bluuebunny/crossref_metadata_2025 huggingface dataset:
The importance of modelled processes in the evolution of snow cover versus snow mass
Authors: Mudryk Lawrence , Krinner Gerhard , Derksen Chris , Santolaria-Otin Maria , Menegoz Martin , Brutel-Vuilmet Claire , Vuyovich Carrie , Kumar Sujay , Kim Rhae Sung
Published: March 2020

Conventional wisdom holds that confidence in future projections of snow cover extent and snow mass requires an understanding of the expected changes in future snow characteristics as a function of modelled snow processes. We will highlight contrasting results which suggest differing importance in the role of sub-grid scale processes on simulations of seasonal snow.

The first study is an evaluation of simulated snow cover extent projections from models participating in the 6th phase of the World Climate Research Programme Coupled Model Inter-comparison Project (CMIP-6). We demonstrate a single linear relationship between projected spring snow extent and global surface air temperature (GSAT) changes, which is valid across all future climate scenarios. This finding suggests that Northern Hemisphere spring snow extent will decrease by about 8% relative to the 1995-2014 level per °C of GSAT increase. The sensitivity of snow to temperature forcing largely explains the absence of any climate change pathway dependency, similar to other fast response components of the cryosphere such as sea ice and near surface permafrost.

The second study makes use of an ensemble of land surface models, downscaled to 5 km resolution across North America over the 2009-2017 period. In this case, uncertainty in total North American snow mass is dominated by differences among land surface model configurations. While the largest absolute spread in snow mass is found in mountainous regions, heavily vegetated boreal regions have the largest fractional spread compared to climatological values. In particular, differences in rain-snow partitioning and sublimation rates control the largest portions of the total uncertainty. These results suggest that projections of future snow mass depend specifically on how such processes are modelled and parameterized.
Characteristics and evolution process of strike-slip fault in Halahatang area, North Tarim Basin, NW China
Authors: Ma Debo
Published: March 2020

Characteristics and evolution process of strike-slip fault is a key issue restricting further exploration in Halahatang area, North Tarim Basin, NW China. This paper uses the new-acquired 3D seismic data and applies fault structural analysis method to study the characteristics of Halahatang area, and discusses evolution process of the faults.
The data used in this paper include 1960 km2 3D seismic data in prestack time migration in Halahatang area, and 4 wells logging data used to calibrate seismic horizon. The bin size of 3D seismic is 25 m×25 m with sampling rate of 4ms, and data length of 7000 ms. Firstly, the Eigen-structure coherency and SO semblance are used to identify the distribution of the strike-slip fault. Secondly, the segmentation of Ordovician strike-slip fault in the study area is studied and the control effect of segmentation on reservoir development and oil and gas enrichment is discussed.
The slip distance of strike-slip fault is very small, the maximum is no more than 2 km. They are typical cratonic strike-slip faults which are developed inside the craton. There are four kinds of structural styles on the profile, which are vertical and steep, positive flower structure, negative flower structure and semi-flower structure. Five structural styles of linear extension, X type, braided structure, horsetail structure, and en-echelon structure are developed on the plane. There are obvious segmentation along the fault trend.
According to the strata subjected to strike-slip deformation and the structural styles in different strata, it is determined that the strike-slip faults have three stages of activity in Halahatang area. 
In the Late Ordovician, NNE, NNW, NE, and NEE strike-slip faults are mainly developed in the study area. The faults on the seismic profile are steep and upright, with small displacements. Faults generally only break into the Ordovician, and later activities will cause faults to go up to the Silurian and even the upper Palaeozoic, which have different tectonic styles with that of the Ordovician faults. The NNE and NNW strike-slip faults form an “X”-type conjugate strike-slip fault, reflecting the conjugate strike-slip fault is generated by near north-south compression.
In the Late Permian, 4 NNW transtensional strike-slip faults are generated by the activation of some Ordovician strike-slip faults. In the Late Cretaceous-Palaeocene, the study area mainly develop several groups of NNE, near SN transtensional strike-slip faults. These transtensional strike-slip faults appear as graben and horst or stepped faults on the section. These transtensional strike-slip faults are R-shear faults in the Mesozoic and Cenozoic strata formed by the Ordovician NNE faults slip dextrally under the tectonic stress.
Formation of low molecular weight mono- and di-carboxylic acids and related compounds from photochemical oxidation of stearic and linoleic acids in aqueous-phase
Authors: Pavuluri Chandra Mouli , Devineni Subba Rao , Xu Zhanjie , Kawamura Kimitaka , Fu Pingqing , Zhang Yan-Lin , Liu Cong-Qiang
Published: March 2020

Secondary organic aerosols (SOA) that account for a substantial and often a dominant fraction of total OA mass are formed by photooxidation of various precursors derived from anthropogenic and biogenic sources in the atmosphere. They have serious impacts on the Earth’s climate system directly by scattering and absorbing solar radiation and indirectly by acting as cloud condensation nuclei, and adverse effects on human health. In recent times, considerable attention has been paid on laboratory studies, preferably in gas-phase, in order to understand the chemistry of SOA formation. However, the studies on SOA formation in aqueous phase are limited, which are mainly focused on high abundant volatile organic compounds (e.g., isoprene) and/or their oxidation products, but not on fatty acids (except oleic acid). To better understand the air-water interface photochemistry of fatty acids and their transformations to lower homologous monoacids and more oxygenated species such as diacids and related compounds in atmospheric waters (fog, cloud and aqueous aerosol), we conducted batch UV irradiation experiments on a saturated (stearic acid, C18H36O2) and an unsaturated (linoleic acid, C18H32O2) fatty acids for different time periods (age, 0-120 h) in aqueous-phase. All the irradiated samples were analyzed for measurements of mono- and di-acids, oxoacids and α-dicarbonyls. We found high abundances of monoacids followed by diacids, pyruvic acid and α-dicarbonyls in less aged samples, whereas C3 and C4 diacids were abundant in the more aged samples. Our results imply that the photochemical oxidation of fatty acids and subsequent transformations of the product species in atmospheric waters are significant and their contribution to more oxygenated SOA is increased with aging in the atmosphere.
Seasonal and longitudinal patterns of plastic pollution in a subtropical urban river
Authors: Haberstroh Charlotte , Arias Mauricio
Published: March 2020

Plastic contamination in rivers quickly changes over time and space, driven by factors such as land use, urbanization and population density, climatic conditions and river hydrology. Understanding the patterns and mechanisms behind these fluctuations is of major importance to estimate and evaluate plastic loads and to forward management strategies and policies. During a 18-month sampling campaign (May 2018 to October 2019) in the Hillsborough River Tampa (USA), we studied how seasonality and urban pollution affected plastic loads transported through the river. We sampled monthly at three sampling sites, strategically located to assess the release of plastic through urban runoff from Tampa, covering two wet seasons and one dry season. At each site, we conducted stationary sampling with a 500-µm mesh neuston net at five different positions through the width and depth of the river. Using an Acoustic Doppler Current Profiler, we also collected comprehensive data on flow characteristics and accurately estimated river discharge during sampling events. All samples were processed in the laboratory with state-of-the-art methods to separate plastic particles from water samples. Plastic particles were classified by size categories and a subset was identified using Raman spectroscopy. Results of this study shows a strong correlation between plastic loads and rainfall seasonality. For instance, mean concentrations close to the mouth of the river varied from less than 1 count/m3 during the dry season (March-May) to up to 9 counts/m3 during wet months (September). Furthermore, there was a substantial increase in loads as the river passed through the city, mostly peaking at the farthest downstream site close to the river mouth; while median concentrations at the site upstream from the city were 0.21 counts/m3 (range of 0-1.68), median concentrations at the station close to the river mouth (in Downtown Tampa) were 1.16 counts/m3 (range of 0.14-21.61 counts/m3). During some months, however, loads were higher at the second site, located in the middle of a residential and commercial district. Differences in plastic loads along the river were explained by river flow accumulation and land use/land cover intensity, though small differences in concentrations between the middle site and the furthest downstream can be explained by differences in stormwater management practices between these two contrasting socioeconomic areas. This study generated a unique and comprehensive dataset on plastic loads and river hydrology on a watershed scale to evaluate drivers of plastic pollution and rivers as their pathway, providing a base for the development of management plans in urban rivers and solution strategies for plastic pollution in similar subtropical watersheds.
Detecting Pipeline Leakage in Long-Distance Water Transmission: Case Study in Liaoning Province, China
Authors: Li Fengbin , Fan Jianqiang , Chen Jinn-Chyi
Published: March 2020

Pipeline leakage inevitably occurs in the long-distance water transmission process. If a leak cannot be identified and processed promptly, it can cause severe economic losses or environmental pollution. This paper proposes a method to evaluate pipeline leakages in long-distance water transmission. The pipeline located in Liaoning Province was selected; it is 63.97-km long and runs from west Shenyang to Liaoyang city. Flowrate time-series data were obtained from two flowrate stations; the data were measured using ultrasonic flowmeters. The variance and mean values of flowrate time-series data were determined and used to evaluate whether pipeline leakage occurs. A Chi-Square test was used to test if the variance of a flowrate time-series was equal to a specified value. The results indicate the following: (1) the method of variance test can be used to evaluate whether the pipeline operation is abnormal or not; (2) when the variance test on time series data of flowrate is abnormal for more than two days, the pipeline leakage situation can be evaluated; (3) the combination of the variance test and the mean value analysis can help locate the leak position, which provides a reference for site personnel. The method proposed in this paper can detect pipeline leakage in a timely manner, and further ensure normal water transmission operation in many cities downstream.
The water storage change anomaly and its causes in the middle-lower reaches of Yangtze River basin
Authors: Jin Taoyong , Li Xiaolong , Cai Zuansi
Published: March 2020

The three gorges dam (TGD) is always thought to have a significant impact on hydrological and climatic change in the middle-lower reaches of the Yangtze River basin (MLYRB), which can be regarded as human driven factor. The El Nino/Southern Oscillation (ENSO) events are also considered have large effect in the MLYRB, which can be regarded as climate driven factor. In the study, using terrestrial water storage change anomalies (TWSA) from Gravity Recovery and Climate Experiment (GRACE) mission and hydrological data, we investigate the effect of TGD and ENSO on the TWSA in MLYRB and its sub-basins. From the routinely impoundment of TGD since October 2010, the TWSA and ENSO show high correlation greater than 0.75 with a 5-month time lag, except for the upper Han River basin which is large affected by the Danjiangkou reservoir, and during two extreme flood and drought events, the TWSA and ENSO are almost consistent. It is concluded that the TWSA in the MLYRB is mainly affected by the climate driven factor, but the impoundment of TGD has limited effect. Since the relationship between TWSA and ENSO is stable during the routinely impoundment of TGD, the extreme events occurred in the MLYRB can be early warned by the ENSO index. 
Minor Ion and Electron Characteristics within Magnetosheath Flux Transfer Events Observed by the Magnetospheric Multiscale Mission
Authors: Petrinec Steven , Burch James , Chandler Michael , Farrugia Charlie , Fuselier Stephen , Giles Barbara , Gomez Roman , Mukherjee Joey , Paterson William , Russell Christopher , Sibeck David , Strangeway Robert , Torbert Roy , Trattner Karlheinz , Vines Sarah , Zhao Cong
Published: March 2020

Several dayside magnetosheath flux transfer events (FTEs) have been observed at high temporal resolution by the four-spacecraft MMS mission. In this study, we examine ion energy spectrograms, ion moments, and ion distribution functions for several long duration magnetosheath FTEs observed by MMS. For these cases, the spacecraft were positioned at similar locations (i.e., south of the equatorial plane, post-noon local time sector). The ion observations are placed in context with electron energy spectrograms parallel and anti-parallel to the observed magnetic field and the location of MMS relative to the predicted reconnection line location as determined from convected solar wind conditions. This combined set of observations provide important information on the formation, topologies, and evolution of FTEs.
Geochemical fingerprinting of lemon juices and cultivation soils for authentication and traceability of geographical provenience
Authors: Ruggiero Luigi , Fontanella Maria Chiara , Amalfitano Carmine , Beone Gian Maria , Di Vaio Claudio , Adamo Paola
Published: March 2020

Food habits or more generally food consumption, especially agro-food products, have always been linked to the territory of production. The Sorrento lemon (Citrus limon (L.) Burm. f. cv. Ovale di Sorrento), is known for its characteristic cultivation on terraces in Sorrento peninsula of Campania (south Italy). In this environment, the peculiar soil and climatic features and the traditional cultivation on terraces have contributed not only to high-quality lemon productions but also to protect the landscape. Indeed, in terms of soil and climatic features, the Sorrento peninsula is very heterogeneous. The geographical conformation of the territory, along with the rainfall increase with elevation and in more inland areas, leads to different microclimates and habitats, even at a very small scale.  Main aim of this work was to develop a chemometric discriminant model to authenticate and track Sorrento lemons at a small geographical scale by multi-element fingerprinting and Linear Discriminant Analysis (LDA) in order to protect the PGI lemon from lemons of other geographical origins. The variability of the total and bioavailable mineral contents in soil (top and subsoil) and their relationship with lemon juices were analysed. The multi-element fingerprinting of different areas are different for mineralogical and geochemical composition. The array of inorganic elements of agrofoods is greatly affected by the soil features, such as mineralogy, pH, moisture, and organic constituents. The LDA model was developed and cross-validated with the cultivar “Ovale di Sorrento”. External validation with other cultivars (Femminello Zagara Bianca, Femminello Siracusano 2KR, Femminello Sfusato Amalfitano, Femminello Adamo, and Femminello Cerza), grown in the same areas, was carried out. The LDA model was applied to 102 samples of “Ovale di Sorrento” lemons, cross-validated (96.08% of correct classification) and validated with external validation of 67 lemons juices from other cultivars (94.03% of correct classification) according to geographical origins. Pearson correlation analysis of the total and bioavailable element content of cultivation soils (top and subsoil) and lemons juices was performed.
Searching for the missing plastic: a global surface mass budget for floating ocean plastics.
Authors: Lebreton Laurent , Egger Matthias
Published: March 2020

Predicted global figures for plastic debris accumulation in the ocean surface layer range on the order of hundreds of thousands of metric tons, representing only a few percent of estimated annual emissions into the marine environment. A commonly accepted explanation for this difference is that positively buoyant macroplastic objects do not persist on the ocean surface. Subject to degradation into microplastics, the major part of the mass is predicted to have settled below the surface. However, we argue that such emission-degradation model cannot explain the occurrence of decades-old objects collected by oceanic expeditions. We show that debris circulation dynamics in coastal environments may be a better explanation for this difference. The results presented here suggest that there is a significant time interval, on the order of several years to decades, between terrestrial emissions and representative accumulation in offshore waters. Importantly, our results also indicate that the current generation of secondary microplastics in the global ocean is mostly a result of the degradation of objects produced in the 1990s and earlier. 
NextGEOSS data hub and platform - connecting data providers with geosciences communities
Authors: Bye Bente , Neinavaz Elnaz , Zabala Alaitz , Maso Joan , Voidrot Marie-Francoise , De Lathouwer Barth , Catarino Nuno , Gonzalves Pedro , Cortes Michelle , Panda Koushik , Meyer-Arnek Julian , Janssen Bram
Published: March 2020

The geosciences communities share common challenges related to effective use of the vast and growing amount of data as well as the continueous development of new technology. It is therefore a great potential in learning from the experiences and knowledge aquired across the various fields. The H2020 project NextGEOSS is building a European data hub and platform to support the Earth observation communities with a set of tools and services through the platform. The suite of tools on the platform alllows scalablitly, interoperability and transparency in a flexible way, well suited to serve a multifaceted interdisciplinary community, NextGEOSS is developed with and for multiple communities, the NextGEOSS pilots. This has resulted and continues to provide transfer of experience and knowledge along the whole value chain from data provision to applications and services based on multiple sources of data. We will introduce the NextGEOSS data hub and platform and show some illustrative examples of the exchange of knowledge that facilitates faster uptake of data and advances in use of new technology. An onboarding system is benefitting for existing and new users. A capacity building strategy is an integral part of both the onboarding and the individual services, which will be highligthed in this presentation.
Post-fire changes in streamflow explained by forest self-thinning behavior
Authors: Inbar Assaf , Benyon Richard , Trouvé Raphaël , Lane Patrick , Haydon Shane , Sheridan Gary
Published: March 2020

Most of the drinking water provided to the Melbourne metropolitan area originates from catchments that are covered by tall-wet eucalyptus forests, which have an estimated mean fire return interval of 80-150 yr. When stand-replacing fires occur in these forests, they result in a significant reduction in streamflow for an extended period of time due to the recovery strategy of the dominant tree species (Eucalyptus regnans and Eucalyptus delegatensis) and the water use of the dense regrowth. Current hydrological models that express this phenomenon are based on empirical data and lack the mechanistic explanation that links changes in streamflow with forest stand dynamics after disturbance. Here, for the first time, we present a simple theoretical framework that shows that this post-fire reduction in streamflow could be explained by the self-thinning behaviour of forest regrowth, which is driven by competition for water and light during recovery after a stand-replacing fire. First, we show that the trend in streamflow following a stand-replacing fire can be replicated simply by using the generic self-thinning line (which represents the maximum carrying capacity of a forest stand for a given mean tree diameter) of the dominant tree species. We then go one step further and show that the magnitude of streamflow reduction and the time it takes for streamflow to recover to pre-fire conditions, are sensitive to both the recovery success and the environmental conditions that control the maximum vegetation carrying capacity across the catchments. By using a simple stand growth and mortality model, we link the competition for water and light and the self-thinning behaviour of the forest to evapotranspiration and streamflow trajectories. This theory provides a simple alternative approach that can be used to improve models that predict streamflow from forested catchments after stand-replacing fires.
From Causative Mechanisms of Extreme Events to a Place-based Assessment of Flash Flood Hazard and Vulnerability in the Continental United States
Authors: Moradkhani Hamid , Khajehei Sepideh , Ahmadalipour Ali , Moftakhari Hamed , Shao Wanyun
Published: March 2020

Flash floods impose extensive damage and disruption to societies, and they are among the deadliest natural hazards worldwide. Flooding is an on-going global-scale socio-economic risk that is likely to increase in the future under climate change and human development. This risk has led to a variety of studies on the natural and anthropogenic causes of floods. Also, the massive socioeconomic impacts engendered by extreme floods is clear motivation for improved understanding of flood drivers. This presentation is two-fold: first, I demonstrate a machine learning approach to perform clustering of reanalysis data to identify synoptic-scale atmospheric circulation patterns associated with extreme floods across the Continental United States (CONUS). We subsequently assess the flood characteristics (e.g., frequency, spatial domain, event size, and seasonality) specific to each circulation pattern. Focusing on atmospheric circulation patterns leading to extreme rainfall, which is a major factor in nearly all except snowmelt-driven extreme floods, can be especially used to inform continental-scale modeling and forecasting effort. Considering that flash flood is mainly initiated by intense rainfall, and due to its rapid onset, taking action for effective response is challenging. Therefore, building resilience to flash floods require understanding of the socio-economic characteristics of the societies and their vulnerability to these extreme events. The second part of this presentation provides a comprehensive assessment of socio-economic vulnerability (SEV) to flash floods, investigates the main characteristics of flash flood hazard and accordingly a SEV index is developed at the county level across the CONUS. The coincidence of SEV and flash flood hazard are investigated to identify the critical and non-critical regions. The results indicate the resemblance and heterogeneity of flash flood spatial clustering and vulnerability of the regions over the CONUS. We show how identifying these spatial patterns will assist policy makers reach informed and effective decisions for planning and allocating resources.
Long-term ZTD and ZWD series and climate normals using NCEP1
Authors: C. Santos Marcelo , Moura Marlon , Nikolaidou Thalia , Balidakis Kyriakos
Published: March 2020

The World Meteorological Organization (WMO) recommends the use of climate normals for dealing with the analysis of variations and trends of the meteorological parameters or be used as input to predictive climate models. The suggested period is 30 years, but shorter periods can also be employed. We computed zenith total delay (ZTD) and zenith wet delay (ZWD) series for each node of NCEP1 numerical weather model, starting in 1948. We computed climate normals of those two parameters using periods of 1, 5, 10, 15, 20 and 30 years, with and without the annual signature. To assess window size impact, we looked at variations and correlation of trends derived from the various solutions. Results shows the obvious better smoothing using larger windows and the decrease of the impact of annual signature. Regions with positive trends appear to be concentrated in continental masses and the equator line, and the most significant negative trends are in the oceans. ZTD increase is caused primarily by an increase in ZWD and is an indication of variations in ZWD variables. In the case of water vapor, such an increase in ZWD shows us a probable increase in the amount of water vapor in the atmosphere. Comparisons with trends computed from GNSS-derived ZTD and ZWD series are included with the caveat that time period for such comparisons must be shorter.
Discussion on The Construction Technology of Marine Environment Safety Knowledge Based on Knowledge Graphs
Authors: Sun Lie , Wu Le , Xu Fei , Song ZhanLong
Published: March 2020

The lack of the ability for machines to understand and judge semantic knowledge in the field of emergency response decision-making for marine environment safety is one of the difficulties in intelligent emergency response of marine disaster. Taking advantage of knowledge graphs in semantic search and intelligent recommendation is an important goal for the construction of the marine environment safety knowledge base. We summarizes the knowledge representation method based on knowledge graphs, analyzes the characteristics and difficulties of knowledge representation for emergency decision-making of marine environment safety, constructs the knowledge system of marine environment safety knowledge base, and proposes the construction idea of ​​marine environment safety knowledge base based on knowledge graphs.
Low-oxygen subsurface eddies in the eastern South Pacific
Authors: Pizarro Oscar , Contreras Marcela , Ramírez Nadín , Pizarro-Koch Matías
Published: March 2020

Modeling studies have shown that mesoscale eddies significantly contribute to modulate the variability of the oxygen minimum zone (OMZ) of the eastern South Pacific at seasonal and interannual time scales. Nevertheless, only few observations have shown the properties of these eddies. Particularly subsurface (intrathermocline) eddies may play an important role in the dynamics of the southern tip of this OMZ. In this work we analyze the characteristics of these eddies based on underwater glider observations, along with oceanographic cruises and satellite data. We also combine our observations with results from a high resolution numerical model to analyze the generation mechanism of these subsurface eddies. Observations show that the eddies are characterized by a core with high salinity (SA > 34.6 g kg-1), low oxygen (DO < 0.5 mL L-1)  and relatively low potential vorticity  (f PV < 10-13 s-4, where f is the Coriolis parameter). The eddy core is typically centered around σθ ~ 26.5 kg m3 (150-200 m depth) and their diameters are about 50 km, transporting typically ~0.2 Sv of very low-oxygen (< 0.5 mL L-1) waters offshore. The eddy core properties coincide with the water mass that is transported by the Peru-Chile Undercurrent. Our modeling study shows that the generation of the subsurface eddies is associated with the separation of the Undercurrent from the slope and current reversals (northward subsurface flow) close to the slope.
Characterization and Source Apportionment of Organic Aerosols in Delhi, India
Authors: kumar Varun , Bell David , Haslett Sophie , Bhattu Deepika , Tong Yandong , Giannoukos Stamatios , Mishra Suneeti , Singh Atinderpal , Vats Pawan , Kumar RV Satish , Baltensperger Urs , Ganguly Dilip , Rastogi Neeraj , Mohr Claudia , Tripathi Sachchida N. , Prevot Andre S.H. , Slowik Jay G.
Published: March 2020

Delhi is one of the world’s most polluted city and experiences very high levels of particulate matter throughout the year. It significantly affects radiative forcing, increases mortality, and causes other deleterious effects on human health. Generally, there is a lack of consensus on the dominant sources of organic aerosol driving these high aerosol concentrations. In particular, there is a need to elucidate the relative importance of primary vs. secondary sources and formation mechanisms of secondary aerosols. In order to answer questions pertaining to the sources, formation mechanisms, and atmospheric transformations of organic aerosol, we deployed for the first time in Delhi, the recently developed extractive electrospray ionization long-time-of-flight mass spectrometer (EESI-TOF) in Delhi. This was deployed along with a high-resolution long-time-of-flight aerosol mass spectrometer (AMS), and a Chemical Ionisation Mass Spectrometer fitted with a Filter Inlet for Gases and AEROsols (FIGAERO-CIMS). These measurements were further supported by measurements of black carbon and gaseous species such as CO, NOx etc.

The EESI-TOF provides in real-time information on the chemical composition at the near-molecular level without thermal desorption and fragmentation (Lopez-Hilfiker et al., 2019). It was operated in Delhi from December to February 2019. Measurements by the AMS showed persisting high levels of particulate matter. We attributed the relative contributions of different sources to total non-refractory PM mass by performing source apportionment analysis by means of positive matrix factorization (PMF). A strong day-night variability was clearly seen in all the AMS species. High levels of secondary sources during daytime e.g., low-volatility oxygenated organic aerosol (LVOOA) and an increase of factors associated with primary sources i.e., hydrocarbon-like organic aerosol (HOA) and aerosol from solid fuel combustion (SFC) during morning and evening hours was observed. A similar trend as for the primary aerosol was seen for the semi-volatile oxygenated organic aerosol (SVOOA) mainly due to increased temperature during daytime which may leads to evaporation of semi-volatile species. A unique feature observed was a significant contribution of chloride to the non-refractory (NR) PM2.5 mass. On average, chloride contributed 18-20% to total NR-mass. Similar trends have also been seen in a recent study (Gani et al., 2018). The effect of these high chlorine concentrations during the night and early morning on atmospheric chemistry as well as on secondary organic aerosol formation will be presented.
Mineral transformation and pore structural evolution during the burial process of basalt: a case from Liaohe Depression, Bohai Bay Basin, East China
Authors: Liu Haibo , Huang Yulong , Feng Yuhui , Wang Pujun
Published: March 2020

There are more than one thousand meters thick of Paleogene volcanic stratigraphy in Liaohe Depression, Bohai Bay Basin, East China. We can identify and divide these Paleogene volcanic stratigraphy into 14 stages (Huang et al., 2014; Feng et al., 2015).

We take samples of buried basalts from depth 1418m to 3951m, then use optical microscope, scanning electron microscopy (SEM), electron probe microanalyzer (EPMA) techniques to analyze mineral transformation during the burial process of basalt. Our goal is to establish a mineral transformation model of buried basalts in this area.

We summarized that pyroxene have no alter during burial; feldspar alteration sequence: plagioclase -- phillipsite/chabazite -- analite; olivine alteration sequence: olivine -- smectite -- mixed-layer minerals (chlorite and smectite) -- chlorite; calcium is precipitated while mineral transformation, which can form calcite and fill the pores.

We concluded that (1) from depth 2400m to 3700m (underground temperature 85~130℃), the effective micropores of phenocryst are mainly intra-crystalline pores of phillipsite; (2) below 3700m (underground temperature above 130℃) the effective pores are mainly calcite dissolved pores. This model may be suitable for portraying the mineral transformation and pore structural evolution during the burial process of alkaline series basalts in the alkaline environment (without the influence of organic acids).

References:

HUANG Y.L., SHAN J.F., BIAN W.H., GU G.Z., FENG Y.H., ZHANG B., WANG P.J., 2014, Facies classification and reservoir significance of the Cenozoic intermediate and mafic igneous rocks in Liaohe Depression, East China [J]. Petroleum Exploration and Development, 41(6), 734-744, https://doi.org/10.1016/S1876-3804(14)60087-2.

FENG Y.H., YU X.J., HUANG Y.L., LIU B.H., GU G.Z., LI H.Y., WANG P.J., 2015, Eruption cycles and stages of Cenozoic volcanic rocks and their significance to hydrocarbon accumulations in Liaohe Basin [J]. Journal of China University of Petroleum (Edition of Natural Science), 39(5), 50-57. (in Chinese with English abstract)
Radon and CO2 tracer for radioxenon subsurface sampling in the On Site Inspection
Authors: Telloli Chiara , Ferrucci Barbara , Rizzo Antonietta , Salvi Stefano , Ubaldini Alberto , Vaccaro Carmela
Published: March 2020

The detection of anomalous concentration of Xenon radiosotopes in the subsurface gases during an On Site Inspection (OSI) is a strong indicator of a suspicious underground nuclear explosion. This implies that the sampling methodology ensure the collection of a reliable representative subsurface gaseous sample, avoiding the mixing with atmospheric gases. Radioxenon sampling in shallow layers can provide reliable results for desert areas, but different local geological features could result in more complex migration of subsurface gases to the very near superficial layers affecting the representativeness of the sample.

Radon is currently use as tracer to reveal the effective sampling of gases form the deep surface, so its measurement is coupled with the collection of radioxenon subsurface gases. The detection of radon anomalous concentration in subsurface gases could indicate different causes: high Radon content in subsurface indicate high radon concentration underground caused by the accumulation in an underground and confined cavity; on the other side, low radon detection in subsurface indicate low radon concentration underground that can be indicative of the absence of an underground cavity or the presence of rocks in the cavity absorbing radon. This lead to the consideration that radon is not a univocal tracer for Xe surface sampling in the OSI. A portable isotopic analyzer (that measures d13C and CO2) could be used to localize the faults and fracturing that could lead to a seeping of the subsurface gases. Therefore, this technique could be proposed as an auxiliary equipment for a preliminary activity during an OSI and a monitoring tool during subsurface gas sampling.
PoLIM: an open source 2D higher-order thermomechanically coupled mountain glacier flow model
Authors: Wang Yuzhe , Zhang Tong
Published: March 2020

The worldwide glacier is retreating and is expected to continue shrinking in a warming climate. Understanding the dynamics of glaciers is essential for the knowledge of sea-level rise, water resources in high mountain and arid regions, and the potential glacier hazards. Over the past decades, various 3D higher-order and full-Stokes ice flow models including thermomechanical coupling have been developed, and some have opened their source codes. However, such 3D modeling requires detailed datasets about surface and bedrock topography, variable climatic conditions, and high computational cost. Due to difficulties in measuring glacier thickness, only a small minority of glaciers around the globe have ice thickness observations. It is also a challenge to downscale the climate data (e.g., air temperature, precipitation) to the glacier surface, particularly, in rugged high-mountain terrains. In contrast to 3D models, flowline models only require inputs along the longitudinal profile and are thus computationally efficient. They continue to be useful tools for simulating the evolution of glaciers and studying the particular phenomena related to glacier dynamics. In this study, we present a two-dimensional thermomechanically coupled ice flow model named PoLIM (Polythermal Land Ice Model). The velocity solver of PoLIM is developed based on the higher-order approximation (Blatter-Pattyn type). It includes three critical features for simulating the dynamics of mountain glaciers: 1) an enthalpy-based thermal model to describe the heat transfer, which is particularly convenient to simulate the polythermal structures; 2) a drainage model to simulate the water transport in the temperate ice layer driven by gravity; 3) a subglacial hydrology model to simulate the subglacial water pressure for the coupling with the basal sliding law. We verify PoLIM with several standard benchmark experiments (e.g., ISMIP-HOM, enthalpy, SHMIP) in the glacier modeling community. PoLIM shows a good performance and agrees well with these benchmark results, indicating its reliable and robust capability of simulating the thermomechanical behaviors of glaciers.
Evaluating Light Use Efficiency Models and Parameter-upscaling Methods
Authors: Bao Shanning , Gans Fabian , Besnard Simon , Koirala Sujan , Moreno Alvaro , Walther Sophia , Weber Ulrich , Jung Martin , Mahecha Miguel , Carvalhais Nuno
Published: March 2020

Given its simplicity, the light use efficiency (LUE) concept is widely used for the estimation of gross primary productivity (GPP) at the ecosystem scale. In the last three decades, many types of LUE models have been developed to explain the dependencies of GPP to different environmental and meteorological conditions across spatial and temporal scales. Despite the simplicity, LUE models are robust against observations from daily to seasonal scales, though entailing challenges in parameter upscaling. The main differences across LUEs resides in the presence/absence of certain meteorological drivers and in the particular formulations of different response functions to diagnose instantaneous light use efficiency (ε*). 

Here, we collected different algorithms for describing the meteorological constraints on ε* from literature and performed a factorial experiment by recombining the different response functions between the different models to assess model performance at site and network level. These models were forced and parameterized by remote sensing data, meteorological data and GPP for 177 eddy covariance flux sites from the FLUXNET2015 and LaThuile using a data assimilation approach. The results show that the two selected optimal LUE models had no significant differences in model performances at site-level at daily, weekly, and monthly scales. The Nash-Sutcliffe Model Efficiency Coefficient (NSE) of 50% sites were larger than 0.726 and 0.725 at daily, 0.788 and 0.783 at weekly, 0.836 and 0.834 at monthly and 0.544 and 0.510 at annual scales. 

Based on the selected models, we further explored the different methods to upscale the optimized parameters: a) site means and medians per plant functional type and climate class, b) random forest regression, using bioclimatic variables and corresponding vegetation index, and c) selection according to the similarity between sites, determined via the NSE in mean seasonal cycle temperature, precipitation, radiation, and vegetation indexes within the same plant functional type. The model efficiencies in cross validation for both models show that using the median parameters per plant functional type had the best performance to upscale parameters from site-level to global-level at daily, weekly and monthly scales. Since the meteorological response functions and the corresponding parameters represent the sensitivity of plant photosynthesis to the meteorological conditions we further explore the relationship between the climate sensitivities and other environmental drivers as well as biophysical plant traits using global retrievals of Sun induced fluorescence. Our results emphasize that novel Earth Observations datasets and transfer learning approaches bridge the LUE formulation tradeoffs between complexity and tractability.
Streamflow Changes in the Duero River Basin using an Ensemble of Euro-CORDEX Projections
Authors: Yeste Patricio , Rosa-Cánovas Juan José , Romero-Jiménez Emilio , García-Valdecasas-Ojeda Matilde , Gámiz-Fortis Sonia Raquel , Castro-Díez Yolanda , Esteban-Parra María Jesús
Published: March 2020

Climate change has lead to a generalized decrease of precipitation and an increase of temperature in the Iberian Peninsula during the last decades. These changes will be more intense over the course of the 21th century according to global climate projections. As a consequence, water resources are expected to decrease, particularly in the Duero River Basin.

This study is focused on the hydrological response of the Duero River Basin to the climate change. For this end, firstly, the implementation of the Variable Infiltration Capacity (VIC) model in this Basin has been carried out. The VIC model has been calibrated for the period 2000-2009 with a dataset of daily precipitation, temperature and streamflow. Precipitation and temperature data are extracted from SPREAD/STEAD, a dataset that covers the Peninsular Spain at 0.05º of spatial resolution. Streamflow data are provided by the Spanish Center for Public Work Experimentation and Study (CEDEX, Centro de Estudios y Experimentación de ObrasPúblicas). Subsequently, the VIC model has been validated for the period 2009-2011in order to verify that the model outputs fit well with the observational data.

After the validation of the VIC model for present climate, secondly, the impacts of climate change in the Duero River Basin have been analyzed by developing several future simulations using an ensemble of 18 members from the Euro-CORDEX database and three study periods: 1975-2005 as the historical period; 2020-2050 as the short-term future period, and 2070-2100 as the long-term future period. The Euro-CORDEX simulations for the two future periods are driven under two different Representative Concentration Pathway (RCP) scenarios, RCP 4.5 and RCP 8.5.

The first results of this work show that the VIC model outputs are in good agreement with the observed streamflow, for both the calibration and validation periods. In the context of climate change, a generalized decrease of the streamflow is expected in the Duero River Basin. The results from this study could be of interest for water policy makers and practitioners in the next decades.

Keywords: Duero River Basin, VIC model, climate change, streamflow, projections.

ACKNOWLEDGEMENTS: All the simulations were conducted in the ALHAMBRA cluster (http://alhambra.ugr.es/) of the University of Granada. This work was partially funded by the Spanish Ministry of Economy and Competitiveness projects CGL2013-48539-R and CGL2017-89836-390-R, with additional support from the European Community Funds (FEDER). The first author was supported by the Ministry of Education, Culture and Sport of Spain (FPU grant FPU17/02098).
An approach to detect turbulence coherent structures based on quadrant analysis
Authors: Wang Ye , Wang Baomin , Fang Renzhi
Published: March 2020

Turbulence coherent structures play an important role in the transport of momentum, sensible heat, water vapour and carbon dioxide fluxes over atmospheric surface layer (ASL) . Using eddy covariance system measurements on a 50m tower in Zengcheng, Guangdong province, we develop a novel method based on quadrant analysis to detect turbulent coherent structures. We presume that turbulent flux events’ durations smaller than threshold t are isotropic turbulence. Therefore, the durations of small-time-scale (duration< t) turbulent flux events of each quadrant are expect to be equal, which can be regarded as the criterion of threshold . A deviation of the similarity between four quadrant small-time-scale turbulent flux events’ durations is set to determine the  value. Contour map of momentum flux joint probability density function on quadrant domain proves our hypothesis. Coherent structures can be identified from large-time-scale (duration>t) turbulent flux events.

We apply this method to the momentum, sensible heat, water vapour and carbon dioxide fluxes and obtain individual turbulent coherent structures time-series of different fluxes. It is found that numbers and durations of turbulent coherent structures are similar. Secondly, threshold  is not sensitive to the change of ASL satiability. Compared with k method (NARASIMHA 2007), our  method stands for more physical background as it can be seen as the time-scale of isotropic turbulence, which makes our detecting method more efficient.
Porosity estimates from marine controlled source electromagnetic dipole-dipole data at the Scanner Pockmark in the North Sea
Authors: Gehrmann Romina , Provenzano Giuseppe , Böttner Christoph , Yilo Naima , Bayrakci Gaye , Marin-Moreno Hector , Bull Jonathan , Minshull Tim , Berndt Christian
Published: March 2020

As part of the EU Horizon2020 ‘STEMM-CCS’ project, controlled source electromagnetic (CSEM) and seismic data were acquired in 2017 at the Scanner Pockmark in the UK sector 15/25 of the North Sea, which is actively venting methane gas, to contribute to the evaluation of risk from potential fluid pathways to the sequestration of carbon dioxide in geological formations. We will present some preliminary results and relate electrical resistivities to sediment properties such as porosity and gas saturation.

The CSEM data presented were acquired with a University of Southampton deep-towed electric dipole source and two towed three axis dipole receivers (Vulcan, Scripps) along 12 profiles across an active pockmark. The data were processed in the frequency domain and the electrical resistivity structure was inferred with a 2D regularized inversion algorithm (MARE2DEM, K. Key).

To estimate porosities and their uncertainties to about 200 m below the seafloor, we use the empirical Archie’s law and calibrate Archie’s coefficient using physical properties measured with the multi-sensor core logger on gravity cores and sediment cores from the British Geological Survey Rock Drill 2 rig. Geological horizons identified on reflection seismic data are used as constraints in the resistivity model. The resulting porosity profile decreases with depth due to compaction and can be related to marine and glacial deposition environments.
An internet of things system for urban flood monitoring and short-term flood forecasting in Colima, Mexico
Authors: Khouakhi Abdou , Pattison Ian , López-de la Cruz Jesús , Mendoza-Cano Oliver , Edwards Robert , Aquino Raul , Lepper Paul , Rangel Victor , Ibarreche Jose , Perez Ismael , Davis John , Clark Ben , Martínez Miguel
Published: March 2020

Urban flooding is one of the major issues in many parts of the world and its management often challenging. Here we present Internet of Things (IoT) approach for monitoring urban flooding in the City of Colima, Mexico. A network of water level and weather sensors have been developed along with a web-based data platform integrated with IoT techniques to retrieve data using 3G/4G and Wi-Fi networks. The developed architecture uses the Message Queuing Telemetry Transport protocol to send real-time data packages from fixed nodes to a server that stores retrieved data in a non-relational database. Data can be accessed and displayed through different queries and graphical representations, allowing future use in flood analysis and prediction. Additionally, machine learning algorithms are integrated into the system for short-range water level predictions at different nodes of the network.