bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of aerosol-type characteristics and sources using MAX-DOAS measurement during haze at an urban site in the Fenwei Plain
Authors: Li Xiaomei , Xie Pinhua , Li Ang
Published: March 2020

Atmospheric aerosols range in diameter from a few nanometers to tens of micrometers, and they have direct or indirect effects on atmospheric radiation assessments, global climate change, local air quality and visibility, and human health. In particular, during the high season of haze in autumn and winter, atmospheric aerosols are more conducive to transform and accumulate. In this paper, we used the aerosol optical thickness (AOD) and aerosol profile obtained by MAX-DOAS instrument to study the characteristics of aerosol-type, vertical distribution characteristics of near-surface aerosol, and pollution source analysis. From December 30, 2018, to January 27, 2019, we conducted MAX-DOAS observations on Sanmenxia Environmental Protection Bureau. According to the relative humidity data and ion chromatography data, we analyzed the correlation between AOD and PM2.5, the result show that aerosols are mainly fine particles, and most of them are nitrates. The near-surface aerosol extinction coefficient obtained by MAX-DOAS was compared with the PM2.5 and PM10 concentrations measured by unmanned aerial vehicle (UAV). Aerosol particles showed an increasing trend from the ground to 500 m. Combined with the wind field information and the backward trajectory of the air mass during the haze, we found that the continuous heavy pollution was caused by the transportation of polluted air masses in the northeast, along with local industrial emissions and other sources of emissions, which resulted in a wide range and long-term accumulation of pollutants under continuous and steady conditions.
Magmatic arcs, ophiolite belts and sedimentary basins in Anatolia interpreted from magnetic data
Authors: Teknik Vahid , Thybo Hans , Artemieva Irina
Published: March 2020

Maps of depth to magnetic basement and crustal average susceptibility for the Anatolian plateau and adjacent regions are calculated by applying a spectral method to the magnetic data. The first map provides information on the shape of the sedimentary basins and the latter map is used for tracking magmatic arcs and ophiolite belts, which are covered by sediment and/or overprinted by different phases of magmatism and ophiolite emplacement. This is possible because magmatic and ophiolite rocks generally have the highest magnetic susceptibility values, and the huge contrast to sedimentary rocks makes magnetic data very useful.

The results shows a heterogeneous pattern associated with a mosaic of the many continental blocks, Tethyside sutures, magmatism and former subduction systems in Anatolia. Major basins such as northern part of the Arabian plateau, Black Sea basin, Mediterranean Sea basin and central Anatolian micro-basins are highlighted by very deep magnetic basement. Shallow magnetic basement is generally prominent in eastern Anatolia, and may represent that large amounts of magmatic rocks were emplacement during the convergence and compression of the Arabian plate, whereas a sporadic and asymmetric pattern of sedimentary basins in western Anatolia may have developed in the frame of the extensional regime. The average susceptibility map reveals extension of the Pontide magmatic arc in the north of Anatolia, following the coastline of the Black Sea. The average susceptibility indicates magmatism or ophiolite emplacement around the Kirşehır block. A 400 km long NW–SE elongated average susceptibility anomaly extends from south to NW of the Kirşehır beneath the Quaternary sediments, while the depth to magnetic basement indicate more than 6 km sediments. We speculate that this anomaly indicates a covered magnetic arc or a trapped part of oceanic crust. The westeward extension of the Urima-Dokhtar magmatic arc (UDMA) from the Iranian plateau fades away towards to Central Anatolian plateau. It suggest a geological boundary around the border between Iran and Turkey, which caused different magmatism between the two sides. A near zero magnetic anomaly in the Menderes massif region in the southwest of Turkey indirectly suggests a high geothermal gradient and hydrothermal activity that reduce the susceptibility of the rocks. This observation is in agreement with the crustal thinning and many geothermal fields of the Menderes massif.
Seismic Monitoring for High-Precision Delineation of Fault Geometry and Stress; Case Study for the West Texas Subscription Array
Authors: Karimi Sepideh , Baig Adam , Booterbaugh Aaron , Vaezi Yoones , Stacey Mark , Baturan Dario , Witten Benjamin
Published: March 2020

Seismicity potentially induced through wastewater disposal, hydraulic fracture completion, or other industrial operations, has been a cause for increasing public concern over the last decade. Monitoring for this activity has focussed on the problems of location and characterization, often to a relatively rough degree of precision. Regulations typically spell out responses for operators should an event exceed a magnitude threshold within a specified distance of their facilities. While this type of monitoring is critical for ensuring injections be conducted effectively while minimizing potential damage from shaking and public alarm, it often leaves many unanswered questions in terms of the underlying processes.

Understanding these questions entails that we demand more out of the seismic networks, essentially upgrading the data products to a “next generation” level.  The data from the network needs to be used to provide a detailed understanding of critical geological structures and geomechanics of the study area. This goal is facilitated through both a densification of hardware and a higher order of event processing. High-precision locations delivered through relative relocation methodologies delineate slipping fault structures, often resolving previously unknown features. Moment tensor inversion processing also helps reveal the orientations of faults and provides information on stress in the region. The resolution of these structures provides critical insight into understanding how a field is reacting.

We illustrate the application of this “next-generation” seismicity monitoring system to the Delaware Basin in West Texas, where we have deployed a network of 25 broadband seismometers complementing monitoring from TexNet and other networks. Despite being an exceptionally challenging recording environment, by aggregating all of these data we obtain a high-resolution catalog of earthquake hypocenters delineating a number of fault features. Inverting the stresses from the moment tensors of the highest-quality events shows a dominantly normal stress regime and tangibly resolves a rotation of axes transitioning across the basin. We illustrate both the logistical and processing requirements necessary for timely delivery of results highlighting the dynamics of seismicity in an active study area.
Asymmetry in the climate-carbon cycle response to positive and negative CO2 emissions
Authors: Zickfeld Kirsten , Azevedo Deven , Matthews Damon
Published: March 2020

The majority of emissions scenarios that limit warming to 2°C, and nearly all emission scenarios that do not exceed 1.5°C warming by the year 2100 require negative CO2 emissions. Negative emission technologies (NETs) in these scenarios are required to offset emissions from sectors that are difficult or costly to decarbonize and to generate global ‘net negative’ emissions, allowing to compensate for earlier emissions and to recover a carbon budget after overshoot. It is commonly assumed that the carbon cycle and climate response to a negative CO2emission is equal in magnitude and opposite in sign to the response to an equivalent positive CO2 emission, i.e. that the climate-carbon cycle response is symmetric. This assumption, however, has not been tested for a range of emissions. Here we explore the symmetry in the climate-carbon cycle response by forcing an Earth system model with positive and negative CO2emission pulses of varying magnitude and applied from different climate states. Our results suggest that an emission of CO2into the atmosphere is more effective at raising atmospheric CO2than a CO2removal is at lowering atmospheric CO2, indicating that the carbon cycleresponse is asymmetric, particularly for emissions/removals > 100 GtC. The surface air temperature response, on the other hand, is largely symmetric. Our findings suggest that the emission and subsequent removal of a given amount of CO2 would not result in the same atmospheric CO2concentration as if the emission were avoided. Furthermore, our results imply using simple models used to estimate negative emission requirements may result in underestimating the amount of negative emissions needed to attain a given CO2concentration target.
Targeted urban heat mitigation strategies using urban morphology databases and micro-climate modelling to examine the urban heat profile
Authors: Nice Kerry , Broadbent Ashley
Published: March 2020

Strategies for urban heat mitigation often make broad and non-specific recommendations (i.e. plant more trees) without accounting for local context. As a result, resources might be allocated to areas of lesser need over those where more urgent interventions are needed. Also, these interventions might return less than optimal results if local conditions are not considered. This project aims to assist with these interventions by providing a method to examine the urban heat profile of a city through an automated systematic approach. Using urban morphology information from databases such as WUDAPT, areas of cities are clustered into representative local climate zones (LCZs) and modelled at a micro-scale using localised features and properties. This bottom up modelling approach, using the VTUF-3D, UMEP, and TARGET models, allows these areas to be assessed in detail for their human thermal comfort performance and provide a city-wide heat map of thermal comfort. It also allows mitigation scenarios to be tested and targeted for each cluster type. A case study performed using this method for Melbourne is presented.
Intra-annual stem growth of co-occurring temperate eucalypts in relation to climate variability, competition and fire history
Authors: Hinko-Najera Nina , Najera Umaña Julio C. , Smith Merryn G. , Löw Markus , Griebel Anne , Bennett Lauren T.
Published: March 2020

Forest growth is considered as an important global carbon sink but its responses to environmental changes remain uncertain. Tree stems are a predominant carbon pool in temperate eucalypt forests, representing a susbstantive component of their net productivity and carbon dynamics. Despite their importance, our understanding of factors controlling stem growth in these evergreen forests remains limited partly because the dominant eucalypts lack distinct growth rings. Unravelling eucalypt species' growth responses to climate from other factors, such as competition and disturbances like fire, is challenging due to the lack of long-term growth data. To address this gap, we present six years of monthly measurements of stem-diamter changes (as basal area increment, BAI) of two co-occurring dominant eucalypts from different sub-genera (Eucalyptus obliqua and E. rubida) across seven sites in a natural temperate forest of south-eastern Australia. We used linear mixed-effect models to examine the relative importance to monthly BAI of species, monthly climate indices and their potential lag effects (temperature and rainfall), inter-tree competition, and recent fire history (long-unburnt, prescribed fires, wildfire). Monthly BAI peaked in spring and autumn and was lowest in summer with signficant differences between species during spring and summer. Overall BAI variation was most clearly associated with maximum mean temperature, having a hyperbolic relationship with increases in BAI up to species-specific temperature optima and decreases thereafter. Rainfall, particularly autumn rainfall, influenced seasonal patterns in BAI, while inter-tree competition and recent fire history were of comparatively minor importance. BAI also varied strongly between years reflecting the opportunistic growth behaviour of eucalypts including higher annual growth rates during and after periods of high rainfall and transient decreases in BAI during extended drier periods. Our study provides field-based evidence of different growth niches for co-existing eucalypts in natural temperate mixed forests and highlights the importance of intra-annual climate variation to better understand overall productivity in temperate evergreen forests.
Interception by a temperate coniferous forest and its relationship with wet canopy gas exchange
Authors: Jiao Linjie , Sempuku Yuichi , Chang Ting-wei , Kosugi Yoshiko
Published: March 2020

Interception is an important hydrological process relating to canopy gas exchange and takes a significant part from precipitation. The real interception process by the needle leaves is worth discussing because their shape may allow interception by both surfaces and thus affects photosynthesis by blocking stomata. Therefore, the aim of this study is to figure out the distribution of interception at needle leaf and its relation with the gas exchange of wet canopy.

We measured ecosystem flux and wetness from a Japanese cypress forest by the advanced water-proof enclosed gas analyzer (LI7200, LI-COR, the USA) and handmade wetness sensors. A SVAT (soil-vegetation-atmosphere transfer) multilayer model with two rainfall interception solutions (free gas exchange with interception only by the adaxial surface and no gas exchange with interception by both surfaces) has been used to figure out the distribution of rainfall interception, snow melting water distribution and photosynthesis process of wet canopy.

The results include precipitation events from 4 years, showing that interception can happen not only on the adaxial surface but also on both surfaces. Meanwhile, when the intensity of rainfall events enhanced, the possibility of interception on both surfaces increased. Hence, such kind of needle leaf can process photosynthesis during the rainfall. Future studies should concentrate on improving the model for snow process and soil respiration. More comparison with other types of forests may also provide worthy results for learning how plants adjust photosynthesis to adapt the climate change.
ASIM - Fermi - AGILE simultaneous observation of Terrestrial Gamma-ray Flashes
Authors: Marisaldi Martino , Mezentsev Andrey , Sarria David , Lindanger Anders , Østgaard Nikolai , Neubert Torsten , Reglero Victor , Kochkin Pavlo , Lehtinen Nikolai , Maiorana Carolina , Skeie Chris Alexander , Bjørge-Engeland Ingrid , Ullaland Kjetil , Genov Georgi , Christiansen Freddy , Christian Hugh , Al Nussirat Samer , Briggs Michael , Ursi Alessandro , Tavani Marco
Published: March 2020

The Atmosphere Space Interaction Monitor (ASIM) mission onboard the International Space Station is the first mission specifically dedicated to the observation of Terrestrial Gamma-ray Flashes (TGF) and Transient Luminous Events (TLE). ASIM, together with the Fermi and AGILE satellites, are the only three currently operating missions capable to detect TGFs from space. Depending on orbital parameters, pairs of these missions periodically get closer than few hundreds kilometers, observing the same region on the Earth surface for up to several tens of seconds. This offers the unique chance to observe the same TGF from two different viewing angles. Such observations allow to probe the TGF production geometry and possibly put constraints on production models and electric field geometry at the source.

Here we present four TGFs detected by ASIM and simultaneously detected by Fermi (three events) or AGILE (one event) in the period June 2018 - November 2019. We present location data, light curves, and possible constraints to emission geometry based on coupled observations and Monte Carlo simulations. 
Demonstration of 11-directional muography in Omuro-yama Scoria cone, Izu, Japan
Authors: Nagahara Shogo , Miyamoto Seigo , Morishima Kunihiro , Nakano Toshiyuki , Koyama Masato , Suzuki Yusuke
Published: March 2020

Muography is the method of determining inner bulk density structures of volcano by using cosmic-ray muons. When we get muography image from one direction, there is no spatial resolution along muon path. However, by observing from multiple directions, three-dimensional density structure can be obtained. In recent years, three-dimensional density reconstruction using two or three muographic images has been performed (Tanaka et al., 2010, Rosas-Carbajal et al., 2017), but they obtained three-dimensional density structure with only several hundreds of meters spatial resolution due to lack of information. To improve the spatial resolution, we suggested “omni-directional muography”, putting ten or more observation points to surround the volcano (Nagahara and Miyamoto, 2018), and we estimated its feasibility by simulation. On the other hand, in recent years, detectors for muography have become larger (Morishima et al., 2018, Olah et al., 2019), and a detector necessary for omni-directional muography can be prepared. Therefore, we demonstrated omni-directional muography in Omuro-yama Scoria cone, Izu, Japan.

Omuro-yama is a scoria cone formed by a single eruption. The mountain baseline diameter is about 1 kilometer and the height from base is 300 meters. The eruption has been investigated by sediment surveys (Koyano et al.,1996). This mountain has many advantages that are suitable for omnidirectional muography. 1) no mountains around Omuroyama, so no contamination of muon path except in the Omuroyama body. 2) easy to access the detector sites, 3) enough statistics of penetrating muons because of size. We started observing Omuro-yama in 2018. In 2018, we observed for two months from three directions using a 0.01 square meter emulsion detector. In 2019, we performed a three-month observation from eight directions using a 0.02 square meter emulsion detector. As a result of preliminary three-dimensional density reconstruction using the analysis method of Nishiyama et al. (2014), a region with a low density over 200 m in diameter was found under the crater. Currently, we are considering this result carefully. We plan to observe from 30 directions by 2021, including 11 points.

In this presentation, we report the latest analysis results of observation results from 11 directions and future plan.
The Arctic and Antarctica
Authors: Ilic Olivera
Published: March 2020

It is highly important for teacher of all subjects to develop students' interest and knowledge about our planet, environmental issues and science. During English language lessons, students from Primary School ‘Sveti Sava’ explored the polar regions and their characteristics, differences and similarities between the Arctic zone and the Antarctic by using different ICT. Students also did simple experiments with ice and water in order to understand how melting ice affects sea level. Finally, students discussed the causes and effects of global warming and what could be done to protect the environment. During the lessons, students developed an awareness of global warming, were familiarized with environmental threats and the importance of environmental protection. They discovered the enormous influence and importance of Arctic, Antarctica and the Southern Ocean on global climate and on our planet. The ice melting experiment helped them understand and visualize the effects of global warming on polar regions and their own environment. In the end, students were asked to think about the actions they personally can take in order fight global warming and protect the environment.
Evaluating the fracture morphology of shale specimen by the means of AE power spectrum characteristics
Authors: Xie Qiang , Ban Yuxin , Fu Xiang , He Chunbo
Published: March 2020

Quantitative evaluation of the fracture morphology of shale is an essential prerequisite for assessing the complexity of hydraulic fracturing fracture networks during shale gas exploitation. Brazilian tests coupled with digital image correlation and acoustic emission technique were conducted on black shale in Sichuan Basin in China, the corresponding relationships between the characteristics of the frequency band of acoustic emission power spectra and the micro-damage mechanism of rock specimens were established, and the fracture morphology was quantitatively evaluated. The bedding layer leads to the differences in power spectra characteristics, micro-damage mechanism and fracture morphology of shale. The tension and shear failure of shale matrix induce high-frequency acoustic emission signals, and the tension and shear failure of shale bedding induce low-frequency acoustic emission signals. With the increase of the angle between the bedding layer and loading direction, the dominant frequency and secondary dominant frequency gradually diffuse from low-frequency band to high-frequency band, and the quantitative ratio of high frequency to low frequency  H:L gradually increases. The H:L  of 0° shale specimen is 4.28%: 95.72%, and the fracture is a straight line in shape. The H:L of 30° and 60° shale specimens are 15.89%: 84.11% and 36.93%: 63.07% respectively, and their fractures are arched in shape. The H:L of 90° specimen is 93.85%: 6.15%, and the fracture is composited arc-straight line in shape. The results can provide references for analyzing micro-seismic data in situ, and provide a theoretical basis for controlling fracture trajectory in hydraulic fracturing in shale reservoirs.
Development of an IoT system for sensing monitoring of soil properties
Authors: Lee Byeongchul , Lim Kyoung Jae , Yang Jae E , Yang Dong Seok , Hong Jiyoeng
Published: March 2020

In the age of big data, constructing a database plays a vital role in various fields. Especially, in the agricultural and environmental fields, real-time databases are useful because the fields are easily affected by dynamic nature phenomena. To construct a real-time database in these fields, various sensors and an Internet of Things (IoT) system have been widely used. In this study, an IoT system was developed to construct soil properties database on a real-time basis and aim to a big data system analysis that can assess ecosystem services provided from soil resources. The IoT system consisted of three types of soil sensors, main devices, sensor connectors, and subsidiary devices. The IoT system can measure soil temperature, moisture, and electrical conductivity (EC) data on a five-minute interval. Also, the devices were applied to two test-beds near Chuncheon city in South Korea and have been testing for the stability and availability of the system. In a further study, we will add various soil sensors and functions into the developed IoT system to improve their availability. If the developed IoT system becomes to be stable and functional, it can contribute to constructing soil properties database on a real-time basis and a big data system that assesses soil ecosystem services.
Verification of temperature and humidity conditions of mineral soils in the active layer model
Authors: Bogomolov Vasiliy , Egor Dyukarev , Victor Stepanenko
Published: March 2020

Detailed monitoring of the temperature of the soil layer provides a unique experimental material for studying the complex processes of heat transfer from the surface layer of the atmosphere to soils. According to the data of autonomous devices of air temperature, it was found that within each key area there are no significant differences between the observation sits. According to the annual (2011-2018) observations of the temperature regime of the soil and ground, it has been found that the microclimatic specificity of bog ecosystems is clearly manifested in the characteristics of the daily and annual variations in soil temperature. A regression model describing the change in the maximum freezing depth during the winter has been proposed, using air temperature, snow depth and bog water level as predictors. The effects of BWL and snow cover have similar values, which indicates an approximately equal contribution of BWL variations and snow depth to changes in freezing. The thickness of the seasonally frozen layer at all sites is 20-60 cm and the maximum freezing of the peat layer is reached in February-March. Degradation of the seasonally frozen layer occurs both from above and below.

It was found that similar bog ecosystems in different bog massifs have significantly different temperature regimes. The peat stratum of northern bogs can be both warmer (in winter) and colder (in summer) in comparison with bogs, located 520 km to the south and 860 km to the west.
Signal propagation in sediment routing systems: an application for granulates prediction (location, grain-size)
Authors: Guillocheau Francois , Robin Cécile
Published: March 2020

The consideration of entire “Source to Sink" systems is one of the most recent and challenging advances in earth surface dynamics and sedimentary geology. To understand S2S systems it is necessary to enhance sharing of knowledge and concepts between (1) geomorphology, which focuses on the understanding of erosion processes driving landform evolution and sediment fluxes, (2) stratigraphy/sedimentology, which focuses on the nature of sedimentary deposits and their distribution in time and space, and (3) tectonics and structural geology, which set the dimensions, geometry and dynamics of source/transfer areas and sedimentary basins (the sink). Understanding S2S systems also involves other Geosciences disciplines such as paleoclimatology and geochemistry, because they allow quantifying the factors controlling S2S systems dynamics (climatic controls on erosion, solid vs. solute fluxes, etc.).

The main challenges are (1) to get all the above mentioned disciplines working together on geological or numerical approaches of the whole S2S system, in different tectonic and climatic settings and (2) to convince some industries of the merits of this approach, e.g. industries dealing with geothermy or granulates.

We here present one example of academia – industry transfer of knowledge for granulates: the low accommodation alluvial system of the Armorican Massif of Messinian to Pliocene age, major source of granulates for the development of the Brittany Province (western France). The understanding of the base level fluctuations sensuWheeler (1964), joined to an knowledge of the uplift history, the climate variations, and the source of sediments (Eocene laterite profiles) gave tools for a better prediction on the location and quality of the granulates.
The impact of groundwater depth on the spatial variance of vegetation index in the Erdos Plateau, China
Authors: Zhang Haoyue , Wang Xu-Sheng
Published: March 2020

As important sensitive feedback of ecosystems, spatial distribution and patterns of vegetation can remarkably reflect eco-environmental conditions in arid and semiarid areas, where groundwater plays a significant role. The impact of groundwater depth (GD) on the spatial variance in remote-sensing vegetation index is highlighted in this study over the Erdos Plateau, China. The 250 m resolution mean annual Enhanced Vegetation Index (EVI) data in the period 2000-2010 are analyzed and compared to the same resolution data of GD. It is indicated from the semivariogram that the correlation range of EVI (10-22 km) is close to the correlation range of GD (9-19 km) and both of them show a near to zero nugget. The semivariance of EVI generally decreases with the increasing GD from 0 m to 10 m, but the relationship could be disturbed by other factors. In the semiarid region of the study area where the aridity index falls between 3 and 5, the 98th percentile EVI which represents high density vegetation decreases nonlinearly with the increasing GD from 0 m to 7 m. In the arid region where the aridity index is higher than 5, EVI is relatively low and almost independent on groundwater. The 50th percentile EVI is generally not sensitive to GD, especially in the arid region. Thus, the spatial variance of vegetation is a synthetic result of the climatic and hydrogeological conditions, which should be considered in the regulation of groundwater resources at the regional scale for ecological benefits.
Organic geochemical characteristics of coal deposits in Mae Than coal mine, Lampang Province, Thailand
Authors: Chaiseanwang Patthapong , Chenrai Piyaphong
Published: March 2020

Fifteen samples were collected from coal mines Mae Than basins located in Lampang Province, Northern Thailand to investigate organic geochemical characterization which can provide organic matter input, thermal maturity and depositional environment. The total organic carbon (TOC) content of the coal samples ranges from 30.12 to 73.71 wt. %, while shales and mudstones value between 5.98 – 24.87 wt. %. The extractable organic matter (EOM) content of all samples, which is yielded from bitumen extraction, values in the range of 1,256 and 16,421 ppm indicating good to excellent hydrocarbon generation potential. The organic geochemical data were studied by using Gas-chromatography Mass-spectrometry (GC-MS) providincg biomarker and non-biomarker data. The thermal maturity of studied samples is represented as immature stage due to ratio of Ts/(Ts+Tm) and homohopane isomerization. The distribution of normal alkanes is predominantly long-chain normal alkanes with odd-numbered carbon. The high Carbon Preference Index (CPI) value of samples indicates terrestrial organic matter input. The depositional environment of the study area can be interpreted that the coal formation is occurred within an oxidizing condition with the majority of higher plant input, whereas shale and mudstone is slightly more anoxic-aquatic environment.
High frequency measurements reveal distinct sources of shoot methane emissions.
Authors: Kohl Lukas , Koskinen Markku , Mäkiranta Paivi , Polvinen Tatu , Patama Marjo , Tenhovirta Salla , Pihlatie Mari
Published: March 2020

Plant shoots can emit methane (CH4) from multiple source processes (microbial methanogenesis in soils and core wood, aerobic CH4 production in foliage). We constructed a chamber system to isolate these processes and study how leaf level CH4 emissions respond to environmental factors like dark-light-cycles, temperature, drought, or CO2 concentrations. Tree samplings are located in a FITOCLIMA D 1200 plant growth chamber for PAR, temperature and humidity control and equipped with a measurement chamber to quantify CH4 exchange in a closed loop setup with a Picarro G2301 CH4 analyser. The system was further customized to control temperature, CO2, and humidity in the measurement chamber. The system allows the detection of CH4 flux rates of on the order of 1 nmol CH4 h-1 and can conduct high frequency (< 15 min) measurements of CH4 emissions rates from small shoots (<5g foliage biomass). Initial measurements were conducted with Scots pine and birch saplings. In addition, we measured conducted manual methane flux measurements on shoots of Scots pine saplings in two 24-hour campaigns.

These experiments demonstrated that the shoots of different tree species emit CH4 from distinct sources. Scots pine shoots emitted CH4 produced within the shoot, likely through aerobic CH4 production, which showed a strong diurnal cycles that follows irradiation and photosynthesis rates. Shoot from some birch species, in contrast, showed emissions of soil-borne CH4 that remained constant throughout day and nighttime. We expect that future experiment with this unique setup will allow to further disentangle shoot CH4 emissions and characterize their response to environmental conditions including light, temperature, and relative humidity.
First airborne gravity wave observations at the world’s hotspot in Southern Argentina
Authors: Rapp Markus , Kaifler Bernd , Dörnbrack Andreas , Gisinger Sonja , Mixa Tyler , Reichert Robert , Kaifler Natalie , Giez Andreas , Preusse Peter , Geldenhuis Markus , Krasauskas Lukas , Woiwode Wolfgang , Friedl-Vallon Felix , de la Torre Alejandro , Hormaechea Jose Luis , Riese Martin , Sinnhuber Björn-Martin , Hoor Peter , Engel Andreas
Published: March 2020

The region around Southern Argentina and the Antarctic peninsula is known as the world’s strongest hotspot of stratospheric gravity wave activity. In this region, large tropospheric winds are perturbed by the orography of the Andes and the Antarctic peninsula resulting in the excitation of mountain waves which might propagate all the way up into the upper mesosphere when the polar night jet is intact. In addition, satellite observations also show large stratospheric wave activity in the region of the Drake passage, i.e., in between the Andes and the Antarctic peninsula, and along the corresponding latitudinal circle of 60°S. The origin of these waves is currently not entirely understood. Several hypotheses are currently being investigated, like for example the idea that the mountain waves that were originally excited over the Andes and the Antarctic peninsula propagate horizontally to 60°S and along the latitudinal circle. In order to investigate this and other hypotheses the German research aircraft HALO was deployed to Rio Grande, Tierra del Fuego, at the Southern Tip of Argentina in September and November 2019 in the frame of the SOUTHTRAC (Southern hemisphere Transport, Dynamics, and Chemistry) research mission. A total of 6 dedicated research flights with a typical length of 7000km were conducted to obtain gravity wave observations with the newly developed ALIMA (ALIMA=Airborne LIdar for Middle Atmosphere research)-instrument and the GLORIA (GLORIA=Gimballed Limb Observer for Radiance Imaging of the Atmosphere) limb sounder. While ALIMA measures temperatures and temperature perturbations in the altitude range from 20-90 km, GLORIA observations allow to characterize wave perturbations in temperatures and trace gas concentrations below flight level (<~14 km). This paper gives an overview of the mission objectives, the prevailing atmospheric conditions during the HALO deployment, and highlights some outstanding initial results of the gravity wave observations.
Magnetic properties of sedimentary smythite (Fe9S11)
Authors: Roberts Andrew , Horng Chorng-Shern
Published: March 2020

Smythite (Fe9S11) is an occasionally reported magnetic iron sulphide mineral that occurs in varied geological settings and co-occurs commonly with other magnetic iron sulphide minerals. Determining the magnetic properties of smythite is important to understand its geological distribution and paleomagnetic and environmental magnetic significance. We have identified sedimentary smythite from three locations in Taiwan (one terrestrial and two marine), which suggest that smythite forms in methanic diagenetic environments into which sulfide has been reintroduced. We report the magnetic properties of our purest smythite sample and compare them with those of other magnetic iron sulfide minerals. The magnetization of smythite is controlled by multi-axial anisotropy, with magnetic easy axes that lie within the crystallographic basal plane. Smythite has stable magnetic properties with no low-temperature magnetic transition. The magnetic properties of smythite at elevated temperatures are dominated by thermal alteration, which precludes Curie temperature determination. Hysteresis and coercivity properties of stable single domain smythite are similar to those of greigite at, and below, room temperature. In contrast to greigite, and similar to pyrrhotite polytypes, smythite crystals occur as hexagonal plates. This morphological contrast facilitates discrimination of smythite from greigite in electron microscope observations, but it does not assist discrimination from pyrrhotite. Similar magnetic and morphological properties between smythite and other magnetic iron sulfides means that diagnostic mineralogical analyses (e.g., X-ray diffraction) are needed to identify these minerals. Further work is needed to obtain pure samples to develop a comprehensive domain state dependent magnetic property framework for smythite.
Investigating basal thaw as a potential driver of ice flow acceleration in Antarctica
Authors: Dawson Eliza , Schroeder Dustin , Chu Winnie , Mantelli Elisa , Seroussi Helene
Published: March 2020

Glacial thermal processes exert a fundamental control on ice flow, governing viscosity and frozen-to-thawed transitions at the ice-bed interface. Across Antarctica, frozen bed regions characterized by numerical models and geophysical observations, can also reduce ice flow by increasing basal traction. Some frozen bed regions can separate or confine fast-flowing glaciers and ice streams. Others separate inland catchments with thawed beds from the grounding zone of marine ice-sheet sectors. If regions with frozen bed experienced thawing, such a transition may lead to ice-sheet acceleration, reconfiguration, or retreat. To investigate the potential impact of such a thermal transition, we use the JPL/UCI Ice Sheet System Model (ISSM) to identify vulnerable regions across Antarctica that are close to the basal melting point. We assess the impact of thawing these regions by quantifying resulting volume changes and surface expressions. This allows us to identify the areas of the ice sheet where the thermal regime at the ice-bed interface has the largest potential impact on ice-sheet stability and sea-level contribution. We also examine the potential basal temperature and thaw-propagation thresholds governing this process. We then compare the ISSM results to a selection of ice-penetrating radar sounding observations to refine our constraints of the configuration, distribution, and extent of these thermally critical areas.
Hydro-isotopic (234U/238U) zoning of groundwaters in the seismically active southern margin of the Siberian craton, Russia
Authors: Rasskazov Sergei , Chebykin Eugene , Ilyasova Aigul , Chuvashova Irina
Published: March 2020

The southern margin of the Siberian craton, which experienced severe tectonic deformations in the Neoproterozoic-Cambrian and Jurassic, is currently a part of the Baikal seismic belt. In groundwater budget of the area, the main contribution is provided by the homogeneous South Baikal reservoir (SBR) with 234U/238U activity ratio (AR) 1.95–1.99 and U concentration 0.44–0.46 µg/L. Lateral penetration of the SBR water from the hydrostatically loaded deeper part of the lake (1000 m and more) to the adjacent Siberian craton area is promoted by gentle ruptures of the Angara thrust fault and sub-vertical shear fissures of the Main Sayan suture zone. In order to predict the time and place of a strong earthquake, AR are determined in groundwater from craton basement and sedimentary cover in an area from Lake Baikal to Irkutsk. AR values associated with deformational (Cherdyntsev–Chalov) effect vary from 1.0 to 3.5. Chemical impacts in evaporates result in AR values as high as 16. Data of a 7-year monitoring show key points in AR variations that might be used for prediction of a future strong earthquake.

This work is supported by the RSF grant 18-77-10027.
Measurement of tropospheric HO2 radical using fluorescence assay by gas expansion with low interferences
Authors: Wang Yihui , Hu Renzhi , Xie Pinhua , Wang Fengyang , Liu Jianguo , Liu Wenqing
Published: March 2020

    An instrument to detect atmospheric HO2 radicals using fluorescence assay by gas expansion (FAGE) technique has been developed. HO2 is measured by reaction with NO to form OH and subsequent detection of OH by laser-induced fluorescence at low pressure. The system performance has been improved by optimizing the expansion distance and pressure, and the influence factors of HO2 conversion efficiency are also studied. The interferences of RO2 radicals produced from OH plus some typical organic compounds were investigated by determining the conversion efficiency of RO2 to OH during the measurement of HO2. The dependence of the conversion of HO2 on NO concentration was investigated, and low HO2 conversion efficiency was selected to realize the ambient HO2 measurement, where the conversion efficiency of RO2 derived by propane, ethene, isoprene and methanol to OH has been reduced to no more than 6%. Furthermore, no significant interferences from PM2.5 and NO were found in the ambient HO2 measurement. The detection limits for HO2 (S/N=2) are estimated to 4.8×105 cm-3 and 1.1×106 cm-3 (the conversion efficiency of HO2 to OH, =20%) under night and noon conditions, with 60s signal integration time. The instrument was successfully deployed during STORM-2018 field campaign at Shenzhen graduate school of Peking University. The diurnal variation of HOx concentration shows that the OH maximum concentration of those days is about 5.5×106 cm-3 appearing around 12:00, while the HO2 maximum concentration is about 5.0×108 cm-3 appearing around 13:30.
Depth and properties of freshwater export from the Greenland Ice Sheet modulated by ice-ocean processes
Authors: Slater Donald , Straneo Fiamma
Published: March 2020

Freshwater export from the Greenland Ice Sheet to the surrounding ocean has increased by 50% since the early 1990s, and may triple over the coming century under high greenhouse gas emissions. This increasing freshwater has the potential to influence both the regional and large-scale ocean, including marine ecosystems. Yet quantification of these impacts remains uncertain in part due to poor characterization of freshwater export, and in particular the transformation of freshwater around the ice sheet margin by ice-ocean processes, such as submarine melting, plumes and fjord circulation. Here, we combine in-situ observations, ocean reanalyses and simple models for ice-ocean processes to estimate the depth and properties of freshwater export around the full Greenland ice sheet from 1991 to present. The results show significant regional variability driven primarily by the depth at which freshwater runoff leaves the ice sheet. Areas with deeply-grounded marine-terminating glaciers are likely to export freshwater to the ocean as a dilute mixture of freshwater and externally-sourced deep water masses, while freshwater from areas with many land-terminating glaciers is exported as a more concentrated mixture of freshwater and near-surface waters. A handful of large glacier-fjord systems dominate ice sheet freshwater export, and the vast majority of freshwater export occurs subsurface. Our results provide an ice sheet-wide first-order characterization of how ice-ocean processes modulate Greenland freshwater export, and are an important step towards accurate representation of Greenland freshwater in large-scale ocean models.
Jupiter As Seen By The Juno Microwave Radiometer: A Progress Report
Authors: Levin Steven ,   Juno Microwave Radiometer Team
Published: March 2020

Juno is a spin-stabilized, solar-powered spacecraft in a highly eccentric 53.5-day polar orbit about Jupiter, with perijoves at about 5000 km above the cloud tops. From this unique vantage point, the Juno Microwave Radiometer (MWR) measures the radio emission in 6 channels, at wavelengths ranging from 1.4 to 50 cm, with 100 mS sampling throughout each spin of the spacecraft.  This data set covers the Jovian atmosphere over a wide range of latitudes, longitudes and emission angles, resulting in discoveries, puzzles, and fresh insights related to the distribution and concentration of ammonia and water, atmospheric dynamics, lightning, and other aspects of the atmosphere at depths as deep as 100 bars or more. We will present an overview of MWR results to date, incorporating data from 22 perijove passes.
Sub-annual moraine formation at an active temperate Icelandic glacier
Authors: Chandler Benjamin M. P. , Chandler Samuel J. P. , Evans David J. A. , Ewertowski Marek W. , Lovell Harold , Roberts David H. , Schaefer Martin , Tomczyk Aleksandra M.
Published: March 2020

We present findings from detailed geomorphological and sedimentological investigations of small recessional moraines at Fjallsjökull, an active temperate outlet of Öræfajökull, southeast Iceland. The moraines are characterised by striking sawtooth or hairpin planforms that are locally superimposed, giving rise to a complex spatial pattern. We recognise two distinct populations of moraines, namely a group of relatively prominent moraine ridges (mean height ~1.2 m) and a group of comparatively low-relief moraines (mean height ~0.4 m). These two groups often occur in sets/systems, comprising one pronounced outer ridge and several inset smaller moraines. Using a representative subsample of the moraines, we establish that they form by either (a) submarginal deformation and squeezing of subglacial till or (b) pushing of extruded tills. Locally, proglacial (glaciofluvial) sediments are also incorporated within the moraines during pushing. For the first time, to our knowledge, we demonstrate categorically that these moraines formed sub-annually using repeat uncrewed aerial vehicle (UAV) imagery. We present a conceptual model for sub-annual moraine formation at Fjallsjökull that proposes the sawtooth moraine sequence comprises (a) sets of small squeeze moraines formed during melt-driven squeeze events and (b) push moraines formed during winter re-advances. We suggest the development of this process-form regime is linked to a combination of elevated temperatures, high surface meltwater fluxes to the bed, and emerging basal topography (a depositional overdeepening). These factors result in highly saturated subglacial sediments and high porewater pressures, which induces submarginal deformation and ice-marginal squeezing during the melt season. Strong glacier recession during the summer, driven by elevated temperatures, allows several squeeze moraines to be emplaced. This process-form regime may be characteristic of active temperate glaciers receding into overdeepenings during phases of elevated temperatures, especially where their englacial drainage systems allow efficient transfer of surface meltwater to the glacier bed near the snout margin.
On the application of confidence limits to biostratigraphy: an example from diatoms
Authors: Lopes Cristina , Velez João
Published: March 2020

For years, diatom-based biostratigraphy has been settings bio-events based on a qualitatively approach. This means that the biostratigraphy would set an age based on the findings or not of a certain species. However, how many species are needed to consider a certain datum as certain? One, ten, 100? Moreover, each biostratigrapher sets its on limits. One might consider one as enough and another 10. Therefore, the scale more often used is the absent, rare, frequent, common, dominant or abundant with an explanation of what of these definitions mean. This is very common in, for example, IODP expeditions.

However, what would happen to these biostratigraphy levels if one would apply, for example, a concept of 95% confidence level? Moreover, what would happen to an age model if this concept would be applied to all the biostratigraphy microfossil?

Here we will show Expedition 346 age model differences with and without confidence levels applied to diatoms. The differences can be significant and even considering the existence of a hiatus can be reconsider if confidence limits are applied, turning a possible hiatus into a very slow sedimentation rate having serious implications to the initial paleoceanographic interpretations.