Improving the DAC de-aliasing model by combining with sub-monthly GRACE gravity data
Event: 2019 Ocean Surface Topography Science Team Meeting
Session: Quantifying Errors and Uncertainties in Altimetry data
Presentation type: Type Oral
Contribution: PDF file
The Dynamic Atmospheric Correction (DAC) can be applied to Jason altimetry data to reduce the aliasing impact of high-frequency inverted barometer and dynamic ocean signals. As imperfections in the DAC will result in longer-period aliased errors in the ultimate sea surface height estimates, it is crucial to make this model as accurate as possible. We attempt to improve upon the DAC’s Mog2D ocean model by combining with bottom pressure estimates from a near-daily GRACE “swath-style” gravity solution. We compare with Jason sea surface heights to localize those places and frequency regimes where the GRACE series is demonstrably better than the original DAC model. We then create a new altimetry de-aliasing product out of the combination of GRACE and Mog2D, with the current model dominating at the higher frequencies and in the equatorial regions, but GRACE bottom pressures becoming relevant at longer sub-monthly periods and particularly in the southern ocean.