[Paddlewise] Waves/Pierson

John,

Prof. Willard Pierson introduced the use of statistics for reporting wave
conditions back in the 1940’s. Bill has been a real contributor to
oceanography for decades, with big time contributions to guiding the use of
radars in space to measure ocean waves and near surface winds. He still
conducts research using the latest and most advanced satellite data sets,
with particular interest in the new systems that are being used to study
rain storms in the tropics. Several of Pierson’s students have had highly
noteworthy careers….

Your explanation of the difference between wave height and wave conditions
help to explain some of Pierson’s  ideas and mathematical models. Pierson is
one of my heroes… he resides near New York… likes Chinese food and smokes a
pipe.

Bye bye bliven
=========================
>From John Winters:

<snipped somewhat randomly>

>One should not confuse the way wave conditions are reported versus the way
individual waves are measured.

> The measurement of wave height is the distance from trough to crest or
twice the amplitude.

>The reporting of wave conditions - average wave height, significant wave
heights, etc. - are based upon many waves not individual waves.

>One should not assume that because wave heights are reported as being 1
meter that they will in fact be 1 meter. They will cover a range some being
much higher and some much lower.

----------------------------------------------------------------------------
---
>Height is but one factor. Perhaps of greater interest to paddlers will be
ratio of length to height. It is the steep breaking waves that cause
capsizes not the long gentle old rollers. Generally for waves of the same
height new waves are steeper than old waves and waves in shallow water are
steeper than waves in deep water.

----------------------------------------------
>One can put this information to good use. You can avoid steep waves by
staying offshore where waves are unaffected by shoaling water and can pay
heed to changing weather conditions that will create new wind driven waves.


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