Please carefully revise your paper by positively adressing the following points:

rev. #1:
There is one pending issue (and 2 minor suggestions regarding Fig. 1):
* Use of two methods and the presentation of the two methods:
I have no problem with the authors using slightly different derivations of the Gaussian plume. However, I think the authors need to rephrase the abstract because, as currently written, it strikes this reviewer as misleading. Based on a reading of the abstract I would assume the authors used two independent methods of estimating the flow rate and found them to be consistent: "two different methods were used to calculate the flow rate: 1. Gaussian plume fitting in the vertical and 2. Direct integration of the plume. When both methods were used, they compared within 6% of each other". The abstract should be rephrased. I would suggest calling the methods something like "Gaussian plume" and "Gaussian plume (fully mixed)". This would also mean changing the legend in Figure 6 and the subsection titles in Section 3.

* Minor suggestions regarding Figure 1:
- There is a typo in Figure 1, the authors have misspelled "The" in the final sentence of the caption.
- I also suggest that the authors add the other platforms in the region (Shearwater, Franklin, Judy, and Jasmine from Fig. 3) to Figure 1. This would help the reader get a feel for the region before going into the analysis. I incorrectly assumed that the Elgin platform was the only platform in the region when I was first going through the manuscript.

rev. #2:
It is helpful to see in Fig. 7 of the revised manuscript which data originate from which flight. This makes it clear that there is a significant spatial dependence of the composition of the plume, which has not been acknowledged by the authors.

In lines 37-40 of the manuscript the authors note an anticorrelation between NMHC and methane mixing ratios but claim (without any quantitative basis) that this may not be statistically significant. In fact, it is quite clear that the mixing ratios of the heavier hydrocarbons (propane, butane and pentane) all fall systematically more rapidly than those of excess methane and ethane, over the entire range of methane mixing ratio. This is either a result of an annular composition profile of the plume, or (more likely) of deposition of the heavier fractions onto the cold water surface along the length of the plume. This is so obvious that some comment is required in order to properly characterise the results.

Acknowledging this has no implications for the flow rate estimates in the paper, which are based on the methane data alone. However, it would not be proper to ignore the fact that the physical situation is more complex than the simple model description used in the paper.

Thank you for peforming the final corrections. The paper is now ready for final publication.
Sincerely,
Ralf Sussmann