Pacific decadal variability and decadal ENSO amplitude modulation

Abstract

[1] Connections between Pacific decadal variability ( PDV) and low-frequency modulation of El Nino and Southern Oscillation (ENSO) amplitude are analyzed using observed sea surface temperature (SST) during 1900 - 2001. The variability of the first two Empirical Orthogonal Functions (EOFs) of PDV, i.e., the PDV1 and PDV2, are compared to decadal variations of ENSO amplitude. The PDV1, which is called the Pacific decadal oscillation or decadal ENSO-like variability, is not related to the modulation of ENSO amplitude and is not a residual associated with periods of either more or less active ENSO. However, there are low-frequency changes in the Pacific mean state forced by changes in the ENSO statistics. The variability of PDV2 is associated with decadal modulation in ENSO amplitude.