bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatiotemporal Characteristics of Tropospheric and Surface NO2 from Sentinel-5 Precursor (S5P) and in-situ Observations in Taiwan
Authors: Cai Yi-Jhen , Liu Chian-Yi , Chou Charles
Published: March 2020

        Sentinel-5 Precursor (S5P) is a new generation environmental satellite, and provides trace gases concentrations along with cloud and aerosol information for global coverage. In this study, we focus on a regional scale nitrogen oxide (NOx) which is not only mainly air pollutant but also the precursors of secondary aerosol and ozone. However, the atmospheric NOx is primary in the form of Nitrogen dioxide (NO2). To understand the chemical properties and air pollution of NO2 from S5P in Taiwan, this study accesses the tropospheric NO2 which is retrieved from the TROPOMI onboard S5P, in conjunction with in-situ surface NO2 concentration observation from Environmental Protection Administration (EPA) of Taiwan. The temporal period is from June 2018 to May 2019, and surface observation is collocated with daily revisit of S5P spatiotemporally. The data are analyzed in 15 sub-regions of Taiwan for the relationship between tropospheric vertical column and surface concentration of NO2.

        The preliminary results reveal high correlation between surface NO2 and tropospheric NO2 in North Taiwan (Taipei/New Taipei City/Keelung), Yunlin, Tainan and Kaohsiung. Relative low correlation in Yilan, Hualian because of broad area with less ground-based stations. On the other hand, in order to avoid the impact of short-term factors, monthly mean concentration of NO2 is applied for further statistics. The results indicate high relationship in most of counties, except Hsinchu and Taitung. This suggests that the tendency of surface NO2 is similar to the tropospheric NO2 in most of countries in Taiwan in the monthly scale. Therefore, in order to monitor and analysis of NO2 concentration, spaceborne TROPOMI on S5P might be an alternative choice for conducting related research in Taiwan.
Establishing an Isolation Alert System for Mountain Community
Authors: Tsai Yuan Fang , Pan Jia Hao , Hsieh I Chia
Published: March 2020

The outreach road of mountain community has been interrupted by disasters such debris flow, flood and landslides, resulting in the interruption of the outreach road of the mountain community, forming a state like an island, which can be regarded as an isolation effect. In recent years, extreme events caused by extreme weather. The special geographical conditions in Taiwan, coupled with the increase in the frequency of natural disasters, have been heard by isolated island news. In 2015, Typhoon Soudelor hit Taiwan, and Wulai, New Taipei City caused severe disasters. Debris flow and landslides occurred, causing the interruption of Xinwu Road, the main liaison road in Wulai, and the isolation effect in Wulai. If we can integrate the historical data and research of isolation effect, and combine the theory of isolated prediction with instant rainfall and disaster prevention information, and finally visualize the information by alert system, it will help the general public's disaster prevention awareness and related disaster prevention unit decision-making reference.

Therefore, this research builds an isolation alert system. The three main information functions of this system include 1. disaster island geographic information function 2. isolated accident village identification function and 3. immediate isolated warning function. The d isolated geographic information display function is mainly to display the historical information about the isolation effect. The information of the village has been published, including the village's geography, social information and disaster history, and the risk map is presented by the vulnerability and resilience indicators. The village identification function of the isolated incident is realized by the Common Alerting Protocol of the road, and based on this, the identification in the immediate isolated village is carried out. The immediate disaster isolated warning function combines real-time rainfall information and integrates the Rainfall Triggering Index, Machine Learning's Supervised Learning algorithm, and the Common Alerting Protocol for the road. In the end, it was verified by the 2017 Typhoon Nepartak incident, and the results were all given the correct warning level for the isolated village.
Ionospheric irregularities detected by GEONET
Authors: Ma Guanyi , Li Qi , Maruyama Takashi , Li Jinghua , Wan Qingtao , Fan Jiangtao , Wang Xiaolan , Zhang Jie
Published: March 2020

Ionospheric irregularities disrupt the propagation of radio waves in the frequency range below a few GHz, a band used by navigation and communication systems such as Global Navigation Satellite System (GNSS). Detailed understanding of the irregularity characteristics is helpful to estimate potential degradation of the performance of radio systems. We develop an algorithm to obtain high spatial resolution vertical total electron content (VTEC) and propose a spatial fluctuation of total electron content (TEC), SFT parameter, to analyze ionospheric irregularities by using the world’s densest GNSS Earth Observation Network (GEONET) of Japan. The data used in this study are carrier phase of the dual frequency GNSS signals from more than 1300 GNSS receivers of GEONET. VTEC is derived by assuming that it is identical in a 0.1°×0.1° grid, and removing a quantity representing inter-frequency hardware bias mixed with integer ambiguity. SFT is defined as the spatial dispersion of TEC within a specific area at a given time. The size of the specific area for SFT calculation is chosen as 0.8°× 0.8° in longitude and latitude, which corresponds to approximately 77 km×95 km at 400 km height at 35°N of Japan. An SFT map is generated by sliding window to show the spatial variation of ionospheric irregularities in two dimensions. The map can be used to obtain the size, shape, orientation and intensity distribution of the irregularity structures. Case studies are carried out for three strong irregularity events on 12 February 2000, 20 March 2001 and 10 November 2004. The irregularities are found to be anisotropic branching structures, which elongate in north-south direction when first seen at lower latitudes. The structures can move and deviate from their previous orientations, and eventually drift perpendicular to their orientations. Such analyses of SFT maps with GEONET observation successfully provide a new perspective of irregularity morphology and evolution.
A New Avenue of Research for Improving the Predictability of Weather Extremes - The Eastern Mediterranen as a Case Study
Authors: Hochman Assaf , Alpert Pinhas , Saaroni Hadas , Harpaz Tzvi , Pinto Joaquim G. , Messori Gabriele
Published: March 2020

Extreme weather events have long been considered challenging to predict. It is likely that global warming will trigger extreme weather in many regions of the globe and especially over the Mediterranean ´hot spot´. Therefore, extreme weather events have been selected as one of the grand challenges of the World Climate Research Program.

The intrinsic predictability of a weather system, or any dynamical system, depends on its persistence and its active number of degrees of freedom. Recent developments in dynamical systems theory allow to compute these metrics for atmospheric configurations (1). In most of the mid-latitudes, synoptic scale patterns exert a strong control on regional weather, thus, stimulating a broad interest, especially in weather forecasting. Recently, we have integrated the dynamical systems approach with a synoptic classification algorithm over the Eastern Mediterranean (2).  It was shown that the dynamical systems perspective provides an extremely informative tool for evaluating the predictability of synoptic patterns and especially of weather extremes.

The novel perspective, which leverages a dynamical systems approach to investigate the predictability of extreme weather events, outlines a new avenue of research that may be fruitfully applied at operational weather and climate forecasting services in the Mediterranean Region and around the globe.

References

Faranda D, Messori G, Yiou P. 2017. Dynamical Proxies of North Atlantic Predictability and Extremes. Scientific Reports 7, 412782017b. DOI: 10.1038/srep4127

Hochman A, Alpert P, Harpaz T, Saaroni H, Messori G. 2019. A New Dynamical Systems Perspective on Atmospheric Predictability; Eastern Mediterranean Weather Regimes as a Case Study. Science Advances 5. DOI: 10.1126/sciadv.aau0936
How volcanism impact on the variability of the South American Monsoon System and the associated Atlantic Subtropical Cell
Authors: Sobral Verona Laura , Wainer Ilana , Khodri Myriam
Published: March 2020

Large volcanic eruptions can affect the global climate through changes in atmospheric and ocean circulation. Understanding the influence of volcanic eruptions on the hydroclimate over monsoon regions is of great scientific and social importance. The South America Monsoon System (SAMS) is the most important climatic feature of the continent. Both the Intertropical and the South Atlantic wind convergence zones (ITCZ and SACZ, respectively) are fundamental components of the SAMS. They show variations on a broad range of scales, dependent on complex multi-system interactions with the adjacent Atlantic Ocean and teleconnections. Also driven by the winds, the Atlantic Subtropical Cell (STC) is the link between the subduction zone in the subtropical gyre with the tropics. Hence, the STC influence equatorial sea surface temperature variability on interannual to decadal scales in the tropical Atlantic Ocean. In order to improve our understanding of the responses of the ocean-atmosphere system to the volcanic forcing, we aim to identify the dominant mechanisms of seasonal-to-interdecadal variability of the SAMS and the Atlantic STC after large Pinatubo-like (1991) and Tambora-like (1815) eruptions relying on the VolMIP model intercomparison project experiments.
Saturn lightning activity from a cyclone at 50°North latitude
Authors: Fischer Georg , Gunnarson Jacob
Published: March 2020

During the Cassini mission (2004-2017) the Radio and Plasma Wave Science (RPWS) experiment has recorded the lightning radio emissions from multiple thunderstorms in Saturn's atmosphere. Most of the storms were located in the storm alley at a planetocentric latitude of 35°South, and there was one extra-large storm at 35°North called "Great White Spot" (GWS), which emitted millions of SEDs. This is short for "Saturn Electrostatic Discharges", a widely-used synonym for the radio emission from Saturn lightning. Most lightning storms have also been observed by the Cassini cameras or by ground-based amateur astronomers as bright white spots with diameters around 2000 km ("smaller" storms in the storm alley) or as large as 10,000 km (GWS at 35°North).

In this presentation we focus on a cyclone at 50°North planetocentric latitude, which was observed by the Cassini cameras from 2007 until the end of 2013. Its average diameter was around 3000 km, and it also exhibited some weak SED activity. The first SED outbreak was in December 2010, at the same time when the GWS was raging further south. Due to the differences in longitude and SED rate of the 50°N cyclone compared to the GWS, it is partly possible to separate the SEDs emitted from the cyclone to those emitted from the GWS. The SED rate of the cyclone is rather low, typically a few SEDs per minute, whereas the GWS showed SED rates up to 10 SEDs per second. The SED activity of the 50°North cyclone was very intermittent, it usually lasted for a few weeks before disappearing again for several months. After the first outbreak in December 2010, there was some more activity in early 2011, autumn 2011, December 2011, spring 2012, July 2012, summer 2013, and finally autumn 2013. By comparing SED data from RPWS with images from the Cassini camera we will show that almost all SEDs taking place after the GWS had their origin in the 50°N cyclone, since the SED sub-spacecraft longitude range is consistent with the longitude of the cyclone. The last SED activity from this cyclone took place in November 2013, and it was also the last SED activity recorded by RPWS during the whole Cassini mission. No more SEDs were found from November 2013 until Cassini burned up in Saturn's upper atmosphere in September 2017.

 
Dense Fog Burst Reinforcement over Eastern China
Authors: Liu Duanyang , Li Zihua , Yan Wenlian , Wang Hongbin , Zhu Chengying , Zhu Yuying , Zu Fan
Published: March 2020

Fog can be hazardous weather. Dense and polluted fog is especially known to impact transportation, air quality, and public health. Low visibilities on fog days threaten the safety of air, sea and land traffic, especially in strong dense fog (SDF) and extremely dense fog (EDF), which is the most likely to cause accidents such as car rear-end collisions and ship collisions. Throughout more than ten years of observations, strong dense fog (SDF) (visibility less than 200m) and extremely dense fog (EDF) (visibility less than 50m) often occurred in the central and eastern regions of China. This could lead to serious traffic accidents.

This research summarizes the research results of dense fog in China, including the burst reinforcement features of strong dense fog (SDF) formation, universal feature of SDF, the microphysical process of the fog body enhancement, the causes of burst reinforcement and the characteristics of the boundary layer structure. There are also remarks about fog dissipations. The research results show that there are still many important scientific problems to be solved about dense fog. Future directions for understanding Dense Fog Burst Reinforcement including that: (1) How fog expands to the surrounding areas, and what factors influence the spread of fog? (2) The physical mechanism of dense fog burst reinforcement. (3) It needs to be further observed to study the role of low-level jets in the formation of dense fog. How the low-level jet stream forms? (4) impact of air pollution on the dense fog formation.
Sensitivity on tendency perturbations of tropical cyclone short-range intensity forecasts generated by WRF
Authors: Qin Xiaohao , Duan Wansuo , Xu Hui
Published: March 2020

The present study uses the nonlinear singular vector (NFSV) approach to identify the optimally-growing tendency perturbations of the Weather Research and Forecasting (WRF) model for tropical cyclone (TC) intensity forecasts. For nine selected TC cases, the NFSV-tendency perturbations of the WRF model, including components of potential temperature and/or moisture, are calculated when TC intensities are forecasted with a 24-hour lead time, and their respective potential temperature components are demonstrated to have more impact on the TC intensity forecasts. The perturbations coherently show barotropic structure around the central location of the TCs at the 24-hour lead time, and their dominant energies concentrate in the middle layers of the atmosphere. Moreover, such structures do not depend on TC intensities and subsequent development of the TC. The NFSV-tendency perturbations may indicate that the model uncertainty that is represented by tendency perturbations but associated with the inner-core of TCs, makes larger contributions to the TC intensity forecast uncertainty. Further analysis shows that the TC intensity forecast skill could be greatly improved as preferentially superimposing an appropriate tendency perturbation associated with the sensitivity of NFSVs to correct the model, even if using a WRF with coarse resolution.

 
Role of Science Communication in beliefs, perceptions and knowledge of science and technology issues among European citizens
Authors: Rubin Andrea , Pellegrini Giuseppe , Šottník Lubomir
Published: March 2020

The last decade had seen an emergence of a new more dynamic and inconsistent media ecosystem. Digital media (i.e. social media) are accused by many independent researchers and influential observers, to have played a significant role in spread of science misinformation. Wide-ranging discussions about so-called ‘post-truth’ or ‘fake news’ phenomena have significantly involved science-related topics such as vaccines, GMO’s, climate change or homeopathy.

The issue of credibility and reliability of information is therefore central for science communication and public understanding of science.

CONCISE (“Communication role on perception and beliefs of EU Citizens about Science”), an EU research project intends to understand the role of science communication in beliefs, perceptions and knowledge of science and technology issues among European citizens from five countries: Spain, Italy, Portugal, Poland and Slovakia.

This paper presents preliminary quantitative results from Italian public consultation analysis regarding preferred citizen´s information channels and sources of scientific information. We will explore data to understand how trust in science is built, how citizens form opinions about the science, which sources of information they use and how they think can science communication could be more effective.
The extreme warmth of the Central European spring in 2018 and its effects on fruit ripening phenology in Austria – a 251 year perspective
Authors: Scheifinger Helfried
Published: March 2020

The exceptional warmth of spring and early summer of 2018 caused the earliest beginning of fruit ripening dates in Austria since 1946 of black elder and red currant, the second earliest of apricot, as well as the shortest period between the beginning of flowering and fruit ripening for all three species (same as 1956 for red currant). These phenological extremities of the 2018 spring correspond with the highest Austrian preseason (temperatures before the phenological event) April/May/June average since 1768.

In order to put the spring of 2018 into a long term perspective, the above mentioned phenological time series were extended back to 1768 by the much longer homogenised HISTALP temperature time series. This was achieved by multiple regression driven by preseason mean monthly temperatures. In order to accommodate for the uncertainty of the regression model, the lower (5%) and upper (95%) bounds of the confidence intervals were added to the reconstructed time series. Even when considering the lower bounds, the 2018 entry date of black elder beginning of fruit ripening remains the earliest since 1768. The 2018 entry date of apricot comes fourth (after 1811, 1794, 1797 and same as 1822) and that of red currant third (after 1811 and 1794). In order to evaluate the phenological variability since 1970 a 11 year moving average and a 41 year moving trend were calculated for the combined time series consisting of the modelled (from 1768 to 1945) and observed (from 1946 – 2018) sections. Neither the level of the 11 year averages nor the level of the 41 year trend values since 1970 have occurred during any other period since 1768.

These results contribute to the discussion of the temperature sensitivity of phenological phases. In spite of the unprecedented spring and early summer temperature level our phenological data do not indicate that lower bounds of the time period between flowering and fruit ripening have yet been reached. The fruit ripening phenology of the mid latitudes is still sensitive enough to faithfully record temperature trends and extreme events supplementing the instrumental record.
Induced uneven spatial distribution of agrochemicals due to preferential flow in water repellent soils and its remediation by surfactant
Authors: Ogunmokun Felix Abayomi , Wallach Rony
Published: March 2020

Soil water repellency is a common feature of dry soils under permanent vegetation and drought conditions. Soil-water hydrology is markedly affected by soil-water repellency as it hinders infiltration, leading to enhanced surface runoff and soil erosion. Although this phenomenon was primarily ascribed to sandy soils, it has been observed in loam, clay, and peat soils in dry and humid regions. One detrimental effect of soil water repellency on plants is the reduction of soil water availability that stems from the non-uniform water retention and flow in preferential pathways (gravity-induced fingers) with relatively dry soil volume among these paths. It was recently discovered that prolonged irrigation with treated wastewater, a widely used alternative in Israel and other Mediterranean countries due to the limited freshwater, triggers soil water repellency which invariably resulted in preferential flow development in the field. Due to climate change events, the use of treated wastewater for irrigation as a means of freshwater conservation is expected to widen, including in countries that are not considered dry.

While a vast amount of research has been devoted to characterizing the preferential flow in water repellent soils, the effect of this flow regime on the spatial distribution of salt and fertilizers in the root zone was barely investigated. Results from a commercial citrus orchard irrigated with treated wastewater that includes the spatial and temporal distribution of preferential flow in the soil profile measured by ERT will be demonstrated. The associated spatial distribution of salinity, nitrate, phosphate, and SAR in the soil profile will be shown as well.  We investigated the efficacy of two nonionic surfactants application to remediate hydrophobic sandy soils both in the laboratory and field. The effect of the surfactant application to the water repellent soils in the orchards on the spatial distribution of soil moisture and the associated agrochemicals will be presented and discussed.
Reconciling the role of the Labrador Sea overturning circulation in OSNAP and climate models
Authors: Lozier Susan , Menary Matthew , Jackson Laura
Published: March 2020

The AMOC (Atlantic Meridional Overturning Circulation) is a key driver of climate change and variability. Since continuous, direct measurements of the overturning strength in the North Atlantic subpolar gyre (SPG) have been unavailable until recently, the understanding, based largely on climate models, is that the Labrador Sea has an important role in shaping the evolution of the AMOC. However, a recent high profile observational campaign (Overturning in the Subpolar North Atlantic, OSNAP) has called into question the importance of the Labrador Sea, and hence of the credibility of the AMOC representation in climate models. Here, we reconcile these viewpoints by comparing the OSNAP data with a new, high-resolution coupled climate model: HadGEM3-GC3.1-MM. Unlike many previous models, we find our model compares well to the OSNAP overturning observations. Furthermore, overturning variability across the eastern OSNAP section (OSNAP-E), and not in the Labrador Sea region, appears linked to AMOC variability further south. Labrador Sea densities are shown to be an important indicator of downstream AMOC variability, but these densities are driven by upstream variability across OSNAP-E rather than local processes in the Labrador Sea.
Effect from polynyas in the Laptev and the Beaufort seas to atmospheric transport of heat and moisture
Authors: Prokhorova Uliana , Urazgildeeva Alexandra , Alexeev Genrich
Published: March 2020

Coastal and fast ice polynyas in the Arctic seas can have a noticeable effect on the Arctic climate, increasing the temperature of the cold air which coming from continental Siberia in winter to these seas and in the Arctic basin [1-2]. In this paper, were studied the effect of polynyas on surface air temperature and on the meridional heat and moisture transfers by the ERA-Interim reanalysis data. From reanalysis, meridional heat transfers were obtained through 70 ° N and 74 ° N, air temperature profiles, wind speed in the region of the Laptev (100 - 140 ° E.) and Beaufort (120 - 160 ° W.) Seas, and polynyas which located in the Laptev Sea (120 - 130 ° E) and Beaufort (160 - 140 ° W.). It was confirmed that winter transfers of cold air from the mainland do not have a cooling effect on the average winter air temperature north of 74 ° N due to the heating effect of polynyas.
Atmospheric iodine chemistry from molecular level to 0D/3D simulations: applications to Fukushima nuclear accident
Authors: Louis Florent , Taamalli Sonia , Fèvre-Nollet Valérie , Li Qinyi , Cuevas Carlos A. , Saiz-Lopez Alfonso
Published: March 2020

In the case of a hypothetical nuclear accident, fission products are released into the environment. Simulation tools are commonly used to predict the radiological consequences on populations. After the Fukushima accident, significant differences have been observed between measured and modeled concentrations for iodine 131. This can be attributed to the high reactivity of iodine in the atmosphere not considered in the current dispersion crisis tools.

To address this, a new gas-phase mechanism of atmospheric iodine chemistry was developed containing 248 reactions. In parallel, missing thermokinetic data were determined by molecular-scale simulations for iodous and iodic acids. The 0D simulation results showed a partial and rapid transformation of these iodinated gaseous compounds. The influence of several parameters (air quality, quantity and nature of iodine released) was evaluated. For all simulations, iodine is quickly found in the form of iodine oxides and nitroxides or gaseous iodinated organic compounds. The latter may be the cause of iodinated aerosols formation and deposition.

Results from the 3D chemistry-climate model CAM-Chem will be compared to iodine Fukushima deposits measurements. Implications for atmospheric chemistry (air quality and climate) will be discussed.
Hybrid-Vlasov simulation of auroral proton precipitation in the cusps: Comparison of northward and southward interplanetary magnetic field driving
Authors: Grandin Maxime , Turc Lucile , Battarbee Markus , Ganse Urs , Johlander Andreas , Pfau-Kempf Yann , Dubart Maxime , Palmroth Minna
Published: March 2020

We present the first hybrid-Vlasov simulations of proton precipitation in the polar cusps. We use two runs from the Vlasiator model to compare cusp proton precipitation fluxes during southward and northward interplanetary magnetic field (IMF) driving. The simulations reproduce well-known features of cusp precipitation, such as a reverse dispersion of precipitating proton energies, with proton energies increasing with increasing geomagnetic latitude under northward IMF driving, and a nonreversed dispersion under southward IMF driving. The cusp location is also found more poleward in the northward IMF simulation than in the southward IMF simulation. In addition, we find that the precipitation takes place in the form of successive bursts during southward IMF driving, those bursts being associated with the transit of flux transfer events in the vicinity of the cusp. In the northward IMF simulation, dual lobe reconnection takes place. As a consequence, in addition to the high-latitude precipitation footprint associated with the lobe reconnection from the same hemisphere, we observe lower-latitude precipitating protons which originate from the opposite hemisphere’s lobe reconnection site. The proton velocity distribution functions along the newly closed dayside magnetic field lines exhibit multiple proton beams travelling parallel and antiparallel to the magnetic field direction, which is consistent with observations with the Cluster spacecraft. We suggest that precipitating protons originating from the opposite hemisphere’s lobe reconnection site, albeit infrequent, could be observed in a situation of dual lobe reconnection.
Data assimilation for a visco-elastic Earth deformation model
Authors: Schachtschneider Reyko , Saynisch-Wagner Jan , Bagge Meike , Klemann Volker , Thomas Maik
Published: March 2020

We present a data assimilation algorithm for the time-domain spectral-finite element code VILMA. We consider a 1D earth structure and a prescribed  glaciation history ICE5G for the external mass load forcing. We use the Parallel Data Assimilation Framework (PDAF) to assimilate sea level data into the  model in order to obtain better estimates of the viscosity structure of mantle and lithosphere. For this purpose, we apply a particle filter in which an ensemble of models is propagated in time, starting shortly before the last glacial maximum. At epochs when observations are available, each particle's performance is estimated  and they are resampled based on their performance to form a new ensemble that better resembles the true viscosity distribution. In a proof of concept we  show that with this method it is possible to reconstruct a synthetic viscosity distribution from which synthetic data were constructed. In a second step,  paleo sea level data are used to infer an optimised 1D viscosity distribution.
An optimization principle for computing stationary MHD equilibria with solar wind flow
Authors: Wiegelmann Thomas , Neukirch Thomas , Nickeler Dieter , Chifu Iulia
Published: March 2020

Knowledge about the magnetic field and plasma environment is important
for almost all physical processes in the solar atmosphere. Precise
measurements of the magnetic field vector are done routinely only in
the photosphere, e.g. by SDO/HMI. These measurements are used as
boundary condition for modelling the solar chromosphere and corona,
whereas some model assumptions have to be made. In the low-plasma-beta
corona the Lorentz-force vanishes and the magnetic field
is reconstructed with a nonlinear force-free model. In the mixed-beta
chromosphere plasma forces have to be taken into account with the
help of a magnetostatic model. And finally for modelling the global
corona far beyond the source surface the solar wind flow has to
be incorporated within a stationary MHD model.
To do so, we generalize a nonlinear force-free and magneto-static optimization
code by the inclusion of a field aligned compressible plasma flow.
Applications are the implementation of the solar wind on
global scale. This allows to reconstruct the coronal magnetic field further
outwards than with potential field, nonlinear force-free and magneto-static models.
This way the model might help in future to provide the magnetic connectivity
for joint observations of remote sensing and in-situ instruments on Solar
Orbiter and Parker Solar Probe.
How to manage windthrows in Central Europe to prevent bark beetle outbreaks?
Authors: Dobor Laura , Hlásny Tomáš , Rammer Werner , Zimová Soňa , Seidl Rupert
Published: March 2020

Bark beetle (Ips typographus) epidemics in Europe are typically triggered by excessive availability of freshly dead trees and trees with compromised defense, which often occur after windstorms or droughts. Subsequently, enlarged beetle populations migrate to the surrounding forests, which were not affected by the primary disturbance. Removal of windfelled trees (salvage or sanitation logging) is therefore a frequent management response to prevent the build-up of bark beetle populations. Yet, the effectivity of the removal remains poorly understood, particularly when the outbreaks are amplified by faster beetle development cycles and reduced tree defense under climate change conditions.

Moreover, diverse ownership, management objectives and limited resources often restrict salvaging operations, and the final effect on bark beetle populations is thus even less clear. To better understand the interplay between climate, management, bark beetle populations, and host trees, we use the process-based forest landscape and disturbance model iLand. We studied differences between the removal of windfelled trees applied evenly across the landscape, focused on the vicinity of roads (scenario of limited logging resources) and concentrated in a contiguous block (scenario of spatially diversified management objectives) on a 16 050 ha forest landscape in Central Europe. We found that the removal of >80% of all windfelled trees is required to substantially reduce bark beetle disturbances. Focusing on the vicinity of roads created a “fire break effect” on bark beetle spread, and was moderately efficient in reducing landscape-scale bark beetle disturbance. Block treatments substantially reduced outbreaks in treated areas. Leaving parts of the landscape untreated (e.g., conservation areas) had no significant amplifying effect on outbreaks in managed areas. Our research suggests that the management of interacting disturbances from wind and bark beetles requires much more complex considerations than are currently practiced.
Interannual-to-decadal variability of the Kuroshio extension: Analyzing an ensemble of global hindcasts from a Dynamical System viewpoint.
Authors: Fedele Giusy , Penduff Thierry , Pierini Stefano , Alvarez-Castro M. Carmen , Bellucci Alessio , Masina Simona
Published: March 2020

The Kuroshio Extension (KE) is the inertial meandering jet formed by the convergence of the Kuroshio and Oyashio currents in the Northern Pacific. It is widely mentioned in the literature that the KE variability is bimodal on the decadal time scale. The nature of this low frequency variability (LFV) is still under debate; some authors suggest that internal oceanic mechanisms play a fundamental role in the phenomenon but there is also evidence from the observations that the KE LFV is connected with changes in broader patterns of variability such as the Pacific Decadal Oscillation.

We first inspect the interplay between the ocean and the atmosphere in the KE by taking advantage of the OCCIPUT 1/4° model dataset: it consists in an ensemble of 50 global ocean–sea-ice hindcasts performed over the period 1960–2015 (hereafter OCCITENS), and in a one-member 330-yr climatological simulation (hereafter OCCICLIM). In this context, OCCITENS simulates both the intrinsic and forced variability and allows for their separation via ensemble statistics, while OCCICLIM simulates the "pure" intrinsic variability of the jet. We then explore some features of the KE dynamical system attractor in the quasi-autonomous (OCCICLIM) and nonautonomous (OCCITENS) regimes: we thus assess the KE predictability in the OCCIPUT dataset in order to better understand the ocean-atmosphere interactions and the source of the associated predictability.

Our analyses show that both oceanic and atmospheric drivers control the KE LFV variability. In this framework, the results suggest that the jet oscillates between the two intrinsic oceanic modes with transitions triggered by the atmosphere.
The chemical evolution from older (323–318 Ma) towards younger highly evolved tin granites (315–314 Ma)—sources and metal enrichment in Variscan granites of the Western Erzgebirge (Central European Variscides, Germany)
Authors: Tichomirowa Marion , Gerdes Axel , Lapp Manuel , Leonhardt Dietmar , Whitehouse Martin
Published: March 2020

The sources and critical enrichment processes for granite related tin ores are still not well understood. The Erzgebirge represents one of the classical regions for tin mineralization. We investigated the four largest plutons from the Western Erzgebirge (Germany) for the geochemistry of bulk rocks and autocrystic zircons and relate this information to their intrusion ages. The source rocks of the Variscan granites were identified as high-grade metamorphic rocks based on the comparison of Hf-O isotope data on zircons, the abundance of xenocrystic zircon ages as well as Nd and Hf model ages. Among these rocks, restite is the most likely candidate for later Variscan melts.

In contrast to previously published suggestions (Romer and Kroner, 2015; Wolf et al., 2018), we can exclude a substantial role of intense sedimentary weathering as an important control factor for later Sn and W enrichment in granite related ores of the Western Erzgebirge due to the remarkable homogeneous Hf and low O isotopes in granitic zircons that are extremely distinct to all pre-Devonian basement rocks of Saxothuringia. We document a source enrichment from meta-sedimentary rocks (575 Ma) towards metamorphic rocks (340 Ma) were restites from granulite-facies melts are enriched 6–7 times in Sn compared to UCC (upper continental crust). These rocks are also enriched in K, but depleted in Na and Ca, contain abundant muscovite, and are fertile for later melting. Further enrichment of Sn and W occurred during multiple melt production of the older igneous granites (323–318 Ma) leading finally to a general enrichment of Sn (15 times compared to UCC) in the tin granites (315-314 Ma). Multiple melt production did not lead to a very strong enrichment of ore metals in the granites but is probably very important for a general enrichment of Sn and W in the thick granite-rich crust of the Erzgebirge. Efficient leaching by hydrothermal fluids led to a very strong enrichment (up to several orders) of Sn and W in the greisen ore bodies.

 

References:

Romer, R.L.; Kroner, U. Sediment and weathering control on the distribution of Paleozoic magmatic tin-tungsten mineralization. Mineral. Depos. 2015, 50, 327–338, doi:10.1007/s00126-014-0540-5.

Wolf, M.; Romer, R.L.; Franz, L.; Lopez-Moro, F.J. Tin in granitic melts: The role of melting temperature and protolith composition. Lithos 2018, 310–311, 20–30.
Geomorphological analysis of different growth stages of a deeply buried submarine fan, Santos Basin, Brazil.
Authors: Seiti Yamassaki Hugo , Farias Vesely Fernando
Published: March 2020

Seismic geomorphology has shown to be a powerful tool to assess deep-water systems, allowing to characterize the geometry and composition of depositional elements and to reconstruct erosion, transport and deposition. However, this approach has been applied mainly to describe a relatively short period of the depositional time, preventing the interpretation of long-term changes in geomorphology and the resulting depositional architecture of individual systems. In this research, we analyze the geomorphological evolution of a deeply buried submarine fan in the Upper Cretaceous of northern Santos Basin, SE Brazil. The submarine fan is 3100 m below seafloor, it has an area of ~700 km2, 200 m of maximum thickness, and the external geometry is influenced by the topography of an underlying mass transport deposit (MTD) and salt domes. By using 3D seismic data, we mapped 5 horizons related to the submarine fan (Hz1 – fan base; Hz2 – lower fan; Hz3 – middle fan; Hz4 – upper fan; Hz5 – fan top). We generated isochron maps to define the overall geometry and to examine spatial changes in deposition during different stages of growth. We produced a coherence map of Hz1 to highlight slope and substrate irregularities. Spectral decomposition attribute was extracted from internal fan horizons (Hz2 to 4), which clearly revealed channel networks radiating from a feeder canyon. A total of 109 channel segments were measured to calculate sinuosity indexes (SI) considering three classes (SI<1.1 = straight; 1.1<SI<1.5 sinuous; SI>1.5 = meandering. The results show important aspects of fan development and changes in channel style with time. The isochron maps reveal lobe avulsion caused by compensation cycles (Hz2 to Hz3) and fan progradation towards the basin in an elongated shape. The submarine fan was first build up with straight channels and we observe an upward increase in channel sinuosity. Hz2 has 100% of straight channels, Hz3 shows 65% of straight, 30% of sinuous and 5% of meandering channels, and the Hz4 presents 51% of sinuous and 49% of straight channels. We interpret this overall increase in sinuosity as a result of a decrease in fan surface gradient caused by a progressive aggradation. The lack of MTDs within the fan and the few terminal depositional lobes observed in seismic attribute maps imply that superimposed overbank and channel-fill elements dominate the submarine fan architecture. Furthermore, the application of seismic attributes based on amplitude of acoustic impedance contrasts shows that channel-fill elements concentrate most of the sandy deposits.
Geodetic SAR for Height System Unification and Sea Level Research in the Baltics
Authors: Gruber Thomas , Ågren Jonas , Angermann Detlef , Ellmann Artu , Gisinger Christoph , Nastula Jolanta , Oikonomidou Xanthi , Poutanen Markku
Published: March 2020

Traditionally, sea level is observed at tide gauge stations, which usually also serve as height reference stations for national levelling networks and therefore define a height system of a country. Thus, sea level research across countries is closely linked to height system unification and needs to be regarded jointly. The project aims to make use of a new observation technique, namely SAR positioning, which can help to connect the GNSS basic network of a country to tide gauge stations and as such to link the sea level records of tide gauge stations to the geometric network. By knowing the geoid heights at the tide gauge stations in a global height reference frame with high precision, one can finally obtain absolute sea level heights of the tide gauge stations in a common reference system and can link them together. By this method, on the one hand national height systems can be connected and on the other hand the absolute sea level at the tide gauge stations can be determined. By analyzing time series of absolute sea level heights their changes can be determined in an absolute sense in a global reference frame and the impact of climate change on sea level can be quantified (e.g. by ice sheet and glacier melting, water inflow, global warming). The paper presents the main scientific questions to be addressed by the project, introduces the idea of using SAR transponders for this application and describes the observation network implemented for this feasibility study.
The European Ground Motion Service: a continental scale map of ground deformation.
Authors: Solari Lorenzo , Crosetto Michele , Balasis-Levinsen Joanna , Casagli Nicola , Frei Michaela , Moldestad Dag Anders , Oyen Anneleen
Published: March 2020

Satellite radar interferometry is widely considered as one of the most robust and reliable techniques for ground motion monitoring at local scale and over wide areas. In the recent years, satellite radar interferometry has undergone a rapid evolution thanks to the launch of the Sentinel-1 constellation, to the refinement of algorithms, and to the increased computational capability offered by cloud computing platforms. All these factors allow for the development of national or regional services based on satellite interferometric data. Italy, Norway, Germany, Denmark, and the Netherlands are the first European countries working to develop their own Ground Motion Service (GMS) at regional or national scale. Each service has its own characteristics, defined by the user needs and by the deformation regimes to be captured: some GMS work at regional scale with a high update frequency while other capture ground motions with e.g. one-year update frequencies over the entire nation. These examples demonstrate the high demand for interferometric products as wide area mapping or monitoring tools which are a direct request from national/regional entities and administrations involved in e.g. geohazard risk management or infrastructures monitoring.

As of November 2016, the European Ground Motion Service (EGMS) Task Force laid the foundation for a new Copernicus service aimed to perform Sentinel-1-based ground motion monitoring which relies on satellite interferometric products at continental scale. The work of the EGMS Task Force led to the creation of the EGMS White Paper (https://land.copernicus.eu/user-corner/technical-library/egms-white-paper), which is considered the conceptual baseline for the EGMS. In 2017, the Copernicus User Forum and the Copernicus Committee unanimously approved the addition of the EGMS to the Copernicus Land Monitoring Service’s product portfolio. The European Environment Agency (EEA) was designated to be responsible for the Service implementation. The EGMS will provide consistent, regular, standardized, harmonized and reliable information regarding natural and anthropogenic ground motion phenomena over Europe. Moreover, the entire product portfolio will be freely available for every private or public user, following the Copernicus data access concept. The EGMS will stimulate a wider use of PSI products all around Europe. As such, it is expected to act as a baseline for those nations already having an operational GMS and as primary data for countries that do not.
The Agulhas Bank Circulation
Authors: Matano Ricardo
Published: March 2020

The southern tip of Africa is the gateway between the Indian and Atlantic oceans, one of the most widely recognized chokepoints of the meridional overturning circulation (MOC). The oceanic circulation in this region connects a western boundary current, the Agulhas Current, to an eastern boundary current, the Benguela Current, a connection not replicated elsewhere and quite important, not only because of its peculiarity, but also because of its role in the MOC. During the last few decades numerous international research programs have collected large amounts of oceanographic data of this region. All these efforts, however, have been largely focused on the deep-ocean, leaving the coastal region practically unattended. In this presentation we will use the results of a suite of process-oriented numerical experiments to discuss the circulation along the Agulhas Bank (AB)—the shelf region sandwiched between the eastern and western margins of the African continent; in particular to illustrate its connections and interactions with the deep-ocean region. As we shall show these shelf/deep-ocean interactions, are not only important to the shelf but also to the Indian/Atlantic interoceanic exchange.
A late Tonian plate reorganization event: Using a deep-time full-plate global model to unravel Neoproterozoic tectonic convulsions
Authors: Collins Alan , Blades Morgan , Merdith Andrew , Foden John
Published: March 2020

Plate reorganization events are a characteristic of plate tectonics that punctuate the Phanerozoic. They fundamentally change the lithospheric plate-motion circuit, influencing the planet’s tectonic-mantle system and both ocean and atmospheric circulation through changes in bathymetry and topography. The development of full-plate reconstructions for deep time allows the geological record to be interrogated in a framework where plate kinematic reorganizations can be explored. Here, the geological record of the one of the most extensive tracts of Neoproterozoic crust on the planet (the Arabian-Nubian Shield) is interpreted to reflect a late Tonian plate reorganization at ca. 800-715 Ma that switched plate-convergence directions in the Mozambique Ocean, bringing Neoproterozoic India towards both the African cratons and Australia-Mawson, instigating the closure of the intervening ocean and the future amalgamation of central Gondwana ca. 200 million years later. This plate kinematic change is coeval with constraints on break-up of the core of Rodinia between Australia-Mawson and Laurentia and Kalahari and Congo.