Bottom-pressure signature of annual baroclinic Rossby waves in the northeast tropical Pacific Ocean

The annual cycle in bottom pressure (p(b)) in the northeast tropical Pacific Ocean (NTPO) is studied. Focus is on a zonal section along 12 degrees N between 105 degrees W and 145 degrees W that is characterized by a strong annual cycle in sea level from satellite altimetry. Estimates of p(b) from the Gravity Recovery and Climate Experiment (GRACE), a state estimate produced by the Estimating the Circulation and Climate of the Ocean (ECCO) consortium, and a linear Rossby wave model (LRWM) are used. The GRACE NTPO p(b) annual cycle shows amplitudes as large as 1 cm water equivalent. The GRACE data also evidence westward propagation that is consistent with the behavior of long mode-1 Rossby waves at this latitude, with phase increasing from east to west at a rate of approximate to 0.34 m s(-1). The ECCO and LRWM p(b) estimates corroborate the notion that GRACE reveals the p(b) signature of annual Rossby waves driven by interior wind stress curl and possibly damped by frictional processes. Results have implications for attempts to constrain global ocean mass using a single point mooring.