scholarly journals Daily Precipitation Statistics for South America: An Intercomparison between NCEP Reanalyses and Observations

2011 ◽  
Vol 12 (1) ◽  
pp. 101-117 ◽  
Author(s):  
Viviane B. S. Silva ◽  
Vernon E. Kousky ◽  
R. Wayne Higgins
Keyword(s):  
South America ◽  
Large Scale ◽  
Atmospheric Model ◽  
Northeastern Brazil ◽  
South American ◽  
The South ◽  
Wet Season ◽  
Central Brazil ◽  
Monsoon System ◽  
Dry Bias

Abstract In this study, the authors document the extent to which the precipitation statistics of the new CFS reanalysis (CFSR) represent an improvement over the earlier reanalyses: the NCEP–NCAR reanalysis (R1) and the NCEP–DOE Second Atmospheric Model Intercomparison Project (AMIP-II) reanalysis (R2). An intercomparison between the CFSR, R1, R2, and observations over South America was made for the period 1979–2006. The CFSR shows notable improvements in the large-scale precipitation patterns compared with the previous reanalyses (R1 and R2). In spite of these improvements, the CFSR has substantial biases in intensity and frequency of occurrence of rainfall events. Over west-central Brazil, the core region of the South American monsoon system (SAMS), the CFSR displays a dry bias during the onset phase of the SAMS wet season and a wet bias during the peak and decay phases of the SAMS wet season. The CFSR also displays a dry bias along the South American coast near the mouth of the Amazon and along the east coast of northeastern Brazil. A wet bias exists in all seasons over southeast Brazil and over the Andes Mountains.

scholarly journals Projected End-of-Century Changes in the South American Monsoon in the CESM Large Ensemble

2020 ◽  
Vol 33 (18) ◽  
pp. 7859-7874
Author(s):  
Ana Claudia Thome Sena ◽  
Gudrun Magnusdottir
Keyword(s):  
South America ◽  
South Atlantic ◽  
Northeastern Brazil ◽  
Southeastern Brazil ◽  
South American ◽  
The South ◽  
Wet Season ◽  
Large Ensemble ◽  
South American Monsoon ◽  
The Mean

AbstractProjected changes in the South American monsoon system by the end of the twenty-first century are analyzed using the Community Earth System Model Large Ensemble (CESM-LENS). The wet season is shorter in LENS when compared to observations, with the mean onset occurring 19 days later and the mean retreat date 21 days earlier in the season. Despite a precipitation bias, the seasonality of rainfall over South America is reproduced in LENS, as well as the main circulation features associated with the development of the South American monsoon. Both the onset and retreat of the wet season over South America are delayed in the future compared to current climate by 3 and 7 days, respectively, with a slightly longer wet season. Central and southeastern Brazil are projected to get wetter as a result of moisture convergence from the strengthening of the South Atlantic low-level jet and a weaker South Atlantic subtropical high. The Amazon is projected to get drier by the end of the century, negatively affecting rain forest productivity. During the wet season, an increase in the frequency and intensity of extreme precipitation events is found over most of South America, and especially over northeastern and southern Brazil and La Plata. Meanwhile, during the dry season an increase in the maximum number of consecutive dry days is found over northeastern Brazil and the northern Amazon.

Precipitation Characteristics of the South American Monsoon System Derived from Multiple Datasets

2012 ◽  
Vol 25 (13) ◽  
pp. 4600-4620 ◽  
Author(s):  
Leila M. V. Carvalho ◽  
Charles Jones ◽  
Adolfo N. D. Posadas ◽  
Roberto Quiroz ◽  
Bodo Bookhagen ◽  
...  
Keyword(s):  
South America ◽  
Large Scale ◽  
Austral Summer ◽  
Global Precipitation Climatology Project ◽  
South American ◽  
The South ◽  
Frequency Distributions ◽  
South American Monsoon ◽  
Monsoon System ◽  
South American Monsoon System

Abstract The South American monsoon system (SAMS) is the most important climatic feature in South America and is characterized by pronounced seasonality in precipitation during the austral summer. This study compares several statistical properties of daily gridded precipitation from different data (1998–2008): 1) Physical Sciences Division (PSD), Earth System Research Laboratory [1.0° and 2.5° latitude (lat)/longitude (lon)]; 2) Global Precipitation Climatology Project (GPCP; 1° lat/lon); 3) Climate Prediction Center (CPC) unified gauge (CPC-uni) (0.5° lat/lon); 4) NCEP Climate Forecast System Reanalysis (CFSR) (0.5° lat/lon); 5) NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis (0.5° lat/0.3° lon); and 6) Tropical Rainfall Measuring Mission (TRMM) 3B42 V6 data (0.25° lat/lon). The same statistical analyses are applied to data in 1) a common 2.5° lat/lon grid and 2) in the original resolutions of the datasets. All datasets consistently represent the large-scale patterns of the SAMS. The onset, demise, and duration of SAMS are consistent among PSD, GPCP, CPC-uni, and TRMM datasets, whereas CFSR and MERRA seem to have problems in capturing the correct timing of SAMS. Spectral analyses show that intraseasonal variance is somewhat similar in the six datasets. Moreover, differences in spatial patterns of mean precipitation are small among PSD, GPCP, CPC-uni, and TRMM data, while some discrepancies are found in CFSR and MERRA relative to the other datasets. Fitting of gamma frequency distributions to daily precipitation shows differences in the parameters that characterize the shape, scale, and tails of the frequency distributions. This suggests that significant uncertainties exist in the characterization of extreme precipitation, an issue that is highly important in the context of climate variability and change in South America.

scholarly journals Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems—New Perspectives using the SISAL Database

Quaternary ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 6 ◽  
Author(s):  
Michael Deininger ◽  
Brittany Marie Ward ◽  
Valdir F. Novello ◽  
Francisco W. Cruz
Keyword(s):  
South America ◽  
Late Quaternary ◽  
Precipitation Amount ◽  
Ice Age ◽  
Convergence Zone ◽  
South American ◽  
The South ◽  
South American Monsoon ◽  
Monsoon System ◽  
South American Monsoon System

Here we present an overview of speleothem δ18O records from South America, most of which are available in the Speleothem Isotopes Synthesis and Analysis (SISAL_v1) database. South American tropical and subtropical speleothem δ18O time series are primarily interpreted to reflect changes in precipitation amount, the amount effect, and consequently history of convection intensity variability of convergence zones such as the Intertropical Convergence Zone (ITCZ) and the South America Monsoon System (SAMS). We investigate past hydroclimate scenarios in South America related to the South American Monsoon System in three different time periods: Late Pleistocene, Holocene, and the last two millennia. Precession driven summertime insolation is the main driver of convective variability over the continent during the last 120 kyrs (from present day to 120 kyrs BP), including the Holocene. However, there is a dipole between speleothem δ18O records from western and eastern South America. Records located in the central region of Brazil are weakly affected by insolation-driven variability, and instead are more susceptible to the variability associated with the South Atlantic Convergence Zone (SACZ). Cold episodic events in the Northern Hemisphere, such as Heinrich and Bond Events, and the Little Ice Age, increase the convective activity of the SAMS, resulting in increased precipitation amount in South America.

A Quaternary record of the big-eyed bat Chiroderma villosum (Chiroptera: Phyllostomidae) with a revised lower molar terminology

Mammalia ◽  
2018 ◽  
Vol 82 (4) ◽  
pp. 393-399 ◽  
Author(s):  
Guilherme S.T. Garbino ◽  
Valéria da C. Tavares
Keyword(s):  
South America ◽  
Late Quaternary ◽  
Northeastern Brazil ◽  
South American ◽  
The South ◽  
Historical Interpretation ◽  
Left Mandible ◽  
Lower Molar

Abstract We report the first Quaternary record of the big-eyed bat Chiroderma villosum from South America based on a left mandible fragment collected in the Gruta dos Brejões, late Quaternary of northeastern Brazil. This material has been identified over the course of our revisionary work of the genus Chiroderma, including all species distributed in South America (Chiroderma doriae, Chiroderma salvini, Chiroderma trinitatum, Chiroderma villosum and Chiroderma vizottoi). Our results revealed that several characters of the second lower molar (m2), and of the posterior mandible may be used to identify and to diagnose the South American Chiroderma. We also revisited the historical interpretation of homologies of the lower molar cusps of Chiroderma, and propose a revised molar cusp terminology.

scholarly journals A mid-Holocene climate reconstruction for eastern South America

2013 ◽  
Vol 9 (5) ◽  
pp. 2117-2133 ◽  
Author(s):  
L. F. Prado ◽  
I. Wainer ◽  
C. M. Chiessi ◽  
M.-P. Ledru ◽  
B. Turcq
Keyword(s):  
South America ◽  
Late Holocene ◽  
Austral Summer ◽  
South Atlantic Convergence Zone ◽  
Northeastern Brazil ◽  
South American ◽  
The South ◽  
Holocene Climate ◽  
Sea Temperature ◽  
Summer Insolation

Abstract. The mid-Holocene (6000 calibrated years before present) is a key period in palaeoclimatology because incoming summer insolation was lower than during the late Holocene in the Southern Hemisphere, whereas the opposite happened in the Northern Hemisphere. However, the effects of the decreased austral summer insolation over South American climate have been poorly discussed by palaeodata syntheses. In addition, only a few of the regional studies have characterised the mid-Holocene climate in South America through a multiproxy approach. Here, we present a multiproxy compilation of mid-Holocene palaeoclimate data for eastern South America. We compiled 120 palaeoclimatological datasets, which were published in 84 different papers. The palaeodata analysed here suggest a water deficit scenario in the majority of eastern South America during the mid-Holocene if compared to the late Holocene, with the exception of northeastern Brazil. Low mid-Holocene austral summer insolation caused a reduced land–sea temperature contrast and hence a weakened South American monsoon system circulation. This scenario is represented by a decrease in precipitation over the South Atlantic Convergence Zone area, saltier conditions along the South American continental margin, and lower lake levels.

scholarly journals Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems – New Perspectives Using the SISAL Database

2018 ◽  
Author(s):  
Michael Deininger ◽  
Brittany Marie Ward ◽  
Valdir F. Novello ◽  
Francisco W. Cruz
Keyword(s):  
South America ◽  
Time Scales ◽  
Late Pleistocene ◽  
Convergence Zone ◽  
South American ◽  
The South ◽  
The Holocene ◽  
South American Monsoon ◽  
Monsoon System ◽  
South American Monsoon System

Here we present an overview of speleothem δ18O records from South America, which mostly are available in the Speleothem Isotopes Synthesis and Analysis (SISAL_v1) database. South American tropical and subtropical δ18O time series are primarily interpreted as being driven by the amount effect and, consequently show the past history of the convection intensity of convergence zones such as the Intertropical Convergence Zone and the South America Monsoon System. We investigate past hydroclimate scenarios in South America related to the South American Monsoon System in three different time scales: Late Pleistocene, Holocene and the last two millennia. The precession driven insolation is the main driver of convective variability over the continent during the last 250 kyrs, including the Holocene period. However a dipole is observed between the west and east portions of the continent. Records located in the central region of Brazil appear to be weakly affected by insolation driven variability and more susceptible to the South Atlantic Convergence Zone. Cold episodic events in Northern Hemisphere increase the activity of the South American Monsoon System on all time scales, in turn increasing rainfall amounts in South America, as was documented during Heinrich events in the late Pleistocene and Bond events in the Holocene, as well as during the Little Ice Age.

Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s.l.—Dennstaedtiaceae), based on morphology and geography

Phytotaxa ◽  
2018 ◽  
Vol 333 (1) ◽  
pp. 22 ◽  
Author(s):  
PEDRO B. SCHWARTSBURD ◽  
AGUSTINA YAÑEZ ◽  
JEFFERSON PRADO
Keyword(s):  
South America ◽  
The Other ◽  
Northeastern Brazil ◽  
Putative Hybrid ◽  
South American ◽  
The South ◽  
The Third ◽  
The Andes ◽  
Northern South America ◽  
Formal Recognition

Based on the morphological study of ca. 470 specimens and geographical studies, we here propose the recognition of six morphotypes within the South American Pteridium esculentum (= P. arachnoideum s.l., or P. aquilinum var. arachnoideum sensu Tryon, or P. esculentum subsp. arachnoideum sensu Thomson). Three of them are widely distributed and well-defined, and we regard them as subspecies of P. esculentum: P. esculentum subsp. arachnoideum s. str., P. esculentum subsp. campestre, comb. et stat. nov., and P. esculentum subsp. gryphus. The other three are more rare. One of these is a pedomorphic form of P. esculentum subsp. arachnoideum, which we name as P. esculentum subsp. arachnoideum var. paedomorficum, nom. nov. The other is a glabrous form of P. esculentum subsp. gryphus, which we name P. esculentum subsp. gryphus var. harpianum, var. nov. The third is a putative hybrid between P. esculentum subsp. arachnoideum and P. esculentum subsp. campestre. All six taxa are keyed, described, illustrated, mapped, and discussed. Pteridium esculentum subsp. arachnoideum s. str. forms an arc of distribution from eastern, to southern, to western South America (but not occurring west of the Andes); Pteridium esculentum subsp. campestre forms an arc of distribution from northeastern Brazil to northern South America (not occurring west of the Andes either); and P. esculentum subsp. gryphus forms an arc of distribution from western to northern South America (occurring also west of the Andes and in Galapagos). This one is morphologically more similar to the Australasian P. esculentum subsp. esculentum.

scholarly journals The Influence of Orbital Forcing of Tropical Insolation on the Climate and Isotopic Composition of Precipitation in South America

2015 ◽  
Vol 28 (12) ◽  
pp. 4841-4862 ◽  
Author(s):  
Xiaojuan Liu ◽  
David S. Battisti
Keyword(s):  
South America ◽  
Isotopic Composition ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Northeastern Brazil ◽  
Convergence Zone ◽  
South American ◽  
The South ◽  
Northern Andes

Abstract The δ18O of calcite (δ18Oc) in speleothems from South America is fairly well correlated with austral summer [December–February (DJF)] insolation, indicating the role of orbitally paced changes in insolation in changing the climate of South America. Using an isotope-enabled atmospheric general circulation model (ECHAM4.6) coupled to a slab ocean model, the authors study how orbitally paced variations in insolation change climate and the isotopic composition of precipitation (δ18Op) of South America. Compared with times of high summertime insolation, times of low insolation feature (i) a decrease in precipitation inland of tropical South America as a result of an anomalous cooling of the South American continent and hence a weakening of the South American summer monsoon and (ii) an increase in precipitation in eastern Brazil that is associated with the intensification and southward movement of the Atlantic intertropical convergence zone, which is caused by the strengthening of African winter monsoon that is induced by the anomalous cooling of northern Africa. Finally, reduced DJF insolation over southern Africa causes cooling and the generation of a tropically trapped Rossby wave that intensifies and shifts the South Atlantic convergence zone northward. In times of low insolation, δ18Op increases in the northern Andes and decreases in northeastern Brazil, consistent with the pattern of δ18Oc changes seen in speleothems. Further analysis shows that the decrease in δ18Op in northeastern Brazil is due to change in the intensity of precipitation, while the increase in the northern Andes reflects a change in the seasonality of precipitation and in the isotopic composition of vapor that forms the condensates.

scholarly journals Climate Change in the South American Monsoon System: Present Climate and CMIP5 Projections

2013 ◽  
Vol 26 (17) ◽  
pp. 6660-6678 ◽  
Author(s):  
Charles Jones ◽  
Leila M. V. Carvalho
Keyword(s):  
Climate Change ◽  
South America ◽  
South American ◽  
Cmip5 Model ◽  
The South ◽  
Model Simulations ◽  
South American Monsoon ◽  
High Emission ◽  
Monsoon System ◽  
South American Monsoon System

Abstract The South American monsoon system (SAMS) is the most important climatic feature in South America. This study focuses on the large-scale characteristics of the SAMS: seasonal amplitudes, onset and demise dates, and durations. Changes in the SAMS are investigated with the gridded precipitation, Climate Forecast System Reanalysis (CFSR), and the fifth phase of the Coupled Model Intercomparison Project (CMIP5) simulations for two scenarios [“historical” and high-emission representative concentration pathways (rcp8.5)]. Qualitative comparisons with a previous study indicate that some CMIP5 models have significantly improved their representation of the SAMS relative to their CMIP3 versions. Some models exhibit persistent deficiencies in simulating the SAMS. CMIP5 model simulations for the historical experiment show signals of climate change in South America. While the observational data show trends, the period used is too short for final conclusions concerning climate change. Future changes in the SAMS are analyzed with six CMIP5 model simulations of the rcp8.5 high-emission scenario. Most of the simulations show significant increases in seasonal amplitudes, early onsets, late demises, and durations of the SAMS. The simulations for this scenario project a 30% increase in the amplitude from the current level by 2045–50. In addition, the rcp8.5 scenario projects an ensemble mean decrease of 14 days in the onset and 17-day increase in the demise date of the SAMS by 2045–50. The results additionally indicate lack of spatial agreement in model projections of changes in total wet-season precipitation over South America during 2070–2100. The most consistent CMIP5 projections analyzed here are the increase in the total monsoon precipitation over southern Brazil, Uruguay, and northern Argentina.

scholarly journals The South American Monsoon Variability over the Last Millennium in CMIP5/PMIP3 simulations

2015 ◽  
Vol 11 (6) ◽  
pp. 5651-5681 ◽  
Author(s):  
M. Rojas ◽  
P. A. Arias ◽  
V. Flores-Aqueveque ◽  
A. Seth ◽  
M. Vuille
Keyword(s):  
South America ◽  
Large Scale ◽  
Model Simulation ◽  
Ice Age ◽  
South American ◽  
Last Millennium ◽  
The South ◽  
South American Monsoon ◽  
The Past ◽  
Intercomparison Project

Abstract. In this paper we assess South American Monsoon System (SAMS) variability throughout the Last Millennium as depicted by the Coupled Modelling Intercomparison Project version 5/Paleo Modelling Intercomparison Project version 3 (CMIP5/PMIP3) simulations. High-resolution proxy records for the South American monsoon over this period show a coherent regional picture of a weak monsoon during the Medieval Climate Anomaly period and a stronger monsoon during the Little Ice Age (LIA). Due to the small forcing during the past 1000 years, CMIP5/PMIP3 model simulations do not show very strong temperature anomalies over these two specific periods, which in turn do not translate into clear precipitation anomalies, as suggested by rainfall reconstructions in South America. However, with an ad-hoc definition of these two periods for each model simulation, several coherent large-scale atmospheric circulation anomalies were identified. The models feature a stronger Monsoon during the LIA associated with: (i) an enhancement of the rising motion in the SAMS domain in austral summer, (ii) a stronger monsoon-related upper-troposphere anticyclone, (iii) activation of the South American dipole, which results to a certain extent in a poleward shift in the South Atlantic Convergence Zone and (iv) a weaker upper-level sub tropical jet over South America, this providing important insights into the mechanisms of these climate anomalies over South America during the past millennium.

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