sydney directional wave height & period

[Billwha]

can anyone help me better understand the bouy data? correct me if i'm wrong

just simple questions I guess but I find it a little difficult to understand

1. wave direction . . . 180 degree's is a due south swell right?, so 135 is due south east, and 90 east?

2. Hsig & Hmax . . . . the Hsig is sets, the Hmax the biggest wave of the sets?

3. what does TP1 mean . . . . is that the duration of the defined sets of Hsig?

4. Is a 2 metre Hsig with a 12 second Tsig (provided no winds, direction favourable etc) gonna most of the time produce a decent wave when it arrives at the beach?

5. wave power increases with increased period because . . . . . . ? less water in front of the wave so it forms better?!? cause it's shallower?

cheers for any info

[thermalben]

Hi Billwha

(1) - spot on

(2) - Hsig is the average of the highest 1/3 of all the wave recorded in a 26 minute sampling period. Effectively, this means that every single wave is recorded, and the top 1/3 waves are then averaged to provide a figure that best represents the overall ocean state. Hmax is the single largest wave to pass beneath the buoy during this time frame.

(3) - Tp = Peak period. This is the longest wave period recorded within the sampling period. Tz = zero crossing, which is the mean period of all of the waves (depending on the methods used.. it's sometimes the average period of the highest 1/3 waves.. ie Hsig)

(4) most of the time. But not always. Depends on lots of other factors.

(5) increased swell period means that the swell is travelling at a faster speed (this adds to quality as faster waves will generally be steeper, and will usually react quicker with reefs and shoals). It also penetrates deeper towards the ocean floor, so swells with larger periods react to the bathymetry better (ie wrap into points, bays, harbours etc).

Just a quick overview on each of them - hope that helps.

Ben

[Billwha]

yep does, cheers ben