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Intraseasonal Predictions for the South American Rainfall Dipole
  • Nicolás Díaz,
  • Marcelo Barreiro,
  • Nicolás Rubido
Nicolás Díaz
Facultad de Ciencias, Universidad de la República, Uruguay, Facultad de Ciencias, Universidad de la República, Uruguay

Corresponding Author:[email protected]

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Marcelo Barreiro
Facultad de Ciencias, Universidad de la Republica, Uruguay, Facultad de Ciencias, Universidad de la Republica, Uruguay
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Nicolás Rubido
Facultad de Ciencias, Universidad de la Republica, Uruguay, Facultad de Ciencias, Universidad de la Republica, Uruguay
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Abstract

The South American rainfall Dipole (SAD) is a renowned spatial structure present in the austral summer as part of the South American monsoon system. SAD phases have been related with extreme precipitations and severe droughts across South America, but are yet to be predicted. Here, we reveal $2$ robust and reliable intraseasonal windows in the accumulated SAD index where we can forecast its quantile-state between $5$ to $15$ and $60$ to $70$ days in advance ($99\%$ significance level). These windows are insensitive to variations in the pole’s size and accumulation window, and results are consistent across different quantiles states (median, tercile, and quartile). Our method, which is based on analysing the lagged mutual information between future and present states, could be used in the development of early-warnings for extreme rainfall events. Moreover, it is unrestricted to the present analysis, being applicable to other stationary signals where a forecast is missing.
16 Nov 2020Published in Geophysical Research Letters volume 47 issue 21. 10.1029/2020GL089985