Forcing of low-frequency ocean variability in the Northeast Pacific Chhak, K., E. Di Lorenzo, N. Schneider and P. Cummins Using an ocean model we examined the forcing mechanisms and underlying ocean dynamics of the PDO and NPGO in the northeast Pacific (NEP). It is found that the PDO and NPGO modes are each tied to a specific atmospheric forcing pattern. The PDO is related to the overlying Aleutian low, while the NPGO is forced by the North Pacific Oscillation. The above-mentioned climate modes captured in the model hindcast are reflected in satellite altimeter data. A budget reconstruction is used to study how the atmospheric forcing drives the SST and SSH anomalies. Results show that the basinwide SST and SSS anomaly patterns associated with each mode are shaped primarily by anomalous horizontal advection of mean surface temperature and salinity gradients via anomalous surface Ekman currents. This suggests a direct link of these modes with atmospheric forcing and the mean ocean circulation. AL_NPO_FORCING