Short-period oceanic circulation: implications for satellite altimetry

Atmospherically forced, high-frequency oceanic variability is investigated using different configurations of an ocean general circulation model. At pe riods less than 20 days, the dynamic response of the sea surface to pressur e loading exceeds that due to wind stress, and is mostly barotropic. Energy at these periods aliases into satellite altimeter measurements of sea surf ace height (SSHT). The global variance of collinear (approximate to 10 day) differences of this modelled aliased SSHT is between (2 cm)(2) and (3.5 cm )(2), depending on the model configuration used. The local variance can rea ch (14 cm)(2) at some high latitude locations. We use the ocean model predi ctions to remove the high-frequency signals from TOPEX/Poseidon (T/P) obser vations. We obtain a global variance reduction in collinear differences of up to (2 cm)(2), about 7% of the T/P signal. Our model has difficulty in pr edicting the variability at periods less than 5 days.