Association of tropical Pacific sea surface temperatures with the stratospheric Holton-Tan Oscillation in the Northern Hemisphere winter

Based on 45 years of the European Centre for Medium Range Weather Forecasting ERA‐40 reanalysis dataset and the NOAA Extended Reconstructed sea surface temperature (SST) data, the associated anomalies in the stratospheric Holton‐Tan Oscillation (HTO) with the tropical eastern Pacific SST in the Northern Hemisphere winter are investigated. It is found that the HTO, which is induced by equatorial quasi‐biennial oscillation (QBO), is significant in the cold SST phase, but the HTO becomes much weaker in the warm SST phase. The conventional QBO modulation on the planetary wave propagation in the stratosphere is only significant when the SST anomaly is cold in the tropical eastern Pacific. However, the modulation tends to be weak when the SST anomaly is warm. It is suggested that this difference may arise from the interaction between the tropical eastern Pacific SST‐ and the QBO‐associated planetary wave propagation.