Latitudinal Direction Research Articles

The Spatiotemporal Characteristics and Driving Factors of Soil Degradation in the Black Soil Region of Northeast China

The Northeastern Black Soil Region in China is recognized as one of the three major black soil regions globally and is often regarded as a cornerstone of national food security. However, prolonged agricultural practices have led to increasingly severe soil degradation, and the mechanisms and driving factors behind the degradation of soil quality remain unclear. Therefore, this study examines the historical and current characteristics of soil quality, focusing on major influencing factors, such as the 70-year history of reclamation and climate change. By accessing different databases, reviewing the relevant literature, and performing Pearson correlation and redundancy analyses (RDA), this study investigated the variation patterns of significant soil quality indicators and their driving factors in the 0–20 cm soil layer along the latitudinal direction (Nenjiang, Beian, Hailun, and Harbin) in the typical black soil region of Northeast China. The main conclusions are as follows: the soil organic matter (SOM) content experienced a rapid decline in the 30 years preceding cultivation (1950~1980), with the greatest decline rate in the Beian area (about 1.10 g/kg per year). The SOM in the Beian, Hailun, and Harbin areas decreased from north to south, changing at rates of 9.40–21.67 g/kg/degree and 0.15–0.34 g/kg/m with latitude and elevation, respectively. Elevation impacts the annual rate of change in soil quality indicators through its influence on the annual mean maximum temperature (AMXT) and annual atmospheric pressure (AP). AMXT and AP exhibit a linear relationship with elevation, based on which regression models were established. The key factors influencing soil quality indicators in the black soil region include cultivation years (Y), annual mean maximum and minimum temperatures (AMXT and AMNT), annual relative humidity (ARH), and AP. An increase in chemical fertilizer application is among the critical factors affecting soil pH. Additionally, the extensive use of agricultural machinery can reduce soil porosity and cause water and salt accumulation, ultimately leading to a decline in soil pH. This study offers theoretical support for mitigating soil degradation in Northeast China’s black soil region, thereby contributing to national food security and promoting sustainable development.

Exploring Spatial and Temporal Patterns in the Debrecen Solar Faculae Database: Part II

In this study, utilizing data from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager–Debrecen Faculae Data Catalogue, we investigated solar facula distribution over timescales much larger than the individual lifetimes of faculae. We aimed to better comprehend the behavior of the Sun’s global magnetic field, where faculae play a role as markers. (1) Along the latitudinal direction, we observed the following in the appearance of faculae. (i) Short-term periods with the Carrington rotation (27.3 days) and some of its harmonics (approximately 13.5 and 9 day periods) are identified. In the northern hemisphere, there is also a faint 7 day period. (ii) We also identified longer periods. These longer periods, approximately between 150–300 and 300–500 days, exhibit a diminishing trend from the solar equator to the poles in both hemispheres. (2) Analyzing the distribution and evolution of the longitudinal coordinates of the faculae, we identified two pairs of active longitudes that are separated by 180° from each other.

Lake responses and mechanisms to El Niño on the Tibetan Plateau using deep learning-based semantic segmentation

Numerous lakes across the Tibetan Plateau (TP) serve as crucial indicators of climate change and are significantly influenced by El Niño events. Previous studies of lake response to El Niño events have focused on a limited number of lakes. Despite advances in remote sensing technology, there have been few comprehensive and large-scale studies using deep learning, and there are still gaps in understanding the response mechanisms on a larger scale. This study leverages advanced deep-learning techniques to map lake responses, offering unprecedented insights into the large-scale hydrological impacts of El Niño. Our results show that lakes shrink significantly during El Niño events on the TP. Lakes located in the central and southern parts of the TP and small lakes with areas ranging from 1 to 50 km2 (over 60 % of them) exhibited strong responses. The range of lake response to El Niño events varies with their intensity, with stronger El Niño events causing an expansion of the response range along the latitudinal direction. We propose four possible mechanisms for lake response patterns to El Niño from the perspective of lake water sources. Strong shrinkage is primarily caused by decreased precipitation and increased evaporation, with a possible contribution from reduced meltwater. Strong expansion is due to increased precipitation, more glacier and frozen soil meltwater, and reduced evaporation. For slight shrinkage and expansion patterns, the balance of meltwater may offset or even counteract the El Niño signal. The study’s results could improve predictions of extreme weather events like droughts and floods in the Third Pole region, enhance water resource management and responsiveness, and offer valuable insights for ecological monitoring and early warning systems development.

The Structure of Field‐Aligned Current Systems as Inferred From the Multiscale Minimum Variance Analysis

AbstractAuroral field‐aligned currents (FACs) have an intrinsic complexity caused by the superposition of contributions from a broad spectrum of scales and diversity of locations. The complex FAC systems are investigated by using the multiscale minimum variance analysis. This technique provides a scale based decomposition of the FAC systems by identifying the constituting FAC elements as well as their structure. At the basis, the analysis exploits the scale dependence of the eigenvalues of the magnetic field variance matrix. The scale decomposition along the transversal (latitudinal) direction results from the scale derivative of the maximum eigenvalue. The complementary information from the scale derivative of the minimum eigenvalue helps to infer the full structure of each FAC element by providing estimates of the FAC length (longitudinal) scale. The scale derivative of minimum and maximum eigenvalues are used to identify FAC signatures associated to different types of aurora (e.g., highly extended, finite arcs, gradient regions) as well as to characterize the influence of the crossing location with respect to the FAC structures (e.g., near edge crossings). The multiscale analysis is applied to simulated FACs and to spacecraft observations made by the Swarm mission. The use with real world data illustrates the power of this analysis, whose full benefits for magnetosphere‐ionosphere coupling investigations are yet to be explored.

Two-Dimensional Legendre Polynomial Method for Internal Tide Signal Extraction

This study employs the two-dimensional Legendre polynomial fitting (2-D LPF) method to fit M2 tidal harmonic constants from satellite altimetry data within the region of 53°E–131°E, 34°S–6°N, extracting internal tide signals acting on the sea surface. The M2 tidal harmonic constants are derived from the sea surface height (SSH) data of the TOPEX/Poseidon (T/P), Jason-1, Jason-2, and Jason-3 satellites via t-tide analysis. We validate the 2-D LPF method against the 300 km moving average (300 km smooth) method and the one-dimensional Legendre polynomial fitting (1-D LPF) method. Through cross-validation across 42 orbits, the optimal polynomial orders are determined to be seven for 1-D LPF, and eight and seven for the longitudinal and latitudinal directions in 2-D LPF, respectively. The 2-D LPF method demonstrated superior spatial continuity and smoothness of internal tide signals. Further single-orbit correlation analysis confirmed generally higher correlation with topographic and density perturbations (correlation coefficients: 0.502, 0.620, 0.245; 0.420, 0.273, −0.101), underscoring its accuracy. Overall, the 2-D LPF method can use all regional data points, overcoming the limitations of single-orbit approaches and proving its effectiveness in extracting internal tide signals acting on the sea surface.

A higher dimensional model of geophysical fluid with the complete Coriolis force and vortex structure

Here, we present a higher dimensional model from the vorticity equation, which describes the dynamic characteristics of large scale Rossby waves by utilizing the Gardner-Morikawa coordinate transformation and the perturbation method. To reveal the influence of physical parameters on the higher dimensional model, we first give the dispersion relation of the model and the N-soliton solutions by Hirota method. Subsequently, the lump solutions are derived by using the long wave limit method. It demonstrates that the horizontal component of the Coriolis force acts as a forcing force on the nonlinear Rossby waves, and affects the amplitude of the meridional structure. Moreover, under the background of secondary zonal basic flow, for different lump solutions, the flow field will appear dipole blocking or double vortex structure. It is also indicated that the horizontal Coriolis force only causes the vortex to move in the latitudinal direction.

Short-term forecasting method for prevailing orientation of leads in the Laptev Sea ice cover during winter-spring season

Sea ice leads are potential routes of easier navigation in the Arctic seas during winter-spring season. Forecasts of the prevailing orientation of ice leads are required for the early selection of the optimal route of a ship in ice. An automated method for short-term forecasting of the prevailing orientation of leads in the Laptev Sea is developed in AARI based on the analog method. Data sources for making a forecast include predictive fields of atmospheric pressure up to 3 days in advance and historical data on surface atmospheric pressure, ice drift and sea ice leads. The data on ice leads are obtained by interpreting SuomiNPP satellite images in a visible and infrared range at 375 m spatial resolution for the cold seasons 2016–2022. The ice drift data are freely available OSI SAF data. In order to make a forecast of the prevailing orientation of leads by a predictive atmospheric pressure field, it is necessary to select from an electronic data archive a historical field of atmospheric pressure that is the most similar to the predictive field. The lead characteristics on the selected date are taken as the predictive ones. Automated selection of an analog consists in searching for an atmospheric pressure field from the electronic data archive which has minimal metrics for the forecast date together with 2 previous days. The metric is calculated as the sum of the squared differences between the change in atmospheric pressure per 1 km in the latitudinal and meridional directions between the predictive atmospheric pressure field and the potential analog field. Actual lead data for a date of the selected analog may not be available due to thick clouds. In this case, the direction of the minor axis of the strain ellipse calculated from ice drift data is taken as the prevailing orientation of leads. The success ratio of diagnostic forecasts by the method developed is 72 %. Comparison of the success ratio of the diagnostic forecasts with the results of inertial and climatic forecasts demonstrates a high effectiveness of the method for cases of abrupt change in the direction of air flows over the Laptev Sea within the first 1–2 days.

УГОЛЬНЫЕ БАССЕЙНЫ СССР В СИСТЕМЕ МЕЖРЕГИОНАЛЬНЫХ ГРУЗОПЕРЕВОЗОК В 1940–1953 гг.

The article introduces into scientific circulation the materials of the USSR transport statistics on the dynamics of coal cargoes transportation by rail in the late 1940s — early 1950s. On the basis of the identified sources, it establishes the importance and place in the system of interregional freight traffic for the five largest coal basins of the Soviet Union: Donetsk, Near Moscow, Karaganda, Kuznetsk and Pechora. The evolution of transportation is considered in the context of political and economic factors of both external and internal nature. In particular, the case of indirect economic damage caused to the eastern regions of the USSR by the Great Patriotic War is shown on the example of transport links between the Urals and Siberia. In the context of interregional freight transportation, an episode of territorial contradictions of the CPSU Sverdlovsk and Leningrad regional committees regarding the development of coal deposits in the Polar Urals is considered. It is noted that the economic effect of the historical inertia of these events can be traced up to the present time, and is expressed both in the imbalance of the latitudinal and meridional directions of transport routes, and the uneven congestion of the railway network of modern Russia. The published material demonstrates the prospects of using the USSR transport statistics for the implementation of comprehensive historical and economic zoning of the Soviet Union, subject to similar studies in relation to other chronological periods and other categories of cargo in the future. The article is supplemented with cartographic materials illustrating the considered changes in the transportation of coal cargoes across the territory of the USSR graphically.

The Lotus angustissumus Group (Fabaceae): Can Phylogenetic Patterns Be Accommodated by a Taxonomic Concept?

The Lotus angustissimus group represents an example of obvious contradictions between the molecular and morphological data. This group includes from six to eight mostly annual species of Lotus section Lotus, with the center of species diversity in the Mediterranean. We performed a phylogenetic analysis of the genus Lotus with an expanded representation of all known species of the L. angustissimus group using both nuclear (nrITS) and a set of plastid DNA markers and compared the results with traditional taxonomy of this group. Our results demonstrated a non-monophyletic nature of the study group. In addition, the nrITS and plastid dataset tree topologies were incongruent with each other in both Bayesian and ML analyses. We revealed very complex phylogenetic relationships among the species of the group. Important results obtained in this study are: (1) genetic and geographical differentiation in the latitudinal direction (between L. angustissimus and L. praetermissus) and in the longitudinal direction among closely related accessions identified as L. castellanus, L. lourdes-santiagoi and L. palustris; (2) close genetic links between the Anatolian endemic L. macrotrichus and L. praetermissus from Eastern Europe and Central Asia; and (3) the hybrid nature of L. subbiflorus with L. parviflorus as its presumed male parent species. These results are discussed in the context of morphology, biogeography and taxonomy.

ANOMALOUS MAGNETIC REGIONS ON THE SUN

We studied the anomalous magnetic regions observed near the minima of solar cycles 24 and 25. The peculiarity of these areas was the deviation of their configuration from Hale's law of magnetic polarity and Joy's law about the inclination of the axes of bipolar groups to the latitudinal direction. Therefore, they belong to the class of so-called anti-Hale active regions. We paid special attention to the flare activity of anti-Hale regions, as this is important for forecasting space weather and magnetic storms in the Earth's atmosphere. The detected anomalies of the surface magnetism of the active regions studied by us may indicate the influence of the mechanisms of the deep small-scale dynamo on their evolution. In this regard we analyzed the possible mechanisms of the formation of anti-Hale magnetic regions. In particular, such mechanisms can be the mechanisms of a small-scale magnetic dynamo. In connection with this an urgent problem today is the search for observed evidence of the existence of the theoretically proposed by Brandenburg A. et al. (2012) of a new physical entity – a small-scale magnetic field hidden in the solar depths, excited by two qualitatively different mechanisms of a small-scale dynamo (SSD). The first mechanism is the SSD of macroscopic MHD (SSD1), while the second is the diffusion SSD of classical MHD (SSD2). However, the small contributions of these sources are very difficult to distinguish observationally. To solve this complication, Sokoloff, Khlystova and Abramenko (2015) proposed a test for separating the contributions of two sources based on a statistical probabilistic model. Such an important feature of the differences between of the two SSD is the behavior of the percentage of anti-Hail groups of sunspots (in relation to the total number of spots) in the minima of solar cycles. According to statistical studies of long series of observations Sokoloff, Khlystova and Abramenko (2015) found that the percentage of anti-Haile groups of spots increases during minima of the solar cycles, suggesting in favor of SSD2. We believe that the detected magnetic anomalies of the studied regions may be caused by the influence of a SSD2 in the depths of the convective zone of the Sun, since this source gives the most noticeable contribution to the surface magnetism near cycle minima.

The Image of Precision: The Case of the Longitudinal Amazon

A set of maps from the middle of the sixteenth century featuring the New World, such as those by Jean Rotz (1542), Giacomo Gastaldi (1546), and Jean Bellère (1554), presented a peculiarity regarding the delineation of the Amazon River. Instead of having a latitudinal direction, as dictated by modern cartographic conventions, the Amazon had a longitudinal orientation. This is often assumed to be an inaccurate cartographic representation of the river. However, these maps were rather precise insofar as, according to contemporaneous accounts of South America provided by scholars such as Peter Martyr, Gonzalo Fernández de Oviedo, and Francisco López de Gómara, the Amazon had a potential longitudinal course. In this sense, the author aims to explain the accuracy of some of the early modern cartographies of Amazonia by placing these maps in dialogue with geographic and hydrographic descriptions of the river that circulated at that time. Consequently, this work re-evaluates the notion of precision when applied to the study of the early European mapping of the Amazon River.

Territory heterogeneity study on the «number of species – area» curve to research its floristic structure (the Inza physical-geographical area)

The Inza high-plain forested area of the upper plateau is located in the Volga region. It stretches from south to north along the western border of Ulyanovsk Region. The floristic heterogeneity of the area was analyzed at the level of species composition according to the «number of species – area» curve. The zones of the most massive influx of species can be considered as a different floristic region with a different species composition. Taking into account the geographical configuration of the Inza area, the study was carried out in the latitudinal direction: from south to north and from north to south. In addition to tracking the increase in the total species composition, the change in the position of the leading families with an increase in the number of species across the territory is considered. The initial data on the flora of the area are lists of species compiled for individual geographical points. It has been established that the increase in the species composition occurs unevenly in both directions: in addition to the first stage, two subsequent ones are noticeable. The heterogeneity of the flora of the Inza area is confirmed by changes in the arrangement of the leading families of the head part of the total flora spectrum with the accumulation of species composition. The middle part of the area has a pronounced Fabaceae type. In the northern and southern parts, the proportions of the families Fabaceae and Rosaceae are close with a slight predominance of Rosaceae. This is especially noticeable when excluded from the general list of adventitious species. In the composition of the native flora, the Brassicaceae family reduces its share, while Cyperaceae, on the contrary, rises up the spectrum. The role of sedges is somewhat greater in the northern part of the area. In the Inza area, three local floras are identified and considered, which are characterized by the Fabaceae type. However, the gap between Fabaceae and Rosaceae in abundance differs greatly. It is the largest in the local flora in the tract Akulovskaya steppe. In its composition, the proportion of the genus Astragalus is noticeably higher, which increases the contribution of legumes to the flora. The spectrum of the complete composition of the flora of the Inza area is Rosaceae type. In this regard, it is also possible to assume that the three local floras considered do not exhaust the entire diversity of the studied area.

A theoretical approach for thermomechanical shock analysis of doubly curved panel with respect to geometrical and physical parameters using machine-leaning-based algorithm

In this work, for the first time, bending information of the doubly curved panel under thermo-mechanical shock loading (MSL) with respect to geometrical and physical parameters via both numerically, and machine-leaning-based algorithms is presented. The graphene nanoplatelets composites are used to reinforce the current composite curved panel along with latitudinal direction. It should be note that the current curved panel is reinforced in latitudinal direction with GPLs due to thermo-MSL in the latitudinal direction. The material properties of the current doubly curved structure are obtained with the aid of role of mixture and Halpin–Tsai micromechanics model. As well as this, GPL distribution’s thermal conductivity for each pattern of GPL is considered for high accuracy of the current work’s model. Three-dimension (3D) elasticity theory, linear thermo-elasticity principle, constitutive heat conduction equation, and relaxation time equation are used to present the mathematical modeling of the current work. After obtaining the governing equations, the equations are solved via numerical solution using Chebyshev–Gauss–Lobatto function, and spatial and Laplace latitudinal methods. Deep neural networks (DNNs) as a machine learning method are used to train and test the obtained results from mathematical modeling. After predicting the results, the results are compared with the outcomes of mathematical modeling and show that with the low computational cost of DNNs algorithm, the results can be predicted instead of other high computational cost methods. Finally, some suggestions for improving the thermo-mechanical behavior of the current doubly curved panel under external shock loading.

Projected changes in extreme snowfall events over the Tibetan Plateau based on a set of RCM simulations

Extreme snowfall events over the Tibetan Plateau (TP) cause considerable damage to local society and natural ecosystems. In this study, the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model, RegCM4. The model is driven by five CMIP5 global climate models at a grid spacing of 25 km, under the RCP4.5 and RCP8.5 pathways. Four modified ETCCDI extreme indices—namely, SNOWTOT, S1mm, S10mm, and Sx5day—are employed to characterize the extreme snowfall events. RegCM4 generally reproduces the spatial distribution of the indices over the region, although with a tendency of overestimation. For the projected changes, a general decrease in SNOWTOT is found over most of the TP, with greater magnitude and better cross-simulation agreement over the eastern part. All the simulations project an overall decrease in S1mm, ranging from a 25% decrease in the west and to a 50% decrease in the east of the TP. Both S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the TP. Notably, S10mm shows a marked increase (more than double) with high cross-simulation agreement over the central TP. Significant increases in all four indices are found over the Tarim and Qaidam basins, and northwestern China north of the TP. The projected changes show topographic dependence over the TP in the latitudinal direction, and tend to decrease/increase in low-/high-altitude areas.摘要基于RegCM4区域气候模式的气候变化预估试验数据, 开展了青藏高原及其周边地区极端降雪事件的未来变化研究. 结果表明, 总降雪量在高原大部分地区呈减少趋势, 降雪日数在高原也将明显减少, 尤其是在东部. 大雪日数和五日最大降雪量在高原东部将减少, 而在中部和西部明显增加. 在高原周边的塔里木和柴达木盆地及中国西北地区, 极端降雪事件同样增加显著. 极端降雪事件在高原上呈现出东西方向上的地形依赖性, 在低/高海拔地区呈减少/增加趋势.

Heterogeneous responses of wetland vegetation to climate change in the Amur River basin characterized by normalized difference vegetation index from 1982 to 2020.

Climate change affects wetland vegetation dramatically in mid- and high- latitudes, especially in the Amur River basin (ARB), straddling three countries and distributing abundance wetlands. In this study, spatiotemporal changes in average normalized difference vegetation index (NDVI) of wetland during the annual growing season were examined in the ARB from 1982 to 2020, and the responses of wetland vegetation to climatic change (temperature and precipitation) in different countries, geographic gradients, and time periods were analyzed by correlation analysis. The NDVI of wetland in the ARB increased significantly (p < 0.01) at the rate of 0.023 per decade from 1982 to 2020, and the NDVI on the Russian side (0.03 per decade) increased faster than that on the Chinese side (0.02 per decade). The NDVI of wetland was significantly positively correlated with daily mean temperature (p < 0.05, r = 0.701) and negatively correlated with precipitation, although the correlation was not significant (p > 0.05, r = -0.12). However, the asymmetric effects of diurnal warming on wetland vegetation were weak in the ARB. Correlations between the NDVI of wetland and climatic factors were zonal in latitudinal and longitudinal directions, and 49°N and 130°E were the points for a shift between increasing and decreasing correlation coefficients, closely related to the climatic zone. Under climate warming scenarios, the NDVI of wetland is predicted to continue to increase until 2080. The findings of this study are expected to deepen the understanding on response of wetland ecosystem to global change and promote regional wetland ecological protection.

Preliminary Study on the Diversity of Soil Oribatid Mite (Acari: Oribatida) Community Reveals Both Longitudinal and Latitudinal Patterns in Paddy Fields along the Middle and Lower Reaches of Yangtze River, China

Soil biodiversity plays an important role in maintaining soil fertility and agricultural health. Exploring the patterns of soil fauna diversity across geographical gradients is a fundamental and crucial scientific topic for understanding the mechanisms of soil biodiversity in farmlands. However, the spatial pattern of soil fauna diversity across longitudinal gradients has received far less attention. In order to explore the longitudinal pattern (west to east) of the composition and diversity of the soil oribatid mite community in paddy fields along the middle and lower reaches of the Yangtze River (MLYR), an investigation was carried out in July 2021 at nine sites spanning a longitudinal range of 8.86° (906 km) in southeastern China. In total, 19 taxa and 2392 individuals were observed with a density of 1535.47/m2. Protoribates and Ceratozetes were the most dominant and widely distributed genera along MLYR. The distribution patterns of the richness, abundance, and diversity index were obvious across the longitudinal and latitudinal gradients. The longitudinal pattern showed a quadratic distribution of first increasing and then decreasing, while the latitudinal pattern showed an increasing pattern with the increase in latitude (unimodal pattern). The influence of latitude on the abundance of the soil oribatid mite community was greater than that of longitude, and the influence of longitude on richness and the corresponding diversity index was greater. The dominance index did not show a distribution pattern in the longitudinal and latitudinal directions, while the evenness index showed only the distribution pattern in the longitudinal direction, and the latitudinal pattern was not significant. The results of this study suggest that the diversity of the soil oribatid mite community along MLYR displays both longitudinal and latitudinal patterns in paddy fields. Moreover, we highlighted the importance of integrating longitudinal and latitudinal patterns into spatial patterns of the soil fauna community in farmlands at a regional scale.

Catch dynamics of freshwater bram Abramis brama in the Ob river basin as a reflection of the success of its acclimatization

The native range of the freshwater bream Abramis brama includes the basins of the North, Baltic, White, Azov, Black, Caspian and Aral seas. This species is not a popular object of aquaculture, but it is cultivated in some countries of Eastern Europe and Central Asia. In the water bodies of Italy, Spain, Portugal, England and China, it is a naturalized alien species that does not have a large number. At first freshwater bream was introduced into the Ob basin in 1862, in the reservoirs of the eastern slope Urals. By the end of the 19th century, bream became common in this region, but spread slowly downstream: in the Lower Irtysh it was noted only in the mid-1920s, and entered the commercial statistics in 1936. It became known in the Middle Irtysh in the 1930s, but it became an object of fishing only in 1963. In the lakes of the Ob-Irtysh interfluve, at first bream was introduced in 1928. In the largest of them, it became naturalized. In the Ubinskoye lake the bream formed a stable self-reproducing population, which served as a source of juvenile bream for resettlement in water bodies of Siberia and Kazakhstan in the middle of the twentieth century. Currently, the bream in the Ubinskoye lake does not inhabit due to the shall owing of the lake. Bream was introduced into the Novosibirsk reservoir in 1957–1960. It quickly became numerous and began to spread up and down the river Ob. It has been known in the Upper Ob in the Altai Region since the early 1960s, and in the Middle Ob in the Tomsk Region since the end of the same decade. Currently, the catch of bream in the Ob basin are maximum in the Bukhtarma reservoir, relatively large in the Novosibirsk reservoir and in the water bodies of the Khanty- Mansiysk Autonomous Region. At the same time, the share of this species in the total volume of fish catch in large reservoirs of the Ob basin is about 80% of the fishing, in the Middle Ob and Middle Irtysh — about 20%, and in the north of Western Siberia — less than 0.5%. The decrease in the share of bream in the fishery from south to north reflects not only a decrease in the abundance of this species in the latitudinal direction, but also an increase in the stocks of native fish species.

Mechanical behavior of three‐harness twill woven composite plates under tension loading

AbstractThree‐harness twill woven composite (THT‐WC) is an advanced carbon fiber reinforced composite that compromises the mechanical behaviors in both longitudinal and latitudinal directions. To explore the further practical application, the structural characteristics and static mechanical behavior of the material were investigated in this article. X‐ray computerized tomography was adopted to obtain the mesostructure details and to capture the key characteristics. With the help of mesoscale information, the 2D and 3D geometric models were established in the form of representative volume elements (RVEs). Combined with voxel mesh generation technology, a finite element model was proposed based on a 3D geometric model where macroscopic mechanical properties of materials along different yarn directions were gained. To verify the simulated geometry and predicted mechanical properties, mesoscale geometric comparison and specimen tensile tests were performed. The results show that the geometric model established in this article can reasonably reflect the periodicity fluctuation of binder warp yarns and the randomness fluctuation of weft yarns. Compared with the experimental results, the relative error of stiffness in the weft direction of the RVE is 4.25%, and that in the warp direction is 5.33%.Highlights The mechanical properties of THT‐WC were investigated experimentally. Meso‐scale reconstruction of THT‐WC was presented. A model to predict the mechanical properties of THT‐WC is established.

Efficient data-driven solution to thermoelastic mixed shock behavior of composite plates by considering the effect of agglomeration

This study presents an innovative path through the method of deep learning to inspect the mixed shock response of a latitudinally-graded agglomerated carbon-nanotubes enriched composite (LaG-ACNTEC) rectangular plate. The case study of this research is simultaneously exposed to thermomechanical and heat flux wave shocks at its edge expanded through the latitudinal direction. Equations of motion for this model are established on the bases of the linear thermoelasticity theory. Differential quadrature technique (DQT) is utilized for solving spatial dependency of these equations, while the Laplace transform and its inverse are utilized to solve temporal dependency of the system’s equations. Authors of this study reveal a novel path for increasing the computation efficiency of the approach by mounting a deep-learning-based method on the results determined by DQT and Laplace transform at designated points due to dynamic nature of the problem. Verification of the applied solution is performed based on a comparative study with the results of the published surveys. This study gives precious insights to designers for inspecting the mixed shock response of the composite structures by considering the effect of agglomeration and utilizing data-driven methods serving as accelerator of conventional solvers.

Effects of assimilation of YOPP‐SH additional radiosonde observations on analyses and forecasts over Antarctica in austral summer

AbstractRadiosonde observations over Antarctica and the surrounding oceans were enhanced during the Year of Polar Prediction in the Southern Hemisphere (YOPP‐SH) summer Special Observing Period (SOP). Observing System Experiments (OSEs) were conducted in a continuous cycling framework using the Weather Research and Forecasting (WRF) Model and its data assimilation system. Routinely available observations were assimilated in the CTL (control) experiment, and special radiosonde observations from the YOPP‐SH SOP were additionally assimilated in the YOPP experiment. The results were compared to investigate the effects of additional radiosonde observations on analyses and forecasts over and around Antarctica. Verifications against ERA5 re‐analysis, radiosonde observations, and Automatic Weather Station (AWS) observations show overall positive effects of additional radiosonde observations. These positive effects are most noticeable in temperature at lower levels at earlier forecast lead times; afterward, wind forecast improvements at upper levels are the most noticeable. Although routine and special radiosonde observations are concentrated over the eastern and coastal regions of Antarctica (compared to the western and inland regions), the effects of the extra data spread in longitudinal and latitudinal directions; therefore, the effects on the forecasts are not limited to only the areas near the radiosonde observations. A case study reveals how cyclone forecasts are improved through the assimilation of the additional YOPP‐SH SOP radiosonde observations. This study provides insights into future observation strategies in Antarctica, such as horizontal/vertical observation locations, observation variables, and so forth to maximize effects of new observations on forecasts over Antarctica.