Abstract's details

Beyond 20 Hz: Deriving the necessity of increased posting rates from first principles

Frithjof Ehlers (Delft University of Technology, Netherlands)


Cornelis Slobbe (Geoscience and Remote Sensing, Delft University of Technology , Netherlands)

Event: 2022 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and Retracking

Presentation type: Type Oral

Contribution: PDF file


Empirical studies have outlined the advantages of 40 Hz and 80 Hz posting rates over 20 Hz in unfocused SAR altimetry (delay/Doppler processing), showing increased precision of sea surface heights and significant wave heights. However, the underlying reasons for this were unknown, as the theoretical Doppler resolution predicts that 20 Hz sampling should suffice.

In our work, we derive the need for posting rates on the order of 60 Hz for all current SAR altimeters from first principles. Hence, our findings are in line with earlier empirical studies that find best performance with 80 Hz in a comparison of 20, 40 and 80 Hz posting rates. The reasons for the increased effective along-track resolution can be fully explained in terms of the observation geometry. We will outline, which orbital parameters and processing settings influence the required posting rate most, and show the limits in which the anticipated along-track resolution of about 300 m is obtained.

Therefore, we hope to settle the ongoing debate in favor of 60 or 80 Hz SAR altimetry data. Our findings will also facilitate the planning of future SAR altimetry missions by making the required posting rates predictable.

Egido, A., Dinardo, S., Ray, C., 2021. The case for increasing the posting rate in delay/Doppler altimeters. Advances in Space Research 2, 930–936.
Dinardo, Salvatore. Techniques and Applications for Satellite SAR Altimetry over Water, Land and Ice. Ph.D. Thesis, Technische Universität, 2020. https://tuprints.ulb.tu-darmstadt.de/11343/.

Oral presentation show times:

Room Start Date End Date
Sala Grande Tue, Nov 01 2022,11:45 Tue, Nov 01 2022,12:00
Frithjof Ehlers
Delft University of Technology