scholarly journals A Multiscale Reexamination of the Pacific–South American Pattern

2017 ◽  
Vol 145 (1) ◽  
pp. 379-402 ◽  
Author(s):  
Terence J. O’Kane ◽  
Didier P. Monselesan ◽  
James S. Risbey
Keyword(s):  
Time Scales ◽  
Wave Train ◽  
Hadley Circulation ◽  
South American ◽  
Tropical Forcing ◽  
Tropical Variability ◽  
Higher Order Modes ◽  
The Pacific ◽  
Total Variability

Abstract The authors undertake a multiscale spectral reexamination of the variability of the Pacific–South American (PSA) pattern and the mechanisms by which this variability occurs. Time scales from synoptic to interannual are investigated, focusing on the means by which tropical variability is communicated to the midlatitudes and on in situ forcing within the midlatitude waveguides. Particular interest is paid to what fraction of the total variability associated with the PSA, occurring on interannual time scales, is attributable to tropical forcing relative to that occurring on synoptic and intraseasonal time scales via internal waveguide dynamics. In general, it is found that the eastward-propagating wave train pattern typically associated with the PSA manifests across time scales from synoptic to interannual, with the majority of the variability occurring on synoptic-to-intraseasonal time scales largely independent of tropical convection. It is found that the small fraction of the total variance with a tropical signal occurs via the zonal component of the thermal wind modulating both the subtropical and polar jets. The respective roles of the Hadley circulation and stationary Rossby wave sources are also examined. Further, a PSA-like mode is identified in terms of the slow components of higher-order modes of tropospheric geopotential height. This study reestablishes the multiscale nonlinear nature of the PSA modes arising largely as a manifestation of internal midlatitude waveguide dynamics and local disturbances.

scholarly journals Intraseasonal variability of wind waves in the western South Atlantic: the role of cyclones and the Pacific South-American pattern

2021 ◽  
Author(s):  
Dalton Kei Sasaki ◽  
Carolina Barnez Gramcianinov ◽  
Belmiro Castro ◽  
Marcelo Dottori
Keyword(s):  
Time Scales ◽  
Spatial Patterns ◽  
Extreme Values ◽  
Wind Waves ◽  
Storm Track ◽  
South Atlantic ◽  
Extratropical Cyclones ◽  
South American ◽  
The Pacific ◽  
Cyclone Genesis

Abstract. Extratropical cyclones are known to generate extreme significant wave height (swh) values in the western South Atlantic (wSA), which are highly influenced by intraseasonal scales. This work aims to investigate the importance of intraseasonal time scales (30–180 days) in the regional wave climate and its atmospheric forcing. The variability is explained by analyzing the storm track modulation due to westerlies winds. These winds present time-scales and spatial patterns compatible with the intraseasonal component of the Pacific South–American (PSA) patterns. The analysis are made using ECMWF’s ERA5 from 1979 to 2019 and a database of extratropical cyclones based on the same reanalysis. Empirical orthogonal function (EOF) analysis of the 10 m zonal wind and swh are used to assess the westerlies and waves regime in the wSA. The EOF1 of u10 presented a core centred at 45° W and 40° S, while the EOF2 is represented by two cores organized into a see-saw pattern with a center between 30° S–40° S and another to the south of 40° S. Composites of cyclone genesis and track densities, and swh fields were calculated based on the phases of both EOFs. In short, EOF phases presenting cores with a positive (negative) u10 anomaly provides a favorable (unfavorable) environment for cyclone genesis and track densities and, therefore, positive (negative) swh anomalies. The modulation of the cyclones track are significant for extreme values of the swh. The spatial patterns of the EOFs of u10 are physically and statistically consistent with 200 hPa and 850 hPa geopotential height signals from the Pacific, indicating the importance of the remote influence of the PSA patterns over the wSA.

scholarly journals Genetic diversity and kinship relationships in one of the largest South American fur seal ( Arctocephalus australis ) populations of the Pacific Ocean

2021 ◽  
Author(s):  
Josefina Gutiérrez ◽  
Mauricio Seguel ◽  
Pablo Saenz‐Agudelo ◽  
Gerardo Acosta‐Jamett ◽  
Claudio Verdugo
Keyword(s):  
Genetic Diversity ◽  
Pacific Ocean ◽  
South American ◽  
The Pacific ◽  
Fur Seal ◽  
The Pacific Ocean

scholarly journals Intercomparison of Global Sea Surface Salinity from Multiple Datasets over 2011–2018

2021 ◽  
Vol 13 (4) ◽  
pp. 811
Author(s):  
Hao Liu ◽  
Zexun Wei
Keyword(s):  
Time Scales ◽  
Correlation Coefficients ◽  
Dominant Mode ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Ocean Data Assimilation ◽  
Multiple Datasets ◽  
Different Time Scales

The variability in sea surface salinity (SSS) on different time scales plays an important role in associated oceanic or climate processes. In this study, we compare the SSS on sub-annual, annual, and interannual time scales among ten datasets, including in situ-based and satellite-based SSS products over 2011–2018. Furthermore, the dominant mode on different time scales is compared using the empirical orthogonal function (EOF). Our results show that the largest spread of ten products occurs on the sub-annual time scale. High correlation coefficients (0.6~0.95) are found in the global mean annual and interannual SSSs between individual products and the ensemble mean. Furthermore, this study shows good agreement among the ten datasets in representing the dominant mode of SSS on the annual and interannual time scales. This analysis provides information on the consistency and discrepancy of datasets to guide future use, such as improvements to ocean data assimilation and the quality of satellite-based data.

Evaluation in situ of genotoxicity and stress in South American common toad Rhinella arenarum in environments related to fluorite mine

2017 ◽  
Vol 24 (22) ◽  
pp. 18179-18187 ◽  
Author(s):  
Favio E. Pollo ◽  
Pablo R. Grenat ◽  
Zulma A. Salinas ◽  
Manuel A. Otero ◽  
Nancy E. Salas ◽  
...  
Keyword(s):  
South American ◽  
Common Toad ◽  
Rhinella Arenarum

Landscape of Migration

2020 ◽  
Author(s):  
Ben Nobbs-Thiessen
Keyword(s):  
Food Security ◽  
South American ◽  
Santa Cruz ◽  
Cash Crop ◽  
Revolutionary Movement ◽  
Export Agriculture ◽  
The Pacific ◽  
Regional Capital ◽  
Tropical Lowlands ◽  
Do So

In the wake of a 1952 revolution, leaders of Bolivia's National Revolutionary Movement (MNR) embarked on a program of internal colonization known as the "March to the East." In an impoverished country dependent on highland mining, the MNR sought to convert the nation’s vast "undeveloped" Amazonian frontier into farmland, hoping to achieve food security, territorial integrity, and demographic balance. To do so, they encouraged hundreds of thousands of Indigenous Bolivians to relocate from the "overcrowded" Andes to the tropical lowlands, but also welcomed surprising transnational migrant streams, including horse-and-buggy Mennonites from Mexico and displaced Okinawans from across the Pacific. Ben Nobbs-Thiessen details the multifaceted results of these migrations on the environment of the South American interior. As he reveals, one of the "migrants" with the greatest impact was the soybean, which Bolivia embraced as a profitable cash crop while eschewing earlier goals of food security, creating a new model for extractive export agriculture. Half a century of colonization would transform the small regional capital of Santa Cruz de la Sierra into Bolivia's largest city, and the diverging stories of Andean, Mennonite, and Okinawan migrants complicate our understandings of tradition, modernity, foreignness, and belonging in the heart of a rising agro-industrial empire.

scholarly journals Diversity of the Global Teleconnections Associated with the Madden–Julian Oscillation

2021 ◽  
Vol 34 (1) ◽  
pp. 397-414
Author(s):  
Guosen Chen
Keyword(s):  
Rossby Wave ◽  
Potential Vorticity ◽  
Wave Train ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
The Pacific ◽  
Weather And Climate ◽  
Baroclinic Model ◽  
Rossby Wave Train ◽  
Upper Level

AbstractA recent study has revealed that the Madden–Julian oscillation (MJO) during boreal winter exhibits diverse propagation patterns that consist of four archetypes: standing MJO, jumping MJO, slow eastward propagating MJO, and fast eastward propagating MJO. This study has explored the diversity of teleconnection associated with these four MJO groups. The results reveal that each MJO group corresponds to distinct global teleconnections, manifested as diverse upper-tropospheric Rossby wave train patterns. Overall, the teleconnections in the fast and slow MJO are similar to those in the canonical MJO constructed by the real-time multivariate MJO (RMM) indices, while the teleconnections in the jumping and standing MJO generally lose similarities to those in the canonical MJO. The causes of this diversity are investigated using a linearized potential vorticity equation. The various MJO tropical heating patterns in different MJO groups are the main cause of the diverse MJO teleconnections, as they induce assorted upper-level divergent flows that act as Rossby-wave sources through advecting the background potential vorticity. The variation of the Asian jet could affect the teleconnections over the Pacific jet exit region, but it plays an insignificant role in causing the diversity of global teleconnections. The numerical investigation with a linear baroclinic model shows that the teleconnections can be interpreted as linear responses to the MJO’s diabatic heating to various degrees for different MJO groups, with the fast and slow MJO having higher linear skill than the jumping and standing MJO. The results have broad implications in the MJO’s tropical–extratropical interactions and the associated impacts on global weather and climate.

Intraseasonal-to-Interannual Variability of South Indian Ocean Sea Level and Thermocline: Remote versus Local Forcing

2012 ◽  
Vol 42 (4) ◽  
pp. 602-627 ◽  
Author(s):  
Laurie L. Trenary ◽  
Weiqing Han
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Sea Level ◽  
Time Scales ◽  
Ekman Pumping ◽  
Remote Forcing ◽  
South Indian ◽  
The Pacific ◽  
The Indian Ocean ◽  
Thermocline Variability

Abstract The relative importance of local versus remote forcing on intraseasonal-to-interannual sea level and thermocline variability of the tropical south Indian Ocean (SIO) is systematically examined by performing a suite of controlled experiments using an ocean general circulation model and a linear ocean model. Particular emphasis is placed on the thermocline ridge of the Indian Ocean (TRIO; 5°–12°S, 50°–80°E). On interannual and seasonal time scales, sea level and thermocline variability within the TRIO region is primarily forced by winds over the Indian Ocean. Interannual variability is largely caused by westward propagating Rossby waves forced by Ekman pumping velocities east of the region. Seasonally, thermocline variability over the TRIO region is induced by a combination of local Ekman pumping and Rossby waves generated by winds from the east. Adjustment of the tropical SIO at both time scales generally follows linear theory and is captured by the first two baroclinic modes. Remote forcing from the Pacific via the oceanic bridge has significant influence on seasonal and interannual thermocline variability in the east basin of the SIO and weak impact on the TRIO region. On intraseasonal time scales, strong sea level and thermocline variability is found in the southeast tropical Indian Ocean, and it primarily arises from oceanic instabilities. In the TRIO region, intraseasonal sea level is relatively weak and results from Indian Ocean wind forcing. Forcing over the Pacific is the major cause for interannual variability of the Indonesian Throughflow (ITF) transport, whereas forcing over the Indian Ocean plays a larger role in determining seasonal and intraseasonal ITF variability.

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.

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