bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of spectra-temporal analysis methods to detect common signals in length of day, global sea level rise, global temperature data, and ENSO indices
Authors: Kosek Wieslaw
Published: March 2020

It is already well known that intra-seasonal oscillations in the Earth’s global temperature are driven by ENSO (El Niño Southern Oscillation) events. ENSO signal is also present in length of day and global sea level rise, because during El Niño the increase of the length of day and global sea level rise can be noticed. To detect common oscillations in length of day, global sea level rise, global temperature data and ENSO indices the wavelet-based semblance filtering method was used. This method, however, seeks the signals with a good phase agreement of oscillations in two time series thus, no phase agreement results in very small amplitudes of the common signals. The spectra-temporal semblance functions allow detecting the similarity of two time series in spectral bands in which the amplitudes and phases of the oscillations are consistent with each other. The amplitudes of oscillations in the considered data vary in time and in order to detect the signals with similar amplitude variations between pairs of time series the normalized Morlet wavelet transform (NMWT) and the combination of the Fourier transform bandpass filter with the Hilbert transform (FTBPF+HT) were used. These two methods enable computation of the instantaneous amplitudes and phases of oscillations in two real-valued time series. In order to detect oscillations with similar amplitude variations in two time series correlation coefficients between the amplitude variations as a function of oscillation frequencies were computed.
Detection of mantle CO2 in an underground salt mine via long-term and high-resolution monitoring by laser-based isotope techniques
Authors: Frank Alexander H. , van Geldern Robert , Myrttinen Anssi , Zimmer Axel , Zimmer Martin , Barth Johannes A. C. , Strauch Bettina
Published: March 2020

Salt deposits may be affected by post-depositional CO2 intrusions. In central Germany, such CO2 contributions from the mantle may originate from Tertiary Rhön- and Vogelsberg-volcanism. The intrusion of those gases may cause technical and operational implications for storage caverns and salt mines.

Carbon isotope compositions of CO2 are useful tools to differentiate between sources and are expressed as δ13C values in ‰ versus an international standard known as the Vienna Pee Dee Belemnite (VPDB). Typical average endmember values for CO2 from the mantle are -5.1 ‰, while background air and anthropogenic influences range around averages of -11.9 ‰ and -29.8‰. Detection of fluctuations between these endmembers can be challenging with discrete sampling. This can be overcome by high-temporal resolution and long-term monitoring.

Towards this purpose, a laser-based isotope system was set up in an active underground salt mine in central Germany. For 34 days, continuous measurements of δ13C and concentrations of CO2 were generated close to a site where mantle CO2 intrusions were suspected. A timer regularly switched intakes from two capillaries, of which one was placed inside a borehole and the other in ambient air of the mine. Measured CO2 concentrations ranged between 700 and 1600 ppmV, while δ13C values ranged between -21.5 ‰ and -11.5 ‰. Lower concentrations coincided with more positive isotope values and occurred around weekends when anthropogenic influences in the mine were less.

While influences of fresh air venting may have caused these weekly shifts, the admixture of mantle CO2 seemed to play a continuous role. This is because small differences between the capillary from the borehole and the one with ambient air existed throughout the time series. Our results indicate that short-term dynamics on the order of hours to days are overlain by admixtures mantle gas intrusions of CO2.
Geological history and tectonic implication of the Kucherov Terrace (East Siberian Arctic shelf).
Authors: Freiman Sergei , Nikishin Anatoly
Published: March 2020

The Kucherov Terrace is a prominent flat platform lies on a depth about 1200 meters below sea level between shelf area of the Chukchi Sea and deep-water area of Podvodnikov Basin and Mendeleev Rise. Due to location between main tectonic features of the East Arctic basin this territory carries some important insights to the tectonic history of the Arctic. By available seismic data and regional seismic correlation, we outlined series of the key moments of the geological history and estimated ancient geomorphological features of the territory.   

Based on our interpretation we suppose main rifting event took place on the territory in Aptian-Albian ages. After the rifting stage thermal subsidence lead to increasing of water depth and infilling of the basin by sediments from the Siberia territory. Two main stages of sedimentary history of the area were identified: Late Cretacerous-Paleocene and Eocene-Recent.    

By presence of obvious clinoform sequences in a sedimentary cover of the Kucherov terrace, we interpret the terrace itself as submerged ancient shelf was formed not later than end of Paleocene. Using clinoform geometry we calculated paleodepth of the Podvodnikov and Toll basins as around 800-1000 meters below sea level in Paleocene. At the same time adjacent to the shelf area seamounts of the Mendeleev Rise already existed in this time and played a role of a natural barrier to the prograding shallow-marine clastic wedges.  By shelf-edge position of a clinoform sets we estimated mean subsidence rates as 15-22 meters/myr in an area with preceding sediment loading less than 3 km.  The obtained estimates can be used as good constraints during further subsidence modelling.

During Eocene-Recent stage existence of flat platform led to a peculiar pattern of a sedimentation in a Chukchi shelf. Shallow-marine circumstances led to a very fast descending profile with less or absence of basin-floor fans. Formation of the mass wasting deposits starts in this area only in the Miocene unlike adjacent territories.

The study was funded by RFBR ‐ projects № 18-05-70011 and 18-05-00495.

 
The biogeochemical research of microbial hopanoids in Dajiuhu peatland, central China
Authors: Xue Jiantao , Huang Xianyu
Published: March 2020

Peatlands are a vast store of organic carbon and play a significant role in the global carbon cycle. The abundance of lipids, especially microbial hopanoids are, directly or indirectly, participating in the carbon cycle in peatlands. Although the hopanoids and their compound-specific carbon isotope composition have been applied to some extent in the study of paleoenvironment and paleoecology, it is still misty about the diagenetic transformation process and the main controlling factors of the early diagenetic transformation of hopanoids. The potential of paleo-ecological application of hopanoids is still lack of systematic understanding. Previously we investigated several typical peatlands in China and found pH plays an important role in the early diagenetic transformation of bacteriohopanepolyols (BHPs) into geohopanoids. We also found the pH value promotes the isomerization of geohopanoids. Here, we focus on the biogeochemical research of microbial hopanoids in Dajiuhu peatland. We  first carried out a series of modern process monitoring on a seasonal scale, such as monthly investigating the climate factors (air temperature, air humidity, rainfall), water, soil temperature, soil moisture, water chemistry (pH, ORP, conductivity, dissolved oxygen), the main nutrient (nitrate, phosphate, etc.), dissolved organic carbon (content, composition and isotopic composition). On this basis, we discussed the relationship between those compounds (composition, carbon and hydrogen isotopes) and the climate-environmental conditions as well as the carbon dynamics. Further on, we examined the response of the carbon cycle based on hopanoid index in a peat core (18ka BP) in Dajiuhu peatland. Our results showed that in acidic peat deposits in Dajiuhu peatland, the carbon isotopes of hopane are generally more than 5‰ positive compared with the carbon isotopes of n-alkanes from higher plants both the surface peat samples and core peat samples, which indicates that in acidic peat environment, the hopanoid-produced bacteria mainly take carbohydrate as carbon source. We also showed that the difference of the carbon isotopes between hopane and n-alkanes is not stable, suggesting that these hopanoids may use different carbon sources.
Multi-decadal (1953 – 2017) response of rock glacier morphodynamics to climate change in the Kauner Valley in the Ötztaler Alps, Austria based on historical aerial images and airborne LiDAR data
Authors: Fleischer Fabian , Haas Florian , Heckmann Tobias , Altmann Moritz , Piermattei Livia , Rom Jakob , Becht Michael
Published: March 2020

Although the observed global climate change has particularly affected high-alpine regions and these geosystems seem to react very sensitively to changes in external forcing, there is a lack of understanding about the effect of a changing climate upon high-alpine landscapes at the timescale of decades.  In the case of rock glaciers, which are common features in high alpine periglacial landscapes, numerous studies suggest a general acceleration of rock glacier displacement rates accompanied by surface lowering. This behaviour has been attributed to the rising permafrost temperature, induced by atmospheric warming and regulated by thermo-hydrological processes. On the other hand, decoupled kinematics of nearby rock glaciers under the same climatic forcing have also been proven. This is attributed to different local topo-climatic conditions and genesis of the investigated rock glaciers.  To contribute to the understanding of multi-decadal rock glacier response to climate change, we investigate the morphodynamic changes for selected rock glaciers in the Upper Kauner Valley in the Ötztaler Alps, Austria, a catchment comprising numerous rock glaciers of different size, genesis, elevation, aspect and activity status. This is done for multiple time slices between 1953 and 2017. These changes are analysed with respect to rock glacier characteristics and changes in the meteorological forcing. This work is part of the interdisciplinary and multi-university research project SEHAG (Sensitivity of high alpine geosystems to climate change since 1850), which aims to investigate changes in different processes of alpine geosystems and their interaction.

In order to investigate morphodynamics of the rock glaciers, we use digital photogrammetry to generate orthophotos and digital elevation models from historical aerial images (available since 1953). Additionally, we use digital elevation models generated from three airborne LiDAR surveys within the period 2006-2017. While the diachronic analysis of digital elevation models predominantly addresses vertical surface changes, image correlation of multitemporal digital orthophotos yields information on rates of horizontal displacement. The results for the individual rock glaciers are compared to each other and to meteorological data of nearby weather stations to analyse the response of rock glaciers with different characteristics to changing climate forcing. 
Dynamics of ecosystem services and their driving factors in China’s Beijing-Tianjin-Hebei regional development
Authors: Li Suxiao , Lei Guangchun , Yu Xiubo
Published: March 2020

Abstract: A comprehensive study on the dynamics of ecosystem services and their driving factors is the key prerequisite for enhancing local ecological sustainability. Based on relevant sets of big data, including spatial land data, soil data, DEM, climatic data and social-economic data, using InVEST model and multivariate logistic regression model, the study firstly assessed the spatiotemporal variation of ecosystem services for China’s Beijing-Tianjin-Hebei (Jing-Jin-Ji) region from 1990 to 2015. The study then analyzed the natural and socioeconomic factors affecting the ecosystem services. The results show that large spatial and quantitative differences exist in the supply of multiple ecosystem services, and the changes of different types of ecosystem services are driven by different factors. For water yield, the areas of arable land, wetland and built-up land and precipitation are the most influential factors; The areas of arable land, precipitation, temperature, altitude, urbanization rate and amount of nutrient applied per unit area are determinants of changes in nutrient retention; The areas of grassland and forest, temperature, altitude, GDP per capita and urbanization rate affect the soil retention to great extent; for carbon storage, its key influential factors are the areas of different land use types and urbanization rate. The study can facilitate identification of where and how to enhance multiple ecosystem services.

Keywords: dynamics of ecosystem services, driving factors, InVEST, multivariate logistic regression model
Experimental microfracture propagation in gneiss through frost wedging
Authors: Anselmetti Flavio , Musso Piantelli Ferdinando , Herwegh Marco , Waldvogel Marius , Gruner Ueli
Published: March 2020

Ice-driven mechanical weathering in mountainous environment is considered an efficient process for slow preconditioning of rockfalls. In this study (Musso Piantelli et al., 2020), we simulate with an innovative experimental approach subcritical fracture-propagation under frost-wedging conditions through pre-existing weaknesses of intact rock bridges. Two series of freeze-thaw experiments in an environmental chamber have been designed to investigate and monitor the propagation of artificially-induced fractures (AIF) in two twin gneiss samples. By employing 3D X-Ray Computed Tomography and a displacement sensor, an accurate characterization and new insights into the fracture-propagation mechanism are provided. Our results demonstrate that frost wedging propagated the AIFs of 1.25 cm2 and 3.5 cm2 after 42 and 87 freeze-thaw cycles, respectively. The experiments show that volumetric expansion of water upon freezing, cooperating with volumetric thermal expansion and contraction of the rock, plays a key role in fracture widening and propagation. Based on these results, this study proposes that: (i) frost wedging exploits intrinsic pre-existing weaknesses of the rock; (ii) the fracturing process is not continuous but alternates propagation stages to phases of tensile stress accumulation; and (iii) downward migration of “wedging grains”, stuck between the walls of the fracture, increases the tensile stress at the tip, widening and propagating the fractures with each freeze-thaw cycle. The experimental design developed in this study offers the chance to visualize fracture-propagation in natural joints quantifying the long-term efficiency of this process in near-natural scenarios.

REFERENCES

Musso Piantelli, F., Herwegh, M., Anselmetti, F.S., Waldvogel, M., Gruner, U., (2020). Microfracture propagation in gneiss through frost wedging: insights from an experimental study. Natural Hazards, 1-18. https://doi.org/10.1007/s11069-019-03846-3
Solar radiation pressure model of GPS and GLONASS satellites considering potential surface radiator impact
Authors: Duan Bingbing , Hugentobler Urs , Selmke Inga
Published: March 2020

Within the IGS (International GNSS Service), precise orbit and clock products of GPS and GLONASS satellites as well as Earth rotation parameters (ERPs) are routinely generated by individual analysis centers. As the dominant non-gravitational perturbation, solar radiation pressure (SRP) is modeled differently by different centers. Without surface properties, the empirical CODE orbit models (ECOM, ECOM2) are mostly used. We find that the ECOM models are not optimal for GLONASS satellites, especially during the eclipsing seasons. Also, the use of a conventional a priori box-wing (BW) model does not help much. By assessing the ECOM estimates we conclude that there are potential radiators on the –x surface of GLONASS satellites causing orbit perturbations in eclipse as well. Based on this finding, we firstly adjust optical properties of GLONASS satellites considering the potential radiator and thermal radiation effects. Then, we introduce all the adjusted parameters into a new a priori model and jointly use it together with the ECOM models. Results show that orbit misclosure between two consecutive arcs reduces by about 30 % for the ECOM model during the eclipsing seasons. In addition, the spurious pattern of the satellite laser ranging (SLR) residuals is greatly reduced. Also, we have repeated the same adjustment of optical properties for GPS satellites by using 6 years’ data (2014 - 2019). We evaluate GPS orbits, ERPs and geocenter products calculated with different SRP models (ECOM, ECOM+BW, ECOM2, ECOM2+BW, adjustable BW, GSPM) and present corresponding systematic errors of each product at harmonics of the GPS draconitic year.
Observations of Magnetotail Interchange Heads' Signatures at Later Stage of Development
Authors: Panov Evgeny V. , Lu San , Pritchett Philip L.
Published: March 2020

The kinetic ballooning/interchange instability (BICI) was recently found to produce azimutally narrow interchange
heads extending from the near-Earth magnetotail into the dipole region. In their nonlinear evolution individual
heads were predicted to grow into transient earthward moving northward magnetic field intensifications
(dipolarization fronts; DFs). The distinguished signatures of such fronts would be their oblique propagation
and cross-tail localization due to the finite k$_y$ structure of the BICI modes. We compare DFs that were observed
by two THEMIS probes at 11 Earth's radii (R$_E$) downtail amidst previously identified interchange heads with a
simulated interchange head during later-stage BICI development. The comparison shows that the DFs propagated
dawnward at about 45$^{\circ}$ to the earthward direction. The leading edges and trailing tails of the DFs were
structured similarly to those of the simulated interchange head. The analysis evidences that BICI indeed releases
obliquely propagating azimuthally localized dipolarization fronts in the Earth's magnetotail. 
A spectroscopic view of mineral aerosol surface aging under atmospheric conditions
Authors: Abdelmonem Ahmed , Lützenkirchen Johannes , Ratnayake Sanduni , Hiranuma Naruki
Published: March 2020

Atmospheric mineral aerosols have direct and indirect influence on the climate system. So far, atmospheric interactions studies have mainly focused on pristine samples, despite the fact that aerosol particles may age under natural atmospheric conditions. For example, multiple freeze-melt or evaporation-condensation cycles of an aerosol-containing cloud droplet can change the surface chemistry of the aerosol particle, the droplet ionic strength and pH. These changes have a large impact on the ice nucleation ability of the aerosol particles. We probe the water structure and surface chemistry at water-mineral interface using surface spectroscopic techniques, particularly supercooled nonlinear spectroscopy [1-4]. We found that successive freeze-melt cycles disrupt the dissolution equilibrium, substantially changing the surface chemistry, giving rise to variations ice nucleation ability of the surface [4]. Along the aging process, the restructuring of the water molecules at the surface upon cooling changes. This was found to be correlated to the ice nucleation ability of the surface. We present here a spectroscopic overview on aging of selected mineral surfaces (Al2O3, Silica, Mica and PbO). We found that the pH, ionic strength, time in contact with water and number of freezing-melting events influence the aging dynamics and hence the ice nucleation ability.

 

Abdelmonem, A., Direct Molecular-Level Characterization of Different Heterogeneous Freezing Modes on Mica – Part 1. Atmos. Chem. Phys., 2017. 17(17): p. 10733-10741.

Abdelmonem, A., et al., Surface-Charge-Induced Orientation of Interfacial Water Suppresses Heterogeneous Ice Nucleation on α-Alumina (0001). Atmos. Chem. Phys., 2017. 17(12): p. 7827-7837.

Lützenkirchen, J., et al., A set-up for simultaneous measurement of second harmonic generation and streaming potential and some test applications. Journal of Colloid and Interface Science, 2018. 529: p. 294-305.

Abdelmonem, A., et al., Cloud history changes water-ice-surface interactions of oxide mineral aerosols (e.g. Silica). Atmos. Chem. Phys. Discuss., 2019. 2019: p. 1-17.

 
Biostratigraphic dating of palaeolake deposits from an overdeepening in the Swiss Northern Alpine Foreland by numerical assessments of vegetation composition and the role of species dynamics
Authors: Schläfli Patrick , Gobet Erika , Tinner Willy , van Leeuwen Jacqueline , Vescovi Elisa , Douillet Guilhem , Schwenk Michael , Bandou Dimitri , Schlunegger Fritz
Published: March 2020

Pollen analysis has shown that at regional to subcontinental scales interglacial vegetation successions usually follow similar patterns throughout the Middle and Late Quaternary. Yet, relevant compositional and species-specific differences among interglacials exist and contribute to their characteristic biostratigraphic fingerprint. We use these divergences to indirectly date palaeolake deposits from Spiezberg (SW margin of overdeepened lake Thun, Switzerland), which have been assigned to either MIS 5e (last interglacial) or MIS 7a (penultimate interglacial) according to the average IRSL age of 164 ± 16 ka. For this purpose, we analyzed the fossil pollen record of the Spiezberg palaeolake deposits and applied optimal partitioning and the broken stick model for zonation. Furthermore, we re-assessed local pollen assemblage zones (LPAZ) of two physically dated reference records (Beerenmösli: MIS 5e; Meikirch: MIS 7a) from the study area by using the same zonation approaches. LPAZ of all three records were then compared optically and numerically (PCA and significance tests) to test which of the two reference records is more similar to Spiezberg. Pollen data show that the major part of the Spiezberg record was sedimented during full interglacial conditions. The irrelevance of Fagus points towards an MIS 5e age for the sediments. This is supported by PCA axis 2, which shows a statistically significant similarity of the Spiezberg record to the MIS 5e reference. This outcome is explained by Fagus playing an important role in the PCA axis 2 gradient, which is probably determined by competition for light. PCA axis 1 is not taken into consideration for the correlation since it represents a climate gradient (e.g. from boreal to temperate forests) and explains most of the intra-locality but less of the inter-locality variance. We thus assign the Spiezberg record to the last interglacial and show that climate-driven compositional differences between MIS 5e and MIS 7a are not diagnostic. In contrast, distinct differences in single-species abundances (e.g. Fagus) are strong enough to significantly distinguish between MIS 5e and MIS 7a records. We conclude that variability across various interglacial vegetation successions (e.g. MIS 5e vs. 7a, PCA axis 2) is smaller than local vegetation variability within a full interglacial succession at the same site (PCA axis 1). This implies a very high vegetation resilience to glacial-interglacial climatic variability, the biotic properties involved might be migration capacity, survival in refugia and adjustments to rapidly changing Quaternary environments.
How sensitive is the sub-seasonal prediction to the choice of dynamical cores in the atmospheric model?
Authors: Kim Ha-Rim , Kim Baek-Min , Jun Sang-Yoon , Choi Yong-Sang
Published: March 2020

This study investigates the prediction skill of the sub-seasonal prediction model that can depend on the choice of dynamical cores: the finite volume (FV) dynamical core on a latitude-longitude grid system versus spectral element (SE) dynamical core on a cubed-sphere grid system. Recent researches showed that the SE dynamical core on a uniform grid system increases parallel scalability and removes the need for polar filters mitigating uncertainty in climate prediction, particularly for the Arctic region. However, it remains unclear whether the choice of dynamical cores can actually yield significant skill changes or not. To tackle this issue, we implemented a sub-seasonal prediction model based on the Community Atmospheric Model version 5 (CAM5) by incorporating the above two dynamical cores with virtually the same physics schemes. Sub-seasonal prediction skills of the SE dynamical core and FV dynamical core are verified with ERA-interim reanalysis during the early winter (November – December) and the late winter (January – February) from 2001/2002 to 2017/2018. The prediction skills of the two different dynamical cores were significantly different regardless of the virtually same physics schemes. In the ocean, the predictability of the SE dynamical core is similar to the FV dynamical core, mostly because of our simulation configuration imposing the same boundary and initial conditions at the surface. Notable differences in the one-month predictability between the two cores are found for the wintertime Arctic and mid-latitudes, particularly over North America and Eurasia continents. With the one-month lead, SE dynamical core exhibited higher predictability over North America in late winter, whereas the FV dynamical core showed relatively higher predictability in East Asia and Eurasia in early winter. One of the reasons for these differences may be the different manifestations of Arctic-midlatitudes linkage in the two dynamical cores; the SE dynamical core captures warmer Arctic and colder mid-latitudes relatively well than the FV dynamical core. Therefore, we conclude that the careful choice of dynamical cores of sub-seasonal prediction models is needed.
Sounds of the deep subduction zone plumbing system: modeling non-volcanic tremor activity in a fault-valve, pore-pressure diffusive system
Authors: Farge Gaspard , Shapiro Nikolai , Jaupart Claude , Kaminski Édouard
Published: March 2020

The activity of slow-earthquakes in subduction zones have been closely linked to fluid circulation processes — like hydro fracturation and pore-pressure pulses — on the one hand by geological observations and on the other hand by slow-earthquake triggering and interaction models. In deep fault zone environments, where slow slip events and various regimes of tremor are observed, fluids coming from metamorphic dehydration of slab sediments are channeled towards the surface. Geological observations indicate that fluid transport conditions vary significantly on short time scales, and along dip, strike and width of the fault zone. In homogeneously permeable systems where fluids transit under stable conditions, pore-pressure can be described by a diffusion equation. We use a time and space bimodal description of the transport properties to model a tremor generating, permeable fault zone. Thin zones of low permeability acting as valves are distributed along the 1D channel with a higher background permeability. When a threshold pore-pressure differential is reached, the valve permeability is brought to background levels, until the barrier is healed and closes again. In this model, the opening of a valve occurs at the same time as the source of a low-frequency earthquake (LFE) is triggered. In such a set up, sources interact uniquely due to the channeling of stress through pore-pressure diffusion, and the interaction characteristics in time/space are described in the framework of a diffusive system. When the number of sources is high, the model can reproduce clustering behaviours observed for LFE activity in subduction zones. The transition from a Poisson process description of seismicity to highly clustered, cascading events is governed by the source interaction distances, directly relating to the transport properties of the medium. In time, such a model is meant to diagnose the transport conditions in a subduction zone or a magmatic system, provided that it can be characterized by clustering statistics on the low-frequency seismicity it generates.
The Cenomanian–Turonian boundary mass extinction (Late Cretaceous): Ammonoid biodiversity in the Eastern Desert, Egypt
Authors: Hefny Ahmed , El Qot Gamal M. , El Araby Abd El Moneim , Aly Mohamed F.
Published: March 2020

The Cenomanian-Turonian (C-T) mass extinction occurred during a peak global greenhouse interval, with eustatic sea-level elevated nearly 300 m above present stand. The time period spanning the Cenomanian–Turonian boundary was characterized by profound paleoenvironmental changes at global scale. World-wide consequences of these events have been the focus of new reports and their influence on local to regional depositional systems. A faunal turnover is recorded in the uppermost Cenomanian, marked by the disappearance of most of the Cenomanian taxa. The macrofossil contents of two Upper Cretaceous sections from Wadi Qena, central Eastern Desert, Egypt have been collected and studied in detail. These fossils, ranging in age from Late Cenomanian to middle Turonian. The Cenomanian- Turonian sequence of centeral Eastern Desert is represented by the fossiliferous Galala formation (about 90 meter) at base and Umm Omeiyid formation (about 40 meter) at top. The Galala Formation is characterized by shale, fossiliferous marl, marly limestone, sandstone and siltstone interbeds. The Umm Omeiyid Formation overlies the Galala Formation unconformably. It consists of unfossiliferous siltstone with fine, medium-grained hummocky cross-stratified sandstone intercalations with a few fossiliferous limestone beds and marl intercalations. The Cenomanian-Turonian boundary cuts within the upper part of the Galala Formation at the last occurrence (LO) of Vascoceras cauvini and the first occurrence (FO) of Vascoceras proprium. There is rapid faunal change across the Cenomanian-Turonian boundary in all the studied sections. Most benthic fauna become extinct at the Upper Cenomanian and new taxa appeared at the Lower Turonian. All Upper Cenomanian cephalopod taxa become extinct at the same level and new taxa appeared at the Lower Turonian. The faunal diversity decreased from the Upper Cenomanian to the Lower Turonian. The ammonite ranges are used for a biostratigraphic zonation of the Cenomanian- Turonian succession in the northern and central parts of Wadi Qena. five ammonite zones have been distinguished (Neolobites vibrayeanus Zone , Vascoceras cauvini Zone , Vascoceras proprium Zone , Choffaticeras (Choffaticeras) segne Zone  and Coilopoceras requienianum Zone).
Increased predictability of spring precipitation over central East China around the late 1970s
Authors: Zhang mengqi , Sun jianqi
Published: March 2020

The predictability of spring (March–May) precipitation over East China is investigated in the present study based on the February-start hindcasts of eight coupled models from DEMETER and ENSEMBLES during 1960–2001. Five out of the eight models exhibit significantly increased predictability of central East China spring precipitation (CECSP) after the late 1970s. The mechanism analysis indicates that CECSP variability is closely related to a meridional dipole vorticity pattern at 200 hPa and southerly wind at 850 hPa over East Asia, whose prediction skill also increased significantly around the late 1970s, consistent with the changes in CECSP predictability. Observational analysis indicates that the sea surface temperature (SST) over the tropical Pacific and Indian Ocean experienced a notable decadal change around the late 1970s. After the decadal change, the tropical SST has an enhanced impact on the CECSP-related East Asian dipole vorticity pattern at the upper level and on the western North Pacific anticyclone at the lower level. The five models can adequately reproduce the observed enhanced connection between the tropical SST and East Asian atmospheric circulation after the late 1970s, consequently showing higher predictability of East Asian atmospheric circulation and CECSP. However, the other three models cannot reproduce the relationship between the tropical SST and East Asian atmospheric circulation; therefore, CECSP predictability in these models remains low during the entire period. The increased predictability is valuable for current dynamical seasonal prediction for central East China.
Potential of environmental DNA for tracing land-use based sediment sources
Authors: Foucher Anthony , Evrard Olivier , Ficetola G. Francesco , Gielly Ludovic , Poulain Julie , Giguet-Covex Charline , Laceby J. Patrick , Salvador-Blanes Sébastien , Cerdan Olivier , Poulenard Jérôme
Published: March 2020

Environmental DNA (eDNA) is a complex mixture of genetic material extracted from environmental samples like soil, water or sediment in order to obtain reliable information on the past and current biological communities. In recent years, the eDNA technique was successfully applied to sediment accumulated in lakes for providing information on past land use and land cover changes in their drainage areas. Recently, the potential of eDNA for providing detailed information on the plant species found in sediment sources was investigated. These research highlight the powerful potential of this method for improving our ability to detect the vegetal communities causing erosion and sediment delivery. Nevertheless, some fundamental questions remain like for example the DNA memory effect of soils. How long the plant signature can persist in soils? Are we recording the last species cultivated or a mixture of past plants in agricultural areas? These issues are of prime importance for examining the potential of eDNA as a new sediment tracer.

To answer these questions, two contrasted sites located in intensively cultivated environments in France were studied. In the first site, soil samples were collected (n=30) in plots for which the crop rotation history was well documented since 1975. In particular, crops cultivated only once during the rotation were used as potential chronological markers. The impact of agricultural practices on eDNA preservation was also investigated comparing soil signatures under conventional and conservation farming. In the second site, samples were collected (n=40) to compare the abundance of currently observed taxa versus detected taxa in cropland, grassland, woodland and river channel banks.

The results showed that the last cultivated crop was detected in 100% of the samples as the most abundant taxa under conventional farming and 75% under no-tillage. The last cultivated species was the most abundant in 80% of the studied plots. Interestingly, grapevine was detected in 46% of the cultivated plots of the second site, although this plant is no longer cultivated in this catchment. In addition, a large variety of weeds were detected in both sites in addition to the cultivated species. eDNA results provided by the current research illustrate the potential of this method for identifying the recent (<7 years) land cover history of soils which may allow to improve our understanding of sediment mobilization and transfer processes over short timescales.
Chemical and geotechnical analysis of the mortar and rammed earth from merinid walls of the Morrocan historical monument Chellah-Rabat for detection of alteration products and the origin of the original materials used.
Authors: Belhaj Siham , Jaouda Imane , Souidi Hanane , Aqil Mohammed
Published: March 2020

Rabat, the capital of the Moroccan Kingdom, listed as a UNESCO World Heritage Site in 2012, has several historic monuments testifying its diversity and richness in tangible and intangible heritage, cultural richness, architectural diversity that perpetuates the different dynasties that are succeeded over time on this Kingdom.

The Chellah monument testifies to this diversity by including within its walls a variety of civilizations.

This special monument by its architecture, its history, its situation in the city of Rabat, knows physical and chemical degradation due to its location and the peculiarity of its building materials as well as the techniques used for the construction or for the rehabilitation.

In this work we have tried to decipher these causes and to quantify these degradations by the petrographic, mineralogical, geotechnical and chemical identifications of the products of the alteration, via laboratory analyzes such as the scanning electron microscope equipped with the EDX system, the diffraction X-ray ,fluorescence and  particle size analysis. This is to optimize the choice of alternative materials, while taking into account all the multidisciplinary scientific mechanisms and processes necessary for a better protection of the built material heritage that constitutes a collective memory of this country.

 

 

 
Geometric Controls of Fjord Glacier Dynamics
Authors: Frank Thomas , Åkesson Henning , de Fleurian Basile , Nisancioglu Kerim H
Published: March 2020

 

 

 

 
Interannual stratification changes affect tides in the Gulf of Maine
Authors: Kotzian Daniel , Schindelegger Michael , Green Mattias , Stolzenberger Sophie
Published: March 2020

Analyses of water level measurements in the Gulf of Maine and Bay of Fundy suggest interannual changes in the tidal M2 amplitude of significant size (∼1–5 cm) and remarkable spatial coherence. These signals are of unknown origin and cannot be caused by the observed sea-level fluctuations of less than 10 cm. Here we use a regional ocean model setup to link interannual M2 variations to changes in stratification, which may alter the surface tide through processes of turbulent mixing and baroclinic wave scattering as the tide propagates into and across the gulf. We run short (20-day) simulations at 1/30° horizontal resolution, omit atmospheric forcing, and prescribe background temperature and salinity fields at annual intervals starting in 1993. Tidal velocities are introduced along with geostrophic currents at open boundaries and are not varied in between runs. M2 amplitudes inferred from these experiments exhibit a year-to-year variability of 1–2 cm throughout the Gulf of Maine, mostly reflecting the sign (but not always the magnitude) of measured amplitude changes at tide gauges Boston, Portland, and Eastport. In particular, we are able to reproduce the 3-cm drop in the M2 time series from 1993 to 1998 and the subsequent increase by 1.5 cm until the year 2000. Over the period 1993–2013 and at all three stations, our simulations explain 22–29% of the locally observed M2 variance, with linear correlations ranging from 50 to 56%. Although model sensitivities and the exact mechanisms underlying these signals are yet to be worked out, our study provides appreciable evidence that varying stratification may indeed be a significant driver for the gulf's tidal changes on interannual and perhaps secular time scales.
Quantum Absolute Sensors for Gravity Measurements
Authors: Merlet Sébastien , Piccon Raphael , Sarkar Sumit , Pereira Dos Santos Franck
Published: March 2020

Gravity measurements are performed with two different classes of instruments: gravimeters, most widely used, measure the gravity acceleration gand its variations, whereas gradiometers measure its gradient.

Quantum gravity sensors, based on cold atom interferometry techniques, can offer higher sensitivities and accuracies than current state of the art commercial available technologies. Their limits in performances, both in terms of accuracy and long term stability, are linked to the temperature of the atomic cloud, in the low µK range, and more specifically, to the residual ballistic expansion of the atomic sources in the laser beams. To overcome these limits, we use ultracold atoms in the nano-kelvin range in our sensors.

I will first present our Cold Atom Gravimeter (CAG) used for the determination of the Planck constant with the LNE Kibble Balance [1]. It performs continuously 3 gravity measurements per second with a demonstrated long term stability of 0.06 nano-gin 40 000 s of measurement. Using ultracold atoms produced by evaporative cooling in a crossed dipole trap as a source, its accuracy, which is still to be improved, is currently at the level of 2 nano-g. This makes our CAG, the more accurate gravimeter [2]. It detects water table level variations. Then I will describe a « dual sensor » which performs simultaneous measurements of g and its gradient. This offers in principle the possibility to resolve, by combining these two signals, the ambiguities in the determination of the positions and masses of the sources, offering new perspectives for applications. It uses cold atom sources for proof of principle demonstrations [3, 4] and will soon combine ultra-cold atomic samples produced by magnetic traps on a chip and large momentum beamsplitters. With these two key elements, the gradiometer will perform measurements in the sub-E sensitivity range in 1 s measurement time on the ground. Such a level of performances opens new prospects for on field and on board gravity mapping, for drift correction of inertial measurement units in navigation, for geophysics and for fundamental physics.

 References

[1] M. Thomas et al. Metrologia 54, 468-480 (2017)

[2] R. Karcher, et al. New J. Phys. 20, 113041 (2018)

[3] M. Langlois et al. Phys. Rev. A 96, 053624 (2017)

[4] R. Caldani et al. Phys. Rev. A 99, 033601 (2019)
Validating the French hYdrometeorological REanalysis (FYRE) with documentary evidence
Authors: Vidal Jean-Philippe , Devers Alexandre , Lauvernet Claire , Vannier Olivier , Caillouet Laurie , Sauquet Eric , Graff Benjamin
Published: March 2020

The recently developed French hYdrometerological Reanalysis (FYRE) covers the period 1871-2012 and provide high-resolution ensemble reconstructions of both climate and hydrology over France. FYRE Climate combines a statistical downscaling of the global Twentieth Century reanalysis (Caillouet et al., 2019) with in-situ station observations through Ensemble Kalman filter (EnKF) data assimilation (Devers et al., 2020). FYRE Climate is composed of 25 members of daily temperature and precipitation fields on a 8~km grid over France. It served as forcings for a conceptual hydrological model over 661 near-natural catchments to build streamflow reconstructions spanning 142 years. These reconstructions have then been combined with historical streamflow observations, again through EnKF data assimilation, to build the FYRE Hydro 25-member daily hydrological reanalysis over the 661 catchments.

FYRE Hydro is here validated with various types of documentary evidence (poem, complaint letter, and photograph), focusing on extreme low-flow events and their spatial and temporal fingerprint. They serve as examples of naturally extreme hydrological events that are exacerbated through human interventions, the magnitude of which has yet to be consistently quantified over the course of the Anthropocene.

 

References

Caillouet, L., Vidal, J.-P., Sauquet, E., Graff, B., Soubeyroux, J.-M. (2019) SCOPE Climate: a 142-year daily high-resolution ensemble meteorological reconstruction dataset over France. Earth System Science Data, 11, 241-260. https://doi.org./10.5194/essd-11-241-2019

Devers, A., Vidal, J.-P., Lauvernet, C., Graff, B., Vannier, O. (2020) A framework for high-resolution meteorological surface reanalysis through offline data assimilation in an ensemble of downscaled reconstructions. Quarterly Journal of the Royal Meteorological Society. https://doi.org./10.1002/qj.3663
Recent nitrate transport response to extreme weather conditions in the Bode lower-mountain range catchment, central Germany
Authors: Jomaa Seifeddine , Wachholz Alexander , Yang Xiaoqiang , Borchardt Dietrich , Rode Michael
Published: March 2020

There is mounting evidence that the extreme weather conditions, either droughts or floods, could likely be more frequent than what was thought before, resulting in increased impacts on our ecosystems. This study aims to investigate the effect of the extreme drought events that occurred in the period 2015-2019 on the nitrate-N concentrations and loads in the Bode catchment (3300 km2) located in the transition areas of central uplands and northern lowlands of Germany. To this, a combination of high-frequency (15 min data in the period 2011-2019) and long-term (1993-2010) of continuous discharge and biweekly nitrate-N records in five typical gauging stations, representing different landscape features and dominant-runoff components of the catchment, were utilized. In the period 2015-2019, mean annual precipitation decreased by about 10%, and mean temperature increased by 1.46 °C compared to the period 1969-2014. Results suggested no evident changes in nitrate-N concentrations and loads in the upper mountainous areas of the Bode catchment (mainly forest) and groundwater-dominated gauging station, reflecting no impact of the droughts on these two archetypical sub-catchments. However, results showed that the nitrate-N concentrations and loads declined significantly in the lowland, agriculture dominated areas of the Bode catchment. This can be explained by the reduction of nitrate-N contribution from the lower part of the catchment during the spring and summer periods. It seems that the drought-induced increased evapotranspiration and decreased precipitation resulted in the reduced runoff from lowland areas of the catchment, affecting the nitrate-N mixing of different N source areas within the catchment. These findings suggest that recent changes of temperature and precipitation unlikely change considerably nitrate-N dynamics in terms of yearly load, but significantly reduce nitrate-N concentrations during low-flow periods in summer.  
Eurasian cooling linked with Arctic warming: Insights from PV dynamics
Authors: Xie Yongkun , Wu Guoxiong , Liu Yimin
Published: March 2020

The three-dimensional connections between Eurasian cooling and Arctic warming since 1979 were investigated using potential vorticity (PV) dynamics. We found that Eurasian cooling can be regulated by Arctic warming through PV adaptation and PV advection. Here, PV adaptation refers to the adaptation of PV to forcing and coherent dynamic/thermodynamic adaptation to PV change. In a PV perspective, first, the anticyclonic circulation change over the Arctic is produced by a negative PV change through PV adaptation, in which the change means the linear trend from 1979~2017. The negative PV change is directly regulated by Arctic warming because the vertical structure of Arctic warming is stronger at lower levels, which generates a negative PV change through the diabatic heating effect. Second, the circulation change produces a change in horizontal PV advection due to the existence of climatological PV gradients. Thus, as a balanced result, both the circulation change and PV change extend to mid-latitude through horizontal PV advection and PV adaptation. Eventually, Eurasian cooling at the surface and in the lower troposphere is dominated by PV changes at the surface through PV adaptation. Meanwhile, enhanced Eurasian cooling in the middle troposphere is dominated by top-down influences of upper-level PV change through PV adaptation. Nevertheless, the upper-level PV changes are still contributed by horizontal PV advection associated with Arctic warming. Overall, the general dynamics connecting Eurasian cooling with Arctic warming is demonstrated in a PV view.
The emission and photochemistry of a large industrial facilities near megacities - a case study in South Korea
Authors: Kim Saewung , Mielnik Anne , Wong Gracie , Sarkar Chinmoy , Guenther Alex
Published: March 2020

In this presentation, we will discuss the top down emission estimates of SO2 and volatile organic compounds using mass spectrometers integrated on a research aircraft with a fast-meteorological sensor. The study area is four coal power plants, one steel mill, and one petrochemical industrial facility, located in the Tae-ahn Peninsular in South Korea 50 km away from the southern tip of the Seoul Metropolitan Area. We conducted 20 research flights to closely monitor emissions from each facility.  We will present detailed analysis of instantaneous emission rates to verify emission inventories to proceed their impacts to regional air quality, particularly towards the Seoul Metropolitan Area with a population of 25 millions, using a semi-Lagrangian photochemical box model.

 