bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of the Effects of Warm Temperature Perturbation on Mesoscale Vortex and Rainfall in Col Field
Authors: Jiang Yongqiang , Chen Chaohui , He Hongrang , Liu Yudi , Huang Hong , Wang Xuezhong , Wang Huawen
Published: March 2020

The col field (a region between two lows and two highs in the isobaric surface) is a common pattern leading to the generation of mesoscale vortex and heavy rainfall in China. The mesoscale vortex usually forms near the col point and the dilatation axis of the col field in the low-level troposphere.

The Mesoscale model WRF was used to numerically simulate a rainfall process in col field. A temperature perturbation column (TPC) was introduced into the low-level col field near the col point, and the effects of TPC on mesoscale vortex and rainfall was analyzed.

It was shown that in the region of strong wind background, the TPC moves downstream and has little effect on the environment, while near the col point, the wind speed and the vertical wind shear are small, the TPC can stay in the col field for a long time, which can have a greater impact on the environment. The strong TPC near the col point can trigger the vortex. As the temperature of the air column increases, the pressure drops, leading to the low-level convergence and the upper-level divergence, and the low-level cyclonic vorticity form under the effect of ageostrophic winds, which is favor of the formation of mesoscale vortex in the weak wind field. The formation of vortex promotes the intensification of precipitation. The release of the latent heat of the condensation induced by the TPC makes a positive feedback for the mesoscale vortex. The southwestly low-level jet enhances through the thermodynamic action, resulting in convergence of the leeward low-level jet and increase of precipitation, and divergence of the upwind low-level jet and decrease of precipitation, respectively. The col field is a favorable circumstance for the formation of mesoscale vortex.

Acknowledgements. This research was supported by the National Natural Science Foundation of China (Grant Nos. 41975128 and 41275099).
High resolution LST climatology in an urban area using Landsat 8 thermal data
Authors: Cheval Sorin , Dumitrescu Alexandru , Amihăesei Vlad
Published: March 2020

The Landsat 8 satellites retrieve land surface temperature (LST) values at 30-m spatial resolution since 2013, but the urban climate studies frequently use a limited number of images due to the problems related to missing data over the area of interest. This paper proposes a procedure for building a long-term LST data set in an urban area using the high-resolution Landsat 8 imagery. The methodology is demonstrated on 94 images available through 2013-2018 over Bucharest (Romania). The raw images contain between 1.1% and 58.4% missing data. Based on an Empirical Orthogonal Filling (EOF) procedure, the LST missing values were reconstructed by means of the function dineof implemented in sinkr R packages. The output was used for exploring the LST climatology in the area of interest. The gap filling procedure was validated by comparing artificial gaps created in the real data sets. At the best of our knowledge, this is the first study using full spatial coverage high resolution remote sensing data for investigating the urban climate. The validation pursued the comparison between LST and Ta at 3 WMO stations monitoring the climate of Bucharest, and returned strong correlation coefficients (R2 > 0.9). Further research may be envisaged aiming to update the data set with more recent LST information and to combine data from various sources in order to build a more robust urban LST climatology.

This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CCCDI -
UEFISCDI, project number COFUND-SUSCROP-SUSCAP-2, within PNCDI III.
New data from the 40 year old Dye3 core
Authors: Blunier Thomas , Venkatesh Janani , Soestmeyer David Aaron , Liisberg Jesper Baldtzer , Rhodes Rachael , Menking James Andrew , Severinghaus Jeffrey P. , Harlan Meg , Kjær Helle Astrid , Vallelonga Paul
Published: March 2020

The Dye3 core was drilled at Dye3 (65°11’N, 43°50’W) in 1979 – 1981. The core has been analyzed for numerous components over the last decades. We measured remaining sections, the Younger Dryas and a larger portion of the last glacial, in a continuous flow setup in fall 2019. Here we focus on gas measurements. We measured methane, δ15N, δ40Ar, and the elemental ratio of Ar and N2. We present the continuous flow setup for measuring those components in parallel and first results with a focus on the exact timing of changes in methane and δ15N and δ40Ar at the Younger Dryas and Dansgaard-Oeschger transitions.
Surrogate climate change projections for the Lake Victoria region with a convection-permitting model.
Authors: Van de Walle Jonas , Brousse Oscar , Brogli Roman , Demuzere Matthias , Thiery Wim , P.M. van Lipzig Nicole
Published: March 2020

Extreme weather is posing constant threat to more than 30 million people living near Lake Victoria or depending on its resources. Thousands of fishermen die every year by severe thunderstorms and associated water currents, while hazardous over-land thunderstorms largely affect people living inland, continuously facing flood risks. These risks call for better understanding of such climate extremes over the region. Climate models are a useful tool to gain insight in the complex behaviour of thunderstorms, especially when simulated at convection-permitting resolution. Such simulations, explicitly resolving deep convection at fine resolutions, have been shown to improve the representation of extreme events in many parts of the world, also in equatorial East-Africa (Finney et al., 2019; Kendon et al., 2019; Van de Walle et al., 2019). As a response, the CORDEX-Flagship Pilot Study “climate extremes in the Lake Victoria basin” (ELVIC) initiative is currently setting up an ensemble of convection-permitting simulations over the region.

At this stage, future climate projections are needed to assess the impact of anthropogenic climate change on extreme weather the region. Therefore, a surrogate global warming approach following Schär et al. (1996), Kröner et al. (2016), Liu et al. (2016) and Rasmussen et al. (2017) has been applied to a convection-permitting COSMO-CLM simulation. In this approach, the lateral boundary conditions from the ERA5 (~31 km resolution) reanalysis are perturbed in accordance with the recent CMIP6 ensemble-mean end-of-century SSP5 8.5 climate change scenario. This approach confers three major advantages over the more conventional methods. First, by perturbing with the ensemble-mean, it excludes uncertainties of GCMs without the need for a time and computational intensive high resolution ensemble approach. Second, it avoids including present-day circulation biases. Third, no intermediate nesting steps are necessary, as the perturbed ERA5 allows a direct downscaling to the convection-permitting climate projection.

Besides the methodology, results for the Lake Victoria basin will be presented. Although the occurrence of extreme over-lake precipitation in the present-day climate is mostly controlled by large- and mesoscale atmospheric dynamics (Van de Walle et al., 2019), its future intensification is mainly attributed to increased humidity (Thiery et al., 2016). Furthermore, the effect of changed large-scale dynamics is assessed, as not only temperature and humidity, but also wind forcing is modified.
Towards Conditional Parameter Estimation for Automatic Model Structure Identification: Using Mixed-Integer Calibration for Model Development
Authors: Spieler Diana , Mai Juliane , Tolson Bryan , Craig James , Schütze Niels
Published: March 2020

A recently introduced framework for Automatic Model Structure Identification (AMSI) allows to simultaneously optimize model structure choices (integer decision variables) and parameter values (continuous decision variables) in hydrologic modelling. By combining the mixed-integer optimization algorithm DDS and the flexible hydrologic modelling framework RAVEN, AMSI is able to test a vast number of model structure and parameter combinations in order to identify the most suitable model structure for representing the rainfall runoff behavior of a catchment. The model structure and all potentially active model parameters are calibrated simultaneously. This causes a certain degree of inefficiency during the calibration process, as variables might be perturbed that are not currently relevant for the tested model structure. In order to avoid this, we propose an adaption of the current DDS algorithm allowing for conditional parameter estimation. Parameters will only be perturbed during the calibration process if they are relevant for the model structure that is currently tested. The conditional parameter estimation setup will be compared to the standard DDS algorithm for multiple AMSI test cases. We will show if and how conditional parameter estimation increases the efficiency of AMSI.
Gravity wave activity during the southern hemispheric sudden stratospheric warming 2019
Authors: Dörnbrack Andreas , Mixa Tyler , Kaifler Bernd , Rapp Markus
Published: March 2020

At the end of the austral winter 2019, a sudden stratospheric warming led to an early breakdown of the polar vortex. The meteorological conditions during this event are documented and analysed by means of operational analyses of the Intgrated Forecast System (IFS) of the ECMWF and ERA5 data. Especially, we focus on the decline of stratospheric wave activity over the southern tip of South America. For this region, ground-based and airborne measurements are employed to compare selected diagnostics with fields from the ECMWF's numerical weather prediction model IFS. Furthmore, the meteorological conditions for one selected research flight during the SOUTHTRAC campaign are presented. This part serves as background information for a case study presented by Tyler Mixa.
Seasonal forecasts of discharge in the Upper Danube upstream of Vienna
Authors: Martin Santos Ignacio , Herrnegger Mathew , Holzmann Hubert , Fröhlich Kristina , Ostermüller Jennifer
Published: March 2020

In the last years, the demand of reliable seasonal streamflow forecasts has increased with the aim of incorporating them into decision support systems for e.g. river navigation, power plant operation  or drought risk management. Recently, the concept of “climate services” has gained stronger attention in Europe, thereby incorporating useful information derived from climate predictions and projections that support adaptation, mitigation and disaster risk management. In the frame of one of these climate services currently in development, Clim2Power project, a seasonal forecast system for discharge in the Upper Danube upstream Vienna has been established.

Seasonal forecasts are generated using a dynamical approach running a hydrological model (COSERO) with forecasted climate input provided by DWD (Germany's National Meterological Service). The climate forecasts are based on a large ensemble of predictions, available up to 6 months. After the application of a statistical downscaling method, the climate forecasts have a spatial resolution of 6km. The predictability is related to two main contributions: meteorological forcings (i.e. temperature and precipitation predictability) and initial basin states at the time the forecast is issued.

The Upper Danube basin with a catchment area of approx. 100.000 km2 is characterized by complex topography dominated by the Alps, elevations range from about 150 m to slightly under 4000 m. Therefore, the skill of the seasonal forecast is highly influenced by the resolution of the meteorological data, and likewise by the hydrological processes that take place, especially, regarding melting processes. Downscaled hindcasts over the last 20 years, generated with the identical setup as the seasonal forecasts, are used in this contribution to assess the skill of the seasonal forecasts. In addition, some post-processing corrections, based on historical observations, are used to adjust the bias of the forecasts. Nevertheless, remaining non-systematic error patterns do not allow complete bias correction. Apart from the biases, also the correlation patterns show a limited skill. We conclude that the seasonal discharge forecasting is still not sufficient to incorporate the results into water resources decision support systems within the studied Alpine basins.
Reconstruction of sediment transported patterns since the late Miocene in the Qiongdongnan Basin, northern South China Sea
Authors: Su Ming , Lin Zhixuan , Wang Ce , Chen Hui , Liu Shan , Luo Kunwen
Published: March 2020

Late Miocene-to-present sedimentary succession, consisting of deep-water channels, submarine canyons, shelf-edge delta and clinoform, mass transport complex (MTC), turbidites, pelagic sediments and so on, has accumulated in the Qiongdongnan Basin (QDNB) and supplied from several sediment potential provenances, including surrounding tectonic uplifts and drainage system (e.g. Hainan island, Red River system and Shenhu Uplift). This multiple sediment source system with a variety of space-time distribution is more likely to result in different transported pathways to connect with accumulated zone of the QDNB. To investigate spatial and temporal variation of sediment transported patterns since the late Miocene, the primary dataset in this study is high-resolution 2D seismic profiles that are used to interpret several types of sedimentary features and to determine the distribution within the basin. Integrated analysis of core samples and well log data summarized from previous studies is allow for acquiring high-resolution vertical information about physical and chemical properties of different types of sedimentary features. Depended on characterization and spatial distribution of depositional models, the sediment delivered pattern could be classified into three major types. (1) the downslope transports suggest that sediments were transported by gravity flows and slope failures from high topographic areas to deposit at the basinfloor, and basinward prograding deposition at the shelf or tectonic uplifts, channels/canyons developed along the slope and submarine fans formed at the lower slope are the products of downslope transports shown in the SE-trending seismic profiles; (2) the canyon-axial transports are associated with geomorphology of the Central Canyon System (CCS) across the QDNB from SWW to NEE. Abundant sediments originated at the Red River system were supplied from the west, resulting in dominantly onlap-filling turbidites with a series of erosional discordance within the head area and western segment of the CCS; (3) the combined transport is a mixture of downslope and canyon-axial sediment transports. A large volume of MTDs source from the Hainan Island in the north was transported southward and impeded by the Southern Uplift, so they tended to widen the canyon and continuously deliver eastward along CCS. These three types of sediment transported patterns since the late Miocene in the QDNB might be helpful for predicting distribution of different sedimentary characteristics, which has economic significance in the industrial field.
Multi-proxy approach to reconstruct Middle and Late Holocene paleoenvironment and climate in the eastern Carpathians.
Authors: Ramos-Roman Maria J. , Seppä Heikki , Magyari Eniko , De Jonge Cindy , Veres Daniel , Heyd Volker , Eglinton Timothy I. , Develle Anne-Lise
Published: March 2020

Sediments from lakes are a useful climate archive that provides information about past climate changes and human impact. It is well-known that abrupt climate change can be the trigger of the collapse or migrations of past civilizations. To have a better understanding of the migration of the Yamnaya civilization, located west of the Black Sea at ~5.5-5 cal kyr BP, we hypothesize that past climate changes acts as a driver of this migration. To test this we focus on a sedimentary record retrieved from the Mocearu lake that is located at 780 m a.s.l. in the Buzau mountains (eastern Carpathians, Romania). The record has a length of 7 m and covers the last ~6.5 cal kyr BP based on AMS radiocarbon dates. To reconstruct vegetation, environment and climate during the Middle and Late Holocene, we use complementary techniques: pollen, inorganic (XRF-analysis) and organic geochemistry based on lipid biomarkers (brGDGTs). The reconstruction has been carried out with higher resolution during the Middle Holocene, with the objective of finding evidence of the climatic changes that may have occurred around 5 cal kyr BP. Based on preliminary radiocarbon dating, the climatic reconstruction (based on brGDGTs) shows an increase in temperature from ~6 to 5.5 cal kyr BP, followed by a prominent decrease ~5.3-5 cal kyr BP.
Morphodynamic processes of blowout on the fixed dune, China
Authors: Zhou Yanguang , Hasi Eerdun
Published: March 2020

Blowout is a common landform on sandy grassland in semi-arid area and part of semi-humid area, and it is the symbol of the activation of fixed dune and the primary manifestation of desertification. This paper selected the south edge of Otingdag Sandy Land as the research area, and used WindSonic and high-precision RTK GPS to measure the airflow and topography of three blowouts with different morphology on the fixed dune. Meanwhile, combining with the image data and meteorological data,we analyzed the morphology evolution process of the three different blowouts and discussed the relationship between airflow and morphology of blowouts. The results showed that the northwest, west and southwest winds were dominant in the study area, and the west wind among them was the most frequent; The average annual wind speed tends to decrease, and the wind direction gradually tends to be stable and unidirectional, which is consistent with the direction of movement of the blowout in this area; From the air inlet to the top of the sand accumulation area, each blowout experienced the process of diffusion deceleration, convergence acceleration, separation deceleration and gradual acceleration along the long axis of the blowout, but the location that highest or lowest wind speed occurred were not the same in different blowout; The relationship between the wind direction and the long axis of blowout determines the airflow pattern inside blowouts. When the airflow diagonally enters the blowout, the airflow pattern tends to be complicated, and the deceleration and acceleration zone in blowout are obviously deviated. After the airflow enters the blowout, the wind speed and direction change obviously, which affects the spatial pattern of erosion or accumulation and further alters the morphology of the blowout. The morphology also in turn reacts on the near-surface airflow, which results in the response and feedback of the morphology and dynamics of the blowout.
Column experiment for purification of clear-cut forest runoff using biochar
Authors: Kakaei Lafdani Elham , Saarela Taija , Laurén Ari , Pumpanen Jukka , Palviainen Marjo
Published: March 2020

In drained boreal peatlands, forest regeneration is typically done using a sequence of clear-cutting, ditch network maintenance, site preparation and planting. Following the forest regeneration, export of nutrients to water courses is increased. This results in degradation of water quality, eutrophication, and enhances the formation of harmful algal blooms. The aim of current research was to test a biochar reactor in forest runoff water purification, especially nitrogen recovery from runoff water. The biochar reactor was tested using a meso-scale laboratory experiment by circulating forest runoff water through biochar-filled columns and by monitoring water nutrient concentrations in the inlet and outlet of the columns. Adsorption rate (Kad) and maximum adsorption capacity (Qmax) were quantified by fitting pseudo-first and second order as kinetic models to the experimental data. The results demonstrated that concentration of total nitrogen (TN) decreased by 58% during the 8 weeks experiment, and the majority of TN adsorption has occurred already within the first 3 days. In addition, NO3-N and NH4-N concentrations decreased below the detection limit in 5 days after the beginning of the experiment. The results demonstrated that the biochar reactor was not able to adsorb TN in low concentrations. The results suggest that biochar reactor can be a useful and effective method for runoff water purification in clear-cut forests and deserves further development and testing. This makes biochar reactor a promising water protection tool to be tested in sites where there is a risk for high rate of nutrient export after forest regeneration.

Keywords: adsorption, biochar reactor, column experiment, inorganic nitrogen, total nitrogen.
Structural Health Monitoring of existing structures and infrastructures combining on-site and satellite data
Authors: Ponzo Felice Carlo , Ditommaso Rocco
Published: March 2020

In the last years, existing structures and transport infrastructures, especially those made using reinforced concrete, have experienced significant safety criticalities implying also a relevant social and economic impacts. Structural Health Monitoring techniques represent a reliable response to the problem available to scientists and engineers. A multidisciplinary approach combing knowledge from several research fields and using different kind of technologies would be preferable for this type of application. Most of developed methods for structural damage detection on civil structures and infrastructures is generally based on the evaluation of displacements, eigenfrequencies, damping factors, mode shapes, etc., and their variation over time, by means of on-site installed sensors. In recent years, thanks to the rapid evolution of interferometric SAR processing techniques, a large amount of “satellite measurements” are available for both geophysical phenomena and building monitoring in terms of displacement rate over time. This paper presents an overview on the 2019-2021 WP6 Reluis Project aiming to contribute to the discussion about the opportunity and the modalities to merge information retrieved both by on-site and remote sensing measurements and to define a shared strategy to detect damage on existing structures and infrastructures in operational conditions.
Filling the “old” aquifer with water from new sources: A perspective on Managed Aquifer Recharge in Israel
Authors: Kurtzman Daniel , Guttman Joseph
Published: March 2020

In the Israeli water supply system there is a continuous development of new water sources to meet the demand. Managed aquifer recharge is operated over the years to recharge the older in use, exploited aquifer by the newly developed sources. The Mediterranean coastal aquifer in Israel and drilling technology that matured in the beginning of the 20 century enabled the fast development of cities, towns and villages along this coastline. Naturally, this lead to over exploitation of this aquifer that peaked in the 1950s. New water resources were developed since, and surpluses beyond direct supply, from these sources were/are used to recharge the coastal aquifer. These new water sources (years used also for managed recharge) include: Ephemeral streams flood-water (1959-present); the neighbour, mountain aquifer (1950s-1990s); Sea of Galilee lake water (1960s-1990s); wastewater effluents (1987–present); and desalinated seawater (2014-present). Manged recharge from these sources through wells and infiltration ponds on the sandy soils overlying this aquifer will be discussed from the following viewpoints: hydrogeology and land-use, injection-well design, variability of availability and water quality and usage.
A Bayesian approach for thermal history reconstruction in basin modeling
Authors: Licciardi Andrea , Gallagher Kerry , Clark Stephen Anthony
Published: March 2020

Vitrinite reflectance and apatite fission track) and borehole data (bottom hole temperature and porosi ty) for thermal history reconstruction in basin modeling.  The approach implements a trans-dimensional and hierarchical Bayesian formulation with a reversible jump Markov chain Monte  Carlo (rjMcMC) algorithm. The main objective of the inverse problem is to infer the heat flow history below a borehole given the data and a set of geological constraints (e.g. stratigraphy , burial histories and physical properties of the sediments).  The algorithm incorporat es an adaptive, data-driven parametrization of the heat flow history, and allows for automatic estimation of relative importance of each data type in the inversion and for robust quantification of parameter uncertainties and trade-offs. In addition, the algorithm deals with uncertainties on the imposed geological constraints in two ways. First, the amount of erosion and timing of an erosional event are explicitly treated as independent parameters to be inferred from the data. Second, uncertainties on compaction parameters and surface temperature histo ry are directly propagated 
into the final probabilistic solution.
Isotopomer approaches to the detection of anaerobic oxidation of natural gas hydrocarbons
Authors: Gilbert Alexis , Julien Maxime , Yoshida Naohiro , Ueno Yuichiro
Published: March 2020

Hydrocarbons are the main constituents of natural gas. Their chemical and isotope abundance is a window to biogeochemical processes occurring in the subsurface. Stable isotopes of natural gas hydrocarbons are traditionally measured through compound-specific isotope analysis (CSIA) where each hydrocarbon is separated before its isotope ratio is determined.

Recently a variety of methods have been developed to determine position-specific isotope composition of propane, the first hydrocarbon with two distinct isotopomers: central and terminal [1][2][3][4]. The relative abundance of propane isotopomers (e.g. Δ13Ccentral = δ13Ccentral - δ13Cterminal) is a promising tool for tracing sources and sinks of hydrocarbons in natural gas reservoirs. In particular, anaerobic oxidation of propane starts with a fumarate addition at the central position, which is expected to lead to a specific enrichment of the central 13C-isotopomer of the remaining propane.

We measured Δ13Ccentral values of propane throughout the course of its oxidation by bacteria BuS5 [5] and showed that the isotope fractionation is located mainly on the central position, which differs from the signature expected for thermogenic evolution [6]. The approach has been used to detect anaerobic oxidation of propane in several natural gas reservoirs: Southwest Ontario (Canada), Carnarvon Basin (Australia), Michigan (USA) [6], and more recently Tokamachi mud volcano in Japan [7]. In addition, isotopomers of n-butane and i-butane analysed using the same technique allows gaining insights into the mechanism of their microbial oxidation.

The isotopomer approach presented here can thus shed light on the fate of natural gas hydrocarbons. In combination with clumped isotope measurements of methane and ethane, the approach can provide unprecedented information regarding carbon cycling in the subsurface.

 

[1] Gilbert et al., 2016 GCA v177, p205

[2] Piasecki et al., 2016 GCA v188 p58

[3] Gao et al., 2016 Chem Geol. v435, p1

[4] Liu et al., 2018 Chem Geol. v491, p14

[5] Kniemeyer et al., 2007 Nature v449, p898

[6] Gilbert et al., 2019 PNAS v116, p6653

[7] Etiope et al., 2011 Appl. Geochem. v26, p348
A concept of hybrid terrestrial gravimetry and cosmic ray neutron sensing for investigating hydrological extreme events
Authors: Reich Marvin , Güntner Andreas
Published: March 2020

While studies on hydrological extremes, and floods in particular, usually take a retrospective approach, the German Helmholtz initiative MOSES (Modular Observation Solutions for Earth Systems) aims at understanding extreme events by observing the flood generation processes directly where they occur: in-situ and during the event. As part of this framework, we present a new concept of monitoring regional water storage changes by combining event-based ad-hoc field campaigns with continuous monitoring, using terrestrial gravimetry for total water storage variations and cosmic ray neutron sensing for near-surface soil moisture variations. In this concept, a key role is taken by a continuously monitoring gravimeter station: the gPhone solar cube. This station is energy self-sufficient and easily deployable at any remote location, hosting a gPhoneX, a full weather station, a GNSS antenna and receiver and a cosmic ray neutron probe. The purpose of this station is i) to provide data describing the longer term hydrological dynamics of the study area including the pre-event conditions and ii) to serve as the reference station for the gravity field campaigns during the event. These field campaigns, triggered by forecasts of extreme weather events, are carried out at least prior and after the event on a network of points across the study site. The locations are chosen with respect to the size of the area of interest, topography and travel times between the points. Measurements at each point include relative gravity with two CG-6 instruments, absolute gravity with a Muquans atom quantum gravimeter (AQG) and near-surface soil moisture using three cosmic ray neutron probes in a mobile rover setup. The same routine is strictly repeated at each point to assure uttermost comparability of the measurements. The AQG is also used to calibrate the permanently installed gPhoneX and, thus, to use the gravity reference station for correcting the high instrumental drift of the CG6 gravimeters. The monitoring concept is expected to be transferable to all areas where a similar interest in water storage dynamics at event time scales is strived for.
Linking the Anatolian microplate rigid motions to the 1999 Mw = 7.5 Izmit earthquake rupture
Authors: Martin de Blas Juan Ignacio , Iaffaldano Giampiero , Calais Eric
Published: March 2020

It is typically assumed that the occurrence of large earthquakes along the margins of tectonic plates does not impact on their rigid motions. However, for tectonic units of small size (i.e. for microplates), the viscous resistance at the plate base, and thus the torques needed to change their rigid motions, are significantly smaller than those needed for medium/large-size plates. In fact, a recent study that makes use of numerical simulations of synthetic microplates indicates that it is theoretically possible to link the temporal evolution of geodetically-observed microplate motions to the buildup and release of stresses associated with the earthquake cycle.

Here, we focus on the motion of the Anatolian microplate. We extract its rigid motion from GPS time series spanning the time around the 1999 MW = 7.5 Izmit earthquake. We select those GPS stations that are sufficiently away from plate boundaries, such as the North Anatolian Fault, the East Anatolian Fault and the Western Anatolia Extensional Province. Then, we attempt linking the temporal evolution of the Anatolian microplate rigid motion to the stresses associated with the 1999 MW = 7.5 Izmit earthquake rupture. The novelty of our approach lies in the fact that, in contrast to current models of the earthquake cycle, we connect earthquake stresses to changes in plate rigid motions and not to the crustal deformation in the vicinity of earthquake-prone faults.
Effects of Flow Regime on DOM Retention in Soils: Continuous Flow vs. Flow Interruption
Authors: Carstens Jannis Florian , Guggenberger Georg , Bachmann Jörg
Published: March 2020

Dissolved organic matter (DOM) is one of the most mobile components of the global carbon cycle. Corresponding transport processes in the environment have received plenty of attention in the context of carbon sequestration as well as the mobility of DOM-associated contaminants.

However, most previous transport studies have been conducted exclusively under continuous flow conditions, which are not comparable to real water flow characteristics in soil. The present study aims to address that gap in knowledge by systematically assessing the effect of defined flow interruption phases on the retention of DOM.

For that, the breakthrough behavior of DOM as affected by phases of flow interruption was investigated in an increasingly complex system of solid matrices rich in oxide mineral coatings: goethite coated quartz sand, disturbed Cambisol subsoil, and undisturbed Cambisol subsoil. The classic DLVO and extended DLVO (XDLVO) models including Lewis acid—base parameters were applied based on measurements of sessile drop contact angles and zeta potentials.  

DOM retention was increasing with the duration of flow interruption, and retention was considerably higher in the soils than in goethite coated sand. After 112 hours of flow stagnation, DOM release from the soils was reduced to 16 to 22 % as compared to continuous flow conditions. The retention in the different solid matrix materials was well correlated with the respective amounts of oxalate and dithionite extractable oxide mineral phases. The DLVO model was capable of correctly predicting the mobility of DOM in goethite coated sand, but not in the soils, due to the fact that soil surface charge heterogeneities could not be measured. The XDVLO model predicted short-range hydrophilic repulsive interactions that may have contributed to the distinct tailing of the DOM breakthrough curves.

We conclude that the significant DOM retention during phases of flow stagnation phases shows that more complex flow regimes need to be considered in order to assess the mobility of DOM in soils. In fact, many previous studies excluding phases of flow stagnation likely overestimated the mobility of DOM in the environment.
Statistical study of foreshock transients in a global hybrid-Vlasov magnetospheric simulation
Authors: Tarvus Vertti , Turc Lucile , Battarbee Markus , Blanco-Cano Xochitl , Kajdic Primoz , Suni Jonas , Alho Markku , Dubart Maxime , Ganse Urs , Grandin Maxime , Johlander Andreas , Pfau-Kempf Yann , Papadakis Konstantinos , Palmroth Minna
Published: March 2020

Upstream of Earth's bow shock lies the foreshock, a region permeated by bow shock-reflected electrons and ions propagating against the incoming solar wind. The interaction between the reflected ions and the solar wind leads to instabilities, which generate Ultra Low Frequency (ULF) waves in the foreshock. Another feature of the foreshock are various propagating transient structures. A particular type of transients are foreshock cavitons, which are characterized as simultaneous depressions of plasma density and magnetic field bounded by edges where these parameters are enhanced.
    Cavitons are proposed to form as a consequence of the non-linear evolution of two ULF wave types. They are carried by the solar wind towards the shock, but have been found to propagate sunward in the solar wind rest frame. Studies have shown that cavitons can accumulate reflected suprathermal ions inside them as they approach the bow shock, causing significant heating and bulk flow deflection in their interiors. These signatures resemble those of Hot Flow Anomalies (HFAs), transients which are associated with interplanetary magnetic field (IMF) discontinuities interacting with the bow shock. As the evolution of cavitons is independent of IMF discontinuities, the hot, evolved transients are classified as spontaneous HFAs (SHFAs). SHFAs arriving to the shock have been found to cause perturbations to the shock surface and the magnetosheath downstream of it.
    In this work, a numerical statistical study of cavitons and SHFAs is conducted with Vlasiator, a global hybrid-Vlasov code. Individual transients are tracked, allowing us to examine their formation rate, propagation characteristics and evolution in addition to their physical properties. Our results show that cavitons and SHFAs form in a uniform region near the bow shock, and there is a distinct distance to the shock within which cavitons can become SHFAs. The density and magnetic field depressions inside cavitons appear well correlated, although shallow compared to spacecraft measurements. We find that both transient types propagate sunwards in the solar wind rest frame, agreeing with earlier studies. Our statistical data set allows us to calculate the propagation velocity, which shows a similar value for all tracked transients. Our results also suggest that the velocity has a southward component. 
Air pollution and cloud-interaction over Europe in 1985 and today
Authors: Schrödner Roland , Genz Christa , Heinold Bernd , Baars Holger , Henning Silvia , Costa Surós Montserrat , Sourdeval Odran , Carbajal Henken Cintia , Madenach Nils , Tegen Ina , Quaas Johannes
Published: March 2020

Aerosol concentrations over Europe and Germany were simulated for the years 1985 and 2013 using the aerosol-chemistry transport model COSMO-MUSCAT. The aerosol fields from the two simulations were used in a high-resolution meteorological model for a sensitivity study on cloud properties. The modelled aerosol and cloud variables were compared to a variety of available observations, including satellites, remote sensing and in-situ observations. Finally, the radiative forcing of the aerosol could be estimated from the different sensitivity simulations.

Due to reduction of emissions the ambient aerosol mass and number in Europe was strongly decreased since the 1980s. Hence, today’s number of particles in the CCN size range is smaller. The HD(CP)2 (High Definition Clouds and Precipitation for Climate Prediction) project amongst others aimed at analysing the effect of the emission reduction on cloud properties.

As a pre-requiste, the aerosol mass, number, and composition over Germany were simulated for 1985 and 2013 using the regional chemistry-transport-model COSMO-MUSCAT. The EDGAR emission inventory was used for both years.

The model results were compared to observations from the two HD(CP)2 campaigns that took place in 2013 (HOPE, HOPE-Melpitz) as well as the AVHRR aerosol optical thickness product, which is available from 1981 onwards. Despite the fact, that emissions of the 1980s are very uncertain, the modelled AOD is in good agreement with observations. The modelled mean CCN number concentration in 1985 is a factor of 2-4 higher than in 2013.

Within HD(CP)2, the ICON weather forecast model was applied in a configuration allowing for large-eddy simulations. In these simulations, the time-varying CCN fields for the year 1985 and 2013 calculated with COSMO-MUSCAT were used as input for ICON-LEM. In the present-day simulation, the cloud droplet number agrees with observations, whereas the perturbed (1985) simulation does not with droplet numbers about twice as high as in 2013. Also, for other cloud variables systematic changes between the two scenarios were observed.
Characteristics and Fracture Pattern within the Basement and Cenozoic Rocks and Implication to Reservoir Potential, Red Sea, Midyan Region, NW Saudi Arabia.
Authors: Abdullatif Osman , Osman Mutasim
Published: March 2020

Exploration work has indicated reservoir potential and targets within the Pre-Cambrian Basement and associated sedimentary succession in the Saudi Arabia  and surrounding areas in the Arabian Plate. Understanding of fracture, characteristics, and distribution in petroleum basins are essential to improve exploration and production. Fractures are usually the main source for porosity and permeability within basement rocks and it controls the fluid flow. Usage of field outcrop analog studies, are very valuable for estimating the fractures distribution in the subsurface. We conducted an integrated outcrop-based study of the fracture pattern at Midyan Region, NW Saudi Arabia for the aim of identifying the fracture types, pattern and distribution on the Pre-Cambrian Basement rocks and associated Cenozoic sedimentary rocks in the region. The approach and methods used included integrated Landsat analysis and interpretation supported by outcrop based high-resolution observation, mapping and measurements of the fracture within the Basements and the Red Sea Cenozoic sedimentary succession. The Midyan Region has evolved through complex tectonic, structural history where four rifting phases have been reported that associated with several distinctive silici-clastic and carbonate facies and paleoenvironments. The Landsat and outcrop data measurements and analysis of fractures revealed characteristic pattern that generally show NW, NE, NS and EW trends. Some of these trends show similarity to fracture patterns associated with the Najid fault system and the also those associated with the Red Sea tectonic in Midyan region. Moreover, the fracture types within the Cenozoic outcropping rocks tend to correlate with those within the Pre-Cambrian Basement rocks. Fracture distribution was observed also cutting through reservoirs/ seals outcrop equivalents to the subsurface in Midyan region. Integration of outcropping results obtained in this study with subsurface geological and geophysical data and faults and fracture pattern data might provide guide for comparison and enhances prediction for identifying fractured reservoir potential targets, hydrocarbon migration pathways, trapping mechanisms, fracture distribution and modeling.
Influences of River Discharge Variation and Tidal Asymmetry on the Spatial Evolution of the Turbidity Maximum Zone in Yangtze Estuary
Authors: Dong Ping , Shi Huabin
Published: March 2020

The Yangtze estuary is characterized by its extremely high suspended sediment concentration (SSC) and the extensive turbidity maximum zone (TMZ). The estuary is physically forced by an upstream river discharge seasonally varying in a wide range of 6000 – 92000 m3/s and semidiurnal-diurnal mixed tides with the tidal range up to 5 m. The influences of the seasonal and interannual variations in the upstream river discharge and the tidal asymmetry on the location of the Yangtze TMZ are numerically investigated with a two-dimensional depth-averaged model. Sensitivities of SSC and hence the location of TMZ to the bottom shear stress, bed erodibility, and the sediment settling velocity are studied. The spatial and temporal evolutions of the TMZ position in the cases of various upstream river discharges with different monthly, seasonal and interannual variations are simulated and discussed. The effects of the M2/M4-induce tidal asymmetry on the TMZ position and those of the interactions between the eight main astronomical tides (M2, S2, N2, K2, K1, O1, P1, and Q1) are compared. It is shown that the M2/M4-induce tidal asymmetry plays a critical role in the formulation of TMZ in the downstream of the South Branch of Yangtze estuary, while the interactions between the eight main astronomical tides have more significant effects on the TMZ location in other areas of Yangtze estuary such as the South and the North Passages.
The role of SOM and CaCO3 on soil aggregate development in reclaimed soils
Authors: Pihlap Evelin , Steffens Markus , Kögel-Knabner Ingrid
Published: March 2020

Soil organic matter (SOM) and extracellular polymeric substances (EPS) from biological processes are considered to be major contributors in aggregate formation. But there is limited knowledge on soil structural formation after reclamation – the step when SOM content is low and soil properties are mostly controlled by the parent material. In our study we used a chronosequence approach in the reclaimed open-cast mining area near Cologne, Germany to elucidate the development of soil structure and soil organic matter during initial soil formation in a loess material. We selected six plots with different ages of agricultural management after reclamation (0, 1, 3, 6, 12, and 24 years after first seeding). In each reclaimed field 12 spatially independent locations were sampled with stainless steel cylinders (100 cm3) at two depths in the topsoil (1-5 cm and 16-20 cm). Samples were wet sieved into four aggregate size classes of <63 µm, 63-200 µm, 200-630 µm and 630-2000 µm. Each aggregate size class was characterized by organic carbon (OC), total nitrogen (TN) and CaCO3 concentration. The chemical composition of the SOM of selected samples was characterized using solid-state 13C NMR spectroscopy.

Wet sieving into aggregate size classes showed different trends along the chronosequence. Contradicting relation between CaCO3 and OC contribution to aggregate size classes display two different mechanisms on soil aggregate formation in young loess derived soils. CaCO3 influenced aggregation predominantly in finer aggregate size classes, where the highest concentration and contribution was measured. SOM, on the other hand, played an important role on formation of large macro-aggregates after organic manure application in year 4. Furthermore, the loss of total OC after year 12 was connected with the loss of OC contributing to the largest aggregate size class. Our findings reveal that SOM and CaCO3 role on stabilizing aggregates is not equally distributed and is aggregate size class dependent.
Improvement of Tropical Cyclone Track Forecast over the Western North Pacific Using a Machine Learning Method
Authors: Kim Kyoungmin , Cha Dong-Hyun , Im Jungho
Published: March 2020

 The accurate tropical cyclone (TC) track forecast is necessary to mitigate and prepare significant damage. TC has been predicted by the numerical models, statistical models, and machine learning methods in previous researches. However, those models are separately used for TC track forecast, and historical data with satellite images were used as input variables for machine learning without forecast data from numerical models. In this study, we corrected the TC track forecast of a numerical model by artificial neural network (ANN). TCs that occurred from 2006 to 2015 over the western North Pacific were hindcasted by the Weather Research and Forecasting (WRF) model, and all categories of TCs except for tropical depression (i.e., tropical storm, severe tropical storm, and typhoon) from June to November were included in this study. We evaluated the performance of TC track forecast in terms of duration, translation speed, and direction compared with the best track data. The simulated positions of TCs at 24-hour, 48-hour, and 72-hour forecast lead time were used as variables for training and testing ANN. To optimize the number of neurons in ANN, simulated TCs were divided into two parts; TCs in 2006-2014 for ANN optimization and those in 2015 for a blind test. Also, the output selection method based on the forecast error of the WRF was applied to exclude the outlier of ANN results. By applying the output selection, the forecast error of ANN was further reduced than that of the WRF. As a result, ANN with the output selection method could improve TC track forecast by about 15% compared to the WRF. Also, the effect of ANN tended to increase when the forecast error of the WRF was large. The output selection method was particularly effective by excluding outliers of ANN results when the forecast error of the WRF was small.

※ This research was supported by Next-Generation Information Computing Development Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT (NRF-2016M3C4A7952637).