bluuebunny/crossref_metadata_2025 huggingface dataset:
How well do seasonal forecasts reproduce European winter storm clustering and its relationship to large-scale climate drivers?
Authors: Angus Michael , Leckebusch Gregor
Published: March 2020

The inter-annual variability of the European windstorm season is dependent on a number of large-scale climate drivers and conditions, for example the North Atlantic Oscillation. For seasonal forecasts to provide valuable information to decision makers about the potential severity of the winter windstorm season, they must capture this relationship between large-scale climate drivers and seasonal windstorm frequency in advance. Here, we examine the performance of the latest state of the art ECMWF seasonal forecast product (SEAS5) in capturing this climate response. We apply a statistical model previously shown to well reproduce the explained behaviour of European windstorms from large-scale climate drivers (Walz et al. 2018) to SEAS5, and examine the choice of statistically significant drivers. The model applied is a stepwise Poisson regression approach to account for serial clustering within inter-annual variability of windstorms, the resultant of which categorizes each windstorm season as either active, neutral or inactive. In particular, we focus on the European region where the explained variance of the statistical model in observations is highest (Walz et al. 2018), the British Isles. In addition to comparing the performance of the model in SEAS5 and in observations, we examine which relationships are not recreated in the seasonal forecast successfully from a dynamical perspective, to provide further insight into the current ability of seasonal forecasts to represent European windstorm inter-annual variability.

 

Reference:

Walz, M. A., Befort, D. J., Kirchner‐Bossi, N. O., Ulbrich, U., & Leckebusch, G. C. (2018). Modelling serial clustering and inter‐annual variability of European winter windstorms based on large‐scale drivers. International Journal of Climatology, 38(7), 3044-3057.
An open-source toolset for automated processing of historic spy photos: sPyMicMac
Authors: McNabb Robert , Girod Luc , Nuth Christopher , Kääb Andreas
Published: March 2020

First launched in 1971, the KH-9 “Hexagon” reconnaissance satellites were operational until 1986. In addition to the high-resolution main cameras, the satellites had a secondary camera system, the mapping camera, which acquired images at approximately 6-10m ground resolution. These images, declassified in 2002, provide an unparalleled ability to extend records of elevation change over areas of the world where older data, typically from aerial photogrammetry, are missing, unavailable, or unreliable, including High Mountain Asia and the Arctic. These images are not, however, free from challenges. Storage and film processing have introduced warping into the images, and the large film format means that images are scanned in halves which must be precisely re-aligned for photogrammetric processing.

 

Building on previous efforts, we have developed an open-source toolset, based in python, that performs several of the steps necessary for processing digital elevation models (DEMs) from the raw imagery within MicMac. These include precise re-alignment based on dense keypoint detection, automated detection of the reseau field to aid in un-warping of the images, color balancing to increase contrast in low-contrast areas, and automated detection of ground control points using modern orthorectified satellite images such as Sentinel-2 and Landsat 8, and high-resolution digital elevation models such as ArcticDEM. Each of these tools interface with the MicMac photogrammetry software package that performs each of the steps necessary for DEM extraction.

 

We have tested this toolset on scenes from Alaska, Iceland, and Norway. Comparison to external elevation datasets such as NASA’s Ice, Cloud and Elevation Satellite (ICESat), ArcticDEM, and national elevation products yields agreement of better than 10 m root mean square error over stable terrain, even in mountainous areas. In particular, we obtain satisfactory results in remote areas where precise ground control measurements are difficult to obtain. This toolset provides the ability to easily extend records of precise elevation change in areas where very little historic data exist. In addition, the GCP matching routine can be used to process other air photo datasets, providing a useful tool for processing older photo archives.
Divide mobility controls knickpoint migration on the Roan Plateau
Authors: Schwanghart Wolfgang , Scherler Dirk
Published: March 2020

Knickpoints in longitudinal river profiles provide proxies for the climatic and tectonic history of active mountains. The analysis of river profiles commonly relies on the assumption that drainage network configurations are stable. Here we show that this assumption must made cautiously if changes in contributing area are fast relative to knickpoint migration rates. We study the Parachute Creek basin in the Roan Plateau, Colorado, United States. Low spatial variations in climate and erosional efficiency permit us to reveal and quantify drainage-area loss that occurred in one of the subbasins where observed knickpoint locations are farther upstream than predicted by a model that takes present-day drainage areas into account. We developed a Lagrangian model of knickpoint migration which enables us to study the kinematic links between drainage area loss and knickpoint migration and that provides us with constraints on the temporal aspects of area loss. Modelled onset and amount of area loss are consistent with cliff retreat rates along the margin of the Roan Plateau inferred from the incisional history of the upper Colorado River.
Links between climate and the upper ocean structure in the Canary current upwelling system
Authors: Georg Tina , Neves Maria C. , Relvas Paulo , Malmgren Kate
Published: March 2020

Sea surface temperature differences between coastal and offshore waters and Ekman transport inferred from the wind velocity have been used to construct upwelling indices. Those indices have been widely used in climatological studies. In the present research we look to the upper layer structure of the ocean, down to 500 m depth, to infer relations between climate and the upwelling regimes. In particular, we explore the links between climate variability and the three-dimensional spatial structure of the upwelling activity along the Canary Current Upwelling System (CCUS) sector limited to 25-35° N, where upwelling is permanent, but intensified during the summer. The vertical structure of the CCUS is studied using vertical profiles of temperature, salinity, density and spiciness from the World Ocean Atlas (WOA). Monthly grids are retrieved for the past 30 years and vertical profiles exported at selected locations. The aim is to identify inter-annual and seasonal changes in the thermocline and the mix layer depth and link them to the upwelling characteristics. We then relate periods of strong upwelling with large-scale modes of climate variability, namely the North Atlantic Oscillation (NAO) and Eastern Atlantic pattern (EA). Time series of winter composites of NAO and EA are separated into positive and negative phases and their signatures quantified through composites of SST, salinity and density. The results provide the first assessment of inter-annual variability of the Canary upwelling current at both the surface and throughout depth and contributes towards understanding the connection between the vertical ocean structure and the large-scale climate modes. The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL.
Obliquity pacing of Antarctic glaciations during the Quaternary
Authors: Ohneiser Christian , Beltran Catherine , Hulbe Christina , Moy Chris , Riesselman Christina , Worthington Rachel , Condon Donna
Published: March 2020

Obliquity pacing of Antarctic glaciations during the Quaternary

The frequency of Antarctic glaciations during the Quaternary are not well understood. Benthic oxygen isotope records provide evidence for eccentricity paced global ice volume changes since c. 800 000 years and the ice core records (such as EPICA) also appear to have 100 000 year cycles over the last 800 000 years. However, the benthic oxygen isotope records are a global average – not an Antarctic record. Quaternary, sedimentary records proximal to the ice margin (such as the ANDRILL AND-1B record) are needed to understand better the recent glacial history of Antarctica. 

Here we present results from the 6.21 m long, NBP03-01A-20PCA sedimentary record which was recovered from the outer continental margin of the Ross Embayment.

Sediments comprise mud with numerous clasts and paleomagnetic analyses revealed magnetic reversals at 4.21 m, 5.74 m, and 5.85 m depth. These reversals are correlated with C1n-C1r.1r-C1r.1n-C1r.2r geomagnetic reversals which have corresponding ages of 773 ka, 990 ka, and 1070 ka. 

Time series analysis of continuous Anhysteretic Remanent Magnetisation (ARM) data, which are controlled primarily by the concentration of magnetic minerals, revealed strong obliquity paced cycles between c. 800 ka and 350 ka. The presence of obliquity cycles prompted us to carry out core scanning XRF and grain size analyses. The archive half was scanned in a itrax XRF core scanner at the Marine and Geology Repository at Oregon State University and high density grain size analyses were conducted at the University of Otago. 

We identified obliquity paced cycles in the titanium elemental data over the same period which we suggest represent variations in the terrigenous material in the core. Weaker obliquity cycles are also present in the >2mm grain size fraction which we suggest is controlled by the proximity of the ice shelf front. 

We suggest that the presence of obliquity paced cycles in our data series indicate that the Ross Ice Shelf calving line advance and retreat cycles were paced with obliquity until at least 350 ka and that the mid-Pleistocene transition occurred later in the Southern Hemisphere than in the North. 
Exploiting wind-turbine noise for seismic imaging and monitoring
Authors: Ruigrok Elmer , Jagt Lisanne , van der Vleut Britt
Published: March 2020

Wind turbines (WTs) have proven to be an increasingly cost-efficient source of sustainable energy. With further cost reductions and growth of environmental awareness, the amount and size of WTs will further expand. In the seismic literature, WTs have mainly been considered a threat rather than an opportunity. WTs act as infrasound and seismic sources, whose wavefield might overwhelm signal from earthquakes. Rather than focusing on the detrimental effects, we embrace the WT revolution and focus on the novel possibilities of the WT seismic source. We show detailed characteristics of this source using recordings over the Groningen seismic network. We further show examples of using the WT seismic noise for extracting medium parameters. Moreover, we exploit the repeatable nature of the source for subsurface monitoring.
Does agricultural practices impact the quantity and the forms of organic carbon stored in cultivated soils of the Senegal groundnut basin? A Rock-Eval approach
Authors: Malou Oscar Pascal , Sebag David , Moulin Patricia , Chevallier Tiphaine , Badiane Ndour Yacine , Thiam Abou , Chapuis-Lardy Lydie
Published: March 2020

Soil organic carbon (SOC) is a key element in the functioning of agrosystems. It ensures soil quality and productivity of cultivated systems in the Sahelian region. This study uses Rock-Eval pyrolysis to examine how cultural practices impact SOC quantity and quality of cultivated sandy soils in the Senegal groundnut basin. Such thermal analysis method provides cost-effective information on SOC thermal stability that has been shown to be qualitatively related to SOC biogeochemical stability. Soils were sampled within 2 villages agricultural plots representative of local agricultural systems and for local preserved areas. Total SOC concentrations ranged from 1.8 to 18.5 g.kg-1 soil (mean ± standard deviation: 5.6 ± 0.4 g.kg-1 soil) in the surface layer (0-10 cm) and from 1.5 to 11.3 g.kg-1 soil (mean ± standard deviation: 3.3 ± 0.2 g.kg-1 soil) in 10-30 cm deep layer. SOC of cultivated soils significantly (p-value < 0.0001) decreased according to treatments in the following order: +organic wastes > +manure > +millet residues > no input. Our results show that the quantity and the quality of SOC are linked to each other and both depend on land-use and agricultural practices, especially the nature of organic inputs. This correlation is very strong in the tree plantation (R² = 0.98) and in the protected shrubby savanna (R² = 0.97). It remains important for cultivated soils receiving organic wastes (R² = 0.82), manure (R² > 0.75), or millet residues (R2 = 0.91) but it’s no more significant in no-input situations. The Rock-Eval based indexes were depicted in a I/R diagram that illustrate the level of SOC stabilization and plotted against comparable results from literature. The Senegalese sandy soils have thermal signatures showing an inversion of the I and the R indexes compared to data from the literature and highlighting SOC stabilization as a function of soil depth. Indeed, the studied soils were characterized by a more abundant refractory pool (A5 which ranged from 7.7 to 21.3 % in 0-10 cm layer and from 12.5 to 24.3 % in 10-30 cm, respectively) compared to other tropical soils. The SOC in these sandy soils while positively affected by organic inputs is dominated by labile forms that mineralize quickly which is excellent for the needs of productivity of these agrosystems but not for mitigation of climate change.

Keywords: Soil organic carbon; Organic inputs; Thermal analysis; Agrosystems; West Africa
A novel shoreface translation model for predicting future coastal change
Authors: McCarroll Jak , Masselink Gerd , Valiente Nieves , Wiggins Mark , Kirby Josie-Alice , Scott Tim , Davidson Mark
Published: March 2020

Predicting changes to global shorelines presents a challenge that will become increasingly urgent over coming years as sea-level rise (SLR) accelerates. Current shoreline prediction models typically estimate the impact of SLR using variations of the ‘Bruun Rule’, which fails to account for many relevant processes, potentially producing erroneous results. To address this shortcoming, we introduce a simple rule-based model that predicts change across a wide variety of sand, gravel, rock and engineered (anthropogenic) coastal environments, at the scale of years to centuries, accounting for trend rates of change as well as natural short-term variability. Applying recent findings of laboratory and field-based research, the model translates 2D cross-sections of the shoreface, then integrates these changes across multiple alongshore profiles (into pseudo-3D). Uncertainty is accounted for using a probability distribution for inputs (e.g., rate of SLR, depth of closure, depth to bedrock). The model accounts for: (1) dune erosion and slumping [for large dunes]; (2) barrier rollback and overwash [for low barriers]; (3) aeolian dune accretion; (4) non-erodible bedrock layers, including those below ‘perched’ dunes; (5) seawall and revetment backed profiles; (6) onshore transport from the lower shoreface; (7) cross-shore variability due to storm erosion; (8) alongshore variability due to beach rotation; (9) alongshore re-distribution of dune erosion across the shoreface of a closed embayment; and (10) other sources and sinks (e.g., estuary infill, longshore flux, headland bypassing, biogenic production). We apply the model to two extensively monitored macrotidal embayments in the UK: Perranporth (sandy, dissipative, cross-shore dominant transport) and Start Bay (gravel, reflective, bi-directional alongshore dominant). For the dissipative sandy site, the primary modes of coastal change are predicted to be: (1) sea-level rise profile translation; and (2) extreme event cross-shore fluctuations. By contrast, for the reflective gravel site, the primary modes are: (1) short-term fluctuations in alongshore rotation; and (2) multi-decadal trends in longshore flux. For the steep gravel barrier, sea-level rise profile translation is important but secondary. Relative to the new model, the Bruun Rule underpredicts shoreline recession in front of cliffs and seawalls, and overpredicts where large erodible dunes are present. This new shoreface translation model is easily transferable to many coastal environments and will provide a useful tool for coastal practitioners to make rapid assessments of future coastal change.
Simulation of electricity production in a remote island for optimal management of a hybrid renewable energy system
Authors: Karkanis Konstantinos , Vatsikouridis Ioannis , Iliopoulou Theano , Dimitriadis Panayiotis , Koutsogiannis Demetris , Mamassis Nikolaos
Published: March 2020

We simulate the electrical energy production in the remote island of Astypalaia, Greece. Solar, wind, hydropower, biomass and marine energy are used for the energy mix. The hypothetical energy system has also the ability to store energy through a pumped-storage unit. We use available data at various time scales. The aim of this work is to optimize the energy management of the hypothetical system studied.

Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

 
INFILTRON package for assessing infiltration & filtration functions of urban soils
Authors: Lassabatere Laurent , De Giacomoni Anne-Cécile , Angulo-Jaramillo Rafael , Lipeme Kouyi Gislain , Martini Matteo , Louis Cédric , Peyneau Pierre-Emmanuel , Rodriguez-Nava Veronica , Cournoyer Benoit , Aigle Axel , Bergeron Emmanuelle , Bonneau Jérémie , Bouarafa Sofia , Colin Yannick , Concialdi Paola , Di Prima Simone , Galia Wessam , Lai Thanh Huong , Marais Arthur , Laurence Marjolet ,   following co-authors
Published: March 2020

The extension of urban and peri-urban areas and the related artificialization of soils drastically impacts the water cycle as well as biogeochemical cycles. In particular, the sealing of soils with impervious surfaces such as roads increases runoff and decreases concomitant infiltration. At the catchment scale, more significant amounts of stormwater must be collected and managed to prevent from flooding urban areas and mitigate discharge to the environment. Sustainable Urban Drainage Systems (SUDS) were developed to alleviate these problems. These systems allow the restoration of one of the main functions of urban and peri-urban soils, i.e., infiltrating stormwater. They simultaneously reduce the risk of flooding and increase groundwater recharge. Another essential service must be ensured and optimized: the removal of pollutants from infiltrating water by the soil, to avoid the degradation of the quality of the groundwater.

The INFILTRON project aims to design a methodology for the assessment of infiltration and filtration of pollutants by SUDS. The project is a collaboration of many partners, with expertise in soil physics, urban hydrology, nanoparticle engineering, and modeling, to engineer a specific device for the simultaneous monitoring of water infiltration and pollutant filtration. This infiltration device both infiltrates water and injects nanoparticles (NPs) into the soil. It was sized to account for preferential flow, which is known to have a significant impact on infiltration and pollutant transfer. The engineered NPs were designed to be detectable in the ground using ground-penetrating radar (GPR) and to mimic the transfer of nano-pollutants (emerging pollutants, bacteria, etc.) commonly found in real stormwater. An infiltration-filtration model was developed to interpret the experimental data and to quantify two indicators for the assessment of water infiltration and pollutant filtration. INFILTRON will provide a very interesting toolbox for practitioners and stakeholders for the evaluation of the infiltration and filtration functions of not only SUDS within the framework of stormwater management, but also anthropized soils within the management of urban and peri-urban areas.
The Middle Pleistocene Transition: estimation of the interval stability by data-driven model
Authors: Loskutov Evgeny , Vdovin Valery , Gavrilov Andrey , Mukhin Dmitry , Feigin Alexander
Published: March 2020

We investigate the Middle Pleistocene Transition (MPT) - a rapid change in the periodicity of the Pleistocene glacial cycles from 41 kyr to about 100 kyr, which occurred about a million years ago - using the data-driven model [1]. Here we estimate stability of the model using a novel concept of interval stability [2-4], referring to the behavior of the perturbed model during a finite time interval. In a few words we define the class of 'safe' perturbations after which the system (our data-driven model) returns back to the initial dynamical regime and 'unsafe' perturbation of minimal amplitude needed to disrupt the system.

We demonstrate that the MPT is likely associated with decreasing of the climate system's interval stability to rapid disturbances (millennial and shorter). This confirms the statement made in the paper [1] that the main factor in the onset of the long-period glacial cycles is strongly nonlinear oscillations induced by the short-scale variability.

D. Mukhin, A. Gavrilov, E. Loskutov, J. Kurths, A. Feigin. Bayesian Data Analysis for Revealing Causes of the Middle Pleistocene Transition. Scientific Reports, 9 7328 (2019).

P. Menck, J. Heitzig, N. Marwan, J. Kurths. How basin stability complements the linear-stability paradigm. Nature Phys, 9 89–92 (2013).

V. Klinshov, V. Nekorkin, J. Kurths. Stability threshold approach for complex dynamical systems. New Journal Physics, 18 013004 (2016).

V. Klinshov, S. Kirillov, J. Kurths, V. Nekorkin. Interval stability for complex systems. New Journal Physics, 18 013004 (2018).
A new framework for understanding and quantifying uncertainties in the remaining carbon budget
Authors: Matthews H. Damon , Tokarska Katarzyna , Rogelj Joeri , Forster Piers , Haustein Karsten , Smith Christopher , MacDougall Andrew , Mengis Nadine , Sippel Sebastian , Knutti Reto
Published: March 2020

The remaining carbon budget quantifies the allowable future CO2 emissions to keep global mean warming below a desiredlevel. Carbon budget estimates are subject to uncertainty in the Transient Climate Response to Cumulative CO2 Emissions (TCRE), which measures the warming resulting from a given total amount of CO2 emitted. Moreover, other sources of uncertainty linked to non-CO2 emissions have been shown to also strongly affect estimates of the remaining carbon budget. Here we present a new framework that estimates the TCRE using geophysical constraints derived from observations, and integrates the effect of geophysical and socioeconomic pathway uncertainties on the distribution of the remaining carbon budget. We estimate a median TCRE of 0.40 °C and likely range of 0.3 to 0.5 °C (17-83%) per 1000 GtCO2 emitted. Our 1.5 °C remaining carbon budget has a median value of 710 GtCO2 from 2020 onwards, with a range of 470 to 960 GtCO2, (for a 67% to 33% chance of not exceeding the target). Uncertainty in the amount of current warming from non-CO2 forcing is the dominant geophysical contributor to the spread in both the TCRE and remaining carbon budget estimates. The remaining carbon budget distribution is also strongly affected by current and future mitigation decisions, where the range of non-CO2forcing across scenarios has the potential to increase or decrease the median 1.5 °C remaining carbon budget by 740 GtCO2.
A recent slowdown in the decline of CFC-11 concentrations in the upper troposphere
Authors: Sheese Patrick , Walker Kaley , Boone Chris , Saunders Laura , Dhomse Sandip , Feng Wuhu , Chipperfield Martyn
Published: March 2020

Since 2004, the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) instrument has been measuring concentrations of chlorofluorocarbons (CFCs) in the stratosphere and upper troposphere and is currently the only satellite instrument that measures vertically resolved profiles of CFC‑11. Since CFCs are major ozone depleting substances, monitoring their atmospheric abundances is critical for understanding ozone layer recovery. Recent studies based solely on surface-level measurements have shown strong evidence for new CFC‑11 production, leading to an increase in CFC‑11 emissions over the past decade. In this study, the TOMCAT/SLIMCAT 3-D chemical transport model is used in order to bridge the altitude/geolocation gap between ACE-FTS measurements in the UTLS and surface level measurements. Trends in two different time periods over the ACE-FTS mission, 2004-2012 and 2013-2018, are examined to determine if the recent change in surface level CFC-11 trends is influencing UTLS concentrations. The ACE-FTS measurements show that, below ~10 km, the rate of decrease of global CFC-11 concentrations was slower during 2013-2018 (-1.2 pptv/year) than during 2004-2012 (‑2.0 pptv/year). Similar trends are observed in the model data for the same spatial/temporal regions.
Cyclones density and characteristics in different reanalyses dataset over South America
Authors: Machado Crespo Natália , Porfírio da Rocha Rosmeri , Marcos de Jesus Eduardo
Published: March 2020

Cyclones developing over and at the eastern coast of South America impact extreme events over the region. Understanding the present climate is crucial to assess future extremes tendencies, which are important for engineering constructions over the southeast Brazil basin. To evaluate these systems in climate change scenarios it is important to study their preferred region of formation and trajectories in the present climate. Therefore, in this study we tracked cyclones in a period from 1979 to 2018 (present climate) using different reanalyses dataset (CFSR, ERA-Interim and ERA5), pointing out the main cyclogenetic regions affecting South America and discussing the main differences between the different dataset. As a preliminary result, the cyclone tracking shows a higher number of systems in CFSR than in ERA-Interim, which would be explained by the finer resolution of CFSR.  Annually, this difference is about 6%, and seasonally, the difference is smaller in summer (3.5%) and similar (~7%) for the other seasons. The reanalyses identify basically the same four cyclogenetic regions, however, there are differences in the density center position. Other features as lifetime, intensity, traveled distance, and wind extremes associated with the cyclones will be also discussed.
Processing of organic matter input influences aggregate formation in artificial soils with different texture
Authors: Bucka Franziska , Tung Shu-Yin , Kögel-Knabner Ingrid
Published: March 2020

Aggregate formation and stabilization depends on the interaction of minerals and soil organic matter (SOM). So far, little is known about the interplay of individual organic matter qualities and soil texture within this process. We developed an experimental set-up to study early soil development and aggregate formation within a controlled lab environment. We designed artificial soil microcosms with different texture, mimicking natural soils, and added organic carbon (OC) derived from particulate organic matter (POM, milled hay litter), dissolved organic matter (DOM, solution derived from hay), and bacterial necromass (Bacillus subtilis). We performed a short-term incubation for 30 days under constant water tension and investigated microbial activity, soil structure development and OC allocation compared to a control that did not receive additional OC input. 

OC input led to the formation of mostly large, water-stable macroaggregates (3000-630 µm) and some small microaggregates (<63 µm) in all microcosms as effect of microbial processing of the added OM. The addition and microbial decay of litter pieces led to physical occlusion of the particles into mainly large (3000-630 µm), OC-rich macroaggregates independent of the texture. The addition of DOM solution also induced the formation of large macroaggregates besides small microaggregates, although the OC input was much lower. Here, the aggregate formation was impaired by higher sand content in the mixtures. The addition of bacterial necromass led to the highest microbial activity, but relatively low aggregate formation, which might be a result of less physically active organic matter nuclei.

The results show that our experimental design allows to specifically investigate selected process complexes of soil structure formation defined by the addition of OM and soil texture.
Nonlinear Climate Dynamics: from Deterministic Behavior to Stochastic Excitability and Chaos
Authors: Crucifix Michel , Alexandrov Dmitri , Bashkirtseva irina , Ryashko Lev
Published: March 2020

Glacial-interglacial cycles are global climatic changes which have characterised the last 3 million years. The eight latest
glacial-interglacial cycles represent changes in sea level over 100 m, and their average duration was around 100 000 years. There is a
long tradition of modelling glacial-interglacial cycles with low-order dynamical systems. In one view, the cyclic phenomenon is caused by
non-linear interactions between components of the climate system: The dynamical system model which represents Earth dynamics has a limit cycle. In an another view, the variations in ice volume and ice sheet extent are caused by changes in Earth's orbit, possibly amplified by feedbacks.
This response and internal feedbacks need to be non-linear to explain the asymmetric character of glacial-interglacial cycles and their duration. A third view sees glacial-interglacial cycles as a limit cycle synchronised on the orbital forcing.

The purpose of the present contribution is to pay specific attention to the effects of stochastic forcing. Indeed, the trajectories
obtained in presence of noise are not necessarily noised-up versions of the deterministic trajectories. They may follow pathways which
have no analogue in the deterministic version of the model.  Our purpose is to
demonstrate the mechanisms by which stochastic excitation may generate such large-scale oscillations and induce intermittency. To this end, we
consider a series of models previously introduced in the literature, starting by autonomous models with two variables, and then three
variables. The properties of stochastic trajectories are understood by reference to the bifurcation diagram, the vector field, and a
method called stochastic sensitivity analysis.  We then introduce models accounting for the orbital forcing, and distinguish forced and
synchronised ice-age scenarios, and show again how noise may generate trajectories which have no immediate analogue in the determinstic model. 
Advances in using radar to observe vegetation water dynamics
Authors: Steele-Dunne Susan , Vermunt Paul , Khabbazan Saeed , Petchiappan Ashwini , Judge Jasmeet , Vreugdenhil Mariette , Hahn Sebastian , Wagner Wolfgang
Published: March 2020

Vegetation acts as an interface between the earth's surface and the atmosphere, modulating exchanges of water, carbon and energy and responding to environmental stressors. Improved understanding of water transport through the soil-vegetation-atmosphere continuum is essential to understand the role of vegetation at a catchment and a global scale. The sensitivity of radar remote sensing observations to the water content of soil and vegetation makes it well-suited to monitoring spatio-temporal dynamics of processes in the soil-vegetation-atmosphere continuum.

Here, we present the latest results from studies using ground-based and spaceborne radar demonstrating the potential of radar to monitor vegetation water dynamics at scales from meters to tens of kilometers. Field data will be used to demonstrate the sensitivity of radar observations to surface and internal vegetation water content. These results illustrate the potential value of radar for monitoring rapid plant water dynamics, and the impact of water-limited conditions on land-atmosphere exchanges. Satellite data will be used to illustrate the degree to which current spaceborne radar systems can already be used to monitor these processes and the limitations posed by revisit time and resolution.

We will conclude with an outline of future opportunities and challenges. The next generation of spaceborne radar sensors offers  unprecedented monitoring capability. To avail of this opportunity, we need improved alignment between the treatment of vegetation in hydrological and radiative transfer models. This is essential to ensure meaningful relationships between new radar data products and hydrological states of interest, and to facilitate the assimilation of radar observations to constrain vegetation processes in hydrological models.
The convexity of carbonate hillslopes: the influence of climate, chemical weathering and dust flux
Authors: Ben-Asher Matan , Haviv Itai , Crouvi Onn , Roering Josh J , Matmon Ari
Published: March 2020

Convex soil-covered hillslopes are ubiquitous in various tectonic and climatic settings and are often modeled based on a mass balance relating hillslope convexity to regolith transport and soil production. In order to account for chemical weathering of carbonate rocks and dust input to the regolith, two fluxes that are commonly neglected in settings with silicate-dominated bedrock,  we modify this mass balance.

We studied 7 study sites in carbonate rocks across an Eastern Mediterranean gradient in the mean annual rainfall (250 to 900 mm yr-1) and dust flux (150 to 40 g m-2 yr-1). Combining cosmogenic 36Cl-derived hilltops denudation rates with an estimate of the regolith chemical depletion and dust fraction based on immobile elements, we predict the hillslope curvature and compare our predictions with observations based on high-resolution airborne LiDAR.

Our results demonstrate that soft carbonates (chalk) experience faster denudation rates relative to resistant dolo-limestone. However, the harder carbonates are more prone to chemical weathering, which systematically constitutes around half of their total denudation.  Soil production rates exhibit a humped dependency on soil thickness, with an apparent maximum at a depth of 8-16 cm.

The observed hillslope curvature vary as function of rainfall and dust flux with a minimum at sub-humid sites with intermediate rainfall of  500-600 mm/yr. The predicted curvature based on our new mass balance is not far from the observed curvature, illustrating the prominent effects of dust flux and chemical weathering on hillslope morphology.  Our model also implies that drier sites in the south probably experienced a more complex history of regolith production due dust flux fluctuations.

By incorporating dust flux and chemical weathering to the classic hillslope evolution model we identify a complex relation between hillslope curvature, soil production, and climate. These two fluxes are not unique to carbonate bedrock and should be incorporated in hillslope evolution models.
Tropical air intrusions over the eastern Mediterranean and Mesopotamia: An atmospheric river case study and role of the East Asian trough
Authors: Sen Omer L. , Bozkurt Deniz , Ezber Yasemin
Published: March 2020

The high-elevation eastern Anatolian plateau, located in eastern Mediterranean basin, is cold and snowy in winter, and functions as a water tower in providing water to Mesopotamia through Euphrates and Tigris rivers. These rivers are snow-fed, as much of their discharges occurs in spring when the seasonal warming melts the snowpack. The anomalous warming over the eastern Anatolia in early March 2004 resulted in unprecedented snowmelt runoff in the Euphrates and Tigris basin together with the accompanying rainfall. This study explores an atmospheric river (AR) leading to the extreme hydrometeorological events in the headwaters regions of the Euphrates and Tigris basins in early March 2004, and its possible linkage to the strength of the East Asian trough (EAT). In the analyses, we used reanalysis data, gridded products of surface temperature and snow cover, river discharge data and satellite imagery. We employed an intensity index for the EAT and a trough displacement index for the Mediterranean trough (MedT) to explore the relationship between the strength of the EAT and the displacement of the MedT at pentad resolution. We show that there is a strong relationship between the strength of the EAT and the zonal displacements of the Mediterranean upper layer trough on the 13th pentad of the year, which corresponds to early days of March. In 2004, which appears to be an extreme year for this phenomenon, the MedT is positioned and deepened in the central Mediterranean (about10−15◦E), and extended towards central Africa during the early days of March. This synoptic pattern provided favorable conditions for the development of AR with a southwest-northeast orientation, carrying warm tropical African air towards the eastern Mediterranean and Anatolian highlands resulting in rapid melting of the snowpack as well as severe precipitation, and thus, flooding events, in the eastern Anatolia. A key finding in our analysis is that the strengthening of the EAT was instrumental to the increased amplitude of the ridge-trough system over the Euro-Mediterranean region in the early days of 2004 late winter. A further analysis is ongoing to provide a basis to analyze past individual AR events over the region, especially those associated with extreme precipitation events and snowmelt.
Agroforestry systems towards rehabilitation of West Africa marginal areas through an integrated green biotechnology approach
Authors: Monteiro Filipa , Abreu Maria Manuela , Correia Augusto Manuel , Vidigal Patrícia
Published: March 2020

To achieve the goals set by the 2030 agenda for Sustainable Development, it is imperative to create sustainable solutions to recovery marginal lands (e.g. landfills or abandoned mining areas) and create conditions for agriculture activities, but most importantly is a concern that deserves political priority. Landfills, poses health and environmental concerns due to the presence of potentially hazardous elements (PHE), among other contaminants that cannot be degraded leading to soil and water contamination, with increasing concern in the African continent. In 2018, a Report to the United Nations Framework Convention on Climate Change by the Republic of Guinea-Bissau reported that waste management is one of the major problems that the country faces. Thus, it is essential to create solutions, beyond contaminated wastes management, such as the rehabilitation of such areas. A potential rehabilitation strategy is the combination of phytostabilization with Technosols. Phytostabilization uses plants to decrease mobility or immobilize PHE in the rhizosphere. These plants should also have low PHE translocation factors from the soil/roots to the shoots. For the Technosols construction it can be used a mixture of different kinds of wastes from different origins (e.g. landfill, construction) to obtain a anthropic soil whose properties (e.g. fertility, water-holding capacity, structure) decrease PHE availability and promote plant growth, minimizing the risk to both human health and the environment. A possible strategy for the rehabilitation of contaminated areas, could be the establishment of an agroforestry system - by intercropping legumes, towards phytostabilization, using cashew as a case study due to its importance as a revenue commodity in West Africa countries (e.g.Guinea-Bissau). However, it is of utmost importance to identify the nature/quantity of PHE and wastes as well as climatic conditions for each contaminated/degraded site, before creating an agroforestry system in those areas, thus ensuring the sustainability of the phyto-geo-technology towards food security. Furthermore, potential alternative revenues obtained from the agroforestry system arise. As such, we present a potential rehabilitation agroforestry system that can in the future be useful for African countries attain the goals set for 2030 and beyond.
Seismic anisotropy and mantle deformation in NW Iran through splitting measurements of SKS and direct S phases
Authors: Arvin Shiva , Sobouti Farhad , Priestley Keith , Ghods Abdolreza , Motaghi Seyed Khalil , Tilmann Frederik , Eken Tuna
Published: March 2020

The present tectonics of Iran has resulted from the continental convergence of the Arabian and Eurasian plates. Our study area, in NW Iran comprises a part of this collision zone and consists of an assemblage of distinct lithospheric blocks including the central Iranian Plateau, the South Caspian Basin, and the Talesh western Alborz Mountains. A proper knowledge of mantle flow field is required to bettwer constrain mantle kinematics in relation to the dynamics of continental deformation in NW Iran. To achieve this aim, we examined splitting of teleseismic shear waves (e.g. SKS and S) arriving with steep arrival angles beneath the receiver, which provide excellent lateral resolution in the upper mantle. We used data from 68 temporary broadband stations with varying operation periods (4 to 31 months) along 3 linear profiles. We perfomed splitting analyses on SK(K)S and direct S waves. Resultant splitting parameters obtained from both shear phases exhibit broad similarities. Relatively large time delays observed for direct S-waves, however, are anticipated since these waves travel longer than SKS along a non-vertical propagation path in an anisotropic layer. Overall, the fast polarization directions (FPDs) in the Alborz, Talesh, Tarom Mountain and in NW Iran indicate a strong consistency with NE-SW anisotropic orientations. Besides, we observe a good accordance between S and SKS results. A comparison of splitting parameters with the absolute plate motion (APM) vector and structural trends in Iran and eastern Turkey suggests asthenospheric flow field as the dominant source for observed seismic anisotropy. The lithospheric layer beneath these regions is relatively thin (compared to the adjacent Zagros region), explaining why it appears to only make a partial contribution to the observed anisotropy. The stations located in central Iran just southwest of the Alborz yield angular deviations from the general NE-SW trend as this may be explained by changing style of deformation across the different tectonic blocks. These stations indicate significant misfit between SK(K)S and direct S-waves that could be caused by local heterogeneities developed due to a diffuse boundary from the flow organization in the upper mantle of central Iran. Another possibility for large differences between two types of waves might be reflect the anisotropic structure of a remnant slab segment or a foundered lithospheric root beneath central Iran with a volume small enough to be detected by SKS phases, but not by the direct S waves.
May long-term historical hydrological data be misleading for flood frequency analysis in current conditions of climate change?
Authors: Fedorova Alexandra , Nesterova Nataliia , Makarieva Olga , Shikhov Andrey
Published: March 2020

In June 2019, the extreme flash flood was formed on the rivers of the Irkutsk region originating from the East Sayan mountains. This flood became the most hazardous one in the region in 80 years history of observations.

The greatest rise in water level was recorded at the Iya River in the town of Tulun (more than 9 m in three days). The recorded water level was more than 5 m above the dangerous mark of 850 cm and more than 2.5 m above the historical maximum water level which was observed in 1984.

The flood led to the catastrophic inundation of the town of Tulun, 25 people died and 8 went missing. According to preliminary assessment, economic damage from the flood in 2019 amounted up to half a billion Euro.

Among the reasons for the extreme flood in June 2019 that are discussed are heavy rains as a result of climate change, melting of snow and glaciers in the mountains of the East Sayan, deforestation of river basins due to clearings and fires, etc.

The aim of the study was to analyze the factors that led to the formation of a catastrophic flood in June 2019, as well as estimate the maximum discharge of at the Iya River. For calculations, the deterministic distributed hydrological model Hydrograph was applied. We used the observed data of meteorological stations and the forecast values â€‹â€‹of the global weather forecast model ICON. The estimated discharge has exceeded previously observed one by about 50%.

The results of the study have shown that recent flood damage was caused mainly by unprepared infrastructure. The safety dam which was built in the town of Tulun just ten years ago was 2 meters lower than maximum observed water level in 2019. This case and many other cases in Russia suggest that the flood frequency analysis of even long-term historical data may mislead design engineers to significantly underestimate the probability and magnitude of flash floods. There are the evidences of observed precipitation regime transformations which directly contribute to the formation of dangerous hydrological phenomena. The details of the study for the Irkutsk region will be presented.
Retention of sediments and nutrients in buffer zones with different riparian vegetation
Authors: Krzeminska Dominika , Buseth Blankenberg Anne-Grette , Nemes Attila , Boe Frederik , Skarbovik Eva
Published: March 2020

In Norway, eutrophication is a major problem for freshwater quality, mainly due to excess phosphorus (P) inputs from agricultural areas. Hence, vegetated buffer zones along water bodies have been used for decades to reduce soil and phosphorus losses from agricultural land to waterbodies. In Norway, buffer zones with grass production are the most popular since these are eligible for subsidies.

The efficiency of grass-covered buffer zones has previously been studied in areas with relatively steep slopes and high risk of surface runoff and erosion. However, more field-based knowledge is needed on the retention efficiency of grassed buffer zones in areas with gentle slopes. In addition, other functions of these zones such as reduced bank erosion, biodiversity, and food production, need to be explored. The latter is important since only 3% of Norway’s area is under cultivation.

Herein, we present the results of three years of monitoring and rainfall simulation experiments carried out along the Hobølelva River in SE Norway. Our aim was to investigate different functions of buffer zones, including the retention of nutrients and particles and the protection against bank erosion in buffer zones with different vegetation cover (grass, shrubs and trees). Results to be presented include comparisons of 1) retention of nutrients and soil practices as observed during a series of rainfall simulation experiments in the field, 2) soil and hydrogeology characteristics (texture, porosity, hydraulic conductivity, infiltration capacity etc.), and 3) stream bank hydrogeological monitoring and stability estimation under different vegetation.