the ÚNKP-19-3 New National Excellence Program of the Ministry for Innovation and Technology. Support of the National Research, Development and Innovation Office NKFIH K120620 is gratefully acknowledged.
Turbulence-driven magnetic reconnection in the magnetosheath downstream of a quasi-parallel shock：a three-dimensional global hybrid simulation
Authors: Lu Quanming , Wang Huanyu , Wang Xueyi
Published: March 2020

Satellite observations with high-resolution measurements have demonstrated the existence of intermittent current sheets and occurrence of magnetic reconnection in a quasi-parallel magnetosheath behind the terrestrial bow shock. In this Letter, by performing a three-dimensional (3-D) global hybrid simulation, we investigated the characteristics of the quasi-parallel magnetosheath of the bow shock, which is formed due to the interaction of the solar wind with the earth’s magnetosphere. Current sheets with widths of several ion inertial lengths are found to be produced in the magnetosheath after the upstream large amplitude electromagnetic waves penetrate through the shock and are then compressed in the downstream. Magnetic reconnection consequently occurs in these current sheets, where high-speed ion flow jets are identified in the outflow region. Simultaneously, flux ropes with the extension (along the   direction) of about several earth’s radii are also observed. Our simulation shed new insight on the mechanism for the occurrence of magnetic reconnection in the quasi-parallel shocked magnetosheath.
Composable, Scalable Solvers on Staggered Grids
Authors: Sanan Patrick , May Dave
Published: March 2020

Scalable preconditioners for saddle point problems are essential to the solution of problems in geodynamics and beyond. Recent years have produced a wealth of research into efficient solvers for finite element methods.  These solvers are also effective, however, for orthogonal-grid finite volume discretizations of saddle point problems, also know as "staggered grid" or "marker and cell (MAC)" methods. Perhaps, ironically, due to the highly-structured nature of these discretizations, the use of advanced solvers is stymied due to the lack of a uniform topological abstraction, which is required for most scalable solvers, such as geometric multigrid.  We present new software to allow experimentation with and composition of these advanced solvers.  We focus on variable-viscosity Stokes problems with discontinuous coefficient jumps.  In particular, we attempt to demonstrate how the important know robust preconditioners may be employed, and how new variants may be experimented with.  Important solvers are compositions of block factorizations and multigrid cycles.  We demonstrate as many of these as possible, including triangular block preconditioners with nested multigrid solves, and monolithic multigrid solves with cellwise (Vanka) or field-based (Distributed Gauss-Seidel, Braess-Sarazin) smoothers.  Implementations are provided as part of the PETSc library, using the new DMStag component, and examples from the StagBL library are also shown where appropriate.  These tools are intended to help break down the barrier between cutting-edge research into advanced solvers (which is only becoming more complex, as multi-phase problems are further explored) and practical usage in geophysical research and production codes.
Investigating the impact of wind, waves and currents on the distribution of surface drifting particles with drifter data and a high resolution numerical model in the nearshore region
Authors: Hahner Florian , Meyerjürgens Jens , Wüllner Tim , Lettmann Karsten Alexander , Badewien Thomas , Zielinski Oliver , Wolff Jörg-Olaf
Published: March 2020

A coupled wave and ocean model within the COAWST Modelling System is used in a one-way nesting scenario to investigate the importance of wind, surface currents and Stokes drift for the distribution of surface drifting objects in the nearshore region of the East Frisian barrier island Spiekeroog in the North Sea. Stokes drift and surface currents are computed on a high resolution grid. Combination with meteorological data, Lagrangian floats and in situ data of surface drifters and wave radar measurements allows for a realistic estimation of wind drag coefficients and Stokes Drift. Therefore GPS-Box Drifters have been developed which resemble surface floating macroplastics. Complex topographic features with shallow areas and deep channels within this coastal region lead to strongly heterogeneous wave and current fields. Due to the high resolution of our numerical model these features can be described with the needed accuracy. At the same time computational costs are minimized by using a two-step nesting approach. We show that Stokes Drift becomes a major role in shallow coastal regions, even exceeding the influence of the wind drag, hence playing a key role for realistic descriptions of beaching and the recognition of litter accumulation.

 
Breaking Gender Barriers: Local actions towards gender equality
Authors: Ulvrova Martina
Published: March 2020

Geosciences together with larger STEM (Science, Technology, Engineering and Mathematics) communities are highly burdened with striking imbalance between female and male researchers especially at high level positions. Indeed, for example in Earth and Planetary Sciences women represent only around 37% of the scientific community. Moreover, different expressions of gender biases tend to preserve these male dominated environments and thwart achieving gender balanced work places. In this contribution, I present three local actions that aim to improve gender diversity in science and promote gender equality. 1) Together with the 500 Women Scientists organisation and supported by the host university, I have been organising a series of Breaking Gender Barriers discussion evenings. These events include short presentations by female experts, and panel and roundtable discussions. We target female researchers in their early careers to increase their competitiveness, motivate them, show them female role models and provide them with networking opportunities. 2) I co-created a mentoring group at my host institution that helps in career building, provides a safe environment for sharing and offers networking opportunities. 3) Lack of female role models in science (evinced already at very early age in the education chain) impedes heavily the communities to evolve into gender parity systems. That is why I present female scientific role models depicted on high quality posters to large public. Combination of these actions are critical in motivating young girls to pursue a scientific career, support sustainable career development and contribute as a solution to losing female researchers at diverse career stages known as the leaky pipeline problem.   
Nutrient sources in the Bohai Sea and Yellow Sea: results from seasonal sampling in 2018
Authors: Tian Shichao , Gaye Birgit , Tang Jianhui , Luo Yongming , Sanders Tina , Dähnke Kirstin , Emeis Kay-Christian
Published: March 2020

The Bohai Sea and Yellow Sea are semi-enclosed basins strongly affected by human activities due to climate change and growing industries in China. Changes of hydrology, nutrient concentrations and sources and resulting ecosystem responses are therefore progressively intensifying during the last decades. In order to characterize nutrient sources and dynamics and to estimate the anthropogenic impact, we investigated nutrient concentrations and dual isotopes of nitrate in spring and summer 2018 in Bohai Sea and Yellow Sea. Furthermore, we sampled suspended matter and surface sediments and determined organic carbon, nitrogen and stable nitrogen isotopic ratios.

In spring, the water column was well mixed and the study area was mainly affected by the Yellow River diluted water and the Yellow Sea Warm Current water, which were the main nitrate sources. In summer, the water was stratified, and the Yellow River and Changjiang River diluted water supplied nutrients to an even larger region than in spring. During this season, the Yellow Sea Cold Water mass formed the bottom water of the Yellow Sea where nutrients became enriched. In contrast to other polluted marginal seas, the stable isotopic ratios of dissolved and particulate nitrogen are relatively low in the study area, which could be due to nutrient supply from the atmosphere or the open ocean. Using nitrogen isotopes, we developed a box model of reactive nitrogen for the Bohai Sea and quantified the input of atmospheric and riverine reactive nitrogen, submarine groundwater and water exchange with the Yellow Sea, constraining the budgets of reactive nitrogen combining mass fluxes with an isotopic balance. Including the isotopic balance improved the mass balance based only on nutrient concentrations.