bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical composition of the Moon's 'primary' crust – a clue at a terrestrial origin
Authors: Vorburger Audrey , Wurz Peter , Scherf Manuel , Lammer Helmut , Galli André , Assis Fernandes Vera
Published: March 2020

The Moon is one of the best characterized objects in space science, yet its origin still actively researched. Available orbital, geophysical, and geochemical information imposes clear restrictions on the origin and evolution of the Earth-Moon system (e.g., Canup 2008, 2012; Ćuk and Stewart 2012; Young et al. 2016). In regard to geochemical constraints, one of the most puzzling conundrums is posed by the similar isotopic fingerprints of the Earth and the Moon (e.g., Wiechert et al. 2001; Armytage et al. 2012; Zhang et al. 2012; Young et al. 2016; Schiller et al. 2018), together with the apparent lunar depletion in volatile elements (e.g., Ringwood and Kesson 1977; Wanke et al. 1977; Albarède et al. 2015; Taylor 2014). This apparent lunar volatile depletion is most notable in the low K content in comparison to U, a finding based on chemical analyses of samples collected from the lunar surface and lunar meteorites, and on spectroscopic observations of the lunar near-surface, despite both having been heavily processed in the past ~ 4.4 billion years.

In the past 4.4 billion years, space has been a harsh environment for our Moon, especially in the beginning, when the young Sun was still very active and the young Moon was continuously bombarded by meteorites of varying sizes. Solar wind and micro-meteoritic interactions with the lunar surface led to rapid and intensive processing of the lunar crust. Hence, the K/U depletion trend observable on today's lunar surface does not necessarily reflect a K/U ratio valid for the Moon in its entirety. We model the evolution of the abundances of the major elements over the past 4.3 to 4.4 billion years to derive the composition of the original lunar crust. Accounting for this processing, our model results show that the original crust is much less depleted in volatiles than the surface observable today, exhibiting a K/U ratio compatible with Earth and the other terrestrial planets, which strengthens the theory of a terrestrial origin for the Moon.
Eoarchean to Paleoproterozoic crustal evolution in the North China Craton
Authors: Ma Qiang , Xu Yi-Gang , Huang Xiao-Long , Zheng Jian-Ping
Published: March 2020

The early evolution of continental crust, particularly its lower layer, during the first 2.0 billion years of Earth history remains enigmatic. Here, we present the first coupled in-situ U-Pb, Lu-Hf and O isotope data for the Precambrian zircons from fourteen deep-crustal xenoliths from five localities in the North China craton. The results show that: (1) the oldest (3.82−3.55 Ga) known lower crustal rocks were survived in the southern part of this craton; (2) the Eo-Paleoarchean zircons have predominant sub-chondritic Hf isotope compositions and elevated δ18O values, suggesting Lu-Hf fractionation and crust-hydrosphere interactions on the Earth can be traced back to Eoarchean or even earlier; (3) a secular change in zircon O isotopes documents an increase in recycling rate of surface-derived materials into magmas at the end of Archean, which, in turn, is possibly linked to modern style subduction processes and maturation of the crust at that time.
Contribution of magnetite (U-Th-Sm)/He thermometer to quantify the final exhumation of high-pressure ultramafic rocks : example of the Rocher Blanc ophiolite (western Alps)
Authors: Schwartz Stéphane , Gautheron Cécile , Ketcham Richard A , Brunet Fabrice , Agranier Arnaud , Corre Marianna
Published: March 2020

This contribution investigates the use of the (U-Th-Sm)/He dating method to unravel the exhumation history of ultramafic ophiolite rocks. Magnetite-bearing rocks are widely distributed on the Earth's surface and are associated with a large range of geological and geodynamic settings. However, little is known of the crystallization and exhumation history of in case of oceanic accretion to orogenic zones, due to a lack of datable minerals. In the past few years, the (U-Th-Sm)/He method applied on magnetite or spinel appears to be very relevant and promising. However, the applicability of this method to access the thermal history has never been quantitatively investigated, limiting the age interpretation. To highlight the applicability and to access geological information using magnetite (U-Th-Sm)/He method (MgHe), we applied it on a well-known high-pressure low-temperature alpine ophiolite (Rocher Blanc ophiolite, Western Alps) where the P-T-t exhumation history is well constrained. A study of magnetite petrology, mineralogy and geochemistry has allowed us to characterize that magnetite crystallize at T>250°C. MgHe ages that range between apatite and zircon fission track (AFT and ZFT) ages of surrounding rocks in agreement with the known thermal sensitivity of those methods. MgHe data were co-inverted with AFT and ZFT data to determine the most robust thermal history associated with the ophiolite cooling. This first MgHe age inversion is consistent with experimental He diffusion data, opening the use of MgHe as a thermochronometer. This result allows us to refine the thermal history and to precise the geodynamical context associated to the final exhumation of this alpine ophiolite.
Characterization of the Pc5 frequency range power spectrum at low latitude in 22 years of geomagnetic field observations.
Authors: Colonico Alessandro , Di Matteo Simone , Villante Umberto
Published: March 2020

An important aspect of the interaction between the solar wind (SW) and the Earth’s magnetosphere concerns the possible relationship between SW and magnetospheric fluctuations under different SW conditions. In recent investigations (Di Matteo and Villante, 2017,2018) we revealed the critical role of the analytical methods and the spectral analysis techniques in the identification of fluctuations between ≈1-5 mHz in the SW parameters as well as in the magnetospheric field measurements at the geostationary orbit and developed a new approach, based on the joint use of the Welch and the Multitaper methods, for a more robust identification of these oscillations in both regions. Here, we extend the analysis to ground measurements, analyzing 22 years of magnetic field measurements along the H and D components at low latitude (L’Aquila, Italy, λ≈36.3°, L≈1.6). We found that, in general, the much steeper spectrum of the geomagnetic fluctuations with respect to the ones estimated in the SW parameters and magnetospheric field, might deeply influence the identification of real events. We then examined, for the entire period, consecutive two hours intervals through the day during low geomagnetic activity conditions (Dst>-50), and, for each interval, we carefully evaluated the characteristics of the background spectrum. As a matter of fact, in the ≈1-5 mHz frequency range the spectral indices of both components typically range between -3.5 and -2 with a steeper spectrum in the night sector when the fluctuations power is lower. Simulations of red noise representations, with spectral indices similar to the observed ones, combined with the Sq variation show a systematic reduction of the rate of identification of real events up to ≈2 mHz.

Ref.

Di Matteo, S., and U. Villante, J. Geophys.Res. Space Physics, 122, 4905–4920, doi:10.1002/2017JA023936.

Di Matteo, S., and U. Villante, Journal of Geophysical Research: Space Physics, 123, doi.org/10.1002/2017JA024922.
Combination of satellite SAR and GNSS data of co-seismic deformation after the November 26, 2019 Albania earthquake: first results
Authors: Grassi Francesca , Cenni Nicola , Mancini Francesco
Published: March 2020

The November 26, 2019 a Mw 6.2 earthquake struck the city of Durres as well as several towns in the Northwestern of Albania. The event killed 51 people, injured more than 900 and destroyed several buildings in the epicentral area. This area is dominated by active thrust tectonics due to the collision between Adriatic and Eurasian plates. This study shows the first results about the co-seismic displacements field estimated by the analysis of satellite SAR and GNSS data. In particular, GNSS observations were acquired by a network of 18 continuous GNSS stations located in the Albanian area. Using the GAMIT/GLOBK, GNSS data were processed within a time period ranging from January 1, 2016 to December 31, 2019 and time series produced. Moreover, a number of ascending and descending radar images acquired by the Sentinel-1 satellite in the period of the seismic event were processed using the ESA SNAP software. Pre-seismic, co-seismic and post-seismic interferograms provided the LOS displacement maps of the event and characterized the main deformation phenomena produced by such an event. The first preliminary results about the co-seismic displacements will be presented and compared with some theoretical co-seismic displacement fields provided thanks to the knowledge of the fault system affecting the area.
NH-GOMO, an efficient and easily portable non-hydrostatic ocean model
Authors: Tang Qiang , Huang Xiaomeng , Huang Xing
Published: March 2020

Numerical simulation of nonlinear gravity internal waves with non-hydrostatic ocean models, especially these which using the terrain-following sigma-coordinate, is challenging. The expensive computation cost, which is caused by the dynamic pressure Poisson solver in cases using fine grid resolution in both directions (horizontal and vertical), is the main reason. A non-hydrostatic ocean model named NH-GOMO is constructed based on a partially implicit finite difference scheme for the dynamic pressure and adopts an idea of “decimation and interpolation”. A significant optimization for the pressure Poisson solver, which brings no obvious accuracy loss, is obtained with these technologies. The automatic parallel operator library named OpenArray is used as the bottom layer of this model and make it easy to transport between different computing platforms. Accuracy and efficiency have been validated by several ideal test cases.
Presence of cavity resonances in the inner magnetosphere
Authors: Laakso Harri
Published: March 2020

In the inner magnetosphere there are sharp plasma boundaries that can cause resonance cavities. The four Cluster satellites move in a string-of-pearls configuration at perigee (at L=4-5) so that they are spatially well separated but their separation is still short that at least some of them are simultaneously at different positions inside the cavity. In the presence of cavity resonance of a half wavelength, all spacecraft inside the cavity observe the same wave mode in the same phase. In this talk we analyze and present a number of cavity resonances observed by the Cluster spacecraft. Typical observed mode frequencies are between 4 - 14 mHz, depending on the size of the cavity. It appears that the occurrence of cavity resonances is well correlated with changes in geomagnetic activity and they are quite common. They tend to occur at 12-16 MLT and 21-23 MLT. These ULF waves may have a significant impact on radiation belt particles as they cover a large L shell range.
Effects of multi-time scales drought on vegetation dynamics in Qaidam River Basin, Qinghai-Tibet Plateau from 1998 to 2015
Authors: Sun Yongxiu , Liu Shiliang , Dong Yuhong , Dong Shikui , Shi Fangning
Published: March 2020

Quantifying drought variations at multi-time scales is important to assess the potential impacts of climate change on terrestrial ecosystems, especially vulnerable desert grassland. Based on the Normalized Difference Vegetation Index (NDVI) and Standardized Precipitation Evapotranspiration Index (SPEI), we assessed the influences of different time-scales drought (SPEI-3, SPEI-6, SPEI-12, SPEI-24, and SPEI-48 with 3, 6, 12, 24 and 48 months, respectively) on vegetation dynamics in the Qaidam River Basin, Qinghai-Tibet Plateau. Results showed that: (1) Temporally, annual and summer NDVI increased, while spring and autumn NDVI decreased from 1998 to 2015. Annual, spring and summer SPEI increased and autumn SPEI decreased. (2) Spatially, annual, spring, summer, and autumn NDVI increased in the periphery of the Basin, with 45.98%, 22.68%, 43.90%  and 30.80% of the study area, respectively. SPEI showed a reverse variation pattern with NDVI, with an obvious decreasing trend from southeast to northwest. (3) Annual vegetation growth in most areas (69.53%, 77.33%, 86.36%, 90.19% and 85.44%) was correlated with drought at all time-scales during 1998-2015. However, high spatial and seasonal differences occurred among different time-scales, with the maximum influence in summer under SPEI24. (4) From month to annual scales, NDVI of all land cover types showed higher correlation to long-term drought of SPEI24 or SPEI48. Vegetation condition index (VCI) and SPEI were positively correlated at all time-scales and had a more obvious response in summer. The highest correlation was VCI of grassland (June-July) or forest (April-May, August-October) and SPEI48. This study contributes to exploring the effect of drought on vegetation dynamics at different time scales, further providing credible guidance for regional water resources management.
Estimation of Forest Fire Risk by Using Fire Weather Index in the MENA Region
Authors: Calda Burcu , Collu Kamil , Pacal Aytac , Kurnaz Mehmet Levent
Published: March 2020

Forest fires are naturals in the Mediterranean ecosystems. However, in the last decade, the number of wildfires has significantly increased in the Mediterranean basin along with climate change. Therefore, forecasts of this region by using fire indices are crucial to take necessary precautions. In the present study, the projected changes for the period 2070 - 2099 concerning the control period 1971 - 2000 were used to estimate forest fire risk by the Canadian Fire Weather Index (FWI). RCP4.5 and RCP8.5 emission scenarios (IPCC) outputs of MPI-ESM-MR and HadGEM2-ES dynamically downscaled to 50 km for the CORDEX-MENA domain with the use of the RegCM4 were utilized. ERA-Interim observational data from ECMWF covering the period 1980-2012 were also used to test the performances of models. The output of MPI-ESM-MR gave more similar fire risk prediction with the reforecast of observational data (ERA-Interim). Thus, the MPI-ESM-MR model could be more suitable to estimate fire risk by FWI. According to future projection, forest fire risk will significantly increase throughout the region for the last 30 years of this century.
GIS based Development of MCDM Model for Flood Risk Management across Godavari Lower Sub-Basin of India
Authors: Gurusamy B. Thanga , Vasudeo Avinash D , Ghare Aniruddha Dattatraya
Published: March 2020

Abstract: Because of the uncertainty and high cost involved, the Absolute Flood Protection has not been considered as a rational decision. Hence the trend is to replace Absolute Flood Protection strategy by Flood Risk Management Strategy. This Paper focus on the development of Multiple Criteria Decision Making (MCDM) model towards Flood Risk Management (FRM) across Godavari Lower Sub-Basin of India using GIS based methodologies for Flood Hazard Zonation in order to achieve global minimum of the Flood predicted Risk level.  Flood Hazard Zone Map for the historical flood events obtained with the use of GIS based Digital Elevation Models across the study area have been presented and used for the estimation of Hazard Risk. Uncertainty (or Control) Risk levels of each Flood estimated using various Flood Forecasting methodologies have been compared for the selected locations of the study area. Effectiveness of Passive Flood Protection Measures in the form of Flood Levees has been quantitatively analyzed for the increase in the Opportunity Risk and corresponding reduction in the Flood Hazard Risk. Various types of Multi-Objective Evolutionary Algorithms (MOEAs) have been used  to determine a Compromise solution with conflicting criteria between Hazard Risk and Opportunity (or Investment) Risk and the results were compared for each of the selected levels of Flood estimated with corresponding uncertainty. Traditional optimization method in the form of Pareto-Optimal Front have also been graphically depicted for the minimization of both Hazard Risk Objective function and Opportunity Risk Objective Function and compared with those obtained using MOEAs. Watershed wise distribution of optimized Flood Risk variation across the Sub-basin has been presented graphically for both the cases of with and without active Flood Routing Measures. Keywords:  Flood Risk Management; GIS based Flood Hazard Zonation; Multi-Criteria Decision Making; Multi-Objective Evolutionary Algorithms; Godavari Lower Sub-Basin of India;
Breaking a single-plate Earth into a global plate network
Authors: Tang Chun’an , Webb Alex G. , Moore William B. , Wang Yongyi , Ma Tianhui , Chen Tiantian
Published: March 2020

Fifty years after the main discovery period for plate tectonics, we still lack a consensus understanding of a critical question: how did the plate tectonic system initiate? For the period before initiation of plate tectonics, models increasingly call upon a stagnant lid (i.e., a single-plate lithosphere) atop a mantle which was hotter by a few hundred degrees than the present mantle. How was this lid first broken into plates? Various hypotheses suggest that the strength of the lid was overcome by (a) mantle convective forcing, potentially along locally pre-weakened zones, (b) lithospheric gravitational instabilities between oceanic lithosphere and either adjacent oceanic plateau lithosphere or adjacent overthickened (i.e., gravitationally collapsing) continental lithosphere, or (c) one or more large bolides. These models have not converged on a mechanism or a typical early plate scale. Here, we use a new solid-mechanics based approach to the problem of the origin of plate tectonics and the processes by which plate boundaries are initiated. Specifically, we employ 3D spherical shell models of a brittle lithosphere via the three-dimensional finite element code RFPA (Rock Failure Process Analysis code). The models are subjected to quasi-static, slowly increasing interior pressure in a displacement-controlled manner (e.g., induced by gradual thermal expansion). Brittle failure is implemented through a strength criterion representing a stress limit at which the strength drops and fracture occurs. To account for local randomness, each element is assigned a failure threshold obtained from a Weibull probability distribution which contains a parameter describing the degree of material homogeneity. Globe-spanning rifting occurs as a consequence of horizontal extension. Resultant fracture spacing is a function of lithospheric thickness and rheology, such that geometrically-regular, polygonal-shaped tessellation is energetically favored because it minimizes total crack length. Therefore, anticipated warming of the early lithosphere itself (as lithospheric chilling from downwards advection due to rapid volcanism wanes) should lead to failure, propagating fractures, and the conditions necessary for the onset of multi-plate tectonics.
Field scale root zone soil moisture estimation by coupling cosmic-ray neutron sensor with soil moisture sensors
Authors: Said Hami , Weltin Georg , Heng Lee Kheng , Franz Trenton , Fulajtar Emil , Dercon Gerd
Published: March 2020

Since it has become clear that climate change is having a major impact on water availability for agriculture and crop productivity, an accurate estimation of field-scale root-zone soil moisture (RZSM) is essential for improved agricultural water management. The Cosmic Ray Neutron Sensor (CRNS) has recently been used for field-scale soil moisture (SM) monitoring in large areas and is a credible and robust technique. Like other remote or proximal sensing techniques, the CRNS provides only SM data in the near surface. One of the challenges and needs is to extend the vertical footprint of the CRNS to the root zone of major crops. This can be achieved by coupling the CRNS measurements with conventional methods for soil moisture measurements, which provide information on soil moisture for whole rooting depth.

The objective of this poster presentation is to estimate field-scale RZSM by correlating the CRNS information with that from soil moisture sensors that provide soil moisture data for the whole root depth. In this study, the Drill and Drop probes which provide continuous profile soil moisture were selected. The RZSM estimate was calculated using an exponential filter approach.

Winter Wheat cropped fields in Rutzendorf, Marchfeld region (Austria) were instrumented with a CRNS and Drill & Drop probes. An exponential filter approach was applied on the CRNS and Drill and drop sensor data to characterize the RZSM. The preliminary results indicate the ability of the merging framework procedure to improve field-scale RZSM in real-time. This study demonstrated how to combine the advantages of CRNS nuclear technique (especially the large footprint and good representativeness of obtained data) with the advantages of conventional methods (providing data for whole soil profile) and overcome the shortcoming of both methods (the lack of information in the deeper part of soil profile being the major disadvantage of CRNS and the spatial limitation and low representativeness of point data being the major disadvantage of conventional capacitance sensors). This approach can be very helpful for improving agricultural water management.
Ecohydrological Behaviour of Mountain Beech Forest: Quantification of Stomatal Conductance Using Sap Flow Measurements
Authors: Su Ye , shao Wei , Vlček Lukáš , Langhammer Jakub
Published: March 2020

In forested regions, transpiration as the main component of evaporation fluxes is important for evaporation partitioning. Physiological behaviors among various vegetation species are quite different. Thus, an accurate estimation of the transpiration rate from a certain tree species needs specific parameterization of stomatal response to multiple environmental conditions. In this study, we chose a 300-m2 beech forest plot located in Vydra basin, the Czech Republic, to investigate the transpiration of beech (Fagus sylvatica) from the middle of the vegetative period to the beginning of the deciduous period, covering 100 days. The study area experienced bark beetle infestation, and the trees are newly formed, and mixed forest stands (spruce and beech) have transformed into beech stands. From the differences in the rooting depth of each kind of tree, an impact on the long-term water regime is expected. Furthermore, trees can change soil moisture distribution or water storage in aquifers by transpiration. Therefore, the sap flow equipment was installed in six trees with varying ages among 32 beech trees in the plot, and the measurements were used to infer the stomatal conductance for the beech forest. The diurnal pattern of stomatal conductance and the response of stomatal conductance under the multiple environmental conditions were analyzed. The results showed that the stomatal conductance inferred from sap flow reached the highest at midday but, on some days, there was a significant drop at midday, which might be attributed to the limits of the hydraulic potential of leaves (trees). The response of stomatal conductance showed no pattern with solar radiation and soil moisture, but it did show a clear correlation with the vapor deficit, in particular when explaining the midday drop. The relation to temperature was rather scattered as the measured period was in the moderate climate. The findings highlighted that the parametrization of stress functions based on the typical deciduous forest does not perfectly represent the measured stomatal response of beech. Therefore, measurements of sap flow can assist in better understanding transpiration in newly formed beech stands after bark beetle outbreaks in Central Europe.

Keywords: Transpiration; beech forest; stomatal conductance; sap flow measurement
Multimodal Imaging of Plant-Soil Interaction for Better and More Predictive Modelling of Rhizosphere Processes
Authors: Roose Tiina , Ruiz Siul , McKay Fletcher Dan , Williams Katy , Petroselli Chiara , Scotson Callum , van Veelen Arjen
Published: March 2020

We rely on soil to support the crops on which we depend. Less obviously we also rely on soil for a host of 'free services' from which we benefit. For example, soil buffers the hydrological system greatly reducing the risk of flooding after heavy rain; soil contains very large quantities of carbon, which would otherwise be released into the atmosphere where it would contribute to climate change. Given its importance it is not surprising that soil, especially its interaction with plant roots, has been a focus of many researchers. However the complex and opaque nature of soil has always made it a difficult medium to study.

In this talk I will show how we can build a state of the art image based model of the physical and chemical properties of soil and soil-root interactions, i.e., a quantitative, model of the rhizosphere based on fundamental scientific laws.
This will be realised by a combination of innovative, data rich fusion of structural and chemical imaging methods, integration of experimental efforts to both support and challenge modelling capabilities at the scale of underpinning bio-physical processes, and application of mathematically sound homogenisation/scale-up techniques to translate knowledge from rhizosphere to field scale. The specific science questions I will address with these

techniques are: (1) how does the soil around the root, the rhizosphere, function and influence the soil ecosystems at multiple scales, (2) what is the role of root- soil interface micro morphology on plant nutrient uptake, (3) what is the effect of plant exuded mucilage on the soil morphology, mechanics and resulting field and ecosystem scale soil function and (4) how to translate this knowledge from the single root scale to root system, field and ecosystem scale in order to predict how the climate change, different soil management strategies and plant breeding will influence the soil fertility.
Future Electrostatic Accelerometer without Polarization Wire
Authors: Boulanger Damien , Christophe Bruno , Rodrigues Manuel , Liorzou Françoise , Lebat Vincent , Dalin Marine , Huynh Phuong-Anh
Published: March 2020

ONERA (the French Aerospace Lab) is developing, manufacturing and testing ultra-sensitive electrostatic accelerometer for space application. Accelerometers have been successfully developed for the Earth-orbiting gravity missions CHAMP, GRACE, GOCE and GRACE-FO and for Earth-orbiting Fundamental Physics mission MICROSCOPE.

In ONERA accelerometer design, the proof mass was levitated and was maintained at the center of an electrode cage by electrostatic forces. Moreover this proof mass was connected by a thin conductive wire (typically 5, 7 or 10 µm diameter wire). This wire allows us to polarize the proof mass and to evacuate the random charges induced by space radiation.

By removing this polarization wire, there will be positive impacts on the accelerometer defaults such as the removal of the parasitic dumping noise at low frequencies created by wire or its bias contribution; but it is important to verify that there are not also negative impacts such as noisy charging process.

After studying the evolution of the space radiation energy distribution on interesting orbits for earth missions, an evaluation of implemented current on the proof mass has been performed. A UV LED had been tested; the set-up and first measurements will be presented. Moreover a prototype is developed by ONERA to characterized charge management capabilities of such a system on a representative environment.
Movements of thick evaporites on the flanks of a mid-ocean ridge: the central Red Sea Miocene evaporites
Authors: Mitchell Neil , Shi Wen , Izzeldin Ay , Stewart Ian
Published: March 2020

Thick evaporites ("salt") were deposited in the South and North Atlantic, and Gulf of Mexico basins, in some parts deposited onto the flanks of nascent oceanic spreading centres.  Unfortunately, knowledge of the history of evaporite movements is complicated in such places by their inaccessibility and subsequent diapirism.  This is less of a problem in the Red Sea, a young rift basin that is transitioning to an ocean basin and where the evaporites are less affected by diapirism.  In this study, we explore the vertical movements of the evaporite surface imaged with deep seismic profiling.  The evaporites have moved towards the spreading axis of the basin during and after their deposition, which ended at the 5.3 Ma Miocene-Pliocene boundary.  We quantify the evaporite surface deflation needed to balance the volume of evaporites overflowing oceanic crust of 5.3 Ma age, thermal subsidence of the lithosphere and loss of halite through pore water diffusion, allowing for isostatic effects.  The reconstructed evaporite surface lies within the range of estimated global sea level towards the end of the Miocene.  Therefore, the evaporites appear to have filled the basin almost completely at the end of the Miocene.  Effects of shunting by terrigenous sediments and carbonates near the coast and contributions of hydrothermal salt are too small to be resolved by this reconstruction.
Phosphate supply to the eutrophic lake Eichbaumsee (Germany): Sedimentary versus groundwater sources
Authors: Scholten Jan , Förster Wiebe , Schubert Michael , Knöller Kay , Classen Nikolaus , Lechelt Michael , Richard Jan-Helge , Rohweder Udo , Zunker Isabell
Published: March 2020

The eutrophic lake Eichbaumsee, a ~ 1 km long and 280m wide (maximum water depth 16m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e. aeration plants, removal of dissolved phosphate by aluminium phosphate precipitation and by Benthophos adsorption) during the past ~ 15 years. Despite these treatments no long-term improvement of the water quality was observed and the lake water phosphate content continued to increase by e.g. ~ 350 kg phosphate per year between March 2016 and February 2019. As no creeks or rivers drain into the lake and hydrological groundwater models do not suggest any major groundwater discharge into the lake, sources of phosphate (and other nutrients) are unknown.

We investigated the phosphate fluxes from sediment pore water and groundwater into the water body of the lake. Sediment pore water was extracted from sediment cores recovered by divers in August 2018 and February 2019. Diffusive phosphate fluxes from pore water were calculated based on phosphate gradients using first Fick`s law. Stable water isotopes (δ2H, δ18O) were measured in the lake water, sediment pore water, interstitial waters in the banks surrounding the lake, the Elbe river and in three groundwater wells close to lake. Stable isotope (δ2H, δ18O) water mass balance models were used to compute water inflow/outflow to/from the lake.

Our results revealed pore-water borne phosphate fluxes between – 0.07 mg/m²/d (i.e. slight phosphate uptake by the sediments) and 2.6 mg/m²/d (i.e. phosphate release to the lake). Assuming that the measured phosphate fluxes are temporarily and spatially representative for the whole lake, about 100 kg/a to 220 kg/a of phosphate is released from sediments. This amount is slightly lower than the observed phosphate increase of the lake water. Stable isotope signatures indicate a water exchange between the aquifer and the lake water. Based on stable isotope mass balances (δ2H, δ18O) we estimate an inflow of phosphate from the aquifer to the lake between 190 kg/a and 1400 kg/a. This inflow indicates that groundwater-born phosphate is as or even more important than phosphate supply via sediment pore-water. Our study suggests that groundwater may have an important impact on lake nutrient budgets.
Application of nighttime fog detection method using MSG8 SEVIRI in an arid environment
Authors: Weston Michael , Temimi Marouane
Published: March 2020

The detection of fog and low cloud (FLC) from satellite data remains challenging despite advances in methodologies and technology. Current methods make use of one or a combination of channel differencing from satellite instruments, surface observations, model data or artificial intelligence. An alternative to the brightness temperature difference method was developed for the GOES-R advanced baseline imager (ABI) which makes use of a channel ratio instead of a channel difference. We apply this method, the so called pseudo emissivity of the 3.9 µm channel, to SEVIRI MSG8 data over the United Arab Emirates, a desert region of the Arabian Peninsula. Low cloud is removed using temperature difference between ERA5 land surface temperature and 10.8 µm channel brightness temperature. Visual inspection of the final fog only mask shows that this method works well over this region. Verification at three sites where METAR data is available returned POD (FAR) of 0.77 (0.27), 0.50 (0.65) and 0.83 (0.26) respectively. Application of this method can be further developed to represent seasonal fog distribution and frequency across the United Arab Emirates.
Thermal and porosity properties of meteorites: A compilation of published data and new measurements
Authors: Soini Assi-Johanna , Kukkonen Ilmo , Kohout Tomas , Luttinen Arto
Published: March 2020

We report direct measurements of thermal diffusivity and conductivity at room temperature for 38 meteorite samples of 36 different meteorites including mostly chondrites, and thus almost triple the number of meteorites for which thermal conductivity is directly measured. Additionally, we measured porosity for 34 of these samples. Thermal properties were measured using optical infrared scanning method on samples of cm-sizes with a flat, sawn surface.

    A database compiled from our measurements and literature data suggests that thermal diffusivities and conductivities at room temperature vary largely among samples even of the same petrologic and chemical type and overlap among e.g. different ordinary chondrite classes. Measured conductivities of ordinary chondrites vary from 0.4 to 5.1 W/m/K. On average, enstatite chondrites show much higher values (2.33 – 5.51 W/m/K) and carbonaceous chondrites lower values (0.5 – 2.55 W/m/K).

    Mineral composition (silicates vs. iron-nickel) and porosity control conductivity. Porosity shows (linear) negative correlation with conductivity. Variable conductivity is attributed to heterogeneity in mineral composition and porosity by intragranular and intergranular voids and cracks, which are important in the scale of typical meteorite samples. The effect of porosity may be even more significant for thermal properties than that of the metal content in chondrites.

 

Reference

Soini A.-J., Kukkonen I. T., Kohout T., and Luttinen A. (accepted for publication). Thermal and porosity properties of meteorites: A compilation of published data and new measurements. Meteoritics & Planetary Science.
A Google Earth Engine application for mapping volcanic thermal anomalies at a global scale by means of Sentinel 2 MSI and Landsat 8 OLI data
Authors: Genzano Nicola , Marchese Francesco , Falconieri Alfredo , Mazzeo Giuseppe , Pergola Nicola
Published: March 2020

NHI (Normalized Hotspot Indices) is an original multichannel algorithm recently developed for mapping volcanic thermal anomalies in daylight conditions by means of infrared Sentinel 2 MSI and Landsat 8 OLI data. The algorithm, which uses two normalized indices analyzing SWIR (Shortwave Infrared) and NIR (Near Infrared) radiances, was tested with success in different volcanic areas, assessing results by means of independent ground and satellite-based observations.

Here we present and describe the NHI-based tool, which exploits the high computation capabilities of Google Earth Engine to perform the rapid mapping of hot volcanic features at a global scale. The tool allows the users to retrieve information also about changes of thermal volcanic activity, giving the opportunity of performing time series analysis of hotspot pixel number and total SWIR radiance. Advantages of using the NHI tool as a complement to current satellite-based volcanoes monitoring systems are then analysed and discussed, such as its future upgrades.
Heat flux measurements at Teide Volcano, Tenerife, Canary Islands, by means of thermal imaging
Authors: Montañez Hernández Ana Carolina , Marotta Enrica , Padilla Germán D. , Peluso Rosario , Hernández Pedro A. , Prieto Alberto , Morales González Francisco Airam , Domínguez Vidal , Barrancos Martínez José , Peréz Nemesio M. , D'Auria Luca
Published: March 2020

Nowadays, scientific surveys to evaluate the thermal energy release from volcanoes are very tedious and involve performing numerous measure points to determine the heat flux of a specific area. This study tests a new method to calculate the heat flux from Teide inner crater using thermal images without the need for on-site heat flow campaigns. So far, panoramic infrared images of the study area and infrared images of thermal anomaly zones at a distance of 1 meter have been carried out in a monthly basis with a FLIR T660 thermal camera. Soil temperature of study area was also measured with a K-type thermocouple in order to compare the results between the temperature measured with the thermocouple and the one obtained by the thermal camera. The method developed in Marotta et al. 2019 to determine the heat flux from thermal images will be adapted to the peculiarities of the Teide stratovolcano, such as the topography of the inner crater. To check the reliability of the method, values obtained with a heat flux sensor, by means of the temperature gradient and those resulting from the application of the developed method are compared. Finally, the error associated to the use of thermography at a greater distance to calculate heat flux is analysed by comparing the results obtained when applying the method with thermographic images taken at 1 meter with the results obtained when applying it with the panoramic thermal images of the crater, taken at approximately 50 metres.
Effects of Grass and Forests and the Infiltration Amount on Preferential Flow in Karst Regions of China
Authors: Kan Xiaoqing , Cheng Jinhua
Published: March 2020

  Preferential flow is an important water infiltration phenomenon in karst regions because it can quickly transport surface water to deep soil and increases available water for underground root growth. The response of preferential flow to vegetation restoration requires urgent investigation due to the special soil structure of karst regions. In order to study the effect of vegetation restoration on water movement in karst regions, four kinds of ponded water infiltration experiments were carried out in Pinus Yunnanensis plantation forestland, secondary forestland, and natural grassland. A brilliant blue dyeing experiment was conducted to visualize the distribution of water infiltration in soil (a total of 150 stained images from vertical soil slices). Results showed that the average depth of matrix flow in natural grassland was approximately six times those in plantation and secondary forestlands. An increase in matrix flow will have a negative effect on the development of preferential flow. Water transported in preferential flow paths affects the distribution of nutrients and organic matter in the soil. However, preferential flow in grassland can promote the accumulation of available nutrients, and preferential flow in plantations can inhibit the loss of organic matter. Preferential flow in grasslands and forest plantations is less than that in native forests soils. The results of SEM showed that preferential flow increases the percolation of water in soils. The effect is that preferential flow can obstructs water uptake by the roots under low rainfall conditions, and decreases surface runoff before soil saturation under high rainfall conditions. In the process of nutrient element migration, preferential flow has a good contribution, which is conducive to the migration and accumulation of elements required for surface vegetation growth. The contribution of preferential flow needs to be considered in studies on vegetation restoration planning and land degradation. Reasonable allocation of plantation forests has a certain mitigation effect on soil erosion in Karst areas, and preferential flow under this special geomorphological type is worth studying. Preferential flow can transport nutrients to deeper soil for roots according to the data of this study. Therefore, plantation is feasible under karst landform conditions, but it is better to combine herbaceous plants in a plantation. The results could provide suggestions for the restoration of rocky desertification and the advantages or disadvantages of vegetation restoration engineering in karst areas.
StratigrapheR: making and using lithologs in R
Authors: Devleeschouwer Xavier , Da Silva Anne-Christine , Boulvain Frédéric , Wouters Sébastien
Published: March 2020

StratigrapheR is an open-source integrated stratigraphy package. It is available in the free software environment R (https://CRAN.R-project.org/package=StratigrapheR) and is designed to generate lithologs in a semi-automated way, to process stratigraphical information, and to visualize any plot along the lithologs in the R environment.

The basic graphical principle behind StratigrapheR is the incremental addition of elements to a drawing: a plot is opened, and graphical elements are successively added. This allows compartmentalisation of the drawing process, as well as the superposition of different plots for comparison. For instance a litholog of a single section can be written as a single function including all the drawing sub-functions, and be integrated in a larger plot, for instance to be correlated to other sections or to show proxy data.

The StratigrapheR package is designed for efficient work, and minimum coding, while still allowing versatility. The lithological information of beds (upper and lower boundary, hardness, lithology, etc.) is converted into polygons. All polygons are drawn together using a single function, and each polygon can have its personalised symbology allowing to distinguish lithologies. A similar workflow can be used for plotting proxies while distinguishing each sample by their lithology. Vector graphics can be imported as SVG files, and precisely drawn with the lithologs to serve as symbols or complex elements. Every type of symbol is plotted by calling one single function which repeats the drawing for each occurrence of the represented feature. This illustrates that the amount of work invested to make lithologs using StratigrapheR is related to their complexity rather than their length: a long but monotonous litholog (e.g. of marl-limestone alternations) only takes a few lines of code to generate.

The StratigrapheR package also provides a set of functions to deal with selected stratigraphic intervals (for instance in the [0,1[ form): they allow simplification, merging, inversion and visualisation of intervals, as well as identifying the samples included in the given intervals, and characterising the relation of the intervals with each other (overlap, neighbouring, etc.). StratigrapheR includes PDF and SVG generation of plots, of any dimension. The generated PDF can even store multiple plots in a single file (each plot on a different page) to document data processing comprehensively.
A bayesian hierarchical model to predict spatio-temporal variability in river water quality at 102 catchments
Authors: Guo Danlu , Lintern Anna , Webb Angus , Ryu Dongryeol , Bende-Michl Ulrike , Liu Shuci , Western Andrew
Published: March 2020

Our current capacity to model stream water quality is limited particularly at large spatial scales across multiple catchments. To address this, we developed a Bayesian hierarchical statistical model to simulate the spatio-temporal variability in stream water quality across the state of Victoria, Australia. The model was developed using monthly water quality monitoring data over 21 years, across 102 catchments, which span over 130,000 km2. The modelling focused on six key water quality constituents: total suspended solids (TSS), total phosphorus (TP), filterable reactive phosphorus (FRP), total Kjeldahl nitrogen (TKN), nitrate-nitrite (NOx), and electrical conductivity (EC). The model structure was informed by knowledge of the key factors driving water quality variation, which had been identified in two preceding studies using the same dataset. Apart from FRP, which is hardly explainable (19.9%), the model explains 38.2% (NOx) to 88.6% (EC) of total spatio-temporal variability in water quality. Across constituents, the model generally captures over half of the observed spatial variability; temporal variability remains largely unexplained across all catchments, while long-term trends are well captured. The model is best used to predict proportional changes in water quality in a Box-Cox transformed scale, but can have substantial bias if used to predict absolute values for high concentrations. This model can assist catchment management by (1) identifying hot-spots and hot moments for waterway pollution; (2) predicting effects of catchment changes on water quality e.g. urbanization or forestation; and (3) identifying and explaining major water quality trends and changes. Further model improvements should focus on: (1) alternative statistical model structures to improve fitting for truncated data, for constituents where a large amount of data below the detection-limit; and (2) better representation of non-conservative constituents (e.g. FRP) by accounting for important biogeochemical processes.
An Internal Atmospheric Process Determining Summertime Arctic Sea Ice Melting in the Next Three Decades: Lessons Learnt from 5 Large Ensembles and CMIP5 Simulations
Authors: Topal Daniel , Ding Qinghua , Mitchell Jonathan , Baxter Ian , Herein Mátyás , Haszpra Tímea , Luo Rui , Li Qingquan
Published: March 2020

Arctic sea ice melting processes in summer due to internal atmospheric variability have recently received considerable attention. A regional barotropic atmospheric process over Greenland and the Arctic Ocean in summer (June-July-August), featuring either a year-to-year change or a low-frequency trend toward geopotential height rise, has been identified as an essential contributor to September sea ice loss, in both observations and the CESM1 Large Ensemble (CESM-LE) of simulations [1-2]. This local melting is further found to be sensitive to remote sea surface temperature (SST) variability in the East Central Pacific [3]. Here, we utilize five available single-model large ensembles and 31 CMIP5 models’ pre-industrial control simulations to show that the same atmospheric process, resembling the observed one and the one found in the CESM-LE, also dominates internal sea ice variability on interannual to interdecadal time scales in pre-industrial, historical and future scenarios, regardless of the modeling environment. However, all models exhibit limitations in replicating the correct magnitude of the observed local atmosphere-sea ice coupling and its sensitivity to remote tropical SST variability. These biases cast a shadow over models’ credibility in simulating interactions of sea ice variability with the Arctic and global climate systems. Further efforts toward identifying possible causes of these model limitations may provide profound implications for alleviating the biases and improving interannual and decadal time scale sea ice prediction and future sea ice projection.

 

[1] Ding, Q., and Coauthors, (2017): Influence of high-latitude atmospheric circulation changes on summertime Arctic sea ice. Nat. Climate Change, 7, 289-295.

[2] Ding, Q., and Coauthors, (2019): Fingerprints of internal drivers of Arctic sea ice loss in observations and model simulations. Nat. Geosci., 12, 28–33.

[3] Baxter, I., and Coauthors, (2019): How tropical Pacific surface cooling contributed to accelerated sea ice melt from 2007 to 2012 as ice is thinned by anthropogenic forcing. J. Climate, 32, 8583–8602 https://doi.org/10.1175/JCLI-D-18-0783.1 