Influence of the Madden Julian Oscillation on precipitation and surface air temperature in South America

Details

• Journal Title:
  Climate Dynamics
• Personal Author:
  Alvarez, Mariano S. ; Vera, C. S. ; Kiladis, G. N. ; Liebmann, B.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; PSL (Physical Sciences Laboratory) ; ESRL (Earth System Research Laboratory)
• Description:
  The regional influence of the Madden-Julian oscillation (MJO) on South America is described. Maps of probability of weekly-averaged rainfall exceeding the upper tercile were computed for all seasons and related statistically with the phase of the MJO as characterized by the Wheeler-Hendon real-time multivariate MJO (RMM) index and with the OLR MJO Index. The accompanying surface air temperature and circulation anomalies were also calculated. The influence of the MJO on regional scales along with their marked seasonal variations was documented. During December-February when the South American monsoon system is active, chances of enhanced rainfall are observed in southeastern South America (SESA) region mainly during RMM phases 3 and 4, accompanied by cold anomalies in the extratropics, while enhanced rainfall in the South Atlantic Convergence Zone (SACZ) region is observed in phases 8 and 1. The SESA (SACZ) signal is characterized by upper-level convergence (divergence) over tropical South America and a cyclonic (anticyclonic) anomaly near the southern tip of the continent. Impacts during March-May are similar, but attenuated in the extratropics. Conversely, in June-November, reduced rainfall and cold anomalies are observed near the coast of the SACZ region during phases 4 and 5, favored by upper-level convergence over tropical South America and an anticyclonic anomaly over southern South America. In September-November, enhanced rainfall and upper-level divergence are observed in the SACZ region during phases 7 and 8. These signals are generated primarily through the propagation of Rossby wave energy generated in the region of anomalous heating associated with the MJO.
• Source:
  Climate Dynamics, 46(1-2), 245-262.
• DOI:
  https://doi.org/10.1007/s00382-015-2581-6
• Document Type:
  Journal Article
• Rights Information:
  Accepted Manuscript
• Rights Statement:
  The NOAA IR provides access to this content under the authority of the government's retained license to distribute publications and data resulting from federal funding. While users may legally access this content, the copyright owners retain rights that govern the reproduction, redistribution, and re-use of this work. The user is solely responsible for complying with applicable copyright law.
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:2e0f47a93bfaf4b75a37a7cf5a612e4abe7c987e1bb1167925bd48cea7dee86cf120789a934d3c034b903208a64b859002102fc9cb58621038656c7f51d298bf
• Download URL:
  https://repository.library.noaa.gov/view/noaa/14494/noaa_14494_DS1.pdf
• File Type:
  [PDF - 2.04 MB ]