The authors reported a new program for studying ship emission rates based on active remote sensing observations. Monitoring of ship emissions is usually carried out using in situ instruments on land, which depend on favourable wind conditions to transport the emitted substances to the measurement site. LP-DOAS measurements overcomes this shortcoming, and it realized real-time observation. However, there are some issues that need to be explained by the authors. After these minor corrections, this manuscript can be accepted by AMT.

1. The measured NO_x and SO₂ concentration and their emission rates should be validated with the measured data.
2. How to characterize the emission concentration and emission rates of NO_x and SO₂ at the ship chimney mouth?
3. During the analysis, the authors should quantify the impact of NO_x

The paper presented by Krause et al. reported a novel approach to derive ship emission rates of NO2, NOx and SO2 from LP-DOAS measurements combing a Gaussian plume model. It falls into the scope of AMT journal and well written. It can be accepted after addressing the following concerns.

Sect. 2.4.: Please describe generally the spectral analysis performance, e.g. how about the residual and the fit errors for each species? And any filtering applied for measured data before introducing the inversion program.

Sect. 2.4.1: If there were averagely 110 ship passages per day and >200 days measured data were analyzed, does it mean that only 30% success rate of the identification, e.g. 7402/(110*233). I think the authors could discuss more details about this or any explanations, which may be related the performance of the identification algorithm.

Sect. 2.4.2: If I do understand correctly, the authors used NO2/NOx ratio is provide by the in-situ measurement at river side, which is the aged plume rather than the fresh plume at the chimney. The difference of NO2/NOx ratio between fresh and aged plume will result in the larger uncertainties on the conversion of NO2 to NOx. In addition, the authors need to check the dependence of in-situ measured NO2/NOx on the ship position and wind direction.

Sect. 2.4.3: Any introduction for Equation 6 and relevant parameters? Moreover, considering the movements of ships and continuous emission of chimney, the detected plume by LP-DOAS at given time is not only the pure emission of the start point, but also mixed with the subsequent ship plume during the cruise. Did the authors consider this condition in the Gaussian plume model estimation? If not, at least the authors should take an example to evaluate the effects on the model evaluation.

Table 2, please specify the temperature of the used absorption cross section