A Reference Spectrum Model for Estimating Source Levels of Marine Shipping Based on Automated Identification System Data

Round 1

Reviewer 1 Report

This appears to be a solid analysis, and it demonstrates that the ability to detect and identify noise from ships associated by vessel type is improving.  The application of statistics and uncertainty analysis appear to be useful advances, and the identified future work follows from the results.  

Author Response

No comments from reviewer 1

Reviewer 2 Report

The topic tackled in this research paper is interesting and up-to-date. This paper helps grasp the importance of AIS in terms of its practical and scientific application. The authors proposed an updated reference spectrum model. As part of the JOMOPANS project, a widely used reference spectrum model (RANDI 3.1) was validated against statistics of monopole ship source level measurements from the Vancouver Fraser Port Authority-led (ECHO) Program. These validation comparisons resulted in a new reference spectrum model that retains the power-law dependence on speed and length but incorporates class-specific reference speeds and new spectrum coefficients that retain the power-law dependence on speed and length.

1. It will be great to see in literature IMO MEPC .1 /Circ. 833 Guidelines for the Reduction of Underwater Noise from Commercial Shipping to Address Adverse impacts on Marine Life.
2. Which model of calibrated hydrophones has been used for measurement? It will be better to see previous research even in the introduction part or before the main methodology.
3. In the lines between 212 to 215 could you provide some evidence or reference for the assumption that dredgers maintain 3 knots speed while dredging.
4. In the lines between 441 and 448 please provide a clear reference for the following statements: AIS carriage requirements broadcasts often contain errors in vessel length, ship type ID, and speed, and many smaller vessels (typically under 300 gross tonnes) do not broadcast on AIS at all. 

Author Response

1. It will be great to see in literature IMO MEPC .1 /Circ. 833 Guidelines for the Reduction of Underwater Noise from Commercial Shipping to Address Adverse impacts on Marine Life.

Thank you for the suggestion. We have added a reference to these guidelines in the introductory section of our paper.

1. Which model of calibrated hydrophones has been used for measurement? It will be better to see previous research even in the introduction part or before the main methodology.

We have added more information regarding the hydrophones and acoustic recorders to section 2.1. We have also added some citations regarding prior research into the effects of shipping noise on marine life to the introduction.

1. In the lines between 212 to 215 could you provide some evidence or reference for the assumption that dredgers maintain 3 knots speed while dredging.

This is based on the dredger speeds observed in reference 19. We have revised the text to clarify this point.

1. In the lines between 441 and 448 please provide a clear reference for the following statements: AIS carriage requirements broadcasts often contain errors in vessel length, ship type ID, and speed, and many smaller vessels (typically under 300 gross tonnes) do not broadcast on AIS at all. 

We have added two additional references in support of this statement in the discussion.