PDO And AMO Modulated the Interdecadal Change in Relationship of Summer Precipitation Between Western and Eastern Parts of Northern China

The summer precipitation over northern China generally presents an obvious dipole pattern, but the relationship between western northern China (WNC) and eastern northern China (ENC) has experienced a significant interdecadal change, with a significant positive correlation for the periods of 1920s–1940s (P1) and 1980s–2000s (P3), while a negative correlation for 1950s–1970s (P2). Further analyses reveal that the atmospheric circulation and water vapour transport anomalies triggered by the negative phase of Pacific Decadal Oscillation (PDO), coupling with an eastward-propagating Silk Road Pattern-like teleconnection stimulated by the Atlantic Multidecadal Oscillation (AMO), can jointly produce the favourable conditions for summer precipitation in ENC but unfavourable for WNC during P2, comparing with P1 and P3. This results in a dipole pattern of summer precipitation over northern China, leading to a negative correlation between precipitation in these two regions. During P1 and P3, precipitation anomalies in northern China mainly exhibit strong regional consistency, with primarily positive anomalies during P1 and negative anomalies during P3. However, the instability of the precipitation relationship during P3 is greater than those of P1 and P2, which may be attributed to the enhanced impact of the interdecadal variation of ENSO at the same period.