The paper is nearly ready for publication. Two minor changes are required based on re-read by the reviewers.

(1) The conclusion about "anomalously high CBE" below the OMZ is based on the "database" of Hartnett et al 1998. The reality is that at these low O2 values (and estimated OETs), Hartnett et al found CBE to be hugely variable. In other words, their relationship between CBE and O2 (or OET) has very large error bars at low O2. In short, (anomalously) high CBE immediately below the OMZ (and many would refer to these sites as WITHIN the OMZ!), or indeed at other sites with low but non-zero O2 levels, is not uncommon (even if it is real). The authors need to address/acknowledge this.

(2) Please replace the word "discretize" with another term... it is not clear for all readers.

Nice work!