The western Pacific oscillation (WPO) teleconnection pattern, which consists of a north‐ south meridional dipole structure with one center located over the Kamchatka Peninsula and another broad center of opposite sign covering portions of southeastern Asian and the western subtropical North Pacific, is one of the primary modes for low‐ frequency variability in conjunction with the North Pacific Oscillation (NPO) variability over the North Pacific. In this study, the specific role of the WPO teleconnection pattern in changing the connection between the mid ‐ latitude and tropical Pacific variability, as known as “Seasonal Footprinting Mechanism (SFM)”, is investigated. Analogous to the NPO variability, the boreal wintertime WPO atmospheric forcing is also able to generate the SFM process with stronger North Pacific Gyre Oscillation (NPGO) climate pattern. Two conditional cases regarding the NPO and WPO are composed in order to identify the specific role of the WP variability: when the NPO only occurs without WPO (i.e., NPO_only), and when the NPO coincides with WPO (i.e., NPO+WPO). Using a conditional composite analysis, it is found that the NPO and WPO atmospheric structures are not the same that the location of the WPO variability is significantly shifted westward compared to that of the NPO variability over the North Pacific. Furthermore, our analysis suggests that when the NPO and WPO simultaneously occur during the winter, a stronger NPGO mode is activated via changes in the surface net heat flux anomalies and equatorward moving anomalous warm temperature and westerly wind stress presumably caused by the weakened polar jet stream. These changes eventually result in the central Pacific‐ type El Niño structure as opposed the eastern Pacific‐ type El Niño structure generally induced by the NPO_only‐ related atmospheric forcing. Long‐ term coupled general circulation model analysis further verifies the observational results, showing a center‐ concentrated warming structure over the equatorial Pacific region in the following winter when the NPO coincides with the WPO in the previous winter.

1. INTRODUCTION

2. Data and methodology

2.1 Reanalysis data

2.2 Coupled general circulation model

2.3 Climatic index and methodology

3. NPO‐/ WPO‐induced Seasonal footprinting mechanism

4. Results

4.1 Comparison between NPO_only and NPO+WPO

4.2 Possible interpretations

4.3 Verification using coupled model

5. Summary and discussion