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The Influence of Recurrent Modes of Climate Variability on the Occurrence of Monthly Temperature Extremes Over South America
- Source :
- Journal of Geophysical Research: Atmospheres. 122:10-10,311
- Publication Year :
- 2017
- Publisher :
- American Geophysical Union (AGU), 2017.
-
Abstract
- The associations between extreme temperature months and four prominent modes of recurrent climate variability are examined over South America. Associations are computed as the percent of extreme temperature months concurrent with the upper and lower quartiles of the El Nino–Southern Oscillation (ENSO), the Atlantic Nino, the Pacific Decadal Oscillation (PDO), and the Southern Annular Mode (SAM) index distributions, stratified by season. The relationship is strongest for ENSO, with nearly every extreme temperature month concurrent with the upper or lower quartiles of its distribution in portions of northwestern South America during some seasons. The likelihood of extreme warm temperatures is enhanced over parts of northern South America when the Atlantic Nino index is in the upper quartile, while cold extremes are often association with the lowest quartile. Concurrent precipitation anomalies may contribute to these relations. The PDO shows weak associations during December, January, and February, while in June, July, and August its relationship with extreme warm temperatures closely matches that of ENSO. This may be due to the positive relationship between the PDO and ENSO, rather than the PDO acting as an independent physical mechanism. Over Patagonia, the SAM is highly influential during spring and fall, with warm and cold extremes being associated with positive and negative phases of the SAM, respectively. Composites of sea level pressure anomalies for extreme temperature months over Patagonia suggest an important role of local synoptic scale weather variability in addition to a favorable SAM for the occurrence of these extremes.
- Subjects :
- Atmospheric Science
010504 meteorology & atmospheric sciences
0208 environmental biotechnology
02 engineering and technology
01 natural sciences
Extreme temperature
020801 environmental engineering
Geophysics
Geography
El Niño Southern Oscillation
Quartile
El Niño
Space and Planetary Science
Synoptic scale meteorology
Climatology
Earth and Planetary Sciences (miscellaneous)
Positive relationship
Precipitation
Pacific decadal oscillation
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 2169897X
- Volume :
- 122
- Database :
- OpenAIRE
- Journal :
- Journal of Geophysical Research: Atmospheres
- Accession number :
- edsair.doi...........f8dd2144062b10df33d3cf4c9a6ce69b