bluuebunny/crossref_metadata_2025 huggingface dataset:
The Global Gridded Crop Model Intercomparison – an AgMIP activity
Authors: Müller Christoph , Jägermeyr Jonas , GGCMI team the
Published: March 2021

The Global Gridded Crop Model Intercomparison was founded in 2012 as a joint activity of the Agricultural Model Intercomparison and Improvement Project (AgMIP) and the InterSectoral Model Intercomparison Project (ISIMIP). Over these 10 years, GGCMI has attracted contributions from many international crop modeling groups and has generated large global agricultural data sets in different model simulation phases. Input data comprise gridded management data for agricultural systems that can be used in combination with climate data that are provided by ISIMIP. Annual output data include crop yields and other variables of plants and soil status for irrigated and purely rainfed production systems for different field crops at 0.5 degree spatial resolution, covering the whole land surface, where crop production is feasible. All data are made publicly available. While Phase 1 of GGCMI was focused on the historical period[1,2], aiming at model evaluation[3], Phase 2 generated an unprecedented large data set of systematic disturbances along the CO2 (C), Temperature (T), Water (W) and Nitrogen (N) dimension[4]. A major outcome of Phase 2 is a very large set of emulators[5] that allows for lightweight, flexible and comprehensive crop yield projections and analyses. With analyses of Phase 2 still forming, Phase 3 was started in collaboration with ISIMIP’s Phase 3, providing new future projections for a range of CMIP6 climate change projections and different management scenarios. Crop models do not only provide outputs on crop yields but also on various processes, such as evapotranspiration, leaf area index, phenology and soil dynamics that allow for broader analyses. GGCMI is a collaborative effort and always open to new contributors. Given the amount and complexity of in- and output data, we welcome proposals for new studies and data analyses. In this presentation we’re providing an overview of the GGCMI activities and exemplify possible entry points for collaboration.

[1] http://dx.doi.org/10.5194/gmd-8-261-2015

[2] http://dx.doi.org/10.1038/s41597-019-0023-8

[3] http://dx.doi.org/10.5194/gmd-10-1403-2017

[4] http://dx.doi.org/10.5194/gmd-13-2315-2020

[5] http://dx.doi.org/10.5194/gmd-13-3995-2020
Observations of iodine monoxide over three summers at the Indian Antarctic bases, Bharati and Maitri
Authors: Mahajan Anoop , Biswas Mriganka , Beirle Steffen , Wagner Thomas , Schönhardt Anja , Benavent Nuria , Saiz-Lopez Alfonso
Published: March 2021

 Iodine plays a vital role in oxidation chemistry over Antarctica, with past observations showing highly elevated levels of iodine oxide (IO) leading to severe depletion of boundary layer ozone in West Antarctica. However, observations across Antarctica are still rare, and have hitherto been mostly focused on the West Antarctic, which needs to be addressed in order for comprehensive model validation. Here, we present multi axis differential absorption spectroscopy (MAX-DOAS) based observations of IO over three summers (2015-2017) at the Indian Antarctic bases, Bharati and Maitri. IO was observed during all the campaigns, with mixing ratios below 2 pptv for the three summers, which are lower than the peak levels observed in West Antarctica. This suggests that sources in West Antarctica are different or stronger than sources of iodine compounds in East Antarctica. Vertical profiles estimated using a profile retrieval algorithm showed decreasing gradients, with a peak in the lower boundary layer. The ground-based instrument retrieved vertical column densities (VCDs) were approximately a factor of three-five higher than the VCDs reported using satellite-based instruments, which is most likely related to the sensitivities of the measurement techniques. Airmass back-trajectory analysis failed to highlight a source region, with most of the airmasses coming from coastal or continental regions. This study adds to the sparse observational database of iodine compounds in Antarctica and highlights the variation in iodine chemistry in different regions in Antarctica. It also shines light on the needs of more long-term datasets in different regions to validate models estimating the impacts of iodine chemistry across Antarctica.
Cancellation of the precessional cycle in δ18O records during the Early Pleistocene
Authors: Nisancioglu Kerim , Morée Anne , Sun Tianyi , Straume Eivind , Gebbie Geoffrey
Published: March 2021

The dominant pacing of glacial‐interglacial cycles in deep‐ocean δ18O records changed substantially during the Mid‐Pleistocene Transition. The precessional cycle (∼23 ky) is absent during the Early Pleistocene, which we show can be explained by cancellation of the hemispherically anti‐phased precessional cycle in the Early Pleistocene interior ocean. Such cancellation develops due to mixing of North Atlantic and Southern Ocean δ18O signals at depth, and shows characteristic spatial patterns. We explore the cancellation potential for different North Atlantic and Southern Ocean deep‐water source δ18O values using a tracer transport ocean model. Cancellation of precession occurs for all signal strengths and is widespread for a signal strength typical for the Early Pleistocene. Early Pleistocene precessional power is therefore likely incompletely archived in deep‐sea δ18O records, concealing the true periodicity of the glacial cycles in the two hemispheres.
Drop infiltration dynamics of anionic, cationic, and nonionic surfactants into hydrophobic soils: effect of the particle size distribution 
Authors: Nguyen Thuc , Arye Gilboa
Published: March 2021

Surfactants have been long used to aid water infiltration into hydrophobic soils since it can reduce the surface tension of water and consequently, the contact angle (CA) form at the solid-liquid-air interface. The degree of soil hydrophobicity is commonly engaged with direct or indirect measurements of the apparent initial advancing CA which is not necessarily correlated with infiltration characteristics of aqueous surfactant solutions. The main objective of this study was to quantify the dynamics of surfactant drop penetration into hydrophobic soils. Three surfactants were examined: anionic (SDS), cationic (CTAB), and nonionic (TX100) at aqueous concentrations of 0.4, 0.8, 1, and 2 C/CMC (where C is the bulk concentration and CMC is critical micelle concentration). Sand with the particle size distribution of 100-210, 425-500, and 600-700 μm was hydrophobized using Leonardite (IHSS). Each run was initiated by placing a 30 μL droplet on the soil surface that was packed into quartz cuvette (2.5×2.5×4 cm). The droplet infiltration dynamics were monitored by an optical goniometer (OCA 20, DataPhysics, Germany), specifically, the drop height, drop base diameter, and CA as a function of time. Notable differences between droplet infiltration characteristics of the three surfactants could be observed. For a given particle fraction, the TX100 and SDS, at concentrations above and below the CMC, the CA and drop height decreased while the drop base diameter increased, suggesting that spreading took place during infiltration. For the CTAB, a significant lag-phase could be observed for all quantities, ranging from 100 to 1000. Following this phase, the drop height and CA showed a relatively gradual decrease while the base diameter exhibited minor changes, suggesting minor changes in solution spreading on the soil surface. Additional observation and interpretation on infiltration characteristics of aqueous surfactants solution will be presented and their implications for enhanced infiltration rate in hydrophobic soils will be discussed.    
A combined fault- and catalog-based hazard assessment for Central Zagros, Iran
Authors: Dolatabadi Nima , Tavakolizadeh Nasrin , Mohammadigheymasi Hamzeh , Valentini Alessandro
Published: March 2021

The Zagros mountains is a tectonically active Arabian-Eurasian plate convergence zone. The convergence direction changes along the strike of the belt, results in oblique faulting in the North-Western Zagros (NWZ) and the prevalence of pure reverse faulting in the South-Eastern Zagros (SEZ). The two regions undergo different convergence rates, (4 ± 2 mm yr −1) in NWZ and (9 ± 2 mm yr −1) in SEZ. These differences is partially accommodated by right-lateral strike-slip faulting throughout the Central Zagros (CZ), resulting in catastrophic earthquakes like 1972 Mw = 6.7 Qir and 1934 Mw = 6.3 Kazerun. This study presents the Probabilistic Seismic Hazard Assessment (PSHA) for the CZ region by integrating fault sources and seismological data. The seismological catalog data consists of 6504 events (2.5 < Mw < 6.7) during 1925-2020 and was compiled from the International Seismological Center (ISC) and the Iranian Seismological Center (IRSC). The faults with the history of Mw > 5.5 or geometrical potential of producing such an event were modeled. A Truncated Gutenberg–Richter (TGR) Magnitude-Frequency Distribution (MFD) for a range of magnitudes (5.5 < Mw < Mmax ) is evaluated by processing the geometrical parameters and slip rate of each fault source using the FiSH code. The Mmax is computed for each source by combining various Mmax estimates based on the faults geometry and observed Mmax if it is available. The catalog data was modeled as a grid source. A unique set of seismic activity rate parameters (for Mw > 4) in each grid is obtained by applying a modified smoothed seismicity approach. More precisely, a penalized likelihood-based methodwas utilized for the spatial estimation of the b-values, and a weighted smoothing method was implemented to calculate the spatial distribution of the a-values. The catalog events with Mw > 5.5 were excluded to avoid duplicated hazard estimation (modified earthquake catalog). Compiling the source models, the hazard computations were performed using the OpenQuake Engine. The Peak Ground Acceleration (PGA) is computed for the Probability Of Exceedance (POE) of 10% over 50 years for distributed seismicity obtained by the full catalog, and an aggregated model of active faults and distributed seismicity with the modified earthquake catalog. The distributed model produces an approximately uniform PGA with a maximum value of 0.185 g over CZ, while the aggregated model accents the PGA in the vicinity of the faults the maximum of 0.319 g observed around the Kazerun fault. The results show the competence of aggregating fault-based and distributed seismicity hazard assessments for applying comprehensive PSHA studies.
Biclustering for uncovering spatial-temporal patterns in telecom data
Authors: Grujić Nastasija , Brdar Sanja , Novović Olivera , Obrenović Nikola , Govedarica Miro , Crnojević Vladimir
Published: March 2021

Understanding human dynamics is of crucial importance for managing human activities for sustainable development. According to the United Nations, 68% of people will live in cities by 2050. Therefore, it is important to understand human footprints in order to develop policies that will improve the lives in urban and suburban areas. Our study aims at detecting spatial-temporal activity patterns from mobile phone data provided by a telecom service provider. To be more precise we used the activity data set which contains the amount of sent/received SMS, calls, as well as internet usage per radio-base station in defined time-stamps. The case study focus is on the capital city of Serbia, Belgrade, which has have nearly 2 million inhabitants and included the month of February 2020 in the analysis. We applied the biclustering (spectral co-clustering) algorithm on the telecom data to detect locations in the city that behave similarly in the specific time windows. Biclustering is a data mining technique that is being used for finding homogeneous submatrices among rows and columns of a matrix, widely used in text mining and gene expression data analysis.  Although, there are no examples in the literature of the algorithm usage on location-based data for urban application, we have seen the potential due to its ability to detect clusters in a more refined way, during a specific period of time that could not otherwise be detected with global clustering approach. To prepare the data for the algorithm appliance, we normalized each type of activity (SMS/Call In/Out and Internet activity) and aggregated the total activity on each antenna per hour. We transformed the data into the matrix, where rows were presenting the antennas, and columns the hours. The algorithm was applied for each day separately. On average number of discovered biclusters was 5, usually corresponding to regular based activities, such as work, home, commuting, and free time, but also to the city’s nightlife. Our results confirmed that urban spaces are the function of space and time. They revealed different functionalities of the urban and suburban parts in the city. We observed the presence of patterned behavior across the analyzed days. The type of day dictated the spatial-temporal activities that occurred. We distinguished different types of days, such as working days (Monday to Thursday), Fridays, weekends, and holidays. These findings showed the promising potential of the biclustering algorithm and could be utilized by policymakers for precisely detecting activity clusters across space and time that correspond to specific functions of the city.
Predicting extreme events using dynamics based machine learning. 
Authors: Lucente Dario , Miloshevich George , Herbert Corentin , Bouchet Freddy
Published: March 2021

Many phenomena in the climate system lie in the gray zone between weather and climate: they are not amenable to deterministic forecast, but they still depend on the initial condition. A natural example is medium-range forecasting, which is inherently probabilistic because it lies beyond the predictability time of the atmosphere. Similarly, one may ask the probability of occurrence of an El Niño event several months ahead of time or the probability of occurrence of a heat wave a few weeks in advance based on the observed atmospheric circulation. In this talk, we introduce a quantity which corresponds precisely to this type of prediction problem: the committor function is the probability for an event to occur in the future, as a function of the current state of the system. 

In the first part of this presentation, we explain the main mathematical properties of this probabilistic concept, and compute it in the case of a low-dimensional stochastic model for El-Niño, the Jin and Timmerman model. This example allows us to show that the ability to predict the probability of occurrence of the event of interest may differ strongly depending on the initial state: in some regions of phase space, the committor function is smooth (intrinsic probabilistic predictability) and in some other regions, it depends sensitively on the initial condition (intrinsic probabilistic unpredictability).  We stress that this predictability concept is markedly different from the deterministic unpredictability arising because of chaotic dynamics and exponential sensivity to initial conditions. 

The second part of the talk is about how to efficiently compute the committor function from data through several data-driven approaches, such as direct estimates, kernel-based methods and neural networks. We discuss two examples: a) the computation of committor function for the Jin and Timmerman model, b) the computation of committor function for extreme heat waves. Both systems are highly nonlinear but, considering the dimensionality of the two, their level of complexity is profoundly different. This therefore allows us to explore and discuss the performance and limits of the different methods proposed. 

Finally, we propose a method for learning effective dynamics by introducing a Markov chain on the data. Using the Markov chain we are able to quickly and easily compute many interesting quantities of the original system, including the committor function. The goal is to overcome some of the limitations of the methods introduced previously and to develop a robust algorithm that can be useful even in the lack of data.
Hortonian Surface Runoff, Hillslope Form and Energy Dynamics, can we read the fingerprints?
Authors: Schroers Samuel , Zehe Erwin
Published: March 2021

Since Horton’s famous reinterpretation of Playfair’s law hydrologists have marvelled over the organization of drainage networks in catchments and on hillslopes. We start at the cross junction of hillslope hydraulics and geomorphology, trying to interpret the formation of hydraulic networks and erosion alike and wondering why movement of fluid creates structure at all.

In its most basic form structure and form has been explained as the result of optimization, either of certain types of energy such as free energy or its thermodynamic counterpart entropy. Research has shown that river networks and river junctions tend to minimize dissipation of kinetic energy and it has been suggested that simultaneously other forms of free energy, such as sediment transport tend to increase along the flow path. Studies have focused on hydraulic networks on the hillslope scale as well as on the catchment scale. Surprisingly little attention has been given to the question why these networks exists in the first place and why discharge confluences towards the catchment outlet.

In the first part of our study we put Hortonian surface runoff into a thermodynamic framework and derive the energy balance for steady state runoff. We derive the equations on the hillslope scale, where we observe the transition from evenly distributed potential energy (the rainfall) to spatially organized discharge in micro rills to larger rills and gullies. In hydraulic terms we distinguish between sheet- and rill flow. We then apply Manning-Strickler’s equation to estimate the distribution of hydraulic variables and compare energy conversion rates on typical 1D hillslope profiles for sheet- and rill flow. Interestingly, we find that only certain hillslope forms lead to spatial maxima of stream power.

In the second part of the study we extend the energy balance to transient flow and analyse power maxima during typical rainfall-runoff events. Finally, we relate our findings to observable, measurable hydraulic structures such as rill systems and estimate past work on sediments. We believe that current energy dynamics of surface runoff reflects past optimization and therefore holds potential for the understanding of landscape evolution and surface runoff contributions alike.
Distributed modeling of groundwater recharge in a semi-arid carbonate aquifer using the integrated surface-subsurface flow simulator HydroGeoSphere
Authors: Bresinsky Lysander , Kordilla Jannes , Engelhardt Irina , Sauter Martin
Published: March 2021

Present methods to quantify recharge in karst aquifers in many cases rely on spatially and temporally aggregated precipitation values, neglecting the highly erratic, non-linear nature of infiltration dynamics that give rise to a dual-domain behavior with a slow diffuse and fast focused recharge component. Here, we demonstrate the applicability of integrated surface-subsurface flow models to simulate diffuse and preferential infiltration within the large scale Western-Mountain-Aquifer (WMA) in Israel and the Palestinian territories. A semi-arid climate region with a highly pronounced seasonality of precipitation and intense short-duration rainfalls, such as the Mediterranean region, emphasizes the importance of understanding and accounting for the complex dynamics of dual-domain infiltration and partitioning of the precipitation input signal via spatially discretized overland flow processes.

We apply HydroGeoSphere as a dual-continuum flow simulator for transient variably-saturated water flows, discretizing the rock matrix and secondary porosity (i.e., conduits and fractures) as separate overlapping continua. Flow is respectively computed via the Richards' equation with volume-averaged van Genuchten parameters, assuming that the Richards' equation is valid for both domains. The presented model accounts for surface flow via the two-dimensional Saint-Vénant equations under nonexistent inertial forces. We apply precipitation directly to the overland flow continuum and naturally account for the partitioning into Horton overland flow and percolating water. However, modeling of unsaturated flow through the conduit/fracture continuum with the van Genuchten parameterization is often limited, as the Richards' equation describes flow solely in terms of capillary forces, leading to high matric suction in the matrix continuum as a result of the smaller pore spaces (and hence constant exchange from the fracture continuum to the matrix system). In a natural system, non-linear transfer processes govern the transfer between fracture/conduit and matrix flow, such as inertia-driven infiltration (i.e., droplet, rivulet, and film flow) that initially retains itself from equilibration of capillary pressure heads and avoids instant matrix imbibition. This study demonstrates parametrization strategies to allow for infiltration through the fracture/conduit continuum using small-scale process-based simulations. Further, we offer procedures that help to achieve convergence of complex catchment-scale variably-saturated simulations.
Quanitification of sustainable hydropower potential in the Upper Indus basin
Authors: Dhaubanjar Sanita , F. Lutz Arthur , Gernaat David , Nepal Santosh , Pradhananga Saurav , Khanal Sonu , Bhakta Shrestha Arun , Immerzeel Walter
Published: March 2021

Considering the lack of a comprehensive assessement of hydropower potential in the Upper Indus basin, we developed and implemented a systematic framework to explore four different classes of hydropower potential. Our framework uses high-resolution discharge generated by a coupled cryosphere-hydrology model as the bio-physical boundary conditions to estimate theoretical potential. Thereafter, diverse context-specific constraints are implemented stepwise to estimate the technical, economic and sustainable hydropower potential. The successive classes of hydropower potential integrate considerations for various water demands under the water-energy-food nexus, multiple geo-hazard risks, climate change, environmental protection, and socio-economic preferences. We demonstrate that the nearly two thousand Terawatt-hour of theoretical potential available annualy in the upper Indus can be misleading because a majority of this is technically and economically not viable. Even smaller potential remains if we account for the various sustainability constraints that vary spatially. Our concept of the sustainable hydropower potential enables decision makers to look beyond the energy sector when selecting hydropower projects for development to achieveenergy security under the Sustainable Development Goal 7 (SDG7).The generated portfolio of sustainable hydropower projects is superior to the current portfolio based on outdated studies because our method looks beyond theoretical possibilities and excludes projects that conflict with management objectives under other SDGs. The spatial maps with potential and the cost curves for hydropower production provide a science-based knowledge base for hydropower development in the Indus basin. Our method could similarly be adapted to inform hydropower development in other basins across the globe.
Anticipating the evolution of the Fitri lake system: temporalities of an overflowing flood and its socio-ecological consequences
Authors: Christine Raimond , Tashi Yalikun , Jean-François Créteaux , Muriel Berge-Nguyen , Mathieu Schuster , Florence Sylvestre
Published: March 2021

The Sahel, located at the southern edge of the Sahara is defined as the transitional boundary of the Sahara, whose aridification since the late Holocene has profoundly affected landscapes, human occupation and ecosystems. Current climate change, characterized by an increase in temperature, raised the idea of aridification and the disappearance of surface water in the Sahelian zone. However, in central Sahel, the trend towards increasing open water surfaces seems to be confirmed over the last decade, particularly during extreme rainfall episodes. Here, we show the current changes of Lake Fitri, a remnant of the mega-lake Chad during the Holocene 6,000 years ago, whose seasonal flooding has reached unequaled levels in the last 50 years. This terminal and shallow lake and spreading out over a vast flat sedimentary plain irrigates a variable surface area. During exceptional rainy years such as the current one (2020-2021), the waters from the Batha river basin (main tributary of Lake Fitri), in the Sahelian zone, can reach the Chari catchment area (main tributary of Lake Chad) by passing through a succession of basins.

The diachronic analysis of Landsat images combined with ground-based observations recorded during the year 2020-2021 will be compared with the previous available time-series, in particular the monthly series already analysed for the year 2015 (Yalikun and al., 2019). The results confirm the trend towards the extension of the lake and the "outflow" of its waters to the west. These observations raise many questions related to the definition of a lake and its precise shoreline in this context. We will also specify the consequences in terms of the recomposition of the social-ecological system (changes in land use, recomposition of activity systems and access to natural resources, governance issues). Finally, we will discuss the timing of the changes observed in the short (annual, decade), medium (25 years), long and very long term (Holocene), on the comparability of these changes and on the elements to be considered in order to envisage the future evolution of such sahelian social-ecological system.
D region observations by VHF and HF radars to investigate Polar Mesospheric Winter Echoes
Authors: Renkwitz Toralf , Latteck Ralph , Strelnikova Irina , Chau Jorge L. , Strelnikov Boris
Published: March 2021

Polar Mesospheric Winter Echoes (PMWE) have been observed by VHF radars for quite some years. Until now, most of the studies were focussed on either major events, that occurred during solar and geomagnetic severely distorted conditions or statistical parameters like their seasonal and interannual occurrence rates as well as altitude distributions were investigated. However, especially the origin of PMWE and underlying processes are still under debate and further observations aim to contribute to this question. Recent PMWE observations with the MAARSY VHF radar included experiments using multiple beam directions to investigate the spatial structure and evolution of PMWE. Within this study we present results of MAARSY radar observations of PMWE layers complemented by simultaneous measurements by the Saura HF radar, located less than 20km apart. Major products of the Saura radar are horizontal winds and electron density within the D region. These parameters are important for both the formation and visibility of PMWE. The spectral width and localization of VHF and HF radar echoes for the presence of PMWE are analyzed and compared in the context of turbulence. Furthermore, observations during the solar minimum for the season 2019/2020 appear to be a suitable period to deepen the investigation of background conditions, excluding intensive geomagnetic disturbances.
The key role of ocean-induced non-conservative processes in Northern Hemisphere stratospheric response to climate changes.
Authors: Omrani Nour-Eddine , Keenlyside Noel , Lubis Sandro , Ogawa Fumiaki
Published: March 2021

The response of the Northern Hemisphere (NH) stratosphere to climate change has been usually studied within the classical Transformed Eulerian Mean framework, which focuses mainly on the impact of the resolved atmospheric waves. The role of the non-conservative (or wave-free) processes (like diabatic heating and diffusive potential vorticity mixing) in setting the stratospheric response to climate change remains poorly understood. Here we use different stand-alone atmospheric model experiments and the newly developed Finite Amplitude Local Wave Activity (FALWA) theory, in order to understand the role and the origins of the non-conservative processes in the NH stratospheric response to climate change.

Our model response can reproduce the well-known weakening of the NH polar stratospheric vortex and strengthening of mid-latitude and subtropical stratospheric westerlies.  It is shown that the overall structure of the wintertime response of the NH stratosphere to climate change is maintained mainly by the ocean-induced non-conservative processes with limited contribution of the wave-induced conservative dynamics. In particular, the tropical ocean warming due to climate change maintains the wave free component of the westerly wind, which setup the background wind for poleward wave propagation and the associated wave-induced weakening of the polar stratospheric vortex. The FALWA budget reveals that the weak response of the conservative (or wave induced) component of the stratospheric westerly is maintained mainly by the eddy meridional potential vorticity (PV) transport (or EP-flux divergence) against the non-conservative diffusive PV-mixing. Our work requires the consideration of the non-conservative processes for an accurate dynamical understanding of the stratospheric response to climate change.
Afar Dallol Drilling – ONset of sedimentary processes in an active rift basin (ADD-ON): Scientific drilling targets in the Afar (Ethiopia)
Authors: Foubert Anneleen , Kidane Tesfaye , Keir Derek , Atnafu Balemwal , ADD-ON Team the ICDP
Published: March 2021

Since the early days of the continental drift theory, the Afar triangle developed into an ideal field laboratory where the onset of continental and future oceanic rifting can be studied in detail. The Danakil Depression is the northern portion of the Afar triangle, bordered to the west by the Ethiopian Plateau and to the East by the Danakil Horst, and characterised by active rifting since Oligocene times. Seismo-stratigraphic interpretations based on industrial seismic sections, core and borehole data evidence the presence of Pleistocene evaporite units to a depth of about 900 m below the Dallol salt pan (central Danakil Depression, northern Afar). However, to date no sub-salt sedimentary core records have been available from the central part of the rift basin filled with likely more than 1.5 km of sediments.

The ADD-ON drilling project aims to get access to the sub-salt sedimentary archives of the Danakil basin. The overall goal is to understand sedimentary facies evolution in an active rift setting paced by global environmental fluctuations and their interplay with volcano-tectonic events. Having future access to scientific core records will give new insights into (1) the mechanical understanding of intermittent and incipient basin dynamics in an initial extensive continental rift basin: from rifting towards the development of passive margins, (2) East African climatic changes and Hominin evolution, (3) the limits of the deep biosphere in extreme hypersaline and high-temperature environments below the salt deposits, (4) natural fluid flow in an active geothermal system, and (5) monitoring of active faults, earthquakes and volcanic events in remote areas. Moreover, deep scientific drilling in Afar will be necessary in the rapid assessment of geothermal potential, the quest for ground water resources and advanced Potash exploitation.
Inverse modelling of global methane emissions using TROPOMI
Authors: van Peet Jacob , Houweling Sander , Marshall Julia , Nunez Ramirez Tonatiuh , Segers Arjo
Published: March 2021

This study investigates the use of total column methane measurements from the TROPOMI satellite instrument for estimating the global sources and sinks of methane. A bias correction method has been developed based on a comparison between the satellite measurements and an inversion using surface measurements only, building on the experience using GOSAT data. The bias correction is applied to the satellite measurements prior to the use of the data in the inversion. Results will be shown of inversions using the TM5 4D-VAR and CarboScope inverse modelling systems applied to two years of TROPOMI data. The inversion-optimized methane mixing ratios are inter-compared and validated against independent surface (WMO-GAW), Aircraft (ATom) and total column (TCCON) observations. The derived methane fluxes are aggregated over selected geographic regions, to compare the optimised methane emissions from TM5-4DVAR, CarboScope, and GOSAT inversions from the Copernicus Atmospheric Monitoring Service.

 

Methane surface mixing ratios derived from the TROPOMI inversion show a good agreement with the surface measurements in general. Near areas with high aerosol optical thickness (e.g. the Sahara) we see significant adjustments in the surface fluxes, compensating for model-data differences, pointing to influences of residual uncorrected systematic errors in the data. The total column comparison with TCCON measurements shows a slight North-South bias gradient. These finding are investigated in further detail by comparing results using the operational retrieval product to the use of the scientific RemoTeC and WFMD retrievals. Encouragingly, both the TM5 and CarboScope inversions show similar increments in the aggregated fluxes over time. The seasonal cycle in the posterior fluxes is different from that of the a a priori fluxes, which were the same for both inversion systems.
Crustal and upper mantle velocity structure of the Pannonian Region using Rayleigh wave ambient noise tomography
Authors: Timkó Máté , Wiesenberg Lars , El-Sharkawy Amr , Wéber Zoltán , Meier Thomas ,   AlpArray Working Group
Published: March 2021

The Pannonian Basin is located in Central-Europe surrounded by the Alpine, Carpathian, and Dinarides mountain ranges. This is a back-arc basin characterized by shallow Moho depth, updoming mantle and high heat flow. In this study, we present the results of the Rayleigh wave based ambient noise tomography to investigate the velocity structure of the Carpathian-Pannonian region. 

For the ambient noise measurements, we collected the continuous waveform data from more than 1280 seismological stations from the broader Central-Eastern European region. This dataset embraces all the permanent and the temporary (AlpArray, PASSEQ, CBP, SCP) stations from the 9-degree radius of the Pannonian Basin which were operating between the time period between 2005 and 2018. All the possible vertical component noise cross-correlation functions were calculated and all phase velocity curves were determined in the 5-80 s period range using an automated measuring algorithm. 

The collected dispersion measurements were then used to create tomographic images that are characterized by similar velocity anomalies in amplitude, pattern and location that are consistent with the well-known tectonic and geologic structure of the research area and are comparable to previous tomographic models published in the literature.
Short-term modulations of Venus’ disk-integrated brightness observed from the Venus orbiter Akatsuki
Authors: Lee Yeon Joo , García Muñoz Antonio , Imamura Takeshi , Yamada Manabu , Satoh Takehiko , Yamazaki Atsushi , Watanabe Shigeto
Published: March 2021

We show that Venus’ disk-integrated brightness at 283, 365, and 2020 nm is modulated by one or both of two periods of 3.7 and 4.6 days, as observed from the Akatsuki Venus orbiter of JAXA. Their typical amplitudes are <10%, but there are occasional events of 20–40%. We find a clear anti-correlation between UV and 2020-nm signals, implying that the cloud top altitudes (2020 nm) and the abundances of UV absorbers (283 and 365 nm) change simultaneously in the global scale. We note that the detected modulations, and their wavelength dependent signals imply the existence of an atmosphere if detected at an exoplanet. Our results should be useful in future direct imaging of terrestrial exoplanets. More details are shown in our paper (https://doi.org/10.1038/s41467-020-19385-6).
Operational planning of WEF infrastructure: quantifying the value of cooperation in the Eastern Nile basin
Authors: Verhagen Jeroen , van der Zaag Pieter , Abraham Edo
Published: March 2021

Integrating the operational planning of river, land and power infrastructure could safeguard the water, energy and food security in regions where these resources are under pressure by increasing demands and decreasing availabilities and production potentials. Our work focuses on the benefits of integration and cooperation in the operational planning of these resources and infrastructures between riparian states in transboundary river basins. Therefore we introduce a regional hard-linked WEF-nexus model that explicitly represents resource connectivity networks, gridded agro-hydrological potentials and constraints, national socio-economic demands and non-linear operational processes to optimise reservoir operations, water allocations, cropping patterns, electricity mixes and trade quantities on a monthly time-step over multiple years in a receding horizon fashion. This iterative process facilitates the modelling of changes as feedback against exogenous disturbances and, through the exchange of information between countries, different levels of cooperation. We optimize the total economic returns of resource allocation for four different transboundary cooperation scenarios over an historic planning period in the Eastern Nile basin, for each country and regionally, for multiple foresight settings and policy objectives. Compared to the reference scenario of unilateral planning, our results indicate an increase in regional economic returns for scenarios in which flow information is shared between countries (+8%), flow and trade information is shared (+9%) and resources are coordinated regionally (+13%), without this being accompanied by a significant decline in returns for any country. These increased returns successively come from an increase in the effectiveness of agricultural water consumption, especially in Sudan, a change in trade patterns for agricultural products and a shift in cropping patterns. These findings illustrate the importance of adequate representations of spatial and temporal heterogeneity and resource connectivity, and the need for a  more  diverse  set  of  collaboration  scenarios  to  quantify the  costs  and  benefits  of  specific  interventions  and  policies to facilitate comprehensively planning in transboundary river systems.
Co-seismic deformation, field observations and seismic fault model of the Oct. 30, 2020 Mw=7.0 Samos earthquake, Aegean Sea
Authors: Elias Panagiotis , Ganas Athanassios , Briole Pierre , Valkaniotis Sotiris , Escartin Javier , Tsironi Varvara , Karasante Ilektra , Kosma Chrysanthi
Published: March 2021

On 30 October 2020 11:51 UTC a large Mw = 7.0 earthquake occurred offshore of the island of Samos, Greece. In this contribution we present the characteristics of the seismic fault (location, geometry, geodetic moment) as inferred from the processing of geodetic data (InSAR and GNSS). We use the InSAR displacement data from Sentinel-1 interferograms (ascending orbit 29 and descending 36) and the GNSS offsets from eleven (11) permanent stations in Greece and Turkey to invert for the fault parameters. Our inversion modeling indicates the activation of a normal fault north of Samos with a length of 32 km, width of 17 km, average slip of 2.1 m, a moderate dip-angle (37°) and with a dip-direction towards North. The inferred fault is located adjacent to Samos northern coastline, with the top of the slip ~1 km below surface, and ~2 km off-shore at its closest to the island. The earthquake caused the permanent uplift of the island up to 10 cm with the exception of a coastal strip along the NE part of the northern shore (near Kokkari) that subsided 2-6 cm. The effects of the earthquake included liquefaction, rock falls, rock slides, road cracks and deep-seated landslides, all due to the strong ground motion and associated down-slope mobilization of soil cover and loose sediments.
Fungi and plant co-variation in Arctic Siberia inferred from sedimentary ancient DNA metabarcoding during the last 45.000 years
Authors: von Hippel Barbara , Stoof-Leichsenring Kathleen R. , Schulte Luise , Seeber Peter , Epp Laura S. , Lenz Matthias , Scheidt Stephanie , Herzschuh Ulrike
Published: March 2021

Climate change has a great impact on boreal ecosystems including Siberian larch forests. As a consequence of warming, larch grow is possible in areas where climate used to be too cold, leading to a shift of the tree line into more arctic regions. Most plants co-exist in symbiosis with heterotrophic organisms surrounding their root system. In arctic ecosystems, mycorrhizal fungi are a prerequisite for plant establishment and survival because they support nutrient uptake from nutrient-poor soils and maintain the water supply. Until now, however, knowledge about the co-variation of vegetation and fungi is poor. Certainly, the understanding of dynamic changes in biotic interactions is important to understand adaptation mechanisms of ecosystems to climate change.

We investigated sedimentary ancient DNA from Lake Levinson Lessing, Taymyr Peninsula (Arctic Siberia, tundra), Lake Lama, Lake Kyutyunda (both northern Siberia, tundra-taiga transition zone) and Lake Bolshoe Toko (southern Siberia, forest area) covering the last about 45.000 years using ITS primers for fungi along with the chloroplast P6 loop marker for vegetation metabarcoding. We found changes in the fungal communities that are in broad agreement with vegetation turnover. To our knowledge, this is the first broad ecological study on lake sediment cores to analyze fungal biodiversity in relation to vegetation change on millennial time scales.
The Polarization of Ambient Noise on Mars 
Authors: Stutzmann Éléonore , Schimmel Martin , Lognonné Philippe , Horleston Anna , Ceylan Savas , van Driel Martin , Stahler Simon , Banerdt Bruce , Calvet Marie , Charalambous Constantinos , Clinton John , Drilleau Mélanie , Fayon Lucile , Garcia Raphael , Jacob Alice , Kawamura Taichi , Kenda Balthazar , Margerin Ludovic , Murdoch Naomie , Panning Marc ,   Insight group
Published: March 2021

Seismic noise recorded at the surface of Mars has been monitored since February 2019, using the InSight seismometers.This noise can reach -200 dB and is 500 times lower than on Earth at night and it increases of 30 dB during the day. We analyze its polarization as a function of time and frequency in the band 0.03-1Hz. We use the degree of polarization  to extract signals with stable polarization independent of their amplitude and type of polarization. We detect polarized signals at all frequencies and all times. Glitches correspond to linear polarized signals which are more abundant during the night. For signals with elliptical polarization, the ellipse is in the horizontal plane below 0.3 Hz (LF). Above 0.3 Hz (HF) and except in the evening, the ellipse is in the vertical plane and the major axis is tilted. While polarization azimuths are different in the two frequency bands, they both vary as a function of local hour and season.  They are also correlated with wind direction, particularly during the daytime.

We investigate possible aseismic and seismic origins of the polarized signals. Lander or tether noise can be discarded. Pressure fluctuations transported by wind may explain part of the HF polarization but not the tilt of the ellipse. This tilt can be obtained if the source is an acoustic emission coming from high altitude at critical angle. Finally, in the evening when the wind is low, the polarized signals may correspond to the seismic wavefield of the Mars background noise.
NanoMagSat, a 16U nanosatellite constellation high-precision magnetic project to initiate permanent low-cost monitoring of the Earth’s magnetic field and ionospheric environment
Authors: Hulot Gauthier , Léger Jean-Michel , Clausen Lasse B. N. , Deconinck Florian , Coïsson Pierdavide , Vigneron Pierre , Alken Patrick , Chulliat Arnaud , Finlay Christopher C. , Grayver Alexander , Kuvschinov Alexey , Olsen Nils , Thébault Erwan , Jager Thomas , Bertrand François , Häfner Tobias
Published: March 2021

The geomagnetic field has been continuously monitored from low-Earth orbit (LEO) since 1999, complementing ground-based observatory data by providing calibrated scalar and vector measurements with global coverage. The successful three-satellite ESA Swarm constellation is expected to remain in operation up to at least 2025. Further monitoring the field from space with high-precision absolute magnetometry beyond that date is of critical importance for improving our understanding of dynamics of the multiple components of this field, as well as that of the ionospheric environment. Here, we will report on the latest status of the NanoMagSat project, which aims to deploy and operate a new constellation concept of three identical 16U nanosatellites, using two inclined (approximately 60°) and one polar LEO, as well as an innovative payload including an advanced Miniaturized Absolute scalar and self-calibrated vector Magnetometer (MAM) combined with a set of precise star trackers (STR), a compact High-frequency Field Magnetometer (HFM, sharing subsystems with the MAM), a multi-needle Langmuir Probe (m-NLP) and dual frequency GNSS receivers. The data to be produced will at least include 1 Hz absolutely calibrated and oriented magnetic vector field (using the MAM and STR), 2 kHz very low noise magnetic scalar (using the MAM) and vector (using the HFM) field, 2 kHz local electron density (using the m-NLP) as well as precise timing, location and TEC products. In addition to briefly presenting the nanosatellite and constellation concepts, as well as the evolving programmatic status of the mission (which already underwent a consolidation study funded by the ESA Scout programme), this presentation will illustrate through a number of E2E simulations the ability of NanoMagSat to complement and improve on many of the science goals of the Swarm mission at a much lower cost, and to bring innovative science capabilities for ionospheric investigations. NanoMagSat could form the basis of a permanent collaborative constellation of nanosatellites for low-cost long-term monitoring of the geomagnetic field and ionospheric environment from space.
Solving uncertainties in Neoproterozoic paleogeographic reconstructions: the key to understanding the links between the Earth's outer and inner envelopes?
Authors: Macouin Melina , Rousse Sonia , Antonio Paul
Published: March 2021

The Neoproterozoic is marked by unusual perturbations of the climate system (global glaciations), biogeochemical cycles (e.g. oxygenation, Carbon), and life diversity that will lead to a world as we know it today. These upheavals can be considered from the point of view of paleogeographic reconstructions to decipher the forcing mechanisms and consequences. The paleopositions of the continents and their geology impact the continental weathering, a fundamental element in the feedbacks driving the climate. Besides, the position of the supercontinent Rodinia and the nature of its margins influence degassing, itself a major factor in biogeochemical cycles. Neoproterozoic paleogeographic reconstructions are based on some reliable paleomagnetic data and geological evidence of kinship between the cratons. Uncertainties in Neoproterozoic paleogeographies hinder our understanding of the relationship between deep Earth and superficials layers. Notably, the positions of the cratons that will constitute the Arabian-Nubian shield are poorly constrained. The paleomagnetic results we obtained in Oman on well-dated mafic dykes, indicate a mid-latitude position at the dawn of the Sturtian glaciation. These results show the potential of these small cratons, which represent a zone of arcs and arc collisions, in our understanding of the geodynamics of the Rodinia supercontinent. We then propose a refined configuration at ca. 720 Ma, highlighting the extent of snowball Earth deposits.