Role of synoptic eddies on low-frequency precipitation variation

Abstract

This study investigates a contribution of the synoptic-eddy moisture feedback to low-frequency precipitation variability. On one hand, synoptic-eddy moisture flux is systematically controlled by monthly mean flow. On the other hand, anomalous synoptic-eddy moisture fluxes can positively contribute to low-frequency precipitation anomalies. The eddy moisture convergence exhibits a considerable magnitude compared to that of precipitation variability, so their ratio is more than 0.5 over several extratropical regions. In addition, the moisture convergence induced by synoptic eddies is significantly correlated to precipitation variability. We also showed eddy-induced moisture convergence plays an important role in the variability of PNA (Pacific North America Pattern)-related precipitation and polar precipitation.