Accumulation Area Research Articles

Capturing Dissipation Charge in Charge Space Accumulation Area for Enhancing Output Performance of Sliding Triboelectric Nanogenerator

AbstractThe charge space‐accumulation effect is one of most effective strategies to boost output performance of the sliding mode triboelectric nanogenerator (TENG) with AC output, by which the shielding layer greatly prevents the air breakdown on the sliding interface and the blank triboarea with charge dissipation on its surface promotes charge accumulation. However, charge dissipation speed depends on the properties of materials and these charges are lost in the air. Herein, a novel strategy is proposed to capture dissipation charge in charge space accumulation area for further enhancing output performance of the sliding TENG. DC output electrodes based on the coupling of triboelectrification and air‐breakdown is designed on both sides of the slider to quickly and completely collect the dissipation charge on the stator and accumulated charge on dielectric tribolayer of slider. Hence, the device has multichannel output to improve output charge to 98%. A new recorded average power density of 5.74 W m–2 Hz–1, 14 times higher than previously reported, is obtained. The coupling relationship between AC and DC output is systematically studied. This work provides a new idea for improving the output and energy harvesting efficiency of TENGs.

Glacier inventory and recent variations of Santa Inés Icefield, Southern Patagonia

ABSTRACT The study of glaciers in remote regions improves our understanding of global glacier change. With an area of 149.31 ± 1.84 km2, the Santa Inés Icefield constitutes one of the largest and least studied and explored glaciated areas of Southern Patagonia. We study the extent and glacier variations of the Santa Inés Icefield over the last 75 years, and we generate the most detailed glacier inventory to date of its 24 constituting glaciers. We estimate surface elevation changes between 2000 and 2014 using Shuttle Radar Topography Mission (SRTM) and TanDEM-X digital elevation models. Our results show a generalized trend of retreat, with a glacier area loss of −9.78 ± 1.52 km2 between 1998 and 2020, with annual rate increase from −0.15 ± 0.01 km2 a−1 (1998–2005) to −0.58 ± 0.10 km2 a−1 (2005–2020), and an average thinning of 0.60 ± 0.26 m a−1 (2σ) between 2000 and 2014. No clear correlation was found between retreat or thinning rates and Accumulation Area Ratio (AAR), terminus slope, aspect, or glacier type. While ERA5 reanalysis data shows no significant climatic trends in temperature or precipitation, a small warming trend below our detection record is the most likely cause of the observed retreat and thinning of the Santa Inés Icefield.

Hanging glacier avalanche (Raunthigad–Rishiganga) and debris flow disaster on 7 February 2021, Uttarakhand, India: a preliminary assessment

A catastrophic debris flow in the Rishiganga and Dhauliganga rivers in Uttarakhand, India, on 7 February 2021 left a trail of disaster. Around 100–150 people lost their lives according to Uttarakhand Chief Secretary statement given to ANI news portal, two hydropower projects were badly damaged and a bridge across the Rishiganga River was washed off in the event. Study shows that the debris flow is caused due to detachment of 0.59 km2 right lobe of a hanging glacier and resultant ice-rock avalanche. This right lobe of the glacier was located over a mountain slope having an average slope of 35° at 4700–5555 m a.s.l. and travelled 12.4 km before hitting the infrastructure projects. Role of precipitation, snow cover, land surface temperature, and permafrost processes were investigated for identifying causes of the event. Since 2012, monsoon precipitation and mean annual land surface temperature (LST) showed significant increasing trend. Snow cover during monsoon months showed increasing trend and September, October and November experienced decreasing trend at glacier elevations. Mean annual LST increased from − 0.3 °C in 2012 to a peak of 0.4 °C in 2016. Central lobe of the glacier advanced during this period and eventually fell off in 2016 suggesting that the LST warming forced reduction of frictional drag at the interface facilitating it advancement and eventual dislodgement. Permafrost modelling suggests warm permafrost below 50 m and conditions favourable for intense frost cracking up to 10–15 m. At ~ 40 m depth, the delayed response of 2012–2016 warming produced peak positive temperature conditions by December and probably facilitated the formation of thin film of water at the deeper layers acting as a lubricant for glacier sliding. It is also suggested that the increase in summer precipitation might have forced thickening of the accumulation area and thereby increasing the shear stress for sliding of the glacier. It is proposed that the recent change in the weather conditions in the region is primarily responsible for this event through geological, glaciological, and permafrost processes. Flood modelling study suggests a flood volume of ~ 10 MCM generating 24.5 m flow depth at the bridge site with 12.7 m/s flow velocity. The event highlighted the need for improved monitoring of the cryosphere areas of the Himalaya to capture the early warning signs for better preparedness.

Global Quaternary Carbonate Burial: Proxy- and Model-Based Reconstructions and Persisting Uncertainties.

Constraining rates of marine carbonate burial through geologic time is critical for interpreting reconstructed changes in ocean chemistry and understanding feedbacks and interactions between Earth's carbon cycle and climate. The Quaternary Period (the past 2.6 million years) is of particular interest due to dramatic variations in sea level that periodically exposed and flooded areas of carbonate accumulation on the continental shelf, likely impacting the global carbonate budget and atmospheric carbon dioxide. These important effects remain poorly quantified. Here, we summarize the importance of carbonate burial in the ocean-climate system, review methods for quantifying carbonate burial across depositional environments, discuss advances in reconstructing Quaternary carbonate burial over the past three decades, and identify gaps and challenges in reconciling the existing records. Emerging paleoceanographic proxies such as the stable strontium and calcium isotope systems, as well as innovative modeling approaches, are highlighted as new opportunities to produce continuous records of global carbonate burial.

Neuroglial relationships and structures of interneuronal communication of the white rat sensorimotor cortex layer v after the common carotid artery ligation

The aim of research was to study changes in neurons, gliocytes and structures of the interneuronal communication system (dendrites, terminals) of the mature white rat sensorimotor cortex (SMC) layer V after the common carotid artery (CCA) bilateral ligation.Material and methods. Acute/chronic incomplete cerebral ischemia was simulated in white Wistar rats by the CCA bilateral ligation. The brain was fixed by perfusion. A comparative histological, immunohistochemical and morphometric evaluation of the related structures in the norm (n=6), and in 1, 3, 7, 14 and 30 days after the common carotid artery bilateral ligation (n=30) was carried out. Nissl and hematoxylin-eosin stains, immunohistochemical reactions for NSE, MAP-2, p38, GFAP and IBA1 were used. The numerical density of pyramidal neurons, astrocytes, oligodendrocytes, microgliocytes and the relative area of p38-positive material (synapse terminals) were determined. Statistical hypotheses were tested by nonparametric methods using Statistica 8.0 program.Results. CCA bilateral ligation led to the appearance of destructively altered dark, hypochromic, vacuolated neurons and shadow cells in layer V of the SMC. These changes were accompanied by a decreased overall numerical density of pyramidal neurons, hyperhydration of the neuropil (processes of dendrites, astrocytes, and synapses), and a pronounced reaction (hypertrophy, proliferation) of all neuroglial cell types. One day after the CCA bilateral ligation, the appearance of neurons with both reversible and irreversible changes was accompanied by an increase in the layer V relative area of edema-swelling zones in the neuropil of the rat SMC up to 14.5 (10.6– 16.4) %, in control – 7.2 (6.9–7.5) %. The maximum content of destructively altered neurons (25%) was found in the rat SMC layer V one day after ischemia. The total number density of neurons in layer V of the SMC decreased by 27.9% after 30 days (Mann–Whitney U Test; p=0.0001). In the areas of damaged neuron accumulation, the content of astrocytes, microgliocytes, and oligodendrocytes increased. The neuroglial index in the control group was 1.30; it was 1.37 in 3 days, it was 1.50 in 7 days, it was 1.63 in 14 days, and it was 1.30 in 30 days. The maximum increase in the number density of microgliocytes was noted after 1 day (Mann–Whitney U Test; p=0.001), oligodendrocytes – 7 days after CCA ligation (Mann–Whitney U Test; p=0.02). According to the data of immunohistochemical typing of p38, two peaks of the relative area of the terminals were revealed: in the acute period (days 1 and 3) and after 30 days. These quantitative changes were first associated with an increase (on the 1st and 3rd day) and then a decrease in the degree of the neuropil hydration. Negative statistically significant strong correlations were detected in 3 days (R=-0.90) and 7 days (R=-0.70) after CCA ligation. This can be explained by hydropic changes in the terminals (destruction of synapses according to the light type). The total numerical density of neuropil terminals decreased to 102300±19400 (by 35.0%) in 3 days after CCA ligation in layer V of white rats and partially recovered to 135000±27100 (24.4%) after 30 days, compared to the animals of the control (157500±20500 per 1 mm2).Conclusion. Thus, the CCA ligation resulted in destructive and compensatory-restorative changes in the structures of interneuronal communication associated with preservation of a significant part of pyramidal neurons and compensatory reorganization of neuroglial relationships in layer V of white rats.

CORE CONCEPT OF GLACIERS AND MELTING GLACIERS EFFECTING THE GLOBAL ENVIRONMENT

Glaciers and ice sheets are found almost in every continent of the world for more than thirty million years and are the large persistent body of perennial accumulation of dense crystalline snow and ice that exist intermittently over a period of time in Polar Regions and in the mountain ranges of landforms. Glaciers are constantly moving and melting because of internal and external pressure and gravity under its own weight. Although extensive glaciers systems lies on different mountain ranges of the landforms in the world i.e. more than seven thousand glaciers lies in Africa, Andes, Alaska, Canada, Greenland, Eurasia, European Alps, New Zeeland, Nepal, Norway, Pakistan, South America and in North America Continent. In the mountain landforms, Pakistan has more glacial ice in the Himalayan Range, Karakorum Range and Koh-Hindu-Kush Range. Glaciers also exist in southern hemisphere in Antarctic Region, in Northern Hemisphere in Arctic Region, Greenland and remaining occurs in the landforms of mountain regions. Glaciers exhibit the different wave like motions that mostly occur internally thus resulting the glacier surge, and waves of velocity. When the glaciers and ice sheet gains a large eroded material through the accumulation of snow above the equilibrium line, the glacier mass is lost through the ablation process and melting water runoff towards the down slope at lowest elevations below the equilibrium line that results the formation of accumulation area, alluvial fan stratification, alluvial plans, arête, askers, braided streams, cirques, crevasses, drumlins, fjords, fracture zones, glacial valleys, ice aprons, and ice bergs. Glaciers are among the oldest and coldest ecosystems on earth that together support the psychrophilic taxa and also impart a requisite water source to shape the downstream ecosystems. But due to global warming and rapid rise in the tropical climate change, melting of tropical glaciers, the fast ablation has contributed the shrinking of global glaciers thus causing the major biological, environmental and human consequences. Subsequently, mountain erosion results the transportation of debris, silt up, floods, and land sliding, raised the global environmental issues. The study includes the core concept of glaciers and melting glaciers effecting the global environments. Keywords: Askers, Craves, Drum line, Fjord, foliations, Gouge, Ice bergs.

Facile Electrodeposition of NiCo2O4 Nanosheets on Porous Carbonized Wood for Wood-Derived Asymmetric Supercapacitors.

Multichannel-porous carbon derived from wood can serve as a conductive substrate for fast charge transfer and ion diffusion, supporting the high-theory capacitance of pseudocapacitive materials. Herein, NiCo2O4 nanosheets, which are hierarchically porous, anchored on the surface of carbonized wood via electrodeposition for free-binder high-performance supercapacitor electrode materials, were proposed. Benefiting from the effectively alleviated NiCo2O4 nanosheets accumulation and sufficient active surface area for redox reaction, a N-doped wood-derived porous carbon-NiCo2O4 nanosheet hybrid material (NCNS–NCW) electrode exhibited a specific electric capacity of 1730 F g−1 at 1 A g−1 in 1 mol L−1 KOH and splendid electrochemical firmness with 80% capacitance retention after cycles. Furthermore, an all-wood-based asymmetric supercapacitor based on NCNS–NCW//NCW was assembled and a high energy density of 56.1 Wh kg−1 at a watt density of 349 W kg−1 was achieved. Due to the great electrochemical performance of NCNS–NCW, we expect it to be used as an electrode material with great promise for energy storage equipment.

Prospects of hydrocarbon exploration in the Laptev sea basin

Background. The geological structure of the Laptev Sea basin is characterized by a rift nature, thus providing no favorable conditions for the presence of hydrocarbon accumulations. However, the lack of seismic information and the absence of well drilling indicate an incomplete stage of the basin exploration.Aim. To analyze the results of geological modeling based on structural mapping and to identify promising areas of hydrocarbon exploration. A geological hydrocarbon study of the Laptev Sea basin was carried out in order to recommend areas for licensing, as well as to identify exploration drilling sites and estimate the total initial prospective geological resources according to the conducted numerical basin modeling. To design sedimentation models and predict reservoir properties in the Laptev Sea basin.Materials and methods. The analysis was based on the data retrieved from production reports for individual large objects in the water area. A model developed by Equinor specialists was used for the basin analysis. The results of hydrocarbon system modeling, the prediction of hydrocarbon saturation obtained from sections of two sample profiles while structural mapping of the basement and top of Oligocene-Miocene sediments were used.Results. Prospective areas of accumulation of hydrocarbons and their confinement were determined. The probability of hydrocarbons in non-anticlinal traps was estimated. Priority areas of hydrocarbon exploration within the unallocated subsoil area were identified. Recommendations for further geological exploration across the license area were formulated.Conclusion. Further exploration of the Yuzhno-Laptevomorsky promising area is recommended by means of analyzing the available data, processing of new geophysical data, updating the geological model and designing 3D seismic surveys within the identified promising areas. In addition, 2D seismic surveys at the regional level should be carried out to define the sedimentary boundaries of the Eastern Artic water area.

Hydrocarbon Accumulation Model Controlled by Overpressure Evolution in the Kelasu Thrust Belt of the Kuqa Depression, NW China

Abstract The Kuqa Depression is the most representative overpressured hydrocarbon accumulation area in western China. The early rapid subsidence since 5 Ma and the strong uplift in the late period have led to a complicated evolution history of the overpressure. Three hydrocarbon charging episodes of Cretaceous in Kuqa Depression were identified based on petrography, microthermometry of fluid inclusions, and fluorescence spectroscopy characteristics. Low-maturity oil, represented by hydrocarbon inclusions with yellow-green-yellow fluorescence, entered the reservoir at circa 5-3 Ma, whereas high-maturity hydrocarbons, as indicated by hydrocarbon inclusions with blue-green-blue fluorescence, charged the reservoir at circa 3-1.2 Ma. Pure gas inclusions with nonfluorescence represented one episode of gas charging from approximately 1.2 Ma to the present. By applying the PVTX simulation method of inclusions, the paleo-pressure evolution of formations was reconstructed, that is, the three-stage model of pressurization-release-pressurization. The coupling relationship between the paleo-pressure evolution of formations and the history of hydrocarbon charging at different stages was reconstructed. This conformed to a compound overpressure-controlled hydrocarbon accumulation model with oil convergence in the early period, oil adjustment along the fracture in the middle period, and rapid gas charging in the late period.

Greenland Ice Sheet Rainfall, Heat and Albedo Feedback Impacts From the Mid‐August 2021 Atmospheric River

AbstractRainfall at the Greenland ice sheet Summit 14 August 2021, was delivered by an atmospheric river (AR). Extreme surface ablation expanded the all‐Greenland bare ice area to near‐record‐high with snowline climbing up to 788 ± 90 m. Ice sheet wet snow extent reached 46%, a record high for the 15–31 August AMSR data since 2003. Heat‐driven firn deflation averaged 0.14 ± 0.05 m at four accumulation area automatic weather stations (AWSs). Energy budget calculations from AWS data indicate that surface heating from rainfall is much smaller than from either the sensible, latent, net‐longwave or solar energy fluxes. Sensitivity tests show that without the heat‐driven snow‐darkening, melt at 1,840 m would have totaled 28% less. Similarly, at 1,270 m elevation, without the bare ice exposure, melting would have been 51% less. Proglacial river discharge was the highest on record since 2006 for late August and confirms the melt‐sustaining effect of the albedo feedback.

CHANGES OF SAND DUNE DISTRIBUTION – A CASE STUDY IKH NUURUUDYN KHOTGOR OF MONGOLIA

Abstract. Ikh Nuuruudyn khotgor in western Mongolia which is characterized by large vertical extend of the sand and area with intensity of desertification in Mongolia. Therefore, it is required to do scientific basis of preservation and usage after examining sand shifting, type, extents of sand in this area. The main objective is to detect the dune sand distribution and its movement in study area, including 1) to determine the geographical conditions 2) to mapping dune sand distribution from topographic map and satellite images, 3) to calculate correlation with climate factors. The variations of spatial and time series of the sand distribution area in this area were delineated using Landsat, NOAA, DEM, MODIS data from 1985-1990-1995-2000-2005-2010-2015-2020 and variations of precipitation and temperature is estimated between these periods. Correlation matrix by Pearson’s correlation coefficient (2) and the ordinary least square estimation of regression analysis was applied in this study to analyze time series of field study area. The result of the study showed sand accumulation area as 1457722.3 hectares (12.7% of total study area) and 1889957.9 hectares (16.5% of total study area) in 1985 and 2020 respectively in this area. Compared to 1985, the sandy area increased by 432235.6 ha in 2020. It is increased by 29.07 % as relative variation percent for three decades in study area. The results showed that the sand distribution changes are negatively correlated with NDVI and precipitation as Pearson’s correlation coefficient. Besides, sand distribution changes are linear correlated with temperature between 1985 and 2020 in study area.

Impact of phosphorus and sulphur levels on growth and productivity of summer sesame

India imports edible vegetable oil to fulfil the domestic requirement and there is a need for enhancement of productivity of oilseeds in the country. Sesame (Sesamum indicum L.), a short duration oilseed, grows well during different seasons under various cropping systems. The average productivity of sesame in India is low and that can be increased by efficient nutrient management. Based on the above facts, a field trial was conducted during summer season of 2021 at Experimental Farm of Centurion University of Technology and Management, Odisha. The experiment was laid out in a split-plot design comprising of four levels of phosphorus (0, 30, 60, 90 kg P2O5/ha) and three levels of sulphur (0, 20, 40 kg S/ha), with three replications. The sesame variety YLM17 was sown on 25th February 2021. The results revealed that the application of 60 kg P2O5/ha registered significantly more growth attributes, namely, plant height (113.8 cm), dry matter accumulation (2899 g/m2) and leaf area index (1.46) than other treatments. Similarly, the treatment being statistically at par with 90 kg P2O5/ha recorded superior yield attributes over other treatments. The seed yield (770 kg/ha), stover yield (2126 kg/ha), oil content (43.7%) and oil yield (336 kg/ha) of summer sesame was more with 60 kg P2O5/ha, but it was statistically at par with 90 kg P2O5/ha. However, 40 kg S/ha registered significantly higher values of growth and yield attributes, seed yield (673 kg/ha), stover yield (1779 kg/ha), oil content (41.5%) and oil yield (282 kg/ha) of sesame. The experiment concludes that the summer sesame can be grown in south Odisha conditions with the application of 60 kg phosphate and 40 kg sulphur per hectare to obtain higher growth and productivity.

Effect of Different Planting Techniques and Puddling Methods on Soil Properties, Growth, Yield, and Grain Quality Characteristics of Rice (Oryza sativa L.)

ABSTRACT The soil structure and production in paddy fields are affected by different options such as planting techniques and puddling methods. To evaluate the effects of planting techniques on soil structure, yield, grain dimensions, and quality of rice at different puddling intensities, a two-year field experiment was conducted as a split plot based on randomized complete block design with three replications at Rice Research Institute of Guilan, Iran, during the spring-summer cropping seasons in 2017 and 2018. The main plots were assigned to three puddling levels (rotary tractor, power tiller conventional puddler, and power tiller rotary puddler), and subplots included three levels (manual transplanting, mechanized transplanting, and direct seeding). The results showed that different puddling practices had significance in the soil bulk density and penetrating depth of the falling cone. The puddling method significantly decreased soil bulk density under a rotary tractor (0.86 g/m3) over the Power tiller rotary puddler (0.96 g/cm3) and conventional puddler (0.95 g/cm3), while the penetrating depth of the falling cone was found to increase in the rotary tractor as compared to puddlers. The tiller number (tillers m−2), spikelet number per panicle, panicle length (cm), and panicle weight were higher under direct seeding in both years. The highest grain yields (4951 kg ha−1and 4681 kg ha−1) were obtained under mechanical transplanting in 2017 and under direct seeding in 2018, respectively. Significantly higher dry matter accumulation (972.37 g/m2) and leaf area index (2.23) were consistently recorded under mechanical transplanting and direct seeding of rice, respectively. Also, direct seeding showed a higher amylose content (AC), gelatinization temperature (GT), and gel consistency (GC) than transplanting. The findings suggest that maintaining a structure of paddy soil through the selection of appropriate puddling intensity and direct seeding could help soil management and provide an alternative to the conventional practice of transplanting.

Tracking the exposure of a pelagic seabird to marine plastic pollution

We aimed to describe how debris originated from coastal cities and fisheries circulates and accumulates along the Argentine continental shelf and its potential interaction with southern giant petrels (SGP, Macronectes giganteus). We used tracking data of 31 SGPs (adults and juveniles) from Patagonian colonies. Lagrangian simulations of particles were released from coastal cities and fisheries. Oceanographic features together with plastic input generated a corridor of debris through the Argentine shelf with areas of high debris accumulation, exposing SGP to plastic consumption. During chick provisioning trips 93.9% of petrel's locations overlapped with areas of plastic accumulation. Although early developmental stages were more exposed to particles from cities, the exposure of petrels (all classes) to debris from fisheries was 10% higher than from cities. Measures to reduce debris from fisheries, would reduce plastic ingestion by giant petrels. Proper management of open sky dumpsters would reduce plastic consumption by chicks and juveniles.

STUDY ON SNOW COVER CHANGE BASED ON THE FUSION OF SENTINEL-2 AND MODIS IMAGES

Abstract. Snow cover is one of the features that change rapidly on the surface, and remote sensing data with high spatial and temporal resolution is an important means to monitor the dynamic changes of snow. However, due to the limitation of satellite conditions, it is difficult to acquire remote sensing images with both high temporal and spatial resolution at the same time. The classical Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM) breaks through the limitations of a single sensor and effectively brings into play the complementary advantages of different observation platforms. In this paper, we take the Babao River Basin within the Qinghai-Tibet Plateau as the study area to investigate the effect of fusion of Sentinel-2 and MODIS (Moderate-resolution Imaging Spectroradiometer) based on the ESTARFM and analyze the fusion-supplemented snow accumulation period data. The results show that the fusion effect of Sentinel-2 and MODIS is good in terms of visual and multiple quantitative indicators. The snow accumulation area of the fused image is also close to the real image. By fusing to supplement the missing Sentinel-2 data, a variation map of snow NDSI (Normalized Difference Snow Index) in the study area was obtained. It was found that the snowfall process in the watershed appeared first in the surrounding uplands and then in the flat areas, and the maximum rate of snow cover area change was 116.17 km2. Therefore, the spatiotemporal data fusion of Sentinel-2 and MODIS based on ESTARFM algorithm can provide reliable satellite remote sensing data with a higher spatiotemporal resolution for snow accumulation change monitoring.

Simulation experiment of fluid-feldspar sandstone interactions and their implications for tight oil and gas exploration of the Yanchang Formation, Ordos Basin, China

Tight oil and gas reservoirs are generally formed in structurally stable and broad buffer zones, with high-quality source rocks developed in large areas and sand bodies in extensive contact with source rocks. Fluids generated from source rock during the thermal maturation are bound to dissolve or precipitate in the adjacent reservoir, which directly restricts the pore development of the reservoir and the direction of oil and gas exploration. To reveal the effect of the total component fluids from source rock on reservoir transformation during hydrocarbon evolution, taking the Yanchang Formation of the Ordos Basin as an example, a fluid-feldspar sandstone interaction simulation experiment of different geological evolution stages under a closed environment was carried out. The results show that the fluids that formed in the hydrocarbon evolution process contain organic acids, and consist mainly of acetic acid. At the peak period of oil generation (VRo = 0.96%), the fluids are the most acidic, the acetic acid yield is the highest, and the average molar ratio is 56.11%. Under closed conditions, after the fluid-feldspar sandstone interaction, the feldspar minerals are altered and clay minerals are generated in situ, which results in a tight reservoir. The feldspar mineral content decreased from 26.1% to 20.8%–22.3%, clay mineral content increased from 11% to 14.30%–14.37%, porosity decreased 5.18%–28.79%, and permeability decreased 4%–34.16%. In addition, a semi-quantitative evaluation method of feldspar dissolution and porosity was established, which was used to evaluate the effect of fluids on feldspar sandstone reservoirs during hydrocarbon evolution. The local semiclosed or open diagenetic system and acid fluid transport and accumulation area beneficial to the formation of the “sweet spot” of tight oil and gas. However, the gentle tectonic setting and extensive contact of sand and mudstone lead to the retention effect of diagenetic fluid in the Yanchang Formation of the Ordos Basin. Oil and gas exploration should be mainly directed to finding sedimentary sand facies bodies favorable for the formation and preservation of primary pores.

Automated Glacier Snow Line Altitude Calculation Method Using Landsat Series Images in the Google Earth Engine Platform

Glacier snow line altitude (SLA) at the end of the ablation season is an indicator of the equilibrium line altitude (ELA), which is a key parameter for calculating and assessing glacier mass balance. Here, we present an automated algorithm to classify bare ice and snow cover on glaciers using Landsat series images and calculate the minimum annual glacier snow cover ratio (SCR) and maximum SLA for reference glaciers during the 1985–2020 period in Google Earth Engine. The calculated SCR and SLA values are verified using the observed glacier accumulation area ratio (AAR) and ELA. We select 14 reference glaciers from High Mountain Asia (HMA), the Caucasus, the Alps, and Western Canada, which represent four mountainous regions with extensive glacial development in the northern hemisphere. The SLA accuracy is ~73%, with a mean uncertainty of ±24 m, for 13 of the reference glaciers. Eight of these glaciers yield R2 > 0.5, and the other five glaciers yield R2 > 0.3 for their respective SCR–AAR relationships. Furthermore, 10 of these glaciers yield R2 > 0.5 and the other three glaciers yield R2 > 0.3 for their respective SLA–ELA relationships, which indicate that the calculated SLA from this algorithm provides a good fit to the ELA observations. However, Careser Glacier yields a poor fit between the SLA calculations and ELA observations owing to tremendous surface area changes during the analyzed time series; this indicates that glacier surface shape changes due to intense ablation will lead to a misclassification of the glacier surface, resulting in deviations between the SLA and ELA. Furthermore, cloud cover, shadows, and the Otsu method limitation will further affect the SLA calculation. The post-2000 SLA values are better than those obtained before 2000 because merging the Landsat series images reduces the temporal resolution, which allows the date of the calculated SLA to be closer to the date of the observed ELA. From a regional perspective, the glaciers in the Caucasus, HMA and the Alps yield better results than those in Western Canada. This algorithm can be applied to large regions, such as HMA, to obtain snow line estimates where manual approaches are exhaustive and/or unfeasible. Furthermore, new optical data, such as that from Sentinel-2, can be incorporated to further improve the algorithm results.

Cosmogenic 10Be constraints on deglacial snowline rise in the Southern Alps, New Zealand

Geochronological dating of glacial landforms, such as terminal and lateral moraines, is useful for determining the extent and timing of past glaciation and for reconstructing the magnitude and rate of past climate changes. In the Southern Alps of New Zealand, well-dated glacial geomorphological records constrain the last glacial cycle across much of the Waitaki River basin (e.g. Ōhau, Pukaki, Tekapo) but its southern sector such as the Ahuriri River valley remains comparatively unconstrained. Recently, there has been debate on the scale and rapidity of mountain glacier retreat during the last glacial termination, particularly the 20–17 ka period in New Zealand. Missing from this debate is well-constrained equilibrium-line altitude (ELA) and associated temperature reconstructions, particularly over the period around 17 ka, which can help us to develop a more complete picture of how past temperature changes drove glacier retreat. Here we report the first glacial chronology dataset from the Last Glacial Maximum (LGM) and subsequent deglaciation from the Ahuriri River valley, Southern Alps, New Zealand (44°23′54″S, 169°39′48″E) based on 38 beryllium-10 (10Be) surface-exposure ages from terminal moraine systems and glaciated bedrock situated at the lower and middle sections of the valley. Our results show that the former Ahuriri Glacier reached its maximum extent at 19.8 ± 0.3 ka, which coincides with the global Last Glacial Maximum. By 16.7 ± 0.3 ka, the glacier had retreat ∼18 km up-valley suggesting at least ∼43% glacier-length loss relative to its full LGM extent. This deglaciation was accompanied by the formation of a shallow proglacial lake. Using the accumulation area ratio (AAR) method, we estimate that the ELA was lower than present by ∼880 m (∼1120 m a.s.l.) at 19.8 ± 0.3 ka, and ∼770 m lower (∼1230 m a.s.l.) at 16.7 ± 0.3 ka. Applying an estimate for temperature lapse rate, this ELA anomaly implies that local air temperature was 5 ± 1 °C colder than present (1981–2010) at 19.8 ± 0.3 ka, while it was 4.4 ± 0.9 °C colder at 16.7 ± 0.3 ka, assuming no change in precipitation. The substantial glacier retreat in response to a relatively small accompanying increases in ELA (110 m) and temperature (0.6 °C) may have been a result of the high glacier-length sensitivity of this glacier system due to its low gradient of former ice surface. Our low warming estimate differs markedly from other deglaciation studies, specifically from Rakaia River valley, which reports a much larger temperature increase at the onset of the last deglaciation. This precisely-dated moraine record along with reconstructed ELA as proxies for atmospheric conditions, provides new insight into post LGM glacier behaviour and climate conditions in New Zealand.

Recent mass-balance changes of Agua Negra glacier (30°S) in the Desert Andes of Argentina

AbstractThe Desert Andes contain >4500 ice masses, but only a handful are currently being monitored. We present the mass changes of the small mountain glacier Agua Negra (1 km2) and of the rest of glaciers in the Jáchal river basin. Remote-sensing data show Agua Negra glacier lost 23% of its area during 1959–2019. Glaciological measurements during 2014–2021 indicate an average annual mass balance of −0.52 m w.e. a−1, with mean winter and summer balances of 0.80 and −1.33 m w.e. a−1, respectively. The Equilibrium Line Altitude (ELA) is estimated to be 5100 ± 100 m a.s.l., which corresponds to an Accumulation Area Ratio (AAR) of 0.28 ± 0.21. Geodetic data from SRTM X and Pléiades show a doubling of the loss rate from −0.32 ± 0.03 m w.e. a−1in 2000–2013, to −0.66 ± 0.06 m w.e. a−1in 2013–2019. Comparatively, the ice losses for the entire Jáchal river basin (25 500 km2) derived from ASTER show less negative values, −0.11 ± 16 m w.e. a−1for 2000–2012 and −0.23 ± 14 m w.e. a−1for 2012–2018. The regional warming trend since 1979 and a recent decline in snow accumulation are probably driving the observed glacier mass balance.

Dynamic particle accumulation on a single wire in transverse field pulsating high gradient magnetic separator

High gradient magnetic separation (HGMS) is widely used to separate feebly magnetic materials. A dynamic buildup equation R4=Et+1 has been built to reflect the change of buildup radius with time and predict these realistic separation processes. In recent years, with the successful application of pulsating slurry in HGMS, the original equation has been increasingly reconsidered to investigate the effect of pulsating slurry. This study explores the particle dynamic accumulation law on a single wire in the transverse HGMS configuration with pulsating slurry. The theoretical expression of the variation of accumulation area with time: Sa2m=Et+1 is derived following the particle trajectory equations. The investigated results of a TV camera system indicate that the realistic buildup process in transverse pulsating HGMS satisfies the derived power equation. The power exponent m is approximately independent of particle size, magnetic field strength, and wire diameter, and it has a positive linear correlation with the pulsating frequency. Similar to previous studies, m is equal to 4 when without pulsation. The coefficient E depends on the force acting on the particle and is related to all parameters affecting the acting force and the power exponent m.