The Relationship Between Atmospheric Rivers and the MJO

The goal of this study is to better understand the dynamics of atmospheric rivers (ARs) impinging on the west coast of North America. ARs have important roles in both local weather and global climate. The NCEP final analysis data set was used to diagnose several cases of ARs in recent decades. Diagnostic analyses indicate that strong meridional transport of moisture from tropical region to the mid-latitudes occurs through AR events causing remarkable precipitation. Analyzing tropical low frequency phenomena and their feedback to the mid-latitudes gives us further insight into the mechanism of ARs. A strong correlation exists between west coast ARs and the phase of the Madden-Julian Oscillation (MJO). In particular, these atmospheric rivers tend to occur when the active phase of the MJO is in the central to western Pacific. We are exploring the mechanisms behind this correlation.