bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring Perturbations in the Lower-Ionosphere Using GNSS Radio Occultation Observed from Spire's Cubesat Constellation
Authors: Savastano Giorgio , Nordström Karl , Angling Matthew , Nguyen Vu , Duly Timothy , Yuasa Takayuki , Masters Dallas
Published: March 2020

The lower altitude region of the ionosphere (60-150 km) is characterized by a strong coupling between the neutral atmosphere and ionospheric plasma. Due to the high ion-neutral collision rate the plasma at these altitudes is less constrained to follow the magnetic field lines compared to plasma at higher altitudes in the ionosphere. This both permits the development of the windshear mechanism responsible for the formation of sporadic E (Es) layers and affects the coupling between atmospheric gravity waves (AGWs) and the ionospheric plasma. 

AGWs transport energy from the lower atmosphere upward to higher altitudes. The wave amplitudes increase with altitude and eventually couple to the ionospheric plasma generating electron density perturbations or travelling ionospheric disturbances (TIDs). 

Es layers are high-density, narrow-altitude layers of enhanced electron density in the ionosphere’s E region. Contrary to what the name would suggest, Es occurs relatively frequently and its climatology has been characterised through ionosonde studies. Furthermore, the vertical structure of Es has been studied using sounding rockets. However, such measurements are very sparse and cannot be used to routine monitoring or for detecting the Es occurrence at a particular time and location. 

Monitoring AGW and Es layers is of great interest to many terrestrial applications, such as natural hazard warning systems, radio communications, and global navigation satellite system (GNSS) users. Recently, the coupling between Es layers and AGWs has also seen increased research attention. 

Spire operates a large constellation of 3U cubesats which carry a radio occultation (RO) GNSS receiver. For ionospheric studies, the satellites measure Total Electron Content (TEC) data in both zenith-looking and RO geometries using dual frequency observations. Furthermore, the high rate (50Hz) phase measurements that are generally used for neutral atmosphere RO can also be used to produce relative TEC profiles of the lower ionosphere with high vertical resolution (approximately 100m at E region altitudes). In this talk, we review recent results describing the coverage and quality of E region ionospheric measurements collected by Spire. Furthermore, we describe Spire's Es and AGW automated detection algorithm that is based on a Hilbert–Huang transform (HHT) of the relative TEC profiles and we compare our results with time coincident and co-located ionosonde data. We also look toward the future and describe how low cost cubesat constellations can be used for global monitoring of AGWs and Es layers. These first results also open the way to near real-time monitoring and classification of more general ionospheric anomalies
The adjoint equations for thermochemical compressible mantle convection: derivation and verification by twin experiments
Authors: Ghelichkhan Sia , Bunge Hans-Peter
Published: March 2020

The adjoint method is an efficient way to obtain gradient information in a mantle convection model relative to past flow structure, allowing one to retrodict mantle flow from observations of the present-day mantle state. While adjoint equations for isochemical mantle flow have been derived for both incompressible and compressible flows, here we extend the method to thermochemical mantle flow models, and present thermochemical adjoint equations in the elastic-liquid approximation. We verify the method with twin experiments, and retrodict the flow history of a thermochemical reference model (reference twin) assuming for the final state, either a consistent thermochemical interpretation, using the thermochemical adjoint equations, or an inconsistent purely thermal interpretation, using the isochemical adjoint equations. The consistent simulation correctly retrodicts the flow evolution of the reference twin. The inconsistent case, instead, restores a false flow history whereby internal buoyancy forces and convectively maintained topography are overestimated. Because the cost function is reduced in either case, our results suggest that the adjoint method can be used to link assumptions on the role of chemical mantle heterogeneity to geologic inferences of dynamic topography, thus providing additional means to test hypotheses on mantle composition and dynamics.
Copernicus Climate Data Store: ready for application in adaptation case studies? – experiences of the training workshop in Hungary
Authors: Gálos Borbála , Lehoczky Annamária
Published: March 2020

As basis of climate change adaptation, good quality climate data and information is required, however, they are very often costly or difficult to access. The Climate Data Store (CDS) developed within Copernicus Climate Change Service aims to bridge the gap between data providers and users by ensuring a freely available, quality-assured information about the past, present and future climate. In order to make users familiar with the CDS, a national training event was organized in Hungary that contained two online webinars and a face-to-face workshop (October 2019). Researchers, lecturers, consultants and stakeholders from the field of agriculture, forestry, water management and environmental engineering have learned how climate data can be properly selected, analyzed and interpreted to address their climate change adaptation challenges. For their own adaptation case studies they tested the applicability of CDS and discussed the experiences in multidisciplinary teams.

Main feedbacks of the participants are:

The concept of CDS is welcome and relevant to their work. Provided climate variables are easily accessible and well documented.

For sectoral application, the country specific adaptation issues would require high spatial resolution (regional and local scale time series) and bias corrected model results instead of the currently available GCM outputs.

The Toolbox associated with the CDS should be more user friendly. At the moment (October 2019) high programming skills are essential to derive praxis-based extreme indices and create country-scale maps and graphs.

The e-learning material on the Learning Experience Platform contains carefully structured background knowledge to the sources, characteristics and proper application of climate data.

Further toolbox improvements driven by the user needs and the ongoing development of Sectoral Information Systems will significantly increase the applicability of the CDS for climate risk analyses and adaptation support in Hungary.

 

Acknowledgements: the training event was supported by the European Union Copernicus Climate Change Service and the Hungarian Meteorological Service.
Space Weather effects on Mars’ ionosphere: From our current knowledge to the way forward
Authors: Sánchez-Cano Beatriz
Published: March 2020

Planetary Space Weather is an emerging topic of increasing interest. Forecast this planetary space weather, however, is currently very challenging mainly due to the lack of continuous solar wind observations for each planet. In the particular case of Mars, understanding the ionospheric behaviour following Space Weather activity is essential in order to assess the response of the Martian plasma environment to the dissipation of energy from solar storms. Moreover, it gives information on the effects on the current technology deployed on the red planet. Despite the recent considerable exploration, however, there is still no continuous upstream solar wind observations at Mars. This fact makes the analysis of the different Martian plasma datasets challenging, relying on solar wind models and upstream solar wind observations at 1 AU (e.g. at Earth’s L1 point, STEREO, etc.) when Mars and those satellites are in apparent opposition or perfectly aligned in the Parker spiral.

This lecture will focus on our current knowledge of the Martian ionosphere, which is the layer that links the neutral atmosphere with space, and acts as the main obstacle to the solar wind. In particular, I will focus on our recent advances in the understanding of the Martian ionospheric reaction to different Space Weather events during the solar cycle, both from the data analysis and ionospheric modelling perspectives. Some important aspects to consider are the bow shock, magnetic pileup boundary, and ionopause characterization, as well as the behaviour of the topside and bottomside of the ionosphere taking into account the planet’s orbital eccentricity. Moreover, I will show the effect of electron precipitation from large Space Weather events in the very low Martian ionosphere, a region that it is non-accessible to in-situ spacecraft observations. Finally, I will conclude the presentation by giving my perspective on some of the key outstanding questions that remain unknown, and I consider they constitute the next generation of Mars’ ionospheric and Space Weather science and exploration.
Improvement of soil characteristics making use of logical, good agricultural practices: purpose and results obtained in the LIFE AMDRYC4 Project
Authors: Martinez-Sanchez Maria Jose , Martinez-Lopez Salvadora , Martinez-Martinez Lucia Belen , Ortega Maria , Hernandez-Cordoba Manuel , Perez-Sirvent Carmen
Published: March 2020

The modification of environmental conditions and the subsequent evolution of the ecosystems results in soil degradation or desertification, which is also caused by the abandonment of the countryside, poor agricultural practices and the socio-economic dynamics that nowadays presents the rural environment. Land degradation leads to loss of fertility, nutrients and vegetation cover and increased erosion, pollution, salinization and alkalinization. The effects derived from this situation aggravate, in turn, climate change, in a strongly intertwined dynamics that feeds back.

Degraded soils are recoverable through various strategies, among them good agricultural practices being especially relevant.  In this paper, the degree of desertification of several plots of soil that have undergone treatments for the incorporation of organic matter (sewage sludge, manure from different animals, composted plant remains) and their untreated counterparts (blank) is evaluated. To this end, desertification indicators (salinization, organic matter, phosphorus content) included in the LIFE AMDRYC4 Project have been used to monitor soil neutrality, as a measure of the global desertification suffered by a plot.

The results obtained clearly show an improvement in the soil characteristics following the application of the mentioned strategy for soil treatment. It is therefore concluded that soil degradation is mitigated by good agricultural practices, which leads to a decrease in erosion and salinization and an increase in organic matter, nutrient content, plant cover and the ability to sequester dioxide carbon.  Soils are not affected by polluting processes both in terms of potentially toxic elements and other emerging pollutants. The experimental data obtained indicate that soils in this way remediated can be used to reduce the concentration of greenhouse gases in the atmosphere and represent a good tool to fight against climate change.

 
Global Methane Emissions Through an Isotopic Lens
Authors: Drinkwater Alice , Arnold Tim , Palmer Paul
Published: March 2020

Changes in atmospheric methane (CH4) are mainly driven by natural, anthropogenic and pyrogenic emissions and oxidation by OH.

There is no consensus about the underlying explanations about hemispheric-scale changes in atmospheric methane (CH4). This is partly due to sparse data that do not exclusively identify individual changes in surface emissions and surface and atmospheric losses of CH4. This challenge represents a major scientific weakness in our understanding of this potent greenhouse gas, with implications for meeting global climate policy obligations.  A confounding challenge is that the regional importance of individual emission sources change with time due to, for example, innovations in agricultural practices, climate-sensitive wetlands, and political decisions associated with climate friendlier transitional fuels.  

Here we use bulk isotope ratios δ13C and δD of CH4 that have been previously shown to provide effective constraints on source apportionment: different CH4 sources have characteristic isotope ratios. One of the key challenges associated with using these data is that region-specific isotope ratios change with time due to varying source prevalance, in addition to source signatures having inherent uncertainties. We use the GEOS-Chem global 3-D chemical transport model to describe the spatial and temporal isotopic behaviour of atmospheric CH4. We develop a Maximum A-Posteriori inverse method to simultaneously infer time dependent CH4 emissions and isotope ratios from in situ data. 

We will report the magnitude, distribution and source attribution of CH4 emissions from 2004 to 2017, inferred from in situ measurements of total atmospheric CH4 mole fraction and the corresponding measurements of δ13C and δD. We will compare our results with previous studies.
Model Calculations of the F-Corona and inner Zodiacal Light
Authors: Eren Saliha , Mann Ingrid
Published: March 2020

The white-light Fraunhofer corona (F-corona) and inner Zodiacal light are generated by interplanetary (Zodiacal) dust particles that are located between Sun and observer. At visible wavelength the brightness comes from sunlight scattered at the dust particles. F-corona and inner Zodiacal light were recently observed from STEREO (Stenborg et al. 2018) and Parker Solar Probe (Howard et al. 2019) spacecraft which motivates our model calculations. We investigate the brightness by integration of scattered light along the line of sight of observations. We include a three-dimensional distribution of the Zodiacal dust that describes well the brightness of the Zodiacal light at larger elongations, a dust size distribution derived from observations at 1AU and assume Mie scattering at silicate particles to describe the scattered light over a large size distribution from 1 nm to 100 µm. From our simulations, we calculate the flattening index of the F-corona, which is the ratio of the minor axis to the major axis found for isophotes at different distances from the Sun, respectively elongations of the line of sight. Our results agree well with results from STEREO/SECCHI observational data where the flattening index varies from 0.45° and 0.65° at elongations between 5° and 24°. To compare with Parker Solar Probe observations, we investigate how the brightness changes when the observer moves closer to the Sun. This brightness change is influenced by the dust number density along the line of sight and by the changing scattering geometry.

-Stenborg G., Howard R. A., and Stauffer J. R., 2018: Characterization of the White-light Brightness of the F-corona between 5° and 24° Elongation, Astrophys. J. 862: 168 (21pp).

-Howard, R.A. and 25 co-authors, 2019: Near-Sun observations of an F-corona decrease and K-corona fine structure, Nature 576, 232–236.
Estimating global warming and natural variability signals in the ocean south of Iceland
Authors: Jónsson Steingrímur
Published: March 2020

The temperature in the Atlantic waters south of Iceland has increased by about 1°C since 1995 with most of the rise occurring before 2000. A similar rise in air temperature in Iceland was observed simultaneously and the rise in temperature is often interpreted as being caused by global warming. Many effects of this in the ocean and on land such as changed distribution of marine species in the area as well as melting of glaciers in Iceland have been attributed to this rising temperature. However, it is unlikely that this rapid increase in temperature was solely due to global warming, especially since it was accompanied by an increase in salinity. It is more likely that there was a change in the ocean circulation in the area leading to more sub-tropical water entering the sub-polar gyre causing a shift in temperature and salinity. A similar increase in temperature and salinity was observed earlier during 1930-1964 in this area. Between the two warm periods the waters were dominated by lower temperature and salinity. These changes have been related to the Atlantic Multidecadal Oscillation. By comparing the water mass properties in the two warm periods it is possible to estimate the relative contribution from natural variability and global warming for the recent warm period. It will be shown how the retreat and advancing of glaciers in Iceland are in harmony with the changes in water mass properties in the waters south of Iceland. It is important that decisions about how to adapt to coming climate change are based on how much of the observed change is due to natural variability and global warming respectively. This is a method that can be used in other areas of the northern North Atlantic.
Probing mantle plumes using seismic arrays
Authors: Cobden Laura , Afanasiev Michael , Deschamps Frederic , Stockmann Fabienne , Thomas Christine , Rost Sebastian , Fichtner Andreas
Published: March 2020

Elucidating the role of deep mantle plumes in mantle convection is challenging because their influence on seismic waveforms – which could be used to map their location – is subtle. Previous seismic studies have mainly focused on waveform modelling and inversion (i.e. tomography). In this study we instead consider the potential visibility of mantle plumes using array methods. We investigate, in particular, how plumes deviate seismic energy from the great-circle path. This requires a multidisciplinary approach: first, we perform geodynamic modelling to generate thermochemical plumes, and convert them to “seismic” plumes via thermodynamic modelling of mineral physics data. Next, spectral element methods are used to model the interaction of seismic waves with the plumes and generate synthetic seismograms. These seismograms are divided into arrays and we generate slowness-backazimuth plots for each array. With recent advances in computational methods and resources, we investigate wave behaviour at previously unattainable frequencies.  We find that plumes do indeed cause seismic waves to change direction, although the exact behaviour may be frequency-dependent, and at low frequencies we observe waves apparently bending around the plume conduit.  We consider how and where these results may be applied to real seismic arrays, to provide new constraints on the location and structure of mantle plumes.
Arctic closure as a trigger for Atlantic overturning at the Eocene-Oligocene Transition
Authors: Hutchinson David , Coxall Helen , O'Regan Matt , Nilsson Johan , Caballero Rodrigo , de Boer Agatha
Published: March 2020

The Eocene-Oligocene Transition (EOT), approximately 34 Ma ago, marks a period of major global cooling and inception of the Antarctic ice sheet. Proxies of deep circulation suggest a contemporaneous onset or strengthening of the Atlantic meridional overturning circulation (AMOC). Proxy evidence of gradual salinification of the North Atlantic and tectonically driven isolation of the Arctic suggest that closing the Arctic-Atlantic gateway could have triggered the AMOC at the EOT. We demonstrate this trigger of the AMOC using a new paleoclimate model with late Eocene boundary conditions. The control simulation reproduces Eocene observations of low Arctic salinities. Subsequent closure of the Arctic-Atlantic gateway triggers the AMOC by blocking freshwater inflow from the Arctic. Salt advection feedbacks then lead to cessation of overturning in the North Pacific. These circulation changes imply major warming of the North Atlantic Ocean, and simultaneous cooling of the North Pacific, but no interhemispheric change in temperatures.
Statistical occurrence of mirror mode waves at Mars
Authors: Simon Wedlund Cyril , Volwerk Martin , Mazelle Christian , Möstl Christian , Rojas-Castillo Diana , Espley Jared , Halekas Jasper
Published: March 2020

Ultra low-frequency wave activity such as mirror mode (MM) waves, arising from an ion temperature anisotropy in the plasma, has been ubiquitously detected in the magnetosheaths of Venus and Mars. The MM instability is usually triggered behind a quasi-perpendicular bow shock in a high plasma β. We present here a statistical survey of these waves at Mars using magnetometer and ion data from the NASA/MAVEN mission between 2014 and 2019 (solar cycle 24, receding activity). First, quasi-perpendicular bow shock crossings are identified in the data using simple bow shock models (Edberg et al. 2008, Gruesbeck et al. 2018, Hall et al. 2019). MM waves are then automatically detected for these conditions, first from magnetometer measurements only (in the manner of Volwerk et al., 2016), and second using both magnetometer and ion moments to refine the analysis. Maps of MM wave occurrence for solar cycle 24 are presented and preliminary comparisons with similar and different solar activity conditions with MGS and Mars Express data are discussed.
The flood bore problem and the mushroom jet formation in the dam-break flow
Authors: Shugan Igor , Chen Yang-Yi , Hsu Cheng-Jung
Published: March 2020

Dam-break flows are not only an important practical problem in civil and hydraulic engineering, but also a fundamental problem of fluid mechanics. Due to property damage and the loss of numerous lives, it is critically important to have an exhaustive understanding of the landslide dam-break flow and sedimentation. The main objective of this study is a detailed analysis of the mechanisms of dam breaking flows through physical and theoretical modeling.     

       Our experimental work was focused on the initial stages of dam-break flow in the water channel, where a thin plate separating water at different levels is impulsively withdrawn in the vertical direction upwards, and as a result, a hydrodynamic bore is formed.

       The theoretical model of the dam-break flow is based on Benney’s shallow water equations. We separately studied the regimes of a breaking and non-breaking bore front. On the hydrodynamic bore, the laws of conservation of mass, momentum and energy were required to be fulfilled,contrary to the classical solutions of Ritter and Stoker, in which the law of energy was not considered at all.

      The non-breaking flow includes several zones: a shock wave and a shear vortex flow after it, a contact surface and a continuous discharge zone. The bore in our solution moves faster than the classical bore, which, in turn, propagates faster than the contact surface.

      The breaking bore is characterised by the generation of a “mushroom jet” structure, including a pair of vortexes, oppositely directed, and a forerunner formed by the plunging jet directed forward. We found that the forerunner of the breaking bore has a speed significantly higher than the speed of the bore.

       The experiments carried out in the wave flume of the Tainan Hydraulics Laboratory confirmed the theoretical predictions of the proposed dam breaking flow model for various initial conditions.
Evaluation the MOD10A1 daily snow albedo product (v. 6) on Livingston Island, Antarctica
Authors: Corbea-Pérez Alejandro , Fernández-Calleja Javier , Recondo Carmen , Fernández Susana
Published: March 2020

One of the factors that can most influence climate changes on a global scale is the albedo decrease, associated with a temperature increase and a snow cover decrease, mainly in the polar areas, where the remote sensing data are essential because there is much difficulty access to obtain measurements in situ. Therefore, evaluations of satellite measurements are essential.

The daily MOD10A1 snow product provides daily measurements of albedo. Version 6 is currently available. In Antarctica, and more specifically on Livingston Island (South Shetland Archipelago), where one of the Spanish Antarctic bases is located, the daily snow albedo product of MODIS (MOD10A1) has been evaluated using version 5 data (Calleja et al. 2019). However, several authors have recommended updating the analyses based on version 6 data (Box et al. 2012, Casey et al. 2017), as they are more accurate.

In this work, we have analyzed the albedo behavior using MOD10A1 version 6 data between 2006 and 2015 and we have seen an increasing trend of albedo. Version 5 showed an increase of 0.07 per decade. However, version 6 data show less variability (0.04 per decade), and its results are closer to those obtained in the measurements in situ (0.03 per decade). In addition, the results obtained allow us to affirm that the MOD10A1 daily albedo product (v. 6) can be used to determine the albedo in the study area.

References:

Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., & Steffen, K. (2012). Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers. The Cryosphere, 6(4), 821-839.

Calleja, J. F., Corbea-Pérez, A., Fernández, S., Recondo, C., Peón, J., & de Pablo, M. Á. (2019). Snow Albedo Seasonality and Trend from MODIS Sensor and Ground Data at Johnsons Glacier, Livingston Island, Maritime Antarctica. Sensors, 19(16), 3569.

Casey, K. A., Polashenski, C. M., Chen, J., & Tedesco, M. (2017). Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends. The Cryosphere, 11(4), 1781-1795.
Preparing for fine-scale ocean surface topography observations with the Surface Water and Ocean Topography (SWOT) Mission
Authors: Morrow Rosemary , Fu Lee-Lueng
Published: March 2020

The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in late 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6° latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15-30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at these smaller scales, that are important in the generation and dissipation of ocean kinetic energy, and are one of the main gateways connecting the surface to the ocean interior. Active vertical exchanges linked to these scales have impacts on the local and global budgets of heat and carbon, and on nutrients for biogeochemical cycles.

SWOT’s unprecedented 2D ocean SSH observations include “balanced” geostrophic eddy motions and high-frequency internal tides and internal waves. SWOT will provide global observations of the 2D structure of these phenomena, enabling us to learn more about their interactions, and helping us to interpret what is currently observed in 1D with conventional altimetry. Yet this mix of balanced and unbalanced motions is a challenge for calculating geostrophic currents directly from SSH or for reconstructing the 4D upper ocean circulation. At these small scales, the ocean dynamics evolve rapidly, and even with SWOT’s 2D SSH images, one satellite cannot observe the temporal evolution of these processes. SWOT data will need to be combined with other satellite and in-situ data and models to better understand the upper ocean 4D circulation (x,y,z,t) over the next decade. SWOT’s new technology will be a forerunner for the future altimetric observing system.

We will present recent progress in understanding the ocean dynamics contributing to fine-scale sea-surface height, including high-frequency processes such as internal tides, from 1D alongtrack altimetry, SAR data, in-situ data and models. We will also discuss the specific problems of validating the SWOT 2D small, rapid dynamics with in-situ data and other satellite data. 
Towards long open-path FTIR spectrometry of CO2 and CH4 in an urban environment
Authors: Schmitt Tobias , Kleinschek Ralph , Batzler Dominic , Schmitt Stefan , Hase Frank , Griffith David W. T. , Butz André
Published: March 2020

Quantifying sources and sinks, as well as photochemical activity of trace gases in the lower troposphere, requires accurate measurements of the concentrations of the species of interest. While there exist in-situ measurement techniques, which are highly accurate, point-like measurements tend to suffer from insufficient representativeness, especially true for high-gradient environments, e.g., an urban setting. Hence, measuring those concentrations averaged on the length scales of a few kilometers is desirable. Further, quantifying emissions requires combining the concentration measurements with regional transport models, which cover a comparable spatial resolution.

Here, we present a long open-path setup that aims at delivering concentration averages on these scales in the urban boundary layer. Our setup is based on an IFS 125 HR Fourier transform spectrometer, which is a commercially available, high precision spectrometer for the IR to near UV regime. We use an artificial light source, which is modulated within the interferometer of the instrument. The modulated beam is then sent towards an array of retro-reflectors 1.5 km away. Sending of the initial beam and collecting of the reflected light is accomplished by a single telescope, which is coupled to the instrument via an optical fiber. The collected light is measured using an InGaS detector. In a first feasibility study, we aim at measuring CO2 and CH4 above Heidelberg to quantify the achievable precision and accuracy. Here we present our setup, first measurements, and ongoing developments.
Links of Atmospheric Blocking to Temperature Extremes over Ukraine
Authors: Popova Lidiia , Khomenko Inna
Published: March 2020

Atmospheric blocking is a phenomenon in which a large, quasi-stationary anticyclone develops in the mid-latitudes and persists for several days or longer, blocking the ambient westerly winds and weather systems. Extremes on both ends of the temperature distribution are especially closely connected to atmospheric blocking (Brunner et al. 2017).

In this study the link between atmospheric blocking and Ukrainian cold and warm spells is investigated during winter and summertime in the period of 1991-2019 in order to provide better insight into the shifting role of blocking for extremes. Extreme temperatures are termed cold or warm spells if temperature stays outside the 10th to 90th percentile range at least six consecutive days. The detection of temperature extremes is based on daily minimum and maximum temperatures obtained for 12 meteorological stations that evenly cover territory of Ukraine. In the database obtained only the high-impact extreme temperature episodes are selected to be investigated in the further study.

The atmospheric blocking is detected on the basis of the daily 500 hPa geopotential height fields from the NCEP/NCAR reanalysis and potential temperature fields on the dynamical tropopause (PV = 2 PVU) obtained from ERA-Interim. In order to objectively diagnose atmospheric blocking two standard detection techniques are used. The first method utilizing the reversal of mid-latitude 500hPa geopotential height gradients was elaborated by Tibaldi and Molteni (1990) and detailed in Trigo et al. (2004), and the other one using reversal of potential temperature gradients was developed in Pelly and Hoskins (2003). These blocking detection algorithms identify fairly well the breaking of upper-level Rossby waves on 500 hPa height and on the dynamic tropopause, associated with onset of mid-latitude atmospheric blocking.

Up to 80% of winter cold and summer hot temperatures in Ukraine are associated with a collocated blocking. Large positive anomalies of 500 hPa geopotential height play a key role in maintaining prolonged extreme temperature spells and atmospheric blocking, though spell and blocking periods are much shorter than periods of positive anomalies. Spatio-temporal distribution of both indices are uneven, which meant that the wave-breaking process is not steady either at the 500 hPa surface or on the dynamical tropopause. Thus, during each episode the prolonged existence of ridges are maintained due not only to breaking of Rossby waves, but other mechanisms It should be mentioned that atmospheric blocking is more frequently revealed with the Tibaldi-Molteni indices than the Pelly-Hoskins ones, meaning that breaking of Rossby waves occurs more frequently at the 500 hPa geopotential height than on the tropopause.
Examining the Effects of Heat Mitigation on the Physical Properties of Urban Green Space and Urban Blue Space: A Case Study
Authors: Shetty Pruthvin , g s Dwarakish
Published: March 2020

The smart and sustainable city idea gained momentum in recent years in order to cope with population growth in urban areas and to make the city live. Cities are projected to consume 70% of the world's resources and 66% of the world population by 2050. Most of tier-3 and tier-2 cities will convert to tier-1 city, and we need to identify and protect the urban green spaces. Urban green areas have many esthetic advantages, including environmental benefits such as a fall in city temperature in the summer and absorption of rainwater. Social advantages are such as feelings of happiness and peace. Objective quantification of greenery on its neighbourhood spatial distribution may help identify essential and potential areas. Heterogeneous land uses describe urban areas. Urban heat island (UHI), with high Land surface temperatures (LST), is distinguished by its city development pattern, socioeconomic and anthropogenic activities. The LST is rising rapidly not only in cities but also in tier-3 & tier-2 cities.  Urban green areas, including parks, playgrounds, gardens and areas, such as ponds, pools, lakes and rivers, will contribute to the control of land temperatures in and around the city. Such spaces also lead to the formation of the Urban Cooling Island (UCI), where temperatures are comparatively cooler than surrounding temperatures, because of their shade of the trees and their evapotranspiration. This cooling island formation is referred to as the Park Cooling Island (PCI) impact. The present work aims to describe the effect of urban green and urban blue spaces on LST using a range of data sources with geospatial technologies. Udupi town, which comes under Udupi district, Karnataka, India is a tier-3 city, selected for the present research work. The data used in the study include Landsat 8 temporal satellite images and secondary data, such as field data from various government and semi-government organisations. LST has been measured using the emissivity reference channel algorithm from Landsat 8 thermal bands. Different indices such as Normalized Difference Built-up Index (NDBI), Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index NDWI, Land Shape Index (LSI) are determined from images from Landsat 8. The results show that LST exists with high spatial variability and urban green, blue spaces have a stronger influence on LST.
First-order machine learning based detection and classification of foraminifera in marine sediments from Arctic environments
Authors: Aagaard-Sørensen Steffen , Haugland Johansen Thomas , Junttila Juho
Published: March 2020

Foraminifera are microscopic single-celled organisms, ubiquitous to the marine realm, that construct shells during their life cycle. The shells, in general, fossilize well in the sediment and they are diagnosable due to inter-species morphology and ornamentation variability. Classifying and counting foraminiferal shells is an important tool in assessing and reconstructing past and present environmental, oceanographic and climatological conditions. However, the present day manual identification procedure, performed with a microscope and a needle/brush, is a very time consuming. Circumventing this manual procedure, using machine leaning, promises to dramatically lower the time consumption related to generating foraminiferal data records.

The first step towards that end is developing a deep learning model that can detect and classify microscopic foraminifera from 2D digital microscope pictures. The work is based on a VGG16 model implementation that has been pre trained on the ImageNet dataset and employing transfer learning techniques to adapt the model to the foraminifera task. The 2D photographic training data input was constructed by combining objects representative of and extracted from Arctic marine sediments (100µm-1mm size fraction) from the Barents Sea region. Four object groups, including 1) calcareous and 2) agglutinated benthic foraminifera, 3) planktic foraminifera and 4) sediments were used in the training data construction. With the initial set-up the algorithms were able to identify adherence to one of the four groups correctly ~90% of the time and with further fine-tuning and refinement reaching 98% correct identifications.

The second step is to use machine leaning for classification of individual benthic calcareous foraminiferal species within the sediment. The work will focus on the 20 most common species that comprise ca. ≥ 80% of the total benthic calcareous foraminiferal fauna in the Arctic. The training of the algorithms will be done using targeted species-specific 2D photographic and 3D CT scanning data in addition to potentially using hyperspectral imaging.
The role of archaeological sites in conveying geoheritage awareness: a case from Southwestern Sardinia (Italy)
Authors: Melis Rita , Mariani Guido Stefano
Published: March 2020

In a world where the interaction between humans and the physical landscape is deep and widespread since prehistory, geological and cultural heritage are still very much separate and addressed by experts and professionals coming from very different fields. The scarcity of effective communication channels impairs shared experience and fruitful collaboration in enhancing geosite awareness in the general public. When integrated approaches appear, they often still concentrate on the cultural narration using geological and environmental information only to support a palimpsest very much human-centred. Attention on integrated divulgation of the geological and natural processes surrounding cultural sites is still lacking. In fact, there is the possibility of walking the opposite path: that is, of using cultural heritage in order to inform the public and divulgate past and current geological processes acting on the wider landscape. This is especially true in highly dynamic environments, where geomorphological processes visibly modify cultural landmarks over time. In this sense, coasts are the ideal setting. They have represented one of the preferential places for human settlement since the dawn of civilization. Coastal environments show strong, complex geomorphological dynamics subject to cycles and variations over time which can be recorded in many different archives, some readily understandable by non-experts.

In this contribution we bring examples of how the interaction between cultural heritage and geoheritage can be used to enhance the communication of geomorphological issues. The coastal area of the southwestern portion of Sardinia (Italy) is the location of numerous archaeological settlements, ranging from Mesolithic shelters to wide, majestic Punic and Roman trade ports and cities. Sea level rise since the Last Glacial Maximum has widely interested this territory, and its effect is very well recorded in archaeological contexts. Here, variations in topography and geomorphology are changing the contexts of the sites themselves and sometimes threat their integrity through different geological and geomorphological hazards. The development of narrations focused on explaining these processes, using the archaeological evidence as a tool to convey geological concepts, might raise geological awareness in the general public and spread knowledge about the geomorphological history and features of the local and global landscape.
Shear coupled grain boundary migration as a deformation mechanism in minerals.
Authors: Pennock Gill , Drury Martyn
Published: March 2020

A grain boundary can move under stress by a mechanism called shear coupled grain boundary migration (SC GBM) and contribute to strain. SC GBM is considered to be a general property of all grain boundaries over a wide range of misorientation angles, although higher deformation temperatures favour grain boundary sliding. Apart from a structured boundary interface, SC also requires a critical shear stress. We examine evidence for SC GBM in ice. An extensive literature study showed that SC GBM of high angle boundaries does occur in ice bicrystals that were probably deformed under conditions close to those found in nature. We conclude that SC GBM is likely to be an important deformation mechanism for geological materials, where extensive GBM occurs and also in nano sized materials, such as fault gauges.
The missing pieces for better future predictions in subarctic ecosystems
Authors: Pascual Descarrega Didac ,   Expert Assessment participants
Published: March 2020

Arctic and subarctic ecosystems are undergoing substantial changes in response to climatic and other anthropogenic drivers, and these changes are likely to continue over this Century. Due to the strong linkages between the biotic (vegetation and carbon cycle) and abiotic (permafrost, hydrology and local climate) ecosystem components, the total magnitude of these changes result from multiple interacting effects that can enhance or counter the direct effects. In some cases, short-lived extreme events can override climate-driven long-term trends. The field measurements can mostly tackle individual drivers rather than the interactions between them. Currently, a comprehensive assessment of the drivers of different changes and the magnitude of their impact on subarctic ecosystems is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years and encompasses the 12% of all published papers and the 19% of all study citations across the Arctic. In this study, we summarize and rank the direct and indirect drivers of ecosystem change in the Torneträsk area, and propose future research priorities identified to improve future predictions of ecosystem change. First, we identified the direct and indirect changing drivers and the multiple related processes and feedbacks impacting the local climate, permafrost, hydrology, vegetation, and the carbon cycle based on the existing literature. Subsequently, an Expert Elicitation with the participation of 27 leading scientists was used to rank the short- (2020-2040) and long-term (2040-2100) future impact of these drivers according to their opinions on the relative importance and novelty. These two key evaluation matrices form the basis for identifying the current research priorities for subarctic regions. The relatively small size of the Torneträsk area, its great biological and geomorphological complexity, and its unique datasets is a microcosm of the subarctic and the rapidly transforming Arctic ecosystems that can help understand the ongoing processes and future ecosystem changes at a larger circumpolar-scale. This in turn will provide the basis for future mitigation and adaptation plans needed in a changing climate.
The Spanish node of the multidisciplinary integrated e-infrastructure EPOS
Authors: DeFelipe Irene , Alcalde Juan , Fernandez-Turiel Jose Luis , Diaz Jordi , Geyer Adelina , Molina Cecilia , Bernal Isabel , Fernandez Jose , Carbonell Ramon
Published: March 2020

The European Plate Observation System (EPOS, https://www.epos-ip.org/) is an e-infrastructure of ESFRI, the European Strategy Forum on Research Infrastructures (https://www.esfri.eu/), aimed at facilitating and promoting the integrated use of data, data products, services and facilities from internationally distributed research infrastructures for Solid Earth Science. This e-infrastructure is greatly committed to tackle viable solutions for Solid Earth challenges. It is a long-term plan that integrates research infrastructures of different European countries into a single inter-operable platform through different thematic core services (e.g., Seismology, Satellite data, Volcano Observations, Multi-Scale Laboratories). The Spanish EPOS node is coordinated by CSIC (the Spanish National Research Council) that hosts its own institutional repository, the DIGITAL.CSIC.

CSIC has adopted the European open data mandate and supports that data archives follow the FAIR principles of data management: Findable, Accessible, Interoperable, and Reusable. Therefore, data are broadly accessible to reuse for other researchers, industry, teaching, training and for the general public. Following these principles, the Institute of Earth Sciences Jaume Almera is updating and enlarging its database (https://digital.csic.es/handle/10261/101879, last access January 2020). These datasets include, among other, geophysical data acquired in the Iberian Peninsula since the 90’s. They comprise seismic studies of the structure of the crust in different geological settings, both on and offshore, and ranging from continental to exploration scale. These projects have been funded by public calls as well as from industry-funded research projects. As an example, these datasets contain data addressing the characterization of the shallow subsurface for the development of CO2, radioactive waste geologic storage sites, and to assess geologic hazards in the nearby of active faults. These datasets provide access to data that are relevant to assess sustainable and secure exploration and exploitation of the subsurface, a key societal challenge.

This work is a contribution of Project EPOS Sustainability Phase (EPOS SP), funded by the European Commission (Grant Agreement no: 871121 - EPOS SP-H2020-INFRADEV-2018-2020/H2020-INFRADEV-2019-2).
Spatial variations of mercury in sediments of Aviles Harbour and its implications on dredging
Authors: García Ordiales Efrén , Mangas Mario , Sanz-Prada Lorena , Pavoni Elena , Covelli Stefano , Roqueñí Nieves , Loredo Jorge , Cienfuegos Pablo
Published: March 2020

Aviles estuary is one of the most impacted estuaries of the north of Spain. In its margins, there are several heavy industries such as steel, zinc and aluminium factories together with other little factories dedicated to secondary metallurgical products. Because of the intense metallurgical activities developed in the area, sediments of the estuary show an important metal load. Among the different heavy metals present in the estuary, Hg in one of the most important due to its toxicity and potential transference to biota. To study the Hg concentrations present in the estuary, 52 scattered samples were collected. Samples were analysed for total Hg, and other parameters such as grain size, organic matter and sulphur have been determined. Total Hg concentration in the estuary sediments ranged between 0.1 to 18.3µg g-1 with an average of 4.3 µg g-1. The particle size of the sediment governed the mercury dispersion in the estuary. In the inner part where silt and clay fraction are predominant, Hg showed the highest values while in areas where sands predominate Hg concentrations decrease. The Hg concentration in a total of 36 samples exceed the probable effect level established by NOAA, which suggest that Hg may be transferred to the biota of the estuary and could be a problem for the health status of the area. On the other hand, concentrations of 26 samples were above the C level of the Spanish dredging regulations, limiting its management to encapsulation in non-vulnerable areas or its management as waste by an authorized manager.