bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of aerosol and NO2 vertical profiles derived from MAX-DOAS in four metropolises of China during 2019
Authors: Xing Chengzhi , Liu Cheng , Liu Haoran , Li Qihua , Tan Wei , Lin Hua , Ji Xiangguang , Zhu Pengcheng , Xu Heng , Liu Jianguo
Published: March 2020

Air pollution has become one of the major environmental problems around the world. It is particularly serious in China due to the rapid development of the economy and industrialization. Four ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) were performed in four metropolises of China during 2019. Beijing, Nanjing, Guangzhou and Chongqing are central cities of Beijing-Tianjin-Hebei region, Yangtze River Delta, Pearl River Delta and Sichuan basin, four major polluted areas of China, respectively. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) in these four cities were retrieved from MAX-DOAS. In order to understand the pollution characteristics in four major polluted areas during 2019, the averaged diurnal variation and seasonal variation of aerosol and NO2 in above four cities were performed. On the other hand, the differences of vertical structure of aerosol and NO2 in four cities were analyzed. In addition, the variation of PM2.5, PM10 and PM2.5/PM10 in above four cities during 2019 were analyzed, and it is helpful to understand the formation and source of haze occurred in the four major polluted areas. PM2.5/PM10 increasing when PM2.5 pollution became worse indicates that regional transport is the major pathway for haze. PM2.5/PM10 decreasing when PM2.5 pollution became worse indicates that primary emission and secondary chemistry are the major pathways for haze.
Using Unmanned Aerial Vehicle to Obtain Digital Images and Estimating In-Situ Soil Water Content
Authors: Wang Ching-Hsiung , Lin Hong-Ru , Chen Jyun-Lin , Huang Shao-Yang , Wen Jet-Chau
Published: March 2020

Soil water content (SWC) is a vital factor for soil sciences. Nowadays, there are many methods for estimating SWC, including the Time-domain reflectometry (TDR) and the Gravimetric method. Nevertheless, most of them may cause damages to soil structure and require a large workforce and resources. The optical method is a non-destructive and cost-efficient; therefore, recommended for SWC estimations.

This study analyses soil samples at the field site, as well as it uses aerial photo-shooting to obtain the digital image distribution of surface soil. Both soil samples and digital images were categorized into groups; 9 in total, depending on time parameters (one group equals one day). More specifically, the gravimetric method was selected for the SWC measurements in the laboratory, while the images were modified in such a way so to match the CIE 1931 XYZ color space resolution for further calculations. Then, comparing the CIE 1931 XYZ color space data with the Soil Water Content correlation of 9 groups by validation.

According to the findings, the sensitivity of CIE 1931 XYZ color space in SWC alternations is high. Additionally, it can be observed that the SWC result data of the model are similar to the SWC measurements; therefore, the CIE 1931 XYZ color space can be applied to agriculture and disaster prevention, and it is a cost-efficient method for SMC estimations, and it can provide several benefits.
MMS/Cluster joint measurements at the vicinity of the plasma sheet boundary layer
Authors: Le Contel Olivier , Retino Alessandro , Alexandrova Alexandra , Chust Thomas , Steinvall Konrad , Alqeeq Soboh , Canu Patrick , Fontaine Dominique , Dandouras iannis , Carr Christopher , Toledo Sergio , Fazakerley Andrew , Doss Natasha , Kiehas Stefan , Nakamura Rumi , Khotyaintsev Yuri , Wilder Frederick , Ahmadi Narges , Gershman Daniel , Strangeway Robert ,   Cluster/MMS team
Published: March 2020

On 28th of August 2018 at 5:30 UT, MMS and Cluster were located in the magnetotail at about 16 earth radii (RE). They both suddenly crossed plasma interfaces. Located in the post midnight sector, Cluster transitioned from a cold plasma sheet to a hot plasma sheet whereas MMS, located at 4 RE duskward of Cluster, transitioned from a similar cold plasma sheet to the lobe region via a very short period in a hot plasma sheet. At 05:50 UT MMS returned to a hot plasma sheet and detected a quasi-parallel earthward flow ~ 400 km/s and increased energetic ion and electron fluxes. We use measurements from both missions during this conjunction to describe the possible macroscale evolution of the magnetotail as well as some associated kinetic processes. In particular, we analyze fast and slow non linear electrostatic waves propagating tailward which are detected in the so called electron boundary layer as well as in the hot plasma sheet. We discuss their possible generation mechanisms and link with the large scale evolution of the magnetotail. Finally, we investigate possible effects related to the dawn-dusk asymmetry of the magnetotail.
BASALT – A Science-Based Mars Con-Ops Astronaut Field Simulation
Authors: Hamilton John ,   BASALT RESEARCH PROJECT team
Published: March 2020

BASALT (Biologic Analog Science Associated with Lava Terrains) was a NASA PSTAR funded field research program. The goal was to understand the habitability of terrestrial volcanic terrains as analog environments for early and present-day Mars.

A key objective was to merge the oftimes disparate field techniques and protocols of biologists, geologists and geochemists.   worked together on this project to understand microbial lifeforms, like bacteria, that grow on these rocks and the factors that allow them to thrive.

Deployments of 21 days at each of its three analog research sites performing field studies of the science operations and technology it had developed.  The first field work was conducted at the Craters of the Moon National Monument, Idaho.  In Hawai’i, operations were conducted twice at Hawai`i Volcanoes National Park (Mauna Ulu, Kilauea Iki and Keanakakoi ). The science targeted active and relict magmatic fumaroles to examine the relationship between meteoric (a condition sampled for in 2016) and magmatic influences on basalt alteration and associated microbial diversity.

These were conducted under simulated Mars mission constraints (5/20 minute light-travel time delay and low/high communication bandwidth conditions) to evaluate strategically selected concepts of operations (ConOps) and capabilities with respect to their anticipated value for the joint human and robotic exploration of Mars.
Contrasting Aerosol Optical Characteristics and Source Regions During Summer and Winter Pollution Episodes in Nanjing, China
Authors: Wang Jing , de Leeuw Gerrit
Published: March 2020

Two episodes with heavy air pollution in Nanjing, China, one in the summer and another one in the winter of 2017, were selected to study aerosol properties using sun photometer and ground-based measurements, together with source region analysis. The aerosol properties, the meteorological conditions, and the source regions during these two episodes were very different. The episodes were selected based on the air quality index (AQI), which reached a maximum value of 193 during the summer episode (26 May–3 June) and 304 during the winter episode (21–31 December). The particulate matter (PM) concentrations during the winter episode reached maximum values for PM2.5/10 of 254 μg m−3 and 345 μg m−3, much higher than those during the summer (73 and 185 μg m−3). In contrast, the value of aerosol optical depth (AOD) at 500 nm was higher during the summer episode (2.52 ± 0.19) than during that in the winter (1.38 ± 0.18). A high AOD value does not necessarily correspond to a high PM concentration but is also affected by factors, such as wind, Planetary Boundary Layer Height (PBLH), and relative humidity. The mean value of the Ångström Exponent (AE) varied from 0.91–1.42, suggesting that the aerosol is a mixture of invaded dust and black carbon. The absorption was stronger during the summer than during the winter, with a minimum value of the single scattering albedo (SSA) at 440 nm of 0.86 on 28 May. Low values of asymmetry factor (ASY) (0.65 at 440 nm and 0.58 at 1020 nm) suggest a large number of anthropogenic aerosols, which are absorbing fine-mode particles. The Imaginary part of the Refractive Index (IRI) was higher during the summer than during the winter, indicating there was absorbing aerosol during the summer. These differences in aerosol properties during the summer and winter episodes are discussed in terms of meteorological conditions and transport. The extreme values of PM and AOD were reached during both episodes in conditions with stable atmospheric stratification and low surface wind speed, which are conducive for the accumulation of pollutants. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analysis show that fine mode absorbing aerosols dominate during the summer season, mainly due to emissions of local and near-by sources. In the winter, part of the air masses was arriving from arid/semi-arid regions (Shaanxi, Ningxia, Gansu, and Inner Mongolia provinces) covering long distances and transporting coarse particles to the study area, which increased the scattering characteristics of aerosols.
Earthworms accelerate the biogeochemical cycling of potentially toxic elements: Results of a meta-analysis
Authors: Sizmur Tom , Richardson Justin
Published: March 2020

Earthworms are ecosystem engineers, capable of modifying the soil environment they inhabit. Recent evidence indicates that they increase the mobility and availability of potentially toxic elements in soils, but the systematic synthesis of the evidence required to understand mechanisms and identify soils most susceptible to earthworm-induced potentially toxic element mobilisation is lacking. We undertook a meta-analysis of 43 peer reviewed journal articles, comprising 1185 pairwise comparisons to quantify the impact of earthworms on potentially toxic element mobility in bulk earthworm-inhabited soil and earthworm casts and on plant uptake and concentration. We find that earthworms mobilise potentially toxic elements primarily due to the passage of soil through the earthworm gut and that this results in an increase in the concentration and uptake by plants. Earthworms mobilise potentially toxic elements in uncontaminated soils to a greater extent than contaminated soils. Soils with either very low (<2%) or very high (>10%) soil organic matter content are most susceptible to earthworm-induced potentially toxic element mobilisation. These findings have important implications for exotic earthworms burdening plants with toxic metals, but also offer a promising phenomenon that, if harnessed, may help to alleviate micronutrient deficiencies in degraded soils.
The role of coastal wetlands in reducing back bay flooding: New Jersey Back Bays case study
Authors: Slusarczyk Gregory , Cialone Mary
Published: March 2020

This paper will provide an analysis of the numerical modeled water levels in the vicinity of New Jersey Back Bays (NJBB) coastal wetlands in response to wave and surge forcing. The main focus of the analysis is to evaluate the contribution of the wetlands to reduce storm and flood risk, resist and recover from storms, and mitigate for degradation of the NJBB shorelines.  In order to provide information that addresses these needs, the US Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) evaluated a set of “high” ranked Engineering with Nature (EWN)/ Natural and Nature Based Features (NNBF) measures through an application of the predictive numerical models ADvanced CIRCulation (ADCIRC) and STeady-state spectral WAVE (STWAVE) coupled via the Coastal Storm Modeling System (CSTORM-MS).

The ERDC modeling team developed a priority list of wetland configurations to evaluate, grouped into four categories: 1) Base Option designed to determine the maximum feasible benefits from a subset of NNBF measures, 2) Option 1 designed to determine how the benefits scale with NNBF size, 3) Option 2 designed to determine how the current marsh extent contributes to flood risk, 4) Option 3 designed to determine the interaction of waves with proposed NNBF measures predominantly in the Barnegat Bay area.

The above configurations were subject to wind forcing composed of a statistically-selected subset of synthetic tropical cyclones that were part of North Atlantic Coast Comprehensive Study (NACCS) storm suite. An analysis of the effectiveness of the wetland configurations was performed with respect to the following criteria: maximum surge envelopes, water level time series, and characteristics of tropical storm forcing conditions.
Hidden Magnetizations and Localization Constraints
Authors: Gerhards Christian
Published: March 2020

Recovering the full underlying magnetization from geomagnetic potential field measurements is known to be highly nonunique. Localization constraints on the magnetization can improve this to a certain extent. We present some analytic background as well as some examples on what is meant by 'to a certain extent'. In particular, if no constraints other than spatial localization are imposed, only two out of three components of the vectorial magnetization can be reconstructed uniquely. If it is additionally assumed that the magnetization is induced by an (unknown) ambient dipole field, then the susceptibility and the direction of the ambient dipole can be reconstructed.
Relation of Time-Varying Vp/Vs ratio to Inflation and Deflation Episodes near Hengill Volcano, Iceland
Authors: Tryggvason Ari , Hobé Alex , Gudmundsson Olafur , Geirsson Halldor ,   SIL Seismological Group
Published: March 2020

The Hengill area experienced an intensive and long-lived series of earthquakes in the 1990s. This coincided with a period of inflation near the Hengill volcano, which was interpreted as new influx of magma at ~7 km depth. Feigl et al. (2000) postulated that the observed seismicity was triggered by the strain accumulation associated with the magma-influx. In a similar area ~3 km to the NW, subsidence has been occurring since 2006. The timing of this subsidence coincides with the onset of geothermal production at Hellisheidi in the west and enlargement of the Nesjavellir powerplant in the North. The source of the subsidence near Hengill volcano is however estimated between 5.6 and 7 km depth and at significant lateral distances from these production sites (Juncu et al. 2016). In this study we apply newly developed methods in time-dependent seismic tomography (Hobé et al. 2020) in the Hengill area, to study if significant velocity changes can be attributed to these inflation/deflation episodes. The dataset employed for the tomography covers the inflation period, the subsidence period, and the time in-between, with varying station coverage and geometry. In this study, the artificial velocity variations due to variations in source and receiver geometries are first separated from “true” velocity variations. In the approximate source region of the 2006-onwards deflation the preliminary results show a low Vp/Vs ratio anomaly between ~4-7 km depth, with an EW extent of ~8-10 km and an NS extent of ~4 km. This anomaly coincides with a significant amount of seismicity. This may indicate an increase in the amount of compressible fluids, accompanied with hydro-fracturing. The seismicity terminates below this low Vp/Vs anomaly, underneath which there is an area of increased Vp/Vs ratios (associated with melt) in the approximate center of the inflation episode in the 1990s. Thus, this investigation provides new information about the nature of the deformation sources, and the surrounding hydrothermal system. We will further investigate the apparent connection between the current subsidence and geothermal production.

 

References:

Feigl et al. (2000): Crustal deformation near Hengill volcano, Iceland 1993-1998: Coupling between magmatic activity and faulting inferred from elastic modeling of satellite radar interferograms, J. Geophys. Res.

Hobé et al. (2020): Imaging the 2010-2011 inflationary source at Krysuvik, SW Iceland, using time-dependent Vp/Vs tomography, WGC 2020, forthcoming

Juncu et al. (2016): Anthropogenic and natural ground deformation in the Hengill geothermal area, Iceland, J. Geophys. Res.
The effect of row orientation on below-canopy turbulence characteristics in a wine-vineyard
Authors: Agam Nurit , Levi Yasmin , Alfieri Joe , Prueger John
Published: March 2020

The momentum flux affects the energy exchange processes and thus may indirectly affect the water balance of agricultural fields. In wine vineyards, a high momentum flux between the vine rows may augment the evaporation and transpiration fluxes, and therefore decrease the water use efficiency. On the other hand, at night, high momentum fluxes may reduce (or even prevent) the formation of dew on the vine canopy, thus decrease the potential development of fungi and related diseases. We hypothesized that the wind direction relative to the row orientation in largely-spaced narrow hedge-rows characterizing wine vineyards greatly affects the turbulent structure and the momentum flux. This, in turn affects the vineyard microclimate, and ultimately, the grape quality. The objective of our research was to explore the effect of wine-vineyard row orientation on wind and temperature profiles below (and slightly above) the canopy and on the turbulence characteristics and eddy size.  The research was conducted in two adjacent vineyards in the Judean foothills in Israel (31°48'38.6"N 34°50'43.6"E and 31°48'37.1"N 34°50'24.0"E) having row orientations of NE-SW and SE-NW, respectively. With a NW prevailing wind direction, the wind is typically flowing perpendicularly to the former and in parallel to the latter. In each vineyard, 10 self-made type-T fine-wire thermocouples (0.08 mm diameter) were set on a pole places in the middle of the inter row, at heights above the ground of 5, 10, 20, 40, 80, 140, 220, 250, 300, and 400 cm. In addition, 4 fast-response 2D sonic anemometers were set at 10, 40, 140, and 250 cm above the ground. The measurements were conducted at 20 Hz.  Below canopy wind regime differed with orientation, mostly at heights lower than 2.5m. Higher wind speed below the canopy and smaller wind speed gradients were observed at the vineyard parallel to the prevailing wind direction.  Temperature gradients were mostly larger in the vineyard perpendicular to the prevailing wind direction.  Nevertheless, the power spectra were generally more uniform in height at the perpendicular vineyard.  
Properties of Suprathermal-through-Energetic He Ions Associated with Stream Interaction Regions Observed over Parker Solar Probe’s First Two Orb¬¬its
Authors: Desai Mihir ,   Parker Solar Probe ISOIS, FIELDS & SWEAP Team
Published: March 2020

The Integrated Science Investigation of the Sun (IS☉IS) suite on board NASA’s Parker Solar Probe (PSP) observed six distinct enhancements in the intensities of suprathermal-through-energetic (~0.03-3 MeV nucleon-1) He ions associated with corotating or stream interaction regions during its first two orbits. Our results from a survey of the time-histories of the He intensities, spectral slopes, and anisotropies, and the event-averaged energy spectra during these events show: 1) In the two strongest enhancements, seen at 0.35 au and 0.85 au, the higher energy ions arrive and maximize later than those at lower energies. In the event seen at 0.35 au, the He ions arrive when PSP was away from the SIR trailing edge and entered the rarefaction region in the high-speed stream; 2) The He intensities are either isotropic or show sunward anisotropies in the spacecraft frame; and 3) In all events, the energy spectra between ~0.2–1 MeV nucleon-1are power-laws of the form ∝E-2. In the two strongest events, the energy spectra are well represented by flat power-laws between ~0.03–0.4 MeV nucleon-1modulated by exponential roll-overs between ~0.4–3 MeV nucleon-1. We conclude that the SIR-associated He ions originate from sources or shocks beyond PSP’s location rather than from acceleration processes occurring atnearby portions of local compression regions. Our results also suggest that rarefaction regions that typically follow the SIRs facilitate easier particle transport throughout the inner heliosphere such that low energy ions do not undergo significant energy loss due to adiabatic deceleration, contrary to predictions of existing models.
The BIO-MAÏDO (Bio-physicochemistry of tropical clouds at Maïdo (La Réunion Island): processes and impacts on secondary organic aerosols formation) campaign
Authors: Leriche Maud , Colomb Aurélie ,   BIO-MAÏDO
Published: March 2020

BIO-MAÏDO is a French collaborative program founded by the ANR (Agence Nationale de La Recherche). BIO-MAÏDO aims at better understanding the chemical and biological multiphasic mechanisms that control the Secondary Organic Aerosol (SOA) formation. The tropical environment of the Reunion Island represents an ideal site to study SOA formation: (1) numerous biogenic volatile organic compounds, precursors of SOA are emitted in huge amount and the high solar intensity flux and the temperature favors their chemical transformations; (2) due to the high occurrence of orographic clouds over this region, this site allows evaluating the influence of aqueous processes on SOA formation. The strategy adopted is based on an intensive field campaign over several sites with the objective to characterize sources of gases and aerosols and to evaluate multiphasic pathways controlling the formation and oxidation of SOA. This work is done in synergy with modeling investigations using a lagrangian particle dispersion model (FLEXPART), a 0D process cloud model (CLEPS) together with a 3D chemistry/transport model (Meso-NH).

The campaign took place from 13th of March to 4th of April 2019 at La Réunion Island. The main objectives were to document the cloud cycle on the slope of the Maïdo, the boundary layer development and the chemical evolution of atmospheric composition (primary and secondary aerosols as well as gaseous precursors) along the slope up to the receptor site, the Maïdo observatory. For this reason, the campaign took place on five sites distributed on the slope from the Maïdo to the observatory. A innovative instrumentation was deployed: three PTR-MS, a tethered balloon, an instrumented mast measuring biogenic volatile organic compounds fluxes, a mobile mast with a cloud impactor, etc. Preliminary results from the campaign will be presented.
LICIACube observation capabilities of dust plume evolution after DART impact
Authors: Corte Vincenzo , Mazzotta Epifani Elena , Dotto Elisabetta , Amoroso Marilena , Pirrotta Simone , Cheng Andy ,   LICIAcube TEAM
Published: March 2020

The NASA Double Asteroid Redirection Test (DART) mission will be the first test to check an asteroid deflection by a kinetic impactor. The target of DART mission is the secondary element of the (65803) Didymos binary asteroid system and the impact is expected in late September – early October, 2022. The DART S/C will carry a 6U cubesat called LICIACube (Light Italian Cubesat for Imaging of Asteroid), provided by the Italian Space Agency, with the aim to collect pictures of the impact’s effects. The impact of the 610 kg DART spacecraft at 6.58 km/s on the 163 m Didymos B will result in a change of the binary orbital period of about 10 minutes assuming momentum transfer efficiency β = 1. Values of β > 1 are expected because the produced ejecta carries momentum, primarily in the direction opposite the DART speed direction. The LICIACube mission profile consists in a flyby of Didymos system with closest approach about 3 minutes after the DART impact. LICIACube will be able to acquire the structure and evolution of the DART impact ejecta plume and will obtain high-resolution images and also in 3 colour of the surfaces of both bodies. The nominal mission foresees also imaging of the Dydymos B non-impact hemisphere. The contributions of LICIACube observations to the DART investigations are important for determination of the momentum transfer efficiency β, that is a crucial result of the planetary defence test. Moreover, captured images can enable scientific investigations about the main features of the asteroid system. 

In order to check the imaging capability and to optimize the fast scientific phase of LICIAcube, the LICIA team performed several simulations of pictures’ acquisition. In these simulations, considering the specifications of the 2 optical payloads and the foreseen mission design, we reconstructed synthetic images mainly of the plume. As the plume evolution remains the most important uncertainty, since it depends on a very high number of impacting phase parameters, we simulated imaging of different expected evolution behaviours, to obtain instrument operative parameters and to prepare the data analysis.  
Cu-NPs combating fungicide resistance: effectiveness and synergy against B. cinerea
Authors: Malandrakis Anastasios , Kavroulakis Nektarios , Chrysikopoulos Constantinos
Published: March 2020

The potential of copper nanoparticles (Cu-NPs) alone or in combination with conventional fungicides against sensitive and resistant to fungicides Botrytis cinerea isolates was assessed in vitro and in vivo. DNA sequencing revealed the E198A resistance mutation in the β-tubulin gene in three B. cinerea isolates highly resistant to benzimidazoles (BEN-R), thiophanare methyl (TM), and the G143A mutation in the cytb gene in four isolates highly resistant to the QoI pyraclostrobin (PYR-R). Cu-NPs could effectively control sensitive and resistant isolates. A synergistic effect between Cu-NPs and TM both in vitro and in vivo was observed in the case of benzimidazole sensitive   isolates while an additive effect was observed in BEN-R isolates. The above observed synergistic action could be attributed to increased TM availability in the target site as indicated by the positive correlation observed between TM and TM+Cu-NPs treatments. A positive cross sensitivity and antagonistic action between Cu-NPs and NaCl suggested that copper ions contribute in the fungitoxic action of Cu-NPs, at least partly, since no correlation between Cu(OH)2 and Cu-NPs sensitivity was found. The co-application of Cu-NPs with the oxidative phosphorylation inhibitor fluazinam (FM) resulted in a synergistic action  in all isolates regardless resistance phenotype, indicating a ATP-dependent mechanism of toxic action of Cu-NPs. Cu-NPs combined with conventional fungicides can aid in the design and implementation of eco friendly, sustainable management strategies by reducing fungicide use and combating resistance against B. cinerea.
Investigation of tipping bucket rain gauges using digital photographic technology
Authors: Liao Minhan , Liu Jiufu , Liao Aimin
Published: March 2020

When studying the tipping bucket rain gauge (TBR), it is rather difficult to make an objective and sophisticated measurement of the duration of bucket rotation. From the perspective of digital photographic technology, however, the problem can be easily solved. The primary interest of this research has been to use digital photographic technology to study the TBR under laboratory conditions. In this study, the interframe difference algorithm and a camera recording device were used. Based on three types of JDZ TBRs, the time variation characteristics of bucket rotation were obtained. The time from the beginning of a tip to the time that the bucket is horizontal (T1) and the time for a complete tip (T2) were analyzed in detail. The results showed that T1 and T2 were functions of rainfall intensity, and T1, T2 decrease as the rain intensity increases significantly (P<0.001). Moreover, excellent evidence shows that the averages of T1 and T2 were positively correlated with bucket mass. It took more time for the bucket to tip as the mass of the bucket increased. Furthermore, the error of each TBR was calculated by the new proposed error calculation formula, and the new method was compared with the traditional method. The results from the two methods were very close, which demonstrates the correctness and feasibility of the new formula. However, the traditional calibration cannot acquire the variation characteristics of the tipping time, but the proposed approach can achieve this.
Energetic electron acceleration during magnetic reconnection
Authors: Fu Huishan
Published: March 2020

During magnetic reconnection, magnetic energy is explosively converted to particle energy and consequently electrons are accelerated to hundreds of keV that are dangerous to spacecraft and astronauts. To date, how and where the acceleration happens during reconnection is still unknown. Also, how efficient can the acceleration be remains a puzzle. Using spacecraft measurements (e.g., Cluster and MMS) and numerical simulations, many attempts have been made to answer these questions during the last twenty years. In this talk, I will briefly review these progresses and then show our recent results in understanding these issues. Specifically, I will (1) report a super-efficient electron acceleration by magnetic reconnection in the Earth’s magnetotail, during which electron fluxes are enhanced by 10000 times within 30 seconds; (2) discuss the mechanisms leading to super-efficient electron acceleration; (3) report the first evidence of electron acceleration at a reconnecting magnetopause, during which the acceleration process is nonadiabatic; and (4) report electron acceleration in the
Positioning and integrity monitoring using the new DFMC SBAS service in the road transport
Authors: Wang Kan , El-Mowafy Ahmed
Published: March 2020

Australia and New Zealand has initiated a two-year test-bed in 2017 for the new generation of Satellite-Based Augmentation System (SBAS). In addition to the legacy L1 service, the test-bed broadcasts SBAS messages through L5 to support the dual-frequency multi-constellation (DFMC) service for GPS and Galileo. Furthermore, PPP corrections were also sent via L1 and L5 to support the PPP service for dual-frequency GPS users and GPS/Galileo users, respectively.

The positioning and integrity monitoring process are currently defined for the aeronautical DFMC SBAS service in [1]. For land applications in road transport, users may encounter problems in complicated measurement environments like urban areas, e.g., more complicated multipath effects and frequent filter initializations of the carrier-smoothed code observations. In this study, a new weighting model related to the elevation angles, the signal-to-noise ratios (SNRs) and the filter smoothing time is developed. The weighting coefficients adjusting the impacts of these factors are studied for the open-sky, the suburban and the urban scenarios. Applying the corresponding weighting models, the overbounding cumulative distribution functions (CDFs) of the weighted noise/biases are searched and proposed for these scenarios.

Using real data collected under different measurement scenarios mentioned above, the DFMC SBAS positioning errors and protection levels are computed in the horizontal direction based on the proposed weighting models and the proposed overbounding CDFs. The results are compared with the case applying only the traditional elevation-dependent weighting model. While the positioning accuracy and protection levels did not change much for the open-sky scenario, the RMS of the positioning errors and the average protection levels are found to be reduced in both the suburban and urban scenarios. 

[1] EUROCAE (2019) Minimum operational performance standard for Galileo/global positioning system/satellite-based augmentation system airborne equipment. The European Organisation for civil aviation equipment, ED-259, February 2019
Jets of the Antarctic Circumpolar Current in the Drake Passage Based on Hydrographic Section Data
Authors: Tarakanov Roman , Gritsenko Alexander
Published: March 2020

We have analyzed the fine structure of Antarctic Circumpolar Current jets in the Drake Passage based on CTD and SADCP measurements over two hydrographic sections in January 2010 and October–November 2011. Eleven jets with a local horizontal velocity maximum were revealed in 2010, and nine jets were in 2011. These individual jets were various combinations of 12 jets of the Antarctic Circumpolar Current, which we revealed earlier in the region south of Africa on the basis of the section data in December 2009. Daily satellite altimetry data available at http://www.aviso.altimetry.fr were also used to interpret the synoptic patterns of currents over the sections. These results allow us to suggest that the multi-jet structure with a number of jets exceeding nine reported by Sokolov&Rintoul, 2009 is common for the entire circumpolar circle and even for regions with significant contraction of the ACC, such as the Drake Passage. However, the question about the number of jets and its temporal and spatial permanency remains open. Investigation was supported by Russian Foundation of Basic Research grant No 18-05-00283.
Using GLEAM soil moisture to improve flash flood simulations at small to medium catchments with a two-layer rainfall-runoff model
Authors: Nguyen Ngoc Tu , He Wei , Lü Haishen
Published: March 2020

Rainfall-runoff (RR) models play a critical role in water resource management and flood risk mitigations. Accurate depiction of soil moisture (SM) state in hydrological processes is very crucial for flash flood simulations with RR models. Satellite SM data offers a great opportunity to improve flood simulations by providing more accurate information about the SM state. However, how to make full use of satellite SM data to constrain flood model behavior is an important but tricky research issue, which is not fully solved. Here we propose a method to employ both satellite surface and root-zone soil moisture from the Global Land Evaporation Amsterdam Model (GLEAM) data to determine initial condition, a key parameter, using a two-layer RR model named as “MISDc-2L”. The flood simulations were performed at an hourly time step at small to medium catchments in China over 2010-2015. Results show that the MISDc-2L model satisfactorily simulates flash floods, and its performance varies with flood magnitude. Specifically, the model generally performs better for high-magnitude floods than medium and small ones. The GLEAM soil moisture data was found to be helpful to determine the initial conditions of the MISDc-2L model and thus substantially improved flood simulations. Furthermore, accounting for the different effects of surface SM and root-zone SM on the quantification of initial conditions clearly improves flood simulations. We conclude that satellite SM data is beneficial to flash flood simulations.
Collection/Aggregation in a Lagrangian cloud microphysical model: Insights from column model applications
Authors: Unterstrasser Simon , Hoffmann Fabian , Lerch Marion
Published: March 2020

Lagrangian cloud models (LCMs) are considered the future of cloud microphysical modeling. However, LCMs are computationally expensive due to the typically high number of simulation particles (SIPs) necessary to represent microphysical processes such as collection/aggregation successfully. In this study, the representation of collection/aggregation is explored in one-dimensional column simulations, allowing for the explicit consideration of sedimentation, complementing the authors' previous study on zero-dimensional collection in a single grid box. Two variants of the Lagrangian probabilistic all-or-nothing (AON) collection algorithm are tested that mainly differ in the assumed spatial distribution of the droplet ensemble: The first variant assumes the droplet ensemble to be well-mixed in a predefined three-dimensional grid box (WM3D), while the second variant considers explicitly the vertical coordinate of the SIPs, reducing the well-mixed assumption to a two-dimensional, horizontal plane (WM2D). Both variants are compared to established Eulerian bin model solutions. Generally, all methods approach the same solutions, and agree well if the methods are applied with sufficiently high accuracy (foremost the number of SIPs, timestep, vertical grid spacing). However, it is found that the rate of convergence depends on the applied model variant.  Most importantly, the study highlights that results generally require a smaller number of SIPs per grid box for convergence than previous box simulations indicated. The reason is the ability of sedimenting SIPs to interact with an effectively larger ensemble of particles when they are not restricted to a single grid box. Since sedimentation is considered in most commonly applied three-dimensional models, the results indicate smaller computational requirements for successful simulations than previously assumed, encouraging a wider use of LCMs in the future.
Use of soil organic biomarkers for tracing the origin of eroded sediment: case study in Petzenkirchen (Austria)
Authors: Mabit Lionel , Mbaye Modou , Toloza Arsenio , Gibbs Max , Swales Andrew , Strauss Peter
Published: March 2020

Compound-specific stable isotopes (CSSI) technique based on the measurement of δ13C signatures of organic biomarker compounds such as fatty acids (FAs) has been used since the end of the 2000s to reinforce the knowledge about sediment production and budget in various ecosystems.
The watershed of Petzenkirchen, located 100 km west from Vienna (Austria), was selected to establish the origin of the sediment produced at its outlet using δ13C-FAs analysis. The climatic conditions of the area are temperate with continental influences with a mean temperature of 9.5˚ C and yearly precipitation of 823 mm. The dominant soil types are Cambisols and Planosols. Based on existing land-use records, most of the agricultural fields are dominated by a rotation of winter wheat followed by maize cultivation.
Considering the specific geomorphology, the flow of the runoff, the significant interaction of roads, the distance and connection of the potential sources to the outlet, the contributing area of the site has been set to around 50 ha and 7 sources most likely to contribute to the sediment at the outlet were investigated. Using the mixing polygons approach, the δ13C of saturated long chain FAs (i.e. C24:0 and C26:0) allowed the best discrimination for establishing the contribution of sources to the sediment collected at the exit of the watershed (i.e. the mixture). The relative contribution to the soil mixture of the different source soils identified has been determined using the Stable Isotope Mixing Models in R (SIMMR) and the specific organic carbon content of each source. The simulated results derived with SIMMR highlights that more than half of the sediment reaching the outlet of the watershed originates from stream bank. 
This Austrian study confirms that the information gained with δ13C-FAs analysis could provide unique support for allowing effective agroecosystems management.
A DNS-based Turbulence Parametrization for Global Climate Models: Doubly Diffusive Convection
Authors: Ma Yuchen , Peltier William
Published: March 2020

Global coupled climate modeling requires the representation of multiple widely separated scales in each model component. In the ocean component, the separation of scales is especially dramatic as small scale turbulence exerts significant control on the global scale overturning circulation.  The importance of this control is demonstrated in the context of analyses of the Dansgaard-Oeschger oscillation of Marine Isotope Stage 3 (MIS 3; see Peltier and Vettoretti, 2014)). In the University of Toronto version of CCSM4 water column diapycnal diffusivity is represented using the KPP parameterization of Large et al (1994). This includes explicit contributions due to double diffusion processes which demonstrably play an important role in determining the period of the D-O oscillation itself.

                                             

We have developed a DNS-based methodology to test the accuracy of the doubly diffusive contributions to KPP. High-resolution turbulence data sets have been produced based upon two different models: the “unbounded gradient model” and the “interface model” with depth-dependent temperature and salinity gradients. By fitting the vertical fluxes in the unbounded gradient model (for equilibrium states) as a function of density ratio (the governing non-dimensional parameter) we derive a functional form on the basis of which KPP can be revised.  By applying the revised scheme to the interface model we demonstrate that the local fluxes predicted agree well with those from the numerical simulations. The difference between this new parametrization scheme and KPP demonstrates that KPP may significantly overestimate the diffusivities for both heat and salt at low-density ratio.
Geostatistical analysis for Uncertainty Quantification in the SMART-SED model: a downscaling approach based on Digital Soil Mapping data
Authors: Gatti Federico , Togni Niccolò , Menafoglio Alessandra , Bonaventura Luca , Papini Monica , Longoni Laura
Published: March 2020

SMART-SED is a project aimed at developing an innovative framework for the numerical simulation of sediment motion in river catchments, intended to be used by local territorial management institutions and professionals to design proper strategies for the mitigation of hydrogeological instability. Uncertainty analysis is an intrinsic feature of models simulating natural processes. In order to perform an effective uncertainty quantification, it is necessary to properly identify the variability of the input parameters and to design stochastic simulation methods able to provide realistic realisations, based on the available data. This thesis focuses on the use of digital soil maps for the prediction and stochastic simulation of terrain-related quantities used for the estimation of the input parameters of the SMART-SED model. The digital maps are obtained from SoilGrids, a system for automated soil mapping based on state-of-the-art spatial predictions methods. Innovative approaches are introduced to account for the limitations of SoilGrids data (low resolution, inaccuracy) and for the specificities of the variables in exam. Although the focus is on the SMART- SED project, the methods proposed can be generally used for geostatistical modelling at a local scale using auxiliary coarse information obtained through remote sensing or from previously fitted digital maps.
Chorus acceleration of relativistic electrons in extremely low L-shell during geomagnetic storm
Authors: Zhang Zhenxia , Chen Lunjin , Liu Si , Xiong Ying , Li Xinqiao , Shen Xuhui
Published: March 2020

Based on data from the Van Allen Probes and ZH-1 satellites, relativistic electron enhancements in extremely low L-shell Regions (reaching L~3) were observed during major geomagnetic storm (minimum Dst`-190 nT).  Contrary to what occurs in the outer belt, such an intense and deep electron penetration event is rare and more interesting. Strong whistler-mode (chorus and hiss) waves, with amplitudes 81-126 pT, were also observed in the extremely low L-shell simultaneously (reaching L~2.5) where the plasmapause was suppressed. The bounce-averaged diffusion coefficient calculations support that the chorus waves can play a significantly important role in diffusing and accelerating the 1-3 MeV electrons even in such low L-shells during storms. This is the first time that the electron acceleration induced by chorus waves in the extremely low L-shell region is reported. This new finding will help to deeply understand the electron acceleration process in radiation belt physics.
Unravelling the Remagnetization of the Oman Ophiolite
Authors: Koornneef Louise , Morris Antony , Harris Michelle , MacLeod Christopher
Published: March 2020

The Oman ophiolite is a natural laboratory for the study of processes operating above a nascent subduction zone. It formed in the Late Cretaceous by supra-subduction zone spreading and shortly afterwards was emplaced onto the Arabian continental margin. Twelve massifs in the ophiolite expose complete sections of the Neotethyan oceanic lithosphere, including upper mantle peridotites, lower crustal gabbros, and upper crustal sheeted dykes and lava flows.

 

Previous palaeomagnetic studies have suggested that the southern massifs of the ophiolite were affected by a large-scale remagnetization event during emplacement, that completely replaced original remanences acquired during crustal accretion. In contrast, primary magnetizations are preserved throughout the northern massifs. This study aimed to: (i) apply palaeomagnetic, magnetic fabric and rock magnetic techniques to analyse crustal sections through the southern massifs of the Oman ophiolite to investigate further the extent and nature of this remagnetization event; and (ii) use any primary magnetizations that survived this event to document intraoceanic rotation of the ophiolite prior to emplacement.

 

Our new data confirms that remagnetization appears to have been pervasive throughout the southern massifs, resulting in presence of shallowly-inclined NNW directions of magnetization at all localities. An important exception is the crustal section exposed in Wadi Abyad (Rustaq massif) where directions of magnetization change systematically through the gabbro-sheeted dyke transition. Demagnetization characteristics are shown to be consistent with acquisition of a chemical remanent overprint that decreased in intensity from the base of the ophiolite upwards. The top of the exposed Wadi Abyad section (in the sheeted dyke complex) appears to preserve original SE-directed remanences that are interpreted as primary seafloor magnetizations. Similar SE primary remanences were also isolated at a control locality in the Salahi massif, outside of the region of remagnetization. Net tectonic rotation analysis at these non-remagnetised sites shows an initial NNE-SSW strike for the supra-subduction zone ridge during spreading, comparable with recently published models for the regional evolution of the ophiolite.
ITCZ shift and extratropical teleconnections drive ENSO response to volcanic eruptions
Authors: Pausata Francesco S.R. , Zanchettin Davide , Karamperidou Christina , Caballero Rodrigo , Battisti David S.
Published: March 2020

The mechanisms through which volcanic eruptions impact the El Niño-Southern Oscillation (ENSO) state are still controversial. Previous studies have invoked direct radiative forcing, an ocean dynamical thermostat (ODT) mechanism and shifts of the Intertropical Convergence Zone (ITCZ), among others, to explain the ENSO response to tropical eruptions. Here, these mechanisms are tested using ensemble simulations with an Earth System Model in which volcanic aerosols from a Tambora-like eruption are confined either in the Northern or the Southern Hemisphere. We show that the primary drivers of the ENSO response are the shifts of the ITCZ together with extratropical circulation changes, which affect the tropics; the ODT mechanism does not operate in our simulations. Our study highlights the importance of initial conditions in the ENSO response to tropical volcanic eruptions and provides explanations for the predominance of post-eruption El Niño events and for the occasional post-eruption La Niña in observations and reconstructions.