bluuebunny/crossref_metadata_2025 huggingface dataset:
Solar Orbiter observations of magnetic Kelvin-Helmholtz waves in the solar wind
Authors: Kieokaew Rungployphan , Lavraud Benoit , Ruffolo David , Matthaeus William , Yang Yan , Stawarz Julia , Aizawa Sae , Louarn Philippe , Rouillard Alexis , Génot Vincent , Fedorov Andrey , Pinto Rui , Foullon Claire , Owen Christopher , Horbury Timothy
Published: March 2021

The Kelvin-Helmholtz instability (KHI) is a nonlinear shear-driven instability that develops at the interfaces between shear flows in plasmas. KHI is ubiquitous in plasmas and has been observed in situ at planetary interfaces and at the boundaries of coronal mass ejections in remote-sensing observations. KHI is also expected to develop at flow shear interfaces in the solar wind, but while it was hypothesized to play an important role in the mixing of plasmas and exciting solar wind fluctuations, its direct observation in the solar wind was still lacking. We report first in-situ observations of ongoing KHI in the solar wind using Solar Orbiter during its cruise phase. The KHI is found in a shear layer in the slow solar wind near the Heliospheric Current Sheet. We find that the observed conditions satisfy the KHI onset criterion from linear theory and the steepening of the shear boundary layer is consistent with the development of KH vortices. We further investigate the solar wind source of this event to understand the conditions that support KH growth. In addition, we set up a local MHD simulation using the empirical values to reproduce the observed KHI. This observed KHI in the solar wind provides robust evidence that shear instability develops in the solar wind, with obvious implications in the driving of solar wind fluctuations and turbulence. The reasons for the lack of previous such measurements are also discussed.
New insights into Southern Caucasian glacial-interglacial climate conditions inferred from Quaternary gastropod faunas
Authors: Richter Christiane
Published: March 2021

New insights into Southern Caucasian glacial-interglacial climate conditions inferred from Quaternary gastropod faunas

Dr. Christiane Richter1, Dr. Daniel Wolf1, Dipl.-Biol. Frank Walther2, Dr. Stefan Meng3, Dr. Lilit Sahakyan4, M. Sc. Tilmann Wolpert5, Prof. Dr. Markus Fuchs5, Prof. Dr. Michael Zech1, Prof. Dr. Dominik Faust1

1Dresden University of Technology, Helmholtzstr. 10, 01069 Dresden, Germany

2 University Hamburg, Centrum für Naturkunde, Martin-Luther-Platz 3, 20146 Hamburg, Germany

3 Ernst-Moritz-Arndt-University Greifswald, Friedrich-Ludwig-Jahn-Str. 17a, 17489 Greifswald, Germany

4 National Academy of Sciences of the Republic of Armenia, Baghramyan Ave. 24a, 0019 Yerevan,
  Armenia

5 Justus-Liebig-University Giessen, Senckenbergstr. 1, 35390 Gießen, Germany

We present our latest results  from gastropod analyses conducted on loess palaeosol sequences from northeast Armenia (Southern Caucasia) covering at least three glacial-interglacial cycles. The ecostratigraphy shows significant patterns of species composition related to the succession of pedocomplexes and loess, respectively. Pedocomplexes included species that can be associated with highgrass- to forest-steppe biomes, indicating increased humidity for these sections compared to loess layers. In contrast, loess layers that relate to glacial periods are associated with gastropod species of semidesert environments with shrub- and shortgrass-steppes, indicating semiarid to arid conditions. Furthermore, the loess deposits do not show any evidence for cold-adapted gastropod species. Therefore we suggest that average July temperatures in the study area were above 10°C, even during periods of loess deposition. We propose, that the limiting factor for bios during glacial periods was aridity, rather than temperature. In addition, we observe environmental differences between the various glacial times, with our results indicating a trend towards steadily increasing aridity in Southern Caucasia across the Middle to Late Pleistocene.
New Nd-Sr isotope-geochronological evidence of its affinity to the East-Scandinavian Large Igneous Province (The Kandalaksha-Kolvitsa gabbro-anorthosite complex, Russia)
Authors: Steshenko Ekaterina , Serov Pavel , Kunakkuzin Evgeniy , Ekimova Nadezhda , Elizarov Dmitriy , Bayanova Tamara
Published: March 2021

The article provides new Sm-Nd and Nd-Sr isotope-geochronological data on rocks of the Paleoproterozoic Kandalaksha-Kolvitsa gabbro-anorthosite complex.

The Sm-Nd and Rb-Sr studies have provided data on isotope compositions of neodymium and strontium in rocks of both massifs. The isotope compositions of neodymium (eNd) range from -0.02 in norites of the Kandalaksha massif to -5.53 in lens bodies of gneiss granites of the Kolvitsa massif

Weakly radiogenic values of eNd = -1.0 – -1.2 dominate, which complies with characteristic values of Paleoproterozoic layered intrusions in Fennoscandia. Isotope compositions of strontium ranging from 0.7013 to 0.7025 also reflect typical values of a Paleoproterozoic igneous province [.

New data suggest that the Kandalaksha-Kolvitsa gabbro-anorthosite complex is confined to the East-Scandinavian Large Igneous Province with a protracted evolution at the turn of 2.53-2.39 Ga. According to geochronological and isotope Nd-Sr data, rocks of the Kandalaksha-Kolvitsa complex seem to have the same anomalous mantle source with Paleoproterozoic layered intrusions in the Baltic Shield (Fig. 3). The latter include Cu-Ni-Co-Cr+PGE deposits in the Monchegorsk ore area and Pechenga, Cr ores in the Pados massif, Fe-Ti-V Kolvitsa deposit, PGE and Cu-Ni Fedorovo-Pana layered complex  and Burakovsky intrusion, Cu-Ni-Co+PGE deposits in Finland, i.e. Kemi, Penikat, Akanvaara, Kontelainen, Tornio and many other. These deposits formed at two episodes, 2.53-2.39 Ga and 2.0-1.8 Ga, that refer to the beginning of rifting and the late rifting stage of the Fennoscandian Shield evolution, respectively.

Rocks of these intrusions referred to the pyroxenite-gabbronorite-anorthosite formation have similar isotope-geochemical features:

1) according to U-Pb and Sm-Nd geochronological data, the formation time span is 2530 to 2380 Ma;

2) the mantle reservoir feeding magmas that formed the massifs is rich in lithophile elements;  ISr values vary from 0.702 to 0.706, εNd(T) varies from +2 to -6;

3) the model Sm-Nd ages of TDM protoliths are 2.8-3.3 Ga.

The scientific research has been carried out in the framework of the State Research Contract of GI KSС RAS No. 0226-2019-0053, RFBR grant No. 18-05-70082 «Arctic’s Resources» and Presidium RAS Program No. 8.
Active faulting and deep-seated gravitational slope deformation in carbonate rocks (Central Apennines, Italy) 
Authors: Del Rio Luca , Moro Marco , Fondriest Michele , Gori Stefano , Falcucci Emanuela , Saroli Michele , Doumaz Fawzi , Cavallo Andrea , Di Toro Giulio
Published: March 2021

Abstract

Active faulting and Deep-seated Gravitational Slope Deformation (DGSD) constitute common geological hazards in mountain belts worldwide. In the Italian central Apennines, km-thick carbonate sedimentary sequences are cut by major active normal faults which shape the landscape generating intermontane basins. Geomorphological observations suggest that the DGSDs are commonly located in the fault footwalls.

          We selected five mountain slopes affected by DGSD and exposing the footwall of active seismic normal faults exhumed from 2 to 0.5 km depth. We combined field structural analysis of the slopes with microstructural investigation of the slipping zones from the slip surfaces of both DGSDs and major faults. The collected data show that DGSDs exploit pre-existing surfaces formed both at depth and near the ground surface by tectonic faulting and, locally, by gravitational collapse. At the microscale, the widespread compaction of micro-grains (e.g., clasts indentation) forming the cataclastic matrix of both normal faults and DGSDs is consistent with clast fragmentation, fluid-infiltration and congruent pressure-solution mechanisms active at low ambient temperatures and lithostatic pressures. These processes are more developed in the slipping zones of normal faults because of the larger displacement accommodated.

          We conclude that in carbonate rocks of the central Apennines, DGSDs commonly exploit pre-existing tectonic faults/fractures and, in addition, localize slip along newly formed fractures that accommodate deformation mechanisms similar to those associated to tectonic faulting. Furthermore, the exposure of sharp slip surfaces along mountain slopes in the central Apennines can result from both surface seismic rupturing and DGSD or by a combination of them.
Ozone super recovery cancelled in the Antarctic upper stratosphere
Authors: Maliniemi Ville , Arsenovic Pavle , Nesse Tyssøy Hilde , Smith-Johnsen Christine , Marsh Daniel R.
Published: March 2021

Ozone is expected to fully recover from the CFC-era by the end of the 21st century. Furthermore, because of the anthropogenic climate change, cooler stratosphere accelerates the ozone production and is projected to lead to a super recovery. We investigate the ozone distribution over the 21st century with four different future scenarios using simulations of the Whole Atmosphere Community Climate Model (WACCM). At the end of the 21st century, higher polar ozone levels than pre CFC-era are obtained in scenarios that have highest atmospheric radiative forcing. This is true in the Arctic stratosphere and the Antarctic lower stratosphere. The Antarctic upper stratosphere forms an exception, where different scenarios have similar level of ozone during winter. This results from excess nitrogen oxides (NOx) descending from above in stronger future scenarios. NOx is formed by energetic electron precipitation (EEP) in the thermosphere and the upper mesosphere, and descends faster through the mesosphere in stronger scenarios. This indicates that the EEP indirect effect will be important factor for the future Antarctic ozone evolution, and is potentially able to prevent the super recovery in the upper stratosphere.
Projections of the Fire Weather Index (FWI) using CORDEX-CORE simulations
Authors: Raffaele Francesca , Nogherotto Rita
Published: March 2021

Changes in global fire activity are influenced by a multitude of factors including land-cover change, policies, and climatic conditions. In this study we focus our attention on climate, investigating how relative humidity, wind, temperature and precipitation changes can act together in fire danger. Within the CORDEX-CORE initiative, two regional climate models (RCM) have been used at  0.22° resolution and to downscale 3 global climate models (GCMs) from the CMIP5 project. The analysis is carried out over 9 CORDEX domains for two climate scenarios namely the RCP2.6 and the RCP8.5. The high resolution regional climate simulations have been used to evaluate changes in the fire danger by means of the Fire Weather Index (FWI).  The attention is focused on the Mediterranean Basin and in South America, as well as in Australia and in the North America domains. Both climate scenarios show similar projections for the near future time slice (2031-2050) with an increase of the index in those areas that are already affected by seasonal fires such as Spain and Southern Italy for the Mediterranean Basin and the central band of Brazil. For the future time slice (2081-2100) the signal increases, and it is stronger for the RCP8.5 scenario in all regions as expected.

 
Patterns of terrestrial carbon distribution in the Arctic Ocean deduced from the Circum-Arctic Sediment CArbon DatabasE (CASCADE)
Authors: Martens Jannik , Wild Birgit , Semiletov Igor , Dudarev Oleg V. , Gustafsson Örjan
Published: March 2021

Climate change is expected to affect the release of organic carbon (OC) from Arctic permafrost systems and other terrestrial deposits. In addition to greenhouse gas emissions on land, a fraction of the organic matter is liberated to the aquatic cycle and migrates to the Arctic Ocean where it is either degraded or buried in sediments, foremost on the vast continental shelves.

The Arctic Ocean basin represents a large footprint for contemporary and past land-ocean transport of terrestrial OC. To this end, the Circum-Arctic Sediment CArbon DatabasE (CASCADE; https://doi.org/10.5194/essd-2020-401) was established to curate and harmonize data on OC and total nitrogen concentrations, carbon isotopes (δ13C, Δ14C) and terrestrial biomarkers (long-chain n-alkanes, n-alkanoic acids and lignin phenols) in an openly accessible data collection. CASCADE was populated using carbon data from both published records and unpublished data from a large community collaboration. The first release of CASCADE includes observations at thousands of oceanographic stations distributed over the shelves and the central basins of the Arctic Ocean, and also includes hundreds of sediment cores, representing a range of time scales (decadal to orbital).

Mapping CASCADE data provides an overview to start deducing sources, pathways and deposition of carbon in different regions of the Arctic Ocean. Dual-isotope (δ13C, Δ14C) source apportionment of OC and 210Pb dating of centennial-scale sediment cores permit quantitative analysis of sequestration of carbon transported from permafrost systems and other deposits to the Arctic Ocean. Preliminary results suggest that surface soils (incl. permafrost active layer) are the dominating terrestrial carbon source to Circum-Arctic shelf sediments. The second largest terrestrial source are Pleistocene ice-rich permafrost compartments (Ice Complex Deposits), which stretch along coastlines of the Laptev, East Siberian, Chukchi and Beaufort Seas and are highly vulnerable to coastal erosion and thermal collapse in a warming climate.

Climate change is likely to cause permafrost thawing by further deepening of the seasonal active layer and accelerated coastal erosion of permafrost, as well as disturbance of the vast boreal peatlands. CASCADE provides an integrated perspective and benchmark for lateral carbon remobilization and will fuel further empirical and modelling studies of Arctic biogeochemical cycles.
Geoethics needs multi-dimensional research agendas and practice
Authors: Nauen Cornelia E.
Published: March 2021

Geoethics have been developed as global ethics to face grand challenges for humanity by Peppoloni and Di Capua in 2020. Complementary to the UN Declaration of Human Rights the proposal of a responsible human development charter formulates universal duties to demonstrate ecological humanism. Commensurate with the need to operationalise such ambitions this paper suggests a multi-pronged approach.

Similar to conversations focused primarily on other scientific fields research agendas and practice in the earth and marine sciences would benefit from a more representative participation of actors from all fields of knowledge, genders, geographical areas, ethnic backgrounds and world views. Journals like Nature and other high-impact publications start giving more space to voices arguing for gendered research, more opportunities in academia and publishing to women and under-represented societal groups to achieve higher quality research for beneficial approaches to societal challenges.

One essential aspect is identifying and overcoming their tacit and not so tacit discrimination with a view to enable the much needed diversification of perspectives, cultures and knowledge sources in the search for a more viable trade-off between different possible responses.

Another, often linked, aspect is to ask questions in ways explicitly addressing a wider spectrum of societal risks and benefits. This is particularly obvious in health research mostly based on white male participants in clinical trials with high percentages of costly failures. But as recently becoming apparent, it also applies e.g. to AI research, now an ubiquitous tool in many research, production and service areas. Among the responses is the obligation for European research proposals to address gender in most thematic areas, including the geosciences, a requirement that almost certainly needs greater attention to avoid tokenism.

Moreover, particular attention is warranted to seek understanding and solutions for and with the substantial small-scale and artisanal sectors in mining, fisheries and other natural resource areas reviewed in earlier research. While traditional social structures can be important in some regions, unintended consequences of demand in globalised markets with strong wealth stratification are prone to create opportunistic rushes. Such attempts to get out of poverty very often come at a high cost to human and environmental health.

These challenges are best addressed by interdisciplinary and otherwise diversified research teams and inclusive forms of field testing conditions and impact of measures. These should be able to cover the multiple dimensions through in-depth, interactive study and exploration of practical approaches with socially, economically and environmentally acceptable trade-offs. Investment in inclusive quality education is expected to underpin longer-term advances towards living the principles of geoethics.
A novel index for ecological drought monitoring based on ecological water deficit: a case study of Northwestern China
Authors: Jiang Tianliang , Su Xiaoling
Published: March 2021

Although the concept of ecological drought was first defined by the Science for Nature and People Partnership (SNAPP) in 2016, there remains no widely accepted drought index for monitoring ecological drought. Therefore, this study constructed a new ecological drought monitoring index, the standardized ecological water deficit index (SEWDI). The SEWDI is based on the difference between ecological water requirements and consumption, referred to as the standardized precipitation index (SPI) method, which was used to monitor ecological drought in Northwestern China (NWRC). The performances of the SEWDI and four widely-used drought indices [standardized root soil moisture index (SSI), self-calibrated Palmer drought index (scPDSI), standardized precipitation-evaporation drought index (SPEI), and SPI) in monitoring ecological drought were evaluated through comparing the Pearson correlations between these indices and the standardized normalized difference vegetation index (SNDVI) under different time scales, wetness, and water use efficiencies (WUEs) of vegetation. Finally, the rotational empirical orthogonal function (REOF) was used to decompose the SEWDI at a 12-month scale in the NWRC during 1982–2015 to obtain five ecological drought regions. The characteristics of ecological drought in the NWRC, including intensity, duration, and frequency, were extracted using run theory. The results showed that the performance of the SEWDI in monitoring ecological drought was highest among the commonly-used drought indices evaluated under different time scales [average correlation coefficient values (r) between SNDVI and drought indices: SEWDI= 0.34, SSI= 0.24, scPDSI= 0.23, SPI= 0.20, SPEI= 0.18), and the 12-month-scale SEWDI was largely unaffected by wetness and WUE. In addition, the results of the monitoring indicated that serious ecological droughts in the NWRC mainly occurred in 1982–1986, 1990–1996, and 2005–2010, primarily in regions I, II, and V, regions II, and IV, and in region III, IV, and V, respectively. This study provides a robust approach for quantifying ecological drought severity across natural vegetation areas and scientific evidence for governmental decision makers.
Variations of geomagnetic thresholds of cosmic rays and magnetospheric parameters during different phases  of the storm of November 20, 2003
Authors: Vernova Elena , Ptitsyna Natalia , Danilova Olga , Tyasto Marta
Published: March 2021

The correlations between variations in the geomagnetic cutoff rigidity of cosmic rays and the Dst and Kp geomagnetic indices and solar-wind and IMF parameters are calculated for the three phases of the magnetic storm of November 20–21, 2003: before the storm and during its main and recovery phases. The correlations are the strongest between variations in the cutoff rigidity and the Dst index during all stages. A significant correlation was recorded with the By component of IMF and the field magnitude B; the correlation with By dominated during the main phase, and the correlation with B was dominant during the recovery phase. There is also a high correlation with the dynamic parameters of solar activity during the main phase, especially with the solar-wind speed.

As far as we know, hysteresis phenomena have been discovered for the first time in the relationship between the cosmic-ray cutoff rigidities and the parameters of the helio- and magnetosphere on the scale of the magnetic storm (with Moscow station as an example). Loop-like patterns formed, because the trajectories of variations in the cutoff rigidities versus the studied parameters during storm intensification (development of current systems) did not coincide with the trajectories during the recovery phase (decay of current systems). The correlations of the cutoff rigidities with Dst and Kp indices were characterized by a narrow hysteresis loop, and their correlations with the IMF parameters were characterized by a wide hysteresis loop. The hysteresis loops for the relationship between the cutoff rigidities and solar-wind density and pressure were disordered.
Dynamics of Aeolian Sand Streamers and Airflow Turbulence over a Beach Surface
Authors: Baas Andreas
Published: March 2021

Sand transport by wind over granular beds displays dynamic structure and organisation in the form of streamers (aka ‘sand snakes’) that appear, meander and intertwine, and then dissipate as they are advected downwind. These patterns of saltating grain populations are thought to be initiated and controlled by coherent flow structures in the turbulent boundary layer wind that scrape over the bed surface raking up sand into entrainment. Streamer behaviour is thus fundamental to understanding sand transport dynamics, in particular its strong spatio-temporal variability, and is equally relevant to granular transport in other geophysical flows (fluvial, submarine).

This paper presents findings on streamer dynamics and associated wind turbulence observed in a field experiment on a beach, with measurements from 30Hz video-imagery using Large-Scale Particle Image Velocimetry (LS-PIV), combined with 50Hz wind measurements from 3D sonic anemometry and co-located sand transport rate monitoring using an array of laser particle counters (‘Wenglors’), all taking place over an area of ~10 m2 and over periods of several minutes. The video imagery was used to identify when and where streamers advected past the sonic anemometer and laser sensors so that relationships could be detected between the passage of turbulence structures in the airflow and the length- and time-scales, propagation speeds, and sand transport intensities of associated streamers. The findings form the basis for a phenomenological model of streamer dynamics under turbulent boundary layer flows that predicts the impact of spatio-temporal variability on local measurement of sand transport.
Machine-Learned Preconditioners for Linear Solvers in Geophysical Fluid Flows
Authors: Ackmann Jan , Düben Peter , Palmer Tim , Smolarkiewicz Piotr
Published: March 2021

Semi-implicit grid-point models for the atmosphere and the ocean require linear solvers that are working efficiently on modern supercomputers. The huge advantage of the semi-implicit time-stepping approach is that it enables large model time-steps. This however comes at the cost of having to solve a computationally demanding linear problem each model time-step to obtain an update to the model’s pressure/fluid-thickness field. In this study, we investigate whether machine learning approaches can be used to increase the efficiency of the linear solver.

Our machine learning approach aims at replacing a key component of the linear solver—the preconditioner. In the preconditioner an approximate matrix inversion is performed whose quality largely defines the linear solver’s performance. Embedding the machine-learning method within the framework of a linear solver circumvents potential robustness issues that machine learning approaches are often criticized for, as the linear solver ensures that a sufficient, pre-set level of accuracy is reached. The approach does not require prior availability of a conventional preconditioner and is highly flexible regarding complexity and machine learning design choices.

Several machine learning methods of different complexity from simple linear regression to deep feed-forward neural networks are used to learn the optimal preconditioner for a shallow-water model with semi-implicit time-stepping. The shallow-water model is specifically designed to be conceptually similar to more complex atmosphere models. The machine-learning preconditioner is competitive with a conventional preconditioner and provides good results even if it is used outside of the dynamical range of the training dataset.
Study of cirrus cloud properties and occurrence over Europe during the COVID-19 based on the lidar measurements of CALIPSO
Authors: Li Qiang , Groß Silke
Published: March 2021

Cirrus clouds have a wide global coverage providing considerable radiative forcing on the Earth’s climate system. Due to their inadequate representation in the global models, cirrus clouds can lead to large uncertainties in the climate prediction. To date, experimental and theoretical efforts have been widely carried out to study the anthropogenic effects such as aviation that may change the formation and microphysic and optical properties of cirrus clouds. Unfortunately, however, solid observational studies are still rare for us to draw any robust conclusion on anthropogenic influence on cirrus. During the COVID-19 pandemic the civil air traffic over Europe was significantly reduced. This unique situation provides a good opportunity to study the effect of air traffic on cirrus. In this work, based on the analysis of the CALIPSO measurements we present the changes of cirrus cloud properties and occurrence over Europe in March and April 2020 compared with the reference results in the previous years under normal conditions. The comparison shows that the cirrus cloud occurrence was reduced by about 30% with smaller cloud thicknesses found in April 2020. The average thickness of cirrus clouds was reduced to 1.18 km in April 2020 compared to a value of 1.40 km under normal conditions. In addition, the cirrus clouds measured in April 2020 possess smaller mean values of the particle linear depolarization ratio (PLDR) than the previous years at a high significance level, especially at colder temperatures (T<-50oC). The same exercises are extended to the observations over China and the United States. Besides the regional discrimination of cirrus clouds, we reach the final summary that cirrus clouds show significant changes in both March and April over Europe, no changes in both months over China, and significant changes only in April over the United States.
Understanding Bacterial Ice Nucleation
Authors: Schwidetzky Ralph , Lukas Max , Kunert Anna T. , Pöschl Ulrich , Fröhlich-Nowoisky Janine , Bonn Mischa , Meister Konrad
Published: March 2021

Bacterial ice-nucleating proteins (INPs) promote heterogeneous ice nucleation better than any known material. On the molecular scale, bacterial INPs are believed to function by organizing water into ice‑like patterns to enable the formation of embryonic crystals. However, the details of their working mechanism remains largely elusive. Here, we report the results of comprehensive evaluations of environmentally relevant effects such as changes in pH, the presence of ions and temperature on the activity, three-dimensional structure and hydration shell of bacterial ice nucleators using ice affinity purification, high-throughput ice nucleation assays and surface-specific sum-frequency generation spectroscopy.

 

[1] Lukas, Max, et al. "Electrostatic Interactions Control the Functionality of Bacterial Ice Nucleators." Journal of the American Chemical Society 142.15 (2020): 6842-6846.

[2] Lukas, Max, et al. "Interfacial Water Ordering Is Insufficient to Explain Ice-Nucleating Protein Activity." The Journal of Physical Chemistry Letters 12 (2020): 218-223.
New insights into the ice-covered Southern Ocean circulation from multi-altimeter combination.
Authors: Auger Matthis , Sallée Jean-Baptiste , Prandi Pierre
Published: March 2021

Subtle changes in the Southern Ocean subpolar ocean circulation patterns can lead to major changes in the global overturning circulation, as well as for floating ice-shelves with critical implications for global sea-level. It is therefore crucial to carefully understand Antarctic polar ocean circulation, but the lack of ocean observation has considerably blocked our advance in this field in the past.

In this study we benefit from a new high-resolution Sea Level Anomaly (SLA) product that has been specifically constructed to document sea-level in the ice-covered Southern Ocean. This product combines up to 3 satellite altimetry missions to map SLA data daily on an equal-area grid, including the ice-covered areas of the ocean from 2013 to 2019.

Results suggest that we can map ocean features with unprecedented resolution for the region. We characterize the main features of the subpolar Southern Ocean SLA and circulation seasonal cycle, being composed of three main modes of variability, significantly impacting the dynamics of the region. We explore how they are linked with atmospheric and sea-ice forcings. Dynamics at smaller scales are investigated, by identifying the properties of mesoscale variability where possible.
Climate literacy in the political forum using Canada as a case study
Authors: Galvez Rosa , Zrinyi Nick , Péloffy Karine , Laviolette Stéphane
Published: March 2021

Evidence-based policy is still lacking in decision-making in Canada and around the world. As much of the world now faces concurrent crises among which are climate change, a global pandemic, and rising wealth inequality, the relationship between politicians and scientists is more important than ever. Climate literacy among office-holders, public servants, and regulators is critical for ushering in change and much needed transformation. Using Canada as a case study, this presentation from an engineer-turned-politician will discuss (1) the progress that has been made in climate literacy, with particular attention to its evolution in the political forum and the role of politicians, (2) a discussion of Canada’s national and the global response to climate change and its link with the COVID-19 pandemic, (3) the climate literacy in the public sphere and the obstacles to its health including undue corporate influence and disinformation. Politicians have an ethical duty to uphold the interests of their constituents, a duty that extends to the environment and to future generations; best-available science rather than the allures of crony-capitalism must win out the tug-of-war to realize that duty.
Geodynamic inversion with uncertain initial geometries
Authors: Spang Arne , Baumann Tobias S. , Kaus Boris J. P.
Published: March 2021

Advanced numerical methods and increasing computational power have enabled us to incorporate numerical forward models into geodynamic inverse frameworks. We now have several strategies to constrain the rheological properties of the crust and lithosphere. Yet, the initial geometry of geological formations (e.g., salt bodies, magma bodies, subducting slabs) and associated uncertainties are, in most cases, excluded from the inverse problem and assumed to be part of the a priori knowledge. Usually, geometrical properties remain constant, or we employ simplified bodies like planes, spheres or ellipsoids for their parameterization.

Here, we present a simple method to parameterize complex three-dimensional bodies and incorporate them into geodynamic inverse problems. Our approach enables us to automatically create an entire ensemble of initial geometries within the uncertainty limits of geophysical imaging data. This not only allows us to account for geometric uncertainties, but also enables us to investigate the sensitivity of geophysical data to the geometrical properties of the geological structures.

We present 3 areas of application for our method, covering salt diapirs, magmatic systems and subduction zones, using both synthetic and real data.
Relict charcoal hearth landscape and soil profile characteristics surrounding a mid-19th century Appalachian iron furnace 
Authors: Bonhage Alexander , Bayuzick Samuel , Drohan Patrick , Hirsch Florian , Raab Thomas
Published: March 2021

Across much of the Mid-Atlantic United States and Europe, relict charcoal hearths (RCHs) are a common landscape feature once used as a primary fuel source for iron smelting and quick-lime production. We investigated a landscape surrounding the Monroe Furnace in central Pennsylvania, which was in operation for around 17 years until 1846. This preliminary investigation explores landscape patterns of hearth placement in relation to the furnace and landscape position and resulting potential effect on soil moisture. We mapped RCHs using LiDAR derived hillshade models of varying aspects, elevation, and slope. We classified the different shapes of RCHs in relation to their geomorphic positions and modeled both a topographic and soil wetness index for selected hearths and off-hearth locations nearby. Two hearths were sampled in the field and their morphology and soil properties investigated.

Hearths that were constructed on flatter slope gradients are seemingly more circular in shape and have more equal axes whereas steep slopes have a more oval shape elongated in one axis with the slope direction. More circular hearths are on or near flatter hillslope positions (such as on summits or shoulders) whereas eye-like shaped hearths are on steeper hillslope positions (like backslopes).  Based on initial topographic wetness index data, hearths are not acting as sinks for flow but instead often cause water to flow around them leading to drier conditions within RCHs.

Trenches alongside the slope orthogonal direction of the two sampled RCHs show a single layered stratigraphy, i.e. both sides had only one continuous technogenic, charcoal rich layer. The downslope half of both sites had generally higher contents of macroscopic charcoal pieces as well as buried colluvial- and buried fossilized A-horizons underlying the charcoal rich layer. Both sites are not perfectly levelled, but slightly sloped. Buried B- and colluvial horizons show signs of heat induced reddening of iron oxides on the top few centimeters. Preliminary results suggest significant differences in soil chemical and physical properties of the technogenic layer in comparison to the adjacent forest soils.
Non-sequential response in Mountainous Area of Southwest China
Authors: Liu Lin , Ran Qihua
Published: March 2021

Non-sequential response, the phenomenon that the water storage change in the lower layer bigger than that of the adjacent upper layer within a set time interval, is often ignored because of lacking of distributed measured data at watershed scale, especially in mountainous area where extensive monitoring network is expensive and difficult to deploy. In this study, the subsurface non-sequential response in a mountainous watershed in Southwest China was investigated, combining field monitoring and numerical simulation. A physics-based numerical model (InHM) was employed to simulate the proportion and position of occurrence of the subsurface non-sequential response. The topographic wetness index (TWI = ln(a/tan b)) was adopted to distinguish the topographic zone corresponding to the non-sequential response occurrence at different depths. The results showed that the storage change in deep layer is not as fast as that in shallow and middle layers due to less disturbance, and the non-sequential response mainly came from the subsurface lateral flow which accumulated at the soil-bedrock interface. During a rainfall event, the shallow soil layer responded rapidly, the saturation increased, the non-sequential response moved from the hillslope zone in the middle layer to the channel zone in the shallow layer, and accumulated gradually at the soil-bedrock interface. In case of double-peak rainfall event, the occurrence proportion of non-sequential response increased, the depth expanded vertically, and the accumulated response shifted from the channel zone to the hillslope zone, which would affect the outlet runoff. Counter to the subconscious, non-sequential response could still happen even when precipitation stopped. The results improve our understanding of non-sequential response and provide a scientific basis for flash flood research in mountainous areas.
The architecture and evolution of shallow water delta mouth bars: examples from the Lower Cretaceous of Spain
Authors: Watkinson Matthew , Cole Grant , Jerrett Rhodri
Published: March 2021

Improved understanding of delta mouth bar morphodynamics, and the resulting stratigraphic architectures, is important for predicting the loci of deposition of different sediment fractions, coastal geomorphic change and heterogeneity in mouth bar reservoirs. Facies and architectural analysis of exceptionally well-exposed shallow water (ca. 5 m depth) mouth bars and associated distributaries, from the Xert Formation (Lower Cretaceous), of the Maestrat Basin (east-central Spain), reveal that they grew via a succession of repeated autogenic cycles. The formation is part of a mixed clastic-carbonate succession deposited during a time of active faulting and incipient salt tectonism, but in an area away from their direct influence and where wave and tidal reworking were minimal.

An initial mouth bar accretion element forms after avulsion of a distributary into shallow standing water. Turbulent expansion of the fluvial jet and high bed friction results in rapid flow deceleration, and deposition of sediment in an aggradational to expansional bar-form. Vertical bar growth causes flattening and acceleration of the jet. The accelerated flow scours channels on the bar top, which focuses further expansion of the mouth bar at individual loci where the channels break through the front of the mouth bar. Here, new mouth bar accretion elements form, downlapping and onlapping against a readily recognizable surface of mouth bar reorganization. Vertical growth of the new mouth bar accretion elements causes flattening and re-acceleration of the jet, leading to channelization, and initiation of the next generation of mouth bar accretion elements. Thus the mouth bar grows, until bed-friction effects cause backwater deceleration and superelevation of flow in the feeding distributary. Within-channel sedimentation, choking and upstream avulsion of the feeding channel, results in mouth bar abandonment. In this study, mouth bars are formed of at least two to three accretion elements, before abandonment happened. The results of this study contrast with the notion that mouth bars form by simple vertical aggradation and radial expansion. However, the architecture and facies distributions of shallow water mouth bars are a predictable product of intrinsic processes that operate to deposit them.
Work towards the near real-time attribution of extreme weather and climate events at the German weather service (Deutscher Wetterdienst)
Authors: Tradowsky Jordis , Lorenz Philip , Kreienkamp Frank , Skålevåg Amalie
Published: March 2021

The interest in statements about the impact of climate change on a specific extreme weather or climate event is largest in the immediate aftermath of an event. The wider public and other stakeholder would like to know, ideally within days after an event occurred, if and how anthropogenic climate change has altered the frequency and severity of such an extreme event. While the scientific area of event attribution has developed quickly within the last decade, providing attribution statements shortly after the event is still a challenge.

To satisfy the public’s need for information, several groups are currently working towards a near real-time attribution system. As part of module B1.2 of the German ClimXtreme project, we are working on a prototype for a semi-automated attribution system to analyse extreme events affecting Germany. Initially, the focus is on heat waves, droughts, and extreme precipitation events, which have large impacts in Germany.

This attribution system will implement existing methodologies for the probabilistic event attribution and extend them, where required. Collaborations with international colleagues facilitate an ongoing exchange with the growing community specialising in extreme event attribution. A close collaboration with project partners within ClimXtreme will enable us to implement new methodologies from other modules of the ClimXtreme project.

In this presentation, we will give an overview of the scientific and technical approach, as well as the different methodologies that will be part of the prototype attribution system. We will also compare the methodologies and discuss their different benefits.
Variability of the frontal and eddies dynamics of the Kara Sea in the summer period
Authors: Konik Aleksandr , Zimin Alexey
Published: March 2021

The dynamics of fronts in the Arctic region is crucial in the formation and further variability of processes in the atmosphere and hydrosphere as a whole. However, the significant synoptic variability of the boundaries of the frontal zones and their characteristics determines the relevance of their study in a changing climate.

The article considers the relationship between the position of frontal zones and eddies structures in the Kara Sea in August and September 2019. To identify frontal zones, a single database is used, formed based on data on sea surface temperature from the Suomi NPP Viirs satellite, sea surface salinity from the NASA SMAP satellite and sea level from the international AVISO base. The cluster analysis method is used to detect frontal zones in the Kara Sea. To register the manifestations of eddies structures 358 Sentinel-1A and-1B satellite radar images obtained in the C-band at BB polarization and EW and IW shooting modes are analyzed.

It was possible to identify four classes of water in the sea area, one of which was identified as the River Plums frontal zone (RPFZ) the Ob and Yenisei. The maximum synoptic temperature gradient in the RPFZ region is 0.14°C/km, salinity is 0.12‰/km, and the level is 2 cm/km. It was found that the area of the RPFZ varies from 190K km2 in August to 221K km2 in September. During the research period, 1272 eddies structures were identified. It is shown that in August the number of eddies observed inside and within the boundaries of the frontal zones was twice as high as in September. In general, in the warm season of 2019 in the Kara Sea, most eddies occur in the RPFZ region. Thus, the number of eddies on the borders and inside the RPFZ in August is 30% more, and in September it is 20% more. The percentage difference is related to the wind impact over the Kara Sea, which is observed in September.

The analysis of the frontal zones and eddies in this work was supported by RFBR grant 20-35-90053.
The Young Island Ice Core - Climate Information of a Melty Archive
Authors: Moser Dorothea Elisabeth , Thomas Elizabeth R. , Jackson Sarah , Pedro Joel B. , Markle Bradley
Published: March 2021

Climate data from the sub-Antarctic region are extremely sparse, with few records available beyond the instrumental period. Here, we investigate the suitability of the first-ever ice core collected from Young Island, in the NW Ross Sea, to capture changes in climate. Despite the presence of surface melt at this maritime location, our findings indicate that stable water isotope and trace element records can still hold potential for paleoclimate reconstruction. We apply two multi-proxy dating approaches based on winter and summer signatures, develop an ice core chronology, and contextualize our findings using a local automatic weather station and reanalysis data. Subsequently, we draw first conclusions about the surface conditions at Young Island and discuss the site’s potential for future studies aimed at paleoclimate reconstruction and resolving the effects of surface melt on proxy records.
Effects of upstream conditions on ULF waves and SLAMS formation at Saturn
Authors: Bebesi Zsofia , Juhasz Antal
Published: March 2021

In this study we present occurences of SLAMS (short large-amplitude magnetic structures) upstream of the quasi-parallel bow shock of Saturn. Five events are analyzed in more detail using the data of the CAPS and MAG instruments of Cassini. Directional and speed analysis of the backstreaming particles related to ULF wave formation (and subsequent SLAMS evolution) in the foreshock region is presented. We also correlate the measured the ULF wave frequencies with the variations of the upstream magnetic field.
With a simple model we estimate the distance of the observed SLAMS from the bow shock front based on the measured plasma pressure. We also 
discuss the spatial characteristics of SLAMS observed near Saturn.
Using machine learning techniques to generate analog ensembles for data assimilation
Authors: Yang Lucia , Grooms Ian
Published: March 2021

We propose to use analogs of the forecast mean to generate an ensemble of perturbations for use in ensemble optimal interpolation (EnOI) or ensemble variational (EnVar) methods.  In addition to finding analogs from a library, we propose a new method of constructing analogs using autoencoders (a machine learning method).  To extend the scalability of constructed analogs for use in data assimilation on geophysical models, we propose using patching schemes to divide the global spatial domain into digestable chunks.  Using patches makes training the generative models possible and has the added benefit of being able to exploit parallel computing powers.  The resulting analog methods using analogs from a catalog (AnEnOI), constructed analogs (cAnEnOI), and patched constructed analogs (p-cAnEnOI) are tested in the context of a multiscale Lorenz-`96 model, with standard EnOI and an ensemble square root filter for comparison.  The use of analogs from a modestly-sized catalog is shown to improve the performance of EnOI, with limited marginal improvements resulting from increases in the catalog size.  The method using constructed analogs is found to perform as well as a full ensemble square root filter, and to be robust over a wide range of tuning parameters.  Lastly, we find that p-cAnENOI with larger patches produces the best data assimilation performance despite having larger reconstruction errors.  All patch variants except for the variant that uses the smallest patch size outperform cAnEnOI as well as some traditional data assimilation methods such as the ensemble square root filter.