bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of human intervention and climate change on the land cover change in the glacial affected area of the Tianshan Mountains
Authors: Wei Hong , Xiong Liyang , Tang Guoan , Strobl Josef , Xue Kaikai
Published: March 2020

Abstract: Land use/land cover change (LULC) in glacial affected areas are driven by climate change and human activities. Monitoring and simulation of the spatial and temporal land cover changes in this special region provide scientific basis in understanding the natural environment, helping to reveal the impact of climate change and human activities on LULC. In this study, the Tianshan Mountains (TSM), located in the hinterland of Eurasia, were selected as the study area to investigate the LULC of the glacial affected areas. The relationship between LULC, human intervention and climate change on a large spatial scale were also analyzed. The LULC of the TSM in China for the past 35 years were analyzed using a dynamical change model, a landscape pattern index, a centroid transfer model, and geoinformation TUPU based on the land use data of 1980, 1990, 2000, and 2015. Results show that the areas of cultivated and built-up lands immensely increased by 45.87% and 187%, respectively. Correspondingly, the areas of bare land and ice and snow cover decreased by 27% and 38%, respectively. The land use change in the TSM was characterized by different stages, and high conversion rate and intensity were obtained from 2000 to 2015. The landscape change was mainly reflected in terms of the significant increase in the number of patches and the simplification and regularization of patch shapes. The spatial connectivity of different land use types increased. The temperature and precipitation in the region show an increasing trend, and the melting rate of ice and snow cover significantly accelerated. This study can help to achieve a dynamic LULC model to investigate the interacting influences of climate change and human activities in glacial affected areas.
Rapid changes in distribution and fate of Polycyclic aromatic hydrocarbons (PAHs) in sediments from the East China Sea and their response to human-induced catchment changes
Authors: Wang Chenglong , Hao Zhe , Feng Ziyue , Zhang Chuchu , Zou Xinqing
Published: March 2020

Human-induced catchment changes have affected the sedimentary processes in marginal seas, which will impact the transport and burial processes of materials and inevitably impact marine biogeochemical cycles. Polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the East China Sea (ECS) at two time nodes (2006 and 2018) were compared to understand the response of PAHs to human-induced catchment changes. PAH concentrations in the ECS ranged from 8–414 ng g-1 (dry weight), with a mean value of 112±77 ng g-1, relatively lower than that in 2006 (38–308 ng g-1, with a mean of 122±60 ng g-1). Sharp decreases in sediment loads have triggered erosion in subaqueous delta and changed the distribution of sediment components, which may eventually influence the distribution pattern of PAHs. The obvious spatial differentiation of PAHs between 2006 and 2018 suggested that the depositional center of PAHs shifted from the estuary to the inner shelf area. PAH deposition patterns in the ECS were primarily influenced by riverine input before 2006, but are now dominated by winnowing processes related to long-distance transport due to sharply decreased sediment loads. Dam construction in the river catchment intercepted large amounts of sediments and PAHs, shifting the Changjiang-derived PAH depositional center from the ocean to reservoirs. Overall, depositional patterns of PAHs in the ECS were largely altered by human-induced catchment changes, which may cause significant impacts on the region’s biogeochemical cycles and ecosystem health.
Modelling the transfer of pesticide transformation products from agricultural fields to the aquatic environment – state of knowledge and future challenges
Authors: Gassmann Matthias
Published: March 2020

Transformation products (TP) of pesticides are found everywhere in the aquatic environment. Their dynamic formation and subsequent transport from agricultural fields to adjacent water bodies can be estimated by using environmental fate models, which is done e.g. in the registration process for plant protection products in the European Union. In this study, an overview of models, transformation simulation concepts and model applications for TP estimation including leaching and catchment scale models is given. The review is restricted to models which were tested against field data in peer-reviewed publications. The models included in this review are GLEAMS, MACRO, RZWQM(2), PEARL, PRZM, Pelmo, LEACHM, HYDRUS 1-D, ZIN-AgriTra and the Field Release Model (FRM).

Investigating model structures revealed, that six transformation schemes, i.e. possible transformation pathways, are implemented in the models. Only one of the reviewed models, PELMO, uses a completely flexible scheme. In all other models, pathways are restricted. An assessment of model complexity, including hydrological processes and transformation-affecting processes, resulted in PELMO having the highest transformation but the least hydrological complexity among leaching models. RZWQM is the leaching model with the highest hydrological complexity and ranks second in transformation processes. Among the three catchment scale models, ZIN-AgriTra ranks highest in both, hydrological and transformation complexity.

Even though the number of publications of TP model applications is rather low, the number of leaching models is adequate (eight models). At the catchment scale, however, only two models with proven applications exist in the literature. A spatio-temporal analysis of all models revealed a gap in catchment and regional-scale models with a daily or lower temporal resolution. Thus, well-developed and applied catchment-scale models should be extended by a TP module. This would enable scientists and authorities to estimate TP concentrations or to analyse the environmental fate of TPs at the larger catchment scale. At the same time, the fate processes in models should be updated to reflect the current state of knowledge, especially more flexible transformation schemes and the formation of TPs in different compartments (i.e. plant, soil, water). The integration of pathway prediction models such as the University of Minnesota Pathway Prediction System could enhance the assessment of the large number of pesticide TPs in the aquatic environment.
The Tibet lithosphere is not all hot
Authors: Xia Bing , Artemieva Irina , Thybo Hans
Published: March 2020

We calculated the thermal lithosphere structure of Tibet and adjacent regions based on the new thermal isostasy method. Moho depth is constrained by the published receiver function results. The calculated surface heat flow in the surrounded Tarim, North China, and Yangtze cratons have a good match with the real measurements of surface heat flow. We recognize the northern Tibet anomaly where has a relatively thin lithosphere with a thermal thickness of <80 km and surface heat flow of >80 - 100 mW/m 2 may cause by the removal of lithospheric mantle and upwelling of asthenosphere. In Lhasa Block, the cold and thick lithosphere (>200 km) with a surface heat flow of 40 - 50 mW/m 2. In the east Tibet, the heterogeneous thermal lithosphere does not follow the widely spread large scale strike-slip faults and suggested that the faults do not cut down to the lithosphere. The surrounding cratons have different thermal lithosphere features. The Tarim and Yangtze cratons show typical cold and thick lithosphere with a lithosphere of >200km and surface heat flow of <50 mW/m2. The western North China Craton has an intermated lithosphere with a thickness of 120-200km and surface heat flow of 45-60 mW/m2. Our result suggested that high and flat Tibet has different isostatic compensation in different blocks. The heterogeneous lithosphere thermal structure of the Tibet suggested that the uplife force drive are difference in Tibet.

 
Implicitly localized MCMC sampler to cope with nonlocal/nonlinear data constraints in large-size inverse problems
Authors: Brankart Jean-Michel
Published: March 2020

Many practical applications involve the resolution of large-size inverse problems, without providing more than a moderate-size sample to describe the prior probability distribution. In this situation, additional information must be supplied to augment the effective dimension of the available sample, for instance using a covariance localization approach. In this study, it is suggested that covariance localization can be efficiently applied to an approximate variant of the Metropolis/Hastings algorithm, by modulating the ensemble members by the large-scale patterns of other members. Modulation is used to design a (global) proposal probability distribution (i) that can be sampled at a very low cost, (ii) that automatically accounts for a localized prior covariance, and (iii) that leads to an efficient sampler for the augmented prior probability distribution or for the posterior probability distribution. The resulting algorithm is applied to an academic example, illustrating (i) the effectiveness of covariance localization, (ii) the ability of the method to deal with nonlocal/nonlinear observation operators and non-Gaussian observation errors, (iii) the reliability, resolution and optimality of the updated ensemble, using probabilistic scores appropriate to a non-Gaussian posterior distribution, and (iv) the scalability of the algorithm as a function of the size of the problem. The codes are openly available from github.com/brankart/ensdam.
Pliocene ocean and climate dynamics in the eastern Indian Ocean and their implications for the global climate state.
Authors: De Vleeschouwer David , Füllberg Angelina , Smith Rebecca , Auer Gerald , Petrick Benjamin , Castañeda Isla , Christensen Beth
Published: March 2020

The Indonesian Throughflow (ITF) operates as an important link in global thermohaline circulation and is often considered a modulator of global past climate changes, with effects as far as Africa or the Atlantic Ocean. Yet, to what extent ITF variability accounted for oceanographic change along the west Australian coast remains controversial. A tectonically reduced ITF has been invoked to explain the short, but intense Pliocene glaciation Marine Isotope Stage (MIS) M2 (3.3 Ma). The hypothesis hinges on a reduced equator-to-pole heat transfer in the Indian Ocean, in response to low connectivity with the Indo-Pacific warm pool. To clarify links between regional oceanographic change and global climate, we present a two-site multiproxy reconstruction from the Perth (U1459) and the Carnarvon (U1463) Basin. These sites provide the opportunity to unravel the Pliocene history of the Leeuwin Current (LC). We use the LC as a proxy for ITF connectivity, as the ITF is the source for the warm, low-salinity, nutrient-deficient LC. A U1459-U1463 comparison thus allows for investigating the possible relationship between mid-Pliocene glaciations and ITF heat flux. We show that the LC was active throughout the Pliocene, albeit with fluctuations in intensity and scope. We identify three main factors that controlled LC strength. First, a tectonic ITF reorganization caused an abrupt and permanent LC reduction at 3.7 Ma, coeval with the remarkably intense Pliocene glacial MIS Gi4. On shorter timescales, eustatic sea level and direct orbital forcing of wind patterns hampered or promoted the LC. At 3.3 Ma, LC intensity plunged in response to a eustatic ITF restriction. MIS M2 caused the latitudinal U1463–U1459 planktonic oxygen isotope gradient to steepen from 1.2 to 2.0‰ and the TEX86 sea surface temperatures gradient to increase from 3 to 6°C. Yet, comparison with Exmouth Plateau Site 763 shows that the LC did not shut down completely during MIS M2: The ITF heat flux dwindled but did not cease. Weakened ITF connectivity led to a significant drop in Indian Ocean poleward heat transport and thus constitutes a positive feedback mechanism that contributed to the relative intensity of MIS M2 and the thermal isolation of Antarctica. This positive feedback mechanism is ultimately driven by orbital-scale changes in relative sea level in the ITF region.
The utilisation of Amino methyl phosphonic acid by soil micro-organisms as a phosphorus nutrient source
Authors: Kehler Anchen , Blackwell Martin , Haygarth Phil , Tamburini Federica
Published: March 2020

Our global climate continues to change, and with that comes the change of our soil climate. Reports by the IPCC indicate annual increases in prolonged rainfall events within temperate climates; thus exacerbating widespread autumn/winter waterlogged conditions within in the years to come. For our soils, this means the development of anaerobic systems as wetland areas and frequent flooding become more common. Reducing systems like these are capable of facilitating conditions in which alternative oxidation states of the vital elements needed for soil health present themselves. The change of our soil climate is rarely considered when attempting to understand how phosphorus is cycled and how it might be affected in an alternative environment. Existing knowledge from the marine sector demonstrates that a low oxidation state group of compounds known as phosphonates (+3) are successfully utilised by micro-organisms instead of phosphate (+5) as their phosphorus source; thus demonstrating that the phosphorus biogeochemical cycle is much more complex than previously regarded. In the case of the soil environment, there is a large quantity of inaccessible phosphorus present that might be utilised through similar microbial mechanisms when considering a reducing system. The aim of this research is to alter the understanding of global phosphorus cycling and additionally of ecosystem phosphorus limitation. This is done by assessing the capabilities of certain biological species to process phosphorus in alternative oxidation states, highlighting the importance of reduced phosphorus compounds on the global redox cycle.
Schumann Resonance on Titan : Huygens Observations Critically Re-Assessed and prospects for the Dragonfly Mission
Authors: Lorenz Ralph , Le Gall Alice
Published: March 2020

The Huygens probe to Titan in 2005 was the first planetary probe or lander to feature ELF electric field sensing and atmospheric conductivity measurements. The atmospheric electricity community showed great interest in the claimed detection of a Schumann resonance signal on another world (despite its unexpected dominant frequency of 36 Hz), and the planetary science community embraced an interpretation of the altitude dependence of the signal as evidence of a theoretically-anticipated internal water ocean beneath an ice crust many tens of km thick.

Quantitative scrutiny suggests that prospects of detecting a Schumann signal at Titan with the Huygens experiment were in fact very poor, due to short measurement time, a horizontal antenna orientation, a lack of lightning, and the likely presence of severe dynamical effects on the probe. Although the latter objections were considered, and arguments developed against them (notably the novel postulated Saturn-magnetospheric excitation of the resonance), we have re-examined the data in the light of a better understanding of the probe dynamics. The evolution of the 36Hz power shows a very strong correlation with accelerometer records of short-period motions of the probe under its small stabilizer parachute, suggesting that mechanical oscillations of the probe and/or the antenna booms were actually the cause. The ‘signal’ ramped up just as the probe accelerated from the much more quiescent main parachute, and ceased abruptly a couple of seconds after impact.

While the Huygens signal may therefore have been an artifact, this does not mean that a Schumann resonance does not occur on Titan. Most likely if it occurs, it may be very sporadic, responding to the infrequent rainstorms on Titan. A search for such signals should therefore be a long-duration monitoring exercise (not unlike listening for seismic events that could also probe Titan’s interior). The Dragonfly mission to Titan, recently selected for launch in 2026 with arrival planned in 2034 and over two years of surface operation, provides an opportunity to perform such monitoring.
Modelling the basal hydrology under the Greenland Ice Sheet
Authors: Vanhulle Alexander , Le Clec’h Sébastien , Huybrechts Philippe
Published: March 2020

Subglacial hydrology plays an important role in the evolution of ice dynamics. Primarily, it affects basal processes such as basal sliding. Further, subglacial water exiting a calving front incites submarine melt, increasing calving, resulting in a thinning of the interior ice sheet. Knowledge of it is therefore crucial towards the development and improvement of ice sheet models. We implement a model representing the routing of subglacial water below the Greenland ice sheet in either a one, four or eight directional manner. Due to its computational efficiency, the model is suited for coupling with continental scale ice sheet models on very high resolutions (e.g. 150 m).

Routing depends on the hydraulic potential of individual grid cells which is therefore heavily dependent on accurate estimates of the ice thickness as well as the grid utilized. Sensitivity analyses brought to life that the routing exhibits artefacts resulting in significant flow diversions on high resolutions if the gradients are only considered over the distance of a single grid cell, this is overcome by incorporating a smoothing procedure.

With the basal water model in place and input of the basal melt rate from the VUB Greenland Ice Sheet Model (GISM) as well as runoff input from the Modèle Athmospherique Régional (MAR), we calculate the inflow of freshwater to several reference fjords for the last thirty years and investigate its temporal and spatial patterns. Jakobshavn Isbrae experiences by far the most freshwater inflow compared to the other reference fjords. Despite limited runoff in the northeast of Greenland, high basal melt rates and a significant catchment area provide the outlets of the Northeast Greenland Ice Stream (NEGIS) with substantial inflow too.
Serious Games to improve decision-making on the water-land-energy-food-climate nexus
Authors: Brouwer Floor , Laspidou Chrysi , Vamvakeridou-Lyroudia Lydia
Published: March 2020

Water, energy, food, land and climate are tightly connected, and actions on one sector impact other sectors, creating feedbacks and unanticipated consequences. SIM4NEXUS (Sustainable Integrated Management for the nexus of water-land-food-energy-climate for a resource-efficient Europe) does address all these resources and their interlinkages, and also account for the possible impact on these elements in response to climate and relevant policy changes. Twelve case studies are implemented to test them at different scales (i.e. regional, national, transboundary, European and global). Barriers to a resource efficient and low-carbon Europe are addressed, including policy inconsistencies and incoherence and knowledge gaps related to the complex interactions.

Gaming has been established as means for understanding policies, leading to acceptance, mitigating conflicts and seeking for compromise. However, to our best knowledge, never has a Serious Game been developed for the nexus, and based on such extensive list of scientifically sound models, data and methodologies. Serious Games are developed in SIM4NEXUS as an enhanced visualisation tool, assisting users in better understanding and visualising policies at different scales, towards a better scientific understanding of the Nexus of water-land-food-energy-climate.
Prediction of landslide susceptibility using Hybrid Support Vector Regression (SVR) with metaheuristic algorithms
Authors: Saro Lee , Panahi Mahdi
Published: March 2020

Spatial landslide susceptibility prediction is essential for adopting landslide mitigation strategies and reducing landslide damages. This study proposes novel hybrid models based on support vector regression (SVR) and meta-heuristic algorithms: Gray Wolf Optimization Algorithm (GWO) and Artificial Bee Colony Algorithm (Bee). Geospatial data including 15 environmental landslide conditioning factors (slope, aspect, plan curvature, air flow, convergence index, terrain surface texture, wind exposition index, vector ruggedness measure, TWI, valley depth, forest type, forest density, forest age, geology and land use) were derived for a landslide-prone region of Icheon, Korea from available data. A landslide inventory map with 457 landslide points was created from existing aerial photos and field surveys. The geospatial data and landslide points were divided to training (50%) and validation (50%) dataset and used to construct the landslide susceptibility models using the SVR model. The parameters of the SVR models were optimized using the GWO and Bee algorithms. The resultant hybrid models (SVR-GWO and SVR-Bee) leveraged the advantages of the GWO and Bee meta-heuristic algorithms for parameter estimation. The predictive accuracy of the models was quantified using the statistical measures of RMSE, MAE, AUC, and ROC curve. Both GWO and Bee algorithms improved the SVR performance with SVR-GWO model performing the best (AUC = 0.82) followed by SVR-Bee model (AUC = 0.82) and standalone SVR model (AUC = 0.79). The results demonstrated the efficiency and improved performance of the proposed hybrid models compared to standalone models for spatial landslide susceptibility prediction with limited environmental data.
Temporal changes in the distinct scattered wave packets and their origin associated with triggered earthquake swarm beneath the Moriyoshi-zan volcano, northeastern Japan
Authors: Amezawa Yuta , Kosuga Masahiro , Maeda Takuto
Published: March 2020

We investigated temporal changes in the waveform of wave packets in S-coda associated with a swarm-like earthquake sequence, and estimated the original location of the wave packets via an array analysis. The earthquakes are located around the Moriyoshi-zan volcano in northeastern Japan, and were triggered by the 2011 off the Pacific coast of Tohoku earthquake, forming the largest cluster to the north of the volcano. A notable feature of seismograms from the triggered earthquakes is the appearance of the distinct scattered wave-packets (DSW) that are S-to-S scattered waves from the localized strong heterogeneity in the mid-crust. The DSW appear about 2–3 s after the onset of S-wave with a dominant frequency of 8–24 Hz and with a duration of around 1 s. Furthermore, the DSW show the variation in their shapes even in the roughly near events. 
To investigated the variation of DSW in detail, we first grouped events in the largest cluster with short inter-event distances and high cross-correlation coefficients (CC) in the time window of direct waves. Then we focused on the DSW part. Even in the same group, DSW showed temporal changes in their amplitudes and shapes. The change occurred gradually in some cases, but temporal variation were much more complicated in many cases. For example, the shapes of DSW changed from unclear peak to clear double peaks and suddenly back to the unclear. We also found that the shape of DSW changed in a very short time interval, for example, within ~ 12 h. 
Next, we estimated the location of DSW origin by applying the semblance analysis to the data of the temporary small-aperture array deployed to the north of the largest cluster. The DSW origin is located between the largest cluster within which hypocentral migration had occurred and the low-velocity zone depicted by a previous tomographic study. These observations imply the existence of crustal fluid and the DSW origin was composed of crustal fluid accumulated midway in the upward fluid pathway from the low-velocity zone to the earthquake cluster. 
Though we could not entirely exclude the possibility of the effect of the event location and focal mechanisms, the remarkable temporal changes in DSW waveforms possibly reflect the temporal changes in and/or near the origin. The short term change in DSW implies that fast movement of crustal fluid can occur at the depth of the mid-crust. 

 
Trade-offs and Synergies of Ecosystem Services in Karst Area of China Driven by Grain-for-Green Program
Authors: Wang Xiaofeng
Published: March 2020

As an important means regulating the relationship between human and natural ecosystem, ecological restoration program plays a key role in restoring ecosystem functions. The Grain-for-Green Program (GFGP, One of the world’s most ambitious ecosystem conservation set-aside programs aims to transfer farmland on steep slopes to forestland or grassland to increase vegetation coverage) has been widely implemented from 1999 to 2015 and exerted significant influence on land use and ecosystem services (ESs). In this study, three ecological models (InVEST, RUSLE, and CASA) were used to accurately calculate the three key types of ESs, water yield (WY), soil conservation (SC), and net primary production (NPP) in Karst area of southwestern China from 1982 to 2015. The impact of GFGP on ESs and trade-offs was analyzed. It provides practical guidance in carrying out ecological regulation in Karst area of China under global climate change. Results showed that ESs and trade-offs had changed dramatically driven by GFGP . In detail, temporally, SC and NPP exhibited an increasing trend, while WY exhibited a decreasing trend. Spatially, SC basically decreased from west to east; NPP basically increased from north to south; WY basically increased from west to east; NPP and SC, SC and WY developed in the direction of trade-offs driven by the GFGP, while NPP and WY developed in the direction of synergy. Therefore, future ecosystem management and restoration policy-making should consider trade-offs of ESs so as to achieve sustainable provision of ESs.
Transient Pleistocene simulations with a new coupled climate-ice-sheet model
Authors: Choudhury Dipayan , Timmermann Axel , Schloesser Fabian , Pollard David
Published: March 2020

Orbital and CO2 variations over glacial timescales are widely held responsible as drivers of the ice-age cycles of the Pleistocene. Alongside these glacial cycles, our paleoclimate history is marked with abrupt changes and millennium scale variabilities. However, the relative contributions of these forcings over glacial transitions and mechanisms of abrupt changes are not very well understood. Here, using the recently developed three-dimensional coupled climate – ice-sheet model (LOVECLIM – Penn State University ice-sheet model), we simulate the glacial inception over the period of MIS7 to MIS6 (240-170ka). This period is the coldest interglacial post the Mid-Brunhes Event and includes one of the fastest glaciation/deglaciation events of the Late Pleistocene, over MIS7e-7d-7c (236-218ka); which we use here to benchmark our transient coupled model runs. Our results suggest that glacial inceptions are more sensitive to orbital variations, whereas terminations need both forcings to work in tandem over a tiny ablation zone at the southern margins of ice sheets. And abrupt changes may result from a critical interplay between the climate and the cryosphere systems. Using multiple ensembles in combination with conceptual dynamical systems’ models, we test the sensitivity of ice-sheets to various physical factors and discuss the presence of multiple equilibrium states and runaway effects. Additionally, our simulations show that regional scale variations at the southern end of Laurentide can lead to a bifurcation of the system and play a role even in orbital-scale ice-sheet growth/decay.
Dust lidar ratios retrieved from the space-borne CALIOP measurements using the MODIS AOD as a constraint
Authors: Kim Sang-Woo , Kim Man-Hae , Omar Ali
Published: March 2020

Dust lidar ratios are retrieved by a synergetic use of CALIOP and MODIS products for 5 years from 2007 to 2011. The CALIOP level 1 total attenuated backscatter data is used for the retrieval and the CALIOP level 2 aerosol profile product is used to determine dust layers. Quality assured (QA > 1 for dark target ocean, QA = 3 for deep blue land) aerosol optical depth (AOD) data from the MODIS level 2 aerosol product is used as constraint. MODIS AOD retrievals and CALIOP attenuated backscatter profiles closer than 10 km from the center of MODIS pixel are defined as collocated measurements. Clouds are screened out for both CALIOP and MODIS. The retrieval is performed for the whole column of the atmosphere from 30 km to the surface adopting a constant lidar ratio of 30 sr for aerosols of clear air above the detected layers. The retrieved dust lidar ratios show a log-normal distribution with mean (median) values of 39.5 ± 16.8 (38.1) sr and 46.6 ± 36.3 (39.2) sr for ocean and land, respectively. The mean values are comparable to the value of 44 sr currently used in the CALIOP level 2 aerosol algorithm but the median values are relatively lower. There is a distinct regional variation in the retrieved dust lidar ratios. Dust lidar ratio is larger for the Saharan Desert (49.5 ± 36.8 sr) than the Arabian Desert (42.5 ± 26.2 sr), which is consistent with many previous studies. Dust aerosols transported to the Mediterranean Sea (44.4 ± 15.9 sr), Mid Atlantic (40.3 ± 12.4 sr) and Arabian Sea (37.5 ± 12.1 sr) show lower values compared with their source regions. An aging process of the long-range transported dust to remote ocean may be responsible for low lidar ratios. Dust lidar ratio over ocean in East Asia is 41.8 ± 27.6 sr is comparable with previous studies. Over Taklamakan and Gobi Deserts region the retrieved dust lidar ratios (35.5 ± 31.1 sr) show low values but still comparable with previous studies. Dust lidar ratios for Australia (35.4 ± 34.4 sr) are also relatively low compared with other regions. Although the mean AOD difference between CALIOP and MODIS is small (close to zero), the distribution of the AOD difference shows that the CALIOP AOD is biased low. However, when including clear air AOD for CALIOP, AODs from the two sensors become more comparable. A conclusion that can be drawn from this is that retrieving only for the detected layers in the CALIOP algorithm is one of the major reasons for lower AODs for CALIOP than MODIS. Lidar ratios retrieved in this study are strongly affected by MODIS AOD, because it is used as a constraint for the retrieval.
Mixed-Mode Seismic Slip and Aseismic Creep on a Highly Active Low-Angle Normal Fault System in Papua New Guinea
Authors: Biemiller James , Wallace Laura , Lavier Luc
Published: March 2020

Whether low-angle normal faults (LANFs; dip < 30°) slip in large earthquakes or creep aseismically is a longstanding problem in fault mechanics. Although abundant in the geologic record, active examples of these enigmatic ‘misoriented’ structures are rare and extension rates across them are typically less than a few mm/yr. As such, geodetic and seismological observations of LANFs are sparse and can be difficult to interpret in terms of earthquake cycles. With a long-term slip rate of ~1 cm/yr, the Mai’iu fault in Papua New Guinea may be the world’s most active LANF and thus offers an outstanding natural laboratory to evaluate seismic vs. aseismic behavior of LANFs. Here, we use new results from a campaign GPS network to determine the degree of locking vs. aseismic creep on the Mai’iu fault and evaluate these results in the context of geological evidence for mixed seismic and aseismic slip in exhumed Mai’iu fault rocks.

We derive velocities from GPS measurements with 3-4 km station spacing above the shallowest portions of the fault, which dips 21-25° at the surface. Dislocation modeling of these velocities is consistent with 6-8 mm/yr of horizontal extension, corresponding to ~1 cm/yr dip-slip rates on a 27-35°-dipping fault. Strain rates and vertical derivatives of horizontal stress rates derived from these velocities confirm localized extension across the fault. We compare and evaluate two interseismic locking models that fit the data best: one in which the fault deforms by shallow near-surface creep updip of a deeper zone of increased interseismic coupling which soles into a steadily creeping shear zone at depth, and one in which the fault creeps steadily downdip of a shallowly locked patch. These results combined with field and microstructural evidence from the exhumed fault rocks suggest that the fault slips by a mixture of brittle frictional (seismic slip, fracturing, and cataclastic creep) and viscous (stress-driven dissolution-precipitation creep, or pressure solution) processes. Using depth-constrained mechanical properties and stress conditions inferred from exhumed fault rocks, we model the time-dependent competition between frictional slip and viscous creep to assess where and how elastic strain accumulates along the Mai’iu fault, and whether the fault is capable of hosting or nucleating earthquakes.
A study on the determination method of Global Warming Potential (GWP) by measuring the experiment-based infrared absorption spectra and the reactivity of the hydroxyl radical
Authors: Lee Bong Jae , Lee Jung Il
Published: March 2020

As the use of chlorofluorocarbons (CFC) gas was completely banned in 2010, hydrofluorocarbon (HFC) and perfluorocarbon (PFC) gases are replacing its place. HFC and PFC demands are consistently increasing due to their use in extinguishing agent, refrigerant for cooling and also in semiconductor and display manufacturing process for etching, deposition, cleaning and more. However, most HFCs and PFCs currently in use have a very high GWP, which adversely affect the greenhouse gas reduction policies that each country is working on.

To this aspect, countries and relating companies are conducting research to replace from high GWP rated HFCs and PFCs to low GWP rated HFCs and PFCs or to new gases. However, the proper study has not yet been made because of unknown information about GWP, in the case of using or developing a gas which has not been clarified its GWP in IPCC, WMO, and related papers.

Therefore, here, we propose a determination method of global warming potential based on various literature studies as following.

Calculating absorbed cross-sectional area by measuring infrared adsorption spectra using Fourier-transform infrared spectroscopy (FT-IR) and applying to Lambert-Beers’ law using measured infrared absorption spectra.

Applying original Pinnock curve (Pinnock et al., 1995) and final Pinnock curve using the Oslo LBL model (Myhre et al., 2006), to calculate the radiative forcing by integrating the calculated absorbed cross-sectional area from Step 1.

Measuring the reactivity of the hydroxyl radical using PTR-Mass (V.Sinha et al., 2008) and based on measured OH radical, calculate the atmospheric life expectancy using the rate coefficient (Burkholder et al., 2014) and tropospheric lifetime (WMO, 2014) of CH3CCl3 (MCF), reference material proposed by WMO, 2014 .

Following the IPCC AR5(2013), calculate GWP from the radiative forcing and the atmospheric life expectancy, determined by Step 2 and 3.

This work was supported by Korea Institute of Energy Technology Evaluation and Planing (No. 20172010106080)
Long-Term Monitoring with Fiber Optics Distributed Temperature Sensing at Campi Flegrei: The Campi Flegrei Deep Drilling Project
Authors: Somma Renato , Troise Claudia , Zeni Luigi , Minardo Alessandro , Fedele Alessandro , Mirabile Maurizio , De Natale Giuseppe
Published: March 2020

Monitoring volcanic phenomena is a key question, for both volcanological research and for civil protection purposes. This is particularly true in densely populated volcanic areas, like the Campi Flegrei caldera, including part of the large city of Naples (Italy). Borehole monitoring of volcanoes is the most promising way to improve classical methods of surface monitoring, although not commonly applied yet. Fiber Optics technology is the most practical and suitable way to operate in such high temperature and aggressive environmental conditions. In this paper, we describe a fiber optics DTS (Distributed Temperature Sensing) sensor, which has been designed to continuously measure temperature all along a 500 m. deep well drilled in the West side of Naples (Bagnoli area), lying in the Campi Flegrei volcanic area. It has been then installed as part of the international ‘Campi Flegrei Deep Drilling Project’, and is continuously operating, giving insight on the time variation of temperature along the whole borehole depth. Such continuous monitoring of temperature can in turn indicate volcanic processes linked to magma dynamics and/or to changes in the hydrothermal system. The developed monitoring system, working at bottom temperatures higher than 100 °C, demonstrates the feasibility and effectiveness of using DTS for borehole volcanic monitoring.
Identification of Soil Erosion in Alpine Grasslands on High-Resolution Aerial Images: Switching from Object-based Image Analysis to Deep Learning?
Authors: Zweifel Lauren , Samarin Maxim , Meusburger Katrin , Roth Volker , Alewell Christine
Published: March 2020

Soil erosion in Alpine grassland areas is an ecological threat caused by the extreme topography, prevailing climate conditions and land-use practices but enhanced by climate change (e.g., heavy precipitation events, changing snow dynamics) in combination with changing land-use practices (e.g, more intensely used pastures). To increase our understanding of ongoing soil erosion processes in Alpine grasslands, there is a need to acquire detailed information on spatial extension and temporal trends.

In the past, we have successfully applied a semi-automatic method using an object-based image analysis (OBIA) framework with high-resolution aerial images (0.25-0.5m) and a digital terrain model (2m) to map erosion features in the Central Swiss Alps (Urseren Valley, Canton Uri, Switzerland). Degraded sites are classified according to the major erosion process (shallow landslides; sites with reduced vegetation cover affected by sheet erosion) or triggering factors (trampling by livestock; management effects) (Zweifel et al. 2019). We now aim to apply a deep learning (DL) model with the purpose of fast and efficient spatial upscaling(e.g., alpine-wide analysis). While OBIA yields high quality results, there are multiple constraints, such as labor-intensive steps and the requirement of expert knowledge, which make the method unsuitable for larger scale applications. The results of OBIA are used as a training dataset for our DL model. The DL approach uses fully-convolutional networks with the U-Net architecture and is capable of rapid segmentation and classification to identify areas with reduced vegetation cover and bare soil sites.

Results for the Urseren Valley (Canton Uri, Switzerland) show an increase in total area affected by soil degradation of 156 ±18% during a 16-year observation period (2000-2016). A comparison of the two methods (OBIA and DL) shows that DL results for the Urseren Valley follow similar trends for the 16-year period and that the segmentations of eroded sites are in good agreement (IoU = 0.83). First transferability tests to other valleys not considered during training of the DL model are very promising, confirming that DL is a well-suited and efficient method for future projects to map and assess soil erosion processes in grassland areas at regional scales.

 

References

L. Zweifel, K. Meusburger, and C. Alewell. Spatio-temporal pattern of soil degradation in a Swiss Alpine grassland catchment. Remote Sensing of Environment, 235, 2019.
Creating quality in PhD education through a national research school network
Authors: Birkelund Anniken R. , Werner Stephanie C.
Published: March 2020

Norwegian geosciences institutes has as separate and spread entities had limited resources for teaching global, large-scale processes and changes related to the evolution of planetary interior and its interaction with the crust, atmosphere and hydrosphere. The institutes experienced that the courses offered locally were insufficient to educate young academics in fundamental and curiosity-driven Earth sciences. The PhD students also experienced to be alone within their field and without a network around them.

The quality of PhD education is highly relying on the supervisor’s ability to give good supervision, but the entire setting that a PhD student is situated in will contribute to their success in science. The short duration of Norwegian PhD programs combined with a course requirement of 30 ECTS points, calls for well-planned and efficient research, good supervision and course work. For a PhD student to work efficient a good workplace, role models and a good network is also of great importance. Under difficult conditions, the universities see higher drop out and longer completion time numbers from the PhD program, especially for already vulnerable groups.

The national research school of Dynamics and Evolution of Earth and Planets (DEEP) aims to gather the Norwegian natural science expertise relevant for studying the Earth as part of the Solar System and promotes an environment that enables efficiency, at the same time as the scientific quality remains high. Since 2016 DEEP research school has offered specialised scientific courses and a bigger network for the PhD students and their supervisors. We see an increasing interest in joining the research school as part of the PhD program and increasing cooperation between PhD students within the network. With annual conferences and many smaller gatherings, we also ensure that the PhD students form a network amongst each other and find mentors that will strengthen them in their future careers.
Effects of intermittency and land use on the in-stream phosphorus and organic carbon uptake
Authors: Weigelhofer Gabriele , Pucher Matthias
Published: March 2020

Understanding the consequences of the interplay between land use and climate change is among the most pressing challenges of the 21st century for river managers. Over the past decades, agricultural land use has altered nutrient concentrations and stoichiometric ratios in stream ecosystems, thereby affecting aquatic biogeochemical cycles and the coupling among carbon, phosphorus, and nitrogen. In addition, the frequency and duration of droughts has increased dramatically across Europe, causing perennial streams to shift to intermittency and changing the capacity of sediments for the uptake and storage of macronutrients.

Our study aims to understand the effects of drying and re-wetting on the uptake, storage, and release of phosphorus and organic carbon from the benthic and the hyporheic zone of headwater streams under the additional stressor of agricultural land use. In specific, we are interested in the potential coupling and decoupling of phosphorus and dissolved organic carbon cycling in autotrophic and heterotrophic benthic biofilms. We sampled headwater streams before, during, and after the dry period in 2018 and 2019 and performed laboratory experiments with artificial drying and re-wetting and additions of dissolved organic carbon. We measured nutrient uptake and release, microbial biomass, respiration, and the activity of extra-cellular enzymes. The first results show an increased phosphorus release from the sediments immediately after re-wetting, foolowed by a reduced uptake capacity. The uptake of DOC was correlated with phosphorus in autotrophic biofilms, but not in heterotrophic ones.
Salvage logging cause short- and mid-term changes of successional trajectories following forest disturbance
Authors: Thorn Simon
Published: March 2020

Following natural forest disturbances, additional anthropogenic disturbance may alter community recovery and successional trajectories by affecting the occurrences of species, functional groups and evolutionary lineages. However, our understanding is limited of whether rare, common, or dominant species, functional groups, or evolutionary lineages are most strongly affected by an additional disturbance, such as salvage logging. Here, we used a generalized diversity concept based on Hill numbers to quantify the community differences of vascular plants, bryophytes, lichens, wood-inhabiting fungi, saproxylic beetles, and birds following disturbances and experimental salvage logging. Most species groups showed no significant changes in dissimilarities between logged and unlogged plots over the first years of succession, indicating that salvage logging did not contribute to an accelerated decrease of initial dissimilarities. These dissimilarities between communities of were mainly driven by rare species. Trends in species dissimilarities only partially match the trends in dissimilarities of functional groups and evolutionary lineages, with little significant changes in successional trajectories. This talk highlights that salvage logging following natural disturbances can alter successional trajectories in early stages of forest succession following natural disturbances and that those changes persist over time. However, community changes over time may differ remarkably in different taxonomic groups and are best detected based on taxonomic, rather than functional or phylogenetic dissimilarities.
3 failure limits to relief
Authors: Voigtländer Anne , Glade Rachel C. , Turowski Jens M.
Published: March 2020

Reaching the top of a high mountain is a great experience, yet there seem to be several limits. One is the relief of the mountain itself, which constitutes the driving stress consisting of the height, h, and density, ρ of the mass, accelerated by gravity, g and modulated by the slope, α. The material strength required to balance this stress defines the limit to relief. There are three failure modes in which the material strength can be surpassed: shear, compression, and tension. Failure criteria established for shear and compression have been demonstrated to be useful in certain settings, but don’t hold in steep (50-90°), hard and rocky landscapes. For those, we propose a tensile strength limit criterion (TSL). Due to the Poisson effect of normal stress (σn), indirect tensile stresses (σt) arise near free surfaces. The magnitude of these stresses is defined by the Poisson’s ratio (ν) of the lithology and the relief. First-order estimates of different lithologies and their material properties are in good agreement with the height of cliffs and slopes of the same lithology. Similar to the approach by Schmidt and Montgomery (1995) predicting bulk, slope scale material properties from relief, we can invert the tensile strength limit criterion. By this, we can infer material tensile strength and Poisson’s ratio from the maximum slope heights and angle on Earth, and beyond!

In terms of dynamics, the tensile strength limit criterion (TSL) predicts critical yielding at the foot of the slope, causing surface parallel fractures that would lead to further critical yielding and failure slope upward. This pattern of progressive rock failure has been observed in steep rock walls, like El Capitan or Half Dome in Yosemite National Park.

We propose this solely geometrically and stress-controlled criterion not contrary but in addition to existing limit criteria. Implications of the three failure limits to relief are that, (i) over-steepening doesn’t necessarily exist, as there is not only a threshold slope angle but also a threshold height, (ii) there is a transition from one dominant limit and failure mechanism to the other, shifting from shear failure and sliding to toppling and fall, and (iii) internal material property changes, due to chemical and/or mechanical weathering, and subcritical crack growth can evoke a progressive reorganisation of yielding and potential rock failure without external triggering events.