Swimmer's Help

How to Understand Wave Measurements

(printable version)

How are waves measured?
Our wave data comes from our CODAR (Coastal Ocean RADAR) system, which is a series of antennas along the New Jersey Coast that measure the surface currents of the ocean using radio waves. In addition to measuring currents, each antenna site can calculate the height and period of waves approaching the beach. These wave measurements are actually made for waves about 1/2 mile off the coast.

For each site, we post the current wave height and period along with a graph showing the wave activity at each site for the previous week.

Wave Height - The wave height is essentially the size of the average incoming wave to the beach. Some waves will be bigger than this height, and many will be smaller. Since our wave measurements are made approximately 1/2 mile out from the beach. As a result of this, waves entering the surf zone will be slightly higher, and waves further offshore could be different.

Wave Period - The period represents the time in-between waves. Again, like the wave height, this is an average which means that the waves that wash ashore will really be more irregular. A shorter period means more frequent waves, and a longer period designates less frequent waves. Simply put, the shorter the period, the rougher and choppier the water will be, and visa versa.

What are the best waves for Surfing?
The best waves for surfers tend to be high waves with long periods. If the period is short (like less than 6 seconds) the waves are too close together for a good ride. The ocean is just too choppy to have a good time with your board.

You can also lean more about how CODAR works.
And you can read more about our Undersea Nodes.