North-south Changes Research Articles

The quasi-biweekly oscillation of eastern China PM2.5 in response to different Rossby wave trains over the Eurasian continent

This study investigates the wintertime quasi-biweekly oscillation characteristic of PM2.5 in eastern China and its relationship with Rossby wave trains propagating over the Eurasian continent. The Empirical orthogonal function (EOF) analysis extracts the three leading modes of PM2.5, including one monopole pattern (Mcon), a north-south dipole pattern (Msn), and a west-east dipole pattern (Mew). The three modes exhibit distinct quasi-biweekly oscillation features (QBWO) under the coupling effects of two Rossby wave trains within the polar front jet and the subtropical westerly jet. The quasi-biweekly evolutions of the Eurasian teleconnection pattern (EU) and Circumglobal teleconnection pattern (CGT) are responsible for the propagation of the two wave trains. The QBWO typical combination cases of the two wave trains are the decay of the EU negative phase and development of the CGT negative phase for Mcon, the development of the EU negative phase and decay of the CGT positive phase for Msn, and the decay of the EU negative phase and development of the CGT positive phase for Mew. A consistent change in surface southerly wind anomalies forms in the north and south when the decay of the EU negative phase works cooperatively with the development of the CGT negative phase, resulting in the PM2.5 monopole pattern (Mcon). The combination case with the development of the EU negative phase and decay of the CGT positive phase favors strong stratification stability in the north and vigorous vertical convection in the south, causing opposing north-south changes in pollutants (Msn). When the decay of the EU negative phase couples with development of the CGT positive phase, surface southerly wind anomalies prevail in the Fenwei Plain, and surface northeasterly wind anomalies from the sea trigger convection in the Yellow River Basin and Huaihe River Basin, forming opposing west-east changes in PM2.5 (Mew).

Origin of ethnic groups, linguistic families, and civilizations in China viewed from the Y chromosome

East Asia, geographically extending to the Pamir Plateau in the west, to the Himalayan Mountains in the southwest, to Lake Baikal in the north and to the South China Sea in the south, harbors a variety of people, cultures, and languages. To reconstruct the natural history of East Asians is a mission of multiple disciplines, including genetics, archaeology, linguistics, and ethnology. Geneticists confirm the recent African origin of modern East Asians. Anatomically modern humans arose in Africa and immigrated into East Asia via a southern route approximately 50,000 years ago. Following the end of the Last Glacial Maximum approximately 12,000 years ago, rice and millet were domesticated in the south and north of East Asia, respectively, which allowed human populations to expand and linguistic families and ethnic groups to develop. These Neolithic populations produced a strong relation between the present genetic structures and linguistic families. The expansion of the Hongshan people from northeastern China relocated most of the ethnic populations on a large scale approximately 5300 years ago. Most of the ethnic groups migrated to remote regions, producing genetic structure differences between the edge and center of East Asia. In central China, pronounced population admixture occurred and accelerated over time, which subsequently formed the Han Chinese population and eventually the Chinese civilization. Population migration between the north and the south throughout history has left a smooth gradient in north-south changes in genetic structure. Observation of the process of shaping the genetic structure of East Asians may help in understanding the global natural history of modern humans.

Structure of the Ecuadorian forearc from the joint inversion of receiver functions and ambient noise surface waves

SUMMARYThe Ecuadorian forearc is a complex region of accreted terranes with a history of large megathrust earthquakes. Most recently, a Mw 7.8 megathrust earthquake ruptured the plate boundary offshore of Pedernales, Ecuador on 16 April 2016. Following this event, an international collaboration arranged by the Instituto Geofisico at the Escuela Politécnica Nacional mobilized a rapid deployment of 65 seismic instruments along the Ecuadorian forearc. We combine this new seismic data set with 14 permanent stations from the Ecuadorian national network to better understand how variations in crustal structure relate to regional seismic hazards along the margin. Here, we present receiver function adaptive common conversion point stacks and a shear velocity model derived from the joint inversion of receiver functions and surface wave dispersion data obtained through ambient noise cross-correlations for the upper 50 km of the forearc. Beneath the forearc crust, we observe an eastward dipping slow velocity anomaly we interpret as subducting oceanic crust, which shallows near the projected centre of the subducting Carnegie Ridge. We also observe a strong shallow positive conversion in the Ecuadorian forearc near the Borbon Basin indicating a major discontinuity at a depth of ∼7 km. This conversion is not ubiquitous and may be the top of the accreted terranes. We also observe significant north–south changes in shear wave velocity. The velocity changes indicate variations in the accreted terranes and may indicate an increased amount of hydration beneath the Manabí Basin. This change in structure also correlates geographically with the southern rupture limit of multiple high magnitude megathrust earthquakes. The earthquake record along the Ecuadorian trench shows that no event with a Mw >7.4 has ruptured south of ∼0.5°S in southern Ecuador or northern Peru. Our observations, along with previous studies, suggest that variations in the forearc crustal structure and subducting oceanic crust may influance the occurrence and spatial distribution of high magnitude seismicity in the region.

Contrasting North–South changes in Amazon wet-day and dry-day frequency and related atmospheric features (1981–2017)

This study provides an updated analysis of the evolution of seasonal rainfall intensity in the Amazon basin, considering the 1981–2017 period and based on HOP (interpolated HYBAM observed precipitation) and CHIRPS (The Climate Hazards Group Infrared Precipitation with Stations) rainfall data sets. Dry and wet day frequencies as well as extreme percentiles are used in this analysis, producing the same results. Dry-day frequency (DDF) significantly increases in the Southern Amazon (p < 0.01), particularly during September–November (SON) in the Bolivian Amazon, central Peruvian Amazon and far southern Brazilian Amazon. Consistently, total rainfall in the southern Amazon during SON also shows a significant diminution (p < 0.05), estimated at 18%. The increase in SON DDF in the southern Amazon is related to a warming of the northern tropical Atlantic Ocean and a weakening of water vapour flux from the tropical Atlantic Ocean. The increase in DDF in the southern Amazon is related to enhanced wind subsidence (ascendance) over the 10°S–20°S (5°S–5°N) region and to a deficit (excess) of specific humidity at 1000–300 hPa south of 10°S (north of the 5°S), which suggest a reduction of deep convection over southern Amazonia. Subsidence over the southern Amazon shows a significant trend (p < 0.01), which can explain the significant increase in DDF. Wet-day frequency (WDF) significantly increases in the northern Amazon, particularly during the March–May (MAM) period (p < 0.01), producing an estimated rainfall increase during MAM of 17% (p < 0.01) between 1981 and 2017. Significant changes in both WDF and rainfall in northern Amazon have been detected in 1998 (p < 0.01). After 1998, the increase in MAM WDF and rainfall is explained by enhanced moisture flux from the tropical North Atlantic Ocean and an increase in deep convection over the northern and northwestern Amazon. These evolutions in DDF and WDF and in the tropical atmosphere occur simultaneously with an increase in sea surface temperature in the northern Atlantic Ocean, particularly after the mid-1990s. These results provide new insight into rainfall variability and climatic features related to increasing dry season length in southern Amazonia. Severe recent droughts may be associated with the increase in DDF in the South. In addition, the increase in MAM rainfall intensity in northern Amazon after 1998 may be associated with several historical floods that occurred after this date.

Spatial variability in winter NAO–wind speed relationships in western Europe linked to concomitant states of the East Atlantic and Scandinavian patterns

The 3‐hourly gridded ECMWF ERA‐Interim climate reanalysis dataset, spanning 1979–2013, was used to investigate the spatial stationarity of the previously documented relationships between wind speeds and the North Atlantic Oscillation (NAO) state in Europe. Over much of western Europe, wind speeds were found to be affected strongly by the concomitant states of the secondary and tertiary atmospheric teleconnections, namely the East Atlantic (EA) and the Scandinavian (SCA) patterns. These modify the geographic positions of the NAO dipole and modulate the influence of the NAO on wind statistics on regional scales, producing non‐stationarities in the NAO–wind speed relationships. The interactions of these teleconnections play an important role in modifying wind speeds within Europe. Finally, systematic north–south changes in the Weibull distribution scale and shape parameters are documented along the western margin of Europe, as a function of different states of the NAO, the EA and the SCA. These effects influence both monthly averaged wind speeds and the statistical distributions of 3‐hourly wind data, implying strong impacts on wind energy resources and expected wind power production. The results have implications for regional to continent‐scale long‐term planning of wind‐farm siting to minimise the impact of resource intermittency.

Further characterization of honey bees from the Iberian Peninsula by allozyme, morphometric and mtDNA haplotype analyses

SummaryIt has been proposed that the Iberian Peninsula served as an important refuge for honey bees during periods of European glaciation. The discovery of genetic markers originating from both African and European honey bee lineages in extant Iberian populations led to hypotheses that the region may be a zone of hybridization or reflect the action of human-assisted translocations. In the present study, we investigated allozyme, mitochondrial and morphological variation in honey bee populations sampled from southern France to northern Morocco. Morphological data supported the interpretation that the bees of Iberia, south and west of a line from Zaragoza to Barcelona, can be characterized as the subspecies Apis mellifera iberica (A. m. iberiensis). There appears to be a narrow demarcation between this subspecies and A. m. mellifera, rather than a gradual cline. The persistence of significant subpopulation differentiation indicates that migratory beekeeping has not strongly influenced the genetic characteristics of local populations. Allozyme data were consistent with previous studies showing north—south changes in allele frequencies, possibly related to subspecific origins or selection. Although mtDNA haplotypes of presumptive A lineage origin were found to be prevalent in Iberian honey bee populations, morphological analysis and published microsatellite evidence does not show a comparatively strong influence from the nearby African subpopulation (Morocco).

Detrital zircon reference for Cambrian to Triassic miogeoclinal strata of western North America

U-Pb analyses of 656 single zircon grains from Cambrian to Triassic miogeoclinal strata provide a latitudinal and temporal reference for the ages of grains that accumulated along the western margin of North America. Comparisons between this detrital zircon reference and the ages of grains in potentially displaced terranes outboard (west) of the miogeocline should help establish when the terranes first arrived in sedimentary proximity to western North America. North-south variations in the ages of grains in Cambrian and Devonian to Triassic strata, which reflect the north-south changes in the age of cratonal rocks near the margin, should also help place constraints on a terrane's paleolatitude during these time periods. The technique cannot be used to determine paleolatitude during Ordovician time, however, because miogeoclinal strata from northern Canada to northern Mexico are dominated by grains shed from the Peace River arch (northwestern Canada).

Influence of inherited taper on structural variability and conglomerate distribution, Cordilleran fold and thrust belt, western United States

North-south changes in thickness of the prethrust stratigraphy of the North American Cordillera within the United States controlled kinematic development of the late Mesozoic (Sevier) fold and thrust belt. Variation in stratigraphic thickness determined the initial slope (β o ) of the basal decollement beneath the thrust wedge. As predicted by critical-wedge theory, segments of the Sevier thrust belt with initially thick Precambrian and Paleozoic stratigraphic sections are structurally simple and are composed of few thrust sheets; segments with thin prethrust stratigraphy and comparably low values of β o are intensely imbricated. The difference in structural style resulted because wedge segments with higher values of β o required less internal deformation to build and maintain the critical taper required for thrust-wedge advance. Transverse structural zones, across which kinematic style differed, formed at the terminations of thrust-belt segments and controlled the locations of long-lived antecedent drainage systems that transported gravel to the foreland. Therefore, along-strike changes in prethrust stratigraphic thickness resulted in an observed disjunct distribution of conglomerate in synorogenic deposits of the thrust wedge and foreland basin.

Rocky intertidal fish communities of California: temporal and spatial variation

We examined data from our own and published collections of intertidal and shallow littoral fishes of the North American Pacific Coast with respect to temporal and spatial trends in species composition and dominance. We compared (1) recent and past intertidal collections made five and seven years apart, respectively, for two California localities, (2) intertidal collections from twelve localities in California, Oregon, and British Columbia, and (3) intertidal versus subtidal collections at one California locality. Temporal comparisons indicated substantially lower abundance of the cottid Oligocottus snyderi at two California localities during 1984, at one locality due to depressed abundance of young. Interannual differences in abundances suggested that other tidepool fish assemblages undergo significant changes as well. Geographical comparisons indicated general similarity in species composition, with cottids predominating in tidepools although several other families also were well represented (e.g., Stichaeidae, Scorpaenidae). Eel-shaped stichaeids and pholids occurred at high densities in exposed boulder fields. Both the tidepool and boulder field assemblages showed north-south changes in species abundances. Comparison of collections from the intertidal and subtidal zones at one California locality demonstrated that fishes of these habitats form two essentially distinct assemblages, with most species restricted to or concentrated in one or the other habitat.

What do weapons secure?

The iron triangle of the Defense Department, Congressional hawks, and the defense industry will fight any efforts to reduce President Reagan's plan to rearm America and will dominate any debate over national security and weapons procurement as they have done since 1945. American attitudes are changing, however, and pressing for a re-evaluation of this closed policy apparatus. The first step to be taken is a re-examination of global and national realities to see if current policy is appropriate. Reagan has reversed the trend toward arms control to more strategic arms competition which, by creating waste and distrust, will reduce security. It also narrows policy considerations to East-West rivalry and ignores the North-South changes that are taking place. US failures in Vietnam and Watergate and a negative response to US involvement in Central America are signs that the public is increasingly skeptical of the iron triangle. (DCK)

Frequency-Wavenumber Spectra of Sea Surface Temperature and Wind-Stress Curl in the Eastern North Pacific

Abstract Frequency-wavenumber spectra of sea surface temperature and wind-stress curl are computed from 11 years of surface marine observations taken in the eastern North Pacific. These data were averaged by month and 2° quadrangles to yield spectra with periods from 2 to 48 months and zonal wavelengths from 400 to 4000 km. Spectra were computed for all 2° zonal bands between 16 and 40°N using data from the area between 120 and 160°W. Missing monthly values led to the computation of these spectra using a least-squares Fourier expansion which eliminated the need for temporal interpolation. Frequency spectra computed with this technique compare well with spectra using standard Fourier methods. The resulting spectra were found to separate naturally into two regions; one between 29 and 40°N and the second between 15 and 29°N. Even within these zonal bands there were some important north–south changes. The annual signal was found to dominate the spectra of sea surface temperature at almost all wavelengths. The...

SOURCE OF SHARON CONGLOMERATE OF NORTHEASTERN OHIO

Research Article| February 01, 1955 SOURCE OF SHARON CONGLOMERATE OF NORTHEASTERN OHIO J. OSBORN FULLER J. OSBORN FULLER 1 Presented with the encouragement of the Geological Survey of Ohio. THE OHIO STATE UNIVERSITY, COLUMBUS 10, OHIO Search for other works by this author on: GSW Google Scholar GSA Bulletin (1955) 66 (2): 159–176. https://doi.org/10.1130/0016-7606(1955)66[159:SOSCON]2.0.CO;2 Article history received: 29 Jun 1954 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation J. OSBORN FULLER; SOURCE OF SHARON CONGLOMERATE OF NORTHEASTERN OHIO. GSA Bulletin 1955;; 66 (2): 159–176. doi: https://doi.org/10.1130/0016-7606(1955)66[159:SOSCON]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Sharon conglomerate crops out in three separate areas in Ohio and in all of these the formation has similar characteristics and is the basal Pennsylvanian bed resting unconformably on Mississippian sandstone or shale. This paper is concerned chiefly with the larger area of outcrop in northeastern Ohio which lies west of the type area at Sharon, Pennsylvania. The formation is dominantly a pure (96+% SiO2), medium-grained, quartz sandstone (orthoquartzite) with a few pebble layers or scattered pebbles. Laterally this rock grades into a series of narrow, conglomerate belts 1000± feet wide and 10–50 feet thick. Trend of these belts, and, in the whole formation, dip of cross-bedding, dip of the initial slope, direction of overturning of tops of cross-beds, imbricate structure, and north-south changes in sedimentary features, mechanical analyses, and chemical analyses all indicate a northern source for the clastic material of the Sharon conglomerate and also suggest a deltaic type of depositional environment. In older literature the pebbles of the Sharon are described as “vein quartz” suggesting an igneous rock source. Fossils as pebbles, and pebbles of sandstone, and conglomerate indicate rocks that were in part sedimentary. Almost no minerals are present except quartz and most of the quartz grains show secondary growth, indicating that the individual grains have been through more than one cycle of sedimentation. Although igneous rocks were doubtlessly the original source of many of the multicycle particles, the lack of pebbles of igneous rock and grains of igneous rock accessory minerals strongly suggests that the sediments of the Sharon are several cycles removed from the original source rocks. This concept is confirmed by examination of thin sections. Most pebbles show ghost granular structure and the inclusions in both pebbles and sand grains are characteristic of quartz derived from a metamorphic source.The fossils, most of which are tabulate corals, prove that at least part of the source was Middle Devonian (Onondaga-Hamilton). The writer concludes that the Sharon sediments originated in a Canadian highland composed of a mixture of sedimentary and metamorphic rocks some of which were of Middle Devonian age, and that these sediments were transported by streams of considerable competency and were ultimately deposited as a delta in a shallow basin developed on Mississippian rocks.The characteristics of the Sharon in southern Ohio indicate a similar origin but the clastic components were apparently derived from the southeast as shown by direction of dip of cross-beds and trend of conglomerate belts. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.