Can we rank vessels using a relative received level metric, rather than an absolute source level?

[scottveirs]

Here's a sketch of a "delta" noise metric (the increase in received level relative to a local baseline) showing a series of peaks caused by passing ships over the course of a day:

Could the peak for a particular ship be meaningful for comparing the radiated noise to that from other vessels, other ships in the same class, or with the same ship on future passages of the same location?