bluuebunny/crossref_metadata_2025 huggingface dataset:
Future water supply and demand in the Peruvian Andes: assessment and implications
Authors: Wade Andrew J. , Rodda Harvey J.E. , Branch Nicholas P. , Bruzzone Marcos , Herrera Alex , Araujo-Feriera Francisco , Meddens Frank M. , Walsh Douglas A.H. , Lane Kevin
Published: March 2020

The aim of the ACCESS project is to help assess the impact of climate change on socio-economic development in the Peruvian Andes, focused on the Ancash region, and to help identify adaptation strategies. As part of this larger effort, we are aiming to understand how climate change will impact: water availability and quality; farming, lives and livelihoods; and to work with local communities to plan adaptation strategies. The current water supply and demand in two catchments in the Cordillera Blanca and two in the Cordillera Negra is being assessed to understand the background water context in contrasting glaciated and non-glaciated landscapes. Based on detailed surveys of the ancient and modern waterscapes led by South American archaeologists, supplemented by more recent data from hydrological measurement and ethnographic surveys and discussions with local communities, a nuanced picture is emerging of how communities have adapted to past and current climate conditions, and potential solutions are being co-developed with the local communities to maintain and improve livelihoods in situations with low rainfall in the Negra and glacial retreat in the Blanca. Crop water demand during the dry season in the Rio Ancash (114 km2) catchment has been assessed using the CROPWAT model and local climate and crop survey data, and the present-day water supply assessed through the gauging of rivers and irrigation canal flows, and measurement of water quality and isotopes. Preliminary results, for the Rio Ancash, suggest the amount of water available for dry season irrigation on the mid-slopes is approximately 70 mm over the cropped area (57 km2) which appears to be less than the crop water demand, though this estimate may change as more data is processed. Initial climate projections suggestion an increase in water as the glaciers melt until around 2050. The dry season crop water demand and supply beyond 2050 is currently being estimated.
Thermal Infrared Imaging of Sea Ice During the MOSAiC Expedition
Authors: Thielke Linda , Spreen Gunnar , Huntemann Marcus
Published: March 2020
Schupy: a python package for modeling and analyzing Schumann resonances
Authors: Bozoki Tamas , Satori Gabriella , Pracser Erno , Bor Jozsef , Szabone Andre Karolina , Rodríguez-Camacho Jesus , Dalya Gergely , Neska Mariusz
Published: March 2020

Schupy is an open-source python package aimed at modeling and analyzing Schumann resonances (SRs), the global electromagnetic resonances of the Earth-ionosphere cavity resonator in the lowest part of the extremely low frequency band (<100 Hz). Its very-first function forward_tdte applies the solution of the 2-D telegraph-equation introduced recently by Prácser et al. (2019) for a uniform cavity and is able to determine theoretical SR spectra for arbitrary source-observer configurations. It can be applied for modeling both the amplitude and phase of extraordinarily large SR-transients and the power spectral density of SRs excited by incoherently superimposed lightning strokes within an extended source region.

In this contribution, test results of planned new functionalities of the package are presented. A new function aims at removing sections of the measured data, e.g. Q-bursts, which bias spectral characteristics of  natural “background” electromagnetic noise. This way, PSD will be calculated from a sanitized time series. Other new functions are introduced for determining the spectral parameters (amplitude/intensity, frequency, Q-factor) of SR modes using different approaches, i.e., symmetrical and asymmetrical Lorentzian fitting, complex demodulation, and the weighted average method. We would like to encourage the community to join our project in developing open-source modeling and signal analyzing capacities for SR research as part of the schupy package.

 

 
Short-term morphological changes of multiple intertidal bars on macrotidal beaches: from seasonal to storm-scales.
Authors: Biausque Melanie , Grottoli Edoardo , Jackson Derek , Cooper Andrew
Published: March 2020

DGPS surveys were undertaken on two beaches of Dundrum Bay (east coast of Northern Ireland, Co.Down, U.K.) and analysed to investigate the short-term morphodynamics of a multiple intertidal bar (‘ridge and runnel’) system, as part of the INTERREG MarPAMM project. Ballykinler (east) and Murlough beach (west) are medium to coarse sand environments subjected to short waves and macrotidal conditions. Since April 2019 (ongoing), monthly surveys consisting of 14 cross-shore profiles and 2 intensive sections (in total) were carried out. Hydrodynamic conditions were extracted from the model WaveWatch3 (WW3) run by Ifremer (France) at a node located offshore of the bay. Intertidal bars were well-developed along Murlough beach (profiles 3 to 11) at the beginning of the experiment, with an increase in the complexity of ridges and runnels morphology toward the inlet (profile 12). In contrast, intertidal bars were only well developed in the western end of Ballykinler beach (profiles 13 and 14) and gradually disappeared toward the eastern end (profiles 15 and 16).

 

Preliminary results from the summer season show no measurable morphological change to significant accretion and onshore migration of the bar crest with low to moderate hydrodynamic conditions. However, there is a strong alongshore variability in the bay, with response to the summer season and is recorded not only between Ballykinler and Murlough beach, but also along Murlough beach. By contrast, the winter season is characterised by a decrease of bar amplitude due to an expansion of the bars wavelength, and in some cases, an onshore migration of the bars crest (mostly noticeably for Ballykinler). The winter season is, however, highly dependent on storm conditions. During the period of November to mid-December 2019 there were 4 storms including Storm Atiyah, and a signature of those highly energetic conditions was recorded in the beach morphology.

 

Depending on the location along the bay, ridges and runnels underwent bar crest erosion and sediment deposition into the runnels leading to a flattering of the profile, or cross-shore bar migrations.  Calm summer conditions, therefore, appear favourable for ridge accretion and onshore migrations, while energetic winter conditions seem to actively drive bar erosion and profile flattening. An alongshore variability in Dundrum Bay is a response to both seasonal and event conditions and is demonstrated by the results to date. This variability is probably due to wave orientation, wave energy dissipation and wave reflection linked to both offshore and nearshore bathymetry. The shape, position and number of the ridges and runnels should therefore play a key role in the energy dissipation depending on the tidal phase.
Dynamic and energetic constraints on the modality and position of the intertropical convergence zone in an aquaplanet
Authors: Adam Ori , Gerstman Hilla
Published: March 2020

The tropical zonal-mean precipitation distribution can vary between single and double peaks, which are associated with intertropical convergence zones (ITCZs). Here, the meridional modality and the sensitivity to hemispherically-asymmetric heating of tropical precipitation is studied in an idealized GCM with parameterized wind-driven ocean energy transport (OET). In the idealized model, transitions from unimodal to bimodal distributions are driven by equatorial ocean upwelling and cooling which inhibits equatorial precipitation. For sufficiently strong cooling, the circulation bifurcates to anti-Hadley circulation (AHC) in the deep tropics, with a descending branch near the equator and off-equatorial double ITCZs. The intensity of the AHC is limited by a negative feedback: the AHC drives westerly surface winds which balance the easterly stress (and hence equatorial upwelling) required for its maintenance. The modality of the precipitation affects the response to asymmetric heating: For weak ocean stratification, OET damps shifts of the tropical precipitation centroid but amplifies shifts of precipitation peaks. For strong ocean stratification, which leads to double ITCZs, asymmetric heating leads to relative intensification of the ITCZ in the warming hemisphere, but the positions of the double ITCZs are insensitive to changes in the asymmetric heating and ocean stratification. The dynamic feedbacks of the coupled system damp the slope of the atmospheric energy transport (AET) near the equator. This justifies a cubic root relation between the cross-equatorial AET and the position of the ITCZ, which captures migrations of the ITCZ significantly better than the commonly-used linear relation.
Is Coulomb stress the best choice for aftershock forecasting?
Authors: Sharma Shubham , Hainzl Sebastian , Zöller Gert , Holschneider Matthias
Published: March 2020

The Coulomb failure stress (CFS) criterion is the most commonly used method for predicting spatial distributions of aftershocks following large earthquakes. However, large uncertainties are always associated with the calculation of Coulomb stress change. The uncertainties arise due to non-unique slip inversions and unknown receiver fault mechanism. Especially for the latter, uncertainties are highly dependent on the choice of the assumed receiver mechanism. There are two ways of defining the receiver faults, either by predefining fault kinematics by geological constraints, or by calculating optimally oriented planes, both ways are pretty unrealistic as real aftershocks show variable rupture mechanisms. Recent studies have proposed an alternative method based on deep learning to forecast aftershocks. Using a binary test (aftershocks yes/no), it has been shown that their method as well as alternative stress values, such as maximum shear or the von-Mises criteria, are more accurate and reliable than the classical CFS criterion with predefined receiver mechanism.

Here we use 351 slip inversions from SRCMOD database to calculate Coulomb failure stress on a layered-half space using variable receiver mechanisms as well as proposed alternative stress metrics. We also perform tests for different magnitude cut-offs, grid size variation, and aftershock duration to verify the use of ROC analysis for ranking of stress metrics. The observations suggest that introducing a layered-half space does not improve the stress maps and ROC curves. However, magnitude cut-off and aftershock duration does effect the efficiency of stress metric in a way that larger magnitudes and shorter aftershock durations are forecasted efficiently. Two alternative statistics based tests i.e. log-likelihood and information gain tests using rate-based forecasts (non-binary) are also performed to compare the ability of metrics to discriminate the regions with and without aftershocks. The results suggest that simple methods of stress calculations perform better than the classic Coulomb failure stress calculations.
Long-term measurements (2010–2019) of carbonaceous aerosol at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia
Authors: Mikhailov Eugene , Ivanova Olga , Vlasenko Sergey , Nebos’ko Evgeniy , Andreae Meinrat , Pöschl Ulrich
Published: March 2020

The Siberian forests cover about 70% of the total area of the Eurasian boreal forest and are an important factor controlling global and regional climate. Forest fires and biogenic emissions from coniferous trees and forest litter are the main sources of carbonaceous aerosols emitted into the atmosphere over boreal forests. Typically, two classes of carbonaceous aerosol are commonly present in ambient air – elemental carbon (EC) (often referred to as black carbon or soot) and organic carbon (OC). Both OC and EC are important agents in the climate system, which affect the optical characteristics and thermal balance of the atmosphere both directly, by absorbing and scattering incoming solar radiation, and indirectly, by modifying cloud properties.

In 2010, a filter-based sampler was mounted at the background ZOTTO station (60.8º N and 89.4 º E; 114 m a.s.l.) for aerosol chemical analysis. We present here the time series of carbonaceous aerosol data measurements for 10 years (2010 -2019). We investigate the seasonal variations in PM, EC, and OC. These data are supplemented by measurements of aerosol absorption (PSAP) and scattering (TSI 3563) coefficients.  We analyze polluted, background and near-pristine periods, as well as the most pronounced pollution events and their sources, observed over the entire sampling campaign.

We also present ground-based measurements of aerosol-cloud condensation nuclear (CCN) properties and hygroscopicity parameter values obtained from the CCN dataset.  A method for assessing the condensation properties of aerosols from satellite measurements based on the data of the VIIRS multichannel radiometer installed on the polar satellite Suomi (USA) has been implemented. The CCN parameters of aerosol particles determined from satellite datasets have been compared with those obtained from ground-based measurements.

Acknowledgments. This work was supported by the Russian Science Foundation (grant agreement no. 18-17-00076) and Max Planck Society (MPG).
Detailed Spectral Analysis of Askja 2014 Landslide Area: From Satellites to the Ground-based Measurements
Authors: Marzban Pouria , Mueller Daniel , Klos Friederike , Hildebrand Constantin , Bredemeyer Stefan , Witt Tanja , Walter Thomas R. , Chabrillat Sabine
Published: March 2020

Abstract:

A major landslide occurred in 2014 on the east flank of the inner Askja caldera, Iceland, causing massive material redistributions and a tsunami hazard that affected even opposite shores of the caldera lake. The landslide has left a scar on the caldera wall, and was followed by mud flows, depositing mixed materials and un-roofing hydrothermally active sites. In an attempt to analyze the lithological and geomorphological consequences of the 2014 Askja landslide, we have realized a series of unmanned aerial system (UAS) surveys 2015-2019 carrying different sensors. From these drone campaigns we investigated the RGB, RedEdge, Near Infrared and thermal Infrared imagery. In addition, ground-based hyperspectral measurements in the wavelength range 350-2500 nm were acquired in 2019 with a field spectroradiometer to get more detailed spectral information of the surface materials. Here we proposed a geo-data-science approach to map and identify different types of deposits and structures by using Principal Component Analysis (PCA) and classification approaches. Specifically, we tested different supervised and unsupervised classification methods to identify the different types of materials found in the landslide area. For the supervised classification approaches, we defined regions of interest (ROI) to train the classifier and to detect those regions with similar patterns and materials. At the end, we can clearly distinguish 5-6 different classes in the UAS data and compare to ground-based spectral and thermal infrared signals. Results suggest that the 2014 landslide source region is composed of a mixed material class, with sharp contrasts in the north, reaching the lake in the west. This re-deposited material is located in an area of hydrothermal alteration and also encircled by the material class associated with thermal anomalies. By comparing the results from the classifications to the in-situ spectral measurements, we were able to further interpret on the involved types of materials and the degree of hydrothermal alteration. At distance to the landslide we find that the materials differ, signaling virtual absence of major landslides entering the lake and minor alteration. As the study demonstrates the success of the supervised classification approach for material mobilization in the inner caldera wall and identification of mixed and non-mixed materials, important implications for hazard assessment in the Askja caldera and elsewhere can be drawn.
GEANT 4 Simulation of the Helios E6 - Proton Contamination of Relativistic Electron Measurements
Authors: Hörlöck Malte , Heber Bernd , Marquardt Johannes
Published: March 2020

The Helios mission consisted of two almost identical spacecraft in highly elliptic orbits launched in 1974 (Helios A) and 1976 (Helios B). Until Parker Solar Probes first perihelion, Helios B was the first spacecraft to reach a distance of 0.29 AU to the Sun. One of its instruments is the Experiment 6 (E6) which was designed and built at the Christian-Albrechts-University Kiel in order to measure ions (protons up to iron) in the energy range of 1.3 MeV/nucleon up to several GeV/nucleon and electrons in the energy range from 0.3 to about 8 MeV. The instrument relies on the dE/dx-E and on the dE/dx-Cherenkov method for stopping and penetrating particles, respectively. Electrons are separated from ions by the signal in the first 100 µm thick solid state detector. Any particle that does not trigger this detector is identified as an electron. Since the solid state detectors are not working perfectly, a significant part of protons is identified as electrons. Here, we present a new method to correct the electron measurements for the cross talk based on detailed instrument simulations.
Assessing the role of internal ocean dynamics and external forcings on the decadal-scale predictability in the North Atlantic: a large ensemble analysis
Authors: Bellucci Alessio , Benassi Marianna , Gualdi Silvio , Mariotti Annarita
Published: March 2020

Understanding processes and mechanisms which contribute to decadal climate variability is a crucial step in the development of a reliable prediction system, and as such it constitutes an important segment of the activities carried forward by the EU-funded Horizon 2020 EUCP project.

Sea surface temperature (SST) variability in the North Atlantic is known to be a key source of decadal predictability for the Euro-Atlantic sector. However, the nature of the observed variability is at the core of a long-standing debate.

In this work, we investigate the origins of North Atlantic SST variability, focusing on a specific event: the mid-20th century (1940-1975) “warm-to-cold” transition. This event is particularly interesting as it represents a well documented decadal-scale fluctuation of the observed climate record and can be used as a suitable test-bed to evaluate the relative skill of initialized versus non-initialized (historical) climate simulations.

Several mechanisms and processes have been taken into account to explain the cooling in the middle of 20th century, ranging from a slowdown of the Atlantic Meridional Overturning Circulation (AMOC) to an increase in anthropogenic aerosol. Here the 1940-1975 transition is examined firstly in the NCAR Large Ensemble (NCAR-LENS), aiming to further explore the role of the possible drivers. Despite the lack of a realistic model state initialization, the NCAR-LENS shows some skill in capturing the North Atlantic SST transition, suggesting a non-negligible influence of the external forcing. Some lag between observations and model results is found, with the ensemble mean SST leading the onset of the observed transition by about ten years. This is consistent with previous studies, where some evidence was found of the driving role of anthropogenic aerosol and greenhouse gas forcing. In contrast, the simultaneous ocean dynamic response (AMOC) exhibits a large intra-member spread. This finding corroborates the hypothesis of a non-oceanic driver for the decadal-scale SST fluctuation. The same episode is then analysed in the NCAR Decadal Prediction Large Ensemble (NCAR-DPLE), which shares the same model code, configuration details, component resolutions, and external forcing datasets as for the non-initialized LENS ensemble. This allows a rigorous attribution of the relative roles of initialization, (mainly constraining the ocean-driven internal variability) and external forcing conditions on the overall skill in reproducing the Atlantic decadal variability, with clear implications for decadal predictability and predictions.

 
Subsurface investigation of the Terrace of the Elephants in the Angkor world heritage site using geophysical survey
Authors: Lee Kwangwu , Kim Kiju , Park Byungsuk , Kim Wooseok , Jeoung Jaehyeung
Published: March 2020

Geophysical survey methods are widely applied into not only underground water exploration and environmental pollution & civil engineering fields of the ground, but also in the archeological field such as exploration of the historic remains. The electrical resistivity tomography(ERT) and seismic surveys were conducted to determine the distribution of underground around the terrace of the elephants. ERT survey was conducted to investigate the natural geological distribution and artificial ground around the terrace of the elephants and seismic survey was conducted to find out the velocity distribution of the terrace of the elephants. ERT resulted in a difference in the traces of artificial ground composition around natural ground and terrace of the elephants. Geophysical survey could be used to infer the range and purpose of the underground composition of historic remains (KOICA Project Number: 2019-00065).
Emissions and ambient air concentrations of isoprene, monoterpenes and sesquiterpenes at a Northern wetland
Authors: Hellén Heidi , Schallhart Simon , Praplan Arnaud P. , Tykkä Toni , Aurela Mika , Lohila Annalea , Hakola Hannele
Published: March 2020

Wetlands cover an area of about 2% of the total land surface area of the world and are most common in the boreal and tundra zones. Northern wetlands are important sinks for carbon dioxide and sources of methane, but knowledge on their VOC emissions is very limited. Currently, we know that northern wetlands are high isoprene emitters (e.g. Holst et al., 2010), but very little is known on the emissions of other VOCs.

We have studied VOC emissions and their ambient concentrations at a sub-Arctic wetland (Lompolojänkkä) in Northern Finland, using an in situ TD-GC-MS. For the emission measurements, a dynamic flow-through FEP chamber was used.

Earlier studies have shown that isoprene is emitted from wetlands and it turned out to be the most abundant compound in the current study also. Monoterpene (MT) emissions were generally less than 10 % of the isoprene emissions, but sesquiterpenes (SQT) emissions were surprisingly high, exceeding MT emissions at all times. Both MT and SQT emissions were dependent on temperature.

Even with the higher emissions from the wetland, ambient air concentrations of isoprene were clearly lower than MT concentrations. This indicates that wetland was not the only source affecting atmospheric concentrations at the site, but surrounding coniferous forests, which are high MT emitters, contribute as well. In May concentrations of SQTs and MTs at Lompolojänkkä were higher than in earlier boreal forest measurements in southern Finland (Hellén et al., 2018). At that time, the snow cover on the ground was melting and soil thawing and VOCs produced under the snow cover, e.g. by microbes and decaying litter, can be released to the air. Daily mean MT concentrations were very highly negatively correlated with daily mean ozone concentrations indicating that vegetation emissions can be a significant chemical sink of ozone at this sub-Arctic area.

References

Hellén, H.et al. 2018, Atmos. Chem. Phys., 18, 13839-13863, https://doi.org/10.5194/acp-18-13839-2018.

Holst, T., et al. 2010, Atmos. Chem. Phys., 10, 1617-1634, https://doi.org/10.5194/acp-10-1617-2010.
Optimizing the potential of iron oxide-based tracers
Authors: Guzmán Gema , Ramos Azahara , Barrón Vidal , Gómez José A.
Published: March 2020

So far, it does not exist a set of tracers which fulfill all the characteristics for being an ideal sediment tracer such as, environmentally friendly, inexpensive or easily analysed (Zhang et al., 2001). For this reason, and in order to address some of the unsolved issues of water erosion processes, more research enquiring into the development of these soil and sediment tracers is needed.

Iron oxide-based tracers has been already tested in several water erosion trials with satisfactory results (e.g. Guzmán et al., 2010, 2013, 2015). In 2015, three cascade plots with a different iron oxide (magnetite, hematite and goethite) each were set up in order to evaluate soil redistribution after the rainy season (Obereder et al., 2016). While these authors presented the total iron content of sediments after clorhydric acid extraction, the present study will show only the free iron content of soil and sediments using a different extraction method (CBC, citrate-bicarbonate-ditionite), as this method is more adequate in high iron content soils, as is our case.

The results depict the suitability of the CBD method extracting the three tracers with an average recovery rate of 0.7. The analysis of the iron content of soil and sediment samples indicates a relatively low movement of soil although showing significant statistical differences with background and mixture values. These results are in line with the ones detected by the magnetic susceptibility measurements. Further textural and visible spectrum analysis of the samples will allow to determine the possible selectivity factor and to discriminate qualitative and quantitatively hematite and goethite tracers, respectively.

References:

Guzmán et al. 2010. Catena, 82(2), 126-133.

Guzmán et al. 2013. Soil Science Society of America Journal, 77(2), 350-361.

Guzmán et al. 2015. Journal of hydrology, 524, 227-242.

Obereder et al. 2016. Geophysical Research Abstracts Vol. 18, EGU2016-2455-1. EGU General Assembly 2016.

Zhang et al. 2001. Soil Science Society of America Journal, 65(5), 1508-1515.
Flow-duration analysis in the context of preliminary design of small hydropower plants: from uncertainty assessment to regionalization
Authors: Ntemiri Kristiano , Pytharouliou Angelina , Ntemiroglou Christina , Tsoukalas Ioannis , Efstratiadis Andreas , Koutsoyiannis Demetris
Published: March 2020

The preliminary design of small hydropower plants is typically relied on empirically-derived flow-duration curves (FDCs). This approach allows for estimating characteristic quantities of interest, such as the mean annual energy production, the mean annual water volume captured by the turbines and the mean annual time of turbine operation. In this work, we aim to parameterize the daily FDCs in statistical terms, i.e. by fitting suitable distribution functions and express their uncertainty through confidence intervals. The fitting procedure emphasizes to the accurate representation of the main body of the distribution, since the high flows cannot be captured by hydropower plants without sufficient storage capacity, while the lower ones are reserved for environmental purposes. The parametric FDCs are next used to provide statistical predictions of the desirable design variables. The methodology is applied to a sample of Mediterranean catchments with different hydroclimatic and geomorphological characteristics. Based on the outcomes of this analysis, we also attempt to establish regional relationships, by associating key statistical and design quantities with lumped properties and hydrological signatures of the studied catchments.
Vertical interval dynamics of greenhouse gases in groundwater (Hesbaye chalk aquifer, Belgium)
Authors: Nikolenko Olha , Morana Cedric , Taminiau Bernard , Borges Alberto V. , Robert Tanguy , Goderniaux Pascal , Duvivier Maxime , Brouyѐre Serge
Published: March 2020

Increase in the concentration of greenhouse gases (GHGs) in the atmosphere threatens the existence of many ecosystems and their inhabitants. Agricultural activities contribute up to 70 % of total anthropogenic emission of nitrous oxide (N2O), one of the GHGs, which is characterized with the highest global warming potential and contributes to stratospheric ozone depletion. Our study presents the results obtained from the recent field and lab activities carried out in order to obtain better insight into the factors that define the presence of N2O in groundwater. Previous large scale investigations, performed in the Hesbaye chalk aquifer in Eastern Belgium, suggested that the concentration of N2O in the aquifer depends on different, possibly overlapping biochemical processes such as nitrification, denitrification and/or nitrifier-denitrification. This study explored the occurrence of biochemical stratification in the same aquifer and its impact on N2O production and consumption mechanisms. For this purpose low flow sampling technique was applied at different depth intervals to obtain better insight into the extent of oxic and anoxic zones and variability of concentrations of GHGs along the vertical profile. Collected groundwater samples were analyzed for the range of hydrochemical parameters as well as NO3-, N2O, H2O and B isotopes signatures and N2O isotopomers. Afterwards, rates of nitrification and denitrification processes were estimated based on short-term incubations of collected groundwater amended with NO3- and NH4+ compounds labeled with heavy 15N isotope. In addition, in order to characterize the dynamics of ongoing biogeochemical processes, polymerase chain reaction (PCR) tests for detection of the activity-specific enzymes in the aquifer were performed. Such studies help to clarify which conditions are more prone to the accumulation of high concentrations of GHGs in aquifers and better constrain models which estimate local and regional GHGs budgets.

Acknowledgments

This project has received funding from the European Union’s Horizon 2020 research and innovation  programme under the Marie Skłodowska-Curie grant agreement No 675120.
Vertical structure of the transport fluxes of aerosol and its precursors on the southwest transport pathway in the Beijing-Tianjin-Hebei region
Authors: Hu Qihou , Liu Cheng , Ji Xiangguang , Liu Ting , Zhu Yizhi
Published: March 2020

Haze pollution caused by atmospheric aerosols has become one of the most severe environmental problems in China, especially in the Beijing-Tianjin-Hebei (BTH) region. Air pollution is not caused by local emission and secondary formation of air pollutants, but also affected by transport from its surrounding areas. A number of studies with respect to the regional transport of air pollutants in the BTH region have been conducted based on surface observation. However, owing to the inhomogeneous vertical distribution of air pollutants and meteorological conditions, the vertical profiles of transport fluxes should be considered for a comprehensive understanding of regional transport. In this study, the vertical profiles of aerosol and its precursor indicators HCHO, NO2 and SO2 were observed by ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) at the Nancheng (NC) site in suburban Beijing on the southwest transport pathway. The profiles of the pollutants varied with seasons with more aerosols concentrated at the surface in the winter. Through potential source contribution function (PSCF) analysis, southwest transport pathway was determined as the main transport source region, particularly for air pollutants in the middle and upper boundary layer. The transport fluxes of air pollutants at each vertical layer on the southwest-northeast direction were estimated combining with wind field simulated by WRF-Chem modeling. The average fluxes of the measured pollutants from June 2018 to May 2019 during the southwest transport (from southwest to northeast) were all higher than those during the northeast transport (from northeast to southwest), indicating net input of pollutants to urban Beijing from southwest transport pathway. Except for northwest transport of aerosols, the other maximum transport fluxes occurred at high altitudes instead of at the surface. The proportions of surface flux in the column flux for all the species during southwest transport were higher than those during northeast transport. Surface observation would overestimate the relative contribution from urban Beijing to southwest pathway and underestimate the contribution from southwest pathway to urban Beijing. Southwest transport played an important role on the developing stage of aerosol pollution in urban Beijing in the autumn and winter, and this transport mainly occurred in the middle boundary layer.
Investigating a link between solar wind variability and atmospheric dynamics in polar regions
Authors: Edvartsen Jone , Maliniemi Ville , Nesse Tyssøy Hilde
Published: March 2020

Evidence are pointing to two potential links between solar wind forcing and atmospheric dynamics in polar regions. The chemical link follows from energetic particle precipitation (EPP) ionizing the higher atmosphere, leading to a production of nitrogen and hydrogen oxides (NOx and HOx), which later on participate in ozone destruction. This can lead to changes in the radiative balance of the atmosphere, followed by related changes in winds. The physical link is related to the interplanetary magnetic field (IMF) and its ability to modulate the global electric circuit (GEC), with a hypothesized link between changes in the GEC and polar tropospheric dynamics through cloud generation processes. By use of ERA-5 reanalysis data and OMNI near Earth solar wind magnetic field and plasma parameter data, we investigate these links with a multiple correlation analysis. Internal atmospheric variability is excluded before the analysis. Time period of the data is 1979-2018. Results concerning the chemical link show a significant negative correlation between EPP (geomagnetic activity index Ap used as a proxy) and pressure anomalies in the local winter inside the polar vortex. The anomaly, starting in the stratosphere, extends downwards to the surface in a matter of days. The results indicate a greater response in the north compared to the south. For the physical link, a significant correlation is seen between the IMF horizontal (By) component and lower tropospheric pressure in the south for certain months in local summer. There seems to be no correlation between the two indices, Ap and By, indicating that these mechanisms operate individually without aliasing between the two. These results imply that solar wind variability can potentially impact polar atmospheric dynamics during specific seasons in different ways. This can enhance our understanding on solar related atmospheric effects.
To link landscape pattern with soil erosion risk at watershed scale based on SPSM model in the loess hilly area
Authors: Chen Liding
Published: March 2020

Linking landscape patterns to specific ecological processes has been and will continue to be a key topic in landscape ecology. However, the traditional landscape pattern analysis by landscape metrics inspired by patch-matrix model (PMM) may be difficult to reach such a requirement, and thus landscape pattern analysis to denote the significance of ecological process is strongly hindered. To find conceptual and methodological innovations integrating ecological processes with landscape patterns is important. In this paper, we proposed a conceptual model, i.e., the source-pathway-sink model (SPSM) by defining the role of each landscape unit to a specific process before conducting landscape pattern analysis. The traditional landscape matrices derived from the patch-matrix model is visual- or geometrical-oriented but lack of linkage to ecological significance. The source-pathway-sink model is process-oriented, dynamic, and scale dependent. This model as a complementary to the patch-corridor-matrix model can provide a simple and dynamic perspective on landscape pattern analysis. Based on the SPSM model, a landscape index was developed in term of the process of soil erosion, and further testified by using on-site measurements. It was found the new landscape index based on SPSM is useful in evaluating the risk of soil erosion from landscape pattern at watershed. Finally, a case study was conducted in the loess hilly areas to define the risk area of soil erosion that will be useful for sustainable land use management and optimization in future.
Climate impact of the Drake Passage opening: lessons from a minimalistic laboratory experiment
Authors: Vincze Miklos , Bozóki Tamás , Herein Mátyás , Borcia Ion Dan , Rodda Costanza , Pálfy József , Nyerges Anita , Harlander Uwe
Published: March 2020

The differentially heated rotating annulus is a widely studied experimental set-up designed to model mid-latitude circulation in the atmosphere and the ocean. By installing an insulating "meridional" barrier in this cylindrical tank, one can construct a minimal model of the large-scale flow phenomena in the Southern Ocean with a closed Drake Passage, imitating the situation before the Eocene-Oligocene transition (EOT) ca. 34 million years ago. We find that in this "closed" case a persistent azimuthal temperature gradient emerges whose magnitude scales linearly with the "meridional" temperature contrast. Furthermore, seemingly contradicting paleoclimatic data, the presence of the barrier appears to yield lower values of "sea surface temperature" in the tank than those in the "opened" control experiments (whereas the actual opening of the passage coincides with a major cooling event). This difference points to the importance of the role ice-albedo feedback plays in an EOT-like transition, an aspect that is not captured in the laboratory setting. This idea appears to be confirmed by numerical simulations conducted in a medium complexity GCM, where the comparison of "closed" on "opened" configurations could be made both with and without sea ice feedback. These runs indeed yielded opposite effects on sea-surface temperature and are therefore consistent with both the laboratory experiment and the paleoclimate data. This finding may well be relevant for the better understanding of the actual EOT dynamics.
Completed in Spring 2020: AAGRG´s new recompilation of the Alpine gravity field
Authors: Götze Hans-Jürgen ,   AlpArray Gravity Research Group
Published: March 2020

The AlpArray gravity research group (AAGRG) focuses on compiling a homogeneous surface-based gravity dataset across the Alpine area, on creating digital data sets for Bouguer-, Free Air- and isostatic anomalies. In 2016/17 all ten countries around the Alps have agreed to contribute with point/gridded gravity data and/or gravity data processing techniques to recompilation of the Alpine gravity in an area from 2° East to 23° East and 50° North to 42° North. For this recompilation, the group was able to rely on existing national data. For the Ivrea zone in the western Alps, newly surveyed data were also integrated into the database.

The AAGRG decided to present the data set of the recalculated gravity fields on a 2 km x 2 km and 4 km x 4 km grid for the public. The final products will also include the calculated values for mass corrections of the measured gravity at each grid point. This allows users to use later customized densities for their own calculations of mass corrections between the physical surface and the ellipsoidal reference. The densities used are 2 670 kg/m3 for landmasses, 1 030 kg/m3 for water masses above and  -1 640 kg/m3 below the ellipsoid. The correction radius was set to the Hayford zone O2 (167 km). In the future, the calculation of long-distance effects of topography/bathymetry and its compensating masses (roots) are planned. The new Bouguer anomaly will be station completed (CBA) and compiled according to the most modern criteria and reference frames (both location and gravity). The concept of ellipsoidal heights implicitly includes the geophysical indirect effect. Atmospheric corrections are also considered. Special emphasis was put on the numerous lakes in the study area. They partly have a considerable effect on the gravity of stations that lie at their edges (for example, the rather deep reservoirs in the Alps). In the Ligurian and the Adriatic seas, ship data of the Bureau Gravimétrique International were used. Although not unproblematic, these data got the preference over satellite data.

 It is the aim of the work of the AAGRG to release a gravity database that can be used for high-resolution modeling, interdisciplinary studies from local to regional to continental scales, as well as for joint inversion with other datasets.
Impact of Lidar Data Assimilation on Analysis and Prediction of Low-level Wind Shears at Lanzhou Zhongchuan International Airport, China
Authors: Li Lanqian , Shao Aimei
Published: March 2020

Low-level wind shear could occur not only in rainy weather conditions but also in non-rainy weather conditions, which is dangerous to aircraft safety for its rapid changes in wind direction or velocity. Recently, dry wind shear occurred in non-rainy condition has drawn more and more attention. Rain-detecting Doppler radar has no capabilities in detecting dry wind shear occurred in non-rainy condition, while Doppler Lidar observations with higher spatial and temporal resolution provide valuable information for dry wind shear. For this, considering dry wind shear cases reported by pilots at Lanzhou Zhongchuan International Airport as study object, lidar observations (radial velocities) were assimilated along with surface data to improve the prediction skill of dry wind shear events.

All experiments were conducted with Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-VAR) system. Three-nested domains were employed with 1-km horizontal resolution in the innermost domain. The model was derived by the NCEP FNL data. Lidar data was processed and only assimilated in the innermost domain. Experimental results show that the low-level wind shear can not be found in the experimental results without lidar data assimilation, while lidar data assimilation experiment successfully represented wind shear small-scale characteristics and simulated radial wind pattern was close to lidar observation. In addition, assimilation cycles with short time intervals effectively improved simulation accuracy of wind shear events.
Beef veins record fluid overpressure during oil primary migration in source rocks
Authors: Wang Miao , Chen Yong , Steele-MacInnis Matthew
Published: March 2020

Bedding-parallel, fibrous calcite veins (commonly referred to as “beefs”) are widely developed within Eocene, lacustrine, laminated organic-rich source rocks in the Dongying Depression, Bohai Bay Basin, East China. Based on the study of vein petrography and fluid inclusions features, we demonstrate the vein was the product of hydrocarbon generation and expulsion from organic-rich shales. Consequently, the primary inclusions in the fibrous calcites recorded the fluid conditions during maturation of these source rocks. In most cases, the calcite-hosted primary inclusion assemblages are composed of the two-phase (oil + gas) hydrocarbon inclusions, with or without coexisting aqueous inclusions. Less commonly, the assemblages are made up of inclusions with only liquid hydrocarbon (i.e., monophase, high-density petroleum inclusions). In addition, many bitumen-bearing oil inclusions could also be observed in the fibrous calcite veins. By modelling the isochores of two-phase oil inclusions and coexisting aqueous inclusions, in light of the burial history for the basin, we conclude the fluid overpressure up to approximately twice (2x) the hydrostatic value (i.e., ~0.5–0.6x lithostatic) are the most common during the hydrocarbon generation and primary migration. The highest degrees of overpressure are recorded by the rare monophase petroleum inclusions. The resulting isochores of these highest density inclusions project to pressures that overlap with the lithostatic gradient. Thus, the monophase inclusions indicate pressures approaching and in some cases exceeding lithostatic. Our results indicate that fluids present during hydrocarbon generation and expulsion in organic-rich shales were indeed overpressured, but that lithostatic pressures were not the norm and evidently not a prerequisite for vein dilation, which means the fluid pressures during dilation of horizontal veins are not necessarily equal to the overburden throughout the history of the opening. This suggests that at least some of the vein dilation is accommodated and offset by concomitant narrowing of the adjacent wall rock laminae, likely by scavenging (dissolution/reprecipitation) of CaCO3 from the adjacent wall rock, owing to the positive pressure dependence of calcite solubility, and presence of organic acids as byproducts of hydrocarbon generation.
Indo-Atlantic plate accelerations and tectonic reorganisations in the Late Cretaceous: no need for plume-push forces
Authors: Perez-Diaz Lucia , Eagles Graeme , Sigloch Karin
Published: March 2020

Observations of the apparent links between plate speeds and the global distribution of plate boundary types have led to the suggestion that subduction may provide the largest component in the balance of torques maintaining plate motions. This would imply that plate speeds should not exceed the sinking rates of slabs into the upper mantle. Instances of this ‘speed limit’ having been broken may thus hint at the existence of driving mechanisms additional to those resulting from plate boundary forces. The arrival and emplacement of the Deccan-Réunion mantle plume beneath the Indian-African plate boundary in the 67-62 Ma period has been discussed in terms of one such additional driving mechanism. Its spatial and temporal coincidence with an abrupt speed-up of the Indian plate has led to suggestions that the arrival of plumes at the base of the lithosphere can introduce a push force capable of overwhelming entire circuits of plates and triggering plate tectonic reorganizations.

 

We challenge the occurrence of a pulse of anticorrelating accelerations and decelerations in seafloor spreading rates around the African and Indian plates and, with it, the proposal that plume-related forces in the Indian Ocean had a significant impact on the Indo-Atlantic plate circuit in late Cretaceous and Paleogene times. Using existing and newly-calculated high-resolution models of plate motion based on seafloor spreading data, we show that the increase in divergence rates previously documented for ridges bordering the Indian plate is artefactual. Records from spreading centers throughout the Indo-Atlantic plate circuit show an ubiquitous increase in plate divergence rates at 67-64 Ma, which is best explained in terms of a timescale error affecting chrons 29-28. Corrected for this error, the motion of the circuit’s plates show little change around Deccan times. Furthermore, we find that Post-Deccan reorganization of the Indo-Atlantic plate circuit can be explained in terms of long-term plate boundary evolution without the need to invoke a large additional plume push force in the 70-60 Ma period.
Hydrocarbon Accumulation Process in the Dawangzhuang Paleozoic Buried Hill Fields in the Jiyang Depression
Authors: Zhang Zhiqing
Published: March 2020

Abstract:The Dawangzhuang area as one of the favorable exploration areas for buried hills in the Jiyang Depression, experienced the complicated accumulation process. Based on the fluid properties and regional tectonic background, it can be briefly discussed oil migration and accumulation process in the Dawangzhuang paleozoic buried hill fields using the petrographic observation, microthermometry and abundance of hydrocarbon inclusions. The result shows that the Dawangzhuang area mainly experienced two stages of crude oil charging from the late Dongying Formation (27-25Ma) and the end of Guantao Formation (5Ma) to now. Moreover, the last charging is the most important in the Dawangzhuang buried hill field. The first charging occurred in the Ordovician in the end of Dongying formation, but was quickly destroyed and adjusted by fault activities. In the end of Guantao formation, crude oil migrated on a large scale and accumulated lately in the Ordovician and Carboniferous-Permian systems respectively when they entered buried hills through Da 1 fault from source center, forming the current oil distribution pattern.

Keywords：Chezhen sag; Paleozoic; buried hill field; fluid inclusion; accumulation process