Source Region Research Articles

A new look at disk winds and external photoevaporation in the σ-Orionis cluster

Disk winds play a crucial role in the evolution of protoplanetary disks. Typical conditions for star and planet formation are in regions with intermediate or strong UV radiation fields produced by massive stars. In these environments, internally or externally driven winds can occur. The is the ideal site to study disk winds under these conditions; its outer parts, exposed only to mild UV fields, can be used to study disk evolution, while its innermost regions can be used to study the effect of external irradiation. Our goal is to study disk winds in the by looking at the properties of optical forbidden lines, and comparing them with other star-forming regions at different ages, to search for potential signatures of disk evolution and external photoevaporation. We analyzed the and 6716 lines using high-resolution MIKE spectra for a sample of 27 classical T Tauri stars and complemented by intermediate-resolution X-shooter data. We decomposed the line profiles into multiple Gaussian components. We calculated luminosities, line ratios, and kinematic properties of these components. We find that the luminosity and kinematic properties for our are similar to those found in low-mass star-forming regions. The frequency of single-component profiles reflects the expected evolutionary stage given the intermediate age of 3-5 Myrs). This points to internal processes contributing to the line emission. However, the highly irradiated disks in the cluster do not follow the accretion luminosity- line luminosity relation found in low-mass star-forming regions, and all exhibit single-component line profiles. Line ratios of highly ionized species of NII and SII show higher ratios than typical values found in sources in low-mass star-forming regions. These are interpreted as signatures of external photoevaporation. We show the potential of using multiple forbidden emission lines to study both internally and externally driven disk winds. In the case of the innermost regions are clearly affected by external irradiation, as evidenced by the lack of correlation in the OI luminosity relation. The broad line widths of close-in sources, however, indicate a possible contribution from internal processes, such as magnetohydrodynamical winds and/or internal photoevaporation. This suggests a coevolution of internal and external winds in the while pointing toward a new way to disentangle these processes.

ICRP pregnant-female mesh-type reference computational phantoms part 1: development of fetal phantoms.

The International Commission on Radiological Protection (ICRP) decided to develop pregnant-female reference computational phantoms, including the maternal and fetal phantoms, through its 2007 general recommendations. Acknowledging the advantages of the mesh geometry, the ICRP decided to develop the pregnant-female mesh-type reference computational phantoms (MRCPs) for 8-, 10-, 15-, 20-, 25-, 30-, 35-, and 38-week fetal ages directly in the mesh format. As part of this process, the present study developed the mesh-type fetal phantoms. The reference blood-inclusive organ masses, elemental compositions, and densities were established based on various scientific literatures. Then, the phantoms were developed in accordance with the established reference dataset while reflecting the anatomical features of the developing fetus, such as fetal-age-specific anthropometric parameters, bone ossification, and contents formation time. The phantoms were developed in the tetrahedral-mesh format and can be implemented in the general-purpose Monte Carlo codes (i.e., Geant4, PHITS, MCNP6, and EGSnrc) without the necessity of the voxelization process. To explore the dosimetric impact of the developed phantoms, photon specific absorbed fractions (SAFs) were computed for energies between 10-2 to 101 MeV for the fetal liver and spleen as source regions and self-irradiation and cross-irradiation to the fetal brain, lungs, and urinary bladder wall as target regions. The SAFs showed the fetal-age-dependent dose trends (i.e., SAF decreases with increasing fetal age) due to organ masses increases via fetal growth. The mesh-type fetal phantoms, as part of the ICRP pregnant-female MRCPs, will be used to calculate reference dose coefficients for fetal members of the public for both the current and future ICRP general recommendations.

Garnet as Indicator of Pegmatite Evolution and Mineralisation: The Case Study of the Koktokay Pegmatites, Altai, NW China

ABSTRACTPegmatite‐related deposits are among the most crucial sources of rare‐metal elements such as Li, Be, Nb, Ta, Rb, Cs and Sn. Despite nearly 2 centuries of extensive study, the mechanism governing the rare‐metal mineralisation of pegmatites remains contentious. Alongside the enrichment of rare‐metal elements in the source region, differentiation processes after emplacement may have also contributed to the concentration and mineralisation of rare‐metal elements. However, compared to fractional crystallisation, limited attention has been directed towards the role of liquid immiscibility in pegmatite mineralisation. In this study, the major and trace element compositions of garnets in the internally zoned (Be‐rich) and un‐zoned (barren) pegmatites from the Koktokay pegmatite field in Altai, NW China, were analysed to evaluate the role of liquid immiscibility in the generation of rare‐metal mineralised pegmatites. The studied garnets belong to the almandine‐spessartine solid solution and are magmatic in origin. The inter‐ and intra‐crystal chemical variations observed for the studied garnets were produced by a combined effect of magmatic crystallisation and liquid immiscibility. The decrease in the spessartine component of garnets from the margins inward and the depleted MREE–HREE distribution patterns of garnet domains indicate the onset of liquid immiscibility, which correlates with the Be mineralisation of the internally zoned pegmatite. Therefore, the chemical variations in garnets from the Koktokay pegmatites suggest a clear genetic relationship between liquid immiscibility and rare‐metal mineralisation, and they are proposed as potential indicators for prospecting rare‐metal ore deposits.

A high-performance capacitorless 1T-DRAM based on Z-shaped electron-hole bilayer TFET and SiGe memory window

Abstract In this paper, a novel capacitorless dynamic random access memory (Z-EHBTFET 1T-DRAM) is designed based on a Z-shaped electron-hole bilayer tunnel field-effect transistor and a SiGe memory window, and its storage performance is systematically analyzed and studied in detail through numerical simulation. A large number of electrons can be induced in the inverted L-shaped channel of Z-EHBTFET 1T-DRAM using gate 1 to create an electron-hole bilayer together with the source region, which increases the line tunneling electric field and ultimately improves the sensing margin (SM) and read current ratio (IR1/IR0). SiGe memory window helps to improve the storage capacity of holes, aiming to improve the retention time (RT) and SM. By optimizing the Ge-composition and width of the SiGe memory window, the thickness of the I-shaped channel, and the gate gap length, the SM of 2.03 μA/μm, IR1/IR0 of 3.58 × 104, and RT of 1.2 s can be obtained for Z-EHBTFET 1T-DRAM. Compared with most reported 1T1C-DRAMs and traditional 1T-DRAMs, it has better storage performance. Moreover, it can operate at a lower programming voltage while ensuring superior storage performance, making it has great application prospect in the low power consumption field.

Characterizing and sourcing metal air contamination coupling concentrations and lead isotopes from moss biomonitoring in urban cemeteries

Populations are constantly exposed to airborne metals, in particular in urban areas. Despite their proven links to health issues, their origin and fate are still subject to debate. Bioindicators, by taking up and cumulating atmospheric metals over time, have been widely used to proxy environmental quality over large areas, at various time scales. Using the example of the Paris region, we investigated the potential for the Grimmia pulvinata moss species to both characterize air metal contamination and to identify its main sources. To this end, we coupled metal/metalloid (Al, As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, Sr, V and Zn) concentrations and Pb isotope ratios from samples collected in cemeteries in the city and its suburbs. Metal enrichment factors ranged between 2 and 10 for As, Cr, Fe, Ni, Sr, V, between 50 and 100 for Cu, Pb and Zn and > 100 for Cd and Sb, indicating a dominant anthropogenic origin. Principal component analysis showed that 3 principal components explained 89% of the metal variations: (i) European atmospheric background, (ii) regional urban sources, and (iii) resuspension of regional soils. This was corroborated by Pb isotope ratios, whose variations were modelled by a ternary mixing that considered the same 3 emission sources. Using a MixSIAR isotope model, we reveal that the European atmospheric background contributes slightly (< ~ 5%) and that within 20 km of the city center bioindicators are mostly impacted by urban sources (contributions: 50–80%). Samples collected > 20 km show almost equal contributions of the endmembers representing urban activities and agricultural soil resuspension.

Fe/O Variations Relative to Source Longitude and Heliospheric Current Sheet in Large Solar Energetic Particle Events

The Fe/O enhancements exhibit significant variations in gradual solar energetic particle (SEP) events. Several causes have been suggested including transport effects in the interplanetary space and flare contribution. In this study, we investigate the relationship between the integrated Fe/O ratios of 27 gradual SEP events, locations of associated solar flares, and positions along the heliospheric current sheet (HCS) between 2010 and 2014. We employ synchronic potential field source surface (PFSS) extrapolations at 2.5R ⊙, derived in near real-time using Artificial Intelligence (AI)-generated far side and Helioseismic and Magnetic Imager (HMI) magnetograms, referred to as AIHMI-PFSS extrapolations. We examine low-energy (∼0.5 MeV/nucleon) Fe and O ion measurements obtained from Suprathermal Ion Telescope on Solar Terrestrial Relations Observatories and Ultra Low Energy Isotope Spectrometer on Advanced Composition Explorer. We found a moderate anticorrelation between the Fe/O ratios and the absolute longitudinal separation angles from the source regions to the spacecraft magnetic footpoints. Furthermore, we investigate the variations in Fe/O ratios with respect to the separation angle, grouped by the same and opposite polarity sectors of the SEP source regions. We found that the mean and median Fe/O values are higher in the same polarity group compared to the opposite polarity group, with the largest contrast at separation angles between 25° and 50°, where the values are approximately 3 times larger. The results imply that the enhanced Fe/O ratios in the examined gradual SEP events are likely associated with direct source regions, while the HCS affects particle transport.

Reappraising the eruptive history of the Alchichica Maar Volcano (Mexico) based on Sr–Nd isotopes: Understanding the role of the magma source region on the growth of small-volume volcanoes

Alchichica Maar is in the eastern sector of the Trans-Mexican Volcanic Belt, where volcanics range from basalts to rhyolites, with 87Sr/86Sr and 143Nd/144Nd values between 0.70293 to 0.70447 (εSr = −21.1 to −4.5) and 0.512733 to 0.512949 (εNd = +3.4 to +6.2), respectively. In this study, Nd and Sr isotopic data and new major and trace elements compositions are provided for the lava flow, the scoria cone, and the phreatomagmatic deposits composing Alchichica Maar Volcano. These results are used in combination with published data to reexamine its eruptive history, though to be formed by more than one eruptive event. The cogeneticy of the magmas that fed the eruptions of these deposits is examined to infer the role of the deep magma source region and post-magmatic alterations on the construction of the Alchichica Maar magmatic system. Alchichica samples present 87Sr/86Sr values between 0.70387 and 0.70447 (εSr = −9.0 to −0.4) and 143Nd/144Nd values from 0.512749 to 0.512773 (εNd = +2.0 to +2.8). While the 87Sr/86Sr values suggest a slight increment in radiogenic 87Sr from the pre-maar lower lava flow to the upper maar eruptions indicative of magma contamination within the upper crust and by hydrodynamic mingling during the phreatomagmatic phases, the slight variation in Nd isotopes suggest an overall homogeneous source where small batches of magmas formed episodically to feed monogenetic eruptions, which subsequently yielded the pre-maar lava flow, the pre-maar surge, the scoria cone, and the maar units. This study reinforces the idea that an already “tapped” source region of a monogenetic volcano may become fertile again, and new eruptions can occur from near or old vent sites. It also highlights the hazardous potential of small-volume volcanoes.

Anthropogenic actinides in seawater and biota from the west coast of Sweden

The assessment of the origin of the anthropogenic contamination in marine regions impacted by other sources than global fallout is a challenge. This is the case of the west coast of Sweden, influenced by the liquid effluents released by the European Nuclear Reprocessing Plants through North Sea currents and by Baltic Sea local and regional sources, among others. This work focused on the study of anthropogenic actinides (236U, 237Np and 239,240Pu) in seawater and biota from a region close to Gothenburg where radioactive wastes with an unknown composition were dumped in 1964. To this aim, a radiochemical procedure for the sequential extraction of U, Np and Pu from biota samples and the subsequent analysis of 236U, 237Np, 239Pu and 240Pu by Accelerator Mass Spectrometry was developed. The method was validated through the study of two reference materials provided by the International Atomic Energy Agency (IAEA): IAEA-446 (Baltic Sea seaweed) and IAEA-437 (Mediterranean Sea mussels). The 233U/236U atom ratio was also studied in the seawater samples. The obtained results indicate that the North Sea currents and global fallout are the major sources for 236U, 237Np and 239,240Pu to the studied area, without clear evidence of other local sources. Complementary, information on the Concentrations Factors (CF) in biota was obtained, for which the available information is very scarce. For seaweed, CF values of (4.07 ± 0.90)·103, 61 ± 22 and 76 ± 16 have been obtained for Pu, Np and U, respectively. Lower CF values of (3.37 ± 0.78)·102, 34 ± 10 and 15.9 ± 3.4 for Pu, Np and U, respectively, have been obtained for mussels.

Characterizing variability in geochemistry and mineralogy of western US dust sources

Dust events originate from multiple sources in arid and semi-arid regions, making it difficult to quantify source contributions. Dust geochemical/mineralogical composition, if the sources are sufficiently distinct, can be used to quantify the contributions from different sources. To test the viability of using geochemical and mineralogical measurements to separate dust-emitting sites, we used dust samples collected between 2018 and 2020 from ten National Wind Erosion Research Network (NWERN) sites that are representative of western United States (US) dust sources. Dust composition varied seasonally at many of the sites, but within-site variability was smaller than across-site variability, indicating that the geochemical signatures are robust over time. It was not possible to separate all the sites using commonly applied principal component analysis (PCA) and cluster analysis because of overlap in dust geochemistry. However, a linear discriminant analysis (LDA) successfully separated all sites based on their geochemistry, suggesting that LDA may prove useful for separating dust sources that cannot be separated using PCA or other methods. Further, an LDA based on mineralogical data separated most sites using only a limited number of mineral phases that were readily explained by the local geologic setting. Taken together, the geochemical and mineralogical measurements generated distinct signatures of dust emissions across NWERN sites. If expanded to include a broader range of sites across the western US, a library of geochemical and mineralogical data may serve as a basis to track and quantify dust contributions from these sources.

Inferring long‐distance movements of insects using combined hydrogen isotope and genetic analyses: A case study of the African edible bush‐cricket

Abstract The degree to which individuals within populations vary in whether, how far and what direction they disperse is central in order to understand many foundational questions in ecological entomology, including factors determining population and invasion dynamics, species' ability to respond to climate change or when designing conservation strategies for threatened species. This study combined stable hydrogen isotope analysis of nymphal and adult wing chitin with population genetic analysis of the cytochrome c oxidase subunit I (COI) gene to understand long‐distance movements of African edible bush cricket (Ruspolia differens) in East Africa. Results revealed that at most 77% of non‐swarming adults and 85% swarming adults originated locally, that is, within a range of a few hundred kilometres. In contrast, non‐local adults captured in Uganda likely originated from Ethiopia, Kenya or South Sudan based on the H isotopic evidence. Genetic analysis revealed 150 COI haplotypes with no significant differentiation among geographic source regions and no evidence of genetic isolation by movement distance. The observed frequent long‐distance movements, together with the historical records, which indicate that the swarm movements can be irregular in their direction, suggest that the movements represent nomadism rather than regular long‐distance migration. Our results thus provide a valuable case study of what characterizes nomadic movements in insects, which have been one of the outstanding open questions in movement ecology of animals.

Ice nucleating ability of mineral particles from subtropical South American deserts

Mineral aerosols are one of the most important ice nucleating particles (INPs) because their efficiency in nucleating ice, wide transport and largest mass contribution to particulate matter in the atmosphere. They are sourced from the arid regions of the world. In this context, this work evaluates the INP potential of fourteen topsoil samples collected from subtropical South American deserts, the major source of mineral aerosols in South America, in the immersion freezing mode. Samples were obtained from three distinct regions located in the South American Arid Diagonal and recognized as potential dust source areas: the Puna-Altiplano Plateau in the north, the central-west of Argentina, and Patagonia in the south. In general, results reveal that samples from the Puna-Altiplano and Patagonia regions, and the central-west of Argentina region exhibit the highest and lowest INP abilities, respectively. The active sites per unit surface area for a given temperature were calculated and compared with previously reported values. The results demonstrate that soil mineral particles from the region of study exhibit ice nucleating abilities comparable to the inorganic fraction of agricultural soils of central Argentina. No direct relationship was identified between INP ability and the major minerals observed in the samples. This study is the first to analyze the ice nucleation properties of soil samples collected along the South American Arid Diagonal and one of the few in South America. Since the analyzed topsoil particles were collected from potential dust source regions, this work contributes to understanding the role of aerosols in initiating atmospheric ice formation, providing valuable data for empirical parameterizations. This could contribute to the improvement in the performance of climate models, as the obtained results suggest that the underestimation of coarse and super-coarse aerosols at altitudes relevant for cloud formation may lead to underestimations in INP concentrations, particularly in regions near to the emission sources.

Investigate the important role of 3-D meteorological patterns in haze formation in the context of pollution reduction

Since 2013, heavy pollution episodes have occurred frequently over the North China Plain after unprecedented efforts to reduce primary pollutants. In this study, a pollution process in Tianjin, a typical city in North China, was selected to investigate the impact of 3-D meteorological patterns on PM2.5 and meteorological element profiles obtained by tethered balloons and meteorological towers. The pollution episode lasted 4 days with hourly PM2.5 concentrations exceeding 150 μg·m−3 for 81 h and a peak concentration of 377 μg·m−3. In the early stages of the first pollution period, wind speed with height showed an almost opposite trend to PM2.5 concentrations. In the vertical direction, weak winds were frequently accompanied by PM2.5 peaks, whereas strong winds were favourable for the diffusion of pollutants. In the later stage, a stable boundary layer with a height of approximately 600–700 m, thermal inversion layer capping the boundary layer, uniformly high-humidity atmosphere (>80 %), and relatively uniform distribution of wind speed across heights contributed to the high PM2.5, which remained within the boundary layer, and the continuous growth of surface PM2.5 concentrations. In the secondary pollution period, the successive regional transport of particles from Beijing and Baoding was the main reason for the two surface PM2.5 peaks in Tianjin. Different regional sources elevate PM2.5 levels, further extending the duration of haze pollution. The results reveal that 3-D meteorological conditions are the key reason for heavy pollution occurrence in the context of pollution reduction.

Mapping and reconstruct suspended sediment dynamics (1986–2021) in the source region of the Yangtze River, Qinghai-Tibet Plateau using Google Earth Engine

Using remote sensing to measure suspended sediment concentration (SSC) in mountainous rivers can compensate for the scarcity of in situ sediment observations, providing valuable direct supplementation to observational records. However, for inland rivers, remote sensing SSC assessments face challenges such as data quality, long-term water body changes, environmental noise, flood events, and the transferability of local calibrations. Here, we introduce and apply remote sensing big data techniques using 12,445 cloud-free Landsat 5, 7, and 8 satellite images to calibrate SSC in the source region of the Yangtze River (SRYR). Utilizing Google Earth Engine, we implemented a series of image preprocessing techniques and water fraction methods to extract precise inland river water masks. Then we used unsupervised K-Means clustering and machine learning algorithms to model the relationship between water optical properties and SSC. By integrating these methodologies, we achieved an average relative calibration error of 0.26 for each optical cluster, and an average relative station deviation of 0.24 based on in situ measurements, minimizing SSC calibration to acceptable levels. Additionally, our results reveal that geomorphic patterns significantly influence sediment yield and transport by regulating sediment sources and sinks, fluvial morphology, and water-sediment connectivity. Over the past two decades, approximately 35.73 % of the sediment relative to the basin outlet discharge in the SRYR has been temporarily stored or confined within sediment sinks. These methods and findings hold significant implications for assessing and projecting fluvial sediment dynamics and the associated ecological and environmental issues in ungauged cold headwater regions.

Brexit consequences on supply chains: towards a risk management framework

ABSTRACT This article investigates Brexit-induced consequences on supply chains and logistics – as well as potential solutions and strategies by carrying out a content analysis through a literature review, the first to our knowledge. Our findings reveal that Brexit-induced consequences for supply chains include increased customs duty rate, labour supply issues, increased costs related to expected delays, tariff and nontariff barriers, added complexity to guarantee food safety, authenticity or security, increased food prices, as well as low-skilled households carrying the major load. Our findings regarding typical supply chain strategies or solutions for abovementioned Brexit-induced consequences include supply chain redesign, relocation of operations and markets, changing sourcing countries or regions, new information and communication technologies solutions such as traceability and blockchains, vertical and horizontal collaboration, resilience, better risk-recovery strategies, as well as the switch to ‘other’ metrics. Another result refers to the fact that we observe only a low level of theoretical grounding in (supply chain) risk management literature among the considered articles.

Migration as a Catalyst of Change: The Impact of Indian Labour Migration to the GCC

The idea of emigration as a method of subsistence has long gained traction in India. Emigration and remittances have been praised as financial sources for the transformation of communities and households. Due to its historical links to international migration and its position as one of India's top labor exporting states, Kerala is an especially intriguing state that has been one of the most significant source regions for Indian temporary workers, primarily to the GCC (Gulf Cooperative Council) countries. Kerala is home to almost 2.1 million migrants, and 36% of the state's net state product comes from their contributions. This study looks at empirical data from the socioeconomic discourses surrounding Gulf migration with respect to the emigrants, their households, and the place from where they migrated in order to comprehend how migrant houses differ from non-migrant households. The study covers empirical research on the reasons behind migration, mobility trends, and the issue of using migration as a strategy to lower state unemployment. The paper goes on to discuss the significance of emigration in the socioeconomic transformations of the state.

Velocity structure of crust and mid-strong earthquake preparation characteristics in the Huoshan region, East China

The Huoshan region, located on the northern margin of the Dabie Orogenic Belt at the junction of the North China Plate and the Yangtze Plate, is one of the most seismically active and concentrated areas in the Dabie Orogenic Belt and adjacent regions. Utilizing the travel time data from 4,427 seismic events observed by 202 stations, we investigated the deep medium structure of the Huoshan region using the double-difference tomography method. The results reveal the medium structure and characteristics of mid-strong earthquake preparation in the region. The crustal medium in the study area exhibits significant lateral heterogeneity. The Dabie Orogenic Belt shows notably high velocity, whereas the North China Plate and the Yangtze Plate display relatively lower velocities. The Tan-Lu Fault Zone exhibits segmentation characteristics; with the crustal medium velocity south of Lujiang being relatively high, north of Jiashan being relatively low, and between Lujiang and Jiashan being intermediate. The epicenters of mid-strong earthquakes are located on the gradient zones of velocity and Poisson’s ratio. The source regions of these earthquakes show significant anomalies of high Poisson’s ratio and low S-wave velocity, which may indicate the presence of fluids. These anomalies possibly reflect the intrusion of deep materials along the fault zone, which could be the driving force for the preparation of mid-strong earthquakes.

Genetic evidence points to distinct paternal settlers of the Faroe Islands and Iceland

IntroductionThe Faroe Islands are a small archipelago located in the North Atlantic likely colonized by a small group of founders sometime between 50 and 300 CE. Post colonization, the Faroese people have been largely isolated from admixture with mainland and other island populations in the region. As such, the initial founder effect and subsequent genetic drift are likely major contributors to the modern genetic diversity found among the Faroese.MethodsIn this study, we assess the utility of Y-chromosomal microsatellites to detect founder effect in the Faroe Islands through the construction of haplotype networks and a novel empirical method, mutational distance from modal haplotype histograms (MDM), for the visualization and evaluation of population bottlenecks.ResultsWe compared samples from the Faroe Islands and Iceland to possible regional source populations and documented a loss of diversity associated with founder events. Additionally, within-haplogroup diversity statistics reveal lower haplotype diversity and richness within both the Faroe Islands and Iceland, consistent with a small founder population colonizing both regions. However, in the within haplogroup networks, the Faroe Islands are found within the larger set of potential source populations while Iceland is consistently found on isolated branches. Moreover, comparisons of within-haplogroup MDM histograms document a clear founder signal in the Faroes and Iceland, but the strength of this signal is haplogroup-dependent which may be indicative of more recent admixture or other demographic processes.DiscussionThe results of the current study and lack of conformity between Icelandic and Faroese haplotypes implies that the two populations were founded by different paternal gene pools and there is no detectable post-founder admixture between the two groups.

Thermophoretic convection in porous atmosphere due to boosting temperature of plume: Climate change effects

A computational analysis of the impacts of thermophoretic convective heat transfer on climate change within a saturated porous atmosphere is predicted. A mathematical model is developed for the proposed problem, employing a Cartesian coordinate system for the source region, a cylindrical coordinate system for the plume region, and a spherical coordinate system for the atmospheric region. The temperature along the central axis of the plume is assumed to be variable, as is the surface temperature of the source region. In the source region, fossil fuel combustion releases thermophoretic particles that travel through the plume into the atmosphere. The climate impact of these particles is calculated via temperature difference across each region. Numerical simulations are performed to gain insights into the physical implications of the model, using the finite difference method to discretise and solve the governing partial differential equations. The effect of various parameters in the flow model, such as mixed convection parameter λT, modified mixed convection parameter λC, Schmidt number Sc, variable viscosity parameter γ, variable thermal conductivity parameter ε, porosity parameter ΩA thermophoretic parameter Nt and indexes of variable surface temperature, are analysed and presented graphically and in tabular form. The primary findings show that an increase in the porosity parameter ΩA results in increase in velocity and temperature profile, while the thermophoretic concentration decreases, potentially moderating climate impact. Further, the thermophoretic rate of heat transfer is maximum at α=1.5rad and minimum at α=πrad in the saturated porous atmosphere. The fundamental innovation of the current work is that three models from three regions are linked via trans-boundaries in terms of temperature differences. The accuracy of the obtained results is ensured by the prescribed boundary conditions and is highlighted graphically as well as in tabular form.

“Ensembled transfer learning approach for error reduction in landslide susceptibility mapping of the data scare region”

Landslide susceptibility map (LSM) plays an important role in providing the knowledge of slopes prone to future landslides. However, the applicability of LSM is often hindered due to high cost of data collection especially in mountainous region such as Himalayas. Therefore, this study proposes transfer learning approach (TL) to improve the performance of LSM by transferring the information from the data rich region (source) to data scare region (target). Two machine learning based model are trained in source area which is then transferred for prediction in target area and a source trained model combined with the knowledge of target is used for the prediction in the target area. The applicability of the proposed approach is tested considering Mandi district as source area and Kullu and Rudraprayag districts as target areas. Independent variables which included 11 landslide conducive factors from the source and target area, the independence was critically analysed using multi-collinearity test, while the geomorphic similarity was assessed using KL divergence method. Efficient machine learning method such as random forest (RF) and multi-layer perceptron (MLP) was used to train the models in both areas, statistical measure such as AUC-ROC, precision, recall, F-score, and accuracy were used to evaluate the performance of the LSMs. The results demonstrated the proposed approach for target area 1, the AUC value increased from 0.908 (Target trained on itself), to 0.942 (Target-Transfer Learned (TL)) and 0.959 (Target Combined) for RF and 0.896, 0.907 and 0.946 for MLP. Additionally, an increase in the precision was observed in RF while all other statistical measures increased to 0.023 for precision, 0.022 for recall, 0.023 for F-score and 0.066 for accuracy in the case of MLP. While on the other hand, in the case of target area 2, the AUC value for RF, ranged from 0.95 (Target area trained on itself), 0.80 (target TL) and 0.98 (target combined) and for MLP the AUC ranged from 0.82 for the source trained model while 0.84 for LSM obtained when both target and source data was used. Thus, the results revealed that proposed TL approach can be effective in improving the performance of LSM in data scare region in Himalayan region, thereby providing a promising approach in overcoming the issue of data limitation.

Modeling the impacts of open biomass burning on regional O3 and PM2.5 in Southeast Asia considering light absorption and photochemical bleaching of Brown carbon

Open biomass burning in Southeast Asia has significant adverse impacts on air quality in the region and in downwind areas. These biomass burning events emit large amounts of light absorbing brown carbon (BrC). Once in the atmosphere, the light absorbing capacity of BrC is reduced by various oxidation processes. However, few modeling studies have been conducted to explicitly examine light absorption and bleaching on the prediction of ozone (O3) and fine particulate matter (PM2.5). In this study, a modified Community Multiscale Air Quality (CMAQ) model that explicitly tracks the concentrations of light absorbing and non-light absorbing organic aerosol components from different emission sources and the bleaching of BrC due to photooxidation and OH oxidation is applied to widespread open biomass burning events in March 2018 in Southeast Asia. Open biomass burning accounts for as much as 20–40 ppb (30–50%) of the maximum daily average 8-h ozone (MDA8 O3) and 40–120 μg m−3 (60–90%) of the daily average PM2.5 in the emission source regions. Compared to a simulation without BrC light absorption, the predicted MDA8 O3 and PM2.5 are as much as 16 ppb and 16 μg m−3 lower, respectively, than a simulation with light absorption. This confirms that neglecting the UV light absorption of BrC can lead to significant overpredictions of O3 and PM2.5 during the open biomass burning periods, which may lead to an overestimation of the adverse impacts of biomass burning on public health in Southeast Asia. The addition of BrC bleaching results in a 0.5–1% increase in MDA8 O3 and 1–5% increase in PM2.5 compared to the case without BrC bleaching. The results of this study indicate that light absorption by BrC needs to be considered in chemical transport modeling of large open biomass burning events. The BrC bleaching process is relatively slow and neglecting this process does not significantly change the predictions of MDA8 O3 and PM2.5 during open biomass burning.