bluuebunny/crossref_metadata_2025 huggingface dataset:
Extratropical cyclone characteristics over the North Atlantic and Western Europe during the Last Glacial Maximum
Authors: Pinto Joaquim G. , Ludwig Patrick
Published: March 2020

Extratropical cyclones are a dominant feature of the mid-latitudes, as their passage is associated with strong winds, precipitation, and temperature changes. The statistics and characteristics of extratropical cyclones over the North Atlantic region exhibit some fundamental differences between Pre-Industrial (PI) and Last Glacial Maximum (LGM) climate conditions. Here, the statistics are analysed based on results of a tracking algorithm applied to global PI and LGM climate simulations. During the LGM, both the number and the intensity of detected cyclones was higher compared to PI. In particular, increased cyclone track activity is detected close to the Laurentide ice sheet and over central Europe. To determine changes in cyclone characteristics, the top 30 extreme storm events for PI and LGM have been simulated with a regional climate model and high resolution (12.5 km grid spacing) over the eastern North Atlantic and Western Europe. Results show that LGM extreme cyclones were characterised by weaker precipitation, enhanced frontal temperature gradients, and stronger wind speeds than PI analogues. These results are in line with the view of a colder and drier Europe, characterised by little vegetation and affected by frequent dust storms, leading to reallocation and build-up of thick loess deposits in Europe.
Analyzing the impact of soil properties on glyphosate degradation
Authors: Karlsson Anneli S. , Weihermüller Lutz , Köppchen Stephan , Vereecken Harry , Dippold Michaela , Spielvogel Sandra
Published: March 2020

In year 1974, Monsanto introduced the glyphosate [N-(phosphonomethyl) glycine] product RoundUp and in the 1990s also glyphosate resistant crops. Since then, and increasingly after the expiry of the patent, glyphosate has become the most commonly used herbicide worldwide. The estimation of the worldwide use of glyphosate as an active ingredient amounts to more than 800,000 tons/year (estimation from 2014). A herbicide of such wide spread use, commercial in agriculture and for personal use in gardens, has been found in many different environmental compartments (e.g. surface waters and food) and with negative impact on non-target organisms (e.g. glyphosate resistance in weeds, or bactericidal effects). Glyphosate persistence and degradation of the compound differ between strongly between soils. In this study, we focus on elucidating the factors contributing to the persistence and degradation of glyphosate in two contrasting soils. Different chemical additives (N, P, DOM), as well as pH change and microbial transfer alongside glyphosate application were investigated in a 14C-glyphosate multi-labeling approach, upon their effect on the glyphosate degradation. The study shows that pH initially has a strong positive impact the mineralization in both soils and the DOM addition only increased the mineralization slightly. On the other hand, phosphate addition shows contrasting results in both soils, and nitrate addition lowered the mineralization significantly. Microbial transfer did not have any significant effect on the mineralization. Furthermore, we identify the impact of adsorption of glyphosate in soil as one of the major factors reducing glyphosate degradation.
Assessing the impact of climate change on water quality and quantity in the Elbe catchment using an open-data driven approach
Authors: Wachholz Alexander , Jomaa Seifeddine , Büttner Olaf , Reinecke Robert , Rode Michael , Borchardt Dietrich
Published: March 2020

Due to global climate change, the past decade has been the warmest for Germany since the beginning of climate records. Not only air temperature but also precipitation patterns are changing and therefore influencing the hydrologic cycle. This will certainly influence the chemical status of ground- and surface water bodies as mobilization, dilution and chemical reactions of contaminants are altered. However, it is uncertain if those alterations will impact water quality for better or worse and how they occur spatially. Since water management in Europe is handled at the regional scale, we suggest that an investigation is needed at the same scale to capture and quantify the different responses of the chemical status of water bodies to climate change and extreme weather conditions. In this study, we use open-access data to (1) quantify changes in temperature, precipitation, streamflow and groundwater levels for the past 40 - 60 years and (2) assess their impacts on nutrient concentrations in surface- and groundwater bodies. To disentangle management from climate effects we pay special attention to extreme weather conditions in the past decade. Referring to the Water Framework Directive, we chose the river basin district Elbe as our area of interest. Preliminary results indicate that especially the nitrate concentrations in surface water bodies of the Elbe catchment were positively affected in the last two years, while no significant impact on nitrate levels in shallow groundwater bodies was witnessed. However, many wells showed the first significant increase in water table depth in both years since 1985, raising the question of how fast groundwater-surface water interactions will change in the next years.
The Efficiency of Upward Wave Propagation Near the Tropopause
Authors: Weinberger Israel , Garfinkel Chaim , Birner Thomas
Published: March 2020

Recent work has highlighted that not all periods with anomalous heat flux at 100hPa were preceded by anomalous heat flux in the troposphere (Birner and Alberts 2017; White et al 2019; Camara et al 2019), and the goal of this work is to understand the factors that govern the efficiency of upward wave propagation near the tropopause. The index of refraction of Matsuno (1970) has been used to offer guidance on the direction of wave propagation within the stratosphere. Specifically, waves are preferentially refracted towards regions with a more positive index of refraction and ducted away from regions in which the index of refraction is more negative. However, the index of refraction was derived under the assumption that buoyancy frequency is constant at all height levels, which is clearly not true near the tropopause. This assumption allowed Matsuno to ignore certain height dependent buoyancy frequency terms, and here we explore the impact of these terms near the tropopause.

Using the dataset of the European Center for Medium-Range Weather Forecasts Reanalysis version 5 (ERA5) we defined 'transmitting' composites consisting of more efficient upward propagation events between 300hPa and 100hPa. Similarly, periods of less efficient upward propagation events between 300hPa and 100hPa are composited as 'decaying' events. We computed the index of refraction profile using a median, percentage of negative days and the trimmed mean (Wilks 2011), and also consider the terms neglected by Matsuno. We find that  the index of refraction can account for the difference between the decaying and transmitting composite.
Petrogenesis of the Ulungur Intrusive Complex, NW China, and Implications for Crustal Generation and Reworking in Accretionary Orogens
Authors: Tang Gong-Jian , Wang Qiang , Wyman Derek , Dan Wei , Ma Lin , Zhang Hai-Xiang , Zhao Zhen-Hua
Published: March 2020

Accretionary orogens are characterized by voluminous juvenile components (recently derived from the mantle) and knowing the origin(s) of such components is vital for understanding crustal generation. Here we present field and petrological observations, along with mineral chemistry, zircon U–Pb age and Hf-O isotope data, and whole rock geochemical and Sr-Nd isotopic data for the c. 320 Ma Ulungur intrusive complex from the Central Asian Orogenic Belt. The complex consists of two different magmatic series: one is characterized by medium-K to high-K calc-alkaline gabbro to monzogranite; the other is defined by peralkaline aegirine-arfvedsonite granitoids. The calc-alkaline and peralkaline series granitoids have similar depleted mantle-like Sr-Nd-Hf isotopic compositions, but they have different zircon δ18O values: the calc-alkaline series have mantle-like δ18O values with mean compositions ranging from 5.2 ± 0.5‰ to 6.0 ± 0.9‰ (2SD), and the peralkaline granitoids have low δ18O values ranging from 3.3 ± 0.5‰ to 3.9 ± 0.4‰ (2SD). The calc-alkaline series were derived from a hydrous sub-arc mantle wedge, based on the isotope and geochemical compositions, under garnet peridotite facies conditions. This study suggests that the magmas underwent substantial differentiation, ranging from high pressure crystallization of ultramafic cumulates in the lower crust to lower pressure crystallization dominated by amphibole, plagioclase and minor biotite in the upper crust. The peralkaline series rocks are characterized by δ18O values lower than the mantle and enrichment of high field strength elements (HFSEs) and heavy rare earth elements (HREEs). They likely originated from melting of preexisting hydrothermally altered residual oceanic crust in the lower crust of the Junggar intra-oceanic arc. Early crystallization of clinopyroxene and amphibole was inhibited owing to their low melting temperature, leading to HFSEs and HREEs enrichment in residual peralkaline melts during crystallization of a feldspar-dominated mineral assemblage. Thus, the calc-alkaline and peralkaline series represent episodes of crust generation and reworking, respectively, demonstrating that the juvenile isotopic signature in accretionary orogens can be derived from diverse source rocks. Our results show that reworking of residual oceanic crust also plays an important role in continental crust formation for accretionary orogens, which has not previously been widely recognized.
Non-tectonic seismological events in Greenland - Cryo-generated events and landslides
Authors: Dahl-Jensen Trine , Larsen Tine B. , Voss Peter H.
Published: March 2020

Following the large June 17 2017 landslide in Karrat Isfjord, Central West Greenland the necessity to differentiate between different kinds of seismological events has become relevant for hazard assessment. Greenland is the origin of a many different kinds of seismic signals.  In addition to the than a thousand small to moderate magnitude tectonic earthquakes, most of them ranging between ML 1.0 and 3.0 are located along the coasts of Greenland every year, many other non-tectonic events are located. This is largely possible thanks to the data collected and distributed by the Greenland Ice Sheet Monitoring Network (GLISN) federation and its members (glisn.info). The non-tectonic events include cryo-generated events, and signals from landslides as for example illustrated by the globally seen seismological signal from the Karrat 2017 landslide. It is possible to separate tectonic events from non-tectonic events, based on the characteristics of the seismological signal alone, but the signals from cryo-generated events and landslides have many similar features. In the Karrat Isfjord area, several large glaciers terminate in the sea where for example calving generate seismological events. With poor location resolution due to large station spacing in the remote areas of Greenland, the differences in the seismological signals are important to determine the cause of the events.
Water management plans and sea level rise impacts on seawater intrusion in the Red River Delta, Vietnam
Authors: Nguyen Hien Thi , Nguyen Hai Yen , Balistrocchi Matteo , Ranzi Roberto
Published: March 2020

Seawater intrusion in coastal areas is now rising as a serious problem for river deltas in the world, especially when high tidal levels occur. Red River Delta plays a paramount role in the economy and society of Vietnam and has already been experiencing the increase in salinity concentrations. The combination of high tidal levels and multi-purposes reservoirs operations in the upstream watershed could exacerbate saltwater intrusion. This research, therefore, analyses the impacts of different water management plans, according to reservoirs operations coupled with sea level rise scenarios, on salinity dynamics in the Red River Delta. Two sea level rise projections referred to RCP4.5 and RCP8.5 emission scenarios have been selected for the simulations of future salinity intrusions in 2050 and 2100. In consideration of the important junction of the 3 main upstream rivers (Lo, Thao and Da River), discharge at Son Tay gauge station is selected as the upstream boundary condition for riverflow. Different discharge scenarios in Son Tay station are, hence, adopted based on statistical analysis of runoff data after the construction of the major reservoirs, started in 1973. Taking into account the 25%, 50%, 75%, 95% exceedance quantiles of the minimum monthly riverflow in Son Tay station combined with 4 downstream sea level rise scenarios, 16 salinity profiles along the Red River Delta reaches were obtained by 1D-hydrodynamic simulations. The results are useful as a guidance to plan multi-purposes reservoirs operations, considering environmental, agricultural, industrial and flood-protection targets.
Effect of stones on soil hydraulic properties: measurement and modeling
Authors: Naseri Mahyar , C. Iden Sascha , Durner Wolfgang
Published: March 2020

Stony soils are soils that contain a high amount of stones and are widespread all over the world.  The effective soil hydraulic properties (SHP), i.e. the water retention curve (WRC) and the hydraulic conductivity curve (HCC) are influenced by the presence of stones in the soil. This influence is normally neglected in vadose zone modeling due to the considerable measurement challenges in stony soils. The available data on the effect of stones on SHP is scarce and there is not a systematic modeling approach to obtain the effective SHP in stony soils. Most of the past studies are limited to the effect of stones on the WRC and saturated hydraulic conductivity and low and medium stone contents (up to 40 % v/v). We investigated the effect of stone content on the effective SHP of stony soils through a series of evaporation experiments. Two soil materials a) sandy loam and b) silt loam as background soils were packed with different volumetric contents (0, 10, 30 and 60 %) of medium stones were in containers with a volume of 5060 cm3. Volumetric stone contents were chosen in a way to present stone-free, moderately stony and highly stony soils. All of the experiments were carried out in two replicate packings with an almost identical bulk density. Packed samples were saturated with water from the bottom and subjected to evaporation in a climate-controlled room. During the evaporation experiments, the pressure head and soil temperature were continuously monitored and the water loss from the soil columns was measured with a balance. The dewpoint method provided additional data on the WRC in the dry soil. The resulting data were evaluated by inverse modeling with the Richards equation to identify effective SHP and to analyze the effect of stone content on the evaporation rate, soil temperature, the effective WRC and the effective HCC. The applied methodology was successful in identifying effective SHP with high precision over the full moisture range. The results reveal a quicker transition from stage I to stage II of evaporation in highly stony soils. Evaporation rate reduces with the increase of the volumetric stone content. The existence of a high amount of stone content shorten stage II of evaporation driven by the vapor diffusion through the restricted soil evaporative surface.
Light absorption properties, chromophore composition and sources of brown carbon aerosol in Xi’an, Northwest China
Authors: Huang Ru-Jin , Yuan Wei , Yang Lu , Guo Jie , Duan Jing , Ni Haiyan
Published: March 2020

The impact of brown carbon aerosol (BrC) on the Earth’s radiative forcing balance has been widely recognized but remains uncertain, mainly because the relationships among BrC sources, chromophores, and optical properties of aerosol are poorly understood (Feng et al., 2013; Laskin et al., 2015). In this work, the light absorption properties and chromophore composition of BrC were investigated for samples collected in Xi’an, Northwest China from 2015 to 2016. Both absorption Ångström exponent and mass absorption efficiency show distinct seasonal differences, which could be attributed to the differences in sources and chromophore composition of BrC. Three groups of light-absorbing organics were found to be important BrC chromophores, including those show multiple absorption peaks at wavelength > 350 nm (12 polycyclic aromatic hydrocarbons and their derivatives) and those show single absorption peak at wavelength < 350 nm (10 nitrophenols and nitrosalicylic acids and 3 methoxyphenols). These measured BrC chromophores show distinct seasonal differences and contribute on average about 1.1% and 3.3% of light absorption of methanol-soluble BrC at 365 nm in summer and winter, respectively, about 7 and 5 times higher than the corresponding mass fractions in total organic carbon. The sources of BrC were resolved by positive matrix factorization (PMF) using these chromophores instead of commonly used non-light absorbing organic markers as model inputs. Our results show that in spring vehicular emissions and secondary formation are major sources of BrC (~70%), in fall coal combustion and vehicular emissions are major sources (~70%), in winter biomass burning and coal combustion become major sources (~80%), while in summer secondary BrC dominates (~60%).

 

References:

Feng, Y., V. Ramanathan, and V. R. Kotamarthi: Brown carbon: A significant atmospheric absorber of solar radiation?, Atmos. Chem. Phys., 13, 8607-8621, doi:10.5194/acp-13-8607-2013, 2013.

Laskin, A., J. Laskin, and S. A. Nizkorodov: Chemistry of atmospheric brown carbon, Chem. Rev., 115, 4335-4382, doi:10.1021/cr5006167, 2015.
Loss of jarosite during remediation of a sandy acid sulfate soil
Authors: Koelbl Angelika , Kaiser Klaus , Mosley Luke , Fitzpatrick Rob , Marschner Petra , Mikutta Robert
Published: March 2020

When acid sulfate soils dry, they generate large amounts of sulfuric acid due to oxidation of iron (Fe) sulfides (e.g., pyrite), causing formation of Fe sulfates such as jarosite and strong acidification (pH < 4). After re-saturation of these sulfuric soils and re-establishment of reduced conditions, activity of Fe- and sulfate-reducing bacteria promote re-formation of Fe sulfides and pH increase. However, many reducing bacteria are heterotrophic and require sufficient available organic carbon (OC). Despite the general knowledge about positive impacts of OC addition to ameliorate sulfuric soils, little is known about the reduction of Fe sulfates (here: jarosite) to Fe sulfides and the formation of mineral-organic associations after establishing anoxic conditions.

We investigated the remediation of a sandy, jarosite-containing sulfuric soil (initial pH = 3.0, initial redox values approx. 400 mV) in a 20-week anoxic laboratory incubation experiment under re-submerged conditions. We used a control without OC addition plus treatments with wheat straw addition as substrate for reducing bacteria. Besides the natural sulfuric soil, an artificial acid sulfate soil composed of synthesized jarosite mixed with quartz sand was used to simulate a simple, mineralogically well-characterized model of the natural soil. To ensure similar conditions, the artificial soil was submerged with soil solution from the natural sulfuric soil. We monitored pH and redox values in the soil suspension weekly. After 20 weeks, concentrations of OC, Fe, and S were analysed in bulk soils and soil solutions. The mineral composition was characterised by X-ray diffraction (XRD).

Addition of wheat straw to the natural acid sulfate soil led to quick changes in redox and pH values, reaching pH ≥ 6.0 and redox values ≤ -100 mV within three weeks. XRD analyses revealed complete loss of jarosite during incubation. Addition of wheat straw to the artificial acid sulfate soil led to slightly lower pH and higher redox values than for the natural soil, resulting in approx. pH 5.7 and redox values ≤ 0 mV after three weeks. Some of the jarosite was reduced, but it is still detectable after incubation. Without wheat straw addition, for both soils pH values remained low (pH ≤ 4.0) and redox values remained high (≥ 300 mV). Jarosite concentration did not change during the incubation without straw. The results showed that microbial reduction of acid sulfate soils requires supply of sufficient organic matter, which effectively triggers the reduction of jarosite to sulfides.
Time-lapse monitoring of fractured rock response to hydraulic stimulation using pressure tomography
Authors: Somogyvári Márk , Jalali Mohammadreza
Published: March 2020

Hydraulic stimulation using high-pressure fluid injection has become the common technique for rock mass treatment in various industrial applications such oil & gas, mining and enhanced geothermal system (EGS) development. Hydraulic stimulation is associated with creation of new fractures or dilation of existing fractures that could alter the flow regime in the stimulated reservoir. In this context, it would be beneficiary to understand the dynamic response of the discrete fracture network (DFN) to the stimulation activities rather than comparison between the changes in injectivity and/or transmissivity.

In this work, a 2-D fully coupled hydro-mechanical model is developed to simulate the dynamic response of a fractured reservoir to hydraulic stimulation. The model calculates stresses, fracture fluid pressure and flow inside the fractures, and modifies the physical properties of the individual fractures given these values. All these alterations will be calculated and applied after each simulation timestep. The results of this synthetic modelling will be used to test the time-lapse pressure tomography approach.

Pressure tomography will be simulated at multiple timesteps, to capture the hydraulically active fractures within the system. The used tomographic interpretation will be based on the transdimensional DFN inversion, where model parametrization could change over time. With this methodology we can model the newly opened fractures by the stimulation.

The time-lapse inversion will use the result of the previous timestep as the initial solution for improved efficiency. We test the proposed methodology on outcrop based synthetic 2-D DFN models. The results could capture the changes of permeability (i.e. aperture) as a direct response to hydraulic stimulation.
High intensity ignimbritic activity in the Central sector of the Main Ethiopian Rift
Authors: Franceschini Zara , Scaillet Stéphane , Cioni Raffaello , Corti Giacomo , Sani Federico , Prouteau Gaëlle , Scaillet Bruno , Assen Melaku Abate
Published: March 2020

The volcano-tectonic evolution of the Main Ethiopian Rift (MER) is punctuated with periods of intense silicic volcanism, characterized by large explosive caldera-forming eruptions and the production of several ignimbrite deposits. These volcanic paroxysms require large volume of evolved silicic magma accumulated in shallow chambers into the continental crust; however, the relations between magmatism and tectonics during rifting, and the influence of the distribution and timing of regional tectonics on the ascent of magma and its stalling in large magmatic reservoirs remain poorly defined.

We present new geochronological data (40Ar/39Ar dataset of 29 samples) providing new constraints on the timing, evolution and characteristics of volcanism in the Central sector of the MER, where large ignimbrite deposits and remnants of several calderas testify the recurrence of silicic flare-ups. Specifically, we investigate in detail the eastern margin of the rift, where a voluminous, widespread, crystal-rich ignimbrite (Munesa Crystal Tuff, MCT) has been described. This deposit has been correlated to a thick ignimbrite occurring at the bottom of geothermal wells in the rift, pointing to a giant eruptive event attributed to a huge caldera structure, presumably buried beneath the rift floor. At least other two widespread ignimbrite units are present along the same margin for several tens of kilometres, testifying the high volcanicity of this sector of the MER.

Our survey and analyses suggest that, at least in the eastern margin of the rift, activity was clustered in periods of large magma production and emission, resulting in the recurrence of intense volcanic phases interspersed with periods of rest of volcanism. Ignimbrites and other volcanic deposits occur in the investigated area, spanning an age interval from 3.5 Ma to as recent as 150 ka. The MCT emission, around 3.5 Ma, was followed, after a long quiescence, by an important phase with the emplacement of both mafic (lava flows and scoria cone) and evolved (ignimbrites) products between 1.9-1.6 Ma. After that, volcanism occurred more frequently, possibly with a lower amount of erupted magma and still alternating with quiescent periods, with volcanism clusters at ~ 1.3-1.2 Ma, ~ 0.8-0.7 Ma and ~ 0.3-0.2 Ma. This clustered volcanic activity will be compared with the episodic rifting of this sector of the Main Ethiopian Rift.
Millennial-scale variability in Antarctic Circumpolar Current and its impacts during the last glacial cycle
Authors: Wu Shuzhuang , Lamy Frank , Kuhn Gerhard , Lembke-Jene Lester , Zhang Xu , Haas Christian , Nowaczyk Nortbert , W. Arz Helge , Tiedemann Ralf
Published: March 2020

The Antarctic Circumpolar Current (ACC) is the largest current system in the world, linking the Pacific, Atlantic and Indian Ocean basins. However, the variability of the ACC, which plays a fundamental role on global ocean circulation and climate variability, is still poorly constrained. This information is crucial for understanding the role of the ACC on global ocean circulation in response to global warming. Here, we reconstruct changes in the ACC over the past 155,000 years based on sediment grain size variations recorded in a highly-resolved marine sedimentary record from the central Drake Passage near the Polar Front. Our results show significant changes in the ACC during the last glacial cycle and a remarkable boundary between the glacial and interglacial periods. Substantial decreases (~33% to ~47%) in the ACC flow speed from interglacial to glacial period, which corroborates and extends results of previous studies along the subantarctic northern limit of the ACC into the central Drake Passage. This strong variation of ACC likely plays a significant role in regulating Pacific-Atlantic water mass exchange via the “cold water route” and could significantly affect the Atlantic Meridional Overturning Circulation. Superimposed on these glacial-interglacial changes, we found strong millennial-scale variations in ACC current speed, increasing in amplitude close to full glacial conditions. We hypothesise that the central ACC increases its sensitivity to Southern Hemisphere millennial-scale climates oscillations, likely associated with westerlies’ wind stress and Antarctic sea ice extent once glacial conditions fully formed.
Comparison of rating-curve uncertainty estimation using hydraulic modelling and power-law methods
Authors: Westerberg Ida , Mansanarez Valentin , Lyon Steve , Lam Norris
Published: March 2020

Establishing reliable rating curves and thereby reliable streamflow monitoring records is fundamental to much of hydrological science and water management practice. Cost-effective methods that enable rapid rating curve estimation with low uncertainty are needed given diminishing monitoring resources and increasing human-driven changes to the water cycle. Traditional power-law rating curves rely on numerous gaugings to estimate rating curves and their associated uncertainty. Hydraulically-modelled rating curves are a promising alternative to power-law methods as they rely on fewer gaugings, but they are associated with additional uncertainty sources in the hydraulic knowledge (bed slope, roughness, topography and vegetation), which need to be assessed.

Our aim with this study was to compare power-law and hydraulic-model based methods for estimating rating curves and their uncertainty. We focused on assessing their accuracy as well as the costs and time required for establishing rating curves. We compared the Rating curve Uncertainty estimation using Hydraulic Modelling (RUHM) framework with the Bayesian power-law method BaRatin. The RUHM framework combines a one-dimensional hydraulic model with Bayesian inference to incorporate information from both hydraulic knowledge and the calibration gauging data. We applied both methods to the 584 km2 River Röån station in Sweden under nine different gauging strategies associated with different costs. The gauging strategies differed in the number and flow magnitude of the gaugings used as well as the probability of observing the gauged flows.

We found that rating curves with low uncertainty could be modelled with fewer gaugings using the RUHM framework compared to BaRatin. As few as three gaugings were needed for RUHM if these gaugings covered low and medium flows, making the estimation both cost effective and time efficient. When using all the gaugings available (i.e. a high-cost gauging strategy), the uncertainty for RUHM and BaRatin was similar at the Röån station. Furthermore, we found that BaRatin needed gaugings with lower probability of occurrence (i.e. covering a larger part of the flow range) than needed when using hydraulic modelling (low and middle flow gaugings with high probability of occurrence gave good results). The results for this Swedish site show that hydraulic rating curve uncertainty estimation is a promising tool for quickly estimating rating curves and their uncertainties. In particular, it is useful for previously ungauged or remote sites, or at stations where there have been major temporal changes to the stage–discharge relation.
Structural thermochronology along geophysical transects through the Alps
Authors: Glotzbach Christoph , Eizenhoefer Paul , Kley Jonas , Ehlers Todd A.
Published: March 2020

Changes in the deep lithosphere (e.g., slab break-off or a switch in subduction polarity) potentially result in orogen-wide structural reorientations and changes in the pace and location of exhumation and Earth surface processes. In this project we combine bedrock thermochronology and balanced cross sections with thermo-kinematic modelling to reconstruct the cooling and exhumation history along geophysical profiles crossing the Central and Eastern Alps. Available thermochronological data together with new apatite and zircon (U-Th)/He ages taken along the NFP-20E, TRANSALP and EASI profile is used to test and improve existing across-strike, orogen-wide balanced cross sections. This ‘structural thermochronology’ method yields reliable information about the structural and kinematic evolution of the Alps since continental collision. As an example, thermochronological data along TRANSALP can be fitted with a kinematic model suggested by balanced cross sections and both datasets suggest a general shift from pro- to retro-wedge deformation, potentially related to a switch in subduction polarity.
Monitoring of forest health using spectral unmixing of multispectral satellite data
Authors: Siliuk Volha , Katkovsky Leonid , Beliaev Boris
Published: March 2020

Forests play an important role in global carbon, hydrological and atmospheric cycles. Current environmental issues have a strong impact on forest health. Satellite remote sensing is widely used for forest state monitoring due to increasing availability of satellite data and high temporal resolution. However, a spatial resolution of satellite data is often insufficient to detect small areas of forest drying. For a clearer detection of affected forest areas, spectral unmixing is required.

The results of spectral unmixing of Belarusian spacecraft data (4 bands: blue, green, red, NIR; spatial resolution 10 meters) are performed. To detect affected forest areas that need to be specified, the vegetation index NDVI is calculated. Then, spectral mixture analysis is running for these areas. The library of endmembers (pure spectral signatures) was created by ground measurements using spectral instruments that were developed in the department of aerospace researches of Belarusian state university. Comparison of spectral unmixing results and airborne measurements shows high agreement. Airborne measurements of study forest area was carried out using Leica airborne digital sensor. Spatial resolution of airborne data is around 40 centimeters. The developed spectral unmixing approach can be used for other tasks, such as burned area mapping, crop monitoring, etc.
Sub-ion scale measurements of compressible turbulence in the solar wind MMS Observations
Authors: Roberts Owen , Nakamura Rumi , Narita Yasuhito , Holmes Justin , Voros Zoltan , Lhotka Christoph , Thwaites Jessica
Published: March 2020

Compressible plasma turbulence is investigated at sub ion scales using both the Fast Plasma Investigation instrument on the Magnetospheric MultiScale mission as well as using calibrated spacecraft potential. The data from FPI allow inertial and a small region of sub-ion scales to be investigated before the instrumental noise becomes significant near 3Hz. In this work we give a detailed description of the spacecraft potential and how it is calibrated such that it can be used the measure the electron density. The key advantage of using the calibrated spacecraft potential is that a much higher time resolution is possible when compared to the direct measurement. This allows a measurement down to 40Hz for a measurement of the electron density. This is an improvement of an additional decade in scale. Using a one hour interval of solar wind burst mode data the power spectrum of the density fluctuations is measured from the inertial range to the sub ion range. At inertial scales the density spectrum shows similarities with the magnetic field power spectrum with a characteristic Kolmogorov like power law. In between the ion inertial and kinetic scales there is a brief flattening in the spectra before steepening in the sub ion range to a spectral index comparable to the trace magnetic field fluctuations. The morphology if the density spectra can be explained by either a cascade of Alfv\'en waves and slow waves at large scales and kinetic Alfv\'en waves at sub ion scales, or by the presence of the hall effect. Using electric field measurements the two hypotheses are tested.
Evaluating the terrestrial carbon dioxide removal (tCDR) potential of large-scale aff-/reforestation and improved forest management in Norway
Authors: Bright Ryan , Allen Micky , Anton-Fernandez Clara , Dalsgaard Lise , Eisner Stephanie , Granhus Aksel , Søgaard Gunnhild , Astrup Rasmus
Published: March 2020

As a carbon dioxide removal measure, the Norwegian government is currently considering a policy of large-scale planting of spruce (Picea abies (L) H. Karst) on non-forested lands (i.e., aff-/reforestation) and secondary forested lands dominated by early successional broadleaved tree species (i.e., improved forest management).  Given the need to achieve net zero emissions in the latter half of the 21st century in effort to limit the global mean temperature rise to “well below” 2 °C, the mitigation potential of such a policy is unclear given relatively slow tree growth rates in the region.  Further convoluting the picture is the magnitude and relevance of surface albedo changes linked to such projects, which typically counter the benefits of an enhanced forest CO2 sink in high latitude regions.  Here, we carry out a rigorous empirical assessment of the terrestrial carbon dioxide removal (tCDR) potential of large-scale aff-/reforestation (AR) and improved forest management (IFM) projects in Norway, taking into account transient developments in both terrestrial carbon sinks and surface albedo over the 21st century and beyond.  We find that surface albedo changes would likely play a negligible role in counteracting the carbon cycle benefit of tCDR, yet given slow forest growth rates in the region, meaningful tCDR benefits from AR and IFM projects would not be realized until the end of the 21st century, with maximum benefits occurring around 2150.  We estimate Norway’s total accumulated tCDR potential at 2100 and 2150 (including surface albedo changes) to be 447 (± 240) and 852 (± 295) Mt CO2-eq. at mean costs of US$ 29 (± 18) and US$ 26 (± 14) per ton CDR, respectively.  For perspective, the accumulated tCDR potential at 2100 represents around 8 years of Norway’s total current annual production-based (i.e., territorial) CO2-eq. emissions.
Precise Positioning with the Modified Ambiguity Function Approach using BDS and GPS observations
Authors: Kwaśniak Dawid , Cellmer Sławomir
Published: March 2020

For many years GPS and GLONNAS were leading navigation systems. However, recent years two new navigational systems have appeared. These systems are the European Galileo System and the Chinese BeiDou System (BDS). The full operability of both systems is foreseen for 2020. The BDS is quickly developing in last years and still increasing number of satellites allows to use this system for positioning. GPS and BDS systems share some of their signals frequencies. These shared signals frequencies allows to combine observation of both systems. The goal of this study is use the BDS along with GPS for positioning purpose.

For test purpose a self-made software was created in MatLab. It consists of three modules.  First is responsible for reading RINEX files, second for the DGPS or the DGNSS in case of combined GPS and BDS observations and the third one uses The Modified Ambiguity Function Approach (MAFA) method for precise positioning purposes. MAFA is a method of processing GNSS carrier phase observations. In this method the integer nature of  ambiguities is taken into account using appropriate form of mathematical model. The theoretical Foundations of Precise Positioning Using MAFA will be presented. For test purpose data from three different days for the same baseline was used. Test was divided on two parts. In the first part short static sessions were performed for GPS only BDS only and for GPS and BDS combination. In the second part data was tested in RTK mode for GPS only, BDS only and for GPS and BeiDou System combination.

BDS allows to obtain an accuracy on the same level as GPS. The usage of GPS and BDS combinations allows to increase the precision of the obtained result comparing to GPS only solution. Very important thing is to remember about inter system bias (ISB) - the difference between the receiver hardware delays affecting the signals from different systems, that can affect for the results.
The phytoextraction potential of selected vegetable plants on Kosovo contaminated soils
Authors: Miano Teodoro , Voca Hana , Piscitelli Lea , Malerba Anna Daniela , Mondelli Donato , D'Orazio Valeria
Published: March 2020

Mining activities generate a great deal of particulate emissions and waste slag enriched in heavy metals that contaminate the surrounding, that is soil, water and air. Such effects are particularly serious and pose a severe ecological and human health risk, mainly if smelters are located in the proximity of urban areas. This is the case regarding the Kosovo, where from the 1930s the British company "Seltrust" founded Trepca Mining & Metallurgical Complex, causing a high level of pollution especially in the area of Mitrovicë, northern Kosovo. Two soils, A and B, have been sampled from two different sites in Mitrovicë municipality, showing a total content of Pb and Zn, respectively, of 2153 and 3087 mg kg-1, and 3214 and 4619 mg kg-1. A pot experiment was carried out aiming to understand the phytoremediation potential of two selected non-food crops (Sorghum bicolor L. Moench and Brassica napus cv. Westar) chosen for their economic importance and heavy metal accumulation capacities. Sorghum and canola plants were cultivated in polluted soils A and B. For both plant species, the accumulation of heavy metals proved to be higher in the roots. Indeed, in order to obtain an adequate phytoextraction, it is required that the metals be moved to the epigeal part of the plants, and plants with bioconcentration factor (BCF) and translocation factor (TF) values < 1 are not considered suitable for phytoextraction. The results obtained in this study indicate that, although canola was quite effective in translocating metals from roots to aerial parts, both sorghum and canola are not suitable for phytoextraction since their coefficient values were < 1. Anyway, both plants, especially canola ones, grew up in presence of high level of Pb and Zn pollution, thus they could be used for phytostabilisation process. Actually, the Tolerance Index (TI) values of the sorghum and canola clearly suggest, under the experimental conditions used in this study, a better performance of the canola in tolerating the presence of Pb and Zn in the soil, even if in soil B was not found the same efficiency shown by the same plants grown in soil A. Probably, since soil B has an absolute higher content of Pb and Zn and a lower pH, the availability of both metals is slightly higher, which may have induced in the plants that grow there a more intense condition of stress. This study shows that canola, unlike sorghum, can be an ideal choice for phytostabilization, and its breeding can represent an effective alternative to food crop. 
A Virtual Geostationary Ocean Colour Sensor to characterise the river-sea interaction over the North Adriatic Sea.
Authors: Bracaglia Marco , Santoleri Rosalia , Volpe Gianluca , Colella Simone , Braga Federica , Bellafiore Debora , Brando Vittorio Ernesto
Published: March 2020

Inherent optical properties (IOPs) and concentrations of the sea water components are key quantities in supporting the monitoring of the water quality and the study of the ecosystem functioning. In coastal waters, those quantities have a large spatial and temporal variability, due to river discharges and meteo-marine conditions, such as wind, wave and current, and their interaction with shallow water bathymetry. This short term variability can be adequately captured only using Geostationary Ocean Colour (OC) satellites, absent over the European seas.

In this study, to compensate the lack of an OC geostationary sensor over the North Adriatic Sea (NAS), the Virtual Geostationary Ocean Colour Sensor (VGOCS) dataset has been used. VGOCS contains data from several OC polar satellites, making available multiple images a day of the NAS, approaching the temporal resolution of a geostationary sensor.

Generally, data from different satellite sensors are characterized by different uncertainty sources and consequently, looking at two satellite images, it is not easy to ascertain how much of the observed differences are due to real processes. In the VGOCS dataset, the inter-sensor differences are reduced, as the satellite data were adjusted with a multi-linear regression algorithm based on in situ reflectance acquired in the gulf of Venice. Consequently, the use of the adjusted spectra as input in the retrieval of the IOPs and the concentrations allows performing a reliable analysis of the short-time bio-optical variability of the basin.

In this work, we demonstrate the suitability of VGOCS to better characterise the river-sea interaction and to understand the influence of the river forcing on the short time variability of IOPs and concentrations in the coastal areas. This variability will be analysed for different case studies characterised by a different regime of river discharges, using meteorological, hydrological, and oceanographic fields as ancillary variables. This new approach and the availability of this new set of data represent an opportunity for interdisciplinary studies, in support to and interacting also with modelling implementations in river-sea areas.
Variation of the surface ozone concentration during precipitation
Authors: Ptashnik Igor V. , Belan Boris D. , Savkin Denis E. , Tolmachev Gennadii N. , Sklyadneva Tatayana K. , Rasskazchikova Tatayana M. , Arshinova Victoria , Fofonov Alexandr V.
Published: March 2020

In the review compiled by Monks et al. (2015), it is noted that the main variations in the tropospheric ozone are determined by the exchange between the troposphere and the stratosphere, in-situ photochemical production from gaseous precursors depending on their composition and concentration, solar radiation income, and meteorological conditions. The impact of precipitation on the surface ozone concentration is a less well-studied factor.

The process of ozone interaction with precipitation was studied theoretically (Heicklen, 1982). Two ways of the above process were analyzed: adsorption of gas molecules on the surface of a particle and a chemical reaction with its surface. There are no direct data on the verification of these findings in the literature. At the same time, there is some evidence of a possible link between precipitation and ozone.

This study is aimed to analyze the presence or absence of changes in the ozone concentration during precipitation. Variations of the surface ozone concentration (SOC) in the presence of precipitation were analyzed using the long-term data obtained at the TOR-station established in 1992 for ozone monitoring in Tomsk. It was revealed that these changes can be both positive (increase in concentration) and negative. The sharp changes in the SOC are observed when frontal precipitation takes place. In the presence of air-mass precipitation, the sign and magnitude of the change is determined by the diurnal variation of ozone concentration.

The analysis showed a coincidence of the SOC growth during precipitation with its increase in diurnal variation in 59% of cases. The coincidence in the wave of the concentration decline in the diurnal variation with decreasing precipitation rate is even higher and amounts to 85%.

Airborne sounding carried out in the vicinity of the TOR-station shown that in a number of cases the ozone deposition from the boundary layer is observed upon the transition of thermal stratification during the precipitation to neutral.

 

Monks P. S, Archibald A. T., Colette A., Cooper O., Coyle M., Derwent R., Fowler D., Granier C., Law K. S., Mills G. E., Stevenson D. S., Tarasova O., Thouret V., von Schneidemesser E., Sommariva R., Wild O., Williams M. L. Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer. Atmos. Chem. Phys., 2015, v.15, N15, p.8889–8973.

Heicklen J. The Removal of Atmospheric Gases by Particulate Matter. In Heterogeneous Atmospheric Chemistry, ed. D. R. Schryer, Geophysical Monograph 26. American Geophysical Union, Washington, DC, USA, 1982, p. 93-98.