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Thread: 44009

  1. #1
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    44009

    What's up with the buoy? No wind direction for months, now speed is gone? Thoughts?

  2. #2
    Quote Originally Posted by Db2k5 View Post
    What's up with the buoy? No wind direction for months, now speed is gone? Thoughts?
    I KNOW !!! im so mad, not only are all the wind readings gone, but also swell height, and swell period are gone too! probably some other things i dont pay attention to also.

    They used to show the differences between the period and height of the wind waves vs. the swells. Now all they show is one average "wave height", and "average period".

    Correct me if im wrong,.... but arn't these readings practically useless if more than one or two swell trains are in the water!? It could be averaging W wind chop 20 miles offshore with a SE hurricane swell.
    Last edited by epidemicepic; Nov 16, 2008 at 09:17 PM.

  3. #3
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    Didn't you hear?

    The government dedicated all of our money elsewhere.

  4. #4
    Quote Originally Posted by epidemicepic View Post
    I KNOW !!! im so mad, not only are all the wind readings gone, but also swell height, and swell period are gone too! probably some other things i dont pay attention to also.
    I dont think a buoy can register a "swell" height without knowing the wind conditions at the buoy. Technically, swell is waves that aren't being generated by the local wind conditions so if the bouy isnt reading wind speed and direction, it cant differentiate between locally generated waves, and swell from elsewhere.

    I'd really like it if Micah could elaborate on this

  5. #5
    Quote Originally Posted by South Bethany View Post
    I dont think a buoy can register a "swell" height without knowing the wind conditions at the buoy. Technically, swell is waves that aren't being generated by the local wind conditions so if the bouy isnt reading wind speed and direction, it cant differentiate between locally generated waves, and swell from elsewhere.

    I'd really like it if Micah could elaborate on this
    hmmm... i dunno how buoys analyze data, but assuming that they differentiate between swells by using local wind conditions you would be right...

    For some reason i always thought that the buoy would be able to tell the difference (between swells) from the analysis of wave period data, or the "swell energy profile". For example, if you have a bunch of waves in the 4 foot range at 5-6 second periods, it would put these waves in a different class (windwaves) from those averaging 6-7 feet and 12-15 second periods (swell).

    I really have no idea which way a buoy works, anyone know for sure ??
    Last edited by epidemicepic; Nov 22, 2008 at 11:07 PM.

  6. #6
    Quote Originally Posted by epidemicepic View Post
    For example, if you have a bunch of waves in the 4 foot range at 5-6 second periods, it would put these waves in a different class (windwaves) from those averaging 6-7 feet and 12-15 second periods (swell).
    I thought that too, until i noticed that on some small days with some east wind the buoy would read 4 foot 4 second wind wave and basically no swell, then after the east winds died for like an hour or two the bouy would ready basically no wind wave and 2 foot 5 second "swell" for a few hours and it kind of dawned on me that as soon as the wind died, the little east wind wave, became little east swell, even if it is short period.

  7. #7
    I am pretty sure that a buoy will take swell size and divide it by wind speed. Then add that to the swell period. Multiplying that by barometric pressure. And finally taking the square root of the speed of light, therefore giving you the meaning of life.

  8. #8
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    the buoys have wave guages, which record the 360 degrees of spectral wave energy. Statistical methods, then generate a significant wave height (highest 1/3 of all the waves) and dominant wave period. Also, often the statistics will differentiate between wind waves and swell.

    It looks like NOAA is defining wind waves by swell which is at least partially influenced by the local wind... So, perhaps this is why the swell height differentiation is not being calculated. I would have thought it was more of a swell height to period ratio like epidemicepic had suggested, but it looks like the local wind is used in the equation as well.

    When there are multiple swells in the water, you should look at the swell break up in the Swell Plots / Surf Plots to get a good idea of how the individual swells are breaking down. Often, when there are multiple swells, the NDBC swell height can still be misleading.