Northwest Direction Research Articles

Application of different edge detection methods for faults identification in Anza Basin, Kenya

The shape of gravity anomalies changes due to the disruption of geological bodies’ continuity by fault structures, and their planar contour line characteristics are an important basis for dividing fault structures. However, the traditional potential field boundary identification method has limited ability to detect the boundaries of buried deep geological bodies. Therefore, geophysicists at home and abroad have proposed various new techniques for potential field boundary identification. These techniques aim to effectively and rapidly extract or enhance weak anomaly information about geological bodies’ boundaries. They also aim to delineate the distribution range of field sources. This paper systematically analyzes the principles of various gravity potential field boundary identification methods. It also uses various methods to process and interpret the Bouguer gravity anomalies in the Anza Basin of Kenya. Additionally, it determines the fault system in the basin and carries out structural zoning. The results of the processing of various gravity boundary identification methods with the gravity data in the study area show that a gravity gradient zone is developed in the Anza Basin, where the Bouguer gravity anomalies are all negative and exhibit a large variation range, overall showing a high-southwest and low-northeast trend. The analysis of residual gravity anomaly yields results indicating that the local structure of the study area has obvious structural pattern of the “east-west zone and north-south block”. The study area exhibits developed faults, which can be mainly categorized into two sets with northwest direction and northeast direction orientations. Small-scale northeast-direction faults cut off larger-scale northwest-direction faults. Six tectonic zones were recognized in combination with the gravity anomalies and seismic data in the study area, which include eastern depression, southern uplift, central bulge, western depression, northern slope and western uplift.

Evaluating the impact of geomorphological determinants and Hazards on urban expansion in Rania.

This study aims to evaluate the impact of geomorphological phenomena that are considered natural barriers on the expansion of the city of Rania. The study area is located in the northeast of the Kurdistan region of Iraq and in the northwest of Sulaymaniyah Governorate. Rania is located astronomically between both latitudes (36°:17: 05 - 36°: 12 :30) north and both longitudes (45°:51: 05 -°45 :54 :30) east. The study area is the administrative center of the Rania district, located in the southeast of the district. In terms of administrative units, in the north of Sarkabakan, northeast of Pshdar district, in the south of Dokan Lake, and in the west of each of the chawarqorna, Hajiyawa, and Betwata, The purpose of the research is to create a morphological stage map, geomorphological units, topography, and slope degree that are considered natural obstacles and risks to the expansion of the city of Rania. Since 1977, the area of residential units has reached about 1.18 km2, and the city has continued to expand in stages, reaching 24.74 km2 in 2022. The Kewarsh and Hajila Mountains form a natural obstacle to the expansion of the city in the northeast, northwest, and southwest directions, so the city takes a longitudinal shape. 100% of the urban area is located at an altitude of 491–749 m, and at an altitude of 750–1430 m, there are no residential units. (63.8%) of the study area has a slope of less than 5 degrees. The area of residential units reaches 88.84%, and the degree of slope is higher (35 degrees), as there is no residential area there as a result of the natural geomorphological barriers that limit the expansion of the city of Rania.

Influence of rain and wind dynamics on lodging of rice (Oryza sativa) varieties under rainfed agro-ecology

The present study was carried during rainy (kharif) seasons of 2021 and 2022 at Research Farm of S G College of Agriculture and Research Station (Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh), Jagdalpur, Chhattisgarh to find the characters responsible for lodging of rice (Oryza sativa L.) under natural condition considering weather parameters. A total of 50 varieties of rice were sown in 5.0 m × 5.0 m plots maintaining strip distance of 10 m for providing proper air movement. However, the lodging tolerance of rice varieties was obviously different from each other and 7 key factors that highly influenced the lodging were studied. Rice varieties were sown as horizontal to the length of plot and just orthogonal to width. The strip was uniformly divided in 50 plots with 0.5 m inter-plot distance and 10 m apart to strips. The recommended doses of 80:60:40 kg of NPK/ha were given through straight fertilizers. The mean annual rainfall was received 1408 mm during June–September. In September, slight shifting of wind was recorded with an average speed of 4.49 km/h in north-east and north-west direction in evening and morning hours, respectively which really impacted on basal nodes. September onwards gradually declined in wind speed from 4.40 to 3.15 km/h was recorded. Correlation study was synchronized both the factors, wind and rain together made susceptibility to lodging the varieties like Benisar, Bewara,Chhota Kabari, Chhota Kabari 1, Dagad desi 2, Kakai 1, Kankeri 1, Kanji 1, Kanji, Kantabuta, Kardhana, Karahani, Kari, Karikhuji, Kohikari and Koliya. The variety (Barhi, Benisar, Kalasu and Kanji 1) attained more than 140 cm height coupled with >6 leaves per plant (Chanda and Kanji 1) had higher lodging. Lodging was also observed in leaf length >70 cm that produced more biomass in Bhaya gonad, Butabari and Kankeri 1. Plant height showed the highest eigen value and reverse was in stem thickness; whereas number and length of leaf were almost similar and expressed greater affinity than leaf width and 1st nodal distance in lodging.

Insights on the structural framework of the Egyptian Eastern Desert derived from edge detectors of gravity data

Advanced geophysical techniques are used on Bouguer gravity data to unravel the structural complexity of the Eastern Desert (ED). Using methods such as tilt angle (TA), enhanced horizontal gradient amplitude (EHGA), lineament analysis, and 2D crustal modeling, we are able to differentiate between deep and shallow gravity sources and delineate the area’s geologic features. Using fast Fourier transform, positive and negative anomalies are identified. The positive anomalies are interpreted as uplifted block, anticline features, or intrusive occurrences of denser rocks, whereas the negative anomalies are interpreted as downfaulted blocks, providing crucial insights. Lineament analysis suggests that the predominant tectonic force that shaped the area is in the northwest direction. Integration of TA and EHGA reveals nuanced structural patterns. The constructed structural map indicates a network of uplifted and downfaulted blocks intersected by strike-slip faults with a northeast trend. The 2D crustal modeling illustrates the diverse composition of granitic and basaltic rocks, with a discernible thinning of the continental crust toward the Red Sea offshore area. This significantly advances the understanding of the ED’s geologic evolution, offering valuable insights into the tectonic processes and crustal dynamics.

Detection of infrasound sources using three-years array data in 2019-2021 deployed at the Lützow-Holm Bay region, Antarctica

Time-space variations of infrasound source locations for three years, 2019-2021, were studied byusing a combination of two local arrays in the Lützow-Holm Bay region (LHB), Antarctica. The local arrays deployed at two coastal outcrops clearly detected temporal variations in signal frequency content as well as propagating directions during the three years. A large number of infrasound sources were detected with many located to the north and north-west directions from the arrays. These events were generated within the Southern Indian Ocean and the northern part of LHB with frequency-content of a few seconds; these “microbaroms” are believed to originate from oceanic swells. From austral summer to fall additional infrasound sources are determined to be located to the north-east. These sources might be related to the effects of katabatic winds across the continental coastal area. Furthermore, several impulsive infrasound events during the winter had higher predominant frequencies of a few Hz, higher than the microbaroms. On the basis of a comparison of source locations with sea-ice and glacier distribution form MODIS satellite images, these high-frequency sporadic sources may be cryo-seismic signals associated with cryosphere dynamics near the local arrays. These results suggest that infrasound waves can be used to monitor surface environments in the coastal area of Antarctica.

INTERPRETING FAULT DYNAMICS IN TERMS OF HYPOCENTER RELOCATION AND FAULT CHARACTERIZATION

Southeast and Central Sulawesi are the areas characterized by high tectonic activity due to the presence of the active Matano fault. The seismicity along this fault is high. However, the initial hypocenter often deviates from the fault’s trend line, thus causing the need for earthquake relocation with an improved local structure description. The double difference method stands out as a precise technique for hypocenter relocation, utilizing the data on relative travel time between hypocenter pairs. After relocation, the selected hypocenter facilitates the derivation of a focal mechanism, crucial in determining fault types. In this research, we relocated the hypocenters of 485 events of January 2009 to December 2016, ranging in magnitude from M2 to M6.1, 427 of which showed a pattern close to the general trend of major and minor faults. Seismic offsets along the Matano fault are predominantly oriented in the southeast or northwest direction. Moreover, most of the earthquake activity recorded at a depth of 10 km before relocation is no longer visible. Based on the statistics, the time residuals from –2.5 to +2.5 ms resulting from the relocation procedure are better close to 0 than those of –4.5 to +4.5 ms for the events before relocation. The focal mechanism solutions of 16 events of final relocation are dominated by strike-slip faulting. The Matano fault is predominantly sinistral-type. The seismicity along this fault zone results from an activity of this fault, which is the main source of earthquakes, and from its interaction with the neighboring Palu-Koro and Sorong faults.

Air Pollution Measurement and Dispersion Simulation Using Remote and In Situ Monitoring Technologies in an Industrial Complex in Busan, South Korea.

Rapid industrialization and the influx of human resources have led to the establishment of industrial complexes near urban areas, exposing residents to various air pollutants. This has led to a decline in air quality, impacting neighboring residential areas adversely, which highlights the urgent need to monitor air pollution in these areas. Recent advancements in technology, such as Solar Occultation Flux (SOF) and Sky Differential Optical Absorption Spectroscopy (SkyDOAS) used as remote sensing techniques and mobile extraction Fourier Transform Infrared Spectrometry (MeFTIR) used as an in situ technique, now offer enhanced precision in estimating the pollutant emission flux and identifying primary sources. In a comprehensive study conducted in 2020 in the Sinpyeong Jangrim Industrial Complex in Busan City, South Korea, a mobile laboratory equipped with SOF, SkyDOAS, and MeFTIR technologies was employed to approximate the emission flux of total alkanes, sulfur dioxide (SO2), nitrogen dioxide (NO2), formaldehyde (HCHO), and methane (CH4). Using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) diffusion model, pollutant dispersion to residential areas was simulated. The highest average daily emission flux was observed for total alkanes, with values of 69.9 ± 71.6 kg/h and 84.1 ± 85.8 kg/h in zones S1 and S2 of the Sinpyeong Jangrim Industrial Complex, respectively. This is primarily due to the prevalence of metal manufacturing and mechanical equipment industries in the area. The HYSPLIT diffusion model confirmed elevated pollution levels in residential areas located southeast of the industrial complex, underscoring the influence of the dominant northwesterly wind direction and wind speed on pollutant dispersion. This highlights the urgent need for targeted interventions to address and mitigate air pollution in downwind residential areas. The total annual emission fluxes were estimated at 399,984 kg/yr and 398,944 kg/yr for zones S1 and S2, respectively. A comparison with the Pollutant Release and Transfer Registers (PRTRs) survey system revealed that the total annual emission fluxes in this study were approximately 24.3 and 4.9 times higher than those reported by PRTRs. This indicates a significant underestimation of the impact of small businesses on local air quality, which was not accounted for in the PRTR survey system.

Impact of Climate Change on Distribution of Endemic Plant Section Tuberculata (Camellia L.) in China: MaxEnt Model-Based Projection.

Sect. Tuberculata, as one of the endemic plant groups in China, belongs to the genus Camellia of the Theaceae family and possesses significant economic and ecological value. Nevertheless, the characteristics of habitat distribution and the major eco-environmental variables affecting its suitability are poorly understood. In this study, using 65 occurrence records, along with 60 environmental factors, historical, present and future suitable habitats were estimated using MaxEnt modeling, and the important environmental variables affecting the geographical distribution of sect. Tuberculata were analyzed. The results indicate that the size of the its potential habitat area in the current climate was 1.05 × 105 km2, and the highly suitable habitats were located in Guizhou, central-southern Sichuan, the Wuling Mountains in Chongqing, the Panjiang Basin, and southwestern Hunan. The highest probability of presence for it occurs at mean diurnal range (bio2) ≤ 7.83 °C, basic saturation (s_bs) ≤ 53.36%, temperature annual range (bio7) ≤ 27.49 °C, -7.75 °C < mean temperature of driest quarter (bio9) < 7.75 °C, annual UV-B seasonality (uvb2) ≤ 1.31 × 105 W/m2, and mean UV-B of highest month (uvb3) ≤ 5089.61 W/m2. In particular, bio2 is its most important environmental factor. During the historical period, the potential habitat area for sect. Tuberculata was severely fragmented; in contrast, the current period has a more concentrated habitat area. In the three future periods, the potential habitat area will change by varying degrees, depending on the aggressiveness of emissions reductions, and the increase in the potential habitat area was the largest in the SSP2.6 (Low-concentration greenhouse gas emissions) scenario. Although the SSP8.5 (High-concentration greenhouse gas emissions) scenario indicated an expansion in its habitat in the short term, its growth and development would be adversely affected in the long term. In the centroid analysis, the centroid of its potential habitat will shift from lower to higher latitudes in the northwest direction. The findings of our study will aid efforts to uncover its originsand geographic differentiation, conservation of unique germplasms, and forestry development and utilization.

Identification of Shale Layer in Offshore Field of North East Java Basin for Non-Conventional Oil and Gas Exploration

&lt;p&gt;Non-conventional hydrocarbon exploration is one way to develop shale potential to increase oil and gas reserves in Indonesia. Shale is a rock that is rich in organic material and is a target for non-conventional exploration, because it functions as a source and reservoir rock with a large shale volume and low permeability. Isopach maps can represent the thickness of shale layers and have the potential to become non-conventional exploration targets located in thick shale layers. Based on this background, this research will identify shale layers in the offshore fields of the North East Java Basin for non-conventional oil and gas exploration. The methods used are well logging and seismic methods. This research focuses on determining the location of shale layer depocenters based on isopach maps as a first step in localizing areas that will be targeted for the development of non-conventional hydrocarbon exploration. This research uses 29 2D seismic lines and 2 well data, namely NP-1 and NP-2 wells and the research target is the Kujung Formation and Ngimbang Formation in the offshore area of the North East Java Basin. The results obtained from the isopach map show that the depocenter location of the Kujung Formation is in the northwest direction with a shale thickness of 600-800 meters, while the Ngimbang Formation is in the east direction with a shale thickness of 1000-1300 meters. From the depocenter location, it can be seen that this location has a wealth of organic material so it has the potential to become a source rock and reservoir.&lt;/p&gt;

Integrating the cellular vortex method with remote sensing and geographical information systems in the modelling of coastal flooding around Niger Delta

Coastal areas are increasingly vulnerable to flooding, necessitating accurate simulation methods to understand flood dynamics and their potential impacts. This study employed a Lagrangian framework integrating the cellular vortex method with remote sensing and GIS to simulate flood height distribution in a coastal region. Leveraging climatic and remotely sensed data, alongside ArcMap 10.6.1 for map processing, the research estimated flood magnitude and frequency using the L-moment approach, applied to a forty-year tidal record dataset. Essential input parameters, such as the roughness coefficient and curve number, were derived from land use and land cover characteristics. Additionally, river flow velocity was observed at 0.12m/s, with measured wind speed and direction recorded at 4m/s in the northwest direction. Notably, analysis of the initial flood height distribution map revealed a significant expansion of wetland areas, attributed to observed land use changes between May 2002 and July 2005. Projections for flood height distribution in 2025 and 2050 highlighted the emergence of tidal floods, emphasizing the critical role of considering future climate and land use scenarios in flood dynamics assessment. This research contributes to advancing understanding of flood modeling techniques and underscores the urgency of adaptive measures to mitigate the potential impacts of coastal flooding.

Simulating the Impact of Urban Expansion on Ecological Security Pattern from a Multi-Scenario Perspective: A Case Changsha–Zhuzhou–Xiangtan Urban Agglomeration, China

Rapid urbanization has further expanded the scale of construction land in urban agglomerations. The encroachment of urban land on ecological land has led to severe ecological problems and threatened the stability of ecological security in urban agglomerations. Analyzing the characteristics of future urban multi-scenario expansion and its impacts on ecological security patterns (ESP) can provide guidance for formulating ecologically sustainable management and control Policies. Our study focuses on Changsha-Zhuzhou-Xiangtan (CZX) urban agglomeration as the study area and establishes an ESP. Additionally, a cellular automata (CA) was used to simulate future urban expansion patterns under three scenarios (i.e., natural development scenario, urban development scenario, and ecological conservation scenario). The subsequent analysis evaluates their impact on the ESP. The simulation results indicate that from 2020 to 2030, the CZX urban agglomeration will undergo rapid urban expansion under the natural development scenario and urban development scenario, characterized by outward growth surrounding the existing construction land. In the natural development scenario, urban expansion is primarily concentrated in the northwest and south directions of construction land, the proportion of construction land increased by 2.78%; in the urban development scenario, it is concentrated in the southeast direction of construction land, the proportion of construction land increased by 3.24%. Ecological conflicts in the aforementioned development scenarios primarily arise in the southwestern region of Changsha County, as well as the southern areas of Kaifu District and Furong District. Conversely, under the ecological conservation scenario, the rate of urban expansion has significantly decreased, environmental preservation is upheld at its highest level, and the proportion of construction land only increased by 0.04%. Based on the simulation results, we present targeted recommendations for urban land planning and growth management, as well as the protection, restoration, monitoring, and development of ecological land. These suggestions provide effective guidance for improving the stability of ESP in urban agglomerations and promoting high-quality development in Chinese urban agglomerations.

Native gold from alluvial deposits of the Kyvvozhsky district and its probable primary sources (Volsko-Vymskoe rise, Middle Timan)

Based on the study of typomorphic features of gold from alluvial deposits of the Kyvvozh region of Middle Timan, including industrial placers, the most probable genetic types of primary sources were determined. The size of gold particles varies widely, reaching the size of small nuggets; along with rounded ones, there are weakly rounded and unrounded particles. Many of them have undergone repeated deformations in the form of envelope-shaped bends, dents and tears. Most gold coins have high-fineness rims. Gold always contains Ag, sometimes Cu, Pd and Cu. Gold particles with a block structure with high-silver vein zones are often found. In intergrowths with gold and in the form of inclusions are noted in it pyrite, galena, and occasionally minerals of the cobaltine-gersdorfite series, ankerite, galenobismutite, native bismuth, aurostibite, and also sudovikovite (PtSe2), which was first identified in the region. Three types of gold have been identified: 1 – homogeneous silver-containing, 2 – block with highly silvery vein-like zones, 3 – rare silver-containing with impurities of Cu, Pd. The morphology, composition and structure of placer gold indicate its entry into placers from various sources, including nearby sources. Of greatest interest are the zones of development in Riphean rocks of hydrothermal veinlet-disseminated sulfide mineralization, oriented in the northwest direction, partially exposed during the development of placers. Gold with Cu and Pd impurities is most likely associated with derivatives of mafic magmatism. The Volsko-Vymskoe, as well as the Tsilemskoe and Chetlasskoe uplifts of Middle Timan can be considered promising in terms of primary gold content and deserve further study and prospecting.

Potential Global Distribution and Habitat Shift of Prunus subg. Amygdalus Under Current and Future Climate Change

The genus of Prunus subg. Amygdalus are endangered Tertiary-relict plants that are an essential source of woody plant oil. In order to provide a theoretical basis for better protection and utilization of species in the Prunus subg. Amygdalus. This study collected global distribution information for six species within the Prunus subg. Amygdalus, along with data on 29 environmental and climatic factors. The Maximum Entropy (MaxEnt) model was used to simulate the globally suitable distribution areas for these species within the subgenus. The suitable results showed that the area under the test curve (AUC) values of the simulation results were more than 0.8, indicating that the simulation results have high accuracy. Temperature, precipitation, UV-B, and altitude were critical environmental factors affecting the distribution of each species in Prunus subg. Amygdalus. Currently, the distribution area of six species in this genus, from largest to smallest, is Prunus triloba (Lindl.) Ricker, Prunus tenella Batsch, Prunus amygdalus Batsch, Prunus pedunculata Maxim, Prunus mongolica Maxim and Prunus tangutica (Batal.) Korsh. The simulation results of distribution areas showed that under the ssp2.45 and ssp5.85 scenarios, the potential distribution areas of P. amygdalus, P. tangutica, and P. pedunculata all show a decreasing trend, while the distribution areas of P. mongolica and P. tenella, and P. triloba exhibit an increasing trend. The general distribution of P. amygdalus, P. mongolica, and P. tenella will trend to transfer in a northwest direction. P. tangutica and P. pedunculata were affected by other environmental factors (such as slope, altitude, and soil pH), and the distribution area has a tendency to move northeastward. The P. triloba moved to the southwest. The spatiotemporal distribution patterns of Prunus subg. Amygdalus can be used as a reference for forest management and to formulate species conservation strategies.

Ground-Based MAX-DOAS Observations for Spatiotemporal Distribution and Transport of Atmospheric Water Vapor in Beijing

Understanding the spatiotemporal distribution and transport of atmospheric water vapor in urban areas is crucial for improving mesoscale models and weather and climate predictions. This study employs Multi-Axis Differential Optical Absorption Spectroscopy to monitor the dynamic distribution and transport flux of water vapor in Beijing within the tropospheric layer (0–4 km) from June 2021 to May 2022. The seasonal peaks in precipitable water occur in August, reaching 39.13 mm, with noticeable declines in winter. Water vapor was primarily distributed below 2.0 km and generally decreases with increasing altitude. The largest water vapor transport flux occurs in the southeast–northwest direction, whereas the smallest occurs in the southwest–northeast direction. The maximum flux, observed at about 1.2 km in the southeast–northwest direction during summer, reaches 31.77 g/m2/s (transported towards the southeast). Before continuous rainfall events, water vapor transport, originating primarily from the southeast, concentrates below 1 km. Backward trajectory analysis indicates that during the rainy months, there was a higher proportion of southeasterly winds, especially at lower altitudes, with air masses from the southeast at 500 m accounting for 69.11%. This study shows the capabilities of MAX-DOAS for remote sensing water vapor and offers data support for enhancing weather forecasting and understanding urban climatic dynamics.

The Characteristics of the Chemical Composition of PM2.5 during a Severe Haze Episode in Suzhou, China

During the past decade, the air quality has been greatly improved in China since the implementation of the “Clean Air Act”. However, haze events are still being reported in some regions of China, and the pollution mechanism remains unclear. In this study, we investigate the chemical characteristics of the pollution mechanism of the PM2.5 composition in Suzhou from October 18 to December 15, 2020. A notable declining trend in temperature was observed from 18 to 27 November, which indicates the seasonal transition from fall to the winter season. Four representative periods were identified based on meteorological parameters and the PM2.5 mass concentrations. The heavy pollution period had the typical characteristics of a relatively low temperature, a high relative humidity, and mass loadings of atmospheric pollutants; nitrate was the dominant contributor to the haze pollution during this period. The nitrate formation mechanism was driven by the planetary boundary layer dynamics. The potential source contribution function model (PSCF) showed that the major PM2.5 composition originated from the northwest direction of the sampling site. The aerosol liquid water content presented increasing trends with an increasing relative humidity. The pH was the highest during the heavy pollution period, which was influenced by the aerosol liquid water content and the mass loadings of NO3−, SO42−, NH4+, and Cl−. The comprehensive analysis in this paper could improve our understanding of the nitrate pollution mechanism and environmental effects in this region.

Exploring the use of ground-based remote sensing to identify new particle formation events: A case study in the Beijing area

New Particle Formation (NPF) is an important process of secondary aerosol production in the atmosphere, which has significant impacts on the Earth's radiation balance, air quality, and climate change. In this study, we develop a method to identify NPF events based on ground-based remote sensing. We propose a proxy to characterize NPF events utilizing ground-based remote sensing of gaseous precursors and aerosol optical depth (AOD). This proxy is applied to identify the NPF events in Beijing in the winter of 2022 and tested by comparison with in-situ observations of aerosol particle number size distributions (PNSD) from SMPS. The comparison shows that the NPF events for regional nucleation can be identified effectively when the threshold for sulfur dioxide and organic gases (i.e. formaldehyde) are determined as 0.44×10-4 and 1.07×10-4. Based on these thresholds, the NPF events can be identified at a high percentage (84%) compared with in-situ observations. The relationship between identification of NPF events and meteorological conditions shows that NPF events in Beijing winter occurred more frequently under weather conditions with north-west wind direction, high wind speed and low relative humidity.

Asymmetric Dust Accumulation of the PDS 70 Disk Revealed by ALMA Band 3 Observations

The PDS 70 system, hosting two planets within its disk, is an ideal target for examining the effect of planets on dust accumulation, growth, and ongoing planet formation. Here, we present high-resolution (0.″07 = 8 au) dust continuum observations of the PDS 70 disk in ALMA Band 3 (3.0 mm). While previous Band 7 observations showed a dust ring with slight asymmetry, our Band 3 observations reveal a more prominent asymmetric peak in the northwest direction, where the intensity is 2.5 times higher than in other directions and the spectral index is at the local minimum with α SED ∼ 2.2. This indicates that a substantial amount of dust is accumulated both radially and azimuthally in the peak. We also detect point-source emission around the stellar position in the Band 3 image, which is likely to be free–free emission. We constrain the eccentricity of the outer ring to be e < 0.04 from the position of the central star and the outer ring. From the comparison with numerical simulations, we constrain the mass of PDS 70c to be less than 4.9 MJupiter if the gas turbulence strength α turb = 10−3. Then, we discuss the formation mechanism of the disk structures and further planet formation scenarios in the disk.

Unveiling the elemental composition, sources and health impacts of PM10 over the central Indo-Gangetic plain (IGP) of India

Unveiling the elemental composition, sources and health impacts of PM10 over the central Indo-Gangetic plain (IGP) of India

Landsat Analysis of Terraced Thermokarst Lake Variability on Alaska's Coastal Plain

ABSTRACTThermokarst lakes are abundant across the Arctic landscape. Although they are largely understood to form due to thawing permafrost and subsidence, these lakes exist in a variety of forms, shapes, and sizes. Some lakes across the Arctic exhibit shallow subaqueous terraces. The terraces have previously been shown to maintain permafrost beneath them due to the presence of bedfast ice during most of the year, whereas a talik develops beneath the deeper central pool. However, the formation of these terraces and their prevalence across the Arctic are currently unknown. In this study, we mapped the locations of thermokarst lakes and their terraces in the Alaska coastal plain using Landsat imagery. We found that terraces are larger and more abundant in sandy deposits, occupying an average of 40% of the lake area, compared to 20% of the lake area in non‐sandy lithologies. Terraces are most often found on the eastern and western lake shorelines, likely associated with regional wind directions, forming on the long sides of northwest–southeast oriented lakes. We propose a conceptual model for terrace formation in sandy deposits that describes the growth of shallow littoral shelves that protect the eastern and western shorelines from erosion while allowing lake extension in the northwest and southeast directions. Finally, given the close association between bedfast ice, talik extent, and the shallow subaqueous terraces, we suggest that mapping of these relatively stable terraces may provide insights about talik extent across the Arctic coastal region. Continued warming and changes to lake ice regimes are likely to increase talik extent, which may be easily observable by temporal analysis of terrace abundance and extent in widely available remotely sensed imagery.

Features of Temporal Variability of the Concentrations of Gaseous Trace Pollutants in the Air of the Urban and Rural Areas in the Southern Baikal Region (East Siberia, Russia)

This article presents the results of the automatic monitoring of the concentrations of gaseous impurities of sulfur and nitrogen oxides in the ground-level atmosphere of the urban and rural areas in the Southern Baikal region (East Siberia, Russia). The study was conducted from 2020 to 2023 at the urban Irkutsk station and the rural Listvyanka station located at a distance of 70 km from each other. We calculated the main statistical characteristics of the variations in the concentrations of nitrogen oxides and sulfur dioxide in the ground-level atmosphere and determined a nature of variability in their concentrations on various time scales: annual, weekly, and daily. Annual variabilities of gaseous pollutants in the ground-level atmosphere above the Irkutsk city and the Listvyanka settlement were similar and showed the highest values in winter and the lowest in summer. The daily and weekly dynamics of the nitrogen oxide concentrations in the urban area clearly depended on the increase in the road traffic during rush hours (morning and evening). In the rural area, there was no such dependence. In this area, the daily and weekly variability in the concentrations of nitrogen oxides and sulfur dioxide mainly depended on natural meteorological processes. The work systematizes the meteorological parameters at which the largest amount of anthropogenic impurities enters the air basin of Lake Baikal. The maximum values of acid-forming gas concentrations were observed when the air masses were transferred from the northwest direction, which corresponds to the location of sources in the territory of the Irkutsk–Cheremkhovo industrial hub—the largest concentration of anthropogenic objects in the Irkutsk region.