De-aliasing of global high frequency barotropic motions in altimeter observations

The existence of high frequency (periods shorter than 10 days) energetic ba rotropic motions in the ocean is shown to lead to a large aliasing error in satellite altimetric observations. This error is most easily seen in the " trackiness" of 10-day altimetric maps, and commonly attributed to orbit err or. Fortunately, existing ocean general circulation models, when driven wit h twice-daily windstress fields, have considerable skill in predicting thes e motions. With improved forcing and models we can expect that in the futur e the alias can be largely suppressed by subtracting the model-generated hi gh frequency fields.