Stress modeling in the Andes: Constraints on the South American intraplate stress magnitudes

1994 ◽  
Vol 99 (B11) ◽  
pp. 22015-22025 ◽  
Author(s):  
Randall M. Richardson ◽  
David D. Coblentz
Keyword(s):  
South American ◽  
The South ◽  
Stress Modeling ◽  
The Andes ◽  
Intraplate Stress

scholarly journals On the Pleistocene Snow-Line Depression in the Arid Regions of the South American Andes

1971 ◽  
Vol 10 (59) ◽  
pp. 255-267
Author(s):  
Stefan L. Hastenrath
Keyword(s):  
Arid Regions ◽  
South American ◽  
The South ◽  
Temperate Latitude ◽  
The Andes ◽  
Western Cordillera ◽  
Snow Line ◽  
The Pacific ◽  
The Arid Regions ◽  
June July

AbstractField observations during a journey through the arid regions of the South American Andes in June-July 1969 are evaluated in conjunction with available air photographs and reports from adjacent regions of the High Andes. Results indicate an increase of the Pleistocene snow-line depression in the western Cordillera from about 700 m at lat. 12° S. to more than 1 500 m at lat. 30° S. The Pleistocene snow-line depression decreases from the Pacific to the Atlantic side of the Andes, but particularly strongly so on the poleward fringe of the arid region. From this geomorphic evidence it is suggested that the atmospheric circulation during the glacial period was characterized by an Equatorward displacement of the boundary between tropical easterlies and temperate-latitude westerlies.

Microsatellites and 16S sequences corroborate phenotypic evidence of trans-Andean variation in the parasitoidMicroctonus hyperodae(Hymenoptera: Braconidae)

2005 ◽  
Vol 95 (4) ◽  
pp. 289-298 ◽  
Author(s):  
L.M. Winder ◽  
C.B. Phillips ◽  
C. Lenney-Williams ◽  
R.P. Cane ◽  
K. Paterson ◽  
...  
Keyword(s):  
Andes Mountains ◽  
South American ◽  
The South ◽  
The Andes ◽  
16S Gene ◽  
Pasture Grasses ◽  
Geographical Populations ◽  
Listronotus Bonariensis ◽  
Microctonus Hyperodae ◽  
Chilean Populations

AbstractEight South American geographical populations of the parasitoidMicroctonus hyperodaeLoan were collected in South America (Argentina, Brazil, Chile and Uruguay) and released in New Zealand for biological control of the weevilListronotus bonariensis(Kuschel), a pest of pasture grasses and cereals. DNA sequencing (16S, COI, 28S, ITS1, β-tubulin), RAPD, AFLP, microsatellite, SSCP and RFLP analyses were used to seek markers for discriminating between the South American populations. All of the South American populations were more homogeneous than expected. However, variation in microsatellites and 16S gene sequences corroborated morphological, allozyme and other phenotypic evidence of trans-Andes variation between the populations. The Chilean populations were the most genetically variable, while the variation present on the eastern side of the Andes mountains was a subset of that observed in Chile.

scholarly journals Revision of the bee genus Chlerogella (Hymenoptera: Halictidae), Part IV: A new species from southwestern Colombia

2014 ◽  
pp. 1
Author(s):  
Michael S. Engel ◽  
Victor H. Gonzalez ◽  
Ismael A. Hinojosa-Díaz
Keyword(s):  
New Species ◽  
South American ◽  
The South ◽  
South American Species ◽  
The Andes ◽  
A New Species

A new species of the diverse augochlorine bee genus Chlerogella Michener (Halictinae: Augochlorini) is described and figured from southwestern Colombia.  Chlerogella anchicaya Engel, Gonzalez, & Hinojosa-Díaz, new species, is similar to C. agaylei Engel and C. materdonnae Engel, both occurring on the eastern slopes of the Andes in Ecuador.  There are also some similarities with C. eumorpha Engel from the western Andean foothills in northern Ecuador, but differences in rostral length and male terminalia can distinguish these species.  Revised couplets are provided to the South American species of Chlerogella to permit identification of the new species.

scholarly journals Observational evidences on the modulation of the South American Low Level Jet east of the Andes according the ENSO variability

2009 ◽  
Vol 27 (2) ◽  
pp. 645-657 ◽  
Author(s):  
G. A. M. Silva ◽  
T. Ambrizzi ◽  
J. A. Marengo
Keyword(s):  
South America ◽  
South American ◽  
The South ◽  
Trade Winds ◽  
La Plata ◽  
The Andes ◽  
La Plata Basin ◽  
Normal Frequency ◽  
Rainfall Anomalies ◽  
Low Level Jet

Abstract. The differences on the phase and wavelength of the quasi-stationary waves over the South America generated by El Niño (EN) and La Niña (LN) events seem to affect the daily evolution of the South American Low Level Jet east of the Andes (SALLJ). For the austral summer period of 1977–2004 the SALLJ episodes detected according to Bonner criterion 1 show normal to above-normal frequency in EN years, and in LN years the episodes show normal to below-normal frequency. During EN and LN years the SALLJ episodes were associated with positive rainfall anomalies over the La Plata Basin, but more intense during LN years. During EN years the increase in the SALLJ cases were associated to intensification of the Subtropical Jet (SJ) around 30° S and positive Sea Level Pressure (SLP) anomalies over the western equatorial Atlantic and tropical South America, particularly over central Brazil. This favored the intensification of the northeasterly trade winds over the northern continent and it channeled by the Andes mountain to the La Plata Basin region where negative SLP are found. The SALLJ cases identified during the LN events were weaker and less frequent when compared to those for EN years. In this case the SJ was weaker than in EN years and the negative SLP anomalies over the tropical continent contributed to the inversion of the northeasterly trade winds. Also a southerly flow anomaly was generated by the geostrophic balance due to the anomalous blocking over southeast Pacific and the intense cyclonic transient over the southern tip of South America. As result the warm tropical air brought by the SALLJ encounters the cold extratropical air from the southerly winds over the La Plata basin. This configuration can increase the conditional instability over the La Plata basin and may explain the more intense positive rainfall anomalies in SALLJ cases during LN years than in EN years.

scholarly journals On the Pleistocene Snow-Line Depression in the Arid Regions of the South American Andes

1971 ◽  
Vol 10 (59) ◽  
pp. 255-267 ◽  
Author(s):  
Stefan L. Hastenrath
Keyword(s):  
Arid Regions ◽  
South American ◽  
The South ◽  
Temperate Latitude ◽  
The Andes ◽  
Western Cordillera ◽  
Snow Line ◽  
The Pacific ◽  
The Arid Regions ◽  
June July

AbstractField observations during a journey through the arid regions of the South American Andes in June-July 1969 are evaluated in conjunction with available air photographs and reports from adjacent regions of the High Andes. Results indicate an increase of the Pleistocene snow-line depression in the western Cordillera from about 700 m at lat. 12° S. to more than 1 500 m at lat. 30° S. The Pleistocene snow-line depression decreases from the Pacific to the Atlantic side of the Andes, but particularly strongly so on the poleward fringe of the arid region. From this geomorphic evidence it is suggested that the atmospheric circulation during the glacial period was characterized by an Equatorward displacement of the boundary between tropical easterlies and temperate-latitude westerlies.

scholarly journals Inter-El Niño variability and its impact on the South American low-level jet east of the Andes during austral summer − two case studies

2006 ◽  
Vol 6 ◽  
pp. 283-287 ◽  
Author(s):  
G. A. M. Silva ◽  
T. Ambrizzi
Keyword(s):  
El Niño ◽  
El Nino ◽  
Austral Summer ◽  
South American ◽  
The South ◽  
Trade Winds ◽  
Low Level ◽  
The Andes ◽  
Low Level Jet ◽  
The Impact

Abstract. The impact of the maximum convection location over eastern and central Equatorial Pacific over the intensity and positioning of the South American Low-Level Jet east of the Andes (SALLJ) during the austral summer was investigated. The Bonner criteria 1 was applied to the NCEP-NCAR circulation fields during the El Niño of 1997/1998 and 2002/2003 to identify the SALLJ episodes. The composites of the atmospheric circulation over the South America during El Niño events showed that the SALLJ can be influenced by small displacements of the quasi-stationary Rossby waves position. During the strong El Niño event of 1997/1998 the SALLJ is maintained by the eastern trade winds. A low-level anomalous anticyclonic circulation over the central part of Brazil enhanced the wind in the nucleus of the jet and displaced its axis to the Northern Argentina and South of Brazil. However, the northern trade winds seem to maintain the SALLJ during the weak El Niño of 2002/2003. The jet was weaker and displaced more southeastward of Brazil than during the strong event.

Analysis of the South American intraplate stress field

1996 ◽  
Vol 101 (B4) ◽  
pp. 8643-8657 ◽  
Author(s):  
David D. Coblentz ◽  
Randall M. Richardson
Keyword(s):  
Stress Field ◽  
South American ◽  
The South ◽  
Intraplate Stress

scholarly journals Genetic diversity in the Andes: variation within and between the South American species of Oreobolus R. Br. (Cyperaceae)

Alpine Botany ◽  
2017 ◽  
Vol 127 (2) ◽  
pp. 155-170 ◽  
Author(s):  
María Camila Gómez-Gutiérrez ◽  
R. Toby Pennington ◽  
Linda E. Neaves ◽  
Richard I. Milne ◽  
Santiago Madriñán ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
South American ◽  
The South ◽  
South American Species ◽  
The Andes
Sign in / Sign up

Export Citation Format

Share Document