The Unstable Relationship Between the Precipitation Dipole Pattern in the Tibetan Plateau and Summer NAO

Substantial progress has been made in understanding the relationship between summer precipitation in the Tibetan Plateau (TP) and North Atlantic Oscillation (NAO), but impacts of the summer NAO on precipitation spatial pattern remain controversial. Using the long-term observational and reanalysis datasets, we have identified the intimate relationship between summer NAO and TP precipitation dipole pattern has been weakened since the late 1990s. Changes in regional atmospheric circulation induced by the asymmetrical wave propagation structure along the Eurasian continent are responsible for this weakened linkage. Further analyses revealed that the wave propagation anomalies are mainly induced by interdecadal change of summer NAO, which is attributed to the Atlantic multidecadal oscillation (AMO) variations. Moreover, the model simulations derived from the Geophysical Fluid Dynamics Laboratory (GFDL AM2.1) provide direct evidence to demonstrate that the AMO phase transition contributes to the unstable relationship between the summer NAO and precipitation dipole pattern in the eastern TP.