This study is an interesting one, but ultimately its messaging and perhaps methodologies might be misguided.

I agree with Referee #2, that, if the authors find an extreme case to be too limiting, that perhaps a range of injection mass rates should be explored.

One of the issues I have here, is that the "solar occultation" retrieval algorithm is a nonlinear inversion technique that requires an a priori under an extreme case and subsequently demonstrates the lack of efficacy of the technique under these circumstances. However, a proper solar occultation retrieval is a well-posed linear problem that does not require an a priori, so it's possible the solution would be better behaved.

Additionally, I would like to point out that the "zero transmission" problem very much depends upon the instrument's capabilities. While it is true that SAGE II could not see through the injected aerosol layer from Mt Pinatubo, ultimately what dictates this is the instrument's signal-to-noise ratio in its measurements and its maximum dynamic range. It is entirely possible, using currently available technology, to achieve meaningful measurements through much higher maximum line-of-sight optical depths than what SAGE II was capable of.

I think the high-level message is clear and unquestionable: Namely that an instrument can make measurements when the signal is not saturated. Since aerosol extinction is naturally lower at longer wavelengths, it is easier to measure under extreme loading conditions than at lower wavelengths. Of course, it is harder to measure under background or slightly elevated conditions. Generally speaking, there is value in aerosol measurements across the visible and IR spectra. I also believe it is worthwhile to discuss the potential limitations of different observation techniques under different atmospheric scenarios. However, ultimately the capability to make measurements depends upon the unique configuration and capability of the individual instrument. One can certainly perform such a study for an already existing instrument with known performance parameters, but one cannot make a blanket statement about a technique in general without testing the range of what is currently and technologically possible.