Hs is significant wave height and Tz the mean zero upcrossing wave period. Hs:Tz scatterplots are widely used in offshore engineering in fatigue calculations (which require the joint distribution of individual wave heights and periods). They are also used as a visual quality check, and in wave energy applications to estimate wave power.
A scatterplot is a diagram illustrating the bivariate distribution of two parameters, such as significant wave height and zero-upcross wave period (Hs and Tz). Usually the diagram shows the data plotted on Cartesian co-ordinates. The individual pairs of data can be plotted, as in Fig.1, but more often, given a large number of pairs, the numbers in specified bins are plotted as in Fig.2 (or bins can be colour-coded). Bins here are 1 m by 1 second; they are often 0.5 m by 0.5 second and sometimes bin numbers are contoured. See for example Fig. 5.11 in Tucker & Pitt, 2001.
For a more detailed description of the process including the appropriate mathematical definitions see the Demonstration Products section of the Product User Guide.
Hs-Tz scatterplots have been generated for a selection of locations where in situ data are available for comparison. The initial set of locations is given below with hyperlinks to each image: