A Comparison of the Westerly Wind Bursts between the Positive Phase and the Negative Phase of the PDO

To understand El Niño-Southern Oscillation (ENSO) diversity under the background of the Pacific decadal oscillation (PDO) during recent decades, the characteristics of westerly wind bursts (WWBs) during the two phases of the PDO were analyzed. It was shown that, during the ENSO developing period, the El Niño evolution may be affected by stronger or more frequent WWBs in the positive PDO phase than in the negative PDO phase. The sustained effects of atmospheric dynamics on the equatorial ocean can be indicated by the accumulated WWB strength, which contains most WWB characteristics, including the duration, occurrence frequency, strength, and spatial range of WWBs. The synoptic/climate systems that are directly related to WWBs show a wider spatial distribution in the positive PDO phase than in the negative PDO phase.