Earlier quoted context omitted.
That's true. Maybe when a buoy registers an "event", an "snapshot" of more fine-grained 15-sec data is recorded from all DART buoys? Edit. From this page: http://www.ndbc.noaa.gov/dart/dart.shtml > The system has two data reporting modes, standard and event. The system operates routinely in standard mode, in which four spot values (of the 15-s data) at 15-minute intervals of the estimated sea surface height are repor…
I see, thanks. But that rather sounds like the buoy itself is switching modes? From the look of all the plots, even the far-away ones, it rather looks to me like they have been remotely switched into event mode (with that 15s stuff being plotted at about the same time)? I guess I am really confused about the time stamps.
http://www.ndbc.noaa.gov/dart/dart.shtml
I think it's a combo of noise when that was activated (see the page above, describes exactly what it reports when it goes into that mode, etc) -- and then for the one that shows a substantial sea level rise, it's likely just the pressure since it's all pressure-based sea-level measurement "estimates". Guess I kind of thought it measured actual rise/fall of the buoy, or maybe used GPS or something, but makes a bit more sense that it's solely based on sea-floor pressure.