A physical mechanism of the precipitation dipole in the western United States based on PDO-storm track relationship

Abstract

It is known that the western United States (US) precipitation displays a north-south contrast, i.e., the so-called "precipitation dipole," during El Nin？o and La Nin？a winters. Furthermore, the Pacific Decadal Oscillation (PDO) has been known to modulate this precipitation dipole. However, the underlying physical mechanism regulating this modulation is not well understood. This study revisits previous studies and suggests a physical mechanism of precipitation dipole modulation based on the PDO-storm track relationship.