Westward Migration Research Articles

Journey to the West: migration patterns of the riparian montane genus Myricaria

Journey to the West: migration patterns of the riparian montane genus Myricaria

The North China record-breaking rainfall in July 2021: The atmospheric influential factors and precursory signal

Abstract In July 2021, the southeastern part of North China (SENC) suffered a record-breaking extreme rainfall event that caused devastating flooding and enormous losses. In this study, the major atmospheric influential factors and the precursory signal of heavy rainfall in 2021 are investigated using the correlation, regression, power spectrum, and filtering methods, the quasi-geostrophic velocity equation, observational data and numerical simulation of a linear baroclinic model (LBM). The results show that the extremity of a quasi-barotropic high anomaly over Northeast Asia (NEA) contributes to the deep anomalous upward motion within SENC by inducing positive vorticity and temperature advections. On the other hand, the anomalous southeasterly flow at the southwestern flank of the NEA high anomaly transports sufficient moisture to SENC in the lower troposphere. The local deep upward motion combined with the lower-tropospheric moisture convergence directly leads to the occurrence of this extreme rainfall event. Further analysis shows that the intensification of the NEA high in July 2021 is closely tied to the westward migration of atmospheric disturbance originating from the vicinity of Northeast Pacific-North America, which could be supported by numerical simulation in LBM. The variation of the geopotential height anomaly over Northeast Pacific-North America precedes that of the NEA high by two weeks, which is likely to provide a potential source of predictability for the extreme rainfall in SENC.

Phylogenomics and phylogeographic model testing using convolutional neural networks reveal a history of recent admixture in the Canarian Kleinia neriifolia.

Multiple-island endemics (MIE) are considered ideal natural subjects to study patterns of island colonization that involve recent population-level genetic processes. Kleinia neriifolia is a Canarian MIE widespread across the archipelago, which exhibits a close phylogenetic relationship with species in northwest Africa and at the other side of the Sahara Desert. Here, we used target sequencing with plastid skimming (Hyb-Seq), a dense population-level sampling of K. neriifolia, and representatives of its African-southern Arabian relatives to infer phylogenetic relationships and divergence times at the species and population levels. Using population genetic techniques and machine learning (convolutional neural networks [CNNs]), we reconstructed phylogeographic relationships and patterns of genetic admixture based on a multilocus SNP nuclear dataset. Phylogenomic analysis based on the nuclear dataset identifies the northwestern African Kleinia anteuphorbium as the sister species of K. neriifolia, with divergence starting in the early Pliocene. Divergence from its sister clade, comprising species from the Horn of Africa and southern Arabia, is dated to the arid Messinian period, lending support to the climatic vicariance origin of the Rand Flora. Phylogeographic model testing with CNNs supports an initial colonization of the central island of Tenerife followed by eastward and westward migration across the archipelago, which resulted in the observed east/west phylogeographic split. Subsequent population extinctions linked to aridification events, and recolonization from Tenerife, are proposed to explain the patterns of genetic admixture in the eastern Canary Islands. We demonstrate that CNNs based on SNPs can be used to discriminate among complex scenarios of island migration and colonization.

“In the Footsteps of Our Ancestors” Polish Traditions of Westward Migration Meets Modern Epigenetics of Trauma

For several years, there have been ongoing considerations regarding the interdisciplinary connections between the natural sciences and the humanities. The same holds true for the question as to whether trauma can be inherited biologically as well as culturally. Today, this topic is increasingly steering the scientific debate in the direction of epigenetic research, which currently combines molecular biology and social psychology with their respective hallmarks. Can culture-related traumas be inherited and, if this was possible, can transgenerational consequences of trauma be passed on to subsequent generations? The focus remains on educational and socialization-related conduct as well on biologically inherited processes of how individual deals with their own trauma. Can migration be inherited by subsequent generations via transgenerational transmission of trauma? In order to answer this question, both consequences and causes of the long-running migration from Poland to Western European countries need to be considered. This article thus seeks to establish a connection between now and then, while also focusing on tragic passages in Poland’s history that were characterized by suffering, statelessness, and occupation (until 1989). Consequently, multi-layered and repeated habitus breakages as well as specific Polish “worldviews” may have emerged, which tend to favour migration. The causal links between the transgenerational transmission of such traumas and their causal connections to ongoing migration from Poland to countries such as Germany are addressed by using modern epigenetics.

Tectonic and eustatic controls on the palaeobiogeographic distribution of Eocene bivalves

ABSTRACT The Eocene epoch experienced important global events—a warming and transgression at the beginning, and a cooling and regression at the end. Crucial tectonic rearrangements were also taking place, such as the northward movement of the Indian plate and closure of the Tethys Sea. Here, the global palaeobiogeography of all Eocene bivalve genera is studied to see the effects of these tectonic and eustatic changes. We have established formal palaeobiogeographic provinces and explored their evolving relationships based on statistical analyses of global distribution data of all bivalve genera for each stage of the Eocene. The late Paleocene (Thanetian) and early Oligocene (Rupelian) stages have also been included to understand potential effects of climate and sea-level changes. Bivalve diversity increased at the beginning and fell at the end of the Eocene, apparently in response to opposite climatic and eustatic changes at these boundaries. The palaeobiogeographic provinces also expanded and shrank, respectively. The tropical and subtropical basins of northwestern Europe and eastern and western America accommodated maximum bivalve diversity and yielded temporally stable provinces. These provinces shared many bivalve genera. However, similarity of the western American fauna with that of eastern America dwindled with time as the Western Interior Seaway disappeared. The distribution sequence of shared diachronous genera between the provinces revealed that (1) the Western American Province later developed affinity to the Japan and Eastern Russian Province facilitated by the Alaska and Oyashio currents, (2) the Northern Equatorial Current and North Atlantic Gyre were primarily responsible for the similarity between the Tethyan and Atlantic provinces, and (3) the Tethys seaway was active until the middle Eocene, which allowed westward migration of the western Indian fauna leading to its similarity with the European and northern African faunas. This link was severed in the late Eocene.

Flow dynamics and channel changes at Yamuna River in Delhi-National Capital Region, India

ABSTRACT The present work was carried out on River Yamuna passing through Delhi-National Capital Region (Delhi-NCR) of India for a stretch of about 125 km to assess the fluvial characteristics in the highly human-dominated region for a period of 200 years with the help of historical maps, topographical maps and satellite data with integration of geographic information system (GIS) environment. Erosion, deposition and channel stability data were analyzed for 1977–1986, 1986–1996, 1996–2006, 2006–2016, and 2016–2022 period. Digital Shoreline Analysis System (DSAS) application was utilized to quantify river channel movement with average channel migration of 22.8 m/year. Westward migration is 4149.2 m maximum in length and eastward migration is about 4083.8 m. The river has migrated a total of 32.26 km2 of area during 1955-2022. The findings indicate that various human activities, such as engineering structures, sand mining, embankments, urbanization, land use/land cover changes, and canal networks, have significantly impacted the river. The DSAS application was also used to predict the position of river channel centerline in future for 2032 and 2042 with channel length of 132.5 and 141.6 km respectively.

Westward Migration of the Chenghai–Jinsha Drainage Divide and Its Implication for the Initiation of the Chenghai Fault

The Chenghai Fault in the Chuan–Dian block terminates at the northwestern segment of the Red River Fault, and is a significant seismogenic structure. The kinematic evolution of this fault should be closely related to the regional tectonic deformation. However, it is difficult to obtain information on structural deformation of the Chenghai Fault due to the large amount of precipitation and well-developed vegetation. The Chenghai normal faulting may drive drainage reorganization in this region, which provides a new perspective for reconstructing and evaluating the tectonic history. High-resolution digital elevation models (DEM) obtained by remote sensing greatly facilitate the study of drainage evolution and active tectonics. We use two methods (χ-plot and Gilbert metrics) to measure the drainage divide stability based on the ALOS DEM (12.5 m resolution) and further reproduce the drainage evolution process in response to the asymmetric uplift by numerical modeling. The results show that the Chenghai–Jinsha drainage divide, hosted by the footwall block of the Chenghai Fault, is migrating westward (away from the Chenghai Fault) and will continue moving ~2.2–3.5 km to reach a steady state. Its migration is controlled by the Chenghai normal faulting. The Chenghai–Jinsha drainage divide formed close to the Chenghai Fault’s surface trace and continues to migrate westward in response to the asymmetric uplift. It only took a few million years for the Chenghai–Jinsha drainage divide to migrate to its current location based on the numerical modeling. The restoration of the drainage reorganization implies that the Chenghai Fault initiated in the Pliocene, which probably results from kinematic reversal along the Red River Fault.

Propagation and Maintenance of the Quasi-Biweekly Oscillation over the Western North Pacific in Boreal Winter

Abstract This study investigates the propagation and maintenance mechanisms of the dominant intraseasonal oscillation over the western North Pacific in boreal winter, the quasi-biweekly oscillation (QBWO). The wintertime QBWO over the western North Pacific is characterized by the westward-northwestward movement from the tropical western Pacific to the western North Pacific and resembles the n = 1 equatorial Rossby wave. Its westward migration is primarily driven by the seasonal-mean zonal winds that advect vorticity anomalies in the lower–middle troposphere and moisture anomalies in the lower troposphere. Its northward movement is preconditioned by the vorticity dynamics of the beta effect, the low-level vertical moisture variation, and the local air–sea interaction. The latter involves the atmospheric forcing on the underlying ocean by changing the surface heat flux fluctuations and the sea surface temperature feedback on the low-level atmospheric instability. Its maintenance is primarily through atmospheric external energy sources from diabatic heating, which first generates eddy available potential energy and then converts it to eddy kinetic energy. Significance Statement Atmospheric quasi-biweekly oscillation (QBWO) is an important climate phenomenon over the western North Pacific in boreal winter. It can trigger significant influences both in the tropical and extratropical regions. Given the importance, it is necessary to investigate the propagation and maintenance mechanisms of the QBWO over the western North Pacific in boreal winter. The QBWO usually propagates northwestward from the tropical western Pacific to the western North Pacific. The westward propagation is driven by the seasonal mean zonal winds that advect vorticity anomalies in the lower–middle troposphere and moisture anomalies in the lower troposphere. The northward propagation is caused jointly by several processes, including the atmospheric forcing on the ocean via the surface heat flux fluctuations, the feedback of ocean on the low-level atmospheric instability, the vorticity dynamics of the beta effect, and the vertical variation of low-level moisture. In addition, converting from eddy available potential energy to eddy kinetic energy is essential in maintaining the QBWO’s development. The disclosure of these crucial processes deepens the dynamics of the QBWO over the western North Pacific in boreal winter.

Historical Origins and Festive Activities of the Westward Migration Festival of the Sibe Tribe in China

The Sibe people, an ancient ethnic group in China, accomplished the historical feat of moving westward to Xinjiang to settle and garrison the border in the Qianlong period, making important contributions to the defense and construction of China’s western frontier. The Westward Migration Festival is the carrier of the historical memory of the westward migration of the Sibe people, which embodies the ethnic cultural characteristics of the Sibe people, inherits the spirit of westward migration, and has an important value and role in the construction of the sense of community of the Chinese ethnic in the western frontier region. This paper collects and organizes the research results related to the history and culture of the westward migration of the Sibe people, and summarizes the historical origin and ceremonial activities of the Westward Migration Festival to provide reference for further research work in the future.

A switch in thermal and haline contributions to stratification in the Greenland Sea during the last four decades

A switch in thermal and haline contributions to stratification in the Greenland Sea during the last four decades

A Study on the Culture and Values of the Westward Migration Festival of the Sibe Ethnic Group in China

The Westward Migration Festival presents the image of the patriotic historical feat of the Sibe people’s westward migration to Xinjiang and garrisoning of the frontier through sacrificial ceremonies such as the sacrifice of Karun and the public sacrifice of Tibet, as well as celebratory activities such as the Zhulun Hulanbi, the Beilun dance, the archery competition, and the goat-carrying competition. Its cultural space reproduces the historical memory of the ethnicity, illustrates the patriotic dedication of the ethnic groups, the mentality of harmony and coexistence, and the sense of self-reliance and self-existence, and plays a role in enhancing the cultural memory of the ethnic and consolidating the consensus of the ethnic culture. Through the benign interaction of festivals, the ideological foundation is laid for the construction of the Chinese ethnic community consciousness in the western border areas, the value norms are provided, and the social foundation is stabilized.

Møre–Vøring Composite Tectono-Sedimentary Element, Norwegian Rifted Margin, Norwegian Sea

Abstract The Møre and Vøring basins at the mid-Norwegian margin were affected by a series of rift phases separated by periods of tectonic quiescence from Caledonian collapse in the Devonian to final continental break-up in the earliest Eocene. The tectonic phases were mostly extensional in nature, and the pre-drift extension across the Møre and Vøring basins since mid-Permian time has been estimated to be of the order of 200–250 km. The pre-Cretaceous basin configuration is poorly constrained due to limited seismic resolution at great depths and a lack of borehole control. A fundamental change occurred in the crustal deformation regime: from Late Jurassic distributed stretching of the upper crust to Early Cretaceous thinning at lower-crustal levels located along the axis of the Møre and Vøring basins. A westward migration of Late Cretaceous–Paleocene depocentres in the Vøring Basin reflects the focus of deformation towards the time and line of break-up. The basin architecture and evolution are summarized in relation to tectono-sedimentary elements corresponding to the main tectonic and depositional phases, and represent characteristic megasequences in the seismic data. Finally, the exploration history and main petroleum systems of the Møre and Vøring basins are presented.

Prediction of potential distributions of Morina kokonorica and Morina chinensis in China.

Changes in the habitats of species can provide insights into the impact of climate change on their habitats. Species in the genus Morina (Morinoideae) are perennial herbaceous plants that are mainly distributed in the South Asian Mountains and Eastern Mediterranean. In China, there are four species and two varieties of this genus distributed across the Yunnan, Sichuan, Qinghai, and Gansu provinces. This study used the optimal MaxEnt model to simulate past, current, and future potentially suitable habitats of Morina kokonorica and Morina chinensis. Seventy data of M. kokonorica occurrences and 3 of M. chinensis were used in the model to predict potentially suitable habitats. The model prediction results indicated that both M. kokonorica and M. chinensis exhibited trends of northward migration to higher latitudes and westward migration along the Himalayas to higher elevations, suggesting that the northern valleys of Hengduan Mountains and northern and eastern parts of the Himalayas were potential refugia for M. kokonorica, and the potential refugia for M. chinensis was located in the eastern part of Qinghai-Tibet Plateau. The results of this niche analysis showed that the two species had higher levels of interspecific competition and that the environmental adaptability of M. chinensis was stronger. This research could help further understand the response pattern of Morina to environmental change, to understand the adaptability of species to the environment, and promote the protection of species.

Recognizing big mantle wedges in deep time: Constraints from the Western Mongolia Collage in Central Asia

Abstract A big mantle wedge (BMW) is defined as the broad region of upper mantle above a stagnant slab in the mantle transition zone (MTZ). It is a common and significant structure within Earth's interior at modern convergent plate margins as revealed by seismic data yet rarely identified in fossil convergent systems. We propose the existence of a BMW beneath the Western Mongolia Collage during the early to middle Paleozoic based on a comprehensive chronology of geological events that characterized the accretionary orogen in this region. The trench-arc system initially developed above a NE-dipping subduction zone, with subduction-related arc magmatism clustered at ca. 530–490 Ma and accumulations of flysch-like sequences from the Cambrian to early Silurian constituting the accretionary wedge of the Altai Zone. The westward migration of the arc was likely driven by slab rollback and trench retreat, leading to gradual formation of a BMW as the slab stagnated at the MTZ. The BMW influenced the tectonic evolution of the entire Western Mongolia Collage, inducing Ordovician–Silurian intraplate magmatism in regions inboard of the migrating magmatic arc and the potential opening of the Mongol-Okhotsk Ocean. Westward movement of the trench-arc continued until the Devonian, resulting in back-arc basin formation in the Chinese Altai and intraplate magmatism in the Hovd and Lake Zones of the Western Mongolia Collage, forming a trench–arc–back-arc and intraplate tectonic system. Mantle flow within the BMW is inferred to have impacted magmatism, basin migration, and the stress and thermal state of the overriding plate.

Westward Migration of Tropical Cyclone Activity in the Western North Pacific during 1982–2020: Features and Possible Causes

Westward Migration of Tropical Cyclone Activity in the Western North Pacific during 1982–2020: Features and Possible Causes

Toroidal flow around the Tonga slab moved the Samoan plume during the Pliocene

Abstract Age-progressive seamount tracks generated by lithospheric motion over a stationary mantle plume have long been used to reconstruct absolute plate motion (APM) models. However, the basis of these models requires the plumes to move significantly slower than the overriding lithosphere. When a plume interacts with a convergent or divergent plate boundary, it is often deflected within the strong local mantle flow fields associated with such regimes. Here, we examined the age progression and geometry of the Samoa hotspot track, focusing on lava flow samples dredged from the deep flanks of seamounts in order to best reconstruct when a given seamount was overlying the mantle plume (i.e., during the shield-building stage). The Samoan seamounts display an apparent local plate velocity of 7.8 cm/yr from 0 to 9 Ma, 11.1 cm/yr from 9 to 14 Ma, and 5.6 cm/yr from 14 to 24 Ma. Current fixed and mobile hotspot Pacific APM models cannot reproduce the geometry of the Samoa seamount track if a long-term fixed hotspot location, currently beneath the active Vailulu’u Seamount, is assumed. Rather, reconstruction of the eruptive locations of the Samoan seamounts using APM models indicates that the surface expression of the plume migrated ~2° northward in the Pliocene. Large-scale mantle flow beneath the Pacific Ocean Basin cannot explain this plume migration. Instead, the best explanation is that toroidal flow fields—generated by westward migration of the Tonga Trench and associated slab rollback—have deflected the conduit northward over the past 2–3 m.y. These observations provide novel constraints on the ways in which plume-trench interactions can alter hotspot track geometries.

Education-to-Work Transitions in Former Communist Countries after 30-Plus Years of Transformation

This paper reviews how young people’s education-to-work transitions have changed since 1989 in former communist countries that have subsequently become full members of the European Union (EU). The sudden collapse of the command economies led to an equally abrupt breakdown in earlier routes into working life. Subsequently, the new independent states have reconstructed their education and training, and their market economies have developed. They now exhibit similar variations in rates of youth unemployment, progression through higher education, and mixtures of academic and vocational secondary education as older EU member states. However, there are features that continue to set all ex-communist countries apart, irrespective of whether they have become full EU members. These are low local rates of pay and westward migration. Its new member states have joined the Southern countries in a European periphery. Yet, there may be sufficient winners in the European core and periphery to keep Europe united.

Long-term spatiotemporal characteristics of meteorological drought in China from a three-dimensional (longitude, latitude, time) perspective

Long-term spatiotemporal characteristics of meteorological drought in China from a three-dimensional (longitude, latitude, time) perspective

Meteorological drought migration characteristics based on an improved spatiotemporal structure approach in the Loess Plateau of China

The development of drought has spatial and temporal synchronization. Previous studies usually explore the spatial and temporal evolution of drought separately. Moreover, existing approaches are based on a fixed overlapping area and do not consider the variable drought cluster area during development. This study proposes an improved and simple approach to derive dynamic overlapping area threshold for 3-dimensional droughts extraction. Based on the one monthly Nonparametric Standardized Precipitation Index (NSPI), this improved approach was applied for investigating the migration characteristics of meteorological drought events in the Loess Plateau of China. Then, Random Forest and Extreme Gradient Boosting model with Shapley additive explanation values were used to quantify the importance of driving factors on the dynamics of drought characteristics. The results showed that: (1) the improved approach has a better performance on identifying prolonged droughts than the method using a fixed overlap area threshold; (2) spatially, meteorological drought events with high severity (DS), long duration (DD), large effected area (DA) and fast migration velocity (DV) mainly occur in the central region; (3) temporally, droughts are expected to aggravate with significantly increased DS and DA which are mainly caused by increased temperature and vegetation; and (4) meteorological droughts have a preferred westward migration direction and three dominant migration paths, which are crucial for local drought prevention and control. The findings of this study provide new perspectives on drought migration characteristics, which are important for the exploration of drought-driven mechanisms, risk assessment and future prediction.

Neogene morphotectonic evolution of the East Asian Continental Shelf

Neogene morphotectonic evolution of the East Asian Continental Shelf