This slide shows some of the steps we use to get our estimates of Ri. For a given CTD station, we average U and V during that time period to get an average U and V as functions of depth.  From this we can find the shear (top right).  Here,  you can see that there is a large amount of shear between 160 - 200 m.

We then use the CTD data to calculate the buoyancy frequency (lower middle panel). We use the ration of N^2 to Shear^2 to estimate Ri (see previous slide).  Here you see that Ri is less than 1 in the area of large shear around 200 m.