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

Description

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.

Period	1 Nov 2022
Event title	Ocean Surface Topography Science Team meeting 2022
Event type	Other
Location	Venice, ItalyShow on map
Degree of Recognition	International