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Probabilistic Rainfall Anomalias in Southern Brazil Associated with Enso
| Content Provider | Semantic Scholar |
|---|---|
| Author | Sansigolo, Clóvis Angeli |
| Copyright Year | 2006 |
| Abstract | ENSO extreme events (El Niño / La Nina) are associated with climate extremes over many regions of the globe (Ropelewski and Halpert, 1987, 89, 96) and Kiladis and Diaz, 1989). Over Southern Brazil, Grimm et al. (1998) and Diaz et al. (1998) verified, using different methods (composites and and canonical correlations), that El Niño and La Niña events are respectively associated with below and above-normal rainfall in Spring. Composites of climate anomalies observed during past ENSO events provide useful information on the typical ENSO impact (Kiladis and Diaz, 1998), but the relationships between ENSO and the expected climatic anomalies is not straightforward. For the same ENSO SST structure and magnitude, the inherent atmosphere unpredictability would lead to different climatic anomalies for each event (Hoerling et al, 1997). The non-linear interactions with SST anomalies in the other oceans and the existence of inter-events differences will increase the uncertainties on the expected climatic anomalies (Mason and Goddard, 2001). Correlations and regressions are the methods commonly used for composite analyses They describe the intensity and shape of the linear teleconnections between ENSO and climate anomalies. However, in some regions, the ENSOclimate relationships is asymmetric between El Niño and La Niña events, and varies in strength during the year (Ropelewski and Halpert, 1996). In addition, the correlation coefficients are sensible to the assumption of data normality, so, inappropriate to describe the ENSO-rainfall strength signal in areas with highly skewed rainfall distributions. Given the limitations of composite and linear measures of ENSO influences for forecasting future impacts, it is of value to estimate the probabilities of climate anomalies conditional upon the phase of ENSO (Roplewski and Halpert, 1996, Mason and Goddard, 2001). A simple and robust alternative approach is to use contingency tables that provide a measure for identifying the influence of an independent variable (ENSO) on the probability of a predefined climate event occurring (eg. given rainfall tercile). |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://mtc-m16b.sid.inpe.br/col/cptec.inpe.br/adm_conf/2005/10.11.13.56/doc/1359-1364.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
