bluuebunny/crossref_metadata_2025 huggingface dataset:
Runout modeling based debris flow risk assessment: a case study from Garhwal Himalaya, India
Authors: Dash Rajesh Kumar , Kanungo Debi Prasanna
Published: March 2020

Debris flows are one of the most frequently occurring and destructive hazards in Indian Himalayas which are often initiated by rainfall.  To minimize the losses due to the destructive power of the debris flows, demarcation of debris flow risk zones is an effective practice for risk reduction. In the present study, site specific debris flow risk assessment has been carried out based upon runout behaviour modeling. Tangni debris flow is an active debris flow in the Chamoli district of Garhwal Himalayas, India which is responsible for disrupting the traffic by blocking the road for days. This debris flow is repetitive in nature and occurs many a times every year in the monsoon during the months between June to September. The Tangni debris flow is categorized as a hill slope debris flow and the failure is considered as a block failure. Runout modeling of Tangni debris flow has been carried out using a Voellmy approach based continuum model. Quantitative information on debris flow intensity parameters such as flow velocity, height and pressure was obtained from the numerical simulation. The calibration of model input parameters was done by back analysis of an event from a particular source area that took place in 2013. Depending upon the amount of materials present in different source areas in the entire source zone and using the calibrated model input parameters, several simulations were performed to assess the flow behaviour of at different possible scenarios. Thus, Tangni debris flow risk assessment has been carried out based on its runout effect modeling. This study revealed that there may be a possibility of damming of river as well as blocking of the National Highway which are located at the downstream of the debris flow.

Key words:  Debris flow, Risk assessment, Runout modeling, Garhwal Himalayas, Voellmy model
The formation model of neotectonic fault zone in the Ulsan Fault Zone, Gyeongsang basin, Korea
Authors: Kang Ji-Hoon
Published: March 2020

The Yangsan Fault Zone (YFZ) of NNE trend and Ulsan Fault Zone (UFZ) of NNW trend are developed in the Gyeongsang Basin, the southern part of the Korean Peninsula, and many active faults and Quaternary faults (ATV and QTY Fs) have been found in these fault zones. The tectonic movement of the YFZ can be explained at least by two different strike-slip movements, named as D1 sinistral strike-slip and D2 dextral strike-slip, and then two different dip-slip movements, named as D3 conjugate reverse-slip and D4 Quaternary reverse-slip. The surfaces of D3 fault in basement rocks are extended those of D4 fault in the covering Quaternary deposits, like the other Quaternary faults within the YFZ. The D3 and D4 faults were formed under the same compression of (N)NW-(S)SE direction. After that, the active faults occurred in the Korean Peninsula under the compression of E-W direction. The ATV and QTY Fs thrust the Bulguksa igneous rocks of Late Cretaceous-Early Tertiary upon the Quaternary deposits or are developed within the Quaternary deposits in the UFZ, showing the reverse-slip sense of top-to-the west movement. This presentation is suggested the formation model of neotectonic fault zone in the UFZ on the basis of the various trends [(W)NW, N-S, (E)NE trends] of fault surfaces of the ATV and QTY Fs found in the UFZ, and the zigzag-form connecting line of their outcrop sites, and the deformation history (the N-S trending 1st reverse-slip faulting by the 1st E-W compression and associated the E-W trending strike-slip tear faulting, the N-S trending 2nd reverse-slip faulting by the 2nd E-W compression) of neotectonic fault zone in the Singye-ri valley around the UFZ, and the compressive arc-shaped lineaments which convex to the west reported in the YFZ.

Acknowledgements: This research was financially supported by a grant (2017-MPSS31-006) from the Research and Development of Active fault of Korean Peninsula funded by the Korean Ministry of the Interior and Safety, and by Ministry of public Administration and Security as Disaster Prevention Safety Human resource development Project.
Role of non-diagonal pressure tensor components in balance of magnetopause current sheet
Authors: Yushkov Egor , Artemyev Anton , Petrukovich Anatoly
Published: March 2020

We study the current sheet model separating a strong magnetic field area from the intense solar wind. We use the ideal MHD equations for ideas proposed by D. Nickeler and T. Wiegelmann to describe the transition region with plasma flows inclined to the boundary field. We show that balance in this case can be supported by nondiagonal components of modified pressure tensor. We discuss the possible application of the results to a description of the Earth’s night-side magnetopause boundary and study influence of solar wind characteristics on magnetopause current structure. We show problems that follow from ideal mhd-approach and from our assumptions about stationarity of two-dimensional CS on examples of magnetopause crossings by MMS mission. We speculate about further model development to day-side and magnetopause flanks application. This work is supported by the RFBR grant N 18-02-00218.
The transformation effect of source rock-derived acidic fluid on carbonate reservoir from simulation experiments
Authors: Ding Qian , He Zhiliang , Zhu Dongya
Published: March 2020

Deep and ultra-deep carbonate reservoir is an important area of petroleum exploration. However, the prerequisite for predicting high quality deep ultra-deep carbonate reservoirs lays on the mechanism of carbonate dissolution/precipitation. It is optimal to perform hydrocarbon generation-dissolution simulation experiments to clarify if burial dissolution could improve the physical properties of carbonate reservoirs, while quantitatively and qualitatively describe the co-evolution process of source rock and carbonate reservoirs in deep layers. In this study, a series of experiments were conducted with the limestone from the Ordovician Yingshan Formation in the Tarim Basin, and the low maturity source rock from Yunnan Luquan, with a self-designed hydrocarbon generation-dissolution simulation equipment. The controlling factors accounted for the alteration of carbonate reservoirs and dissolution modification process by hydrocarbon cracking fluid under deep burial environments were investigated by petrographic and geochemical analytical methods. In the meantime, the transformation mechanism of surrounding rocks in carbonate reservoirs during hydrocarbon generation process of source rock was explored. The results showed that: in the burial stage, organic acid, CO2 and other acidic fluids associated with thermal evolution of deep source rocks could dissolve carbonate reservoirs, expand pore space, and improve porosity. Dissolution would decrease with the increasing burial depth. Whether the fluid could improve reservoir physical properties largely depends on calcium carbonate saturation, fluid velocity, water/rock ratio, original pore structure etc. This study could further contribute to the prediction of high-quality carbonate reservoirs in deep and ultra-deep layers.
Doppler spectral width studies from polar mesospheric summer echoes
Authors: Gudadze Nikoloz , Stober Gunter , Luce Hubert , Chau Jorge Luis
Published: March 2020

Investigation of turbulence in the polar mesopause is essential for a better understanding of dynamical or mixing processes in the region. Polar Mesospheric Summer Echoes (PMSEs), occurring at mesopause altitudes during the summer season, are known to be a result of turbulence-induced fluctuations in the refractive index. The presence of ice particles controls and reduce the free-electron diffusivity in D region plasma, which in turn leads to complex, strong radar echoes at very high frequencies.

Often, Doppler spectral width of radar measurements are associated with the strength of turbulence in the target area and traditionally used to estimate turbulent kinetic energy dissipation rates, a fundamental parameter of the turbulence processes. Besides the cooling of summer mesopause region induced by GW drag, the turbulence produced by GW breaking contributes to the total energy budget due to release of turbulent kinetic energy to heat. We use PMSE spectral width measurements observed by Middle Atmosphere Alomar Radar System (MAARSY) during summer of 2016 to study their summer temporal mean profiles as well as temporal evolution and connection to the atmospheric turbulence at PMSE altitudes - 80 and 90 km. The current theoretical models suggest that the radar reflectivity should correlate to the strength of the turbulence; however, such a relation is mainly observed for the weaker PMSEs. The mean summer behaviour of estimated turbulent kinetic energy dissipation rates shows an increase from lower altitudes up to 90 km. It should be noticed that spectral width measurements contain additional broadening rather than turbulence, so derived energy dissipation rates are “upper values” than expected from pure turbulence. The results are still slightly lower than those known from climatology obtained from rocket soundings, mostly at altitudes close to the maximum occurrence of PMSE, 86-87 km.

We discuss a possible consequence of spectral width measurements under strong PMSEs. In such conditions, the strength of the echo does not correlate with the turbulence intensity, and the observed spectral width is weaker. However, the uniform distribution of spectral width values throughout the echo power is expected from the present theoretical understandings. Based on previous studies, strong PMSEs can also be observed during fossil turbulence. The interpretation of connection the spectral with measurements under fossil turbulence with the turbulence energy dissipation rates and the possibility of using PMSEs for the turbulence studies will be discussed.
Accretionary orogenesis in the Lake Superior region, USA: modern-like tectonics during the Paleoproterozoic
Authors: Viete Daniel R. , Holder Robert M.
Published: March 2020

Terrane accretion and tectonothermal activity associated with the Penokean and Yavapai Orogenies are recorded in various geologic elements of the Lake Superior region, USA, including: (1) mafic–ultramafic terranes comprising tholeiitic basalts and gabbros, boninites and calc-alkaline volcanics and intrusives (e.g., the Pembine–Wausau Terrane), and (2) multiple and distinct, short-length-scale (5–15 km) chlorite–biotite–garnet–staurolite–(kyanite–)sillimanite regional metamorphic isograd sequences. These geologic associations reflect development of a suprasubduction zone system (subduction initiation?) within a Paleoproterozoic ocean in the Orosirian Period, followed by episodes of short-duration (limited-length-scale) tectonometamorphism during accretionary orogenesis in the Statherian Period.

The geologic processes recorded in the Paleoproterozoic terranes of the Lake Superior region are very common in the Phanerozoic. We suggest that Paleoproterozoic tectonism in the Lake Superior region may reflect a West Pacific-type setting, involving distinct, short-lived tectonothermal events marking periods of subduction rollback and lithospheric extension, punctuated by episodes of arc/microcontinent collision, terrane accretion and lithospheric shortening.

The apparent operation of modern-like plate tectonics—accretionary tectonics involving rapid switching between lithospheric extension and shortening—in the Paleoproterozoic requires that a scenario of temporally-varying buoyancy forces at the subduction zone (spatially-varying density of the subducting slab?) be reconciled with the thicker (slower-densifying) oceanic lithosphere expected for a hotter Earth. Such a scenario may be explained by: (1) an anomalously cool mantle (producing anomalously thin oceanic crust) beneath the ocean basin whose closure led to the accretionary orogenesis recorded in the Lake Superior region, or (2) an incredibly long-lived (>> 100 Myr) ocean basin that allowed widespread development of critically-overdense lithosphere prior to subduction initiation and onset of accretionary orogenesis associated with the Penokean and Yavapai Orogenies.

We are currently investigating geologic associations in the Lake Superior region and their potential tectonic origins, using whole-rock geochemistry to test for the tectonic origins of the Pembine–Wausau Terrane, and 40Ar/39Ar geochronology/geospeedometry to constrain time scales for the tectonometamorphism that produced the metamorphic isograd sequence in the region of Republic, Michigan. Results will provide new insights into accretionary tectonics during the Paleoproterozoic, and processes controlling the emergence and evolution of plate tectonics on Earth.
Productivity and carbon export potential in the Weddell Sea, with a focus on the waters near Larsen C Ice Shelf
Authors: Flynn Raquel , Burger Jessica , Smith Shantelle , Spence Kurt , Bornman Thomas , Fawcett Sarah
Published: March 2020

Net primary production (NPP) is indicative of the energy available to an ecosystem, which is central to ecological functioning and biological carbon cycling. The Southern Ocean’s Weddell Sea (WS) represents a point of origin where water masses form and exchange with the atmosphere, thereby setting the physical and chemical conditions of much of the global ocean. The WS is particularly understudied near Larsen C Ice Shelf (LCIS) where harsh sea-ice conditions persist year-round. We measured size-fractionated rates of NPP, nitrogen (N; as nitrate, ammonium, and urea) uptake, and nitrification, and characterized the phytoplankton community at 19 stations in summer 2018/2019, mainly near LCIS, with a few stations in the open Weddell Gyre (WG) and at Fimbul Ice Shelf (FIS). Throughout the study region, NPP and N uptake were dominated by nanophytoplankton (3-20 μm), with microphytoplankton (>20 μm) becoming more abundant later in the season, particularly at FIS. Here, we observed high phytoplankton biomass and diversity, and the community was dominated by diatoms known to enhance carbon export (e.g., Thalassiosira spp.). At LCIS, by contrast, the community comprised mainly Phaeocystis Antarctica. In the open WG, a population of small and weakly-silicified diatoms of the genus Corethron dominated the phytoplankton community. Here, euphotic zone-integrated uptake rates were similar to those at LCIS even though the depth-specific rates were lower. Mixed-layer nitrification was below detection at all stations such that nitrate uptake can be used as a proxy for carbon export potential sensu the new production paradigm – this was highest near FIS in late summer. Our observations can be explained by melting sea ice near the ice shelves that supplies iron and enhances water column stratification, thus alleviating iron and/or light limitation of phytoplankton and allowing them to consume the abundant surface macronutrients. That the sea ice melted completely at FIS but not LCIS may explain why late-summer productivity and carbon export potential were highest near FIS, more than double the rates measured in early summer and near LCIS. The early-to-late summer progression near the ice shelves contrasts that of the open Southern Ocean where iron is depleted by late summer, driving a shift towards smaller phytoplankton that facilitate less carbon export.
Does having access to uncertainty information improve geologic interpretation? You tell us!
Authors: Wilson Cristina , Shipley Thomas , Williams Randolph , Tikoff Basil
Published: March 2020

We are a collaborative group of geoscientists and psychologists seeking to understand the influence of uncertainty information on geologic interpretation. We have developed a five-fold ranking system for characterizing uncertainty in the internal features of an outcrop. From least well constrained to best constrained, these are, Permissive, Suggestive, Presumptive, Compelling, and Certain. In some sense, Permissive and Certain are end members, because there is no variability within these categories. In contrast, the middle three categories - Suggestive, Presumptive, Compelling – have a range of possible values. 

Permissive is the least certain form of evidence.  Permissive suggests that a particular idea or interpretation cannot be ruled out, but it is also not the only available solution.  Suggestive indicates that there is positive evidence for a particular interpretation, but that the evidence also allows the possibility for other interpretations.  Presumptive – defined as “presumed in the absence of further information“– indicates that an interpretation is “more likely right than wrong”. Compelling indicates that the evidence is strongly supportive of the interpretation.  That is, compelling evidence for an interpretation is based on a preponderance of positive evidence.   Finally, Certain indicates that there is a direct and resolvable link between the evidence and a particular interpretation.

Attaching uncertainty rankings to observational data has the potential to improve the sharing and combining of datasets within geoscience, and offers experts the opportunity to weight data (based on uncertainty) during geologic interpretation. At this poster, we are investigating how the availability of uncertainty rankings for strike and dip bedding measurements impacts the structural interpretation of folding rocks in Mecca Hills in Southern California. The geology of the Mecca Hills is often described as three distinct structural blocks (the platform, central, and basin blocks), all of which are highly exposed. The Central block is characterized by highly deformed stratigraphy of Palm Spring and underlying Miocene Mecca formations that define a series of en-echelon anticline/syncline pairs of varying frequency.

We invite expert geoscientists (who have completed at least a Master’s degree) to make structural interpretations of folds (e.g., hinge orientations). You will be provided drone imagery of anticline/syncline pairs, with strike and dip bedding measurements marked at different locations. Each measurement has a corresponding ranking of uncertainty in measurement quality. We will not collect any identifying information, but we will ask you to complete a brief demographic survey.
It’s a macroporous world; we just model in it
Authors: Stewart Ryan , Radolinski Jesse
Published: March 2020

Many soil physical models assume a homogeneous domain and equilibrium conditions, even as decades of evidence have suggested that such states are rarely present in the real world. Instead, natural soils tend to be characterized by physical heterogeneity (e.g., macropores) and non-equilibrium movement of water, solutes and gases (e.g., preferential flow and transport), making it critical to develop physically realistic yet parsimonious descriptors of these processes. In this presentation we discuss recent advances using multi-domain descriptions of soils to model preferential flow and subsurface contaminant movement under field conditions. Here we emphasize the use of simplifying assumptions and straightforward parameterizations, and consider whether those factors constrain the ability of such models to realistically represent underlying physical mechanisms. We also discuss results of an innovative field experiment aimed at constraining macropore porosity, which is a key yet highly uncertain factor in such multi-domain models. Finally, we consider the relevant scales of these multi-domain models, and whether such approaches merit consideration in larger (e.g., hillslope- or catchment-scale) simulations.    
Land Subsidence In Jharia Coalfields, Jharkhand, India – Detection, Estimation And Analysis Using Persistent Scatterer Interferometry
Authors: Karanam Vamshi Krishna Rao , Motagh Mahdi , Jain Kamal
Published: March 2020

Subsidence due to coal mining is an increasingly prominent concern in the management of the coalfields. Jharia coalfields, Jharkhand are the oldest and one of the largest coalfields in India. Due to poor management of the coal mines in the past, land subsidence due to coal fires has become a common phenomenon in Jharia. Throughout the year, several factors such as coal fires, seepage of rainwater into mines, and illegal settlements above the abandoned mines contribute to the mining-induced subsidence. Due to such varied causes, subsidence in mining areas is temporally and spatially irregular. Traditional techniques using GPS, leveling, and total station are tedious, time-consuming, and can measure subsidence only on a point basis.

From the past few years, Interferometric Synthetic Aperture Radar (InSAR) has become a powerful tool to calculate and monitor the land subsidence. Persistent Scatterer Interferometry (PSI) is an advanced time-series interferometry technique, which calculates temporal deformation rates at mm scale with the help of stable pixels in the dataset referred to as Persistent Scatterers. The study aims at the detection and estimation of land subsidence in Jharia coalfield, Jharkhand, India, using the Persistent Scatterer Interferometry (PSI) technique. We used 30 C Band Sentinel-1 SAR images acquired in TOPSAR mode for a period of two years from 2017 to 2019, captured in a descending direction. Data acquired during the dry season are preferred to ensure good coherence. Potential subsidence zones are identified and demarcated using the Differential Interferometry technique in SNAP. PSI analysis is carried out using the StaMPS method. High temporal decorrelation due to the surrounding agricultural land cover and atmospheric interference are significant challenges for the PSI analysis in mining areas. The temporal baseline is adapted accordingly to reduce de-correlation. Atmospheric interference is removed using the TRAIN toolbox using the GACOS correction model. The results show an average subsidence rate in Jharia coal mines of approximately 4 cm/yr. Among the 23 underground mines in Jharia, 6 mines are subsiding at the maximum rate of 12 cm/yr. We identified subsidence in several small coal mines in multiple locations surrounding settlements and agricultural areas that can lead to contamination of groundwater when collapsed. Kustore underground mine covering an area of 1.2 sq. km is the largest subsidence zone in the study area just 200 meters away from the settlements.
Separating the effects of revegetation and sediment-trapping dams construction on runoff decrease in a semi-arid watershed of the Loess Plateau
Authors: Lu Bingjun , Lei Huimin , Yang Dawen , Fu Xudong
Published: March 2020

Runoff decrease as was triggered or exacerbated by human activities over the past decades on the Loess Plateau has grown to be a hot spot increasingly drawing nationwide concerns; distinguishing human-induced runoff-altering factors from one another is of great significance to decision-making on maintaining regional water, ecological and economic security. Sediment-trapping dams (STDs) construction and revegetation are the two major soil conservation practices regarded to have also caused runoff reduction, whose hydrologic effects on the basin scale have not been separated quantitatively. Our study, choosing the Huangfuchuan River Basin as the study area and based on analyses of its hydrologic, climatic and underlying condition changes, proposed a physically-based attribution framework which is able to account for the hydrological effects of STDs, revegetation, land use change and climate change simultaneously, and attributed runoff decrease of the basin among factors including climate change, STDs construction, revegetation and land use cover change. The model-based attribution results indicate that STDs construction caused a 45% (48%) runoff reduction from 1976-1988 to 1989-2000 (2001-2014) and revegetation was responsible for a 30% runoff decrease from 1976-1988 to 2001-2014, with daily simulation implying that the hydrologic effect of revegetation to affect flow magnitudes more consistently than that of STDs. Our study demonstrates that STDs construction is the prime contributor to runoff decrease in the study area and suggests that STDs should be taken into account in similar studies on the Loess Plateau in the future.
Impact assessment of anthropogenic interpositions on hydrological regimes of Godavari and Krishna River Basins, India
Authors: Singh Rahul Kumar , Jain Dr. Manoj Kumar
Published: March 2020

The rivers around the world have been transformed due to various anthropogenic activities and have led to the altered natural flow regime, which is crucial for controlling the essential environmental conditions within the river which in turn forms the biotic diversity. This study quantifies the adverse impacts due to the construction of dams on the hydrology of the Godavari and Krishna River Basins over the last half a century. The quantification of hydrologic alteration at five representative gauging stations of both the rivers has undertaken using Indicator of Hydrological Alteration (IHA) and the Flow Health (FH) methods based on the Range of Variability approach. To evaluate the alterations of flow regime due to the impact of dams (anthropogenic) only, the data for wet and dry years were excluded from the analysis as these represent the impact of climate variability. The IHA results reveal that the average monthly flow (especially from June to September), annual extreme streamflow indices (1-, 3-, and 7-day maxima flow), and rise and fall rates were among the most affected ones when compared to the pre-impacted period. The improved overall hydrologic alteration values for the Dhalegaon, Nowrangpur, K. Agraharam, and Vijayawada stations were found approximately 75.5%, 73.2%, 76.9 %, and 67.9 % respectively, suggesting a significant impact on the overall riverine ecosystem. The flow health (FH) analysis scores for high flow (HF) (K.Agraharam and Yadgir) highest monthly (HM) (Dhalegaon, K.Agraharam, and Yadgir), Low Flow (LF) (Dhalegaon) and flood flow intervals (FFI) (Dhalegaon and Vijayawada) during the test period were in the very high alteration range and these all hydrological indicator represents important ecological functions in both the rivers. The results showed in this study may guide in strategizing the multi-step process needed to improve the riverine ecosystems of Godavari and Krishna Basins and their ecological functioning.

Keywords: Hydrological alteration; Krishna River; Godavari River; Ecosystem
Check Dam-Trapped Farmlands on the Hilly and Ravine Region of the Loess Plateau: Soil Fertility, Crop Yields and Faced Challenges
Authors: Dang Weiqin , Wang Baiqun , Dang Tianmin
Published: March 2020

It is well known that soils are vulnerable to water erosion in the hilly and ravine region of the Loess Plateau. The soil and water losses induced by water erosion have both the on-site and off-site impacts in this region, which causes the on-site decline of soil fertility and reductions of crop yields on sloping farmlands, and drains the generated overland runoff and transports the eroded soils/sediments to the off-site valleys or rivers to threaten the safety of the river systems. Constructing the check dam in the valley has the long history and is regarded as one of the powerful measures to control the soil and water losses in a watershed in this region. On the one hand, the check dam plays the vital roles in trapping the large amounts of sediment generated from the sloping lands and buffering the drainage of runoff yielded form the slopes. On the other hand, the silted sediments or eroded soils by the check dam can develop the relatively flat lands in the valleys. The check dam-trapped lands can be utilized to grow the crops and become the farmlands in a watershed. The investigation indicates that the contents of soil organic matter, nutrients and soil moisture of he check dam-trapped farmlands are higher than those of the sloping farmlands or the terraces. According to the analysis on the survey data on the crop yield evolutions in the watershed in this region, the crop yields of check dam-trapped farmlands have been significantly higher than those of the sloping farmlands and terraces in the scenario of the similar fertilizer input and crop cultivars due to the optimum soil moisture condition in the check dam-trapped farmlands. However, the check dam-trapped farmlands face some challenges under the climate change. Some of the check dam-trapped farmlands or the grown crops in these kinds of lands are susceptible to the damage arose from extreme rainstorms because of the outdated measures of soil and water conservation for these kinds of farmlands. In some watersheds, the check dam-trapped farmlands are prone to salinization due to the outdated management. Therefore，the protective measures and techniques of harnessing salinization for the check dam-trapped farmlands should be updated over time in order to keep the check dam-trapped farmlands safe and maintain the higher crop yields in those farmlands in the hilly and ravine region of the Loess Plateau.
Comparison between Blue Intensity (BI) and Maximum Latewood Density (MXD) tree-ring chronologies from the North American Boreal forests
Authors: Andreu-Hayles Laia , D'Arrigo Rosanne , Oelkers Rose , Anchukaitis Kevin , Wiles Greg , Wilson Rob , Frank David , Davi Nicole
Published: March 2020

Tree ring-width (TRW) and Maximum Latewood Density (MXD) series have been largely used to develop high-resolution temperature reconstructions for the Northern Hemisphere. The divergence phenomenon, a weakening of the positive relationship between TRW and summer temperatures, has been observed particularly in northwestern North America chronologies. In contrast, MXD datasets have shown a more stable relationship with summer temperatures, but it is costly and labor-intensive to produce. Recently, methodological advances in image analyses have led to development of a less expensive and labor-intensive MXD proxy known as Blue Intensity (BI). Here, we compare 6 newly developed BI tree-ring chronologies of white spruce (Picea glauca [Moench] Voss) from high-latitude boreal forests in North America (Alaska in USA; Yukon and the Northwestern Territory in Canada), with MXD chronologies developed at the same sites. We assessed the quality of BI in relation to MXD based on mean correlation between trees, chronology reliability based on the Expressed Population Signal (EPS), spectral properties, and the strength and spatial extent of the temperature signal. Individual BI chronologies established significant correlations with summer temperatures showing a similar strength and spatial cover than MXD chronologies. Overall, the BI tree-ring data is emerging as a valuable proxy for generating high-resolution temperature spatial reconstructions over northwestern America.
Evaluation of land-atmosphere processes of the Polar WRF in the summertime Arctic tundra
Authors: Kim Jeongwon , Lee Junhong , Hong Je-Woo , Hong Jinkyu , Koo Ja-Ho , Kim Joo-Hong , Yun Juyeol , Nam Sungjin , Jung Ji Young , Choi Taejin , Lee Bang Yong
Published: March 2020

Arctic tundra is changing rapidly under the influence of global warming and it is important to know its impact on local and regional climate. Polar Weather Research and Forecasting (PWRF) model is a regional climate model optimized for the polar region and it is a useful tool for studying the Arctic tundra in high resolution. In this study, we evaluate the performance of the PWRF model over the Arctic tundra on clear summer days, when the transition is taking place the most, based on the surface energy fluxes and PBL observations in Cambridge Bay, Nunavut, Canada.

The PWRF simulates a drier and warmer environment in PBL than the observations. Our analysis shows that it is due to the surface energy imbalance in the model caused by the uncertainties in prescribed initial input data and physical parameters rather than structural flaws in the model physics. The performance of the PWRF model over the Arctic tundra is improved when those values are modified based on the observation data.
Within and Between-Events Variability of Strong-Velocity Pulses
Authors: Yen Ming-Hsuan , Ma Kuo-Fong , Cotton Fabrice , Lin Yen-Yu , Lee Ya-Ting
Published: March 2020

Ground motions with strong pulses often bring significant damage to structures. The period and the amplitude of the strong-velocity pulses are critical for structural engineering and seismic hazard assessment. The scaling of pulses periods with magnitudes and the within-event variability of pulses is however poorly understood. In this study, we analyze two moderate earthquakes, namely 2016 Meinong earthquake and 2018 Hualien earthquake, using Shahi and Baker’s criteria (2014) to detect pulses. The observations in this study show that the amplitudes of the pulse decay with the distance from the source to the stations, and is also associated with the rupture direction from the asperity instead of the direction from the hypocenter. In addition, we further perform simulations using a simple FK method to clarify the causes of the variability of the pulse periods within and between events. We test the effect of faults dipping angles and the impacts of the asperity location and size. Through our simulations, we reveal that the amplitudes of the pulses in the shallow dipping fault are larger on the hanging wall than on the foot wall, and that the asperity properties has a large impact on the pulses periods and the amplitudes at the nearby stations. The results show that the asperity characteristics are critical for the occurrence of the strong-velocity pulses. The complete understanding of the kinematics of the rupture is then important for clarifying the effects of the strong-velocity pulses and improving ground-motions predictions.
Strong linkage between irrigation and land surface cooling in India
Authors: Krishnankutty Ambika Anukesh , Mishra Vimal
Published: March 2020

A significant increase in irrigated area has been observed in India since the green revolution, however the influence of irrigation on vegetation health, land surface temperature (LST), and vegetation drought remains to be explored in detail. We develop a high-resolution (250m) remotely sensed data of enhanced vegetation index (EVI) and LST from Moderate Resolution Imaging Spectroradiometer (MODIS) at 8-day temporal resolution for the period 2000-2019 for India. We quantify the role of irrigation in the modulation of EVI, LST, and vegetation stress. The results show significantly higher EVI (p-value < 0.05) and cooler LST (1-2 K) in the irrigation dominated regions during the crop-growing season over the Indo-Gangetic Plain. A poor correlation between vegetation and meteorological drought (Standardized Precipitation Evapotranspiration Index-SPEI and Standardized Precipitation Index-SPI) was found in highly irrigated regions due to irrigation. While irrigation resulted in an elevated vegetation growth, it has caused groundwater depletion in Indo-Gangetic Plain. Simulations (with and without irrigation) using Noah land surface model coupled with the weather research and forecasting (WRF) show cooling due to irrigation that is consistent with the observational evidence.
Sulfur isotopic compositions of the lithospheric mantle sulfides from the Udachnaya pipe (Yakutia)
Authors: Ilyina Olga , Agashev Alexey , Moine Bertrand
Published: March 2020

Sulfide inclusions in Neoproterozoic West African diamonds have revealed mass-independently fractionated sulfur isotopes in them [Smit et.al., 2019]. This feature is a sign of Archean surface changes traced in the mantle. Here we present an S isotope study of the unique fresh mantle deep-seated peridotites, eclogites and pyroxenites with rare or without any secondary alterations from the Udachnaya-East pipe. This research will give better understanding the role of subduction in the formation of the lithospheric mantle under the Siberian craton. Sulfur isotopes (34S/32S which is denoted as δ34S) were measured in the sulfides from eclogites, peridotites and pyroxenites using an Isoprime isotope ratio mass spectrometer (IRMS) with classic configuration with 4 collectors. The sulfides from eclogites are pyrrotite, pentlandites and chalcopyrites. They have δ34S values from +0,67 to +3,08 per mil (‰). Sulfides in peridotites are pyrrotite-pentlandite-chalcopyrites assemblages and they have δ34S values from +0,22 to +3,55 ‰. These δ34S values from eclogites and peridotites are broadly overlap with the field for depleted mantle and chondrites (-1,9 to +0,35‰) [Labidi et.al., 2013; 2014]. Sulfides from pyroxenites are pyrrotite and they have δ34S values from -3,62 to +1,49 ‰. These δ34S values have a wider range than the estimates for depleted mantle. The δ34S values in our samples are close to those in the depleted mantle, but still have deviation from it and do not fractionated. Our data did not detect mass-independently fractionated sulfur isotopes in the mantle samples from the Udachnaya pipe. Thus subduction of the earth’s crust did not play role in the values of sulfur isotopes of the lithospheric mantle sampled by Udachnaya kimberlite pipe. The source of sulfur in these rocks probably was the astenospheric mantle.

References

Smit et. al., 2019

Labidi et. al., 2013; 2014

This study was supported by the Russian Foundation for Basic Research № 18-05-70064
A physical based model to describe effective hydraulic conductivity of the soil mixtures
Authors: Joshi Deep Chandra , Naseri Mahyar , Durner Wolfgang
Published: March 2020

There is a long-lasting interest in obtaining the effective hydraulic conductivity functions of soil mixtures. The few available models to obtain hydraulic conductivity of mixtures are mostly empirical and applicable for saturated conditions. We propose a simple physical model based on the effective medium theory to calculate the effective hydraulic conductivity of soil mixtures with two or more components. The model incorporates the volumetric content of each mixture component and their hydraulic conductivity to calculate the effective conductivity of the mixture. The results of the model were compared with the measured hydraulic conductivity data obtained from the simplified evaporation method using the Hyprop device. Samples were prepared by packing homogeneous mixtures of different soil textures in cylinders with a volume of 250 cm3. Packed soil mixtures were saturated and exposed to evaporation in a climate controlled laboratory with constant air temperature and humidity. The results show an acceptable match between the measured and modeled hydraulic conductivity of the tested soil mixtures. The model can be used as a physical way to describe the effective hydraulic conductivity of mixtures in a wide range of moisture.
MLT Dependence of Contribution of Charge Exchange Loss to the Storm Time Ring Current Decay: Van Allen Probes Observations
Authors: Li Songyan , Luo Hao
Published: March 2020

Much evidence has indicated that charge exchange with the neutral atoms is an important loss mechanism of the ring current ions, especially during the slow recovery phase of a geomagnetic storm. Most of the studies, however, were focused on the global effect of the charge exchange on the ring current decay. The effect on different magnetic local times and L shells has not been achieved. In this study, based on the in-situ energetic ion data (Level 3) from RBSPICE onboard two Van Allen Probes, we study the contribution of the charge exchange, calculated from the differential flux of ions, to the local ring current decay at different magnetic local times and radial distance. Results indicate that the charge exchange effect on the ring current decay shows clear MLT and L dependence. Our study provides important information of spatial distribution of the ring current loss evolution, which could be as a reference during the ring current modeling.
Incorporating large datasets of synthetic tropical cyclones with Global Tide and Surge Model (GTSM) for global assessment of extreme sea levels.
Authors: Chertova Maria , Muis Sanne , Pelupessy Inti , Ward Philip
Published: March 2020

Coastal flooding due to tropical cyclones (TC) is one of the world’s most threatening hazards. The potential increase in the probability of these events in the future, due to climate change, necessitates the more accurate simulation of their potential hazard and resulting risks. This contribution is a step of a MOSAIC (MOdelling Sea level And Inundation for Cyclones) project that aims at developing and validating a computationally efficient, scalable, framework for large-scale flood risk assessment, combining cutting-edge disciplinary science and eScience technologies. As the first step, we develop a computationally efficient method for more accurately simulating current and future TC hazard and risk, by incorporating large datasets of tropical cyclones within the Global Tide and Surge Model (GTSM). The starting point is simulating the spatially explicit extreme sea levels for a large number of synthetic TCs. The difficulty lies in high computational time required for running GTSM models, as with duration of one simulation running on 24 cores of 5 days ( for 1yr). Until present each TC was simulated separately*, which is not feasible when modelling thousands of TC events. Here we present the development of an algorithm for the spatio-temporal optimization of the placing of TCs within GTSM in order to allow optimal use of the computational resources. This can be achieved because the region of influence of a particular TC in the model is limited in space and time (e.g. a TC making landfall in Florida will not materially affect water levels near New York).  This will enable running a large number of TCs in one simulation and will significantly reduce the required total computation time. We investigate a large range of parameters, such as distance between cyclones, time to the landfall, category of cyclone, and others, to optimize the distribution of TC within a single model run. We demonstrate a significant speedup relative to the sequential running of the cyclones within a single simulation.

*Muis, S., Verlaan, M., Winsemius, H. C., Aerts, J. C. J. H., & Ward, P. J. (2016). A global reanalysis of storm surge and extreme sea levels. Nature Communications, 7(7:11969), 1–11.
Inter- and Intragranular age variations: Diffusion or mineral growth? – And what is wrong with the error?
Authors: Schneider Susanne
Published: March 2020

We present various examples of age variations in Potassium-bearing minerals of tectonites obtained by 40Ar/39Ar in situ dating. Age variations in pre-kinematic clasts and syn-kinematic blasts both span large age ranges of significantly different ages values at the cores compared to the rims, calling for petrologic interpretation. Some of the synkinematic grains are overgrown by late- to post-kinematic blast that show consequently the youngest ages values within the samples. The concurrence of textural relation and age value in the case of late- to post-kinematic growth seem to be a robust tool to date the termination of deformation.  

Additional examples where break down reactions lead to dissolution of the prekinematic texture and crystallization of new minerals as coronas, within fractures of strain shadows also yield partly reset age values with larger scatter. The interpretation of those age values is more challenging and might be obscured by the 3D textural geometry of the analysed volume as well as disequilibrium between reactants and products.      

Commonly based on the percentage errors age values are interpreted as being geological significantly different, when errors do not overlap, or as natural geologic scatter, in the case errors overlap. This interpretation is biased by the absolute age value itself and might lead to over- and underestimations of geological events in geologic history. There is a strong need of error calculation that enables geological interpretation of tectonic event independent from their absolute age.
Efficiency and mechanism of lead stabilization in soil of lead-acid battery contaminated site with phosphorus-based materials
Authors: Zhang Zhuo , Guo Guanlin , Li Fasheng
Published: March 2020

Lead contaminated soils occurred at lead-acid battery manufacturing and recycling sites are of great concern. Bench-scale batch experiments of stabilization treatment were conducted using twelve materials and three phosphorus-based materials, KH2PO4(KP), KH2PO4:oyster shell power = 1:1 (by mass ratio; KSP), and KH2PO4:sintered magnesia = 1:1(by mass ratio; KPM), were screened out for lead contaminated soil in an abandoned lead-acid battery factory site. The three materials had higher remediation efficiencies that led to a 92% reduction in leachable Pb and 12% reduction in bioaccessible Pb with the addition of 5% material, while the acid soluble fraction of lead decreased by 41–46%. The lead activity in the soil solution sharply decreased treated by three materials. Pb5(PO4)3Cl was the primary mineral controlling lead solubility in soil treated by KP and KSP and lead activity was related to Pb5(PO4)3OH and Pb5(PO4)3Cl in soil amended with KPM.
Preliminary Evaluation of the Atmospheric Correction Look-Up-Tables (LUTs) of the COCTS-HY1C
Authors: Du Keping , Chen Shuguo , Ding Jing , Lee Zhongping
Published: March 2020

The Chinese Ocean Colour and Temperature Scanner (COCTS), Coastal Zone Imager (CZI) and the novel Ultra-Violet Imager (UVI) which on-board the Chinese Ocean Satellite  HY-1C was launched in September 2018. The atmospheric correction of ocean color sensors was a critical step for accurate retrieval of the remote sensing reflectance, and the look-up-tables (LUTs), for the Rayleigh scattering, the aerosol scattering, and the diffuse transmittance, which were built bases on a Successive Order Scattering Vector Radiative Transfer Solver, played an important role in the processing step. Preliminary evaluation has been performed using the SeaWiFS LUTs and the MODIS data, it showed that COCTS can provide accurate ocean color products.
Long-term trends in ocean chlorophyll: update from a Bayesian hierarchical space-time model
Authors: Beaulieu Claudie , Hammond Matthew , Henson Stephanie , Sahu Sujit
Published: March 2020

Assessing ongoing changes in marine primary productivity is essential to determine the impacts of climate change on marine ecosystems and fisheries. Satellite ocean color sensors provide detailed coverage of ocean chlorophyll in space and time, now with a combined record length of just over 20 years. Detecting climate change impacts is hindered by the shortness of the record and the long timescale of memory within the ocean such that even the sign of change in ocean chlorophyll is still inconclusive from time-series analysis of satellite data. Here we use a Bayesian hierarchical space-time model to estimate long-term trends in ocean chlorophyll. The main advantage of this approach comes from the principle of ”borrowing strength” from neighboring grid cells in a given region to improve overall detection. We use coupled model simulations from the CMIP5 experiment to form priors to provide a “first guess” on observational trend estimates and their uncertainty that we then update using satellite observations. We compare the results with estimates obtained with the commonly used vague prior, reflecting the case where no independent knowledge is available.  A global average net positive chlorophyll trend is found, with stronger regional trends that are typically positive in high and mid latitudes, and negative at low latitudes outside the Atlantic. The Bayesian hierarchical model used here provides a framework for integrating different sources of data for detecting trends and estimating their uncertainty in studies of global change.