A Method of Stacking AltiKa Repeat Cycle Data that May Reveal 75,000+ Possible Small Seamounts

摘要

The SARAL AltiKa radar altimeter measured sea surface height along ground tracks that were regularly revisited by repeating cycles. We devised an automated method of “stacking” the repeat cycles that aligns them to common positions along a model track, selects segments that pass quality criteria, removes the non‐geoidal height and height error from each repeat profile, and calculates the median height profile. This procedure reinforces geoid signals while reducing measurement noise and height signals produced by ocean dynamics. A seamount detection filter applied to the median profiles reveals 75,208 possible small seamounts along AltiKa ground tracks globally. Of these, 4824 are located over multibeam surveys. Seamount heights estimated by subtracting regional depths from the multibeam depths follow a Poisson statistical distribution that suggests at least 84% are less than 2?km tall. A 1?km along‐track sampling of the stacked repeat cycles is available from the National Centers for Environmental Information (NCEI) data repository. Plain Language Summary Our automated method of combining and processing sea surface height data collected by the AltiKa satellite that revisited the same ground tracks over time may reveal more than 75,000 possible small seamounts globally, and resolves seamounts down to 720?m tall. These detections may be useful for seamount census studies and for attempting to identify seamounts that may pose hazards to submarine navigation. The combined satellite profile data are available for download from the National Centers for Environmental Data (NCEI) data repository.