Intraseasonal variability in South America during the cold season
Intraseasonal (IS) variability in South America is analyzed during the cold season using 10-90 day bandpass filtered OLR anomalies (FOLR). IS variability explains a large percentage of variance with maximum values over Paraguay, northeastern Argentina, and southern Brazil. The leading pattern of FOL...
Guardado en:
Autores principales: | , , , |
---|---|
Formato: | JOUR |
Materias: | |
Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_09307575_v42_n11-12_p3253_Alvarez |
Aporte de: |
id |
todo:paper_09307575_v42_n11-12_p3253_Alvarez |
---|---|
record_format |
dspace |
spelling |
todo:paper_09307575_v42_n11-12_p3253_Alvarez2023-10-03T15:47:59Z Intraseasonal variability in South America during the cold season Alvarez, M.S. Vera, C.S. Kiladis, G.N. Liebmann, B. Intraseasonal variability Outgoing longwave radiation South America Winter anticyclone longwave radiation precipitation assessment Rossby wave seasonal variation Southern Hemisphere winter Antarctic Peninsula Antarctica Argentina Brazil Indian Ocean Indian Ocean (Tropical) Pacific Ocean Pacific Ocean (West) Paraguay West Antarctica Intraseasonal (IS) variability in South America is analyzed during the cold season using 10-90 day bandpass filtered OLR anomalies (FOLR). IS variability explains a large percentage of variance with maximum values over Paraguay, northeastern Argentina, and southern Brazil. The leading pattern of FOLR, as isolated from an EOF analysis, (Cold Season IS pattern, CSIS), is characterized by a monopole centered over southeastern South America (SESA) with a northwest-southeast orientation. CSIS induces a large modulation on daily precipitation anomalies, especially on both wet spells and daily precipitation extremes, which are favored during positive (wet) CSIS phases. Large-Scale OLR anomalies over the tropical Indian and west Pacific Oceans associated with CSIS exhibit eastward propagation along tropical latitudes. In addition, circulation anomalies in the Southern Hemisphere reveal the presence of an anticyclonic anomaly over Antarctica with opposite-sign anomalies in middle latitudes 10 days before CSIS is maximum as well as evidence of Rossby wave-like patterns. Positive precipitation anomalies in SESA are favored during wet CSIS phases by the intensification of a cyclonic anomaly located further south, which is discernible over the southeastern Pacific for at least 14 days before CSIS peaks. The cyclonic anomaly evolution is accompanied by the intensification of an upstream anticyclonic anomaly, which remains quasi-stationary near the Antarctica Peninsula before the CSIS peak. We speculate that the stationary behavior of the anticyclonic center is favored by a hemispheric circulation anomaly pattern resembling that associated with a negative southern annular mode phase and a wavenumber 3-4 pattern at middle latitudes. © 2013 Springer-Verlag Berlin Heidelberg. Fil:Vera, C.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_09307575_v42_n11-12_p3253_Alvarez |
institution |
Universidad de Buenos Aires |
institution_str |
I-28 |
repository_str |
R-134 |
collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
topic |
Intraseasonal variability Outgoing longwave radiation South America Winter anticyclone longwave radiation precipitation assessment Rossby wave seasonal variation Southern Hemisphere winter Antarctic Peninsula Antarctica Argentina Brazil Indian Ocean Indian Ocean (Tropical) Pacific Ocean Pacific Ocean (West) Paraguay West Antarctica |
spellingShingle |
Intraseasonal variability Outgoing longwave radiation South America Winter anticyclone longwave radiation precipitation assessment Rossby wave seasonal variation Southern Hemisphere winter Antarctic Peninsula Antarctica Argentina Brazil Indian Ocean Indian Ocean (Tropical) Pacific Ocean Pacific Ocean (West) Paraguay West Antarctica Alvarez, M.S. Vera, C.S. Kiladis, G.N. Liebmann, B. Intraseasonal variability in South America during the cold season |
topic_facet |
Intraseasonal variability Outgoing longwave radiation South America Winter anticyclone longwave radiation precipitation assessment Rossby wave seasonal variation Southern Hemisphere winter Antarctic Peninsula Antarctica Argentina Brazil Indian Ocean Indian Ocean (Tropical) Pacific Ocean Pacific Ocean (West) Paraguay West Antarctica |
description |
Intraseasonal (IS) variability in South America is analyzed during the cold season using 10-90 day bandpass filtered OLR anomalies (FOLR). IS variability explains a large percentage of variance with maximum values over Paraguay, northeastern Argentina, and southern Brazil. The leading pattern of FOLR, as isolated from an EOF analysis, (Cold Season IS pattern, CSIS), is characterized by a monopole centered over southeastern South America (SESA) with a northwest-southeast orientation. CSIS induces a large modulation on daily precipitation anomalies, especially on both wet spells and daily precipitation extremes, which are favored during positive (wet) CSIS phases. Large-Scale OLR anomalies over the tropical Indian and west Pacific Oceans associated with CSIS exhibit eastward propagation along tropical latitudes. In addition, circulation anomalies in the Southern Hemisphere reveal the presence of an anticyclonic anomaly over Antarctica with opposite-sign anomalies in middle latitudes 10 days before CSIS is maximum as well as evidence of Rossby wave-like patterns. Positive precipitation anomalies in SESA are favored during wet CSIS phases by the intensification of a cyclonic anomaly located further south, which is discernible over the southeastern Pacific for at least 14 days before CSIS peaks. The cyclonic anomaly evolution is accompanied by the intensification of an upstream anticyclonic anomaly, which remains quasi-stationary near the Antarctica Peninsula before the CSIS peak. We speculate that the stationary behavior of the anticyclonic center is favored by a hemispheric circulation anomaly pattern resembling that associated with a negative southern annular mode phase and a wavenumber 3-4 pattern at middle latitudes. © 2013 Springer-Verlag Berlin Heidelberg. |
format |
JOUR |
author |
Alvarez, M.S. Vera, C.S. Kiladis, G.N. Liebmann, B. |
author_facet |
Alvarez, M.S. Vera, C.S. Kiladis, G.N. Liebmann, B. |
author_sort |
Alvarez, M.S. |
title |
Intraseasonal variability in South America during the cold season |
title_short |
Intraseasonal variability in South America during the cold season |
title_full |
Intraseasonal variability in South America during the cold season |
title_fullStr |
Intraseasonal variability in South America during the cold season |
title_full_unstemmed |
Intraseasonal variability in South America during the cold season |
title_sort |
intraseasonal variability in south america during the cold season |
url |
http://hdl.handle.net/20.500.12110/paper_09307575_v42_n11-12_p3253_Alvarez |
work_keys_str_mv |
AT alvarezms intraseasonalvariabilityinsouthamericaduringthecoldseason AT veracs intraseasonalvariabilityinsouthamericaduringthecoldseason AT kiladisgn intraseasonalvariabilityinsouthamericaduringthecoldseason AT liebmannb intraseasonalvariabilityinsouthamericaduringthecoldseason |
_version_ |
1782025457699389440 |