Dynamic Sea Level Variability Due to Seasonal River Discharge: A Preliminary Global Ocean Model Study

River discharge R is an important driver of the coastal ocean circulation. However, the influence of variable R effects on large-scale sea level zeta related to ocean dynamics is not well understood. We perform numerical experiments using a coarse (similar to 1 degrees) global ocean state estimate to quantify R effects on the seasonal cycle in dynamic zeta over the global ocean. Forcing by R drives substantial dynamic zeta signals (greater than or similar to 1 cm) on regional scales around major rivers (e.g., Amazon, Ganges, Brahmaputra, Irrawaddy, Ob, Lena, and Yenisei). Modeled zeta changes largely reflect halosteric (salinity) effects, which are partly affected by transport processes involving planetary waves and advection. The modeled zeta response to R is informative for interpreting zeta observations from satellite altimetry and tide gauges, explaining 10-20% of the regional-scale seasonal data variance around some major rivers. Future zeta studies should consider finer-resolution models and R forcing on nonseasonal time scales of relevance to climate.