Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Diagram of the algorithm and the variables contained in the dataset. A detailed diagram of the “open sea removing” algorithm in Step 1 is provided in Supplementary Figure 3. The specifics of the tracing algorithm used in Step 3 are described in Supplementary Text 1.
