scholarly journals Influence of Surface Processes over Africa on the Atlantic Marine ITCZ and South American Precipitation

2005 ◽  
Vol 18 (23) ◽  
pp. 4993-5010 ◽  
Author(s):  
Samson M. Hagos ◽  
Kerry H. Cook
Keyword(s):  
Soil Moisture ◽  
South America ◽  
Atlantic Ocean ◽  
South American ◽  
Tropical Africa ◽  
Surface Wetness ◽  
The North ◽  
Symmetric Perturbation ◽  
Dry Conditions ◽  
Weak Influence

Abstract Previous studies show that the climatological precipitation over South America, particularly the Nordeste region, is influenced by the presence of the African continent. Here the influence of African topography and surface wetness on the Atlantic marine ITCZ (AMI) and South American precipitation are investigated. Cross-equatorial flow over the Atlantic Ocean introduced by north–south asymmetry in surface conditions over Africa shifts the AMI in the direction of the flow. African topography, for example, introduces an anomalous high over the southern Atlantic Ocean and a low to the north. This results in a northward migration of the AMI and dry conditions over the Nordeste region. The implications of this process on variability are then studied by analyzing the response of the AMI to soil moisture anomalies over tropical Africa. Northerly flow induced by equatorially asymmetric perturbations in soil moisture over northern tropical Africa shifts the AMI southward, increasing the climatological precipitation over northeastern South America. Flow associated with an equatorially symmetric perturbation in soil moisture, however, has a very weak cross-equatorial component and very weak influence on the AMI and South American precipitation. The sensitivity of the AMI to soil moisture perturbations over certain regions of Africa can possibly improve the skill of prediction.

South American Missions

2021 ◽  
Author(s):  
Cameron Jones
Keyword(s):  
South America ◽  
Amazon Basin ◽  
Colonial Period ◽  
Indigenous Populations ◽  
South American ◽  
Extensive Experience ◽  
Republican Period ◽  
The North ◽  
Bourbon Reforms ◽  
Franciscan Order

While it is certainly true that more academic studies have focused on the North American missions, in terms of their historical impact South American missions were just as important to the frontiers of Spain and Portugal’s American empires. The massive size alone of the frontier region, stretching from the upper reaches of the Amazon basin to the headwaters of the Paraná as well as stretching across the lower Southern Cone, meant numerous missionary enterprises emerged in an attempt to evangelize the peoples who inhabited these regions. While small handfuls of Dominicans, Mercedarians, and Augustinians would engage in such efforts, most missions were established by the Jesuits or Franciscans. Certainly, for the Jesuits, or the Society of Jesus as they are properly known, American missions represented an extension of the Counter-Reformation for which they were created. Starting in the mid-16th century, this relatively new organization, founded in 1534, began in earnest to “reduce” the Indigenous peoples into their missions. These activities, however, abruptly ended when the Jesuits were expelled from both the Portuguese and Spanish empires in 1759 and 1767 respectfully. The much older Franciscan order had extensive experience in popular missions in Europe and was one of the first orders of regular clergy in the Americas. Franciscans, like the Jesuits, engaged in evangelizing activities throughout both North and South America from the colonial period to the present. The expulsion of the Jesuits, however, pushed them further to the forefront of missionizing efforts in the late colonial period. This acceleration of Franciscan missionary activity was aided by the establishment of the Apostolic Institute in 1682. The Institute created a pipeline of missionaries from Spain to come directly to frontier areas with funding from the crown. While this aided missionary efforts throughout South America, particularly in areas abandoned by the Jesuits, it embroiled the missionaries in the politics of the Bourbon reforms and their obsession with limited clerical power. Ultimately, while missionizing efforts continued into the Republican period, their association with the Spanish and Portuguese crowns led to widespread suppression and secularization following independence. The historiographical divide in the field tends to lie between usually older, Eurocentric histories by scholar-clerics which focus on the missionaries themselves, and newer studies carried out by more secular professional historians that examine how Indigenous populations were affected by the inherent imperialism of the missions, though exceptions abound.

Geodynamic study of the north of the Andes block (Colombia, Panama, Ecuador and Venezuela) through gnss-gps: models of displacements, models of deformation and definition of local and regional geodynamic structures.

2020 ◽  
Author(s):  
Berrocoso Manuel ◽  
Del Valle Arroyo Pablo Emilio ◽  
Colorado Jaramillo David Julián ◽  
Gárate Jorge ◽  
Fernández-Ros Alberto ◽  
...  
Keyword(s):  
South America ◽  
Seismic Activity ◽  
Great Part ◽  
Velocity Model ◽  
South American ◽  
The South ◽  
South American Plate ◽  
Northern Andes ◽  
Velocity Models ◽  
The North

<p>The northwest of South America is conformed by the territories of Ecuador, Colombia and Venezuela. Great part of these territories make up the Northern Andes Block (BAN). The tectonic and volcanic activity in the northwest of South America is directly related to the interaction of the South American plate, and the Nazca and Caribbean plates, with the Maracaibo and Panama-Chocó micro plates. The high seismic activity and the high magnitude of the recorded earthquakes make any study necessary to define this complex geodynamic region more precisely. This work presents the velocity models obtained through GNSS-GPS observations obtained in public continuous monitoring stations in the region. The observations of the Magna-eco network (Agustín Codazzi Geographic Institute) are integrated with models already obtained by other authors from the observations of the GEORED network (Colombian Geological Service). The observations have been processed using Bernese software v.52 using the PPP technique; obtaining topocentric time series. To obtain the speeds, a process of filtering and adjustment of the topocentric series has been carried out. Based on this velocity model, regional structures have been defined within the Northern Andes Block through a differentiation process based on the corresponding speeds of the South American, Nazca and Caribbean tectonic plates. Local geodynamic structures within the BAN itself have been established through cluster analysis based on both the direction and the magnitude of each of the vectors obtained. Finally, these structures have been correlated with the most significant geodynamic elements (fractures, faults, subduction processes, etc.) and with the associated seismic activity.</p>

scholarly journals Sarcocystis neurona and related Sarcocystis spp. shed by opossums (Didelphis spp.) in South America

2021 ◽  
Vol 30 (3) ◽  
Author(s):  
Luís Fernando Pita Gondim ◽  
Rodrigo Martins Soares ◽  
Gastón Moré ◽  
Rogério Fernando de Jesus ◽  
Horwald Alexander Bedoya Llano
Keyword(s):  
South America ◽  
Special Focus ◽  
South American ◽  
Sarcocystis Species ◽  
Protozoan Parasites ◽  
Sarcocystis Neurona ◽  
Genetic Characteristics ◽  
The North ◽  
Sarcocystis Spp ◽  
American Opossum

Abstract Protozoan parasites of the genus Sarcocystis are obligatory heteroxenous cyst-forming coccidia that infect a wide variety of animals and encompass approximately 200 described species. At least four Sarcocystis spp. (S. falcatula, S. neurona, S. lindsayi and S. speeri) use opossums (Didelphis spp.) as definitive hosts, and two of them, S. neurona and S. falcatula, are known to cause disease in horses and birds, respectively. Opossums are restricted to the Americas, but their distribution in the Americas is heterogeneous. Five Didelphis spp. are distributed in South America (D. aurita, D. albiventris, D. marsupialis, D. imperfecta and D. pernigra) whereas just one opossum species (D. virginiana) is found in North America. Studies conducted in the last decades show that Sarcocystis spp., derived from South American Didelphis spp., have biological and genetic differences in relation to Sarcocystis spp. shed by the North American opossum D. virginiana. The aim of this review was to address the peculiar scenario of Sarcocystis species shed by South American opossums, with a special focus on diagnosis, epidemiology, and animal infections, as well as the genetic characteristics of these parasites.

The Kinetic Empires of Native American Nomads

2021 ◽  
pp. 1035-1057
Author(s):  
Pekka Hämäläinen
Keyword(s):  
Native American ◽  
South America ◽  
Great Plains ◽  
South American ◽  
Collective Identities ◽  
Long Distance ◽  
The North ◽  
Political Unity ◽  
And Control ◽  
North And South

This chapter re-examines the powerful nomadic-equestrian societies in the North and South American grasslands and makes the case for a distinctive imperial formation, the kinetic empire. Kinetic empires were shape-shifting, action-based regimes that turned mobility into an imperial strategy and revolved around mobile activities: long-distance raiding, seasonal expansions, transnational diplomatic missions, semi-permanent trade fairs, recurring political assemblies, and control over shifting nodes. Their governing systems were light and flexible, and they rose and stayed in power by capitalizing on their superior capacity to access and connect political and economic centers around them. The Comanche and Lakota Indians created the Western Hemisphere’s most prominent examples of kinetic empires in the North American Great Plains. In South America the Araucanians frustrated European colonizing efforts, commanded a large and expanding territory, and pulled other Native groups on their orbit, but lacked the Comanches’ and Lakotas’ strong collective identities and political unity.

White Flowers in South America: A New Species of Antiphytum (Echiochiloideae, Boraginaceae)

2020 ◽  
Vol 45 (4) ◽  
pp. 913-920
Author(s):  
Nidia Mendoza-Díaz ◽  
Marina Díaz ◽  
Patricia Brussa ◽  
Fabián Muñoz ◽  
José M. Bonifacino ◽  
...  
Keyword(s):  
New Species ◽  
South America ◽  
Endemic Species ◽  
North American Species ◽  
Distribution Range ◽  
Sharp Contrast ◽  
South American ◽  
South American Species ◽  
The North ◽  
A New Species

Abstract—Antiphytum charruasorum, a new endemic species from western Uruguay, is described. This is the only South American species in the genus with white corolla and an infra-medial cicatrix on the ventral face of the eremocarp, both features shared with the North American species of Antiphytum, in sharp contrast with the blue corolla and the basal cicatrix at the end of a stipe-like prolongation that characterizes all South American species in the genus. Antiphytum charruasorum increases the diversity of the genus in South America, as well as the endemism and distribution range into Uruguay. Moreover, this new species adds novel features in Antiphytum such as the irregularly dichasial inflorescences, the hirsute faucal appendages, the eremocarps with a tissue plug from the gynobase, and the habitat where the species has been reported.

scholarly journals A Single Chromosome Unexpectedly Links Highly Divergent Isolates of Toxoplasma gondii

mBio ◽  
2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Katelyn A. Walzer ◽  
Jon P. Boyle
Keyword(s):  
Toxoplasma Gondii ◽  
South America ◽  
North American ◽  
Phylogenetic Analyses ◽  
Unexpected Finding ◽  
Type I ◽  
South American ◽  
Single Chromosome ◽  
Content Type ◽  
The North

ABSTRACT Toxoplasma gondii is an obligate intracellular parasite that can cause disease in all warm-blooded animals studied to date, including humans. Over a billion people have been infected with this parasite worldwide. In Europe and North America, Toxoplasma has a clonal population structure, where only three lineages are highly dominant (strain types I, II, and III). Khan et al. [mBio 2(6): e00228-11, 2011] have carried out phylogenetic analyses on a large number of diverse strains from outside of these lineages and found evidence for a significant split between the clonal North American/European lineages and those in South America. In contrast to most of the genome, nearly all North American/European strains sampled, and the majority of South American strains sampled, harbored at least portions of a monomorphic chromosome Ia (Ia*). In contrast to previous models, these data suggest that the monomorphic haplotype originated in South America and migrated to the North. These authors propose that South American haplotype 12 was a precursor to modern-day type II, while South American haplotypes 6 and 9 crossed with haplotype 12 to give rise to the type I and III lineages, respectively. However, the findings reported by Khan et al. complicate the origin of chromosome Ia, since there are members of haplotypes 9 and 12 with nearly complete versions of Ia* and members of haplotypes 6 and 12 with over 50% of Ia*. This unexpected finding raises exciting new questions about how an entire common chromosome can be found within strains that are highly divergent at most other genomic loci.

scholarly journals Tropical climate and vegetation changes during Heinrich Event 1: comparing climate model output to pollen-based vegetation reconstructions with emphasis on the region around the tropical Atlantic Ocean

2011 ◽  
Vol 7 (3) ◽  
pp. 1973-2019 ◽  
Author(s):  
D. Handiani ◽  
A. Paul ◽  
L. Dupont
Keyword(s):  
South America ◽  
Atlantic Ocean ◽  
Northern Hemisphere ◽  
Land Surface ◽  
Climate Model ◽  
Vegetation Changes ◽  
Tropical Africa ◽  
Heinrich Event ◽  
Southward Shift ◽  
Heinrich Event 1

Abstract. Abrupt climate changes associated with Heinrich Event 1 (HE1) about 18 to 15 thousand years before present (ka BP) strongly affected climate and vegetation patterns not only in the Northern Hemisphere, but also in tropical regions in the South Atlantic Ocean. We used the University of Victoria (UVic) Earth System-Climate Model (ESCM) with dynamical vegetation and land surface components to simulate four scenarios of climate-vegetation interaction: the pre-industrial era (PI), the Last Glacial Maximum (LGM), and a Heinrich-like event with two different climate backgrounds (interglacial and glacial). The HE1-like simulation with a glacial climate background produced sea surface temperature patterns and enhanced interhemispheric thermal gradients in accordance with the "bipolar seesaw" hypothesis. It allowed us to investigate the vegetation changes that result from a transition to a drier climate as predicted for northern tropical Africa due to a southward shift of the Intertropical Convergence Zone (ITCZ). We found that a cooling of the Northern Hemisphere caused a southward shift of those plant-functional types (PFTs) in Northern Tropical Africa that are indicative of an increased desertification, and a retreat of broadleaf forests in Western Africa and Northern South America. We used the PFTs generated by the model to calculate mega-biomes to allow for a direct comparison between paleodata and palynological vegetation reconstructions. Our calculated mega-biomes for the pre-industrial period and the LGM corresponded well to the modern and LGM sites of the BIOME6000 (v.4.2) reconstruction, except that our present-day simulation predicted the dominance of grassland in Southern Europe and our LGM simulation simulated more forest cover in tropical and sub-tropical South America. The mega-biomes from the HE1 simulation with glacial background climate were in agreement with paleovegetation data from land and ocean proxies in West, Central, and Northern Tropical Africa as well as Northeast South America. However, our model did not agree well with predicted biome distributions in Eastern South America.

scholarly journals Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America

2016 ◽  
Vol 12 (4) ◽  
pp. 20160062 ◽  
Author(s):  
Kieren J. Mitchell ◽  
Sarah C. Bray ◽  
Pere Bover ◽  
Leopoldo Soibelzon ◽  
Blaine W. Schubert ◽  
...  
Keyword(s):  
South America ◽  
North American ◽  
Convergent Evolution ◽  
Phylogenetic Analyses ◽  
Early Pleistocene ◽  
South American ◽  
The North ◽  
Molecular Phylogenetic ◽  
North And South America ◽  
North And South

The Tremarctinae are a subfamily of bears endemic to the New World, including two of the largest terrestrial mammalian carnivores that have ever lived: the giant, short-faced bears Arctodus simus from North America and Arctotherium angustidens from South America (greater than or equal to 1000 kg). Arctotherium angustidens became extinct during the Early Pleistocene, whereas Arctodus simus went extinct at the very end of the Pleistocene. The only living tremarctine is the spectacled bear ( Tremarctos ornatus ), a largely herbivorous bear that is today only found in South America. The relationships among the spectacled bears ( Tremarctos ), South American short-faced bears ( Arctotherium ) and North American short-faced bears ( Arctodus ) remain uncertain. In this study, we sequenced a mitochondrial genome from an Arctotherium femur preserved in a Chilean cave. Our molecular phylogenetic analyses revealed that the South American short-faced bears were more closely related to the extant South American spectacled bear than to the North American short-faced bears. This result suggests striking convergent evolution of giant forms in the two groups of short-faced bears ( Arctodus and Arctotherium ), potentially as an adaptation to dominate competition for megafaunal carcasses.

scholarly journals South American monsoon response to iceberg discharge in the North Atlantic

2018 ◽  
Vol 115 (15) ◽  
pp. 3788-3793 ◽  
Author(s):  
Nicolás M. Stríkis ◽  
Francisco W. Cruz ◽  
Eline A. S. Barreto ◽  
Filipa Naughton ◽  
Mathias Vuille ◽  
...  
Keyword(s):  
South America ◽  
North Atlantic ◽  
South American ◽  
Atmospheric Methane ◽  
Monsoon Precipitation ◽  
Abrupt Increase ◽  
South American Monsoon ◽  
Tropical Precipitation ◽  
The North ◽  
The North Atlantic

Heinrich Stadials significantly affected tropical precipitation through changes in the interhemispheric temperature gradient as a result of abrupt cooling in the North Atlantic. Here, we focus on changes in South American monsoon precipitation during Heinrich Stadials using a suite of speleothem records covering the last 85 ky B.P. from eastern South America. We document the response of South American monsoon precipitation to episodes of extensive iceberg discharge, which is distinct from the response to the cooling episodes that precede the main phase of ice-rafted detritus deposition. Our results demonstrate that iceberg discharge in the western subtropical North Atlantic led to an abrupt increase in monsoon precipitation over eastern South America. Our findings of an enhanced Southern Hemisphere monsoon, coeval with the iceberg discharge into the North Atlantic, are consistent with the observed abrupt increase in atmospheric methane concentrations during Heinrich Stadials.

scholarly journals Assessment of Seasonal Soil Moisture Forecasts over Southern South America with Emphasis on Dry and Wet Events

2017 ◽  
Vol 18 (8) ◽  
pp. 2297-2311 ◽  
Author(s):  
Pablo C. Spennemann ◽  
Juan A. Rivera ◽  
Marisol Osman ◽  
A. Celeste Saulo ◽  
Olga C. Penalba
Keyword(s):  
Soil Moisture ◽  
South America ◽  
Standardized Precipitation Index ◽  
Added Value ◽  
Lead Times ◽  
Severe Drought ◽  
Drought Event ◽  
Southern South America ◽  
Large Populations ◽  
Dry Conditions

Abstract The importance of forecasting extreme wet and dry conditions from weeks to months in advance relies on the need to prevent considerable socioeconomic losses, mainly in regions of large populations and where agriculture is a key value for the economies, such as southern South America (SSA). To improve the understanding of the performance and uncertainties of seasonal soil moisture and precipitation forecasts over SSA, this study aims to 1) perform a general assessment of the Climate Forecast System, version 2 (CFSv2), soil moisture and precipitation forecasts against observations and soil moisture simulations based on GLDAS, version 2.0; 2) evaluate the ability of CFSv2 to represent wet and dry events through the forecasted standardized precipitation index (SPI) and standardized soil moisture anomalies (SSMA); and 3) analyze the capability of a statistical methodology (merging observations and forecasts) in representing a severe drought event. Results show that both SPI and SSMA forecast skill are regionally and seasonally dependent. In general, a fast degradation of the forecasts skill is observed as the lead time increases, resulting in almost no added value with regard to climatology at lead times longer than 3 months. Additionally, a better performance of the SSMA forecasts is observed compared to SPI calculated using three months of precipitation (SPI3), with a higher skill for dry events against wet events. The CFSv2 forecasts are able to represent the spatial patterns of the 2008/09 severe drought event, although it shows crucial limitations regarding the identification of drought onset, duration, severity, and demise, considering both meteorological (SPI) and agricultural (SSMA) drought conditions.

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