Resumen

DIAZ, Diana  y  VILLEGAS, Nancy. Wavelet coherence between ENSO indices and two precipitation databases for the Andes region of Colombia. Atmósfera [online]. 2022, vol.35, n.2, pp.237-271.  Epub 16-Mayo-2022. ISSN 0187-6236.  https://doi.org/10.20937/atm.52890.

The influence of El Niño Southern Oscillation (ENSO) on Colombia’s hydrological variables has been shown in different studies. Most of the methodologies implemented have identified linear relationships and have associated the warm (cold) phase called El Niño (La Niña) with negative (positive) rainfall and streamflow anomalies. One of the most adverse impacts is the reduction in water supply during the warm phase. One aim of this study is to explore nonlinear correlations between ENSO and precipitation and the second is to identify which indices will enable improving the predictability of hydro-climatological variables. Wavelet coherence analysis is performed for monthly precipitation time series and ENSO indices from 1981-2016. Results show that ENSO events influence precipitation as periods of rainfall deficit or excess. Also, precipi tation organized in the 2-8-year scales explain most of their variance. The most significant sectors are those that cover El Niño events when impacts on precipitation tend to be greater. In contrast, sectors are smaller when La Niña episodes occur. Results also allowed to identify that Niño 3, Niño 3.4, ONI, and BEST indices can be good predictors for specific regions. Intercomparison of two datasets allows to establish the feasibility of using satellite data in regions with scarce information, but fewer anomalies are reported from the satellite data. While the coherence structure is similar in both datasets, for periods between 36 and 48 months, there were discrepancies of π /4 in the phase difference, that is, between 3 and 6 months of difference in lags calculated with each database.

Palabras llave : Precipitation variability; climate ENSO indices; continuous wavelet transform; CHIRPS.

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