Effects of the Pacific Decadal Oscillation on the Characteristics of Two Types of El Nino under Possible Climate Change

The effect of the Pacific Decadal Oscillation (PDO) phase on the intensity and localization of anomalies in sea surface temperature and meteorological parameters associated with two types of El Nino is analyzed. The analysis is based on reanalysis and CMIP5 model data for modern and future climate (RCP 8.5 scenario). It is found that El Nino does not exhibit robust intensification during the positive PDO phase, as mentioned in the previous studies, but the PDO influence is highly dependent on the El Nino type. The canonical El Nino is intensified during the positive PDO phase, while, on the contrary, El Nino Modoki weakens. In future climate the interaction between PDO and El Nino is modified, but the significant intermodel spread does not allow an unambiguous determination of trends.