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onnoonno | 8 years ago

But that doesn't fit the data, either. The buoys all report something around the 9:45ish GMT mark. And 1500m/s would mean you reach Mendocino bay in California only about now or so. But have a look at the plot:

https://archive.fo/KsN8b

discuss

order

JorgeGT|8 years ago

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 reported at scheduled transmission times. When the internal detection software (Mofjeld) identifies an event, the system ceases standard mode reporting and begins event mode transmissions. In event mode, 15-second values are transmitted during the initial few minutes, followed by 1-minute averages. Event mode messages also contain the time of the initial occurrence of the event. The system returns to standard transmission after 4 hours of 1-minute real-time transmissions if no further events are detected.

The algorithm is described here: http://www.ndbc.noaa.gov/dart/algorithm.shtml

onnoonno|8 years ago

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.